X-ray μ-Laue diffraction analysis of Cu through-silicon vias: A two-dimensional and three-dimensional study

Abstract

Here, white X-ray μ-beam Laue diffraction is developed and applied to investigate elastic strain distributions in three-dimensional (3D) materials, more specifically, for the study of strain in Cu 10-μm diameter-80-μm deep through-silicon vias (TSVs). Two different approaches have been applied: (i) two-dimensional μ-Laue scanning and (ii) μ-beam Laue tomography. 2D μ-Laue scans provided the maps of the deviatoric strain tensor integrated along the via length over an array of TSVs in a 100-μm thick sample prepared by Focused Ion Beam. The μ-beam Laue tomography analysis enabled to obtain the 3D grain and elemental distribution of both Cu and Si. The position, size (about 3-μm), shape, and orientation of Cu grains were obtained. Radial profiles of the equivalent deviatoric strain around the TSVs have been derived through both approaches. The results from both methods are compared and discussed.