Monomer, Resin for Photoresist, Photoresist Resin Composition, and Pattern Forming Method

Abstract

An object of the present invention is to provide a monomer useful in forming a resin for a photoresist having excellent swelling resistance. The resin for a photoresist of the present invention contains a polymerization unit represented by the following formula (Y). (In formula (Y), R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom, and A 1 represents a single bond or a linking group. When A 1 represents a linking group, A 1 and R X1 optionally bond to each other to form a ring. R X1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. n represents an integer of 0 to 5. When n is 2 or more, R X1 may be the same or different and may optionally bond to each other to form a ring. m represents an integer of 1 to 4.)

Description

Technical Field

[0001] The present invention relates to a monomer, a resin, a resin composition, and a pattern forming method. Background Art

[0002] In the manufacture of semiconductors, lithography technology for pattern formation has achieved a leap in innovation. Initially, i-rays and g-rays were used for exposure in lithography, and the line width of the pattern was relatively wide, so the capacity of the manufactured semiconductors was low. However, due to recent technological developments, it has become possible to use a KrF excimer laser with a shorter wavelength and an ArF excimer laser with an even shorter wavelength, and their line widths have become extremely fine.

[0003] In the exposure using a KrF excimer laser, novolak resins or styrene resins have been used. However, since these resins contain aromatic groups, there is a problem that they absorb the laser based on an ArF excimer laser. Therefore, in the exposure using an ArF excimer laser, a resin that does not contain an aromatic group (for example, a resin having an alicyclic skeleton) has been used instead of a resin containing an aromatic group. The resin mainly used in the exposure using an ArF excimer laser is an acrylic resin. This is based on the following mechanism: in the case of a resin composition using an acrylic resin containing a radiation-sensitive acid generator and (meth)acrylic acid protected by a protecting group as a monomer unit, the protecting group of the monomer unit is detached by the acid generated by exposure and becomes a carboxyl group, thereby becoming alkali-soluble.

[0004] Most of the currently used protecting groups are groups containing an alicyclic skeleton having no polarity, but their adhesion to the substrate is poor and their affinity for an alkali developing solution is lacking. Therefore, a large number of acrylic monomers containing an alicyclic skeleton having polarity (for example, a skeleton having an ester group) have been proposed. Among them, regarding the alicyclic skeleton having a lactone ring, its functionality has been highly evaluated and has been widely used (Patent Documents 1 and 2).

[0005] In addition, with the development of miniaturization, the demand for improving the line width variation of the formed pattern, which is called line width roughness (hereinafter referred to as "LWR"), has further increased. As one of the causes of LWR deterioration, swelling of the pattern caused by an alkali developing solution is cited, and as a solution to this problem, a method of using a resin containing a specific tertiary ester unit having a ring ether structure has been proposed (Patent Document 3).

[0006] Prior Art Documents

[0007] Patent Documents

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-026446

[0009] [Patent Document 2] Japanese Patent Laid-Open No. 10-274852

[0010] [Patent Document 3] WO 2007 / 094473 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] However, with respect to the above resin, since the swelling resistance (the property of suppressing the swelling of the pattern caused by the alkali developer) is insufficient, further improvement is required.

[0013] Accordingly, an object of the present invention is to provide a monomer useful for forming a resin having excellent swelling resistance. Another object of the present invention is to provide a resin having excellent swelling resistance and a resin composition containing the resin. Another object of the present invention is to provide a method capable of accurately forming a pattern having excellent swelling resistance and fineness by using the above resin composition.

[0014] Means for Solving the Problems

[0015] The present inventors conducted intensive studies to achieve the above object, and as a result, found that the swelling resistance can be improved by using a resin containing a polymerization unit having a specific structure. The present invention has been completed based on these findings.

[0016] That is, in the present invention, there is provided a resin for a photoresist, which contains a polymerization unit represented by the following formula (Y).

[0017] [Chemical Formula 1]

[0018]

[0019] (In the formula, R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom, A 1 represents a single bond or a linking group. When A 1 represents a linking group, A 1 and R X1 optionally bond to each other to form a ring, R X1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, n represents an integer of 0 to 5. When n is 2 or more, R X1 optionally are the same or different and optionally bond to each other to form a ring, and m represents an integer of 1 to 4.)

[0020] The resin preferably contains at least one polymerization unit selected from the polymerization unit represented by the following formula (Y1) and the polymerization unit represented by the following formula (Y2).

[0021] [Chemical Formula 2]

[0022]

[0023] (In the formula, R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom, R X2 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, n represents an integer of 0 to 5, and when n is 2 or more, R X2 are optionally the same or different and are optionally bonded to each other to form a ring.)

[0024] [Chemical formula 3]

[0025]

[0026] (In the formula, R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom, R X3 and R X4 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, R X3 and R X4 are optionally bonded to each other to form a ring.)

[0027] The resin preferably further contains at least one polymerization unit selected from the polymerization units represented by the following formulas (a1) to (a4),

[0028] [Chemical formula 4]

[0029]

[0030] (In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms optionally having a halogen atom, A represents a single bond or a linking group, R 2 to R 4 are the same or different and represent an alkyl group having 1 to 6 carbon atoms optionally having a substituent. Among them, R 2 and R 3 are optionally bonded to each other to form a ring, R 5 , R 6 are the same or different and represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms optionally having a substituent, R 7 represents a -COOR c group, the R c represents a tertiary hydrocarbon group, tetrahydrofuran group, tetrahydropyran group, or oxepanyl group optionally having a substituent, n represents an integer of 1 to 3, and R a is bonded to ring Z 1The substituents, which may be the same or different, represent an oxo group, an alkyl group, a hydroxy group optionally protected by a protecting group, a hydroxyalkyl group optionally protected by a protecting group, or a carboxyl group optionally protected by a protecting group, p represents an integer of 0 to 3, and ring Z 1 represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms.)

[0031] The resin preferably contains at least one polymer unit selected from the polymer units represented by the following formulas (b1) to (b5) (excluding those belonging to the polymer unit represented by formula (Y)).

[0032] [Chemical formula 5]

[0033]

[0034] (In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms optionally having a halogen atom, A represents a single bond or a linking group, X represents unbonded, methylene, ethylene, an oxygen atom, or a sulfur atom, Y represents methylene or a carbonyl group, Z represents a divalent organic group, V 1 to V 3 which may be the same or different, represent -CH 2 -, [-C(=O)-], or [-C(=O)-O-]. Among them, at least one of V 1 to V 3 is [-C(=O)-O-], and R 8 to R 14 which may be the same or different, represent a hydrogen atom, a fluorine atom, an alkyl group optionally having a fluorine atom, a hydroxy group optionally protected by a protecting group, a hydroxyalkyl group optionally protected by a protecting group, a carboxyl group optionally protected by a protecting group, or a cyano group.)

[0035] The resin preferably contains a polymer unit represented by the following formula (c1),

[0036] [Chemical formula 6]

[0037]

[0038] (In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms optionally having a halogen atom, A represents a single bond or a linking group, R b represents a hydroxy group optionally protected by a protecting group, a hydroxyalkyl group optionally protected by a protecting group, a carboxyl group optionally protected by a protecting group, or a cyano group, q represents an integer of 1 to 5, and ring Z 2 represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms.)

[0039] Furthermore, the present invention provides a resin composition containing at least the resin and a radiation-sensitive acid generator.

[0040] In addition, the present invention provides a method for forming a pattern, which at least includes the following steps: coating the composition on a substrate to form a coating film, exposing the coating film, and then performing alkali dissolution.

[0041] In addition, the present invention provides a monomer represented by the following formula (X):

[0042] [Chemical formula 7]

[0043]

[0044] (In the formula, R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom, A 1 represents a single bond or a linking group. When A 1 represents a linking group, A 1 and R X1 optionally bond to each other to form a ring. R X1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. n represents an integer from 0 to 5. When n is 2 or more, R X1 are optionally the same or different and optionally bond to each other to form a ring. m represents an integer from 1 to 4.)

[0045] The monomer is preferably a monomer represented by the following formula (X1) or a monomer represented by the following formula (X2).

[0046] [Chemical formula 8]

[0047]

[0048] (In the formula, R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom. R X2 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. n represents an integer from 0 to 5. When n is 2 or more, R X2 are optionally the same or different and optionally bond to each other to form a ring.)

[0049] [Chemical formula 9]

[0050]

[0051] (In the formula, R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom. R X3 and R X4 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. R X3 and R X4 optionally bond to each other to form a ring.)

