Photosensitive compound, photosensitive composition, and method for forming pattern

Abstract

To provide a high-sensitivity and high-resolution photosensitive compound corresponding to a demand for miniaturization of a circuit pattern, and a photosensitive composition.SOLUTION: A photosensitive compound is constituted by a heteropoly acid anion, a photoreactive cation expressed by the following formula (1), and a hydrogen cation. A photosensitive composition includes the photosensitive compound. In the formula (1), R1 and R2 are, each independently, a 1-10C linear saturated aliphatic hydrocarbon group, a 2-10C linear unsaturated aliphatic hydrocarbon group, or a 3-10C aromatic group, which may have a substituent, Q is a saturated aliphatic hydrocarbon chain or an aromatic chain, which may have a substituent, and G is a substituent having a univalent cation.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a photosensitive compound and a photosensitive composition suitable for use in ultra-microlithography processes such as the manufacture of ultra-LSIs and high-capacity microchips, and other photofabrication processes, and a pattern formation method using the photosensitive composition. More specifically, the present invention relates to a photosensitive compound and a photosensitive composition suitable for use in the microfabrication of semiconductor elements using electron beams, X-rays, and EUV light (wavelength: about 13 nm), and a pattern formation method using the photosensitive composition. [Background technology]

[0002] Conventionally, in the manufacturing process of semiconductor devices such as ICs and LSIs, microfabrication is carried out by lithography using a photoresist composition. In semiconductor photolithography technology, in accordance with Moore's Law, as semiconductor devices become finer, circuit patterns become smaller, and further miniaturization is desired. Photolithography is roughly divided into the shortening of wavelengths of the light source of the exposure tool and the photoresist that reacts to it. Photoresists are required to meet all of the requirements of high resolution, low roughness, and high sensitivity, and it is thought that conventional resists that contain photoacid generators, known as chemically amplified resists, cannot handle ultra-fine patterns because the diffusion of acid leads to a decrease in resolution.

[0003] In recent years, non-chemically amplified photoresists based on compounds containing metal elements such as Zn and Sn have been proposed, and it has been reported that they can be used to form fine patterns using next-generation exposure equipment that uses EUV (extreme ultraviolet) light.

[0004] Regarding chemically amplified photoresists, it has been known that those containing polyoxoacid and a polymer function as chemically amplified resists (Patent Documents 1 and 2). It has also been reported that a polyoxoacid having an acrylic substituent on the polymer can be synthesized and polymerized to function as a resist (Non-Patent Document 1).

[0005] Incidentally, an example in which a heteropolyacid is used as a negative photoresist is reported in Patent Document 3. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Pat. No. 5,178,989 [Patent Document 2] International Publication No. 2016 / 190261 [Patent Document 3] International Publication No. 2007 / 148566 [Non-patent literature]

[0007] [Non-Patent Document 1] Vishwanath Kalyani et al.Chem.Eur.J.2015,21,2250-2258 http: / / dx.doi.org / 10.1002 / chem.201405369. Summary of the Invention [Problem to be solved by the invention]

[0008] In photolithography, particularly in semiconductor photolithography, there is a demand for photosensitive compositions and pattern forming methods that can realize even finer circuit patterns.

[0009] The present invention has been made in view of the above-mentioned conventional techniques, and has an object to provide a photosensitive compound and photosensitive composition having high sensitivity and high resolution in response to the demand for finer circuit patterns, and a pattern forming method using the photosensitive composition. [Means for solving the problem]

[0010] As a result of intensive research, the inventors have found that a heteropolyacid containing a cation with a specific photoreactive substituent as a photosensitive compound functions well as a photoresist suitable for ultrafine patterns. Specifically, as a result of an electron beam (EB) drawing test, a fine pattern of hp 50 nm L&S (1:1) could be formed, and a photoresist with very little roughness was realized. The present invention has been achieved based on these findings, and is summarized as follows: In the text, "~" means "greater than or equal to" or "less than or equal to." For example, "110~500" in [2] means "greater than or equal to 110 and less than or equal to 500."

[0011] [1] A photosensitive compound comprising a heteropolyacid anion, a photoreactive cation represented by the following formula (1), and a hydrogen cation:

[0012] [ka]

[0013] (In the above formula (1), R 1 and R 2 are each independently a chain saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms, a chain unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms, or an aromatic group having 3 to 10 carbon atoms, each of which may have a substituent; Q is a saturated aliphatic hydrocarbon chain or an aromatic chain, each of which may have a substituent; and G is a substituent having a monovalent cation.

[0014] [2] The photosensitive compound according to [1], which has a molecular weight of 110 to 500.

[0015] [3] The photosensitive compound according to [1] or [2], wherein the heteropolyacid anion is one or more anions selected from the group consisting of phosphotungstate anion, silicotungstate anion, phosphomolybdate anion, phosphotungstomolybdate anion, and phosphovanadomolybdate anion.

[0016] [4] R in the above formula (1)1 and R 2 each independently represents a chain saturated aliphatic hydrocarbon group having a secondary or tertiary carbon atom adjacent to the nitrogen atom in formula (1).

[0017] [5] The photosensitive compound according to any one of [1] to [4], wherein Q in the formula (1) is a phenylene group which may have a substituent.

[0018] [6] The photosensitive compound according to any one of [1] to [5], wherein G in the formula (1) is an ammonium cation, a sulfonyl cation or a phosphonium cation.

[0019] [7] A photosensitive composition comprising the photosensitive compound according to any one of [1] to [6].

[0020] [8] A photosensitive composition comprising the photosensitive compound according to any one of [1] to [6] and a photoacid generator which generates an acid by the action of actinic radiation.

[0021] [9] The photosensitive composition according to [7] or [8], which is for use in exposure to actinic radiation having a wavelength of 6.5 to 13.5 nm.

[0022]

[10] A pattern formation method comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive composition according to any one of [7] to [9]; irradiating predetermined regions of the photosensitive layer with actinic radiation to perform pattern exposure; and developing the exposed photosensitive layer with a developer to selectively remove exposed or unexposed regions of the photosensitive layer.

[0023]

[11] The pattern formation method according to

[10] , wherein the developer is an organic solvent having a solubility parameter (SP value) of 7.5 to 11. Effect of the Invention

[0024] The photosensitive compound and photosensitive composition of the present invention have high sensitivity and high resolution, and can simultaneously satisfy high sensitivity, high resolution, good pattern shape and reproducibility thereof, and good line width roughness in an ultrafine region. Here, line width roughness refers to the phenomenon in which the edge of the resist pattern and the substrate interface fluctuates irregularly in the direction perpendicular to the line direction due to the characteristics of the resist, so that the edge appears uneven when the pattern is viewed from directly above. This unevenness is transferred during the etching process using the resist as a mask, degrading the electrical characteristics and reducing the yield. According to the pattern forming method of the present invention using such a photosensitive composition of the present invention, it becomes possible to fully meet the recent demand for finer circuit patterns. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, the embodiments of the present invention will be described in detail, however, the present invention is not limited to the following embodiments and can be practiced in various modified forms within the scope of the gist of the present invention.

