Sulfonium salt having polymerizable anion, polymer, resist composition, and patterning process

[0001] This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2006-292023 filed in Japan on Oct. 27, 2006, the entire contents of which are hereby incorporated by reference.

[0002] This invention relates to (1) a polymer capable of generating a sulfonic acid in response to high-energy radiation or heat, (2) a sulfonium salt having a polymerizable anion useful as a photoacid generator or a monomer for sulfonic acid polymers, (3) a polymer comprising the sulfonium salt as a monomer, (4) a resist composition comprising the polymer, and (5) a patterning process using the resist composition.

[0003] While a number of recent efforts are being made to achieve a finer pattern rule in the drive for higher integration and operating speeds in LSI devices, DUV and VUV lithography is thought to hold particular promise as the next generation in microfabrication technology. In particular, photolithography using an ArF excimer laser as the light source is thought requisite to the micropatterning technique capable of achieving a feature size of 0.13 μm or less.

[0004] The ArF lithography started partial use from the fabrication of 130-nm node devices and became the main lithography since 90-nm node devices. Although lithography using F₂ laser (157 nm) was initially thought promising as the next lithography for 45-nm node devices, its development was retarded by several problems. A highlight was suddenly placed on the ArF immersion lithography that introduces a liquid having a higher refractive index than air (e.g., water, ethylene glycol, glycerol) between the projection lens and the wafer, allowing the projection lens to be designed to a numerical aperture (NA) of 1.0 or higher and achieving a higher resolution. See Journal of Photopolymer Science and Technology, Vol. 17, No. 4, p 587 (2004).

[0005] In the photolithography using an ArF excimer laser (wavelength 193 nm) as the light source, a high sensitivity resist material capable of achieving a high resolution at a small dose of exposure is needed to prevent the degradation of precise and expensive optical system materials. Among several measures for providing high sensitivity resist material, the most common is to select each component which is highly transparent at the wavelength of 193 nm. For example, polyacrylic acid and derivatives thereof, norbornene-maleic anhydride alternating copolymers, polynorbornene, ring-opening metathesis polymers, and hydrogenated ring-opening metathesis polymers have been proposed as the base resin. This choice is effective to some extent in that the transparency of a resin alone is increased.

[0006] Studies have also been made on photoacid generators. In prior art chemically amplified resist compositions for lithography using KrF excimer laser, photoacid generators capable of generating alkane- or arene-sulfonic acids are used. However, the use of these photoacid generators in chemically amplified resist compositions for ArF lithography results in an insufficient acid strength to scissor acid labile groups on the resin, a failure of resolution or a low sensitivity. Thus these photoacid generators are not suited for the fabrication of microelectronic devices.

[0007] For the above reason, photoacid generators capable of generating perfluoroalkanesulfonic acids having a high acid strength are generally used in ArF chemically amplified resist compositions. These photoacid generators capable of generating perfluoroalkanesulfonic acids have already been developed for use in the KrF resist compositions. For instance, JP-A 2000-122296 and U.S. Pat. No. 6,048,672 (or JP-A 11-282168) describe photoacid generators capable of generating perfluorohexanesulfonic acid, perfluorooctanesulfonic acid, perfluoro-4-ethylcyclohexanesulfonic acid, and perfluorobutanesulfonic acid. JP-A 2002-214774, US Patent Application Publication 2003-0113659 A1 (JP-A 2003-140332), and US Patent Application Publication 2002-0197558 A1 describe novel photoacid generators capable of generating perfluoroalkyl ether sulfonic acids.

[0008] Among these, perfluorooctanesulfonic acid and homologues thereof (collectively referred to as PFOS) are considered problematic with respect to their non-degradability and biological concentration in the environment. Manufacturers made efforts to develop partially fluorinated alkane sulfonic acids having a reduced degree of fluorine substitution as the replacement to PFOS. For instance, JP-A 2004-531749 describes the development of α,α-difluoroalkanesulfonic acid salts from α,α-difluoroalkene and a sulfur compound and discloses a resist composition comprising a photoacid generator which generates such sulfonic acid upon exposure, specifically di(4-tert-butylphenyl)iodonium 1,1-difluoro-2-(1-naphthyl)-ethanesulfonate. JP-A 2004-2252 describes the development of α,α,β,β-tetrafluoroalkanesulfonic acid salts from α,α,β,β-tetrafluoro-α-iodoalkane and sulfur compound and discloses a photoacid generator capable of generating such a sulfonic acid and a resist composition comprising the same. JP-A 2002-214774 discloses such photoacid generators having difluorosulfoacetic acid alkyl esters and difluorosulfoacetic acid amides although their synthesis method is lacking. Furthermore, JP-A 2005-266766 discloses a photosensitive composition comprising a compound capable of generating a partially fluorinated alkane sulfonic acid having a sulfonylamide structure derived from perfluoroalkylene disulfonyl difluoride.

[0009] In forming fine feature size patterns with a pitch of less than 200 nm, the problem of pattern density dependency, that is, the size difference between isolated and grouped patterns having different optical contrast becomes significant. Using a photoacid generator capable of generating an acid with low diffusion, the problem of pattern density dependency can be overcome to some extent, but not to a satisfactory extent. While the resist composition is required to achieve a further reduction of the pattern rule as well as a good balance of sensitivity, substrate adhesion, and etching resistance, it is also required to ameliorate the pattern density dependency fundamentally without sacrifice of resolution.

[0010] Under the circumstances, it was proposed to form a polymer from an acryloyloxyphenyl diphenyl sulfonium salt as a monomer for enhancing sensitivity (as described in JP-A 4-230645) and to incorporate the monomer into a polyhydroxystyrene resin for improving the line edge roughness of this base resin (as described in JP-A 2005-84365). However, since the sulfonium salt is bonded at its cation side to the polymer, the sulfonic acid generated upon exposure to high-energy radiation is not different from the sulfonic acids generated by conventional photoacid generators, which is unsatisfactory in view of the outstanding problem. Also, sulfonium salts having an anion side incorporated into the polymer backbone such as polystyrenesulfonic acid are disclosed as effective in enhancing sensitivity or improving resist pattern profile (Japanese Patent No. 3,613,491). The acids generated thereby are arenesulfonic and alkylsulfonic acid derivatives which have too low an acid strength to sever acid labile groups, especially acid labile groups in ArF chemically amplified resist compositions.

[0011] With respect to the immersion lithography, some problems arise from minute water droplets which are left on the resist and wafer after the immersion exposure. They can often cause damages and defects to the resist pattern profile. The resist pattern after development can collapse or deform into a T-top profile. There exists a need for a patterning process which can form a satisfactory resist pattern after development according to the immersion lithography.

[0012] The lithography techniques which are considered promising next to the ArF lithography include electron beam (EB) lithography, F₂ lithography, extreme ultraviolet (EUV) lithography, and x-ray lithography. In these techniques, exposure must be done in vacuum or reduced pressure, which allows the sulfonic acid generated during exposure to volatilize, failing to form a satisfactory pattern profile. The sulfonic acid volatilized can damage or stain the exposure system.

[0013] An object of the present invention is to provide (1) a sulfonium salt having a polymerizable anion useful as a monomer for forming a base resin in resist compositions, (2) a polymer derived from the sulfonium salt, (3) a resist composition comprising the polymer, which composition exhibits a high resolution and improved mask fidelity when processed by the photolithography using high-energy radiation, typically ArF excimer laser radiation as the light source, and (4) a patterning process using the resist composition.

[0014] The inventors have found that a sulfonium salt having a polymerizable anion represented by the general formula (1), shown below, can be produced from reactants which are commercially available and relatively inexpensive; that a polymer capable of generating recurring units of sulfonic acid having the general formula (1a) in response to high-energy radiation, heat or the like, and a resist composition comprising as a base resin a polymer comprising recurring units of a sulfonium salt having a polymerizable anion exhibit good characteristics including exposure dose dependency, pattern density dependency, and mask fidelity; and that the polymer is very effective as a resist material in precise micropatterning.

[0015] Thus the invention provides a sulfonium salt having a polymerizable anion, a polymer, a resist composition, and a patterning process, as defined below.

[0016] In a first aspect, the invention provides a polymer capable of generating a sulfonic acid in response to high-energy radiation or heat, said sulfonic acid comprising recurring units of the general formula (1a):

[0017]
wherein R¹ is hydrogen, fluorine, methyl or trifluoromethyl.

[0018] In a second aspect, the invention provides a sulfonium salt having a polymerizable anion, represented by the general formula (1):

[0019]
wherein R¹ is hydrogen, fluorine, methyl or trifluoromethyl, R², R³ and R⁴ are each independently a substituted or unsubstituted, straight or branched alkyl, alkenyl or oxoalkyl group of 1 to 10 carbon atoms, or a substituted or unsubstituted aryl, aralkyl or aryloxoalkyl group of 6 to 18 carbon atoms, or at least two of R², R³ and R⁴ may bond together to form a ring with the sulfur atom.

[0020] In a third aspect, the invention provides a polymer comprising recurring units of the general formula (2):

[0021]
wherein R¹ to R⁴ are as defined above. In a preferred embodiment, the polymer may further comprise recurring units of at least one selected from the general formulae (3) to (6):

[0022]
wherein R¹ is as defined above, R⁶ and R⁷ are each independently hydrogen or hydroxyl, X is an acid labile group, Y is a lactone structure-containing substituent group, and Z is hydrogen, a fluoroalkyl group of 1 to 15 carbon atoms or a fluoroalcohol-containing substituent group of 1 to 15 carbon atoms. In another preferred embodiment, the polymer may further comprise recurring units of at least one selected from the general formulae (7) to (10):

[0023]
wherein R¹ and X are as defined above, and G is an oxygen atom or carbonyloxy group (—C(═O)O—).

[0024] In a fourth aspect, the invention provides a resist composition comprising the polymer defined above as a base resin; or a resist composition comprising the polymer defined above and another polymer free of units of formula (2) as a base resin. In a preferred embodiment, the resist composition may further comprise a surfactant which is insoluble in water and soluble in an alkaline developer.

[0025] In a fifth aspect, the invention provides

[0026] a pattern forming process comprising the steps of applying the resist composition defined above onto a substrate to form a coating, heat treating the coating and exposing it to high-energy radiation through a photomask, and optionally heat treating the exposed coating and developing it with a developer;

[0027] a pattern forming process comprising the steps of applying the resist composition defined above onto a substrate to form a resist coating, heat treating the resist coating, applying onto the resist coating a protective coating which is insoluble in water and soluble in an alkaline developer, exposing the coated substrate to high-energy radiation from a projection lens through a photomask while holding water between the substrate and the projection lens, optionally heat treating, and developing with a developer; or

[0028] a pattern forming process comprising the steps of applying the resist composition defined above onto a substrate to form a coating, heat treating the coating, imagewise writing on the coating with an electron beam, optionally heat treating the coating, and developing it with a developer.

[0029] It is noted that the resist composition of the invention can be applied to the immersion lithography. The immersion lithography involves prebaking a resist film and exposing the resist film to light through a projection lens with a liquid medium interposed between the resist film and the projection lens. The ArF immersion lithography generally uses deionized water as the immersion medium. This technology, combined with a projection lens having a numerical aperture of at least 1.0, is important for the ArF lithography to survive to the 65 nm node and forth, with a further development thereof being accelerated.

[0030] The resist composition of the invention allows the feature size of the pattern after development to be reduced by various shrinkage techniques. For example, the hole size can be shrunk by such known techniques as thermal flow, RELACS, SAFIRE, and WASOOM. More effective shrinkage of hole size by thermal flow is possible particularly when the inventive polymer is blended with a hydrogenated cycloolefin ring-opening metathesis polymer (ROMP) having a low Tg.

[0031] Since the sulfonium salt having a polymerizable anion according to the invention has fluorine atoms at α- and γ-positions relative to sulfonic acid, it generates a very strong sulfonic acid upon exposure to high-energy radiation so that it facilitates effective scission of acid labile groups in chemically amplified resist compositions. The sulfonium salt is thus useful as a monomer from which a base resin for use in radiation-sensitive resist compositions is derived. A radiation-sensitive resist composition comprising the polymer of the invention as a base resin exhibits a high resolution and is improved in pattern density dependency and exposure margin when processed by photolithography. The polymer is advantageously used as a resist material in precise micropatterning. In the practice of ArF immersion lithography, the polymer prevents leach-out in water and also minimizes the influence of water left on the wafer, restraining defects from forming. In the disposal of resist-containing waste liquid after the device fabrication, (meth)acrylic ester moieties are hydrolyzable under basic conditions so that the polymers can be converted into less accumulative compounds of lower molecular weight. In the disposal by combustion, the polymers are more combustible because of a low degree of fluorine substitution.

[0034] As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0035] The notation (Cn-Cm) means a group containing from n to m carbon atoms per group.

[0036] The term “high-energy radiation” is intended to encompass UV, deep UV, electron beam, EUV, x-ray, excimer laser, γ-ray and synchrotron radiation.

[0037] The polymer of the invention is capable of generating a sulfonic acid in response to high-energy radiation or heat. The sulfonic acid generated comprises recurring units of the general formula (1a):

[0038]
wherein R¹ is a hydrogen atom, fluorine atom, methyl group or trifluoromethyl group.

[0039] The sulfonium salt having a polymerizable anion according to the invention is represented by the general formula (1).

[0040]
Herein R¹ is hydrogen, fluorine, methyl or trifluoromethyl, R², R³ and R⁴ are each independently a substituted or unsubstituted, straight or branched alkyl, alkenyl or oxoalkyl group of 1 to 10 carbon atoms, or a substituted or unsubstituted aryl, aralkyl or aryloxoalkyl group of 6 to 18 carbon atoms, or any two or more of R², R³ and R⁴ may bond together to form a ring with the sulfur atom.

[0041] In formula (1), R², R³ and R⁴ are each independently a substituted or unsubstituted, straight or branched C₁-C₁₀ alkyl, alkenyl or oxoalkyl group, or a substituted or unsubstituted C₆-C₁₈ aryl, aralkyl or aryloxoalkyl group, or any two or more of R², R³ and R⁴ may bond together to form a ring with the sulfur atom. Specifically, suitable alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl. Suitable alkenyl groups include, but are not limited to, vinyl, allyl, propenyl, butenyl, hexenyl, and cyclohexenyl. Suitable oxoalkyl groups include, but are not limited to, 2-oxocyclopentyl, 2-oxocyclohexyl, 2-oxopropyl, 2-oxoethyl, 2-cyclopentyl-2-oxoethyl, 2-cyclohexyl-2-oxoethyl, and 2-(4-methylcyclohexyl)-2-oxoethyl. Suitable aryl groups include, but are not limited to, phenyl, naphthyl and thienyl; 4-hydroxylphenyl; alkoxyphenyl groups such as 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, and 3-tert-butoxyphenyl; alkylphenyl groups such as 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 4-tert-butylphenyl, 4-n-butylphenyl, and 2,4-dimethylphenyl; alkylnaphthyl groups such as methylnaphthyl and ethylnaphthyl; alkoxynaphthyl groups such as methoxynaphthyl and ethoxynaphthyl; dialkylnaphthyl groups such as dimethylnaphthyl and diethylnaphthyl; and dialkoxynaphthyl groups such as dimethoxynaphthyl and diethoxynaphthyl. Suitable aralkyl groups include, but are not limited to, benzyl, 1-phenylethyl, and 2-phenylethyl. Suitable aryloxoalkyl groups include, but are not limited to, 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl. When any two or more of R², R³ and R⁴ bond together to form a cyclic structure with the sulfur atom, exemplary cyclic structures are shown below.

[0042]
Herein R⁴ is as defined above.

[0043] Illustrative examples of the sulfonium cation include triphenylsulfonium, 4-hydroxyphenyldiphenylsulfonium, bis(4-hydroxyphenyl)phenylsulfonium, tris(4-hydroxyphenyl)sulfonium, 4-tert-butoxyphenyldiphenylsulfonium, bis(4-tert-butoxyphenyl)phenylsulfonium, tris(4-tert-butoxyphenyl)sulfonium, 3-tert-butoxyphenyldiphenylsulfonium, bis(3-tert-butoxyphenyl)phenylsulfonium, tris(3-tert-butoxyphenyl)sulfonium, 3,4-di-tert-butoxyphenyldiphenylsulfonium, bis(3,4-di-tert-butoxyphenyl)phenylsulfonium, tris(3,4-di-tert-butoxyphenyl)sulfonium, diphenyl(4-thiophenoxyphenyl)sulfonium, 4-tert-butoxycarbonylmethyloxyphenyldiphenylsulfonium, tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium, (4-tert-butoxyphenyl)bis(4-dimethylaminophenyl)sulfonium, tris(4-dimethylaminophenyl)sulfonium, 2-naphthyldiphenylsulfonium, (4-hydroxy-3,5-dimethylphenyl)diphenylsulfonium, (4-n-hexyloxy-3,5-dimethylphenyl)diphenylsulfonium, dimethyl(2-naphthyl)sulfonium, 4-hydroxyphenyldimethylsulfonium, 4-methoxyphenyldimethylsulfonium, trimethylsulfonium, 2-oxocyclohexylcyclohexylmethylsulfonium, trinaphthylsulfonium, tribenzylsulfonium, diphenylmethylsulfonium, dimethylphenylsulfonium, 2-oxo-2-phenylethylthiacyclopentanium, diphenyl-2-thienylsulfonium, 4-n-butoxynaphthyl-1-thiacyclopentanium, 2-n-butoxynaphthyl-1-thiacyclopentanium, 4-methoxynaphthyl-1-thiacyclopentanium, and 2-methoxynaphthyl-1-thiacyclopentanium. Preferred cations are triphenylsulfonium, 4-tert-butylphenyldiphenylsulfonium, 4-tert-butoxyphenyldiphenylsulfonium, tris(4-tert-butylphenyl)sulfonium, tris(4-tert-butoxyphenyl)sulfonium, and dimethylphenylsulfonium.

[0044] Illustrative examples of the compounds having formula (1) are given below.

