JP5461472B2 - POLYMER COMPOUND, PHOTORESIST COMPOSITION CONTAINING THE POLYMER COMPOUND, AND METHOD FOR FORMING RESIST PATTERN - Google Patents

Description

  The present invention relates to a polymer compound, a low molecular compound suitable for preparation of the polymer compound, a photoresist composition containing at least the polymer compound, and a resist pattern forming method.

  It is no exaggeration to say that miniaturization of semiconductor integrated circuit patterns has been achieved by advancements in photolithography and peripheral technologies. As is well known, optical lithography is broadly supported by two techniques. One is the exposure wavelength and numerical aperture of a reduction projection exposure apparatus called a stepper or scanner, and the other is a transfer solution of a photoresist composition to which a mask pattern is transferred by the reduction projection exposure apparatus. It is a resist characteristic mainly composed of image properties. These have improved the processing accuracy of the semiconductor integrated circuit pattern by photolithography.

The light source used in the reduction projection exposure apparatus has been made shorter and shorter in response to the demand for higher resolution circuit patterns. In general, when the resist resolution is about 0.5 μm, the g-line with a main spectrum of the mercury lamp of 436 nm is used, and when about 0.5 to 0.30 μm, the main spectrum of the mercury lamp is the i-line with the same wavelength of 365 nm. 30 to 0.15 μm uses 248 nm KrF excimer laser light, and about 0.15 μm or less uses 193 nm ArF excimer laser light. For further miniaturization, 157 nm F ₂ excimer laser light or 126 nm The use of Ar ₂ excimer laser light and EUV (extreme ultraviolet wavelength 13 nm) is being studied.

On the other hand, looking at the photoresist composition, there is a combination with an organic or inorganic antireflection film and a lighting system. At present, in the lithography using KrF excimer laser light, the life of the photoresist for KrF is prolonged. Photoresist compositions have been developed with a view of about 110 nm of λ / 2 or less. In addition, in lithography using ArF excimer laser light, it is desired to provide a photoresist composition for ArF for future mass production of fine patterns of about 90 nm node or less. Lithography using the F ₂ excimer laser is attracting attention as a technology for processing future fine patterns of 65 nm or less, and can be applied to fine processing by lithography using the F ₂ excimer laser. Development of new photoresist compositions is underway.

In order to obtain such a fine pattern, since it is difficult to use a conventional positive photoresist having an alkali-soluble novolak resin and a quinonediazide group-containing compound as basic components, far-ultraviolet rays having a shorter wavelength (200 to 300 nm), KrF, Development of resists using excimer lasers such as ArF and F ₂ , electron beams and X-rays is desired. As such a resist, in addition to achieving high resolution, a chemically amplified resist that can use a catalytic reaction and a chain reaction of an acid generated by irradiation of radiation and has a quantum yield of 1 or more and can achieve high sensitivity is attracting attention. It has been actively developed.

In a positive chemically amplified resist, a resin having an acid dissociable, dissolution inhibiting group is mainly used.
Examples of the acid dissociable dissolution inhibiting group used in the chemically amplified resist include an acetal group, tert as an acid dissociable dissolution inhibiting group for a fluorinated alcohol, as shown in Non-Patent Documents 1 to 3 below. Tertiary alkyl groups such as -butyl group, tert-butoxycarbonyl group, tert-butoxycarbonylmethyl group and the like are known.

  In addition, as a structural unit having an acid dissociable, dissolution inhibiting group in a resin component of a conventional ArF resist composition, as shown in Patent Document 1 below, a tertiary ester compound of (meth) acrylic acid, for example, 2-alkyl A structural unit derived from 2-adamantyl (meth) acrylate or the like is generally used.

JP-A-10-161313

T.A. Hagiwara, S .; Irie, T .; Itani, Y. et al. Kawaguchi, O .; Yokokoji, S .; Kodama, J .; Photopolym. Sci. Technol. 16, 557, 2003. F. Houlihan, A .; Romano, D.M. Rentkiewicz, R.A. Sakamura, R.A. R. Dammel, W.M. Conley, G.M. Rich, D.C. Miller, L.M. Rhodes, J. et al. McDaniels, C.I. Chang, J.M. Photopolym. Sci. Technol. 16, 1681, 2003. Y. Kawaguchi, J. et al. Irie, S.M. Kodama, S .; Okada, Y .; Takebe, I. et al. Kaneko, O .; Yokokoji, S .; Ishikawa, S .; Irie, T, Hagiwara, T .; Itani, Proc. SPIE, 5039, 43, 2003.

  However, in the acid dissociable, dissolution inhibiting group used in the chemically amplified resists shown in Non-Patent Documents 1 to 3, the alkali dissolution inhibiting property at the unexposed portion is insufficient (resist pattern is reduced in film). Thus, there are problems in terms of improving resolution and forming a fine pattern with good rectangularity. Even if the introduction rate of the acid dissociable dissolution inhibiting group is increased to improve the alkali dissolution inhibiting property in the unexposed area, the risk of defects increases, which is a problem.

  In addition, as shown in Patent Document 1, as a compound that forms an acid dissociable, dissolution inhibiting group, for example, a wide variety of compounds that form a cyclic or chain tertiary alkyl ester with a carboxyl group of (meth) acrylic acid. Are known. However, the types of acid generators that can be used in the resist composition using them are limited. That is, if an acid generator having a strong acid strength, such as an onium salt having a fluorinated alkyl sulfonate ion in the anion portion, is not applied, the acid dissociable dissolution inhibiting group is not eliminated. There is a problem that it does not function as a positive resist. In addition, when an acid generator having a weak acid strength is used, there is a problem that the sensitivity is insufficient, and improvement is desired.

  The present invention has been made in view of the above, has excellent resolution, can form a fine pattern with good rectangularity, and is also a good resist even when the acid generated from the acid generator is weak An object of the present invention is to provide a polymer compound capable of forming a photoresist composition having characteristics and good sensitivity. It is another object of the present invention to provide a compound suitable for preparing such a polymer compound, a photoresist composition containing the polymer compound, and a resist pattern forming method using the photoresist composition. .

  In order to solve the above problems, the present inventors introduced various acid-dissociable, dissolution-inhibiting groups as protective groups for alkali-soluble groups in the polymer compound for photoresist compositions, and the resist characteristics of these polymer compounds. As a result of diligent research, we found for the first time that when using an acid-dissociable, dissolution-inhibiting group having a specific aliphatic cyclic group, the resist pattern has a good shape and a fine pattern with improved resolution can be formed. The present invention has been completed based on this finding. In addition, when an acid dissociable, dissolution inhibiting group having the specific alicyclic group is used, a compound that forms a cyclic or chain tertiary alkyl ester with a carboxyl group of a conventional (meth) acrylic acid is used. It was also found that the selectivity of the acid generator is widened and a highly sensitive resist composition can be obtained as compared with the case where an acid dissociable, dissolution inhibiting group is formed.

  The present invention has been made based on such knowledge. That is, the polymer compound of the present invention is a polymer compound whose alkali solubility can be changed by the action of an acid, and has the following general formula (2)

(In the formula, R ₁ having 20 or less of an aliphatic cyclic group (wherein a carbon, a.) Except 4-oxo-adamantane-1-yl group, n represents an integer of 0 or 1 to 5, R ₂ represents a hydrogen atom or a lower alkyl group having 20 or less carbon atoms. configured as a unit (a1) derived from a compound represented by), the following general formula (4)

(In the formula, R ₂ is the same as described above. X ′ represents a divalent or trivalent cyclic group, Y represents a divalent alkylene group having 1 to 6 carbon atoms or an alkyloxy group. P and q Each independently represents an integer of 1 to 5, and s represents an integer of 1 or 2. The structural unit (a6) is included. The polymer compound of the present invention preferably further contains a structural unit (a4) derived from a (meth) acrylic acid ester containing a polar group-containing polycyclic group.

  The photoresist composition of the present invention generates at least a base resin component (A) whose alkali solubility is changed by the action of an acid (hereinafter sometimes referred to as the (A) component) and radiation upon irradiation. The acid generator component (B) (hereinafter sometimes referred to as the component (B)) is contained, and the base resin component (A) is the polymer compound of the present invention. To do.

  The resist pattern forming method of the present invention includes a step of forming a photoresist film on a substrate using such a photoresist composition, a step of exposing the photoresist film, and developing the resist film to form a resist pattern. Including a process.

  According to the present invention, it is possible to provide a fine pattern having a good resist pattern shape (rectangularity) and high resolution. Moreover, even if the acid generated from the acid generator is weak, the acid dissociable, dissolution inhibiting group can be dissociated, and good sensitivity can be obtained.

It is a figure which shows the sensitivity curve by ArF exposure.

Hereinafter, embodiments of the present invention will be described.
The “structural unit” in the claims and the specification means a monomer unit (monomer unit) constituting the polymer compound.
In the claims and specification, unless otherwise specified, the alkyl group, alkoxy group, and alkylene group may be linear or branched.
In the polymer compound of the present invention, the hydrogen atom of the alkali-soluble group (i) in the molecule is represented by the following general formula (3).

(Wherein R ₁ represents an aliphatic cyclic group having 20 or less carbon atoms, n represents 0 or an integer of 1 to 5), and is substituted with an acid dissociable, dissolution inhibiting group (ii). It is characterized by that.
When the polymer compound of the present invention is used in a chemically amplified positive resist system, the polymer compound is an acid having an aliphatic cyclic group represented by the general formula (1) (or general formula (3)). By having a dissociable, dissolution-inhibiting group, it exhibits a dissolution-inhibiting action in alkali development before exposure, and exhibits alkali solubility by deprotection after exposure and PEB (post-exposure heating) processes, before and after exposure. Since the alkali solubility of the material greatly changes, a fine pattern with excellent resolution can be obtained. Moreover, when the polymer compound of the present invention is used, the etching resistance of the resist pattern is improved. In particular, when a hydrophilic group is further introduced into the acid dissociable, dissolution inhibiting group (ii), the adhesion of the resist pattern to the substrate is improved, and development defects are reduced by improving the affinity for an alkaline developer. Also, the mask linearity is good.

<Acid dissociable, dissolution inhibiting group (ii)>
Details of the alkali-soluble group (i) will be described later. The alkali-soluble group (i) has a hydrogen atom, and the acid dissociable, dissolution inhibiting group (ii) replaces this hydrogen atom. That is, when the alkali-soluble group (i) is an alcoholic hydroxyl group, a carboxyl group, or a phenolic hydroxyl group, the acid dissociable, dissolution inhibiting group (ii) is an oxygen atom excluding the hydrogen atom of the alkali-soluble group (i). Is bound to.

The acid dissociable, dissolution inhibiting group (ii) is represented by the general formula (1). In the formula, R ₁ is an aliphatic cyclic group having 20 or less carbon atoms, and preferably an aliphatic cyclic group having 5 to 12 carbon atoms. The aliphatic cyclic group may have a substituent. The value of n is preferably 0 or 1.
“Aliphatic” in the claims and the specification is a relative concept with respect to aromaticity, and is defined to mean a group, a compound, or the like that does not have aromaticity. The “aliphatic cyclic group” means a monocyclic group or a polycyclic group (alicyclic group) having no aromaticity. In this case, the “aliphatic cyclic group” is not limited to a group consisting of carbon and hydrogen, but is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated.
Examples of such an aliphatic cyclic group are derived from cyclohexane, cyclopentane, adamantane, norbornane, norbornene, methylnorbornane, ethylnorbornane, methylnorbornene, ethylnorbornene, isobornane, tricyclodecane, tetracyclododecane, and the like. A monovalent group can be mentioned. Such an aliphatic cyclic group can be appropriately selected and used from among many proposed ArF resists. Among these, cyclohexyl group, cyclopentyl group, adamantyl group, norbornyl group, norbornenyl group, methylnorbornyl group, ethylnorbornyl group, methylnorbornenyl group, ethylnorbornenyl group, tetracyclododecanyl group are industrially used. Preferably, an adamantyl group is more preferable.

