OBSERVATION OF SMALL DEFECTS IN SILICON CRYSTAL BY DIFFUSE-X-RAY SCATTERING

Two kinds of diffuse x-ray scattering due to defects were observed from a very perfect silicon single crystal. One forms the shape of a cigar, elongated along the [111] direction, and the other is a disk, which is broad and perpendicular to the [111] direction. The cigar-shaped diffuse scattering is asymmetric around the 111 relp with respect to the Bragg peak. Fourier transforms reveal two types of defects; platelike defects [200 Å (φ) ×30 Å (t)] of vacancy type and needlelike defects (400 A (l)). The platelike defect dimensions are in fairly good agreement with those of B-swirl defects observed by de Kock et al. The platelike defects also have a close correlation with the crystal pulling direction. They are contained predominantly in the (111) planes for a crystal grown along the [111] direction.