[0045]

[0046] Understandably, the sulfonium salts having a polymerizable anion represented by formula (1) according to the invention are exemplary while iodonium salts, ammonium salts and analogous salts having a polymerizable anion can be synthesized by a similar technique as in the invention and are applicable to the polymers, resist compositions and patterning process to be described later.

[0047] Illustrative examples of iodonium cations include diphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-(1,1-dimethylethyl)phenyl)iodonium, bis(4-(1,1-dimethylpropyl)phenyl)iodonium, and (4-(1,1-dimethylethoxy)phenyl)phenyliodonium. Illustrative examples of ammonium salts include tertiary ammonium salts such as trimethylammonium, triethylammonium, tributylammonium, and N,N-dimethylanilinium, and quaternary ammonium salts such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium. An iodonium salt having a polymerizable anion as described above and a polymer comprising recurring units derived therefrom may be used as an agent having a photo-acid-generating or thermal acid-generating effect. An ammonium salt having a polymerizable anion and a polymer comprising recurring units derived therefrom may be used as a thermal acid generator.

[0048] Now the method for synthesizing the sulfonium salt having a polymerizable anion represented by formula (1) according to the invention is described. The sulfonium salt having a polymerizable anion represented by formula (1) can be synthesized by reacting triphenylsulfonium 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, which has been synthesized by the inventors, with (meth)acryloyl chloride or (meth)acrylic anhydride under basic conditions.

[0049] Briefly noted herein is the synthesis of triphenylsulfonium 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate. First, an aliphatic or aromatic carboxylic acid ester of 1,1,3,3,3-pentafluoropropen-2-yl, typically 1,1,3,3,3-pentafluoropropen-2-yl benzoate, which was developed by Nakai et al. using 1,1,1,3,3,3-hexafluoro-2-propanol as the starting reactant, is reacted with sodium hydrogen sulfite or sodium sulfite in a solvent such as water or alcohol or a mixture thereof in the presence of a radical initiator such as azobisisobutyronitrile or benzoyl peroxide, forming a corresponding 1,1,3,3,3-pentafluoro-2-acyloxypropanesulfonic acid salt or 1,1,3,3,3-pentafluoro-2-arenecarbonyloxypropanesulfonic acid salt. This salt is ion-exchanged with a suitable sulfonium salt, forming triphenylsulfonium 1,1,3,3,3-pentafluoro-2-acyloxypropanesulfonate or triphenylsulfonium 1,1,3,3,3-pentafluoro-2-arenecarbonyloxypropanesulfonate. The carboxylate moiety of the sulfonate is then subjected to hydrolysis with the aid of an alkali such as sodium hydroxide or potassium hydroxide, or solvolysis with the aid of an alcohol and base, yielding the target compound, triphenylsulfonium 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate. Synthesis of sulfonium salts other than triphenylsulfonium may be similarly carried out.

[0050] The reaction to synthesize the polymerizable anion proceeds readily by any well-known procedure. The reaction may be carried out by dissolving a sulfonium salt such as triphenylsulfonium 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate in a solvent such as methylene chloride, tetrahydrofuran or acetonitrile, sequentially or simultaneously adding thereto a base such as triethylamine, pyridine or 4-dimethylaminopyridine and an acid chloride or acid anhydride such as acryloyl chloride, acrylic anhydride, methacryloyl chloride, methacrylic anhydride, 2-fluoroacryloyl chloride, 2-fluoroacrylic anhydride, α, α, α-trifluoromethacryloyl chloride or α, α, α-trifluoromethacrylic anhydride, and cooling or heating the system as desired.

[0051] The polymer of the invention comprises recurring units derived from the sulfonium salt having a polymerizable anion represented by formula (1). Specifically, the recurring units derived from the sulfonium salt having a polymerizable anion represented by formula (1) include units of the general formula (2):

[0052]
wherein R¹ to R⁴ are as defined above.

[0053] In addition to the recurring units of formula (2), the polymer of the invention may further comprise recurring units of at least one selected from the general formulae (3) to (6):

[0054]
wherein R¹ is as defined above, R⁶ and R⁷ are each independently a hydrogen atom or hydroxyl group, X is an acid labile group, Y is a lactone structure-containing substituent group, and Z is hydrogen, a C₁-C₁₅ fluoroalkyl group or a C₁-C₁₅ fluoroalcohol-containing substituent group.

[0055] Under the action of an acid, a polymer comprising recurring units of formula (3) is decomposed to generate a carboxylic acid and turns into an alkali-soluble polymer.

[0056] The acid labile groups represented by X may be selected from a variety of such groups, for example, groups of the following general formulae (L1) to (L4), tertiary alkyl groups of 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, trialkylsilyl groups in which each alkyl moiety has 1 to 6 carbon atoms, and oxoalkyl groups of 4 to 20 carbon atoms.

[0057]
The broken line indicates a valence bond.

[0058] In formula (L1), R^L01 and R^L02 are hydrogen or straight, branched or cyclic alkyl groups of 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms. Examples include hydrogen, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclopentyl, cyclohexyl, 2-ethylhexyl, n-octyl, norbornyl, tricyclodecanyl, tetracyclododecanyl, and adamantyl.

[0059] R^L03 is a monovalent hydrocarbon group of 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, which may contain a hetero atom such as oxygen, examples of which include straight, branched or cyclic alkyl groups and substituted forms of these groups in which some hydrogen atoms are replaced by hydroxyl, alkoxy, oxo, amino, alkylamino or the like. Examples of the straight, branched or cyclic alkyl groups are as exemplified above for R_L01 and R_L02, and examples of the substituted alkyl groups are shown below.

[0060]

[0061] A pair of R^L01 and R^L02, R^L01 and R^L03, or R^L02 and R^L03 may bond together to form a ring with the carbon and oxygen atoms to which they are attached. Each of R^L01, R^L02 and R^L03 is a straight or branched alkylene group of 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms when they form a ring.

[0062] In formula (L2), R^L04 is a tertiary alkyl group of 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trialkylsilyl group in which each alkyl moiety has 1 to 6 carbon atoms, an oxoalkyl group of 4 to 20 carbon atoms, or a group of formula (L1). Exemplary tertiary alkyl groups are tert-butyl, tert-amyl, 1,1-diethylpropyl, 2-cyclopentylpropan-2-yl, 2-cyclohexylpropan-2-yl, 2-(bicyclo[2.2.1]heptan-2-yl)propan-2-yl, 2-(adamantan-1-yl)propan-2-yl, 1-ethylcyclopentyl, 1-butylcyclopentyl, 1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl, 1-ethyl-2-cyclohexenyl, 2-methyl-2-adamantyl, and 2-ethyl-2-adamantyl. Exemplary trialkylsilyl groups are trimethylsilyl, triethylsilyl, and dimethyl-tert-butylsilyl. Exemplary oxoalkyl groups are 3-oxocyclohexyl, 4-methyl-2-oxooxan-4-yl, and 5-methyl-2-oxooxolan-5-yl. In formula (L2), y is an integer of 0 to 6.

[0063] In formula (L3), R^L05 is a substituted or unsubstituted, C₁-C₈ straight, branched or cyclic alkyl group or a substituted or unsubstituted C₆-C₂₀ aryl group. Examples of the substituted or unsubstituted alkyl groups include straight, branched or cyclic ones such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl, cyclopentyl and cyclohexyl; and substituted forms of the foregoing in which some hydrogen atoms are replaced by hydroxyl, alkoxy, carboxy, alkoxycarbonyl, oxo, amino, alkylamino, cyano, mercapto, alkylthio, sulfo or other groups. Exemplary substituted or unsubstituted aryl groups are phenyl, methylphenyl, naphthyl, anthryl, phenanthryl, and pyrenyl. In formula (L3), m is 0 or 1, n is 0, 1, 2 or 3, and 2m+n is equal to 2 or 3.

[0064] In formula (L4), R^L06 is a substituted or unsubstituted, C₁-C₈, straight, branched or cyclic alkyl group or a substituted or unsubstituted C₆-C₂₀ aryl group. Examples of these groups are the same as exemplified for R^L05. R^L07 to R^L16 independently represent hydrogen or monovalent C₁-C₁₅ hydrocarbon groups. Exemplary hydrocarbon groups are straight, branched or cyclic alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl and cyclohexylbutyl, and substituted forms of the foregoing in which some hydrogen atoms are replaced by hydroxyl, alkoxy, carboxy, alkoxycarbonyl, oxo, amino, alkylamino, cyano, mercapto, alkylthio, sulfo or other groups. Alternatively, two of R^L07 to R^L16 may bond together to form a ring with the carbon atom to which they are attached (for example, a pair of R^L07 and R^L08, R^L07 and R^L09, R^L08 and R^L10, R^L09 and R^L10, R^L11 and R^L12, R^L13 and R^L14, or a similar pair form a ring). Each of R^L07 to R^L16 represents a divalent C₁-C₁₅ hydrocarbon group when they form a ring, examples of which are the ones exemplified above for the monovalent hydrocarbon groups, with one hydrogen atom being eliminated. Two of R^L07 to R^L16 which are attached to vicinal carbon atoms may bond together directly to form a double bond (for example, a pair of R^L07 and R^L09, R^L09 and R^L15, R^L13 and R^L15, or a similar pair).

[0065] Of the acid labile groups of formula (L1), the straight and branched ones are exemplified by the following groups.

[0066]

[0067] Of the acid labile groups of formula (L1), the cyclic ones are, for example, tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2-yl, tetrahydropyran-2-yl, and 2-methyltetrahydropyran-2-yl.

[0068] Examples of the acid labile groups of formula (L2) include tert-butoxycarbonyl, tert-butoxycarbonylmethyl, tert-amyloxycarbonyl, tert-amyloxycarbonylmethyl, 1,1-diethylpropyloxycarbonyl, 1,1-diethylpropyloxycarbonylmethyl, 1-ethylcyclopentyloxycarbonyl, 1-ethylcyclopentyloxycarbonylmethyl, 1-ethyl-2-cyclopentenyloxycarbonyl, 1-ethyl-2-cyclopentenyloxycarbonylmethyl, 1-ethoxyethoxycarbonylmethyl, 2-tetrahydropyranyloxycarbonylmethyl, and 2-tetrahydrofuranyloxycarbonylmethyl groups.

[0069] Examples of the acid labile groups of formula (L3) include 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-n-propylcyclopentyl, 1-isopropylcyclopentyl, 1-n-butylcyclopentyl, 1-sec-butylcyclopentyl, 1-cyclohexylcyclopentyl, 1-(4-methoxy-n-butyl)cyclopentyl, 1-methylcyclohexyl, 1-ethylcyclohexyl, 3-methyl-1-cyclopenten-3-yl, 3-ethyl-1-cyclopenten-3-yl, 3-methyl-1-cyclohexen-3-yl, and 3-ethyl-1-cyclohexen-3-yl groups.

[0070] The acid labile groups of formula (L4) are preferably groups of the following formulae (L4-1) to (L4-4).

[0071]

[0072] In formulae (L4-1) to (L4-4), the broken line indicates a bonding site and direction. R^L41 is each independently selected from monovalent hydrocarbon groups, typically straight, branched or cyclic C₁-C₁₀ alkyl groups, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl, cyclopentyl, and cyclohexyl.

[0073] For formulas (L4-1) to (L4-4), there can exist enantiomers and diastereomers. Each of formulae (L4-1) to (L4-4) collectively represents all such stereoisomers. Such stereoisomers may be used alone or in admixture.

[0074] For example, the general formula (L4-3) represents one or a mixture of two selected from groups having the following general formulas (L4-3-1) and (L4-3-2).

[0075]

[0076] Similarly, the general formula (L4-4) represents one or a mixture of two or more selected from groups having the following general formulas (L4-4-1) to (L4-4-4).

[0077]

[0078] Each of formulas (L4-1) to (L4-4), (L4-3-1) and (L4-3-2), and (L4-4-1) to (L4-4-4) collectively represents an enantiomer thereof and a mixture of enantiomers.

[0079] It is noted that in the above formulas (L4-1) to (L4-4), (L4-3-1) and (L4-3-2), and (L4-4-1) to (L4-4-4), the bond direction is on the exo side relative to the bicyclo[2.2.1]heptane ring, which ensures high reactivity for acid catalyzed elimination reaction (see JP-A 2000-336121). In preparing these monomers having a tertiary exo-alkyl group of bicyclo[2.2.1]heptane skeleton as a substituent group, there may be contained monomers substituted with an endo-alkyl group as represented by the following formulas (L4-1-endo) to (L4-4-endo). For good reactivity, an exo proportion of at least 50 mol % is preferred, with an exo proportion of at least 80 mol % being more preferred.

[0080]
(See JP-A 2000-336121 corresponding to U.S. Pat. No. 6,312,864 and EP 1,004,568.)

[0081] Illustrative examples of the acid labile group of formula (L4) are given below.

[0082]

[0083] Examples of the tertiary C₄-C₂₀ alkyl, tri(C₁-C₆-alkyl)silyl and C₄-C₂₀ oxoalkyl groups included in the acid labile groups represented by X are as exemplified above for R^L04.

[0084] Illustrative, non-limiting examples of the recurring units of formula (3) are given below.

[0085]

[0086] Illustrative, non-limiting examples of the recurring units of formula (4) are given below.

[0087]

[0088] Illustrative, non-limiting examples of the recurring units of formula (5) are given below.

[0089]

[0090] Illustrative, non-limiting examples of the recurring units of formula (6) are given below.

[0091]

[0092] The polymer of the invention may further comprise recurring units derived from another monomer having a carbon-to-carbon double bond other than the foregoing. Examples of the additional monomer include substituted acrylic acid esters such as methyl methacrylate, methyl crotonate, dimethyl maleate, and dimethyl itaconate, unsaturated carboxylic acids such as maleic acid, fumaric acid and itaconic acid, cyclic olefins such as norbornene, norbornene derivatives, and tetracyclo[6.2.1.1^3,6.0^2,7]dodecene derivatives, and unsaturated acid anhydrides such as itaconic anhydride.

[0093] While the polymer of the invention is applicable to the ArF lithography, it is also applicable to other lithography processes such as KrF, EB and EUV lithography.

[0094] Specifically, in addition to the recurring units of formula (2), the polymer of the invention may further comprise recurring units of at least one selected from the general formulae (7) to (10) and optionally, recurring units of at least one selected from the general formulae (3) to (6) described above.

[0095]
Herein, R¹ and X are as defined above, and G is an oxygen atom or carbonyloxy group (—C(═O)O—).

[0096] Under the action of an acid, a polymer comprising recurring units of formula (7) is decomposed to generate a phenolic hydroxyl group and/or carboxylic acid and turns into an alkali-soluble polymer. The acid labile groups represented by X may be selected from a variety of such groups, for example, groups of the general formulae (L1) to (L4), tertiary alkyl groups of 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, trialkylsilyl groups in which each alkyl moiety has 1 to 6 carbon atoms, and oxoalkyl groups of 4 to 20 carbon atoms, which have been described above.

[0097] Illustrative, non-limiting examples of the recurring units of formula (7) are given below.

[0098]

[0099] The hydroxyvinylnaphthalenes from which units of formula (10) are derived may have the substituents at any desired sites on naphthalene and include 6-hydroxy-2-vinylnaphthalene and 4-hydroxy-1-vinylnaphthalene, with 6-hydroxy-2-vinylnaphthalene being preferred.

[0100] Preference is given to polymers comprising recurring units of at least one of formulae (7) to (10) and recurring units of at least one of formulae (3) to (6), especially recurring units of formula (3).

[0101] The polymer of the invention comprising recurring units derived from a sulfonium salt having a polymerizable anion and recurring units of at least one of formulae (7) to (10) may further comprise recurring units derived from another monomer having a carbon-to-carbon double bond other than the foregoing. Examples of the additional monomer include substituted acrylic acid esters such as methyl methacrylate, methyl crotonate, dimethyl maleate, and dimethyl itaconate, unsaturated carboxylic acids such as maleic acid, fumaric acid and itaconic acid, cyclic olefins such as norbornene, norbornene derivatives, tetracyclo[6.2.1.1^3,6.0^2.7]dodecene derivatives, and norbornadienes, and unsaturated acid anhydrides such as itaconic anhydride, as well as styrene, acenaphthylene, vinylnaphthalene, and other monomers.

[0102] It is noted that the polymer has a weight average molecular weight (Mw) of about 1,000 to about 500,000, and preferably about 3,000 to about 100,000. Outside the range, a polymer may suffer an extreme drop of etching resistance or a reduced resolution due to a failure to provide a difference in dissolution rate before and after exposure. The measurement of molecular weight may be performed by gel permeation chromatography (GPC) versus polystyrene standards or a light scattering method.

[0103] In the inventive polymer, the preferred proportion of respective recurring units derived from discrete monomers may fall, for example, in the range (mol %) shown below, but is not limited thereto. The polymer may consist essentially of:

[0104] (I) from more than 0 mol % to 100 mol %, preferably 1 to 30 mol %, and more preferably 5 to 20 mol % of constituent units of at least one type having formula (2) derived from the monomer(s) having formula (1);

[0105] (II) from 0 mol % to less than 100 mol %, preferably 70 to 99 mol %, and more preferably 80 to 95 mol % of constituent units of at least one type having formulae (3) to (6) and/or formulae (7) to (10); and optionally,

[0106] (III) from 0 mol % to 80 mol %, preferably 0 to 70 mol %, and more preferably 0 to 50 mol % of constituent units of at least one type derived from the additional monomer(s).

[0107] The polymer of the invention may be prepared through copolymerization reaction using the compound of formula (1) as a first monomer and one or more compounds having a polymerizable double bond as second and subsequent monomers. Various modes of copolymerization reaction may be used for the preparation of the inventive polymer. The preferred modes are radical polymerization, anionic polymerization and coordination polymerization.

[0108] For radical polymerization, preferred reaction conditions include (a) a solvent selected from among hydrocarbons such as benzene, ethers such as tetrahydrofuran, alcohols such as ethanol, and ketones such as methyl isobutyl ketone, (b) a polymerization initiator selected from azo compounds such as 2,2′-azobisisobutyronitrile and peroxides such as benzoyl peroxide and lauroyl peroxide, (c) a temperature of about 0° C. to about 100° C., and (d) a time of about ½ hour to about 48 hours. Reaction conditions outside the described range may be employed if desired.

