US5796648A
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Nonvolatile semiconductor memory device and method for manufacturing same
Assignee: Toshiba Corp
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Filing: 1996-12-10
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Granted: 1998-08-18
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Expires: 2016-12-10
Abstract
Abstract A nonvolatile semiconductor memory device has a ferroelectric cell and a paraelectric cell. The ferroelectric cell includes a first thin-film capacitor which has a first lower electrode formed on a substrate, a first dielectric film grown on the first lower electrode and a first upper electrode formed on the first dielectric film, and a first switching transistor connected to the first thin-film capacitor. The paraelectric cell includes a second thin-film capacitor which has a second lower electrode, a second dielectric film grown on the second lower electrode and a second upper electrode formed on the second dielectric film, and a second switching transistor connected to the second thin-film capacitor. The first lower electrode is provided such that the first dielectric film has ferroelectricities, while the second lower electrode is provided such that the second dielectric film has paraelectricities.
Inventors
- 👤 Takashi Kawakubo
- 👤 Kazuhide Abe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:48
CPC Classifications
H; H10; H10B; H10B53/00; G; G11; G11C; G11C11/00; G11C11/21; G11C11/22; H10B53/30; H10D; H10D1/00; H10D1/60; H10D1/68; H10D1/692
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
168 words
A nonvolatile semiconductor memory device which comprises: a ferroelectric cell and a paraelectric cell; wherein said ferroelectric cell includes a first thin-film capacitor which comprises a first lower electrode formed on a substrate, a first dielectric film grown on the first lower electrode, and a first upper electrode formed on the first dielectric film, and a first switching transistor connected to the first thin-film capacitor, and wherein said paraelectric cell includes a second thin-film capacitor which comprises a second lower electrode, a second dielectric film grown on the second lower electrode, and a second upper electrode formed on the second dielectric film, and a second switching transistor connected to the second thin-film capacitor; and wherein the first and second dielectric films are formed of the same material and have a single crystal structure, each of the first and second lower electrodes have a single crystal structure, and dielectric characteristics of the first and second dielectric films are controlled by changing lattice constants of the first and second-lower electrodes.
Claim 2
Dependent Claim
168 words
A nonvolatile semiconductor memory device which comprises: a ferroelectric cell and a paraelectric cell; wherein said ferroelectric cell includes a first thin-film capacitor which comprises a first lower electrode formed on a substrate, a first dielectric film grown on the first lower electrode, and a first upper electrode formed on the first dielectric film, and a first switching transistor connected to the first thin-film capacitor, and wherein said paraelectric cell includes a second thin-film capacitor which comprises a second lower electrode, a second dielectric film grown on the second lower electrode, and a second upper electrode formed on the second dielectric film, and a second switching transistor connected to the second thin-film capacitor; and wherein the first and second dielectric films are formed of the same material and have a single crystal structure, each of the first and second lower electrodes have a single crystal structure, and dielectric characteristics of the first and second dielectric films are controlled by changing lattice constants of the first and second-lower electrodes.
Claim 3
Dependent Claim
50 words
A nonvolatile semiconductor memory device according to claim 1, wherein said first and second dielectric films are epitaxially grown on the first and second lower electrodes, respectively, and said first lower electrode has a lattice constant which is smaller than that of the second lower electrode by 0.2% or more.
Claim 4
Dependent Claim
36 words
A nonvolatile semiconductor memory device according to claim 1, wherein said first and second dielectric films are formed of bariurn/strontium titanate, and said first dielectric film is made to have ferroelectricities by residual strain produced therein.
Claim 5
Dependent Claim
24 words
A nonvolatile semiconductor memory device according to claim 1, wherein at least one of said first and second lower electrodes is formed of Pt.
Claim 6
Dependent Claim
52 words
A nonvolatile semiconductor memory device according to claim 1, wherein at least one of said first and second lower electrodes is formed of a mixed crystal made from a plurality of conductive compounds, and dielectric characteristics of the first and second dielectric films are controlled by changing composition of the mixed crystal.
