Method of forming a thin film transistor electrode with a tapered edge

摘要

A mask with a line and space pattern 150 whose space width is smaller than the resolution of the exposure system is used to pattern a photoresist layer formed over a metal layer which is used for forming the drain electrode of a thin film transistor. The photoresist pattern is only partially exposed around the edges of the pattern and after development corrugations are formed at the edges of the photoresist pattern. The photoresist pattern is used to mask the metal layer during etching to form the drain electrode and the metal layer beneath the corrugated photoresist pattern is partially etched during drain electrode formation. The drain electrode produced by the etching has a tapered sidewall profile at the position corresponding to the corrugations in the photoresist etch mask. The tapered sidewall profile reduces step coverage problems such as crack formation in the passivation layer formed over the drain electrode.