[0109] For anionic polymerization, preferred reaction conditions include (a) a solvent selected from among hydrocarbons such as benzene, ethers such as tetrahydrofuran, and liquid ammonia, (b) a polymerization initiator selected from metals such as sodium and potassium, alkyl metals such as n-butyllithium and sec-butyllithium, ketyl, and Grignard reagents, (c) a temperature of about −78° C. to about 0° C., (d) a time of about ½ hour to about 48 hours, and (e) a stopper selected from among proton-donative compounds such as methanol, halides such as methyl iodide, and electrophilic compounds. Reaction conditions outside the described range may be employed if desired.

[0110] For coordination polymerization, preferred reaction conditions include (a) a solvent selected from among hydrocarbons such as n-heptane and toluene, (b) a catalyst selected from Ziegler-Natta catalysts comprising a transition metal (e.g., titanium) and alkylaluminum, Phillips catalysts of metal oxides having chromium or nickel compounds carried thereon, and olefin-metathesis mixed catalysts as typified by tungsten and rhenium mixed catalysts, (c) a temperature of about 0° C. to about 100° C., and (d) a time of about ½ hour to about 48 hours. Reaction conditions outside the described range may be employed if desired.

[0111] The polymer prepared by any mode of polymerization as described above may be used in a negative resist composition, provided that some or all acid labile groups on the polymer are deprotected. Alternatively, the polymer in which acid labile groups have been deprotected can be modified by introducing acid labile groups therein again whereby substituent groups different from the acid labile groups initially introduced during polymerization are introduced into the polymer.

[0112] For example, once a polymer is formed through radical polymerization of 4-ethoxyethoxystyrene and a sulfonium salt with a polymerizable anion having formula (1) according to the invention, the polymer may be converted into a copolymer with polyhydroxystyrene by eliminating ethoxyethoxy groups from the polymer using acetic acid, pyridinium tosylate or the like. The resultant copolymer may be used as a base resin in a negative resist composition. Alternatively, hydroxystyrene units in the resultant copolymer may be reacted with di-tert-butyl dicarbonate, tert-butyl chloroacetate, vinyl ethers or the like, whereby acid labile groups different from the acid labile groups (i.e., ethoxyethoxy groups) initially introduced during polymerization are introduced.

[0113] The polymer of the invention is advantageously used as a base resin in a resist composition, and specifically a chemically amplified positive resist composition. Thus the invention provides a resist composition comprising the polymer, and especially a positive resist composition comprising the polymer. The positive resist composition preferably comprises:

[0114] (A) a base resin comprising the inventive polymer,

[0115] (C) an organic solvent, and optionally,

[0116] (B) an acid generator,

[0117] (D) a quencher, and

[0118] (E) a surfactant.

[0119] Also the polymer of the invention may be used as a base resin in a chemically amplified negative resist composition. The negative resist composition preferably comprises:

[0120] (A) a base resin comprising the inventive polymer,

[0121] (C) an organic solvent,

[0122] (H) a crosslinker for inducing crosslinkage under the action of an acid, and optionally,

[0123] (B) an acid generator,

[0124] (D) a quencher, and

[0125] (E) a surfactant.

[0126] For the positive resist composition, the base resin as component (A) may comprise another resin having a dissolution rate in an alkaline developer that increases under the action of an acid, if desired, as well as the inventive polymer. Exemplary other resins include, but are not limited to, (i) poly(meth)acrylic acid derivatives, (ii) norbornene derivative/maleic anhydride copolymers, (iii) hydrogenated products of ring-opening metathesis polymers (ROMP), (iv) vinyl ether/maleic anhydride/(meth)acrylic acid derivative copolymers, and (v) polyhydroxystyrene derivatives.

[0127] Of these, the poly(meth)acrylic acid derivatives (i) are polymers comprising units of formulae (3) to (6) and other units in combination. The polyhydroxystyrene derivatives (v) include polymers comprising units of formulae (7) to (10) in combination and polymers comprising units of formulae (3) to (10) in combination. In these polymers, a proportion of those units having acid labile groups, for example, monomer units of one or more types selected from among formulae (3) and (7) and a combination thereof is from more than 0 mole % to 80 mole %, preferably 1 to 50 mole %, and more preferably 10 to 40 mole %.

[0128] The hydrogenated products of ROMP (iii) are synthesized by the method illustrated in Examples of JP-A 2003-66612. Illustrative examples of such hydrogenated polymers include those polymers having the recurring units shown below, but are not limited thereto.

[0129]

[0130] The inventive polymer and the other polymer are preferably blended in a weight ratio from 100:0 to 10:90, more preferably from 100:0 to 20:80. If the blend ratio of the inventive polymer is below this range, the resist composition would become poor in some of the desired properties. The properties of the resist composition can be adjusted by properly changing the blend ratio of the inventive polymer. The polymer is not limited to one type and a mixture of two or more polymers may be added. The use of plural polymers allows for easy adjustment of resist properties.

[0131] Photoacid Generator

[0132] In the practice of the invention, an acid generator is optionally used as component (B). Where a photoacid generator is added as the acid generator, it may be any compound capable of generating an acid upon exposure to high-energy radiation. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate acid generators. Exemplary acid generators are given below while they may be used alone or in admixture of two or more.

[0133] Sulfonium salts are salts of sulfonium cations with sulfonates, bis(substituted alkylsulfonyl)imides and tris(substituted alkylsulfonyl)methides. Exemplary sulfonium cations include triphenylsulfonium, (4-tert-butoxyphenyl)diphenylsulfonium, bis(4-tert-butoxyphenyl)phenylsulfonium, tris(4-tert-butoxyphenyl)sulfonium, (3-tert-butoxyphenyl)diphenylsulfonium, bis(3-tert-butoxyphenyl)phenylsulfonium, tris(3-tert-butoxyphenyl)sulfonium, (3,4-di-tert-butoxyphenyl)diphenylsulfonium, bis(3,4-di-tert-butoxyphenyl)phenylsulfonium, tris(3,4-di-tert-butoxyphenyl)sulfonium, diphenyl(4-thiophenoxyphenyl)sulfonium, (4-tert-butoxycarbonylmethyloxyphenyl)diphenylsulfonium, tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium, (4-tert-butoxyphenyl)bis(4-dimethylaminophenyl)sulfonium, tris(4-dimethylaminophenyl)sulfonium, 4-methylphenyldiphenylsulfonium, 4-tert-butylphenyldiphenylsulfonium, bis(4-methylphenyl)phenylsulfonium, bis(4-tert-butylphenyl)phenylsulfonium, tris(4-methylphenyl)sulfonium, tris(4-tert-butylphenyl)sulfonium, tris(phenylmethyl)sulfonium, 2-naphthyldiphenylsulfonium, dimethyl(2-naphthyl)sulfonium, 4-hydroxyphenyldimethylsulfonium, 4-methoxyphenyldimethylsulfonium, trimethylsulfonium, 2-oxocyclohexylcyclohexylmethylsulfonium, trinaphthylsulfonium, tribenzylsulfonium, diphenylmethylsulfonium, dimethylphenylsulfonium, 2-oxopropylthiacyclopentanium, 2-oxobutylthiacyclopentanium, 2-oxo-3,3-dimethylbutylthiacyclopentanium, 2-oxo-2-phenylethylthiacyclopentanium, 4-n-butoxynaphthyl-1-thiacyclopentanium, and 2-n-butoxynaphthyl-1-thiacyclopentanium. Exemplary sulfonates include trifluoromethanesulfonate, pentafluoroethanesulfonate, heptafluoropropanesulfonate, nonafluorobutanesulfonate, tridecafluorohexanesulfonate, perfluoro(4-ethylcyclohexyl)sulfonate, heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate, 4-(trifluoromethyl)benzenesulfonate, 4-fluorobenzenesulfonate, mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate, 4-(p-toluenesulfonyloxy)benzenesulfonate, 6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate, 4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate, camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate, butanesulfonate, methanesulfonate, 1,1-difluoro-2-naphthyl-ethanesulfonate, 1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, 1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^2,5.1^7,10]dodec-3-en-8-yl)ethanesulfonate, 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate. Exemplary bis(substituted alkylsulfonyl)imides include bis(trifluoromethylsulfonyl)imide, bis(pentafluoroethylsulfonyl)imide, bis(heptafluoropropylsulfonyl)imide, and perfluoro(1,3-propylenebissulfonyl)imide. A typical tris(substituted alkylsulfonyl)methide is tris(trifluoromethylsulfonyl)methide. Sulfonium salts based on combination of the foregoing examples are included.

[0134] Iodonium salts are salts of iodonium cations with sulfonates, bis(substituted alkylsulfonyl)imides and tris(substituted alkylsulfonyl)methides. Exemplary iodonium cations include diphenyliodinium, bis(4-tert-butylphenyl)iodonium, 4-tert-butoxyphenylphenyliodonium, and 4-methoxyphenylphenyliodonium. Exemplary sulfonates include trifluoromethanesulfonate, pentafluoroethanesulfonate, heptafluoropropanesulfonate, nonafluorobutanesulfonate, tridecafluorohexanesulfonate, perfluoro(4-ethylcyclohexane)sulfonate, heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate, 4-(trifluoromethyl)benzenesulfonate, 4-fluorobenzenesulfonate, mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate, 4-(p-toluenesulfonyloxy)benzenesulfonate, 6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate, 4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate, camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate, butanesulfonate, methanesulfonate, 1,1-difluoro-2-naphthyl-ethanesulfonate, 1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, 1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^2,5.1^7,10]dodec-3-en-8-yl)ethanesulfonate, 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yloxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate. Exemplary bis(substituted alkylsulfonyl)imides include bis(trifluoromethylsulfonyl)imide, bis(pentafluoroethylsulfonyl)imide, bis(heptafluoropropylsulfonyl)imide, and perfluoro(1,3-propylenebissulfonyl)imide. A typical tris(substituted alkylsulfonyl)methide is tris(trifluoromethylsulfonyl)methide. Iodonium salts based on combination of the foregoing examples are included.

[0135] Exemplary sulfonyldiazomethane compounds include bissulfonyldiazomethane compounds and sulfonylcarbonyldiazomethane compounds such as bis(ethylsulfonyl)diazomethane, bis(1-methylpropylsulfonyl)diazomethane, bis(2-methylpropylsulfonyl)diazomethane, bis(1,1-dimethylethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(perfluoroisopropylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(4-methylphenylsulfonyl)diazomethane, bis(2,4-dimethylphenylsulfonyl)diazomethane, bis(4-acetyloxyphenylsulfonyl)diazomethane, bis(4-(methanesulfonyloxy)phenylsulfonyl)diazomethane, bis(4-(p-toluenesulfonyloxy)phenylsulfonyl)diazomethane, bis(4-n-hexyloxyphenylsulfonyl)diazomethane, bis(2-methyl-4-n-hexyloxyphenylsulfonyl)diazomethane, bis(2,5-dimethyl-4-n-hexyloxyphenylsulfonyl)diazomethane, bis(3,5-dimethyl-4-n-hexyloxyphenylsulfonyl)diazomethane, bis(2-methyl-5-isopropyl-4-n-hexyloxyphenylsulfonyl)diazomethane, bis(2-naphthylsulfonyl)diazomethane, 4-methylphenylsulfonylbenzoyldiazomethane, tert-butylcarbonyl-4-methylphenylsulfonyldiazomethane, 2-naphthylsulfonylbenzoyldiazomethane, 4-methylphenylsulfonyl-2-naphthoyldiazomethane, methylsulfonylbenzoyldiazomethane, and tert-butoxycarbonyl-4-methylphenylsulfonyldiazomethane.

[0136] N-sulfonyloxydicarboxyimide photoacid generators include combinations of imide skeletons with sulfonates. Exemplary imide skeletons are succinimide, naphthalenedicarboxyimide, phthalimide, cyclohexyldicarboxyimide, 5-norbornene-2,3-dicarboxyimide, and 7-oxabicyclo[2.2.1]-5-heptene-2,3-dicarboxyimide. Exemplary sulfonates include trifluoromethanesulfonate, pentafluoroethanesulfonate, heptafluoropropanesulfonate, nonafluorobutanesulfonate, tridecafluorohexanesulfonate, perfluoro(4-ethylcyclohexane)sulfonate, heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate, 4-(trifluoromethyl)benzenesulfonate, 4-fluorobenzenesulfonate, mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate, 4-(p-toluenesulfonyloxy)benzenesulfonate, 6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate, 4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate, camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate, butanesulfonate, methanesulfonate, 1,1-difluoro-2-naphthylethanesulfonate, 1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, 1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^2,5.1^7,10]dodec-3-en-8-yl)ethanesulfonate, 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

[0137] Benzoinsulfonate photoacid generators include benzoin tosylate, benzoin mesylate, and benzoin butanesulfonate.

[0138] Pyrogallol trisulfonate photoacid generators include pyrogallol, phloroglucin, catechol, resorcinol, and hydroquinone, in which all the hydroxyl groups are substituted by trifluoromethanesulfonate, pentafluoroethanesulfonate, heptafluoropropanesulfonate, nonafluorobutanesulfonate, tridecafluorohexanesulfonate, perfluoro(4-ethylcyclohexane)sulfonate, heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate, 4-(trifluoromethyl)benzenesulfonate, 4-fluorobenzenesulfonate, mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate, 4-(p-toluenesulfonyloxy)benzenesulfonate, 6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate, 4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate, camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate, butanesulfonate, methanesulfonate, 1,1-difluoro-2-naphthylethanesulfonate, 1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, 1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^2,5.1^7,10]dodec-3-en-8-yl)ethanesulfonate, 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate, etc.

[0139] Nitrobenzyl sulfonate photoacid generators include 2,4-dinitrobenzyl sulfonate, 2-nitrobenzyl sulfonate, and 2,6-dinitrobenzyl sulfonate, with exemplary sulfonates including trifluoromethanesulfonate, pentafluoroethanesulfonate, heptafluoropropanesulfonate, nonafluorobutanesulfonate, tridecafluorohexanesulfonate, perfluoro(4-ethylcyclohexane)sulfonate, heptadecafluorooctanesulfonate, 2,2,2-trifluoroethanesulfonate, pentafluorobenzenesulfonate, 4-(trifluoromethyl)benzenesulfonate, 4-fluorobenzenesulfonate, mesitylenesulfonate, 2,4,6-triisopropylbenzenesulfonate, toluenesulfonate, benzenesulfonate, 4-(p-toluenesulfonyloxy)benzenesulfonate, 6-(p-toluenesulfonyloxy)naphthalene-2-sulfonate, 4-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 5-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, 8-(p-toluenesulfonyloxy)naphthalene-1-sulfonate, naphthalenesulfonate, camphorsulfonate, octanesulfonate, dodecylbenzenesulfonate, butanesulfonate, methanesulfonate, 1,1-difluoro-2-naphthylethanesulfonate, 1,1,2,2-tetrafluoro-2-(norbornan-2-yl)ethanesulfonate, 1,1,2,2-tetrafluoro-2-(tetracyclo[4.4.0.1^2,5.1^7,10]dodec-3-en-8-yl)ethanesulfonate, 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate, etc. Also useful are nitrobenzyl sulfonate analogues in which the nitro group on the benzyl side is substituted by a trifluoromethyl group.

[0140] Sulfone photoacid generators include bis(phenylsulfonyl)methane, bis(4-methylphenylsulfonyl)methane, bis(2-naphthylsulfonyl)methane, 2,2-bis(phenylsulfonyl)propane, 2,2-bis(4-methylphenylsulfonyl)propane, 2,2-bis(2-naphthylsulfonyl)propane, 2-methyl-2-(p-toluenesulfonyl)propiophenone, 2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane, and 2,4-dimethyl-2-(p-toluenesulfonyl)pentan-3-one.

[0141] Suitable O-arylsulfonyloxime compounds and O-alkylsulfonyloxime compounds (oxime sulfonates) include photoacid generators in the form of glyoxime derivatives; photoacid generators in the form of oxime sulfonates with a long conjugated system separated by thiophene or cyclohexadiene; oxime sulfonates having an electron withdrawing group such as trifluoromethyl incorporated for increased stability; oxime sulfonates using phenylacetonitrile or substituted acetonitrile derivatives; and bisoxime sulfonates.

