HIGH-VOLTAGE SEMICONDUCTOR ELEMENT AND MANUFACTURING METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a high-voltage semiconductor element, using SIPOS(semi- insulating polycrystalline silicon) that improves electrical characteristics and facilitates production, and to provide its manufacturing method. SOLUTION: A semi-polysilicon film 150 is formed on a semiconductor substrate 100 to relax the field concentration in a field region, and a thermal oxide film 160 is formed on it as a protective film. This thermal oxide film improves an interface state for a semi-insulating polysilicon film as compared with a CVD oxide film and can reduce the amount of the leakage current. The thermal oxide film shows higher surface protection and dielectric strength effects than for a two-layer semi-insulating polysilicon film and can greatly reduce the process time. Furthermore, as shown in Fig. 4, the DC current gain of the element can be prevented from decreasing within the low collector current range, by removing the semi-insulating polysilicon film 150 from an active region.