Patent ID: 8829615

Claim:
A semiconductor device comprising: a well of a first conductivity type formed in a substrate; a gate electrode formed over the well; a first implant region formed in the well and extending from below the gate electrode, the first implant region having the first conductivity type; a second implant region formed in the well and extending from below the gate electrode, the second implant region having a second conductivity type, and the second implant region being separated from the first implant region by a channel region below the gate electrode; a source diffusion region formed in the first implant region, the source diffusion region having the second conductivity type; a drain diffusion region formed in the second implant region, the drain diffusion region having the second conductivity type and having a heavier doping concentration than the second implant region; and a fourth implant region between the drain diffusion region and the second implant region, wherein the fourth implant region is of the same conductivity type as the drain diffusion region, wherein the fourth implant region has a lower doping concentration than the source diffusion region, and wherein the fourth implant region has a higher doping concentration than the second implant region.