Thin film transistor and method of fabricating the same

Abstract

A thin film transistor (TFT) which may be used as a pixel drive element in an active matrix LCD display includes a pair of side wall spacers adjacent to the opposing side walls of its gate electrode. The side wall spacers provide the gate electrode with a substantially rectangular cross section, such that the gate electrode has a substantially constant thermal conductivity over its area. The TFT has a uniform device characteristic.

What is claimed is:  
     
         1 . A thin film transistor comprising: 
 an insulator substrate;    a gate electrode located on the insulator substrate;    a gate insulator film provided above the insulator substrate and the gate electrode; and    a polycrystalline silicon film located on the gate insulator film, the polycrystalline silicon film being formed by irradiating a laser beam on a surface of an amorphous silicon film to heat the amorphous silicon film,    the gate electrode having a center portion with a flat surface and a pair of tapered end portions with inclined surfaces, an angle between each of the inclined surfaces of the pair of tapered end portions and a surface of the insulator substrate being set within a range of 5° to 40° so that a uniform grain size of the polycrystalline silicon film is acquired by securing a gate withstand voltage of the thin film transistor and preventing the inclined surfaces of the pair of tapered end portions from increasing, wherein the laser beam is scanned on the surface of the amorphous silicon film such that laser energy increases in order of the substrate, one of the pair of tapered end portions, and the center portion.