ABSTRACT 3D X-ray microscopy (XRM) is used to image both 2-layer and multi-layer 3D stacked chips, assembled by both chip-to-chip and chip-to-wafer formats. XRM is able to generate 3D volumetric views and 2D virtual cross-sectional images of interconnects, such as through-silicon vias (TSVs) and micro bump joints in multi-layer 3D stacks. A voxel size down to 0.3 μm is obtained, sufficient to reveal details and defects in highly complicated 3D ICs. XRM offers an effective and versatile non-destructive method for process accuracy metrology, process quality inspection, and failure analysis. In addition, XRM has shown the capability to image chip stacks at different locations on a 300 mm wafer without substantial loss of resolution.
