Method for fabricating a thin film transistor

Claim 1

A method for fabricating a thin film transistor, the method comprising the steps of: forming a gate insulating layer on a substrate; forming a gate electrode having at least one tapered side on the gate insulating layer; forming a mask layer over the substrate and the gate electrode; defining an offset region below the at least one tapered side of the gate electrode corresponding to the mask layer; oxidizing a portion of the gate electrode and a portion of the substrate corresponding to the offset region; and forming first and second impurity regions in the substrate at sides of the gate electrode, the second impurity region being adjacent to the offset region.

Claim 2

A method for fabricating a thin film transistor, the method comprising the steps of: forming a gate insulating layer on a substrate; forming a gate electrode having at least one tapered side on the gate insulating layer; forming a mask layer over the substrate and the gate electrode; defining an offset region below the at least one tapered side of the gate electrode corresponding to the mask layer; oxidizing a portion of the gate electrode and a portion of the substrate corresponding to the offset region; and forming first and second impurity regions in the substrate at sides of the gate electrode, the second impurity region being adjacent to the offset region.

Claim 9

A method for fabricating a thin film transistor, the method comprising the steps of: providing a substrate; forming a gate insulating layer over a portion of the substrate; forming a gate electrode having at least one tapered side over the gate insulating layer; forming an oxide film over the gate electrode and the substrate; forming an insulating film over a portion of the oxide film: oxidizing the oxide film to form a thicker portion using the insulating film as a mask, the thicker portion being at a region below the at least one tapered side of the gate electrode, implanting impurity ions into the substrate using the gate electrode as a mask to form first and second impurity regions, the second impurity region including an offset region corresponding to the thicker portion of the oxide film.

Claim 10

A method for fabricating a thin film transistor, the method comprising the steps of: providing a substrate; forming a gate insulating layer over a portion of the substrate; forming a gate electrode having at least one tapered side over the gate insulating layer; forming an oxide film over the gate electrode and the substrate; forming an insulating film over a portion of the oxide film: oxidizing the oxide film to form a thicker portion using the insulating film as a mask, the thicker portion being at a region below the at least one tapered side of the gate electrode, implanting impurity ions into the substrate using the gate electrode as a mask to form first and second impurity regions, the second impurity region including an offset region corresponding to the thicker portion of the oxide film.

Claim 17

A method for fabricating a thin film transistor, the method comprising the steps of: forming a first insulating layer on a substrate; forming a first semiconductor layer on the first insulating layer; forming a second insulating layer on the first semiconductor layer; forming a second semiconductor layer on the second insulating layer; forming a mask on the second semiconductor layer; etching the second semiconductor layer to form a gate with at least one tapered side by removing a larger amount of the second semiconductor layer at a top portion of the gate adjacent to the mask and removing a smaller amount of the second semiconductor layer at a bottom portion of the gate; forming a third insulating layer over the gate and the second semiconductor layer; forming a fourth insulating layer having a pattern defining an offset region, the fourth insulating layer having an etch selectivity different from an etch selectivity of the third insulating layer; oxidizing a portion of the gate electrode and a portion of the substrate corresponding to the offset region to form an oxide portion thicker than the second insulating layer; forming a first impurity region in the second semiconductor layer corresponding to the offset region; and forming second and third impurity regions in the second semiconductor layer adjacent sides of the gate, one of the second and third impurity regions being connected to the first impurity region.

Claim 18

A method for fabricating a thin film transistor, the method comprising the steps of: forming a first insulating layer on a substrate; forming a first semiconductor layer on the first insulating layer; forming a second insulating layer on the first semiconductor layer; forming a second semiconductor layer on the second insulating layer; forming a mask on the second semiconductor layer; etching the second semiconductor layer to form a gate with at least one tapered side by removing a larger amount of the second semiconductor layer at a top portion of the gate adjacent to the mask and removing a smaller amount of the second semiconductor layer at a bottom portion of the gate; forming a third insulating layer over the gate and the second semiconductor layer; forming a fourth insulating layer having a pattern defining an offset region, the fourth insulating layer having an etch selectivity different from an etch selectivity of the third insulating layer; oxidizing a portion of the gate electrode and a portion of the substrate corresponding to the offset region to form an oxide portion thicker than the second insulating layer; forming a first impurity region in the second semiconductor layer corresponding to the offset region; and forming second and third impurity regions in the second semiconductor layer adjacent sides of the gate, one of the second and third impurity regions being connected to the first impurity region.

Claim 20

A method for fabricating a thin film transistor, comprising the steps of: forming a gate insulating layer on a substrate; forming a gate electrode on the gate insulating layer; forming a first insulating film over an offset region and the gate electrode, the offset region being formed between one side portion of the gate electrode and an impurity region forming a patterned insulating film over the first insulating film; oxidizing the first insulating film using the patterned insulating film as a mask; and forming the impurity region in the substrate at sides of the gate electrode.

Claim 21

A method for fabricating a thin film transistor, comprising the steps of: forming a gate insulating layer on a substrate; forming a gate electrode on the gate insulating layer; forming a first insulating film over an offset region and the gate electrode, the offset region being formed between one side portion of the gate electrode and an impurity region forming a patterned insulating film over the first insulating film; oxidizing the first insulating film using the patterned insulating film as a mask; and forming the impurity region in the substrate at sides of the gate electrode.