[0052] Effects of the Invention

[0053] According to the present invention, a monomer useful for forming a resin excellent in swelling resistance can be provided. Further, a resin excellent in swelling resistance and a resin composition containing the resin can be provided. Furthermore, a method capable of precisely forming a fine pattern excellent in swelling resistance by using the above resin composition can be provided. Detailed Description of the Invention

[0054] <Monomer>

[0055] The monomer of the present invention is represented by the following formula (X).

[0056] [Chemical Formula 10]

[0057]

[0058] In formula (X), R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom, and A 1 represents a single bond or a linking group. When A 1 represents a linking group, A 1 and R X1 may optionally bond to each other to form a ring. R X1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. n represents an integer of 0 to 5. When n is 2 or more, R X1 may be the same or different and may optionally bond to each other to form a ring. m represents an integer of 1 to 4.

[0059] The halogen atom in R X is not particularly limited, but from the viewpoint of improving swelling resistance, a fluorine atom or a chlorine atom is preferable, and a fluorine atom is more preferable. In addition, the number of carbon atoms of the alkyl group in R X is not particularly limited as long as it is 1 to 6, preferably 1 to 3, and more preferably 1 or 2. That is, as the alkyl group having 1 to 6 carbon atoms substituted by a halogen atom in R X , from the viewpoint of improving swelling resistance, an alkyl group having 1 or 2 carbon atoms substituted by a fluorine atom such as fluoromethyl, difluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, 1,1,2,2,2-pentafluoroethyl, etc. is preferable, and trifluoromethyl is more preferable.

[0060] It should be noted that for the monomer represented by formula (X), the reason for the improvement in swelling resistance is not clear, but it is considered that by making R XR is a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom. The water repellency of the resin containing a polymerization unit derived from the above monomer (i.e., the polymerization unit represented by formula (Y)) is improved. As a result, the alkali developer is less likely to impregnate into the resin film, and the swelling of the pattern is suppressed.

[0061] R X1 The alkyl group in may have 1 to 6 carbon atoms and is not particularly limited. For example, it is preferably 1 to 4. R X1 The alkenyl group in may have 2 to 6 carbon atoms and is not particularly limited. For example, it is preferably 2 to 4. When n is 2 or more and R X1 are bonded to each other to form a ring, R X1 may also form a ring via an oxygen atom or a sulfur atom. In addition, the carbon atoms constituting the ring may form a double bond with adjacent carbon atoms. It should be noted that the number of carbon atoms constituting the ring is not particularly limited. For example, it is preferably 4 to 12, more preferably 4 to 10, and further preferably 4 to 6.

[0062] As the linking group in A 1 , for example, the following can be mentioned: alkylene, carbonyl (-C(=O)-), ether bond (-O-), ester bond (-C(=O)-O-), amide bond (-C(=O)-NH-), carbonate bond (-O-C(=O)-O-), and groups formed by linking multiple of these, etc. As the alkylene, for example, the following can be mentioned: methylene, methylmethylene, dimethylmethylene, ethylene, propylene, trimethylene and other linear or branched alkylene groups, 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, cyclohexylidene and other divalent alicyclic hydrocarbon groups (especially divalent cycloalkylene groups), etc. When A 1 is bonded to the α-position of the lactone ring, there is a tendency for the adhesion of the resin to the substrate to be improved.

[0063] When A 1 and R X1 are bonded to each other to form a ring, the ring may also form a ring via an oxygen atom or a sulfur atom. In addition, the carbon atoms constituting the ring may form a double bond with adjacent carbon atoms. It should be noted that the number of carbon atoms constituting the ring is not particularly limited and is preferably 4 to 12, more preferably 4 to 10, and further preferably 4 to 6.

[0064] The monomer of the present invention is not particularly limited. For example, the monomers represented by the following formulas (X1) and (X2) can be mentioned.

[0065] [Chemical formula 11]

[0066]

[0067] [Chemical formula 12]

[0068]

[0069] In formula (X1), R X is the same as described in formula (X), and represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom. R X2 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. n represents an integer from 0 to 5. When n is 2 or more, R X2 are optionally the same or different and are optionally bonded to each other to form a ring.

[0070] R X2 in the alkyl group only needs to have 1 to 6 carbon atoms, and there is no particular limitation. For example, 1 to 4 is preferred. R X2 in the alkenyl group only needs to have 2 to 6 carbon atoms, and there is no particular limitation. For example, 2 to 4 is preferred. When R X2 are bonded to each other to form a ring, R X2 can also form a ring via an oxygen atom or a sulfur atom. In addition, the carbon atoms constituting the ring can also form a double bond with adjacent carbon atoms. It should be noted that the number of carbon atoms constituting the ring is not particularly limited. For example, 4 to 12 is preferred, more preferably 4 to 10, and still more preferably 4 to 6.

[0071] In formula (X2), R X is the same as described in formula (X), and represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom. R X3 and R X4 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. R X3 and R X4 are optionally bonded to each other to form a ring.

[0072] R X3 and R X4 in the alkyl group only needs to have 1 to 6 carbon atoms, and there is no particular limitation. For example, 1 to 4 is preferred. R X3 and R X4 in the alkenyl group only needs to have 2 to 6 carbon atoms, and there is no particular limitation. For example, 2 to 4 is preferred. When R X3 and R X4 are bonded to each other to form a ring, R X3 and R X4 can also form a ring via an oxygen atom or a sulfur atom. In addition, the carbon atoms constituting the ring can also form a double bond with adjacent carbon atoms. It should be noted that the number of carbon atoms constituting the ring is not particularly limited. For example, 4 to 12 is preferred, more preferably 4 to 10, and still more preferably 4 to 6.

[0073] The monomer represented by the formula (X1) is not particularly limited, and examples thereof include the monomers represented by the following formula (X3) and the following formula (X4).

[0074] [Chemical formula 13]

[0075]

[0076] [Chemical formula 14]

[0077]

[0078] In the formula (X3), R X , which is the same as the description in the formula (X), represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom. R X5 and R X6 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. In addition, R X5 and R X6 optionally bond to each other to form a ring. The alkyl group of R X5 and R X6 only needs to have 1 to 6 carbon atoms, and there is no particular limitation. For example, 1 to 4 are preferred, and 1 to 2 are more preferred. In addition, the alkenyl group only needs to have 2 to 6 carbon atoms, and there is no particular limitation. For example, 2 to 4 are preferred.

[0079] In the formula (X4), R X , which is the same as the description in the formula (X), represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom. R X7 and R X8 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. The alkyl group of R X5 and R X6 only needs to have 1 to 6 carbon atoms, and there is no particular limitation. For example, 1 to 4 are preferred, and 1 to 2 are more preferred. In addition, the alkenyl group only needs to have 2 to 6 carbon atoms, and there is no particular limitation. For example, 2 to 4 are preferred.

[0080] As a representative example of the monomer represented by the formula (X), the monomer represented by the following formula can be cited.

[0081] [Chemical formula 15]

[0082]

[0083] The monomer represented by the above formula (X) can be synthesized by a known method. As the preparation method, there is no particular limitation. For example, it can be cited: an alcohol containing the lactone ring in the monomer represented by the formula (X) and the -A 1 -OH group bonded to the lactone ring, and a compound having R XEsterification reaction between the base and acrylic anhydride. The esterification reaction can preferably be carried out in the presence of a base such as diisopropylethylamine, triethylamine, dimethylethylamine, dimethylisopropylamine, diethylmethylamine, or diisopropylmethylamine.

[0084] <Resin>

[0085] The resin of the present invention exhibits high swelling resistance by containing the polymerization unit represented by formula (Y). Therefore, it can preferably be used as a resin for photoresist.

[0086] [Chemical formula 16]

[0087]

[0088] In formula (Y), R X , R X1 , A 1 , n and m are the same as those described in formula (X), and R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom. A 1 represents a single bond or a linking group. When A 1 represents a linking group, A 1 and R X1 optionally bond to each other to form a ring. R X1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. n represents an integer of 0 to 5. When n is 2 or more, R X1 are optionally the same or different and optionally bond to each other to form a ring. m represents an integer of 1 to 4.

[0089] The resin of the present invention is not particularly limited as long as it contains the polymerization unit represented by the above formula (Y). For example, it may contain at least one polymerization unit selected from the polymerization unit represented by the following formula (Y1) and the polymerization unit represented by the following formula (Y2).

[0090] [Chemical formula 17]

[0091]

[0092] [Chemical formula 18]

[0093]

[0094] In formulas (Y1) and (Y2), n, R X , R X2 , R X3 , R X4 are the same as those described in formulas (X1) and (X2).

[0095] As the polymerization unit represented by the formula (Y1), for example, the polymerization units represented by the following formulas (Y3) and (Y4) can be mentioned.

[0096] [Chemical formula 19]

[0097]

[0098] [Chemical formula 20]

[0099]

[0100] In the formulas (Y3) and (Y4), R X , R X5 , R X6 , R X7 and R X8 are the same as those described in the formulas (X3) and (X4).

