Resonance Characteristic Improvement of ZnO-Based FBAR Devices Fabricated on Thermally Annealed Bragg Reflectors

  • Yim, Mun-Hyuk (Communication and Electronics Lab (CEL), Information and Communications University(ICU)) ;
  • Kim, Dong-Hyun (CEL, IC) ;
  • Linh Mai (CEL, IC) ;
  • Giwan Yoon (ICU)
  • Published : 2003.12.01

Abstract

In this paper, we present the thermal annealing effects of the W/$SiO_2$ multi-layer reflectors in ZnO-based FBAR devices with cobalt (Co) electrodes in comparison with those with aluminum (Al) electrodes. Various thermal annealing conditions have been implemented on the W/$SiO_2$ multi-layer reflectors formed on p-type (100) silicon substrates. The resonance characteristics could be significantly improved due to the thermal annealing and were observed to depend strongly on the annealing conditions applied to the reflectors. Particularly, the FBAR devices with the W/$SiO_2$ multi- layer reflectors annealed at $400^{\circ}C$/30min have shown superior resonance characteristics in terms of return loss and quality-factor (Q-factor). In addition, the use of Co electrodes has resulted in further improvement of the resonance characteristics as compared with the Al electrodes. As a result, the combined use of both the thermal annealing and Co electrodes seems very useful to more effectively improve the resonance characteristics of the FBAR devices with the W/$SiO_2$ multi-layer reflectors.

Keywords

FBAR;Bragg reflector;Thermal annealing;Cobalt electrode;Return loss;and Q-factor

References

  1. W. E. Newell, 'Face-mounted piezoelectric resonators', Proc. IEEE, vol. 53, pp. 575-58, 1965 https://doi.org/10.1109/PROC.1965.3925
  2. R. C. Ruby, P. Bradley, Y. Oshmyansky, A. Chien, 'Thin Film Bulk Wave Acoustic Resonators (FBAR) for Wireless Applications', IEEE Ultrasonics Symp., pp. 813-821, 2001
  3. M.-A. Dubois and P. Muralt, V.Plessky, 'BAW resonators based on aluminium nitride thin films' IEEE Ultrasonics Symp., pp. 907-910, 1999
  4. K. M. Lakin, J. Belsick, J. F. McDonald, and K. T. McCarron, 'Improved Bulk Wave Resonator Coupling Coefficient For Wide Bandwidth Filters', IEEE Ultrasonics Symp., pp.827-831, 2001
  5. K. M. Lakin, K. T. McCarron and R. E. Rose, 'Solidly Mounted Resonators and Filters', IEEE Ultrasonics Symp., pp. 905-908, 1995
  6. S. L. Pinkett and W. D. Hunt, 'Temperature Characteristics of ZnO-based Thin Film Bulk Acoustic Wave Resonators,' Proc. IEEE Ultrasonics Symp., pp. 823-826, 2001
  7. R. C. Ruby, P. Bradley, J. D. Larson III and Y. Oshmyansky, 'PCS 1900MHz duplexer using thin film bulk acoustic resonators (FBARs)', lEE Electron. Lett., vol. 35, pp. 794-795, 1999 https://doi.org/10.1049/el:19990559
  8. K. M. Lakin, G. R. Kline and K. T. McCarron, 'High-Q Microwave Acoustic Resonators and Filters,' IEEE Trans. Microwave Theory & Tech. vol. 41, pp. 2139-2146, 1993 https://doi.org/10.1109/22.260698
  9. S.-H. Park, B.-C. Seo, H.-D. Park and G. Yoon, 'Film Bulk Acoustic Resonator Fabrication for Radio Frequency Filter Applications', Jpn. J. Appl. Phys. vol.39, pp. 4115-4119, https://doi.org/10.1143/JJAP.39.4115
  10. K. M. Lakin, G. R. Kline and K. T. McCarron, 'Development of Miniature Filters for Wireless Applications', IEEE Trans. Microwave Theory & Tech., vol. 43, pp. 2933-2939, 1995 https://doi.org/10.1109/22.475658
  11. K. M. Lakin, K. T. McCarron, J. F. McDonald, 'Temperature Compensated Bulk Acoustic Thin Film Resonators,' Proc. IEEE Ultrasonics Symp., pp. 855-858, 2000