The acid dissociable, dissolution inhibiting group (ii) is more preferably an aliphatic cyclic group having at least one hydrophilic group as R ₁ in the general formula (1). Are preferably a carbonyl group (preferably a ketonic carbonyl group), an ester group (—COOR), an alcoholic hydroxyl group, an ether (—OR), an imino group, or an amino group, and are available as a carbonyl group. It is most preferable because it is easy.

  Examples of the acid dissociable, dissolution inhibiting group (ii) include groups represented by the following chemical formulas (4) to (15).

<Alkali-soluble group (i)>
The alkali-soluble group (i) in the polymer compound of the present invention is known from the KrF resist, ArF resist, and F ₂ resist that have been proposed so far, as exemplified in the aforementioned non-patent literature. . Examples of such alkali-soluble groups include alcoholic hydroxyl groups, phenolic hydroxyl groups, and carboxyl groups, and are not particularly limited.
In the present invention, at least one selected from an alcoholic hydroxyl group, a phenolic hydroxyl group, and a carboxyl group is preferable. Of these, alcoholic hydroxyl groups are preferred because of their high transparency and moderate alkali solubility. In the case of an alcoholic hydroxyl group, an alcoholic hydroxyl group characterized in that a carbon atom adjacent to a carbon atom bonded to the alcoholic hydroxyl group has at least one fluorine atom is more preferable.

  The alcoholic hydroxyl group may be simply a hydroxy group, an alcoholic hydroxyl group-containing alkyloxy group, an alcoholic hydroxyl group-containing alkyloxyalkyl group, or an alcoholic hydroxyl group-containing alkyl group. Examples of the alkyloxy group, the alkyloxyalkyl group or the alkyl group include a lower alkyloxy group, a lower alkyloxy lower alkyl group and a lower alkyl group. Here, “lower” means 4 or less carbon atoms.

  Specific examples of the lower alkyloxy group include a methyloxy group, an ethyloxy group, a propyloxy group, and a butyloxy group. Specific examples of the lower alkyloxy lower alkyl group include a methyloxymethyl group, an ethyloxymethyl group, a propyloxymethyl group, and a butyloxymethyl group. Specific examples of the lower alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group.

  Further, in the alcoholic hydroxyl group-containing alkyloxy group, the alcoholic hydroxyl group-containing alkyloxyalkyl group or the alcoholic hydroxyl group-containing alkyl group, the alkyloxy group, the alkyloxyalkyl group, or a part or all of the hydrogen atoms of the alkyl group It may be substituted with a fluorine atom. Preferably, in the alcoholic hydroxyl group-containing alkyloxy group or the alcoholic hydroxyl group-containing alkyloxyalkyl group, a part of hydrogen atoms of their alkyloxy moiety is substituted with a fluorine atom, in the alcoholic hydroxyl group-containing alkyl group, Examples thereof include those in which part of the hydrogen atoms of the alkyl group is substituted with fluorine atoms, that is, alcoholic hydroxyl group-containing fluoroalkyloxy groups, alcoholic hydroxyl group-containing fluoroalkyloxyalkyl groups, or alcoholic hydroxyl group-containing fluoroalkyl groups.

Examples of the alcoholic hydroxyl group-containing fluoroalkyloxy group include (HO) C (CF ₃ ) ₂ CH ₂ O— group, 2-bis (trifluoromethyl) -2-hydroxy-ethyloxy group, (HO) C (CF ₃ ) ₂ CH ₂ CH ₂ O— group, 3-bis (trifluoromethyl) -3-hydroxypropyloxy group, and the like. Examples of the alcoholic hydroxyl group-containing fluoroalkyloxyalkyl group include (HO) C (CF ₃ ). ₂ CH ₂ O—CH ₂ — group, (HO) C (CF ₃ ) ₂ CH ₂ CH ₂ O—CH ₂ — group, and the like. Examples of the alcoholic hydroxyl group-containing fluoroalkyl group include (HO) C (CF _{3) 2} CH ₂ - group, 2- bis (trifluoromethyl) -2-hydroxy - _{ethyl, (HO) C (CF 3} ) 2 CH 2 CH 2 - group, 3-bis (trifluoromethyl) -3 − Mud propyl group, and the like.

  Examples of the phenolic hydroxyl group include phenolic hydroxyl groups contained in novolak resins and poly- (α-methyl) hydroxystyrene. Among these, a phenolic hydroxyl group of poly- (α-methyl) hydroxystyrene is preferable because it is inexpensive and easily available.

  Examples of the carboxyl group include a carboxyl group in a structural unit derived from an ethylenically unsaturated carboxylic acid. Examples of the ethylenically unsaturated carboxylic acid include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and fumaric acid. Among these, acrylic acid and methacrylic acid are preferable because they are inexpensive and easily available.

<Compound and Structural Unit (a1) of the Present Invention>
The novel compound of the present invention (sometimes referred to as “low molecular compound” for the polymer compound of the present invention) is represented by the following general formula (16):

Wherein R ₂ represents a hydrogen atom, a fluorine atom, a lower alkyl group having 20 or less carbon atoms or a fluorinated lower alkyl group, R ₁ is an aliphatic cyclic group having 20 or less carbon atoms, and n is 0 or And a polymer compound containing at least the structural unit (a1) derived from this compound as a monomer unit is also included in the polymer compound of the present invention. included.
The structural unit (a1) is a structural unit derived from the novel compound of the present invention, and the alkali-soluble group (i) is derived from acrylic acid which may have a substituent (R ₂ ). It corresponds to a structural unit in which a hydrogen atom of the carboxyl group is substituted with an acid dissociable, dissolution inhibiting group (ii).

In the general formula (16), R ₂ is a hydrogen atom, a fluorine atom, a lower alkyl group having 20 or less carbon atoms or a fluorinated lower alkyl group having 20 or less carbon atoms, preferably a lower alkyl group having 1 to 4 carbon atoms. Or it is a C1-C4 fluorinated lower alkyl group, and a methyl group, an ethyl group, a propyl group, a butyl group, a trifluoromethyl group etc. are mentioned specifically ,. Among these, a hydrogen atom and a methyl group are most preferable because they are inexpensive and easily available. n is 0 or an integer of 1 to 5, and 0 or 1 is preferable.

  Among the compounds represented by the general formula (16), a compound represented by the following general formula (17) is preferable.

(In the formula, R ₂ is the same as above, X represents a hydrogen atom of 2 atoms or an oxygen atom of 1 atom. N ′ represents 0 or 1.)
That is, when X is a two-atom hydrogen atom, it means a methylene chain (—CH ₂ —).

  Among the compounds represented by the general formula (17), compounds represented by the following general formulas (18) to (20) are more preferable.

(R ² is the same as above)

(R ² is the same as above)

(R ² is the same as above)

<Polymer compound>
The polystyrene-reduced mass average molecular weight (Mw) of the polymer compound of the present invention by gel permeation chromatography (GPC) is not particularly limited, but is preferably 5000 to 80000, more preferably when used for a photoresist composition. Is 8000-50000. The dispersity (Mw / Mn) is about 1.0 to 5.0, preferably 2.5 or less. Mn is the number average molecular weight.

The precursor before introducing the acid dissociable, dissolution inhibiting group (ii) in the polymer compound of the present invention can be composed of one or more structural units having an alkali-soluble group (i). Hereinafter, for the convenience of explanation, the one before the introduction of the acid dissociable dissolution inhibiting group (ii) may be distinguished as a “precursor”, and the one after the introduction as a “polymer compound”.
As the structural unit having an alkali-soluble group, at least one or two or more structural units selected from monomer units having the alcoholic hydroxyl group, phenolic hydroxyl group, and carboxyl group are preferably used. In addition to these, the structural unit used for the conventionally well-known polymer for photoresist compositions can also be included.

As the structural unit having an alkali-soluble group, for example, the carbon atom adjacent to the carbon atom bonded to the alcoholic hydroxyl group as represented by the following chemical formulas (21) to (29) is at least one fluorine atom. A structural unit having an alcoholic hydroxyl group, a structural unit having a phenolic hydroxyl group as shown in (30) to (31), and R ^{7 in} (32) to (35) or (45) is a hydrogen atom Examples thereof include a structural unit having a carboxyl group as shown in some cases.
In addition, it is also preferable to use together the structural unit represented by Chemical formula (22) with the structural unit induced | guided | derived from tetrafluoroethylene, as shown by Chemical formula (23).

The polymer compound can be synthesized by a known method or a method described in the non-patent document.
The method of introducing the acid dissociable, dissolution inhibiting group (ii) by replacing the hydrogen atom of the alkali-soluble group (i) in the precursor is, for example, halogenated using an alcohol compound containing a halogen atom such as chlorine or bromine. A methyl ether compound can be synthesized and reacted with the alkali-soluble group of the precursor to introduce an acid dissociable, dissolution inhibiting group (ii).
For example, by using a chloromethyl ether compound as a starting material and reacting with any one alkali-soluble group (i) selected from an alcohol hydroxyl group, a carboxyl group, and a phenolic hydroxyl group of the precursor, the alkali-soluble group (i ) Can be protected with an acid dissociable, dissolution inhibiting group represented by formula (1).

The chloromethyl ether compound can be synthesized by a known method as shown in the following reaction formula. That is, paraformaldehyde is added to an alcohol compound, and 2.0 to 3.0 equivalents of hydrogen chloride gas is blown into the alcohol compound and reacted at 40 to 100 ° C. under hydrochloric acid acidity. After completion of the reaction, the desired chloromethyl ether compound can be obtained by distilling the product under reduced pressure. In the following reaction formula, R corresponds to the group represented by “— (CH ₂ ) _n —R ₁ ” in the target compound.

  Examples of the chloromethyl ether compound include 4-oxo-2-adamantyl chloromethyl ether represented by the following chemical formula (36), 2-adamantyl chloromethyl ether represented by the following chemical formula (37), and the following chemical formula (38 1-adamantyl methyl chloromethyl ether represented by the following formula:

  The precursor having a phenolic hydroxyl group as the alkali-soluble group (i) can be obtained, for example, by reacting the halogenated methyl ether compound with a poly- (α-methyl) hydroxystyrene resin.

  The precursor having a carboxyl group as the alkali-soluble group (i) is, for example, polymerizing an unsaturated carboxylic acid ester obtained by reacting the halogenated methyl ether compound with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid. Can be obtained.

  Examples of the halogenated methyl ether compound or other compounds having an aliphatic cyclic group include a structural unit having an alkali-soluble group (i) as represented by the above chemical formulas (21) to (35), or The acid dissociable, dissolution inhibiting group (ii) can be introduced by reacting with a compound that induces a structural unit. If necessary, the polymer compound of the present invention can be obtained by further polymerization.

