Method of fabricating a high voltage semiconductor device using sipos

Abstract

A high voltage semiconductor device including a semiconductor substrate on which a semi-insulating polycrystalline silicon layer is formed to alleviate electric field concentration in a field region, is disclosed. A thermal oxide layer is formed on the semi-insulating polycrystalline silicon layer to serve as a protective layer. The thermal oxide layer forms a good interface with the semi-insulating polycrystalline silicon layer compared to a wet etched oxide layer or a chemical vapor deposition (CVD) oxide layer, thereby decreasing the amount of leakage current. In addition, compared to a dual semi-insulating polycrystalline silicon layer, the thermal oxide layer exhibits a high surface protection effect and a high resistance against dielectric breakdown. It also allows a great reduction in fabrication time. In particular, the semi-insulating polycrystalline silicon layer is removed from the active region, thereby preventing the direct current (DC) gain of a device from being lowered within a low collector current range caused by the semi-insulating polycrystalline silicon layer.