Method of fabricating staggered thin film transistor with an improved ohmic contact structure

Claim 1

A method of forming a multi-layer structure between source/drain electrodes and an amorphous silicon layer in a forward staggered thin film transistor, said method comprising the steps of: forming an undoped indium tin oxide transparent conductive film on an insulator; forming an impurity doped indium tin oxide transparent conductive film on said undoped transparent conductive film; patterning laminations of said undoped transparent conductive film and said impurity doped transparent conductive film to form source/drain electrodes; and forming an amorphous silicon active layer over said source/drain electrodes and a top surface of said insulator along with a heat treatment so that in said amorphous silicon active layer over said source/drain electrodes, an impurity diffused interface is formed, which is in contact with said impurity doped transparent conductive film thereby to form ohmic contacts between said impurity doped transparent conductive film and said amorphous silicon active layer, whilst no impurity introduced region is formed in said amorphous silicon active layer being in contact with said top surface of said insulator and being positioned between said source/drain electrodes.

Claim 2

A method of forming a multi-layer structure between source/drain electrodes and an amorphous silicon layer in a forward staggered thin film transistor, said method comprising the steps of: forming an undoped indium tin oxide transparent conductive film on an insulator; forming an impurity doped indium tin oxide transparent conductive film on said undoped transparent conductive film; patterning laminations of said undoped transparent conductive film and said impurity doped transparent conductive film to form source/drain electrodes; and forming an amorphous silicon active layer over said source/drain electrodes and a top surface of said insulator along with a heat treatment so that in said amorphous silicon active layer over said source/drain electrodes, an impurity diffused interface is formed, which is in contact with said impurity doped transparent conductive film thereby to form ohmic contacts between said impurity doped transparent conductive film and said amorphous silicon active layer, whilst no impurity introduced region is formed in said amorphous silicon active layer being in contact with said top surface of said insulator and being positioned between said source/drain electrodes.

Claim 14

A method of forming a forward staggered thin film transistor, said method comprising the steps of: forming an undoped indium tin oxide transparent conductive film on an insulator; forming an n type impurity doped indium tin oxide transparent conductive film on said undoped transparent conductive film; patterning laminations of said undoped transparent conductive film and said impurity doped transparent conductive film to form source/drain electrodes; and successively forming an amorphous silicon active layer and a gate insulation film over said source/drain electrodes and a top surface of said insulator along with a heat treatment so that in said amorphous silicon active layer over said source/drain electrodes, an impurity diffused interface is formed which is in contact with said impurity doped transparent conductive film thereby to form ohmic contacts between said impurity doped transparent conductive film and said amorphous silicon active layer, whilst no impurity introduced region is formed in said amorphous silicon active layer being in contact with said top surface of said insulator and being positioned between said source/drain electrodes; forming a gate electrode film on said gate insulation film; and patterning laminations of said amorphous silicon active layer, said gate insulation film and said gate electrode film.

Claim 15

A method of forming a forward staggered thin film transistor, said method comprising the steps of: forming an undoped indium tin oxide transparent conductive film on an insulator; forming an n type impurity doped indium tin oxide transparent conductive film on said undoped transparent conductive film; patterning laminations of said undoped transparent conductive film and said impurity doped transparent conductive film to form source/drain electrodes; and successively forming an amorphous silicon active layer and a gate insulation film over said source/drain electrodes and a top surface of said insulator along with a heat treatment so that in said amorphous silicon active layer over said source/drain electrodes, an impurity diffused interface is formed which is in contact with said impurity doped transparent conductive film thereby to form ohmic contacts between said impurity doped transparent conductive film and said amorphous silicon active layer, whilst no impurity introduced region is formed in said amorphous silicon active layer being in contact with said top surface of said insulator and being positioned between said source/drain electrodes; forming a gate electrode film on said gate insulation film; and patterning laminations of said amorphous silicon active layer, said gate insulation film and said gate electrode film.

Claim 27

A method of forming a forward staggered thin film transistor, said method comprising the steps of: selectively forming an optical shielding metal film on a first region of a top surface of a glass substrate; forming an inter-layer insulator which extends over said optical shielding metal film and said top surface of said glass substrate; forming an undoped indium tin oxide film on said inter-layer insulator; forming an impurity doped indium tin oxide film on said undoped indium tin oxide film; patterning laminations of said undoped indium tin oxide film and said impurity doped indium tin oxide film to form source/drain electrodes; and successively forming an amorphous silicon active layer and a gate insulation film over said source/drain electrodes and a top surface of said insulator along with a plasma chemical vapor deposition method so that in said amorphous silicon active layer over said source/drain electrodes, an impurity diffused interface is formed which is in contact with said impurity doped indium tin oxide film thereby to form ohmic contacts between said impurity doped indium tin oxide film and said amorphous silicon active layer, whilst no impurity introduced region is formed in said amorphous silicon active layer being in contact with said top surface of said insulator and being positioned between said source/drain electrodes; forming a gate electrode film on said gate insulation film; and patterning laminations of said amorphous silicon active layer, said gate insulation film and said gate electrode film.

Claim 28

A method of forming a forward staggered thin film transistor, said method comprising the steps of: selectively forming an optical shielding metal film on a first region of a top surface of a glass substrate; forming an inter-layer insulator which extends over said optical shielding metal film and said top surface of said glass substrate; forming an undoped indium tin oxide film on said inter-layer insulator; forming an impurity doped indium tin oxide film on said undoped indium tin oxide film; patterning laminations of said undoped indium tin oxide film and said impurity doped indium tin oxide film to form source/drain electrodes; and successively forming an amorphous silicon active layer and a gate insulation film over said source/drain electrodes and a top surface of said insulator along with a plasma chemical vapor deposition method so that in said amorphous silicon active layer over said source/drain electrodes, an impurity diffused interface is formed which is in contact with said impurity doped indium tin oxide film thereby to form ohmic contacts between said impurity doped indium tin oxide film and said amorphous silicon active layer, whilst no impurity introduced region is formed in said amorphous silicon active layer being in contact with said top surface of said insulator and being positioned between said source/drain electrodes; forming a gate electrode film on said gate insulation film; and patterning laminations of said amorphous silicon active layer, said gate insulation film and said gate electrode film.