Growth of AlN thin film on Mo electrode for FBAR application

Kok Wan Tay, Long Wu, Cheng Liang Huang, Meng Shan Lin, Long Wu

Research output: Contribution to journalConference articlepeer-review

6 Citations (Scopus)


In this study a FBAR devices with four-layered composite structure is study. In this four layer structure, an AlN piezoelectric thin film is sandwiched between two metal electrodes, all of which lied on a low stress silicon nitride (Si3N4) as a support membrane in silicon. Most of the research using Pt/Ti and Al as the bottom electrode. But in this study, molybdenum was chosen as the bottom electrode because it has low acoustic attenuation, good electrical conductivity and has a good adhesive with AlN and low stress silicon nitride. Compare to Pt/Ti bi-layer electrode, the process of Mo electrode is easier. Compare to Al, there is no evidence transition region between Mo and AlN film. Which is indicative of smooth interface quality to fabrication FBAR. The high quality c-axis orientation AlN thin films with different thickness are achieved by optimum sputter deposition conditions on Mo and showed quasi-single crystal piezoelectric properties assessed using XRD, SEM, AFM and electrical characterizations are reported. The experimental results indicate that the resonance frequency is mainly determined by the thickness of the AlN film layer, which reducing the AlN thickness increase the resonant frequencies. One of the devices-considered here with AlN film thickness is 1.35μm, Mo and Al is used as bottom electrode and top electrode with the thickness of 0.1 μm and 0.18μm, respectively. The resonant frequency of the devices is 3.42GHz and the return loss is -37.95dB.

Original languageEnglish
Pages (from-to)2024-2027
Number of pages4
JournalProceedings of the IEEE Ultrasonics Symposium
Publication statusPublished - 2003 Dec 1
Event2003 IEEE Ultrasonics Symposium - Proceedings - Honolulu, HI, United States
Duration: 2003 Oct 52003 Oct 8

All Science Journal Classification (ASJC) codes

  • Acoustics and Ultrasonics


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