SEMICONDUCTOR DEVICE AND METHOD OF MANUFACTURING THE SAME

LDMOS having an n-type source region and a drain region formed on an upper surface of a semiconductor substrate, a gate electrode formed on the semiconductor substrate via a gate dielectric film, and a field plate electrode formed on the semiconductor substrate between the gate electrode and the drain region via a dielectric film having a larger film thickness than the gate dielectric film, is formed. Here, the field plate electrode has a larger work function than an n-type semiconductor region formed in the semiconductor substrate directly below the field plate electrode.