Patent ID: 6242292
Filing Date: 2001-06-05
Classification: H01L

Abstract:
A method for producing a semiconductor device comprising the steps of:forming a semiconductor film over a substrate having an insulating surface;first irradiating said semiconductor film with a pulsed first linear laser light having a first energy density while moving said substrate in a first scanning direction at a first scanning speed, said first scanning direction being perpendicular to a first longitudinal direction of said pulsed first linear laser light;second irradiating said semiconductor film with a second pulsed linear laser light having a second energy density higher than said first energy density while moving said substrate in a second scanning direction at a second scanning speed, said second scanning direction being perpendicular to a second longitudinal direction of said second pulsed linear laser light and being same as said first scanning direction wherein each irradiation of the first and second laser light is conducted in such a manner that an irradiation area of one pulse is partly overlapped with a next pulse; andforming a plurality of thin film transistors using said semiconductor film, each of said thin film transistors having an active region including source and drain regions and a channel region interposed therebetween, and a line connecting source and drain regions of one of said plurality of thin film transistors is substantially parallel with a line connecting source and drain regions of each other of said plurality of thin film transistors,wherein said active region of each of the plurality of the thin film transistors is formed in a portion of the semiconductor film which is irradiated with first pulses of said first pulsed linear laser light and with second pulses of said second pulsed linear laser light, andwherein variation of refractive indexes of said channel regions in said first and second scanning directions is more than in a direction perpendicular to said first and second scanning directions.