PURPOSE: To obtain stability for a prolonged term regarding reverse leakage current characteristics by forming an annular aluminum film to the predetermined surface of a Pb group gas film while being separated from a P-N junction and surrounding the P-N junction.

CONSTITUTION: An anode contact window is bored, Al is evaporated, and an annular aluminum film 12 is formed together with an anode electrode 5 through selective etching by a photographic process. The whole is sintered in a nitrogen atmosphere in order to obtain an ohmic contact between the anode electrode 5 and a P+ diffusion layer 2. Glass 3b under the Al film 12 during a sintering process has some quantity of positive charges ⊕ though glass 3a in a section in which there is no Al film 12 has a large quantity of negative currents . Consequently, an inversion layer 9 is stopped only under the glass film 3a. Accordingly, an initial contact with a channel stopper layer 4 of the inversion layer 9 is prevented, and leakage currents are controlled.