[0142] Photoacid generators in the form of glyoxime derivatives include bis-O-(p-toluenesulfonyl)-α-dimethylglyoxime, bis-O-(p-toluenesulfonyl)-α-diphenylglyoxime, bis-O-(p-toluenesulfonyl)-α-dicyclohexylglyoxime, bis-O-(p-toluenesulfonyl)-2,3-pentanedionedioxime, bis-O-(n-butanesulfonyl)-α-dimethylglyoxime, bis-O-(n-butanesulfonyl)-α-diphenylglyoxime, bis-O-(n-butanesulfonyl)-α-dicyclohexylglyoxime, bis-O-(methanesulfonyl)-α-dimethylglyoxime, bis-O-(trifluoromethanesulfonyl)-α-dimethylglyoxime, bis-O-(2,2,2-trifluoroethanesulfonyl)-α-dimethylglyoxime, bis-O-(10-camphorsulfonyl)-α-dimethylglyoxime, bis-O-(benzenesulfonyl)-α-dimethylglyoxime, bis-O-(4-fluorobenzenesulfonyl)-α-dimethylglyoxime, bis-O-(4-trifluoromethylbenzenesulfonyl)-α-dimethylglyoxime, bis-O-(xylenesulfonyl)-α-dimethylglyoxime, bis-O-(trifluoromethanesulfonyl)-nioxime, bis-O-(2,2,2-trifluoroethanesulfonyl)-nioxime, bis-O-(10-camphorsulfonyl)-nioxime, bis-O-(benzenesulfonyl)-nioxime, bis-O-(4-fluorobenzenesulfonyl)-nioxime, bis-O-(4-(trifluoromethyl)benzenesulfonyl)-nioxime, and bis-O-(xylenesulfonyl)-nioxime. Also included are modified forms of the foregoing compounds having substituted on their skeleton 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

[0143] Photoacid generators in the form of oxime sulfonates with a long conjugated system separated by thiophene or cyclohexadiene include (5-(p-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile, (5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile, (5-n-octanesulfonyloxyimino-5H-thiophen-2-ylidene)phenylacetonitrile, (5-(p-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile, (5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile, (5-n-octanesulfonyloxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile, (5-(4-(p-toluenesulfonyloxy)benzenesulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile, and (5-(2,5-bis(p-toluenesulfonyloxy)benzenesulfonyl)oxyimino-5H-thiophen-2-ylidene)phenylacetonitrile. Also included are modified forms of the foregoing compounds having substituted on their skeleton 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

[0144] Suitable oxime sulfonates having an electron withdrawing group such as trifluoromethyl incorporated for increased stability include 2,2,2-trifluoro-1-phenyl-ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-phenyl-ethanone O-(10-camphorsulfonyl)oxime, 2,2,2-trifluoro-1-phenylethanone O-(4-methoxybenzenesulfonyl)oxime, 2,2,2-trifluoro-1-phenyl-ethanone O-(1-naphthylsulfonyl)oxime, 2,2,2-trifluoro-1-phenylethanone O-(2-naphthylsulfonyl)oxime, 2,2,2-trifluoro-1-phenylethanone O-(2,4,6-trimethylphenylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylphenyl)ethanone O-(10-camphorsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylphenyl)ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-methylphenyl)-ethanone O-(10-camphorsulfonyl)oxime, 2,2,2-trifluoro-1-(2,4-dimethylphenyl)ethanone O-(10-camphorsulfonyl)oxime, 2,2,2-trifluoro-1-(2,4-dimethylphenyl)ethanone O-(1-naphthyl-sulfonyl)oxime, 2,2,2-trifluoro-1-(2,4-dimethylphenyl)-ethanone O-(2-naphthylsulfonyl)oxime, 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)ethanone O-(10-camphorsulfonyl)oxime, 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)ethanone O-(1-naphthylsulfonyl)oxime, 2,2,2-trifluoro-1-(2,4,6-trimethylphenyl)ethanone O-(2-naphthylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxyphenyl)ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylthiophenyl)-ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(3,4-dimethoxyphenyl)-ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxyphenyl)ethanone O-(4-methylphenylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxyphenyl)ethanone O-(4-methoxyphenylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxyphenyl)-ethanone O-(4-dodecylphenylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxyphenyl)ethanone O-(octylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-thiomethylphenyl)ethanone O-(4-methoxyphenylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-thiomethylphenyl)-ethanone O-(4-dodecylphenylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-thiomethylphenyl)ethanone O-(octylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-thiomethylphenyl)ethanone O-(2-naphthylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-methylphenyl)ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylphenyl)-ethanone O-(phenylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-chlorophenyl)ethanone O-(phenylsulfonyl)oxime, 2,2,3,3,4,4,4-heptafluoro-1-phenylbutanone O-(10-camphorsulfonyl)oxime, 2,2,2-trifluoro-1-(1-naphthyl)ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-naphthyl)-ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-benzylphenyl)ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-(phenyl-1,4-dioxa-but-1-yl)phenyl)-ethanone O-(methylsulfonyl)oxime, 2,2,2-trifluoro-1-(1-naphthyl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-naphthyl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-benzylphenyl)ethanone O-(propyl-sulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylsulfonylphenyl)-ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylsulfonyloxyphenyl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methylcarbonyloxyphenyl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(6H, 7H-5,8-dioxonaphth-2-yl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxycarbonylmethoxyphenyl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-methoxycarbonyl)-(4-amino-1-oxa-pent-1-yl)phenyl)ethanone O-(propyl-sulfonyl)oxime, 2,2,2-trifluoro-1-(3,5-dimethyl-4-ethoxy-phenyl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-benzyloxyphenyl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(2-thiophenyl)ethanone O-(propylsulfonate)-oxime, and 2,2,2-trifluoro-1-(1-dioxathiophen-2-yl)ethanone O-(propylsulfonate)oxime; 2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(trifluoromethanesulfonyloxyimino)ethyl)phenoxy)-propoxy)phenyl)ethanone O-(trifluoromethanesulfonyl)oxime, 2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(1-propane-sulfonyloxyimino)ethyl)phenoxy)propoxy)phenyl)ethanone O-(propylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(1-butanesulfonyloxyimino)ethyl)phenoxy)propoxy)-phenyl)ethanone O-(butylsulfonyl)oxime, 2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(4-(4-methylphenylsulfonyloxy)-phenylsulfonyloxyimino)ethyl)phenoxy)propoxy)phenyl)ethanone O-(4-(4-methylphenylsulfonyloxy)phenylsulfonyl)oxime, and 2,2,2-trifluoro-1-(4-(3-(4-(2,2,2-trifluoro-1-(2,5-bis(4-methylphenylsulfonyloxy)benzenesulfonyloxy)phenylsulfonyloxyimino)ethyl)phenoxy)propoxy)phenyl)ethanone O-(2,5-bis(4-methylphenylsulfonyloxy)benzenesulfonyloxy)phenylsulfonyl)-oxime. Also included are modified forms of the foregoing compounds having substituted on their skeleton 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

[0145] Also included are oxime sulfonates having the formula (Ox-1):

[0146]
wherein R⁴⁰¹ is a substituted or unsubstituted C₁-C₁₀ haloalkylsulfonyl or halobenzenesulfonyl group, R⁴⁰² is a C₁-C₁₁ haloalkyl group, and Ar⁴⁰¹ is a substituted or unsubstituted aromatic or hetero-aromatic group.

[0147] Examples include 2-[2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)pentyl]fluorene, 2-[2,2,3,3,4,4-pentafluoro-1-(nonafluorobutylsulfonyloxyimino)butyl]fluorene, 2-[2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl]fluorene, 2-[2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)pentyl]-4-biphenyl, 2-[2,2,3,3,4,4-pentafluoro-1-(nonafluorobutylsulfonyloxyimino)butyl]-4-biphenyl, and 2-[2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl]-4-biphenyl. Also included are modified forms of the foregoing compounds having substituted on their skeleton 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

[0148] Suitable oxime sulfonate generators using substituted acetonitrile derivatives include α-(p-toluenesulfonyloxyimino)-phenylacetonitrile, α-(p-chlorobenzenesulfonyloxyimino)-phenylacetonitrile, α-(4-nitrobenzenesulfonyloxyimino)-phenylacetonitrile, α-(4-nitro-2-trifluoromethylbenzenesulfonyloxyimino)-phenylacetonitrile, α-(benzenesulfonyloxyimino)-4-chlorophenylacetonitrile, α-(benzenesulfonyloxyimino)-2,4-dichlorophenylacetonitrile, α-(benzenesulfonyloxyimino)-2,6-dichlorophenylacetonitrile, α-(benzenesulfonyloxyimino)-4-methoxyphenylacetonitrile, α-(2-chlorobenzenesulfonyloxyimino)-4-methoxyphenylacetonitrile, α-(benzenesulfonyloxyimino)-2-thienylacetonitrile, α-(4-dodecylbenzenesulfonyloxyimino)-phenylacetonitrile, α-[(4-toluenesulfonyloxyimino)-4-methoxyphenyl]acetonitrile, α-[(dodecylbenzenesulfonyloxyimino)-4-methoxyphenyl]-acetonitrile, α-(tosyloxyimino)-3-thienylacetonitrile, α-(methylsulfonyloxyimino)-1-cyclopentenylacetonitrile, α-(ethylsulfonyloxyimino)-1-cyclopentenylacetonitrile, α-(isopropylsulfonyloxyimino)-1-cyclopentenylacetonitrile, α-(n-butylsulfonyloxyimino)-1-cyclopentenylacetonitrile, α-(ethylsulfonyloxyimino)-1-cyclohexenylacetonitrile, α-(isopropylsulfonyloxyimino)-1-cyclohexenylacetonitrile, and α-(n-butylsulfonyloxyimino)-1-cyclohexenylacetonitrile.

[0149] Also included are modified forms of the foregoing compounds having substituted on their skeleton 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

[0150] Suitable bisoxime sulfonates include bis(α-(p-toluenesulfonyloxy)imino)-p-phenylenediacetonitrile, bis(α-(benzenesulfonyloxy)imino)-p-phenylenediacetonitrile, bis(α-(methanesulfonyloxy)imino)-p-phenylenediacetonitrile, bis(α-(butanesulfonyloxy)imino)-p-phenylenediacetonitrile, bis(α-(10-camphorsulfonyloxy)imino)-p-phenylenediacetonitrile, bis(α-(trifluoromethanesulfonyloxy)imino)-p-phenylenediacetonitrile, bis(α-(4-methoxybenzenesulfonyloxy)imino)-p-phenylenediacetonitrile, bis(α-(4-toluenesulfonyloxy)imino)-m-phenylenediacetonitrile, bis(α-(benzenesulfonyloxy)imino)-m-phenylenediacetonitrile, bis(α-(methanesulfonyloxy)imino)-m-phenylenediacetonitrile, bis(α-(butanesulfonyloxy)imino)-m-phenylenediacetonitrile, bis(α-(10-camphorsulfonyloxy)imino)-m-phenylenediacetonitrile, bis(α-(trifluoromethanesulfonyloxy)imino)-m-phenylenediacetonitrile, bis(α-(4-methoxybenzenesulfonyloxy)imino)-m-phenylenediacetonitrile, etc.

[0151] Also included are modified forms of the foregoing compounds having substituted on their skeleton 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-(4-phenylbenzoyloxy)propanesulfonate, 1,1,3,3,3-pentafluoro-2-pivaloyloxypropanesulfonate, 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-furoyloxypropanesulfonate, 2-naphthoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-(4-tert-butylbenzoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 2-acetyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 1,1,3,3,3-pentafluoro-2-hydroxypropanesulfonate, 1,1,3,3,3-pentafluoro-2-tosyloxypropanesulfonate, 1,1-difluoro-2-tosyloxyethanesulfonate, adamantanemethoxycarbonyldifluoromethanesulfonate, 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, methoxycarbonyldifluoromethanesulfonate, 1-(hexahydro-2-oxo-3,5-methano-2H-cyclopenta[b]furan-6-yl-oxycarbonyl)difluoromethanesulfonate, and 4-oxo-1-adamantyloxycarbonyldifluoromethanesulfonate.

[0152] When the photoacid generator (B) is added to the KrF excimer laser resist composition, preference is given to sulfonium salts, bissulfonyldiazomethanes, N-sulfonyloxyimides and oxime-O-sulfonates. Illustrative preferred photoacid generators include triphenylsulfonium p-toluenesulfonate, triphenylsulfonium camphorsulfonate, triphenylsulfonium pentafluorobenzenesulfonate, triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfonium 4-(p-toluenesulfonyloxy)benzenesulfonate, triphenylsulfonium 2,4,6-triisopropylbenzenesulfonate, 4-tert-butoxyphenyldiphenylsulfonium p-toluenesulfonate, 4-tert-butoxyphenyldiphenylsulfonium camphorsulfonate, 4-tert-butoxyphenyldiphenylsulfonium 4-(p-toluenesulfonyloxy)benzenesulfonate, 4-tert-butylphenyldiphenylsulfonium camphorsulfonate, tris(4-methylphenyl)sulfonium camphorsulfonate, tris(4-tert-butylphenyl)sulfonium camphorsulfonate, bis(tert-butylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(2,4-dimethylphenylsulfonyl)diazomethane, bis(4-n-hexyloxyphenylsulfonyl)diazomethane, bis(2-methyl-4-n-hexyloxyphenylsulfonyl)diazomethane, bis(2,5-dimethyl-4-n-hexyloxyphenylsulfonyl)diazomethane, bis(3,5-dimethyl-4-n-hexyloxyphenylsulfonyl)diazomethane, bis(2-methyl-5-isopropyl-4-n-hexyloxy)phenylsulfonyldiazomethane, bis(4-tert-butylphenylsulfonyl)diazomethane, N-camphorsulfonyloxy-5-norbornene-2,3-dicarboxylic acid imide, N-p-toluenesulfonyloxy-5-norbornene-2,3-dicarboxylic acid imide, (5-(10-camphorsulfonyl)oxyimino-5H-thiophen-2, -ylidene)(2-methylphenyl)acetonitrile, and (5-(p-toluenesulfonyl)oxyimino-5H-thiophen-2-ylidene)(2-methylphenyl)acetonitrile.

[0153] When the photoacid generator (B) is added to the ArF laser resist composition, preference is given to sulfonium salts and oxime-O-sulfonates. Illustrative preferred photoacid generators include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium pentafluoroethanesulfonate, triphenylsulfonium heptafluoropropanesulfonate, triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfonium tridecafluorohexanesulfonate, triphenylsulfonium heptadecafluorooctanesulfonate, triphenylsulfonium perfluoro(4-ethylcyclohexane)sulfonate, 4-methylphenyldiphenylsulfonium nonafluorobutanesulfonate, 2-oxo-2-phenylethylthiacyclopentanium nonafluorobutanesulfonate, 4-tert-butylphenyldiphenylsulfonium nonafluorobutanesulfonate, 4-tert-butylphenyldiphenylsulfonium perfluoro(4-ethylcyclohexane)sulfonate, 4-tert-butylphenyldiphenylsulfonium heptafluorooctanesulfonate, triphenylsulfonium 1,1-difluoro-2-naphthylethanesulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-2-(norbornan-2-yl)-ethanesulfonate, triphenylsulfonium 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium 1,1,3,3,3-pentafluoro-2-(pivaloyloxy)-propanesulfonate, triphenylsulfonium 2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium 2-(2-naphthoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium adamantanemethoxycarbonyldifluoromethanesulfonate, triphenylsulfonium 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, triphenylsulfonium methoxycarbonyldifluoromethanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium 1,1,3,3,3-pentafluoro-2-(pivaloyloxy)propanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-(2-naphthoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium adamantanemethoxycarbonyldifluoromethanesulfonate, 4-tert-butylphenyldiphenylsulfonium 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, 4-tert-butylphenyldiphenylsulfonium methoxycarbonyldifluoromethanesulfonate, 2-oxo-2-phenylethylthiacyclopentanium 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-oxo-2-phenylethylthiacyclopentanium 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium perfluoro(1,3-propylenebissulfonyl)imide, triphenylsulfonium bis(pentafluoroethylsulfonyl)imide, 2-(2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)pentyl)fluorene, 2-(2,2,3,3,4,4-pentafluoro-1-(nonafluorobutylsulfonyloxyimino)butyl)fluorene, 2-(2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl)fluorene, 2-(2,2,3,3,4,4,5,5-octafluoro-1-(2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonyloxyimino)pentyl)fluorene, 2-(2,2,3,3,4,4-pentafluoro-1-(2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonyloxyimino)butyl)fluorene, and 2-(2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl)fluorene.

[0154] When the photoacid generator (B) is added to the ArF immersion lithography resist composition, preference is given to sulfonium salts and oxime-O-sulfonates. Illustrative preferred photoacid generators include triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfonium tridecafluorohexanesulfonate, triphenylsulfonium heptadecafluorooctanesulfonate, triphenylsulfonium perfluoro(4-ethylcyclohexane)sulfonate, 4-methylphenyldiphenylsulfonium nonafluorobutanesulfonate, 2-oxo-2-phenylethylthiacyclopentanium nonafluorobutanesulfonate, 4-tert-butylphenyldiphenylsulfonium nonafluorobutanesulfonate, 4-tert-butylphenyldiphenylsulfonium perfluoro(4-ethylcyclohexane)sulfonate, 4-tert-butylphenyldiphenylsulfonium heptafluorooctanesulfonate, triphenylsulfonium 1,1-difluoro-2-naphthylethanesulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-2-(norbornan-2-yl)-ethanesulfonate, triphenylsulfonium 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium 1,1,3,3,3-pentafluoro-2-(pivaloyloxy)-propanesulfonate, triphenylsulfonium 2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium 2-(2-naphthoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium adamantanemethoxycarbonyldifluoromethanesulfonate, triphenylsulfonium 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, triphenylsulfonium methoxycarbonyldifluoromethanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium 1,1,3,3,3-pentafluoro-2-(pivaloyloxy)propanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-(2-naphthoyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-(1-adamantanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium 2-hydroxy-1,1,3,3,3-pentafluoropropanesulfonate, 4-tert-butylphenyldiphenylsulfonium adamantanemethoxycarbonyldifluoromethanesulfonate, 4-tert-butylphenyldiphenylsulfonium 1-(3-hydroxymethyladamantane)methoxycarbonyldifluoromethanesulfonate, 4-tert-butylphenyldiphenylsulfonium methoxycarbonyldifluoromethanesulfonate, 2-oxo-2-phenylethylthiacyclopentanium 2-benzoyloxy-1,1,3,3,3-pentafluoropropanesulfonate, 2-oxo-2-phenylethylthiacyclopentanium 2-cyclohexanecarbonyloxy-1,1,3,3,3-pentafluoropropanesulfonate, triphenylsulfonium perfluoro(1,3-propylenebissulfonyl)imide, triphenylsulfonium bis(pentafluoroethylsulfonyl)imide, 2-(2,2,3,3,4,4,5,5-octafluoro-1-(nonafluorobutylsulfonyloxyimino)pentyl)fluorene, 2-(2,2,3,3,4,4-pentafluoro-1-(nonafluorobutylsulfonyloxyimino)butyl)fluorene, 2-(2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl)fluorene, 2-(2,2,3,3,4,4,5,5-octafluoro-1-(2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonyloxyimino)pentyl)fluorene, 2-(2,2,3,3,4,4-pentafluoro-1-(2-(cyclohexanecarbonyloxy)-1,1,3,3,3-pentafluoropropanesulfonyloxyimino)butyl)fluorene, and 2-(2,2,3,3,4,4,5,5,6,6-decafluoro-1-(nonafluorobutylsulfonyloxyimino)hexyl)fluorene.

