Novel application of FIB lift-out and ultramicrotomy for advanced package failure analysis

The semiconductor industry is pushing the technology envelope of integrated circuit packaging: aggressively shrinking the geometry and introducing cost competitive materials and processing technology. The need for more powerful package FA techniques also increases, especially in the area of higher resolution imaging and material characterization. The field emission SEM no longer has the spatial resolution needed to image thin film interfaces found in new generation packages. Hence, TEM was called into action, especially in analyzing thin interfaces such as the solder joint interface and copper via interface. The sample preparation technique for package FA is the gating factor for TEM analysis. The conventional TEM preparation techniques such as wedge and dimpling are not compatible with the advanced packaging materials. The FIB cross-section technique is applicable but typically takes a long time to prepare by trimming to the region of interest (ROI) and then polishing to a 20 μm sliver. There is a great need for effective TEM sample preparation techniques to make TEM available to package failure analysis. FIB lift-out and ultramicrotomy techniques have been improvised to meet this need.