Alkylated Aminoalkylpiperazine Surfactants and Their Use in Photoresist Developers

The invention relates to the use of alkylated aminoalkylpiperazines to reduce the surface tension in water-based systems and in particular as a wetting agent in aqueous photoresist developer and electronics cleaning compositions.

The ability to reduce the surface tension of water is of great importance in waterborne coatings, inks, adhesives, and agricultural formulations because decreased surface tension translates to enhanced substrate wetting in actual formulations. Surface tension reduction in water-based systems is generally achieved through the addition of surfactants. Performance attributes resulting from the addition of surfactants include enhanced surface coverage, fewer defects, and more uniform distribution. Equilibrium surface tension performance is important when the system is at rest. However, the ability to reduce surface tension under dynamic conditions is of great importance in applications where high surface creation rates are utilized. Such applications include spraying, rolling and brushing of coatings or spraying of agricultural formulations, or high speed gravure or ink-jet printing. Dynamic surface tension is a fundamental quantity which provides a measure of the ability of a surfactant to reduce surface tension and provide wetting under such high speed application conditions.

Traditional nonionic surfactants such as alkylphenol or alcohol ethoxylates, and ethylene oxide (EO)/propylene oxide (PO) copolymers have excellent equilibrium surface tension performance but are generally characterized as having poor dynamic surface tension reduction. In contrast, certain anionic surfactants such as sodium dialkyl sulfosuccinates can provide good dynamic results, but these are very foamy and impart water sensitivity to the finished coating. The problem of foaming is particularly troublesome in aqueous photoresist developers used in semiconductor fabrication.

The demands of semiconductor manufacture have required the use of high performance surfactants and wetting agents in photoresist developer formulations. As line features shrink to smaller sizes and photoresist substrate materials become more aliphatic in nature (i.e. having lower surface energy), aqueous developer solutions are being formulated with surface tension reducing agents. Another requirement for these developers is that they have a low tendency to foam. This is accentuated by the movement toward larger wafer sizes. Low foam formation is particularly important when using spray-puddle techniques because microbubble entrainment during spreading of the solution over the photoresist surface can lead to defects. Surfactants that have been used in the past to increase wetting of the photoresist typically lead to higher foam formation. For the most part the industry has focused on the effect of surfactant on photoresist performance, such as contrast, critical dimension, and feature sharpness. Although the cleaning ability of underlying substrates is enhanced by typical surfactants, foam formation still remains a problem.

There is a need for a family of surfactants which provide good equilibrium and dynamic surface tension properties, are low-foaming, are liquids at room temperature to facilitate handling, are stable under basic conditions and would be widely accepted in waterborne coating, ink, adhesive, fountain solution, agricultural and electronics cleaning formulations.

The importance of reducing equilibrium and dynamic surface tension in applications such as coatings, inks, adhesives, fountain solutions, agricultural formulations and electronics cleaning compositions, e.g., aqueous developer solutions for making semiconductor devices, is well-appreciated in the art.

Low dynamic surface tension is of great importance in the application of waterborne coatings. In an article, Schwartz, J. "The Importance of Low Dynamic Surface Tension in Waterborne Coatings", Journal of Coatings Technology, September 1992, there is a discussion of surface tension properties in waterborne coatings and a discussion of dynamic surface tension in such coatings. Equilibrium and dynamic surface tension were evaluated for several surface active agents. It is pointed out that low dynamic surface tension is an important factor in achieving superior film formation in waterborne coatings. Dynamic coating application methods require surfactants with low dynamic surface tensions in order to prevent defects such as retraction, craters, and foam.

Efficient application of agricultural products is also highly dependent on the dynamic surface tension properties of the formulation. In an article, Wirth, W.; Storp, S.; Jacobsen, W. "Mechanisms Controlling Leaf Retention of Agricultural Spray Solutions"; Pestic. Sci. 1991, 33, 411-420, the relationship between the dynamic surface tension of agricultural formulations and the ability of these formulations to be retained on a leaf was studied. These workers observed a good correlation between retention values and dynamic surface tension, with more effective retention of formulations exhibiting low dynamic surface tension.

Low dynamic surface tension is also important in high-speed printing as discussed in the article "Using Surfactants to Formulate VOC Compliant Waterbased Inks", Medina, S. W.; Sutovich, M. N. Am. Ink Maker 1994, 72 (2), 32-38. In this article, it is stated that equilibrium surface tensions (ESTs) are pertinent only to ink systems at rest. EST values, however, are not good indicators of performance in the dynamic, high speed printing environment under which the ink is used. Dynamic surface tension is a more appropriate property. This dynamic measurement is an indicator of the ability of the surfactant to migrate to a newly created ink/substrate interface to provide wetting during high speed printing.

