US 12,111,565 B2
Reflective photomask blank and reflective photomask
Ayumi Goda, Tokyo (JP); and Norihito Fukugami, Tokyo (JP)
Assigned to TOPPAN INC., Tokyo (JP)
Appl. No. 17/615,083
Filed by TOPPAN INC., Tokyo (JP)
PCT Filed May 28, 2020, PCT No. PCT/JP2020/021196
§ 371(c)(1), (2) Date Nov. 29, 2021,
PCT Pub. No. WO2020/241780, PCT Pub. Date Dec. 3, 2020.
Claims priority of application No. 2019-102991 (JP), filed on May 31, 2019.
Prior Publication US 2022/0221784 A1, Jul. 14, 2022
Int. Cl. G03F 1/24 (2012.01); G03F 1/54 (2012.01)
CPC G03F 1/24 (2013.01) [G03F 1/54 (2013.01)] 18 Claims
 
1. A reflective photomask blank comprising:
a substrate;
a reflection part provided on the substrate and configured to reflect incident light; and
a low reflection part provided on the reflection part and configured to absorb incident light,
wherein the low reflection part has a multi-layer structure including at least two or more layers, and
an outermost layer of the low reflection part has a refractive index n equal to or more than 0.90 and an extinction coefficient k equal to or less than 0.02 with respect to extreme ultraviolet (EUV) light (where a wavelength is 13.5 nm),
wherein the outermost layer is constituted of a compound material in which an atomic number ratio of silicon (Si) to oxygen (O) is within a range of 1:1.5 to 1:2, and a total content of the silicon and the oxygen is 50% by atom or more of a whole compound material.