| 摘要 |
PURPOSE:To increase the lifetime of a P base without decreasing emitter surface concentration, by a method wherein an N layer which is formed on one side surface, is composed two N layers differed by concentration of impurity on the surface, and distribution of concentration difference. CONSTITUTION:P layers 12 and 13 are prepared by diffusion of Ga from the both sides of an N type Si substrate 11 whose relative resistance is approximately 15- 250OMEGAcm. An N emitter layer 14 is made by selectively diffusing P on the P layer 13 side controlling surface concentration CNE1 to approximately 1X10<19>-1X10<20>/ cm<3> and diffusion depth xJ3 to approximately 5-20mum. And then, the P compound used for forming the N layer 14 is removed and a P-containing compound is piled again and P is thermally diffused to prepare an N emitter layer 24. Surface concentration CNE2 of the layer 24 is to be approximately 1X10<21>/cm<3> which is in the neighborhood of solid solution concentration of P and the diffusion depth xJ3 is less than 3mum. The P compound is removed, and electrodes and a protective film are provided. It is possible, by using this constitution, to prolong lifetime of carrier of the layer 13 without lowering the inverse breakdown voltage of a joint J3 between the layers 13 and 14 and also to obtain such characteritics as to keep low ON voltage and low holding current, etc. maintaining the conventional controllable current. |
