| 摘要 |
PURPOSE:To enhance the reverse withstand voltage characteristic of a semiconductor element in which reverse mesa type bevel etching is performed from the back of a semiconductor wafer provided with a p-n junction on the surface by a method wherein impurity diffusion walls to suppress extension of depletion layers are provided at the adjacents part of the p-n junctions on the sides. CONSTITUTION:An n<-> type collector layer 18, a p type base layer 17 are made to grow epitaxially on an n<+> type substrate 19, and after a protective film is formed, openings are formed to provide n type emitter layers 16 by diffusion. The wafer 15 thereof is etched from the back 23 to form bevel etched grooves in nearly V shape, and walls 24 are made to be inclined as to form the exposed sides of collector junctions 21. Then p<++> type impurity diffusion walls 25 to suppress extension of the depletion layers are provided at the bottom parts 28 of grooves. Accordingly reverse withstand voltage characteristic is enhanced, distortion of wave form is eliminated, and noise can be reduced. |
