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Minimizing surface damage during FIB specimen preparation is an important factor for high quality analytical results, especially in the case of TEM membrane and EBSD sample preparation. For conventional Ga + FIB milling, techniques using reduced accelerating voltages for final polishing to minimize sample damage are commonly used [1]. With newer ion species available for FIB milling, namely Xe + , the ion-solid interaction will be slightly different from Ga+, but the same low ion energy strategies can be applied for minimizing ion milling damage.Previous studies on single crystal silicon with a conventional Ga + FIB show ~22 nm amorphous sidewall damage when milled with an energy of 30 keV and less sidewall damage with lower energies . On the same substrate, modeling indicates that milling with heavier ions will produce less sidewall damage than with a lighter ion of the same energy [2]. Hence, less sidewall damage should be achievable when FIB milling with Xe + (54) in comparison to Ga + (31). In this study, the sidewall amorphization damage on single crystal silicon after Xe + FIB milling and also Ga+ FIB milling has been measured for comparison.Cross-sections of a blanket silicon wafer were prepared using both a Vion Plasma FIB (Xe + ) and a Helios DualBeam at 30 keV. Specimens were polished with energies of 5, and 2 keV using incident angles of 88°, 86°, 84° respectively. After sputter coating the surface with iridium as an initial protection layer, conventional in-situ liftout TEM samples of the milled cross-sections were prepared using a Helios NanoLab 450HP DualBeam equipped with an EasyLift nanomanipulator. Amorphous silicon damage was analyzed by HRTEM on a Tecnai Osiris TEM operating at 200 keV.Figs. 1a, 1b and 1c show HRTEM images of the amorphous sidewall damage from Ga+ FIB milling with 30 keV, 5 keV and 2 keV, respectively. Figs. 2a, 2b and 2c show HRTEM images of the amorphous sidewall damage from Xe+ FIB milling with 30 keV, 5 keV and 2 keV, respectively. As expected, the experimental results follow SRIM calculations and predictions from fundamental ion-solid interactions [3]. The Xe+ sidewall amorphous damage decreases dramatically as a function of energy and is smaller than 30 keV Ga+ FIB results by as much as ~ 40%.

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