Advanced microelectronics packaging, driven by the multiple benefits of system performance, power, size, and cost, has now entered the three-dimensional (3-D) era. According to the International Technology Roadmap for Semiconductors 2012 [1], the interconnect pitch size is predicted to be 4?16 ?m at the global interconnect level by the year 2018. Silicon die incorporated with through-silicon-via (TSV) technology [2] can be stacked using solder microbumps as high-density interconnects [3]. However, solder microbump technology faces many challenges because of the intermetallic compound growth and an underfill requirement as the bump size reduces [4]. Meanwhile, the temperature of the soldering process is more than 260 ?C, which can result in high thermal stress in the devices and impact the thermal budget of the processing, particularly for the multitechnology node-stacking processes [5]. Therefore, developing interconnect methods, which can provide ultrafine-pitch capability and low-temperature process for 3-D systems, attracts continuous attention from industry [6].