Liquid crystal electrooptical device

• US 5,745,195 A
• Filed: 05/07/1996
• Issued: 04/28/1998
• Est. Priority Date: 05/07/1995
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Zhang, Hongyong
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): NGUYEN, TIEP HUU
• Application Number:
  US08/646,511
• Time in Patent Office: 721 Days
• Field of Search: 349/42, 349/43, 349/39, 349/51, 349/38
• US Class Current: 349/39
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode

Abstract

An active matrix liquid crystal display having auxiliary capacitors. Two transparent conductive layers of ITO are formed on opposite sides of an insulating film. The first conductive layer forms pixel electrodes. The second transparent conductive film overlaps at least parts of the pixel electrodes via the insulating film to form the auxiliary capacitors without deteriorating the aperture ratio of the pixels.

Claims

1. An electrooptical device comprising:

a transistor;

a first transparent conductive film forming a pixel electrode for forming a pixel;

an insulating film; and

a second transparent conductive film disposed on the opposite side of said insulating film from said first transparent conductive film and overlapping at least a part of said pixel electrode with said insulating film to provide an auxiliary capacitor comprising said second transparent conductive film, said insulating film and said pixel electrode.

wherein said transistor and said auxiliary capacitor are provided on the same substrate, and a gate and a channel region of said transistor are on different planes from said auxiliary capacitor.

2. The device of claim 1 wherein said electrooptical device is an active matrix liquid crystal display.

3. The device of claim 1 wherein said transparent conductive films are made of ITO.

4. The device of claim 1 wherein said transparent conductive films are made of SnO₂.

5. The device of claim 1 further comprising a pixel capacitor provided in parallel with corresponding one of said auxiliary capacitors and comprising an electro-optical modulating layer provided between the corresponding one of said pixel electrodes and a counter electrode provided on an opposite side of said electro-optical modulating layer from said pixel electrodes.

6. The device of claim 5 wherein said electro-optical modulating layer comprises a liquid crystal.

7. The device of claim 1 further comprising a thin film transistor comprising a source and drain and a channel provided between said source and said drain wherein said drain is connected with corresponding one of said pixel electrodes.

8. The device of claim 7 wherein said thin film transistor further comprising offset gate regions each provided between said channel and corresponding one of said source and said drain.

9. The device of claim 7 wherein said thin film transistor and said pixel electrodes are provided in an active matrix.

10. The device of claim 7 wherein said source and said drain and said channel are provided in a crystalline silicon film.

11. A device as in claim 1 wherein said pixel electrode is operatively associated with said transistor.

12. An electrooptical device comprising:

a transistor;

an interlayer insulating film provided over a gate and a channel region of said transistor;

a first transparent conductive film forming a pixel electrode for forming a pixel;

a dielectric film; and

a second transparent conductive film disposed on the opposite side of said dielectric film from said first transparent conductive film and overlapping at least a part of said pixel electrode with said dielectric film being between said first and second conductive film to provide an auxiliary capacitor comprising said second transparent conductive film, said dielectric film and said pixel electrode,

wherein said transistor and said auxiliary capacitor are provided on the same substrate, and said auxiliary capacitor is provided on said interlayer insulating film.

13. A device as in claim 12 wherein said pixel electrode is operatively associated with said transistor.

14. An electrooptical device comprising:

a plurality of horizontally-extending material layers, including;

a first plurality of layers forming a transistor;

an interlayer insulating film provided vertically above a gate and a channel region of said transistor;

a first transparent conductive film layer, provided vertically above said transistor, and forming a pixel electrode for forming a pixel;

a capacitive film layer, vertically above said transistor and adjacent said first transparent layer; and

a second transparent conductive film disposed vertically above said transistor and on the opposite side of said capacitive film layer from said first transparent conductive film and overlapping at least a part of said pixel electrode with said capacitive film layer being between said first and second conductive films to provide an auxiliary capacitor comprising said second transparent conductive film, said capacitive layer and said pixel electrode,

wherein said transistor and said auxiliary capacitor are provided coupled to the same substrate, and said auxiliary capacitor is provided on a vertically different plane from said transistor.