X-Ray Micro-Beam Diffraction Determination of Full Stress Tensors in Cu TSVs
Chukwudi A. Okoro, Lyle E. Levine, Oleg A. Kirillov, Yaw S. Obeng, Ruqing Xu, Jonathan Z. Tischler, Wenjun Liu, Klaus Hummler
We report the first non-destructive, depth resolved determination of the full stress tensor in Cu through-silicon vias (TSVs), using synchrotron based micro-beam X-ray diffraction. Two adjacent Cu TSVs were studied; one deliberately capped with SiO2, the other without (uncapped). Both Cu TSVs were found to be in a state of tensile hydrostatic stress that fluctuated considerably with depth. The average hydrostatic stress across the capped and the uncapped Cu TSVs was found to be (99 MPa ± 13 MPa) and (118 MPa ± 18 MPa), respectively. This apparent disparity between the mean hydrostatic stresses is attributed to local differences in their microstructure, and not to the differences in capping.
Proceeding of IEEE Electronic Components and Technology Conference (ECTC)