Semiconductor device and fabrication method thereof

A method of manufacturing a semiconductor device comprising the steps of: forming a semiconductor layer on an insulating surface; forming a gate insulating film on said semiconductor layer; forming a first conductive film, a second conductive film, and a third conductive film on said gate insulating film; etching said first conductive film, said second conductive film, and said third conductive film to thereby form a first gate electrode comprising a first electrode, a second electrode and a third electrode; doping an n-type impurity element into said semiconductor layer in a self-aligned manner with said first gate electrode as a mask; etching said first electrode, said second electrode, and said third electrode to thereby form a second gate electrode comprising a fourth electrode, a fifth electrode and a sixth electrode; and doping an n-type impurity element into said semiconductor layer with said second gate electrode as a mask.

A method of manufacturing a semiconductor device comprising the steps of: forming a semiconductor layer on an insulating surface; forming a gate insulating film on said semiconductor layer; forming a first conductive film, a second conductive film, and a third conductive film on said gate insulating film; etching said first conductive film, said second conductive film, and said third conductive film to thereby form a first gate electrode comprising a first electrode, a second electrode and a third electrode; doping an n-type impurity element into said semiconductor layer in a self-aligned manner with said first gate electrode as a mask to form a n-type impurity region (A); etching said first electrode, said second electrode, and said third electrode to thereby form a second gate electrode comprising a fourth electrode, a fifth electrode and a sixth electrode; and doping an n-type impurity element into said semiconductor layer with said second gate electrode as a mask to form n-type impurity region (B).

A method of manufacturing a semiconductor device comprising the steps of: forming a semiconductor layer on an insulating surface; forming a gate insulating film on said semiconductor layer; forming a first conductive film, a second conductive film, and a third conductive film on said gate insulating film; etching said first conductive film, said second conductive film, and said third conductive film to thereby form a first gate electrode comprising a first electrode, a second electrode and a third electrode; doping an n-type impurity element into said semiconductor layer in a self-aligned manner with said first gate electrode as a mask to form a n-type impurity region (A) comprising said n-type impurity element at a concentration of 110 20 to 110 22 /cm 3 ; etching said first electrode, said second electrode, and said third electrode to thereby form a second gate electrode comprising a fourth electrode, a fifth electrode and a sixth electrode; and doping an n-type impurity element into said semiconductor layer with said second gate electrode as a mask to form n-type impurity region (B) comprising said n-type impurity element at a concentration of 110 17 to 110 20 /cm 3 .