X-ray crystal truncation rod scattering analysis of reactive ion etched silicon

Abstract

We have investigated lattice damage in reactive ion etched silicon by using x-ray crystal truncation rod (CTR) scattering. The x-ray intensity associated with the rod in the reciprocal space depends on the etching-induced lattice distortion. To estimate the magnitude of the lattice distortion, we analyzed the obtained data with a kinematic x-ray diffraction model on the assumption that the lattice distortion decays exponentially with the depth. We found that the lattice distortion extends to a depth of about 9 nm. In addition, we propose a method for quantitatively evaluating lattice damage based on our analysis. This method allows us to compare lattice damage among samples etched under different conditions. This study indicates that x-ray CTR experiments provide a useful means of characterizing lattice distortions near processed surfaces.