Low temperature FIB cross section: Application to indium micro bumps

This paper presents the interest of low temperature FIB cross section on indium micro bump. Experimental setup and results which demonstrate the interest of cooling the sample are detailed. We will explain the artefacts observed during FIB milling at room temperature. The Ga ions interact with indium to create locally an eutectic alloy, with melting point below room temperature. Inside the vacuum chamber, this eutectic alloys sublimates quickly and voids appear in the cross section. Cooling the sample with cryogenic stage enables to perform “clean” cross section without these artefacts.