| 摘要 |
PROBLEM TO BE SOLVED: To manufacture easily an SOI substrate adapted favorably to a large scale integration and so having on both its surfaces circuit-element forming regions as to suppress the substrate from becoming large-sized. SOLUTION: After subjecting respectively both the surfaces of a semiconductor substrate 11 to ion implantation to form buried insulation layers 12, 13 based on the implanting conditions for securing their desired depths and film thicknesses, the intermediate is subjected to a heat treatment in a nitrogen atmosphere. Then, on both surfaces of the substrate 11, there are formed respectively element forming regions (silicon layers) 14, 15 separated by the buried insulation layers 12, 13 and for forming therein circuit elements.
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