Semiconductor electro-optical device

• US 5,847,410 A
• Filed: 11/25/1996
• Issued: 12/08/1998
• Est. Priority Date: 11/24/1995
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Nakajima, Setsuo
• Primary Examiner(s): Hardy, David B.
• Application Number:
  US08/756,172
• Time in Patent Office: 743 Days
• Field of Search: 257/59, 257/72, 257/749
• US Class Current: 257/59
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence

Abstract

A display device comprising a pixel portion having a thin film transistor using silicon as a semiconductor layer and a pixel electrode connected to the thin film transistor, wherein: said pixel electrode having a first transparent electrically conductive film electrically connected to said semiconductor layer and a second transparent electrically conductive film disposed on the first transparent electrically conductive film; said first transparent electrically conductive film comprises an oxide layer of a first metal having an oxidation potential lower than that of silicon; and said second transparent electrically conductive film comprises an oxide layer of a second metal having an oxidation potential higher than that of silicon. Also claimed is a process for fabricating the display device.

Claims

1. An electro-optical device comprising a pixel portion having a thin film transistor using silicon as a semiconductor layer and a pixel electrode connected to the thin film transistor,

wherein said pixel electrode comprises a first transparent electrically conductive film electrically connected to said semiconductor layer and a second transparent electrically conductive film disposed on the first transparent electrically conductive film,

said first transparent electrically conductive film comprises an oxide layer of a first metal having an oxidation potential lower than that of silicon, and

said second transparent electrically conductive film comprises an oxide layer of a second metal having an oxidation potential higher than that of silicon.

2. The device of claim 1, wherein the oxide layer of the first metal comprises titanium oxide, and the oxide layer of the second metal comprises a metal compound containing indium oxide as the principal component thereof.

3. The device of claim 1, wherein a region connected to the first transparent electrically conductive film contains an impurity having a predetermined electric conductivity.

4. An electro-optical device comprising a pixel portion having a thin film transistor using a semiconductor layer comprising silicon and a pixel electrode connected to the thin film transistor,

wherein said pixel electrode having a first transparent electrically conductive film electrically connected to said semiconductor layer and a second transparent electrically conductive film placed on the first transparent electrically conductive film,

said first transparent electrically conductive film comprises an oxide layer obtained by oxidizing by heat treatment a first metal having an oxidation potential lower than that of silicon, and

said second transparent electrically conductive film comprises an oxide layer of a second metal having an oxidation potential higher than that of silicon.

5. An electro-optical device comprising a pixel portion having a thin film transistor using a semiconductor layer comprising silicon and a pixel electrode electrically connected to said thin film transistor,

wherein said pixel electrode comprises a titanium oxide film electrically connected to said semiconductor layer and an indium oxide film disposed on the titanium oxide film.

6. The device of claim 5 wherein said indium oxide film includes indium tin oxide.

7. An electro-optical device comprising a pixel portion having a thin film transistor using a semiconductor layer comprising silicon and a pixel electrode connected to said thin film transistor,

wherein said pixel electrode comprises a titanium oxide film electrically connected to said semiconductor layer and a metal compound film comprising an indium oxide in contact with said titanium oxide film.

8. The device of claim 7 wherein said indium oxide includes indium tin oxide.

9. An electro-optical device comprising:

a first electrically conductive film comprising an oxide layer of a first metal electrically connected to a semiconductor layer comprising silicon; and

a second electrically conductive film comprising an oxide layer of a second metal,

wherein said first metal has an oxidation potential lower than that of said second metal.

10. The device of claim 9 wherein said oxide layer of the second metal comprises indium oxide or indium tin oxide.