Lens heating-induced focus drift of I-line step and scan: correction and control in a manufacturing environment

Grace H. Ho; Anthony Cheng; Chung-Jen Chen; C. K. Fang; Meng C. Li; I-Chung Chang; P. T. Chu; Y. C. Chu; K. Y. Shu; C. Y. Huang; H. L. Yeh; H. C. Shiao; Ho Ku Lan

doi:10.1117/12.436722

22 August 2001 Lens-heating-induced focus drift of I-line step and scan: correction and control in a manufacturing environment

Grace H. Ho, Anthony Cheng, Chung-Jen Chen, C. K. Fang, Meng C. Li, I-Chung Chang, P. T. Chu, Y. C. Chu, K. Y. Shu, C. Y. Huang, H. L. Yeh, H. C. Shiao, Ho Ku Lan

Author Affiliations +

Proceedings Volume 4344, Metrology, Inspection, and Process Control for Microlithography XV; (2001) https://doi.org/10.1117/12.436722
Event: 26th Annual International Symposium on Microlithography, 2001, Santa Clara, CA, United States

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.

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Grace H. Ho, Anthony Cheng, Chung-Jen Chen, C. K. Fang, Meng C. Li, I-Chung Chang, P. T. Chu, Y. C. Chu, K. Y. Shu, C. Y. Huang, H. L. Yeh, H. C. Shiao, and 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); https://doi.org/10.1117/12.436722

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