Patent ID: 7226841

Claim:
A method of manufacturing a semiconductor device, comprising: forming a semiconductor layer on a semiconductor substrate of a first conductivity type; forming a trench having a first opening in the semiconductor layer, the trench extending in a depth direction toward the semiconductor substrate; ion-implanting first and second impurities into an inner wall of the trench through the first opening; diffusing the first impurities to form a first region of the first conductivity in the depth direction on and along a side of the trench in the semiconductor layer, a bottom of the first region contacting the semiconductor substrate; diffusing the second impurities to form a second region of a second conductivity type in the depth direction along the first region in the semiconductor layer, the second region contacting one side of the first region, which is opposite to another side contacting the trench; burying a filling layer into the trench; forming a third region of the first conductivity type in a surface area of the semiconductor layer and close to the side of the trench, the third region contacting the first region; forming a fourth region of the second conductivity type in the surface area of the semiconductor layer, the fourth region having impurity concentration which is higher than that of the second region; and forming a fifth region of the first conductivity type in a surface area of the fourth region.