[0026] [Photosensitive compound] The photosensitive compound of the present invention is characterized in that it is composed of a heteropolyacid anion, a photoreactive cation represented by the following formula (1) (hereinafter sometimes referred to as "photoreactive cation (1)"), and a hydrogen cation.

[0027] [ka]

[0028] (In the above formula (1), R 1 and R 2 are each independently a chain saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms, a chain unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms, or an aromatic group having 3 to 10 carbon atoms, each of which may have a substituent; Q is a saturated aliphatic hydrocarbon chain or an aromatic chain, each of which may have a substituent; and G is a substituent having a monovalent cation.

[0029] [mechanism] The photosensitive compound of the present invention functions as a non-chemically amplified low molecular weight resist by decomposing the photoreactive cation represented by the above formula (1) after exposure. The photosensitive compound of the present invention has a small molecular size, which is believed to enable finer pattern formation.

[0030] [Heteropolyacid anion] The heteropoly acid anion according to the present invention is not particularly limited as long as it is a small nanostructure having a diameter of 2 nm or less and has high durability against dry etching gas by containing a metal element, and examples thereof include phosphotungstate anion, silicotungstate anion, phosphomolybdate anion, phosphotungstomolybdate anion, and phosphovanadomolybdate anion. Among these, phosphotungstate anion, silicotungstate anion, phosphomolybdate anion, phosphotungstomolybdate anion, and phosphovanadomolybdate anion are preferred because they are easy to synthesize and inexpensive, and silicotungstate anion is more preferred. The photosensitive compound of the present invention may contain only one type of these heteropolyacid anions, or may contain two or more types of them.

[0031] [Photoreactive cation (1)] The photoreactive cation (1) according to the present invention is represented by the following formula (1).

[0032] [ka]

[0033] (In the above formula (1), R 1 and R 2are each independently a chain saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms, a chain unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms, or an aromatic group having 3 to 10 carbon atoms, each of which may have a substituent; Q is a saturated aliphatic hydrocarbon chain or an aromatic chain, each of which may have a substituent; and G is a substituent having a monovalent cation.

[0034] <R 1 ,R 2 > R in formula (1) 1 ,R 2 The chain saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, more preferably a branched alkyl group, and specific examples thereof include a branched alkyl group such as an isopropyl group, an isobutyl group, a t-butyl group, and an isopentyl group.

[0035] R 1 ,R 2 The chain unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms is preferably a straight-chain or branched chain unsaturated aliphatic hydrocarbon group having 3 to 5 carbon atoms, more preferably a branched alkenyl group. Specific examples thereof include an isopropenyl group, an isobutenyl group, an isopentenyl group, and an isohexenyl group.

[0036] Also, R 1 ,R 2 The aromatic group having 3 to 10 carbon atoms may be an aromatic heterocyclic group or an aromatic hydrocarbon group. It may also be a monocyclic group or a condensed ring group. The aromatic heterocyclic group may be an aromatic heterocyclic group having 3 to 9 carbon atoms, specifically, a pyrrolyl group, a thiophenyl group, a furanyl group, a pyridinyl group, a pyrrolopyrrolyl group, a thienothiophenyl group, a cyclopentadithiophenyl group, an indolyl group, a benzothiadiazolyl group, a benzpyrrolyl group, etc. The aromatic hydrocarbon group may be an aromatic hydrocarbon group having 6 to 10 carbon atoms, specifically, a phenyl group, a naphthyl group, etc. These may have a substituent such as a methyl group or an ethyl group.

[0037] Of these, R1 ,R 2 are each independently a chain saturated aliphatic hydrocarbon group in which the carbon atom adjacent to the nitrogen atom in formula (1) is a secondary or tertiary carbon atom, from the viewpoint of enhancing the electron donating property of the nitrogen atom, facilitating the decomposition reaction between the carbonyl group and the nitrogen atom upon exposure, and enhancing the reaction sensitivity. Examples of such a chain saturated aliphatic hydrocarbon group include branched alkyl groups having 3 to 5 carbon atoms, and most preferably an isopropyl group.

[0038] These R 1 ,R 2 Examples of the substituent that the chain saturated aliphatic hydrocarbon group, the chain unsaturated aliphatic hydrocarbon group, or the aromatic group may have include those exemplified as the following group T of substituents. 1 ,R 2 The chain saturated aliphatic hydrocarbon group, the chain unsaturated aliphatic hydrocarbon group, or the aromatic group may have only one of these substituents, or may have two or more of the same or different substituents.

[0039] <Substituent group T> Examples of the substituent T include a hydroxy group, a nitro group, a carboxy group, an acyl group, an alkoxy group, an amino group, a sulfonyl group, a phosphonic acid group, and a halogen group such as fluorine, chlorine, or bromine. For an aromatic group, an alkyl group may further be mentioned as a substituent.

[0040] Among the above-mentioned substituent group T, R 1 ,R 2 The substituents which the chain-like saturated aliphatic hydrocarbon group, the chain-like unsaturated aliphatic hydrocarbon group or the aromatic group may have are preferably a hydroxy group, an alkoxy group, an amino group, a nitro group, a carboxy group, an acyl group, a sulfonyl group or a phosphonic acid group, more preferably an amino group, an alkoxy group or a hydroxy group. In the case of an aromatic group, an alkyl group is also preferred. However, from the viewpoint of ease of synthesis, R 1 ,R 2 It is preferred that the chain saturated aliphatic hydrocarbon group, the chain unsaturated aliphatic hydrocarbon group or the aromatic group does not have a substituent.

[0041] <q> The saturated aliphatic hydrocarbon chain of Q in formula (1) includes an alkylene group having 1 to 20 carbon atoms.

[0042] The aromatic group of Q may be an aromatic heterocyclic group or an aromatic hydrocarbon group. It may also be a group based on a single ring or a group based on a condensed ring. The aromatic heterocyclic group may be an aromatic heterocyclic group having 3 to 9 carbon atoms, specifically, a pyrrolylene group, a thiophenylene group, a furanylene group, a pyridinylene group, a pyrrolopyrrolylene group, etc. The aromatic hydrocarbon group may be an aromatic hydrocarbon group having 6 to 10 carbon atoms, specifically, a phenylene group, a naphthylene group, etc.

[0043] The substituent that the saturated aliphatic hydrocarbon chain or aromatic chain of Q may have includes those selected from the substituents T described above.

[0044] From the viewpoint of ease of synthesis, Q is preferably a phenylene group which may have a substituent such as an alkyl group, such as a methyl group, an ethyl group, or a propyl group, a hydroxyl group, a methoxy group, a nitro group, an amino group, a carboxyl group, or an ester group, and is most preferably a paraphenylene group.

[0045] <g> The substituent having a monovalent cation of G in formula (1) includes an ammonium cation, a sulfonyl cation, a phosphonium cation, etc., and from the viewpoint of ease of synthesis, a sulfonium cation is preferable, and from the viewpoint of ease of synthesis and ionicity, a dimethylsulfonyl cation is more preferable. The ionicity tends to be stronger when the organic group bonded to the sulfonium cation is smaller.

