US4436593A
Expired / Lapsed
US
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Self-aligned pole tips
Assignee: Unisys Corp
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Filing: 1981-07-13
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Granted: 1984-03-13
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Expires: 2001-07-13
Abstract
Abstract A method is disclosed for precisely aligning the pole tips of a thin film magnetic head. Two separate metallic layers, such as Permalloy (Ni-Fe alloy) are separated by a layer of insulating material such as silicon dioxide or AL 2 O 3 which will serve as the insulative spacer of the final magnetic head. A photo-resist is applied to the surface of the top metallic layer in an imagewise configuration to establish the shape of the top pole. The top pole is then etched and the photo-resist removed. The top electrode is then encapsulated with a protective metal and is used as a mask during the chemical etching of the insulative layer, the bottom electrode being used as an etch stop. This integral structure is then used as a mask during the chemical etching of the bottom electrode, resulting in pole tips which are precisely aligned.
Inventors
- 👤 John R. Osborne
- 👤 Peter G. Bischoff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:56
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/31; G11B5/3163; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49036; Y10T29/49043; Y10T29/49044; Y10T29/49046
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
178 words
A method of precisely aligning the pole tips of a thin film magnetic head comprising: a. applying to a support, two metallic layers separated by an insulative layer, these all being superposed on one another, said metallic layers to become the pole tips of the magnetic head; a "first" one of said metallic layers being applied to said support; the insulative layer being then applied over said "first" metallic layer, and a "second" metallic layer being then applied on said insulative layer; b. applying a photo-resist to the surface of said "second", or "top" metallic layer in imagewise configuration to establish the shape of the top pole; c. etching the top metallic layer to the insulative layer in areas not protected by the photo-resist thus forming the top pole; d. removing the photo-resist and encapsulating the top pole with a protective metal; e. etching the insulative layer using the top pole as a mask; and f. etching the "first", or "bottom" metallic layer using the top pole and insulative layer as a mask to form the bottom pole.
Claim 2
Independent Claim
178 words
A method of precisely aligning the pole tips of a thin film magnetic head comprising: a. applying to a support, two metallic layers separated by an insulative layer, these all being superposed on one another, said metallic layers to become the pole tips of the magnetic head; a "first" one of said metallic layers being applied to said support; the insulative layer being then applied over said "first" metallic layer, and a "second" metallic layer being then applied on said insulative layer; b. applying a photo-resist to the surface of said "second", or "top" metallic layer in imagewise configuration to establish the shape of the top pole; c. etching the top metallic layer to the insulative layer in areas not protected by the photo-resist thus forming the top pole; d. removing the photo-resist and encapsulating the top pole with a protective metal; e. etching the insulative layer using the top pole as a mask; and f. etching the "first", or "bottom" metallic layer using the top pole and insulative layer as a mask to form the bottom pole.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein the metallic layers are comprised of Ni-Fe alloy.
Claim 4
Dependent Claim
23 words
The method of claim 2 wherein the metallic layers are etched by spray etching with a solution of FeCl 3 in ethylene glycol.
Claim 5
Dependent Claim
18 words
The method of claim 1 wherein the insulative layer is SiO 2 or Al 2 O 3 .
Claim 6
Dependent Claim
17 words
The method of claim 4 wherein the SiO 2 layer is etched with a buffered HF solution.
Claim 7
Dependent Claim
21 words
The method of claim 4 wherein the Al 2 O 3 is etched in a mixture of nitric, HF, and water.
Claim 8
Dependent Claim
22 words
The method of claim 1 wherein the protective metal comprises a metal selected from the group consisting of silver, gold and rhodium.
Claim 9
Dependent Claim
24 words
The method of claim 7 wherein the protective metal is applied to the top electrode by electroplating the protective metal through a bus bar.
Claim 10
Dependent Claim
11 words
The method of claim 1 wherein the protective metal is rhodium.
Claim 11
Dependent Claim
17 words
The method of claim 1 wherein the protective metal is removed after formation of the bottom pole.
Claim 12
Dependent Claim
15 words
The method of claim 1 wherein the poles are approximate 40-140 micro inches in thickness.
Claim 13
Dependent Claim
14 words
The method of claim 1 wherein the insulative layer is removed by ion milling.
