Patent ID: 7413966

Claim:
A method of forming a polycrystalline silicon active layer for use in a thin film transistor, comprising: forming a buffer layer over a substrate; forming an amorphous silicon layer over the buffer layer; applying a catalytic metal to a surface of the amorphous silicon layer; crystallizing the entire amorphous silicon layer having the catalytic metal thereon into a whole polycrystalline silicon layer; annealing the whole polycrystalline silicon layer directly on the buffer layer and having the catalytic metal thereon in an N 2 gas atmosphere to stabilize the whole polycrystalline silicon layer; after annealing, etching a surface of the stabilized whole polycrystalline silicon layer using an etchant to remove a residual catalytic metal left on the surface of the whole polycrystalline silicon layer; and patterning the whole polycrystalline silicon layer to form an island-shaped active layer wherein said annealing the whole polycrystalline silicon layer is performed after crystallizing the entire amorphous silicon layer.