In this work, a detailed failure analysis of the physical root cause for the increase in electrical resistance and radio-frequency (RF) transmission coefficient of through-silicon via (TSV) daisy chain was investigated. Six different failure modes were found, all of which involved the formation and propagation of voids at different interfaces, except for the formation of voids in the microstructure of the TSV and in the top metal-line. Additionally, mixed failure mode was observed at the top region of the TSV, in which voids propagating along the TSV- top metal line interface were found to interact with the voids propagating along the TSV-TaN sidewall interface. These failure modes were found to be caused or aggravated by thermal cycling and were identified as the root cause for the observed changes in the electrical and the RF characteristics of the TSVs.
Citation: IEEE Transactions on Electron Devices
Pub Type: Journals