US 5,673,474 AGrant
Method of Fabricating a Thin Film Magnetic Head Including Layered Magnetic Side Poles
Issue Date:1997-10-07
•20 Claims
•13 Drawing Sheets
Abstract
A method is provided for fabricating a thin film magnetic head on a substrate. A seed layer formed on the substrate and advantageously used as a common seed for a plurality of magnetic head related structures which are built-up on the substrate. A lower magnetic layer is plated on the substrate in an opening provided in an insulative layer which is deposited on the substrate. The aforementioned seed layer is used as the seed for the plating of this lower magnetic layer. A plurality of magnetic layers are plated at one end of the lower magnetic layer to build-up and form a first side pole by again using the aforementioned seed layer as a seed. Another plurality of magnetic layers are plated at the other end of the lower magnetic layer to build-up and form a second side pole by using the same seed layer as a seed. The first and second side poles thus formed include upper and lower ends, the lower ends being plated to the ends of the lower magnetic layer. A first upper pole is plated to the upper end of the first side pole. The first upper pole includes a gap end facing the second side pole. A gap region of nonmagnetic material is deposited adjacent the gap end of the first upper pole. A second upper pole is plated to the upper end of the second side pole and includes a gap end adjacent the gap region.
Metadata
Assignee
- AIWA Research and Development, Inc.
Inventors
- James Watterston
- Arun Malhotra
- G. Robert Gray
- Jane Ang
Application Information
Application Number:US 7227027
Filing Date:1996-09-30
Priority Date:1994-08-26
Art Unit:326
Classifications
IPC:
G11B 542
Field of Search:
29427360603.13;603.14;603.15;603.25;603.26;603.24128-132119-121;125-127
Patent Drawings (13 sheets)
Description
Cross Reference to Related Patent Applications
This patent application is related to the copending patent application entitled "METHOD OF FABRICATING A THIN FILM MAGNETIC HEAD INCLUDING LAYERED MAGNETIC SIDE POLES", patent application Ser. No. 08/297,186, now abandoned, by Malhotra et al., filed concurrently herewith and assigned to the same assignee, the disclosure of which is incorporated herein by reference.
Background of the Invention
1. Field of the Invention
This invention relates in general to magnetic recording and playback heads and, more particularly, to thin film magnetic recording and playback heads.
2. Description of Related Art
In the continuing drive for increased storage density in magnetic media storage devices, thin film magnetic heads have been developed. As opposed to earlier types of magnetic heads, the fabrication of which involves significant piecework and manual handling of individual parts, thin film magnetic heads take advantage of semiconductor fabrication processes to form a large number of heads simultaneously on a common substrate or wafer.
One such head which is formed by a semiconductor thin film process is disclosed in the article, "A New Thin Film Head Generation IC Head" by J. P. Lazzari et al., IEEE Transactions on Magnetics, Vol. 25, No. 5, September 1989. A cross-sectional view of the Lazzari head is illustrated in FIG. 1 as head 10. Head 10 is fabricated within a recess 15 in a silicon substrate 20. A gap 25 is shown in the uppermost portion of a magnetic layer or yoke 30 situated within recess 15. Head 10 is shown positioned adjacent magnetic recording media 35. A magnetic coil 40 is wound around magnetic yoke 30. A plurality of sliders with respective heads 10 thereon are fabricated from a common silicon wafer or substrate using semiconductor thin film processes. The sliders are then diced up into individual slider assemblies.
In fabricating thin film heads and other thin film structures, difficulties are often encountered in maintaining the planarity of the various layers which form the head. It is possible that if planarity is not maintained in some structures of the thin film head during head fabrication, the resulting irregularities can cause failure in the operation of the resultant head or degraded operation of the head.
Summary of the Invention
One advantage of the disclosed method of fabricating a thin film head is the maintenance of layer planarity in selected areas of the head.
Another advantage of the disclosed method of fabricating a thin film head is that the head can be fabricated without excavating a recess within the substrate to contain the head.
Another advantage of the disclosed method of fabricating a thin film head is a narrow gap width which results in correspondingly high density magnetic recording capabilities.
Still another advantage of the disclosed method of fabricating a thin film head is that the head can be fabricated in large quantities using thin film semiconductor fabrication equipment.
In accordance with one embodiment of the present invention, a method of fabricating a thin film magnetic head apparatus is provided. The method includes the step of depositing a conductive seed layer on a substrate. The method also includes the step of plating a lower magnetic layer on the substrate, the lower magnetic layer having first and second opposed ends, the seed layer being the seed for plating the lower magnetic layer. The method further includes the step of plating a plurality of layers of magnetic material at the first end of the lower magnetic layer to build-up a first side pole having a first top end, this plating step using the seed layer as a common seed for the build-up of the plurality of layers of the first side pole. The disclosed method also includes the step of plating a plurality of layers of magnetic material at the second end of the lower magnetic layer to build-up a second side pole having a second top end, this plating step using the seed layer as a common seed for the build-up of the plurality of layers of the second side pole. The disclosed method further includes the step of depositing a first upper magnetic pole element at the first top end, the first upper magnetic pole element including a first gap end extending toward the second top end. The method also includes the step of forming a gap region of nonmagnetic material at the first gap end of the first upper magnetic pole element. The method further includes the step of depositing a second upper magnetic pole element at the second top end, the second upper magnetic pole element including a second gap end situated adjacent the gap region.
Brief Description of the Drawings
The features of the invention believed to be novel are specifically set forth in the appended claims. However, the invention itself, both as to its structure and method of operation, may best be understood by referring to the following description and accompanying drawings,
FIG. 1 is a cross section of a conventional thin film magnetic head.
FIG. 2A is a plan view of a substrate with via holes employed by one embodiment of the magnetic head of the invention.
FIG. 2B is a cross section of the magnetic head of FIG. 2A taken along section line 2B--2B.
FIG. 3 is a plan view of the magnetic head of FIG. 2A with a seed layer added.
