In this study, the effect of thermal cycling on defect generation, microstructure, and the RF signal integrity of blind Cu through-silicon via (TSV) were investigated. Three different thermal cycling profiles were used; each differentiated by their peak cycling temperature (100°C, 150°C, 200 °C) and the time needed to complete one cycle (cycle time). The study was performed on two Cu-TSV wafer sample types; one containing large processing-induced voids (voided sample), the other without (non-voided sample). It was found that the RF signal return loss |S11| of the Cu-TSVs degraded upon thermal cycling for both the voided and the non-voided sample types. This was attributed to the increase in the void area due to the formation of new voids, rather than the growth of pre-existing voids. On the other hand, the grain orientation and grain sizes of the Cu-TSVs were found to be unaffected by all studied thermal cycling conditions and sample types.
Citation: Microelectronics Reliability
Pub Type: Journals