12 April 2013 Flare management for 40-nm logic devices
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Since flare-related CD variation was observed in some 40-nm test chips, we evaluated the flare level of an ArF immersion scanner by the Kirk method. We found that the tool flare for a 1.3-μm pad was more than 5% and the short-range flare (scattering range < 10 μm) was quite large when the optics were degraded. Optics maintenance reduced the tool flare to about 2%. An evaluation of the impact of short-range flare on the space CDs of 40-nm logic devices revealed it to be quite large. The point spread function for flare was determined from measured flare data, and the flare density was calculated for various patterns. A simulation analysis showed that the measured CD error was closely related to flare density. Since the impact of a change in dose on space CD is nonlinear, the impact of a change in flare is also nonlinear. Simulations using tool flare and flare density can predict most of the CD error. In the active layer of 40-nm logic devices, the flare density is generally in the range of 40-70% for critical space patterns. Varying the dose control pattern from small-area L/S (< 5 μm square) to large-area L/S (50 μm square) should reduce the impact of flare on space CD. Patterns with a medium flare density are preferable for dose control.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yuusuke Tanaka, Yuusuke Tanaka, Takao Tamura, Takao Tamura, Masashi Fujimoto, Masashi Fujimoto, Kyoichi Tsubata, Kyoichi Tsubata, Naka Onoda, Naka Onoda, Kiyoshi Fujii, Kiyoshi Fujii, "Flare management for 40-nm logic devices", Proc. SPIE 8683, Optical Microlithography XXVI, 86832E (12 April 2013); doi: 10.1117/12.2010082; https://doi.org/10.1117/12.2010082


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