Method of manufacturing thin film transistor, thin film transistor manufactured by using the method, method of manufacturing organic light-emitting display apparatus, and organic light-emitting display apparatus manufactured by using the method

Abstract

A method of manufacturing a thin film transistor (TFT) comprises forming a buffer layer, an amorphous silicon layer, and an insulating layer on a substrate; crystallizing the amorphous silicon layer as a polycrystalline silicon layer; forming a semiconductor layer and a gate insulating layer which have a predetermined shape by simultaneously patterning the polycrystalline silicon layer and the insulating layer; forming a gate electrode including a first portion and a second portion by forming and patterning a metal layer on the gate insulating layer. The first portion is formed on the gate insulating layer and overlaps a channel region of a semiconductor layer, and the second portion contacts the semiconductor layer. A source region and a drain region are formed on the semiconductor layer by doping a region of the semiconductor layer. The region excludes the channel region overlapping the gate electrode and constitutes a region which does not overlap the gate electrode. An interlayer insulating layer is formed on the gate electrode so as to cover the gate insulating layer; contact holes are formed on the interlayer insulating layer and the gate insulating layer so as to expose the source region and the drain region, and simultaneously an opening for exposing the second portion is formed. A source electrode and a drain electrode are formed by patterning a conductive layer on the interlayer insulating layer. The source electrode and the drain electrode are electrically connected to the source region and the drain region via the contact holes, and simultaneously the second portion exposed via the opening is removed.