Tetramethylammonium hydroxide (TMAH) is the chemical of choice in aqueous alkaline solutions for developing photoresists according to Microlithography, Science and Technology, edited by J. R. Sheats and B. W. Smith, Marcel Dekker, Inc., 1998, pp 551-553. Surfactants are added to the aqueous TMAH solutions to reduce development time and scumming and to improve surface wetting.

U.S. Pat. No. 5,098,478 discloses water-based ink compositions comprising water, a pigment, a nonionic surfactant and a solubilizing agent for the nonionic surfactant. Dynamic surface tension in ink compositions for publication gravure printing must be reduced to a level of about 25 to 40 dynes/cm to assure that printability problems will not be encountered.

U.S. Pat. No. 5,562,762 discloses an aqueous jet ink of water, dissolved dyes and a tertiary amine having two polyethoxylate substituents and that low dynamic surface tension is important in ink jet printing.

Although many monoalkylated aminoalkylpiperazine derivatives have been reported, it has not been recognized these materials possess surface active properties.

U.S. Pat. No. 3,007,929 discloses compounds of the form ##STR2## where R is a C8 to C16 linear alkyl group. Aqueous solutions of the C12 and C14 derivatives were effective sterilizing and disinfecting agents for food containers and kitchen utensils.

Zagudullin and Baimetov [J. Gen. Chem. USSR (Engl. Transl.) 1991, 61, 889-894; Zh. Obshch. Khim. 1991, 61, 978-985] report the alkylation of aminoethylpiperazine with ethyl chloride, allyl and methallyl chlorides, and chloropropenes. Depending on reaction conditions and the amount of alkylating agent used, mono-, di-, or tri-allyl and -methallyl derivatives can be formed: ##STR3## where R.dbd.H or CH.sub.3. The workers also report the formation of compounds of the form ##STR4## Alkylated aminoethylpiperazine compounds are said in this article to be important as catalysts in the synthesis of polyurethanes, polyamines, and epoxy resins. They are also said to be useful as selective solvents and as auxiliary agents in the textile industry.

JP 01 38,080 discloses a class of compounds of the structure ##STR5## where R.sup.1 can be C3-C8 linear or branched aliphatic,

R.sup.2 and R.sup.3 can be C3-C11 linear or branched aliphatic,

one of R.sup.2 or R.sup.3 must be H or C1-C2,

R.sup.4 is H or C1-C12 linear or branched alkyl,

m and n are each an integer from 0 to 3 with m+n.ltoreq.3,

p is an integer from 2-13.

Specifically shown is 1-[3-[4-methyl-1-(3-methylbutyl)pentylamino]propyl]piperazine. These compounds are disclosed as central nervous system agents and insecticides.

There are few references describing low foam surfactants in developer compositions. JP 10-319606 discloses that commercially available ethylene oxide (EO)/propylene oxide (PO) block polymers give good wetting and low foam.

JP 03-062034 discloses polyoxyalkylene dimethyl polysiloxanes as good surfactants with low foam in developer formulations. Polysiloxanes are known to rearrange or decompose under conditions of high pH.

Although there are a few references to the use of amines in photoresist developer compositions, they are not related to the use of surface active agents. U.S. Pat. No. 5,252,436 discloses the use of relatively high levels of amine additives (3-30 wt %) and U.S. Pat. No. 5,039,595 uses amine additives at levels of 5-50 wt %. Both of these disclosures appear to be using the amines to alter the bulk solvent properties of the developer solution.

U.S. Pat. No. 4,997,748 discloses cyclic nitrogen compounds at levels of 0.1 to 10 wt % to decrease scum formation and enhance image sharpness during photoresist development. Among the cyclic nitrogen compounds taught is the cyclic urea 1,3-dimethyl-2-imidazolidinone. Since the nitrogen compounds are not amphipathic, it is not likely that they will lower surface tensions at low concentrations, and their utility appears to be based on properties other than surface tension reduction. 1,3-dimethyl-2-imidazolidinone is well known as a very good solvent and not as a surface-active material.

U.S. Pat. No. 4,828,965 discloses the use of lower alkanolamines (1-4 carbons) in combination with alcohols at concentrations of 0.40-5 wt %.

U.S. Pat. No. 4,741,989 discloses the use of small amounts of amines to modify the reaction chemistry of the quinonediazide photoactive compounds in photoresists, but only small chain amines are used and no surface active amines are cited.

U.S. Pat. No. 4,628,023 discloses water soluble amines as the alkali source for developer solutions. Because the preferred pH range is above 12.5, the use of organic amines would necessarily be at high concentrations.

