A chip-scale cooling scheme with integrated heat sink and thermal-fluidic I/O interconnects

We demonstrate a prototype chip-scale microfluidic cooling scheme. CMOS compatible processes allow the monolithic integration of the microchannel heat sink into the backside of a Si chip at low temperature (<= 260 degrees C). At the front side of a chip, fine pitch area-array solder bumps are fabricated by electroplating for high-density electrical I/O interconnection, while a peripheral array of micro polymer pipes are fabricated as thermal-fluidic I/O interconnects. The resulting "microfluidic flip chip" can be bonded onto a liquid-cooled board substrate using conventional flip-chip assembly processes. The cooling liquid can, therefore, be transferred into a Si chip directly from the board-level manifolds to alleviate the thermal interface issues.