Mis-type semiconductor device

Abstract

A MIS-type semiconductor device has reduced ON-resistance by securing an overlapping area between the gate electrode and the drift region, and has low switching losses by reducing the feedback capacitance. The MIS-type semiconductor device includes a p-type base region, an n-type drift region, a p-type stopper region in the base region, a gate insulation film on the base region, a gate electrode on the gate insulation film, an oxide film on the drift region, a field plate on the oxide film, and a source electrode. The position (P) of the impurity concentration peak in base region is located more closely to the drift region. The oxide film is thinner on the side of the gate electrode. The field plate is connected electrically to the source electrode, the spacing (dg) between the gate insulation film and the stopper region is 2.5 μm or narrower, and the minimum spacing (x) between the drain region and the stopper region is 5.6 μm or narrower. The minimum thickness of the oxide film is equal to or larger than the thickness of the gate insulation film and equal to or smaller than the ratio Vb/Ec of the breakdown voltage Vb to the critical dielectric breakdown strength of silicon Ec. The drift region can be formed of first and second drift regions, with the first drift region being more heavily doped. The gate electrode and the drift region can be buried.