[0155] In the chemically amplified resist composition, the photoacid generator (B) may be added in any desired amount as long as the objects of the invention are not compromised. An appropriate amount of the photoacid generator (B) is 0.1 to 10 parts, and more preferably 0.1 to 5 parts by weight per 100 parts by weight of the base resin in the composition. Too high a proportion of the photoacid generator (B) may give rise to problems of degraded resolution and foreign matter upon development and resist film peeling. The photoacid generators may be used alone or in admixture of two or more. The transmittance of the resist film can be controlled by using an photoacid generator having a low transmittance at the exposure wavelength and adjusting the amount of the photoacid generator added.

[0156] It is noted that an acid diffusion controlling function may be provided when two or more photoacid generators are used in admixture provided that one photoacid generator is an onium salt capable of generating a weak acid. Specifically, in a system using the inventive polymer capable of generating a strong acid in combination with an onium salt capable of generating a weak acid (e.g., non-fluorinated sulfonic acid or carboxylic acid), if the strong acid generated from the inventive polymer upon exposure to high-energy radiation collides with the unreacted onium salt having a weak acid anion, then a salt exchange occurs whereby the weak acid is released and an onium salt having a strong acid anion is formed. In this course, the strong acid is exchanged into the weak acid having a low catalysis, incurring apparent deactivation of the acid for enabling to control acid diffusion.

[0157] If an onium salt capable of generating a strong acid and an onium salt capable of generating a weak acid are used in admixture, an exchange from the strong acid to the weak acid as above can take place, but it never happens that the weak acid collides with the unreacted onium salt capable of generating a strong acid to induce a salt exchange. This is because of a likelihood of an onium cation forming an ion pair with a stronger acid anion.

[0158] In the resist composition of the invention, there may be added a compound which is decomposed with an acid to generate another acid, that is, acid amplifier compound. For these compounds, reference should be made to J. Photopolym. Sci. and Tech., 8, 43-44, 45-46 (1995), and ibid., 9, 29-30 (1996). Examples of the acid amplifier compound include tert-butyl-2-methyl-2-tosyloxymethyl acetoacetate and 2-phenyl-2-(2-tosyloxyethyl)-1,3-dioxolane, but are not limited thereto. Of well-known photoacid generators, many of those compounds having poor stability, especially poor thermal stability exhibit an acid amplifier-like behavior.

[0159] In the resist composition of the invention, an appropriate amount of the acid amplifier compound is up to 2 parts, and especially up to 1 part by weight per 100 parts by weight of the base resin. Excessive amounts of the acid amplifier compound make diffusion control difficult, leading to degradation of resolution and pattern profile.

[0160] Organic Solvent

[0161] The organic solvent (C) used herein may be any organic solvent in which the base resin, acid generator, and other components are soluble. Illustrative, non-limiting, examples of the organic solvent include ketones such as cyclohexanone and methyl amyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono-tert-butyl ether acetate; and lactones such as γ-butyrolactone. These solvents may be used alone or in combinations of two or more thereof. Of the above organic solvents, it is recommended to use diethylene glycol dimethyl ether, 1-ethoxy-2-propanol, propylene glycol monomethyl ether acetate, and mixtures thereof because the acid generator is most soluble therein.

[0162] An appropriate amount of the organic solvent used is about 200 to 1,000 parts, especially about 400 to 800 parts by weight per 100 parts by weight of the base resin.

[0163] Quencher

[0164] A quencher (D) may be optionally used in the resist composition of the invention. The term “quencher” as used herein has a meaning generally known in the art and refers to a compound capable of suppressing the rate of diffusion when the acid generated by the acid generator diffuses within the resist film. The inclusion of quencher facilitates adjustment of resist sensitivity and holds down the rate of acid diffusion within the resist film, resulting in better resolution. In addition, it suppresses changes in sensitivity following exposure and reduces substrate and environment dependence, as well as improving the exposure latitude and the pattern profile.

[0165] Examples of suitable quenchers include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds with carboxyl group, nitrogen-containing compounds with sulfonyl group, nitrogen-containing compounds with hydroxyl group, nitrogen-containing compounds with hydroxyphenyl group, alcoholic nitrogen-containing compounds, amide derivatives, imide derivatives, carbamate derivatives, and ammonium salts.

[0166] Examples of suitable primary aliphatic amines include ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, pentylamine, tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine, ethylenediamine, and tetraethylenepentamine. Examples of suitable secondary aliphatic amines include dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine, dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine, N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, and N,N-dimethyltetraethylenepentamine. Examples of suitable tertiary aliphatic amines include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tripentylamine, tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, tridodecylamine, tricetylamine, N,N,N′,N′-tetramethylmethylenediamine, N,N,N′,N′-tetramethylethylenediamine, and N,N,N′,N′-tetramethyltetraethylenepentamine.

[0167] Examples of suitable mixed amines include dimethylethylamine, methylethylpropylamine, benzylamine, phenethylamine, and benzyldimethylamine. Examples of suitable aromatic and heterocyclic amines include aniline derivatives (e.g., aniline, N-methylaniline, N-ethylaniline, N-propylaniline, N,N-dimethylaniline, N,N-bis(hydroxyethyl)aniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, ethylaniline, propylaniline, dimethylaniline, 2,6-diisopropylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline, 2,6-dinitroaniline, 3,5-dinitroaniline, and N,N-dimethyltoluidine), diphenyl(p-tolyl)amine, methyldiphenylamine, triphenylamine, phenylenediamine, naphthylamine, diaminonaphthalene, pyrrole derivatives (e.g., pyrrole, 2H-pyrrole, 1-methylpyrrole, 2,4-dimethylpyrrole, 2,5-dimethylpyrrole, and N-methylpyrrole), oxazole derivatives (e.g., oxazole and isooxazole), thiazole derivatives (e.g., thiazole and isothiazole), imidazole derivatives (e.g., imidazole, 4-methylimidazole, and 4-methyl-2-phenylimidazole), pyrazole derivatives, furazane derivatives, pyrroline derivatives (e.g., pyrroline and 2-methyl-1-pyrroline), pyrrolidine derivatives (e.g., pyrrolidine, N-methylpyrrolidine, pyrrolidinone, and N-methylpyrrolidone), imidazoline derivatives, imidazolidine derivatives, pyridine derivatives (e.g., pyridine, methylpyridine, ethylpyridine, propylpyridine, butylpyridine, 4-(1-butylpentyl)pyridine, dimethylpyridine, trimethylpyridine, triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridine, 4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine, 4-pyrrolidinopyridine, 2-(1-ethylpropyl)pyridine, aminopyridine, and dimethylaminopyridine), pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives, pyrazoline derivatives, pyrazolidine derivatives, piperidine derivatives, piperazine derivatives, morpholine derivatives, indole derivatives, isoindole derivatives, 1H-indazole derivatives, indoline derivatives, quinoline derivatives (e.g., quinoline and 3-quinolinecarbonitrile), isoquinoline derivatives, cinnoline derivatives, quinazoline derivatives, quinoxaline derivatives, phthalazine derivatives, purine derivatives, pteridine derivatives, carbazole derivatives, phenanthridine derivatives, acridine derivatives, phenazine derivatives, 1,10-phenanthroline derivatives, adenine derivatives, adenosine derivatives, guanine derivatives, guanosine derivatives, uracil derivatives, and uridine derivatives.

[0168] Examples of suitable nitrogen-containing compounds with carboxyl group include aminobenzoic acid, indolecarboxylic acid, and amino acid derivatives (e.g. nicotinic acid, alanine, alginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine, methionine, phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic acid, and methoxyalanine). A typical nitrogen-containing compound with sulfonyl group is 3-pyridinesulfonic acid. Examples of suitable nitrogen-containing compounds with hydroxyl group, nitrogen-containing compounds with hydroxyphenyl group, and alcoholic nitrogen-containing compounds include 2-hydroxypyridine, aminocresol, 2,4-quinolinediol, 3-indolemethanol hydrate, monoethanolamine, diethanolamine, triethanolamine, N-ethyldiethanolamine, N,N-diethylethanolamine, triisopropanolamine, 2,2′-iminodiethanol, 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, 4-(2-hydroxyethyl)morpholine, 2-(2-hydroxyethyl)pyridine, 1-(2-hydroxyethyl)piperazine, 1-[2-(2-hydroxyethoxy)ethyl]piperazine, piperidine ethanol, 1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)-2-pyrrolidinone, 3-piperidino-1,2-propanediol, 3-pyrrolidino-1,2-propanediol, 8-hydroxyjulolidine, 3-quinuclidinol, 3-tropanol, 1-methyl-2-pyrrolidine ethanol, 1-aziridine ethanol, N-(2-hydroxyethyl)phthalimide, and N-(2-hydroxyethyl)isonicotinamide. Examples of suitable amide derivatives include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, and 1-cyclohexylpyrrolidone. Suitable imide derivatives include phthalimide, succinimide, and maleimide. Suitable carbamate derivatives include N-tert-butoxycarbonyl-N,N-dicyclohexylamine, N-tert-butoxycarbonylbenzimidazole, and oxazolidinone.

[0169] Suitable ammonium salts include pyridinium p-toluenesulfonate, triethylammonium p-toluenesulfonate, trioctylammonium p-toluenesulfonate, triethylammonium 2,4,6-triisopropylbenzenesulfonate, trioctylammonium 2,4,6-triisopropylbenzenesulfonate, triethylammonium camphorsulfonate, trioctylammonium camphorsulfonate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, tetramethylammonium p-toluenesulfonate, tetrabutylammonium p-toluenesulfonate, benzyltrimethylammonium p-toluenesulfonate, tetramethylammonium camphorsulfonate, tetrabutylammonium camphorsulfonate, benzyltrimethylammonium camphorsulfonate, tetramethylammonium 2,4,6-triisopropylbenzenesulfonate, tetrabutylammonium 2,4,6-triisopropylbenzenesulfonate, benzyltrimethylammonium 2,4,6-triisopropylbenzenesulfonate, tetramethylammonium acetate, tetrabutylammonium acetate, benzyltrimethylammonium acetate, tetramethylammonium benzoate, tetrabutylammonium benzoate, and benzyltrimethylammonium benzoate.

[0170] In addition, amine compounds of the following general formula (B)-1 may also be included alone or in admixture.
N(X)_n(Y)_3-n   (B)-1
In the formula, n is equal to 1, 2 or 3. The side chain X is independently selected from groups of the following general formulas (X)-1 to (X)-3. The side chain Y is independently hydrogen or a straight, branched or cyclic C₁-C₂₀ alkyl group in which some or all hydrogen atoms may be substituted by fluorine atoms and which may contain an ether or hydroxyl group. Two or three X may bond together to form a ring.

[0171]

[0172] In the formulas, R³⁰⁰, R³⁰² and R³⁰⁵ are independently straight or branched C₁-C₄ alkylene groups; R³⁰¹ and R³⁰⁴ are independently hydrogen or straight, branched or cyclic C₁-C₂₀ alkyl groups in which some or all hydrogen atoms may be substituted by fluorine atoms and which may contain at least one hydroxyl group, ether group, ester group or lactone ring; R³⁰³ is a single bond or a straight or branched C₁-C₄ alkylene group; R³⁰⁶ is a straight, branched or cyclic C₁-C₂₀ alkyl group in which some or all hydrogen atoms may be substituted by fluorine atoms and which may contain at least one hydroxyl group, ether group, ester group or lactone ring.

[0173] Illustrative examples of the compounds of formula (B)-1 include, but are not limited to, tris(2-methoxymethoxyethyl)amine, tris{2-(2-methoxyethoxy)ethyl}amine, tris{2-(2-methoxyethoxymethoxy)ethyl}amine, tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine, tris{2-(1-ethoxypropoxy)ethyl}amine, tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine, 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, 4,7,13,18-tetraoxa-1,10-diazabicyclo[8.5.5]eicosane, 1,4,10,13-tetraoxa-7,16-diazabicyclooctadecane, 1-aza-12-crown-4, 1-aza-15-crown-5, 1-aza-18-crown-6, tris(2-formyloxyethyl)amine, tris(2-acetoxyethyl)amine, tris(2-propionyloxyethyl)amine, tris(2-butyryloxyethyl)amine, tris(2-isobutyryloxyethyl)amine, tris(2-valeryloxyethyl)amine, tris(2-pivaloyloxyethyl)amine, N,N-bis(2-acetoxyethyl)-2-(acetoxyacetoxy)ethylamine, tris(2-methoxycarbonyloxyethyl)amine, tris(2-tert-butoxycarbonyloxyethyl)amine, tris[2-(2-oxopropoxy)ethyl]amine, tris[2-(methoxycarbonylmethyl)oxyethyl]amine, tris[2-(tert-butoxycarbonylmethyloxy)ethyl]amine, tris[2-(cyclohexyloxycarbonylmethyloxy)ethyl]amine, tris(2-methoxycarbonylethyl)amine, tris(2-ethoxycarbonylethyl)amine, N,N-bis(2-hydroxyethyl)-2-(methoxycarbonyl)ethylamine, N,N-bis(2-acetoxyethyl)-2-(methoxycarbonyl)ethylamine, N,N-bis(2-hydroxyethyl)-2-(ethoxycarbonyl)ethylamine, N,N-bis(2-acetoxyethyl)-2-(ethoxycarbonyl)ethylamine, N,N-bis(2-hydroxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine, N,N-bis(2-acetoxyethyl)-2-(2-methoxyethoxycarbonyl)ethylamine, N,N-bis(2-hydroxyethyl)-2-(2-hydroxyethoxycarbonyl)ethylamine, N,N-bis(2-acetoxyethyl)-2-(2-acetoxyethoxycarbonyl)ethylamine, N,N-bis(2-hydroxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine, N,N-bis(2-acetoxyethyl)-2-[(methoxycarbonyl)methoxycarbonyl]-ethylamine, N,N-bis(2-hydroxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine, N,N-bis(2-acetoxyethyl)-2-(2-oxopropoxycarbonyl)ethylamine, N,N-bis(2-hydroxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)-ethylamine, N,N-bis(2-acetoxyethyl)-2-(tetrahydrofurfuryloxycarbonyl)-ethylamine, N,N-bis(2-hydroxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxy-carbonyl]ethylamine, N,N-bis(2-acetoxyethyl)-2-[(2-oxotetrahydrofuran-3-yl)oxy-carbonyl]ethylamine, N,N-bis(2-hydroxyethyl)-2-(4-hydroxybutoxycarbonyl)ethylamine, N,N-bis(2-formyloxyethyl)-2-(4-formyloxybutoxycarbonyl)-ethylamine, N,N-bis(2-formyloxyethyl)-2-(2-formyloxyethoxycarbonyl)-ethylamine, N,N-bis(2-methoxyethyl)-2-(methoxycarbonyl)ethylamine, N-(2-hydroxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine, N-(2-acetoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine, N-(2-hydroxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine, N-(2-acetoxyethyl)-bis[2-(ethoxycarbonyl)ethyl]amine, N-(3-hydroxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine, N-(3-acetoxy-1-propyl)-bis[2-(methoxycarbonyl)ethyl]amine, N-(2-methoxyethyl)-bis[2-(methoxycarbonyl)ethyl]amine, N-butyl-bis[2-(methoxycarbonyl)ethyl]amine, N-butyl-bis[2-(2-methoxyethoxycarbonyl)ethyl]amine, N-methyl-bis(2-acetoxyethyl)amine, N-ethyl-bis(2-acetoxyethyl)amine, N-methyl-bis(2-pivaloyloxyethyl)amine, N-ethyl-bis[2-(methoxycarbonyloxy)ethyl]amine, N-ethyl-bis[2-(tert-butoxycarbonyloxy)ethyl]amine, tris(methoxycarbonylmethyl)amine, tris(ethoxycarbonylmethyl)amine, N-butyl-bis(methoxycarbonylmethyl)amine, N-hexyl-bis(methoxycarbonylmethyl)amine, and β-(diethylamino)-δ-valerolactone.

[0174] Also useful are one or more of cyclic structure-bearing amine compounds having the following general formula (B)-2.

[0175]
Herein X is as defined above, and R³⁰⁷ is a straight or branched C₂-C₂₀ alkylene group in which some or all hydrogen atoms may be substituted by fluorine atoms and which may contain one or more carbonyl, ether, ester or sulfide groups.

[0176] Illustrative examples of the cyclic structure-bearing amine compounds having formula (B)-2 include 1-[2-(methoxymethoxy)ethyl]pyrrolidine, 1-[2-(methoxymethoxy)ethyl]piperidine, 4-[2-(methoxymethoxy)ethyl]morpholine, 1-[2-[(2-methoxyethoxy)methoxy]ethyl]pyrrolidine, 1-[2-[(2-methoxyethoxy)methoxy]ethyl]piperidine, 4-[2-[(2-methoxyethoxy)methoxy]ethyl]morpholine, 2-[2-(2-methoxyethoxy)ethoxy]ethylmorpholine, 2-[2-(2-butoxyethoxy)ethoxy]ethylmorpholine, 2-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}ethylmorpholine, 2-{2-[2-(2-butoxyethoxy)ethoxy]ethoxy}ethylmorpholine, 2-(1-pyrrolidinyl)ethyl acetate, 2-piperidinoethyl acetate, 2-morpholinoethyl acetate, 2-(1-pyrrolidinyl)ethyl formate, 2-piperidinoethyl propionate, 2-morpholinoethyl acetoxyacetate, 2-(1-pyrrolidinyl)ethyl methoxyacetate, 4-[2-(methoxycarbonyloxy)ethyl]morpholine, 1-[2-(t-butoxycarbonyloxy)ethyl]piperidine, 4-[2-(2-methoxyethoxycarbonyloxy)ethyl]morpholine, methyl 3-(1-pyrrolidinyl)propionate, methyl 3-piperidinopropionate, methyl 3-morpholinopropionate, methyl 3-(thiomorpholino)propionate, methyl 2-methyl-3-(1-pyrrolidinyl)propionate, ethyl 3-morpholinopropionate, methoxycarbonylmethyl 3-piperidinopropionate, 2-hydroxyethyl 3-(1-pyrrolidinyl)propionate, 2-acetoxyethyl 3-morpholinopropionate, 2-oxotetrahydrofuran-3-yl 3-(1-pyrrolidinyl)propionate, tetrahydrofurfuryl 3-morpholinopropionate, glycidyl 3-piperidinopropionate, 2-methoxyethyl 3-morpholinopropionate, 2-(2-methoxyethoxy)ethyl 3-(1-pyrrolidinyl)propionate, butyl 3-morpholinopropionate, cyclohexyl 3-piperidinopropionate, α-(1-pyrrolidinyl)methyl-γ-butyrolactone, β-piperidino-γ-butyrolactone, β-morpholino-δ-valerolactone, methyl 1-pyrrolidinylacetate, methyl piperidinoacetate, methyl morpholinoacetate, methyl thiomorpholinoacetate, ethyl 1-pyrrolidinylacetate, 2-methoxyethyl morpholinoacetate, 2-morpholinoethyl 2-methoxyacetate, 2-morpholinoethyl 2-(2-methoxyethoxy)acetate, 2-morpholinoethyl 2-[2-(2-methoxyethoxy)ethoxy]acetate, 2-morpholinoethyl hexanoate, 2-morpholinoethyl octanoate, 2-morpholinoethyl decanoate, 2-morpholinoethyl laurate, 2-morpholinoethyl myristate, 2-morpholinoethyl palmitate, 2-morpholinoethyl stearate, 2-morpholinoethyl cyclohexanecarboxylate, and 2-morpholinoethyl adamantanecarboxylate.

