US4272347A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bubble memory optimization by adjusting properties of quartz film
Assignee: Unisys Corp
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Filing: 1977-10-05
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Granted: 1981-06-09
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Expires: 1997-10-05
Abstract
Abstract A bubble memory device and method of fabrication are disclosed which establish that there is a correlation between bubble memory performance and the properties of a quartz film, which is interposed between the bubble film and metallic overlays, namely, the permalloy and/or conductor layers of the device. Specifically, it has been established that there is a correlation between improved device performance and a low p-etch rate which is a measurement that establishes certain elastic constants of the quartz (i.e., the response of the device to stress).
Inventors
- 👤 Martin J. Casey
- 👤 Barry F. Stein
- 👤 Herman E. Wetterskog
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:13
CPC Classifications
H; H01; H01F; H01F10/00; H01F10/26; H01F10/30; H01F41/00; H01F41/32; H01F41/34
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
73 words
The method of fabricating an improved bubble memory device having at least one quartz layer separating two conductive surfaces comprising the step of a. depositing said layer with a p-etch rate on the order of 4 A/second at approximately a 60° C. substrate temperature, said rate providing said quartz with a characteristic to minimize local stress fields formed in a bubble layer of said memory device wherein said minimization optimizes said device performance.
Claim 2
Independent Claim
73 words
The method of fabricating an improved bubble memory device having at least one quartz layer separating two conductive surfaces comprising the step of a. depositing said layer with a p-etch rate on the order of 4 A/second at approximately a 60° C. substrate temperature, said rate providing said quartz with a characteristic to minimize local stress fields formed in a bubble layer of said memory device wherein said minimization optimizes said device performance.
Claim 3
Independent Claim
119 words
The method of depositing a quartz layer on a garnet film substrate wafer of a bubble memory device by means of a vacuum enclosed R.F. sputtering system having an anode table and cathode comprising the steps of: a. providing an intimate thermal contact between said anode table and said wafer; b. providing a gas pressure for sputtering within said system on the order of 10 microns; c. maintaining said anode at approximately 40° C. and and at d.c. ground potential; d. applying energy to said cathode to provide a power density of 3 watts/cm 2 , and maintaining said cathode at a potential on the order of 1,700 volts; e. maintaining the p-etch rate at a relatively low value.
Claim 4
Independent Claim
119 words
The method of depositing a quartz layer on a garnet film substrate wafer of a bubble memory device by means of a vacuum enclosed R.F. sputtering system having an anode table and cathode comprising the steps of: a. providing an intimate thermal contact between said anode table and said wafer; b. providing a gas pressure for sputtering within said system on the order of 10 microns; c. maintaining said anode at approximately 40° C. and and at d.c. ground potential; d. applying energy to said cathode to provide a power density of 3 watts/cm 2 , and maintaining said cathode at a potential on the order of 1,700 volts; e. maintaining the p-etch rate at a relatively low value.
Claim 5
Dependent Claim
27 words
The method of fabricating an improved bubble memory device in accordance with claim 2 wherein the sputter gas is a mixture of 90% argon and 10% oxygen.
Claim 6
Dependent Claim
25 words
The method of fabricating an improved bubble memory device in accordance with claim 2 wherein the p-etch rate is maintained at approximately 4 A-6 A/second.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-06-08 | 1984-12-08 | 1985-06-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-08 | 1988-12-08 | 1989-06-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-08 | 1992-12-08 | 1993-06-09 | $7700.00 | Window Closed / Lapsed |