Patent ID: 6294419
Filing Date: 2001-09-25
Classification: H01L

Abstract:
A method for making a dual depth trench, the method comprising:a) providing a substrate having at least one dielectric layer thereon and a resist layer on said dielectric layer;b) patterning said resist layer and forming a trench through said at least one dielectric layer into said substrate according to said patterned resist layer;c) implanting a dopant into said substrate using said patterned resist layer as a mask for forming a doped region in said substrate below said trench;d) removing said resist and said at least one dielectric layer adjacent said trench;e) etching said substrate exposed by step d) simultaneously with said trench until a bottom of said trench reaches said doped region for forming a dual depth trench;f) filling said dual depth trench; andg) implanting wells of opposite conductivity types into said substrate on opposite sides of said dual depth trench.