EP0747937A2
Expired / Lapsed
EP
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Ferroelectric thin film coated substrate, producing method thereof and capacitor structure element using thereof
Assignee: Sharp Corp
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Filing: 1996-05-02
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Granted: —
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Expires: 2016-05-02
Abstract
Abstract A ferroelectric thin film coated substrate is obtained by a producing method of forming a crystalline thin film on a substrate by means of a MOCVD method at a substrate temperature at which crystal grows and of forming a ferroelectric thin film on the crystalline thin film by means of the MOCVD method at a film forming temperature, which is lower than the film forming temperature of the crystalline thin film. This producing method makes it possible to produce a ferroelectric thin film, where a surface of the thin film is dense and even, leakage current properties are excellent and sufficiently large remanent spontaneous polarization is shown, at a lower temperature.
Inventors
- 👤 Sakiko Satoh
- 👤 Takeshi Kijima
- 👤 Hironori Matsunaga
- 👤 Masayoshi Koba
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 10:01
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/682; H10D1/684
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
50 words
A ferroelectric thin film coated substrate, comprising: a substrate; a crystalline thin film formed on said substrate at a first substrate temperature at which crystal grows; and a ferroelectric thin film formed on said crystalline thin film at a second substrate temperature which is lower than the first substrate temperature.
Claim 2
Dependent Claim
37 words
The ferroelectric thin film coated substrate as defined in claim 1, wherein a particle diameter of crystal grains composing said crystalline thin film is smaller than a particle diameter of crystal grains composing said ferroelectric thin film.
Claim 3
Dependent Claim
31 words
The ferroelectric thin film coated substrate as defined in claim 1, wherein a film thickness of said crystalline thin film is smaller than a film thickness of said ferroelectric thin film.
Claim 4
Dependent Claim
81 words
The ferroelectric thin film coated substrate as defined in claim 3, wherein: the film thickness of said crystalline thin film is in the range of 5 nm to 10 nm, the thickness of said ferroelectric thin film is in the range of 5 nm to 300 nm (however, the range of 5 nm to 10 nm is limited to the case where the film thickness of said crystalline thin film is smaller than the film thickness of the ferroelectric thin film).
Claim 5
Dependent Claim
35 words
The ferroelectric thin film coated substrate as defined in claim 1, wherein at least one of constituent elements of said crystalline thin film is same as one of constituent elements of said ferroelectric thin film.
Claim 6
Dependent Claim
31 words
The ferroelectric thin film coated substrate as defined in claim 5, wherein said crystalline thin film is composed of bismuth titanate and the ferroelectric thin film is composed of bismuth titanate.
Claim 7
Dependent Claim
36 words
The ferroelectric thin film coated substrate as defined in claim 6, wherein said crystalline thin film and said ferroelectric thin film are made of Bi 4 Ti 3 O 12 with random orientation including a-axis orientation.
Claim 8
Dependent Claim
40 words
The ferroelectric thin film coated substrate as defined in claim 6, wherein said crystalline thin film is made of Bi 2 Ti 2 O 7 and said ferroelectric thin film is made of Bi 4 Ti 3 O 12 .
Claim 9
Dependent Claim
28 words
The ferroelectric thin film coated substrate as defined in claim 1, wherein said ferroelectric thin film is composed of a Bi ferroelectric material having a layered perovskite structure.
Claim 10
Dependent Claim
40 words
The ferroelectric thin film coated substrate as defined in claim 1, wherein said ferroelectric thin film is composed of a material which is selected from a group of PZT, PLZT, SrTiO 3 and Ba 1-X Sr X TiO 3 .
Claim 11
Dependent Claim
60 words
The ferroelectric thin film coated substrate as defined in claim 1, wherein: the first substrate temperature is in the rage of 450°C to 650°C, the second substrate temperature is in the range of 400°C to 500°C (however, the range of 450°C to 500°C is limited to the case where the second substrate temperature is lower than the first substrate temperature).
Claim 12
Independent Claim
60 words
A method of producing a ferroelectric thin film coated substrate, comprising: the first step of forming a crystalline thin film on a substrate at a first substrate temperature at which crystal grows; and the second step of forming a ferroelectric thin film on said crystalline thin film at a second substrate temperature which is lower than the first substrate temperature.
Claim 13
Dependent Claim
76 words
The producing method as defined in claim 12, wherein: said first step is the step for heating the substrate heated to the first substrate temperature so as to form said crystalline thin film on the substrate by means of a MOCVD method, said second step is the step for maintaining the substrate at the second substrate temperature so as to form said ferroelectric thin film on said crystalline thin film by means of the MOCVD method.
Claim 14
Dependent Claim
65 words
The producing method as defined in claim 12, wherein: the first substrate temperature in said first step is in the range of 450°C to 650°C, the second substrate temperature in said second step is in the range of 400°C to 500°C (however, the range of 450°C to 500°C is limited to the case where the second substrate temperature is lower than the first substrate temperature).
Claim 15
Dependent Claim
83 words
A capacitor structure element, comprising: a substrate; a crystalline thin film formed on a substrate at a first substrate temperature at which crystal grows; a ferroelectric thin film formed on said crystalline thin film at a second substrate temperature, which is lower than the first substrate temperature; a lower electrode made of a conductive material, which is formed between said substrate and said crystalline thin film; and a upper electrode made of a conductive material, which is formed on said ferroelectric thin film.
Claim 16
Dependent Claim
54 words
A ferroelectric thin film coated substrate, comprising: a substrate; a crystalline thin film formed on said substrate; and a ferroelectric thin film formed on said crystalline thin film, wherein a particle diameter of crystal grains composing said crystalline thin film is smaller than a particle diameter of crystal grains composing said ferroelectric thin film.
Claim 17
Dependent Claim
21 words
A ferroelectric thin film coated substrate wherein a crystalline thin film is provided between the substrate and the ferroelectric thin film.
References Cited (Backward Citations)
No citation records indexed.
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