JP 61-179651 discloses the use of amine-containing developer solutions with surface tensions of between 25 and 50 dyne/cm. These surface tensions are achieved by the use of relatively large amounts of non-surface-active amines (3-5 wt %) in combination with tetramethylammonium hydroxide as the base.

This invention provides water-based compositions containing an organic or inorganic compound, particularly aqueous organic coating, ink, adhesive, fountain solution, agricultural and photoresist developing/electronics cleaning compositions, having reduced equilibrium and dynamic surface tension by incorporation of an effective amount of an alkylated aminoalkylpiperazine compound of the following structure: ##STR6## where one of R.sup.1 and R.sup.2 is a C5-C14 alkyl or cycloalkyl group, preferably C6-C8 alkyl, and the other is H, or both of R.sup.1 and R.sup.2 are C5 to C8 alkyl groups, and n is 2 or 3. It is desirable that an aqueous solution of the alkylated aminoalkylpiperazine demonstrates a dynamic surface tension of less than 45 dynes/cm at a concentration of .ltoreq.5 wt % in water at 23.degree. C. and 1 bubble/second according to the maximum-bubble pressure method. The maximum-bubble-pressure method of measuring surface tension is described in Langmuir 1986, 2, 428-432, which is incorporated by reference.

By "water-based", "aqueous" or "aqueous medium" we mean, for purposes of this invention, a solvent or liquid dispersing medium which comprises at least 90 wt %, preferably at least 95 wt %, water. Obviously, and most preferably, an all water medium is also included. Also for purposes of the present invention, the terms "photoresist developing" and "electronics cleaning" are interchangeable.

Also provided is a method for lowering the equilibrium and dynamic surface tension of aqueous compositions by the incorporation of these alkylated aminoalkylpiperazine compounds.

Also provided is a method for applying a coating of a water-based inorganic or organic compound-containing composition to a surface to partially or fully coat the surface with the water-based composition, the composition containing an effective amount of an alkylated aminoalkylpiperazine compound of the above structure for reducing the dynamic surface tension of the water-based composition, and allowing the water to evaporate.

There is also provided a method for developing a photoresist after exposure to radiation by applying to the photoresist surface a water-based developer composition containing an effective amount of an alkylated aminoalkylpiperazine compound of the above structure for reducing the dynamic surface tension of the developer composition.

There are significant advantages associated with the use of these alkylated aminoalkylpiperazines in water-based organic coatings, inks, adhesives, fountain solutions, agricultural compositions and electronic cleaning compositions and these advantages include:

an ability to formulate water-borne coatings, inks, fountain solutions and agricultural compositions which may be applied to a variety of substrates with excellent wetting of substrate surfaces including contaminated and low energy surfaces;

an ability to provide a reduction in coating or printing defects such as orange peel and flow/leveling deficiencies;

an ability to produce water-borne coatings and inks which have low volatile organic content, thus making these surfactants environmentally favorable;

an ability to formulate coating and ink compositions capable of high speed application; and

an ability to formulate compositions which retain excellent dynamic surface tension properties under strongly basic, high temperature environments.

an ability to formulate low surface tension aqueous electronics cleaning and processing solutions, including photoresist developer solutions, for the semiconductor manufacturing industry with good wetting and extremely low foam.

Because of their excellent surfactant properties and the ability to control foam, these materials are likely to find use in many applications in which reduction in dynamic and equilibrium surface tension and low foam are important. Applications in which low foam is important include various wet-processing textile operations, such as dyeing of fibers, fiber souring, and kier boiling, where low-foaming properties would be particularly advantageous; they may also have applicability in soaps, water-based perfumes, shampoos, and various detergents where their marked ability to lower surface tension while simultaneously producing substantially no foam would be highly desirable.

The use of these materials in aqueous photoresist developer formulations is of particular importance because of their ability to provide all the advantages of surface tension lowering plus outstanding performance in reducing the formation of foam, even under extreme conditions, and doing so while maintaining good contrast for photoresist developing applications. Other applications in the electronics industry using aqueous processing media would also benefit from good dynamic wetting and low foam.

This invention relates to the use of compounds of the formula ##STR7## where one of R.sup.1 and R.sup.2 is a C5-C14 alkyl or cycloalkyl group and the other is H, or both of R.sup.1 and R.sup.2 are C5 to C8 alkyl groups, and n is 2 or 3, for the reduction of equilibrium and dynamic surface tension in water-based compositions containing an organic compound, particularly coating, ink, adhesive, agricultural and electronics processing compositions containing organic compounds such as polymeric resins, organic bases, herbicides, fungicides, insecticides or plant growth modifying agents. It is desirable that an aqueous solution of the alkylated aminoalkylpiperazine demonstrates a dynamic surface tension of less than 45 dynes/cm at a concentration of .ltoreq.5 wt % in water at 23.degree. C. and 1 bubble/second according to the maximum-bubble-pressure method. The maximum-bubble-pressure method of measuring surface tension is described in Langmuir 1986, 2, 428-432, which is incorporated by reference.

