Focused ion-beam milling for field-ion specimen preparation:: preliminary investigations

Focused ion-beam milling has been used to fabricate field-ion specimens from a pure metal, a metal alloy, an intermetallic alloy and a multilayer film device. Gallium ions of 30 keV energy with beam currents of 4–1000 pA were used for micromachining of the field-ion specimens and for simultaneous imaging. The final sharpening for pure metal and intermetallic specimens and the entire sharpening procedure for a metal alloy sample and a multilayer film structure containing 100 repetitions of a Cu2nm/Co2nm bilayer were accomplished using the focused ion-beam system. Atom probe analysis indicated that although the amount of gallium implantation was minimal in a Cu–15% Co alloy, significant damage occurred in Cu/Co multilayer film structures prepared by focused ion-beam milling. Focused ion-beam techniques provide an alternative to traditional electropolishing methods for field-ion specimen preparation and atom probe analysis provides quantitative information of implanted gallium and ion-induced damage in such samples.