At-wavelength interferometry of extreme ultraviolet lithographic optics
- Center for X-ray Optics, Mail Stop 2-400, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
A phase-shifting point diffraction interferometer (PS/PDI) has recently been developed to evaluate optics for extreme ultraviolet (EUV) projection lithography systems. The interferometer has been implemented at the Advanced Light Source at Lawrence Berkeley National Laboratory and is currently being used to test experimental EUV Schwarzschild objectives. Recent PS/PDI measurements indicate these experimental objectives to have wavefront errors on the order of 0.1 waves ({approximately}1 nm at a wavelength of 13.4 nm) rms. These at-wavelength measurements have also revealed the multilayer phase effects, demonstrating the sensitivity and importance of EUV characterization. The measurement precision of the PS/PDI has been experimentally determined to be better than 0.01 waves. Furthermore, a systematic-error-limited absolute measurement accuracy of 0.004 waves has been demonstrated. {copyright} {ital 1998 American Institute of Physics.}
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 678847
- Report Number(s):
- CONF-980364--
- Journal Information:
- AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 449; ISSN APCPCS; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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