Photomask CD and LER characterization using Mueller matrix spectroscopic ellipsometry

A. Heinrich; I. Dirnstorfer; J. Bischoff; K. Meiner; H. Ketelsen; U. Richter; T. Mikolajick

doi:10.1117/12.2065670

17 October 2014 Photomask CD and LER characterization using Mueller matrix spectroscopic ellipsometry

A. Heinrich, I. Dirnstorfer, J. Bischoff, K. Meiner, H. Ketelsen, U. Richter, T. Mikolajick

Proceedings Volume 9231, 30th European Mask and Lithography Conference; 92310L (2014) https://doi.org/10.1117/12.2065670
Event: 30th European Mask and Lithography Conference, 2014, Dresden, Germany

Abstract

Critical dimension and line edge roughness on photomask arrays are determined with Mueller matrix spectroscopic ellipsometry. Arrays with large sinusoidal perturbations are measured for different azimuth angels and compared with simulations based on rigorous coupled wave analysis. Experiment and simulation show that line edge roughness leads to characteristic changes in the different Mueller matrix elements. The influence of line edge roughness is interpreted as an increase of isotropic character of the sample. The changes in the Mueller matrix elements are very similar when the arrays are statistically perturbed with rms roughness values in the nanometer range suggesting that the results on the sinusoidal test structures are also relevant for “real” mask errors. Critical dimension errors and line edge roughness have similar impact on the SE MM measurement. To distinguish between both deviations, a strategy based on the calculation of sensitivities and correlation coefficients for all Mueller matrix elements is shown. The Mueller matrix elements M₁₃/M₃₁ and M₃₄/M₄₃ are the most suitable elements due to their high sensitivities to critical dimension errors and line edge roughness and, at the same time, to a low correlation coefficient between both influences. From the simulated sensitivities, it is estimated that the measurement accuracy has to be in the order of 0.01 and 0.001 for the detection of 1 nm critical dimension error and 1 nm line edge roughness, respectively.

Citation Download Citation

A. Heinrich, I. Dirnstorfer, J. Bischoff, K. Meiner, H. Ketelsen, U. Richter, and T. Mikolajick "Photomask CD and LER characterization using Mueller matrix spectroscopic ellipsometry", Proc. SPIE 9231, 30th European Mask and Lithography Conference, 92310L (17 October 2014); https://doi.org/10.1117/12.2065670

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