HIGH BREAKDOWN STRENGTH SEMICONDUCTOR DEVICE

摘要

PURPOSE:To provide a high breakdown strength semiconductor device which can improve the breakdown strength without being accompanied with the increase of ON voltage. CONSTITUTION:In a high breakdown strength semiconductor device 1, which is equipped with a semiconductor substrate 1 provided with a semiconductor element, and a high breakdown strength construction for the semiconductor element, comprising field plates 12 and 13 and a reverse conductivity type of floating impurity diffusion area 15, the floating impurity diffusion area is made so as to be shallower stepwise as it comes near to the end of each field plate.