[0046] <Hydrogen cation> Hydrogen cation is H + The heteropolyacid anion, the photoreactive cation (1) and the hydrogen cation exist so that the charge of the photosensitive compound of the present invention is neutralized.

[0047] [Molecular weight] The molecular weight of the photosensitive compound of the present invention (the sum of the molecular weights of the heteropolyacid anion, the photoreactive cation (1), and the hydrogen cation) is preferably 1,000 to 5,000, more preferably 1,500 to 4,000, and even more preferably 2,500 to 4,000. When the molecular weight of the photosensitive compound of the present invention is equal to or less than the above upper limit, the volume is small, and therefore roughness and resolution are expected to be high. On the other hand, when the molecular weight is equal to or more than the above lower limit, the coating property and etching resistance tend to be improved. However, the molecular weight is only a guideline and does not determine the lithography properties by itself, so this is not limiting. Here, the molecular weight of the photosensitive compound of the present invention can be determined by, for example, electrospray ionization mass spectrometry (ESI-MS) to examine the molecular weight of each of the cation and the anion. However, in principle, ESI-MS cannot determine the sum of molecular weights, and can only determine the molecular weight and ion valence of a single anion and cation. Therefore, first, the molecular weight of a single anion and cation is determined by ESI-MS. Next, the valence of the anion is determined, and the coordination number of the cation is determined. Then, the molecular weight of the cation is integrated by the coordination number, and the result is added to the molecular weight of the anion, so that the sum of the molecular weights can be determined.

[0048] Specifically, the photosensitive compound of the present invention can be synthesized by the method described in the Examples section below.

[0049] [Photosensitive composition] [Photosensitive compound] The photosensitive composition of the present invention contains such a photosensitive compound of the present invention. The photosensitive composition of the present invention may contain only one type of the photosensitive compound of the present invention, or may contain two or more types of the photosensitive compound of the present invention.

[0050] The content of the photosensitive compound of the present invention in the photosensitive composition of the present invention is usually 30 to 100 mass %, preferably 40 to 100 mass %, and particularly preferably 50 to 100 mass %, based on the total of all components of the photosensitive composition other than the solvent. When the content of the photosensitive compound of the present invention in the photosensitive composition is equal to or higher than the above lower limit, good exposure sensitivity can be obtained.

[0051] [Photoacid generator] The photosensitive composition of the present invention can also function by containing, together with the photosensitive compound of the present invention, a photoacid generator that generates an acid by the action of actinic radiation. Examples of actinic radiation include the bright line spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light (EUV light), X-rays, and electron beams. From the viewpoint of resolution, it is preferable that the exposure wavelength is small, and EUV light that emits light with a wavelength of 6.5 to 13.5 nm is preferred.

[0052] Such a photoacid generator that generates an acid when exposed to chemical radiation is not particularly limited as long as it is a known compound, but is preferably a compound that generates an organic acid, such as at least one of sulfonic acid, bis(alkylsulfonyl)imide, and tris(alkylsulfonyl)methide, when exposed to chemical radiation. More preferred examples include compounds represented by the following formulae (ZI), (ZII) and (ZIII).

[0053] [ka]

[0054] In the above formula (ZI), R 201 , R 202 and R 203 each independently represents an organic group. R 201 , R 202 and R 203 The organic group as the substituent generally has 1 to 30 carbon atoms, and preferably 1 to 20 carbon atoms.

[0055] R 201 , R 202 and R 203 Examples of the organic group include an aryl group, an alkyl group, and a cycloalkyl group. R 201 , R 202 and R 203 The aryl group generally has 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms, and is more preferably a phenyl group or a naphthyl group, and even more preferably a phenyl group. The aryl group may be an aryl group having a heterocyclic structure containing an oxygen atom, a nitrogen atom, a sulfur atom, etc. Examples of the heterocyclic structure include pyrrole, furan, thiophene, indole, benzofuran, and benzothiophene.

[0056] R 201 , R 202 and R 203 The alkyl group and cycloalkyl group are preferably a linear or branched alkyl group having 1 to 10 carbon atoms and a cycloalkyl group having 3 to 10 carbon atoms. The alkyl group is more preferably a 2-oxoalkyl group and an alkoxycarbonylmethyl group. The cycloalkyl group is more preferably a 2-oxocycloalkyl group.

[0057] The 2-oxoalkyl group may be either linear or branched, and preferably includes the above alkyl groups having >C=O at the 2-position. A preferred 2-oxocycloalkyl group is the above cycloalkyl group having >C=O at the 2-position.

[0058] R 201 , R 202 and R 203 may be further substituted with a halogen atom, an alkoxy group (eg, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, a nitro group, or the like. Also, R 201 ~R 203 Two of these may be bonded to form a ring structure (preferably a 3- to 15-membered ring), and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. 201 ~R 203 Examples of the group formed by combining two of these include an alkylene group (eg, a butylene group, a pentylene group). Z - represents a non-nucleophilic anion (an anion that has a significantly reduced ability to undergo nucleophilic reactions).

[0059] Examples of non-nucleophilic anions include sulfonate anions (aliphatic sulfonate anions, aromatic sulfonate anions, camphorsulfonate anions, etc.), carboxylate anions (aliphatic carboxylate anions, aromatic carboxylate anions, aralkyl carboxylate anions, etc.), sulfonylimide anions, bis(alkylsulfonyl)imide anions, tris(alkylsulfonyl)methide anions, etc.

[0060] The aliphatic moiety in the aliphatic sulfonate anion and the aliphatic carboxylate anion may be an alkyl group or a cycloalkyl group, and preferred examples include linear or branched alkyl groups having 1 to 30 carbon atoms and cycloalkyl groups having 3 to 30 carbon atoms.

[0061] The aromatic group in the aromatic sulfonate anion and aromatic carboxylate anion is preferably an aryl group having 6 to 14 carbon atoms, such as a phenyl group, a tolyl group, or a naphthyl group.

[0062] The alkyl group, cycloalkyl group and aryl group in the aliphatic sulfonate anion and aromatic sulfonate anion may have a substituent. Specific examples of such groups include a nitro group, a halogen atom such as a fluorine atom, a carboxyl group, a hydroxyl group, an amino group, a cyano group, an alkoxy group (preferably having 1 to 15 carbon atoms), a cycloalkyl group (preferably having 3 to 15 carbon atoms), an aryl group (preferably having 6 to 14 carbon atoms), an alkoxycarbonyl group (preferably having 2 to 7 carbon atoms), an acyl group (preferably having 2 to 12 carbon atoms), an alkoxycarbonyloxy group (preferably having 2 to 7 carbon atoms), an alkylthio group (preferably having 1 to 15 carbon atoms), an alkylsulfonyl group (preferably having 1 to 15 carbon atoms), an alkyliminosulfonyl group (preferably having 2 to 15 carbon atoms), an aryloxysulfonyl group (preferably having 6 to 20 carbon atoms), an alkylaryloxysulfonyl group (preferably having 7 to 20 carbon atoms), a cycloalkylaryloxysulfonyl group (preferably having 10 to 20 carbon atoms), an alkyloxyalkyloxy group (preferably having 5 to 20 carbon atoms), and a cycloalkylalkyloxyalkyloxy group (preferably having 8 to 20 carbon atoms). The aryl group and ring structure of each group may further include an alkyl group (preferably having 1 to 15 carbon atoms) as a substituent.