[0101] The resin of the present invention may have a group that partially dissociates by the action of an acid to generate a polar group (sometimes referred to as an "acid-decomposable group"). Thus, the resin of the present invention increases in polarity under the action of an acid and increases in solubility in an alkaline developer.

[0102] As the polar group, for example, phenolic hydroxyl group, carboxyl group, fluorinated alcohol group (preferably hexafluoroisopropanol group), sulfonic acid group, sulfonamide group, sulfimide group, (alkylsulfonyl)(alkylcarbonyl)methylene, (alkylsulfonyl)(alkylcarbonyl)imide group, bis(alkylcarbonyl)methylene, bis(alkylcarbonyl)imide group, bis(alkylsulfonyl)methylene, bis(alkylsulfonyl)imide group, tris(alkylcarbonyl)methylene, tris(alkylsulfonyl)methylene and other acidic groups, alcoholic hydroxyl group, etc. can be mentioned. Among them, carboxyl group, fluorinated alcohol group (preferably hexafluoroisopropanol group), and sulfonic acid group are preferred.

[0103] As the acid-decomposable group, it is preferably a group in which a hydrogen atom of the polar group is replaced by a group that dissociates by an acid. As the acid-decomposable group, for example, -C(R I )(R II )(R III ), -C(R IV )(R V )(OR VI ), etc. In the above formulas, R I to R III , R VI each independently represent an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R IV and R V each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R I to R IIIAt least two of the groups can be bonded to each other to form a ring. In addition, R IV and R V can also be bonded to each other to form a ring.

[0104] The number of carbon atoms of the acid-decomposable group is not particularly limited, preferably 4 or more, more preferably 5 or more. The upper limit of the number of carbon atoms is not particularly limited, preferably 20.

[0105] The alkyl group of R I ~R VI is preferably an alkyl group having 1 to 8 carbon atoms, and examples thereof include methyl, ethyl, propyl, n-butyl, sec-butyl, tert-butyl, hexyl, octyl and the like.

[0106] The cycloalkyl group of R I ~R VI can be a monocyclic hydrocarbon group or a polycyclic (bridged) hydrocarbon group. As the monocyclic hydrocarbon group, a cycloalkyl group having 3 to 8 carbon atoms is preferred, and examples thereof include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl and the like. As the polycyclic hydrocarbon group, a cycloalkyl group having 6 to 20 carbon atoms is preferred, and examples thereof include adamantyl, norbornyl, isobornyl, camphenyl, dicyclopentyl, α-pinene group, tricyclodecyl, tetracyclododecyl, androstanyl and the like. It should be noted that at least one carbon atom in the cycloalkyl group can be substituted with a heteroatom such as an oxygen atom.

[0107] The aryl group of R I ~R VI is preferably an aryl group having 6 to 14 carbon atoms, and examples thereof include phenyl, naphthyl, anthryl and the like.

[0108] The aralkyl group of R I ~R VI is preferably an aralkyl group having 7 to 12 carbon atoms, and examples thereof include benzyl, phenethyl, naphthylmethyl and the like.

[0109] The alkenyl group of R I ~R VI is preferably an alkenyl group having 2 to 8 carbon atoms, and examples thereof include vinyl, allyl, butenyl, cyclohexenyl and the like.

[0110] As the ring formed by bonding at least two of the groups in R I ~R III , and the ring formed by bonding R IV and R V , a cycloalkane ring is preferred. As the cycloalkane ring, monocyclic cycloalkane rings such as cyclopropane ring, cyclobutane ring, cyclopentane ring, cyclohexane ring are preferred; polycyclic cycloalkane rings such as norbornane ring, tricyclodecane ring, tetracyclododecane ring, adamantane ring are preferred.

[0111] It should be noted that I ~R VI the alkyl group, cycloalkyl group, aryl group, aralkyl group, alkenyl group, and the cycloalkane ring in

[0112] As the acid-decomposable group, a tert-butyl group, a tert-amyl group, and groups represented by the following formulas (I) to (IV) are preferable.

[0113] [Chemical formula 21]

[0114]

[0115] R in the formulas (I) to (IV) 2 ~R 7 , R a , n, p, and ring Z 1 respectively represent the same ones as R 2 ~R 7 , R a , n, p, and ring Z 1 in the following formulas (a1) to (a4).

[0116] The acid-decomposable group may be provided via a spacer group. As the spacer group, those the same as the linking group exemplified and described as A in the following formula (1) are represented.

[0117] The resin of the present invention preferably contains an acid-decomposable group as a polymer unit having an acid-decomposable group. As such a polymer unit having an acid-decomposable group, for example, a polymer unit represented by the following formula (1) can be cited.

[0118] [Chemical formula 22]

[0119]

[0120] In the above formula (1), R 1 represents the acid-decomposable group. Further, in the above formula (1), R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms optionally having a halogen atom. As the halogen atom, for example, a chlorine atom, a bromine atom, an iodine atom, etc. can be cited. As the alkyl group having 1 to 6 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, tert-pentyl, hexyl, etc. can be cited. As the alkyl group having 1 to 6 carbon atoms having a halogen atom, groups in which one or more hydrogen atoms constituting the alkyl group are substituted with a halogen atom (halo(C 1-6 )) alkyl), etc. can be cited.

[0121] In the above formula (1), A represents a single bond or a linking group. Examples of the linking group include: a carbonyl group (-C(=O)-), an ether bond (-O-), an ester bond (-C(=O)-O-), an amide bond (-C(=O)-NH-), a carbonate bond (-O-C(=O)-O-), a group formed by linking multiple of these, and a group formed by bonding an alkylene group and these groups. Examples of the alkylene group include: a linear or branched alkylene group such as a methylene group, a methylmethylene group, a dimethylmethylene group, an ethylene group, a propylene group, a trimethylene group, a divalent alicyclic hydrocarbon group (especially a divalent cycloalkylene group) such as a 1,2-cyclopentylene group, a 1,3-cyclopentylene group, a cyclopentylidene group, a 1,2-cyclohexylene group, a 1,3-cyclohexylene group, a 1,4-cyclohexylene group, a cyclohexylidene group, etc.

[0122] As the polymerization unit represented by the above formula (1), preferably, it contains at least one polymerization unit selected from the polymerization units represented by the following formulas (a1) to (a4). It should be noted that "at least one polymerization unit selected from the polymerization units represented by the formulas (a1) to (a4)" is sometimes referred to as "monomer unit a".

[0123] [Chemical formula 23]

[0124]

[0125] In the polymerization units represented by the above formulas (a1) to (a4), R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms optionally having a halogen atom, in the same manner as R in the above formula (1), and A represents a single bond or a linking group. As A in the above formulas (a1) to (a4), preferably, it is a group formed by bonding a single bond, an alkylene group, and a carbonyloxy group (alkylene-carbonyloxy). R 2 ~R 4 are the same or different and represent an alkyl group having 1 to 6 carbon atoms optionally having a substituent. It should be noted that R 2 and R 3 may also bond to each other to form a ring. R 5 、R 6 are the same or different and represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms optionally having a substituent. R 7 represents a -COOR c group, and the R c represents a tertiary hydrocarbon group optionally having a substituent, a tetrahydrofuran group, a tetrahydropyran group, or an oxepanyl group. n represents an integer of 1 to 3. When n is 2 or 3, R 7 may be the same or different from each other. R a is bonded to the ring Z 1The substituents, which may be the same or different, represent an oxo group, an alkyl group, a hydroxy group optionally protected by a protecting group, a hydroxyalkyl group optionally protected by a protecting group, or a carboxyl group optionally protected by a protecting group. p represents an integer from 0 to 3. Ring Z 1 represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms. When p is 2 or 3, R a may be the same or different, optionally.

[0126] As the alkyl group in the R a , examples thereof include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, tert-pentyl, n-hexyl and the like.

[0127] As the hydroxyalkyl group in the R a , examples thereof include hydroxyalkyl groups such as hydroxymethyl, 2-hydroxyethyl, 1-hydroxyethyl, 3-hydroxypropyl, 2-hydroxypropyl, 4-hydroxybutyl, 6-hydroxyhexyl and the like, which are hydroxy C 1-6 alkyl groups.

[0128] As the protecting group optionally possessed by the hydroxy group and the hydroxyalkyl group in the R a , examples thereof include C 1-4 alkyl groups such as methyl, ethyl, tert-butyl; a group that forms an acetal bond together with the oxygen atom constituting the hydroxy group (for example, C 1-4 alkyl-O-C 1-4 alkyl); a group that forms an ester bond together with the oxygen atom constituting the hydroxy group (for example, acetyl, benzoyl, etc.).

