Radiosensitive composition, pattern formation method, and compound

Abstract

Provided are: a radiosensitive composition capable of exhibiting sensitivity, CDU, LWR, pattern rectangularity, etching resistance, exposure latitude (EL), depth of focus (DOF), pre- and post-exposure storage stability, and development defect suppression at sufficient levels during pattern formation; and a pattern formation method. This radiosensitive resin composition comprises a first radiosensitive acid generator that generates an acid represented by formula (1) under exposure to radiation, a second radiosensitive acid generator that generates an acid represented by formula (2) under exposure to radiation (where the second radiosensitive acid generator is different from the first radiosensitive acid generator), a polymer that contains at least one structural unit, and a solvent. (In formula (1), Wa is a monovalent aliphatic group A, a monovalent aliphatic group B containing at least one atom selected from an oxygen, halogen, and sulfur atoms, or a monovalent monocyclic aromatic group. The number of oxygen atoms in Wa is 3 or fewer. L1 is a divalent group represented by formulas (i) to (iv).)　

Description

Radiation-sensitive composition, pattern-forming method, and compound

[0001] The present invention relates to radiation-sensitive compositions, pattern-forming methods, and compounds.

[0002] Photolithography, which uses resist compositions, is employed to form fine circuits in semiconductor devices. A typical procedure involves, for example, generating acid by irradiating a resist composition film with radiation through a mask pattern. This acid then acts as a catalyst, creating a difference in the solubility of the polymer in alkaline or organic developers between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] The above-mentioned photolithography techniques utilize short-wavelength radiation such as KrF excimer lasers and ArF excimer lasers, and further employ liquid immersion lithography, a method in which exposure is performed with a liquid medium filling the space between the lens of the exposure apparatus and the resist film. As next-generation technologies, lithography using even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered.

[0004] Regarding photoacid generators, which are the main components of resist compositions, perfluoroalkyl sulfonic acid, which can impart strong acid, is widely used to improve sensitivity and resolution. On the other hand, in recent years, due to growing environmental awareness, photoacid generators with reduced fluorine atom content are being investigated (see Japanese Patent Publication No. 7015295).

[0005] Patent No. 7015295

[0006] In the development of 3D NAND technology used in non-volatile flash memory, the thickness of the resist film is increasing as the number of stacked cells increases. When the film thickness is thick, it can be difficult to obtain the desired resist performance due to differences in light intensity between the top and bottom layers, and conventional low-fluorination technologies are not adequately able to address this issue.

[0007] Even when applied to a thick resist film while being environmentally friendly, various resist performances equal to or better than conventional ones are required in terms of sensitivity, CDU, LWR, pattern rectangularity, etching resistance, exposure latitude (EL), depth of focus (DOF), storage stability before and after exposure, developability defect suppression, and the like.

[0008] An object of the present invention is to provide a radiation-sensitive composition, a pattern forming method and a compound that can exhibit sufficient levels of sensitivity, CDU, LWR, pattern rectangularity, etching resistance, exposure latitude (EL), depth of focus (DOF), storage stability before and after exposure, and development defect suppression during pattern formation.

[0009] As a result of intensive studies to solve this problem, the present inventors have found that the above object can be achieved by adopting the following constitution, and have completed the present invention.

[0010] In one embodiment, the present invention relates to a radiation-sensitive composition comprising: a first radiation-sensitive acid generator that generates an acid represented by the following formula (1) upon irradiation with radiation; a second radiation-sensitive acid generator that generates an acid represented by the following formula (2) upon irradiation with radiation (excluding the case where the second radiation-sensitive acid generator is the first radiation-sensitive acid generator described above); a polymer containing at least one structural unit; and a solvent. (In formula (1), W ａ is a monovalent aliphatic group A consisting of carbon atoms and hydrogen atoms, a monovalent aliphatic group B consisting of carbon atoms, hydrogen atoms and at least one atom selected from the group consisting of an oxygen atom, a halogen atom and a sulfur atom, or a substituted or unsubstituted monovalent monocyclic aromatic group. Provided that W ａ has 3 or less oxygen atoms. L １ is a divalent group represented by the following formula (i), formula (ii), formula (iii) or formula (iv). (In formulas (i) to (iv), R ２１ and R ２２ are each independently a hydrogen atom or a methyl group. R ２１ and R ２２ when there are plural instances, plural R ２１ and R ２２These are either identical or different from each other. m1 is an integer between 0 and 2. m2 is an integer between 0 and 5. * is W in equation (1) above. ａ This is a combination of . ** is R in equation (1) above. １ This is the bond with the carbon atom to which it is bonded. １ These are monovalent hydrocarbon groups having 1 to 20 carbon atoms, -F, -CF ２ H, -SO ２ -R １１ , or -CN. R １１ (This refers to a monovalent hydrocarbon group having 1 to 20 carbon atoms.) (In formula (2), W ｂ L is a monovalent organic group having 1 to 40 carbon atoms. ２ R is a single bond or a divalent linking group. ｆ１ and R ｆ２ Each of these is independently a fluorine atom, a fluorinated hydrocarbon group, a cyano group, or a hydrogen atom. n is an integer from 0 to 8.

[0011] In another embodiment, the present invention relates to a pattern forming method comprising the steps of: applying the above-mentioned radiation-sensitive composition directly or indirectly to a substrate to form a resist film; exposing the resist film to light; and developing the exposed resist film with a developer.

[0012] In another embodiment, the present invention relates to compounds represented by the following formulas (1-3). (In formula (1-3), W ａ１ This is a monovalent aliphatic group A1 having three carbon atoms consisting of a carbon atom and a hydrogen atom, a monovalent aliphatic group B1 consisting of at least one atom selected from the group consisting of an oxygen atom, a halogen atom, and a sulfur atom, and a carbon atom and a hydrogen atom, or a substituted or unsubstituted monovalent monocyclic aromatic group C1. However, W ａ１ The following requirements (a) and (b) are met: (a) W ａ１ The number of oxygen atoms in is 3 or less; and (b) L １ If is a divalent group represented by the following formula (i), then W ａ１ In the above, the monovalent aliphatic group B1 has a chain-like structure. １This is a divalent group represented by the following formulas (i), (ii), (iii), or (iv). (In formulas (i) to (iv), R ２１ and R ２２ Each of these is independently either a hydrogen atom or a methyl group. ２１ and R ２２ If multiple R ２１ and R ２２ These are either identical or different from each other. m1 is an integer between 0 and 2. m2 is an integer between 0 and 5. * is W in the above equation (1-3). ａ１ This is a combination of . ** is R in equation (1-3) above. １ This is the bond with the carbon atom to which it is bonded. １ These are monovalent hydrocarbon groups having 1 to 20 carbon atoms, -F, -CF ２ H, -SO ２ -R １１ , or -CN. R １１ This is a monovalent hydrocarbon group having 1 to 20 carbon atoms. ＋ (This is an organic cation.)

[0013] In this specification, "organic group" means a group containing at least one carbon atom. However, cyano groups (-CN), carboxyl groups (-COOH), formyl groups (-CHO), carbonyl groups (-CO-:-(C=O)-), etc., which can function as functional or characteristic groups on their own, are excluded. A "condensed ring" means a polycyclic structure in which any two adjacent rings share two consecutive atoms. A "bridged ring" means a polycyclic structure in which any two adjacent rings share three or more consecutive atoms. When three or more atoms are shared between two adjacent rings, the atoms or atomic chains excluding the atoms at both ends of the three or more shared atoms are referred to as "bridges" or "bridged structures." As abbreviations for substituents, "Me" represents a methyl group and "Ph" represents a phenyl group.

[0014] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments. Preferred combinations of embodiments are also preferred.

[0015] <Radiation-sensitive composition> The radiation-sensitive composition according to this embodiment (hereinafter also simply referred to as "the composition") contains a first radiation-sensitive acid generator, a second radiation-sensitive acid generator, a polymer, and a solvent. The above composition may contain other optional components as long as they do not impair the effects of the present invention.

[0016] According to this composition, sensitivity, CDU, LWR, pattern rectangularity, etching resistance, exposure margin (EL), depth of field (DOF), storage stability before and after exposure, and development defect suppression can be achieved at a sufficient level during pattern formation. Although the reason for this is not entirely clear, it is presumed that the following occurs: As mentioned above, when the resist film thickness is high, the light intensity at the top and bottom differs, resulting in variations in the amount of acid generated from the radiation-sensitive acid generator. To suppress variations in the amount of acid generated, a method can be used to increase the diffusion length of the acid generated from the radiation-sensitive acid generator. However, with thick resist films, the long diffusion length is partially emphasized due to the effect of standing waves, resulting in a trade-off where the desired pattern shape cannot be obtained. In this composition, since two predetermined radiation-sensitive acid generators with different acid diffusion lengths and acidities are blended, the difference in light intensity at the top and bottom of the resist film and the effects of standing waves can be efficiently mitigated. Furthermore, since this composition uses a radiation-sensitive acid generator with a low fluorine content, aggregation of radiation-sensitive acid generators can be suppressed, resulting in improved uniform dispersion compared to conventional resist compositions using radiation-sensitive acid generators. In addition, the radiation-sensitive acid generator contains -CO-CH ２ -C (CN) ２ -SO ３ - or -CO-CH ２ -CH(CN)-C(CN) ２ -SO ３ - When a structure like this is present, the hydrogen atoms of the methylene group in the structure become active protons due to the electron-withdrawing properties of the carbonyl and dicyano structures, causing the adjacent cyano group to be eliminated and generating hydrogen cyanide while simultaneously forming an acrylic structure (-CO-CH=C(CN)-SO ３ -(and so on) can occur. Since this side reaction is accelerated in the presence of acid, it not only reduces storage stability when the material is left to dry after exposure, but also leads to contamination of the exposure machine itself. The first radiation-sensitive acid generator in this composition employs a structure that does not generate such active protons, thus ensuring good storage stability after exposure. Through the synergistic effects of these factors, the composition can exhibit the desired resist properties.

[0017] <Primary Radiation Acid Generator> The primary radiation acid generator is a compound that generates an acid represented by the above formula (1) upon irradiation with radiation. If the above polymer contains structural units having acid-dissociating groups, the acid generated from the primary radiation acid generator can dissociate the above acid-dissociating groups.

[0018] In the above formula (1), W ａ This is a monovalent aliphatic group A, a monovalent aliphatic group B, or a substituted or unsubstituted monovalent monocyclic aromatic group.

[0019] W ａ The above-mentioned monovalent aliphatic group A is a monovalent aliphatic group consisting of a carbon atom and a hydrogen atom. Examples of the above-mentioned aliphatic group A include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, or groups that combine these.

[0020] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, n-heptyl, n-octyl, and n-nonyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0021] The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms may be either monocyclic or polycyclic. Examples of monocyclic alicyclic hydrocarbon groups include cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and cycloalkenyl groups such as cyclopropenyl, cyclopentenyl, and cyclohexenyl. Examples of polycyclic alicyclic hydrocarbon groups include cross-linked ring saturated hydrocarbon groups such as norbornyl, adamantyl, and tricyclodecyl; and cross-linked ring unsaturated hydrocarbon groups such as norbornenyl and tricyclodecenyl.

[0022] The monovalent aliphatic group A is preferably a monovalent linear hydrocarbon group having 2 to 12 carbon atoms, a monovalent alicyclic hydrocarbon group having 5 to 12 carbon atoms, or a combination thereof; more preferably a monovalent linear or branched saturated hydrocarbon group having 2 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 5 to 10 carbon atoms, or a combination thereof; and even more preferably a monovalent linear or branched saturated hydrocarbon group having 3 to 8 carbon atoms, a monovalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, or a combination thereof.

[0023] W ａ The above monovalent aliphatic group B is a monovalent aliphatic group consisting of at least one atom selected from the group consisting of oxygen, halogen, and sulfur atoms, a carbon atom, and a hydrogen atom. As the above monovalent aliphatic group B, for example, -O-, -CO-, -S-, -SO- is present between the carbon-carbon atoms (between adjacent or non-adjacent two carbon atoms) of the above monovalent aliphatic group A. ２ -Or a group containing a combination of two or more of these (B1), a group (B2) in which some or all of the hydrogen atoms of the monovalent aliphatic group A or the above group (B1) are substituted with a halogen atom, a carboxyl group, a hydroxyl group, a formyl group, or a sulfanyl group. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms. Other heteroatoms include nitrogen atoms, but W ａ If nitrogen atoms are present, their acid-scavenging ability may locally trap the diffusion of acid, potentially preventing the acquisition of the desired cross-sectional shape.

[0024] The monovalent aliphatic group B is preferably a chain group having one or more oxyalkylene groups (-R-O-; R is an alkylene group), a cyclic group having a sultone structure, a cyclic ketone group, or a substituted cycloalkyl group, and more preferably a group having an oxyethylene methyl ether structure, a group having an oxypropylene methyl ether structure, a norbornane sultone-yl group, an oxoadamantan-yl group, or a substituted cyclohexyl group. The substituents on the substituted cyclohexyl group are preferably a carboxyl group or a hydroxyl group.

[0025] In the above formula (1), W ａ In the above-mentioned monovalent aliphatic group A or aliphatic group B, it is preferable that the chain-like structure is present. This allows the diffusion length of the generated acid to be appropriately extended, and when combined with the second radioactive acid generator described later, the optimal diffusion length can be controlled at the top and bottom of the resist film, allowing even thick resist films to exhibit the desired resist properties.

[0026] W ａ Examples of the above monovalent monocyclic aromatic group include phenyl group, furyl group, thienyl group, etc. If the above aromatic group has substituents, examples of substituents include the above aliphatic group A, the above aliphatic group B, halogen atom, carboxyl group, hydroxyl group, formyl group, sulfanyl group, etc.

