Plastic Deformation in Central Regions of Epitaxial Silicon Slices

Abstract

Central yielding, as well as peripheral slip, was observed in curved epitaxial silicon slices produced in the laboratory. The central plastic deformation is the result of compressive stresses set up by the entrapment of a hot central region within a colder annular zone. A stress analysis was performed which explains the occurrence and relative intensities of slip in the two regions by reference to the distortion energy densities throughout the slice. A model of the centrally localized plastic deformation in {111} slices was presented in which the 〈110〉 slip vectors inclined to the {111} surface are activated and produce relief of the central compressive stresses by vertical movements of pyramidal sections of the crystal.