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Proceedings Paper

Lens heating-induced focus drift of I-line step and scan: correction and control in a manufacturing environment
Author(s): 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
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Paper 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.

Paper Details

Date Published: 22 August 2001
PDF: 8 pages
Proc. SPIE 4344, Metrology, Inspection, and Process Control for Microlithography XV, (22 August 2001); doi: 10.1117/12.436722
Show Author Affiliations
Grace H. Ho, ASML (Taiwan)
Anthony Cheng, ASML (Taiwan)
Chung-Jen Chen, TSMC (Taiwan)
C. K. Fang, TSMC (Taiwan)
Meng C. Li, TSMC (Taiwan)
I-Chung Chang, TSMC (Taiwan)
P. T. Chu, TSMC (Taiwan)
Y. C. Chu, TSMC (Taiwan)
K. Y. Shu, TSMC (Taiwan)
C. Y. Huang, TSMC (Taiwan)
H. L. Yeh, TSMC (Taiwan)
H. C. Shiao, TSMC (Taiwan)
Ho Ku Lan, TSMC (Taiwan)


Published in SPIE Proceedings Vol. 4344:
Metrology, Inspection, and Process Control for Microlithography XV
Neal T. Sullivan, Editor(s)

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