Semiconductor device and method for manufacturing semiconductor device

A method for manufacturing a semiconductor device that includes a semiconductor substrate including a cell area and a termination area that surrounds the cell area, wherein the cell area is provided with a plurality of main trenches, the termination area is provided with one or more termination trenches surrounding the cell area, the one or more termination trenches comprise a first termination trench, which is disposed at an innermost circumference, and in an inner region of the first termination trench, a first conductive type body region is disposed on a surface of a second conductive type drift region,

• the method comprising:
• a trench forming process that forms the plurality of main trenches in the cell area, and the one or more termination trenches surrounding the cell area,
• an insulating layer forming process that forms an insulating layer on a surface of the semiconductor substrate, the thickness of the insulating layer being a predetermined value,
• an etching process that selectively etches the insulating layer disposed in the cell area by a predetermined amount, and
• a conductive layer forming process that selectively forms a conductive layer within each main trench and the first termination trench,
• wherein
• the plurality of main trenches penetrates the body region from the surface of the semiconductor substrate and reaches the drift region, the semiconductor substrate including a first conductive type body region disposed on a surface of a second conductive type drift region, and
• the one or more termination trenches penetrates the body region from the surface of the semiconductor substrate and reaches the drift region,
• a depth of the plurality of main trenches is formed identical to a depth of the first termination trench in the trench forming process, and
• a thickness of the insulating layer covering a bottom surface of the first termination trench is formed thinner than a thickness of the insulating layer covering the bottom surface of the plurality of main trenches.