| abstract |
This invention provides a semiconductor device to avoid the problem with a conventional semiconductor in which the shape of the depletion layer in a guard ring region is distorted and a stable voltage-resisting characteristic can not be obtained. In the semiconductor device of the present invention, a thermal oxide film (25) in a real operating region and a thermal oxide film (26) in a guard ring region are formed in a same process step. The thermal oxide film (25) is removed once and then formed again, and thus the thermal oxide film (26) is formed, for example, to have a thickness of about 8000 to 10,000 Å. By such process a CVD oxide film (27) containing movable ions (31) is formed at a position apart from the surface of an epitaxial layer (2), and a desirable voltage-resisting characteristic can be maintained by suppressing the distortion of the depletion layer caused by the movable ions (31). |