JP2003268057A - Graft copolymer for photoresist and chemical amplifying photoresist composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a graft polymer for a chemical amplifying photoresist suitable for ArF excimer laser beams and a photoresist composition. <P>SOLUTION: The graft polymer for the photoresist is prepared by copolymerizing a monomer having excellent dry etching resistance with a monomer having a protecting group deprotecting by actions of an acid generated by a photoreaction and preferably comprises (a) and/or (b). (a) a graft polymer has a backbone polymer moiety obtained by polymerizing a monomer component having the excellent dry etching resistance and a graft moiety prepared by polymerizing the monomer component having the protecting group deprotecting by the actions of the acid generated by the photoreaction and (b) a graft polymer has the backbone moiety obtained by polymerizing the monomer component having the protecting group deprotecting by the actions of the acid generated by the photoreaction and the graft moiety prepared by polymerizing the monomer component having the excellent dry etching properties. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a graft polymer for photoresist and a chemically amplified photoresist composition.

[0002]

2. Description of the Related Art In general, a positive photoresist uses a sensitizer having a quinonediazide group such as a naphthoquinonediazide compound and an alkali-soluble resin (for example, a novolac phenolic resin). The positive photoresist having such a composition exhibits high resolution when developed with an alkaline solution, and is used for manufacturing semiconductors such as IC and LSI and circuit substrates such as LCD. Further, since the novolac type phenol resin has a structure having many aromatic rings, it has high dry etching resistance and heat resistance against plasma dry etching after exposure. Up to now, many positive photoresists containing a novolac phenolic resin and a naphthoquinonediazide type photosensitizer have been developed and put into practical use, and great results have been achieved in line width processing up to about 0.3 μm to 2 μm.

However, in recent years, as the demand for higher integration of semiconductors has increased year by year, it has become necessary to process finer line widths.
The use of excimer light such as KrF, ArF, and F _{2 having} shorter wavelengths as a light source is under study. These lights are lights having wavelengths of 248 nm, 193 nm, and 157 nm, respectively, and the phenol resin has poor transparency due to absorption of light by its own aromatic ring, and light does not easily reach the bottom of the resist. Therefore, the amount of exposure at the bottom of the resist is reduced, and only a defective pattern with a taper or the like can be obtained after development. Therefore, polyhydroxystyrene for KrF, acrylic resin, cycloolefin resin for ArF, and fluorine resin for F ₂ are used as the base resin, and the acid generated from the photoacid generator is used as a catalyst. Amplification systems are being considered for application.

For the KrF excimer light, application of polyhydroxystyrene has been mainly studied, and its practical application has been advanced. However, studies are underway for further integration of semiconductors, and it is necessary to apply ArF excimer light having a shorter wavelength. In that case, polyhydroxystyrene cannot be used because it has no transparency,
New applications for acrylic resins and cycloolefin resins are being studied. When a norbornene / maleic anhydride resin, which is a cycloolefin resin, is used as a photoresist resin, the dry etching resistance and heat resistance are excellent, but the ArF wavelength (193
(nm) region, the difference in dissolution rate (dissolution contrast / resolution) between the exposed area and the unexposed area in an alkaline developer is insufficient, and the cycloolefin polymer is copolymerized with an acrylic monomer. Although a hybrid type polymer that has been used has been studied, the fact is that a polymer having satisfactory properties for a photoresist for ArF excimer light has not yet been found.

[0005]

The present invention relates to a graft polymer for photoresist and a chemically amplified photoresist composition, and in particular, a graft polymer for photoresist and chemical amplification suitable for lithography using ArF as a light source. Provided are photoresist compositions.

[0006]

The above objects are achieved by the present invention described in (1) to (12) below. (1) A graft polymer for photoresist, which is obtained by copolymerizing a monomer having excellent dry etching resistance with a monomer having a protective group that is deprotected by the action of an acid generated by a photoreaction. (2) The graft polymer for photoresist as described in (1) above, wherein the graft polymer for photoresist is composed of the following (a) and / or (a). (A) Graft formed by polymerizing a monomer component having excellent dry etching resistance in the trunk polymer portion, and polymerizing a monomer component having a protective group that is deprotected by the action of an acid generated by a photoreaction in the graft portion polymer. (A) A graft formed by polymerizing a monomer component having a protective group for deprotection by the action of an acid generated by a photoreaction in the trunk polymer portion, and polymerizing a monomer component having excellent dry etching resistance in the graft portion. polymer. (3) ATR having a halogen atom in the trunk polymer part
The graft polymer for photoresist according to the above (2), which contains a monomer that serves as an initiator of the P method (living radical polymerization method) and is bonded to the graft portion by at least a part thereof. (4) The number average molecular weights of the trunk polymer part and the graft part are 1,000 to 30,000, respectively, and the weight ratio of the trunk polymer part and the graft part is 90:10 to 10: 9.
The graft polymer for photoresist according to the above (2) or (3), which is 0. (5) The above (a) is a graft polymer represented by the general formula (I-1), and / or the above (a) is a graft polymer represented by the general formula (I-2). The graft polymer for photoresist according to any one of (2) to (4).

