Method of making a thin film transistor

Abstract

This is a method of fabricating a transistor on a wafer. The method comprises: forming a doped silicon layer; patterning the active transistor regions of the doped silicon layer and utilizing a silicon etch to remove the non-transistor regions of the doped silicon layer to create a silicon mesa; forming a gate oxide layer on a doped silicon mesa; depositing a polysilicon layer on top of the oxide layer; depositing a photoresist layer over the polysilicon mesa; patterning the photoresist layer with a gate configuration; etching to remove portions of the polysilicon layer using the photoresist as a mask to create a polysilicon gate; depositing a TEOS layer over the polysilicon gate and exposed gate oxide; etching to remove portions of the TEOS layer and the exposed gate oxide to leave sidewall spacers on sides of the polysilicon gate and sides of silicon mesa; depositing a metal layer over remaining portions of the polysilicon gate, the sidewall spacers, and the silicon mesa; annealing the wafer to react portions of the metal layer with exposed portions of the silicon mesa to form a metal silicide; etching all unreacted the metal layer to leave the silicided portions of the polysilicon gate and silicided portion of the doped silicon layer.