In-situ optical testing of exposure tools via localized wavefront curvature sensing

Autor: Dominic Ashworth, Michael Goldstein, Yashesh Shroff, Xibin Zhou, Yu-Jen Fan, Ryan Miyakawa, Gregory Denbeaux, Yudhi Kandel, Patrick P. Naulleau, Kevin Cummings
Rok vydání: 2013
Předmět:
Zdroj: Extreme Ultraviolet (EUV) Lithography IV.
ISSN: 0277-786X
Popis: We present a new form of optical testing for exposure tools based on measuring localized wavefront curvature. In this method, offset monopole illumination is used to probe localized regions of the test optic pupil. Variations in curvature manifest as focus shifts, which are measured using a photodiode-based grating-on-grating contrast monitor, and the wavefront aberrations are reconstructed using a least-squares approach. This technique is attractive as it is independent of the numerical aperture of the system and does not require a CCD or a separate interferometer branch.
Databáze: OpenAIRE