[0063] The aralkyl group in the aralkyl carboxylate anion is preferably an aralkyl group having 6 to 12 carbon atoms, such as a benzyl group, a phenethyl group, a naphthylmethyl group, a naphthylethyl group, or a naphthylbutyl group.

[0064] An example of the sulfonylimide anion is a saccharin anion.

[0065] The alkyl group in the bis(alkylsulfonyl)imide anion and the tris(alkylsulfonyl)methide anion is preferably an alkyl group having a carbon number of 1 to 5. Examples of the substituent of these alkyl groups include a halogen atom, an alkyl group substituted with a halogen atom, an alkoxy group, an alkylthio group, an alkyloxysulfonyl group, an aryloxysulfonyl group, and a cycloalkylaryloxysulfonyl group, and a fluorine atom or an alkyl group substituted with a fluorine atom is preferred. In addition, the alkyl groups in the bis(alkylsulfonyl)imide anion may be bonded to each other to form a ring structure, which increases the acid strength.

[0066] Other non-nucleophilic anions include, for example, phosphorus fluorides (e.g., PF6 - ), boron fluorides (e.g. BF4 - ), antimony fluorides (e.g. SbF6 - ) etc.

[0067] As the non-nucleophilic anion, an aliphatic sulfonate anion in which at least the α-position of the sulfonic acid is substituted with a fluorine atom, an aromatic sulfonate anion in which a fluorine atom or a group having a fluorine atom is substituted, a bis(alkylsulfonyl)imide anion in which an alkyl group is substituted with a fluorine atom, and a tris(alkylsulfonyl)methide anion in which an alkyl group is substituted with a fluorine atom are preferred. As the non-nucleophilic anion, a perfluoroaliphatic sulfonate anion (more preferably having 4 to 8 carbon atoms), a benzenesulfonate anion having a fluorine atom, and even more preferably a nonafluorobutanesulfonate anion, a perfluorooctane sulfonate anion, a pentafluorobenzenesulfonate anion, and a 3,5-bis(trifluoromethyl)benzenesulfonate anion are more preferred.

[0068] From the viewpoint of acid strength, it is preferable for the pKa of the generated acid to be −1 or less in order to improve sensitivity.

[0069] As a preferred embodiment of the non-nucleophilic anion, there can be mentioned an anion represented by the following formula (AN1).

[0070] [ka]

[0071] In formula (AN1), each Xf independently represents a fluorine atom or an alkyl group substituted with at least one fluorine atom. R A , R B each independently represents a group selected from a hydrogen atom, a fluorine atom, and an alkyl group, A , R B may be the same or different. L represents a divalent linking group, and when a plurality of L's are present, they may be the same or different. A represents a group having a cyclic structure. x represents an integer of 1 to 20, y represents an integer of 0 to 10, and z represents an integer of 0 to 10.

[0072] Formula (AN1) will now be described in further detail. The alkyl group in the alkyl group substituted with a fluorine atom of Xf preferably has a carbon number of 1 to 10, more preferably a carbon number of 1 to 4. In addition, the alkyl group substituted with a fluorine atom of Xf is preferably a perfluoroalkyl group. Xf is preferably a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms. Specifically, Xf is a fluorine atom, CF3, C2F5, C3F7, C4F9, C5F 11 , C6F 13 , C7F 15 , C8F 17 , CH2CF3, CH2CH2CF3, CH2C2F5, CH2CH2C2F5, CH2C3F7, CH2CH2C3F7, CH2C4F9, and CH2CH2C4F9, among which a fluorine atom and CF3 are preferred. It is particularly preferred that both Xf are fluorine atoms.

[0073] R A , R B The alkyl group in R may have a substituent (preferably a fluorine atom) and is preferably one having 1 to 4 carbon atoms, more preferably a perfluoroalkyl group having 1 to 4 carbon atoms. A , R B Specific examples of the alkyl group having a substituent include CF3, C2F5, C3F7, C4F9, and C5F 11 , C6F 13 , C7F 15 , C8F 17 , CH2CF3, CH2CH2CF3, CH2C2F5, CH2CH2C2F5, CH2C3F7, CH2CH2C3F7, CH2C4F9, and CH2CH2C4F9, of which CF3 is preferred. R A , R B is preferably a fluorine atom or CF3. x is preferably an integer of 1 to 10, and more preferably an integer of 1 to 5. y is preferably 0 to 4, and more preferably 0. z is preferably an integer of 0 to 5, and more preferably an integer of 0 to 3. The divalent linking group of L is not particularly limited, and examples thereof include -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO2-, an alkylene group, a cycloalkylene group, an alkenylene group, or a linking group in which a plurality of these are linked together, and a linking group having a total carbon number of 12 or less is preferred. Among these, -COO-, -OCO-, -CO-, -O-, and -SO2- are preferred, and -COO-, -OCO-, and -SO2- are more preferred.

[0074] The group having a cyclic structure for A is not particularly limited as long as it has a cyclic structure, and examples thereof include an alicyclic group, an aryl group, and a group having a heterocyclic structure (including not only those having aromaticity but also those having no aromaticity). The alicyclic group may be monocyclic or polycyclic, and is preferably a monocyclic cycloalkyl group such as a cyclopentyl group, a cyclohexyl group, or a cyclooctyl group, or a polycyclic cycloalkyl group such as a norbornyl group, a tricyclodecanyl group, a tetracyclodecanyl group, a tetracyclododecanyl group, or an adamantyl group. Among them, an alicyclic group having a bulky structure with 7 or more carbon atoms, such as a norbornyl group, a tricyclodecanyl group, a tetracyclodecanyl group, a tetracyclododecanyl group, or an adamantyl group, is preferred from the viewpoint of suppressing in-film diffusibility in a post-exposure heating step and improving MEEF. The aryl group includes a benzene ring, a naphthalene ring, a phenanthrene ring, and an anthracene ring. Examples of the group having a heterocyclic structure include a furan ring, a thiophene ring, a benzofuran ring, a benzothiophene ring, a dibenzofuran ring, a dibenzothiophene ring, and a pyridine ring. Of these, a furan ring, a thiophene ring, and a pyridine ring are preferred. The group having a cyclic structure may have a substituent, and examples of the substituent include an alkyl group (which may be linear, branched, or cyclic, and preferably has 1 to 12 carbon atoms), an aryl group (which preferably has 6 to 14 carbon atoms), a hydroxy group, an alkoxy group (which preferably has 1 to 12 carbon atoms), a ureido group, a sulfonamide group (which preferably has 0 to 12 carbon atoms), or a group having an ester group, an amide group, a urethane group, a thioether group, or a sulfonate ester group (which preferably has 1 to 12 carbon atoms).

