Semiconductor device and method of fabricating the same

A method of manufacturing a semiconductor device comprising:

• forming a semiconductor film over a substrate;
• etching the semiconductor film into a semiconductor layer;
• forming a gate insulating film on the semiconductor layer;
• forming a conductive layer on the gate insulating film;
• selectively etching the conductive layer to form a tapered gate electrode and a tapered gate insulating film;
• and
• introducing an n-type impurity element into the semiconductor layer through the tapered gate insulating film to form a low concentration n-type impurity region in the semiconductor layer,
• wherein the low n-type impurity concentration region has a gradient of concentration of the n-type impurity element in a direction parallel with a surface of the substrate.

A method of manufacturing a semiconductor device comprising:

• forming a semiconductor film over a substrate;
• etching the semiconductor film into a semiconductor layer;
• forming a gate insulating film on the semiconductor layer;
• forming a conductive layer on the gate insulating film;
• and
• selectively etching the conductive layer to form a tapered gate electrode and a tapered gate insulating film.

A method of manufacturing a semiconductor device comprising:

• forming a semiconductor film over a substrate;
• crystallizing the semiconductor film;
• etching the crystallized semiconductor film into a semiconductor layer;
• forming a gate insulating film on the semiconductor layer;
• forming a conductive layer on the gate insulating film;
• and
• selectively etching the conductive layer to form a tapered gate electrode and a tapered gate insulating film.

A method of manufacturing a semiconductor device comprising:

• forming a semiconductor film over a substrate;
• crystallizing the semiconductor film;
• etching the crystallized semiconductor film into a semiconductor layer;
• forming a gate insulating film on the semiconductor layer;
• forming a conductive layer on the gate insulating film;
• selectively etching the conductive layer to form a tapered gate electrode and a tapered gate insulating film;
• and
• introducing an n-type impurity element into the semiconductor layer through the tapered gate insulating film to form a low concentration n-type impurity region in the semiconductor layer.