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US4364099A
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Tantalum thin film capacitor
Assignee: Fujitsu Ltd
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Filing: 1980-08-20
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Granted: 1982-12-14
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Expires: 2000-08-20
Abstract
Abstract A tantalum film capacitor has an α-tantalum as a lower electrode, a chemical conversion layer of α-tantalum as a dielectric and an upper electrode, an improvement involving forming a highly nitrogen-doped tantalum film between the α-tantalum and a substrate, and also, another improvement involving forming a transitional thin tantalum layer between said highly nitrogen-doped tantalum film and said α-tantalum. The nitrogen concentration of the highly nitrogen-doped tantalum film is from 14 to 30 atomic %. The electrical properties, especially leakage current, are improved over those of the prior art. A disadvantage of the conventional α-tantalum thin film capacitor, that is the necessity of using an expensive partial glazed Al 2 O 3 substrate, is eliminated, and a non-glazed Al 2 O 3 substrate can be used in the present invention.
Inventors
- 👤 Masataka Koyama
- 👤 Kiyoshi Satoh
- 👤 Minoru Terashima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:38
CPC Classifications
H; H10; H10D; H10D86/00; H10D86/80; H10D86/85; H01; H01G; H01G4/00; H01G4/002; H01G4/018; H01G4/06; H01G4/08; H01G4/10
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
90 words
A tantalum thin film capacitor comprising: a highly nitrogen-doped tantalum film, having a nitrogen concentration of from 14 to 30 atomic %; a lower electrode formed on the highly nitrogen-doped tantalum film and comprising an α-tantalum thin film, said thin film having a nitrogen concentration of from 6 to 15 atomic %, but lower than the nitrogen concentration of the highly nitrogen-doped tantalum film; a dielectric layer formed on the lower electrode and comprising a chemical conversion film of the α-tantalum; and an upper electrode formed on the dielectric layer.
Claim 2
Dependent Claim
90 words
A tantalum thin film capacitor comprising: a highly nitrogen-doped tantalum film, having a nitrogen concentration of from 14 to 30 atomic %; a lower electrode formed on the highly nitrogen-doped tantalum film and comprising an α-tantalum thin film, said thin film having a nitrogen concentration of from 6 to 15 atomic %, but lower than the nitrogen concentration of the highly nitrogen-doped tantalum film; a dielectric layer formed on the lower electrode and comprising a chemical conversion film of the α-tantalum; and an upper electrode formed on the dielectric layer.
Claim 3
Dependent Claim
58 words
A tantalum thin film capacitor according to claim 1, wherein between the highly nitrogen-doped tantalum film and the lower electrode, a transitional tantalum thin layer is formed, and the nitrogen concentration at the boundaries between said highly nitrogen-doped tantalum film and said transitional thin film and between said transitional thin film and said lower electrode is gradually changed.
Claim 4
Dependent Claim
24 words
A tantalum thin film capacitor according to claim 1 or 2, wherein said highly nitrogen-doped tantalum film is formed on a non-glazed alumina substrate.
Claim 5
Dependent Claim
29 words
A tantalum thin film capacitor according to claim 3, wherein the nitrogen concentration of said α-tantalum thin film is in the range of from 6 to 12 atomic %.
Claim 6
Dependent Claim
30 words
A tantalum thin film capacitor according to claim 3, wherein the nitrogen concentration of said highly nitrogen-doped tantalum film is in the range of from 20 to 30 atomic %.
Claim 7
Dependent Claim
23 words
The capacitor of claim 4, wherein the nitrogen concentration of said α-tantatum thin film is in the range from 10 to 12 atomic%.
Claim 8
Dependent Claim
24 words
The capacitor of claim 1 or 2, said highly nitrogen doped tantalum film having a thickness in the range from 1000 to 2000 angstroms.
Claim 9
Dependent Claim
23 words
The capacitor of claim 1 or 2, said chemical conversion film having a thickness approximately in the range from 5000 to 6000 angstroms.
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) | 1985-12-13 | 1986-06-14 | 1986-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-12-13 | 1990-06-14 | 1990-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-12-13 | 1994-06-14 | 1994-12-14 | $7700.00 | Window Closed / Lapsed |