How to achieve artefact-free FIB milling on polyimide packages

High speed FIB cross-sectioning of polyimide material was traditionally very difficult because of artifacts created by FIB on the cross section plane. Therefore we propose a simple method, which retains the high speed of the FIB process, but significantly improves the quality of the cross section plane. The method involves a hard mask positioned close to the intended place of the cross section using a precise manipulator. This then enables highly accurate and site-specific FIB cross sectioning. Cross sections can be made very quickly and with the excellent quality in comparison to standard procedures based on gas-assisted deposition of a protection layer.