FIG. 4A is a plan view of the magnetic head of FIG. 3 with an insulative layer and open region formed therein.
FIG. 4B is a sectional view of the magnetic head of FIG. 4A taken along section line 4B--4B.
FIG. 4C is a presentation of an E-beam curing system used in fabricating the magnetic head.
FIG. 5 illustrates a plurality of magnetic heads being fabricated on a common substrate.
FIG. 6A is a plan view of the magnetic head of FIG. 4A showing an early stage of side pole build-up
FIG. 6B is a cross sectional view of the magnetic head of FIG. 6A taken along section line 6B--6B.
FIG. 7A is a plan view of the magnetic head of FIG. 6A showing the placement of a lower coil structure.
FIG. 7B is a cross sectional view of the magnetic head of FIG. 7A taken along section line 7B--7B.
FIG. 8A is a plan view of the magnetic head of FIG. 7A showing an insulative layer on the lower coil structure.
FIG. 8B is a cross sectional view of the magnetic head of FIG. 8A taken along section line 8B--8B.
FIG. 9A is a plan view of the magnetic head of FIG. 8A showing placement of an upper coil structure.
FIG. 9B is a cross sectional view of the magnetic head of FIG. 9A taken along section line 9B--9B.
FIG. 10A is a plan view of the magnetic head of FIG. 9A showing an insulative layer on the upper coil structure.
FIG. 10B is a cross sectional view of the magnetic head of FIG. 10A taken along section line 10B--10B.
FIG. 11A is a plan view of the magnetic head of FIG. 10A showing placement of a seed layer and a connective grounding strip.
FIG. 11B is a cross sectional view of the magnetic head of FIG. 11A taken along section line 11B--11B.
FIG. 12 is a cross sectional view of the magnetic head of FIG. 11B showing placement of an insulative pedestal thereon.
FIG. 13A is a cross sectional view of the magnetic head of FIG. 13B showing the further build-up of the magnetic side poles.
FIG. 13B is a close-up plan view of a portion of the head of FIG. 13A showing the side pole and insulative pedestal area.
FIG. 14A is a cross sectional view of the magnetic head of FIG. 14B showing the addition of a first magnetic pole at the top of the magnetic yoke structure of the head.
FIG. 14B is a close-up plan view of a portion of the head of FIG. 14A showing the first magnetic pole.
FIG. 15A is a close-up plan view of a portion of the head of FIG. 14A showing the gap region of the head.
FIG. 15B is a cross sectional view of the magnetic head of FIG. 15A showing the addition of a gap region.
FIG. 16A is a close-up plan view of the side pole and gap region of the magnetic head of FIG. 15A showing the addition of a second magnetic pole at the top of the magnetic yoke structure of the head.
FIG. 16B is a cross sectional view of the magnetic head of FIG. 16A taken along section line 16B--16B and showing the addition of a second magnetic pole.
FIG. 17A is a close-up plan view of the side pole and gap region of the magnetic head of FIG. 16A after addition of an adhesion layer and a diamond-like carbon wear layer to the top of the head.
FIG. 17B is a cross sectional view of the magnetic head of FIG. 17A taken along section line 17B--17B.
FIG. 18 is a cross sectional view of the magnetic head of FIG. 17B showing the magnetic head after a diamond-like carbon wear layer and adhesion layer are patterned and etched in regions other than the insulative pedestal.
FIG. 19A is close-up view of the side pole and gap region of the magnetic head when fabrication is complete.
FIG. 19B is a cross section view of the magnetic head of FIG. 19A taken along section line 19B--19B.
Detailed Description of the Invention
FIG. 2A shows a portion of a thin film head 100 which is situated on an insulative substrate 105 such as a ceramic, alumina or other nonconductive substrate. Substrate 105 includes opposed surfaces 105A and 105B. Via holes 110 are formed in substrate 105 and are filled with an electrically conductive material to create conductive paths through substrate 105 at the locations shown. Laser drilling or other high precision via formation technique may be employed to form via holes 110. Via holes 110 are filled with electrically conductive material such as plated copper, thick film processed gold, or sintered tungsten and copper, for example, to form via connective members 112A, 112B and 112C. Connective members 112A and 112C will subsequently be coupled to the ends of a coil structure and connective member 112B will be coupled to ground. In one embodiment of the invention wherein the magnetic head is ungrounded, via hole 112B is omitted. In actual practice, substrate 105 is a wafer on which the FIG. 2A pattern is replicated thousands of times.
A seed layer 115 of an electrically conductive material suitable for plating is sputtered on substrate surface 105A. For example, seed layer 115 may be fabricated from Cr-NiV, namely, a chrome or other adhesion-promoting layer followed by a non-magnetic nickel-vanadium 7% film. Via caps 120 are patterned using photolithographic techniques and plated on seed layer 115 at the tops of vias 110 as shown in FIGS. 2A and 2B. More specifically, to pattern via caps 120, a photoresist layer (not shown) is deposited on seed layer 115 and patterned to include openings above connective members 112A, 112B and 112C at which the formation of respective via caps 120 is desired. Plating is then conducted in these openings using seed layer 115 as the seed. The photoresist is then removed, thus leaving patterned via caps 120. As used in this document, the term "patterning" will mean the formation of a particular layer such that the layer exhibits a specified pattern, such as described with respect to the formation of via caps 120 above, for example.
Via caps 120 are fabricated from NiFe by any suitable deposition or plating process. It is noted that later in the process described herein, portions of seed layer 115 will be removed by sputter etching. While in the particular example described, via caps 120 are fabricated from NiFe, in actual practice via caps 120 can be fabricated from other conductive materials which would not be attacked by the particular etchant used to later remove Cr-Cu seed layer 185, 230 and 275. Via caps 120 are regarded as being a part of via connective members 112A, 112B and 112C.
Seed layer 115 is also used to pattern and NiFe plate photolithographic alignment targets (not shown) for registration of subsequent layers. The exposed portions of seed layer 115 are then sputter etched away leaving via caps 120 and the alignment targets intact. It should be appreciated that seed layer 115 served as a sacrificial layer for the purpose of enabling plating of via caps 120.
