Copper-airbridged low-noise GaAs PHEMT with Ti/WNx/Ti diffusion barrier for high-frequency applications

Cheng Shih Lee, Yi Chung Lien, Edward Yi Chang, Huang Choung Chang, Szu Houng Chen, Ching Ting Lee, Li Hsin Chu, Shang Wen Chang, Yen Chang Hsieh

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


A GaAs pseudomorphic HEMT (PHEMT) with Cu-metallized interconnects was successfully developed. Sputtered WNx was used as the diffusion barrier and Ti was used as the adhesion layer to improve the adhesion between WNx/Cu interface in the thin-metal structure. After copper metallization, the PHEMTs were passivated with silicon nitride to avoid copper oxidation. The Cu-airbridged PHEMT showed the saturation IDS was 250 mA/mm and the gmwas 456 mS/mm. The Ti adhesion layer plays a significant role on the gm and Vp uniformity of the Cu-metallized PHEMTs. The GaAs PHEMTs with TI/WNx/Ti/Cu multilayer have better noise figure and associated gain than those of the devices without the Ti adhesion layer. The fabricated Cu-metallized GaAs PHEMT with Ti/WNx/Ti/Cu multilayer has a noise figure of 0.76 dB and an associated gain of 8.8 dB at 16 GHz. The cutoff frequency (fT) is 70 GHz when biased at VDS = 1.5 V. These results show that the Ti/WNx/Ti multilayer can serve as a good diffusion barrier for Cu metallization process of airbridge interconnects on GaAs lownoise PHEMTs.

Original languageEnglish
Pages (from-to)1753-1758
Number of pages6
JournalIEEE Transactions on Electron Devices
Issue number8
Publication statusPublished - 2006 Aug

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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