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Proceedings Paper

Through-the-mask (TTM) optical alignment for high volume manufacturing nanoimprint lithography systems
Author(s): Takamitsu Komaki; Yasuyuki Unno; Takahiro Matsumoto; Toshiki Iwai; Nozomu Hayashi; Tomokazu Taki; Tohru Kawashima; Satoshi Iino; Shinichirou Hirai; Ken Minoda; Takafumi Miyaharu; Kazuhiro Takahashi; Kazuhiko Mishima
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Paper Abstract

As the most aggressive features in advanced memory designs continue to shrink, so does the overlay budget. The number of layer stacks also creates unwanted topography, and the alignment robustness of lithography tools becomes much more important for on-product overly. Canon developed a through-the-mask moiré alignment system for the FPA-1200NZ2C nanoimprint lithography (NIL) system allowing high-speed measurement of several alignment marks within each imprint field and alignment compensation to be completed during the imprinting sequence. To provide increased process flexibility and overlay accuracy while maintaining high-productivity, we have developed a new low-noise and high-resolution moiré diffraction alignment system based on spatial phase interferometry. In this paper, we report on the TTM detection system used in FPA-1200NZ2C. In particular, the principle of moiré detection and the improvement of the detection method will be described. The measurement error of moiré is analyzed by a simplified model calculation and we confirmed the relationship between process change and alignment error. Results of analyses proved that selection of the wavelength are key factors for optimizing alignment accuracy. Based on these results we applied the following improvement items: 1) Dual Dipole illumination, 2) Optimization of the alignment wavelength. We evaluated the new alignment system measurement error by comparing the moiré measurement value with the measured overlay values for 24 wafers and confirmed that new TTM alignment system can reduce to the measurement error more than 40%. The data shows that our moiré measurement system can provide process robustness and can support mass-production of leading-edge memory products.

Paper Details

Date Published: 23 March 2020
PDF: 11 pages
Proc. SPIE 11327, Optical Microlithography XXXIII, 113270Y (23 March 2020);
Show Author Affiliations
Takamitsu Komaki, Canon Inc. (Japan)
Yasuyuki Unno, Canon Inc. (Japan)
Takahiro Matsumoto, Canon Inc. (Japan)
Toshiki Iwai, Canon Inc. (Japan)
Nozomu Hayashi, Canon Inc. (Japan)
Tomokazu Taki, Canon Inc. (Japan)
Tohru Kawashima, Canon Inc. (Japan)
Satoshi Iino, Canon Inc. (Japan)
Shinichirou Hirai, Canon Inc. (Japan)
Ken Minoda, Canon Inc. (Japan)
Takafumi Miyaharu, Canon Inc. (Japan)
Kazuhiro Takahashi, Canon Inc. (Japan)
Kazuhiko Mishima, Canon Inc. (Japan)

Published in SPIE Proceedings Vol. 11327:
Optical Microlithography XXXIII
Soichi Owa, Editor(s)

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