Residual stresses in the elastoplastic multilayer thin film structures: The cases of Si/Al bilayer and Si/Al/SiO2 trilayer structures

Abstract

A theoretical model was developed to predict the thermal residual stresses within the elastoplastic multilayer thin film structures. The plastic deformation of one of the films was considered. Special analyses were made on the bilayer structures, i.e., a film overlaid on a substrate, as they are more of practical interest. Closed-form solutions were derived to estimate the residual stresses in the films and curvature of the multilayer film structure, and the relationship between the temperature difference and the thickness of the plastic zone. The cases of Si/Al bilayer and Si/Al/SiO2 multilayer structures were studied to illustrate the implementation of this model. In these structures, Al film was assumed to be plastically deformed. Results showed that, for both structures, there was a linear relationship existing between the thickness of the plastic zone in Al film and the temperature difference. SiO2 layer deposited on the aluminum film had an obvious influence on the critical temperature at which Al film started to be plastically deformed.