Copper Airbridged Low Noise GaAs PHEMT with WNx as the Diffusion Barrier

L.H. Chu, H.C. Chang, Edward Y. Chang, Y.C. Lien

Department of Materials Science and Eng8ineering, National Chiao Tung University, Hsinchu,Taiwan, R.O.C.

Phone: +886-3-5712121 ext52969; FAX: +886-3-5745497; E-mail:


Keywords: copper metallization, LNA, PHEMT



The silicon nitride passivated copper-metallized airbridges had been successfully integrated on the low noise PHEMT (Pseudomorphic High Electron Mobility Transistor) using WNx as the diffusion barrier between copper and the conventional gold based electrodes.  40 A PecVD (Plasma Enhanced Chemical Vapor Deposition) silicon nitride was used for copper airbridge passivation to avoid the copper oxidation.  The 0.25x160mm2 copper-airbridged PHEMT device shows a transconductance of 480mS/mm and a noise figure of 0.76 dB with an associated gain of 10.4 dB at 12 GHz.  The decide performance is comparable to devices with gold-metallized airbridges.  The performance did not degrade after annealing at 250oC for 20 hours.  This study shows promising results for copper metallization of GaAs devices in the future.


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