ULE® Glass for EUVL applications, a fictive temperature correlation

Structure and thermo-mechanical response of TiO2-SiO2 glasses to temperature

“…Shelby [6] summarized densities of TiO 2 -SiO 2 glasses from eight studies, where the majority of measured values are between 2.19-2.21 g/cm 3 with the rest between 2.15 and 2.28 g/cm 3 . Densities of TiO 2 -SiO 2 glasses prepared through the sol-gel process have been reported in the range of 2.10 to 2.36 g/cm 3 [15], so the densities of our sol-gel samples seem reasonable, if generally slightly low.…”

“…Density of samples was measured through the Archimedes method, using water as the liquid medium. Each sample was measured ten times, resulting in standard deviations between 0.005 and 0.01 g/cm 3 . Sintered sol-gel samples have densities between 2.15 and 2.18 g/cm 3 , very close to the values of TiO 2 -SiO 2 glasses prepared through other methods [6][7][8], but lower than the 2.20 g/cm 3 of other synthetic glasses produced by FHD that were measured using the same method.…”

“…Each sample was measured ten times, resulting in standard deviations between 0.005 and 0.01 g/cm 3 . Sintered sol-gel samples have densities between 2.15 and 2.18 g/cm 3 , very close to the values of TiO 2 -SiO 2 glasses prepared through other methods [6][7][8], but lower than the 2.20 g/cm 3 of other synthetic glasses produced by FHD that were measured using the same method. Shelby [6] summarized densities of TiO 2 -SiO 2 glasses from eight studies, where the majority of measured values are between 2.19-2.21 g/cm 3 with the rest between 2.15 and 2.28 g/cm 3 .…”

“…Titania is added to silica to produce ultra-low expansion (ULE) glasses, i.e., glasses that have zero or even negative coefficient of thermal expansion (CTE) at room temperature [1,2]. This unique characteristics has made them very useful in many applications, such as machine tool reference blocks, mirror blanks for telescopes and space satellites, and mask substrates for extreme ultra-violet lithography (EUVL) in the semiconductor industry [3]. However, the role titanium plays in the glass structure to give the ultra-low CTE is still under much speculation despite the extensive studies in the past few decades [1,2,4, and 5].…”

ULE®Glass with Improved Thermal Properties for EUVL Masks and Projection Optics Substrates

“…These results are previously published. 16 This paper contains details on how the structural state of the glass can be modified and also provides details of both the characterization metrology and how the behavior is modeled. Knowing the titania content and the FTIR spectra, the fictive temperature (structural state of the glass) could be determined.…”