US 11,927,880 B2
Phase shift blankmask and photomask for EUV lithography
Yong-Dae Kim, Daegu-si (KR); Chul-Kyu Yang, Daegu-si (KR); Min-Kwang Park, Daegu-si (KR); and Mi-Kyung Woo, Daegu-si (KR)
Assigned to S&S TECH Co., Ltd., Daegu-si (KR)
Filed by S&S TECH Co., Ltd., Daegu-si (KR)
Filed on Jan. 10, 2022, as Appl. No. 17/572,390.
Claims priority of application No. 10-2021-0025384 (KR), filed on Feb. 25, 2021; application No. 10-2021-0077682 (KR), filed on Jun. 15, 2021; and application No. 10-2021-0077683 (KR), filed on Jun. 15, 2021.
Prior Publication US 2022/0269160 A1, Aug. 25, 2022
Int. Cl. G03F 1/24 (2012.01); G03F 1/26 (2012.01)
CPC G03F 1/24 (2013.01) [G03F 1/26 (2013.01)] 38 Claims
 
1. A blankmask for extreme ultraviolet lithography, comprising:
a substrate;
a reflective layer formed on the substrate; and
a phase shift layer formed on the reflective layer,
wherein the phase shift layer contains niobium (Nb) and tantalum (Ta),
wherein a content of tantalum (Ta) in the phase shift layer is 30 to 70 at %, and
wherein the phase shift layer has a relative reflectance of greater than 5% and lower than 20% with respect to the reflective layer in extreme ultraviolet exposure light having a wavelength of 13.5 nm.