[Chemical 2] In the general formula (I-1) and the general formula (I-2), A,
B and C represent each monomer component. General formula (I-1)
Represents a graft polymer having a structure in which C is bonded as a graft portion via at least a part of B to a trunk polymer which is a copolymer of A and B. In addition, the general formula (I-2)
Represents a graft polymer having a structure in which A is bonded as a graft portion via at least a part of B to a trunk polymer which is a copolymer of B and C. General formula (I-1), (I-
In 2), A is at least one selected from the general formulas (II), (III) and (IV). In the general formula (II), R ₁ is selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group, an alkoxyalkyl group, a cycloalkyl group, a cyclic ether group and a cyclic ester group. is there.
l is 1 to 5, and when l is 2 to 5, two or more of the above may be used in combination. In general formula (IV), R ₂ is a hydrogen atom or a methyl group. R ₃ is a hydrogen atom, having 1 to 1 carbon atoms
It is selected from 15 alkyl groups, alkoxyalkyl groups, cycloalkyl groups, cyclic ether groups and cyclic ester groups. B is at least one selected from the general formulas (V) and (VI). In formula (V), R ₄ is a halogen atom, R ₅ is a hydrogen atom or a methyl group, and R ₆ is a carbon atom having 1 to 1 carbon atoms.
15 is an alkyl group. In general formula (VI), R ₇ is a hydrogen atom or a methyl group. R ₈ is a halogen atom. C is one or more selected from the general formulas (VII) and (VIII). In general formula (VII), R ₉ is a hydrogen atom or a methyl group. R ₁₀ is selected from a tertiary alkyl group having 4 to 15 carbon atoms, a tertiary alkoxyalkyl group, a tertiary cycloalkyl group, a tertiary cyclic ether group, and a tertiary cyclic ester group. In formula (VIII), R ₁₁ is selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group, an alkoxyalkyl group, a cycloalkyl group, a cyclic ether group and a cyclic ester group. m
Is 1 to 5, and when m is 2 to 5, two or more of the above may be used in combination. R ₁₂ is selected from a tertiary alkyl group having 4 to 15 carbon atoms, a tertiary alkoxyalkyl group, a tertiary cycloalkyl group, a tertiary cyclic ether group and a tertiary cyclic ester group. And a, b, and c showing the ratio of each monomer component of A, B, and C are a / (a + b + c) 0.1-0.8, b / (a + b + c) 0.01-0. 2, c / (a + b + c) is 0.1 to 0.8. (6) A in general formula (I-1) and general formula (I-2).
Is at least one selected from cyclohexyl acrylate, cyclohexyl methacrylate, norbornene, and maleic anhydride. The graft polymer for photoresist according to (5) above. (7) In general formula (I-1) and general formula (I-2), C
Is 2-methyl-2-adamantyl acrylate, 2-
Methyl-2-adamantyl methacrylate, tert-
The graft polymer for photoresist according to (5) or (6) above, which is one or more selected from butyl acrylate and tert-butyl methacrylate. (8) B in the general formula (I-1) and the general formula (I-2).
Is one or more selected from 2-bromoisobutenoyloxyethyl methacrylate, 2-bromoisobutenoyloxyethyl acrylate, 2-bromopropanoyloxyethyl methacrylate and 2-bromopropanoyloxyethyl acrylate (5 ) Thru | or the graft polymer for photoresists in any one of (7). (9) The graft polymer represented by the general formula (I-1) is obtained by polymerizing C on a backbone polymer composed of A and B by ATRP method (living radical polymerization method) through at least a part of B. The graft polymer for photoresist according to any one of (5) to (8) above, which is obtained. (10) The graft polymer represented by the general formula (I-2) is obtained by polymerizing A on a trunk polymer composed of B and C by ATRP method through at least a part of B. The graft polymer for photoresist according to any one of (5) to (8) above. (11) A chemically amplified photoresist composition containing the following (X) to (Z) as essential components. (X) Dissolves the graft polymer for photoresist according to any one of (1) to (10) above, (Y) a compound that generates an acid by the action of light, and (Z) (X) and (Y). solvent. (12) The chemical amplification type as described in (11) above, wherein the compound (Y) that generates an acid by the action of light is 1 to 20 parts by weight with respect to 100 parts by weight of the graft polymer (X) for photoresist. Photoresist composition.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a graft polymer for photoresist and a chemically amplified photoresist composition. First, the graft polymer for photoresist of the present invention will be described. (X) Graft Polymer for Photoresist The graft polymer for photoresist of the present invention (hereinafter,
"Polymer") is characterized by comprising a monomer having excellent dry etching resistance and a monomer having a protective group that is deprotected by the action of an acid generated by a photoreaction. Here, the monomer having excellent dry etching resistance means a monomer having resistance to oxygen or nitrogen plasma used in dry etching in a semiconductor manufacturing process. The monomer is not particularly limited,
Compounds having a cyclic structure such as aromatic rings, monocyclic hydrocarbons and polycyclic hydrocarbons are generally excellent, and examples thereof include compounds containing a cyclic alkyl group, a cyclic ether group and a cyclic ester group. . The monomer having a protective group that is deprotected by the action of the acid generated by the photoreaction is soluble in alkali by a chemical reaction such as elimination reaction using the acid generated by the action of light as a catalyst. Refers to monomers. The monomer is not particularly limited, and examples thereof include compounds having a structure in which a protecting group that is deprotected by the action of an acid has an ester bond with a tertiary carbon.

The polymer of the present invention is not particularly limited, but preferably comprises the following (a) and / or (a). Thereby, the characteristics of the photoresist can be improved. (A) Graft formed by polymerizing a monomer component having excellent dry etching resistance in the trunk polymer portion, and polymerizing a monomer component having a protective group that is deprotected by the action of an acid generated by a photoreaction in the graft portion polymer. (A) A graft formed by polymerizing a monomer component having a protective group for deprotection by the action of an acid generated by a photoreaction in the trunk polymer portion, and polymerizing a monomer component having excellent dry etching resistance in the graft portion. polymer.