[0129] As the protecting group for the carboxyl group in the R a , examples thereof include C 1-6 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, tert-pentyl, hexyl; 2-tetrahydrofuranyl, 2-tetrahydropyranyl, 2-oxacycloheptyl and the like.

[0130] As the alkyl group having 1 to 6 carbon atoms in the R 2 to R 6 , examples thereof include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, tert-pentyl, hexyl and the like. Among them, C 1-4 alkyl is preferred, C 1-3 alkyl is more preferred, and C 1-2 alkyl is even more preferred.

[0131] As the R 2 to R 6The substituent optionally possessed by the alkyl group having 1 to 6 carbon atoms, for example, may include: a halogen atom, a hydroxyl group, a substituted hydroxyl group (for example, a C 1-4 alkoxy group such as methoxy, ethoxy, propoxy, etc.), a cyano group, etc. As the alkyl group having 1 to 6 carbon atoms with a substituent, for example, may include: trifluoromethyl, 2,2,2-trifluoroethyl, etc., in which one or more of the hydrogen atoms constituting the alkyl group are substituted by a halogen atom, a halogenated (C 1-6 ) alkyl group, hydroxymethyl, 2-hydroxyethyl, methoxymethyl, 2-methoxyethyl, ethoxymethyl, 2-ethoxyethyl, cyanomethyl, 2-cyanoethyl, etc.

[0132] When R 2 and R 3 are bonded to each other to form a ring, as the ring, for example, may include an alicyclic hydrocarbon ring having 3 to 12 carbon atoms which optionally has a substituent.

[0133] As the tertiary hydrocarbon group in the R c , for example, may include tert-butyl, tert-pentyl, etc.

[0134] As the substituent optionally possessed by the tertiary hydrocarbon group in the R c , for example, may include: a halogen atom, a hydroxyl group, a substituted hydroxyl group (for example, a C 1-4 alkoxy group such as methoxy, ethoxy, propoxy, etc.), a cyano group, etc.

[0135] As the alicyclic hydrocarbon ring having 3 to 20 carbon atoms in the ring Z 1 , for example, may include: a cycloalkane ring such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cyclooctane ring, etc., having about 3 to 20 members (preferably 3 to 15 members, particularly preferably 5 to 12 members); a cycloalkene ring such as a cyclopropene ring, a cyclobutene ring, a cyclopentene ring, a cyclohexene ring, etc., having about 3 to 20 members (preferably 3 to 15 members, particularly preferably 5 to 10 members), etc., a monocyclic alicyclic hydrocarbon ring; an adamantane ring; a norbornane ring, a norbornene ring, a borane ring, an isoborane ring, a tricyclo[5.2.1.0 2,6 decane ring, a tetracyclo[4.4.0.1 2,5 .1 7,10 dodecane ring, etc., a ring containing a norbornane ring or a norbornene ring; a polycyclic aromatic condensed ring such as a perhydroindene ring, a decahydronaphthalene ring (perhydro naphthalene ring), a perhydrofluorene ring (tricyclo[7.4.0.0 3,8 tridecane ring), a perhydroanthracene ring, etc., which is a hydrogenated ring (preferably a completely hydrogenated ring); a bicyclic, tricyclic, tetracyclic, etc., bridged hydrocarbon ring such as a tricyclo[4.2.2.1 2,5 undecane ring, etc. (for example, a bridged hydrocarbon ring having about 6 to 20 carbon atoms), etc., a bridged ring hydrocarbon ring having about 2 to 6 rings, etc.

[0136] As a specific example of the monomer unit a, monomer units represented by the following formula etc. may be mentioned. In the monomer unit represented by the following formula, R d represents a methyl group or a hydrogen atom, and R e represents a methyl group or a hydrogen atom. Further, the bonding position of R e relative to the alicyclic hydrocarbon ring is not particularly limited, and one or more R e may be bonded to any carbon atom among the carbon atoms constituting the alicyclic hydrocarbon ring. When there are two or more R e in the monomer unit represented by the following formula, the two or more R e are optionally the same or different. The monomer unit a can be introduced into the resin by polymerizing the corresponding unsaturated carboxylic acid ester.

[0137] [Chemical formula 24]

[0138]

[0139] [Chemical formula 25]

[0140]

[0141] As the polymer unit represented by the above formula (1), in addition to the polymer unit represented by the monomer unit a, a polymer unit corresponding to an unsaturated carboxylic acid ester containing a lactone ring in which the oxygen atom constituting the ester bond is bonded to the β-position of the lactone ring and the α-position of the lactone ring has at least one hydrogen atom (however, excluding the polymer unit corresponding to the monomer unit b described below) can be used.

[0142] The polymer unit represented by the above formula (1) may be only one kind, or may be a combination of two or more kinds. As the polymer unit represented by the above formula (1), it is preferable to contain at least one polymer unit selected from the polymer units represented by the above formulas (a1) to (a4). Further, regarding the polymer unit represented by the above formula (1), at least one polymer unit selected from the polymer units represented by the above formulas (a1) to (a4) and the polymer unit represented by the above formula (1) other than at least one polymer unit selected from the polymer units represented by the above formulas (a1) to (a4) (other polymer units represented by the formula (1)) may be used in combination. As the other polymer unit represented by the formula (1), it is preferable that R 1 is a group having a tertiary hydrocarbon group (for example, tert-butyl group, tert-pentyl group, etc.) in the formula (1).

[0143] Further, the resin of the present invention preferably contains at least [-C(=O)-O-], [-S(=O) 2-O-] or an alicyclic skeleton of [-C(=O)-O-C(=O)-]. When the alicyclic skeleton is included, high substrate adhesion and etching resistance can be imparted by the resin. The resin of the present invention preferably contains the above alicyclic skeleton as the polymer unit having an alicyclic skeleton. It should be noted that sometimes the polymer unit containing the at least [-C(=O)-O-], [-S(=O) 2 -O-] or an alicyclic skeleton of [-C(=O)-O-C(=O)-] is referred to as "monomer unit b". It should be noted that those belonging to the polymer unit represented by formula (Y) are not included in monomer unit b.

[0144] Regarding the monomer unit b, preferably, it contains at least one polymer unit selected from the polymer units represented by the following formulas (b1) to (b5) (excluding those belonging to the polymer unit represented by formula (Y)). In the following formulas (b1) to (b5), R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms optionally having a halogen atom, and A represents a single bond or a linking group. X represents unbonded, methylene, ethylene, an oxygen atom, or a sulfur atom. Y represents methylene or a carbonyl group. Z represents a divalent organic group (for example, the alkylene groups exemplified and described as the alkylene groups optionally contained in A in the polymer units represented by formulas (a1) to (a4) (especially a linear alkylene group having 1 to 3 carbon atoms), etc. V 1 ~V 3 are the same or different and represent -CH 2 -, [-C(=O)-], or [-C(=O)-O-]. And, V 1 ~V 3 at least one of which is [-C(=O)-O-]. R 8 ~R 14 are the same or different and represent a hydrogen atom, a fluorine atom, an alkyl group optionally having a fluorine atom, a hydroxyl group optionally protected by a protecting group, a hydroxyalkyl group optionally protected by a protecting group, a carboxyl group optionally protected by a protecting group, or a cyano group.

[0145] [Chemical formula 26]

[0146]

[0147] As R and A in the polymer units represented by formulas (b1) to (b5), the same examples as R and A in the polymer units represented by formulas (a1) to (a4) can be cited. In addition, as the alkyl group, the hydroxyl group optionally protected by a protecting group, the hydroxyalkyl group optionally protected by a protecting group, and the carboxyl group optionally protected by a protecting group in R 8 ~R 14 in the polymer units represented by formulas (b1) to (b5), the same as R in the polymer units represented by formulas (a1) to (a4) can be cited.a Those same examples in

[0148] As the R 8 ~R 14 Alkyl groups having fluorine atoms in , for example, groups in which one or more of the hydrogen atoms constituting the alkyl group such as trifluoromethyl, 2,2,2-trifluoroethyl, etc. are substituted by fluorine atoms [fluoro(C 1-6 )alkyl] etc.

[0149] In the polymerization units represented by the above formulas (b1) to (b4), R 8 ~R 11 Can each have one or more, preferably 1 to 3. In addition, in the polymerization units represented by the above formulas (b1) to (b4), when there are two or more of the above R 8 ~R 11 In the case of , the two or more of the above R 8 ~R 11 Can be the same or different from each other.

