24 July 1996 DOF enhancement effect of attenuated assist feature
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Proceedings Volume 2793, Photomask and X-Ray Mask Technology III; (1996) https://doi.org/10.1117/12.245202
Event: Symposium on Photomask and X-Ray Mask Technology, 1996, Kawasaki City, Japan
To improve the depth of focus (DOF) of isolated lines, attenuated assist feature (AAF) technique has been proposed; AAFs having more than 20 % transmittance were located around an isolated line. In this mask, the transmittance & phase shift angle of AAF as well as its position & width have effects on lithographic performance. In particular, the phase shift angle has strong effect on focus latitude. The performances of two AAF masks (65 % transmittance/ 28° phase shift and 40 % transmittance/ 54° phase shift) were evaluated by using an NA=0.6, σinout = 0.42/0.7, i-line stepper. The focus latitude of 0.3 μm isolated line became flat around the best focus position with 28(degree) phase shift AAFs. In conclusion, we can obtain wide DOF for isolated lines by selecting optimum phase shift angle of AAF.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Shinji Ishida, Shinji Ishida, Shuichi Hashimoto, Shuichi Hashimoto, Tadao Yasuzato, Tadao Yasuzato, Kunihiko Kasama, Kunihiko Kasama, } "DOF enhancement effect of attenuated assist feature", Proc. SPIE 2793, Photomask and X-Ray Mask Technology III, (24 July 1996); doi: 10.1117/12.245202; https://doi.org/10.1117/12.245202

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