The molecular weight of the polymer of the present invention is not particularly limited, but the number average molecular weight of each of the trunk polymer portion and the graft portion is preferably 1,000 to 30,000,
More preferably, it is 1500-15000. If the number average molecular weight of the polymer is less than the lower limit, the heat resistance may decrease, and if it exceeds the upper limit, the sensitivity of the polymer may decrease. The molecular weight can be controlled by adjusting the monomer concentration, the polymerization initiator concentration, the reaction temperature and the like when synthesizing the polymer. In particular,
If it is desired to obtain a low molecular weight polymer, it is possible to use a chain transfer agent. As an example of the chain transfer agent,
Examples thereof include thiols and halogenated hydrocarbons. Further, when polymerizing the graft part, a monomer having a halogen atom and serving as an initiator of the ATRP method (living radical polymerization method) is introduced into the trunk polymer part, and at least a part of the monomer is used as a branching starting point. When the ATRP method of polymerizing the monomer constituting the is applied, it is possible to control the molecular weight of the graft portion by adjusting the addition amount of the monomer. The number average molecular weight of the polymer is calculated based on a calibration curve prepared using a polystyrene standard substance by gel permeation chromatography (GPC) measurement. G
The PC measurement was carried out using tetrahydrofuran as an elution solvent at a flow rate of 1.0 ml / min and a column temperature of 40 ° C. Main body: TOSOH HLC-8020, detector: TOSOH UV-8011, analytical column: Showa Denko SHODEX KF-802 / 1, KF-80
3/1 and KF-805 / 1 were used respectively.
When the living radical polymerization method (ATRP method) is applied, the number average molecular weight of the graft part is the amount of the monomer component constituting the graft part,
It can be determined by dividing by the number of monomers that serve as the initiator of the RP method, and converting this by calculation based on a calibration curve prepared using a polystyrene standard substance. The amount of the monomer component constituting the graft part is calculated from the amount of the monomer of the graft part charged in the reaction system during the polymerization reaction and its reaction rate, and the reaction rate is determined by measuring the amount of the unreacted monomer by gas chromatography. I asked. Then, the number of monomers having a halogen atom and serving as an initiator of the ATRP method is similarly calculated from the amount of the monomer serving as an initiator charged in the reaction system during the polymerization reaction and the reaction rate thereof, and the reaction rate is unreacted. It was determined by measuring the amount of the monomer by gas chromatography.

The polymer of the present invention is not particularly limited, but the weight ratio of the trunk polymer part to the graft part is 9
It is preferably 0:10 to 10:90. More preferably, it is 80/20 to 20/80. If the amount is out of the above range, the effect of the graft polymer is diminished, and the superiority in photoresist characteristics may be impaired as compared with a general random polymer.

The polymer of the present invention is not particularly limited,
The (a) is a graft polymer represented by the general formula (I-1), and / or the (a) is a graft polymer represented by the general formula (I-2). Is preferred. In general formula (I-1) and general formula (I-2), A, B, and C show each monomer component. The general formula (I-1) represents a graft polymer having a structure in which C is bonded as a graft portion via at least a part of B to a trunk polymer which is a copolymer of A and B. Further, the general formula (I-2) represents a graft polymer having a structure in which A is bonded as a graft portion through at least a part of B to a trunk polymer which is a copolymer of B and C.

General formula (I-1) and general formula (I-2)
In the above, A is represented by the number of units "a" and is one or more selected from the general formulas (II), (III) and (IV). In the general formula (II), R ₁ is selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group, an alkoxyalkyl group, a cycloalkyl group, a cyclic ether group and a cyclic ester group. is there. l is 1 to 5, and when l is 2 to 5, two or more of the above may be used in combination. In general formula (IV), R ₂ is a hydrogen atom or a methyl group. R ₃ is selected from a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, an alkoxyalkyl group, a cycloalkyl group, a cyclic ether group and a cyclic ester group. A
The monomer component represented by is not particularly limited as long as it is within the above range, for example, norbornene, methyl norbornene, maleic anhydride, methyl allylate, methyl methacrylate, butyl allylate, butyl methacrylate, cyclohexyl allylate, Examples thereof include cyclohexyl methacrylate. Among these, at least one selected from cyclohexyl acrylate, cyclohexyl methacrylate, norbornene and maleic anhydride is preferable.

General formula (I-1) and general formula (I-2)
Among them, B is represented by the number of units “b” and is one or more selected from the general formulas (V) and (VI). Each of these is a monomer component having a halogen molecule and serving as an initiator of the ATRP method. In general formula (V), R ₄ is
A halogen atom, R ₅ is a hydrogen atom or a methyl group, and R ₆ is an alkyl group having 1 to 15 carbon atoms. R in the general formula (VI)
₇ is a hydrogen atom or a methyl group, and R ₈ is a halogen atom. The monomer component represented by B is not particularly limited as long as it is within the above range, and examples thereof include 2-bromoisobutenoyloxyethyl methacrylate, 2-bromoisobutenoyloxyethyl acrylate, and 2-bromopropanoyloxyethyl methacrylate. , 2-bromopropanoyloxyethyl acrylate, chloromethylstyrene, and the like. Among these, at least one selected from 2-bromoisobutenoyloxyethyl methacrylate, 2-bromoisobutenoyloxyethyl acrylate, 2-bromopropanoyloxyethyl methacrylate, and 2-bromopropanoyloxyethyl acrylate. Is preferred. As a result, the graft polymer portion can act promptly as an initiator and a graft polymer can be produced in good yield.

