In order to understand the properties of point defects in Si, it is important to clarify temperature dependence of Si intrinsic self-diffusion coefficient over a wide temperature range. In this work, we used highly isotopically enriched Si-30 epi-layers as a diffusion source to bulk and epilayers Si and evaluated self-diffusion Si-30 epi-layers were grown on each CZ-Si substrate and non-doped epi-layer grown on CZ-Si substrate using low pressure CVD with (SiH4)-Si-30. Diffusion was performed in resistance furnaces under pure Ar (99.9%) atmosphere at temperature between 867 and 1300degreesC. After annealing, the concentrations of the respective Si isotopes were measured with SIMS. Diffusion coefficients of 30Si (called Si self-diffusivity, D-SD) were determined using numerical fitting process with 30Si SIMS profiles. We found no major differences in self-diffusivity between in bulk Si and epi-layers Si. It was shown that within 867-1300degreesC range, D-SD can be described by an Arrhenius equation with one single activation enthalpy, D-SD = 14 exp (-4.37 eV/kT). The present result is in good agreement with that of Bracht et al. (C) 2004 Elsevier B.V. All rights reserved.