JPS5779639A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a semiconductor device having few defect in a single crystal layer and having favorable electric characteristic by a method wherein thermal influence and generation of stress in the single crystal semiconductor layer to be caused at the time of selective oxidation is prevented. CONSTITUTION:A P type single crystal Si layer 2 is made to grow on the surface of a P<-> type single crystal substrate 1, and a polycrystalline Si layer doped with phosphorus and having higher oxidation speed than the single crystal Si layer is accumulated on a thermal oxide film 3. After B ions are implanted therein making Si nitride patterns 5 as masks to form P<+> type channel stoppers 6, the polycrystalline Si layer is oxidized selectively to oxidize the neighborhood of the exposed parts to form thick oxide films 7. When the Si nitride patterns 5, the remained polycrystalline Si layers 4' are etched next, the Si layers 4' are etched vertically and the polycrystalline Si layers 4'' are remained at the overhang parts of the thick oxide films 7. Then, thermal oxidation treatment is performed to make the polycrystalline Si layers 4'' also to oxide films together with the thick oxide films 7 forming the element isolation films, and ion implantation, etc., are performed to form the MOSIC.