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## POSITIVE RESIST COMPOSITION FOR EUV LITHOGRAPHY AND METHOD OF FORMING RESIST PATTERN 

[0001] The present disclosure relates to a positive resist composition for EUV (extreme ultraviolet) lithography and a method of forming a resist pattern using EUV. 

[0002] Polymers that display increased solubility in a developer after undergoing main chain scission through irradiation with ionizing radiation, such as an electron beam, or short-wavelength light, such as ultraviolet light, are conventionally used as main chain scission-type positive resists in fields such as semiconductor production. 

[0003] Specifically, Patent Literature (PTL) 1, for example, discloses a positive resist formed of an a-methyl› styrene-methyl a-chloroacrylate copolymer as a main chain scission-type positive resist, whereas PTL 2, for example, discloses a positive resist formed of an a-methylstyrene-2, 2,2-trifluoroethyl a-chloroacrylate copolymer as a main chain scission-type positive resist. In PTL 1 and 2, resist patterns are formed by irradiating resist films formed of these positive resists with electron beams. 

[0004] Moreover, in recent years, EUV lithography using extreme ultraviolet light (EUV) has been attracting attention as a technique that enables formation of fine patterns and has a small proximity effect during exposure compared to when an electron beam or the like is used. Non-Patent Literature (NPL) 1, for example, evaluates patterning performance during exposure using extreme ultraviolet light for a resist film formed using a positive resist composition that contains an a-methylstyrene-methyl a-chloroacrylate copolymer. 

[0005] PTL 1: JP-HS-3636B 

[0006] PTL 2: WO2017/130872Al 

[0007] NPL 1: Roberto Fallica (and 6 others), "Litho› graphic performance of ZEP520A and mr-PosEBR resists exposed by electron beam and extreme ultraviolet lithogra› phy", Journal of Vacuum Science & Technology B, October 2017 

[0008] However, resist films formed using the conven› tional positive resists described above have low sensitivity to extreme ultraviolet light and leave room for improvement in terms of enabling efficient formation of a resist pattern. 

[0009] Accordingly, an object of the present disclosure is to provide a positive resist composition for EUV lithography that can form a resist film having high sensitivity to extreme ultraviolet light and to also provide a method that enables efficient formation of a resist pattern using extreme ultra› violet light. 

## TECHNICAL FIELD 

## BACKGROUND 

## CITATION LIST 

## Patent Literature 

## Non-Patent Literature 

## SUMMARY 

## Technical Problem 

[0010] The inventor conducted diligent studies with the aim of achieving the object set forth above. The inventor reached a new finding that a resist film formed using a positive resist composition that contains a specific copoly› mer including 5 or more fluorine atoms has high sensitivity to extreme ultraviolet light and that a resist pattern can be efficiently obtained by exposing the resist film using extreme ultraviolet light. In this manner, the inventor completed the present disclosure. 

[0011] Specifically, the present disclosure aims to advan› tageously solve the problem set forth above, and a presently disclosed positive resist composition for EUV lithography comprises: a copolymer including a monomer unit (A) represented by general formula (I), shown below, 

where, in general formula (I), R 1 is an organic group including 5 or more fluorine atoms, and a monomer unit (B) represented by general formula (II), shown below, 

where, in general formula (II), R 2 is a hydrogen atom, a fluorine atom, an unsubstituted alkyl group, or a fluorine atom-substituted alkyl group, R 3 is a hydrogen atom, an unsubstituted alkyl group, or a fluorine atom-substituted alkyl group, p and q are each an integer of not less than O and not more than 5, and p+q=5; and 

[0012] a solvent. 

[0013] Through inclusion of a copolymer including the specific monomer unit (A) and monomer unit (B) set forth above as a positive resist in this manner, it is possible to form a resist film having high sensitivity to extreme ultraviolet light. 

[0014] Note that in a case in which p in general formula (II) is 2 or more, the plurality ofR $^{2 }$groups may be the same or different. Moreover, in a case in which q in general formula (II) is 2 or more, the plurality of R 3 groups may be the same or different. 

[0015] In the presently disclosed positive resist composi› tion for EUV lithography, R 1 is preferably a fluoroalkyl group. When R$^{1 }$is a fluoroalkyl group, it is possible to form a resist film having further improved sensitivity to extreme ultraviolet light. 

[0016] In the presently disclosed positive resist composi› tion for EUV lithography, a total number of fluorine atoms included in the monomer unit (A) and the monomer unit (B) 

## Solution to Problem 

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