Local Stress Analysis by XRD Single Crystal Method and Kossel Diffraction Applied to a Flip Chip Structure

Abstract

X-Ray Diffraction (XRD) is a very efficient experimental tool for strain/stress analysis at different scales, which makes possible to carry out some mappings in complex 3D flip chip assemblies. First, with single crystal method, both the chip and the substrate have been analyzed at the same positions, considering a 1mm2 step, in order to quantify the level of stress inside. Then Kossel microdiffraction has been tested for local stress analysis with a spatial resolution of a few micrometers. This method is set up in a Scanning Electron Microscope (SEM) which allows to select precisely the analyzed area, the probe volume is about 1ìm3 and the strain resolution is about 10-4. The work here proposed describes the means employed to perform the different XRD analyses on single crystals used in 3D integration structures, the experimental results are then compared to numerical Finite Elements simulations and are discussed.