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26 May 1995 New generation i-line lens for 0.35-um lithography
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In order to meet industrial requirements for 0.35 micrometers lithography, we have developed a new i-line lens with a high numerical aperture (0.63 NA) and wide image field (31.1 mm diameter). This paper described the image performance of this new i-line lens and the possibility of achieving 0.35 micrometers and 0.3 micrometers lithography with i-line. It is extremely important that the performance of a new generation i-line lens for 0.35 micrometers lithography be confirmed, not only with the conventional illumination technique but with other illumination such as modified illumination or with the phase shift reticle. This new i-line lens has been developed to show the smallest aberration for both its design and manufacturing. As a result of this effort, a total deviation of the field curvature is 0.15 micrometers or less and distortion deviation is 0.03 micrometers or less when the illumination condition is changed. In addition, another experiment for optimizing both NA and sigma was done with 0.35 micrometers critical dimension (CD). It has been confirmed that the optimum NA is 0.55 in order to maximize depth of focus (DOF) for 0.35 micrometers and the optimum Sigma is 0.65 from the view point of the smallest CD bias between isolated and dense features.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hiroyuki Ishii and Yoshio Kawanobe "New generation i-line lens for 0.35-um lithography", Proc. SPIE 2440, Optical/Laser Microlithography VIII, (26 May 1995);

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