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Proceedings Paper

Development of a 20Х Schwarzschild projection optics for principle experiment of EUV at-wavelength interferometry
Author(s): Ke Liu; Yanqiu Li
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Paper Abstract

A 20× Schwarzschild projection optics (PO) designed for principle experiment of interferometry for extreme ultraviolet lithography (EUVL) is assembled and aligned utilizing a Fizeau-type interferometer. The design goal of the PO is to achieve a wavefront error (WFE) of less than 30mλ rms (λ = 632.8nm ) in an image side field diameter of 0.2mm. This paper presents the detailed design, assembly and alignment procedure of the PO. The PO is designed at 13.4nm wavelength for future EUV at-wavelength experiment and the original design could achieve a resolution of 100nm within a depth of focus of 75nm. Due to fabrication errors, the fabricated PO could only achieve a WFE of 28mλ rms (λ = 632.8nm ) simulated by CODE V in ideal alignment status. Tolerance analysis is performed by CODE V to determine the requirement of assembly mechanism and the tolerance of coarse alignment. In the coarse alignment process, a simple method based on the precise positioning of the curvature center of each mirror in Schwarzschild PO is used. In the fine alignment process, an effective computer aided alignment (CAA) method based on the singular value decomposition (SVD) of sensitivity matrix is used. Finally, alignment experiment is performed and a WFE of 28mλ rms (λ = 632.8nm ) is achieved after fine alignment.

Paper Details

Date Published: 18 May 2009
PDF: 6 pages
Proc. SPIE 7284, 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems, 72840E (18 May 2009); doi: 10.1117/12.832072
Show Author Affiliations
Ke Liu, Institute of Electrical Engineering (China)
Graduate Univ. of the CAS (China)
Yanqiu Li, Institute of Electrical Engineering (China)
Beijing Institute of Technolog (China)


Published in SPIE Proceedings Vol. 7284:
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems

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