MANUFACTURE OF SEMICONDUCTOR DEVICE

摘要

PURPOSE:To make it easy to set up Zener voltage by means of providing a Zener diode between an emitter layer and a base layer with high impurity concentration by a method wherein a collector layer with high impurity concentration at surface layer and normal concentration at lower layer is epitaxially grown on a semiconductor substrate and after diffusion-forming a deep base region in the collector region, an emitter region is provided in the base region. CONSTITUTION:An N type layer 2 to be a collector region is epitaxially grown on an N<+> type Si substrate 1 while the surface layer is ion implanted with N type impurity such as P etc. and then an N<++> layer 3 is formed on the layer 2 by heat treatment. Next a P type base region 4 penetrating into the layer 2 through the layer 3 is diffusion-formed and an N type emitter region 5 is provided in the region 4 to produce an NPN type transistor. Through those procedures, the upper peripheral part of P type base region 4 is encircled by the N<++> type layer 3 to make a Zener diode making it feasible to set up Zener voltage of a transistor extending over wide range.