B-Spline X-Ray Diffraction Imaging techniques for die warpage and stress monitoring inside fully encapsulated packaged chips

Advanced More than Moore integrated circuit chip packaging is leading to the development of multiply stacked silicon die and these die are becoming ever thinner. This is leading to reliability problems. One of these is process induced die strain/warpage and there is no compelling metrology which can non-destructively measure the warpage of the die inside the packaged chips. In this paper we report on a series of techniques, which we call B-Spline X-Ray Diffraction Imaging (B-XRDI). These techniques allow for the rapid reconstruction of strain fields and lattice warpage data from x-ray diffraction images (also known as x-ray topographs) and they can provide for in situ and non-destructive analysis of stresses, strains and deformations inside packaged chip systems for single and multiple die. The technique, which uses synchrotron x-ray sources can be applied, under certain circumstances, to laboratory-based tools.