Lithium Ion Microscopy: Surface Sensitive Imaging with Elemental Contrast and without Charging Effects

We present a new nanoscale imaging technique based on detecting backscattered ions from a lithium focused ion beam (FIB). Scanning ion microscopes are of general interest as they provide image contrast that differs from scanning electron microscopes (SEM), as has been demonstrated with the traditional gallium FIB and the helium ion microscope [1]. Like helium, the low mass of lithium makes it ideal for imaging applications where sample sputtering must be minimized. Our lithium ion microscope has the additional advantage of operating at beam energies much lower than the gallium or helium microscopes, giving excellent surface sensitivity at high resolution. Imaging with backscattered ions is of particular interest as they provide elemental contrast and are relatively insensitive to charging effects. We present images and measurements showing the current capabilities of our instrument and demonstrate an example application.