Study of Stresses and Plasticity in Through-Silicon Via Structures for 3D Interconnects by X-Ray Micro-Beam Diffraction

X-ray microbeam diffraction measurements were conducted for copper (Cu) through-silicon via (TSV) structures. This technique has the unique capability to measure stress and deformation in Cu and in silicon with submicron resolution, which enables direct observation of the local plasticity in Cu and the deformation induced by thermal stresses in TSV structures. Grain growth in Cu vias was found to play an important role in controlling the stress relaxation during thermal cycling and, thus, the residual stress and plasticity in the TSV structure. The implication of the local plasticity on TSV reliability is discussed based on the results from this study and finite element analysis.