Method of manufacturing semiconductor device

A method of manufacturing a semiconductor device, comprising steps of:

• forming an amorphous semiconductor film over a glass substrate;
• forming a crystalline semiconductor film by irradiating the amorphous semiconductor film with continuous wave laser light;
• nitriding at least a portion of the crystalline semiconductor film;
• forming a conductive film over the crystalline semiconductor film;
• forming a mask having a tapered shape which is formed with a resist over the conductive film;
• and
• forming a gate electrode by etching the conductive film by using the mask,
• wherein the conductive film is etched so that the gate electrode has a gate length of 1.0 μm or less.

A method of manufacturing a semiconductor device, comprising steps of:

• forming a base film over a glass substrate;
• forming an amorphous semiconductor film over the base film;
• forming a crystalline semiconductor film by irradiating the amorphous semiconductor film with laser light;
• patterning the crystalline semiconductor film;
• nitriding a portion of the base film and at least a portion of the crystalline semiconductor film;
• washing a surface of the crystalline semiconductor film;
• forming a gate insulating film over the crystalline semiconductor film;
• forming a conductive film over the gate insulating film;
• forming a mask having a tapered shape over the conductive film;
• and
• forming a gate electrode by etching the conductive film using the mask,
• wherein the conductive film is etched so that the gate electrode has a gate length of 1.0 μm or less.

A method of manufacturing a semiconductor device, comprising steps of:

• forming an amorphous semiconductor film over a glass substrate;
• forming a crystalline semiconductor film by irradiating the amorphous semiconductor film with laser light;
• nitriding at least a portion of the crystalline semiconductor film;
• forming a conductive film over the crystalline semiconductor film;
• forming a mask having a tapered shape over the conductive film;
• forming a gate electrode by etching the conductive film by using the mask;
• forming an impurity region by adding an impurity element to the crystalline semiconductor film using the gate electrode as a mask;
• forming an insulating film which covers the gate electrode and the crystalline semiconductor film;
• forming an opening in the insulating film by using a mask having a vertical end portion so that the impurity region and a wiring are connected;
• and
• forming a wiring so as to connect with the impurity region via the opening,
• wherein the conductive film is etched so that the gate electrode has a gate length of 1.0 μm or less.