Integration of cooling devices in silicon technology

Abstract

A novel cooling device fully built in silicon technology is presented. The new concept developed in this work consists in micromachining the bottom side of the circuit wafer in order to embed heat sinking microchannels directly in the silicon material, as near as possible to the heat generation source. These microchannels are then sealed, by a direct wafer bonding procedure, with another silicon wafer where microchannels and inlet-outlet nozzles are micromachined too. Such a configuration presents the advantages to provide a significant reduction of the cooler overall dimensions, to reduce the number of involved materials and to be obtainable by a VLSI compatible technology. The first prototype has been designed to meet severe power dissipation constraints representative of high-power electronic devices (i.e. IGBT). Using an adequate thermal simulator with appropriate approximations, the optimum dimensions of the micro heat sink were found out. The realization procedure was then carried out in a clean room environment. First experimental characterization results obtained from the earlier prototypes has demonstrated that the thermal properties of this silicon-based cooling device are satisfactory and can be reasonably compared to those of commercially available copper micro heat sinking components.