Patent ID: 6933184

Claim:
A method of manufacturing a semiconductor device comprising the steps of: forming a semiconductor layer on an insulating surface; forming an insulating film on said semiconductor layer; forming a first electrode comprising a first conductive layer having a first width on said insulating film and a second conductive layer on said first conductive layer; forming a high concentration impurity region in said semiconductor layer by adding a first impurity element using said first electrode as a mask; forming a second electrode comprising said first conductive layer having said first width and said second conductive layer having a second width that is different from said first width by etching said second conductive layer of said first electrode; forming a third electrode comprising said first conductive layer having a third width that is different from said first and second widths and said second conductive layer having said second width by etching said first conductive layer of said second electrode; and forming a low concentration impurity region in said semiconductor layer by adding a second impurity element through at least one of said first conductive layer and said insulating film using said second conductive layer as a mask.