| 摘要 |
PURPOSE:To prevent the generation of the lowering in the breakdown strength of a gate oxide film, and to improve yield on manufacture and reliability by leaving a polycrystalline silicon film having a selective etching rate with a second insulating film in the foundation of the oxidation-resistant second insulat ing film used when a field oxide film is formed onto a semiconductor substrate. CONSTITUTION:A first insulating film 11, a polycrystalline silicon film 12 and an oxidation-resistant second insulating film 13 are deposited onto the surface of a semiconductor substrate 10, and the second insulating film 13 is etched selectively to shape a mask for oxidation. A field oxide film 15 is formed onto the substrate through selective oxidation by using the mask. Since the polycrystalline silicon film 12 is left onto the silicon oxide film 11 on field oxidation, there is no possibility in which a white ribbon is generated near the interface between the silicon oxide film 11 and the field oxide film 15. Accordingly, a gate oxide film 16 can be shaped in a clean state, thus preventing the lowering of gate breakdown strength.
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