Using Digital Image Correlation on SEM Images of Strain Field after Ion Beam Milling for the Residual Stress Measurement of Thin Films

Abstract

The residual stress of thin films during the deposition process can cause the components to have unpredictable deformation and damage, which could affect the service life and reliability of the microsystems. Developing an accurate and reliable method for measuring the residual stress of thin films at the micrometer and nanometer scale is a great challenge. To analyze the residual stress regarding factors such as the mechanical anisotropy and preferred orientation of the materials, information related to the in-depth lattice strain function is required when calculating the depth profiles of the residual strain. For depth-resolved measurements of residual stress, it is strategically advantageous to develop a measurement procedure that is microstructurally independent. Here, by performing an incremental focused ion beam (FIB) ring-core drilling experiment with various depth steps, the digital image correlation (DIC) of the specimen images was obtained. The feasibility of DIC to FIB images was evaluated after the translation test, and an appropriate procedure for reliable results was established. Furthermore, the condition of the film in the function of residual stress was assessed and compared to elucidate the applicability of this technology.

An Estimation of Local Residual Stresses in Amorphous and Crystallized Trivalent Chromium Coatings

“…This method is based on the combined use of a focused ion beam (FIB), scanning electron microscope (SEM) imaging, and digital image correlation (DIC). Estimating residual stresses are obtained from the relaxation-induced displacement fields of the analyzed area (determined by DIC) as a result of FIB milling of a given groove geometry [28]. A finite element model (FEM) can also be used to improve the understanding of the results.…”

Mechanical Properties and Residual Stress Measurement of TiN/Ti Duplex Coating Using HiPIMS TiN on Cold Spray Ti

“…In particular, no techniques are currently available that can produce a sub-micron lateral and depth resolution in an automated and robust manner. In this research, it was assumed that these limitations could be surmounted through the use of a combination of FIB milling, SEM imaging, DIC analysis, and finite element modeling [15][16][17][18][19]. Thus, the study provides important information on residual stress measurement of the thin film through PVD, sputter, and HiPIMS.…”

“…The objective of this study was to investigate the mechanical properties and residual stress of the combination of protective hard coatings (TiN/Ti duplex coating) deposited through HiPIMS on top of the three different cold-sprayed Ti grade 4 coatings deposited on the conventional Ti grade 12 substrates [20]. The residual stress of HiPIMS TiN film measured by THE FIB-DIC method [15] on top of three different cold spray Ti coatings was able to predict the influence of the substrate effects on the mechanical behavior of TiN/Ti duplex coating using HiPIMS TiN on cold-sprayed Ti coating. This study would benefit the industry since cold spraying is cost-saving, sustainable, and has low environmental impacts.…”

Advances in Multi-Scale Mechanical Characterization of Materials with Optical Methods

“…The determination of residual stress with optical methods (i.e., ESPI and digital image correlation) is discussed in Refs. [ 7 , 8 ]. In particular, Sasaki et al [ 7 ] evaluated changes in elastic modulus caused by residual stresses.…”

“…Chen et al [ 8 ] used digital image correlation (DIC) to measure residual stress in Ag and ZrN thin films. DIC served to analyze the SEM images obtained through incremental ring-core drilling performed with a focused ion beam (FIB) at various depth steps.…”