JPS6442836A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive accomplishment of high integration by a method wherein an inverted diffusion of a buried impurity diffusion layer into the second epitaxial layer, which is a semiconductor device forming region, is eliminated and the transverse diffusion of the isolation impurity diffusion layer for isolation of each semiconductor device is reduced. CONSTITUTION:The first epitaxial layer 13, having the conductivity type same as that of a substrate 11, is formed on the semiconductor substrate 11 on which a buried impurity diffusion layer 12 is formed, and the second epitaxial layer 14 of the conductivity type opposite of that of the first epitaxial layer 13 is formed thereon. Accordingly, when an isolation impurity diffusion layer is formed, the impurity diffusion layer is not invertedly diffused to the second epitaxial layer 14, the second epitaxial layer 14 can be thinly formed to obtain the same degree of withstand voltage as before, and the isolation impurity diffusion layer can also be formed shallow. As a result, the transverse diffusion of the diffusion layer can be reduced, each semiconductor forming region can be reduced, and the high integration of the semiconductor device can also be made possible.