Patent ID: 8212313

Claim:
A semiconductor device comprising a semiconductor base substance having a first semiconductor region having an impurity of a first conductivity type, and a second semiconductor region contacting a top surface of the first semiconductor region and having a second conductivity type different from the first conductivity type, the semiconductor base substance having: an element region, on which a switching element is formed; a terminal region formed so as to surround the element region when observed from an upper side; a trench formed in the depth direction from a top surface of the second semiconductor region of the terminal region; an insulating film formed on a sidewall and a bottom surface of the trench; and a first conductive layer embedded inside the trench via the insulating film, wherein the depth of the trench from the top surface of the second semiconductor region to the bottom surface of the trench is 0.9 to 2.0 times the thickness of the second semiconductor region and a plurality of the trenches are formed on the terminal region so as to traverse the semiconductor device from the element region side toward a termination side when observed from an upper side, and the thickness of the insulating film on the sidewall of the trench in the termination side is thick compared with the thickness of the insulating film on the sidewall of the trench in the element region side.