Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer

• Published in: Scientific reports 2015-03, Vol.5 (1), p.9510-9510, Article 9510
• Main Authors: Chen, Guohao, Zhao, Xinru, Wang, Xiaozhi, Jin, Hao, Li, Shijian, Dong, Shurong, Flewitt, A. J., Milne, W. I., Luo, J. K.
• Format: Article
• Language: English
• Subjects: 639/166/987; 639/301/1005; 639/925/927; Acoustics; Fabrication; Humanities and Social Sciences; Integration; Microelectromechanical systems; multidisciplinary; Polymers; Science; Silicon
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep09510

The film bulk acoustic resonator (FBAR) is a widely-used MEMS device which can be used as a filter, or as a gravimetric sensor for biochemical or physical sensing. Current device architectures require the use of an acoustic mirror or a freestanding membrane and are fabricated as discrete components. A new architecture is demonstrated which permits fabrication and integration of FBARs on arbitrary substrates. Wave confinement is achieved by fabricating the resonator on a polyimide support layer. Results show when the polymer thickness is greater than a critical value, d, the FBARs have similar performance to devices using alternative architectures. For ZnO FBARs operating at 1.3–2.2 GHz, d is ~9 μm and the devices have a Q -factor of 470, comparable to 493 for the membrane architecture devices. The polymer support makes the resonators insensitive to the underlying substrate. Yields over 95% have been achieved on roughened silicon, copper and glass.