Patent ID: 8232610
Filing Date: 2012-07-31
Classification: H01L

Abstract:
1. A semiconductor device comprising: a drain region of a field-effect transistor disposed over a semiconductor substrate; a channel forming region of the field-effect transistor disposed over the drain region; a source region of the field-effect transistor disposed over the channel forming region; a trench reaching the drain region from an upper surface of the source region; a first insulating film disposed in the trench and disposed at a lower part of the trench; a first conductive film disposed over the first insulating film in the trench and disposed at the lower part of the trench, the first conductive film serving as a dummy gate electrode; a gate insulating film of the field-effect transistor disposed over the first insulating film in the trench and disposed at a upper part of the trench; and a gate electrode of the field-effect transistor disposed over the gate insulating film in the trench and disposed at the upper part of the trench, wherein the gate electrode and the first conductive film are separately disposed and are insulated from each other by an intervening second insulating film, wherein a thickness of the gate insulating film is less than a thickness of the first insulating film, wherein an outer peripheral portion of the trench is filled with the first conductive film through the first insulating film such that a lead-out part of the first conductive film extends over the semiconductor substrate, and wherein a concentration of impurities introduced in the dummy gate electrode is lower than that of impurities introduced in the gate electrode of the field-effect transistor.