| 摘要 |
PROBLEM TO BE SOLVED: To reduce a step on a surface of a substrate between a thick portion and a thin portion of a buried oxide film. SOLUTION: A high-temperature oxidation heat treatment is carried out while a first mask 40 is formed at the surface of a thin oxide film 20, the first mask 40 is removed while a thick oxide film is formed in an area where the thin oxide film 20 is not present, and a second heat treatment is carried out again in an oxide atmosphere. A second thermal oxidation film is formed even at the surface of the thin oxide film 20, and the same conditions are selected for interfaces between the first thermal oxide film and second thermal oxidation films, and the substrate to form a flat substrate having no step on the surface after the first thermal oxide film and second oxide film are removed. COPYRIGHT: (C)2007,JPO&INPIT
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