Si self-diffusivity using isotopically pure 30Si epitaxial layers

Abstract

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 30Si epi-layers as a diffusion source to bulk and epi-layers Si and evaluated self-diffusion 30Si epi-layers were grown on each CZ–Si substrate and non-doped epi-layer grown on CZ–Si substrate using low pressure CVD with 30SiH 4. Diffusion was performed in resistance furnaces under pure Ar (99.9%) atmosphere at temperature between 867 and 1300 °C. 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 867–1300 °C 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.