In the next step of the process, a Cr-NiV seed layer 130 is formed on the structure of FIG. 2B after seed layer 115 is etched away. Seed layer 130 is formed in the shape of a ground structure 125 which extends around the periphery of head 100 on substrate 105 and laterally across the middle of head 100 as shown in FIG. 3. Open regions 117A and 117B are thus formed in seed layer 130 which respectively isolate via connective members 112A and 112C from ground structure 125 and via connective member 112B. In the embodiment depicted in FIG. 3, via connective member 112B is coupled to ground structure 125. To actually form seed layer 130, a "lift-off" process is used. In this "lift-off" process, photoresist (not shown) is patterned covering open regions 117A and 117B (see FIG. 3). Seed layer 130 is then sputtered on the entire upper surface of the partially completed head 100. The photo-resist which covers open regions 117A and 117B is now "lifted-off" head 100. To accomplish this lift-off, the partially complete head 100 is placed in an ultrasonic bath including a photoresist solvent such as acetone, for example. The seed layer 130 is sufficiently thin such that it does not cover photoresist layer at open regions 117A and 117B very well. In this manner, there are sufficient avenues of attack by which the solvent can get through seed layer 130 at the edges of open regions 117A and 117B to dissolve the photoresist layer at open regions 117A and 117B. When the photoresist layer at open regions 117A and 117B is thus dissolved, the portions of seed layer 130 immediately above open regions 117A and 117B lift-off and float away. The region of head 100 at open regions 117A and 117B is thus void of seed layer 130 as shown in FIG. 3.
An insulative layer 135 of photoresist is patterned on head 100 as shown in FIG. 4B. Insulative layer 135 is cured with an electron beam or E-beam. To cure insulative layer 135, the partially complete head 100 with insulative layer 135 thereon is placed in the E-beam curing system 700 of FIG. 4C. More particularly, head 100 is placed in a vacuum chamber 705 which is shown in cross section in FIG. 4C. The vacuum chamber 705 includes a pump port 705A which is coupled to a vacuum pump by a valve 710. Chamber 705 further includes an inlet gas port 705B which is coupled to an inlet gas source via a valve 715. Chamber 705 also includes a wide area electron emitter 720 and a grounded anode 725. A extraction grid 730 is supported by insulators 735 and 740. A high voltage power supply 745 is coupled between grid 730 and emitter 720.
System 700 is pumped down to a rough vacuum of approximately 20 mTorr. The flow of inert gas such as nitrogen or argon is started though valve 715 to inlet port 705B. A high voltage within the range of approximately 17-22 KV is applied between extraction grid 730 and the electron emitting cathode emitter 720 thus creating a plasma. Free electrons are accelerated though grid 730 and bombard head 100 and cross-link the polymer photoresist material of photoresist layer 135. The amount of cross-linking is determined by the coulomb (charge) dose. A coulomb dose of approximately 6700 .mu.C is found to be sufficient to cure a 7-8 micron thick photoresist film. The rate of cross-linking of the photoresist is determined by the E-beam current which may be controlled from approximately 1 mA to approximately 5 mA in one embodiment. Other photoresist layers fabricated in head 100 can be E-beam cured as well using this technique.
Layer 135 includes an open region 140 for receiving the lowermost portion of a magnetic yoke 145 therein. More particularly, a layer 150 of magnetic material such as NiFe is patterned and plated on seed layer 130 within open region 140 to form the lowermost portion of magnetic yoke 145. Magnetic layer 150 exhibits a thickness of approximately 5 microns to approximately 6 microns in this particular embodiment. When reference is made to "magnetic layers" or other magnetic structures in this document, it should be understood that layers of magnetically permeable material are being referenced. Magnetic layer 150 forms the bottom pole of magnetic yoke 145. Seed layer 130, or more specifically the middle section of the ground structure 125 thereof, acts as a base upon which magnetic yoke 145 is built up layer by layer. Magnetic layer 150 is plated up to a level such that it is level with insulative layer 135.
It has been found that the order of forming seed layer 130 and insulative layer 135 with opening 140 therein is important with respect to maintaining the planarity of the main body of the thin film head structure. (The main body 388 is specified in more detail in FIG. 19B) If insulative layer 135 is formed prior to seed layer 130, non planar irregularities in the layers of the head can result. For example, if insulative layer 135 is first formed with opening 145 therein and a seed layer is deposited on insulative layer 135 including opening 140, then when magnetic layer 150 is plated within opening 140, the resultant magnetic layer 150 may be nonplanar. To avoid this undesired situation, seed layer 130 is first formed on substrate 105 and then insulative layer 135 with opening 140 is formed on seed layer 130 as shown in FIG. 4B.
For convenience, one half of head 100 is depicted in FIG. 4A and subsequent figures. It should be understood that substantially the same structure as shown in FIG. 4A and the subsequent figures is repeated to form the actual head. More particularly, in the particular embodiment shown, head 100 is symmetric about major axis 155 such that head 100 actually includes two recording or playback portions. In actual practice, a plurality of heads 100 are fabricated simultaneously on a common insulating substrate 105 as shown in FIG. 5. For example, 5000 or more heads may be fabricated at the same time on the same substrate. FIG. 5 shows another embodiment of head 100, namely an ungrounded version in which via connective member 112B is omitted.
An insulative layer 160 of photoresist is patterned on head 100 as shown in FIGS. 6A and 6B. Insulative layer 160 is electron beam cured to provide a planar surface as illustrated. The thickness of insulative layer 160 in this particular embodiment is approximately 2 microns. Insulative layer 160 includes open regions 165 and 170 in which respective magnetic side poles are built up. More specifically, a magnetic side pole portion 175 is plated in open region 165 up to a height which is level with insulative layer 160, and a magnetic side pole portion 180 is plated in open region 170 up to a height which is level with insulative layer 160.
