JPS571243A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent lateral expansion of a field film in an MOSLSI by a method wherein a polycrystalline Si layer is provided to cover a mask pattern consisted of an oxide film and a nitride film, and after the layer is etched remaining the polycrystalline Si layer at the side faces, the substrate is oxidized. CONSTITUTION:In the selective oxidizing process of the MOSLSI, the oxidation- proof mask pattern consisted of the thin oxide film 2 and the Si nitride film 4 are formed on the Si substrate 1. The polycrystalline Si layer 8 is accumulated on the whole surface thereof to thickness of the same grade with the mask layer by CVD method. The polycrystalline Si layer 8 thereof is etched as to proceed etching in the vertical direction with a sputtering device, for example, to remain the polycrystalline Si layer 8' only at the side face parts of the mask pattern. Thermal oxidation process is performed in succession, and a field oxide film 5 is formed in the substrate 1. Accordingly progress of oxidation to the lower part of the mask pattern (lateral expansion) can be prevented, and the device can be manufactured in high density owing to the formation of the minute pattern.