Patent ID: 7517759
Filing Date: 2009-04-14
Classification: H01L

Abstract:
1. A method of fabricating a metal oxide semiconductor device, comprising the steps of: providing a substrate, wherein the substrate is doped a second conductivity type dopant and is used as a drain; forming a first conductivity type epitaxial layer on the substrate; forming a second conductivity type epitaxial layer on the first epitaxial layer, wherein the doping concentration in the second conductivity type epitaxial layer decreases gradually from the bottom to the top of the second conductivity type epitaxial layer; patterning the second conductivity type epitaxial layer and a portion of the first epitaxial layer with a pattern of trench to form a plurality of islands; forming a gate dielectric layer on a surface of the trench; forming a gate in the trench to cover the gate dielectric layer; and forming a source at the top of the islands.