Patent ID: 8278739

Claim:
A method for manufacturing a semiconductor device comprising: forming an insulating film over a substrate; forming an amorphous semiconductor film having a film thickness of equal to or more than 20 nm and equal to or less than 80 nm over the insulating film; forming, over the amorphous semiconductor film, a silicon nitride film in which a film thickness is 200 nm to 1000 nm, equal to or less than 10 atomic % of oxygen is included, and a relative proportion of nitrogen to silicon is equal to or more than 1.3 and equal to or less than 1.5; and forming a crystalline semiconductor film from the amorphous semiconductor film by irradiating the amorphous semiconductor film with a laser light through the silicon nitride film such that energy of the laser light is absorbed in the amorphous semiconductor film, wherein at a first plane of the crystalline semiconductor film, a ratio of crystal grains of an orientation of <001> within a range of ±10° of angle fluctuation is equal to or more than 60% and less than 100%, wherein at a second plane of the crystalline semiconductor film, a ratio of crystal grains of an orientation of any one of <001>, <101>, <201>, <301>, <401>, <501>, or <601> within a range of ±10° of angle fluctuation is equal to or more than 60% and less than 100%, wherein at a third plane of the crystalline semiconductor film, a ratio of crystal grains of an orientation of any one of <001>, <101>, <201>, <301>, <401>, <501>, or <601> within a range of ±10° of angle fluctuation is equal to or more than 60% and less than 100%, wherein a normal vector of the first plane is perpendicular to the surface of the substrate, wherein a normal vector of the second plane is parallel to the surface of the substrate and is parallel to the direction of crystal growth of crystal grain, wherein a normal vector of the third plane is parallel to the surface of the substrate and is perpendicular to the direction of crystal growth of crystal grain, and wherein the laser light is a continuous-wave laser light or a laser light with repetition rate of equal to or more than 10 MHz.