13 June 2017 Detection of grating asymmetries by phase-structured illumination
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Proceedings Volume 10449, Fifth International Conference on Optical and Photonics Engineering; 104490C (2017) https://doi.org/10.1117/12.2269167
Event: Fifth International Conference on Optical and Photonics Engineering, 2017, Singapore, Singapore
The characterization of nanoscale grating asymmetries is an indispensable prerequisite for improving the accuracy of process control in modern semiconductor lithography. Model-based scatterometry is the state-of-the-art optical waferinspection technique. We suggest to extend it by coherent phase-structured illumination. The resulting intensity and phase profiles are evaluated in the far-field image plane. By means of rigorous simulations, it has already been demonstrated that the use of phase-structured illumination increases the sensitivity towards any kind of grating asymmetry including asymmetric sidewall angles (SWAs), floor tilts, asymmetric top and bottom roundings, and even overlay errors. Furthermore, it is possible to determine both the absolute value and the sign (magnitude and direction) of an asymmetry. In this paper, we will recapitulate the evaluation strategy and summarize the most important simulation results. Subsequently, we will present first proof-of-principle measurements obtained by digital off-axis holography. A direct comparison between simulation and measurement demonstrates the validity of the suggested approach.
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M. L. Gödecke, M. L. Gödecke, S. Peterhänsel, S. Peterhänsel, D. Buchta, D. Buchta, K. Frenner, K. Frenner, W. Osten, W. Osten, } "Detection of grating asymmetries by phase-structured illumination", Proc. SPIE 10449, Fifth International Conference on Optical and Photonics Engineering, 104490C (13 June 2017); doi: 10.1117/12.2269167; https://doi.org/10.1117/12.2269167

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