Lawrence Berkeley National Laboratory

Mechanical behaviors and especially the strain-rate responses at the nanoscales of low melting temperature metals, such as indium, have not been studied much. Indium is one of the key materials or alloy components in advanced microelectronics and the nanotechnology industry, and understanding their mechanical behaviors at nanoscales becomes increasingly important to ensure lifetime reliability of their applications in novel nanoscale devices or advanced systems (for packaging at the nanoscales, for instance). Synchrotron X-ray microdiffraction has been utilized to examine defect structures of nanoscale materials as well as their strain-rate responses. Nanoscale or advanced microelectronics packaging, for instance, require acceptable levels of drop test results. For these low melting temperature materials especially, this technique offers a unique advantage as conventional methods such as transmission electron microscope and EBSD will expose the structure to high-energy electron beams that may significantly alter the microstructure and defect structure during analysis. Using this approach, we found interesting differences in term of X-ray peak broadening after deformation with different strain rates, which could indicate differences in plasticity mechanisms in the submicron pillars of indium, which could be important for their applications in nanodevices. Understanding these differences could lead to better control of mechanical properties of low melting temperature metals at the nanoscales and, thus, have important implications for nanodevice reliability.