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Applied Optics

Applied Optics


  • Vol. 41, Iss. 34 — Dec. 2, 2002
  • pp: 7187–7192

Phase-modulation scatterometry

Petre C. Logofătu  »View Author Affiliations

Applied Optics, Vol. 41, Issue 34, pp. 7187-7192 (2002)

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Phase-modulation scatterometry is a metrology technique for determining, by means of a phase modulator as a key device, the parameters of gratings. The main source of error to be dealt with are the fluctuations of the phase-modulation amplitude. The grating zeroth-order reflectance modulated by the phase modulator is converted into a signal by the photodetector. The measurables are the direct term and the first two harmonics of the signal. For experimental data fitting, we used the ratio of the harmonics over the direct term because it significantly improves the accuracy. A sensitivity analysis was performed for two samples, one real and one theoretical, to find the measurement configuration that insures optimum determination precision for the grating parameters. For the real sample, comparison of the theoretical predictions for sensitivity with the actual values showed a good agreement. For both samples the sensitivity analysis indicated subnanometric precision for the critical dimension (grating linewidth).

© 2002 Optical Society of America

OCIS Codes
(050.1950) Diffraction and gratings : Diffraction gratings
(120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
(120.5060) Instrumentation, measurement, and metrology : Phase modulation
(120.5700) Instrumentation, measurement, and metrology : Reflection
(260.2130) Physical optics : Ellipsometry and polarimetry
(260.5430) Physical optics : Polarization

Original Manuscript: March 11, 2002
Revised Manuscript: May 23, 2002
Published: December 1, 2002

Petre C. Logofătu, "Phase-modulation scatterometry," Appl. Opt. 41, 7187-7192 (2002)

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