US5889299A
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Thin film capacitor
Assignee: Toshiba Corp
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Filing: 1997-02-21
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Granted: 1999-03-30
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Expires: 2017-02-21
Abstract
Abstract A thin film capacitor including a first electrode having on its surface a (100) face of cubic system or a (001) face of tetragonal system, a dielectric thin film epitaxially grown on the first electrode and exhibiting a crystal structure which inherently belongs to a perovskite structure of cubic system, and a second electrode formed on the dielectric thin film. Further, the dielectric thin film meets the following relationship V/V0>/=1.01 where a unit lattice volume of true perovskite crystal structure belonging to the cubic system (lattice constant a0) is represented by V0=a03, and a unit lattice volume (lattice constant a=b NOTEQUAL c) which is strained toward a tetragonal system after the epitaxial growth is represented by V=a2c, and also meets the following relationship c/a>/=1.01 where c/a represents a ratio between a lattice constant "c" in the direction thicknesswise of the film and a lattice constant "a" in the direction parallel with a plane of the film.
Inventors
- 👤 Kazuhide Abe
- 👤 Shuichi Komatsu
- 👤 Mitsuaki Izuha
- 👤 Noburu Fukushima
- 👤 Kenya Sano
- 👤 Takashi Kawakubo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 05:53
CPC Classifications
H; H10; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/682; H10B; H10B12/00; H10B12/30
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
174 words
A thin film capacitor comprising: a first electrode having on a surface one of a (100) face of a cubic system or a (001) face of a tetragonal system; a dielectric thin film epitaxially grown on said first electrode and exhibiting a crystal structure which inherently belongs to a perovskite structure of a cubic system; and a second electrode formed on said dielectric thin film; wherein said dielectric thin film meets the following relationship: V/V.sub.0 ≧1.01 where a unit lattice volume of an inherent perovskite crystal structure belonging to a cubic system (lattice constant: a 0 ) is represented by V 0 =a 0 3 , and a unit lattice volume (lattice constant a=b≠c) which is strained toward a tetragonal system after the epitaxial growth is represented by V=a 2 c; and also meets the following relationship: c/a≧1.01 where c/a represents a ratio between a lattice constant "c" in a thickness direction of said dielectric thin film and a lattice constant "a" in a direction parallel with a plane of said dielectric thin film.
Claim 2
Dependent Claim
174 words
A thin film capacitor comprising: a first electrode having on a surface one of a (100) face of a cubic system or a (001) face of a tetragonal system; a dielectric thin film epitaxially grown on said first electrode and exhibiting a crystal structure which inherently belongs to a perovskite structure of a cubic system; and a second electrode formed on said dielectric thin film; wherein said dielectric thin film meets the following relationship: V/V.sub.0 ≧1.01 where a unit lattice volume of an inherent perovskite crystal structure belonging to a cubic system (lattice constant: a 0 ) is represented by V 0 =a 0 3 , and a unit lattice volume (lattice constant a=b≠c) which is strained toward a tetragonal system after the epitaxial growth is represented by V=a 2 c; and also meets the following relationship: c/a≧1.01 where c/a represents a ratio between a lattice constant "c" in a thickness direction of said dielectric thin film and a lattice constant "a" in a direction parallel with a plane of said dielectric thin film.
Claim 3
Dependent Claim
19 words
The thin film capacitor according to claim 1, wherein said dielectric thin film meets the following relationship: 1.05≧V/V.sub.0 ≧1.01
Claim 4
Dependent Claim
42 words
The thin film capacitor according to claim 1, wherein said dielectric thin film meets the following relationship: 1.03≧c/a≧1.01; when said dielectric thin film is formed of a paraelectric material; and 1.08≧c/a≧1.01; when said dielectric thin film is formed of a ferroelectric material.
