Patent ID: 7492003

Claim:
A power semiconductor device comprising: a semiconductor substrate of one conductivity; an epitaxial semiconductor body of another conductivity on a surface of said substrate; a gate trench in said epitaxial semiconductor body; a drift region of said one conductivity extending from at least the bottom of said trench to said substrate and extending along only a portion of the sidewalls of said gate trench, said drift region of said one conductivity and said epitaxial semiconductor body being in charge balance; a source region of said one conductivity formed in said epitaxial semiconductor body adjacent said gate trench and spaced from said drift region of said one conductivity by an invertible channel region adjacent said trench; a source contact in ohmic contact with at least said source region; and a drain contact in ohmic contact with said substrate, wherein said drift region includes a high resistivity region adjacent said substrate and a low resistivity region adjacent said gate trench.