| 摘要 |
PROBLEM TO BE SOLVED: To relieve stress concentration to an element substrate by providing the slope of specific orientation at the side-wall upper part of a groove-shaped region, and by setting the groove-shaped region other than the side-wall upper part nearly vertical to the main surface of the element substrate. SOLUTION: The surface of 100} surface of an element substrate 101 made of silicon is thermally oxidized, and a thermal oxide film 102 is formed. The thermal oxide film 102 is subjected to patterning, and the surface of the element substrate 101 is etched. For the etching of Si, anisotropy exists regarding orientation. The etching rate of the 100} surface is set to at least 2 times larger than that of a 111} surface, so that the 111} surface with a slow etching rate is exposed. Then, the thermal oxide film 102 is used as a mask for forming trench structure by anisotropy etching. An oxide film is generated on the surface of a trench, and the trench is buried. Etchback is made, and the internal part of the trench is buried with the oxide film, thus greatly relieving the concentration of angle stress in thermal oxidation.
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