Patent US4003813A successfully refreshed from Google Patents.
US4003813A
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Method of making a magnetic oxide film with high coercive force
Assignee: NTT Inc
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Filing: 1975-08-14
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Granted: 1977-01-18
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Expires: 1995-08-14
Abstract
Abstract A magnetic oxide film manufacturing method is disclosed which involves the steps of sputtering a target made of iron and aluminum to form a film of non-magnetic iron oxide (α-Fe 2 O 3 ) and reducing the film to obtain a magnetic oxide film. When a target made of iron and aluminum is employed, it is possible to obtain a high coercive force magnetic oxide film which is highly adhesive to a substrate, excellent in surface roughness and less than 0.3μm in thickness. Accordingly, it is possible to obtain a magnetic disk of high magnetic recording density.
Inventors
- 👤 Seizi Hattori
- 👤 Nobuo Inagaki
- 👤 Yoshikazu Ishii
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:51
CPC Classifications
C; C23; C23C; C23C14/00; C23C14/58; C23C14/5806; C23C14/06; C23C14/08; C23C14/085; C23C14/5846; H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/18; H01F10/20; H01F41/00; H01F41/14
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
83 words
A method of making a high coercive force magnetic oxide film comprising the steps of sputtering a target made of iron and aluminum in an atmosphere containing an inert gas and oxygen with the oxygen above a certain partial pressure to form on a substrate an α-Fe 2 O 3 non magnetic oxide film having aluminum dissolved therein, and reducing said non-magnetic oxide film under a hydrogen gas atmosphere to yield an Fe 3 O 4 magnetic oxide film having aluminum dissolved therein.
Claim 2
Independent Claim
83 words
A method of making a high coercive force magnetic oxide film comprising the steps of sputtering a target made of iron and aluminum in an atmosphere containing an inert gas and oxygen with the oxygen above a certain partial pressure to form on a substrate an α-Fe 2 O 3 non magnetic oxide film having aluminum dissolved therein, and reducing said non-magnetic oxide film under a hydrogen gas atmosphere to yield an Fe 3 O 4 magnetic oxide film having aluminum dissolved therein.
Claim 3
Dependent Claim
57 words
A method of making a high coercive force magnetic oxide film according to claim 1 wherein said target made of iron and aluminum is a target formed from an iron plate and having mounted thereon small pieces of aluminum and the ratio of surface area of said aluminum pieces to said iron plate is 2 to 4%.
Claim 4
Dependent Claim
37 words
A method of making a high coercive force magnetic oxide film according to claim 1 wherein said target made of iron and aluminum is formed of an iron- aluminum alloy with aluminum content of 1 to 2%.
Claim 5
Dependent Claim
37 words
A method of making a high coercive force magnetic oxide film according to claim 1 wherein said inert gas is argon and said oxygen is held above a partial pressure of 3 × 10 - 3 Torr.
Claim 6
Dependent Claim
40 words
A method of making a high coercive force magnetic oxide film according to claim 1 wherein the reduction of said non-magnetic oxide under hydrogen gas atmosphere is carried out at a temperature in the range of 280° to 320° C.
Claim 7
Independent Claim
101 words
A method of making a high coercive force magnetic oxide film comprising the steps of sputtering a target in a mixed atmosphere of argon and oxygen held at a partial pressure 3 × 10 - 3 to form an α-Fe 2 O 3 non-magnetic oxide film having aluminum dissolved therein, said target being formed from an iron plate and having mounted thereon small aluminum pieces with a surface area ratio of 2 to 4% relative to said iron plate, and reducing said non-magnetic oxide under a hydrogen atmosphere at 280° to 320° C to form magnetic oxide having aluminum dissolved therein.
Claim 8
Independent Claim
101 words
A method of making a high coercive force magnetic oxide film comprising the steps of sputtering a target in a mixed atmosphere of argon and oxygen held at a partial pressure 3 × 10 - 3 to form an α-Fe 2 O 3 non-magnetic oxide film having aluminum dissolved therein, said target being formed from an iron plate and having mounted thereon small aluminum pieces with a surface area ratio of 2 to 4% relative to said iron plate, and reducing said non-magnetic oxide under a hydrogen atmosphere at 280° to 320° C to form magnetic oxide having aluminum dissolved therein.
Claim 9
Independent Claim
98 words
A method of making a high coercive force magnetic film comprising the steps of sputtering a target in a mixed atmosphere of argon and oxygen held at a partial pressure above 3 × 10 - 3 Torr to form on a substrate an α-Fe 2 O 3 non-magnetic oxide film having aluminum dissolved therein, said target being made of an ironaluminum alloy composed of 1 to 2% of aluminum and the remainder iron, and reducing said non-magnetic oxide film under a hydrogen atmosphere at 280° to 320° C to form a magnetic oxide film having aluminum dissolved therein.
Claim 10
Independent Claim
98 words
A method of making a high coercive force magnetic film comprising the steps of sputtering a target in a mixed atmosphere of argon and oxygen held at a partial pressure above 3 × 10 - 3 Torr to form on a substrate an α-Fe 2 O 3 non-magnetic oxide film having aluminum dissolved therein, said target being made of an ironaluminum alloy composed of 1 to 2% of aluminum and the remainder iron, and reducing said non-magnetic oxide film under a hydrogen atmosphere at 280° to 320° C to form a magnetic oxide film having aluminum dissolved therein.
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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) | 1980-01-18 | 1980-07-19 | 1981-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-18 | 1984-07-19 | 1985-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-18 | 1988-07-19 | 1989-01-18 | $7700.00 | Window Closed / Lapsed |