A seed layer 185 is sputtered on insulative layer 160 of the partially formed head 100 of FIG. 6A to form a plating base for a lower coil layer 190 as shown in FIG. 7A. Seed layer 185 is drawn sufficiently thin such that it does not appear to have significant vertical dimension in FIG. 7A. Seed layer 185 is fabricated from CrCu in one embodiment.
A lower coil layer 190 is formed on seed layer 185 as shown. One way to form lower coil member 190 is to deposit a layer of photoresist (not shown) on seed layer 185. This photoresist layer is then patterned using conventional photolithographic techniques which includes photoresist application, masking, exposure, developing, and so forth. More specifically, the photoresist layer is patterned to cover the entire surface of seed layer 185 except for openings at the locations where the coil elements of lower coil layer 190 are to be formed. Head 100 is then subjected to a plating bath of copper. Copper is thus plated in the openings of the photoresist layer to form lower coil layer 190. The thickness of coil layer 190 is within the range of approximately 3 .mu. to approximately 3.5 .mu. at this stage.
Lower coil layer 190 includes a connective strip 195 made of electrically conductive material which couples an end 190A of coil layer 190 to the via cap 120 of via connective member 112A. Copper plating may be used to fabricate connective strip 195 as part of the above step of forming lower coil layer 190. The remaining end 190B of lower coil layer 190 is located at the center of the lower coil. Head 100 is then etched to remove CrCu seed layer 185 from those portions of head 100 not protected by lower coil layer 190. To achieve this, an etchant which does not significantly attack the any NiFe magnetic core material or any NiV seed layer is used. For example, a wet etchant for copper is generated by dissolving 120 g of ammonium persulfate and 64 mL of ammonium hydroxide in 1 liter of deionized water. The wet etchant for chromium is generated by dissolving 20 g of potassium permanganate and 5 g of potassium hdroxide in 1 liter of deionized water. Both etchants may be used at room temperature.
An insulative layer 200 of photoresist is patterned on head 100 above lower coil layer 190 leaving an open region 205 for access to coil end 190B as shown in FIGS. 8A and 8B. The thickness of insulative layer 200 is within the range of approximately 5 .mu. to approximately 6 .mu. insulative layer 200 is also patterned to leave open regions 210 and 215 above side pole portion 175 and side pole portion 180, respectively. Insulative layer 200 is electron beam cured. Insulative layer 200 electrically isolates lower coil layer 190 from structures subsequently placed above layer 190.
Magnetic side pole portions 220 and 225 are plated on side pole portions 175 and 180, respectively, as shown in FIGS. 8A and 8B. Side pole portions 220 and 225 are plated with a magnetic material such as NiFe up to a level even with that of insulative layer 200.
A seed layer 230 is sputtered on insulative layer 200 of the partially formed head 100 of FIG. 8B to form a plating base for an upper coil layer 235. Seed layer 230 is drawn sufficiently thin such that it does not appear to have significant vertical dimension in FIG. 8B. Seed layer 230 is fabricated from CrCu in one embodiment. Upper coil layer 235 is patterned and copper plated on seed layer 230 as shown in FIG. 9A and 9B. FIG. 9B is a simplified cross-section of head 100 at the described stage of fabrication in which structures in back of upper coil layer 235 are not shown in order to emphasize upper coil layer 235. In this particular embodiment, upper coil layer 235 is substantially similar in geometry to lower coil layer 190 and is fabricated using substantially the same technique. However, other coil arrangements are possible if desired. Head 100 is then etched to remove seed layer 230 from those portions of head 100 not protected by upper coil layer 235.
Upper coil layer 235 includes a connective strip 237 made of electrically conductive material which couples an end 235A of upper coil layer 235 to the via cap 120 of via connective member 112C. Copper may be used to fabricate connective strip 237. The remaining end 235B of upper coil layer 235 is coupled to lower coil end 190B through open region 205, shown later in FIG. 10B, by a plated connection therebetween.
An insulative layer 240 of photoresist material is deposited and patterned on head 100 as shown in FIGS. 10A and 10B. Insulative layer 240 electrically isolates upper coil layer 235 from the other structures of head 100. Insulative layer 240 includes open regions 245 and 250 into which magnetic side pole portions 255 and 260 are respectively plated. More specifically, magnetic side pole portions 255 and 260 are plated up to a level even with insulative layer 240 as shown in FIG. 10B.
Magnetic side pole portions 175, 220 and 255 together form a first side pole 265. Magnetic side pole portions 180, 225 and 260 together form a second side pole 270. First side pole 265, second side pole 270 and bottom pole 150 together form a significant portion of magnetic yoke 145.
A seed layer 275 fabricated of CrCu material is formed on the upper surface of the head structure 100 as shown in FIG. 11B. Seed layer 275 is sputtered, patterned and chemically etched on the upper surface of head 100 to include an open region 280 above the side pole structure also as shown in FIG. 11B. Seed layer 275 is formed by an adhesion layer of chromium (Cr) on the upper surface of head 100 followed by a layer of copper (Cu). The chromium adhesion layer enhances the adherence of the copper portion of seed layer 275 to upper surface of head 100.
The primary requirement in selection of the material for seed layer 275 is that seed layer 275 be chemically etchable without damage to the exposed NiFe. Copper is an example of a material that meets this requirement and is also used for the coil seed layers. Chrome is used as the adhesion layer for copper. It is noted that a titanium-tungsten seed layer (Ti 10%; W 90%) which wet etches easily can also be used for seed layer 275.
Protective caps 285 and 290 are patterned over connective strips 195 and 237, respectively. Caps 285 and 290 are fabricated from NiFe by plating in one embodiment. A material such as nickel, nickel-phosphorus 7-10%, or gold may be used to provide environmental protection for the underlying plated copper connective strips.
In an embodiment of head 100 wherein head 100 is grounded, a grounding connective strip 295 is also patterned and plated in the same process step as protective caps 285 and 290. Grounding strip 295 connects ground via connective member 112B and magnetic yoke 145 through seed layer 130. Grounding strip 295 is fabricated from the same material as protective caps 285 and 290 in this particular embodiment.
