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20 August 2001 Recent developments in EUV reflectometry at the Advanced Light Source
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In order to satisfy the metrology requirements of multilayer coatings for EUVL optics and masks, improvements have been made to the reflectometry beamline at the Advanced Light Source. The precision in determining multilayer peak reflectance and wavelength has been improved by reducing the measurement noise. The peak reflectance of a typical Mo/Si multilayer can now be measured with a precision of 0.08% rms (relative) and the centroid wavelength with a precision of 0.007% rms. It has now been possible to determine the contribution of scattered light to the spectral purity. Under the typical measurement conditions the scattered light accounts for about 1.3% of the incident beam. With an appropriate slit it is possible to reduce the scattered light to 0.25%. By correcting for the remaining scattered light, it is estimated that a reflectance accuracy of 0.1% (absolute) is obtained for a typical Mo/Si multilayer.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Eric M. Gullikson, Stanley Mrowka, and Benjamin B Kaufmann "Recent developments in EUV reflectometry at the Advanced Light Source", Proc. SPIE 4343, Emerging Lithographic Technologies V, (20 August 2001);

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