| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for forming inter-element isolating insulation film by which the occurrence of the projections on a silicon substrate and acute- angle portions on a silicon oxide film formed through thermal oxidation can be avoided by making the thickness of the silicon oxide film uniform. SOLUTION: First, a silicon oxide film 2 and a silicon nitride film 3, both of which have openings above an inter-element isolation region are successively formed on the surface of a P-type silicon substrate 1. Then a trench 5 is formed by etching the substrate 1 to a prescribed depth by using the silicon nitride film 3 as a mask. Thereafter, an ion-implanted region 6 is formed by implanting silicon ions into the exposed portion of the substrate 1 on the side and bottoms faces of the trench 5. Consequently, the substrate 1 in the ion-implanted region 6 becomes amorphous, and the plane orientation property of the substrate 1 in the amorphous portion can be eliminated. Finally, a silicon oxide film is formed by thermally oxidizing the surface of the substrate 1.
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