An electrically insulative layer of photoresist is patterned and electron beam cured to form a protrusion or pedestal 300 on the upper portion of head 100 as shown in FIG. 12. Insulative pedestal 300 exhibits a substantially rectangular geometry with rounded corners in this particular embodiment, although other geometries may be used if desired. Insulative pedestal 300 includes open regions 305 and 310 for side poles 265 and 270 of the magnetic yoke. Open regions 305 and 310 are filled with magnetic material by plating side poles 265 and 270 with NiFe up to the level of the top of insulative layer 300 as shown in FIG. 13A. Magnetic side pole portions 315 and 320 are thus formed in open regions 305 and 310. Magnetic side pole portions 315 and 320 form the uppermost parts of first side pole 265 and second side pole 270, respectively.
A frame 325 of magnetic material, for example NiFe, is patterned around insulative pedestal 300 at the same time that magnetic side pole portions 315 and 320 are plated. Plating or other suitable deposition technique is used to form frame 325. Frame 325 exhibits a thickness of approximately 5 .mu. in this particular embodiment. Seed layer 275 acts as the seed for the plating of frame 325. Frame 325 exhibits a substantially rectangular shape in this particular embodiment and surrounds insulative pedestal 300 which forms the inner boundary of frame 325 as seen in FIG. 13B. Shapes other than rectangular can be used for frame 235 as long as frame 325 substantially surrounds, and is located immediately adjacent to, pedestal 300. Frame 325 serves to Stiffen insulative pedestal 300 and may provide electrical shielding of the contained structures. In other words, frame 325 provides structural integrity to pedestal 300. FIG. 13B is a close-up view of the coil and side pole regions of head 100 at the present stage in the fabrication of head 100. Alternatively, side pole portions 315 and 320 are fabricated as before, but frame 325 is subsequently patterned and plated with non-magnetic NiP alloy up to a level even with the top of insulative pedestal 300. The innermost boundary of seed layer 275 which abuts its open region 280 is shown in dashed line in FIG. 13B. The exposed CrCu seed layer 275 is removed by wet chemical etching.
Referring now to FIGS. 3, 14A and 14B, a layer of photoresist is patterned covering open regions 117A and 117B (see FIG. 3) and further covering side poles 265 and 270 (see FIGS. 14A and 14B). A Cr-NiV seed layer 330 is sputtered on the exposed upper surfaces of head 100. The photo-resist is stripped as in the earlier-described "lift-off" process, thus "lifting off" the sputtered Cr-NiV film from regions 117A and 117B. During this photoresist stripping step, the photoresist above side poles 265 and 270 is removed to form open regions 335 and 340 as shown in FIG. 14A. Side poles 265 and 270 are thus exposed.
A first magnetic pole 345 is patterned at the top of magnetic yoke 145 as shown in FIGS. 14A and 14B. First magnetic pole 345 is fabricated by plating a magnetic material such as NiFe on side pole 265 and on a portion of seed layer 330 adjacent side pole 265. Magnetic control regions 350 and 355, which are adjacent both sides of first magnetic pole 345, may be patterned and plated at the same time as first pole 345. Magnetic control regions 350 and 355 serve to better control local plating current density which influences NiFe composition and enhances the effect of the easy axis magnetic orienting field of between approximately 1000 Gauss to approximately 10,000 Gauss, provided by an external magnet during the first magnetic pole plating step, to give a desired magnetic domain structure in the magnetic pole piece. Head 100 is exposed to the same magnetic field throughout the duration of building up the various magnetic layers thereof.
A substantially rectangular gap region 360 of non-magnetic material is plated adjacent pole end 345A as shown in FIG. 15A and the head cross section of FIG. 15B. One non-magnetic material which may be used to fabricate gap region 360 is NiP. Diamond-like carbon is another material which may be chemically vapor deposited as gap region 360.
A second magnetic pole 365 is patterned and plated at side pole 270 at the top of magnetic yoke 145 as shown in FIGS. 16A and 16B. Second magnetic pole 365 includes a pole end 365A which is situated adjacent pole end 345A and which is separated from pole end 345A by gap region 360. It is noted that pole 345 becomes narrower from side pole 265 to pole end 345A. Similarly, pole 365 becomes narrower from side pole 270 to pole end 365A. This gives poles 345 and 365 a bow tie-like appearance in this particular embodiment. Other pole geometries may be used as well. Pole ends 345A and 365A are alternatively referred to as gap ends. First magnetic pole 345 and second magnetic pole 365 exhibit a thickness of approximately 5 .mu..
Magnetic control regions 370 and 375 are patterned and plated adjacent both sides of second pole 365 to enhance magnetic control as shown in FIG. 16A. Control regions 350, 355, 370 and 375 are fabricated from a magnetic material such as the material used to fabricate second magnetic pole 365. For optimal wear performance, the area of NiFe exposed to the recording media should be minimized. Thus, to avoid possible magnetic effects that may degrade recording performance, NiFe plated magnetic control regions 350, 355, 370 and 375 are patterned with photoresist and etched away leaving a pole geometry seen in FIG. 17A.
Magnetic side pole portions 175, 220, 255 and 315 together make up a first side pole which is shown collectively as side pole 265 in FIG. 16B. Magnetic side pole portions 180, 225, 260 and 320 together make up a second magnetic side pole which is shown collectively as side pole 270 in FIG. 16B. Magnetic yoke 145 is collectively made up of bottom magnetic layer 150, side poles 265 and 270, and magnetic poles 345 and 365.
The exposed seed layer 330 is removed by sputter etching. Alternatively, seed layer 330 is not etched, but is permitted to remain. A silicon adhesion layer 380 is sputtered on the exposed upper surface of head 100 as shown in FIG. 17B. A diamond-like carbon (DLC) protective wear layer 385 is then deposited on adhesion layer 380. Adhesion layer 380 enables DLC layer 385 to stick to the upper surface of head 100. This silicon adhesion layer typically exhibits a thickness within the range of approximately 400A.degree. to approximately 1000A.degree.. This silicon adhesion layer exhibits a nominal thickness of approximately 600A.degree. in a preferred embodiment.