Claim 5
Dependent Claim
108 words
The thin film capacitor according to claim 1, wherein said dielectric thin film is formed of a compound represented by the following formula: ABO.sub.3 wherein A represents at least one element selected from the group consisting of Ba, Sr and Ca; and B represents at least one member selected from the group consisting of Ti, Zr, Hf, Sn, Mg 1/3 Nb 2/3 , Mg 1/3 Ta 2/3 , Zn 1/3 Nb 2/3 , Zn 1/3 Ta 2/3 , Ni 1/3 Nb 2/3 , Ni 1/3 Ta 2/3 , Co 1/3 Nb 2/3 , Co 1/3 Ta 2/3 , Sc 1/3 Nb 2/3 and Sc 1/3 Ta 2/3 .
Claim 6
Dependent Claim
27 words
The thin film capacitor according to claim 4, wherein said dielectric thin film is formed of a compound represented by (Ba x Sr 1-x )TiO 3 (0<x<0.7).
Claim 7
Dependent Claim
36 words
The thin film capacitor according to claim 4, wherein said dielectric thin film is formed of a compound of perovskite crystal structure, which is represented by (Ba x Sr 1-x-y Ca y )TiO 3 (0<x<0.7; 0.01<y<0.12).
Claim 8
Dependent Claim
69 words
The thin film capacitor according to claim 1, wherein said first electrode is formed of a conductive compound of perovskite crystal structure, which is represented by the following formula: ABO.sub.3 wherein A represents at least one element selected from the group consisting of Ba, Sr, Ca and La; and B represents at least one element selected from the group consisting of Ru, Ir, Mo, W, Co, Ni and Cr.
Claim 9
Dependent Claim
29 words
The thin film capacitor according to claim 7, wherein said first electrode is formed of a conductive compound of perovskite crystal structure, which is represented by SrRuO 3 (0.9<Sr/Ru<1.1).
Claim 10
Dependent Claim
48 words
The thin film capacitor according to claim 1, wherein said dielectric thin film is formed of a compound represented by (Ba x Sr 1-x )TiO 3 (0<x<0.7), and said first electrode is formed of a conductive compound of perovskite crystal structure, which is represented by SrRuO 3 (0.9<Sr/Ru<1.1).
Claim 11
Dependent Claim
69 words
The thin film capacitor according to claim 1, wherein said second electrode is formed of a conductive compound of perovskite crystal structure, which is represented by the following formula: ABO.sub.3 wherein A represents at least one element selected from the group consisting of Ba, Sr, Ca and La; and B represents at least one element selected from the group consisting of Ru, Ir, Mo, W, Co, Ni and Cr.
Claim 12
Dependent Claim
29 words
The thin film capacitor according to claim 10, wherein said second electrode is formed of a conductive compound of perovskite crystal structure, which is represented by SrRuO 3 (0.9<Sr/Ru<1.1).
Claim 13
Dependent Claim
17 words
The thin film capacitor according to claim 1, wherein said capacitor is a capacitor for a DRAM.
Claim 14
Dependent Claim
171 words
A thin film capacitor comprising: a first electrode having on a surface one of a (100) face of a cubic system or a (001) face of a tetragonal system; a dielectric thin film epitaxially grown on said first electrode and exhibiting a crystal structure which inherently belongs to a perovskite structure of a cubic system; and a second electrode formed on said dielectric thin film; wherein said dielectric thin film meets the following relationship: a.sub.0 /a.sub.s ≦1.002 where a s represents a lattice constant in a direction parallel with a surface of said first electrode, and a 0 represents a lattice constant inherent to a dielectric material constituting said dielectric thin film, which can be expressed by a length of an a-axis of a perovskite crystal structure belonging to a cubic system; and also meets the following relationship: c/a≧1.01 where c/a represents a ratio between a lattice constant "c" in a thickness direction of said film and a lattice constant "a" in a direction parallel with a plane of said film.
