Analytic modeling, optimization, and realization of cooling devices in silicon technology

A novel cooling device fully built in silicon technology is presented. The new concept developed in this work consists in micromachining the bottom si de of the circuit wafer in order to embed heat sinking microchannels direct ly into the silicon material. These microchannels are then sealed, by a dir ect wafer bonding procedure, with another silicon wafer where microchannels and inlet-outlet nozzles are micromachined too. A cooling fluid (water) is then forced through the array of channel to convey heat outside the chip. Such a configuration presents the advantages to provide a significant reduc tion of the cooler overall dimensions, to reduce the number of the involved materials and to be compatible with integrated circuits fabrication proced ures. In this study analytical tools were used in order to get a global evaluatio n of all the thermal resistances characteristic of such devices, Using thes e adequate analytic models with appropriate approximations, a global optimi zation procedure was then applied and led to the definition of he optimum d imensions of the silicon micro heat sink. The realization procedure was the n carried out in a clean room environment, First experimental characterizat ion results obtained from the earlier prototypes demonstrated that the ther mal properties of this silicon-based cooling device are satisfactory and ca n be reasonably compared to those of commercially available copper micro he at sinking components.