Furthermore, the novel compounds of the present invention (low molecular compound), can be prepared by reacting a substituent (R ₂₎ and an acrylate may have a the halogenated methylether compound. Introduction of the substituent (R ₂ ) can be performed by an arbitrary procedure.

<Photoresist composition>
The photoresist composition according to the present invention contains at least a base resin component (A) whose alkali solubility is changed by the action of an acid and an acid generator component (B) that generates an acid upon irradiation with radiation. The base resin component (A) is the polymer compound according to the present invention described above.

The photoresist composition of the present invention may be positive or negative as long as it has the above characteristics. A positive type is preferred.
In the case of the negative type, an alkali-soluble resin is used as the component (A) and a crosslinking agent is blended. When an acid is generated from the component (B) by exposure at the time of resist pattern formation, the acid acts to cause cross-linking between the alkali-soluble resin and the cross-linking agent, and the alkali-soluble resin changes to alkali-insoluble. As the crosslinking agent, for example, an amino crosslinking agent such as melamine, urea or glycoluril having a methylol group or alkoxymethyl group is usually used.
In the case of the positive type, the component (A) is an alkali-insoluble one having a so-called acid dissociable dissolution inhibiting group, and the acid dissociable dissolution inhibiting group is dissociated when the acid generated from the component (B) by the exposure acts. As a result, the entire component (A) changes from alkali-insoluble to alkali-soluble. Therefore, when exposure is performed through a mask pattern in the formation of a resist pattern, or when post-exposure heating (PEB) is performed in addition to exposure, the exposed portion turns into alkali-soluble, while the unexposed portion remains alkali-insoluble. Therefore, a positive resist pattern can be formed by alkali development. In the case of the positive type, as the component (A), the polymer compound of the present invention is preferably used.

  In the base resin component (A), when a polymer compound having a phenolic hydroxyl group is used as a precursor as the alkali-soluble group (i), the alkali-soluble group with respect to all structural units constituting the component (A). The proportion of the structural unit having (i) is preferably 50 to 95 mol%, more preferably 55 to 90 mol%. On the other hand, the proportion of the structural unit protected by the acid dissociable, dissolution inhibiting group (ii) is preferably 3 to 50 mol%, more preferably 7 to 30 mol%.

  In the base resin component (A), when a polymer compound having an alcoholic hydroxyl group is used as a precursor as the alkali-soluble group (i), the alkali-soluble group with respect to all the structural units constituting the component (A). The proportion of the structural unit having (i) is preferably 50 to 95 mol%, more preferably 55 to 90 mol%. On the other hand, the proportion of the structural unit protected by the acid dissociable, dissolution inhibiting group (ii) is preferably 3 to 50 mol%, more preferably 5 to 35 mol%.

<Structural unit (a1)>
In the base resin component (A), when a polymer compound having a carboxyl group as an alkali-soluble group (i) is used as a precursor, the general unit as a structural unit protected by an acid dissociable, dissolution inhibiting group (ii) It is preferable to use the structural unit (a1) derived from the compound represented by the formula (2).
In this case, the structural unit (a1) and other known structural units conventionally used in chemically amplified photoresist compositions can be copolymerized and used as the base resin component (A). Examples of the other structural unit include structural units as shown in the following (a2) to (a6). As such other structural units, for example, those forming a cyclic or chain tertiary alkyl ester with a carboxyl group of (meth) acrylic acid are widely known.
As the structural unit (a1), a structural unit derived from at least one compound selected from the following general formula (39) can be used. Since these have an acetal group (—R—O—R ′; alkoxyalkyl group), for example, they tend to be dissociated by the action of an acid as compared with a structural unit (a2) described later. Therefore, even if the acid generated from the acid generator is weak (such as a diazomethane acid generator, an oxime sulfonate acid generator, or an onium salt having camphorsulfonic acid in the anion portion, which will be described later), the acid dissociable dissolution inhibiting group is sufficiently present. Can be dissociated.

(In the formula, R ′ represents a group represented by the chemical formulas (4) to (15), and R ₂ is the same as above).

  Among these, at least one selected from structural units represented by the following chemical formulas (40) to (42) is preferable.

(R ₂ is the same as above)

(R ₂ is the same as above)

(R ₂ is the same as above)

It is preferable to use the structural unit (a1) represented by the above (40) to (42) as a structural unit having an acid dissociable, dissolution inhibiting group because line edge roughness is reduced. Moreover, since it can be made to dissociate even with a weak acid, various acid generators can be used, which is preferable. Moreover, it is preferable because the exposure margin is improved. Further, the exposure area margin is also improved, which is preferable. The exposure area margin is a problem that the resist shape and dimensions change depending on the mask coverage and the in-cell coordinates (whether it is located in the periphery or the center of the exposure apparatus). .
The acetal type protecting group of the present invention has a very low deprotection energy, and since the deprotection reaction proceeds only with exposure energy, it is less susceptible to acid diffusion and deactivation, so the exposure area margin is improved. I think that.
Moreover, since a thermal decomposition point is high compared with the tertiary ester compound of (meth) acrylic acid like the structural unit (a2) mentioned later, it is preferable since thermal stability improves. Accordingly, the storage stability is also improved. Furthermore, since Tg (glass transition point) is lower than that of the structural unit (a2) described later and the protective group is dissociated at the time of exposure (the unit (a2) dissociates the protective group at the time of PEB), PEB is performed at a low temperature. be able to. That is, it is preferable because the diffusion of the acid generator can be easily controlled and the resist pattern shape can be easily controlled. Moreover, since a PEB margin also becomes favorable, it is preferable. Moreover, it is preferable also on an inorganic substrate such as a SiON substrate because it has good resolution and resist pattern shape.

  The acid dissociable, dissolution inhibiting group in the photoresist composition of the present invention may contain (a2) described later, but the unit (a1) is 50 as the acid dissociable, dissolution inhibiting group in the component (A). % By mass or more, preferably 80% by mass or more, and most preferably 100% by mass.

<Structural unit (a2)>
The structural unit (a2) is a unit derived from a (meth) acrylic acid ester containing a monocyclic group or polycyclic group-containing acid dissociable, dissolution inhibiting group, and has acid dissociation properties other than the structural unit (a1). Examples include a structural unit having a dissolution inhibiting group. These can be used as long as the effects of the present invention are not impaired.
Examples of the monocyclic group include groups obtained by removing one hydrogen atom from cycloalkane, for example, aliphatic monocyclic groups such as cyclohexyl and cyclopentyl groups. Examples of polycyclic groups include bicycloalkanes, tricycloalkanes, tetracycloalkanes, etc., groups obtained by removing one hydrogen atom from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, An aliphatic polycyclic group is mentioned. Here, many of these monocyclic groups or polycyclic groups have been proposed in ArF resists, and in the present invention, these monocyclic groups or polycyclic groups can be arbitrarily selected and used. However, it is preferable to use an aliphatic polycyclic group such as an adamantyl group, a norbornyl group, or a tetracyclododecanyl group from the viewpoint of industrial availability. Specifically, at least one structural unit selected from the following general formula (43), (44), or (45) is preferable in that it has excellent resolution and dry etching resistance.

(Wherein R ³ is a hydrogen atom or a lower alkyl group, and R ⁴ is a lower alkyl group)

(Wherein R ³ is a hydrogen atom or a lower alkyl group, and R ⁵ and R ⁶ are each independently a lower alkyl group)

(Wherein R ³ is a hydrogen atom or a lower alkyl group, and R ⁷ is a tertiary alkyl group)

In the structural unit represented by the general formula (43), the carbon atom adjacent to the oxygen atom (—O—) of the ester portion of (meth) acrylic acid is a tertiary alkyl group on a ring skeleton such as an adamantyl group. This is the case.
R ³ is a hydrogen atom or a methyl group, and further a lower alkyl group having about 2 to 5 carbon atoms, specifically an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, Examples include lower linear or branched alkyl groups such as a pentyl group, isopentyl group, and neopentyl group.
R ⁴ may be a lower linear or branched group such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, or neopentyl. Of the alkyl group. Here, if R ⁴ is an alkyl group having 2 or more carbon atoms, the acid dissociation tends to be higher than that of a methyl group, which is preferable. However, industrially, a methyl group or an ethyl group is most preferable.

In the structural unit represented by the general formula (44), the carbon atom adjacent to the oxygen atom (—O—) of the ester portion of (meth) acrylic acid is a tertiary alkyl group, and further, adamantyl is contained in the alkyl group. This is the case when a ring skeleton such as a group is present. R ³ has the same definition as in the general formula (43), and R ⁵ and R ⁶ are each an independent lower alkyl group, that is, a linear or branched alkyl group having about 1 to 5 carbon atoms. is there. Such groups tend to be more acid dissociable than 2-methyl-2-adamantyl groups. In addition, it is industrially preferable that R ⁵ and R ⁶ are both methyl groups.

The structural unit represented by the general formula (45) is not a (meth) acrylic ester part, but a carbon atom adjacent to an oxygen atom (—O—) of another ester part is a tertiary alkyl group, This is a case where the ester part and the (meth) acrylic acid ester part are connected by a ring skeleton such as a tetracyclododecanyl group. In the unit represented by the general formula (45), R ³ has the same definition as in the general formula (43), and R ⁷ is a tertiary alkyl group such as a tert-butyl group or a tert-amyl group. is there. Note that ^{R 7} is for a tert- butyl group is preferred industrially.
Among the structural units represented by the general formulas (43) to (45), particularly, the structural unit represented by the general formula (43), and R ⁴ is a methyl group or an ethyl group However, it is preferable in terms of excellent resolution.

<Structural unit (a3)>
The structural unit (a3) is a structural unit derived from a (meth) acrylic acid ester containing a lactone-containing monocyclic or polycyclic group. The lactone functional group is effective in increasing the adhesion of the photoresist film formed from the composition of the present invention to the substrate or increasing the hydrophilicity with the developer.
In addition, the lactone ring here shows one ring containing a —O—C (O) — structure, and this is counted as one ring. Therefore, here, in the case of only a lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
As the structural unit (a3), any unit can be used without particular limitation as long as it has both such a lactone functional group and a cyclic group. Specifically, examples of the lactone-containing monocyclic group include groups obtained by removing one hydrogen atom from γ-butyrolactone, and examples of the lactone-containing polycyclic group include bicycloalkanes having a lactone group, tricyclo groups. Examples include groups in which one hydrogen atom has been removed from an alkane or tetracycloalkane. In particular, a group obtained by removing one hydrogen atom from a lactone-containing tricycloalkane having the following structural formula (46) or structural formula (47) is advantageous in that it is easily available in the industry.

  Specific examples of the structural unit (a3) include structural units derived from (meth) acrylic acid esters containing a lactone-containing monocycloalkyl group or tricycloalkyl group, and more specifically, Examples include structural units represented by formulas (48) to (50).

(Wherein R ³ is a hydrogen atom or a lower alkyl group)

(Wherein R ³ is a hydrogen atom or a lower alkyl group)

(Wherein R ³ is a hydrogen atom or a lower alkyl group)

R ³ is a hydrogen atom or a methyl group, and further a lower alkyl group having about 2 to 5 carbon atoms, specifically an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, Examples include lower linear or branched alkyl groups such as a pentyl group, isopentyl group, and neopentyl group.

