Method of manufacturing a semiconductor device with a vertical drain drift layer of the alternating-conductivity-type

Abstract

A semiconductor device includes an improved drain drift layer structure of alternating conductivity types, that is easy to manufacture, and that facilitates realizing a high current capacity and a high breakdown voltage and to provide a method of manufacturing the semiconductor device. The vertical MOSFET according to the invention includes an alternating-conductivity-type drain drift layer on an n-type drain layer as a substrate. The alternating-conductivity-type drain drift layer is formed of n-type drift current path regions and p-type partition regions alternately arranged laterally with each other. The n-type drift current path regions and p-type partition regions extend in perpendicular to n-type drain layer. Each p-type partition region is formed by vertically connecting p-type buried diffusion unit regions U. The n-type drift current path regions are residual regions, left after connecting p-type buried diffusion unit regions U, with the conductivity type thereof unchanged. The alternating-conductivity-type drain drift layer is formed by repeating the step of epitaxial layer growth and the step of implanting p-type impurity ions and by diffusing the impurity ions at once from the impurity sources located on multiple levels.