Semiconductor device having thin film transistors on a metal substrate

• US 7,977,680 B2
• Filed: 07/10/2008
• Issued: 07/12/2011
• Est. Priority Date: 09/06/2000
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Isobe, Atsuo, Takayama, Toru, Arao, Tatsuya
• Primary Examiner(s): Hu; Shouxiang
• Application Number:
  US12/170,588
• Publication Number:
  US 20080272376A1
• Time in Patent Office: 1,097 Days
• Field of Search: 257/59, 257/40, 257/57, 257/61, 257/66, 257/72, 257/532, 257/534, 257/E27.111, 349/39, 349 42- 43, 349/47, 349/139
• US Class Current: 257/72
• CPC Class Codes: G02F 1/133305 Flexible substrates, e.g. plastics, organic film
• CPC Class Codes: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• 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: G02F 1/136295 Materials; Compositions; Manufacture processes
• 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 29/66742 Thin film unipolar transistors
• CPC Class Codes: H01L 29/78603 characterised by the insulating substrate or support H01L29/78657 takes precedence
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays

Abstract

In a semiconductor device having a substrate which has a metal surface, an insulating film which is formed on the substrate having the metal surface, and a pixel unit which is formed on the insulating film; the pixel unit includes a TFT, and wiring lines connected with the TFT, and a storage capacitor is constituted by the substrate (11) having the metal surface, the insulating film (12), and the wiring line (21). As the insulating film is thinner, and as the area of a region where the insulating film and the wiring line lie in contact is larger, the storage capacitor is endowed with a larger capacity.

Claims

1. A light emitting device comprising:

a metal substrate;

a first insulating film formed over the metal substrate;

a first thin film transistor and a second thin film transistor formed over the first insulating film, each of the first thin film transistor and the second thin film transistor comprising a semiconductor layer and a gate electrode with a gate insulating film interposed therebetween;

a second insulating film having a first contact hole and a second contact hole formed over the first thin film transistor and the second thin film transistor;

a first wiring formed over the first insulating film and second insulating film, the first wiring being electrically connected to the first thin film transistor through the first contact hole and being in contact with a portion of the first insulating film;

a second wiring formed over the second insulating film and electrically connected to the second thin film transistor through the second contact hole;

a third insulating film formed over the second insulating film, the first wiring, and the second wiring; and

an EL element formed over the third insulating film,

wherein a portion of the second insulating film is provided between the semiconductor layer of the first thin film transistor and a portion of the first wiring.

2. The light emitting device according to claim 1, wherein the metal substrate is a stainless steel substrate.

3. The light emitting device according to claim 1, wherein a storage capacitor is formed by the metal substrate, the portion of the first insulating film, and the first wiring.

4. The light emitting device according to claim 1, wherein the first insulating film is a silicon oxide film, a silicon nitride film, or a silicon oxynitride film.

5. The light emitting device according to claim 1, wherein the first wiring is electrically connected to the gate electrode of the second thin film transistor.

6. A light emitting device comprising:

a metal substrate;

a first insulating film formed over the metal substrate;

a first thin film transistor and a second thin film transistor formed over the first insulating film, each of the first thin film transistor and the second thin film transistor comprising a semiconductor layer and a gate electrode with a gate insulating film interposed therebetween;

a second insulating film having a first contact hole and a second contact hole formed over the first thin film transistor and the second thin film transistor;

a first wiring formed over the first insulating film and second insulating film, the first wiring being electrically connected to the first thin film transistor through the first contact hole and being in contact with a portion of the first insulating film;

a second wiring formed over the second insulating film and electrically connected to the second thin film transistor through the second contact hole;

a third insulating film having a third contact hole formed over the second insulating film, the first wiring, and the second wiring;

a first electrode formed over the third insulating film and electrically connected to the second wiring through the third contact hole;

an EL layer formed over the first electrode; and

a second electrode formed over the EL layer,

wherein a portion of the second insulating film is provided between the semiconductor layer of the first thin film transistor and a portion of the first wiring.

7. The light emitting device according to claim 6, wherein the metal substrate is a stainless steel substrate.

8. The light emitting device according to claim 6, wherein a storage capacitor is formed by the metal substrate, the portion of the first insulating film, and the first wiring.

9. The light emitting device according to claim 6, wherein the first insulating film is a silicon oxide film, a silicon nitride film, or a silicon oxynitride film.

10. The light emitting device according to claim 6, wherein the first wiring is electrically connected to the gate electrode of the second thin film transistor.

11. An electronic book comprising:

a main body;

a operation switch; and

a display portion, the display portion comprising;

a metal substrate;

a first insulating film formed over the metal substrate;

a first thin film transistor and a second thin film transistor formed over the first insulating film, each of the first thin film transistor and the second thin film transistor comprising a semiconductor layer and a gate electrode with a gate insulating film interposed therebetween;

a second insulating film having a first contact hole and a second contact hole formed over the first thin film transistor and the second thin film transistor;

a first wiring formed over the first insulating film and second insulating film, the first wiring being electrically connected to the first thin film transistor through the first contact hole and being in contact with a portion of the first insulating film;

a second wiring formed over the second insulating film and electrically connected to the second thin film transistor through the second contact hole;

a third insulating film formed over the second insulating film, the first wiring, and the second wiring; and

an EL element formed over the third insulating film,

wherein a portion of the second insulating film is provided between the semiconductor layer of the first thin film transistor and a portion of the first wiring.

12. The electronic book according to claim 11, wherein the metal substrate is a stainless steel substrate.

13. The electronic book according to claim 11, wherein a storage capacitor is formed by the metal substrate, the portion of the first insulating film, and the first wiring.

14. The electronic book according to claim 11, wherein the first insulating film is a silicon oxide film, a silicon nitride film, or a silicon oxynitride film.

15. The electronic book according to claim 11, wherein the first wiring is electrically connected to the gate electrode of the second thin film transistor.

16. An electronic book comprising:

a main body;

a operation switch; and

a display portion, the display portion comprising;

a metal substrate;

a first insulating film formed over the metal substrate;

a first thin film transistor and a second thin film transistor formed over the first insulating film, each of the first thin film transistor and the second thin film transistor comprising a semiconductor layer and a gate electrode with a gate insulating film interposed therebetween;

a second insulating film having a first contact hole and a second contact hole formed over the first thin film transistor and the second thin film transistor;

a first wiring formed over the first insulating film and second insulating film, the first wiring being electrically connected to the first thin film transistor through the first contact hole and being in contact with a portion of the first insulating film;

a second wiring formed over the second insulating film and electrically connected to the second thin film transistor through the second contact hole;

a third insulating film having a third contact hole formed over the second insulating film, the first wiring, and the second wiring;

a first electrode formed over the third insulating film and electrically connected to the second wiring through the third contact hole;

an EL layer formed over the first electrode; and

a second electrode formed over the EL layer,

wherein a portion of the second insulating film is provided between the semiconductor layer of the first thin film transistor and a portion of the first wiring.

17. The electronic book according to claim 16, wherein the metal substrate is a stainless steel substrate.

18. The electronic book according to claim 16, wherein a storage capacitor is formed by the metal substrate, the portion of the first insulating film, and the first wiring.

19. The electronic book according to claim 16, wherein the first insulating film is a silicon oxide film, a silicon nitride film, or a silicon oxynitride film.

20. The electronic book according to claim 16, wherein the first wiring is electrically connected to the gate electrode of the second thin film transistor.