US 11,940,725 B2
Phase shift blankmask and photomask for EUV lithography
Cheol Shin, Daegu-si (KR); Yong-Dae Kim, Daegu-si (KR); Jong-Hwa Lee, 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 (KR)
Filed by S&S TECH Co., Ltd., Daegu-si (KR)
Filed on Dec. 6, 2021, as Appl. No. 17/543,534.
Claims priority of application No. 10-2021-0011135 (KR), filed on Jan. 27, 2021; application No. 10-2021-0053875 (KR), filed on Apr. 26, 2021; and application No. 10-2021-0077681 (KR), filed on Jun. 15, 2021.
Prior Publication US 2022/0236635 A1, Jul. 28, 2022
Int. Cl. G03F 1/32 (2012.01); G03F 1/24 (2012.01)
CPC G03F 1/32 (2013.01) [G03F 1/24 (2013.01)] 34 Claims
OG exemplary drawing
 
1. A mask blank for extreme ultraviolet lithography, comprising:
a substrate;
a reflective layer formed on the substrate;
a capping layer formed on the reflective layer;
an etch stop layer formed on the capping layer; and
a phase shift layer formed on the reflective-layer etch stop layer;
wherein,
the capping layer is made of a material containing ruthenium (Ru),
the phase shift layer comprises ruthenium (Ru) and chromium (Cr), and
the etch stop layer is formed in a structure of two or more layers, an uppermost layer of the etch stop layer is made of a material containing tantalum (Ta) and oxygen (O), and a layer under the uppermost layer of the etch stop layer is made of a material containing tantalum and not containing oxygen (O).