[0027] W ａ The number of oxygen atoms in is three or less. This allows for improvements in pattern roughness and suppression of development defects. Primary radioactive acid generators with reduced fluorine tend to have higher polarity compared to conventional products. In particular, W located at the terminal end of the molecular structure of the primary radioactive acid generator. ａ When the oxygen atom content is high, intramolecular polarization increases, and the polarity tends to become too high. As a result, it can induce swelling of the pattern, leading to roughness. Furthermore, due to the highly polarized structure, the elution of the primary radiation-sensitive acid generator into the immersion water during immersion exposure is accelerated, reducing the amount of radiation-sensitive acid generator in the resist film, which may cause development defects or insufficient pattern formation. In the primary radiation-sensitive acid generator of this composition, W ａBy limiting the number of oxygen atoms in the resist to three or less, the occurrence of these phenomena can be suppressed, and good resist performance can be achieved.

[0028] In the above formula (1), W ａ Regardless of which base it is, W ａ The number of carbon atoms in W is preferably 3 or more. ａ By giving the molecular structure a certain degree of hydrophobicity by setting the number of carbon atoms to three or more, aggregation can be suppressed to a higher level and dispersibility can be improved. This allows for further improvement of the resist properties described above.

[0029] In the above formula (1), W ａ It is preferable that the above monovalent aliphatic group A or aliphatic group B is used, and more preferably that the above monovalent aliphatic group A is used. This makes it possible to increase the light transmittance even in thick resist films, improve the light intensity at the bottom of the resist film, and more efficiently form the desired pattern. In particular, considering the viewpoints of diffusion length control and aggregation suppression, W ａ It is particularly preferable that the group is a monovalent linear or branched saturated hydrocarbon group having 3 carbon atoms (i.e., an n-propyl group or an isopropyl group).

[0030] In the above formulas (i) to (iv), R ２１ and R ２２ Preferably, the atom is a hydrogen atom. This balances the polarity of the entire molecule while improving molecular mobility by expanding the range of motion of the molecular structure, and allows for appropriate control of the solubility of the primary radiation-sensitive acid generator and the acid diffusion length of the generated acid.

[0031] m1 is preferably 0 or 1.

[0032] m2 is preferably an integer between 0 and 4, more preferably an integer between 0 and 3, and even more preferably an integer between 1 and 3.

[0033] In the above formula (1), L １ From the viewpoint of stability and acid diffusion length, it is preferable that the group is a divalent group represented by formula (i) or formula (ii) above.

[0034] In the above formula (1), R１ and R １１ As a monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above formula (1), W ａ Examples include the monovalent aliphatic group A, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof.

[0035] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.

[0036] R １ and R １１ The monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by the formula are preferably linear hydrocarbon groups having 1 to 10 carbon atoms, more preferably alkyl groups having 1 to 5 carbon atoms, and even more preferably methyl and ethyl groups.

[0037] In the above formula (1), R １ -CN, -SO ２ -R １１ Alternatively, it is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably -CN. １１ R is preferably an alkyl group having 1 to 5 carbon atoms. １ or R １１ As the alkyl group having 1 to 5 carbon atoms, methyl and ethyl groups are preferred. １ These preferred substituents increase the acidity of the generated acid, allowing the reaction with the acid-dissociable group to proceed efficiently, thereby increasing the dissolution contrast between the exposed and unexposed areas, and enabling the resist to exhibit excellent performance characteristics.

[0038] The primary radiation-sensitive acid generator that produces the acid represented by formula (1) above upon irradiation with radiation is preferably a compound represented by the following formula (1-1). (In formula (1-1), W ａ , L １ and R １ This is equivalent to equation (1) above. Z １ ＋ (This is a radiation-sensitive onium cation.)

[0039] Specific examples of the anion of the compound represented by the above formula (1-1) include structures represented by the following formulas, and the like. The acid represented by the above formula (1) corresponds to a structure obtained by adding a proton to a sulfonate anion (-SO ３ - ３ ３ H) to convert it into sulfonic acid (-SO

[0040]

[0041]

[0042]

[0043] Z １ ＋ Examples of the radiation-sensitive onium cation represented by include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, and the like. Among these, sulfonium cations or iodonium cations are preferable, and sulfonium cations are more preferable.

[0044] The radiation-sensitive onium cation may have at least one selected from the group consisting of an iodine group and a fluoro group. The above organic cation preferably contains an iodine group-containing aromatic ring structure as the form of the iodine group. An iodine group-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms of the aromatic ring are replaced by iodine groups. In the organic cation, it is preferable that the fluoro group is contained in the form of a fluoro group-containing aromatic ring structure. A fluoro group-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms of the aromatic ring are replaced by fluoro groups. Examples of aromatic rings in iodine group-containing aromatic ring structures and fluoro group-containing aromatic ring structures include C6-C20 aromatic hydrocarbon rings such as benzene rings, naphthalene rings, anthracene rings, tetracene rings, phenalene rings, phenanthrene rings, pyrene rings, fluorene rings, perylene rings, and biphenyl rings; C3-C20 aromatic heterocycles such as triazole rings, imidazole rings, furan rings, pyrrole rings, thiophene rings, phosphole rings, pyrazole rings, oxazole rings, isoxazole rings, thiazole rings, pyridine rings, pyrimidine rings, pyridazine rings, triazine rings, indole rings, benzimidazole rings, benzofuran rings, quinoline rings, and carbazole rings; or combinations thereof. The introduction of an iodine group or a fluoro group can increase radiation absorption efficiency, thereby improving sensitivity.

[0045] The sulfonium cation or iodonium cation is preferably represented by the following formulas (X-1) to (X-6).

[0046]

[0047] In the above equation (X-1), R ａ１ , R ａ２ and R ａ３ Each of these independently comprises a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, hydroxyl group, halogen atom, or -OSO ２ -R Ｐ , -SO２ -R Ｑ , -S-R Ｔ , -O-, -CO- or a combination thereof, or represents a ring structure formed by combining two or more of these groups with each other. The ring structure may contain a heteroatom such as O or S between carbon-carbon bonds forming the skeleton. R Ｐ , R Ｑ and R Ｔ are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2 and k3 are each independently an integer of 0 to 5. R ａ１ to R ａ３ and R Ｐ , R Ｑ and R Ｔ each are present in plurality, a plurality of R ａ１ to R ａ３ and R Ｐ , R Ｑ and R Ｔ may each be the same or different.

[0048] In the above formula (X-2), R ｂ１ is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, an alkoxyalkyloxy group, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. n ｋ is 0 or 1. When n ｋ is 0, k4 is an integer of 0 to 4; when n ｋ is 1, k4 is an integer of 0 to 7. When a plurality of R ｂ１ are present, a plurality of R ｂ１ may be the same or different, and a plurality of R ｂ１ may be combined with each other to form a ring structure. R ｂ２ is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. LＣ k5 is a single bond or a divalent linking group. k5 is an integer from 0 to 4. ｂ２ If there are multiple R ｂ２ They may be the same or different, and there may be multiple R's. ｂ２ may represent a ring structure formed by combining with each other. q is an integer from 0 to 3. In the formula, S ＋ The ring structure containing may include heteroatoms such as O and S between the carbon-carbon bonds that form the skeleton.

[0049] In the above equation (X-3), R ｃ１ , R ｃ２ and R ｃ３ One or two selected from the group consisting of are substituted or unsubstituted phenyl groups, and the remainder are substituted or unsubstituted linear or branched alkyl groups having 1 to 12 carbon atoms. Among these, R ｃ１ , R ｃ２ and R ｃ３ Preferably, one of them is a linear or branched alkyl group having 1 to 5 carbon atoms.

[0050] In the above equation (X-4), R ｇ１ This refers to a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. ｋ２ n is either 0 or 1. ｋ２ When is 0, k10 is an integer from 0 to 4, and n ｋ２ When is 1, k10 is an integer from 0 to 7. ｇ１ If there are multiple R ｇ１ They may be the same or different, and there may be multiple R's. ｇ１ R may represent a ring structure formed by combining with other elements. ｇ２ and R ｇ３Each of these independently represents a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, hydroxyl group, halogen atom having 6 to 12 carbon atoms, or a ring structure formed by combining these groups. k11 and k12 are each independently integers from 0 to 4. R ｇ２ and R ｇ３ If each of them is multiple, then multiple R ｇ２ and R ｇ３ These may be the same or different.

[0051] In the above equation (X-5), R ｄ１ and R ｄ２ Each of these independently represents a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyl group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by combining two or more of these groups. k6 and k7 are each independently integers from 0 to 5. R ｄ１ and R ｄ２ If each of them is multiple, then multiple R ｄ１ and R ｄ２ These may be the same or different.

[0052] In the above formula (X-6), R ｅ１ and R ｅ２ Each of these is independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are independently integers from 0 to 4.

[0053] Specific examples of the above-mentioned radiation-sensitive onium cation include, but are not limited to, structures represented by the following formula.

[0054]

[0055]

[0056]

[0057]

[0058] A specific example of a case where the first radiation-sensitive acid generator is a compound represented by formula (1-1) above can be obtained by appropriately combining the above anion and the above radiation-sensitive onium cation (the anion and the radiation-sensitive onium cation are not limited to the structures specifically shown). Specific examples, though not particularly limited, include structures represented by the following formula.

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065] The primary radiation-sensitive acid generator that produces the acid represented by formula (1) above upon irradiation with radiation may be a compound represented by the following formula (1-2). (In formula (1-2), W ａ , L １ and R １ This is equivalent to formula (1) above. W is a substituted or unsubstituted nitrogen-containing heterocycle that is composed of CO-N-CO in the formula.

[0066] In formula (1-2) above, examples of nitrogen-containing heterocycles in W include succinimide rings, maleimide rings, norbornenedicarboxylate imide rings, phthalimide rings, naphthalenedicarboxylate imide rings, and the like.

[0067] When the nitrogen-containing heterocycle of W has substituents, examples of substituents include halogen atoms; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, cycloalkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, or groups in which the hydrogen atoms of these groups are substituted with halogen atoms; or groups that combine these groups; oxo groups (=O), etc.

[0068] Specific examples of cases where the primary radiation-sensitive acid generator is a compound represented by the above formula (1-2) include, for example, the structure represented by the following formula.

[0069]

[0070]

[0071] The primary radiation-sensitive acid generator may be used alone or in combination of two or more types. The lower limit of the content of the primary radiation-sensitive acid generator (total in the case of multiple types) is preferably 0.1 parts by mass, more preferably 1 part by mass, and still more preferably 3 parts by mass, per 100 parts by mass of the base polymer described later. The upper limit of the above content is preferably 60 parts by mass, more preferably 55 parts by mass, and still more preferably 50 parts by mass. This allows for the excellent resist performance described above to be achieved.

[0072] <Synthesis Method for Primary Radiation-Inducing Acid Generator> It is clear that the primary radiation-induced acid generator can be synthesized based on the description in the examples and common technical knowledge. In the above formula (1), L １ This is expressed by the above equation (i), and R ２１ and R ２２ is a hydrogen atom, R １ As a representative example of the embodiment where is -CN, it can be synthesized using the following scheme.

[0073] (In the scheme, W ａ and Z １ ＋ This is equivalent to equation (1) above. Each X is an independent halogen atom. - (This is a halide ion.)

[0074] The first radioactive acid generator can be synthesized by reacting a halogenated compound with malononitrile to form a dicyano compound, introducing a sulfonic acid group by reacting with a halogenated sulfonic acid, and finally undergoing a salt exchange with the target radioactive onium cation halogen. Other structures can also be synthesized by appropriately selecting the starting materials and reaction substrates. Furthermore, for the introduction of the sulfonic acid group, it is also effective to use other common sulfonic acid introducers or to use a base in combination, and it can also be derived by converting the active proton between the dicyano compounds to a halogen before converting it to a sulfonic acid group.

[0075] <Secondary Radiation Acid Generator> The secondary radiation acid generator is a compound that generates an acid represented by the above formula (2) upon irradiation with radiation. If the above polymer contains structural units having acid-dissociating groups, the acid generated from the secondary radiation acid generator can dissociate the above acid-dissociating groups.

[0076] In the above formula (2), W ｂ Examples of monovalent organic groups having 1 to 40 carbon atoms represented by include monovalent hydrocarbon groups having 1 to 40 carbon atoms, groups having a divalent heteroatom-containing linking group between carbon atoms of the hydrocarbon group or at the terminal end of the hydrocarbon group (hereinafter also referred to as "group (α)"), groups in which some or all of the hydrogen atoms of the hydrocarbon group or group (α) are replaced with monovalent heteroatom-containing substituents, or groups that combine these.

[0077] As a monovalent hydrocarbon group having 1 to 40 carbon atoms, R in formula (1) above is an example. １ A monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by [the formula shown], can be suitably adopted, with the carbon number extended up to 40.

[0078] Examples of heteroatoms that constitute a divalent heteroatom-containing linking group or a monovalent heteroatom-containing substituent include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. The halogen atoms are as described above.

[0079] Examples of divalent heteroatom-containing linking groups include -CO-, -CS-, -NR'-, -O-, -S-, -SO-, and -SO２ - and combinations thereof are examples. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0080] Examples of monovalent heteroatom-containing substituents include hydroxyl groups, sulfanyl groups, cyano groups, nitro groups, amino groups, and halogen atoms.

[0081] W ｂ It is preferable that the ring structure includes a ring structure. The ring structure may be monocyclic, polycyclic, or a combination thereof. Furthermore, the ring structure may be alicyclic, aromatic, or a combination thereof. In the case of a combination, the ring structure may be linked by a chain structure, or two or more ring structures may form a fused ring structure. It is preferable that these structures are included as the smallest basic skeleton of the ring structure. The number of ring structures may be one or two or more. The above-mentioned divalent heteroatom-containing linking groups may be present between carbon atoms or at the ends of carbon chains forming the skeleton of the ring or chain structure, and hydrogen atoms on carbon atoms of the ring or chain structure may be substituted with other substituents.

[0082] The above alicyclic structure is W in formula (1) above. ａ Structures corresponding to monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, as shown in [reference], can be suitably adopted.

