Semiconductor device and method of fabricating thereof

A method of fabricating a semiconductor device comprising the steps of:

• forming a first undercoat insulating film having a refractive index different from a refractive index of a substrate over the substrate having a light transmitting performance;
• forming a plurality of recessed portions by partially etching the first undercoat insulating film;
• forming a second undercoat insulating film having a refractive index different from the refractive index of the first undercoat insulating film over the first undercoat insulating film formed with the plurality of recessed portions;
• forming an amorphous semiconductor film over the second undercoat insulating film;
• and
• forming a crystalline semiconductor film by irradiating a laser beam from a rear face side of the substrate or both sides of a surface side and the rear face side of the substrate to the amorphous semiconductor film;
• wherein the crystalline semiconductor film formed over the recessed portions is made to constitute a channel forming region of TFT.

A method of fabricating a semiconductor device comprising the steps of:

• forming a first undercoat insulating film having a refractive index different from a refractive index of a substrate over the substrate having a light transmitting performance;
• forming a plurality of projected portions by partially etching the first undercoat insulating film;
• forming a second undercoat insulating film having a refractive index different from the refractive index of the first undercoat insulating film over the first undercoat insulating film formed with the plurality of projected portions;
• forming an amorphous semiconductor film over the second undercoat insulating film;
• and
• forming a crystalline semiconductor film by irradiating a laser beam from a rear face side of the substrate or both sides of a surface side and the rear face side of the substrate to the amorphous semiconductor film;
• wherein the crystalline semiconductor film formed over the projected portions is made to constitute a channel forming region of TFT.

A semiconductor device formed by the steps of:

• forming a first undercoat insulating film having a refractive index different from a refractive index of a substrate over the substrate having a light transmitting performance;
• forming a second undercoat insulating film having a refractive index different from the refractive index of the first undercoat insulating film and having a plurality of projected portions over the first undercoat insulating film;
• forming an amorphous semiconductor film over the second undercoat insulating film;
• and
• forming a crystalline semiconductor film by irradiating a laser beam to the amorphous semiconductor film;
• wherein the crystalline semiconductor film over the projected portions are made to constitute a channel forming region of TFT.

A semiconductor device formed by the steps of:

• forming a first undercoat insulating film having a plurality of recessed portions and having a refractive index different from a refractive index of a substrate over the substrate having a light transmitting performance;
• forming a second undercoat insulating film having a refractive index different from the refractive index of the first undercoat insulating film over the first undercoat insulating film;
• forming an amorphous semiconductor film over the second undercoat insulating film;
• and
• forming a crystalline semiconductor film by irradiating a laser beam to the amorphous semiconductor film;
• wherein the crystalline semiconductor film over the recessed portions are made to form a channel forming region of TFT.

A semiconductor device formed by the steps of:

• forming a first undercoat insulating film having a plurality of projected portions and having a refractive index different from a refractive index of a substrate over the substrate having a light transmitting performance;
• forming a second undercoat insulating film having a refractive index different from the refractive index of the first undercoat insulating film over the first undercoat insulating film;
• forming an amorphous semiconductor film over the second undercoat insulating film;
• and
• forming a crystalline semiconductor film by irradiating a laser beam to the amorphous semiconductor film;
• wherein the crystalline semiconductor film over the projected portions are made to form a channel forming region of TFT.