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Proceedings Paper

"Performance Of A Wafer Stepper With Automatic Intra-Die Registration Correction."
Author(s): M. A. van den Brink; S. Wittekoek; H. F. D. Linders; F. J. van Hout; R. A. George
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Paper Abstract

An evaluation of a wafer stepper with the new improved Philips/ASM-L phase grating alignment system is reported. It is shown that an accurate alignment system needs an accurate X-Y-0 wafer stage and an accurate reticle Z stage to realize optimum overlay accuracy. This follows from a discussion of the overlay budget and an alignment procedure model. The accurate wafer stage permits high overlay accuracy using global alignment only, thus eliminating the throughput penalty of align-by-field schemes. The accurate reticle Z stage enables an intra-die magnification control with respect to the wafer scale. Various overlay data are reported, which have been measured with the automatic metrology program of the stepper. It is demonstrated that the new dual alignment system (with the external spatial filter) has improved the ability to align to weakly reflecting layers. The results are supported by a Fourier analysis of the alignment signal. Resolution data are given for the PAS 2500 projection lenses, which show that the high overlay accuracy of the system is properly matched with submicron linewidth control. The results of a recently introduced 20mm i-line lens with a numerical aperture of 0.4 (Zeiss 10-78-58) are included.

Paper Details

Date Published: 1 January 1987
PDF: 18 pages
Proc. SPIE 0772, Optical Microlithography VI, (1 January 1987); doi: 10.1117/12.967039
Show Author Affiliations
M. A. van den Brink, ASM Lithography (Netherlands)
S. Wittekoek, ASM Lithography (Netherlands)
H. F. D. Linders, ASM Lithography (Netherlands)
F. J. van Hout, ASM Lithography (Netherlands)
R. A. George, ASM Lithography (Netherlands)

Published in SPIE Proceedings Vol. 0772:
Optical Microlithography VI
Harry L. Stover, Editor(s)

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