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US5317432A Expired / Lapsed US ⏱️ 0.0 years remaining

Liquid crystal display device with a capacitor and a thin film transistor in a trench for each pixel

Assignee: Sony Corp
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Filing: 1992-09-01
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Granted: 1994-05-31
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Expires: 2012-09-01
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Abstract

Abstract A liquid crystal display device includes a pair of opposed insulating substrate and a liquid crystal layer sandwiched therebetween. One of the insulating substrates is formed with a first trench for forming a thin film transistor therein and a second trench for forming a capacitor element therein. The thin film transistor is constituted of a semiconductor layer formed along an inner surface of the first trench, a gate insulating layer formed on the semiconductor layer, and a gate electrode formed on the gate insulating layer. The capacitor element is constituted of a first electrode formed along an inner surface of the second trench, a dielectric layer formed on the first electrode, and a second electrode formed on the dielectric layer. The first electrode is formed integrally with the semiconductor layer, thereby increasing an aperture ratio. The first trench has a tapering side surface, thereby ensuring uniform ion implantation for the semiconductor layer. In the case that the substrate has a laminated structure of an insulating substrate and an insulating layer, an etching rate of the substrate as a whole can be improved.

Inventors

  • 👤 Masumitsu Ino

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-31 17:29
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/136; G02F1/1362; G02F1/136213; G02F1/1368; H; H10; H10D; H10D30/00; H10D30/60; H10D30/67; H10D86/00; H10D86/40; G02F2201/00; G02F2201/12; G02F2201/123; G02F2201/40

Claims Analysis

Total Claims: 17
Claim 1
Independent Claim 98 words
A liquid crystal display device comprising: a substrate having a first trench; a plurality of display elements arranged in a matrix form, each of said display elements comprising a picture element electrode, a thin film transistor formed in said first trench and associated with said picture element electrode, and a capacitor element associated with said picture element electrode; and wherein said first trench has a structure satisfying the relation of: 0<tanθ≦a/2b wherein a represents a width of said first trench; b represents a depth of said first trench; and θ represents a tapered angle of said first trench.
Claim 2
Dependent Claim 98 words
A liquid crystal display device comprising: a substrate having a first trench; a plurality of display elements arranged in a matrix form, each of said display elements comprising a picture element electrode, a thin film transistor formed in said first trench and associated with said picture element electrode, and a capacitor element associated with said picture element electrode; and wherein said first trench has a structure satisfying the relation of: 0<tanθ≦a/2b wherein a represents a width of said first trench; b represents a depth of said first trench; and θ represents a tapered angle of said first trench.
Claim 3
Dependent Claim 17 words
A liquid crystal display device according to claim 1, wherein said first trench has tapered side walls.
Claim 4
Dependent Claim 54 words
A liquid crystal display device according to claim 2, wherein said thin film transistor comprises a polysilicon semiconductor layer formed along an inner surface of said first trench, a gate insulating layer formed on said semiconductor layer, and a gate electrode formed on said gate insulating layer so as to fill said first trench.
Claim 5
Dependent Claim 32 words
A liquid crystal display device according to claim 3, wherein said substrate has a second trench formed simultaneously with said first trench, and said capacitor element is formed in said second trench.
Claim 6
Dependent Claim 54 words
A liquid crystal display device according to claim 4, wherein said capacitor element comprises a first electrode formed along an inner surface of said second trench, a dielectric layer formed of the same material as that of said gate insulating layer, and a second electrode opposed to said first electrode through said dielectric layer.
Claim 7
Dependent Claim 25 words
A liquid crystal display device according to claim 5, wherein said first electrode, said second electrode, and said gate electrode are formed of doped polysilicon.
Claim 8
Dependent Claim 18 words
A liquid crystal display device according to claim 5, wherein said first electrode is formed of doped polysilicon.
Claim 9
Dependent Claim 18 words
A liquid crystal display device according to claim 3, wherein said semiconductor layer is formed of doped polysilicon.
Claim 10
Dependent Claim 35 words
A liquid crystal display device according to claim 8, wherein said polysilicon is doped with a cation selected from the group consisting of Si + , B + , As + and P + .
Claim 11
Dependent Claim 26 words
A liquid crystal display device according to claim 1, wherein said substrate has a second trench, and said capacitor element is formed in said second trench.
Claim 12
Dependent Claim 17 words
A liquid crystal display device according to claim 10, wherein said second trench has tapered side walls.
Claim 13
Dependent Claim 25 words
A liquid crystal display device according to claim 1, wherein said substrate comprises an insulating substrate and an insulating layer formed on said insulating substrate.
Claim 14
Dependent Claim 17 words
A liquid crystal display device according to claim 12, wherein said first trench has tapered side walls.
Claim 15
Dependent Claim 26 words
A liquid crystal display device according to claim 13, wherein said substrate has a second trench, and said capacitor element is formed in said second trench.
Claim 16
Dependent Claim 59 words
A liquid crystal display device according to claim 14, wherein said capacitor element comprises a first electrode formed along an inner surface of said second trench, a dielectric layer formed of the same material as that of a gate insulating layer of said thin film transistor, and a second electrode opposed to said first electrode through said dielectric layer.
Claim 17
Dependent Claim 17 words
A liquid crystal display device according to claim 14, wherein said second trench has tapered side walls.

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1997-05-30 1997-11-29 1998-05-31 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2001-05-30 2001-11-29 2002-05-31 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2005-05-30 2005-11-29 2006-05-31 $7700.00 Window Closed / Lapsed

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