軟X線と非対称回折を使った薄膜結晶およびバルク結晶の評価(<特集>Growth and Characterization of Silicon Crystals)

抄録

A soft X-ray diffraction technique using asymmetric diffraction is developed as a method of evaluating both thin crystalline films and bulk crystals. It is confirmed that an asymmetric diffraction technique using soft X-ray beams (TiKα_1 and CrKα_1) enables the sampling of only a surface layer within 0.1〜0.3μm contrary to conventional techniques. The improved technique is successfully applied to SOS wafers. As a result, the half-width is found to correlate with both a fault density and a Hall mobility. At the same time, the X-ray anomalous transmission phenomenon in "Bragg case" diffraction is applied in bulk crystal evaluation. Anomalously transmitted peak intensity in the Bragg case is 2〜3 times that of anomalously transmitted intensity in conventional Laue case diffraction at the same μ_0t value. Therefore, high sensitivity to lattice defects is obtained. The technique has been tentatively applied in the evaluation of micro-defects both in Si and GaP crystals.