Residual stress release during nanoindentation-induced delamination

This study proposed a new method to determine residual stresses through delamination induced by cyclic indentation loads. For the silicon oxide film indented by a cube corner indenter, sudden increase of indentation depth, together with a particular two-stage behavior, suggests that delamination occurred. After that, contact stiffness divided by depth was found to drop from an initial value to a steady value, which is independent of load conditions and is related to the release of residual stress. Similar phenomena were found in diamond-like carbon films tested by the continuous stiffness measurements using a Berkovich indenter, and the proposed method was applied to obtain the residual stresses of the as-deposited and annealed films. The dimensionless parameters related to the indenter geometry were determined to be 2.61±0.03 and 5.63±0.06 for a cube corner and a Berkovich indenter, respectively. The later one showed good agreement compared to the reported value from the simulation analysis.