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Electromagnetically dual‐axis driven MEMS grating and its application to 3D profiling with near‐infrared low‐coherence interferometry
Author(s) -
Watanabe Yoshiyuki,
Takahashi Yoshiyuki,
Abe Yutaka,
Iwamatsu Shinnosuke,
Yahagi Toru,
Kobayashi Seiya,
Konno Shunsuke,
Sato Toshiyuki
Publication year - 2013
Publication title -
electronics and communications in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.131
H-Index - 13
eISSN - 1942-9541
pISSN - 1942-9533
DOI - 10.1002/ecj.11452
Subject(s) - interferometry , optics , microelectromechanical systems , grating , materials science , wavelength , astronomical interferometer , physics , optoelectronics
Abstract We have investigated 3D profiling of the objects by a low‐coherence optical interferometer using MEMS grating. This system, constructed with optical fibers and MEMS devices, is a Fourier domain interferometer, which can discriminate distance to the object by wavelength analysis of the interference spectra. A MEMS mirror gives the object 2D optical scanning, and a MEMS grating permits spectroscopy of interference spectra. The MEMS grating can tilt to dual axis with electromagnetic force induced by planar coils and a permanent magnet. One axis tilting enables near‐infrared spectroscopy and another axis tilting functions as optical axis alignment in an interferometer. Fabricated MEMS grating could tilt ±3.5° (mech.)/less than ±10 mA in both directions at low frequency, which were equivalent to approximately 1400 to 1700 nm in wavelength. The interferometer, whose S/N was 50 dB and vertical standard deviation was 0.6 µm, could scan full wavelength width (1400 to 1700 nm) in 25 ms. Finally, we could realize 3D profiling which was not only surface reection profiling of 1‐µm step, but also transparent profiling of IC process layer from the wafer backside. © 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(2): 9–15, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11452