| 摘要 |
PROBLEM TO BE SOLVED: To stabilize the equipotential line in a first semiconductor region by covering a specific area of the surface of the first semiconductor region contacting one main surface of a semiconductor device, and to stabilize an element voltage by discouraging concentration of electric field. SOLUTION: The electric field in an S4 region is intensified two times or more than that near p-layers 134 and 135 in an n- layer, in short, a half or more of the area of n- layer 12 which is exposed to a main surface is covered with a forward/reverse field plate, so that a high yield is provided. With (L+ R)/(L+R+S) at least 0.5, an yield of about 95% is provided stably. (L, R, and S correspond to lengths L4, R4, and S4, respectively). An insulating film 30 in the S4 region is stronger than a semiconductor region for dielectric breakdown strength. Even if the forward/reverse field plate allows condensed equipotential line for increased electric field intensity, no dielectric breakdown takes place with the S4 region, causing no degradation in prevention voltage. |
