Patent ID: 7553778

Claim:
A method for producing a semiconductor device, comprising: irradiating an amorphous semiconductor film on an insulating material and having a thickness in a range from 60 nm to 100 nm, with a pulsed laser beam having a wavelength in a range from 390 nm to 640 nm and a rectangular irradiation area, while scanning in a direction intersecting a longitudinal direction of the irradiation area, thereby forming a first polycrystalline semiconductor film; and irradiating a part of the amorphous semiconductor film with the laser beam while scanning in a longitudinal direction, intersecting the irradiation area, the part being partially superposed on the first polycrystalline semiconductor film and being partially adjacent to the first polycrystalline semiconductor film, thereby forming a second polycrystalline semiconductor film, the second polycrystallline semiconductor film having a larger surface roughness than parts of the first polycrystalline semiconductor film on which the second polycrystalline semiconductor film is not superposed.