9 July 2015 CD measurement point extraction from local dense patterns
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Precision control of critical dimensions (CD) in modern photomask manufacturing is conventionally accomplished by measuring of CD check patterns allocated inside photomask area. Recently, due to use of immersion and High-NA processes for ArF scanners surface of photomask is subjected to higher energy exposure. Such high energy exposure not only increases the loading effect and the flare but also brings about additional issues such as Cr migration and degradation of MoSi film quality due to its surface oxidation which become a new source of CD deviation. Such phenomenon influence both local pattern shape and its dependence on pattern density and global pattern density and arrangement. To achieve good control of CD in such global environment it is required to measure patterns in the chip device area equivalent to CD check patterns allocated on that chip. However, it is extremely difficult to accurately extract coordinates of patterns for CD measurements inside large device of the chip. We have developed a system in which firstly, using design rule check (DRC) method we extract from the chip device area simple line and space (L/S) patterns similar to CD check patterns and secondly, after bitmap transformation of the extraction result use a convolution operation approach to determine the patterns to measure. We confirmed that our method enables selection of CD measurement points with good reproducibility and stability. Next, we report on details of our method to extract CD measurement points and demonstrate its usefulness due to its excellent reproducibility and stability.
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Masaaki Miyajima, Masaaki Miyajima, Hiroyuki Matsumoto, Hiroyuki Matsumoto, Kanji Takeuchi, Kanji Takeuchi, Mitsufumi Naoe, Mitsufumi Naoe, Koji Hosono, Koji Hosono, Toru Miyauchi, Toru Miyauchi, } "CD measurement point extraction from local dense patterns", Proc. SPIE 9658, Photomask Japan 2015: Photomask and Next-Generation Lithography Mask Technology XXII, 96580Z (9 July 2015); doi: 10.1117/12.2195445; https://doi.org/10.1117/12.2195445

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