Fast simulation methods for defective EUV mask blank inspection

Michael C. Lam; Andrew R. Neureuther

doi:10.1117/12.569075

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6 December 2004 Fast simulation methods for defective EUV mask blank inspection

Michael C. Lam, Andrew R. Neureuther

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Proceedings Volume 5567, 24th Annual BACUS Symposium on Photomask Technology; (2004) https://doi.org/10.1117/12.569075
Event: Photomask Technology, 2004, Monterey, California, United States

Abstract

A proof of concept methodology has been demonstrated for greatly speeding up the simulation of buried defects inside of EUVL multilayer mask blanks through exploiting the problem specific nature of EUV multilayer materials. The optical homogeneity and optical smoothness of EUV buried defects, along with the low numerical aperture of the EUV system, allow the development of fast and accurate simulations. The buried defect problem is broken into three separate components: a push inward to deliver the electromagnetic energy, a reflection calculation, and a push outward to propagate the reflections outside of the multilayer. This new method has been shown to give results as accurate as FDTD simulations, while maintaining the speed of the SSA method when used to simulate buried defects coated with the smoothing process developed at LLNL. The newly proposed method can be viewed as a generalization of the SSA method to incorporate the entire multilayer stack by using a dual mirror structure to approximate the resonance conditions. The new method has been shown to be about 400X faster and use about 20X less memory than FDTD simulations.

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Michael C. Lam and Andrew R. Neureuther "Fast simulation methods for defective EUV mask blank inspection", Proc. SPIE 5567, 24th Annual BACUS Symposium on Photomask Technology, (6 December 2004); https://doi.org/10.1117/12.569075

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