19 May 2008 Modeling mask pellicle effects for OPC/RET
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Proceedings Volume 7028, Photomask and Next-Generation Lithography Mask Technology XV; 70283B (2008); doi: 10.1117/12.793118
Event: Photomask and NGL Mask Technology XV, 2008, Yokohama, Japan
Abstract
A thin membrane called a pellicle is commonly used to protect the mask from contamination. The thickness of the pellicle material is usually optimized at normal incident angle to minimize the thin film optics interference effect by cancellation of the reflected light from the top ambient/pellicle interface with the reflected light from the bottom pellicle/ambient interface. In previous lithography generations the maximum angle collected by the projection lens (NA) was low, hence the normal incidence approach was valid, and the transmission loss for the non-normal incident angles was minor and ignored. With modern hyper-NA imaging for 45nm and smaller nodes, this transmission attenuation becomes larger. The more stringent CD error budget of these technology nodes demands that this effect should not be ignored anymore. In this paper, we present a modeling framework that takes into consideration the high angle pellicle effects. Taking the pellicle's polarization state dependent transmission data, which can be measured or computed with a rigorous simulator, we first present the pellicle transmission property as Jones matrices on the pupil plane, and then incorporate pellicle modeling into the existing vector model for lithography imaging computation. Existing modeling software for modelbased OPC/RET tools is easily enhanced to include pellicle modeling. Using Synopsys' OPC/RET modeling software ProGen, we investigate the necessity of pellicle effect modeling for mask synthesis for 45 nm and smaller nodes. Numerical experiments are performed to study the impact of illumination polarization on the accuracy of lithography simulation and the quality of OPC results.
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Lena Zavyalova, Hua Song, Kevin Lucas, Qiaolin Zhang, James Shiely, "Modeling mask pellicle effects for OPC/RET", Proc. SPIE 7028, Photomask and Next-Generation Lithography Mask Technology XV, 70283B (19 May 2008); doi: 10.1117/12.793118; https://doi.org/10.1117/12.793118
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KEYWORDS
Pellicles

Optical proximity correction

Photomasks

Apodization

Data modeling

Lithography

Polarization

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