Measurement of Elastic Strains in Crystal Surfaces by X-Ray Diffraction Topography

Abstract

AbstractThe use of X-ray topographic techniques for studying elastic strains in crystals deformed at their surfaces is becoming widespread, especially in the field of silicon semiconductor devices. Although the broad features of the phenomenological processes involved in producing the strain patterns on the X-ray micrographs are understood, little attention has been devoted to evaluating the detailed nature or range of the strain fields in the crystal. In this paper, an clastic model is proposed for cases in which a region of crystal surface is uniformly deformed over a thin layer. With this model, the associated strain field in the surrounding crystal, which is readily computed from elasticity theory, may be characterized by a single parameter. The model is in accord with observed strain patterns on topographs of abraded diamond surfaces and silicon surfaces onto which a strip of metal film has been evaporated. From the spatial range of the diffraction contrast, an estimate of the parameter characterizing the strain field may be made.