- [Show abstract] [Hide abstract] ABSTRACT: 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.
- [Show abstract] [Hide abstract] ABSTRACT: A gold-free, fully Cu metallized InGaP/GaAs HBT using platinum as the diffusion barrier has been successfully fabricated. The HBT uses Pd/Ge for ntype, Pt/Ti/Pt/Cu for p+type ohmic contacts, and Ti/Pt/Cu for interconnect metals with platinum as the diffusion barrier. The Ti/Pt/Cu structure was stable up to 350 annealing as judged from the data of XRD and sheet resistance. Current accelerated stress test was conducted on the device with current density JC=140 kA/cm2 for 24 hours, the current gain showed no degradation. The devices were also thermally annealed at 250 for 24 hours and showed little changes. We have successfully demonstrated that Aufree, fully Cu metallized HBT can be achieved by using Pt as the diffusion barrier and Pd/Ge and Pt/Ti/Pt/Cu as the ohmic contacts.