[0075] R 201 , R 202 and R 203 Among these, at least one is preferably an aryl group, and more preferably all three are aryl groups. The aryl group may be a phenyl group, a naphthyl group, or a heteroaryl group such as an indole residue or a pyrrole residue. These aryl groups may further have a substituent. Examples of the substituent include a nitro group, a halogen atom such as a fluorine atom, a carboxyl group, a hydroxyl group, an amino group, a cyano group, an alkoxy group (preferably having 1 to 15 carbon atoms), a cycloalkyl group (preferably having 3 to 15 carbon atoms), an aryl group (preferably having 6 to 14 carbon atoms), an alkoxycarbonyl group (preferably having 2 to 7 carbon atoms), an acyl group (preferably having 2 to 12 carbon atoms), and an alkoxycarbonyloxy group (preferably having 2 to 7 carbon atoms), but are not limited thereto.

[0076] Also, R 201 ~R 203 When two of these are bonded to form a ring structure, it is preferable that the ring structure be a structure represented by the following formula (A1).

[0077] [ka]

[0078] In formula (A1), R 1a ~R 13a each independently represents a hydrogen atom, a halogen atom, a nitro group, or an organic group. R 1a ~R 13a Among these, it is preferable that 1 to 3 are not hydrogen atoms, and R 9a ~R 13a It is more preferable that any one of these is not a hydrogen atom. Za is a single bond or a divalent linking group. X - is Z in formula (ZI). - is synonymous with.

[0079] R 1a ~R 13a Specific examples of when is not a hydrogen atom include a halogen atom, a nitro group, a linear, branched, or cyclic alkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a cyano group, a carboxyl group, an alkoxy group, an aryloxy group, a silyloxy group, a heterocyclic oxy group, an acyloxy group, a carbamoyloxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group (including an anilino group), an acylamino group, an aminocarbonylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, a sulfamoylamino group, an alkyl and arylsulfonylamino group, an alkylthio group, an arylthio group, a heterocyclic thio group, an alkyl and arylsulfinyl group, an alkyl and arylsulfonyl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, an aryl and heterocyclic azo group, a phosphinylamino group, a silyl group, a ureido group, and other known organic groups. R 1a ~R 13a When is not a hydrogen atom, it is preferably a linear, branched or cyclic alkyl group substituted with a hydroxyl group.

[0080] The divalent linking group of Za is an alkylene group, an arylene group, a carbonyl group, a sulfonyl group, a carbonyloxy group, a carbonylamino group, a sulfonylamido group, -O-, -S-, an amino group, a disulfide group, -(CH2) n -CO-, -(CH2) n Examples thereof include -SO2-, -CH=CH-, an aminocarbonylamino group, and an aminosulfonylamino group (n is an integer of 1 to 3).

[0081] In addition, R 201 , R 202 and R 203 Among these, preferred structures in which at least one is not an aryl group include cationic structures such as those exemplified as compounds represented by formulae (I-1) to (I-70) in JP-A No. 2003 / 0224288A1, paragraphs (0046) and (0047) of JP-A No. 2004-233661, and compounds represented by formulae (IA-1) to (IA-54) and (IB-1) to (IB-24) in JP-A No. 2003 / 0077540A1.

[0082] In formulas (ZII) and (ZIII), R 204 ~R 207 each independently represents an aryl group, an alkyl group, or a cycloalkyl group.

[0083] R 204 ~R 207 As the aryl group, alkyl group, and cycloalkyl group, R 201 ~R 203 The same applies to the aryl group, alkyl group, and cycloalkyl group in the above formula (1). R 204 ~R 207 The aryl group, alkyl group, and cycloalkyl group may have a substituent. The substituent may also be R 201 ~R 203 The aryl group, alkyl group and cycloalkyl group may have any of the above groups.

[0084] Z - represents a non-nucleophilic anion, and Z in formula (ZI) - Examples of the non-nucleophilic anions include those similar to those of the above.

[0085] Further examples of the photoacid generator include compounds represented by the following formulas (ZIV), (ZV) and (ZVI).

[0086] [ka]

[0087] In formulae (ZIV) to (ZVI), Ar3 and Ar4 each independently represent an aryl group. R 208 , R 209 and R 210 each independently represents an alkyl group, a cycloalkyl group, or an aryl group. A represents an alkylene group, an alkenylene group, or an arylene group.

[0088] Ar3, Ar4, R 208 , R 209 and R 210 Specific examples of the aryl group include R 201 , R 202 and R 203 Specific examples of the aryl group as mentioned above include the same as those mentioned above. R 208 , R 209 and R 210 Specific examples of the alkyl group and cycloalkyl group include R 201 , R 202 and R 203 Specific examples of the alkyl group and cycloalkyl group as mentioned above include the same as those mentioned above. Examples of the alkylene group of A include alkylene groups having 1 to 12 carbon atoms (e.g., a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, an isobutylene group, etc.), examples of the alkenylene group of A include alkenylene groups having 2 to 12 carbon atoms (e.g., an ethynylene group, a propenylene group, a butenylene group, etc.), and examples of the arylene group of A include arylene groups having 6 to 10 carbon atoms (e.g., a phenylene group, a tolylene group, a naphthylene group, etc.).

[0089] Among the photoacid generators, particularly preferred examples are given below.

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] The photoacid generator may be used alone or in combination of two or more. When two or more types are used in combination, for example, (1) two types of photoacid generators with different acid strengths are used in combination, or (2) two types of photoacid generators with different sizes (molecular weight or carbon number) of generated acid are used in combination, etc. are preferred. Examples of the embodiment of (1) include a combined use of a fluorine-containing sulfonic acid generator and a tris(fluoroalkylsulfonyl)methide acid generator, a combined use of a fluorine-containing sulfonic acid generator and a non-fluorine-containing sulfonic acid generator, and a combined use of an alkylsulfonic acid generator and an arylsulfonic acid generator. As an embodiment of (2), for example, two types of acid generators whose generated acid anions differ in the number of carbon atoms by 4 or more may be used in combination.

[0096] In particular, the photosensitive composition of the present invention is preferably a photosensitive composition for use with actinic radiation. If the photosensitive composition reacts with actinic radiation, the developing speed in a developer changes, and therefore a pattern can be formed after a certain period of development, which is preferable. As the actinic radiation, a shorter light wavelength is preferable since higher resolution can be obtained, and light with a wavelength of 6.5 to 13.5 nm, that is, EUV light, is preferable. That is, the photosensitive composition of the present invention is preferably a photosensitive composition that reacts with light having a wavelength of 6.5 to 13.5 nm.

[0097] In the photosensitive composition, the photosensitive compound of the present invention reacts with light even when used alone. When a photoacid generator is added, it acts synergistically with the photosensitive compound of the present invention in the photosensitive composition to enhance the photosensitivity of the photosensitive compound of the present invention. Therefore, when the photosensitivity of a photosensitive composition composed only of the photosensitive compound of the present invention is insufficient for the required specifications, it is preferable to add a photoacid generator. When the photosensitive composition of the present invention contains a photoacid generator, the content of the photoacid generator in the photosensitive composition of the present invention (the total amount when a plurality of photoacid generators are used in combination) is preferably 0.1 to 30 mass %, more preferably 0.5 to 20 mass %, and even more preferably 1 to 15 mass %, based on the total of the components other than the solvent in the photosensitive composition. When the content of the photoacid generator in the photosensitive composition is equal to or more than the above-mentioned lower limit, the effect of enhancing photosensitivity can be obtained, whereas when the content is equal to or less than the above-mentioned upper limit, the composition is less susceptible to the poor film-forming properties of the photoacid generator, and therefore good film-forming properties based on the photosensitive compound of the present invention can be obtained, which is preferable.

