| 摘要 |
PURPOSE:To obtain a planar type power transistor with a high withstand voltage approaching a theoretical value by eliminating the concentration of electric field arising from curvature at a P-N junction by a method wherein the P-N junction is shaped at the bulk to contain near right angles, in the process of the building of a base region forming P-N junction and some field rings arranged in a ring shape to surround said base junction. CONSTITUTION:A first condcutive type semiconductor substrate 1 to become a collector region is coated with an oxide film 5, wherein an opening is provided as perdetermined, and a base region 2 of the second conductive type and a multiplicity of field rings 4 of the second conductive type are formed, the rings 4 arranged surrounding the base region 2. Next, an emitter region 3 of the first conductive type is formed within the region 2 by diffusion. An oxide film 6 formed during this process is provided with an opening and an emitter electrode 7 is installed in the region 3. In this construction, the P-N junction 20 formed between the substrate 1 and the region 2 and the P-N junction 22 formed between the substrate 1 and the rings 4 would have some curvature if the diffusion method was employed. The formation thereof is therfore effected by means of ion implantation. This allows the junctions to be formed with near right angles, resulting in reduced electric field concentration particularly at the junction 20. |
