Kinetics of strain relaxation in semiconductor films grown on borosilicate glass-bonded substrates

Abstract

Changes in the strain relaxation of semiconductor films due to growth on a thin epitaxial template bonded via a borosilicate glass to a mechanical handle wafer have been observed. Akinetic analysis of the mechanical decoupling between the film/template heterostructure and the handle wafer is developed in order to estimate and evaluate the contribution of glass viscous deformation to the observed strain relaxation. The thickness and elastic constants of the template and film, the thickness and viscosity of the bonding media, and the lateral dimension of the bonded structure are included in this model. Based on this model, the viscous flow of the glass is unlikely to have played a role in previous observations of changes in film strain relaxation due to growth on glass-bonded substrates. The calculations are used in conjunction with simple expressions for the temperature and composition dependence of borosilicate glass viscosity to result in design guidelines for substrate structures and annealing schedules in which the viscous flow of a borosilicate glass will contribute to the strain relaxation of a lattice-mismatched film.