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EP0024863A2
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A tantalum thin film capacitor and process for producing the same
Assignee: Fujitsu Ltd
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Filing: 1980-08-18
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Granted: —
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Expires: 2000-08-18
Abstract
Abstract In a tantalum thin film capacitor, comprising an a-tantalum as a lower electrode, a chemical conversion layer of a-tantalum as dielectrics and an upper electrode, an improvement which comprises forming a highly nitrogen-doped tantalum film between the a-tantalum and a substrate, and also, another improvement which comprises forming a transitional thin tantalum layer between said highly nitrogen-doped tantalum film and said a-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 a-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
EP
Data Source
google_patents
Last Synchronized
2026-11-09 03:56
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: 17
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 a-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 a-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 a-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 a-tantalum, and; an upper electrode formed on the dielectric layer.
Claim 3
Dependent Claim
57 words
A tantalum thin film capacitor according to claim, 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 a-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
104 words
A process for producing a tantalum thin film capacitor comprising the steps of: forming on a substrate a highly nitrogen--doped tantalum film having a nitrogen concentration of from 14 to 30 atomic %; forming on said highly nitrogen-doped tantalum film an a-tantalum thin film having a nitrogen concentration of from 6 to 15 atomic %, but lower than the nitrogen concentration of said highly nitrogen-doped tantalum film; subjecting said a-tantalum thin film to an anodic oxidation, thereby converting the upper part thereof to a dielectric layer and leaving the lower part as a lower electrode, and; forming on said dielectric layer an upper electrode.
Claim 8
Dependent Claim
104 words
A process for producing a tantalum thin film capacitor comprising the steps of: forming on a substrate a highly nitrogen--doped tantalum film having a nitrogen concentration of from 14 to 30 atomic %; forming on said highly nitrogen-doped tantalum film an a-tantalum thin film having a nitrogen concentration of from 6 to 15 atomic %, but lower than the nitrogen concentration of said highly nitrogen-doped tantalum film; subjecting said a-tantalum thin film to an anodic oxidation, thereby converting the upper part thereof to a dielectric layer and leaving the lower part as a lower electrode, and; forming on said dielectric layer an upper electrode.
Claim 9
Dependent Claim
47 words
A process for producing a tantalum thin film capacitor according to claim, wherein said highly nitrogen--doped tantalum film and said a-tantalum thin film are formed in a magnetron sputtering assembly without removing said substrate from said assembly, but changing the nitrogen content of a nitrogen-containing sputtering atmosphere.
Claim 10
Dependent Claim
49 words
A process for producing a tantalum thin film capacitor according to claim 7, wherein the sputtering discharge is stopped while the nitrogen content of the nitrogen-containing sputtering atmosphere is changed, and the sputtering discharge is initiated when said nitrogen content is such that said a-tantalum thin film is formed.
Claim 11
Dependent Claim
141 words
A process for producing a tantalum thin film capacitor comprising the steps of: forming on a substrate a highly nitrogen--doped tantalum film having a nitrogen concentration of from 14 to 30 atomic %; forming on said highly nitrogen-doped tantalum film a transitional thin tantalum layer, wherein during the formation of said transitional thin tantalum layer the nitrogen concentration of a nitrogen source for introducing nitrogen into the tantalum is continuously decreased; forming on said transitional thin layer an a-tantalum thin film having a nitrogen concentration of from 6 to 15 atomic %, but lower than the nitrogen concentration of said highly nitrogen-doped tantalum film; subjecting said a-tantalum thin film to an anodic oxidation, thereby converting the upper part thereof to a dielectric layer and leaving the lower part as a lower electrode, and; forming on said dielectric layer an upper electrode.
Claim 12
Dependent Claim
141 words
A process for producing a tantalum thin film capacitor comprising the steps of: forming on a substrate a highly nitrogen--doped tantalum film having a nitrogen concentration of from 14 to 30 atomic %; forming on said highly nitrogen-doped tantalum film a transitional thin tantalum layer, wherein during the formation of said transitional thin tantalum layer the nitrogen concentration of a nitrogen source for introducing nitrogen into the tantalum is continuously decreased; forming on said transitional thin layer an a-tantalum thin film having a nitrogen concentration of from 6 to 15 atomic %, but lower than the nitrogen concentration of said highly nitrogen-doped tantalum film; subjecting said a-tantalum thin film to an anodic oxidation, thereby converting the upper part thereof to a dielectric layer and leaving the lower part as a lower electrode, and; forming on said dielectric layer an upper electrode.
Claim 13
Dependent Claim
53 words
A process for producing a tantalum thin film capacitor according to claim 9, wherein said highly nitrogen-doped tantalum film, said transitional thin tantalum layer and said a-tantalum thin film are formed in a magnetron sputtering assembly without removing said substrate from said assembly, but changing the nitrogen content of a nitrogen-containing sputtering atmosphere.
Claim 14
Dependent Claim
37 words
A process for producing a tantalum thin film capacitor according to claim 10, wherein the sputtering discharge is continued, while the nitrogen content of the nitrogen-containing sputtering atmosphere is changed, thereby forming said transitional thin tantalum layer.
Claim 15
Dependent Claim
39 words
A process for producing a tantalum thin film capacitor according to claim 6, 7, 8, 9. 10 or 11, wherein the nitrogen concentration of said a-tantalum thin film is in the range of from 6 to 12 atomic %.
Claim 16
Dependent Claim
40 words
A process for producing a tantalum thin film capacitor according to claim 6, 7, 8, 9, 10 or 11, wherein the nitrogen concentration of said highly nitrogen-doped tantalum film is in the range of from 20 to 30 atomic %.
Claim 17
Dependent Claim
32 words
A process for producing a tantalum thin film capacitor according to claim 6, 7, 8, 9, 10 or 11, wherein said highly nitrogen-doped tantalum film is formed on a non-glazed alumina substrate.
References Cited (Backward Citations)
No citation records indexed.
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