[0083] The above aromatic ring structure is Z in formula (1-1) above. １ ＋ The aromatic ring shown can be suitably adopted.

[0084] The above chain-like structure is W in formula (1) above. ａ Structures corresponding to monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, as shown in [reference], can be suitably adopted.

[0085] Aliphatic heterocyclic structures can also be used as the alicyclic structures described above. Examples of such aliphatic heterocyclic structures include oxygen-containing aliphatic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, and dioxane; nitrogen-containing aliphatic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; sulfur-containing aliphatic heterocyclic structures such as thiethane, thiolane, and thian; and aliphatic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0086] Aliphatic heterocyclic structures include lactone structures, cyclic carbonate structures, sultone structures, cyclic acetal structures, cyclic imide structures, lactam structures, or combinations thereof.

[0087] W ｂ It is preferable that it contains the above-mentioned alicyclic structure.

[0088] As substituents that substitute hydrogen atoms on carbon atoms in the above-mentioned ring or chain structure, substituents that W in formula (1-2) may have can be suitably adopted.

[0089] In the above formula (2), L ２ Examples of divalent linking groups represented by include divalent hydrocarbon groups, divalent heteroatom-containing linking groups, groups in which the divalent heteroatom-containing linking group is incorporated between the carbon-carbon bonds of the divalent hydrocarbon group or at the terminal end of the divalent hydrocarbon group, or groups that combine these. Some or all of the hydrogen atoms in these groups may be substituted with substituents.

[0090] Examples of the divalent hydrocarbon groups mentioned above include alkanediyl groups, cycloalkanediyl groups, alkenediyl groups, arenediyl groups, or combinations thereof.

[0091] The alkanediyl group described above is preferably an alkanediyl group having 1 to 8 carbon atoms, such as a methanediyl group, an ethanediyl group, a 1,3-propanediyl group, a 2,2-propanediyl group, or an isopentane-1,2-diyl group.

[0092] Examples of the above-mentioned cycloalkanediyl groups include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups; and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups. A cycloalkanediyl group having 5 to 12 carbon atoms is preferred.

[0093] As the above-mentioned alkenediyl group, for example, alkenediyl groups having 2 to 6 carbon atoms, such as ethendiyl groups, propenediyl groups, and butendiyl groups, are preferred.

[0094] As the above-mentioned arenediyl group, for example, an arenediyl group with an prime number of 6 to 15, such as a benzenediyl group or a naphthalenediyl group, is preferred.

[0095] The above-mentioned divalent heteroatom-containing linking group is as described above.

[0096] L ２ If the substituent has substituents, the substituents that W in formula (1-2) may have can be preferably adopted.

[0097] L ２ Preferably, the group is an alkanediyl group having 1 to 6 carbon atoms, a divalent heteroatom-containing linking group or a combination thereof, or a single bond; more preferably, an alkanediyl group having 1 to 4 carbon atoms, -O-, -CO-, or a combination thereof, or a single bond.

[0098] In the above formula (2), R ｆ１ and R ｆ２ Examples of monovalent fluorinated hydrocarbon groups represented by include monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms and monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0099] Examples of the above-mentioned monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms include fluorinated alkyl groups such as trifluoromethyl group, difluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, heptafluoron-propyl group, heptafluoroisopropyl group, nonafluoron-butyl group, nonafluoroisobutyl group, nonafluorot-butyl group, 2,2,3,3,4,4,5,5-octafluoron-pentyl group, tridecafluoron-hexyl group, and 5,5,5-trifluoro-1,1-diethylpentyl group; fluorinated alkenyl groups such as trifluoroethenyl group and pentafluoropropenyl group; and fluorinated alkynyl groups such as fluoroethynyl group and trifluoropropynyl group.

[0100] Examples of the above-mentioned monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms include fluorinated cycloalkyl groups such as fluorocyclopentyl group, difluorocyclopentyl group, nonafluorocyclopentyl group, fluorocyclohexyl group, difluorocyclohexyl group, undecafluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, and fluorotricyclodecyl group; and fluorinated cycloalkenyl groups such as fluorocyclopentenyl group and nonafluorocyclohexenyl group.

[0101] The above monovalent fluorinated hydrocarbon group is preferably a monovalent fluorinated linear hydrocarbon group having 1 to 8 carbon atoms, and more preferably a monovalent fluorinated linear hydrocarbon group having 1 to 5 carbon atoms.

[0102] n is preferably an integer between 0 and 6, more preferably an integer between 0 and 4, and even more preferably an integer between 0 and 2.

[0103] The secondary radiation-sensitive acid generator that produces the acid represented by formula (2) above upon irradiation with radiation is preferably a compound represented by the following formula (2-1) or formula (2-2).

[0104] (In equations (2-1) and (2-2), W ｂ , L ２ and R ｆ１ and R ｆ２ This is equivalent to equation (2) above. Z １ ＋ This is equivalent to equation (1-1) above. W is equivalent to equation (1-2) above.

[0105] Specific examples of the compound represented by formula (2-1) above, and specific examples of the compound represented by formula (2-2) above, include, for example, the structure represented by the following formula.

[0106]

[0107]

[0108] The secondary radioactive acid generator may be used alone or in combination of two or more types. The lower limit of the content of the secondary radioactive acid generator (total in the case of multiple types) is preferably 0.1 parts by mass, more preferably 1 part by mass, and even more preferably 1.5 parts by mass, per 100 parts by mass of the base polymer described later. The upper limit of the above content is preferably 60 parts by mass, more preferably 55 parts by mass, and even more preferably 50 parts by mass. This allows for the excellent resist performance described above to be achieved.

[0109] <Polymers> A polymer (i.e., a base polymer) is an aggregate of polymer chains containing at least one structural unit. The main structural units that polymers may contain include structural units containing acid-dissociable groups (hereinafter also referred to as "structural unit (I)"), structural units containing at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures (hereinafter also referred to as "structural unit (II)"), structural units containing polar groups (hereinafter also referred to as "structural unit (III)") (excluding those corresponding to structural units (I) and (II)), and structural units having phenolic hydroxyl groups (hereinafter also referred to as "structural unit (IV)").

[0110] The polymer described above preferably contains three or more structural units having different structures from each other, and each of these three or more structural units preferably independently has an acid-dissociable group, a lactone structure, a cyclic carbonate structure, or a sultone structure. By having three or more of the above specific structural units, the polymer can exhibit a high level of balance between etching resistance required for thick resist films and solubility for suppressing development defects.

[0111] The structural units incorporated into the polymer can be appropriately selected according to various conditions in the pattern formation process to which the composition is applied, particularly the exposure conditions. The following describes each structural unit.

[0112] [Structural Unit (I)] Structural unit (I) is a structural unit containing an acid-dissociable group. An "acid-dissociable group" is a hydrogen atom-substituting group such as a carboxyl group, phenolic hydroxyl group, alcoholic hydroxyl group, or sulfo group that dissociates upon the action of an acid. The radiation-sensitive composition exhibits excellent pattern-forming properties because the polymer contains structural unit (I).

[0113] Structural unit (I) is not particularly limited as long as it has an acid-dissociable group. Examples include structural units having a tertiary alkyl ester moiety, a structure in which an aromatic group and an aliphatic hydrocarbon group are bonded to a secondary carbon atom in a secondary carboxylic acid ester structure, a structural unit having a structure in which a hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. However, from the viewpoint of improving the pattern-forming properties of the radiation-sensitive composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0114]

[0115] In the above formula (3), R １７ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １８ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. １９ and R ２０Each of these independently represents a substituted or unsubstituted monovalent linear hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups with the carbon atoms to which they are bonded. １１ teeth, ＊ -COO-, ＊ -L １１ａ COO- or ＊ -COOL １１ａ Represents COO-. １１ａ * is a substituted or unsubstituted alkanediyl group or arenediyl group. １７ This is the bonding site with the carbon atom to which it is bonded.

[0116] Furthermore, a "substituted hydrocarbon group" refers to a hydrocarbon group in which one or more hydrogen atoms are replaced by a monovalent heteroatom-containing substituent. The monovalent heteroatom-containing substituents are as described above.

[0117] The above R １７ From the viewpoint of copolymerization of the monomer that gives the structural unit (I-1), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0118] L １１ａ The alkanediyl group and arenediyl group represented by the above formula (2) are L ２ The alkanediyl group and arenediyl group shown in the above can be suitably used.

[0119] L １１ａ As substituents that the arenediyl group represented by can have, the substituents that W in the above formula (1-2) can have can be suitably adopted.

[0120] The above R １８ Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by [the formula], include monovalent linear hydrocarbon groups having 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

[0121] The above R １８ ~R ２０Examples of monovalent linear hydrocarbon groups having 1 to 10 carbon atoms represented by include monovalent linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, or monovalent linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms.

[0122] The above R １８ ~R ２０ As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (1), R １ The monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms shown in the above can be suitably used.

[0123] The above R １８ As a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the above formula (1), R １ Monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, as shown in the above, can be suitably used.

[0124] The above R １８ Preferably, the hydrocarbon group is a straight-chain or branched-chain saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0125] The above R １９ and R ２０ The divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining these atoms with the carbon atoms to which they are bonded, can preferably be groups obtained by removing one hydrogen atom from the above-mentioned monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0126] Among these, R １８ R is an alkyl group, alkenyl group, or phenyl group having 1 to 4 carbon atoms. １９ and R ２０ It is preferable that the alicyclic structure formed by combining these atoms with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure or an aliphatic heterocyclic structure. As the aliphatic heterocyclic structure, a cyclic ether structure containing an ether bond between the carbon atoms of the cycloalkane is preferred.

[0127] The above R １８ ~R ２０ The substituents that can be present are L １１ａ The substituents that the arenediyl group represented by can have can be suitably adopted.

[0128] Examples of structural units (I-1) include those represented by the following formulas (3-1) to (3-15) (hereinafter also referred to as "structural units (I-1-1) to (I-1-15)").

[0129]

[0130]

[0131] In the above equations (3-1) to (3-15), R １７ ~R ２０ This is equivalent to equation (3) above. R Ｌ１１ R is a halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group, fluorinated alkyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, or alkoxy group. i and j are each independently integers from 1 to 4. k and l are 0 or 1. 3a are each independently integers from 0 to 3. If 3a is 2 or more, multiple R Ｌ１１ They are either identical or different from each other. a4 is an integer between 1 and 3.

[0132] i and j are preferably 1 or 2. １８ Preferred groups include methyl group, ethyl group, isopropyl group, t-butyl group, cyclopentyl group, ethenyl group, phenyl group, iodophenyl group, methoxyphenyl group, and (di)iodomethoxyphenyl group. １９ and R ２０ Preferably, the group is a methyl group, an ethyl group, or an isopropyl group. Ｌ１１ By employing an iodine atom, an iodine group can be suitably introduced into the structural unit (I).

[0133] Furthermore, the polymer may contain structural units (I) represented by the following formulas (1f) to (2f).

[0134]

[0135] In the above equations (1f) to (2f), R αｆ Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. βｆEach of these is independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. h1 is an integer from 1 to 4.

[0136] The above R βｆ Preferably, the element is a hydrogen atom, a methyl group, or an ethyl group. H1 is preferably 1 or 2.

[0137] The lower limit of the content of structural unit (I) (total content if multiple types are included) is preferably 10 mol%, more preferably 20 mol%, and even more preferably 25 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 65 mol%. By setting the content of structural unit (I) within the above range, the pattern-forming properties of the radiation-sensitive composition can be further improved.

[0138] [Structural Unit (II)] Structural Unit (II) is a structural unit comprising at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. By further comprising Structural Unit (II), the solubility of the base polymer in the developer can be adjusted, and as a result, the radiation-sensitive composition can improve lithography performance such as resolution. Furthermore, the adhesion between the resist pattern formed from the base polymer and the substrate can be improved.

[0139] Examples of structural units (II) include structural units represented by the following formulas (T-1) to (T-11).

[0140]

[0141] In the above formula, R Ｌ１ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｌ２ ~R Ｌ５ These are, independently, a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxyl group, a hydroxymethyl group, and a dimethylamino group. Ｌ４ and R Ｌ５These may be divalent alicyclic groups having 3 to 8 carbon atoms, which can be combined with each other and bonded together with the carbon atoms. Ｅ is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0142] The above R Ｌ４ and R Ｌ５ When these are combined with each other, the divalent alicyclic group having 3 to 8 carbon atoms, formed together with the carbon atoms to which they are bonded, is R in formula (3) above. １９ and R ２０ Examples include divalent alicyclic groups with 3 to 20 carbon atoms, where these groups are combined with each other and formed together with the carbon atoms to which they are bonded, specifically groups with 3 to 8 carbon atoms. One or more hydrogen atoms on these alicyclic groups may be substituted with hydroxyl groups.

[0143] The above L Ｅ Examples of divalent linking groups represented by include divalent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of the groups -CO-, -O-, -NH-, and -S-.

[0144] Among these, structural units (II) are preferably those containing a lactone structure, more preferably those containing a γ-butyrolactone structure or a norbornane lactone structure, and even more preferably those derived from γ-butyrolactone-yl-(meth)acrylate or norbornane lactone-yl(meth)acrylate.

[0145] When the base polymer has structural unit (II), the lower limit of the content of structural unit (II) (total content if multiple types are included) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 85 mol%, more preferably 80 mol%, and even more preferably 75 mol%. By setting the content of structural unit (II) within the above range, the radiation-sensitive composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0146] [Structural Unit (III)] The base polymer optionally has structural unit (III) containing a polar group (however, it is different from structural units (I) and (II)). By further having structural unit (III), the solubility in the developer can be adjusted, and as a result, the lithographic performance such as resolution of the radiation-sensitive composition can be improved. Examples of the above polar group include hydroxyl group, carboxyl group, cyano group, nitro group, sulfonamide group, etc. Among these, hydroxyl group and carboxyl group are preferred, and hydroxyl group is more preferred.

