Nanoscale Deformation and Strain Analysis by AFM–DIC Technique

Abstract

Digital image correlation (DIC) technique with the aid of scanning probe microscopes has become a very promising tool for deformation analysis of micro- and nanoscale components. The scanner drift of the atomic force microscope (AFM) is a great disadvantage to the application of digital image correlation to micro/nanoscale deformation measurements. This chapter has addressed the image distortion induced by the scanner drifts and developed a method to reconstruct AFM images for the successful use of AFM image correlation. The proposed AFM–DIC method is to generate a corrected image from two correlated AFM images scanned at the angle of 0^° and 90^°, respectively. The method has been validated by two simple AFM–DIC experiments. The application of this AFM–DIC technique was demonstrated by the deformation measurement on the micro-interconnection in a micro thermoelectric cooler. AFM images of the scan region of interest were obtained separately when the microelectronic device was before and after operating at both its cooling and heating stages. The AFM images were then used to obtain the in-plane deformation fields in the observed region of the micro-assembly. AFM image correlation is performed for nanoscale deformation analysis using the authors’ AFM–DIC program. The results show that the observed region was subjected to cyclic strains when the device worked between its cooling and heating stages and cyclic strain in the vertical direction was found to be significant deformation mode. The thermally induced deformation behavior of the micro-assembly device was modeled by finite element analysis (FEA). Both thermal-electric analysis and thermal stress analysis were conducted on a 3D finite element model of the device. It is shown that the experimental results were able to validate the finite element analysis results.