Patent ID: 8999790
Filing Date: 2015-04-07
Classification: H01L

Abstract:
1. A method of forming a trench gate MOSFET comprising: forming an epitaxial layer with a first conductivity type on a substrate with the first conductivity type; forming a trench in the epitaxial layer; conformally forming a first insulating layer on surfaces of the epitaxial layer and the trench; forming a first conductive layer at a bottom of the trench; removing a portion of the first insulating layer to form a second insulating layer exposing an upper portion of the first conductive layer; performing an oxidation process to oxidize the first conductive layer to a third insulating layer, wherein a fourth insulating layer is simultaneously formed on the surface of the epitaxial layer and on a sidewall of the trench by the oxidation process; forming a second conductive layer in the trench; forming two body layers with a second conductivity type in the epitaxial layer respectively beside the trench; and forming two doped regions with the first conductivity type in the body layers respectively beside the trench.