US 12,468,220 B2
Mask blank substrate, substrate with multilayer reflective film, reflective mask blank, reflective mask, and method of manufacturing semiconductor device
Tatsuya Sasaki, Tokyo (JP); and Masaru Tanabe, Tokyo (JP)
Assigned to HOYA CORPORATION, Tokyo (JP)
Filed by HOYA CORPORATION, Tokyo (JP)
Filed on Oct. 25, 2022, as Appl. No. 17/972,887.
Claims priority of application No. 2021-177544 (JP), filed on Oct. 29, 2021.
Prior Publication US 2023/0132780 A1, May 4, 2023
Int. Cl. G03F 1/60 (2012.01); G03F 1/24 (2012.01); G03F 1/54 (2012.01)
CPC G03F 1/60 (2013.01) [G03F 1/24 (2013.01); G03F 1/54 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A mask blank substrate comprising two opposing main surfaces,
wherein the substrate consists of a glass material containing SiO2 and TiO2,
wherein the substrate has a first region in one main surface side,
wherein the first region is a region within a 132 mm×104 mm square comprising a center portion in the one main surface and which is a region extending from the one main surface toward the other main surface up to a position of 500 μm in depth,
wherein an inner region of the substrate excluding the first region has a locally non-uniform portion,
wherein a ratio of Ti content rate to Si content rate (Ti/Si) of the non-uniform portion differs from Ti/Si of the inner region excluding the non-uniform portion by 0.25% or more, and
wherein a variation of Ti content rate in the inner region of the substrate excluding the first region and the non-uniform portion is 0.06 mass % or less.