| 摘要 |
PROBLEM TO BE SOLVED: To prevent a gate insulating film of a MOS type element from deteriorating due to bimetal effect characteristics of an SOI substrate. SOLUTION: A groove 35 is formed surrounding an element-forming region of the SOI substrate 11 and a thick oxide film 17a is formed on a side wall and then embedded under a polycrystalline silicon 17b, to form a trench separation layer 17. The thick oxide film 17a is different in the coefficient of thermal expansion for silicon semiconductor layers 11c and 11d, so that adverse influence on an element can be reduced, even by subsequent heat treatment. A gate insulating film 20 of a MOS capacitor 13 can be prevented from deterioration in film quality and formation in the same yield as formation on a bulk silicon substrate is enabled. COPYRIGHT: (C)2003,JPO
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