Residual stress measurement in thin films at sub-micron scale using Focused Ion Beam milling and imaging

Residual stress evaluation in thin films at the sub-micron scale was achieved in the present study using a semi-destructive trench-cutting (ring-core) method. Focused Ion Beam was employed to introduce the strain relief by milling the slots around an “island” and also to record the images for strain change evaluation by digital image correlation analysis of micrographs. Finite element simulation was employed to predict the curves for strain relief as a function of milling depth, and compared with the experimental measurements, showing good agreement. An empirical mathematical description of the curves was proposed that allows efficient data analysis for residual stress evaluation.