[0147] Examples of structural units (III) include structural units represented by the following formula.

[0148]

[0149]

[0150] In the above formula, R Ｋ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0151] When the base polymer has structural unit (III) having the polar group described above, the lower limit of the content of structural unit (III) (total content if multiple types are included) is preferably 1 mol%, more preferably 2 mol%, and even more preferably 3 mol%, relative to the total structural units constituting the base polymer. The upper limit of the content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%. By setting the content of structural unit (III) within the above range, the lithographic performance, such as resolution, of the radiation-sensitive composition can be further improved.

[0152] [Structural Unit (IV)] The base polymer optionally contains structural units having phenolic hydroxyl groups (hereinafter also referred to as "structural unit (IV)"). Structural unit (IV) contributes to improved etching resistance and improved difference in developer solubility between exposed and unexposed areas (dissolution contrast). It can be suitably applied to pattern formation using exposure with radiation of wavelengths of 50 nm or less, such as electron beams and EUV, in addition to KrF excimer lasers.

[0153] The structural unit having a phenolic hydroxyl group is preferably represented by the following formula (4).

[0154] (In the above formula (4), R β L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＣＡ This is a single bond, -COO- ＊ Or -O-. * indicates a bond on the aromatic ring side. R １０２ R is a halogen atom, cyano group, nitro group, alkyl group, alkoxy group, alkoxycarbonyl group, acyl group, or acyloxy group. １０２ If multiple R １０２ They are either identical or different from each other. ３ m is an integer between 0 and 2. ３ m is an integer from 1 to 8. ４ m is an integer between 0 and 8, where 1 ≤ m ３ +m ４ ≤ 2n ３ (Saves +5.)

[0155] The above R β From the viewpoint of copolymerization of the monomer that gives the structural unit (IV), it is preferable that it be a hydrogen atom or a methyl group.

[0156] L ＣＡ For example, a single bond or -COO- ＊ It is preferable.

[0157] R １０２ Fluorine atoms and iodine atoms are preferred as halogen atoms in this mixture.

[0158] The above n ３ 0 or 1 is more preferable, and 0 is even more preferable.

[0159] The above m ３ Preferably, the integer is between 1 and 3, and more preferably 1 or 2.

[0160] The above m ４ Preferably, the integer is between 0 and 3, and more preferably between 0 and 2.

[0161] When obtaining structural units (IV), it is preferable to polymerize the monomer while protecting the phenolic hydroxyl group of the corresponding monomer with a protecting group such as an alkali-dissociable group (e.g., an acyl group), and then deprotect it by hydrolysis to obtain structural units (IV). Polymerization of the monomer may also be carried out without protecting the phenolic hydroxyl group.

[0162] For polymers used for exposure with KrF excimer lasers or radiation with wavelengths of 50 nm or less, the lower limit of the content of structural units (IV) (total content if multiple types are included) is preferably 15 mol%, and more preferably 25 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content may be 100 mol%, 70 mol%, or 60 mol%.

[0163] [Other structural units] The base polymer may also contain structural units other than those listed above, such as structural units having an alicyclic structure represented by the following formula (6) (hereinafter also referred to as "structural unit (VII)"). (In the above formula (6), R １α R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２α (It is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0164] In the above formula (6), R ２α As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (1), W ａ The monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms shown in the above can be suitably used.

[0165] When the base polymer contains structural unit (VII), the lower limit of the content of structural unit (VII) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.

[0166] (Method for synthesizing base polymers) Base polymers can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0167] Examples of the radical polymerization initiators mentioned above include azo-based radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred. These radical initiators can be used individually or in combination of two or more.

[0168] Solvents used in the above polymerization include, for example, alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, methyl propionate, and propylene glycol monomethyl ether acetate; and ketones such as acetone, methyl ethyl ketone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and cyclohexanone. Examples include linear ethers such as dimethoxyethanes and diethoxyethanes; cyclic ethers such as tetrahydrofurans and 1,4-dioxanes; polyhydric alcohol partial ethers such as 1-methoxy-2-propanol (propylene glycol monomethyl ether); alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol; and lactones such as γ-butyrolactone. The solvents used in these polymerizations may be used alone or in combination of two or more.

[0169] The reaction temperature in the polymerization described above is usually 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is usually 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0170] The molecular weight of the base polymer is not particularly limited, but the lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 2,000, more preferably 3,000, and even more preferably 4,000. The upper limit of Mw is preferably 30,000, more preferably 20,000, and even more preferably 18,000. By keeping the Mw of the base polymer within the above range, good heat resistance and developability can be obtained in the resulting resist film.

[0171] The ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) of the base polymer (Mw / Mn) determined by GPC is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

[0172] In this specification, the Mw and Mn values ​​of polymers are measured using gel permeation chromatography (GPC) under the following conditions.

[0173] GPC columns: 2 x G2000HXL, 1 x G3000HXL, 1 x G4000HXL (all manufactured by Tosoh) Column temperature: 40°C Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0174] The base polymer content is preferably 40% by mass or more, and more preferably 50% by mass or more, relative to the total solid content of the radiation-sensitive composition.

[0175] (Other Polymers) The radiation-sensitive composition of this embodiment may also contain, as other polymers, a polymer with a higher mass content of fluorine atoms than the base polymer (hereinafter also referred to as a "high-fluorine content polymer") or a polymer with a higher introduction rate of hydrocarbon groups than the base polymer (different from the high-fluorine content polymer; hereinafter also referred to as a "high-hydrophobic polymer"). When the radiation-sensitive composition contains a high-fluorine content polymer or a high-hydrophobic polymer (hereinafter both are collectively referred to as "high-fluorine content polymers, etc."), these polymers can be unevenly distributed on the surface of the resist film relative to the base polymer. As a result, the water repellency of the surface of the resist film during immersion exposure can be enhanced, and the surface modification of the resist film and the distribution of the internal composition can be controlled during EUV exposure.

[0176] High-fluorine-content polymers may have, for example, structural units represented by the following formula (5) (hereinafter also referred to as "structural unit (V)").

[0177]

[0178] In the above formula (5), R １３This is a hydrogen atom, a methyl group, or a trifluoromethyl group. Ｌ It consists of a single bond, an alkanediyl group with 1 to 5 carbon atoms, an oxygen atom, a sulfur atom, -COO-, and -SO ２ ONH-, -CONH-, -OCONH-, or a combination thereof. １４ This is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0179] The above R １３ From the viewpoint of copolymerizability of the monomer that gives the structural unit (V), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0180] The above G Ｌ From the viewpoint of copolymerization of monomers that provide structural units (V), single bonds and -COO- are preferred, and -COO- is more preferred.

[0181] The above R １４ Examples of monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a linear or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms.

[0182] The above R １４ Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted with fluorine atoms.

[0183] The above R １４ Preferably, the group is a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl-2-yl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0184] When a high-fluorine-content polymer has structural units (V), the lower limit of the content of structural units (V) is preferably 15 mol%, more preferably 25 mol%, and even more preferably 35 mol%, relative to the total structural units constituting the high-fluorine-content polymer. The upper limit of the above content is preferably 70 mol%, more preferably 60 mol%, and even more preferably 50 mol%. By setting the content of structural units (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content polymer can be more appropriately adjusted, further promoting the uneven distribution on the surface of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0185] High-fluorine polymers may have fluorine atom-containing structural units represented by the following formula (f-2) (hereinafter also referred to as "structural unit (VI)") together with or in place of structural unit (V). Having structural unit (VI) improves the solubility of high-fluorine polymers in alkaline developers and suppresses the occurrence of development defects.

[0186]

[0187] Structural units (VI) can be broadly classified into two types: (x) those having an alkali-soluble group, and (y) those having a group that dissociates under the action of alkali, increasing its solubility in an alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). In both (x) and (y), in the above formula (f-2), R Ｃ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｄ R is a single bond, a (s+1) valent hydrocarbon group with 1 to 20 carbon atoms, and this hydrocarbon group Ｅ At the end of the side are an oxygen atom, a sulfur atom, and -NR ｄｄ -A structure to which a carbonyl group, -COO-, -OCO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms of this hydrocarbon group are substituted by an organic group having a heteroatom. ｄｄ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0188] If structural unit (VI) has (x) an alkali-soluble group, R ＦA is a hydrogen atom, １ The oxygen atom is -COO-* or -SO ２ It is O-*. * is R Ｆ This indicates the binding site. １ This is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. １ If is an oxygen atom, W １ is A １ It is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which it is bonded. Ｅ is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R Ｅ , W １ A １ and R Ｆ These may be the same or different. Having an alkali-soluble group in structural unit (VI) increases its affinity for alkaline developers and suppresses development defects. A structural unit (VI) having an alkali-soluble group is A １ is an oxygen atom and W １ It is particularly preferable that the group is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0189] If the structural unit (VI) has an alkali-dissociable group (y), R Ｆ A is a monovalent organic group having 1 to 30 carbon atoms. １ is an oxygen atom, -NR ａａ -, -COO-*, -OCO-*, or -SO ２ It is O-*. ａａ * is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Ｆ This indicates the binding site. １ R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Ｅ A is a single bond or a divalent organic group having 1 to 20 carbon atoms. １ -COO-*, -OCO-*, or -SO ２ If it is O-*, then W １ or R Ｆ is A １ It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. １If is an oxygen atom, W １ , R Ｅ It is a single bond, R Ｄ R is a hydrocarbon group having 1 to 20 carbon atoms. Ｅ It is a structure in which a carbonyl group is bonded to the terminal end, R Ｆ is an organic group having a fluorine atom. When s is 2 or 3, multiple R Ｅ , W １ A １ and R Ｆ These may be the same or different. The presence of a (y) alkali-dissociable group in structural unit (VI) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. Examples of structural units (VI) having a (y) alkali-dissociable group include A １ is -COO-*, R Ｆ Or W １ Alternatively, it is particularly preferable that both of these contain fluorine atoms.

[0190] R Ｃ From the viewpoint of copolymerizability of monomers that provide structural unit (VI), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0191] R Ｅ When the group is a divalent organic group, a group having a lactone structure is preferred, a group having a polycyclic lactone structure is more preferred, and a group having a norbornane lactone structure is even more preferred.

[0192] When a high-fluorine-content polymer has structural units (VI), the lower limit of the content of structural units (VI) is preferably 5 mol%, and more preferably 15 mol%, relative to the total structural units constituting the high-fluorine-content polymer. The upper limit of the above content is preferably 95 mol%, and more preferably 85 mol%. By setting the content of structural units (VI) within the above range, it is possible to improve the water repellency of the resist film during immersion exposure and improve solubility in alkaline developers, thereby suppressing the occurrence of development defects.

[0193] [Other structural units] High-fluorine polymers may, if necessary, include structural units other than those listed above, such as structural unit (I), structural unit (III), and structural unit (VII) in the base polymer.

[0194] When a high-fluorine-content polymer contains structural unit (I), the lower limit of the content of structural unit (I) is preferably 10 mol%, and more preferably 20 mol%, relative to the total structural units constituting the high-fluorine-content polymer. The upper limit of the above content is preferably 90 mol%, and more preferably 80 mol%.

[0195] When a high-fluorine-content polymer contains structural unit (III), the lower limit of the content of structural unit (III) is preferably 2 mol%, and more preferably 4 mol%, relative to the total structural units constituting the high-fluorine-content polymer. The upper limit of the above content is preferably 40 mol%, and more preferably 30 mol%.

[0196] When a high-fluorine-content polymer contains structural unit (VII), the lower limit of the content of structural unit (VII) is preferably 2 mol%, and more preferably 5 mol%, relative to the total structural units constituting the high-fluorine-content polymer. The upper limit of the above content is preferably 20 mol%, and more preferably 15 mol%.

[0197] The highly hydrophobic polymer may have structural units having primary, secondary, or tertiary hydrocarbyl ester structures (however, different from structural unit (I) in the base polymer; hereinafter also referred to as "structural unit (VIII)") in addition to structural unit (I) and structural unit (II) in the base polymer. In this case, it is preferable that the highly hydrophobic polymer does not contain fluorine atoms. It is preferable that structural unit (VIII) has a secondary hydrocarbyl ester structure. It is preferable that structural unit (VIII) is a structural unit represented by the following formula (VIII-1).

[0198] (In formula (VIII-1), R γ R is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. ３１ and R ３２Each of these is independently a monovalent linear hydrocarbon group having 3 to 10 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a group in which some or all of the hydrogen atoms of the alicyclic hydrocarbon group are substituted with alkyl groups, or R ３１ and R ３２ This represents a monovalent alicyclic group having 3 to 20 carbon atoms, which can be combined with the carbon atoms to which they are bonded, or a group in which some or all of the hydrogen atoms of the alicyclic group are replaced with alkyl groups.

[0199] R γ As an alkyl group having 1 to 10 carbon atoms represented by the above formula (1), W ａ Among the alkyl groups shown, groups corresponding to those with 1 to 10 carbon atoms can be preferably adopted.

[0200] R ３１ and R ３２ As a monovalent chain hydrocarbon group having 3 to 10 carbon atoms represented by the above formula (1), W ａ Among the monovalent chain hydrocarbon groups having 1 to 20 carbon atoms shown above, groups corresponding to 3 to 10 carbon atoms can be suitably adopted. In particular, R ３１ and R ３２ The monovalent chain hydrocarbon group having 3 to 10 carbon atoms represented by isopropyl, isobutyl, t-butyl, and n-hexyl groups are preferred.

[0201] R ３１ and R ３２ As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (1), W ａ The monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms shown above can be suitably adopted. The alkyl group that substitutes some or all of the hydrogen atoms of the alicyclic hydrocarbon group is R γ A C1 to C10 alkyl group represented by [the formula shown] can be preferably used.

