20 August 2004 Optimization of the chromium-shielding attenuated phase shift mask for 157-nm lithography
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Proceedings Volume 5446, Photomask and Next-Generation Lithography Mask Technology XI; (2004); doi: 10.1117/12.557753
Event: Photomask and Next Generation Lithography Mask Technology XI, 2004, Yokohama, Japan
Abstract
We evaluated the chromium-shielding attenuated phase shift mask (Cr-shield att-PSM) for the fabrication of fine hole patterns in 157-nm lithography. The transmittance of the phase shifter was set at 5% to achieve the best performance for 70- to 90-nm-diameter holes. Simulation and experimental results indicated that the optimum distance a between the pattern edge and the Cr-shield edge changed depending on the size and pitch of the holes. The optimum distance a for sub-70-nm-diameter holes was zero, which meant the binary mask gives the best depth of focus. In the case of 80-nm-diameter holes, the conventional att-PSM proved to be the best option for 1:1 hole patterns. For 1:2 hole patterns, the optimized distance a was 60 to 70 nm. For isolated hole patterns, the optimum distance a was 45 nm. After optimizing distance a, we confirmed the side-lobe control capability of the Cr-shield att-PSM through exposure experiments. The elimination of side-lobes greatly improved the resolution. Furthermore, we found that the mask linearity was improved through use of a Cr-shield att-PSM.
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Eiji Kurose, Kunio Watanabe, Toshifumi Suganaga, Toshiro Itani, Kiyoshi Fujii, "Optimization of the chromium-shielding attenuated phase shift mask for 157-nm lithography", Proc. SPIE 5446, Photomask and Next-Generation Lithography Mask Technology XI, (20 August 2004); doi: 10.1117/12.557753; https://doi.org/10.1117/12.557753
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KEYWORDS
Photomasks

Binary data

Phase shifts

Lithography

Nanoimprint lithography

Transmittance

Optical lithography

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