22 August 2001 Lens-heating-induced focus drift of I-line step and scan: correction and control in a manufacturing environment
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Abstract
The lens heating (LH) induced focus drift of the ASML i-line Step & Scan was measured at five NA/Sigma settings: three ASML default and two TSMC production settings. The new LH scaling constants at three ASML settings, when multiplied by a dose-matching factor for production, agreed well with the default constants. Experimental results at NAI11 of 0.21 - 0.228 indicate that the LH induced focus drift is NA dependent, and the extent is NA = 0.4A ~ 0.5B>0.63 - 0.65. At the TSMC production settings of NA = 0.4A and 0.5B, the focus drift is approximately 20% greater than those predicted by the ASML LH algorithm. This study applies the new set of scaling constants for the LH focus correction. Long-term focus stability can be maintained within three standard deviations of less than 70nm, for all i-line Step & Scans in the manufacturing environment of one TSMC Fab.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Grace H. Ho, Grace H. Ho, Anthony Cheng, Anthony Cheng, Chung-Jen Chen, Chung-Jen Chen, C. K. Fang, C. K. Fang, Meng C. Li, Meng C. Li, I-Chung Chang, I-Chung Chang, P. T. Chu, P. T. Chu, Y. C. Chu, Y. C. Chu, K. Y. Shu, K. Y. Shu, C. Y. Huang, C. Y. Huang, H. L. Yeh, H. L. Yeh, H. C. Shiao, H. C. Shiao, Ho Ku Lan, Ho Ku Lan, } "Lens-heating-induced focus drift of I-line step and scan: correction and control in a manufacturing environment", Proc. SPIE 4344, Metrology, Inspection, and Process Control for Microlithography XV, (22 August 2001); doi: 10.1117/12.436722; https://doi.org/10.1117/12.436722
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