[0202] R ３１ and R ３２ As a monovalent alicyclic group having 3 to 20 carbon atoms formed by combining these, the W in formula (1) above is an example. ａ The monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms shown above can be suitably adopted. In particular, R３１ and R ３２ which are bonded to each other, the monovalent alicyclic group having 3 to 20 carbon atoms thus formed is preferably a monocyclic or polycyclic cycloalkyl group, more preferably a cyclopentyl group, a cyclohexyl group, or a norbornyl group. As the alkyl group that substitutes for part or all of the hydrogen atoms of the above monovalent alicyclic group, R γ an alkyl group having 1 to 10 carbon atoms represented by can be suitably employed. Among these, the alkyl group as a substituent is preferably a methyl group, an ethyl group, an isopropyl group, or a t-butyl group.

[0203] When the highly hydrophobic polymer has the structural unit (VIII), the content ratio of the structural unit (VIII) (the total content ratio when multiple types are included) is based on all structural units constituting the highly hydrophobic polymer, 5 mol% is preferable, 10 mol% is more preferable, and 15 mol% is further more preferable. Further, the upper limit of the above content ratio is preferably 40 mol%, more preferably 30 mol%, and still more preferably 25 mol%. By setting the content ratio of the structural unit (VIII) within the above range, it is possible to increase the water repellency of the resist film during immersion exposure, and improve the solubility in an alkaline developer to suppress the occurrence of development defects.

[0204] When the highly hydrophobic polymer contains the structural unit (I), the content ratio of the structural unit (I) is based on all structural units constituting the highly hydrophobic polymer, 50 mol% is preferable, and 60 mol% is more preferable. Further, the upper limit of the above content ratio is preferably 90 mol%, more preferably 80 mol%.

[0205] When the highly hydrophobic polymer contains the structural unit (II), the content ratio of the structural unit (II) is based on all structural units constituting the highly hydrophobic polymer, 4 mol% is preferable, and 8 mol% is more preferable. Further, the upper limit of the above content ratio is preferably 15 mol%, more preferably 10 mol%.

[0206] The lower limit of Mw of a high fluorine content polymer or the like is preferably 3,000, and more preferably 4,000. Further, the upper limit of the above Mw is preferably 20,000, more preferably 14,000.

[0207] The lower limit of Mw / Mn of a polymer having a high fluorine content or the like is usually 1, and more preferably 1.1. Further, the upper limit of the above Mw / Mn is usually 5, preferably 3, and more preferably 2.

[0208] When the radiation-sensitive composition contains a polymer having a high fluorine content or the like, the lower limit of the content of the polymer having a high fluorine content or the like is preferably 0.5 parts by mass, more preferably 1 part by mass, and still more preferably 1.5 parts by mass, relative to 100 parts by mass of the base polymer described above. Further, the upper limit of the above content is preferably 15 parts by mass, more preferably 10 parts by mass, and still more preferably 8 parts by mass.

[0209] By setting the content of the polymer having a high fluorine content or the like within the above range, the polymer having a high fluorine content or the like can be more effectively unevenly distributed on the surface layer of the resist film. As a result, it is possible to enhance the water repellency of the resist film surface during immersion exposure, and to achieve surface modification of the resist film and control of the in-film composition distribution during EUV exposure. The radiation-sensitive composition may contain one or two or more polymers having a high fluorine content or the like.

[0210] (Method for Synthesizing Polymer having High Fluorine Content, etc.) A polymer having a high fluorine content or the like can be synthesized by the same method as the above-mentioned method for synthesizing the base polymer.

[0211] <Acid Diffusion Controller> The radiation-sensitive composition may optionally contain an acid diffusion controller. The acid diffusion controller controls the diffusion phenomenon in the resist film of acids generated from the first radiation-sensitive acid generator and the second radiation-sensitive acid generator upon exposure, and exhibits the effect of suppressing undesirable chemical reactions in unexposed regions. Further, the storage stability of the resulting radiation-sensitive composition is improved. Furthermore, while the resolution of the resist pattern is further enhanced, it is possible to suppress changes in the line width of the resist pattern caused by fluctuations in the waiting time from exposure to development processing, whereby a radiation-sensitive composition excellent in process stability can be obtained.

[0212] Examples of acid diffusion control agents include compounds represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compounds (I)"), compounds having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compounds (II)"), compounds having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compounds (III)"), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

[0213]

[0214] In the above formula (7), R ２２ , R ２３ and R ２４ Each of these is independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0215] Examples of nitrogen-containing compounds (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline and 2,6-di-i-propylaniline.

[0216] Examples of nitrogen-containing compounds (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0217] Examples of nitrogen-containing compounds (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

[0218] Examples of amide group-containing compounds include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0219] Examples of urea compounds include urea, methyl urea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tributylthiourea.

[0220] Examples of nitrogen-containing heterocyclic compounds include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; and pyrazines and pyrazoles.

[0221] Furthermore, compounds having an acid-dissociable group can also be used as the nitrogen-containing organic compound. Examples of nitrogen-containing organic compounds having an acid-dissociable group include N-t-butoxycarbonylpiperidine, N-t-butoxycarbonylimidazole, N-t-butoxycarbonylbenzimidazole, N-t-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, N-t-butoxycarbonyl-4-hydroxypiperidine, N-t-butoxycarbonyl-4-acetoxypiperidine, and N-t-amyloxycarbonyl-4-hydroxypiperidine.

[0222] Furthermore, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can be suitably used as an acid diffusion control agent. The acid generated from the above-mentioned radiation-sensitive weak acid generator is a weak acid that does not dissociate the acid-dissociable groups in the polymer under conditions that cause the acid-dissociable groups to dissociate.

[0223] Examples of radiation-sensitive weak acid generators include onium salt compounds that decompose upon exposure and lose their ability to control acid diffusion. Examples of onium salt compounds include sulfonium salt compounds represented by the following formula (8-1) and iodonium salt compounds represented by the following formula (8-2). Also, examples include compounds containing a sulfonium cation and anion in the same molecule, represented by the following formula (8-3), and compounds containing an iodonium cation and anion in the same molecule, represented by the following formula (8-4).

[0224]

[0225] In the above formulas (8-1) to (8-4), J ＋ It is a sulfonium cation, U＋ This is an iodonium cation. ＋ Examples of sulfonium cations represented by the above formulas (X-1) to (X-4) include U ＋ Examples of iodonium cations represented by the above formulas (X-5) to (X-6) include iodonium cations represented by E. - and Q - Each of them is independent of OH - , R α -COO - , R α -SO ３ - This is an anion represented by R. α R is a single bond or a monovalent organic group having 1 to 30 carbon atoms. α As a monovalent organic group having 1 to 30 carbon atoms represented by the above formula (2), W ｂ Of the monovalent organic groups having 1 to 40 carbon atoms represented by , groups corresponding to 1 to 30 carbon atoms can be suitably adopted. Furthermore, if radiation sensitivity is not required, an organic ammonium cation can be used instead of the sulfonium cation or iodonium cation mentioned above.

[0226] Examples of anions for the above-mentioned acid diffusion control agent include, but are not limited to, those listed below. Compounds containing both an iodonium cation and anion within the same molecule, and compounds containing both a sulfonium cation and anion within the same molecule are also given as examples. The iodine group in the following formulas may be substituted with a hydrogen atom or other substituents.

[0227]

[0228]

[0229] As the onium cation in the above-mentioned acid diffusion control agent, the radioactive onium cation of the above-mentioned first radioactive acid generator or an organic ammonium cation such as a tetraalkylammonium cation can be suitably used.

[0230] The above-mentioned acid diffusion control agents can also be synthesized by known methods, particularly by salt exchange reactions.

[0231] These acid diffusion control agents may be used individually or in combination of two or more. When the radiation-sensitive composition contains an acid diffusion control agent, the lower limit of the acid diffusion control agent content (total in the case of multiple types) is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, and even more preferably 1 part by mass, per 100 parts by mass of the base polymer. The upper limit of the above content is preferably 50 parts by mass, more preferably 40 parts by mass, and even more preferably 35 parts by mass.

[0232] (Solvent) The radiation-sensitive composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing the first radiation-sensitive acid generator, the second radiation-sensitive acid generator, the base polymer, and any optional components that may be contained therein.

[0233] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0234] Examples of alcohol-based solvents include monoalcohol solvents having 1 to 18 carbon atoms, such as isopropanol, 4-methyl-2-pentanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; and polyhydric alcohol partial ether solvents, such as 3-methoxybutanol and 1-methoxy-2-propanol (propylene glycol monomethyl ether), which are obtained by etherifying some of the hydroxyl groups in the above-mentioned polyhydric alcohol solvents. In this embodiment, alcohol acid ester solvents such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, isopropyl 2-hydroxyisobutyrate, isobutyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate are also included in the alcohol-based solvents.

[0235] Examples of ether solvents include: dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); and polyhydric alcohol ether solvents obtained by etherifying the hydroxy group of the above polyhydric alcohol solvents such as propylene glycol monomethyl ether.

[0236] Examples of ketone solvents include: chain ketone solvents such as acetone, butanone, and methyl isobutyl ketone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0237] Examples of amide solvents include: cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0238] Examples of ester solvents include: monocarboxylic acid ester solvents such as n-butyl acetate; polyhydric alcohol partial ether acetate ester solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; lactone solvents such as γ-butyrolactone and valerolactone; carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; and polyhydric carboxylic acid diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, and diethyl phthalate.

[0239] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, diisopropylbenzene, and n-amylnaphthalene.

[0240] Among these, alcohol-based solvents and ester-based solvents are preferred, alcoholic acid ester-based solvents, monocarboxylic acid ester-based solvents, polyhydric alcohol partial ether-based solvents, polyhydric alcohol partial ether acetate-based solvents, and lactone-based solvents are more preferred, and ethyl lactate, methyl 2-hydroxyisobutyrate, butyl acetate, propylene glycol acetate monomethyl ether, propylene glycol monomethyl ether, and γ-butyrolactone are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0241] (Other optional components) The above-mentioned radiation-sensitive composition may contain other optional components in addition to the components listed above. Examples of these other optional components include crosslinking agents, localization promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, etc. These other optional components may be used individually or in combination of two or more types.

[0242] <Method for preparing a radiation-sensitive composition> The above radiation-sensitive composition can be prepared by mixing, for example, compound (A), polymer, and optionally additives, as well as a solvent, in predetermined proportions. After mixing, it is preferable to filter the above radiation-sensitive composition using, for example, a filter with a pore size of about 0.05 μm to 0.40 μm.

[0243] <Pattern Forming Method> A pattern forming method according to one embodiment of the present invention includes a step (1) of applying the above-mentioned radiation-sensitive composition directly or indirectly to a substrate to form a resist film (hereinafter also referred to as the "resist film forming step"), a step (2) of exposing the resist film (hereinafter also referred to as the "exposure step"), and a step (3) of developing the exposed resist film with a developer solution (hereinafter also referred to as the "development step").

[0244] According to the pattern formation method described above, since the radiation-sensitive composition is used during pattern formation that exhibits excellent sensitivity, CDU, LWR, pattern rectangularity, etching resistance, exposure margin (EL), depth of field (DOF), storage stability before and after exposure, and suppression of development defects, high-quality resist patterns can be efficiently formed. Each step will be described below.

[0245] [Resist Film Formation Process] In this process (step (1) above), a resist film is formed using the radiation-sensitive composition. Examples of substrates for forming this resist film include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Publication No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting, and roll coating. After coating, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 170°C, with 80°C to 150°C being preferred. The PB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0246] The lower limit of the thickness of the resist film formed is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm. The upper limit of the thickness may be 5000 nm (5 μm), 4000 nm (4 μm), 2000 nm (2 μm), 1000 nm (1 μm), or 800 nm.

[0247] When performing immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine-content polymer in the above-mentioned radiation-sensitive composition, an immersion-insoluble protective film may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the immersion-protective film, either a solvent-peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Publication No. 2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development process (see, for example, Japanese Patent Application Publication Nos. WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable immersion-protective film.

[0248] [Exposure Process] In this process (process (2) above), the resist film formed in the resist film formation process, which is process (1) above, is exposed by irradiating it with radiation through a photomask (and, in some cases, through an immersion liquid such as water). The radiation used for exposure can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays, depending on the line width of the desired pattern; electron beams, alpha rays, and other charged particle beams. Among these, far ultraviolet light, electron beams, and EUV are preferred, and ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred.

[0249] When exposure is performed by immersion lithography, the immersion liquid used can be, for example, water or a fluorine-based inert liquid. The immersion liquid is preferably transparent to the exposure wavelength and has the smallest possible temperature coefficient of refractive index to minimize distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above considerations, water is preferred due to its availability and ease of handling. When water is used, a small amount of an additive that reduces the surface tension of the water and increases its surfactant properties may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0250] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in polymers, etc., by the acid generated from the primary and secondary radiation-sensitive acid generators during exposure in the exposed portion of the resist film. This PEB creates a difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is usually 60°C to 170°C, with 80°C to 150°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0251] [Development Process] In this process (step (3) above), the resist film exposed in the exposure process, which is step (2) above, is developed. This allows a predetermined resist pattern to be formed. After development, it is common to wash with a rinsing solution such as water or alcohol and then dry it.

[0252] Examples of developers used in the above development process include, in the case of alkaline development, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0253] Furthermore, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, etc., or solvents containing organic solvents. Examples of the above organic solvents include one or more of the solvents listed above as solvents for the radiation-sensitive composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As for ether solvents, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As for ester solvents, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The content of organic solvents in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than organic solvents in the developer include water and silicone oil.

[0254] As mentioned above, either an alkaline developer or an organic solvent developer may be used as the developer. The appropriate choice can be made depending on whether a positive or negative pattern is desired.

[0255] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by puddling the developer solution onto the substrate surface using surface tension and leaving it still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method).

