Ldmos with field plates

Abstract

There is provided a high withstand voltage LDMOS field-effect transistor that enables the compatibility of an increase of its withstand voltage and a decrease of its ON resistance. The high withstand voltage LDMOS is characterizing in including: a first electroconductive type body region formed on a main surface of a semiconductor substrate; a second electroconductive type source region formed on a surface of the body region; a second electroconductive type drift region formed so as to have contact with the body region; a second electroconductive type drain region formed on the drift region; a first electroconductive type buried region having contact with the body region and formed below the drift region; a gate electrode formed above the body region between the source region and the drift region and above the drift region nearer to the source region via a gate insulating film; a first field plate that extends from the gate electrode toward the drain region and that is formed above the drift region via a first insulating film; and a second field plate that has contact with the source region or the gate electrode and that is formed above the first field plate via a second insulating film, in which a distance between the buried region and the drain region is smaller than a distance between the first field plate and the drain region and larger than a distance between the second field plate and the drain region.