Nondestructive, in Situ Mapping of Die Surface Displacements in Encapsulated IC Chip Packages Using X-Ray Diffraction Imaging Techniques

We have recently shown that x-ray synchrotron-based B-Spline X-Ray Diffraction Imaging (B-XRDI), and laboratory-based X-Ray Diffraction (XRD) techniques, can be used to non-destructively and in situ evaluate die warpage and strain inside fully encapsulated chip packages. In this paper, we show that both synchrotron-based X-Ray Diffraction Imaging (XRDI) and laboratory-based XRD can be used to usefully evaluate die surface shape f(x, y) and vertical displacements (Δz) induced in commercially packaged chips at room temperature and at elevated temperatures consistent with typical package processing temperatures, e.g. 25 - 200 oC. We describe a suite of algorithms, which have been developed to generate full die Δz and warpage maps for the encapsulated die using the rocking curve (RC) data collected by laboratory-based XRD and these are correlated with section topography (ST) data acquired via synchrotron-based white beam XRDI. Confidence in the efficacy of the techniques was established through the correlation of the laboratory-based Δz vertical displacement maps with optical interferometry analysis for a series of golden samples of known and predetermined warpage.