[0256] Compounds The compounds according to this embodiment are compounds represented by the following formulas (1-3). (In formula (1-3), W ａ１This is a monovalent aliphatic group A1 having three carbon atoms consisting of a carbon atom and a hydrogen atom, a monovalent aliphatic group B1 consisting of at least one atom selected from the group consisting of an oxygen atom, a halogen atom, and a sulfur atom, and a carbon atom and a hydrogen atom, or a substituted or unsubstituted monovalent monocyclic aromatic group C1. However, W ａ１ The following requirements (a) and (b) are met: (a) W ａ１ The number of oxygen atoms in is 3 or less; and (b) L １ If is a divalent group represented by the following formula (i), then W ａ１ In the above, the monovalent aliphatic group B1 has a chain-like structure. １ This is a divalent group represented by the following formulas (i), (ii), (iii), or (iv). (In formulas (i) to (iv), R ２１ and R ２２ Each of these is independently either a hydrogen atom or a methyl group. ２１ and R ２２ If multiple R ２１ and R ２２ These are either identical or different from each other. m1 is an integer between 0 and 2. m2 is an integer between 0 and 5. * is W in the above equation (1-3). ａ１ This is a combination of . ** is R in equation (1-3) above. １ This is the bond with the carbon atom to which it is bonded. １ These are monovalent hydrocarbon groups having 1 to 20 carbon atoms, -F, -CF ２ H, -SO ２ -R １１ , or -CN. R １１ This is a monovalent hydrocarbon group having 1 to 20 carbon atoms. ＋ (This is an organic cation.)

[0257] The compound in question is the compound represented by formula (1-1) above as the first radioactive acid generator, wherein the monovalent aliphatic group A has 3 carbon atoms, L １ If is a divalent group represented by the above formula (i), then W ａ１Except for the fact that the monovalent aliphatic group B1 in the above compound has a chain structure and the cation is an organic cation, the same configuration as the compound represented by formula (1-1) can be suitably adopted. The differences from the compound represented by formula (1-1) will be explained below.

[0258] In the above formulas (1-3), W ａ１ From the viewpoint of diffusion length and aggregation suppression, this is a monovalent aliphatic group A1 having 3 carbon atoms consisting of a carbon atom and a hydrogen atom, or a substituted or unsubstituted monovalent monocyclic aromatic group C1, provided that W ａ１ The number of oxygen atoms in is preferably three or less.

[0259] M ＋ Examples of organic cations represented by include onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples of onium cations include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, pyridinium cations, and ammonium cations. ＋ The organic cation represented is preferably a sulfonium cation or an iodonium cation. The sulfonium cation and iodonium cation shown in the first radiation-sensitive acid generator described above can be suitably used.

[0260] In the above formulas (1-3), M ＋ It may have a structure represented by the following formula (1-1-C). (In formula (1-1-C), Ar １ R is a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group. ｐ１ R is a substituted or unsubstituted phenyl group, ｐ２ is either an alkyl group or R ｐ１ and R ｐ２ They are combined with each other and they join together S ＋ (Together, they form a ring structure.)

[0261] Ar １, R ｐ１ and R ｐ２ As substituents in the above formula (1-2), substituents that W may have can be preferably adopted.

[0262] R ｐ１ and R ｐ２ The ring structure formed by this is W in formula (1) above. ａ The methylene group in the structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms shown in the above is S ＋ The structure replaced by W in the above equation (2) ｂ The methylene group in the aliphatic heterocyclic structure shown above is S ＋ The structure in which the sulfur atom in the sulfur-containing aromatic ring structure of thiophene and benzothiophene is replaced with S ＋ Examples include structures in which the carbon atoms are replaced. In particular, it is preferable that the ring structure contains oxygen atoms (-O-) between the carbon-carbon bonds that form the skeleton.

[0263] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are shown below.

[0264] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the conditions described above. The degree of dispersion (Mw / Mn) was calculated from the measured results of Mw and Mn.

[0265] [ １３ [C-NMR analysis] Polymer １３ C-NMR analysis was performed using a nuclear magnetic resonance spectrometer (JEOL Ltd.'s "JNM-Delta400").

[0266] <Synthesis of Polymers> The monomers used in the synthesis of each polymer in each example and comparative example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refers to the value when the total mass of the monomers used is 100 parts by mass, and mol% refers to the value when the total number of moles of the monomers used is 100 mol%.

[0267]

[0268] [Synthesis Example 1] (Synthesis of Polymer (A-1)) Monomers (M-1), (M-3), (M-5), (M-10), and (M-14) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 35 / 5 / 45 / 10 / 5 (mol%). AIBN (azobisisobutyronitrile) (10 mol%) relative to the total 100 mol% of the monomers used) was added as an initiator to prepare a monomer solution. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered again, and dried at 50°C for 24 hours to obtain a white powdery polymer (A-1) (yield: 85%). The Mw of polymer (A-1) was 5,100, and the Mw / Mn ratio was 1.62. Furthermore, １３ ¹³C-NMR analysis revealed that the content percentages of each structural unit derived from (M-1), (M-3), (M-5), (M-10), and (M-14) were 35.1 mol%, 4.8 mol%, 45.3 mol%, 10.2 mol%, and 4.6 mol%, respectively.

[0269] [Synthesis Examples 2-11] (Synthesis of Polymers (A-2) to (A-11)) Polymers (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that monomers of the types and proportions shown in Table 1 below were used. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymers are also shown in Table 1 below. Note that "-" in Table 1 below indicates that the corresponding monomer was not used (the same applies to subsequent tables).

[0270]

[0271] (Synthesis of Polymer (A-12)) Monomers (M-4), (M-5), and (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) in a molar ratio of 60 / 10 / 30 (mol%), and AIBN (7 mol%) was added as an initiator to prepare monomer solutions. 100 parts by mass of 1-methoxy-2-propanol was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the temperature inside the reaction vessel was raised to 80°C, and the monomer solutions were added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Then, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After the reaction was complete, the residual solvent was removed by distillation, and the resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to solidify the polymer. The resulting solid was filtered and dried at 50°C for 13 hours to obtain a white powdery polymer (A-12) (yield: 81%). The Mw of polymer (A-12) was 5,900, and the Mw / Mn ratio was 1.55. １３ 13C-NMR analysis revealed that the content of each structural unit derived from (M-4), (M-5), and (M-18) was 60.3 mol%, 10.3 mol%, and 29.4 mol%, respectively.

[0272] [Synthesis Examples 13-16] (Synthesis of Polymers (A-13) to (A-16)) Polymers (A-13) to (A-15) were synthesized in the same manner as in Synthesis Example 12, except that monomers of the types and proportions shown in Table 2 below were used. Note that for monomers that give structural unit (IV), in the polymer, １３ 13C-NMR measurements confirmed the disappearance of the carbonyl group peak of the acetyl group, indicating that virtually all alkali-dissociable groups had been hydrolyzed to phenolic hydroxyl groups. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymer are shown in Table 2 below.

[0273]

[0274] [Synthesis Example 17] (Synthesis of High Fluorine-Content Polymer (F-1)) Monomer (M-4) and monomer (M-20) were dissolved in 2-butanone (200 parts by mass) in a molar ratio of 45 / 55 (mol%), and AIBN (3 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the temperature inside the reaction vessel was set to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of high fluorine-content polymer (F-1) was obtained (yield: 75%). The Mw of the high-fluorine-content polymer (F-1) was 8,700, and the Mw / Mn ratio was 1.67. Furthermore, １３ ¹³C-NMR analysis revealed that the content of each structural unit derived from (M-4) and (M-20) was 44.9 mol% and 55.1 mol%, respectively.

[0275] [Synthesis Examples 18-22] (Synthesis of high-fluorine content polymers (F-2) to high-fluorine content polymers (F-5) and high-hydrophobic polymers (F-6)) High-fluorine content polymers (F-2) to high-fluorine content polymers (F-5) and high-hydrophobic polymers (F-6) were synthesized in the same manner as in Synthesis Example 16, except that monomers of the types and blending ratios shown in Table 3 below were used. The content ratio (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained high-fluorine content polymers are shown in accordance with Table 3 below.

[0276]

[0277] <Synthesis of Primary Radiation-Inducing Acid Generator B> [Synthesis Example B1] (Synthesis of Primary Radiation-Inducing Acid Generator (B-1)) Compound (B-1) as a primary radiation-induced acid generator was synthesized according to the following synthesis scheme.

[0278]

[0279] 20.0 mmol of 1-bromodecane, 20.0 mmol of malononitrile, 30.0 mmol of potassium carbonate, and 50 g of acetone were added to a reaction vessel and stirred at 50°C for 12 hours. Then, saturated aqueous ammonium chloride solution was added to the reaction solution to terminate the reaction, and ethyl acetate was added for extraction, separating the organic layer. The obtained organic layer was washed with saturated aqueous sodium chloride solution and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the dicyano compound was obtained in good yield by column chromatography.

[0280] 30.0 mmol of chlorosulfonic acid, 3.0 mmol of potassium carbonate, and 50 g of dichloromethane were added to the above dicyano compound and the mixture was stirred at room temperature for 12 hours. Then, 30.0 mmol of triphenylsulfonium bromide and 50 g of water were added to the reaction solution and the mixture was stirred at room temperature for 1 hour. Dichloromethane was then added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the compound (B-1) represented by the above formula (B-1) was purified by column chromatography to obtain compound (B-1) in good yield.

[0281] [Synthesis Examples B2 to B16] (Synthesis of compounds (B-2) to (B-16)) Compounds as radiation-sensitive acid generators represented by the following formulas (B-2) to (B-16) were synthesized in the same manner as in Synthesis Example B1, except that the raw materials and precursors were appropriately changed.

[0282]

[0283]

[0284] [Example B101] (Synthesis of primary radiation-sensitive acid generator (B-101)) Compound (B-101) as a primary radiation-sensitive acid generator was synthesized according to the following synthesis scheme.

[0285]

[0286] 20.0 mmol of compound (B-101-1), 20.0 mmol of malononitrile, 30.0 mmol of potassium carbonate, and 50 g of acetone were added to a reaction vessel and stirred at 50°C for 12 hours. Then, saturated aqueous ammonium chloride solution was added to the reaction solution to terminate the reaction, and ethyl acetate was added for extraction, separating the organic layer. The obtained organic layer was washed with saturated aqueous sodium chloride solution and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the compound (B-101-2) was obtained in good yield by purification by column chromatography.

[0287] To the above compound (B-101-2), 30.0 mmol of sulfur trioxide-pyridine complex, 30.0 mmol of sodium hydride, and 50 g of dichloromethane were added and the mixture was stirred at room temperature for 24 hours. Then, 30.0 mmol of triphenylsulfonium bromide and 50 g of water were added to the reaction solution and the mixture was stirred at room temperature for 1 hour. After that, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the compound (B-101) represented by the above formula (B-101) was purified by column chromatography to obtain the compound (B-101) represented by the above formula in good yield.

[0288] [Examples B102 to B117] (Synthesis of compounds (B-102) to (B-117)) Compounds as radiation-sensitive acid generators represented by the following formulas (B-102) to (B-117) were synthesized in the same manner as in Example B101, except that the raw materials and precursors were appropriately changed.

[0289]

[0290]

[0291] [Radiation-sensitive acid generators other than the first type of radiation-sensitive acid generator (B-1) to (B-16) and (B-101) to (B-107)] b-1 to b-7: Compounds represented by the following formulas (b-1) to (b-7).

[0292]

[0293] [C] Compounds as secondary radiation-sensitive acid generators: C-1 to C-14: Compounds represented by the following formulas (C-1) to (C-14) were used as secondary radiation-sensitive acid generators.

[0294]

[0295] [[D] Compounds as acid diffusion control agents] D-1 to D-7: Compounds represented by the following formulas (D-1) to (D-7) were used as acid diffusion control agents.

[0296]

[0297] [Q] Compounds used as crosslinking agents Q-1: A compound represented by the following formula (Q-1) was used as a crosslinking agent.

[0298]

[0299] [E] Solvents E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: γ-Butyrolactone E-4: Ethyl lactate E-5: Butyl acetate E-6: Methyl 2-hydroxyisobutyrate

[0300] [Preparation of positive-type radiation-sensitive composition for ArF immersion exposure] [Example 1] A radiation-sensitive composition (J-1) was prepared by mixing 100 parts by mass of (A-1) as a polymer, 5.0 parts by mass of (F-1) as a high-fluorine-content polymer (solids), 6.0 parts by mass of (B-1) as a first radiation-sensitive acid generator, 5.0 parts by mass of (C-1) as a second radiation-sensitive acid generator, 8.0 parts by mass of (D-1) as an acid diffusion control agent, and 3,400 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0301] [Examples 2-41, 101-117 and Comparative Examples 1-11] Radiation-sensitive compositions (J-2) to (J-41), (J-101) to (J-117), and (CJ-1) to (CJ-11) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 4-1, 4-2, and 4-3 below were used.

[0302]

[0303]

[0304]

[0305] <Formation of a resist pattern using a positive-type radiation-sensitive composition for ArF immersion lithography> An anti-reflective underlayer film formation composition ("ARC66" from Brewer Science) was applied to a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form an anti-reflective underlayer film with an average thickness of 100 nm. The positive-type radiation-sensitive composition for ArF immersion lithography prepared above was applied to this anti-reflective underlayer film using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 110 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7) through a mask pattern of a resist pattern with 50 nm holes and a 120 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer, washed with water after development, and then dried to form a positive-type resist pattern (a resist pattern with 50 nm holes and a 120 nm pitch).

[0306] <Evaluation> The resist patterns formed using the above ArF immersion exposure positive-type radiation-sensitive composition were evaluated for sensitivity, CDU, pattern rectangularity, etching resistance, EL, storage stability before and after exposure, and development defect suppression according to the following methods. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns. The results are shown in Tables 5-1, 5-2, and 5-3 below.

[0307] [Sensitivity] In forming a resist pattern using the above ArF immersion lithography positive-type radiation-sensitive composition, the exposure amount used to form a resist pattern with 50 nm holes and a 120 nm pitch is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２The sensitivity was set to 40 mJ / cm². ２ In the following cases, it is considered "good" and 40 mJ / cm². ２ If it exceeded this value, it was rated as "poor."