Claim 15
Dependent Claim
171 words
A thin film capacitor comprising: a first electrode having on a surface one of a (100) face of a cubic system or a (001) face of a tetragonal system; a dielectric thin film epitaxially grown on said first electrode and exhibiting a crystal structure which inherently belongs to a perovskite structure of a cubic system; and a second electrode formed on said dielectric thin film; wherein said dielectric thin film meets the following relationship: a.sub.0 /a.sub.s ≦1.002 where a s represents a lattice constant in a direction parallel with a surface of said first electrode, and a 0 represents a lattice constant inherent to a dielectric material constituting said dielectric thin film, which can be expressed by a length of an a-axis of a perovskite crystal structure belonging to a cubic system; and also meets the following relationship: c/a≧1.01 where c/a represents a ratio between a lattice constant "c" in a thickness direction of said film and a lattice constant "a" in a direction parallel with a plane of said film.
Claim 16
Dependent Claim
18 words
The thin film capacitor according to claim 13, wherein said dielectric thin film meets the following relationship: 1.1≧c/a≧1.01
Claim 17
Dependent Claim
108 words
The thin film capacitor according to claim 13, wherein said dielectric thin film is formed of a compound represented by the following formula: ABO.sub.3 wherein A represents at least one element selected from the group consisting of Ba, Sr and Ca; and B represents at least one member selected from the group consisting of Ti, Zr, Hf, Sn, Mg 1/3 Nb 2/3 , Mg 1/3 Ta 2/3 , Zn 1/3 Nb 2/3 , Zn 1/3 Ta 2/3 , Ni 1/3 Nb 2/3 , Ni 1/3 Ta 2/3 , Co 1/3 Nb 2/3 , Co 1/3 Ta 2/3 , Sc 1/3 Nb 2/3 and Sc 1/3 Ta 2/3 .
Claim 18
Dependent Claim
27 words
The thin film capacitor according to claim 15, wherein said dielectric thin film is formed of a compound represented by (Ba x Sr 1-x )TiO 3 (0≦x<0.7).
Claim 19
Dependent Claim
36 words
The thin film capacitor according to claim 15, wherein said dielectric thin film is formed of a compound of perovskite crystal structure, which is represented by (Ba x Sr 1-x-y Ca y )TiO 3 (0<x<0.7; 0.01<y<0.12).
Claim 20
Dependent Claim
69 words
The thin film capacitor according to claim 13, wherein said first electrode is formed of a conductive compound of perovskite crystal structure, which is represented by the following formula: ABO.sub.3 wherein A represents at least one element selected from the group consisting of Ba, Sr, Ca and La; and B represents at least one element selected from the group consisting of Ru, Ir, Mo, W, Co, Ni and Cr.
Claim 21
Dependent Claim
29 words
The thin film capacitor according to claim 18, wherein said first electrode is formed of a conductive compound of perovskite crystal structure, which is represented by SrRuO 3 (0.9<Sr/Ru<1.1).
Claim 22
Dependent Claim
48 words
The thin film capacitor according to claim 13, wherein said dielectric thin film is formed of a compound represented by (Ba x Sr 1-x )TiO 3 (0<x<0.7), and said first electrode is formed of a conductive compound of perovskite crystal structure, which is represented by SrRuO 3 (0.9<Sr/Ru<1.1).
Claim 23
Dependent Claim
69 words
The thin film capacitor according to claim 13, wherein said second electrode is formed of a conductive compound of perovskite crystal structure, which is represented by the following formula: ABO.sub.3 wherein A represents at least one element selected from the group consisting of Ba, Sr, Ca and La; and B represents at least one element selected from the group consisting of Ru, Ir, Mo, W, Co, Ni and Cr.
Claim 24
Dependent Claim
29 words
The thin film capacitor according to claim 21, wherein said second electrode is formed of a conductive compound of perovskite crystal structure, which is represented by SrRuO 3 (0.9<Sr/Ru<1.1).
Claim 25
Dependent Claim
17 words
The thin film capacitor according to claim 13, wherein said capacitor is a capacitor for a DRAM.
References Cited (Backward Citations)
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