In one aspect of the invention the alkylated aminoalkylpiperazines of the above formula display excellent ability to reduce equilibrium and dynamic surface tension while producing substantially no foam.

These materials can be prepared by reductive alkylation of the parent aminoalkylpiperazines with aldehydes and ketones using well-established procedures. The essential aspects of the preparation are the reaction of an aldehyde or ketone with the aminoalkylpiperazine to make an imine or eneamine intermediate which then reacts with hydrogen in the presence of a suitable hydrogenation catalyst to form the corresponding saturated derivative: ##STR8## The imine or eneamine derivative may be preformed or may be prepared in situ.

The reductive alkylation procedure is the method of choice for the production of these materials, but the products may also be prepared by reaction of an aminoalkyl piperazine with an alkyl halide. This reaction is illustrated for the reaction of aminoethylpiperazine with an alkyl chloride: ##STR9## where in the product, at least one of R.sup.1 and R.sup.2 is R, and the other is either R or H.

Aminoalkylpiperazine starting materials which are suitable for use in the reductive alkylation reaction include compounds of the form ##STR10## where n is 2 or 3. Specific examples include aminoethyl piperazine and aminopropyl piperazine.

Alkyl groups which are suitable for use in this invention should have sufficient carbon number to confer surface activity (i.e. an ability to reduce the surface tension of water) to the material but not enough carbon to decrease the solubility to the extent that the ability of the material to reduce surface tension is insufficient for a particular application. In general, an increase in the carbon number increases the efficiency of the surfactant (i.e. less surfactant is required to obtain a given decrease in surface tension) but decreases its ability to reduce surface tension at high surface creation rates. The latter effect is a result of the fact that increased carbon number decreases the water solubility or critical micelle concentration (CMC) of the material, and consequently, diminishes the diffusive flux of surfactant to newly-created surface. Generally, in the practice of this invention, it is desirable to use alkylated aminoalkylpiperazines with a solubility limit or CMC from 0.001 to about 20 g/100 mL of the total aqueous formulation, preferably from 0.01 to 10 g/100 mL, and most preferably from 0.05 to 5 g/100 mL.

Monoalkylated derivatives should be substituted with alkyl groups containing five to 14 carbon atoms, preferably six to eight carbon atoms. Alkyl groups are most-preferably derived from reductive alkylation reactions of methyl isobutyl ketone and methyl isoamyl ketone because these products would be the most economical, but alkyl groups derived from C5 to C14 aldehydes or ketones are suitable. Specific examples of suitable aldehydes and ketones include 2-pentanone, 3-pentanone, pivaldehyde, methyl isopropyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, 2-hexanone, 3-hexanone, methyl tert-butyl ketone, ethyl isopropyl ketone, 2-methylhexanal, 2-heptanone, 3-heptanone, 4-heptanone, 2-octanone, 3-octanone, 4-octanone, 2-ethylhexanal, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, cyclodecanone, cyclododecanone, 2-dodecanone, 1-dodecanal, 2-tetradecanone, 8-tetradecanone, and so on. The alkyl groups may be linear or branched, and the point of attachment to nitrogen may be on either an internal or terminal carbon. The specific carbonyl compound chosen will depend on the surfactant properties required for a particular application. The alkyl groups for the monoalkylated derivatives may be attached to either the nitrogen present on the alkyl chain, or to the ring nitrogen. The use of mixtures of ring- and chain-alkylated aminoalkyl piperazines is preferred since then the synthesis and purification of the materials is simplified.

For dialkylated aminoalkyl piperazines, the alkyl groups may be the same or different, but should again contain sufficient carbon to confer surface activity, but not so much carbon that the solubility of the surfactant decreases to the extent that the ability of the surfactant to reduce the surface tension of water is insufficient for a particular application. In general, dialkylated aminoalkyl piperazines possessing alkyl groups with, in aggregate, a total of about 10 to 16 alkyl carbons are preferred. The alkyl substituents may be linear or branched, and the point of attachment to the nitrogen may be on either an internal or terminal carbon. The most preferred derivatives are those in which the alkyl groups are the same, because manufacture of these materials will be the most straightforward. Specific examples of suitable R.sub.1 and R.sub.2 include n-pentyl, 2-pentyl, 3-pentyl, isopentyl, n-hexyl, 2-hexyl, 3-hexyl, cyclohexyl , 2-(4-methylpentyl), 2-(5-methylhexyl), n-octyl, 2-octyl, 3-octyl, 2-dodecyl, cyclododecyl, and so on.

