PURPOSE: To remove completely a distortion layer on the surface, and to enhance reliability about the withstand voltage of a mesa diode by a method wherein the etching out quantity of the surface after formation of a bevel is restricted appropriately.

CONSTITUTION: A bevel shape is formed according to machining to a silicon plate 1 having a P type layer 3 on the under side of the high resistance N type layer 2 of the main body of a substrate, having an N+ type layer 4 on the top side, fixed with a metal supporting plate 5 to act as an anode electrode, and a cathode 6, and having P-N junction between the N type layer 2 and the P type layer 3, and etching is performed to remove a distortion layer. The etching out quantity 7 in the lateral direction is made to 200∼300μm. The slant 8 of an angle smaller than the bevel angle θ is formed on the periphery of the electrode 6, and the etching out quantity 9 in the lengthwise direction becomes to 30∼70μm at the peripheral edge. When the etching out quantity 9 in the lengthwise direction exceeds 70μm, a depletion layer 10 becomes easily to reach the N+ type layer 4 when a reverse voltage is applied to the diode, and brings about the fall of the withstand voltage.