[0098] [solvent] The photosensitive composition of the present invention usually contains a solvent for preparing the composition. The solvent for preparing the photosensitive composition is not particularly limited as long as it dissolves each component, and examples thereof include alkylene glycol monoalkyl ether carboxylates (propylene glycol monomethyl ether acetate (PGMEA; 1-methoxy-2-acetoxypropane) and the like), alkylene glycol monoalkyl ethers (propylene glycol monomethyl ether (PGME; 1-methoxy-2-propanol) and the like), alkyl lactate esters (ethyl lactate, methyl lactate and the like), cyclic lactones (γ-butyrolactone and the like, preferably having 4 to 10 carbon atoms), linear or cyclic ketones (2-heptanone, cyclohexanone and the like, preferably having 4 to 10 carbon atoms), alkylene carbonates (ethylene carbonate, propylene carbonate and the like), alkyl carboxylates (butyl acetate and other alkyl acetates are preferred), and alkoxy alkyl acetates (ethyl ethoxypropionate). Other usable solvents include, for example, the solvents described in US Patent Application Publication No. 2008 / 0248425A1, starting from

[0244] .

[0099] Of the above, alkylene glycol monoalkyl ether carboxylates and alkylene glycol monoalkyl ethers are preferred.

[0100] These solvents may be used alone or in combination of two or more. When two or more are mixed, it is preferable to mix a solvent having a hydroxyl group with a solvent not having a hydroxyl group. As the solvent having a hydroxyl group, an alkylene glycol monoalkyl ether is preferred, and as the solvent not having a hydroxyl group, an alkylene glycol monoalkyl ether carboxylate is preferred.

[0101] The content of the solvent in the total amount of the photosensitive composition of the present invention can be appropriately adjusted depending on the thickness of the pattern film to be formed, etc., but is generally adjusted so that the total concentration of components other than the solvent in the photosensitive composition is 0.5 to 30 mass %, preferably 1.0 to 20 mass %, more preferably 1.5 to 10 mass %, and even more preferably 1.5 to 5 mass %.

[0102] [Surfactants] The photosensitive composition of the present invention preferably further contains a surfactant, preferably a fluorine-based and / or silicone-based surfactant. Examples of surfactants that fall into this category include Megafac F176 and Megafac R08 manufactured by Dainippon Ink and Chemicals, Inc., PF656 and PF6320 manufactured by OMNOVA, Troysol S-366 manufactured by Troy Chemical Co., Ltd., Fluorad FC430 manufactured by Sumitomo 3M Limited, and polysiloxane polymer KP-341 manufactured by Shin-Etsu Chemical Co., Ltd. Moreover, surfactants other than fluorine-based and / or silicon-based surfactants can also be used, more specifically, polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, etc.

[0103] Other known surfactants may be used as appropriate. Examples of usable surfactants include those described in U.S. Patent Application Publication No. 2008 / 0248425A1, paragraphs

[0273] and thereafter.

[0104] The surfactants may be used alone or in combination of two or more kinds. The content of the surfactant is preferably from 0.0001 to 2% by mass, and more preferably from 0.001 to 1% by mass, based on the total of all components other than the solvent in the photosensitive composition.

[0105] [Other additives] In addition to the components described above, the photosensitive composition of the present invention may contain, as appropriate, carboxylic acids, onium salts of carboxylic acids, dissolution inhibiting compounds having a molecular weight of 3,000 or less as described in, for example, Proceeding of SPIE, 2724, 355 (1996), dyes, plasticizers, photosensitizers, light absorbers, antioxidants, and the like. In particular, carboxylic acids are preferably used to improve performance. As the carboxylic acid, aromatic carboxylic acids such as benzoic acid and naphthoic acid are preferred. The content of the carboxylic acid is preferably from 0.01 to 10% by mass, more preferably from 0.01 to 5% by mass, and even more preferably from 0.01 to 3% by mass, based on the total of all components other than the solvent in the photosensitive composition.

[0106] [Method of producing photosensitive composition] The photosensitive composition of the present invention can be produced by dissolving the photosensitive compound of the present invention, a photoacid generator used as necessary, and other components in a solvent for preparation of the solution, and filtering the solution through a filter as necessary. The filter is preferably made of polytetrafluoroethylene, polyethylene, or nylon with a pore size of 0.1 microns or less, more preferably 0.05 microns or less, and even more preferably 0.03 microns or less. It is presumed that the photosensitive compound of the present invention contained in the photosensitive composition, when dissolved in a solvent for preparation, exists in the form of heteropolyacid anion, photoreactive cation (1) and hydrogen cation, respectively, as ions.

[0107] [Pattern Forming Method] The pattern formation method of the present invention includes the steps of forming a photosensitive layer on a substrate using the photosensitive composition of the present invention, irradiating predetermined regions of the photosensitive layer with actinic radiation to perform pattern exposure, and developing the exposed photosensitive layer with a developer to selectively remove exposed or unexposed regions of the photosensitive layer.

[0108] [Photosensitive layer formation process] The photosensitive layer can be formed by applying the photosensitive composition of the present invention onto a substrate (e.g., silicon, silicon dioxide coated) such as that used in the manufacture of integrated circuit elements by a suitable application method such as a spinner, and then drying at 50 to 150°C. In this case, if necessary, a commercially available inorganic or organic anti-reflective film can be used, and further, an anti-reflective film can be applied to the lower layer of the resist.

[0109] [Exposure process] In the present invention, unless otherwise specified, "exposure" includes not only exposure to far ultraviolet light such as mercury lamps and excimer lasers, X-rays, EUV light, and the like, but also drawing with particle beams such as electron beams and ion beams. The exposure can be carried out by irradiating the formed photosensitive layer with chemical radiation through a predetermined mask in a predetermined area to perform pattern exposure, or by irradiating the layer with an electron beam to perform pattern exposure by drawing (direct drawing) without using a mask. The actinic radiation is not particularly limited, but examples include KrF excimer laser, ArF excimer laser, EUV light, and electron beams, with EUV light and electron beams being preferred, and as described above, EUV light that emits light with a wavelength of 6.5 to 13.5 nm being preferred.

[0110] After the exposure, baking (heating) may or may not be performed before development. When baking (heating) is performed, the heating temperature is preferably 50 to 150°C, more preferably 60 to 150°C, and further preferably 80 to 140°C. When baking (heating) is performed, the heating time is preferably from 30 to 300 seconds, more preferably from 30 to 180 seconds, and even more preferably from 30 to 90 seconds. Heating can be carried out by a means provided in a normal exposure / developing machine, and may also be carried out using a hot plate or the like.

[0111] [Development process] After exposure, development is carried out using a developer to selectively remove the exposed or unexposed areas of the photosensitive layer.

