Patent ID: 6677189
Filing Date: 2004-01-13
Classification: H01L

Abstract:
A method of forming a polysilicon thin film transistor with a self-aligned LDD structure, comprising steps of:(a) providing a transparent insulating substrate with a polysilicon layer formed on the substrate and a gate insulating layer formed on the polysilicon layer; (b) forming a first metal layer, a second metal layer and a patterned photoresist layer successively on an entire surface of the substrate; (c) dry etching to remove the second metal layer and the first metal layer not covered by the patterned photoresist layer; (d) performing a first ion implantation process with the patterned photoresist layer as a mask to form a heavily doped region in a peripheral region of the polysilicon layer; (e) wet etching to remove a part of a peripheral region of the second metal layer so as to expose a part of a peripheral region of the first metal layer; (f) removing the patterned photoresist layer; and (g) dry etching to remove the exposed part of the first metal layer so as to level off the sidewalls of the second metal layer and the first metal layer.