Impact of Bonding Sequence on Contact Resistance in Hybrid Bonding of Via-middle TSV Wafer

This study examines the impact of the bonding sequence on the contact resistance in the hybrid bonding of a via-middle Cu though-silicon via (TSV) wafer. Hybrid bonding was performed at room temperature via a surface-activated bonding method using an ultrathin Si film. Comparative study of various bonding sequences revealed that the (a) cleaning of the target Si, via-middle TSV, and Cu electrode wafers with an Ar fast atom beam (FAB), (b) transferring of the Cu electrode wafer into another chamber during cleaning of the via-middle TSV wafer, and (c) transferring of the via-middle TSV wafer to another chamber while cleaning the Cu electrode wafer were all effective in decreasing the oxygen atoms in the bonding interface (amorphous Si layer) and reducing the contact resistances between the TSVs and Cu electrodes.