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Proceedings Paper

Immersion specific error contribution to overlay control
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Paper Abstract

Ever since the introduction of immersion lithography overlay has been a primary concern. Immersion exposure tools show an overlay fingerprint that we hope to correct for by introducing correctables per field, i.e. a piece-wise approximation of the fingerprint but within the correction capabilities of the exposure tool. If this mechanism is to be used for reducing overlay errors it must be stable over an entire batch. This type of correction requires a substantial amount of measurements therefore it would be ideal if the fingerprint is also stable over time. These requirements are of particular importance for double patterning where overlay budgets have been further reduced. Since the variation of the fingerprint specific to immersion tools creeps directly into the overlay budget, it is important to know how much of the total overlay error can be attributed to changes in the immersion fingerprint. In this paper we estimate this immersion specific error but find it to be a very small contributor.

Paper Details

Date Published: 23 March 2009
PDF: 6 pages
Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72720D (23 March 2009); doi: 10.1117/12.814923
Show Author Affiliations
Koen D'havé, IMEC (Belgium)
David Laidler, IMEC (Belgium)
Shaunee Cheng, IMEC (Belgium)


Published in SPIE Proceedings Vol. 7272:
Metrology, Inspection, and Process Control for Microlithography XXIII
John A. Allgair; Christopher J. Raymond, Editor(s)

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