Claim 14
Dependent Claim
155 words
In a method for fabricating a thin film magnetic head, wherein the pole tips are very precisely aligned, the steps of: applying a first magnetic layer to base means; applying a non-magnetic spacer layer on this first magnetic layer; applying a second magnetic layer on this spacer layer; applying photo-resist atop the second magnetic layer, such as to outline it for etching into a prescribed top-pole configuration; etching said second magnetic layer to form a configured "top-pole" and removing said photo-resist; encapsulating the so-generated "top-pole" against a prescribed later etching of said spacer and first magnetic layers by covering it with a prescribed coating of protective metal; etching away all portions of said spacer layer not so-masked by said so-encapsulated "top-pole" structure, and likewise etching away all portions of said first magnetic layer not masked by the top-pole and the spacer layer to leave a "bottom pole" structure very precisely aligned with the so-superposed "top-pole".
Claim 15
Dependent Claim
155 words
In a method for fabricating a thin film magnetic head, wherein the pole tips are very precisely aligned, the steps of: applying a first magnetic layer to base means; applying a non-magnetic spacer layer on this first magnetic layer; applying a second magnetic layer on this spacer layer; applying photo-resist atop the second magnetic layer, such as to outline it for etching into a prescribed top-pole configuration; etching said second magnetic layer to form a configured "top-pole" and removing said photo-resist; encapsulating the so-generated "top-pole" against a prescribed later etching of said spacer and first magnetic layers by covering it with a prescribed coating of protective metal; etching away all portions of said spacer layer not so-masked by said so-encapsulated "top-pole" structure, and likewise etching away all portions of said first magnetic layer not masked by the top-pole and the spacer layer to leave a "bottom pole" structure very precisely aligned with the so-superposed "top-pole".
Claim 16
Dependent Claim
14 words
The method of claim 13 wherein the magnetic layers are comprised of Ni-Fe alloy.
Claim 17
Dependent Claim
24 words
The method of claim 14 wherein the magnetic layers are etched chemically by spray etching with a solution of FeCl 3 in ethylene glycol.
Claim 18
Dependent Claim
18 words
The method of claim 13 wherein the insulative layer is SiO 2 or Al 2 O 3 .
Claim 19
Dependent Claim
17 words
The method of claim 16 wherein the SiO 2 layer is etched with a buffered HF solution.
Claim 20
Dependent Claim
21 words
The method of claim 16 wherein the Al 2 O 3 is etched in a mixture of nitric, HF, and water.
Claim 21
Dependent Claim
22 words
The method of claim 13 wherein the protective metal comprises a metal selected from the group consisting of silver, gold and rhodium.
Claim 22
Dependent Claim
11 words
The method of claim 19 wherein the protective metal is rhodium.
Claim 23
Dependent Claim
23 words
The method of claim 19 wherein the encapsulation of the "top-pole" is effected by electroplating the protective metal thereon through a bus bar.
Claim 24
Dependent Claim
17 words
The method of claim 13 wherein the protective metal is removed after formation of the bottom pole.
Claim 25
Dependent Claim
15 words
The method of claim 13 wherein the poles are approximate 40-140 micro inches in thickness.
Claim 26
Dependent Claim
14 words
The method of claim 13 wherein the insulative layer is removed by ion milling.
Claim 27
Dependent Claim
28 words
The method of claim 13 wherein the magnetic layers are comprised of Ni-Fe alloy and wherein the insulative layer is SiO 2 or Al 2 O 3 .
Claim 28
Dependent Claim
22 words
The method of claim 25 wherein the protective metal comprises a metal selected from the group consisting of silver, gold and rhodium.
Claim 29
Dependent Claim
11 words
The method of claim 26 wherein the protective metal is rhodium.
Claim 30
Dependent Claim
15 words
The method of claim 27 wherein the poles are approximate 40-140 micro inches in thickness.
Claim 31
Dependent Claim
34 words
The method of claim 28 wherein the SiO 2 layer is etched with a buffered HF solution, and wherein the Al 2 O 3 is etched in a mixture of nitric, HF, and water.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-13 | 1987-09-12 | 1988-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-13 | 1991-09-12 | 1992-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-13 | 1995-09-12 | 1996-03-13 | $7700.00 | Window Closed / Lapsed |