The thickness of an interlayer between HfO2 and Si substrate was estimated by SIMS and high-resolution Rutherford backscattering spectrometry (HRBS). The model sample that changes the interlayer thickness was prepared to find an appropriate measurement condition of SIMS. The thickness of the interlayer can be estimated by the depth pro. le of Si measured by 250 eV Cs+ primary ion and incidence angle of 45 degrees. The thickness of the interlayer was also estimated by HRBS spectrum measured by 450 keV He+ and the scattering angle of 52 degrees. The thickness of the SiO2 layer estimated by SIMS and HRBS shows a good linear correlation. (C) 2008 Elsevier B.V. All rights reserved.