High withstand voltage semiconductor device and method of manufacturing the same

摘要

In the surface layer of an n-type semiconductor substrate 1, an n+ cathode region 2 and a p+ anode region 3 are formed, on which a cathode electrode 5 and an anode electrode 6 are formed, respectively. An oxide film 4 serving as a surface protection film is formed partially on the n+ cathode region 2, p+ anode region 3 and n-type semiconductor substrate 1 sandwiched by these regions. On the oxide film 4, a semi-insulating silicon nitride film 10 having a thickness of 1 mu m is deposited by the plasma CVD technique. The film composition of the surface layer of the semi-insulating silicon nitride film 10 is changed into silicon nitride film (Si3N4) having a thickness of about 0.1 mu m to form an insulating silicon nitride film 8. Then, the composition of the underlying semi-insulating silicon nitride film is not changed. The semi-insulating silicon nitride film serves as a field plate so that concentration of the electric field on the surface can be relaxed. <IMAGE>