[0177] Also, one or more of cyano-bearing amine compounds having the following general formulae (B)-3 to (B)-6 may be added.

[0178]
Herein, X, R³⁰⁷ and n are as defined in formula (B)-1, and R³⁰⁸ and R³⁰⁹ each are independently a straight or branched C₁-C₄ alkylene group.

[0179] Illustrative examples of the cyano-bearing amine compounds having formulae (B)-3 to (B)-6 include 3-(diethylamino)propiononitrile, N,N-bis(2-hydroxyethyl)-3-aminopropiononitrile, N,N-bis(2-acetoxyethyl)-3-aminopropiononitrile, N,N-bis(2-formyloxyethyl)-3-aminopropiononitrile, N,N-bis(2-methoxyethyl)-3-aminopropiononitrile, N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile, methyl N-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropionate, methyl N-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropionate, methyl N-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropionate, N-(2-cyanoethyl)-N-ethyl-3-aminopropiononitrile, N-(2-cyanoethyl)-N-(2-hydroxyethyl)-3-aminopropiononitrile, N-(2-acetoxyethyl)-N-(2-cyanoethyl)-3-aminopropiononitrile, N-(2-cyanoethyl)-N-(2-formyloxyethyl)-3-aminopropiononitrile, N-(2-cyanoethyl)-N-(2-methoxyethyl)-3-aminopropiononitrile, N-(2-cyanoethyl)-N-[2-(methoxymethoxy)ethyl]-3-aminopropiononitrile, N-(2-cyanoethyl)-N-(3-hydroxy-1-propyl)-3-aminopropiononitrile, N-(3-acetoxy-1-propyl)-N-(2-cyanoethyl)-3-aminopropiononitrile, N-(2-cyanoethyl)-N-(3-formyloxy-1-propyl)-3-aminopropiononitrile, N-(2-cyanoethyl)-N-tetrahydrofurfuryl-3-aminopropiononitrile, N,N-bis(2-cyanoethyl)-3-aminopropiononitrile, diethylaminoacetonitrile, N,N-bis(2-hydroxyethyl)aminoacetonitrile, N,N-bis(2-acetoxyethyl)aminoacetonitrile, N,N-bis(2-formyloxyethyl)aminoacetonitrile, N,N-bis(2-methoxyethyl)aminoacetonitrile, N,N-bis[2-(methoxymethoxy)ethyl]aminoacetonitrile, methyl N-cyanomethyl-N-(2-methoxyethyl)-3-aminopropionate, methyl N-cyanomethyl-N-(2-hydroxyethyl)-3-aminopropionate, methyl N-(2-acetoxyethyl)-N-cyanomethyl-3-aminopropionate, N-cyanomethyl-N-(2-hydroxyethyl)aminoacetonitrile, N-(2-acetoxyethyl)-N-(cyanomethyl)aminoacetonitrile, N-cyanomethyl-N-(2-formyloxyethyl)aminoacetonitrile, N-cyanomethyl-N-(2-methoxyethyl)aminoacetonitrile, N-cyanomethyl-N-[2-(methoxymethoxy)ethyl)aminoacetonitrile, N-cyanomethyl-N-(3-hydroxy-1-propyl)aminoacetonitrile, N-(3-acetoxy-1-propyl)-N-(cyanomethyl)aminoacetonitrile, N-cyanomethyl-N-(3-formyloxy-1-propyl)aminoacetonitrile, N,N-bis(cyanomethyl)aminoacetonitrile, 1-pyrrolidinepropiononitrile, 1-piperidinepropiononitrile, 4-morpholinepropiononitrile, 1-pyrrolidineacetonitrile, 1-piperidineacetonitrile, 4-morpholineacetonitrile, cyanomethyl 3-diethylaminopropionate, cyanomethyl N,N-bis(2-hydroxyethyl)-3-aminopropionate, cyanomethyl N,N-bis(2-acetoxyethyl)-3-aminopropionate, cyanomethyl N,N-bis(2-formyloxyethyl)-3-aminopropionate, cyanomethyl N,N-bis(2-methoxyethyl)-3-aminopropionate, cyanomethyl N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate, 2-cyanoethyl 3-diethylaminopropionate, 2-cyanoethyl N,N-bis(2-hydroxyethyl)-3-aminopropionate, 2-cyanoethyl N,N-bis(2-acetoxyethyl)-3-aminopropionate, 2-cyanoethyl N,N-bis(2-formyloxyethyl)-3-aminopropionate, 2-cyanoethyl N,N-bis(2-methoxyethyl)-3-aminopropionate, 2-cyanoethyl N,N-bis[2-(methoxymethoxy)ethyl]-3-aminopropionate, cyanomethyl 1-pyrrolidinepropionate, cyanomethyl 1-piperidinepropionate, cyanomethyl 4-morpholinepropionate, 2-cyanoethyl 1-pyrrolidinepropionate, 2-cyanoethyl 1-piperidinepropionate, and 2-cyanoethyl 4-morpholinepropionate.

[0180] Also included are amine compounds having an imidazole structure and a polar functional group, represented by the general formula (B)-7.

[0181]
Herein, R³¹⁰ is a straight, branched or cyclic C₂-C₂₀ alkyl group in which some or all hydrogen atoms may be substituted by fluorine atoms and which has one or more polar functional groups. The polar functional group is selected from among hydroxyl, carbonyl, ester, ether, sulfide, carbonate, cyano and acetal groups and mixtures thereof. R³¹¹, R³¹² and R³¹³ are each independently a hydrogen atom, a straight, branched or cyclic C₁-C₁₀ alkyl group, aryl group or aralkyl group.

[0182] Also included are amine compounds having a benzimidazole structure and a polar functional group, represented by the general formula (B)-8.

[0183]
Herein, R³¹⁴ is a hydrogen atom, a straight, branched or cyclic C₁-C₁₀ alkyl group, aryl group or aralkyl group. R³¹⁵ is a straight, branched or cyclic C₁-C₂₀ alkyl group in which some or all hydrogen atoms may be substituted by fluorine atoms and which has one or more polar functional groups. The alkyl group contains as the polar functional group at least one group selected from among ester, acetal and cyano groups, and may additionally contain at least one group selected from among hydroxyl, carbonyl, ether, sulfide and carbonate groups.

[0184] Further included are heterocyclic nitrogen-containing compounds having a polar functional group, represented by the general formulae (B)-9 and (B)-10.

[0185]
Herein, A is a nitrogen atom or ≡C—R³²². B is a nitrogen atom or ≡C—R³²³. R³¹⁶ is a straight, branched or cyclic C₂-C₂₀ alkyl group in which some or all hydrogen atoms may be substituted by fluorine atoms and which has one or more polar functional groups, the polar functional group being selected from among hydroxyl, carbonyl, ester, ether, sulfide, carbonate, cyano and acetal groups and mixtures thereof. R³¹⁷, R³¹⁸, R³¹⁹ and R³²⁰ are each independently a hydrogen atom, a straight, branched or cyclic C₁-C₁₀ alkyl group or aryl group, or a pair of R³¹⁷ and R³¹⁸ and a pair of R³¹⁹ and R³²⁰, taken together, may form a benzene, naphthalene or pyridine ring. R³²¹ is a hydrogen atom, a straight, branched or cyclic C₁-C₁₀ alkyl group or aryl group. R³²² and R³²³ each are a hydrogen atom, a straight, branched or cyclic C₁-C₁₀ alkyl group or aryl group, or a pair of R³²¹ and R³²³, taken together, may form a benzene or naphthalene ring.

[0186] Also included are organic nitrogen-containing compounds having an aromatic carboxylic acid ester structure, represented by the general formulae (B)-11 to (B)-14.

[0187]
Herein R³²⁴ is a C₆-C₂₀ aryl group or C₄-C₂₀ hetero-aromatic group, in which some or all hydrogen atoms may be replaced by halogen atoms, straight, branched or cyclic C₁-C₂₀ alkyl groups, C₆-C₂₀ aryl groups, C₇-C₂₀ aralkyl groups, C₁-C₂₀ alkoxy groups, C₁-C₁₀ acyloxy groups or C₁-C₁₀ alkylthio groups. R³²⁵ is CO₂R³²⁶, OR³²⁷ or cyano group. R³²⁶ is a C₁-C₁₀ alkyl group, in which some methylene groups may be replaced by oxygen atoms. R³²⁷ is a C₁-C₁₀ alkyl or acyl group, in which some methylene groups may be replaced by oxygen atoms. R³²⁸ is a single bond, methylene, ethylene, sulfur atom or —O(CH₂CH₂O)_n— group wherein n is 0, 1, 2, 3 or 4. R³²⁹ is hydrogen, methyl, ethyl or phenyl. X is a nitrogen atom or CR³³⁰. Y is a nitrogen atom or CR³³¹. Z is a nitrogen atom or CR³³². R³³⁰, R³³¹ and R³³² are each independently hydrogen, methyl or phenyl. Alternatively, a pair of R³³⁰ and R³³¹ or a pair of R³³¹ and R³³² may bond together to form a C₆-C₂₀ aromatic ring or C₂-C₂₀ hetero-aromatic ring.

[0188] Further included are amine compounds of 7-oxanorbornane-2-carboxylic ester structure, represented by the general formula (B)-15.

[0189]
Herein R³³³ is hydrogen or a straight, branched or cyclic C₁-C₁₀ alkyl group. R³³⁴ and R³³⁵ are each independently a C₁-C₂₀ alkyl group, C₆-C₂₀ aryl group or C₇-C₂₀ aralkyl group, which may contain one or more polar functional groups selected from among ether, carbonyl, ester, alcohol, sulfide, nitrile, amine, imine, and amide and in which some hydrogen atoms may be replaced by halogen atoms. R³³⁴ and R³³⁵, taken together, may form a heterocyclic or hetero-aromatic ring of 2 to 20 carbon atoms.

[0190] The quencher is preferably formulated in an amount of 0.001 to 2 parts, and especially 0.01 to 1 part by weight, per 100 parts by weight of the base resin. Less than 0.001 phr of the quencher may achieve no addition effect whereas more than 2 phr may lead to too low a sensitivity.

[0191] Surfactant

[0192] Optionally, the resist composition of the invention may further comprise (E) a surfactant which is commonly used for improving the coating characteristics. The surfactant may be added in conventional amounts so long as this does not compromise the objects of the invention.

[0193] Illustrative, non-limiting, examples of the surfactant include nonionic surfactants, for example, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether, polyoxyethylene alkylaryl ethers such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether, polyoxyethylene polyoxypropylene block copolymers, sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, and sorbitan monostearate, and polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; fluorochemical surfactants such as EFTOP EF301, EF303 and EF352 (JEMCO Inc.), Megaface F171, F172, F173, R08 and R30 (Dai-Nippon Ink & Chemicals, Inc.), Fluorad FC430, FC431, FC-4430 and FC-4432 (Sumitomo 3M Co., Ltd.), Asahiguard AG710, Surflon S-381, S-382, SC101, SC102, SC103, SC104, SC105, SC106, Surfynol E1004, KH-10, KH-20, KH-30 and KH-40 (Asahi Glass Co., Ltd.); organosiloxane polymers KP341, X-70-092 and X-70-093 (Shin-Etsu Chemical Co., Ltd.), acrylic acid or methacrylic acid Polyflow No. 75 and No. 95 (Kyoeisha Ushi Kagaku Kogyo Co., Ltd.). Inter alia, FC430, Surflon S-381, Surfynol E1004, KH-20 and KH-30 are preferred. These surfactants may be used alone or in admixture.

[0194] In the chemically amplified resist composition of the invention, the surfactant is preferably added in an amount of up to 2 parts, and especially up to 1 part by weight, per 100 parts by weight of the base resin.

[0195] In an embodiment wherein the resist composition of the invention is used in immersion lithography using water, especially in the absence of a resist protective coating, a surfactant may be added to the resist composition, the surfactant having a function to collect near the resist surface after spin coating to prevent or reduce water penetration or leaching. This surfactant is a polymeric surfactant which is insoluble in water and soluble in an alkaline developer, and preferably is highly water repellent and improves water slippage. Exemplary polymeric surfactants are those comprising monomeric units represented by the following formula.

[0196]
wherein R¹ is each independently hydrogen, fluorine, methyl or trifluoromethyl,

[0197] R⁸ is each independently hydrogen or a straight, branched or cyclic C₁-C₂₀ alkyl or fluoroalkyl group, or plural R⁸ in a common monomer may bond together to form a ring with the carbon atom to which they are attached, and in this case, they collectively stand for a straight, branched or cyclic alkylene or fluoroalkylene group having 2 to 20 carbon atoms in total,

[0198] R⁹ is fluorine or hydrogen, or R⁹ may bond with R¹⁰ to form a ring having 3 to 10 carbon atoms in total, especially cycloaliphatic ring, with the carbon atom to which they are attached,

[0199] R¹⁰ is a straight, branched or cyclic C₁-C₆ alkylene group in which one or more hydrogen atoms may be replaced by fluorine atoms,

[0200] R¹¹ is a straight or branched C₁-C₁₀ alkyl group in which one or more hydrogen atoms are replaced by fluorine atoms, or R¹⁰ and R¹¹ may bond together to form a ring with the carbon atoms to which they are attached, and in this case, they collectively stand for a trivalent organic group having 2 to 12 carbon atoms in total, and especially an alkylene group with one hydrogen atom eliminated in which one or more hydrogen atoms may be replaced by fluorine atoms,

[0201] R¹² is a single bond or a C₁-C₄ alkylene group,

[0202] R¹³ is each independently a single bond, —O— or —CR¹R¹—,

[0203] R¹⁴ is a straight or branched C₁-C₄ alkylene group, or R¹⁴ may bond with R⁸ within a common monomer to form a ring having 4 to 7 carbon atoms in total, especially cycloaliphatic ring, with the carbon atom to which they are attached,

[0204] R¹⁶ is 1,2-ethylene, 1,3-propylene or 1,4-butylene,

[0205] Rf is a straight perfluoroalkyl group of 3 to 6 carbon atoms, or 3H-perfluoropropyl, 4H-perfluorobutyl, 5H-perfluoropentyl or 6H-perfluorohexyl,

[0206] X² is each independently —C(═O)—O—, —O—, or —C(═O)—R—¹⁵—C(═O)—O— wherein R¹⁵ is a straight, branched or cyclic C₁-C₁₀ alkylene group, and

[0207] the subscripts are numbers in the range: 0≦(a-1)<1, 0≦(a-2)<1, 0≦(a-3)<1, 0<(a-1)+(a-2)+(a-3)<1, 0≦b<1, 0≦c<1, and 0<(a-1)+(a-2)+(a-3)+b+c≦1.

[0208] In the resist composition, the polymeric surfactant is added in an amount of 0.001 to 20 parts, and preferably 0.01 to 10 parts by weight, per 100 parts by weight of the base resin.

[0209] In an embodiment wherein the inventive polymer is used in a chemically amplified negative resist composition, the polymer must comprise recurring units having substituent groups capable of forming a crosslinked structure with the aid of an acid crosslinker, as well as the recurring units having formula (2). Specifically, suitable units include recurring units derived from acrylic acid, methacrylic acid, hydroxystyrene (any site available for substitution), and hydroxyvinylnaphthalene (any site available for substitution), but are not limited thereto.

[0210] Besides the polymer described above, an alkali-soluble resin may be added. Suitable resins include, but are not limited to, poly(p-hydroxystyrene), poly(m-hydroxystyrene), poly(4-hydroxy-2-methylstyrene), poly(4-hydroxy-3-methylstyrene), poly(α-methyl-p-hydroxystyrene), partially hydrogenated p-hydroxystyrene copolymers, p-hydroxystyrene/α-methyl-p-hydroxystyrene copolymers, p-hydroxystyrene/α-methylstyrene copolymers, p-hydroxystyrene/styrene copolymers, p-hydroxystyrene/m-hydroxystyrene copolymers, p-hydroxystyrene/styrene copolymers, p-hydroxystyrene/acrylic acid copolymers, p-hydroxystyrene/methacrylic acid copolymers, p-hydroxystyrene/methyl acrylate copolymers, p-hydroxystyrene/acrylic acid/methyl methacrylate copolymers, p-hydroxystyrene/methyl acrylate copolymers, p-hydroxystyrene/methacrylic acid/methyl methacrylate copolymers, polymethacrylic acid, polyacrylic acid, acrylic acid/methyl acrylate copolymers, methacrylic acid/methyl methacrylate copolymers, acrylic acid/maleimide copolymers, methacrylic acid/maleimide copolymers, p-hydroxystyrene/acrylic acid/maleimide copolymers, and p-hydroxystyrene/methacrylic acid/maleimide copolymers.

