CMOS Compatible TSV Process with Post-CMOS Thermomigration Refilling of Au-Si Eutectic Alloy

A CMOS-compatible through-silicon-via (TSV) process is reported for the first time, in which a via-first silicon TSV is fabricated to obtain small-footprint structures with high-quality insulating layers. Following CMOS processes, the silicon in TSV is replaced by an Au-Si eutectic alloy with thermomigration of Au to achieve low serial resistance. Because the process temperature is higher than the melting point of the eutectic alloy, it takes less than 50 min to replace the 50-μm-thick silicon TSV with the eutectic alloy. With this method, the serial resistances of the via-first silicon TSVs decrease drastically to approximately 1.1 Ω.