Patent US4013534A successfully refreshed from Google Patents.
US4013534A
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Method of making a magnetic oxide film
Assignee: NTT Inc
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Filing: 1975-10-14
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Granted: 1977-03-22
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Expires: 1995-10-14
Abstract
Abstract In the process of sputtering of an iron target in an atmosphere composed of a mixed gas containing a rare gas and oxygen, the oxygen partial pressure is regulated prior to both presputtering and main sputtering, by which ferromagnetic oxide Fe 3 O 4 is deposited on a substrate in one process. By setting the temperature of the substrate at 150° to 250° C, the coercive force and the squareness ratio of the oxide film is greatly enhanced. By using the oxide film as a medium of a magnetic disk storage, a magnetic recording and storage device of excellent characteristics can be obtained.
Inventors
- 👤 Yoshikazu Ishii
- 👤 Seizi Hattori
- 👤 Nobuo Inagaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:10
CPC Classifications
H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/18; H01F10/20; C; C23; C23C; C23C14/00; C23C14/06; C23C14/08; C23C14/085; H01F41/00; H01F41/14
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
146 words
A method of making a magnetic oxide film on a substrate by sputtering thereto from an iron target in an atmosphere composed of a mixed gas containing an inert gas and oxygen, with the partial pressure of the oxygen being regulated, said method comprising the steps of: pre-sputtering the iron target in the oxygen-argon atmosphere while maintaining the oxygen partial pressure between 1 × 10 - 3 and 2 × 10 - 3 Torr, with a shutter being disposed between the iron target and the substrate; and sputtering from the iron target to the substrate in the oxygen-argon atmosphere while maintaining the oxygen partial pressure between 3 × 10 - 3 and 6 × 10 - 3 Torr, with the shutter being removed from between the iron target and the substrate, thereby depositing a magnetite thin film of single-phase Fe 3 O 4 on the substrate.
Claim 2
Independent Claim
146 words
A method of making a magnetic oxide film on a substrate by sputtering thereto from an iron target in an atmosphere composed of a mixed gas containing an inert gas and oxygen, with the partial pressure of the oxygen being regulated, said method comprising the steps of: pre-sputtering the iron target in the oxygen-argon atmosphere while maintaining the oxygen partial pressure between 1 × 10 - 3 and 2 × 10 - 3 Torr, with a shutter being disposed between the iron target and the substrate; and sputtering from the iron target to the substrate in the oxygen-argon atmosphere while maintaining the oxygen partial pressure between 3 × 10 - 3 and 6 × 10 - 3 Torr, with the shutter being removed from between the iron target and the substrate, thereby depositing a magnetite thin film of single-phase Fe 3 O 4 on the substrate.
Claim 3
Dependent Claim
22 words
The method according to claim 1 wherein said substrate is held at a temperature in the range of 150° to 250° C.
Claim 4
Dependent Claim
33 words
The method according to claim 1 which further includes the step of annealing said magnetite film in an air atmosphere, while the substrate is held at a temperature of 150° to 250° C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-21 | 1980-09-20 | 1981-03-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-21 | 1984-09-20 | 1985-03-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-21 | 1988-09-20 | 1989-03-22 | $7700.00 | Window Closed / Lapsed |