Innovative Low damage Silicon Nitride Passivation of 100nm In0.45AlAs/In0.4GaAs Metamorphic HEMTs with Remote ICPCVD

In this paper, a novel low-damage silicon nitride passivation for 100 nm In0.45AlAs/In0.4GaAs MHEMTs has been developed using remote ICPCVD. The silicon nitride deposited by ICPCVD showed higher quality, higher density, and lower hydrogen concentration than those of silicon nitride deposited by PECVD. In particular, we successfully minimized the plasma damage by separating the silicon nitride deposition region remotely from ICP generation region, typically with distance of 34 cm. The silicon nitride passivation with remote ICPCVD has been successfully demonstrated on GaAs MHEMTs with minimized damage. The passivated devices showed considerable improvement in DC characteristics and also exhibited excellent RF characteristics (fT of 200 GHz).The devices with remote ICPCVD passivation of 50 nm silicon nitride exhibited 22 % improvement (535 mS/mm to 654 mS/mm) of a maximum extrinsic transconductance and 20 % improvement (551 mA/mm to 662 mA/mm) of a maximum saturation drain current compared to those of unpassivated ones, respectively. The results achieved in this work demonstrate that remote ICPCVD is a suitable candidate for the next-generation MHEMT passivation technique.