Analysis of systematic errors in lateral shearing interferometry for EUV optical testing

Ryan Miyakawa; Patrick Naulleau; Ken Goldberg

doi:10.1117/12.812340

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23 March 2009 Analysis of systematic errors in lateral shearing interferometry for EUV optical testing

Ryan Miyakawa, Patrick Naulleau, Ken Goldberg

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Proceedings Volume 7272, Metrology, Inspection, and Process Control for Microlithography XXIII; 72721V (2009) https://doi.org/10.1117/12.812340
Event: SPIE Advanced Lithography, 2009, San Jose, California, United States

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.

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Ryan Miyakawa, Patrick Naulleau, and Ken Goldberg "Analysis of systematic errors in lateral shearing interferometry for EUV optical testing", Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72721V (23 March 2009); https://doi.org/10.1117/12.812340

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