Semiconductor device and production method therefor

A method for producing a semiconductor device comprising:

• forming a device region including a first conductivity type first layer, a second conductivity type second layer formed on the first layer, and an interface between the first layer and the second layer exposed on the end surfaces of the first layer and the second layer;
• and
• forming a terminal region surrounding the device region, wherein the method comprising:
• forming first conductivity type fourth layer in the terminal region and the device region respectively of the second layer by ion implantation into the terminal region and the device region of the second layer respectively;
• forming a third layer and a fifth layer in the second layer of the terminal region and the device region respectively by the ion implantation to form the fourth layer such that the third layer and the fifth layer have a carrier concentration distribution in which the carrier concentration is gradually increased toward the first layer;
• forming a mesa groove surrounding the device region and having a depth reaching from the surface of the second layer to the first layer, thereby the fourth layer disposed above the third layer being removed;
• and
• forming a recess groove surrounding the device region between the device region and the mesa groove and having an electric field relaxation region of the thinned second layer, thereby the fourth layer disposed above the third layer being removed.