Semiconductor device and method for manufacturing semiconductor device

A semiconductor device comprising:

• a semiconductor substrate including a cell portion and an outer peripheral portion outside the cell portion;
• a gate electrode provided inside a trench formed on an upper surface of the cell portion;
• a cell portion interlayer film inside the trench provided on the gate electrode;
• an outer peripheral portion interlayer film provided on an upper surface of a mesa portion adjacent to the trench in the outer peripheral portion;
• and
• a main electrode provided on the cell portion interlayer film and the outer peripheral portion interlayer film and in contact with the cell portion interlayer film and the outer peripheral portion interlayer film, wherein
• the cell portion interlayer film includes impurities,
• the outer peripheral portion interlayer film includes a first outer peripheral portion interlayer film, and a second outer peripheral portion interlayer film provided on the first outer peripheral portion interlayer film and in contact with the main electrode, and
• a portion of an upper surface of the outer peripheral portion interlayer film directly above the mesa portion and an end face of the outer peripheral portion interlayer film above the mesa portion are formed of a same type of interlayer film.

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

• in a semiconductor substrate including a cell portion and an outer peripheral portion outside the cell portion, forming a trench on an upper surface of the cell portion,
• forming a gate electrode inside the trench,
• forming a first interlayer film on an upper surface of the semiconductor substrate from the cell portion to the outer peripheral portion,
• etching the first interlayer film so that the first interlayer film remains inside the trench,
• after the etching of the first interlayer film, forming a second interlayer film on the upper surface of the semiconductor substrate from the cell portion to the outer peripheral portion such that the second interlayer film is formed on the first interlayer film inside the trench,
• etching the second interlayer film so that the second interlayer film remains inside the trench and in the outer peripheral portion, and
• after the etching of the second interlayer film, forming a main electrode on the second interlayer film so as to be in contact with the second interlayer film, wherein
• one of the first interlayer film and the second interlayer film includes impurities.