A layer of well oxide is grown over the n-well or p-well region of the semiconductor substrate. A deep n-well implant is performed in high voltage device region, followed by a deep n-well drive-in of the deep n-well implant. The well oxide is removed; the field oxide (FOX) region is created in the high voltage device region. A layer of sacrificial oxide is deposited on the surface of the semiconductor substrate. A low voltage cluster n-well implant is performed in the high voltage PMOS region of the semiconductor substrate followed, for the high voltage NMOS region, by a low voltage cluster p-well implant which is followed by a buried p-well cluster implant.