Patent ID: 8927369
Filing Date: 2015-01-06
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 and a first conductive layer on surfaces of the epitaxial layer and the trench; filling up the trench with a second insulating layer; removing a portion of the first conductive layer to form a second conductive layer below the second insulating layer; removing the second insulating layer and a portion of the first insulating layer to form a third insulating layer below the second conductive layer; performing an oxidation process to oxidize the second conductive layer to a fourth insulating layer, wherein a fifth 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 third 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.