Fabrication and thermal evaluation of silicon on diamond wafers

Silicon on diamond (SOD) is proposed as a superior alternative to conventional silicon on insulator (SOI) technology for silicon-based electronics. In this paper, we present a novel SOD structure in which the active Si layer is in direct contact with a thick, highly oriented diamond (HOD) layer that is directly attached to a heat sink. In contrast to the earlier work,(1,2) the diamond film is relatively thick (similar to 70 mu m), free standing, and close to single crystalline, thus possessing much greater thermal conductivity and no limitation of the Si backing wafer. Two different fabrication schemes are investigated: (1) direct growth, where the Si-device layer makes contact with the nucleation side of the diamond layer; and (2) wafer fusion, where the Si device layer makes a direct contact with the diamond growth surface. Thermal evaluation was performed using metallic microheaters. These studies clearly showed more than one order of magnitude better thermal management properties of diamond with respect to Si and SOI.