Patent ID: 8227858

Claim:
A power metal-oxide-semiconductor field effect transistor (MOSFET), comprising: a substrate of a first conductivity type; an epitaxial layer of the first conductivity type, disposed on the substrate; a body layer of a second conductivity type, disposed in the epitaxial layer, wherein a trench is disposed in the body layer and in a portion of the epitaxial layer; an isolation structure, disposed on the substrate at one side of the trench; a first oxide layer, disposed on a surface of the trench; a first conductive layer, filling in the trench and extending to a portion of the isolation structure; a dielectric layer, disposed on the first conductive layer and the isolation structure and having an opening exposing a portion of the first conductive layer; at least one source region of the first conductivity type, disposed in the body layer at the other side of the trench; a second conductive layer, disposed on the dielectric layer and electrically connected to the source region while electrically isolated from the first conductive layer by the dielectric layer; and a third conductive layer, disposed on the dielectric layer and electrically connected to the first conductive layer through the opening of the dielectric layer, wherein the second conductive layer and the third conductive layer are separated from each other, wherein the first conductive layer comprises a first part filling in the trench and a second part extending from the first part to the portion of the isolation structure, and the dielectric layer covers on a portion of a surface of the first part directly, and the surface of the first part of the first conductive layer is no higher than a surface of the body layer.