[0112] <Developer> As the developer, an organic solvent is preferably used, preferably an organic solvent having a vapor pressure of 5 kPa or less, more preferably 3 kPa or less, and particularly preferably 2 kPa or less at 20° C. By making the vapor pressure of the organic solvent 5 kPa or less, evaporation of the developer on the substrate or in the developing cup is suppressed, improving the temperature uniformity within the surface of the pattern-formed substrate, and as a result, improving the dimensional uniformity within the surface of the pattern-formed substrate.

[0113] As the organic solvent used as the developer, various organic solvents are widely used. For example, at least one solvent selected from ester-based solvents, ketone-based solvents, alcohol-based solvents, amide-based solvents, ether-based solvents, hydrocarbon-based solvents, and the like can be used. In particular, the developer preferably contains at least one solvent selected from the group consisting of ketone-based solvents, ester-based solvents, alcohol-based solvents, and ether-based solvents.

[0114] Examples of ester-based solvents include alkyl carboxylate solvents such as methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, ethyl-3-ethoxypropionate, propylene glycol diacetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, and propyl lactate; alkylene glycol monoalkyl ether carboxylate solvents such as propylene glycol monomethyl ether acetate (PGMEA; also known as 1-methoxy-2-acetoxypropane), ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and propylene glycol monoethyl ether acetate; and more preferably, butyl acetate, amyl acetate, ethyl lactate, and propylene glycol monomethyl ether acetate.

[0115] Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl amyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetyl carbinol, acetophenone, methyl naphthyl ketone, isophorone, and propylene carbonate. Of these, alkyl ketone solvents, such as methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, and cyclohexanone, are more preferred.

[0116] Examples of the alcohol-based solvent include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, hexyl alcohols such as n-hexyl alcohol, heptyl alcohols such as n-heptyl alcohol, octyl alcohols such as n-octyl alcohol, and decanols such as n-decanol; glycol-based solvents such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, and 1,4-butylene glycol; and ethyl Examples of suitable solvents include alkylene glycol monoalkyl ether solvents such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether (PGME; also known as 1-methoxy-2-propanol), ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, and triethylene glycol monoethyl ether; glycol ether solvents such as methoxymethylbutanol and propylene glycol dimethyl ether; and phenol solvents such as phenol and cresol. Of these, 1-hexanol, 2-hexanol, 1-octanol, 2-ethyl-hexanol, propylene glycol monomethyl ether, and cresol are more preferred.

[0117] Examples of the amide solvent that can be used include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, hexamethylphosphoric triamide, and 1,3-dimethyl-2-imidazolidinone.

[0118] Examples of the ether solvent include the alkylene glycol monoalkyl ether solvents and glycol ether solvents described above, as well as dioxane, tetrahydrofuran, tetrahydropyran, and the like.

[0119] Examples of the hydrocarbon solvent include aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as pentane, hexane, octane, decane, and dodecane.

[0120] The developer preferably contains one or more solvents selected from alkylene glycol monoalkyl ether carboxylate solvents, alkylene glycol monoalkyl ether solvents, alkyl carboxylate solvents, and alkyl ketone solvents, and more preferably contains one or more solvents selected from propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, cyclohexanone, ethyl lactate, and butyl acetate.

[0121] The developer used is preferably one containing at least one organic solvent selected from the group consisting of ester solvents having no hydroxyl groups in the molecule, ketone solvents having no hydroxyl groups in the molecule, and ether solvents having no hydroxyl groups in the molecule.

[0122] The organic solvent used as the developer in the present invention is preferably an organic solvent having a solubility parameter (SP value) of 7.5 to 11. An organic solvent having a solubility parameter of 7.5 or more is preferred because it increases the development speed of the dissolved portion, while an organic solvent having a solubility parameter of 11 or less is preferred because it can suppress the development speed of the pattern forming portion. The solubility parameter of the organic solvent in the developer is more preferably 8 to 11.

[0123] In the present invention, the solubility parameter (SP value) is calculated by the method proposed by Fedors et al. Specifically, the value is determined by referring to "POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS. (pages 147-154)". The SP value is a physical property value determined by the content of hydrophobic and hydrophilic groups in the molecule, and when a mixed solvent is used, it means the value of the mixture.

[0124] Examples of organic solvents that satisfy the above SP values ​​include diethylene glycol monomethyl ether (SP value = 10.7), triethylene glycol monomethyl ether (SP value = 10.7), ethylene glycol monoisopropyl ether (SP value = 10.9), ethylene glycol monobutyl ether (SP value = 10.2), diethylene glycol monobutyl ether (SP value = 10.0), triethylene glycol monobutyl ether (SP value = 10.0), ethylene glycol monoisobutyl ether (SP value = 9.1), ethylene glycol monohexyl ether (SP value = 9.9), diethylene glycol monohexyl ether (SP value = 9.7), diethylene glycol mono 2-ethylhexyl ether (SP value = 9.3), ethylene glycol monoallyl ether (SP value = 10.8), ethylene glycol monophenyl ether (SP value = 10.8), ethylene glycol monobenzyl ether (SP value = 10.9), propylene glycol monomethyl ether (SP value = 10.0), di ... propylene glycol monomethyl ether (SP value = 9.7), tripropylene glycol monomethyl ether (SP value = 9.4), propylene glycol monopropyl ether (SP value = 9.6), dipropylene glycol monopropyl ether (SP value = 9.8), propylene glycol monobutyl ether (SP value = 9.0), dipropylene glycol monobutyl ether (SP value = 9.6), ethylene glycol monomethyl ether acetate (SP value = 10.0), ethylene glycol monoethyl ether acetate ether acetate (SP value = 9.6), ethylene glycol monobutyl ether acetate (SP value = 8.9), diethylene glycol monoethyl ether acetate (SP value = 9.4), diethylene glycol monobutyl ether acetate (SP value = 9.0), propylene glycol monomethyl ether acetate (SP value = 9.4), propylene glycol monoethyl ether acetate (SP value = 9.0), and dipropylene glycol monomethyl ether acetate (SP value = 9.2).

[0125] The organic solvents mentioned above may be used in combination, or may be used in combination with a solvent other than the above or with water.

[0126] The concentration of the organic solvent (total when a plurality of organic solvents are mixed) in the developer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. Particularly preferred is a developer that is essentially made up of an organic solvent. The developer that is essentially made up of an organic solvent includes a developer that contains a small amount of a surfactant, an antioxidant, a stabilizer, an antifoaming agent, etc.

[0127] The water content in the developer is preferably 10% by mass or less, more preferably 5% by mass or less, particularly preferably 3% by mass or less, and most preferably substantially free of water. By keeping the water content at 10% by mass or less, good development characteristics can be obtained.

[0128] If necessary, a suitable amount of a surfactant may be added to the developer used in the present invention. As the surfactant, the same surfactants as those described above for use in the photosensitive composition of the present invention can be used. The amount of the surfactant used is usually from 0.001 to 5% by mass, preferably from 0.005 to 2% by mass, and more preferably from 0.01 to 0.5% by mass, based on the total amount of the developer.

