Integration of a temporary carrier in a TSV process flow

Three-dimensional (3-D) wafer stacking technologies offer new possibilities in terms of device architecture and miniaturization. To stack wafers, reliable through-silicon vias (TSVs) and interconnections must be processed into ultrathin wafers, and such processing is made possible by new methods for wafer handling. Of the different wafer-level bonding techniques, temporary wafer bonding adhesives can offer a variety of properties sufficient for withstanding the TSV processes: flow properties, mechanical strength, thermal stability, chemical resistance, and easy debonding and cleaning processes. This paper demonstrates that, contrary to tapes and waxes currently used for temporary bonding, a new removable high-temperature adhesive meets all the requirements named above for reliable TSV processing on 8-inch active wafers. We will first describe formation of TSVs with aspect ratios of 1:1 and 2:1 into thinned wafers.