Patent ID: 7799636
Filing Date: 2010-09-21
Classification: H01L,Y10S

Abstract:
1. A method of forming a semiconductor device, comprising: forming a masking layer over a silicon layer, the masking layer having openings through which surface areas of the silicon layer are exposed; isotropically etching the silicon layer through the masking layer openings so as to remove bowl-shaped portions of the silicon layer, each bowl-shaped portion having a middle portion and outer portions extending directly underneath the masking layer, the outer portions forming outer sections of corresponding trenches; removing additional portions of the silicon layer through the masking layer openings so as to form a middle section of the trenches which extends deeper into the silicon layer than the outer sections of the trenches; forming a first doped region of a first conductivity type in an upper portion of the silicon layer; forming an insulating layer within each trench, the insulating layer in each trench extending directly over a portion of the first doped region adjacent each trench sidewall; and removing silicon from adjacent each trench until, of the first doped region, only the portions adjacent the trench sidewalls remain, the remaining portions of the first doped region adjacent the trench sidewalls forming source regions which are self-aligned to the trenches.