Reseach On The Cooling Performance Of The On-chip Hotspot Based On 3D Microchannel

The development of semiconductor technology integration leads to shrinking feature size, increasing transistor density, faster circuit speeds which makes the power dissipations and heat fluxes of chip become even higher. In recent years nanoscale electronics technologies and increasing performance demands have resulted in greater nonuniformity of on-chip power dissipation, creating localized hot spots, often with high heat flux. The conventional air cooling has very limited capability for dealing with high flux on-chip hot spots, so innovative cooling techniques with the ability to cool on-chip hot spots effectively, are being investigated.Liquid cooling using liquid with high thermal conductivity, high specific heat and low viscosity as coolants is an efficient cooling method, so in this paper we use liquid cooling method to cool the on-chip hotspots. There are two kinds of chips which are planar chip and three-dimensional(3D) chip stacks are investigated in this paper.For 2D chip, mainly study the cooling performance for hot spot of the parallel and the cross-linked micro heat sink and compare the cooling performance of the two micro heat sinks. The effects of inlet velocity, the width and positions of cross-linked channels, positions and the heat fluxes on local hotspots are studied. All investigated heat sinks have better cooling performance for hot spot when the only one hotspot is placed in the upstream region or upstream hotspot is subjected to a higher heat flux than the downstream one. The cross-linked heat sink has the best cooling performance when the width of the cross-linked channels is 0.5 millimeter and that the cross-linked channels are located at the front of the hotspot and are adjacent to the hot spot. Compared to the parallel micro heat sink, the cross-linked micro heat sink has better cooling performance for hot spot and temperature distribution of which is more uniform. Moreover, the cooling performance for hot spot of the multilayer micro heat sinks with thinner cross channels above the hot spot is aslo studied. The effects of inlet velocity, the layer of the micro heat sink and the heat flux of hot spot are studied. The more the layer of the micro heat sink is, the better the cooling performance of the micro heat sink for hotspot is and the more nonuniform the temperature distribution is. When the layer increases to a certain value, the cooling performance of micro heat sink is no longer affected by the layer. The bigger the heat flux of on-chip hot spot is, the worse the cooling performance of micro heat sink is, the more ununiform of temperature distribution is.For 3D chip stacks, use interlayer cooling method to study the effects of inlet velocity and the heat flux of hot spots. With the increasement of the heat flux of the hotspot, the temperature of per layer hotspot increases dramatically and the underlying hot spot has a maximum temperature rise while the top hotspot has a minimum temperature rise.