Patent ID: 7271048

Claim:
A method of manufacturing a trench MOSFET comprising: providing a substrate and forming an epitaxy layer on said substrate; forming a mask oxide layer on said epitaxy layer and defining a trench opening to expose a surface of said epitaxy layer where a trench structure is to be formed; forming a sidewall spacer on a sidewall of said mask oxide layer around said trench opening for narrowing said trench opening; etching said epitaxy layer to form a trench structure; removing said mask oxide layer and said sidewall spacer; forming a gate oxide layer on a surface of said epitaxy layer and an inner sidewall of said trench structure, and filling said trench structure with a polysilicon layer; after filling said trench structure with a polysilicon layer, implanting a body structure in said epitaxy layer; blanket implanting a source layer between said body structure and said gate oxide layer; forming a dielectric layer on said trench structure and said gate oxide layer; downward etching said dielectric layer, said gate oxide layer and said source layer till a surface of said body structure for defining a source structure and forming a contact region; forming a contact plus structure in said body structure via said contact region, wherein said contact plus structure is exposed via said contact region; filling said contact region with a contact layer for contacting with said contact plus structure; back etching said contact layer till a surface of said dielectric layer; and forming a conductive metal layer on said contact layer and said dielectric layer for obtaining said trench MOSFET.