JPS574145A - Manufacturing process of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce a difference in heights of the surfaces of MOSIC and to make a hard occurrence of soft error by a method wherein an epitaxial layer having the same conductive characteristic as that of the substrate and a low concentration of impurities, the epitaxial layer is selectively removed up to such a depth as it is reached to the substrate and then separated under its oxidation process. CONSTITUTION:P-type epitaxial layer 6 having 20OMEGAcm is formed to have a thickness of about 1.5mum on P-type Si substrate plate 1 having, for example, a specific resistance of 0.01OMEGAcm, both a dampening thermo-oxidation film 2 and CVD nitrization film 3 are formed on the surface of the epitaxial layer. Then, after the nitrization film 3 and the oxidation film 2 in the area for forming the separation layer are removed, the epitaxial layer 6 is etched up to a depth in which it is reached to the substrate plate 1. Then, the nitrization film 3 is oxidized under a hot temperature, and the separate oxidation film 14 is grown up to a surface position of the epitaxial layer 6. In sequence, for example, several steps for making a memory element are performed to make IC. Thereby, the oxidation film 14 having less height difference in a surface thereof may be formed in a relative short period of time. Pairs of electronic positive holes which are generated by alpha-rays are diminished rapidly in an area of the substrate plate 1, so that it is possible to make a hard occurrence of soft error.