US 11,982,935 B2
Reflective mask blank for EUV lithography
Hirotomo Kawahara, Cupertino, CA (US); Hiroshi Hanekawa, Fukushima (JP); Toshiyuki Uno, Fukushima (JP); and Masafumi Akita, Tokyo (JP)
Assigned to AGC INC., Tokyo (JP)
Filed by AGC Inc., Tokyo (JP)
Filed on Nov. 17, 2021, as Appl. No. 17/529,124.
Application 17/529,124 is a continuation of application No. PCT/JP2020/020016, filed on May 20, 2020.
Claims priority of application No. 2019-095189 (JP), filed on May 21, 2019.
Prior Publication US 2022/0075256 A1, Mar. 10, 2022
Int. Cl. G03F 1/24 (2012.01); G03F 1/52 (2012.01); H01L 21/027 (2006.01); H01L 21/033 (2006.01)
CPC G03F 1/24 (2013.01) [G03F 1/52 (2013.01); H01L 21/0274 (2013.01); H01L 21/0332 (2013.01); H01L 21/0337 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A reflective mask blank for EUV lithography comprising a substrate and, formed on or above the substrate in the following order, a reflective layer for reflecting EUV light, a protective layer for the reflective layer, an absorption layer for absorbing EUV light, and a hard mask layer,
wherein the protective layer comprises ruthenium (Ru),
the absorption layer comprises tantalum (Ta),
the hard mask layer comprises chromium (Cr) and at least one of nitrogen (N) and oxygen (O), and
the hard mask layer has a film density of from 4.45 g/cm3 to 5.40 g/cm3.