General formula (I-1) and general formula (I-2)
In the formula, C is represented by the number of units “c” and is one or more selected from the general formulas (VII) and (VIII).
In general formula (VII), R ₉ is a hydrogen atom or a methyl group. R ₁₀ is selected from a tertiary alkyl group having 4 to 15 carbon atoms, a tertiary alkoxyalkyl group, a tertiary cycloalkyl group, a tertiary cyclic ether group, and a tertiary cyclic ester group. In formula (VIII), R ₁₁ is selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group, an alkoxyalkyl group, a cycloalkyl group, a cyclic ether group and a cyclic ester group. m is 1 to 5, and when m is 2 to 5, two or more of the above may be used in combination. R ₁₂ is selected from a tertiary alkyl group having 4 to 15 carbon atoms, a tertiary alkoxyalkyl group, a tertiary cycloalkyl group, a tertiary cyclic ether group and a tertiary cyclic ester group. The monomer component represented by C is not particularly limited as long as it is within the above range. For example, acrylic acid ter
t-butyl, tert-butyl methacrylate, 2-methyl-2-adamantate acrylate, 2-methacrylic acid
Examples thereof include methyl-2-adamantate, tert-butyl norbornenecarboxylic acid, and 2-methyl-2-adamantate norbornenecarboxylic acid. Among these, 2-methyl-2-adamantyl acrylate, 2-
Methyl-2-adamantyl methacrylate, tert-
It is preferably at least one selected from butyl acrylate and tert-butyl methacrylate. As a result, it is possible to improve the sensitivity and the dry etching resistance.

When the polymer of the present invention is represented by general formula (I-1) or general formula (I-2), the numbers of units of A, B and C are represented by a, b and c, respectively. To be done.
Of these, the ratio of the number of A units to the total number of all units of A, B, and C (a / (a + b + c)) is not particularly limited, but is preferably 0.1 to 0.8, and more preferably Is 0.2 to 0.7. Thereby, good dry etching resistance can be exhibited. If the ratio of the number of A units is less than the above lower limit, the dry etching resistance of the photoresist may be insufficient, and the heat resistance tends to be poor. On the other hand, if the upper limit is exceeded, the sensitivity of the photoresist may be lowered. Also, the ratio of the number of B units (b / (a + b + c))
Is not particularly limited, but is preferably 0.01 to 0.2, and more preferably 0.02 to 0.18. This makes it possible to make the number of graft portions to the trunk polymer portion appropriate. If the ratio of the number of B units is less than the above lower limit value, the number of grafted parts will be too small, so that the features of the grafted part cannot be fully exhibited. On the other hand, when the amount exceeds the above upper limit, the number of grafted parts becomes too large and the characteristics of the trunk polymer part may not be sufficiently exhibited, and the molecular weight of the grafted part may decrease, resulting in a decrease in sensitivity and heat resistance. is there. Similarly, the ratio of the number of C units (c / (a + b + c)) is not particularly limited, but is preferably 0.1 to 0.8, and more preferably 0.2 to 0.7. Thereby, good sensitivity can be imparted to the polymer. When the ratio of the number of C units exceeds the above upper limit, the solubility in alkali becomes high when used as a photoresist, which may make it difficult to form an image and lower the resolution. Further, if it is less than the lower limit, the sensitivity tends to be low, and similarly it tends to be difficult to form an image. In the polymer of the present invention, by setting the above-mentioned three kinds of monomer components preferably within the above ranges, it is possible to have both high sensitivity and high resolution and further improve dry etching resistance. The ratio of the number of each unit in the polymer was calculated from the charged amount of each unit monomer at the start of the polymerization reaction and the concentration of each unit monomer remaining in the reaction solution after the completion of the polymerization reaction measured by gas chromatography. It is a thing.

The bonding state of the units in the polymer of the present invention is not particularly limited, and examples thereof include random bonding and block bonding. The polymerization method is also not particularly limited, and it can be synthesized by radical polymerization, ionic polymerization, or the like.
Among these, the graft polymer represented by the general formula (I-1) is obtained by polymerizing C on the trunk polymer composed of A and B by the ATRP method (living radical polymerization method) through at least a part of B. It is preferably obtained by Similarly, the graft polymer represented by the general formula (I-2) is a trunk polymer composed of B and C,
It is preferably obtained by polymerizing A by ATRP method through at least a part of B.

Next, the polymer of the present invention will be described according to a synthetic method (polymerization method). The synthesis of the graft polymer for photoresist of the present invention is performed in two steps, that is, the synthesis of the trunk polymer portion and the synthesis of the graft portion. The method for polymerizing the trunk polymer part is not particularly limited, but a general radical polymerization under deoxygenation using a radical generator as an initiator can be mentioned. As the initiator, an azo compound (for example, azobisisobutyronitrile) or a peroxide (for example, benzoyl peroxide) can be used in consideration of the decomposition temperature of the compound. Further, the redox type initiator may be used at room temperature. The polymerization method of the graft part is not particularly limited, but as a method for easily adjusting the molecular weight of the graft part,
Living polymerization is preferred, and the ATRP method is particularly preferred. Further, in living anionic polymerization, it is important and complicated to control the prevention of impurities such as trace amounts of water, whereas in ATRP method, in addition to living polymerization, ordinary deoxidation operation is sufficient. It has the advantage that the reaction can continue. Such simplicity is very advantageous in scale-up such as industrialization.