[0211] The inventive polymer and the other alkali-soluble resin are preferably blended in a weight ratio from 100:0 to 10:90, more preferably from 100:0 to 20:80. If the blend ratio of the inventive polymer is below this range, the resist composition would become poor in some of the desired properties. The properties of the resist composition can be adjusted by properly changing the blend ratio of the inventive polymer.

[0212] The alkali-soluble resin is not limited to one type and a mixture of two or more other polymers may be added. The use of plural polymers allows for easy adjustment of resist properties.

[0213] Crosslinker

[0214] Component (H) is an acid crosslinker capable of forming a crosslinked structure under the action of an acid. Typical crosslinkers are compounds having at least two hydroxymethyl, alkoxymethyl, epoxy or vinyl ether groups within a molecule. Substituted glycoluril derivatives, urea derivatives, and hexa(methoxymethyl)melamine compounds are suitable as the crosslinker in chemically amplified negative resist compositions. Examples include N,N,N′,N′-tetramethoxymethylurea, hexamethoxymethylmelamine, tetraalkoxymethyl-substituted glycoluril compounds such as tetrahydroxymethyl-substituted glycoluril and tetramethoxymethylglycoluril, and condensates of phenolic compounds such as substituted or unsubstituted bis(hydroxymethylphenol) compounds and bisphenol A with epichlorohydrin. Especially preferred crosslinkers are 1,3,5,7-tetraalkoxymethylglycolurils such as 1,3,5,7-tetramethoxymethylglycoluril, 1,3,5,7-tetrahydroxymethylglycoluril, 2,6-dihydroxymethyl-p-cresol, 2,6-dihydroxymethylphenol, 2,2′,6,6′-tetrahydroxymethyl-bisphenol A, 1,4-bis[2-(2-hydroxypropyl)]benzene, N,N,N′,N′-tetramethoxymethylurea, and hexamethoxymethylmelamine.

[0215] In the chemically amplified resist composition, an appropriate amount of acid crosslinker (H) is, though not limited thereto, 1 to 20 parts, and especially 5 to 15 parts by weight per 100 parts by weight of the base resin. The crosslinkers may be used alone or in admixture of two or more.

[0216] While the resist composition of the invention typically comprises a polymer or base resin, acid generator, organic solvent and quencher as described above, there may be added optional other ingredients such as dissolution inhibitors, acidic compounds, stabilizers, and dyes. Optional ingredients may be added in conventional amounts so long as this does not compromise the objects of the invention.

[0217] In forming a pattern from the resist composition of the invention, any well-known lithography may be employed. For example, the composition is applied onto a substrate for integrated circuitry fabrication (e.g., Si, SiO₂, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective coating, etc.) or a substrate for mask circuitry fabrication (e.g., Cr, CrO, CrON, MoSi, etc.) by a suitable coating technique such as spin coating. The coating is prebaked on a hot plate at a temperature of 60 to 150° C. for about 1 to 10 minutes, preferably 80 to 140° C. for 1 to 5 minutes, to form a resist film of 0.05 to 2.0 μm thick. A patterning mask having the desired pattern is then placed over the resist film, and the film exposed through the mask to an electron beam or to high-energy radiation such as deep-UV, excimer laser or x-ray in a dose of about 1 to 200 mJ/cm², and preferably about 10 to 100 mJ/cm². Alternatively, pattern formation may be performed by writing with an electron beam directly (not through a mask). Light exposure may be done by a conventional exposure process or in some cases, by an immersion process of providing liquid impregnation between the mask and the resist. In the case of immersion lithography, a protective coating which is insoluble in water may be used. The resist film is then post-exposure baked (PEB) on a hot plate at 60 to 150° C. for 1 to 5 minutes, and preferably at 80 to 140° C. for 1 to 3 minutes. Finally, development is carried out using as the developer an aqueous alkali solution, such as a 0.1 to 5 wt %, preferably 2 to 3 wt %, aqueous solution of tetramethylammonium hydroxide (TMAH), this being done by a conventional method such as dip, puddle, or spray development for a period of 0.1 to 3 minutes, and preferably 0.5 to 2 minutes. These steps result in the formation of the desired pattern on the substrate. Of the various types of high-energy radiation that may be used, the resist composition of the invention is best suited to fine pattern formation with, in particular, deep-UV having a wavelength of 250 to 190 nm, excimer laser, x-ray, or electron beam. The desired pattern may not be obtainable outside the upper and lower limits of the above range.

[0218] The water-insoluble protective coating which is used in the immersion lithography is to prevent the resist coating from being leached and to improve water slippage at the coating surface and is generally divided into two types. The first type is an organic solvent-strippable protective coating which must be stripped, prior to alkaline development, with an organic solvent in which the resist coating is not dissolvable. The second type is an alkali-soluble protective coating which is soluble in an alkaline developer so that it can be removed simultaneously with the removal of solubilized areas of the resist coating. The protective coating of the second type is preferably of a material comprising a polymer having a 1,1,1,3,3,3-hexafluoro-2-propanol residue (which is insoluble in water and soluble in an alkaline developer) as a base in an alcohol solvent of at least 4 carbon atoms, an ether solvent of 8 to 12 carbon atoms or a mixture thereof. Alternatively, the aforementioned surfactant which is insoluble in water and soluble in an alkaline developer may be dissolved in an alcohol solvent of at least 4 carbon atoms, an ether solvent of 8 to 12 carbon atoms or a mixture thereof to form a material from which the protective coating of the second type is formed.

[0219] Any desired step may be added to the pattern forming process. For example, after a photoresist coating is formed, a step of rinsing with pure water (post-soaking) may be introduced to extract the acid generator or the like from the coating surface or wash away particles. After exposure, a step of rinsing (post-soaking) may be introduced to remove any water remaining on the coating after exposure.

[0220] Examples and Comparative Examples are given below by way of illustration and not by way of limitation.

[0221] Sulfonium salts having a polymerizable anion within the scope of the invention were synthesized according to the following formulation.

[0222] Diphenyl sulfoxide, 40 g (0.2 mole), was dissolved in 400 g of dichloromethane, which was stirred under ice cooling. At a temperature below 20° C., 65 g (0.6 mole) of trimethylsilyl chloride was added dropwise to the solution, which was allowed to mature for 30 minutes at the temperature. Then, a Grignard reagent which had been prepared from 14.6 g (0.6 mole) of metallic magnesium, 67.5 g (0.6 mole) of chlorobenzene and 168 g of tetrahydrofuran (THF) was added dropwise at a temperature below 20° C. The reaction solution was allowed to mature for one hour, after which 50 g of water at a temperature below 20° C. was added to quench the reaction. To this solution, 150 g of water, 10 g of 12N hydrochloric acid, and 200 g of diethyl ether were further added. The water layer was separated and washed with 100 g of diethyl ether, yielding an aqueous solution of triphenylsulfonium chloride. The compound in aqueous solution form was used in the subsequent reaction without further isolation.

[0223] The target compound was obtained by following the procedure of Synthesis Example 1 aside from using 4-tert-butylbromobenzene instead of the chlorobenzene in Synthesis Example 1 and increasing the amount of water for extraction.

[0224] The target compound was obtained by following the procedure of Synthesis Example 1 aside from using 4-tert-butoxychlorobenzene instead of the chlorobenzene in Synthesis Example 1, using dichloromethane containing 5 wt % of triethylamine as the solvent, and increasing the amount of water for extraction.

[0225] The target compound was obtained by following the procedure of Synthesis Example 1 aside from using bis(4-methylphenyl) sulfoxide instead of the diphenyl sulfoxide and 4-chlorotoluene instead of the chlorobenzene in Synthesis Example 1, and increasing the amount of water for extraction.

[0226] The target compound was obtained by following the procedure of Synthesis Example 1 aside from using bis(4-tert-butylphenyl) sulfoxide instead of the diphenyl sulfoxide and 4-tert-butylbromobenzene instead of the chlorobenzene in Synthesis Example 1, and increasing the amount of water for extraction.

[0227] A mixture of 84 g (0.5 mole) of tert-butylbenzene, 53 g (0.25 mole) of potassium iodate and 50 g of acetic anhydride was stirred under ice cooling. A mixture of 35 g of acetic anhydride and 95 g of conc. sulfuric acid was added dropwise thereto at a temperature below 30° C. The resulting solution was allowed to mature for 3 hours at room temperature and ice cooled again, after which 250 g of water was added dropwise to quench the reaction. The reaction solution was extracted with 400 g of dichloromethane. The organic layer was discolored by adding 6 g of sodium hydrogen sulfite. The organic layer was washed with 250 g of water three times. The washed organic layer was concentrated in vacuum, obtaining a crude target product. The product was used in the subsequent reaction without further purification.

[0228] 88.2 g (0.44 mole) of phenacyl bromide and 39.1 g (0.44 mole) of tetrahydrothiophene were dissolved in 220 g of nitromethane, which was stirred for 4 hours at room temperature. 800 g of water and 400 g of diethyl ether were added to the reaction solution whereupon the mixture separated into two layers. The aqueous layer was taken out, which was an aqueous solution of the target compound, phenacyltetrahydrothiophenium bromide.

[0229] 6.2 g (0.05 mole) of thioanisole and 6.9 g (0.055 mole) of dimethyl sulfate were stirred for 12 hours at room temperature. 100 g of water and 50 ml of diethyl ether were added to the reaction solution whereupon the mixture separated into two layers. The aqueous layer was taken out, which was an aqueous solution of the target compound, dimethylphenylsulfonium hydrogen sulfate.

[0230] 10.0 g of 1,1,3,3,3-pentafluoro-2-propan-2-yl benzoate, which had been synthesized by a conventional technique, was dispersed in 72 g of water, after which 12.0 g of sodium hydrogen sulfite and 1.24 g of benzoyl peroxide were added. The mixture was allowed to react at 85° C. for 65 hours. It was allowed to cool and combined with toluene, followed by separatory operation to separate a water layer. A saturated sodium chloride aqueous solution was added to the water layer whereupon white crystals settled out. The crystals were collected by filtration, washed with a small volume of saturated sodium chloride aqueous solution and then dried in vacuum, obtaining the target compound, sodium 2-benzoyloxy-1,1,3,3,3-pantafluoropropane-1-sulfonate. White crystals, 5.85 g (yield 43%).

[0231] To 50 g of dichloromethane were added an amount (corresponding to 0.011 mole) of the triphenylsulfonium chloride aqueous solution of Synthesis Example 1 and 3.6 g (0.01 mole) of sodium 2-benzoyloxy-1,1,3,3,3-pantafluoropropane-1-sulfonate synthesized in Synthesis Example 9, followed by stirring. The organic layer was separated and washed with 50 g of water three times. The organic layer was concentrated and 25 g of diethyl ether was added to the concentrate for crystallization. The crystals were filtered and dried, obtaining the target compound. White crystals, 4.5 g (yield 75%).

[0232] In 72 g of methanol was dissolved 34.4 g of triphenylsulfonium 2-benzoyloxy-1,1,3,3,3-pentafluoropropane-1-sulfonate synthesized in Synthesis Example 10. While the solution was stirred under ice cooling, 54.0 g of 5% sodium hydroxide solution was added dropwise at a temperature below 10° C. It was allowed to mature at the temperature for 4 hours. At a temperature below 10° C., 6.8 g of 12N hydrochloric acid was added to quench the reaction. The methanol was distilled off in vacuum, after which 270 g of dichloromethane was added to the residue. The organic layer was washed with 40 g of water three times. The organic layer was concentrated, and 60 g of diethyl ether was added to the concentrate for crystallization. The crystals were filtered and dried, obtaining the target compound. White crystals, 24.3 g (yield 85%).

[0233] Target compounds were synthesized as in Synthesis Examples 10 and 11 except that the onium salts prepared in Synthesis Examples 2 to 8 were used. The resulting onium salts PAG2 to PAG8 are shown below.

[0234]

[0235] In 200 g of dichloromethane was dissolved 49.0 g (0.1 mole) of triphenylsulfonium 1,1,3,3,3-pentafluoro-2-hydroxypropane-1-sulfonate synthesized in Synthesis Example 11. 10.1 g (0.10 mole) of triethylamine and 2.4 g (0.2 mole) of N,N-dimethylaminopyridine were added to the solution, which was stirred under ice cooling. To the solution, 10.0 g (0.10 mole) of methacrylic anhydride was added dropwise at a temperature below 10° C. It was allowed to mature for 15 minutes and combined with dilute hydrochloric acid whereupon the organic layer was separated. The organic layer was washed three times with 200 g of water and then concentrated. Diethyl ether was added to the concentrate for crystallization. The crystals were filtered, purified by silica gel column chromatography (elute: dichloromethane/methanol solvent mixture), recrystallized from diethyl ether again, filtered, and dried. The target compound was obtained as white crystals in an amount of 29 g (yield 51%). The target compound was analyzed by spectroscopy. The nuclear magnetic resonance spectra, ¹H-NMR and ¹⁹F-NMR are shown in FIGS. 1 and 2. The data of infrared (IR) absorption spectroscopy and time-of-flight mass spectrometry (TOFMS) are shown below.

IR Spectra (KBr, cm⁻¹)

[0236] 1737, 1477, 1448, 1375, 1334, 1257, 1213, 1186, 1170, 1137, 1068, 993, 902, 769, 755, 748, 686, 640, 520, 512, 503

TOFMS (MALDI)

[0237] Positive M⁺263 (corresponding to (C₆H₅)₃S⁺)

[0238] Negative M⁻297 (corresponding to CF₃CH(OCOC(CH₃)═CH₂)CF₂SO₃⁻)

[0239] Triphenylsulfonium 2-acryloyloxy-1,1,3,3,3-pentafluoro-1-propanesulfonate was synthesized by following the procedure of Synthesis Example 19 aside from using acryloyl chloride instead of the methacrylic anhydride in Synthesis Example 19.

[0240] Onium salts having a polymerizable anion were synthesized by following the procedure of Synthesis Examples 19 and 20 except that the onium salts (PAG2 to PAG8) in Synthesis Examples 12 to 18 were used instead of the triphenylsulfonium 1,1,3,3,3-pentafluoro-2-hydroxypropane-1-sulfonate used in Synthesis Examples 19 and 20.

[0241] Monomers 1 to 16 have the structural formulae shown below.

[0242]

[0243] Polymers within the scope of the invention were synthesized according to the following formulation.

[0244] A flask under a nitrogen blanket was charged with 7.60 g of triphenylsulfonium 1,1,3,3,3-pentafluoro-2-methacryloyloxypropane-1-sulfonate, 8.49 g 1-(7-oxanorbornan-2-yl)cyclopentyl methacrylate, 8.01 g of 3-hydroxy-1-adamantyl methacrylate, 9.12 g of 4,8-dioxatricyclo[4.2.1.0^3,7]nonan-5-on-2-yl methacrylate, 6.78 g of 3,5-bis(hexafluoro-2-hydroxy-2-propyl)cyclohexyl methacrylate, 1.11 g of 2,2′-azobisisobutyronitrile, and 70.0 g of methyl ethyl ketone (MEK), to form a monomer solution. Another flask under a nitrogen blanket was charged with 23.3 g of MEK, which was heated to 80° C. with stirring and to which the monomer solution was added dropwise over 4 hours. After the completion of dropwise addition, the polymerization solution was stirred for 2 hours while keeping the temperature of 80° C. It was then cooled to room temperature. With vigorous stirring, the polymerization solution was added dropwise to 400 g of hexane, after which the precipitated copolymer was filtered. The copolymer was washed two times with a solvent mixture of 45.4 g of MEK and 194.6 g of hexane and then dried in vacuum at 50° C. for 20 hours. 38.7 g of the copolymer was obtained in white powder form. The copolymer was analyzed by ¹³C-NMR, finding a copolymerization compositional ratio of 10/25/22/33/10 mol % in the order of the monomers described above.

[0245]

[0246] Resins shown in Table 1 were prepared by the same procedure as Example 2-1 except that the type and proportion of monomers were changed. The structure of the units in Table 1 is shown in Tables 2 to 6. Note that the ratio of incorporated units in Table 1 is expressed in a molar ratio.

[0247] Each of Polymers 36 to 40, 44 and 49 was obtained by preparing a polymer according to the formulation described above and dissolving it in a solvent mixture of methanol and tetrahydrofuran. Oxalic acid was added to the solution whereupon deprotection reaction was allowed to run at 40° C. The reaction solution was neutralized with pyridine and purified by routine re-precipitation, obtaining a polymer having hydroxystyrene units.

[0248] Polymers 36 and 46 were reacted with 1-chloro-1-methoxy-2-methylpropane under basic conditions, obtaining the target Polymers 41 and 50.

[0249] With respect to the deprotection and protection of polyhydroxystyrene derivatives in Examples 2-36 to 2-41, reference should be made to JP-A 2004-115630 and JP-A 2005-8766.

