Patent ID: 7910440

Claim:
A method for making the semiconductor device comprising: concurrently forming a first trench, a second trench wider than the first trench, and a third trench wider than the second trench on the same surface of a semiconductor layer; forming an oxide film on a surface of the semiconductor layer; filling up the first trench with conductive material without filling up the second trench and the third trench therewith, through deposition of the conductive material on the semiconductor layer where the oxide film is formed, the conductive material corresponding to a gate electrode; removing by etching all of the conductive material deposited in the second trench and the third trench with the conductive material being left in the first trench; filling up the second trench with insulating material without filling up the third trench therewith, through deposition of the insulating material on the semiconductor layer where the oxide film is formed, the insulating material corresponding to an embedded insulation layer; removing by etching all of the insulating material and all of the oxide film deposited in the third trench with the insulating material being left in the second trench; and covering at least an inner surface of the third trench with metallic material, through deposition of the metallic material on the semiconductor layer, the metallic material corresponding to an electrode film.