Gallium Phase Formation in Cu and Other FCC Metals During Near-Normal Incidence Ga-FIB Milling and Techniques to Avoid this Phenomenon

Abstract

Focused ion beam (FIB) circuit modification of devices with Cu-based interconnect is well known to be problematic Measurements of FIB sputter rates on single crystal Cu specimens This difference in sputter rate poses severe difficulties in uniformly cutting Cu interconnect, but at first glance produces only an annoyance in terms of a requirement of extra milling time to produce TEM specimens by FIB. However, the reasons for this differential sputter rate conceal more alarming issues that need to be taken into account by those producing TEM specimens, particularly as these effects do not seem to be limited only to Cu, but have been observed at Fibics to appear to occur in certain Au and Ni based systems.