[0150] In the monomer unit b, from the viewpoints of being able to impart excellent substrate adhesion and etching resistance to the resin, having excellent solubility in an alkali developer, and being able to form a fine pattern with high precision, it is preferably: a polymerization unit represented by the formula (b1) and R 8 Is an electron-withdrawing group such as a cyano group, a group having an amide group, a group having an imide group, or a fluoro(C 1-6 )alkyl; a polymerization unit represented by the formula (b2); a polymerization unit represented by the formula (b3) and Y is a carbonyl group; a polymerization unit represented by the formula (b4); and a polymerization unit represented by the formula (b5).

[0151] In the above formula (b1), when R 8 Is an electron-withdrawing group such as a cyano group, a group having an amide group, a group having an imide group, or a fluoro(C 1-6 )alkyl, it is particularly preferred that the R 8 Is at least bonded to the carbon atom marked * in the above formula (b1).

[0152] As a specific example of the monomer unit b, a polymerization unit represented by the following formula can be cited. In the monomer unit represented by the following formula, R d Represents a methyl group or a hydrogen atom. The monomer unit b can be introduced into the resin by polymerizing a corresponding unsaturated carboxylic acid ester.

[0153] [Chemical formula 27]

[0154]

[0155] [Chemical formula 28]

[0156]

[0157] The resin of the present invention may also have monomer unit c. The monomer unit c is a polymerization unit represented by the following formula (c1). When the resin of the present invention contains the monomer unit c as a polymerization unit, high transparency and etching resistance can be imparted by the resin for photoresist. In the formula, R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms optionally having a halogen atom. A represents a single bond or a linking group. R b represents a hydroxyl group optionally protected by a protecting group, a hydroxyalkyl group optionally protected by a protecting group, a carboxyl group optionally protected by a protecting group, or a cyano group, where a hydroxyl group and a cyano group are preferred. q represents an integer of 1 to 5. Ring Z 2 represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms. When q is an integer of 2 to 5, 2 to 5 R b may be the same or different from each other.

[0158] [Chemical formula 29]

[0159]

[0160] As R and A in the polymerization unit represented by the formula (c1), the same examples as R and A in the polymerization units represented by the formulas (a1) to (a4) can be cited. In addition, as the hydroxyl group optionally protected by a protecting group, the hydroxyalkyl group optionally protected by a protecting group, and the carboxyl group optionally protected by a protecting group in R b in the polymerization unit represented by the formula (c1), the same examples as those in R a in the polymerization units represented by the formulas (a1) to (a4) can be cited.

[0161] Ring Z in the polymerization unit represented by the formula (c1) 2 represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms, preferably, for example: cycloalkane rings such as a cyclohexane ring and a cyclooctane ring having about 6 to 20 members (preferably 6 to 15 members, particularly preferably 6 to 12 members); monocyclic alicyclic hydrocarbon rings such as a cyclohexene ring having about 6 to 20 members (preferably 6 to 15 members, particularly preferably 6 to 10 members); adamantane ring; norbornane ring, norbornene ring, borane ring, isoborane ring, tricyclo[5.2.1.0 2,6 decane ring, tetracyclo[4.4.0.1 2,5 .1 7,10 dodecane ring and other rings containing a norbornane ring or a norbornene ring; polycyclic aromatic condensed rings such as a perhydroindene ring, a decahydronaphthalene ring (perhydro-naphthalene ring), a perhydrofluorene ring (tricyclo[7.4.0.0 3,8 tridecane ring), and a perhydroanthracene ring which are formed by hydrogenating polycyclic aromatic condensed rings (preferably rings formed by complete hydrogenation); tricyclo[4.2.2.1 2,5Bridged hydrocarbon rings such as bicyclic, tricyclic, and tetracyclic rings including undecane rings (e.g., bridged hydrocarbon rings having about 6 to 20 carbon atoms), etc., and bridged-ring hydrocarbon rings having about 2 to 6 rings, etc. As the ring Z 2 , preferably includes a ring containing a norbornane ring or a norbornene ring, and an adamantane ring.

[0162] As a specific example of the monomer unit c, a polymerization unit represented by the following formula can be cited. In the polymerization unit represented by the following formula, R d represents a methyl group or a hydrogen atom. The monomer unit c can be introduced into the resin by polymerizing the corresponding unsaturated carboxylic acid ester.

[0163] [Chemical formula 30]

[0164]

[0165] The resin of the present invention more preferably includes the polymerization unit represented by the above formula (Y), and includes at least one monomer unit selected from the monomer unit a, the monomer unit b, and the monomer unit c. In this case, in the resin of the present invention, with respect to all monomer units (polymerization units) constituting the resin, the content of the polymerization unit represented by the above formula (Y) is, for example, 5 to 95 mol%, preferably 10 to 90 mol%, more preferably 20 to 80 mol%, and further preferably 30 to 60 mol%. In addition, the content of the monomer unit a with respect to all monomer units constituting the resin is, for example, 10 to 90 mol%, preferably 20 to 80 mol%, more preferably 30 to 70 mol%, and further preferably 40 to 60 mol%. In addition, when the resin of the present invention has the monomer unit b, the content of the monomer unit b with respect to all monomer units constituting the resin is, for example, 0 to 80 mol%, preferably 10 to 60 mol%, and more preferably 20 to 50 mol%. In addition, when the resin of the present invention has the monomer unit c, the content of the monomer unit c with respect to all monomer units constituting the resin is, for example, 0 to 40 mol%, preferably 1 to 30 mol%, and more preferably 3 to 25 mol%.

[0166] In addition, the weight average molecular weight (Mw) of the resin of the present invention is, for example, 1000 to 50000, preferably 2000 to 30000, more preferably 3000 to 20000, and particularly preferably 4000 to 15000. The molecular weight distribution of the resin of the present invention (the ratio of the weight average molecular weight to the number average molecular weight: Mw / Mn) is not particularly limited as long as it is 2.5 or less, and is, for example, 1.0 to 2.2, preferably 1.0 to 2.0. It should be noted that in this specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) can be measured, for example, by GPC using polystyrene as a standard substance, and are preferably measured by the method used in the examples.

[0167] The acid value of the resin of the present invention is, for example, 0.10 mmol / g or less, preferably 0.05 mmol / g or less, and more preferably 0.03 mmol / g or less. When the acid value is 0.10 mmol / g or less, the acid-decomposable groups in the resin are protected and do not detach, so it has excellent corrosion resistance and good stability over time. It should be noted that the lower limit of the acid value is, for example, 0 mmol / g.

[0168] <Manufacturing method of resin>

[0169] The manufacturing method of the resin of the present invention is not particularly limited. For example, a dropping polymerization method can be cited. As the dropping polymerization method, for example, a method of polymerizing monomers by dropping a monomer or a solution containing monomers in the presence of a polymerization initiator can be cited. Specifically, it can include: [1] a step of dropping a solution containing a polymerization initiator and monomers; [2] a step of dropping a monomer or a solution containing monomers into a solution containing a polymerization initiator. In addition, in addition to the polymerization initiator, the dropping polymerization method can be carried out in the presence of a chain transfer agent. As the monomers, for example, the monomers of the present invention and the monomers corresponding to the monomer unit a, the monomer unit b, and the monomer unit c can be cited.

[0170] As the polymerization initiator, known radical polymerization initiators can be used. For example, azo compounds, peroxide compounds, and redox compounds can be cited. Particularly preferred are: dimethyl 2,2'-azobisisobutyrate, azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), tert-butyl peroxyneopentanoate, di-tert-butyl peroxide, isobutyryl peroxide, lauroyl peroxide, succinic peroxide, dicyclohexyl peroxide, di-n-propyl peroxydicarbonate, tert-butyl allyl monoperoxycarbonate, benzoyl peroxide, hydrogen peroxide, ammonium persulfate, etc.

[0171] The amount of the polymerization initiator used is only required to be the amount necessary to obtain a resin having a desired molecular weight distribution. For example, it is 0.05 to 120 moles, preferably 0.1 to 50 moles, and more preferably 0.5 to 10 moles relative to the total amount of monomers (100 moles). In addition, relative to the total amount of monomers (100 parts by weight), the amount of the polymerization initiator used is, for example, 0.01 to 30 parts by weight, preferably 0.2 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight.

[0172] As a chain transfer agent, known chain transfer agents that can be used in free radical polymerization can be used. For example, the following can be cited: mercaptans (n-dodecyl mercaptan, n-octyl mercaptan, n-butyl mercaptan, tert-butyl mercaptan, n-dodecyl mercaptan, mercaptoethanol, mercaptopropanol, triethylene glycol dithiol, etc.), thiocarboxylic acids and their esters (mercaptoacetic acid, thiobenzoic acid, mercaptoacetic acid, thiomalic acid, etc., and their alkyl esters, etc.), alcohols (isopropyl alcohol, etc.), amines (dibutylamine, etc.), hypophosphites (sodium hypophosphite, etc.), α-methylstyrene dimer, terpinolene, myrcene, limonene, α-pinene, β-pinene, etc.).