Claim 7
Dependent Claim
31 words
A nonvolatile semiconductor memory device according to claim 5, wherein said plurality of conductive compounds are selected from the group consisting of BaRuO 3 , SrRuO 3 and CaRuO 3 .
Claim 8
Independent Claim
147 words
A method for manufacturing a nonvolatile semiconductor memory device, comprising the steps of: forming a first lower electrode and a second lower electrode on a substrate, wherein lattice constants of the first lower electrode are different from those of the second lower electrode, and each of the first and second lower electrodes have a single crystal structure; forming a first dielectric film having ferroelectricities and a second dielectric film have paraelectricities simultaneously on the first and second lower electrodes, respectively, under epitaxial growth condition, the first and second dielectric films have a single crystal structure and are formed of the same material which has a lattice constant different from that of the first lower electrode; and providing a first upper electrode on the first dielectric film, thereby forming a ferroelectric cell, and providing a second upper electrode on the second dielectric film, thereby forming a paraelectric cell.
Claim 9
Independent Claim
147 words
A method for manufacturing a nonvolatile semiconductor memory device, comprising the steps of: forming a first lower electrode and a second lower electrode on a substrate, wherein lattice constants of the first lower electrode are different from those of the second lower electrode, and each of the first and second lower electrodes have a single crystal structure; forming a first dielectric film having ferroelectricities and a second dielectric film have paraelectricities simultaneously on the first and second lower electrodes, respectively, under epitaxial growth condition, the first and second dielectric films have a single crystal structure and are formed of the same material which has a lattice constant different from that of the first lower electrode; and providing a first upper electrode on the first dielectric film, thereby forming a ferroelectric cell, and providing a second upper electrode on the second dielectric film, thereby forming a paraelectric cell.
Claim 10
Dependent Claim
175 words
A nonvolatile semiconductor memory device which comprises: a ferroelectric cell and a paraelectric cell; wherein said ferroelectric cell includes a first thin-film capacitor which comprises a first lower electrode formed on a substrate, a first dielectric film grown on the first lower electrode, and a first upper electrode formed on the first dielectric film, and a first switching transistor connected to the first thin-film capacitor; and wherein said paraelectric cell includes a second thin-film capacitor which comprises a second lower electrode, a second dielectric film grown on the second lower electrode, and a second upper electrode formed on the second dielectric film, and a second switching transistor connected to the second thin-film capacitor; and wherein the first and second dielectric films are formed of the same material, the first dielectric film and the first lower electrode have a single crystal structure, the second dielectric film and the second electrode have a polycrystalline structure, and dielectric characteristics of the first and second dielectric films are controlled by crystallinities of the first and the second lower electrodes.
Claim 11
Dependent Claim
175 words
A nonvolatile semiconductor memory device which comprises: a ferroelectric cell and a paraelectric cell; wherein said ferroelectric cell includes a first thin-film capacitor which comprises a first lower electrode formed on a substrate, a first dielectric film grown on the first lower electrode, and a first upper electrode formed on the first dielectric film, and a first switching transistor connected to the first thin-film capacitor; and wherein said paraelectric cell includes a second thin-film capacitor which comprises a second lower electrode, a second dielectric film grown on the second lower electrode, and a second upper electrode formed on the second dielectric film, and a second switching transistor connected to the second thin-film capacitor; and wherein the first and second dielectric films are formed of the same material, the first dielectric film and the first lower electrode have a single crystal structure, the second dielectric film and the second electrode have a polycrystalline structure, and dielectric characteristics of the first and second dielectric films are controlled by crystallinities of the first and the second lower electrodes.
Claim 12
Dependent Claim
36 words
A nonvolatile semiconductor memory device according to claim 8, wherein said first and second dielectric films are formed of barium/strontium titanate, and said first dielectric film is made to have ferroelectricities by residual strain produced therein.
Claim 13
Dependent Claim
24 words
A nonvolatile semiconductor memory device according to claim 8, wherein at least one of said first and second lower electrodes is formed of Pt.
