X-RAY STUDY OF DEFECT DEPTH DISTRIBUTION IN SILICON-WAFERS AFTER HEAT-TREATMENT

A surface defect-free denuded zone in silicon wafers has been studied by x-ray double-crystal diffractometry. On the basis of the dynamical theory of x-ray diffraction on crystals with microdefects, it has been demonstrated that the x-ray reflection curve of a crystal with a denuded zone measured in the Bragg geometry (reflection case) depends strongly on the denuded zone thickness, while that in the Laue geometry (transmission case) is practically not affected by the zone. Thus, it is possible to determine the denuded zone thickness nondestructively from the ratio of the tails of the reflection curves measured in both geometries. The thickness values obtained experimentally by this approach have been compared with those from chemical etch patterns of cleavage wafer cross sections, and a good agreement has been achieved.