Patent ID: 6884665

Claim:
A method for manufacturing a thin film transistor comprising the steps of: depositing a non-single crystal semiconductor film on an insulting substrate; introducing at least one dopant into the whole of said non-single crystal semiconductor film; irradiating 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 single crystal material, resulting in formation of a crystallized semiconductor film; and forming transistors of different conductivity types in said crystallized semiconductor film, said method being further constructed such that a ratio between quasi-fermi level of said single crystal material corresponding to one of said transistors of different conductivity types and quasi-fermi level of said single crystal material corresponding to the other of said transistors of different conductivity types is between 0.5:1 and 2.0:1 wherein introducing at least one dopant into the whole of said non-single crystal semiconductor film includes introducing said at least one dopant into the whole 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.