In addition, among the structural units represented by the general formulas (48) to (50), the general formula having an ester bond on the α carbon (for example, the effect of suppressing and reducing the proximity effect is excellent) 50), a structural unit derived from a (meth) acrylic acid γ-butyrolactone ester, that is, a γ-butyrolactone (meth) acrylic acid ester is preferred.
Moreover, the norbornane lactone ester of (meth) acrylic acid represented by the general formulas (48) and (49), that is, the structural unit derived from the (meth) acrylic acid ester of norbornane lactone is the shape of the resist pattern to be obtained, For example, it is preferable because the rectangularity is even better. In particular, the structural unit represented by the general formula (49) is preferable because of its extremely high effect.

  One (a3) unit may be used, or two or more different units may be used in combination. It is preferable to introduce two or more different lactone skeletons into the resin skeleton because the adhesion of the photoresist film to the substrate, the alkali developer affinity and the etching resistance are further improved. As the preferable lactone combination, it is preferable to use a monocyclic lactone and a polycyclic lactone in combination, and a structural unit derived from a (meth) acrylic acid ester of γ-butyrolactone represented by the general formula (50) And a structural unit derived from a (meth) acrylic ester of norbornane lactone represented by the general formula (48) or (49) is most preferable because etching resistance and substrate adhesion are improved.

<Structural unit (a4)>
The structural unit (a4) is a structural unit derived from a (meth) acrylic acid ester containing a polar group-containing polycyclic group. By having a polar group, the resin component (A) as a whole is hydrophilic with the developer. This improves the solubility and improves the alkali solubility of the exposed area, thereby contributing to the improvement of the resolution. Here, as the polycyclic group, the same polycyclic group as in the structural unit (a1) can be used. Examples of the polar group include a cyano group, a carboxyl group, and a hydroxyl group, and a hydroxyl group is preferable.
Such a structural unit (a4) is not particularly limited as long as it is a polar group-containing polycyclic group, and any unit can be used. Specifically, a hydroxyl group-containing adamantyl group, particularly a structural unit represented by the following general formula (51) is preferable in that it has an effect of increasing dry etching resistance and an effect of making the pattern cross section rectangular.

(In the formula, R ³ is the same as described above, and h is an integer of 1 to ^3. )

  Among these, those in which h is 1 and the hydroxyl group is bonded to the 3-position of the adamantyl group are preferable.

<Structural unit (a5)>
The structural unit (a5) is derived from a (meth) acrylic acid ester containing a polycyclic group-containing non-acid dissociable, dissolution inhibiting group other than the structural units (a1), (a2), (a3), and (a4). It is a structural unit.
A structural unit derived from a (meth) acrylic acid ester containing a polycyclic group-containing non-acid-dissociable, dissolution inhibiting group is a function that suppresses alkali solubility by increasing the hydrophobicity of the entire component (A) before and after exposure. Is a structural unit having That is, the alkali solubility of the entire component (A) before exposure is reduced, and the acid of the structural unit (a1) or (a2) is not dissociated by the action of an acid generated from the component (B) after exposure. A structure comprising a group having a solubility-suppressing property that reduces the alkali solubility of the entire component (A) when the entire component (A) is changed to alkali-soluble by dissociation of the dissociable dissolution-inhibiting group, as long as it does not become insoluble in alkali. Unit.

The structural unit (a5) does not overlap with the structural unit (a1), the structural unit (a2), the structural unit (a3), and the structural unit (a4). That is, the groups such as the acid dissociable, dissolution inhibiting group in the structural units (a1) and (a2), the lactone group in the structural unit (a3), and the polar group in the structural unit (a4) are not retained.
As the polycyclic group for the structural unit (a5), the same polycyclic groups as those for the structural unit (a2) can be used.

  As such a structural unit (a5), many conventionally known ArF positive resist materials can be used. In particular, tricyclodecanyl (meth) acrylate, adamantyl (meth) acrylate, tetra A structural unit derived from at least one selected from cyclododecanyl (meth) acrylate and isobornyl (meth) acrylate is preferred in terms of industrial availability. These exemplified structural units are shown below as general formulas (52) to (54). Among these, the structural unit represented by the general formula (52) is preferable because the shape of the obtained resist pattern, for example, rectangularity is particularly good.

(Wherein R ³ is a hydrogen atom or a lower alkyl group)

(Wherein R ³ is a hydrogen atom or a lower alkyl group)

(Wherein R ³ is a hydrogen atom or a lower alkyl group)

R ³ is a hydrogen atom or a methyl group, and further a lower alkyl group of about C2 to C5, specifically an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group. , A lower linear or branched alkyl group such as an isopentyl group and a neopentyl group.

<Structural unit (a6)>
The structural unit (a6) does not overlap with the units (a1) to (a5), and is represented by the following general formula (55) and is a ring bonded to an acrylate ester which may have a substituent. It is a structural unit derived from a compound composed of a formula group X ′ and a fluorinated organic group bonded to the cyclic group X ′. This fluorinated organic group is characterized in that it is formed by substituting at least part of the hydrogen atoms of the organic group with fluorine, and has an alcoholic hydroxyl group. By having the unit (a6), an improvement in alkali solubility is expected. This is preferable because the resolution is improved by increasing the dissolution contrast.

R ₂ is the same as described above. X ′ represents a divalent or trivalent cyclic group, and Y represents a divalent alkylene group having 1 to 6 carbon atoms or an alkyloxy group. p and q each independently represent an integer of 1 to 5, and s represents an integer of 1 or 2.

In the general formula, the divalent or trivalent cyclic group represented by X ′ is not particularly limited as long as it is a cyclic group, and examples thereof include aliphatic and aromatic cyclic groups. Among these, an aromatic cyclic group can be used in the photoresist composition for KrF exposure. In particular, in the photoresist composition for ArF exposure, it is preferable to use an aliphatic cyclic group from the viewpoint of improving the transparency of the photoresist film.
When X ′ is divalent, s = 1. When X ′ is trivalent, s = 2. That is, when X ′ is trivalent, two fluorinated organic groups are bonded to X ′.

  The aromatic cyclic group is not particularly limited, and various monocyclic or polycyclic divalent or trivalent aromatic cyclic groups can be used. For example, a group obtained by removing 2 or 3 hydrogen atoms from an aromatic hydrocarbon can be mentioned, and examples of the aromatic hydrocarbon include benzene, naphthalene, anthracene and the like.

The aliphatic cyclic group is not particularly limited, and various monocyclic or polycyclic divalent or trivalent aliphatic cyclic groups can be used. For example, a group obtained by removing two or three hydrogen atoms from an aliphatic cyclic hydrocarbon is exemplified. Examples of the aliphatic cyclic hydrocarbon include monocyclic aliphatic cyclics such as cyclohexane and cyclopentane. Mention may be made of hydrocarbons and polycyclic aliphatic cyclic hydrocarbons. Two or three hydrogen atoms are removed from these hydrocarbons and used as an aliphatic cyclic group.
Among these, polycyclic aliphatic hydrocarbons are more preferable, and examples thereof include adamantane, norbornane, norbornene, methylnorbornane, ethylnorbornane, methylnorbornene, ethylnorbornene, isobornane, tricyclodecane, and tetracyclododecane. Such polycyclic hydrocarbons can be appropriately selected and used from among many proposed ArF resists. Among these, adamantane, norbornane, norbornene, methylnorbornane, ethylnorbornane, methylnorbornene, ethylnorbornene, and tetracyclododecane are industrially preferable, and norbornane is most preferable.
Y is a divalent alkylene group having 1 to 6 carbon atoms or alkyloxy group, and is not particularly limited, but is preferably a methylene group. p, q, and s are each preferably 1.

  Among these, the compound represented by the following general formula (56) is most preferable.

(R ₂ is the same as above.)

<Other structural units>
In addition, in the positive photoresist composition of the present invention, as the component (A), a monomer that forms each of the structural units (a1) to (a6) is added to the conventional resists known as chemically amplified positive resists. Has an ethylenic double bond to make it soluble in alkali such as acrylic acid derivatives, methacrylic acid derivatives, acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc., which have dry etching property improving groups and non-acid dissociable, dissolution inhibiting groups Known monomers used for the production of carboxylic acid and acrylic resin can be appropriately combined and copolymerized as necessary.

  Examples of the acrylic acid derivative include naphthyl acrylate, benzyl acrylate, 3-oxocyclohexyl acrylate, an ester of acrylic acid and terpineol, and a hydroxyl group of a carboxyl group such as an ester of acrylic acid and 3-bromoacetone. Examples thereof include an acrylate ester protected with an etching property improving group or an acid non-dissociable substituent. Examples of methacrylic acid derivatives include methacrylic acid derivatives corresponding to these acrylic acid derivatives.

Examples of the carboxylic acid having an ethylenic double bond include acrylic acid, methacrylic acid, maleic acid, and fumaric acid.
Examples of known monomers used in the production of acrylic resins include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, acrylic acid Examples thereof include alkyl acrylates such as octyl, 2-ethylhexyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and the corresponding alkyl methacrylates.

<Polymer compound containing (a1)>
A preferred polymer compound as the base resin component (A) used in the positive resist composition of the present invention is a copolymer containing the structural unit (a1) and the structural unit (a3), which has good resolution and resist pattern shape. It is preferable from the point which becomes. In particular, a copolymer containing the structural unit (a1), the structural unit (a3), and the structural unit (a4) is more preferable. Moreover, the copolymer which has two mutually different structural units (a3) in a base resin component is also preferable.

When the polymer compound of the present invention is used in a binary system (copolymer of (a1) / (a3)), the structural unit (a1) is 20 to 20 times the total of all structural units of the component (A). 80 mol%, preferably 30 to 60 mol%, and the structural unit (a3) is 20 to 80 mol%, preferably 30 to 60 mol%.
When the polymer compound of the present invention is used in a binary system (copolymer of (a1) / (a6)), the structural unit (a1) is 20 to 20 times the total of all structural units of the component (A). 80 mol%, preferably 30 to 60 mol%, and the structural unit (a3) is 20 to 80 mol%, preferably 30 to 60 mol%. When the polymer compound of the present invention is used in a ternary system (copolymer of (a1) / (a3) / (a4)), the structural unit (a1) is based on the total of all structural units of the component (A). 20 to 60 mol%, preferably 30 to 50 mol%, the structural unit (a3) is 20 to 60 mol%, preferably 20 to 50 mol%, the structural unit (a4) is 10 to 50 mol%, Preferably it is 20-40 mol% because it is excellent in resolution and dry etching tolerance.

  When the polymer compound of the present invention is used in a quaternary system (copolymer of (a1) / (a3) / (a4) / (a5)), the proportion of each structural unit in the component (A) The unit (a1) is in the range of 25 to 50 mol%, preferably 30 to 40 mol%, the structural unit (a3) is in the range of 25 to 50 mol%, preferably 30 to 40 mol%, and the structural unit ( It is preferred that a4) is in the range of 10 to 30 mol%, preferably 10 to 20 mol%, and the structural unit (a5) is in the range of 3 to 25 mol%, preferably 5 to 20 mol%. . With such a range, the depth of focus of the isolated pattern formed from the obtained positive resist composition can be greatly improved, and the proximity effect can be sufficiently suppressed to greatly reduce this. In addition, if it deviates greatly from the said range, there exists a possibility that the malfunction that resolution may fall may arise.

