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21 June 2006 Spot sensor enabled reticle uniformity measurements for 65nm CDU analysis with scatterometry
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Proceedings Volume 6281, 22nd European Mask and Lithography Conference; 62810F (2006)
Event: 22nd European Mask and Lithography Conference, 2006, Dresden, Germany
Spot sensor Enabled Reticle Uniformity Measurement (SERUM) is a fast and accurate technique for measuring the CD fingerprint of a reticle. It is an alternative for the traditional SEM or optical based reticle line width measurements. The reticle fingerprint is obtained by scanning a spot sensor located on the wafer stage of the ASML Step & Scan system, and measuring the reticle transmission on actinic wavelength. Since the reticle is the main contributor to the 65nm CDU budget, Step & Scan system qualification is only possible when correcting for reticle errors. Especially for scatterometry based measurement an extensive reticle qualification is required. With the traditional methods it involves measuring multiple positions within the gratings to average-out the intra-grating variation. This results in an expensive and time consuming process (5 to 10 hours). SERUM reticle metrology has several applications. ASML specific Step & Scan system qualification can be improved in correcting for reticle errors. The reticle can be inspected on actinic wavelength for changes due to pellicle non-uniformity, transmission losses and contamination. SERUM data can also be used as input for DoseMapperTM to correct for global reticle line width non-uniformity. This metrology allows reticle measurement on 182 locations within 70 seconds, with a repeatability of 3σ < 0.35nm (reticle level).
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Maurice Janssen, Koen van Ingen Schenau, and Hans van der Laan "Spot sensor enabled reticle uniformity measurements for 65nm CDU analysis with scatterometry", Proc. SPIE 6281, 22nd European Mask and Lithography Conference, 62810F (21 June 2006);

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