[0308] [CDU] A resist pattern with 50 nm holes and a 120 nm pitch was measured at 1,800 arbitrary points from the top of the pattern using the scanning electron microscope described above. The dimensional variation (3σ) was determined and defined as CDU (nm). A smaller CDU value indicates less variation in hole diameter over long periods and therefore better performance. CDU performance was evaluated as "good" if it was 3.5 nm or less, and "poor" if it exceeded 3.5 nm.

[0309] [Pattern Rectangularity] The resist patterns with 50 nm holes and a 120 nm pitch, formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above, were observed using the scanning electron microscope described above, and the cross-sectional shape of the contact hole pattern was evaluated. The rectangularity of the resist pattern was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side (aperture diameter) in the cross-sectional shape was 1.00 or more and 1.05 or less, it was evaluated as "A" (excellent); if it was greater than 1.05 and 1.10 or less, it was evaluated as "B" (good); and if it was greater than 1.10, it was evaluated as "C" (poor).

[0310] [Etching Resistance] The resist pattern with 50 nm holes and a 120 nm pitch, formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above, was etched using an etching device (Tokyo Electron's "TACTRAS") and CF ４ The resist film was treated with gas, and the etching rate (nm / min) was calculated from the time required for the resist film to disappear. The ratio of this ratio to the etching rate in Comparative Example 1 was determined and used as a measure of etching resistance. Etching resistance was evaluated as follows: if the ratio was 0.95 or more and less than 0.98, it was "A" (excellent); if it was 0.98 or more and less than 1.00, it was "B" (good); and if it was 1.00 or more, it was "C" (poor). In Table 5-2, "-" in Comparative Example 1 indicates that it is an evaluation criterion.

[0311] [EL (Exposure Margin)] Within the range of exposure amounts including the above optimal exposure amount, the exposure amount is 1 mJ / cm². ２Each resist pattern was formed by varying the exposure dose, and the hole diameter was measured using the scanning electron microscope described above. From the relationship between the obtained diameter and exposure dose, the exposure dose E(66) that resulted in a diameter of 66 nm and the exposure dose E(54) that resulted in a diameter of 54 nm were determined, and the exposure margin (EL) was calculated using the formula: Exposure margin (EL) = (E(54) - E(66)) × 100 / (Optimal exposure dose). The larger the exposure margin value, the smaller the variation in the dimensions of the pattern obtained when the exposure dose is varied, and the higher the yield during device fabrication. An EL of 7% or more was evaluated as "good," and a value below 7% was evaluated as "poor."

[0312] [Storage Stability Before Exposure] The above ArF immersion lithography positive-type radiation-sensitive composition was stored at 35°C for 30 days, and then the optimal exposure amount, i.e., sensitivity, for forming a resist pattern with 50 nm holes and a 120 nm pitch was measured again. The sensitivity before storage (S), expressed by the following formula, was measured. ０ Sensitivity (S) after 30 days of storage for ) ３０ If the rate of change of ) was between 0% and 1.0%, it was evaluated as "A" (excellent); if it was between 1.0% and 2.0%, it was evaluated as "B" (good); and if it was above 2.0%, it was evaluated as "C" (poor). Rate of change of sensitivity (%) = | (S ３０ -S ０ ) / S ０ | × 100

[0313] [Storage Stability After Exposure (PED Storage Stability)] The optimal exposure amount determined in the sensitivity evaluation above was applied, and PEB was performed at 100°C for 60 seconds. After that, the material was stored at room temperature for 12 hours before proceeding with the development process. After storage, the resist film was alkaline developed, washed with water after development, and then dried to form a positive-type resist pattern, and the line width was measured. The line width L in the normal development process is expressed by the following formula. ０ Line width L after 12 hours of storage at room temperature following PEB １２ If the rate of change was between 0% and 5.0%, it was evaluated as "A" (excellent); if it was between 5.0% and 7.5%, it was evaluated as "B" (good); and if it was above 7.5%, it was evaluated as "C" (poor). Rate of change of line width (%) = |(L １２ -L ０ ) / L ０ | × 100

[0314] [Development Defect Count] A resist film was exposed at the optimal exposure level to form a resist pattern with 50 nm holes and a 120 nm pitch, and this was used as a wafer for defect inspection. The number of defects on this wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Defects with a diameter of 5 μm or less were judged to be originating from the resist film, and their number was calculated. After development, the defect count was evaluated as "good" if the number of defects judged to be originating from the resist film was 150 or less, and as "poor" if it exceeded 150.

[0315]

[0316]

[0317]

[0318] As is clear from the results in Tables 5-1, 5-2, and 5-3, the radiation-sensitive compositions of the examples exhibited good sensitivity, CDU performance, pattern rectangularity, etching resistance, exposure margin, pre- and post-exposure storage stability, and development defect count when used in ArF immersion lithography, whereas the comparative examples failed to satisfy all of these characteristics. Therefore, when the radiation-sensitive compositions of the examples are used in ArF immersion lithography, it is possible to form a resist pattern with optimal sensitivity and excellent roughness performance, pattern shape, and various margins.

[0319] [Preparation of positive-type radiation-sensitive composition for ArF-Dry exposure] [Example 42] A radiation-sensitive composition (J-42) was prepared by mixing 100 parts by mass of (A-1) as a polymer, 4.0 parts by mass of (B-2) as a first radiation-sensitive acid generator, 4.0 parts by mass of (C-1) as a second radiation-sensitive acid generator, 3.0 parts by mass of (D-6) as an acid diffusion control agent, and 2,830 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0320] [Examples 43-58, 121-128 and Comparative Examples 12-22] Radiation-sensitive compositions (J-43)-(J-58), (J-121)-(J-128), and (CJ-12)-(CJ-22) were prepared in the same manner as in Example 42, except that the components of the types and amounts shown in Table 6 below were used.

[0321]

[0322] <Formation of a resist pattern using a positive-type radiation-sensitive composition for ArF-Dry exposure> An anti-reflective base layer film (ARC29 from Brewer Sciences) was applied to an 8-inch silicon wafer using a spin coater (CLEAN TRACK ACT8 from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form an anti-reflective base layer film with an average thickness of 77 nm. The positive-type radiation-sensitive composition for ArF-Dry exposure prepared above was applied to this anti-reflective base layer film using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 300 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed using an ArF excimer laser exposure system (Nikon's "S306C") under optical conditions of NA = 0.75 and Annular (σ = 0.8 / 0.6) through a mask pattern of a resist pattern with 150 nm holes and a 250 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer, washed with water after development, and then dried to form a positive-type resist pattern (a resist pattern with 150 nm holes and a 250 nm pitch).

[0323] <Evaluation> The resist patterns formed using the above ArF-Dry positive-type radiation-sensitive composition were evaluated for sensitivity, CDU performance, storage stability before and after exposure, and development defects according to the following method. The results are shown in Table 7 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "S-9380") was used to measure the length of the resist patterns.

[0324] [Sensitivity] In forming a resist pattern using the above ArF-Dry positive-type radiation-sensitive composition, the exposure amount used to form a resist pattern with 150 nm holes and a 250 nm pitch is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity was set to 25 mJ / cm². ２ The following conditions are considered "good" and 25 mJ / cm². ２ If it exceeded this value, it was rated as "poor."

[0325] [CDU] A resist pattern with 150 nm holes and a 250 nm pitch was measured at 1,800 arbitrary points from the top of the pattern using the scanning electron microscope described above. The dimensional variation (3σ) was determined and defined as CDU (nm). A smaller CDU value indicates less variation in hole diameter over long periods and therefore better performance. CDU performance was evaluated as "good" if it was 2.5 nm or less, and "poor" if it exceeded 2.5 nm.

[0326] [Storage Stability Before Exposure] After storing the above ArF-Dry exposure positive-type radiation-sensitive composition at 35°C for 30 days, the optimal exposure amount, i.e., sensitivity, for forming a resist pattern with 150 nm holes and a 250 nm pitch was measured again. The sensitivity before storage (S), expressed by the following formula, was measured again. ０ Sensitivity (S) after 30 days of storage for ) ３０ If the rate of change of ) was between 0% and 1.0%, it was evaluated as "A" (excellent); if it was between 1.0% and 2.0%, it was evaluated as "B" (good); and if it was above 2.0%, it was evaluated as "C" (poor). Rate of change of sensitivity (%) = | (S ３０ -S ０ ) / S ０ | × 100

[0327] [Storage Stability After Exposure (PED Storage Stability)] The optimal exposure amount determined in the sensitivity evaluation above was applied, and PEB was performed at 100°C for 60 seconds. After that, the material was stored at room temperature for 12 hours before proceeding with the development process. After storage, the resist film was alkaline developed, washed with water after development, and then dried to form a positive-type resist pattern, and the line width was measured. The line width L in the normal development process is expressed by the following formula. ０ Line width L after 12 hours of storage at room temperature following PEB１２ If the rate of change was between 0% and 5.0%, it was evaluated as "A" (excellent); if it was between 5.0% and 7.5%, it was evaluated as "B" (good); and if it was above 7.5%, it was evaluated as "C" (poor). Rate of change of line width (%) = |(L １２ -L ０ ) / L ０ | × 100

[0328] [Development Defect Count] A resist film was exposed at the optimal exposure level to form a resist pattern with 150 nm holes and a 250 nm pitch, and this was used as a wafer for defect inspection. The number of defects on this wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Defects with a diameter of 5 μm or less were judged to be originating from the resist film, and their number was calculated. After development, the defect count was evaluated as "good" if the number of defects judged to be originating from the resist film was 150 or less, and as "poor" if it exceeded 150.

[0329]

[0330] As is clear from the results in Table 7, the radiation-sensitive composition of the example showed good sensitivity, CDU performance, storage stability before and after exposure, and development defects when used in ArF-Dry exposure, whereas the comparative example did not satisfy all of these characteristics. Therefore, when the radiation-sensitive composition of the example is used in ArF-Dry exposure, it is possible to form a resist pattern with optimal sensitivity, excellent roughness performance, and good margins.

[0331] [Preparation of positive-type radiation-sensitive composition for KrF exposure] [Example 59] A radiation-sensitive composition (J-59) was prepared by mixing 100 parts by mass of (A-12) as polymer (A), 5.0 parts by mass of (B-1) as first radiation-sensitive acid generator (B), 2.0 parts by mass of (C-6) as second radiation-sensitive acid generator (C), 1.0 part by mass of (D-7) as acid diffusion control agent (D), and 700 parts by mass of a mixed solvent of (E-1) / (E-4) as solvent (E), and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0332] [Examples 60-64, 131-134 and Comparative Examples 23-25] Radiation-sensitive compositions (J-60)-(J-64), (J-131)-(J-134), and (CJ-23)-(CJ-25) were prepared in the same manner as in Example 59, except that the types and amounts of each component shown in Table 8 below were used.

[0333]

[0334] <Formation of a resist pattern using a positive-type radiation-sensitive composition for KrF exposure> The prepared positive-type radiation-sensitive composition for KrF exposure was applied to a 12-inch silicon wafer treated with hexamethyldisilazane using a spin coater (CLEAN TRACK ACT8 from Tokyo Electron Limited), and pre-bake (PB) was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 600 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using a KrF excimer laser scanner (PAS5500 / 850C wavelength 248 nm from ASML) under optical conditions of NA = 0.68 and σ = 0.60, through a 250 nm line-and-space mask pattern. After exposure, post-exposure bake (PEB) was performed at 130°C for 60 seconds. Subsequently, the resist film was alkaline-developed using a 2.38% by mass aqueous solution of TMAH as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (250 nm line, 350 nm pitch).

[0335] <Evaluation> The resist patterns formed using the above-mentioned positive-type radiation-sensitive composition for KrF exposure were evaluated for sensitivity, depth of field, pattern rectangularity, storage stability after exposure, and number of development defects according to the following method. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns. The results are shown in Table 9 below.

[0336] [Sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive composition for KrF exposure, the exposure amount used to form the 250 nm line and 350 nm pitch is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２The sensitivity was set to 50 mJ / cm². ２ The following conditions are considered "good" and 50 mJ / cm². ２ If it exceeded this value, it was rated as "poor."

[0337] [Depth of Focus] In the resist pattern resolved at the optimal exposure amount determined in the sensitivity evaluation above, the dimensions were observed when the focus was changed in the depth direction. The margin in the depth direction where the pattern dimensions fall within 90% to 110% of the standard without bridging or residue was measured, and this measured value was defined as the depth of focus (nm). A larger depth of focus indicates a better result. A depth of focus of 200 nm or more is evaluated as "good," and a depth of focus of less than 200 nm is evaluated as "poor."

[0338] [Storage Stability After Exposure (PED Storage Stability)] The optimal exposure amount determined in the sensitivity evaluation above was applied, and PEB was performed at 100°C for 60 seconds. After that, the material was stored at room temperature for 12 hours before proceeding with the development process. After storage, the resist film was alkaline developed, washed with water after development, and then dried to form a positive-type resist pattern, and the line width was measured. The line width L in the normal development process is expressed by the following formula. ０ Line width L after 12 hours of storage at room temperature following PEB １２ If the rate of change was between 0% and 5.0%, it was evaluated as "A" (excellent); if it was between 5.0% and 7.5%, it was evaluated as "B" (good); and if it was above 7.5%, it was evaluated as "C" (poor). Rate of change of line width (%) = |(L １２ -L ０ ) / L ０ | × 100

[0339] [Development Defect Count] A resist film was exposed at the optimal exposure level to form a resist pattern with 250 nm lines and a 350 nm pitch, and this was used as a wafer for defect inspection. The number of defects on this wafer was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Defects with a diameter of 5 μm or less were judged to be originating from the resist film, and their number was calculated. After development, the defect count was evaluated as "good" if the number of defects judged to be originating from the resist film was 150 or less, and as "poor" if it exceeded 150.