  (A1) / (a3), (a1) / (a6), (a1) / (a3) / (a4), and (a1) / (a3) / In the copolymer (a4) / (a5), the structural unit (a2) and other structural units may be further copolymerized within the range not impairing the effects of the present invention.

The polymer compound containing (a1) is obtained by polymerizing a monomer for deriving each structural unit by known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). Can be obtained by:
The content of the base resin component (A) in the photoresist composition of the present invention may be adjusted according to the resist film thickness to be formed. For example, it adjusts so that it may become the below-mentioned preferable solid content concentration.

<(B) component>
As the acid generator component (B) used in the photoresist composition of the present invention, any compound can be appropriately selected from known compounds that generate an acid upon irradiation with radiation. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, Various kinds of acid generators such as diazomethane acid generators such as nitrobenzyl sulfonates, imino sulfonate acid generators and disulfone acid generators are known.

  Specific examples of the onium salt-based acid generator include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethane. Lomethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoro Lomethanesulfonate, its heptafluoropropanesulfonate, or Nonafluorobutanesulfonate, trifluoromethanesulfonate of monophenyldimethylsulfonium, heptafluoropropanesulfonate or nonafluorobutanesulfonate thereof, trifluoromethanesulfonate of diphenylmonomethylsulfonium, heptafluoropropanesulfonate or nonafluorobutanesulfonate thereof, etc. It is done. Of these, onium salts having a fluorinated alkyl sulfonate ion as an anion are preferable.

  Among the onium salt acid generators, an onium salt having a weak acid strength and having a camphorsulfonic acid ion in the anion portion can be used. Specifically, the compound etc. which are represented by following Chemical formula (57) can be illustrated.

  Specific examples of the oxime sulfonate acid generator include α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino). -Phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile , Α- (methylsulfonyloxyimino) -p-bromophenylacetonitrile and the like. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

Among the diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane. Bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like.
Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane (Compound A, decomposition point 135 ° C.), 1,4-bis (phenyl) having the following structure. Sulfonyldiazomethylsulfonyl) butane (compound B, decomposition point 147 ° C.), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C, melting point 132 ° C., decomposition point 145 ° C.), 1,10-bis (phenyl) Sulfonyldiazomethylsulfonyl) decane (compound D, decomposition point 147 ° C.), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (compound E, decomposition point 149 ° C.), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) ) Propane (Compound F, decomposition point 153 ° C.), , 6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (Compound G, melting point 109 ° C., decomposition point 122 ° C.), 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane (Compound H, decomposition point 116 ° C.), etc. Can be mentioned.

As the component (B), one type of acid generator may be used alone, or two or more types may be used in combination.
(B) Content of a component is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-15 mass parts. If the amount is less than the above range, pattern formation may not be sufficiently performed, and if the amount exceeds the above range, a uniform solution is difficult to obtain, which may cause a decrease in storage stability.

<(D) component>
If necessary, the photoresist composition may further contain a nitrogen-containing organic compound (D). It is already known to mix a small amount of a nitrogen-containing compound as an acid diffusion inhibitor in a chemically amplified resist composition. Also in the present invention, such a known nitrogen-containing organic compound can be added. Examples of such nitrogen-containing organic compounds include amines and ammonium salts.

  Examples of the amine include aliphatic secondary amines such as diethylamine, dipropylamine, dibutylamine, dipentylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, N, N-dimethylpropylamine, N- Aliphatic tertiary amines such as ethyl-N-methylbutylamine, trihexylamine, triheptylamine, trioctylamine, tridecanylamine, tridodecylamine, tritetradecanylamine (trialkylamine, nitrogen in the above) The three alkyl groups bonded to may be the same or different.), N, N-dimethylmonoethanolamine, triisopropanolamine, N, N-diethylmonoethanolamine, triethanolamine, tributanol Tertiary alkanolamines such as N, N-dimethylaniline, N, N-diethylaniline, N-ethyl-N-methylaniline, N, N-dimethyltoluidine, N-methyldiphenylamine, N-ethyldiphenylamine, tri Aromatic tertiary amines such as phenylamine can be mentioned.

Examples of the ammonium salts include quaternary alkylammonium ions such as ammonium ion, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, and tetrapentylammonium ion, and an organic carboxyl having a hydroxyl group such as lactic acid. Mention may be made of salts with acid ions.
Among these, lower tertiary alkanolamines such as triethanolamine, triisopropanolamine, tributanolamine, trihexylamine, triheptylamine, trioctylamine, tridecanylamine, tridodecylamine, tritetradecanylamine A trialkylamine having 6 to 15 carbon atoms is preferable because it is excellent in the effect of reducing the film loss at the top portion of a fine resist pattern.

  The nitrogen-containing organic compound (D) is usually used in a range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the base resin component (A). If the amount is less than this range, the effect of improving the shape of the pattern due to the effect of inhibiting the diffusion of acid generated by exposure cannot be obtained. If the amount is too large, the diffusion of the acid is excessively inhibited and so-called exposure sensitivity is deteriorated. .

<Acid component>
In the present invention, an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof can be further added as an optional component for the purpose of preventing sensitivity deterioration due to the addition of the nitrogen-containing organic compound (D). .

  Suitable examples of the organic carboxylic acid include malonic acid, citric acid, malic acid, succinic acid, benzoic acid, and salicylic acid.

  Examples of the phosphorous oxo acid or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, and phosphonic acid. Of phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and their esters, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable. The organic carboxylic acid or phosphorus oxo acid or derivative component thereof is used in a proportion of 0.01 to 5.0 parts by mass per 100 parts by mass of the resin component (A).

<Organic solvent (E)>
In the photoresist composition of the present invention, the base resin component (A), the acid generator (B), the nitrogen-containing organic compound (D), and an optional component to be added as necessary are mixed with an organic solvent (E 1) or any two or more of conventionally known solvents for chemical amplification resists can be appropriately selected and used. it can.

  Examples of the organic solvent include ketones such as γ-butyrolactone, acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol. Polyacetates such as monoacetate, dipropylene glycol, or monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate and derivatives thereof, and cyclic ethers such as dioxane And methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, pyruvate ester Le, methyl methoxypropionate, esters such as ethyl ethoxypropionate can be exemplified. These organic solvents may be used independently and may be used as 2 or more types of mixed solvents. The blending ratio of propylene glycol monomethyl ether acetate (PGMEA) and the polar solvent may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 1: 9 to 9: 1, more preferably It is preferable to be in the range of 2: 8 to 8: 2.

  More specifically, when ethyl lactate (EL) is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 2: 8 to 8: 2, more preferably 3: 7 to 7: 3. preferable. In addition, as the organic solvent, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5. The amount of the component (E) used is not particularly limited, but is a concentration that can be applied to a substrate and the like, and is appropriately set according to the coating film pressure. In general, the solid content concentration of the photoresist composition is 2 It is made into the range of -20 mass%, Preferably it is 5-15 mass%.

<Other ingredients>
Further, the photoresist composition of the present invention may further contain miscible additives as desired, for example, known dissolution inhibitors, additional resins for improving the performance of the photoresist film, and coating properties. Surfactants, plasticizers, stabilizers, colorants, antihalation agents, and the like can be added.

  In addition, the compound having an alcoholic hydroxyl group, a phenolic hydroxyl group, or a carboxyl group protected with the acid dissociable, dissolution inhibiting group (ii) of the present invention can also be used as a dissolution inhibitor. Preferably, the alkali-soluble group (i), particularly the alcoholic hydroxyl group, the phenolic hydroxyl group, and the carboxyl group in the monomer component corresponding to each structural unit of the chemical formulas (21) to (35) are acid dissociable according to the present invention. A compound protected with the dissolution inhibiting group (ii) can be used as a dissolution inhibitor. A photoresist composition containing such a compound as an acid dissociable dissolution inhibitor (C) together with the base resin component (A) exhibits a dissolution inhibiting action on alkali development before exposure, and after the exposure process. Expresses alkali solubility due to deprotection. Thereby, the resist film can be prevented from slipping and a fine pattern with high resolution can be provided.

  In particular, the compound of the present invention has an acid dissociable, dissolution inhibiting group having an aliphatic cyclic group in the molecule, and the alkali solubility is greatly changed by the action of an acid. Therefore, according to the polymer compound of the present invention having a structural unit derived from the compound, the rectangularity, the resolution and the sensitivity are good in the chemically amplified photoresist system, and it is generated from the acid generator. Even if the acid is weak, the acid dissociable, dissolution inhibiting group is sufficiently dissociated to realize a photoresist composition exhibiting good photoresist performance.

In addition, in the photoresist composition of the present invention, the etching resistance is improved, particularly when a hydrophilic group is further introduced, the adhesion of the resist pattern to the substrate is improved, and the affinity for an alkali developer is increased. The improvement can reduce the development defects.
The photoresist composition of the present invention can be suitably used for patterning of a semiconductor integrated circuit by lithography. In particular, excellent resolution characteristics can be achieved in fine patterning using a light source having a wavelength of 300 nm or less, particularly KrF, ArF, or F ₂ excimer laser. Among these, an ArF excimer laser is most preferable. Furthermore, it is also effective for electron beams.

  The resist pattern forming method of the present invention includes a step of forming a photoresist film on a substrate using such a photoresist composition, a step of exposing the photoresist film, and developing the photoresist film to form a resist pattern. Including the step of:

The photoresist composition of the present invention forms a resist pattern by a normal lithography process. In such a method, first, a photoresist composition is applied onto a substrate by spin coating or the like and dried to form a photoresist film. Then, it selectively exposes through a mask pattern and heats after exposure (PEB). Finally, the resist pattern can be formed by developing with an alkaline aqueous solution. In addition, you may perform a post-baking process as needed. The light source is not limited, but far ultraviolet light of 200 nm or less, specifically ArF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet light), electron beam, soft X-ray, X-ray, etc. Can be used. In particular, a KrF excimer laser, an ArF excimer laser, and an F ₂ excimer laser are preferable. In particular, when a polymer compound (copolymer) using the novel compound of the present invention is used, an ArF excimer laser is preferable. Furthermore, it is also effective for electron beams.

  Conditions at the time of resist pattern formation, that is, the number of revolutions of resist coating, pre-baking temperature, exposure conditions, post-exposure heating (PEB) conditions, and alkali development conditions may be those conventionally used. Specifically, the rotational speed is about 1200 to 3500 rpm, more specifically about 2000 rpm, and the pre-bake (PB) temperature is in the range of 70 to 130 ° C., thereby forming a resist film thickness of 80 to 300 nm. To do. The exposure may be performed through a mask. A normal binary mask is used as the mask in the selective exposure. As such a mask, a phase shift mask may be used. The post-exposure heating (PEB) temperature is in the range of 90 to 140 ° C., and the alkali development conditions are 1 to 5% by mass of TMAH (tetramethylammonium hydroxide) developer and developed at 23 ° C. for 15 to 90 seconds. Then, rinse with water.

[Synthesis Example 1] 4-oxo-2-adamantyl chloromethyl ether (compound represented by the chemical formula (58). Hereinafter, only the formula number and (58) etc. may be described after the compound name). Synthesis Paraformaldehyde was added to 4-oxo-2-hydroxyadamantane, and 2.5 equivalents of hydrogen chloride gas was blown into 4-oxo-2-hydroxyadamantane, followed by reaction at 50 ° C. for 12 hours. After completion of the reaction, the product was distilled under reduced pressure to obtain 4-oxo-2-adamantyl chloromethyl ether (Compound 1) represented by the following chemical formula (58).

