Accurate prediction of 3D mask topography induced best focus variation in full-chip photolithography applications

Peng Liu

doi:10.1117/12.898783

13 October 2011 Accurate prediction of 3D mask topography induced best focus variation in full-chip photolithography applications

Peng Liu

Author Affiliations +

Proceedings Volume 8166, Photomask Technology 2011; 816640 (2011) https://doi.org/10.1117/12.898783
Event: SPIE Photomask Technology, 2011, Monterey, California, United States

Abstract

Best focus variation among different device features is one of the limiting factors to process window in semiconductor photolithography applications. Accurate prediction of best focus variation in full-chip optical proximity correction (OPC) and verifications is important in order to detect and mitigate the problem in design and post-design stages. In this work, the origin of best focus variation is first studied analytically by analyzing a simple but important imaging problem. It shows that phase difference between diffraction orders causes best focus shift. Then a rigorous simulation of mask diffraction further shows that the phase difference induced by 3D mask topography is non-zero and is a function of pattern and angle of incidence onto the mask. As a result, 3D mask models that can take into account oblique incidence effects are required in order to accurately predict best focus variations in full-chip applications. Tachyon M3D is a fast 3D mask model developed for full-chip OPC and verifications. Its accuracy in predicting best focus variation against measured wafer data is evaluated in this work. The results show very good correlation between M3D simulations and experiments.

Citation Download Citation

Peng Liu "Accurate prediction of 3D mask topography induced best focus variation in full-chip photolithography applications", Proc. SPIE 8166, Photomask Technology 2011, 816640 (13 October 2011); https://doi.org/10.1117/12.898783

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