3DIR metrology system includes confocal IR laser scanning microscopy for measuring post-bond parameters of 3-D stacked integrated circuits. Is a nondestructive, through-silicon metrology technique that monitors a variety of post-bond parameters, including overlay alignment accuracy, bonding interface thickness variations, and bonding interface quality including pre- and post-bond defect inspection and review. Measures alignment points at selected die of bonded wafers, stores images and data, and summarizes results. Correlation of overlay alignment offset data to electrical yield provide an early indication of bonded wafer yield. Software tools display data in the form of vector maps. Confocal capability permits thin optical sectioning in Z and construction of 3-D images of the bonded wafer interface and structures. 3-D reconstructions can be used to create sections in the XZ plane. Bonded wafers are automatically scanned at low magnification. Images are stitched together to form a single wafer image. When the overlay vector map is superimposed on the scanned wafer image, correlation of many of the failed overlay measurement points to bonded interface anomalies can be seen. Stitched image can be viewed and zoomed. Any site can be revisited and the image reviewed or rescanned and imaged using the IR microscope with objective magnifications up to 90x and 0.14µm pixel resolution.

Olympus Integrated Technologies, www.olympus-ita.com 

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