[Synthesis Example 2] Synthesis of 2-adamantyl chloromethyl ether (59) Paraformaldehyde was added to 2-hydroxyadamantane, and 2.5 equivalents of hydrogen chloride gas was blown into 2-hydroxyadamantane, followed by reaction at 50 ° C for 12 hours. I let you. After completion of the reaction, the product was distilled under reduced pressure to obtain 2-adamantyl chloromethyl ether (compound 2) represented by the following chemical formula (59).

[Synthesis Example 3] Synthesis of 1-adamantylmethyl chloromethyl ether (60) Paraformaldehyde was added to adamantane-1-methanol, and 2.5 equivalents of hydrogen chloride gas was blown into adamantane-1-methanol at 50 ° C. The reaction was performed for 12 hours. After completion of the reaction, the product was distilled under reduced pressure to obtain 1-adamantylmethyl chloromethyl ether (compound 3) represented by the following chemical formula (60).

[Synthesis Example 4] Synthesis of 2-adamantyloxymethyl methacrylate (61) 6.9 g of methacrylic acid was dissolved in 200 mL of tetrahydrofuran, and 8.0 g of triethylamine was added. After stirring at room temperature, 100 mL of tetrahydrofuran in which 15 g of compound 2 (59) was dissolved was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was evaporated, dissolved in 200 mL of ethyl acetate, washed with pure (100 mL × 3), and evaporated. After standing under ice cooling, a white solid was obtained. This compound is referred to as compound 4 and represented by chemical formula (61). Infrared absorption spectrum (IR), showing the results of measurement of the proton nuclear magnetic resonance spectra ⁽¹ H-NMR). IR (cm ^-1 ): 2907, 2854 (CH stretch), 1725 (C = O stretch), 1638 (C = C stretch) ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane) ppm: 1.45 -2.1 (m, 17H), 3.75 (s, 1H), 5.45 (s, 2H), 5.6 (s, 1H), 6.12 (s, 1H)

[Synthesis Example 5] Synthesis of 4-oxo-2-adamantyloxymethyl methacrylate (62) 2.2 g of methacrylic acid was dissolved in 50 mL of tetrahydrofuran, and 2.5 g of triethylamine was added. After stirring at room temperature, 50 mL of tetrahydrofuran in which 4.3 g of Compound 1 (58) was dissolved was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was evaporated, dissolved in 100 mL of ethyl acetate, washed with pure (50 mL × 3), and evaporated. A white solid was obtained after standing under ice cooling. This compound is referred to as compound 5 and represented by chemical formula (62). Infrared absorption spectrum (IR), showing the results of measurement of the proton nuclear magnetic resonance spectra ⁽¹ H-NMR). IR (cm ^-1 ): 2926, 2861 (CH stretch), 1725 (C = O stretch), 1636 (C = C stretch) ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane) ppm: 1. 62-3.85 (m, 15H), 4.2 (s, 1H), 5.4 (s, 2H), 5.65 (s, 1H), 6.15 (s, 1H)

[Synthesis Example 6] Synthesis of 1-adamantylmethyloxymethyl methacrylate (63) 5.5 g of methacrylic acid was dissolved in 200 mL of tetrahydrofuran, and 6.5 g of triethylamine was added. After stirring at room temperature, 100 mL of tetrahydrofuran in which 12.9 g of compound 3 (60) was dissolved was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was evaporated, dissolved in 100 mL of ethyl acetate, washed with pure (100 mL × 3) and evaporated to give a colorless oil. This compound is referred to as compound 6 and represented by chemical formula (63). Infrared absorption spectrum shows the results of measurement of the proton nuclear magnetic resonance spectra ⁽¹ H-NMR). IR (cm ^-1 ): 2904, 2850 (CH stretch), 1727 (C = O stretch), 1638 (C = C stretch) ¹ H-NMR (CDCl ₃ , internal standard: tetramethylsilane) ppm: 1. 46-1.96 (m, 18H), 3.22 (s, 2H), 5.34 (s, 2H), 5.6 (s, 1H), 6.15 (s, 1H)

<Synthesis of Resin 5 from Resin 1 Having Structural Unit (a1)>
[Synthesis Example 7] Synthesis of Resin 1 (polymer compound represented by chemical formula (64). Hereinafter, (64) and the like and only the formula number may be described simply after the resin number) 8.0 g of compound 4 and 5.4 g of γ-butyrolactone methacrylate were dissolved in 50 mL of tetrahydrofuran, and 0.52 g of azobisisobutyronitrile was added. After refluxing for 24 hours, the reaction solution was added dropwise to 1 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as resin 1 and represented by chemical formula (64). The molecular weight (Mw) of Resin 1 was 21100. Further, as a result of measuring carbon 13 (meaning carbon having a mass number of 13; hereinafter the same) nuclear magnetic resonance spectrum ( ¹³ C-NMR), the composition ratio (mol%, the same applies hereinafter) in the formula was m: n = 0.49: 0.51.

[Synthesis Example 8] Synthesis of Resin 2 (65) 1.0 g of Compound 4, 0.68 g of γ-butyrolactone methacrylate, and 0.47 g of 3-hydroxy-1-adamantyl methacrylate are dissolved in 20 mL of tetrahydrofuran. 0.08 g of azobisisobutyronitrile was added. After refluxing for 24 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as a resin 2 and represented by the chemical formula (65). The molecular weight (Mw) of this resin 2 was 11500. Moreover, as a result of measuring carbon-13 nuclear magnetic resonance spectrum ( ^13C -NMR), the composition ratio in the formula was m: n: l = 0.34: 0.42: 0.24.

[Synthesis Example 9] Synthesis of Resin 3 (66) 1.0 g of Compound 4, 0.68 g of γ-butyrolactone methacrylate, and 0.44 g of 3-hydroxy-1-adamantyl acrylate were dissolved in 20 mL of tetrahydrofuran. 0.08 g of azobisisobutyronitrile was added. After refluxing for 24 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as resin 3 and represented by chemical formula (66). The molecular weight (Mw) of this resin 3 was 10800. Moreover, as a result of measuring carbon-13 nuclear magnetic resonance spectrum (< ¹³ > C-NMR), composition ratio was m: n: l = 0.29: 0.45: 0.26.

[Synthesis Example 10] Synthesis of Resin 4 (67) 1.0 g of Compound 4 and 0.68 g of γ-butyrolactone methacrylate ester, norbornanelactone methacrylate ester (a structural unit in which R ^{3 in the} general formula (49) is a methyl group Monomer corresponding to) was dissolved in 20 mL of tetrahydrofuran, and 0.08 g of azobisisobutyronitrile was added. After refluxing for 24 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as resin 4 and represented by chemical formula (67). The molecular weight (Mw) of this resin 4 was 12000. Moreover, as a result of measuring carbon-13 nuclear magnetic resonance spectrum ( ^13C -NMR), composition ratio was m: n: l = 0.37: 0.42: 0.21.

[Synthesis Example 11] Synthesis of Resin 5 (68) 1.0 g of Compound 4, 0.68 g of γ-butyrolactone methacrylate ester, norbornanelactone methacrylate ester (a structural unit in which R ^{3 in the} general formula (48) is a methyl group Monomer corresponding to) was dissolved in 20 mL of tetrahydrofuran, and 0.08 g of azobisisobutyronitrile was added. After refluxing for 24 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as resin 5 and represented by chemical formula (68). The molecular weight (Mw) of this resin 5 was 12900. Moreover, as a result of measuring carbon-13 nuclear magnetic resonance spectrum ( ^13C -NMR), the composition ratio was m: n: l = 0.36: 0.42: 0.22.

<Synthesis of Resin 9 from Resin 7 whose Alkali-Soluble Group is Alcoholic Hydroxyl Group>
Using resin 6 synthesized by addition polymerization, resin 9 was obtained from resin 7 into which compounds 1 to 3 were introduced. Resins 6 to 9 are represented by the following chemical formulas (69) to (72), respectively. The physical properties of these resins are shown in Table 1.

[Synthesis of Resin 6 (69)]
Resin 6 represented by Chemical Formula (69) was synthesized using an addition polymerization reaction using a known metal catalyst. X in the formula is 100.

[Synthesis Example 12] Synthesis of Resin 7 (70) 5.0 g of Resin 6 was dissolved in 70 mL of tetrahydrofuran, and 0.15 g of sodium hydride was added. After stirring at room temperature until the solution system became uniform, 0.8 g of Compound 1 was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was added dropwise to 1 L of water. The precipitated resin was separated by filtration, dried under reduced pressure, dissolved in tetrahydrofuran, and dropped into 1 L of a mixture of methanol: pure water (80:20). The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as Resin 7.

[Synthesis Example 13] Synthesis of Resin 8 (71) 5.0 g of Resin 6 was dissolved in 70 mL of tetrahydrofuran, and 0.15 g of sodium hydride was added. After stirring at room temperature until the solution system became uniform, 0.7 g of Compound 2 was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was added dropwise to 1 L of water. The precipitated resin was separated by filtration, dried under reduced pressure, dissolved in tetrahydrofuran, and dropped into 1 L of a mixture of methanol: pure water (80:20). The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as Resin 8.

[Synthesis Example 14] Synthesis of Resin 9 (72) 5.0 g of Resin 6 was dissolved in 70 mL of tetrahydrofuran, and 0.15 g of sodium hydride was added. After stirring at room temperature until the solution system became uniform, 0.8 g of Compound 3 was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was added dropwise to 1 L of water. The precipitated resin was separated by filtration, dried under reduced pressure, dissolved in tetrahydrofuran, and dropped into 1 L of a mixture of methanol: pure water (80:20). The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as “resin 9”.

<Synthesis of Resin 10 (74) in which the alkali-soluble group is a phenolic hydroxyl group>
[Synthesis Example 15] Synthesis of Resin 10 (74) 24.0 g of poly-4-hydroxystyrene resin (73) represented by the following chemical formula (73) was dissolved in 200 mL of tetrahydrofuran, and 2.4 g of sodium hydride was added. It was. After stirring until the solution system became uniform at room temperature, 12 g of Compound 2 was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was added dropwise to 1 L of water. The precipitated resin was separated by filtration, dried under reduced pressure, dissolved in tetrahydrofuran and added dropwise to 3 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin 10.
The molecular weight (Mw) of the resin 10 was 12400, and the dispersity (Mw / Mn) was 1.28. As a result of measurement of a proton nuclear magnetic resonance spectra ⁽¹ H-NMR), the compositional ratio in the chemical formula (74) is m: n = 0.87: 0.13.

<Synthesis of Resin 14 from Resin 11 Having Structural Unit (a1)>
[Synthesis Example 16] Synthesis of Resin 11 (75) 3.0 g of Compound 4 and 2.0 g of γ-butyrolactone methacrylate were dissolved in 45 mL of tetrahydrofuran, and 0.20 g of azobisisobutyronitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as a resin 11 and represented by the chemical formula (75). The resin 11 had a molecular weight (Mw) of 12300 and a dispersity (Mw / Mn) of 1.96. Further, as a result of measuring a carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR), the composition ratio in the formula was m: n: l = 0.47: 0.53. Moreover, the thermal decomposition point was 257.1 degreeC and Tg was 147.9 degreeC. In this synthesis example and comparative synthesis example, the thermal decomposition point was measured with a thermal analyzer DSC6200 (manufactured by Seiko Instrument) under a temperature rising condition of 10 ° C./min. In addition, Tg (glass transition point) was measured with a thermal analyzer TG / DTA6200 (manufactured by Seiko Instrument Co., Ltd.) under a temperature rising condition of 10 ° C / min.

