This nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2017-123228 filed in JAPAN on Jun. 23, 2017, the entire contents of which are hereby incorporated by reference.

FIELD OF TEE INVENTION

The present invention relates to a compound, a resin, photoresist composition and a process for producing a photoresist pattern.

BACKGROUND OF THE INVENTION

JP2012-123376A1 mentions a composition which comprises a resin having a structural unit derived from the following compound.



JP2007-114412A1 mentions a composition which comprises a resin having a structural unit derived from the following compound.



SUMMARY OF THE INVENTION

The present invention relates to the followings:

<1> A compound represented by the formula (I):



wherein R1represents a hydrogen atom or a methyl group,

R2and R3independently each represent a hydrogen atom or a C1-C6 saturated hydrocarbon group,

R4represents a C1-C18 aliphatic hydrocarbon group having a C3-C24 alicyclic hydrocarbon moiety which aliphatic hydrocarbon group can have a substituent and in which a methylene group can be replaced by —O—, —S—, —CO— or —SO2— or

a C3-C24 alicyclic hydrocarbon group which can have a substituent and in which a methylene group can be replaced by —O—, —S—, —CO— or —SO2—.

<2> The compound according to <1>

wherein R4represents a C1-C6 aliphatic hydrocarbon group having a C3-C18 alicyclic hydrocarbon moiety which aliphatic hydrocarbon group can have a fluorine atom or a hydroxyl group and in which a methylene group can be replaced by —O—, —S— —CO— or —SO2—, or

a C3-C24 alicyclic hydrocarbon group which can have a fluorine atom or a hydroxyl group and in which a methylene group can be replaced by —O—, —S— —CO— or —SO2—.

<3> The compound according to <1>

wherein R3represents a hydrogen atom.

<4> A resin comprising a structural unit derived from the compound according to any one of <1> to <3>.

<5> The resin according to <4>

which further comprises a structural unit having an acid-labile group and being different from a structural unit derived from the compound represented by formula (I).

<6> A photoresist composition which comprises a resin according to <4> or <5> and an acid generator.

<7> The photoresist composition according to <6>

wherein the acid generator comprises a salt represented by the formula (B1):



wherein Qb1and Qb2independently each represent a fluorine atom or a C1-C6 perfluoroalkyl group,

Lb1represents a C1-C24 divalent saturated hydrocarbon group in which a methylene group can be replaced by —CO— or —O— and in which a hydrogen atom can be replaced by a fluorine atom or a hydroxyl group,

Y represents a methyl group in which a hydrogen atom can be replaced by a substituent or a C3-C18 alicyclic hydrocarbon group in which a hydrogen atom can be replaced by a substituent and in which a methylene group has been replaced by —O—, —SO2— or —CO—, and

Z+represents an organic cation.

<8> The photoresist composition according to <6> or <7> which further comprises a salt generating an acid weaker in acidity than an acid generated from the acid generator.

<9> The photoresist composition according to any one of <6> to <8> which further comprises a resin comprising a structural unit having a fluorine atom.

<10> A process for producing a photoresist pattern comprising the following steps (1) to (5):(1) a step of applying the photoresist composition according to any one of <6> to <9> on a substrate,(2) a step of forming a composition film by conducting drying,(3) a step of exposing the composition film to radiation,(4) a step of baking the exposed composition film, and(5) a step of developing the baked composition film, thereby forming a photoresist pattern.

