Patent ID: 7271041

Claim:
A method for manufacturing a thin film transistor comprising, in order, the steps of: depositing a non-single crystal semiconductor film on an insulting substrate; introducing at least one dopant into all regions of said non-single crystal semiconductor film; irradiating, for the first time, said non-single crystal semiconductor film with a laser beam to convert a non-single crystal material of said non-single crystal semiconductor film into a crystallized semiconductor film; and forming transistors of different conductivity types in said crystallized semiconductor film, and wherein introducing at least one dopant into all regions of said non-single crystal semiconductor film includes introducing said at least one dopant into all regions of said non-single crystal semiconductor film through a protective film formed on said non-single crystal semiconductor film and wherein irradiating said non-single crystal semiconductor film with a laser beam includes removing said protective film from said non-single crystal semiconductor film and then irradiating said non-single crystal semiconductor film with said laser beam.