Evaluation of Thin-Film Residual Stress Using Nano-Indentation Combined with an Atomic Force Microscope

Abstract

Thin-film stress changes the shape of nanoindentation loading curve. The change in the indentation load is treated as the effect of the residual stress on the indenting deformation. A residual-stress-induced normal load is defined as a multiple of contact area and plastic deformation-sensitive deviator stress component extracted from the equi-biaxial thin-film stress. A final equation for the residual stress is derived from the residual-stress-induced normal load by considering an integration along a depth-controlled stress-relaxation route. This proposed model is applied to the analyses of the nanoindentation curves for diamond-like carbon thin films. The residual stresses from the nanoindentation analyses were consistent with the values obtained by the conventional curvature method.