Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device, the method comprising:

• preparing a semiconductor layer in which a first semiconductor region of a first conductivity type is disposed over the entire thickness, a plurality of insulation regions are disposed at a distance from each other along a second direction orthogonal to a first direction, the first direction being a thickness direction, and a gate electrode is disposed in the insulation region;
• forming an interlayer insulation layer by depositing an insulation material on an upper surface of the semiconductor layer;
• implanting ions of impurities of a second conductivity type between adjacent ones of the insulation regions, and forming a second semiconductor region of a second conductivity type on the first semiconductor region sandwiched between adjacent ones of the insulation regions;
• implanting ions of impurities of a first conductivity type into the second semiconductor region, and forming a third semiconductor region of a first conductivity type on the second semiconductor region;
• forming a plurality of interlayer insulation regions on the plurality of insulation regions by removing the interlayer insulation layer between adjacent ones of the insulation regions, and forming a first trench in which the third semiconductor region is exposed at a bottom surface;
• forming a second trench that passes through the third semiconductor region exposed at the bottom surface of the first trench to extend up to a middle of the second semiconductor region, and is narrower than the first trench;
• depositing a conductive material on the upper surface of the semiconductor layer to form a first conductive film that covers upper surfaces of the plurality of interlayer insulation regions and an inner wall of the first trench and filles the second trench;
• depositing an insulation material on the upper surface of the semiconductor layer to form, on the first conductive film, an insulation layer that includes a material different from the first conductive film and filles a recessed portion between adjacent ones of the interlayer insulation regions;
• removing the insulation layer other than the insulation layer in the recessed portion to expose the first conductive film covering an upper surface of the interlayer insulation region, and forming an intermediate region in the recessed portion;
• depositing a conductive material on the upper surface of the semiconductor layer to form a second conductive film on the intermediate region and a portion of the first conductive film covering the upper surface of the interlayer insulation region;
• and
• forming a third conductive film on the second conductive film.