Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device having high reverse voltage blocking ability, said method comprising:

• a step of preparing a drill having a cutting edge provided along a circumferential direction about the center of curvature of a rotation axis within a surface perpendicular to said rotation axis, said cutting edge being finished in a mesa type sectional configuration being decreased in width from a head portion toward a bottom portion;
• a step of forming a semiconductor wafer having a first conductivity type inner region of low impurity concentration and a second conductivity type outer region of high impurity concentration provided in an exterior of said inner region;
• a step of relatively moving said drill perpendicularly to a junction between said outer region and said inner region while rotatingly pressing said drill against a surface of said semiconductor wafer, thereby to form a ring-shaped vertical groove exposing said junction;
• and
• a step of rotatingly relatively moving said drill parallely to said junction, thereby to finish said ring-shaped vertical groove in mesa type sectional configurations of positive beveled structure.