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23 September 2009 Revisit to aberration: a simulation study of lens aberration induced overlay misalignment and its experimental validation
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Abstract
Overlay (O/L) misalignment (M/A) is induced from numerous sources including metrology error and stage control error, and aberration in projection optics. However, as design rule become smaller, aberration induced O/L M/A is evaluated to take considerable portion in the overlay budget. This paper focuses on O/L M/A issues from projection optics. We presents a simulation analysis of M/A between contact hole (C/H) pattern and line & space (L/S) pattern at 65nm node based on the aberration data from actual lithography tool to single out the main source of O/L M/A.. The study shows that the aberration in projection optics can induce considerable M/A and the conventional overlay keys do not represent this M/A properly. Among the Zernike fringe polynomials, the third-order behavior (D3) in Z2 (tilt) is found to be the critical source of misalignment. This portion of the aberration is resulted from the lens heating (LH) and can be corrected. However, this correction method needs improvements because its controllability over LH is not enough for the complete correction of LH induced M/A. Besides D3, Z10 (3-Foil) are found to be the major sources for pattern shift in C/H patterns, and Z7 and Z14 (Coma x) are found for L/S patterns.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hoyeon Kim, Sung-Woo Lee, Byeongcheol Lee, Sanghwa Lee, Kyoungyong Cho, Seong-Woon Choi, and Chan-Hoon Park "Revisit to aberration: a simulation study of lens aberration induced overlay misalignment and its experimental validation", Proc. SPIE 7488, Photomask Technology 2009, 74883E (23 September 2009); https://doi.org/10.1117/12.833345
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