Patent ID: 6982193

Claim:
A method of forming a semiconductor device comprising: providing a substrate of a first conductivity type; forming a doped layer of the first conductivity type on at least a portion the substrate; forming a first opening in the doped layer wherein the first opening has sidewalls; doping a first region of the doped layer juxtaposed to at least a portion of the sidewalls of the first opening to form a first doped region along the sidewalls and extending into the doped layer leaving a first portion of the doped layer adjacent to the first doped region and distal from the first opening; doping a second region of the doped layer between the first region and the sidewalls to form a second doped region along the sidewalls between a portion of the first doped region and the sidewalls wherein the second doped region has a conductivity that is opposite to a conductivity of the first doped region; and forming a transistor on the substrate wherein the second doped region remains distinct from the first doped region.