[0173] The amount of the chain transfer agent used is not particularly limited. Relative to the total amount of the monomers (100 moles), it is preferably 0.001 to 100 moles, more preferably 0.01 to 50 moles, further preferably 0.1 to 30 moles, and particularly preferably 1 to 10 moles. In addition, relative to the total amount of the monomers (100 parts by weight), the amount of the chain transfer agent used is not particularly limited, preferably 0.1 to 100 parts by weight, more preferably 0.5 to 50 parts by weight, and further preferably 1 to 25 parts by weight.

[0174] The polymerization step can be carried out without a solvent or in the presence of a polymerization solvent. As the polymerization solvent, for example, the following can be cited: glycol solvents (the glycol compounds), ester solvents, ketone solvents, ether solvents, amide solvents, sulfoxide solvents, monohydric alcohol solvents (the monohydric alcohol compounds), hydrocarbon solvents, and their mixed solvents. As glycol solvents, in addition to the glycol compounds, the following can be cited: propylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, etc. Ester solvents can include: lactate solvents such as ethyl lactate; propionate solvents such as methyl 3-methoxypropionate; acetate solvents such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, etc. Ketone solvents can include: acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, cyclohexanone, etc. Ether solvents can include: chain ethers such as diethyl ether, diisopropyl ether, dibutyl ether, dimethoxyethane; cyclic ethers such as tetrahydrofuran, dioxane, etc. Amide solvents can include N,N-dimethylformamide, etc. Sulfoxide solvents can include dimethyl sulfoxide, etc. Hydrocarbon solvents can include: aliphatic hydrocarbons such as pentane, hexane, heptane, octane; cycloaliphatic hydrocarbons such as cyclohexane, methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, etc. As preferred polymerization solvents, the following can be cited: glycol solvents such as propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate; ester solvents such as ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, cyclohexanone; and their mixed solvents.

[0175]

[0176] ​The addition of the monomer-containing solution can be continuous addition (a method of addition over a certain period of time) or intermittent addition (a method of addition in multiple portions). In addition, regarding the rate of the addition, etc., it can be changed more than once during the addition.

[0177] The total addition time of the monomer-containing solution (the time from the start of the addition to the end of the addition) varies depending on the polymerization temperature, the type of monomer, etc., and is usually 1 to 10 hours, preferably 2 to 9 hours, more preferably 3 to 8 hours. As the temperature of the monomer-containing solution to be added, it is preferably 40°C or lower. When the monomer-containing solution is 40°C or lower, there is a tendency that it is more difficult to generate polymers with too large a molecular weight in the initial stage of the reaction. In addition, regarding the monomer-containing solution, depending on the type of monomer, crystallization may sometimes occur due to excessive cooling.

[0178] The polymerization temperature is not particularly limited, for example, it is 30 to 150°C, preferably 50 to 120°C, more preferably 60 to 100°C. It should be noted that the polymerization temperature can be changed more than once during the polymerization within the above polymerization temperature range.

[0179] In the polymerization step, a ripening time can be set after the addition is completed. The ripening time is not particularly limited, for example, it is preferably 0.5 to 10 hours, more preferably 1 to 5 hours.

[0180] For the polymer produced in the polymerization step, it can be recovered, for example, by precipitation (including reprecipitation). For example, the polymerization solution (polymer stock solution) can be added to a solvent (precipitation solvent) to precipitate the polymer, or the polymer can be redissolved in an appropriate solvent and the solution can be added to a solvent (reprecipitation solvent) for reprecipitation, or a solvent (reprecipitation solvent, polymerization solvent) can also be added to the polymerization solution (polymer stock solution) for dilution, thereby obtaining the target polymer. The precipitation or reprecipitation solvent can be any solvent among organic solvents and water, and can also be a mixed solvent.

[0181] As the precipitation or reprecipitation solvent, known or commonly used solvents can be used, and there is no particular limitation. In addition, the precipitation or reprecipitation solvent can be the same solvent as the above polymerization solvent or a different solvent. Examples of the precipitation or reprecipitation solvent include: the organic solvents exemplified as the polymerization solvent (glycol solvents, ester solvents, ketone solvents, ether solvents, amide solvents, sulfoxide solvents, monohydric alcohol solvents, hydrocarbon solvents); halogenated hydrocarbons (halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, etc.); nitro compounds (nitromethane, nitroethane, etc.); nitriles (acetonitrile, benzonitrile, etc.); carbonates (dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, etc.); carboxylic acids (acetic acid, etc.); mixed solvents containing these solvents, etc.

[0182] Among them, as the precipitation or reprecipitation solvent, a solvent containing at least a hydrocarbon (especially aliphatic hydrocarbons such as hexane, heptane) or an alcohol (especially methanol, ethanol, propanol, isopropanol, butanol, etc.) is preferred. In such a solvent containing at least a hydrocarbon, the ratio of the hydrocarbon (e.g., aliphatic hydrocarbons such as hexane, heptane) to other solvents (e.g., ester solvents such as ethyl acetate, etc.) is, for example, the former / latter (volume ratio; 25 °C) = 10 / 90 to 99 / 1, preferably the former / latter (volume ratio: 25 °C) = 30 / 70 to 98 / 2, more preferably the former / latter (volume ratio: 25 °C) = 50 / 50 to 97 / 3.

[0183] In addition, as the precipitation or reprecipitation solvent, a mixed solvent of an alcohol (especially methanol) and water, or a mixed solvent of a glycol solvent (especially polyethylene glycol) and water is also preferred. The ratio of the organic solvent (alcohol or glycol solvent) to water at this time (volume ratio; 25 °C) is, for example, the former / latter (volume ratio; 25 °C) = 10 / 90 to 99 / 1, preferably the former / latter (volume ratio: 25 °C) = 30 / 70 to 98 / 2, more preferably the former / latter (volume ratio: 25 °C) = 50 / 50 to 97 / 3.

[0184] For the polymer obtained by precipitation (including reprecipitation), a rinsing treatment and a treatment of washing while dispersing the polymer by a solvent and stirring (sometimes called "re-slurrying treatment") can be carried out as needed. A rinsing treatment can also be carried out after the re-slurrying treatment. By re-slurrying the polymer formed by polymerization with a solvent and rinsing, residual monomers, low molecular weight oligomers, etc. attached to the polymer can be effectively removed.

[0185] In the production method of the present invention, among them, as the re-slurrying treatment and rinsing treatment solvent, a solvent containing at least a hydrocarbon (especially aliphatic hydrocarbons such as hexane, heptane), an alcohol (especially methanol, ethanol, propanol, isopropanol, butanol, etc.), or an ester (especially ethyl acetate, etc.) is preferred.

[0186] After the precipitation (including reprecipitation), repulping treatment, or rinsing treatment, the solvent can be removed, for example, by decantation, filtration, etc. as needed, and a drying treatment can be carried out.

[0187] <Resin composition>

[0188] The resin composition of the present invention contains at least the resin of the present invention and a radiation-sensitive acid generator.

[0189] As the radiation-sensitive acid generator, a conventional or well-known compound that can effectively generate an acid by exposure to radiation such as visible light, ultraviolet light, far ultraviolet light, electron beam, X-ray, etc. can be used, and it is a compound containing a mother nucleus and the generated acid. As the mother nucleus, for example, iodine salt, sulfonium salt (including tetrahydrothiophene salt), salt, diazonium salt, pyridine salt, etc. salt compounds, sulfonimide compounds, sulfone compounds, sulfonate compounds, disulfonyldiazomethane compounds, disulfonylmethane compounds, oxime sulfonate compounds, hydrazine sulfonate compounds, etc. In addition, as the acid generated by the exposure, for example, alkyl or fluoroalkyl sulfonic acid, alkyl or fluoroalkyl carboxylic acid, alkyl or fluoroalkyl sulfonimide acid, etc. can be cited. These can be used alone or in combination of two or more.

[0190] The amount of the radiation-sensitive acid generator used can be appropriately selected according to the strength of the acid generated by irradiation with radiation, the ratio of each repeating unit in the resin, etc. For example, it can be selected from the range of 0.1 to 30 parts by weight, preferably 1 to 25 parts by weight, more preferably 2 to 20 parts by weight based on 100 parts by weight of the resin.

[0191] The resin composition can be prepared, for example, by mixing the resin and the radiation-sensitive acid generator in a resist solvent. As the resist solvent, the glycol solvents, ester solvents, ketone solvents, and their mixed solvents exemplified as the polymerization solvents can be used.

[0192] The resin concentration of the resin composition is, for example, 3 to 40% by weight. The resin composition can also contain alkali-soluble components such as alkali-soluble resins (for example, novolak resins, phenolic resins, imide resins, carboxyl group-containing resins), colorants (for example, dyes), etc.