[0250]

	TABLE 1
	Resin	Unit 1 (ratio)	Unit 2 (ratio)	Unit 3 (ratio)	Unit 4 (ratio)	Unit 5 (ratio)
Example 2-1	Polymer 1	PM-1 (0.10)	A-6M (0.25)	B-1M (0.22)	B-3M (0.33)	C-3M (0.10)
Example 2-2	Polymer 2	PM-1 (0.10)	A-6M (0.25)	B-1M (0.22)	B-6M (0.33)	C-3M (0.10)
Example 2-3	Polymer 3	PM-1 (0.10)	A-1M (0.25)	B-1M (0.22)	B-3M (0.33)	C-3M (0.10)
Example 2-4	Polymer 4	PM-1 (0.10)	A-1M (0.25)	B-1M (0.22)	B-6M (0.33)	C-3M (0.10)
Example 2-5	Polymer 5	PM-1 (0.10)	A-1M (0.35)	B-1M (0.22)	B-3M (0.33)
Example 2-6	Polymer 6	PM-1 (0.10)	A-1M (0.35)	B-1M (0.22)	B-5M (0.33)
Example 2-7	Polymer 7	PM-1 (0.10)	A-3M (0.35)	B-1M (0.22)	B-6M (0.33)
Example 2-8	Polymer 8	PM-1 (0.10)	A-3M (0.35)	B-1M (0.22)	B-4M (0.33)
Example 2-9	Polymer 9	PM-1 (0.10)	A-1M (0.25)	B-1M (0.22)	B-3M (0.33)	C-1M (0.10)
Example 2-10	Polymer 10	PM-1 (0.10)	A-5M (0.25)	B-1M (0.22)	B-3M (0.33)	C-1M (0.10)
Example 2-11	Polymer 11	PM-1 (0.10)	A-4M (0.35)	B-1M (0.22)	B-6M (0.33)
Example 2-12	Polymer 12	PM-1 (0.10)	A-4M (0.35)	B-1M (0.22)	B-3M (0.33)
Example 2-13	Polymer 13	PM-1 (0.10)	A-1M (0.25)	B-1M (0.22)	B-3M (0.33)	C-2M (0.10)
Example 2-14	Polymer 14	PM-1 (0.10)	A-1M (0.25)	B-1M (0.22)	B-3M (0.33)	C-4M (0.10)
Example 2-15	Polymer 15	PM-1 (0.10)	A-6M (0.25)	B-1M (0.22)	B-3M (0.33)	C-4M (0.10)
Example 2-16	Polymer 16	PM-1 (0.10)	A-3M (0.25)	B-1M (0.22)	B-3M (0.33)	C-4M (0.10)
Example 2-17	Polymer 17	PM-1 (0.10)	A-1M (0.20)	A-5M (0.15)	B-1M (0.15)	B-6M (0.20)
Example 2-18	Polymer 18	PM-1 (0.10)	A-3M (0.25)	B-1M (0.22)	B-6M (0.33)	B-7M (0.10)
Example 2-19	Polymer 19	PM-2 (0.10)	A-2M (0.35)	B-1M (0.22)	B-3M (0.33)
Example 2-20	Polymer 20	PM-1 (0.10)	A-1M (0.20)	A-2M (0.15)	B-1M (0.22)	B-3M (0.33)
Example 2-21	Polymer 21	PM-1 (0.10)	A-3M (0.25)	B-1M (0.22)	B-4M (0.33)	B-7M (0.10)
Example 2-22	Polymer 22	PM-1 (0.10)	A-1M (0.25)	B-1M (0.22)	B-4M (0.33)	B-7M (0.10)
Example 2-23	Polymer 23	PM-1 (0.10)	A-1M (0.35)	B-2M (0.22)	B-6M (0.33)
Example 2-24	Polymer 24	PM-1 (0.10)	A-2M (0.35)	B-1M (0.15)	B-6M (0.25)	C-3M (0.10)
Example 2-25	Polymer 25	PM-1 (0.10)	A-5M (0.25)	B-1M (0.22)	B-3M (0.33)	C-2M (0.10)
Example 2-26	Polymer 26	PM-1 (0.05)	A-6M (0.30)	B-1M (0.22)	B-3M (0.33)	C-3M (0.10)
Example 2-27	Polymer 27	PM-1 (0.05)	A-6M (0.30)	B-1M (0.22)	B-6M (0.33)	C-3M (0.10)
Example 2-28	Polymer 28	PM-1 (0.05)	A-1M (0.30)	B-1M (0.22)	B-3M (0.33)	C-1M (0.10)
Example 2-29	Polymer 29	PM-1 (0.05)	A-5M (0.30)	B-1M (0.22)	B-3M (0.33)	C-1M (0.10)
Example 2-30	Polymer 30	PM-1 (0.05)	A-3M (0.30)	B-1M (0.22)	B-6M (0.33)	B-7M (0.10)
Example 2-31	Polymer 31	PM-1 (0.20)	D-2 (0.80)
Example 2-32	Polymer 32	PM-1 (0.20)	D-2 (0.65)	D-5 (0.15)
Example 2-33	Polymer 33	PM-1 (0.20)	D-2 (0.65)	D-6 (0.15)
Example 2-34	Polymer 34	PM-1 (0.20)	D-2 (0.55)	D-4 (0.15)	D-7 (0.10)
Example 2-35	Polymer 35	PM-1 (0.20)	D-2 (0.55)	A-1M (0.15)	D-7 (0.10)
Example 2-36	Polymer 36	PM-1 (0.20)	D-1 (0.80)
Example 2-37	Polymer 37	PM-1 (0.20)	D-1 (0.65)	D-5 (0.15)
Example 2-38	Polymer 38	PM-1 (0.20)	D-1 (0.65)	D-6 (0.15)
Example 2-39	Polymer 39	PM-1 (0.20)	D-1 (0.55)	D-4 (0.15)	D-7 (0.10)
Example 2-40	Polymer 40	PM-1 (0.20)	D-1 (0.55)	A-1M (0.15)	D-7 (0.10)
Example 2-41	Polymer 41	PM-1 (0.20)	D-1 (0.55)	D-3 (0.15)
Example 2-42	Polymer 42	PM-1 (0.05)	A-1M (0.30)	C-4M (0.65)
Example 2-43	Polymer 43	PM-1 (0.05)	D-2 (0.55)	D-5 (0.20)	D-9 (0.20)
Example 2-44	Polymer 44	PM-1 (0.05)	D-1 (0.55)	D-5 (0.20)	D-8 (0.20)
Comparative Synthesis	Polymer 45		A-6M (0.35)	B-1M (0.22)	B-3M (0.33)	C-3M (0.10)
Example 1-1
Comparative Synthesis	Polymer 46		A-1M (0.35)	B-1M (0.25)	B-3M (0.45)
Example 1-2
Comparative Synthesis	Polymer 47		A-1M (0.35)	B-1M (0.22)	B-3M (0.33)	C-1M (0.10)
Example 1-3
Comparative Synthesis	Polymer 48		D-2 (1.0)
Example 1-4
Comparative Synthesis	Polymer 49		D-1 (1.0)
Example 1-5
Comparative Synthesis	Polymer 50		D-1 (0.75)	D-3 (0.25)
Example 1-6

[0251]

TABLE 2
PM-1	PA-1	PM-2

[0252]

TABLE 3
A-1M (R = CH3)	A-2M (R = CH3)	A-3M (R = CH3)	A-4M (R = CH3)	A-5M (R = CH3)	A-6M (R = CH3)
A-1A (R = H)	A-2A (R = H)	A-3A (R = H)	A-4A (R = H)	A-5A (R = H)	A-6A (R = H)

[0253]

TABLE 4
B-1M (R = CH3)	B-2M (R = CH3)	B-3M (R = CH3)	B-4M (R = CH3)
B-1A (R = H)	B-2A (R = H)	B-3A (R = H)	B-4A (R = H)
B-5M (R = CH3)	B-6M (R = CH3)	B-7M (R = CH3)
B-5A (R = H)	B-6A (R = H)	B-7A (R = H)

[0254]

TABLE 5
C-1M (R = CH3)	C-2M (R = CH3)	C-3M (R = CH3)	C-4M (R = CH3)	C-5M (R = CH3)
C-1A (R = H)	C-2A (R = H)	C-3A (R = H)	C-4A (R = H)	C-5A (R = H)

[0255]

TABLE 6
D-1	D-2	D-3	D-4
D-5	D-6	D-7	D-8	D-9

[0256] Preparation of Resist Compositions

[0257] Resist compositions were prepared by using inventive resins (Polymer 1 to 30, 41, 42 and 44, abbreviated P-01 to P-30, P-41, P-42 and P-44) or comparative resins (Polymers 45 to 47 and 50, abbreviated P-45 to P-47 and P-50) as the base resin, and dissolving the polymer, an acid generator (PAG), and a quencher (Base) in a solvent mixture (PGMEA and CyHO) in accordance with the recipe shown in Table 7. These compositions were each filtered through a Teflon® filter having a pore diameter 0.2 μm, thereby giving inventive resist solutions (R-01 to 35) and comparative resist solutions (R-60 to 63). Note that the solvent contained 0.01 wt % of surfactant KH-20 (Asahi Glass Co., Ltd.).

[0258]

	TABLE 7
		Resin	PAG	Base	Solvent 1	Solvent 2
	Resist	(pbw)	(pbw)	(pbw)	(pbw)	(pbw)
Example 3-1	R-01	P-01 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-2	R-02	P-02 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-3	R-03	P-03 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-4	R-04	P-04 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-5	R-05	P-05 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-6	R-06	P-06 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-7	R-07	P-07 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-8	R-08	P-08 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-9	R-09	P-09 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-10	R-10	P-10 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-11	R-11	P-11 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-12	R-12	P-12 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-13	R-13	P-13 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-14	R-14	P-14 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-15	R-15	P-15 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-16	R-16	P-16 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-17	R-17	P-17 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-18	R-18	P-18 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-19	R-19	P-19 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-20	R-20	P-20 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-21	R-21	P-21 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-22	R-22	P-22 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-23	R-23	P-23 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-24	R-24	P-24 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-25	R-25	P-25 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-26	R-26	P-26 (80)	PAG-1 (3.3)	Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-27	R-27	P-27 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-28	R-28	P-28 (80)	PAG-1 (3.3)	Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-29	R-29	P-29 (80)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-30	R-30	P-30 (80)	PAG-1 (3.3)	Base-1 (0.94)	PGMEA (560)	CyHO (240)
Example 3-31	R-31	P-01 (40)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
		P-30 (40)
Example 3-32	R-32	P-41 (80)		Base-1 (0.30)	PGMEA (560)	EL (240)
Example 3-33	R-33	P-01 (40)		Base-1 (0.94)	PGMEA (560)	CyHO (240)
		P-45 (40)
Example 3-34	R-34	P-42 (5)	PAG-1 (3.3)	Base-1 (0.94)	PGMEA (560)	CyHO (240)
		P-45 (75)
Example 3-35	R-35	P-44 (80)		Base-1 (0.30)	PGMEA (560)	EL (240)
Comparative Example 2-1	R-60	P-42 (80)	PAG-1 (4.4)	Base-1 (0.94)	PGMEA (560)	CyHO (240)
Comparative Example 2-2	R-61	P-43 (80)	PAG-1 (4.4)	Base-1 (0.94)	PGMEA (560)	CyHO (240)
Comparative Example 2-3	R-62	P-44 (80)	PAG-1 (4.4)	Base-1 (0.94)	PGMEA (560)	CyHO (240)
Comparative Example 2-4	R-63	P-47 (80)	PAG-1 (10.0)	Base-1 (0.30)	PGMEA (560)	EL (240)

[0259] The acid generator, quencher (base) and solvent shown in Table 7 have the following meanings.

• [0260] PAG-1: triphenylsulfonium nonafluorobutanesulfonate
• [0261] Base-1: tri(2-methoxymethoxyethyl)amine
• [0262] PGMEA: 1-methoxyisopropyl acetate
• [0263] CyHO: cyclohexanone
• [0264] EL: ethyl lactate
  Evaluation of Resolution and Mask Fidelity on ArF Lithography

[0265] Each of inventive resist compositions (R-01 to 31, 33 and 34) and comparative resist compositions (R-60 to 61) was spin coated on a silicon wafer having an antireflective coating (ARC-29A, Nissan Chemical Co., Ltd.) of 78 nm thick and baked at 100° C. for 60 seconds, forming a resist film of 170 nm thick. The wafer was exposed by means of an ArF excimer laser stepper 307E (Nikon Corp., NA 0.85, σ 0.93/0.70, ¾ annular illumination, 6% halftone mask), post-exposure baked (PEB) at 110° C. for 60 seconds, and puddle developed with a 2.38 wt % tetramethylammonium hydroxide aqueous solution for 30 seconds, forming a 1:1 line-and-space pattern and a 1:10 isolated line pattern. The patterned wafer was observed under a top-down scanning electron microscope (TDSEM). The optimum exposure (Eop) was defined as the exposure dose (mJ/cm²) which provided a 1:1 resolution at the top and bottom of a 80-nm 1:1 line-and-space pattern. The maximum resolution of the resist was defined as the minimum line width (on-mask size, in increments of 5 nm) of a 1:1 line-and-space pattern that was resolved and separated at the optimum exposure, with smaller values indicating better resolution. The 1:10 isolated line pattern at the optimum exposure was also observed for determining an actual on-wafer size of the isolated line pattern with an on-mask size of 130 nm, which was reported as mask fidelity (on-wafer size, a larger size being better).

[0266] Table 8 tabulates the test results (maximum resolution and mask fidelity) of the inventive and comparative resist compositions.

[0267]

	TABLE 8
			Maximum	Mask
		Eop	resolution	fidelity
	Resist	(mJ/cm2)	(nm)	(nm)
Example 4-1	R-01	33	75	75
Example 4-2	R-02	35	75	75
Example 4-3	R-03	30	70	80
Example 4-4	R-04	32	70	80
Example 4-5	R-05	30	75	78
Example 4-6	R-06	31	75	80
Example 4-7	R-07	32	75	80
Example 4-8	R-08	30	70	75
Example 4-9	R-09	32	75	78
Example 4-10	R-10	27	70	70
Example 4-11	R-11	29	75	70
Example 4-12	R-12	28	75	70
Example 4-13	R-13	32	70	75
Example 4-14	R-14	30	70	78
Example 4-15	R-15	35	70	75
Example 4-16	R-16	32	75	80
Example 4-17	R-17	30	70	80
Example 4-18	R-18	32	70	78
Example 4-19	R-19	33	75	75
Example 4-20	R-20	31	70	80
Example 4-21	R-21	30	75	75
Example 4-22	R-22	33	75	75
Example 4-23	R-23	30	70	78
Example 4-24	R-24	35	70	80
Example 4-25	R-25	28	75	75
Example 4-26	R-26	35	75	70
Example 4-27	R-27	36	75	75
Example 4-28	R-28	30	75	75
Example 4-29	R-29	27	70	75
Example 4-30	R-30	31	70	75
Example 4-31	R-31	30	75	75
Example 4-32	R-33	38	70	75
Example 4-33	R-34	35	75	70
Comparative Example 3-1	R-60	41	80	60
Comparative Example 3-2	R-60	48	80	65
Comparative Example 3-3	R-61	31	80	65

[0268] It is seen from the results of Table 8 that the resist compositions within the scope of the invention have improved resolution and mask fidelity when processed by ArF excimer laser lithography. The data of Comparative Examples in Table 8 reveal that prior art resist compositions satisfy either one or none of resolution and mask fidelity. It has been demonstrated that resist compositions comprising polymers comprising recurring units derived from the polymerizable anion-bearing sulfonium salts of the invention are improved in resist properties over the prior art resist compositions.

Evaluation of Resolution on EB Lithography

[0269] The inventive resist composition (R-32, R-35) or comparative resist composition (R-63) was spin coated on a 8-inch silicon wafer having an organic antireflective coating (DUV-44, Brewer Science) of 610 Å thick and baked at 100° C. for 60 seconds, forming a resist film of 2,000 Å thick. The wafer was exposed by means of an EB lithography system HL-800D (Hitachi High-Technologies Co, Ltd.) at an accelerating voltage of 50 keV, post-exposure baked (PEB) at 120° C. for 60 seconds, and developed in a 2.38 wt % TMAH aqueous solution to form a positive pattern.

[0270] The pattern was evaluated as follows. The optimum exposure (sensitivity, Eop) was defined as the exposure dose (μC/cm²) which provided a 1:1 resolution at the top and bottom of a 0.12-μm line-and-space pattern. The maximum resolution of the resist was defined as the minimum line width of a line-and-space pattern that was resolved and separated at the optimum exposure. The profile of the resolved resist pattern was evaluated by observing a cross section of the resist under a SEM. The post-exposure delay (PED) in vacuum was evaluated by exposing the coated wafer on an EB lithography system, holding it in the vacuum system for 24 hours, thereafter effecting PEB and development. The size of lines of a 0.12-μm line-and-space pattern was measured and a percent change thereof was calculated. If the line size increased by 0.012 μm, the change is reported as +10%. A smaller change indicates better stability. The test results are shown in Table 9.

[0271]

	TABLE 9
				Line size
	Eop	Resolution	Pattern	change
	(μC/cm2)	(μm)	profile	by PED
Example 4-34	18	0.08	Rectangular	0
Example 4-35	20	0.08	Rectangular	0
Comparative	25	0.10	Somewhat	+10%
Example 3-4			rounded top

[0272] It is evident from Table 9 that the resist composition of the invention is also improved in resolution and vacuum PED when processed by EB lithography. The resist composition is expected to perform equally when processed by the EUV or KrF lithography using polyhydroxystyrene derivatives.

Measurement of Leach-Outs

[0273] The resist solutions (R-01, R-03, R-33, R-34 and Comparative R-60 to R-62) were spin coated on silicon substrates, then baked at 120° C. for 60 seconds to give photoresist films having a thickness of 120 nm. Using an ArF scanner S305B (Nikon Corp.), the entire surface of the photoresist film was irradiated through an open frame at an energy dose of 50 mJ/cm². Then a true circle ring of Teflon® having an inner diameter of 10 cm was placed on the resist film, 10 mL of deionized water was carefully injected inside the ring, and the resist film was kept in contact with water at room temperature for 60 seconds. Thereafter, the water was recovered, and a concentration of PAG anion in the water was measured by an LC-MS analyzer (Agilent). The anion concentration measured indicates an amount of anions leached out for 60 seconds. The results are shown in Table 10.

[0274]

	TABLE 10
	Resist solution	Anion leach-out (ppb)
Example 5-1	R-01	undetected
Example 5-2	R-03	undetected
Example 5-3	R-33	undetected
Example 5-4	R-34	10
Comparative Example 4-1	R-60	30
Comparative Example 4-2	R-61	35
Comparative Example 4-3	R-62	30

[0275] As is evident from the foregoing results, the photoresist films formed from the resist compositions of the invention are effective for preventing the PAG component from being leached out in water when processed by the immersion lithography using water. It is expected that the resist compositions of the invention undergo little change in pattern profile when processed by the immersion lithography and cause minimal damage to the exposure system.

[0276] Japanese Patent Application No. 2006-292023 is incorporated herein by reference.

[0277] Although some preferred embodiments have been described, many modifications and variations may be made thereto in light of the above teachings. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without departing from the scope of the appended claims.