Patent ID: 7868416

Claim:
A semiconductor device comprising: a substrate; a source region formed on the surface portion of the substrate, a first insulating layer formed on the substrate; a gate electrode formed on the first insulating layer; a second insulating layer formed on the gate electrode; a body section connected with the source region, penetrating through the first insulating layer, the gate electrode and the second insulating layer, and containing an insulating region; a gate insulating film surrounding the body section, and formed between the body section and the gate electrode; and a drain region connected with the body section; wherein the gate electrode has a boron-doped first amorphous silicon film, a second amorphous silicon film formed on the first amorphous silicon film, and a boron-doped third amorphous silicon film formed on the second amorphous silicon film; and the diameter of the body section on the second amorphous silicon film portion is larger than the diameter on the first amorphous silicon film portion and the diameter on the third amorphous silicon film portion.