Microchannel splitting and scaling for thermal balancing of liquid-cooled 3DIC

This paper introduces the notion of channel splitting to augment the scaling of microchannels for a balanced microflu-idic cooling of 3DIC. The idea is to place appropriate number of channel splitters along various sections of microchannels to reduce the convective resistances at potential hotspots. The increases in pressure drops due to channel splitting are then redistributed by scaling the channel widths to match the coolant flowrates with the power distribution, which is usually nonuniform in practice. Unlike the existing techniques, this thermal balancing method requires no extra pump or valve. Only the customization of etching masks is needed for the deposition of silicon splitters and different sizes of microchannels. Experiment on a 4-layer multicore 3DIC stack shows that the proposed microchannel design technique can effectively reduce both the maximum temperature and thermal gradient in the 3D circuit.