Ion-Induced Bending with Applications for High-Resolution Electron Imaging of Nanometer-Sized Samples

In this work, a “stand-out” approach is proposed for the preparation of nanoscale specimens for high-resolution imaging such as transmission electron microscopy (TEM) and atom probe tomography (APT). By controlling the FIB (focused ion beam) irradiation parameters, including the ion dose, beam direction, and beam energy, the proposed approach is capable of lifting nano- or microscale specimens in situ to a desired height, driven by internal stresses. The “stand-out” specimens can be further shaped by FIB milling into needle-shaped or micropad geometries for various nanocharacterization techniques. A detailed investigation of the underlying ion-induced bending (IIB) mechanisms has been performed through both experiments and theoretical analysis of the control of molybdenum cantilevers at both ambient and cryogenic temperatures. Additional materials including copper, silicon, and steel have also been trialed, and all the results suggest IIB to be a universal phenomenon. Application of IIB has been demonstrated for site-specific TEM imaging of gold nanoparticles. Furthermore, the proposed approach also provides unique site-specific sample preparation for APT. It is expected that this approach will streamline nanoscale specimen preparation for high-resolution imaging and facilitate the development of fully automated solutions.