Patent ID: 7176538

Claim:
A high voltage metal oxide semiconductor field effect transistor (MOSFET), comprising: a well region formed on a semiconductor substrate and doped with impurities of a first conductivity type; first and second diffusion regions isolated from each other by the well region and doped with impurities of a second conductivity type; a gate oxide layer formed on the well region; a gate electrode formed on the gate oxide layer; an impurity region formed under the well region and doped with impurities of the first conductivity type; a third diffusion region formed under the first diffusion region and doped with impurities of the second conductivity type; and a fourth diffusion region formed under the second diffusion region and doped with impurities of the second conductivity type; a buried layer doped with impurities of the first conductivity type under the third diffusion region, the well region, and the fourth diffusion region; and wherein the sides of the well region overlap with the third and fourth diffusion regions, respectively.