Effect of Substrate Constraint on Stress-Induced Deformation Mechanism of Tungsten Thin Film

Abstract

The deformation process of sputtered tungsten films were investigated according to the morphological characteristics and residual stress analysis. Results show that there are four characteristics depending on the substrates and stress state. For thin films on polyimide, the localized plastic deformation is mediated by the alignment of grain boundaries in the case of tension or line bulges in the case of compression. It results from both in-plane and out-of-plane grain rotation. For thin films on silicon substrate, wedge cracks in the case of tension or regular hillocks in the case of compression become the typical morphology. From this point of view, the deformation behaviors of films depended on the substrate constraint and residual stress states.