| 摘要 |
PROBLEM TO BE SOLVED: To facilitate control of the height of polycrystalline silicon buried in a trench. SOLUTION: After depositing a pad oxide film 4, an Si3N4 film 5 and an SiO2 film 6 on the surfaced of an SOI substrate on the side of a silicon substrate 3, a trench 7 reaching an insulating film 2 is formed. Then after forming an insulating coating 8 on the interior walls of the trench 7, polycrystalline silicon 9 is deposited in such a way that the trench is embedded. Then excessive polycrystalline silicon 9 deposited on the SiO2 film is etched back for exposing the SiO2 film 6. After that, the SiO2 film 6 and the polycrystalline silicon 9 in the trench 7 are polished and removed at the same time, using the Si3N4 film 5 as stopper by CMP. In this case, since the height of the polycrystalline silicon 9 is determined by variations in thickness of the pad oxide film 4 and the Si3N4 film 5, control of the height of the polycrystalline silicon 9 is facilitated.
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