Semiconductor device and manufacturing method thereof

A method of manufacturing a semiconductor device comprising steps of:

• forming a semiconductor layer on an insulating surface;
• forming an insulating film on said semiconductor layer;
• forming a first electrode comprising a laminate structure of a first conductive layer with a first width and a second conductive layer on said insulating film;
• adding an impurity element to said semiconductor layer using said first electrode as a mask to form a high concentration impurity region;
• etching said second conductive layer to form a second electrode comprising a laminate structure of the first conductive layer with said first width and said second conductive layer with a second width;
• adding the impurity element to said semiconductor layer using said second conductive layer as a mask to form a low concentration impurity region;
• and
• etching said first conductive layer to form a third electrode comprising a laminate structure of said first conductive layer with a third width and said second conductive layer with said second width.

A method of manufacturing a semiconductor device comprising steps of:

• forming a semiconductor layer on an insulating surface;
• forming an insulating film on said semiconductor layer;
• forming a first electrode comprising a laminate structure of a first conductive layer with a first width and a second conductive layer on said insulating film;
• etching said second conductive layer to form a second electrode comprising a laminate structure of said first conductive layer with said first width and said second conductive layer with a second width;
• adding an impurity element to said semiconductor layer using said second electrode as a mask to form a high concentration impurity region;
• adding said impurity element to said semiconductor layer through said first conductive layer using the second conductive layer as a mask to form a low concentration impurity region;
• and
• etching said first conductive layer to form a third electrode comprising a laminate structure of said first conductive layer with a third width and said second conductive layer with said second width.

A method of manufacturing a semiconductor device comprising steps of:

• forming a semiconductor layer on an insulating surface;
• forming an insulating film on said semiconductor layer;
• forming a first electrode comprising a laminate structure of a first conductive layer with a first width and a second conductive layer on said insulating film;
• etching said second conductive layer to form a second electrode comprising a laminate structure of said first conductive layer with said first width and said second conductive layer with a second width;
• adding an impurity element to said semiconductor layer using said second conductive layer as a mask to form a low concentration impurity region and a high concentration impurity region;
• and
• etching said first conductive layer to form a third electrode comprising a laminate structure of said first conductive layer with a third width and said second conductive layer with said second width.

A method of manufacturing a semiconductor device comprising steps of:

• forming a semiconductor layer on an insulating surface;
• forming an insulating film on said semiconductor layer;
• laminating a first conductive film and a second conductive film on said insulating film;
• forming a second conductive layer with a first width;
• adding an impurity element to said semiconductor layer using said second conductive layer with said first width as a mask to form a high concentration impurity region;
• etching said first conductive film to form a first electrode comprising a laminate structure of said first conductive layer with a second width and said second conductive layer with a third width;
• etching said second conductive layer to form a second electrode comprising a laminate structure of said first conductive layer with said second width and said second conductive layer with a fourth width;
• adding said impurity element to said semiconductor layer through said first conductive layer using said second conductive layer with said fourth width as a mask to form a low concentration impurity region;
• and
• etching said first conductive layer to form a third electrode comprising a laminate structure of said first conductive layer with a fifth width and said second conductive layer with said fourth width.

A method of manufacturing a semiconductor device comprising steps of:

• forming a semiconductor layer on an insulating surface;
• forming an insulating film on said semiconductor layer;
• laminating a first conductive film and a second conductive film on said insulating film;
• forming a second conductive layer with a first width;
• adding an impurity element to said semiconductor layer using said second conductive layer with said first width as a mask to form a high concentration impurity region;
• etching said second conductive layer to form said second conductive layer with a second width;
• adding an impurity element to said semiconductor layer through said first conductive film using said second conductive layer with said second width as a mask to form a low concentration impurity region;
• and
• etching said first conductive film to form an electrode comprising a laminate structure of said first conductive layer with a third width and said second conductive layer with said second width.