Method for fabricating a polysilicon thin film transistor

Abstract

A method for fabricating a polysilicon thin film transistor combining the channel oxidation process and the plasma hydrogenation process is disclosed. The fabrication process includes the following steps: (a) forming a field oxide layer on a silicon substrate, (b) forming a polysilicon layer on a portion of the field oxide layer to serve as a gate, (c) forming a gate oxide on the polysilicon layer and another portion of the field oxide layer, (d) forming a polysilicon channel on the gate oxide layer, (e) defining a source region and a drain region in a portion of the polysilicon channel, (f) oxidizing another portion of the polysilicon channel, (g) forming a dielectric layer on said polysilicon channel, and (h) hydrogenating said polysilicon thin film transistor by plasma. Such a combination results in an better efficiency for passivating the tail state traps, and can prevent the polysilicon thin film from being damaged caused by the plasma glow during the plasma hydrogenation process. The polysilicon thin film transistor formed thereby has a lower subthreshold swing, higher on/off current ratio, and excellent reliability.

Dependencies are inferred from the claim text.