Wafer-level microfluidic cooling interconnects for GSI

We present a novel CMOS compatible approach to fabricate on-chip microfluidic cooling channels using a spin-on sacrificial polymer material at wafer level. Deep trenches (>100 /spl mu/m) etched into the backside of an IC wafer were successfully filled up by a single spin coating step with a high viscosity sacrificial polymer. A porous overcoat material allows the decomposition of the polymer to form enclosed microchannels. Through chip holes and polymer pipes are used as the inlet/outlet interconnects. Different channel array designs were described and the pressure drop was estimated for a heat flux of 100 W/cm/sup 2/ with DI water flow rate. The resulting cooling scheme offers a simple and compact solution to transfer cooling liquid directly into a GSI chip and is fully compatible with flip-chip packaging.