TRENCH MOSFET DEVICE WITH IMPROVED ON-RESISTANCE

摘要

A trench MOSFET device comprises: a substrate 200 of a first conductivity type an epitaxial layer 202 of the first conductivity type wherein the epitaxial layer has a lower impurity concentration than the substrate a trench extending into the epitaxial layer an insulated conductive region 211 within the trench a doped region 206 of the first conductivity type formed within the epitaxial layer between a bottom portion of the trench and the substrate, wherein the doped region has an impurity concentration that is lower than that of the substrate and higher than that of the epitaxial layer a body region 204 of a second conductivity type formed within an upper portion of the epitaxial layer and adjacent trench wherein the body region extends to a lesser depth from the upper surface of the epitaxial layer than does the trench a source region 212 within the body region.