[0193] <Pattern formation method>

[0194] After the resin composition of the present invention is coated on a substrate or a base plate and dried, a latent image pattern is formed by exposing the coating film (resist film) through a given mask (or further performing post-exposure baking after exposure), and then alkali dissolution is carried out, whereby a pattern excellent in swelling resistance and fine can be formed with high precision.

[0195] Examples of the substrate or the base plate include: silicon wafers, metals, plastics, glasses, ceramics, etc. Coating of the resin composition can be carried out using conventional coating mechanisms such as spin coaters, dip coaters, roll coaters, etc. The thickness of the coating film is preferably, for example, 0.05 to 20 μm, more preferably 0.1 to 2 μm.

[0196] During exposure, radiation such as visible light, ultraviolet rays, far ultraviolet rays, electron beams, X-rays, etc. can be used.

[0197] An acid is generated from a radiation-sensitive acid generator by exposure. Through this acid, protecting groups (acid-decomposable groups) such as carboxyl groups of polymer units (repeating units having acid-decomposable groups) in the resin composition that become alkali-soluble under the action of the acid are rapidly detached, and carboxyl groups and the like that contribute to dissolution are generated. Thus, by developing with an alkali developer, a given pattern can be formed with high precision.

[0198] Examples

[0199] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. It should be noted that the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) of the resin were determined by GPC measurement (gel permeation chromatography) using tetrahydrofuran solvent. Polystyrene was used as a standard sample, and a refractometer (refractive index detector; RI detector) was used as a detector. In addition, for GPC measurement, a chromatographic column formed by connecting three columns (trade name “KF-806L”) manufactured by Showa Denko K.K. in series was used, and the measurement was carried out under the conditions of a column temperature of 40 °C, an RI temperature of 40 °C, and a tetrahydrofuran flow rate of 0.8 mL / minute. The molecular weight distribution (Mw / Mn) was calculated from the above measurement values.

[0200] Example 1 (Preparation of monomer A)

[0201] According to the method described in J.Chem.Soc.Perkin Trans.1(1999),(23),p.3469, 3-hydroxyhexahydro-2H-cyclopenta[b]furan-2-one was obtained.

[0202] Dissolve 14.8 g of 3-hydroxyhexahydro-2H-cyclopenta[b]furan-2-one obtained in 148 g of THF, add 1.27 g of DMAP (N,N-dimethyl-4-aminopyridine), 14.0 g of sodium 2-fluoropropenoate, and 7.0 mg of p-methoxyphenol. After heating the solution to 40 °C, divide 39.9 g of EDCI·HCl (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) into 5 portions and add them, and stir at 40 °C for 30 minutes. After dropping 79.8 g of 10% hydrochloric acid, add 148 g of ethyl acetate and 148 g of water. After separating the organic phase, wash it three times with 148 g of water, and perform drying and concentration (40 °C, 30 Torr) to obtain a crude product. Purify the crude product by silica gel column chromatography to obtain 10.9 g of monomer A shown by the following formula. The yield is 49%. In addition, 1 The spectral data of 1H-NMR are shown below.

[0203] [Chemical formula 31]

[0204]

[0205] [Spectral data]

[0206] 1 1H-NMR (DMSO-d 6 ) δ 5.88 (d, 1H), 5.84 (d, 1H), 5.75 (m, 1H), 5.05 (t, 1H), 3.15 (m, 1H), 1.88 (m, 2H), 1.62 (m, 4H)

[0207] Example 2 (Preparation of monomer B)

[0208] Except that 3-hydroxyhexahydro-2H-cyclopenta[b]furan-2-one was changed to α-hydroxy-γ-butyrolactone (Tokyo Chemical Industry Co., Ltd. industrial product), 10.0 g of monomer B shown by the following formula was obtained by the same method as in Example 1. The yield was 55%. In addition, 1 The spectral data of 1H-NMR are shown below.

[0209] [Chemical formula 32]

[0210]

[0211] [Spectral data]

[0212] 1 1H-NMR (DMSO-d 6 ) δ 5.88 (d, 1H), 5.84 (d, 1H), 5.47 (m, 1H), 4.30 (m, 2H), 2.34 (m, 2H)

[0213] Example 3 (Preparation of Monomer C)

[0214] Except for changing sodium 2-fluoropropenoate to 2-(trifluoromethyl)acrylic acid (Tokyo Chemical Industry Co., Ltd. industrial product), 11.0 g of monomer C represented by the following formula was obtained by the same method as in Example 1. The yield was 40%. In addition, 1 The spectral data of 1H-NMR are shown below.

[0215] [Chemical Formula 33]

[0216]

[0217] [Spectral Data]

[0218] 1 1H-NMR (DMSO-d 6 ) δ6.93 (s, 1H), 6.64 (s, 1H), 5.75 (m, 1H), 5.04 (t, 1H), 3.15 (m, 1H), 1.85 (m, 2H), 1.60 (m, 4H)

[0219] Example 4 (Preparation of Resin A)

[0220] In a round-bottomed flask equipped with a reflux tube, a magnetic stirrer, and a three-way stopcock, 113.33 g of propylene glycol monomethyl ether acetate and 113.33 g of methyl ethyl ketone were added under a nitrogen atmosphere, and the temperature was maintained at 80 °C. While stirring, a solution obtained by mixing 22.5 g (0.11 mol) of monomer A, 27.5 g (0.11 mol) of 1-(adamantan-1-yl)-1-methylethyl methacrylate (monomer D), 3.1 g of dimethyl 2,2'-azobisisobutyrate [manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601"], 28.33 g of propylene glycol monomethyl ether acetate, and 28.33 g of methyl ethyl ketone was added dropwise at a constant rate over 5 hours. After the dropwise addition was completed, the reaction solution was stirred for an additional 2 hours.

[0221] After the polymerization reaction was completed, it was added dropwise with stirring to a mixed solution (25 °C) of 10 times the amount of heptane and ethyl acetate at a weight ratio of 9:1. The resulting precipitate was separated by filtration and dried under reduced pressure to obtain 42.2 g of the desired polymer. As a result of analyzing the recovered polymer by GPC, Mw (weight-average molecular weight) was 10,500, and the molecular weight distribution (Mw / Mn) was 1.80.

[0222] Example 5 (Preparation of Resin B)

[0223] In a round-bottomed flask equipped with a reflux tube, a magnetic stir bar, and a three-way stopcock, 113.33 g of propylene glycol monomethyl ether acetate and 113.33 g of methyl ethyl ketone were added under a nitrogen atmosphere. The temperature was maintained at 80 °C, and while stirring, a solution prepared by mixing 18.9 g (0.11 mol) of monomer B, 6.4 g (0.03 mol) of 3-hydroxyadamantan-1-yl methacrylate (monomer E), 24.7 g (0.14 mol) of 1-ethylcyclopentan-1-yl methacrylate (monomer F), 5.9 g of dimethyl 2,2'-azobis(2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601"], 28.33 g of propylene glycol monomethyl ether acetate, and 28.33 g of methyl ethyl ketone was added dropwise at a constant rate over 5 hours. After the addition was completed, the reaction solution was stirred for an additional 2 hours.

[0224] After the polymerization reaction was completed, the reaction solution was added dropwise with stirring to a 10-fold amount of a mixture of heptane and ethyl acetate at a weight ratio of 9:1 (25 °C). The resulting precipitate was separated by filtration and dried under reduced pressure to obtain 36.0 g of the desired polymer. As a result of analyzing the recovered polymer by GPC, the Mw (weight-average molecular weight) was 7200, and the molecular weight distribution (Mw / Mn) was 1.70.

[0225] Example 6 (Preparation of Resin C)

[0226] In a round-bottomed flask equipped with a reflux tube, a magnetic stir bar, and a three-way stopcock, 113.33 g of propylene glycol monomethyl ether acetate and 113.33 g of methyl ethyl ketone were added under a nitrogen atmosphere. The temperature was maintained at 80 °C, and while stirring, a solution prepared by mixing 25.1 g (0.10 mol) of monomer C, 24.9 g (0.10 mol) of 1-(adamantan-1-yl)-1-methylethyl methacrylate (monomer D), 3.1 g of dimethyl 2,2'-azobis(2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601"], 28.33 g of propylene glycol monomethyl ether acetate, and 28.33 g of methyl ethyl ketone was added dropwise at a constant rate over 5 hours. After the addition was completed, the reaction solution was stirred for an additional 2 hours.