An amount of the aminoalkylpiperazine compound that is effective to reduce the equilibrium and/or dynamic surface tension of the water-based, organic compound-containing composition is added. Such effective amount may range from 0.001 to 20 g/100 mL, preferably 0.01 to 10 g/100 mL, and most preferably 0.05 to 5 g/100 mL of the aqueous composition. For water-based photoresist developer/electronics cleaning compositions effective amounts may range from 0.001 to 1 g/100 mL, preferably 0.002 to 0.8 g/100 mL, and most preferably 0.005 to 0.5 g/100 mL. Naturally, the most effective amount will depend on the particular application and the solubility and or critical micelle concentration of the alkylated aminoalkyl piperazine.

The alkylated aminoalkylpiperazines are suitable for use in an aqueous composition comprising in water an inorganic compound which is a mineral ore or a pigment or an organic compound which is a pigment, a polymerizable monomer, such as addition, condensation and vinyl monomers, an oligomeric resin, a polymeric resin, a detergent, a caustic cleaning agent, a dissolution agent such as tetramethylammonium hydroxide (TMAH), a herbicide, a fungicide, an insecticide, or a plant growth modifying agent.

The use of the dialkylated aminoalkyl piperazine as a surfactant is particularly advantageous in the developers for photoresists that are employed in the semiconductor industry. Such developers and their use are well known in the art and do not need to be described in detail. The improvement provided by this invention, which could not have been foreseen, involves the use in these developer formulations of certain alkylated aminoalkyl piperazine containing 5 to 14 carbon atoms in the alkyl group on the nitrogen atom and certain dialkylated aminoalkyl piperazine containing 5 to 8 carbon atoms in each alkyl group on the nitrogen atoms.

In the following water-based organic coating, ink, adhesive, fountain solution, agricultural and photoresist developer compositions containing an alkylated aminoalkylpiperazine according to the invention, the other listed components of such compositions are those materials well known to the workers in the relevant art.

A typical water-based protective or decorative organic coating composition to which the alkylated aminoalkylpiperazine surfactants of the invention may be added would comprise in an aqueous medium 30 to 80 wt % of a coating composition of the following components:

A typical water-based ink composition to which the alkylated aminoalkylpiperazine surfactants of the invention may be added would comprise in an aqueous medium 20 to 60 wt % of an ink composition of the following components:

A typical water-based agricultural composition to which the alkylated aminoalkylpiperazine surfactants of the invention may be added would comprise in an aqueous medium 0.01 to 80 wt % of an agricultural composition of the following components:

A typical water-based fountain solution composition to which the alkylated aminoalkylpiperazine surfactants of the invention may be added would comprise in an aqueous medium 30 to 70 wt % of a fountain solution composition containing the following components:

A typical water-based adhesive composition to which the alkylated aminoalkylpiperazine surfactants of the invention may be added would comprise in an aqueous medium 30 to 65 wt % of an adhesive composition containing the following components:

A typical water-based photoresist developer, or electronic cleaning, composition to which the alkylated aminoalkylpiperazine surfactants of the invention may be added would comprise an aqueous medium containing the following components:

Briefly, the process for manufacture of integrated circuits involves the application of a film of photoresist composition to a suitable substrate, such as a silicon wafer, which is then exposed to actinic radiation in a design pattern that is imposed upon the photoresist film. Depending upon whether the photoresist is positive or negative-working, the radiation either increases or decreases its solubility in a subsequently applied developer solution. Consequently, in a positive-working photoresist the areas masked from the radiation remain after development while the exposed areas are dissolved away. In the negative-working photoresist the opposite occurs. The surfactant of this invention can be used in developers for either type of photoresist. The character of the developer is very important in determining the quality of the circuits formed and precise control of developing is essential. To achieve better surface wetting by the developer is has been common to add surfactant to the formulation in order to reduce surface tension of the solution. This addition, however, can cause the developer to foam which leads to circuit defects. This foaming problem is also recognized in the art and considerable attention in the industry has been directed toward its solution.

