Patent ID: 8587061

Claim:
A power MOSFET device comprises: An epitaxial layer disposed on a bottom substrate; A trench gate formed in a trench opened into the epitaxial layer; A body region formed from a top surface of the epitaxial layer into the epitaxial layer and surrounding the trench; A source region formed from the top surface of the epitaxial layer ( 20 ) into a top portion of the body region and surrounding the trench; A dielectric layer formed on the top surfaces of the trench gate and the source region; A contact trench opened through the dielectric layer and the source region; Wherein a bottom of the contact trench terminates at a depth shallower than a bottom of the body region, with bottom corners of the contact trench surrounded by the body region and a central portion of the contact trench bottom exposing a drift region; wherein a first conductive material disposed over the central portion of the contact trench bottom forming a Schottky junction with the drift region and a second conductive material lining over a sidewall and the bottom corners of the contact trench forming ohmic contact with the body region; and a third conductive material filling in the contact trench and extending above the top surface of the dielectric layer.