DLC layer 385 covers at least the top of magnetic yoke 145 and the immediately surrounding area of the head. As seen in FIG. 17A and more clearly in FIG. 17B, a hard protective wear layer 385 covers magnetic yoke 145 and insulative pedestal 300. Protective layer 385 exhibits a Knoop hardness greater than 700 Knoop and preferably greater than 800 Knoop. The hardness of protective layer should be within the range of greater than approximately 700 Knoop to approximately 2000 Knoop. One material that is satisfactory for formation of protective wear layer 385 is diamond like carbon (DLC).
To form such a DLC wear layer 385, DLC layer 385 is chemically vapor deposited and patterned. More specifically, both DLC layer 385 and adhesion layer 380 are reactive ion etched to leave a DLC wear layer 385' over magnetic yoke 145 and insulative pedestal 300 as shown in FIG. 18. Prior to exposing head 100 to this reactive ion etch, the upper surface of head 100 is covered with a layer of photoresist (not shown). The photoresist layer is patterned to include unprotected open regions for those portions of the head external to frame 325. In this manner, when the head is subjected to the reactive ion etch, the portion of DLC layer 385 external to frame 325 is etched away and the remaining portion of DLC layer 385 is protected and remains as DLC layer 385'.
An alternative to the above described photoresist masking approach to patterning DLC layer 385 into DLC layer 385' is to cover head 100 with a metal layer such as chromium. For example, a relatively thin photomask layer (not shown) of chromium is sputtered over the DLC layer. In this particular example, the photomask layer is approximately 500A.degree. thick. The metal photomask layer is photo-patterned and etched to expose DLC areas which are to be excavated by reactive ion etching. The DLC layer is then reactive ion etched to the desired DLC structure.
More detail is now provided with respect to the formation of DLC protective wear layer 385. Before DLC protective wear layer 385 is actually laid down on silicon adhesion layer 380, adhesion layer 380 is sputter cleaned. In the course of performing this sputter cleaning, approximately 200A.degree. of the upper surface of silicon adhesion layer 380 is removed. More particularly, the silicon adhesion layer is sputter cleaned in a SAMCO plasma machine, Model No. PD-200D (Plasma Enhanced CVD System For DLC Deposition and Etching), hereafter the "plasma machine". This sputter cleaning is performed with Argon in a plasma within the plasma machine vessel at a pressure of 70 mTorr with 180 watts RF input power at a frequency of 13.56 MHz. The flow rate of Argon is approximately 100 sccm. The partially complete head 100 is situated on a 6 inch diameter cathode (ie. the energized electrode) of the SAMCO plasma machine, Model PD-200D, for approximately 3 to approximately 4 minutes.
Immediately after the Argon plasma cleaning (sputter etching) is complete, the input power is reduced to 110-150 Watts to the same 6 inch cathode electrode. The Argon source is turned off and a source of liquid hydrocarbon DLC source material is turned on. For example, one DLC source material that may be used is Part No. S-12 available from SAMCO, Sunnyvale, Calif. The pressure within the vessel is approximately 20-approximately 25 mTorr at a flow rate of source material of approximately 25 cm.sup.3 /min. Although the temperature is not specifically controlled during this process, the wafer on which the head is fabricated is situated on a water-cooled cathode while in the plasma machine. Under these conditions, a DLC deposition rate of approximately 1000A/min is obtained which is maintained until the desired DLC thickness is reached, namely approximately 5 .mu..
DLC fabricated in this manner results in a DLC layer 385 with a Knoop hardness of approximately 800. It is found that DLC layer Knoop hardnesses of greater than 700 up to approximately 2000 Knoop produce an acceptably hard wear layer 385 for wear protection purposes. DLC wear layer 385 is then reactive ion etched as described to form DLC wear layer 385'.
DLC wear layer 385' is machined as shown in FIG. 19B to expose magnetic gap region 360 as shown in both FIGS. 19A and 19B. DLC wear layer 385' protects head 100, specifically gap region 360 and magnetic poles 345, 365, from wear when head 100 is brought into contact with a magnetic media for recording or playback purposes. By using the methodology described herein, the planarity of the main body 388 of thin film head 100 is maintained. Also, by using the techniques described herein, very narrow gap regions can be produced. The gap width, W.sub.G, is defined to be the width of gap region 360, namely the distance between pole end 345A and pole end 365A as seen in FIG. 19B. Typical gap widths for head 100 are approximately 0.2 microns to approximately 1 micron.
It is noted that in one embodiment of the invention, the upper magnetic pole elements 345 and 365 are plated directly on magnetic side poles 265 and 270, respectively. Advantageously, no intervening structures are required between upper magnetic pole element 345 and magnetic side pole 265 or between magnetic pole element 365 and magnetic side pole 270. Magnetic pole elements 345 and 365 are thus integral with magnetic side poles 265 and 270, respectively.
The foregoing has described a thin film magnetic head in which the lower element of the magnetic yoke and two side poles are built up from a common seed layer, namely seed layer 130. Advantageously, the disclosed thin head achieves substantial planarity in the main body of the head and further exhibits a very narrow gap width which results in correspondingly high density magnetic recording capabilities. The thin film head can be fabricated without excavating a recess within the substrate to contain the head. Moreover, the disclosed thin film head can be fabricated in large quantities using thin film semiconductor fabrication equipment.
While only certain preferred features of the invention have been shown by way of illustration, many modifications and changes will occur. It is, therefore, to be understood that the present claims are intended to cover all such modifications and changes which fall within the true spirit of the invention.
