Active matrix liquid crystal display device with overlapping conductive film and pixel electrode

• US 8,531,619 B2
• Filed: 08/16/2012
• Issued: 09/10/2013
• Est. Priority Date: 03/28/1997
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ohtani, Hisashi, Ogata, Yasushi
• Primary Examiner(s): Qi, Mike
• Application Number:
  US13/587,109
• Publication Number:
  US 20130001581A1
• Time in Patent Office: 390 Days
• Field of Search: 349/44, 349/38, 349/39, 349/138, 349/139, 257/346, 257/72
• US Class Current: 349/44
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1255 integrated with passive devices, e.g. auxiliary capacitors
• CPC Class Codes: H01L 29/78645 with multiple gate

Abstract

A first insulating thin film having a large dielectric constant such as a silicon nitride film is formed so as to cover a source line and a metal wiring that is in the same layer as the source line. A second insulating film that is high in flatness is formed on the first insulating film. An opening is formed in the second insulating film by etching the second insulating film, to selectively expose the first insulating film. A conductive film to serve as a light-interruptive film is formed on the second insulating film and in the opening, whereby an auxiliary capacitor of the pixel is formed between the conductive film and the metal wiring with the first insulating film serving as a dielectric.

Claims

1. A display device comprising:

a thin film transistor over a substrate;

a first insulating film over the thin film transistor, the first insulating film having an opening;

a conductive film over the first insulating film, the conductive film being in contact with a side surface of the first insulating film in the opening;

a second insulating film over the conductive film; and

a pixel electrode over the second insulating film, the pixel electrode being connected to one of a source and a drain of the thin film transistor,

wherein the pixel electrode and the conductive film overlap with each other, and

wherein the conductive film is kept at a constant potential.

2. The display device according to claim 1, further comprising a third insulating film over the thin film transistor and under the first insulating film,

wherein the conductive film is in contact with the third insulating film in the opening.

3. The display device according to claim 2, further comprising a wiring connected to the one of the source and the drain of the thin film transistor,

wherein a capacitor is formed by the conductive film, the third insulating film and the wiring in the opening.

4. The display device according to claim 1, wherein the second insulating film comprises polyimide.

5. The display device according to claim 1, wherein the thin film transistor is a top-gate thin film transistor.

6. The display device according to claim 1, wherein the thin film transistor is a bottom-gate thin film transistor.

7. The display device according to claim 1, wherein the conductive film is a light-interruptive film.

8. The display device according to claim 1, wherein the opening of the first insulating film is provided within a pixel.

9. A display device comprising:

a thin film transistor over a substrate;

a first insulating film over the thin film transistor, the first insulating film having an opening;

a conductive film over the first insulating film, the conductive film being in contact with a side surface of the first insulating film in the opening;

a second insulating film over the conductive film; and

a pixel electrode over the second insulating film, the pixel electrode being connected to one of a source and a drain of the thin film transistor,

wherein the conductive film overlaps a channel formation region of the thin film transistor,

wherein the pixel electrode and the conductive film overlap with each other, and

wherein the conductive film is kept at a constant potential.

10. The display device according to claim 9, further comprising a third insulating film over the thin film transistor and under the first insulating film,

wherein the conductive film is in contact with the third insulating film in the opening.

11. The display device according to claim 10, further comprising a wiring connected to the one of the source and the drain of the thin film transistor,

wherein a capacitor is formed by the conductive film, the third insulating film and the wiring in the opening.

12. The display device according to claim 9, wherein the second insulating film comprises polyimide.

13. The display device according to claim 9, wherein the thin film transistor is a top-gate thin film transistor.

14. The display device according to claim 9, wherein the thin film transistor is a bottom-gate thin film transistor.

15. The display device according to claim 9, wherein the conductive film is a light-interruptive film.

16. The display device according to claim 9, wherein the conductive film overlaps entirety of the channel formation region of the thin film transistor.

17. The display device according to claim 9, wherein the opening of the first insulating film is provided within a pixel.