GaN MMICs on a diamond heat spreader with through-substrate vias fabricated by deep dry etching process

GaN monolithic microwave integrated circuits (MMICs) on a diamond heat spreader were successfully fabricated and demonstrated. The diamond was bonded to the back-side surface of the GaN on SiC devices by atomic diffusion bonding. In addition, through-substrate vias (TSVs) of diamond and SiC were fabricated using a deep dry etching process. This study marks the first development of GaN MMIC on diamond with TSVs fabricated using diamond etching. From the large-signal measurement of GaN MMICs at 7 GHz, the output power of the device with diamond during continuous wave operation was improved by 11% compared to that of without diamond.