X-ray Moire topography on SIMOX structures

Moire fringes are observed on X-ray diffraction topographs of silicon on insulator structures produced by different SIMOX (separation by implantation of oxygen) processes. The parameters that can be extracted from a diffraction Moire experiment are discussed. A Moire experiment is sensitive to the relative strain between the two parts of a bicrystal system. The sign of the relative strain and its components perpendicular to the sample surface cannot be determined from the geometry of the Moire fringes. The influence of sample curvature on Moire fringes is considered. Different deformation models are discussed to interpret the experimental findings. It is found that a triclinic relative deformation explains the observed symmetries between Moire topographs from different reflections, the spacings of the Moire fringes and their angles to a reference direction. Both the dilational and the shear components of the relative strain tensor are found to be in the order of 10(-7). Significant differences in relative strain are observed on SIMOX samples produced by different processes.