The aqueous developer, or electronics cleaning, solutions in which use of the alkylated aminoalkyl piperazine is preferred are the aqueous solutions of tetramethylammonium hydroxide (TMAH). These developers are also well known in the art. Commercial developers usually contain low levels of surfactant on the order of 50 to 1000 ppm by weight. Surfactant level should not exceed that required to achieve the desired surface tension of the solution. For example, surface tensions of about 40 to 45 dynes/cm would be appropriate for novolac-based photoresist resins. Advanced resins that often incorporate aliphatic groups might require a developer with lower surface tension to enhance wetting. One of the advantages of the surfactants of this invention is that suitable surface tensions can be obtained at lower levels than is required by other wetting agents. This in itself is a step toward solving the foaming problem in the manufacture of microcircuitry.

This example illustrates the procedure for the preparation of the reductive alkylation product of 1-(2-aminoethyl)piperazine (AEP) and methyl isoamyl ketone (MIAK).

AEP (1.0 mole), MIAK (1.1 mole) and 10% Pd/C (4 wt % of total charge) were charged to a one liter stainless steel autoclave. The reactor was sealed and purged with nitrogen then hydrogen. The contents of the reactor were heated to 90.degree. C. under 7 bar (100 psig) H.sub.2. The pressure was increased to 55 bar (800 psig) and maintained throughout the reaction (6 hours) by the admission of hydrogen from a 1 gallon (3.79 L) ballast on demand by a dome regulator. The reactor contents were analyzed by GC/FID and found to be 77.9 area % monoalkylated and 19.2 area % dialkylated AEP. The monoalkylated product was isolated by distillation at 142-145.degree. C., 4.0 millibar (3 Torr). The dialkylated product was purified by distillation at 148-150.degree. C., 0.53 millibar (0.4 Torr).

The monoalkylated derivative (AEP/MIAK1) was identified by gas chromatography/mass spectrometry (gc-ms) and .sup.1 H and .sup.13 C nuclear magnetic resonance (NMR) spectroscopy as a 5.2:1 mixture of the chain and ring alkylated materials shown below. ##STR11##

The structure of the dialkylated material, was shown to be that below using the same analytical techniques: ##STR12##

This example illustrates the preparation of the reductive alkylation product of AEP and methyl amyl ketone (MAK).

AEP (1.25 mole), methyl amyl ketone (1.37 mole) and 10% Pd/C (3 wt % of total charge) were charged to a one liter stainless steel autoclave. The reactor was sealed and purged with nitrogen then hydrogen. The contents of the reactor were heated to 80.degree. C. under 7 bar (100 psig) H.sub.2. The pressure was increased to 55 bar (800 psig) and maintained throughout the reaction (5 hours) by the admission of hydrogen from a 1 gallon (3.79 L) ballast on demand by a dome regulator. The water of reaction was removed in vacuo and the crude product distilled through a 4 inch (10.2 cm) Vigreux column to give 208.4 g of AEP/MAK1 at 155-160.degree. C. and 14 mbar (11 torr) as a colorless liquid.

The product was confirmed to be a mixture of the two components shown below by gas chromatography/mass spectrometry (gc-ms) and .sup.1 H and .sup.13 C nuclear magnetic resonance (NMR) spectroscopy. .sup.13 C NMR showed that the mixture was composed of a 6:1 ratio of chain:ring alkylated material. ##STR13##

This example illustrates the procedure for the preparation of the reductive alkylation product of AEP and 2 equivalents of methyl isobutyl ketone (MIBK).

AEP (0.8 mole), methyl isobutyl ketone (1.6 mole) and 5% Pd/C (4 wt % of total charge) were charged to a one liter stainless steel autoclave and reacted as in Example 1 for 22 hours. The reactor contents were analyzed by GC/FID and found to be 97.9 area % dialkylated AEP. The product was purified by distillation at 152-154.degree. C., 2.7 millibar (2 Torr).

The structure of the product was confirmed to be that shown below by gas chromatography/mass spectrometry (gc-ms) and .sup.1 H and .sup.13 C nuclear magnetic resonance (NMR) spectroscopy. ##STR14##

The monoalkylated derivative was prepared using a procedure similar to that used for AEP/MIBK2, except that only 1.1 equivalents of MIBK was used. The product was purified by distillation at 102-104.degree. C., 1.0 torr. The structure of the product was confirmed by gas chromatography/mass spectrometry (gc-ms) and .sup.1 H and .sup.13 C nuclear magnetic resonance (NMR) spectroscopy. GC was used to establish that the product was comprised of a 3.3:1 mixture of chain and ring monoalkylated material. ##STR15##

This example illustrates the preparation of the reductive alkylation product of AEP and cyclododecanone (CDD).

