TSV diagnostics by X-ray microscopy

TSV (Through Silicon Via) is one of the key elements for building 3D integrated silicon devices with high bandwidth interconnections. In this paper, we propose a diagnostic method for TSV defects by using X-ray projection microscopy. By optimizing the image contrast of the X-ray projection micrographs in reference to its X-ray intensity histogram, we could obtain the small defect features in TSVs fast and non-destructively. Comparison between this X-ray observation and the destructive cross sectional observation agreed very well. We also extended the implementation of this X-ray microscope diagnostic method to 8-in. full wafer observation. We investigated the wafers with copper-filled TSVs with 80 μm and 20 μm diameters, and confirmed the feasibility of this method for an in-line process monitoring.