sWe have developed an X-ray microbeam with a narrow energy bandwidth and a small angular divergence in both horizontal and vertical directions normal to the X-rays. Utilizing synchrotron radiation from the so-called third-generation ring like SPring-8 (Super Photon ring, 8 GeV), the X-ray microbeam possesses sufficient photons even after beam size compression. Using the X-ray microbeam, we have demonstrated to measure very local and minute lattice strain in silicon materials after some wafer preparation processes or device fabrication processes. Local strain in an Si crystal around the SiO2/Si film edge and also strain at silicon-on-insulator (Sol) interface have been measured as ;sample materials. (C) 2002 Elsevier Science B.V. All rights reserved.