Patent ID: 7135739

Claim:
A vertical-type metal insulator field effect transistor device comprising: a first conductivity type drain region layer; a plurality of second conductivity type base regions produced and arranged in said first conductivity type drain region layer; a first conductivity type source region produced in each of said second conductivity type base regions; both a flat gate insulating layer and a flat gate electrode layer formed on said first conductivity type drain region layer such that a plurality of unit transistor cells are produced in conjunction with said second conductivity type base regions and said first conductivity type source regions, each of said unit transistor cells including respective span portions of said gate insulating layer and said gate electrode layer, which bridge a space between the first conductivity type source regions formed in two adjacent second conductivity base regions; and a buried-insulator region produced in said first conductivity type drain region layer beneath each of the portions of said gate electrode layer.