Scatterometry: a metrology for subwavelength surface-relief gratings

Petre-Catalin Logofatu; John R. McNeil

doi:10.1117/12.436772

22 August 2001 Scatterometry: a metrology for subwavelength surface-relief gratings

Proceedings Volume 4344, Metrology, Inspection, and Process Control for Microlithography XV; (2001) https://doi.org/10.1117/12.436772
Event: 26th Annual International Symposium on Microlithography, 2001, Santa Clara, CA, United States

Abstract

Phase-modulation scatterometry is a metrology technique for determining the parameters of gratings using as a key device a phase modulator. For measurement purposes the phase modulator requires a complicated calibration procedure that is analyzed here in detail. The main source of error to be dealt with are the fluctuations of the phase modulation amplitude. The measurables are the direct term and the first two harmonics of the output. For the fitting of the experimental data we used the ratio of the harmonics to the direct term because it improves significantly 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, comparisons of the theoretical predictions for sensitivity with the actual values showed a good agreement. For both samples the sensitivity analysis indicated sub-nanometric precision for the critical dimension (grating linewidth).

Citation Download Citation

Petre-Catalin Logofatu and John R. McNeil "Scatterometry: a metrology for subwavelength surface-relief gratings", Proc. SPIE 4344, Metrology, Inspection, and Process Control for Microlithography XV, (22 August 2001); https://doi.org/10.1117/12.436772

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