ATRP is used as a method for polymerizing the polymer of the present invention.
When the method is used, a general ATRP method initiator or catalyst can be used. For example, as the initiator, ethyl 2-bromo-isobutenoate, bromide such as 2-bromobenzazene,
Examples include chlorides such as benzyl chloride and dichloroacetophenone. As the catalyst, cuprous chloride, cuprous bromide, ruthenium 2+, nickel 2+, and iron 2+ complexes can be used. When the solubility of the catalyst in the solvent is a problem, good solubility can be obtained by combining an appropriate ligand. Typical ligands are 2,2'-bipyridyl, 4,4'-dihexyl-2,2'-bipyridyl, 4,
4'-ditert-butyl-2,2'bipyridyl, 1,
1,4,7,7-pentamethyldiethylenetriamine and the like can be mentioned. When a ruthenium + 2 complex is used, it is preferable to use a Lewis acid such as triisopropoxyaluminum together. Further, by using a monomer containing a halogen atom as an initiator of the ATRP method as a monomer constituting the trunk polymer portion, it becomes possible to synthesize a graft polymer by the ATRP method. In the polymerization reaction of the polymer, a solvent can be used if necessary. The type of solvent is not particularly limited, but any solvent can be used as long as it dissolves the monomer and polymer and does not promote chain transfer or termination reaction. For example, tetrahydrofuran (TH
F), dimethylformamide (DMF), dimethylacetamide, dimethylsulfoxide (DMSO), toluene, PGMEA, ethyl lactate, cyclohexanone and the like can be used. It is difficult to react 100% of the monomers charged during the reaction, but the residual monomer can be removed by a purification operation such as reprecipitation or dialysis. Also,
If necessary, through a column such as ion exchange resin,
It is more preferable as a polymer for a chemically amplified photoresist to remove metal impurities.

Next, the chemically amplified photoresist composition of the present invention (hereinafter referred to as "composition") will be described.
The composition of the present invention, the polymer, a compound that generates an acid by the action of light (hereinafter, referred to as "photoacid generator"), and a solvent that dissolves the polymer and the photoacid generator (hereinafter,
"Solvent") is added as an essential component. When the composition of the present invention is used as a photoresist, the photoacid generator generates an acid upon irradiation with light, and the action of this acid causes a deprotection reaction in the polymer. The polymer of the deprotected portion is dissolved in an alkaline developing solution in the subsequent development step, and a clear difference in dissolution rate is generated between the polymer of the portion where the deprotection reaction has not occurred and the target pattern. Can be obtained by development.

(Y) Photoacid generator The photoacid generator used in the composition of the present invention is not particularly limited.
Although not specified, sulfonium salt derivatives [sulfonic acid ester
Tell (1,2,3-tri (methylsulfonyloxy))
Aryl alkane sulfonates (especially C
_6-10Aryl C _1-2Alkane sulfonate); 2,6-
Dinitrobenzyltoluene sulfonate, benzointo
Silate nadonaryl benzene sulfonate (especially
C which may have a benzoyl group_6-10Aryltoluene
Phosphonate); 2-benzoyl-2-hydroxy-2
-Aralkyl such as phenylethyltoluenesulfonate
Rubenzenesulfonates (especially with benzoyl groups
May be C_6-10Aryl-C_1-4Alkyl toluene
Disulfone such as diphenyldisulfone
Acid; Lewis acid salt (triphenylsulfonium hexaflu
Orophosphate, triphenylsulfonium hexaf
Luoroantimony, triphenylsulfonium methane
Triarylsulfonium salts such as rufonyl, especially triarylsulfonium salts
Phenylsulfonium salt) etc.) etc.)], Phosphonium
Salt derivative, diarylionium salt derivative [diary
Ruiodonium salt (diphenyliodonium hexaflu
Lewis acid salts such as orophosphates, etc.), dia
Zonium salt derivative (p-nitrophenyldiazonium
Lewis acid salts such as oxafluorophosphate), di-
Examples include azomethane derivatives and triazine derivatives
It In particular, Lewis acid salts (Lewis acids such as phosphonium salts)
Salt) is preferred.

The amount of the photo-acid generator blended is not particularly limited, but is preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the polymer. This improves the sensitivity and resolution of the composition. If the blending amount of the photo-acid generator is less than the above lower limit value, the deprotection reaction of the polymer is difficult to proceed, so that an image may not be formed. On the other hand, when the amount exceeds the above upper limit, the deprotection reaction rapidly proceeds, so that the polymer is likely to be dissolved during development, and it may be difficult to form an image. Further, the melting point of the polymer containing the photo-acid generator becomes low, which may cause deterioration in heat resistance.

(Z) Solvent The solvent to be added to the composition of the present invention is not particularly limited as long as it dissolves the polymer and the photo-acid generator, but water, alcohols, glycols, cellosolves. ,
Examples thereof include ketones, esters, ethers, amides #, and hydrocarbons. Specifically, propylene glycol monomethyl ether acetate (PGME
A), propylene glycol monoethyl ether acetate, ethyl cellosolve acetate, methyl cellosolve acetate, butyl cellosolve acetate, methoxyethyl propionate, ethoxyethyl propionate,
Examples thereof include methyl lactate, ethyl lactate, butyl lactate, ethyl acetate, butyl acetate, methyl isobutyl ketone, and methyl pentyl ketone. Among these, PGMEA, ethoxyethyl propionate, and ethyl lactate are particularly preferable from the viewpoints of solubility, coating film stability, safety, environmental impact, human impact, and economic efficiency. These are alone or 2
Used as a mixture of two or more species.

In addition to the components described above, the composition of the present invention may further contain, if necessary, stabilizers such as antioxidants, plasticizers, surfactants, adhesion improvers, and dissolution accelerators. Various additives may be used.

The polymer of the present invention is a graft polymer for a chemically amplified photoresist, which preferably comprises A units, B units and C units as a photoresist resin, and three types of units in the polymer are appropriately constituted. By adjusting the ratio, it was possible to obtain a resin which, in addition to the characteristics originally possessed by the random polymer, had further excellent characteristics in dissolution contrast (resolution) and sensitivity.

The method for producing the composition of the present invention will be described below. First, (X) polymer and (Y) photoacid generator
(Z) Dissolves in a solvent. At that time, if necessary, a stabilizer such as an antioxidant, a plasticizer, a surfactant, an adhesion improver,
Various additives such as a dissolution accelerator may be added. The above components can be dissolved in any order. Usually, under the temperature condition of about room temperature, the components are dissolved by stirring for a sufficient time (for example, 6 to 12 hours). After dissolution, filter (PT with filtration accuracy of 0.1 μm or less
Foreign substances are removed using an FE (polytetrafluoroethylene) filter or the like), and the container is preliminarily filled with the foreign substances and metal impurities.
When filling, it is preferable to use a machine such as an automatic filling device that does not involve humans in a clean room of class 100 or less. If necessary, the polymer or composition can be washed with an aqueous acid solution or pure water or demetallized with an ion exchange resin to remove metal impurities.

