JPS55107243A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To prevent the induction of a disconnection by etching and relieving the difference in level of an oxidized film between the surfaces of an element region and an isolating region in a semiconductor substrate.

CONSTITUTION: An n⁺ buried layer 12 followed by an n epitaxial layer 13 are piled on a p^- Si substrate 11, and the layers are covered by a SiO₂ film 14. Masks 16a, 16b of Si₃N₄ film are applied to the layer above so as to eatch the film 14 and n layer 13 successively and form a concave portion 17. Next if a separated oxidized layer 18 is made through wet oxidization at 1000°C, 9 air pressure and for 60min., thin oxidized films 20a, 20b are produced on the rugged portion 19 and the masks. Excepting the Si₃N₄ film 16a and the SiO₂ layer 14 under that 16a, the remaining one is exposed to a POCl₃ gas at a high temperature in order to form a PSG layer on the film 18, then an n⁺ layer 21, using the diffusion of P. The film 20b is changed into PSG at the same time. Next the film 20b is etched to the extent beyond its thickness so that the PSG on the isolated layer 18 as well as the rugged portion are removed. The films 16b and 14 are removed, thence after SiO₂ film 20c, p⁺ and n⁺ layers are formed, Al wiring 24W26 is completed. This constitution prevent the occurrence of a disconnection considerably.

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