[Synthesis Example 17] Synthesis of Resin 12 (77) 3.0 g of Compound 4 and 4.0 g of Compound 7 represented by the following chemical formula (76) were dissolved in 60 mL of tetrahydrofuran to obtain azobisisobutyronitrile 0. .20 g was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as a resin 12 and represented by the chemical formula (77). The resin 12 had a molecular weight (Mw) of 9800 and a dispersity (Mw / Mn) of 1.61. Moreover, as a result of measuring a carbon-13 nuclear magnetic resonance spectrum ( ^13C -NMR), the composition ratio in the formula was m: n = 0.57: 0.43. Moreover, the thermal decomposition point was 234.5 degreeC and Tg was 114.1 degreeC.

[Synthesis Example 18] Synthesis of Resin 13 (78) 6.0 g of Compound 6 and 3.9 g of γ-butyrolactone methacrylate were dissolved in 90 mL of tetrahydrofuran, and 0.37 g of azobisisobutyronitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as a resin 13 and represented by the chemical formula (78). This resin 13 had a molecular weight (Mw) of 12800 and a dispersity (Mw / Mn) of 1.87. Moreover, as a result of measuring a carbon 13 nuclear magnetic resonance spectrum ( ^13C -NMR), the composition ratio in the formula was m: n = 0.43: 0.57. Moreover, the thermal decomposition point was 240.0 degreeC and Tg was 142.2 degreeC.

[Synthesis Example 19] Synthesis of Resin 14 (79) 6.0 g of Compound 6 and 7.6 g of Compound 7 were dissolved in 120 mL of tetrahydrofuran, and 0.37 g of azobisisobutyronitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as the resin 14 and represented by the chemical formula (79). This resin 14 had a molecular weight (Mw) of 11600 and a dispersity (Mw / Mn) of 1.60. Moreover, as a result of measuring a carbon 13 nuclear magnetic resonance spectrum ( ^13C -NMR), the composition ratio in the formula was m: n = 0.56: 0.44. Moreover, the thermal decomposition point was 233.6 degreeC and Tg was 109.4 degreeC.

<Synthesis of Comparative Resins 1-4 as Comparative Examples>
Comparative Synthesis Example 1 Synthesis of Comparative Resin 1 (80) 9.9 g of 2-methyl-2-adamantyl methacrylate and 6.0 g of γ-butyrolactone methacrylate were dissolved in 140 mL of tetrahydrofuran to obtain azobisisobutyro. 0.63 g of nitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as a comparative resin 1 and represented by the chemical formula (80). The comparative resin 1 had a molecular weight (Mw) of 8700 and a dispersity (Mw / Mn) of 1.83. Moreover, as a result of measuring a carbon 13 nuclear magnetic resonance spectrum ( ^13C -NMR), the composition ratio in the formula was m: n = 0.41: 0.59. Moreover, the thermal decomposition point was 222.5 degreeC and Tg was 158.9 degreeC.

Comparative Synthesis Example 2 Synthesis of Comparative Resin 2 (81) 10.6 g of 2-methyl-2-adamantyl methacrylate and 15.0 g of Compound 7 were dissolved in 230 mL of tetrahydrofuran to obtain 0.74 g of azobisisobutyronitrile. Was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as a comparative resin 2 and represented by the chemical formula (81). The comparative resin 2 had a molecular weight (Mw) of 8780 and a dispersity (Mw / Mn) of 1.42. Moreover, as a result of measuring a carbon 13 nuclear magnetic resonance spectrum ( ^13C -NMR), the composition ratio in the formula was m: n = 0.64: 0.36. Moreover, the thermal decomposition point was 215.7 degreeC and Tg was 133.3 degreeC.

[Comparative Synthesis Example 3] Synthesis of Comparative Resin 3 (83) 100 g of 15 g (mass average molecular weight = 7640, dispersity = 1.93) of comparative resin 3 '(Promerus) represented by the following chemical formula (82) Was dissolved in tetrahydrofuran and 0.88 g of sodium hydride was added. After stirring until the solution system became uniform at room temperature, 1.76 g of chloromethyl methyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise. After stirring for 12 hours at room temperature, the precipitated salt was filtered off. The obtained filtrate was added dropwise to 1 L of water. The precipitated resin was separated by filtration, dried under reduced pressure, dissolved in tetrahydrofuran, and added dropwise to 1 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. Yield 5.0 g. This resin is referred to as a comparative resin 3 and represented by the chemical formula (83). In this comparative resin 3, the mass average molecular weight (Mw) was 14,000, the dispersity (Mw / Mn) was 2.14, and the hydroxyl group protection rate was 40.7%.

[Comparative Synthesis Example 4] Synthesis of Comparative Resin 4 (83) In Comparative Synthesis Example 3, the protection rate was changed. That is, the reaction was carried out using the same method except that the amount of chloromethyl methyl ether was adjusted. The obtained resin had a mass average molecular weight (Mw) of 13,900, a dispersity (Mw / Mn) of 2.23, and a hydroxyl group protection ratio of 20.8%. This is designated as comparative resin 4. It is represented by chemical formula (83).

[Examples 1 to 3 (reference example)] Confirmation of exposure resolution of positive photoresist Using resins 7 to 9, the resolution of the positive photoresist was confirmed by ArF exposure. Positive photoresist compositions were prepared for resins 7 to 9 using the following acid generator, nitrogen-containing organic compound, and solvent.
Resins 7-9 100 parts by weight Acid generator: TPS-PFBS 2.0 parts by weight Nitrogen-containing organic compound: Triisopropanolamine 0.2 parts by weight Solvent: PGMEA 1250 parts by weight

  “TPS-PFBS” represents triphenylsulfonium nonafluorobutanesulfonate. “PGMEA” represents propylene glycol monomethyl ether acetate.

The exposure resolution of the positive photoresist was confirmed under the conditions shown in Table 2 below.
“Development conditions: NMD-3 2.38% (manufactured by Tokyo Ohka Kogyo) for 30 seconds” means that NMD-3 2.38% (product name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is used and the development time is 30 seconds. Indicates development.

「現像条件：ＮＭＤ−３ ２．３８％（東京応化工業製）の３０秒」とは、ＮＭＤ−３ ２．３８％（製品名、東京応化工業製）を用い、現像時間３０秒の条件で現像したことを示す。

“Development conditions: NMD-3 2.38% (manufactured by Tokyo Ohka Kogyo) for 30 seconds” means that NMD-3 2.38% (product name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is used and the development time is 30 seconds. Indicates development.

The above exposure resolution evaluation is shown in Table 3 below. A positive-type photoresist composition (Examples 1 to 3) each containing resins 7 to 9 which are specific examples of the polymer compound of the present invention provides a 120 nm line-and-space pattern 1: 1. It became clear that the shape shows rectangularity. The exposure amount at this time was 14 to 15 mJ / cm ² , and good sensitivity was obtained.

[Example 4 (reference example)]
Using resin 1, the positive photoresist performance was confirmed from the change in the resist film thickness when the exposure amount of the ArF excimer laser was changed. The positive photoresist composition was prepared using the following acid generator, nitrogen-containing organic compound, and solvent. The resist film thickness was adjusted to 200 nm. FIG. 1 shows a sensitivity curve representing a change in resist film thickness with respect to the obtained change in exposure amount.
Resin 1 100 parts by mass Acid generator: TPS-PFBS 2.0 parts by mass Nitrogen-containing organic compound: Triisopropanolamine 0.2 parts by mass Solvent: PGMEA 1250 parts by mass

  As is clear from the sensitivity curve by ArF exposure in FIG. 1, the performance of the positive photoresist could be confirmed. The sensitivity was good.

[Examples 5 to 8 (reference examples)]
Using resins 2 to 5, the resolution of the positive photoresist was confirmed by ArF exposure. A positive photoresist composition was prepared for each of the resins 2 to 5 using the following acid generator, nitrogen-containing organic compound, and solvent.
Resins 2 to 5 100 parts by mass Acid generator: TPS-PFBS 3.0 parts by mass Nitrogen-containing organic compound: Triisopropanolamine 0.35 parts by mass Solvent: PGMEA 1250 parts by mass GBL 125 parts by mass

“GBL” represents γ-butyrolactone.
The exposure resolution of the positive photoresist was confirmed under the conditions shown in Table 4 below.

  The above exposure resolution evaluation is shown in Table 5 below. A positive-type photoresist composition (Examples 5 to 8) containing resins 2 to 5, which are specific examples of the polymer compound of the present invention, gives a 120 nm line-and-space pattern 1: 1. It became clear that the shape shows rectangularity. Table 5 shows the exposure amount (sensitivity) at that time.

[Examples 9 to 19 (Examples 9 to 11 and 15 to 16 are reference examples), Comparative Examples 1 to 8]
After preparing a positive resist composition having the composition shown in Table 6 below, a resist pattern was formed and evaluated under the conditions shown in Table 7. The results are shown in Table 8.

Abbreviations in Table 6 are shown.
PAG1: triphenylsulfonium nonafluorobutanesulfonate PAG2: bis (2,4-dimethylphenylsulfonyl) diazomethane represented by the following chemical formula (84)

PAG3: camphorsulfonic acid of triphenylsulfonium represented by the following chemical formula (85)

PGMEA: Propylene glycol monomethyl ether acetate EL: Ethyl lactate

  The conditions of Comparative Examples 7 and 8 were the conditions shown in Table 2, and the resist film pressure was changed to 200 nm.

When PAG2 was used, the resolution was not resolved in Comparative Examples 2 and 5, whereas in Examples 10, 13, and 18, line and space resist patterns were obtained.
When PAG3 was used, Comparative Example 3 did not resolve, and Comparative Example 6 obtained a 170 nm line and space pattern. Compared with these, Examples 11, 14, and 19 had both resolution and sensitivity. Improved.
A line-and-space pattern having a line width of 120 nm and a pitch of 240 nm was formed, and each of Example 9, Example 12, Example 15, Comparative Example 1, and Comparative Example 4 was LER (line edge roughness: line edge roughness) 3σ, which is a scale indicating non-uniform irregularities of the above). In this example, 3σ was measured by a side length SEM (manufactured by Hitachi, Ltd., trade name “S-9220”). The smaller this 3σ, the smaller the roughness and the uniform width resist pattern was obtained. Means. As a result, it was 6.4 nm in Example 9, 5.4 nm in Example 12, 6.9 nm in Example 15, 9.0 nm in Comparative Example 1, and 6.9 nm in Comparative Example 4. Also from this, it was found that LER was reduced by using the structural unit (a1) of the present invention.
When PAG1 was used, the resolution was substantially the same, but an improvement in sensitivity was observed in the examples.

[Examples 20 to 21 (Example 20 is a reference example), Comparative Example 9]
The resist compositions having the compositions shown in Table 9 below were prepared, and after forming resist patterns under the mounting conditions shown in Table 10 below, the evaluation results are summarized in Table 11.

