US4375390A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thin film techniques for fabricating narrow track ferrite heads
Assignee: International Business Machines Corp
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Filing: 1982-03-15
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Granted: 1983-03-01
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Expires: 2002-03-15
Abstract
Abstract A process for producing a reactive ion-etched structure with height and width dimensions of the order of 25 microns or less on a ferrite substrate surface is disclosed. A mask of positive water saturated photoresist is formed on the substrate. A metal taken from the group consisting of nickel and a nickel-iron alloy is plated through the mask. The photoresist mask is removed to leave a pattern in the plated metal. The ferrite substrate surface that is exposed by the pattern is reactive ion etched with a power density of >1w/cm2 and a bias voltage <-100 volts.
Inventors
- 👤 Nathaniel C. Anderson
- 👤 Larry E. Daby
- 👤 Vincent D. Gravdahl
- 👤 Patrick M. McCaffrey
- 👤 Bruce A. Murray
- 👤 Bruce W. Wright
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:19
CPC Classifications
H; H01; H01F; H01F41/00; H01F41/32; H01F41/34; G; G03; G03F; G03F7/00; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/193
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
119 words
A process for producing a reactive ion etched structure with height and width dimensions of the order of 25 microns or less on a ferrite substrate surface comprising the steps of depositing an electrically conductive layer on the substrate surface, forming a mask of positive photoresist on said conductive layer, plating said conductive layer exposed by said mask with one of the group consisting of nickel and nickel-iron alloys, removing said photoresist mask to leave a pattern of said plated metal, reactive-ion etching the ferrite substrate surface that is exposed by said pattern with a power of >1 watts/cm 2 of cathode area and a bias voltage <-100 volts, and removing said metal pattern to leave said etched structure.
Claim 2
Dependent Claim
119 words
A process for producing a reactive ion etched structure with height and width dimensions of the order of 25 microns or less on a ferrite substrate surface comprising the steps of depositing an electrically conductive layer on the substrate surface, forming a mask of positive photoresist on said conductive layer, plating said conductive layer exposed by said mask with one of the group consisting of nickel and nickel-iron alloys, removing said photoresist mask to leave a pattern of said plated metal, reactive-ion etching the ferrite substrate surface that is exposed by said pattern with a power of >1 watts/cm 2 of cathode area and a bias voltage <-100 volts, and removing said metal pattern to leave said etched structure.
Claim 3
Dependent Claim
30 words
A process as described in claim 1 whereby the ferrite substrate surface exposed by said pattern is reactive-ion etched with a power density of 1.7 to 3.0 watts/cm 2 .
Claim 4
Dependent Claim
28 words
A process as described in claim 1 whereby the ferrite substrate surface exposed by said pattern is reactive-ion etched with a bias voltage of -1400 to -1900 volts.
Claim 5
Dependent Claim
20 words
A process as described in claim 1 whereby the mask is at least two microns thicker than said pattern thickness.
Claim 6
Dependent Claim
32 words
A process as described in claim 1 whereby after a prebake step, said mask is exposed to a high humidity in order to increase the H 2 O content of said mask.
Claim 7
Dependent Claim
28 words
A process as described in claim 1 wherein the plating layer is at least the desired substrate etch depth divided by the etch ratio plus about 2 micronmeters.
Claim 8
Dependent Claim
26 words
A process as described in claim 1 whereby the substrate is at a temperature of 250° C. to 300° C. during the reactive ion etch step.
Claim 9
Dependent Claim
15 words
A process as described in claim 1 whereby the reactive gas includes a halogenated hydrocarbon.
Claim 10
Dependent Claim
15 words
A process as described in claim 1 whereby nickel is plated on said conductive layer.
Claim 11
Dependent Claim
18 words
A process as described in claim 1 whereby the pH of the electroplating bath is 3.5 to 4.5.
References Cited (Backward Citations)
US3808108A
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US3984300A
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US4259433A
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US4124473A
Cited
US4256514A
Cited
US4275286A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-28 | 1986-08-30 | 1987-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-28 | 1990-08-30 | 1991-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-28 | 1994-08-30 | 1995-03-01 | $7700.00 | Window Closed / Lapsed |