Staggered thin film transistor with transparent electrodes and an improved ohmic contact structure

Claim 2

A multi-layer structure of source/drain electrodes and an amorphous silicon layer in a forward staggered thin film transistor, said multi-layer structure comprising: source/drain electrodes selectively provided on an insulator, each of said source/drain electrodes comprising an undoped transparent conductive film on said insulator and an impurity doped transparent conductive film on said undoped transparent conductive film; and an amorphous silicon active layer extending over said source/drain electrodes and a top surface of said insulator so that said amorphous silicon active layer over said source/drain electrodes has an impurity diffused interface in contact with said impurity doped transparent conductive film to form ohmic contacts between said impurity doped transparent conductive film and said amorphous silicon active layer, said impurity diffused interface not contacting said top surface of said insulator, whilst said amorphous silicon active layer in contact with said top surface of said insulator between said source/drain electrodes is free of any impurity introduced region.

Claim 3

The multi-layer structure as claimed in claim 1, wherein said undoped transparent conductive film comprises an indium tin oxide film.

Claim 4

The multi-layer structure as claimed in claim 1, wherein said undoped transparent conductive film comprises an indium oxide film.

Claim 5

The multi-layer structure as claimed in claim 1, wherein said undoped transparent conductive film comprises a tin oxide film.

Claim 6

The multi-layer structure as claimed in claim 1, wherein said impurity doped transparent conductive film comprises an impurity doped indium tin oxide film.

Claim 7

The multi-layer structure as claimed in claim 1, wherein said impurity doped transparent conductive film comprises an impurity doped indium oxide film.

Claim 8

The multi-layer structure as claimed in claim 1, wherein said impurity doped transparent conductive film comprises an Impurity doped tin oxide film.

Claim 9

The multi-layer structure as claimed in claim 1, wherein said impurity doped transparent conductive film has a thickness of approximately 10% or less of a total thickness of said undoped transparent conductive film and said impurity doped transparent conductive film.

Claim 10

The multi-layer structure as claimed in claim 1, wherein said insulator comprises an inter-layer insulator made of silicon oxide.

Claim 11

The multi-layer structure as claimed in claim 1, wherein said insulator comprises an insulation substrate.

Claim 12

A forward staggered thin film transistor comprising: an insulator; source/drain electrodes selectively provided on an insulator, each of said source/drain electrodes comprising an undoped transparent conductive film on said insulator and an impurity doped transparent conductive film on said undoped transparent conductive film; an amorphous silicon active layer extending over said source/drain electrodes and a top surface of said insulator so that said amorphous silicon active layer over said source/drain electrodes has an impurity diffused interface in contact with said impurity doped transparent conductive film to form an ohmic contact between said impurity doped transparent conductive film and said amorphous silicon active layer, said impurity diffused interface not contacting said top surface of said insulator whilst said amorphous silicon active layer in contact with said top surface of said insulator between said source/drain electrodes is free of any impurity introduced region; a gate insulation film extending over said amorphous silicon active layer; and a gate electrode provided on said gate insulation film.

Claim 13

A forward staggered thin film transistor comprising: an insulator; source/drain electrodes selectively provided on an insulator, each of said source/drain electrodes comprising an undoped transparent conductive film on said insulator and an impurity doped transparent conductive film on said undoped transparent conductive film; an amorphous silicon active layer extending over said source/drain electrodes and a top surface of said insulator so that said amorphous silicon active layer over said source/drain electrodes has an impurity diffused interface in contact with said impurity doped transparent conductive film to form an ohmic contact between said impurity doped transparent conductive film and said amorphous silicon active layer, said impurity diffused interface not contacting said top surface of said insulator whilst said amorphous silicon active layer in contact with said top surface of said insulator between said source/drain electrodes is free of any impurity introduced region; a gate insulation film extending over said amorphous silicon active layer; and a gate electrode provided on said gate insulation film.

Claim 14

The forward staggered thin film transistor as claimed in claim 11, wherein said undoped transparent conductive film comprises an indium tin oxide film.

Claim 15

The forward staggered thin film transistor as claimed in claim 11, wherein said undoped transparent conductive film comprises an indium oxide film.

Claim 16

The forward staggered thin film transistor as claimed in claim 11, wherein said undoped transparent conductive film comprises a tin oxide film.

Claim 17

The forward staggered thin film transistor as claimed in claim 11, wherein said impurity doped transparent conductive film comprises an impurity doped indium tin oxide film.

Claim 18

The forward staggered thin film transistor as claimed in claim 11, wherein said impurity doped transparent conductive film comprises an impurity doped indium oxide film.

Claim 19

The forward staggered thin film transistor as claimed in claim 11, wherein said impurity doped transparent conductive film comprises an impurity doped tin oxide film.

Claim 20

The forward staggered thin film transistor as claimed in claim 11, wherein said impurity doped transparent conductive film has a thickness of approximately 10% or less of a total thickness of said undoped transparent conductive film and said impurity doped transparent conductive film.

Claim 21

The forward staggered thin film transistor as claimed in claim 11, wherein said insulator comprises an inter-layer insulator made of silicon oxide.

Claim 22

The forward staggered thin film transistor as claimed in claim 11, wherein said insulator comprises an insulation substrate.

Claim 23

A forward staggered thin film transistor comprising: a glass substrate; an optical shielding metal film selectively provided on a first predetermined region of a top surface of said glass substrate; an inter-layer insulator extending over said optical shielding metal film and said top surface of said glass substrate; source/drain electrodes selectively provided on second predetermined regions of a top surface of said interlayer insulator, each of said source/drain electrodes comprising an undoped indium tin oxide film on said inter-layer insulator and an impurity doped indium tin oxide film on said undoped indium tin oxide film; an amorphous silicon active layer extending over said source/drain electrodes and said top surface of said inter-layer insulator so that said amorphous silicon active layer over said source/drain electrodes has an impurity diffused interface in contact with said impurity doped indium tin oxide film to form an ohmic contact between said impurity doped indium tin oxide film and said amorphous silicon active layer, said impurity diffused interface not contacting said top surface of said interlayer insulator, whilst said amorphous silicon active layer in contact with said top surface of said inter-layer insulator between said source/drain electrodes is free of any impurity introduced region; a gate insulation film extending over said amorphous silicon active layer; and a gate electrode provided on said gate insulation film.

Claim 24

A forward staggered thin film transistor comprising: a glass substrate; an optical shielding metal film selectively provided on a first predetermined region of a top surface of said glass substrate; an inter-layer insulator extending over said optical shielding metal film and said top surface of said glass substrate; source/drain electrodes selectively provided on second predetermined regions of a top surface of said interlayer insulator, each of said source/drain electrodes comprising an undoped indium tin oxide film on said inter-layer insulator and an impurity doped indium tin oxide film on said undoped indium tin oxide film; an amorphous silicon active layer extending over said source/drain electrodes and said top surface of said inter-layer insulator so that said amorphous silicon active layer over said source/drain electrodes has an impurity diffused interface in contact with said impurity doped indium tin oxide film to form an ohmic contact between said impurity doped indium tin oxide film and said amorphous silicon active layer, said impurity diffused interface not contacting said top surface of said interlayer insulator, whilst said amorphous silicon active layer in contact with said top surface of said inter-layer insulator between said source/drain electrodes is free of any impurity introduced region; a gate insulation film extending over said amorphous silicon active layer; and a gate electrode provided on said gate insulation film.

Claim 25

The forward staggered thin film transistor as claimed in claim 21, wherein said impurity doped indium tin oxide film has a thickness of approximately 10% or less of a total thickness of said undoped indium tin oxide film and said impurity doped indium tin oxide film.