Process Technologies for GaN High Voltage Devices

The vertical structure of the power device has advantages such as small chip size, easy wiring, and high breakdown voltage. Furthermore, wideband gap semiconductors have the greatest feature of low on-resistance. GaN is a material having the ability to fully exhibit these properties and in recent years development of GaN vertical devices has been accelerated. For example, GaN vertical devices with over lkV breakdown voltage have been reported recently
^1-5)
. Moreover, over 3kV pn diodes were also reported
^6,7)
. Therefore, ability of GaN for high voltage devices has been proven. Next issues are developments of fabrication process technologies which make devices stable operation. In this paper, we will report recent advances in process technology for GaN vertical devices.