Method for fabricating a DMOS transistor

摘要

Disclosed is an improved method for fabricating double-diffused MOS (DMOS) transistors, comprising the steps of thermally oxidizing a previously formed oxide layer on a semiconductor substrate to form a partially and relatively thick oxide layer before performing a POCl3 doping. During the POCl3 doping to render a conductivity to a gate polysilicon layer, phosphorus of the POCl3 can not be penetrated into the substrate through the relatively thick oxide layer. A completed DMOS device has the channel region in the P type body and in the source/drain region which has an ununiform provision of impurity concentration, and results in increase of a withstanding voltage.