Patent ID: 6780693
Filing Date: 2004-08-24
Classification: H01L,Y10S

Abstract:
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 amorphous silicon layer having the catalytic metal thereon into a polycrystalline silicon layer; forming an island pattern on the polycrystalline silicon layer, thereby defining an active region underneath in the polycrystalline silicon layer; applying n-type ions to the polycrystalline silicon layer and then heat-treating the polycrystalline silicon layer to remove the catalytic metal from the active region underneath the island pattern; patterning the polycrystalline silicon layer using the island pattern as a mask to form an active layer; doping a small amount of p-type ions into the active layer to adjust a threshold voltage of the thin film transistor to be formed using the active layer; and removing the island pattern from the active layer.