[0026]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.

1. Synthesis of polymer (Example 1) 1) Synthesis of trunk polymer part In a three-neck flask equipped with a mechanical stirrer, cyclohexyl methacrylate (8.02 g), 2-bromopropanoyloxyethyl methacrylate (1.98 g), TH
F (40 g), mercaptoethanol (0.8 g) and azobisisobutyronitrile (AIBN) (0.3 g) were charged and completely dissolved. After argon gas was blown in to sufficiently deoxidize, the temperature was raised to 80 ° C. and the reaction was performed for 6 hours. After completion of the reaction, the solution after completion was poured into 10 times amount of methanol and vigorously stirred for 1 hour. This mixture was allowed to cool at -40 ° C for several hours, and the generated precipitate was filtered and dried under reduced pressure (40 ° C). The solid content thus obtained was used as the trunk polymer part. The polystyrene-equivalent number average molecular weight (Mn) of the present polymer (Mn) = 2051, and the degree of dispersion (Mw / Mn) = 1.
It was 39. 2) The above trunk polymer (2 g), 2-methyl-2-adamantyl methacrylate (2 g) and THF (2 g) were charged into a three-necked flask equipped with a synthetic mechanical stirrer for the graft portion and completely dissolved. After argon gas was blown in and sufficient deoxidation was performed, a nickel complex (dibromo-bis (tributylphosphine) nickel (II), 96.6 mg) was added, and the mixture was vigorously stirred until it turned reddish brown. Then, the temperature was raised and the reaction was carried out under reflux for 1 day. The solution after the reaction was poured into 10 times the amount of methanol, and the generated precipitate was filtered and dried under reduced pressure (40 ° C.). The solid content thus obtained was a crude graft polymer containing a residual metal catalyst, and the target graft polymer for photoresist was obtained by purification by column fractionation. Polystyrene-equivalent number average molecular weight (Mn) = 1550, dispersity (Mw / Mn) = 1.41
Met. The weight ratio of the trunk polymer portion to the graft portion was 51:49.

(Example 2) 1) Synthesizing the trunk polymer part In a three-neck flask equipped with a mechanical stirrer, 2
-Norbornene (6.6g), maleic anhydride (6.9g), 2
-Bromopropanoyloxyethyl methacrylate (3.2
g), THF (85.2 g) and AIBN (1.07 g) were charged and completely dissolved. After argon gas was blown in to sufficiently deoxidize, the temperature was raised to 80 ° C. and the reaction was performed for 6 hours. After completion of the reaction, the solution was poured into 10 times amount of diethyl ether and vigorously stirred for 1 hour. The generated precipitate was filtered and dried under reduced pressure (40 ° C). The solid content thus obtained was used as the trunk polymer part. The polystyrene-equivalent number average molecular weight (Mn) of this polymer was 3102 and the dispersity (Mw / Mn) was 1.34. 2) In a three-necked flask equipped with a synthetic mechanical stirrer for the graft part, the above-mentioned trunk polymer (2 g), tert-butyl acrylate (2 g), 2,2 ′ bipyridyl (0.725 g) and THF (2
g) was charged and completely dissolved. Argon gas was blown in to thoroughly deoxidize the mixture, cuprous bromide (0.397 g) was added, and the mixture was vigorously stirred until it turned reddish brown. Then, the temperature was raised and the mixture was reacted under reflux for 5 hours. The solution after the reaction was poured into 10 times amount of methanol, and the generated precipitate was filtered,
It was dried under reduced pressure (40 ° C). The solid content thus obtained was a crude graft polymer containing residual metal catalyst, and was purified by treating with a large amount of activated carbon to obtain the desired graft polymer for photoresist. Polystyrene-equivalent number average molecular weight (Mn) of graft part = 250
0, dispersity (Mw / Mn) = 1.71. Also,
The weight ratio of the trunk polymer part to the graft part was 52:48.

(Example 3) 1) Synthesis of a trunk polymer part In a three-neck flask equipped with a mechanical stirrer, 2
-Methyl-2-adamantyl methacrylate (2g), 2
-Bromopropanoyloxyethyl methacrylate (1.98
g), THF (40 g), mercaptoethanol (0.8 g) and azobisisobutyronitrile (AIBN) (0.3 g) were charged and completely dissolved. After argon gas was blown in to sufficiently deoxidize, the temperature was raised to 80 ° C. and the reaction was performed for 6 hours. After completion of the reaction, the solution after completion was poured into 10 times amount of methanol and vigorously stirred for 1 hour. This mixture was allowed to cool at -40 ° C for several hours, and the generated precipitate was filtered and dried under reduced pressure (40 ° C).
The solid content thus obtained was used as the trunk polymer part. This polymer has a polystyrene-equivalent number average molecular weight (Mn) of 2040 and a dispersity (Mw / M).
n) = 1.45. 2) The above-mentioned trunk polymer (2 g), cyclohexyl methacrylate (8.02 g) and THF (2 g) were charged into a three-necked flask equipped with a synthetic mechanical stirrer for the graft portion and completely dissolved.
After argon gas was blown in and sufficient deoxidation was performed, a nickel complex (dibromo-bis (tributylphosphine) nickel (II), 96.6 mg) was added, and the mixture was vigorously stirred until it turned reddish brown. Then, the temperature was raised and the reaction was carried out under reflux for 1 day. The solution after the reaction was poured into 10 times the amount of methanol, and the generated precipitate was filtered and dried under reduced pressure (40 ° C). The solid content thus obtained was a crude graft polymer containing a residual metal catalyst, and the target graft polymer for photoresist was obtained by purification by column fractionation.
Polystyrene-equivalent number average molecular weight (Mn) of the graft part
= 5050 and the dispersity (Mw / Mn) = 1.80. The weight ratio of the trunk polymer portion to the graft portion is 30:
It was 70.

