A method of forming a semiconductor device includes forming a first well and a second well in a substrate, wherein the first well is doped with dopants of a first conductivity type and the second well is doped with dopants of a second conductivity type. A third well is formed within the first well, and a gate structure is formed above the substrate, the gate structure partially overlying at least the first and second wells. A first epi region is formed on the third well, wherein the first epi region is doped with second dopants of the second conductivity type, and a drain region is formed that is electrically coupled to the second well.