Abstract: Provided are a semiconductor device which can be manufactured at low cost and has a low on-resistance and a high withstand voltage, and its manufacturing method. The semiconductor device comprises an N-type well area formed on a P-type semiconductor substrate, a P-type body area formed within the well area, an N-type source area formed within the body area, an N-type drain area formed at a distance from the body area within the well area, a gate insulating film formed so as to overlay a part of the body area, a gate electrode formed on the gate insulating film and a P-type buried diffusion area which makes contact with the bottom of the body area and extends to an area beneath the drain area in a direction parallel to the surface of the semiconductor substrate within the well area.

Abstract: Provided are a semiconductor device which can be manufactured at low cost and has a low on-resistance and a high withstand voltage, and its manufacturing method. The semiconductor device comprises an N-type well area formed on a P-type semiconductor substrate, a P-type body area formed within the well area, an N-type source area formed within the body area, an N-type drain area formed at a distance from the body area within the well area, a gate insulating film formed so as to overlay a part of the body area, a gate electrode formed on the gate insulating film and a P-type buried diffusion area which makes contact with the bottom of the body area and extends to an area beneath the drain area in a direction parallel to the surface of the semiconductor substrate within the well area.