| 摘要 |
PURPOSE:To prevent the intrusion of the bird's beak of an SiO2 layer into the active region of a transistor, by forming a trench, in which a polycrystalline semiconductor layer is buried, in a semiconductor substrate, and selectively oxidizing the upper part of the polycrystalline semiconductor layer. CONSTITUTION:A polycrystalline Si layer 7 is buried in a trench 6. Thereafter, the upper part of the trench and the surface of a substrate are etched away. A cap oxide film of the trench 6 is formed. The upper part of the trench 6 and the recess in the surface of the substrate are positioned so that the bird's beak of an SiO2 layer 11 formed at this time is not intruded into the active region of a transistor. For example, LOCOS oxidation is performed, and the SiO2 layer 11 having a thickness of 1mum is formed. At this time, the cap oxide film of the trench and a field oxide film are simultaneously formed. An SiO2 layer 12 is grown by a CVD method. Photoresist 13 is applied. Etch back is performed and the surface is flattened. Since the bird's beak of the SiO2 layer 11 hardly intrudes into the active region, a dead space due to the bird's beak can be saved, and the high integration density of the semiconductor integrated circuit can be implemented.
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