Claims
What is claimed is:
1. A method of fabricating a planar thin film magnetic head comprising the steps of: depositing a main body of the thin film magnetic head on a recessless surface of a substrate such that the planarity of the main body is maintained, the main body further comprising a plurality of thin film layers deposited in a sequence of substeps including the substeps of: depositing a lower magnetic layer on the substrate, the lower magnetic layer having first and second opposed ends; depositing a lower insulative layer on the substrate, the lower insulative layer surrounding the lower magnetic layer and being deposited so as to form a planar surface with the lower magnetic layer; forming and patterning a middle insulative layer to form a first middle insulative layer open region at the first end of the lower magnetic layer and to form a second middle insulative layer open region at the second end of the lower magnetic layer, the middle insulative layer overlying the lower magnetic and insulative layers; subsequently depositing a layer of magnetic material to form a first and a second side pole lower portion in the first and second middle insulative layer open regions, respectively, the first and second side pole lower portions being deposited so as to form a planar surface with the middle insulative layer; subsequently plating a coil layer overlying the middle insulative layer so as to laterally encircle a side pole coil level portion selected from a first and a second side pole coil level portion; subsequently forming and patterning a coil level insulative layer to form a first coil level insulative layer open region above the first middle insulative layer open region and to form a second coil level insulative layer open region above the second middle insulative layer open region, the coil level insulative layer overlying the middle insulative layer; and subsequently depositing a layer of magnetic material to form a first and a second side pole coil level portion in the first and second coil level insulative layer open regions, respectively, the first and second side pole coil level portions being deposited so as to form a planar surface with the coil level insulative layer; forming and patterning a top insulative layer to form a first top insulative layer open region above the first coil level insulative layer open region and to form a second top insulative layer open region above the second coil level insulative layer open region, the top insulative layer overlying the coil level insulative layer; depositing a layer of magnetic material to form a first and a second side pole top portion in the first and second top insulative layer open regions, respectively, the first and second side pole top portions being deposited so as to form a planar surface with the top insulative layer; depositing a first upper magnetic pole element above the first side pole top portion, the first upper magnetic pole element including a first gap end extending toward the second side pole top portion; forming a gap region of nonmagnetic material at the first gap end of the first upper magnetic pole element; and depositing a second upper magnetic pole element above the second side pole top portion, the second upper magnetic pole element including a second gap end situated adjacent to the gap region.
2. The method of claim 1 wherein a sequence of substeps including the coil layer plating substep, the coil level insulative layer forming and patterning substep, and the first and second side pole coil level portion depositing substep, is performed multiple times so that a plurality of coil layers and side pole coil level portions are formed.
3. The method of claim 2 further comprising the step of machining the first upper magnetic pole element, the second upper magnetic pole element and the gap region.
4. The method of claim 2 wherein the middle insulative layer open regions, the coil level insulative layer open regions, and the top insulative layer open regions are formed and patterned such that the side pole lower portions, the side pole coil level portions, and the side pole top portions have respective thicknesses greater than their respective widths.
5. A method of fabricating a planar thin film magnetic head comprising the steps of: depositing a conductive seed layer on a recessless surface of a substrate; depositing a main body of the thin film magnetic head on the conductive seed layer such that the planarity of the main body is maintained, the main body further comprising a plurality of thin film layers deposited in a sequence of substeps including the substeps of: forming and patterning a lower insulative layer to form a lower insulative layer open region, the lower insulative layer overlying the conductive seed layer; subsequently depositing a layer of magnetic material to form a lower magnetic layer in the lower insulative layer open region, the lower magnetic layer having first and second opposed ends, and being deposited so as to form a planar surface with the lower insulative layer; forming and patterning a middle insulative layer to form a first middle insulative layer open region at the first end of the lower magnetic layer and to form a second middle insulative layer open region at the second end of the lower magnetic layer, the middle insulative layer overlying the lower magnetic and insulative layers; subsequently depositing a layer of magnetic material to form a first and a second side pole lower portion in the first and second middle insulative layer open regions, respectively, the first and second side pole lower portions being deposited so as to form a planar surface with the middle insulative layer; subsequently plating a coil layer overlying the middle insulative layer so as to laterally encircle a side pole coil level portion selected from a first and a second side pole coil level portion; subsequently forming and patterning a coil level insulative layer to form a first coil level insulative layer open region above the first middle insulative layer open region and to form a second coil level insulative layer open region above the second middle insulative layer open region, the coil level insulative layer overlying the middle insulative layer; and subsequently depositing a layer of magnetic material to form a first and a second side pole coil level portion in the first and second coil level insulative layer open regions, respectively, the first and second side pole coil level portions being deposited so as to form a planar surface with the coil level insulative layer; forming and patterning a top insulative layer to form a first top insulative layer open region above the first coil level insulative layer open region and to form a second top insulative layer open region above the second coil level insulative layer open region, the top insulative layer overlying the coil level insulative layer; depositing a layer of magnetic material to form a first and a second side pole top portion in the first and second top insulative layer open regions, respectively, the first and second side pole top portions being deposited so as to form a planar surface with the top insulative layer; depositing a first upper magnetic pole element above the first side pole top portion, the first upper magnetic pole element including a first gap end extending toward the second side pole top portion; forming a gap region of nonmagnetic material at the first gap end of the first upper magnetic pole element; and depositing a second upper magnetic pole element above the second side pole top portion, the second upper magnetic pole element including a second gap end situated adjacent to the gap region.
6. The method of claim 5 wherein a sequence of substeps including the coil layer plating substep, the coil level insulative layer forming and patterning substep, and the first and second side pole coil level portion depositing substep, is performed multiple times so that a plurality of coil layers and side pole coil level portions are formed.
7. The method of claim 5 further comprising the step of machining the first upper magnetic pole element, the second upper magnetic pole element and the gap region.
8. The method of claim 5 wherein the middle insulative layer open regions, the coil level insulative layer open regions, and the top insulative layer open regions are formed and patterned such that the side pole lower portions, the side pole coil level portions, and the side pole top portions have respective thicknesses greater than their respective widths.
