US 12,422,751 B2
Positive resist composition and pattern forming process
Jun Hatakeyama, Joetsu (JP); and Masahiro Fukushima, Joetsu (JP)
Assigned to SHIN-ETSU CHEMICAL CO., LTD., Tokyo (JP)
Filed by Shin-Etsu Chemical Co., Ltd., Tokyo (JP)
Filed on May 4, 2022, as Appl. No. 17/736,267.
Claims priority of application No. 2021-090241 (JP), filed on May 28, 2021.
Prior Publication US 2023/0029535 A1, Feb. 2, 2023
Int. Cl. G03F 7/039 (2006.01); C08F 212/14 (2006.01); C08F 220/18 (2006.01); C08F 220/22 (2006.01); C08F 220/28 (2006.01); C08F 220/36 (2006.01)
CPC G03F 7/039 (2013.01) [C08F 212/24 (2020.02); C08F 220/1805 (2020.02); C08F 220/1806 (2020.02); C08F 220/1808 (2020.02); C08F 220/22 (2013.01); C08F 220/281 (2020.02); C08F 220/36 (2013.01)] 12 Claims
 
1. A positive resist composition comprising a base polymer comprising repeat units represented by the formula (a):

OG Complex Work Unit Chemistry
wherein RA is hydrogen or methyl,
X1 is a single bond, phenylene, naphthylene, or a C1-C12 linking group containing at least one moiety selected from an ester bond, ether bond and lactone ring, and
R is a tertiary hydrocarbyl group consisting of R1, R2 and a nitrobenzene ring, which is represented by the formula (a1):

OG Complex Work Unit Chemistry
wherein R1 and R2 are each independently a C1-C6 aliphatic hydrocarbyl group which may contain a heteroatom, R1 and R2 may bond together to form a ring with the carbon atom to which they are attached in which the nitrobenzene ring in the formula (a1) is separate from the ring formed of R1 and R2, R3 is hydrogen, halogen, a C1-C6 alkyl group, C1-C6 alkoxy group or C1-C6 acyloxy group, m is an integer of 1 to 4, n is 1 or 2, and the broken line designates a valence bond.