Development of TLP joining technique for fabrication of vertical interconnections in TSV stacking

The present work is focused on the development of reliable, cost-effective and environmentally friendly metallic interconnection systems suitable for TSV (through silicon vias) technology, which can be considered as replacements for direct Cu/Cu bonding or high-temperature soldering. It is shown that through the judicious selection of the Sn-interlayer between the metallization constituents, Transient Liquid-Phase (TLP) bonding can be achieved at relatively low temperature (below 300°C), and the resulting joints are capable of service at elevated temperatures. Selection of the suitable materials was dictated by the outcome of the experimental study reaction phenomena in the Cu-Ni/Sn system. The newly developed metallization materials can be produced by electrochemical deposition, which makes the suggest joining method compatible with the existing packaging technology. The potential for the proposed materials and techniques are very appealing for use not only for vertical interconnects in the TSV stacking, but also as an alternative to the high-Lead soldering (especially in die-attach operations).