Multilayer diamond heat spreaders for electronic power devices

Single layer diamond and multilayer diamond hear spreader substrates are prepared and bonded to device wafers of silicon and gallium arsenide. Metallization schemes for the diamond surface and the backside of the device wafers are described. Bonding of the device wafers to the diamond substrates using the high thermal conductivity gold-tin eutectic solder is carried out. Characterization of the bond for the distribution of different elements in the metalization layers and the solder, for the presence of microscopic defects such as voids and cracks, for the adhesion strength and for the stability of the bond under thermal cycling is performed. The heat spreader characteristics of the substrates with single and multlayer diamond are determined using infrared imaging of the bonded device wafers and compared with that of wafers bonded to metal substrates. Modeling and analysis of the effective thermal conductivity showed that the multilayer diamond substrates are better heat spreaders and reduce the device temperature so that the life of the electronic devices is prolonged. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.