AEP (0.4 mole), cyclododecanone (0.42 mole), tetrahydrofuran (100 mL) and 10% Pd/C (4 wt % of total charge) were charged to a one liter stainless steel autoclave. The reactor was sealed and purged with nitrogen then hydrogen. The contents of the reactor were heated to 90.degree. C. under 7 bar (100 psig) H.sub.2. The pressure was increased to 55 bar (800 psig) and maintained throughout the reaction (24 hours) by the admission of hydrogen from a 1 gallon (3.79 L) ballast on demand by a dome regulator. The reactor contents were cooled to ambient temperature and the catalyst removed by filtration. The solvent and water were removed in vacuo and the crude product distilled through a 4" (10.2 cm) Vigreux column to give a forecut of 8.8 g of CDD followed by 52.1 g of AEP/CDD1 at 180-182.degree. C. and 0.20 mbar as a colorless liquid.

The product was confirmed to be a mixture of the two compounds shown below by gas chromatography/mass spectrometry (gc-ms) and .sup.1 H and .sup.13 C nuclear magnetic resonance (NMR) spectroscopy. .sup.13 C NMR showed that the mixture was composed of a 12:1 ratio of chain:ring alkylated material. ##STR16##

In the following Examples dynamic surface tension data were obtained for aqueous solutions of various compounds using the maximum bubble pressure method at bubble rates from 0.1 bubbles/second (b/s) to 20 b/s. These data provide information about the performance of a surfactant at conditions from near-equilibrium (0.1 b/s) through extremely high surface creation rates (20 b/s). In practical terms, high bubble rates correspond to high printing speeds in lithographic printing, high spray or roller velocities in coating applications, and rapid application rates for agricultural products.

Dynamic surface tension data were obtained for aqueous solutions of the reductive alkylation product of aminoethylpiperazine with one equivalent of methylisobutylketone (AEP/MIBK1) using the above procedure. The data are presented in Table 1.

These data show that AEP/MIBK1 effectively reduced the surface tension of water, and that surface tensions below 40 dyne/cm could be achieved at a use level of 5 wt %. The performance under conditions of high surface creation rate was particularly good, as illustrated by the data obtained at 20 b/s. Such a marked ability to lower the surface tension of water under a variety of conditions is certainly of utility in water borne coatings, inks, adhesives, and agricultural formulations.

Solutions in distilled water of the reductive alkylation product of aminoethylpiperazine with one equivalent of methyl isoamyl ketone (AEP/MIAK1) and aminoethylpiperazine with one equivalent of methyl amyl ketone (AEP/MAK1) were prepared and their dynamic surface tension properties were measured using the procedure described above. The data are set forth Tables 2A and 2B for AEP/MIAK1 and AEP/MAK1, respectively.

These results show that for a 1.0 wt % solution of AEP/MIAK1, the surface tension at 0.1 b/s was 31.0 dyne/cm and that the surface tension increased only to 38.8 dyne/cm at 20 b/s. At a use level of 2 wt %, the surface tension measured at 0.1 b/s dropped to 28.2 dyne/cm and remained under 35 dyne/cm even at 20 b/s. For a 1.0 wt % solution of AEP/MAK1, the surface tension at 0.1 b/s was 31.2 dyne/cm and that the surface tension increased only to 40.8 dyne/cm at 20 b/s. At a use level of 2 wt %, the surface tension measured at 0.1 b/s dropped to 27.8 dyne/cm and remained under 36 dyne/cm even at 20 b/s. The ability of the surfactants of this invention to maintain this extremely low surface tension under such rapid application conditions would be of use in high speed coating and ink processes, particularly when the substrate possesses a low energy surface. The outstanding performance at these high surface creation rates will provide superior productivity by enabling high printing speeds or application rates for water-based coating, ink, and agricultural formulations.

Solutions in distilled water of the reductive alkylation product of aminoethylpiperazine with one equivalent of cyclododecanone (AEP/CDD1) were prepared and their dynamic surface tension properties were measured using the procedure described above. The data are set forth Table 3.

The data show that AEP/CDD1 is more efficient than the surfactants of Examples 4 and 5, i.e. equivalent performance can be achieved at a lower use level. Thus, effective performance can be achieved in aqueous formulations, even at relatively low use levels.

Solutions in distilled water of the reductive alkylation product of aminoethylpiperazine with two equivalents of methyl isobutyl ketone (AEP/MIBK2) were prepared and their dynamic surface tension properties were measured using the procedure described above. The data are set forth Table 4.

These data illustrate that the dialkylated material AEP/MIBK2 was much more efficient than the corresponding monoalkylated product AEP/MIBK1 of Example 4.

Solutions in distilled water of the reductive alkylation product of aminoethylpiperazine with two equivalents of methyl isoamyl ketone (AEP/MIAK2) were prepared and their dynamic surface tension properties were measured using the procedure described above. The data are set forth Table 5.

