ELASTIC STRESS-RELAXATION IN SIGE EPILAYERS ON PATTERNED SI SUBSTRATES

A two-dimensional analysis of the in-plane misfit stress and its elastic relaxation in rectangular patterned heteroepitaxial SiGe/Si multilayer structures on Si substrate is presented. Based on the model of relaxing film stress the distribution of the misfit stress versus distance from the free surface of a multilayered mesa edge is calculated. By superposition of the isolated stress fields of the mesa edges, the biaxial misfit stress distribution in a finite heteroepitaxial thin-film structure on thick substrate is obtained. The formalism developed permits the determination of the variation of misfit stress values as a function of material and size characteristics of the patterned multilayer-substrate system. An elementary application of the theoretical analysis of the biaxial state of stress existing in the structured layer system is discussed briefly.