**4.5.2 Dynamic profile measurement**

A region of interest (ROI, see in figure 21) on the device was tested to study the dynamic profile change at a certain stimulating signal. The dynamic profiles were shown in figure 22.

Fig. 21. Choice of ROI

MEMS Characterization Based on Optical Measuring Methods 107

The stimulating voltage frequency was 23 kHz, the amplitude was 10 V, and the offset voltage was 20 V. The motion can be classified into three kinds of cases: 1) one reference plane; 2) the first phase of the device movement; 3) the reference mirror in the interferometer. Here the second case is chosen. From figure 22, it can be shown that the movement of the device is like sinusoidal waveform and there is a distort phenomena in the

This chapter has discussed several optical methods to realize MEMS characterization, including dimensional (static) and moving (dynamic) properties analysis. Two measuring systems are introduced. NMM based system combines nano-measuring machine with high positioning accuracy and microscopic interferometers. PSI, WLI, WLPSI are applied in the system to measure the dimensional parameters. MMA combines video microscopy, stroboscopic illumination and special algorithms. It employs two kinds of nondestructive methods - computer microvision for in-plane motion measurement and phase shifting interferometry for out-of-plane motion measurement. This system can test the three-

The authors gratefully acknowledge the support of National Natural Science Fund (91023022), International Cooperation Project of MOST (2008DFA71610) and Natural Science

Bosseboeuf, A., Gilles, J. P., Danaie, K. et al.(1999). A versatile microscopic profilometer-

Burdess, J. S., Harris, A. J., Wood, D. et al. (1997). A system for the dynamic characterization of microstructures. *J. Microelectromechan. Syst.*, Vol.6, No.4, pp. 322-328 Fu, X., Liu, Y. Q., Hu, X. D. et al. (2004). Micro Laser Doppler Vibrometer Technology for

Guo, T., Chang, H., Chen, J.P. et al. (2009). Micro-motion Analyzer used for Dynamic MEMS Characterization, *Optics and Lasers in Engineering*, Vol. 47, No.3-4, pp. 512-517 Guo, T., Wu, Z. C., Ma, L. et al.(2010). Dynamic MEMS characterization system using

Guo, T., Ma, L., Zhao, J. et al. (2011). A nanomeasuring machine based white light tilt

Guo, T., Ma, L., Chen, J.P. et al.(2011). MEMS surface characterization based on white light phase shifting interferometry, *Optical Engineering*, Vol. 50, No.5, pp. 053606

*and Lasers in Engineering*, Vol. 49, No.9-10, pp.1124-1130

vibrometer for static and dynamic characterization of micromechanical devices.

MEMS Dynamic Measurement. *J of Optoelectronics·Laser*, Vol.15, No.11, pp.1357-

differential phase measurement method, *Proceedings of SPIE*, Vol. 7544, pp.

scanning interferometer for large scale optical array structure measurement, *Optics* 

dimensional motions and dynamic profiles with nanometer accuracy.

process of the movement.

**6. Acknowledgment** 

**7. References** 

1360

75444W

Fund of Tianjin (09JCYBJC05300).

*Proc. SPIE*, Vol. 3825, pp. 123-133

**5. Conclusion** 

(a) Profile at the second phase

(b) Profile at the ninth phase

The stimulating voltage frequency was 23 kHz, the amplitude was 10 V, and the offset voltage was 20 V. The motion can be classified into three kinds of cases: 1) one reference plane; 2) the first phase of the device movement; 3) the reference mirror in the interferometer. Here the second case is chosen. From figure 22, it can be shown that the movement of the device is like sinusoidal waveform and there is a distort phenomena in the process of the movement.