Again, AEP/MIAK2 exhibited a good ability to reduce dynamic surface tension in aqueous compositions.

The foaming properties of 0.1 wt % solutions of the alkylated aminoalkylpiperazine surfactants of this invention were examined using a procedure based upon ASTM D 1173-53. In this test, a 0.1 wt % solution of the surfactant is added from an elevated foam pipette to a foam receiver containing the same solution. The foam height is measured at the completion of the addition ("Initial Foam Height") and the time required for the foam to dissipate at the air-liquid interface ("Time to 0 Foam") is recorded. This test provides a comparison between the foaming characteristics of various surfactant solutions. In general, in coatings, inks, and agricultural formulations, foam is undesirable because it complicates handling and can lead to coating and print defects, and to inefficient application of agricultural materials. The data are presented in Table 6.

The data in Table 6 show that the compounds of this invention form little foam and that which forms dissipates quickly.

A commercially available photoresist (OCG 825 20 cS, Olin Corporation) was used to coat a 4 inch silicon wafer with a film thickness of approximately 1 micron. This resist is designed to be much more soluble in developer solutions and was used with 0.131M TMAH. The photoresist was exposed to UV radiation centered at 365 nm (mercury i-line) through a variable transmission filter (from Opto-Line Associates, Wilmington Mass.), which consisted of a circular area on a quartz plate broken up into wedges of varying transmission levels. Different areas of the resist were then exposed to the UV radiation at various levels of intensity by positioning the wafer under an aperture opening and operating a shutter. Table 7 shows data for the dissolution of exposed resist with a 0.131 M TMAH aqueous solution formulated with AEP/MAK1 (0.1 wt %; 1000 ppm) to a surface tension of 44.1 dynes/cm. The data show outstanding selectivity, even with this highly sensitive photoresist formulation.

Foam tests were made in TMAH developer solutions formulated with AEP/MAK1 as a surfactant and with three commercial developer solutions containing surfactants. Data were collected utilizing a foam generating apparatus whereby nitrogen gas was passed through a frit and bubbled through 100 mL of the solutions at 50 mL/min. Except for the commercial developer solutions which were used as received, the AEP/MAK1-containing solution contained 2.4 wt % TMAH in water with enough surfactant to lower surface tension to about 43 dyne/cm. The results are given in Table 8.

The above data in Table 8 show that TMAH developer solution containing the AEP/MAK1 as the surfactant developed considerably less foam than the commercial developer solutions containing other types of surfactant. It is quite surprising that alkylated aminoalkylpiperazines containing C5-C8 alkyl groups increase the ability of these materials to reduce both surface tension and foaming tendency in TMAH developer solutions while maintaining good contrast for photoresist developing applications. These goals are achieved while lowering the level of alkylated aminoalkylpiperazine required for a desired surface tension reduction.

Table 9 presents additional data indicating the low foam associated with the AEP/MAK1 wetting agent in a 0.262N TMAH solution obtained using the Ross-Miles technique.

By comparison, N-dodecyl diethylenetriamine (DETA/DDA1), a derivative with a long linear side-chain, at a concentration of only 40 ppm showed an initial foam height of 8.3 cm which was almost completely stable for five minutes at which time the foam was still 7.5 cm in height.

The ability of a surfactant in aqueous systems to reduce surface tension under both equilibrium and dynamic conditions is of great importance in the performance of waterbased coatings, inks, adhesives, fountain solutions, agricultural formulations and photoresist developing and electronics cleaning compositions. Low equilibrium surface tension allows the development of excellent properties subsequent to application. Low dynamic surface tension results in enhanced wetting and spreading under the dynamic conditions of application, resulting in more efficient use of the formulations and fewer defects. In waterborne coating, ink, adhesive, fountain solution, agricultural and photoresist developing and electronics cleaning compositions, the formation of foam is generally undesirable because it complicates handling and can cause defects or result in inefficient application. The alkylated aminoalkylpiperazine surfactants of this invention display an outstanding ability to provide equilibrium and dynamic surface tension reduction in aqueous formulations while producing substantially no foam. Foam control is a particularly important attribute in photoresist developer/electronics cleaning compositions. The present invention affords these attributes while maintaining good contrast for photoresist developing application. These materials would therefore be expected to be useful in aqueous coatings, inks, adhesives, fountain solutions, agricultural formulations and photoresist developing and electronics cleaning formulations.

The invention provides compositions suitable for reducing the equilibrium and dynamic surface tension in water-based coating, ink, adhesive, fountain solution, agricultural compositions and photoresist developing/electronics cleaning compositions.