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10 May 2005 High speed reflectometer for EUV mask-blanks
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AIXUV GmbH and partners have developed a high speed Reflectometer for EUV mask-blanks which is fully compliant with the SEMI-standard P38 for EUV-mask-blank metrology. The system has been installed in June 2004 at SCHOTT Lithotec AG. It features high throughput, high lateral and spectral resolution, high reproduci-bility and low absolute uncertainty. Using AIXUV's EUV-LAMP and debris mitigation, low cost-of-ownership and high availability is expected. The spectral reflectance of up to 3 mask-blanks per hour can be measured with at least 20 spots each. The system is push button-controlled. Results are stored in CSV file format. For a spot size of 0.1×1 mm2, 2000 spectral chan-nels of 1.6 pm bandwidth are recorded from 11.6 nm to 14.8 nm. The reflectance measurement is based on the comparison of the sample under test to two reference mirrors calibrated at the PTB radiometry laboratory at BESSY II. The three reflection spectra are recorded simultaneously. For each spot more than 107 photons are ac-cumulated in about 20 s, providing statistical reproducibility below 0.2 % RMS. The total uncertainty is below 0.5 % absolute. Wavelength calibration better than 1 pm RMS over the whole spectral range is achieved by refe-rence to NIST published wavelengths of about 100 xenon emission lines. It is consistent with the wavelength of the krypton 3d-5p absorption resonance at 13.5947 nm to better than 2 pm.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
C. Wies, R. Lebert, B. Jaegle, L. Juschkin, F. Sobel, H. Seitz, R. Walter, C. Laubis, F. Scholze, W. Biel, and O. Steffens "High speed reflectometer for EUV mask-blanks", Proc. SPIE 5752, Metrology, Inspection, and Process Control for Microlithography XIX, (10 May 2005);

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