Power MOS FET with carrier lifetime killer

Claim 1

An MOS type field effect transistor comprising: a drain region made of a semiconductor substrate of a first conduction type; a base region of a second conduction type formed within said semiconductor substrate, said base region having a deep portion and a shallow portion; a source region of the first conduction type formed within said base region; a gate insulator layer formed above said base region between said drain region and said source region; a gate electrode formed on said gate insulator layer; a covering insulator layer formed over the surface of said substrate including said gate electrode, an opening being formed in a portion of said covering insulator layer and above a PN diode junction formed by said drain and said deep portion of the base region, said opening being located at a position laterally displaced from said gate electrode; a source electrode connected to a portion of said source region and a portion of said base region through said opening; and a drain electrode connected to said drain region; wherein platinum is diffused as a lifetime killer into the vicinity of said diode junction so that the concentration of platinum in the surface of said base region and said source region below said opening is highest.