Patent ID: 7800204

Claim:
A semiconductor device, comprising: a semiconductor substrate of a first conduction type having a first major surface and a second major surface opposite to each other; an anode portion of a second conduction type adjacent to said first major surface of said semiconductor substrate; a cathode portion of said first conduction type adjacent to said second major surface of said semiconductor substrate; and a stepwise impurity layer provided at one of said anode portion and said cathode portion by introducing an impurity of a predetermined conduction type from one of said first major surface and said second major surface of said semiconductor substrate through to a first depth to provide a first region of said semiconductor substrate having said impurity of said predetermined conduction type introduced therein, said predetermined conduction type being a same conduction type as a conduction type of the one of said anode portion and said cathode portion, and by melting a second, predetermined region of said semiconductor substrate having a second depth deeper than said first depth and including said first region to make uniform said impurity of said predetermined conduction type in a concentration from said one of said first major surface and said second major surface through to said second depth to provide a uniform stepwise impurity concentration profile.