| 摘要 |
PURPOSE:To suppress the elongation of a bird's beak simply without increasing processes to a large extent, by oxidizing a semiconductor substrate with an oxidation resisting film as a mask, removing the oxide film, forming an oxidizing film on the outer edge (side surface) of the oxidation resisting film, oxidizing the semiconductor substrate again, and forming a selective oxide film. CONSTITUTION:A bird's beak 8 is elongated to the side of an element forming region from the side of a selective oxide film 7 at the time of selective oxidation. The elongation is suppressed with polycrystalline silicon film 6, which is formed on the side surface of a silicon nitride film 3 and has oxidizing property. Namely, the length l of the bird's beak 8 can be made short. The integration density of ICs, LSIs and the like can be improved. The processes, which are newly required, are only as follows: the first oxidizing process, by which the silicon nitride film 3 is selectively etched and thereafter the surface of the semiconductor is oxidized; a process for etching an oxide film 4; a process, by which the polycrystalline silicon film 6 is formed by vapor phase deposition; and a process, by which anisotropic etching of he polycrystalline silicon film 6 is performed and a part other than a part positioned at the side surface of the silicon nitride film 3 is removed.
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