A non-destructive and non-contact observational method was developed in order to detect defects in Si crystals. By using this method, cross-sectional images of the defects in a crystal could be obtained. The method was effective in revealing near-surface defects, precipitates within the denuded zone of intrinsic gettering-treated wafers, twins or slip-plane defects in epitaxial layers, and defects on the layer boundaries of SOI wafers. The present results were compared with the results which were obtained by using conventional laser scattering tomography. Inconsistencies were noted in some cases.

K.Moriya, H.Wada, K.Hirai: Journal of Crystal Growth, 1993, 128[1-4], 304-9