Extreme-ultraviolet phase-shifting point-diffraction interferometer: a wave-front metrology tool with subangstrom reference-wave accuracy

Journal Article · Fri Dec 10 04:00:00 EST 1999 · Applied Optics

DOI:https://doi.org/10.1364/AO.38.007252· OSTI ID:20215573

Naulleau, Patrick P ^[1]; Goldberg, Kenneth A ^[1]; Lee, Sang H ^[1]; Chang, Chang ^[2]; Atwood, David ^[1]; Bokor, Jeffrey ^[1]

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1. Center for X-Ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
2. Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California 94720 (United States)

The phase-shifting point-diffraction interferometer (PS/PDI) was recently developed and implemented at Lawrence Berkeley National Laboratory to characterize extreme-ultraviolet (EUV) projection optical systems for lithography. Here we quantitatively characterize the accuracy and precision of the PS/PDI. Experimental measurements are compared with theoretical results. Two major classes of errors affect the accuracy of the interferometer: systematic effects arising from measurement geometry and systematic and random errors due to an imperfect reference wave. To characterize these effects, and hence to calibrate the interferometer, a null test is used. This null test also serves as a measure of the accuracy of the interferometer. We show the EUV PS/PDI, as currently implemented, to have a systematic error-limited reference-wave accuracy of 0.0028 waves ({lambda}/357 or 0.038 nm at {lambda}=13.5 nm) within a numerical aperture of 0.082. (c) 1999 Optical Society of America.

• OSTI ID: 20215573
• Journal Information: Applied Optics, Journal Name: Applied Optics Journal Issue: 35 Vol. 38; ISSN 0003-6935; ISSN APOPAI
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ERRORS
EXPERIMENTAL DATA
EXTREME ULTRAVIOLET RADIATION
INTERFEROMETERS
PHASE SHIFT
SENSITIVITY ANALYSIS
SPATIAL RESOLUTION