Surface activated bonding of SiC/diamond for thermal management of high-output power GaN HEMTs

GaN-based high-electron-mobility transistors (HEMTs) fabricated on SiC substrates were successfully bonded to single-crystal diamond heat spreader by a surface activated bonding method with a thin titanium (Ti) cover layer. A thin Ti layer on the diamond improved the bonding strength of the SiC/diamond interface since the formation of an amorphous layer on the diamond surface was suppressed. This SiC/diamond bonding process was applied to high-output power InAlGaN/GaN HEMTs on diamond heat spreaders. The structure with the diamond successfully reduced the thermal resistance of the devices and enabled their high-power operation.