| 摘要 |
A method for manufacturing a semiconductor substrate comprises: forming a silicon on insulator (SOI) area and an element isolation film on a semiconductor base; forming a first semiconductor layer on the semiconductor base in the SOI structure area; forming a second semiconductor layer having an etching selection ratio smaller than an etching selection ratio of the first semiconductor layer on the first semiconductor layer; removing a part of the second semiconductor layer and a part of the first semiconductor layer in the SOI structure area so as to form a recess exposing the semiconductor base and supporting a support; forming a support forming layer on the semiconductor base so as to bury the recess and cover the second semiconductor layer; etching an area excluding the recess, the element area, and an area covering the element isolation film so as to form the support and an opening face exposing a part of end parts of the first semiconductor layer and the second semiconductor layer, the opening face being positioned under the support; removing the first semiconductor- layer and the second semiconductor layer that are disposed at a border between the element isolation film and the SOI structure area and in a vicinity of the border; etching the first semiconductor layer through the opening face so as to form a cavity between the second semiconductor layer and the semiconductor base; forming a buried insulation layer in the cavity; forming an insulation film above the second semiconductor layer; and planarizing above the second semiconductor layer so as to remove a part of the support.
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