Use of WNx as diffusion barrier for copper airbridged low noise GaAs PHEMT

A low noise pseudomorphic high electron mobility transistor (PHEMT) with copper airbridges using sputtered WNx as the diffusion barrier has been developed. Both the material system and the copper airbridged PHEMT with WNx as the diffusion barrier did not decay even after thermal annealing at 250°C for 20 h. The results show that the copper airbridges with WNx diffusion barrier can be used as the interconnects for low noise GaAs PHEMTs.