Silicon carbide enhanced thermomigration

The widespread acceptance of thermomigration technology to produce through-chip interconnects has been impaired by (i) a random walk of the Si-Al liquid eutectic inclusion as it traverses the wafer, and (ii) a ?surface barrier? which allows thermomigration of only relatively large inclusions. In this paper it is shown that these problems can be mitigated by thermomigrating at high wafer temperatures and with large temperature gradients through the wafer. It has been possible to achieve these high wafer temperatures and large gradients using a bank of infrared lamps and a bilaminar structure of silicon carbide powder compressed onto the top of a silicon wafer. This increases the delivery of energy to the wafer and reduces the random walk of the liquid inclusion. Further, the high wafer temperatures and enhanced temperature gradients created with this bilaminar silicon carbide structure allow relatively small, square aluminum pads (35 pm on a side) to thermomigrate through a l&nil-thick silicon wafer.