| 摘要 |
PROBLEM TO BE SOLVED: To form the trench isolation by filling trenches with an insulation film for isolation by a HDP-CVD method, without being influenced by pattern widths in active and element isolation regions. SOLUTION: This method includes following steps. With a protective insulation film 3 as an etching mask, isolation trenches 5a, 5b, 5c are formed in a semiconductor substrate 1 through anisotropic dry etching. Then, an insulation film 6 for isolation is formed by a high-density plasma CVD method. After forming a sacrificial protective film 7, formed of a fluid material on the insulation film 6 for isolation, heat treatment is conducted to make the sacrificial protective film 7 flow, thereby planarizing the surface of the sacrificial protective film. Thereafter, the sacrificial protective film 7 and insulation film 6 for isolation are etched back to remove part of the sacrificial protective film 7 and insulation film 6 for isolation on the protective insulation film 3, and then at least a remaining part of the insulation film 6x left over on the protective insulation film 7 is polished and removed by a CMP method, leaving the insulation film for isolation only in the isolation trenches, and thereby forming element isolation insulation films 6a, 6b, 6c.
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