(Comparative Example 1) A three-necked flask equipped with a mechanical stirrer was charged with cyclohexyl methacrylate (5 g), 2-methyl-2-adamantyl methacrylate (5 g), THF (39 g) and AIBN (0.3 g) and then completely charged. Dissolved in. After argon gas was blown in to sufficiently deoxidize, the temperature was raised to 80 ° C. and the reaction was performed for 6 hours. The solution after completion of the reaction was poured into 10 times the amount of methanol and vigorously stirred for 1 hour. The mixture was allowed to cool at -40 ° C for several hours, and the generated precipitate was filtered and dried under reduced pressure (40 ° C). The polymer thus obtained is a linear and random copolymer having substantially the same composition as in Example 1. The polystyrene-reduced number average molecular weight (Mn) of the present polymer as a comparative example of Example 1 measured by GPC (Mn) = 14927, dispersity (M
w / Mn) = 2.81.

Comparative Example 2 In a three-necked flask equipped with a mechanical stirrer, 2-norbornene (65.8 g),
Maleic anhydride (68.6g), tert-butyl acrylate (134.4g), THF (627.2g) and AIBN (5.37g).
g) was charged and completely dissolved. After argon gas was blown in to sufficiently deoxidize, the temperature was raised to 80 ° C. and the reaction was performed for 6 hours. After completion of the reaction, the solution was poured into 10 times amount of diethyl ether and vigorously stirred for 1 hour. The generated precipitate was filtered and dried under reduced pressure (40 ° C). The polymer thus obtained is a linear and random copolymer having substantially the same composition as in Example 2. The polystyrene-reduced number average molecular weight (Mn) measured by GPC (Mn) = 2768, and the dispersity (Mw / Mn) = of this polymer as a comparative example of Example 2.
It was 2.20.

For the polymers obtained in the examples and comparative examples, the number average molecular weight was measured by GPC, IR analysis, N
MR analysis was performed. Regarding Example 1, a GPC chart is shown in FIG. 1 and an NMR chart is shown in FIG.

2. Evaluation of Photoresist Composition (1) Preparation of Photoresist Composition 10 parts by weight of the polymers obtained in Examples and Comparative Examples
After dissolving in 0 part by weight of propylene glycol monomethyl ether acetate (PGMEA), 0.2 part by weight of triphenylsulfonium triflate as a photo-acid generator was added and sufficiently dissolved. This was filtered using a PTFE filter (filtration accuracy 0.1 μm).

(2) Evaluation of photoresist performance (2-1) The photoresist composition whose sensitivity was adjusted was coated on a silicon wafer by a spin coater so that the film thickness after prebaking would be 0.5 μm, and then hot. 14 on the plate
Prebaked at 0 ° C. for 90 seconds. After that, A made by ISI
rF excimer laser irradiation device (lens numerical aperture 0.6
0, exposure wavelength 193 nm) was used for exposure through test reticles (masks) having various line widths. Then, post-exposure bake at 140 ° C for 90 seconds on a hot plate (PE
After performing B), 60% at 23 ° C. with a 2.38 wt% aqueous solution of tetramethylammonium hydroxide.
Paddle development was performed for 2 seconds. Then, it was washed with water and dried to obtain a positive pattern. At that time, the exposure amount capable of forming a line-and-space pattern having a line width of 0.18 μm (the ratio of line to space is 1: 1) with a line width of 1: 1 is defined as the sensitivity (E
_op ). (2-2) Resolution The minimum dimension of the photoresist pattern resolved when exposed with an exposure amount corresponding to the sensitivity obtained in (2-1) was defined as the resolution. (2-3) tan θ The exposure amount (mJ / cm ² ) is plotted on the horizontal axis and the alkali dissolution rate (nm / s) of the composition is plotted on the vertical axis, and the discrimination curve (discrimina
tion curve) was created. The slope near the inflection point of this curve is represented by tangent (tan θ).

Table 1 shows the measurement results of (2-1) to (2-3).
It was shown to.

[Table 1]

Examples 1 and 2 are graft polymers obtained by polymerizing C on the trunk polymer consisting of A and B by ATRP method via at least a part of B, and Example 3 is a graft polymer. A graft polymer obtained by polymerizing A by a ATRP method on a trunk polymer composed of B and at least a portion of B, each having a predetermined composition ratio and number average molecular weight. Then, the photoresist composition using the same has excellent resolution and sensitivity without substantially lowering the sensitivity. On the other hand, Comparative Example is a random polymer consisting of A and C, but Comparative Example 1 cannot be dissolved in a solvent, and the resolution and sensitivity of the photoresist composition using the polymer of Comparative Example 2 are the same as those of the present invention. Inferior to the polymer of.

[0037]

EFFECT OF THE INVENTION The present invention is characterized in that a photoresist excellent in dry etching resistance is copolymerized with a monomer having a protective group that is deprotected by the action of an acid generated by photoreaction. A graft polymer and a photoresist composition using the same, and the composition of the present invention has excellent sensitivity and resolution. Therefore, the polymer and composition of the present invention are expected to play a major role in high integration of semiconductors and the like.

[Brief description of drawings]

FIG. 1 is a GPC chart of the polymer of Example 1.