[0227] After the polymerization reaction was completed, the reaction solution was added dropwise with stirring to a 10-fold amount of a mixture of heptane and ethyl acetate at a weight ratio of 9:1 (25 °C). The resulting precipitate was separated by filtration and dried under reduced pressure to obtain 42.8 g of the desired polymer. As a result of analyzing the recovered polymer by GPC, the Mw (weight-average molecular weight) was 10200, and the molecular weight distribution (Mw / Mn) was 1.85.

[0228] Comparative Example 1 (Preparation of Resin D)

[0229] In a round-bottom flask equipped with a reflux tube, a magnetic stir bar, and a three-way stopcock, 113.33 g of propylene glycol monomethyl ether acetate and 113.33 g of methyl ethyl ketone were added under a nitrogen atmosphere. The temperature was maintained at 80 °C, and a solution prepared by mixing 22.2 g (0.11 mol) of 2-oxabicyclo[3.3.0]octan-3-one-4-yl methacrylate (monomer G), 27.8 g (0.11 mol) of 1-(adamantan-1-yl)-1-methylethyl methacrylate (monomer D), 2.1 g of dimethyl 2,2'-azobis(2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601"], 28.33 g of propylene glycol monomethyl ether acetate, and 28.33 g of methyl ethyl ketone was added dropwise at a constant rate over 5 hours while stirring. After the addition was complete, the reaction solution was stirred for an additional 2 hours.

[0230] After the polymerization reaction was completed, the reaction solution was added dropwise with stirring to a 10-fold amount of a mixture of heptane and ethyl acetate (9:1 by weight) at 25 °C. The resulting precipitate was separated by filtration and dried under reduced pressure to obtain 45.0 g of the desired polymer. As a result of analyzing the recovered polymer by GPC, the Mw (weight-average molecular weight) was 10,000 and the molecular weight distribution (Mw / Mn) was 1.84.

[0231] Comparative Example 2 (Preparation of Resin E)

[0232] In a round-bottom flask equipped with a reflux tube, a magnetic stir bar, and a three-way stopcock, 113.33 g of propylene glycol monomethyl ether acetate and 113.33 g of methyl ethyl ketone were added under a nitrogen atmosphere. The temperature was maintained at 80 °C, and a solution prepared by mixing 18.6 g (0.11 mol) of 2-oxotetrahydrofuran-3-yl methacrylate (monomer H), 6.5 g (0.03 mol) of 3-hydroxyadamantan-1-yl methacrylate (monomer E), 24.9 g (0.14 mol) of 1-ethylcyclopentan-1-yl methacrylate (monomer F), 4.1 g of dimethyl 2,2'-azobis(2-methylpropionate) [manufactured by Wako Pure Chemical Industries, Ltd., trade name "V-601"], 28.33 g of propylene glycol monomethyl ether acetate, and 28.33 g of methyl ethyl ketone was added dropwise at a constant rate over 5 hours while stirring. After the addition was complete, the reaction solution was stirred for an additional 2 hours.

[0233] After the polymerization reaction was completed, the reaction solution was added dropwise with stirring to a 10-fold amount of a mixture of heptane and ethyl acetate (9:1 by weight) at 25 °C. The resulting precipitate was separated by filtration and dried under reduced pressure to obtain 39.8 g of the desired polymer. As a result of analyzing the recovered polymer by GPC, the Mw (weight-average molecular weight) was 7400 and the molecular weight distribution (Mw / Mn) was 1.72.

[0234] The resin prepared in Example 4 above has a polymerization unit represented by the following formula.

[0235] [Chemical formula 34]

[0236]

[0237] The resin prepared in Example 5 above has a polymerization unit represented by the following formula.

[0238] [Chemical formula 35]

[0239]

[0240] The resin prepared in Example 6 above has a polymerization unit represented by the following formula.

[0241] [Chemical formula 36]

[0242]

[0243] The resin prepared in Comparative Example 1 above has a polymerization unit represented by the following formula.

[0244] [Chemical formula 37]

[0245]

[0246] The resin prepared in Comparative Example 2 above has a polymerization unit represented by the following formula.

[0247] [Chemical formula 38]

[0248]

[0249] [Measurement of film thickness before contact with alkali developer]

[0250] Resin solutions were prepared by dissolving Resins A to E obtained in Examples 4 to 6 and Comparative Examples 1 and 2 in propylene glycol monomethyl ether acetate and adjusting the solid content concentration to 10%. The above resin solutions were applied onto 10-cm silicon wafers by spin coating, and pre-baked at 100 °C for 60 seconds on a hot plate to form resist resin films. After immersing half of the silicon wafers in a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (hereinafter referred to as alkali developer) for 120 seconds, the film thicknesses of the immersed and non-immersed portions were measured by atomic force microscopy (AFM).

[0251] [Evaluation of swelling resistance]

[0252] Let the film thickness of the immersed portion be "X (nm)" and the film thickness of the non-immersed portion be "Y (nm)", and the film thickness increase rate "Z (%)" before and after immersion in the alkali developer was calculated by the following formula.

[0253] Z(%) = (Y - X) × 100 / X

[0254] [Table 1]

[0255]

[0256] From the evaluation results, it can be understood that the resin for photoresist of the present invention (Examples 4 to 6) has excellent swelling resistance with respect to the alkali developing solution. Therefore, it can be expected that the resin for photoresist of the present invention has excellent corrosion resistance.

Claims

1. A resin for a photoresist, which contains a polymerization unit derived from any one of the monomers represented by the following formula, 2. The resin for a photoresist according to claim 1, which further contains at least one polymerization unit selected from the polymerization units represented by the following formulas (a1) to (a4), In formulas (a1) to (a4), R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may optionally have a halogen atom, A represents a single bond or a linking group, R 2 ~R 4 are the same or different and represent an alkyl group having 1 to 6 carbon atoms which may optionally have a substituent, and R 2 and R 3 may optionally bond to each other to form a ring, R 5 、R 6 are the same or different and represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may optionally have a substituent, R 7 represents a -COOR c group, where the R c represents a tertiary hydrocarbon group, tetrahydrofuran group, tetrahydropyran group, or oxepanyl group which may optionally have a substituent, n represents an integer of 1 to 3, R a is a substituent bonded to ring Z 1 and are the same or different and represent an oxo group, an alkyl group, a hydroxy group optionally protected by a protecting group, a hydroxyalkyl group optionally protected by a protecting group, or a carboxyl group optionally protected by a protecting group, p represents an integer of 0 to 3, and ring Z 1 represents an alicyclic hydrocarbon ring having 3 to 20 carbon atoms.

3. The resin for a photoresist according to claim 2, which further contains at least one polymerization unit selected from the polymerization units represented by the following formulas (b1) to (b5), wherein, except for the polymerization unit belonging to the polymerization unit represented by the following formula (Y), In formulas (b1) to (b5), R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may optionally have a halogen atom, A represents a single bond or a linking group, X represents an unbonded group, a methylene group, an ethylene group, an oxygen atom, or a sulfur atom, Y represents a methylene group or a carbonyl group, Z represents a divalent organic group, V 1 to V 3 are the same or different and represent -CH 2 -, [-C(=O)-], or [-C(=O)-O-], where at least one of V 1 to V 3 is [-C(=O)-O-], and R 8 to R 14 are the same or different and represent a hydrogen atom, a fluorine atom, an alkyl group which may optionally have a fluorine atom, a hydroxyl group which may optionally be protected by a protecting group, a hydroxyalkyl group which may optionally be protected by a protecting group, a carboxyl group which may optionally be protected by a protecting group, or a cyano group. In formula (Y), R X represents a halogen atom or an alkyl group having 1 to 6 carbon atoms substituted by a halogen atom, A 1 represents a single bond or a linking group. When A 1 represents a linking group, A 1 and R X1 optionally bond to each other to form a ring. R X1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms. n represents an integer of 0 to 5. When n is 2 or more, R X1 are optionally the same or different and optionally bond to each other to form a ring. m represents an integer of 1 to 4.

4. The resin for a photoresist according to claim 2 or 3, which further contains the polymerization unit represented by the following formula (c1), In formula (c1), R represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms which may optionally have a halogen atom, A represents a single bond or a linking group, R b represents a hydroxyl group which may optionally be protected by a protecting group, a hydroxyalkyl group which may optionally be protected by a protecting group, a carboxyl group which may optionally be protected by a protecting group, or a cyano group, q represents an integer of 1 to 5, and ring Z 2 represents an alicyclic hydrocarbon ring having 6 to 20 carbon atoms.

5. A resin composition for a photoresist, which contains at least: the resin for a photoresist according to claim 2 or 3, and a radiation-sensitive acid generator.

6. A pattern forming method, which at least includes the following steps: Coating the resin composition for a photoresist according to claim 5 on a substrate to form a coating film, exposing the coating film, and then performing alkali dissolution.

7. A monomer, which is any one of the monomers represented by the following formula,

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