| 摘要 |
PURPOSE:To prevent the degrading of voltage-withstanding capability attributable to moisture and to prevent the occurrence of short circuits between electrodes during a withstand voltage test by a method wherein a metal coating is formed, on an insulating film covering a guard ring region surrounding a base region, to be free of ohmic contact with said guard ring region. CONSTITUTION:Just over the innermost guard ring region 4A at the least, of the guard ring regions 4A-4B encircling the base region 3 of a planar-type transistor, a metal coating 12 is formed, with the intermediary of an insulating film 7, not to contact the guard ring region 4A owing to the insulating film 7. The metal coating 1 is a ring, as seen from above, formed on the insulating film 7, covering the entire guard ring region 4A. It follows therefore that there is no ohmic contact between the metal coating 12 and the guard ring region 4A. This design eliminates the possibilities of the generation of sparks beween the metal coating 12 and other electrodes during a withstand voltage testing process or of the occurrence of inversion in the guard ring region attributable to moisture. |