FIG. 2 is an NMR chart of the polymer of Example 1.

Claims (12)

[Claims] 1. A graft polymer for photoresist, which is obtained by copolymerizing a monomer having excellent dry etching resistance with a monomer having a protective group that is deprotected by the action of an acid generated by photoreaction. 2. The graft polymer for photoresist according to claim 1, wherein the graft polymer for photoresist is composed of the following (a) and / or (a). (A) Graft formed by polymerizing a monomer component having excellent dry etching resistance in the trunk polymer portion, and polymerizing a monomer component having a protective group that is deprotected by the action of an acid generated by a photoreaction in the graft portion polymer. (A) A graft formed by polymerizing a monomer component having a protective group for deprotection by the action of an acid generated by a photoreaction in the trunk polymer portion, and polymerizing a monomer component having excellent dry etching resistance in the graft portion. polymer. 3. The trunk polymer part contains a monomer having a halogen atom and serving as an initiator of the ATRP method (living radical polymerization method), and is bonded to the graft part by at least a part thereof. Item 3. A graft polymer for photoresist according to Item 2. 4. The number average molecular weights of the trunk polymer part and the graft part are respectively 1,000 to 30,000, and the weight ratio of the trunk polymer part to the graft part is 90:10.
The graft polymer for photoresist according to claim 2, which is 10:90. 5. The (a) is a graft polymer represented by the general formula (I-1), and / or the (a).
Is a graft polymer represented by the general formula (I-2), wherein the graft polymer for photoresist according to any one of claims 2 to 4. [Chemical 1] In the general formula (I-1) and the general formula (I-2), A,
B and C represent each monomer component. General formula (I-1)
Represents a graft polymer having a structure in which C is bonded as a graft portion via at least a part of B to a trunk polymer which is a copolymer of A and B. In addition, the general formula (I-2)
Represents a graft polymer having a structure in which A is bonded as a graft portion via at least a part of B to a trunk polymer which is a copolymer of B and C. General formula (I-1), (I-
In 2), A is at least one selected from the general formulas (II), (III) and (IV). In the general formula (II), R ₁ is selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group, an alkoxyalkyl group, a cycloalkyl group, a cyclic ether group and a cyclic ester group. is there. l is 1 to 5, and when l is 2 to 5,
You may use together said 2 or more types. In general formula (IV), R ₂ is a hydrogen atom or a methyl group. R ₃ is selected from a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, an alkoxyalkyl group, a cycloalkyl group, a cyclic ether group and a cyclic ester group. B is the general formula (V), (V
It is one or more selected from I). In the general formula (V), R ₄ is a halogen atom, R ₅ is a hydrogen atom or a methyl group,
R ₆ is an alkyl group having 1 to 15 carbon atoms. General formula (V
In I), R ₇ is a hydrogen atom or a methyl group. R ₈ is a halogen atom. C is one or more selected from the general formulas (VII) and (VIII). In general formula (VII), R ₉ is a hydrogen atom or a methyl group. R ₁₀ is selected from a tertiary alkyl group having 4 to 15 carbon atoms, a tertiary alkoxyalkyl group, a tertiary cycloalkyl group, a tertiary cyclic ether group and a tertiary cyclic ester group. General formula (VII
In I), R ₁₁ is selected from a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group, an alkoxyalkyl group, a cycloalkyl group, a cyclic ether group and a cyclic ester group. m is 1 to 5, and when m is 2 to 5, two or more of the above may be used in combination. R ₁₂ is selected from a tertiary alkyl group having 4 to 15 carbon atoms, a tertiary alkoxyalkyl group, a tertiary cycloalkyl group, a tertiary cyclic ether group and a tertiary cyclic ester group. And A,
A, b, and c representing the ratios of the respective monomer components of B and C are: a / (a + b + c) is 0.1 to 0.8, b / (a + b + c) is 0.01 to 0.2, c / (A + b + c) is 0.1 to 0.8. 6. General formula (I-1) and general formula (I-2)
The photoresist graft polymer according to claim 5, wherein A is one or more selected from cyclohexyl acrylate, cyclohexyl methacrylate, norbornene, and maleic anhydride. 7. The general formula (I-1) and the general formula (I-2).
Among them, C is 2-methyl-2-adamantyl acrylate, 2-methyl-2-adamantyl methacrylate, t
7. One or more kinds selected from ert-butyl acrylate and tert-butyl methacrylate.
The graft polymer for photoresist as described in 1. 8. A general formula (I-1) and a general formula (I-2).
Among them, B is one or more selected from 2-bromoisobutenoyloxyethyl methacrylate, 2-bromoisobutenoyloxyethyl acrylate, 2-bromopropanoyloxyethyl methacrylate, and 2-bromopropanoyloxyethyl acrylate. The graft polymer for photoresist according to claim 5. 9. The graft polymer represented by the general formula (I-1) is obtained by polymerizing C on a trunk polymer composed of A and B by ATRP method (living radical polymerization method) through at least a part of B. 6. The product obtained by
9. The graft polymer for photoresist according to any one of 1 to 8. 10. The graft polymer represented by the general formula (I-2) is obtained by polymerizing A on a trunk polymer composed of B and C by ATRP method through at least a part of B. 9. The graft polymer for photoresist according to claim 5, which is 11. A chemically amplified photoresist composition containing the following components (X) to (Z) as essential components. (X) The graft polymer for photoresist according to any one of claims 1 to 10, (Y) a compound capable of generating an acid by the action of light, and (Z) a solvent capable of dissolving (X) and (Y). 12. The chemical amplification according to claim 11, wherein the compound (Y) that generates an acid by the action of light is 1 to 20 parts by weight with respect to 100 parts by weight of the graft polymer (X) for photoresist. -Type photoresist composition.