Thin film transistor

• US 5,202,572 A
• Filed: 01/23/1992
• Issued: 04/13/1993
• Est. Priority Date: 09/21/1988
• Status: Expired due to Fees

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Kobayashi, Kenichi
• Primary Examiner(s): LARKINS, WILLIAM
• Application Number:
  US07/826,636
• Time in Patent Office: 446 Days
• Field of Search: 357/21.7, 357/23.7, 357/4, 437/184
• US Class Current: 257/60
• CPC Class Codes: H01L 29/66765 Lateral single gate single channel transistors with inverted structure, i.e. the channel layer is formed after the gate

Abstract

A thin-film transistor basically comprises an insulating substrate, a gate electrode formed on the substrate, a gate insulating layer covering the gate electrode, a semiconductor layer formed on the gate insulating layer, and source/drain electrodes electrically connected to the semiconductor layer. An insulating layer is interposed between the source/drain electrodes and the semiconductor layer, and the source/drain electrodes are electrically connected to the semiconductor layer through a pair of openings provided in the insulating layer. The connection to the semiconductor layer is made directly or via an electrical connection member.

Claims

1. In a thin-film transistor comprising an insulating substrate, a gate electrode formed on the substrate, a gate insulating layer covering the gate electrode, a first semiconductor layer formed on the gate insulating layer, and source and drain electrodes electrically connected to the first semiconductor layer, the improvement comprising:

a protective layer formed on the first semiconductor layer above the gate electrode;

an insulating layer interposed between the source and drain electrodes and the first semiconductor layer, said insulating layer having a portion which overlies said gate electrode and said protective layer, and said insulating layer being provided with a pair of openings through which the source and drain electrodes are electrically connected to the first semiconductor layer; and

source and drain electrical connection members disposed between said insulating layer and the first semiconductor layer, for electrically connecting the source and drain electrodes to the first semiconductor layer;

wherein each said electrical connection member comprises a second semiconductor layer containing p-type or n-type impurity atoms and formed on the first semiconductor layer, and a diffusion preventive layer disposed between said second semiconductor layer and both said source and drain electrodes and said insulating layer for preventing metal constituting the source and drain electrodes from diffusing into said second semiconductor layer;

said second semiconductor layer and said diffusion preventive layer partially overlap said protective layer;

said insulating layer partially overlaps said second semiconductor layer and said diffusion preventive layer; and

said source and drain electrodes overlie said insulating layer.

2. The thin-film transistor according to claim 1, wherein said protective layer is disposed between the first semiconductor layer and the portion of said insulating layer which overlies the gate electrode, for protecting the first semiconductor layer.