9. A method of fabricating a planar thin film magnetic head comprising the steps of: depositing a lower insulative layer on a recessless surface of a substrate, the lower insulative layer including an open region; subsequently depositing a lower magnetic layer on the substrate and in the lower insulative layer open region, the lower magnetic layer having first and second opposed ends, and being deposited up to a level even with the lower insulative layer; depositing a middle insulative layer above the lower insulative layer and the lower magnetic layer, the middle insulative layer including a first middle insulative layer open region at the first end of the lower magnetic layer and a second middle insulative layer open region at the second end of the lower magnetic layer; subsequently depositing at least one layer of magnetic material to form a first and a second side pole lower portion in the first and second middle insulative layer open regions, respectively, the first and second side pole lower portions being deposited up to a level even with the middle insulative layer; subsequently forming a coil layer on the middle insulative layer so as to surround a side pole coil level portion selected from a first and a second side pole coil level portion; subsequently depositing a coil level insulative layer above the middle insulative layer and the coil layer, the coil level insulative layer including a first coil level insulative layer open region above the first middle insulative layer open region and a second coil level insulative layer open region above the second middle insulative layer open region; subsequently depositing at least one layer of magnetic material to form the first and the second side pole coil level portion in the first and second coil level insulative layer open regions, respectively, the first and second side pole coil level portions being deposited up to a level even with the coil level insulative layer; depositing a top insulative layer above the coil level insulative layer, the top insulative layer including a first top insulative layer open region above the first coil level insulative layer open region and a second top insulative layer open region above the second coil level insulative layer open region; depositing at least one layer of magnetic material to form a first and a second side pole top portion in the first and second top insulative layer open regions, respectively, the first and second side pole top portions being deposited up to a level even with the top insulative layer; depositing a first upper magnetic pole element above the first side pole top portion, the first upper magnetic pole element including a first gap end extending toward the second side pole top portion; forming a gap region of nonmagnetic material at the first gap end of the first upper magnetic pole element; and depositing a second upper magnetic pole element above the second side pole top portion, the second upper magnetic pole element including a second gap end situated adjacent to the gap region.
10. The method of claim 9 further comprising: depositing a seed layer overlying the substrate before the depositing a lower insulative layer step.
11. The method of claim 10 wherein a sequence of substeps including the forming a coil layer substep, the depositing a coil level insulative layer substep, and the depositing at least one layer of magnetic material to form a first and a second side pole coil level portion substep is performed multiple times so that a plurality of coil layers and side pole coil level portions are formed.
12. The method of claim 10 further comprising the step of machining the first upper magnetic pole element, the second upper magnetic pole element and the gap region.
13. The method of claim 10 wherein the middle insulative layer open regions, the coil level insulative layer open regions, and the top insulative layer open regions are formed and patterned such that the side pole lower portions, the side pole coil level portions, and the side pole top portions have respective thicknesses greater than their respective widths.
14. The method of claim 10 wherein the forming a coil layer step occurs concurrently with the depositing at least one layer of magnetic material to form the first and the second side pole coil level portion step.
15. A method of fabricating a planar thin film magnetic head comprising the steps of: depositing a first seed layer overlying a recessless surface of a substrate; depositing a first photoresist layer on the first seed layer, the first photoresist layer including an open region; plating a lower magnetic layer on the first seed layer in the open region of the first photoresist layer, the lower magnetic layer having first and second opposed ends; depositing a second photoresist layer overlying the first photoresist layer, the second photoresist layer including first and second openings at the first and second opposed ends of the lower magnetic layer, the second photoresist layer including an upper surface; subsequently plating first and second side layers of magnetic material in the first and second openings, respectively, up to a level substantially even with the upper surface of the second photoresist layer, the first and second side layers forming portions of a first and a second side pole, respectively; subsequently depositing a second seed layer overlying the second photoresist layer; plating a coil on the second seed layer, the coil substantially encircling side pole from the first and second side poles; etching away the second seed layer leaving unetched portions of the second seed layer where the coil is plated; subsequently depositing a third photoresist layer above the second photoresist layer and the coil, the third photoresist layer including third and fourth openings above the first and second side layers of magnetic material, the third photoresist layer including an upper surface; subsequently plating third and fourth side layers of magnetic material in the third and fourth openings; respectively, up to a level substantially even with the upper surface of the third photoresist layer, the first and third layers forming the first side pole, the second and fourth layers forming the second side pole; forming a pedestal of photoresist overlying a portion of the upper surface of the third photoresist layer, the pedestal including fifth and sixth openings above the third and fourth side layers of magnetic material, the pedestal including a periphery; forming a frame around the periphery of the pedestal to provide structural integrity to the pedestal; depositing a third seed layer overlying the pedestal so as to avoid the fifth and sixth openings in the pedestal; plating a first magnetic pole element overlying the first side pole and the third seed layer, the first magnetic pole element including a first gap end extending toward the second side pole; forming a gap region of nonmagnetic material at the first gap end of the first upper magnetic pole element; and plating a second magnetic pole element overlying the second side pole and the third seed layer, the second magnetic pole element extending from the second side pole to the gap region.
16. The method of claim 15 further comprising the step of machining the first upper magnetic pole element, the second upper magnetic pole element and the gap region.
17. The method of claim 15 further comprising the steps of: E-beam curing the first photoresist layer subsequent to depositing the first photoresist layer; E-beam curing the second photoresist layer subsequent to depositing the second photoresist layer; and E-beam curing the third photoresist layer subsequent to depositing the third photoresist layer.
18. A method according to claim 15, wherein the step of plating the third seed layer while leaving the fifth and sixth openings in the pedestal unplated includes the substeps of: patterning a layer of photoresist overlying the fifth and sixth openings; sputtering the third seed layer overlying the entire surface of the pedestal including the photoresist overlying the fifth and sixth openings; and lifting off the patterned layer of photoresist and the overlying third seed layer.
19. A method according to claim 18, wherein the lifting off substep further includes the substeps of placing the thin film magnetic head in an ultrasonic bath including a photoresist solvent.
20. A method according to claim 19, wherein the photoresist solvent is acetone.
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