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14 September 2001 Impact of flare on CD variation for 248-nm and 193-nm lithography systems
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All optical imaging systems have some amount of stray light, or flare, that detracts from system performance, critical dimension (CD) control, and process latitude. The effects of flare increase when multiple exposure processes, such as complementary phase shift, are used since this doubles the amount of exposure energy going through the optics. Flare was characterized on several modern KrF and ArF exposure tools using a direct method of measurement. Flare is determined by measuring the reduction in the size of a 160 nm line as it is subjected to increasing dose from a second 'flare' exposure. The amount of flare is determined using regression between experimental and modeled data. Lithography modeling was used to quantify the amount of flare responsible for CD variation. This method allows evaluation of CD control degradation on actual features that are sized close to production feature size. The effects of substrate reflectance and mask loading were also studied. The results were compared to a published large pad flare measurement technique in common use.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Anatoly Bourov, Lloyd C. Litt, and Lena Zavyalova "Impact of flare on CD variation for 248-nm and 193-nm lithography systems", Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001);

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