A high-resolution X-ray topographical technique for thin flexible crystal plates

A new technique for high-resolution X-ray diffraction topography is described, which is specially applicable to the examination of thin crystal slices of large area in symmetric transmission. The crystal plate is slightly curved so that the whole area can selectively diffract a single wavelength from an X-ray beam divergent from a distant point source. For the case of symmetric transmission, image contrast is identical to that obtained from the conventional Lang technique. Resolution equivalent to that of the Lang technique is obtained in a small fraction of the exposure time. The method is restricted to materials in which the defect distribution is not strongly dependent on macroscopic strain. The method is illustrated by application to silicon crystals used in semiconductor device manufacture. Process-induced curvature can to some extent be compensated.