Incremental FIB-DIC Ring-Core Methods for the Residual Stress Measurement of Bilayer Thin Films

Background: The thin film coating and the microsystem device’s reliability can be strongly affected by residual stress; thus, accurate residual stress measurement in thin films is important. Objective: This study conducted residual stress measurement to provide a viable semi-destructive method for evaluating the residual stress of bilayer thin film. Methods: A model for analyzing residual stress in elastically isotropic bilayer thin film was developed by combining the usage of Focused Ion Beam—Digital Image Correlation (FIB-DIC) with finite element (FE) modeling calculated calibration coefficients. The relaxation stress of thin film can be revealed with corresponding milling depth. Results: Residual stress results of ZrN/Zr bilayer thin films were measured with the implementation of FE analysis calibration coefficients and the resulting strain release. A comparison between the collected results with other studies was performed to prove the practicality and applicability of this method. Conclusions: This study showed that the residual stress of each layer of the bilayer thin film corresponded to its deposition conditions. Therefore, the residual stress of the bilayer thin film could be measured using the proposed Incremental FIB-DIC ring-core method.