[0340]

[0341] As is clear from the results in Table 9, the radiation-sensitive composition of the example showed good sensitivity, depth of field, storage stability before and after exposure, and development defects when used in KrF exposure, whereas the comparative example failed to satisfy all of these characteristics. Therefore, when the radiation-sensitive composition of the example is used in KrF exposure, it is possible to form a resist pattern with optimal sensitivity, excellent margins, and superior defect suppression.

[0342] [Preparation of positive-type radiation-sensitive composition for extreme ultraviolet (EUV) exposure] [Example 65] A radiation-sensitive composition (J-65) was prepared by mixing 100 parts by mass of (A-12) as a polymer, 2.0 parts by mass (solids) of (F-5) as a high-fluorine-content polymer, 40.0 parts by mass of (B-15) as a first radiation-sensitive acid generator, 40.0 parts by mass of (C-11) as a second radiation-sensitive acid generator, 30.0 parts by mass of (D-2) as an acid diffusion control agent, and 6,200 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-6) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0343] [Examples 66-72, 141-144 and Comparative Examples 26-29] Radiation-sensitive compositions (J-66)-(J-72), (J-141)-(J-144), and (CJ-26)-(CJ-29) were prepared in the same manner as in Example 65, except that the components of the types and amounts shown in Table 10 below were used.

[0344]

[0345] <Formation of a resist pattern using a positive-type radiation-sensitive composition for EUV exposure> An anti-reflective underlayer film (ARC66 from Brewer Sciences) was applied to a 12-inch silicon wafer using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form an anti-reflective underlayer film with an average thickness of 105 nm. The prepared positive-type radiation-sensitive composition for EUV exposure was applied to this anti-reflective underlayer film using the spin coater, and PB (plate blot) was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed using an EUV lithography system (ASML's "NXE3300") with NA = 0.33, illumination conditions: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer, washed with water after development, and then dried to form a positive-type resist pattern (25 nm line and space pattern).

[0346] <Evaluation> The sensitivity, LWR performance, and storage stability after exposure were evaluated for the resist patterns formed using the above-mentioned positive-type radiation-sensitive composition for EUV exposure according to the following method. The results are shown in Table 11 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0347] [Sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive composition for EUV exposure, the exposure amount used to form a 25 nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity was set to 40 mJ / cm². ２ In the following cases, it is considered "good" and 40 mJ / cm². ２ If it exceeded this value, it was rated as "poor."

[0348] [LWR Performance] A resist pattern was formed by adjusting the mask size to create a 25 nm line-and-space pattern using the optimal exposure amount determined in the sensitivity evaluation above. The formed resist pattern was observed from the top using the scanning electron microscope described above. Line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line jaggedness and better performance. LWR performance was evaluated as "good" if it was 4.0 nm or less, and "poor" if it was greater than 4.0 nm.

[0349] [Storage Stability After Exposure (PED Storage Stability)] The optimal exposure amount determined in the sensitivity evaluation above was applied, and PEB was performed at 100°C for 60 seconds. After that, the material was stored at room temperature for 12 hours before proceeding with the development process. After storage, the resist film was alkaline developed, washed with water after development, and then dried to form a positive-type resist pattern, and the line width was measured. The line width L in the normal development process is expressed by the following formula. ０ Line width L after 12 hours of storage at room temperature following PEB １２ If the rate of change was between 0% and 5.0%, it was evaluated as "A" (excellent); if it was between 5.0% and 7.5%, it was evaluated as "B" (good); and if it was above 7.5%, it was evaluated as "C" (poor). Rate of change of line width (%) = |(L １２ -L ０ ) / L ０ | × 100

[0350]

[0351] As is clear from the results in Table 11, the radiation-sensitive composition of the example exhibited good sensitivity, LWR performance, and post-exposure storage stability when used in EUV exposure, whereas the comparative example failed to satisfy all of these characteristics. Therefore, when the radiation-sensitive composition of the example is used in EUV exposure, it is possible to form a resist pattern with optimal sensitivity, good LWR performance, and good storage stability.

[0352] [Preparation of a negative-type radiation-sensitive composition for ArF exposure, formation and evaluation of a resist pattern using this composition] [Example 73] A radiation-sensitive composition (J-73) was prepared by mixing 100 parts by mass of (A-8) as a polymer, 3.0 parts by mass (solids) of (F-3) as a high-fluorine-content polymer, 8.0 parts by mass of (B-5) as a first radiation-sensitive acid generator, 4.0 parts by mass of (C-5) as a second radiation-sensitive acid generator, 10.0 parts by mass of (D-2) as an acid diffusion control agent, and 3,230 parts by mass of a mixed solvent of (E-1) / (E-5) / (E-3) (2240 / 960 / 30 parts by mass) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0353] On a 12-inch silicon wafer, a base layer anti-reflective coating composition ("ARC66" from Brewer Science) was applied using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF exposure negative-type radiation-sensitive composition (J-73) prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA = 1.35 and Annular (σ = 0.8 / 0.6) through a mask pattern with 50 nm holes and a 100 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (a contact hole pattern with 50 nm holes and a 100 nm pitch).

[0354] The sensitivity and CDU of the resist pattern using the above-mentioned ArF exposure negative-type radiation-sensitive composition were evaluated in the same manner as the evaluation of the resist pattern using the above-mentioned ArF immersion exposure positive-type radiation-sensitive composition.

[0355] The radiation-sensitive compositions of the examples showed good sensitivity and CDU performance even when a negative-type resist pattern was formed by ArF exposure.

[0356] [Preparation of a negative-type radiation-sensitive composition for KrF exposure, formation and evaluation of a resist pattern using this composition] [Example 74] A radiation-sensitive composition (J-74) was prepared by mixing 100 parts by mass of (A-16) as a polymer, 2.0 parts by mass of (B-2) as a first radiation-sensitive acid generator, 6.0 parts by mass of (C-9) as a second radiation-sensitive acid generator, 1.0 part by mass of (D-6) as an acid diffusion control agent, 6.0 parts by mass of (C-9) as a second radiation-sensitive acid generator, 5.0 parts by mass of (Q-1) as a crosslinking agent, and 300 parts by mass of a mixed solvent of (E-1) / (E-5) (200 / 100 parts by mass) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0357] <Formation of a resist pattern using a negative-type radiation-sensitive composition for KrF exposure> The prepared negative-type radiation-sensitive composition for KrF exposure (J-74) was applied to a 12-inch silicon wafer treated with hexamethyldisilazane using a spin coater (CLEAN TRACK ACT8 from Tokyo Electron Limited), and pre-bake (PB) was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 3.0 μm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using a KrF excimer laser scanner (PAS5500 / 850C wavelength 248 nm from ASML) under optical conditions of NA = 0.68 and σ = 0.60, through a mask pattern with 500 nm holes and a 1000 nm pitch. After exposure, post-exposure bake (PEB) was performed at 130°C for 60 seconds. Subsequently, the resist film was alkaline-developed using a 2.38% by mass aqueous solution of TMAH as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (500 nm holes, 1000 nm pitch).

[0358] The sensitivity and depth of field of the resist pattern using the above-mentioned negative-type radiation-sensitive composition for KrF exposure were evaluated in the same manner as the evaluation of the resist pattern using the above-mentioned positive-type radiation-sensitive composition for KrF immersion exposure.

[0359] The radiation-sensitive compositions of the examples showed good sensitivity and depth of field even when a negative-type resist pattern was formed by KrF exposure.

[0360] The radiation-sensitive composition and resist pattern formation method described above can form resist patterns that are excellent in sensitivity, CDU, LWR, pattern rectangularity, etching resistance, exposure margin (EL), depth of field (DOF), storage stability before and after exposure, and suppression of development defects. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

A primary radiation-sensitive acid generator that generates an acid represented by the following formula (1) by irradiation with radiation, A second-stage radioactive acid generator (which differs from the first-stage radioactive acid generator mentioned above) generates an acid represented by the following formula (2) upon irradiation with radiation, A polymer containing at least one structural unit, Solvent and A radiation-sensitive composition containing [a certain substance]. (In formula (1), W ａ This is a monovalent aliphatic group A consisting of a carbon atom and a hydrogen atom, a monovalent aliphatic group B consisting of at least one atom selected from the group consisting of an oxygen atom, a halogen atom, and a sulfur atom, and a carbon atom and a hydrogen atom, or a substituted or unsubstituted monovalent monocyclic aromatic group. However, W ａ The number of oxygen atoms in this is three or less. L １ This is a divalent group represented by the following formulas (i), (ii), (iii), or (iv). (In formulas (i) to (iv), R ２１ and R ２２ each independently represent a hydrogen atom or a methyl group. When there are multiple R ２１ and R ２２ , the multiple R ２１ and R ２２ may each be the same or different from each other. 　　 m1 is an integer between 0 and 2. m² is an integer between 0 and 5. * represents W in the above formula (1). ａ This is a combination of . ** is R in equation (1) above. １ This is the bonding site with the carbon atom to which it is bonded. R １ These are monovalent hydrocarbon groups having 1 to 20 carbon atoms, -F, -CF ２ H, -SO ２ -R １１ , or -CN. R １１ (This refers to a monovalent hydrocarbon group having 1 to 20 carbon atoms.) (In formula (2), W ｂ It is a monovalent organic group having 1 to 40 carbon atoms. L ２ It is a single bond or a divalent linking group. R ｆ１ and R ｆ２ Each of these is independently a fluorine atom, a fluorinated hydrocarbon group, a cyano group, or a hydrogen atom. 　 n is an integer between 0 and 8. 　 In the above formula (1), W ａ The radiation-sensitive composition according to claim 1, wherein the number of carbon atoms in is 3 or more. 　 In the above formula (1), W ａ The radiation-sensitive composition according to claim 1, wherein the monovalent aliphatic group A or aliphatic group B has a chain-like structure. 　 In the above formula (1), W ａ The radiation-sensitive composition according to claim 1, wherein is the monovalent aliphatic group A or aliphatic group B. 　 In the above formulas (i) to (iv), R ２１ and R ２２ The radiation-sensitive composition according to claim 1, wherein is a hydrogen atom. 　 In the above formula (1), L １ The radiation-sensitive composition according to claim 1, wherein is a divalent group represented by formula (i) or formula (ii) above. 　 In the above formula (1), R １ -CN, -SO ２ -R １１ａ or an alkyl group having 1 to 5 carbon atoms, R １１ａ The radiation-sensitive composition according to any one of claims 1 to 6, wherein is an alkyl group having 1 to 5 carbon atoms. 　 The radiation-sensitive composition according to any one of claims 1 to 6, wherein the content of the above-mentioned first radiation-sensitive acid generator is 0.1 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the above-mentioned polymer. 　 In the above formula (2), W ｂ A radiation-sensitive composition according to any one of claims 1 to 6, wherein the composition comprises a ring structure. 　 The radiation-sensitive composition according to any one of claims 1 to 6, wherein the content of the above-mentioned second radiation-sensitive acid generator is 0.1 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the above-mentioned polymer. 　 The above polymer contains three or more structural units having different structures from each other. The radiation-sensitive composition according to any one of claims 1 to 6, wherein each of the three or more structural units described above independently has an acid-dissociable group, a lactone structure, a cyclic carbonate structure, or a sultone structure. 　 The radiation-sensitive composition according to any one of claims 1 to 6, wherein the polymer further comprises a structural unit having a phenolic hydroxyl group. 　 A step of forming a resist film by directly or indirectly applying the radiation-sensitive composition according to any one of claims 1 to 6 to a substrate, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. A pattern formation method including the following. 　 The pattern formation method according to claim 13, wherein the above exposure is performed using a KrF excimer laser, an ArF excimer laser, or extreme ultraviolet light. 　 Compounds represented by the following formulas (1-3). (In formula (1-3), W ａ１ This is a monovalent aliphatic group A1 having three carbon atoms consisting of a carbon atom and a hydrogen atom, a monovalent aliphatic group B1 consisting of at least one atom selected from the group consisting of an oxygen atom, a halogen atom, and a sulfur atom, and a carbon atom and a hydrogen atom, or a substituted or unsubstituted monovalent monocyclic aromatic group C1. However, W ａ１ The following requirements (a) and (b) are met: (a) W ａ１ The number of oxygen atoms in is 3 or less; and (b) L １ If is a divalent group represented by the following formula (i), then W ａ１ The monovalent aliphatic group B1 in the above-mentioned product has a chain-like structure. L １ This is a divalent group represented by the following formulas (i), (ii), (iii), or (iv). (In formulas (i) to (iv), R ２１ and R ２２ Each of these is independently either a hydrogen atom or a methyl group. ２１ and R ２２ If multiple R ２１ and R ２２ They are either identical or different from one another. 　　 m1 is an integer between 0 and 2. m² is an integer between 0 and 5. * represents W in the above formula (1-3). ａ１ This is a combination of . ** is R in equation (1-3) above. １ This is the bonding site with the carbon atom to which it is bonded. R １ These are monovalent hydrocarbon groups having 1 to 20 carbon atoms, -F, -CF ２ H, -SO ２ -R １１ , or -CN. R １１ It is a monovalent hydrocarbon group having 1 to 20 carbon atoms. M ＋ (This is an organic cation.) In the above formulas (1-3), M ＋ The compound according to claim 15, wherein is a sulfonium cation or an iodonium cation. 　 In the above formulas (1-3), W ａ１ A1 is a monovalent aliphatic group having 3 carbon atoms, consisting of a carbon atom and a hydrogen atom, or a substituted or unsubstituted monovalent monocyclic aromatic group C1, provided that W ａ１ The compound according to claim 15, wherein the number of oxygen atoms in is three or less. 　 In the above formulas (1-3), M ＋ The compound according to claim 15, which is represented by the following formula (1-1-C). (In formula (1-1-C), Ar １ This is a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group. R ｐ１ R is a substituted or unsubstituted phenyl group, ｐ２ is either an alkyl group or R ｐ１ and R ｐ２ They are combined with each other and they join together S ＋ (Together, they form a ring structure.)

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