Claim 14
Dependent Claim
22 words
A nonvolatile semiconductor memory device according to claim 8, wherein said first and second lower electrodes are formed of the same material.
Claim 15
Dependent Claim
33 words
A nonvolatile semiconductor memory device according to claim 8, wherein at least one of said first and second lower electrodes is formed of a mixed crystal made from a plurality of conductive compounds.
Claim 16
Dependent Claim
31 words
A nonvolatile semiconductor memory device according to claim 12, wherein said plurality of conductive compounds are selected from the group consisting of BaRuO 3 , SrRuO 3 and CaRuO 3 .
Claim 17
Dependent Claim
47 words
A method according to claim 7, wherein said first and second dielectric films are epitaxially grown on the first and second lower electrodes, respectively, and said first lower electrode has a lattice constant which is smaller than that of the second lower electrode by 0.2% or more.
Claim 18
Dependent Claim
33 words
A method according to claim 7, wherein said first and second dielectric films are formed of barium/strontium titanate, and said first dielectric film is made to have ferroelectricities by residual strain produced therein.
Claim 19
Dependent Claim
19 words
A method according to claim 7, wherein one of said first and second lower electrodes is formed of Pt.
Claim 20
Dependent Claim
50 words
A method according to claim 7, wherein at least one of said first and second lower electrodes is formed of a mixed crystal made from a plurality of conductive compounds, and the dielectric characteristics of the first and second dielectric films are controlled by changing composition of the mixed crystal.
Claim 21
Dependent Claim
28 words
A method according to claim 7, wherein said plurality of conductive compounds are selected from the group consisting of BaRuO 3 , SrRuO 3 and CaRuO 3 .
Claim 22
Independent Claim
133 words
A method for manufacturing a nonvolatile semiconductor memory device, comprising the steps of: forming a first lower electrode and a second lower electrode, which has a roughened surface, on a substrate; forming a first dielectric film having ferroelectricities and a second dielectric film having paraelectricities simultaneously on the first and second lower electrodes, respectively, under epitaxial growth condition, the first and second dielectric films being formed of the same material which has a lattice constant different from that of the first lower electrode, said first dielectric film having a single crystal structure, and said second dielectric film having a polycrystalline structure; and providing a first upper electrode on the first dielectric film, thereby forming a ferroelectric cell, and providing a second upper electrode on the second dielectric film, thereby forming a paraelectric cell.
Claim 23
Independent Claim
133 words
A method for manufacturing a nonvolatile semiconductor memory device, comprising the steps of: forming a first lower electrode and a second lower electrode, which has a roughened surface, on a substrate; forming a first dielectric film having ferroelectricities and a second dielectric film having paraelectricities simultaneously on the first and second lower electrodes, respectively, under epitaxial growth condition, the first and second dielectric films being formed of the same material which has a lattice constant different from that of the first lower electrode, said first dielectric film having a single crystal structure, and said second dielectric film having a polycrystalline structure; and providing a first upper electrode on the first dielectric film, thereby forming a ferroelectric cell, and providing a second upper electrode on the second dielectric film, thereby forming a paraelectric cell.
Claim 24
Dependent Claim
19 words
A method according to claim 19, wherein said first and second lower electrodes are formed of the same material.
Claim 25
Dependent Claim
33 words
A method according to claim 19, wherein said first and second dielectric films are formed of barium/strontium titanate, and said first dielectric film is made to have ferroelectricities by residual strain produced therein.
Claim 26
Dependent Claim
30 words
A method according to claim 19, wherein at least one of said first and second lower electrodes is formed of a mixed crystal made from a plurality of conductive compounds.
Claim 27
Dependent Claim
28 words
A method according to claim 22, wherein said plurality of conductive compounds are selected from the group consisting of BaRuO 3 , SrRuO 3 and CaRuO 3 .
Claim 28
Dependent Claim
21 words
A method according to claim 19, wherein at least one of said first and second lower electrodes is formed of Pt.
References Cited (Backward Citations)
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