Interferometry using undulator sources
- Center for X-ray Optics, Lawrence Berkeley Laboratory, 1 Cyclotron Rd., MS 2-400, Berkeley, CA 94720 (United States)
Optical systems for extreme ultraviolet (EUV) lithography need to use optical components with subnanometer surface figure error tolerances to achieve diffraction-limited performance [M.D. Himel, in {ital Soft} {ital X}-{ital Ray} {ital Projection} {ital Lithography}, A.M. Hawryluk and R.H. Stulen, eds. (OSA, Washington, D.C., 1993), {bold 18}, 1089, and D. Attwood {ital et} {ital al}., Appl. Opt. {bold 32}, 7022 (1993)]. Also, multilayer-coated optics require at-wavelength wavefront measurement to characterize phase effects that cannot be measured by conventional optical interferometry. Furthermore, EUV optical systems will additionally require final testing and alignment at the operational wavelength for adjustment and reduction of the cumulative optical surface errors. Therefore, at-wavelength interferometric measurement of EUV optics will be the necessary metrology tool for the successful development of optics for EUV lithography. An EUV point diffraction interferometer (PDI) has been developed at the Center for X-Ray Optics (CXRO) and has been already in operation for a year [K. Goldberg {ital et} {ital al}., in {ital Extreme} {ital Ultra} {ital Lithography}, D.T. Attwood and F. Zernike, eds. (OSA, Washington, D.C., 1994), K. Goldberg {ital et} {ital al}., Proc. SPIE {bold 2437}, to be published, and K. Goldberg {ital et} {ital al}., J. Vac. Sci. Technol. B {bold 13}, 2923 (1995)] using an undulator radiation source and coherent optics beamline at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. An overview of the PDI interferometer and some EUV wavefront measurements obtained with this instrument will be presented. In addition, future developments planned for EUV interferometry at CXRO towards the measurement of actual EUV lithography optics will be shown. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 389543
- Report Number(s):
- CONF-9510119-; ISSN 0034-6748; TRN: 96:027944
- Journal Information:
- Review of Scientific Instruments, Vol. 67, Issue 9; Conference: SRI `95: synchrotron radiation instrumentation symposium and the 7. users meeting for the advanced photon source (APS), Argonne, IL (United States), 16-20 Oct 1995; Other Information: PBD: Sep 1996
- Country of Publication:
- United States
- Language:
- English
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