Patent ID: 6884684

Claim:
A method of forming a high-density trench power-MOSFET structure, said method comprising the following steps of: forming a first dielectric layer on a substrate, wherein said first dielectric layer and said substrate are identical in polarity; forming a second dielectric layer on said first dielectric layer, wherein said first dielectric layer and said second dielectric layer have are opposite in polarity; forming a trench structure in the substrate/first dielectric layer/second dielectric layer combination structure, wherein said trench structure penetrates said second dielectric layer; forming a gate oxide layer on an outer surface of said trench structure; forming a first conducting layer to fill said trench structure to serve as a gate structure, wherein a top surface of said first conducting layer is lower than a top surface of said second dielectric layer; forming a third dielectric layer on said gate structure, wherein a top surface of said third dielectric layer and a top surface of said second dielectric layer form a plane; forming a first doped region in said second dielectric layer to serve as a deep body region, wherein said first doped region and said second dielectric layer are identical in polarity; forming a second doped region in said second dielectric layer to serve as a source region, wherein said second doped region is next to sidewalls of said trench structure and said second doped region and said first dielectric layer are identical in polarity; forming a fourth dielectric layer to cover said third dielectric layer; and forming a second conducting layer on said fourth dielectric layer and said second dielectric layer.