Battula, Venkata Siva; Zeuske, Jacob R.; Engelstad, Roxann L.; Vukkadala, Pradeep; Mikkelson, Andrew R. (UW Computational Mechanics Center, Mechanical Engineering Department, 1513 University Ave., University of Wisconsin - Madison, WI USA 53706)
Peski, Chris K. Van (Van Peski Consulting, 108 Palo Duro Drive, Cedar Creek, TX USA 78612)
Extreme Ultraviolet Lithography (EUVL) is one of the leading candidates for the next-generation lithography in the sub-30 nm regime. Stringent flatness requirements have been imposed for the front and back surfaces of EUVL masks to ensure successful pattern transfer that satisfies the image placement error budget. The EUVL Mask Standard (SEMI P-37) specifies the flatness of the two mask surfaces to be approximately 50 nm peak-to-valley. It is essential to measure the mask surface nonflatness accurately (without gravitational distortions) to the extent possible. The purpose of this research was to study the various mask mounting techniques and to compare these methods for repeatability and accuracy during the measurements.