Strained-Si-on-insulator (strained-SOI) MOSFETs are one of the most promising device structures for high-speed and/or low-power CMOS. In realizing strained-Si MOS'LSI, fabrication of strained-Si MOSFETs with small active area is indispensable, and thus the strain relaxation of strained-SOI mesa islands was investigated in this study. Thin strained-Si films were grown on thin relaxed SiGe-on-insulator (SGOI) structures. The isolation process was carried out by using chemical-dry-etching (CDE) to fabricate samples with small active areas. Using Raman spectroscopy, strained-Si islands on SGOT substrates were investigated. As a result, it was confirmed that the strained-Si layers grown on relaxed SiGe (x = 0.28) before and after mesa isolation, down to 5 mum in size, had almost no relaxation after rapid-thermal-annealing (RTA) at 1000 degreesC. Furthermore, it was confirmed that the nano-beam electron diffraction (NBD) measurement showed a similar tendency regarding the strain relaxation. (C) 2003 Elsevier B.V. All rights reserved.