JPS6464257A - Semiconductor device - Google Patents

Abstract

PURPOSE:To realize a bipolar transistor having both high current amplification factor and high collector dielectric strength, by providing a base region so that it includes regions with a smaller base width and regions with a larger base width arranged altenately and periodically with a certain space. CONSTITUTION:A base region 2 having a dopant thickness, i.e. base width identical to those of prior arts is formed, while in this base region 2 regions 3 having a larger base width are provided periodically with a proper space from each other. These larger base width regions 3 may be formed, after formation of the base region 2, by introducing a dopant deep in regions as desired by means of a selective dopant introducing technique such as ion implantation or the like. In this manner, diffusion of a depletion layer 5 into a collector region 4 can be accelerated with the diffusion of the depletion layer 6 into the base region 2 inhibited. Accordingly, a high current amplification factor can be obtained in the base region 2 having a smaller base width, while high collector dielectric strength can be obtained in the larger base width regions 3. As a result, a bipolar transistor having high current amplification factor together with high collector dielectric strength can be obtained.