In Table 11, sensitivity and LER are as follows.
Sensitivity: For Examples 20 to 21, the sensitivity was measured when the size of the 100 nm line and space pattern was 1: 1. For Comparative Example 9, the sensitivity was measured when the size of the 160 nm line and space pattern was 1: 1.
LER: For Examples 20 to 21, LER with a 100 nm line and space pattern size of 1: 1 was measured. For Comparative Example 9, the LER was measured when the size of the 160 nm line and space pattern was 1: 1.

  From the above results, even when an electron beam was used as the exposure light source, the resist composition of the present invention was excellent in resolution, sensitivity, and LER.

[Synthesis Examples 20 to 25]
Resins 15 to 20 having the same structural formula shown below and different composition ratios were synthesized in the same manner as in Synthesis Example 8. The results are shown in Table 12.

[Synthesis Example 26]
38.8 g of (4-oxo-2-adamantyloxy) methyl methacrylate (corresponding to compound 5 of Synthesis Example 5) and 25.0 g of γ-butyrolactone methacrylate were dissolved in 640 mL of tetrahydrofuran, and azobisisobutyronitrile 2 .41 g was added. After refluxing for 6 hours, the reaction solution was added dropwise to 2 L of methanol. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as resin 21, and the structural formula is shown below. The molecular weight (Mw) of the resin 21 was 12400, and the dispersity (Mw / Mn) was 2.01. Moreover, as a result of measuring a carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR), the composition ratio was m: n = 0.48: 0.52. The results are shown in Table 12.

[Comparative Synthesis Example 5]
18.7 g of 2-methyl-2-adamantyl methacrylate, 13.6 g of γ-butyrolactone methacrylate and 9.5 g of 3-hydroxy-1-adamantyl methacrylate are dissolved in 200 ml of tetrahydrofuran to obtain azobisisobutyronitrile 1 .64 g was added. After refluxing for 6 hours, the reaction solution was added dropwise to 1 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as Comparative Resin 5 and the structural formula is shown below. Comparative resin 5 had a mass average molecular weight (Mw) of 10,000 and a dispersity (Mw / Mn) of 2.0. Met. Further, as a result of measuring the carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR), the composition ratio of each structural unit represented by the following structural formula was m: n: l = 0.4: 0.4: 0.2. It was.

[Comparative Synthesis Example 6]
Comparative resin 6 was synthesized in the same manner as in Comparative Synthesis Example 1. Comparative resin 6 had a weight average molecular weight (Mw) of 9,200 and a dispersity (Mw / Mn) of 1.96. Met. Further, as a result of measuring a carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR), the composition ratio of each structural unit represented by the following structural formula was m: n = 0.44: 0.56.

[Examples 22 to 27 (Reference Example), Comparative Example 10]
A positive resist composition having the composition shown in Table 13 below was prepared.
Next, an organic antireflection film material (trade name ARC-29, manufactured by Brewer Science Co., Ltd.) was applied onto an 8-inch silicon wafer, and baked at 225 ° C. for 60 seconds to form an antireflection film to obtain a substrate.
On the substrate, the positive resist composition obtained above was uniformly applied using a spinner, pre-baked (PAB) under the conditions shown in Table 14, and dried to form a resist layer. Subsequently, it selectively exposed through the mask using ArF exposure apparatus (wavelength 193 nm) NSR-S302 (made by Nikon, NA (numerical aperture) = 0.60, 2/3 annular illumination).
Then, PEB treatment was performed under the conditions shown in Table 14, followed by paddle development with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 30 seconds, followed by water rinsing with pure water for 30 seconds, and shaken off and dried. And a 140 nm line and space (1: 1) resist pattern (hereinafter referred to as an L / S pattern) was formed.

  The following evaluation was performed and the results are shown in Table 15.

[Exposure margin]
Obtained from the exposure amount (sensitivity) (EOP) for resolving a 140 nm L / S pattern exactly 1: 1, and the exposure amount fluctuation range (sensitivity fluctuation range) for resolving an L / S pattern of ± 10% of 140 nm. The obtained exposure margin was calculated from the following equation.
Exposure margin = [E (126 nm) −E (154 nm)] × 100 / EOP
EOP: Sensitivity when obtaining L / S of 140 nm exactly 1: 1 (mJ / cm ² )
E (154 nm): Sensitivity when obtaining L / S of 154 nm (mJ / cm ² )
E (126 nm): Sensitivity when obtaining L / S of 126 nm (mJ / cm ² )

[Example 28 (reference example), comparative example 11]
A positive resist composition having the composition shown in Table 13 was prepared.
Next, an organic antireflection film material (trade name ARC-29, manufactured by Brewer Science Co., Ltd.) was applied onto an 8-inch silicon wafer, and baked at 225 ° C. for 60 seconds to form an antireflection film to obtain a substrate.
On the substrate, the positive resist composition obtained above was applied uniformly using a spinner, pre-baked under the conditions shown in Table 14, and dried to form a resist layer. Subsequently, it selectively exposed through the mask using ArF exposure apparatus (wavelength 193 nm) NSR-S302 (made by Nikon, NA (numerical aperture) = 0.60, 2/3 annular illumination).
Then, PEB treatment was performed under the conditions shown in Table 14, followed by paddle development with an aqueous 2.38 mass% tetramethylammonium hydroxide solution at 23 ° C. for 30 seconds, followed by water rinsing with pure water for 30 seconds, followed by shaking off and drying. Then, a 130 nm line and space (1: 1) resist pattern (hereinafter referred to as an L / S pattern) was formed.

  The following evaluation was performed and the results are shown in Table 16.

[LER]
With respect to the L / S pattern of 130 nm of 1: 1, 3σ, which is a scale indicating LER, was obtained. In addition, 3σ is a triple value of the standard deviation (σ) calculated from the result of measuring the width of the resist pattern of the sample at 32 locations with a side length SEM (trade name “S-9220” manufactured by Hitachi, Ltd.). (3σ). This 3σ means that the smaller the value, the smaller the roughness and the uniform width resist pattern was obtained.

When the results of Examples 22 to 27 and Comparative Example 10 were compared, it was found that the exposure margin was excellent by having the structural unit of the present invention.
Moreover, when the result of Example 28 and Comparative Example 11 was compared, it turned out that it is very excellent in LER.

[Synthesis Example 27]
21.0 g of (4-oxo-2-adamantyloxy) methyl methacrylate (corresponding to compound 5 of Synthesis Example 5), 13.6 g of γ-butyrolactone methacrylate (GBLMA), and 9.5 g of 3-hydroxy- 1-adamantyl methacrylate was dissolved in 200 ml of tetrahydrofuran, and 1.64 g of azobisisobutyronitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 1 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as resin 22 and the structural formula is shown below.
The resin 22 had a weight average molecular weight (Mw) of 10,200 and a dispersity (Mw / Mn) of 1.72.
Further, as a result of measuring carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR), the composition ratio of each structural unit shown in the following structural formula was m: n: l = 0.4: 0.4: 0.2 (mol). %)Met.

[Synthesis Example 28]
15.7 g of (4-oxo-2-adamantyloxy) methyl methacrylate (corresponding to compound 5 of synthesis example 5), 17.0 g of γ-butyrolactone methacrylate (GBLMA), and 9.5 g of 3-hydroxy- 1-adamantyl methacrylate was dissolved in 200 ml of tetrahydrofuran, and 1.64 g of azobisisobutyronitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 1 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powder resin. This resin is referred to as resin 23, and the structural formula is shown below.
The resin 23 had a weight average molecular weight (Mw) of 9800 and a dispersity (Mw / Mn) of 1.60.
As a result of measuring a carbon 13 nuclear magnetic resonance spectrum ( ¹³ C-NMR), the composition ratio of each structural unit shown in the above [Chemical Formula 62] was m: n: l = 0.3: 0.5: 0.2. (Mol%).

[Example 29 (reference example)]
A positive resist composition was prepared with the composition shown below.
(A) Resin: Resin 22 100 parts by mass (B) Acid generator: TPS-PFBS 3.5 parts by mass (D) Nitrogen-containing organic compound: Triethanolamine 0.35 parts by mass Organic solvent: PGMEA: EL = 6: 4 750 parts by mass

Next, an organic antireflection film material (trade name ARC-29, manufactured by Brewer Science Co., Ltd.) was applied onto an 8-inch silicon wafer, and baked at 205 ° C. for 60 seconds to form an antireflection film having a thickness of 38 nm.
On the substrate, the positive resist composition obtained above was uniformly applied using a spinner, prebaked at 95 ° C. for 90 seconds, and dried to form a resist layer having a thickness of 225 nm. Subsequently, selective exposure was performed through a binary mask using an ArF exposure apparatus (wavelength: 193 nm) NSR-S302A (manufactured by Nikon, NA (numerical aperture) = 0.60, 2/3 annular illumination).
Then, PEB treatment at 105 ° C. for 90 seconds, paddle development with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 30 seconds, and then water rinsing with pure water for 30 seconds, followed by shaking off and drying. Then, a 140 nm line and space (1: 1) resist pattern was formed. The sensitivity at that time was 23 mJ / cm ² and the exposure margin was 15.4%.

  When Example 29 was compared with Comparative Example 10, it was found that the exposure margin was excellent.

As described above, the high molecular compound and the low molecular compound according to the present invention are useful for forming a fine resist pattern having high rectangularity, and are particularly suitable for forming a fine pattern for KrF, ArF and F ₂ exposure. Yes.

Claims (7)

A polymer compound whose alkali solubility can be changed by the action of an acid,
The following general formula (2)

(In the formula, R ₁ having 20 or less of an aliphatic cyclic group (wherein a carbon, a.) Except 4-oxo-adamantane-1-yl group, n represents an integer of 0 or 1 to 5, R ₂ represents a hydrogen atom or a lower alkyl group having 20 or less carbon atoms.)
A structural unit (a1) derived from a compound represented by:
The following general formula (4)

(In the formula, R ₂ is the same as described above. X ′ represents a divalent or trivalent cyclic group, Y represents a divalent alkylene group having 1 to 6 carbon atoms or an alkyloxy group. P and q Each independently represents an integer of 1 to 5, and s represents an integer of 1 or 2.)
And a structural unit (a6). The polymer compound according to claim 1, wherein, in the general formula ( 2 ), R ₁ is an aliphatic cyclic group having one or more hydrophilic groups.   The polymer compound according to claim 2, wherein the hydrophilic group is at least one selected from the group consisting of a carbonyl group, an ester group, an alcoholic hydroxyl group, an ether, an imino group, and an amino group.   Furthermore, the high molecular compound of any one of Claims 1-3 containing the structural unit (a4) induced | guided | derived from the (meth) acrylic acid ester containing a polar group containing polycyclic group. In a photoresist composition comprising a base resin component (A) whose alkali solubility is changed by the action of an acid and an acid generator (B) that generates an acid upon irradiation with radiation,
The said base resin component (A) is a high molecular compound of any one of Claims 1-4, The photoresist composition characterized by the above-mentioned.   6. The photoresist composition according to claim 5, comprising a nitrogen-containing organic compound (D). Forming a photoresist film on a substrate using the photoresist composition according to claim 5 or 6,
Exposing the photoresist film;
A resist pattern forming method including a step of developing the photoresist film to form a resist pattern.

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