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Proceedings Paper

Analysis of systematic errors in lateral shearing interferometry for EUV optical testing
Author(s): Ryan Miyakawa; Patrick Naulleau; Ken Goldberg
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Paper Abstract

Lateral shearing interferometry (LSI) provides a simple means for characterizing the aberrations in optical systems at EUV wavelengths. In LSI, the test wavefront is incident on a low-frequency grating which causes the resulting diffracted orders to interfere on the CCD. Due to its simple experimental setup and high photon efficiency, LSI is an attractive alternative to point diffraction interferometry and other methods that require spatially filtering the wavefront through small pinholes which notoriously suffer from low contrast fringes and improper alignment. In order to demonstrate that LSI can be accurate and robust enough to meet industry standards, analytic models are presented to study the effects of unwanted grating and detector tilt on the system aberrations, and a method for identifying and correcting for these errors in alignment is proposed. The models are subsequently verified by numerical simulation. Finally, an analysis is performed of how errors in the identification and correction of grating and detector misalignment propagate to errors in fringe analysis.

Paper Details

Date Published: 23 March 2009
PDF: 6 pages
Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72721V (23 March 2009); doi: 10.1117/12.812340
Show Author Affiliations
Ryan Miyakawa, Univ. of California, Berkeley (United States)
Lawrence Berkeley National Lab. (United States)
Patrick Naulleau, Lawrence Berkeley National Lab. (United States)
Ken Goldberg, Lawrence Berkeley National Lab. (United States)

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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