Optimum Design Method of Sacrificial Layer Release Window for Aperture Cavity Type FBAR

Abstract:

Sacrificial layer release is the key process step of cavity structure formation of Film Bulk Acoustic Resonator (FBAR), the degree of sacrificial layer release directly determines how good or bad the resonance characteristic of FBAR is. The Constant Diffusion Coefficient (CDC) model numerical iteration of sacrificial layers etching process was simulated with MATLAB, and the etching process was also simulated with Silvaco. According to the simulation results, put forward optimum design of release window. The resonance simulations of FBAR with/without release window have been done by FEA software. The simulation results show that the aperture cavity type FBAR, i.e. the cavity type FBAR with release holes, still has distinct resonant characteristic, but the frequency of impedance zero point and impedance pole of the novel type FBAR are all drifted to higher frequency, and the effective electromechanical coupling coefficient and the quality factor are all reduced.

• Periodical: Applied Mechanics and Materials (Volumes 719-720)
• Pages: 157-167
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.719-720.157
• Online since: January 2015
• Authors: Yang Gao*, Yi He, Bin Zhou, Wan Jing He
• Keywords: Air Cavity, Film Bulk Acoustic Resonator (FBAR), Optimization, Resonance Frequency, Sacrificial Layer Release, Simulation, Wet Etching

References

[1] Jiang Song-tao, Wu Meng-qiang, Wu Yong, et al., Materials, Devices Design and Applications of Thin Film Bulk Acoustic Wave Filters, Materials Review, 20(11), 21-24, (2006).

[2] S. Taniguchi, T. Yokoyama, M. Iwaki, et al., An Air-Gap Type FBAR Filter Fabricated Using a Thin Sacrificed Layer on a Flat Substrate, Proc. 2007 IEEE Ultrasonics Symposium, 600-603, (2007).

DOI: 10.1109/ultsym.2007.156

[3] L. Shao, M. Palaniapan. Effect of etch holes on quality factor of bulk-mode micromechanical resonators, Electronics Letters, 44(15), 938-939, (2008).

DOI: 10.1049/el:20081320

[4] Shi Sha-li, Chen Da-peng, Ding De-yong, Study of Sacrificial Layer Etch and Release Technology in MEMS Device, Microfabrication Technology, (6), 58-62, (2006).

[5] Wu Changju, Study of Sacrificial Layer Etching of Micro/Nano Structure and its Model, Hangzhou: Zhejiang University, (2006).

[6] W. P. Eaton, J. H. Smith, R. L. Jarecki, Release-Etch Modeling for Complex Surface Micromachined Structures, Proc. SPIE Micromachining and Microfabrication Process Technology II, 2879, 80-93, (1996).

DOI: 10.1117/12.251224

[7] Wang Sheng-fu, Xu Yue, Zheng Sheng-ling, et al., Development of 1. 8 GHz Film Bulk Acoustic Resonator Based on AlN, Semiconductor Technology, 37(2), 146-149, (2012).

[8] Jin Hao. A number of problems of film bulk acoustic resonator (FBAR) in research, Hangzhou: Zhejiang University, (2006).