Measurement of Step Height Using White Light Spectral Interferometry

Abstract:

The development of micro-nanomanufacturing technology leads to higher requirement for measurement technology, which gives birth to the ultra-precision measurement technology. As a kind of low coherence interferometry technology, spectral interferometry has been proposed. In this paper, the theory and system of white light spectral interferometry were described in detail, and the measurement principle of micro-structure was analyzed. The spectral interference signal was recorded and the phase information was retrieved from it by using five-step phase shifting algorithm, which includes the phase change on reflection from the stucture. So the optical path difference (OPD) can be obtained, which represents the height information. Three methods including slope method, single wavelength method and least square method were discussed based on the theory deduction and the experimental analysis. A step height standard was measured and the results show that this method has a good accuracy.

• Periodical: Key Engineering Materials (Volume 625)
• Pages: 326-331
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.625.326
• Online since: August 2014
• Authors: Tong Guo*, Lian Feng Ni, Long Ma, Jin Ping Chen, Xing Fu, Xiao Tang Hu
• Keywords: Microstructure, Phase Shifting, Spectral Interference, White Light

References

[1] Gao F., Leach R. K., Petzing J., et al., Surface measurement errors using commercial scanning white light interferometers, Meas. Sci. Technol., 19, 015303 (2008).

DOI: 10.1088/0957-0233/19/1/015303

[2] GUO T., Ma L., Zhao J. et al. A nano measuring machine based on white light tilt scanning interferometer for large scale optical array structure measurement. Optics and Laser in Engineering, 49(9-10), 1124-1130(2011).

DOI: 10.1016/j.optlaseng.2011.05.011

[3] Helen S. S., Kothiyal, M. P., Sirohi R. S., Analysis of spectrally resolved white light interferomgrams: use of a phase shifting technique, Proc. of SPIE, 40(7), 1329-1336 (2001).

DOI: 10.1117/1.1383997

[4] Hlubina P., Ciprian D., Lunácek J., Dispersive white light spectral interferometry with absolute phase retrieval to measure thin film, Opt. Express, 17(14), 7678-7685 (2006).

DOI: 10.1364/oe.14.007678

[5] Ghim Y. S., Kim S. W., Thin-film thickness profile and its refractive index measurement by dispersive white light interferometry, Opt. Express, 24(14), 11885-11891 (2006).

DOI: 10.1364/oe.14.011885

[6] I. Gurov, P. Hlubina, V. Chugunov, Evaluation of spectral modulated interferograms using a Fourier transform and the iterative phase-locked loop method, Meas. Sci. Technol., 14, 122–130 (2003).

DOI: 10.1088/0957-0233/14/1/318

[7] I. Gurov, E. Ermolaeva, A. Zakharov, Analysis of low-coherence interference fringes by the Kalman filtering method, Opt. Soc. Am. A, 21, 242–251 (2004).

DOI: 10.1364/josaa.21.000242

[8] Kino G. S., Chim S. S. C., Mirau correlation microscope, Appl. Opt, 29 (26), 3775-3783 (1990).

DOI: 10.1364/ao.29.003775

[9] Sanjit K. D., Kothiyal M. P., Schmit J., et al., Spectral resolved phase-shifting interfermotery of transparent thin film: sensitivity of thickness measurements, Appl. Opt. , 45(34), 8636-8640 (2006).

DOI: 10.1364/ao.45.008636