[0129] <Developing method> Development methods that can be applied include, for example, a method in which the substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which the developer is piled up on the substrate surface by surface tension and left to stand for a certain period of time (paddle method), a method in which the developer is sprayed onto the substrate surface (spray method), and a method in which the developer is continuously dispensed by scanning a developer dispensing nozzle at a constant speed over a substrate rotating at a constant speed (dynamic dispense method). After the development step, a step of stopping the development while replacing the solvent with another solvent may be carried out. The development time is preferably a time required for the compound (1) and the like in the unexposed or exposed portion of the photosensitive layer to be sufficiently dissolved, and is usually preferably from 10 to 300 seconds, more preferably from 20 to 120 seconds. The temperature of the developer is preferably from 0 to 50°C, and more preferably from 15 to 35°C. The amount of developer can be appropriately adjusted depending on the developing method.

[0130] [Rinse process] The pattern forming method of the present invention may include a step of washing with a rinsing liquid containing an organic solvent after the developing step.

[0131] <Rinse solution> The organic solvent used in the rinse liquid preferably has a vapor pressure of 0.05 kPa to 5 kPa, more preferably 0.1 kPa to 5 kPa, and most preferably 0.12 kPa to 3 kPa at 20° C. By setting the vapor pressure of the organic solvent used in the rinse liquid to 0.05 kPa to 5 kPa, the temperature uniformity within the wafer surface is improved, and further swelling caused by the penetration of the rinse liquid is suppressed, improving the dimensional uniformity within the wafer surface.

[0132] As the rinse solution, various organic solvents can be used. For compound (1), it is preferable to use a rinse solution containing at least one organic solvent selected from hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents, or water. More preferably, after development, a step of washing is performed using a rinse solution containing at least one organic solvent selected from the group consisting of ketone solvents, ester solvents, alcohol solvents, amide solvents, and hydrocarbon solvents. Even more preferably, after development, a step of washing is performed using a rinse solution containing at least one organic solvent selected from the group consisting of alcohol solvents and hydrocarbon solvents. Specific examples of the ketone-based solvent, ester-based solvent, alcohol-based solvent, amide-based solvent, ether-based solvent, and hydrocarbon-based solvent used as the rinsing liquid are the same as those described above for the developer. It is particularly preferable to use a rinse solution containing at least one organic solvent selected from the group consisting of monohydric alcohol solvents and hydrocarbon solvents.

[0133] Here, examples of the monohydric alcohol solvent used in the rinsing step after development include linear, branched and cyclic monohydric alcohols. Specifically, 1-butanol, 2-butanol, 3-methyl-1-butanol, tert-butyl alcohol, isopropyl alcohol, cyclopentanol, cyclohexanol and the like can be used, with 1-butanol, 2-butanol, 3-methyl-1-butanol and isopropyl alcohol being preferred. Examples of the hydrocarbon solvent include aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as octane, decane, and dodecane.

[0134] The above-mentioned components may be used in combination in plural numbers, or may be used in combination with an organic solvent other than those mentioned above.

[0135] The organic solvent may be mixed with water, but the water content in the rinse solution is usually 30% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. Most preferably, the rinse solution does not contain water. By making the water content 30% by mass or less, good development characteristics can be obtained.

[0136] The rinse solution may contain a suitable amount of a surfactant. As the surfactant, the same surfactants as those described above for use in the photosensitive composition can be used, and the amount of the surfactant used is usually 0.001 to 5 mass %, preferably 0.005 to 2 mass %, and more preferably 0.01 to 0.5 mass %, based on the total amount of the rinse solution.

[0137] <Rinse method> In the rinsing step, the developed pattern-formed substrate is washed with a rinsing liquid containing the organic solvent. The cleaning method is not particularly limited, but may be, for example, a method of continuously applying the rinse solution onto a substrate rotating at a constant speed (spin coating method), a method of immersing the substrate in a tank filled with the rinse solution for a certain period of time (dip method), or a method of spraying the rinse solution onto the substrate surface (spray method). Among these, it is preferable to perform the cleaning process by the spin coating method, rotate the substrate at a rotation speed of 2000 to 4000 rpm after cleaning, and remove the rinse solution from the substrate. The rotation time of the substrate can be set within a range that achieves removal of the rinse solution from the substrate depending on the rotation speed, but is usually 10 seconds to 3 minutes. It is preferable to perform rinsing at room temperature. The rinsing time is preferably set so that the developing solvent does not remain on the substrate, and is usually preferably from 10 to 300 seconds, more preferably from 20 to 120 seconds. The temperature of the rinse liquid is preferably from 0 to 50°C, and more preferably from 15 to 35°C. The amount of the rinse solution can be appropriately adjusted depending on the rinse method.

[0138] [Post-processing process] After the development treatment or rinsing treatment, a treatment can be carried out in which the developer or rinsing liquid adhering to the pattern is removed by using a supercritical fluid. Furthermore, after the development treatment, rinsing treatment, or treatment with a supercritical fluid, a heat treatment can be performed to remove the solvent remaining in the pattern. The heating temperature and time are not particularly limited as long as a good resist pattern can be obtained, and are usually 40 to 160°C and 10 seconds to 3 minutes. The heat treatment may be performed multiple times.

[0139] [Application] The photosensitive composition and the pattern forming method of the present invention are suitable for use in the production of semiconductor microcircuits, such as the manufacture of ultra-large scale integration (ULSI) and high-capacity microchips. During the production of semiconductor microcircuits, the resist film on which the pattern is formed is subjected to circuit formation and etching, and the remaining resist film portion is finally removed with a solvent or the like. Therefore, unlike so-called permanent resists used in printed circuit boards and the like, the resist film derived from the photosensitive composition of the present invention does not remain in the final product such as a microchip. EXAMPLES

[0140] The present invention will be described in more detail below with reference to examples, but the contents of the present invention are not limited thereto.

[0141] [Example 1] <Synthesis of photosensitive compound 1> Under a nitrogen atmosphere, phenol (100 g, 1062 mmol), DMSO (83.0 g), and methanol (750 ml) were placed in a reaction vessel and cooled to an internal temperature of 0° C. in a salt ice bath. After bubbling hydrogen chloride gas for 4 days, the mixture was concentrated under reduced pressure and azeotroped with acetone. The precipitated crystals were collected by filtration to obtain 58.84 g of intermediate 1-1 represented by the following structural formula.

[0142] [ka]

[0143] Next, in a nitrogen atmosphere, intermediate 1-1, NaCF3SO3 (12.65 g, 313.0 mmol), and acetone (410 ml) were placed in a reaction vessel and reacted at room temperature overnight. The precipitated salt was removed by filtration and the mixture was concentrated under reduced pressure to obtain 88.26 g of intermediate 1-2 represented by the following structural formula.

[0144] [ka]

[0145] Further, in a nitrogen atmosphere, intermediate 1-2, NaOH (12.16 g, 304 mol), and methanol (580 ml) were placed in a reaction vessel and stirred at room temperature for one hour. The mixture was cooled to an internal temperature of 0°C in a salt-ice bath, the precipitated salt was removed by filtration, and the mixture was concentrated under reduced pressure to obtain intermediate 1-3 (70.32 g, 215 mmol, yield 20.3%) represented by the following structural formula.

[0146] [ka]

[0147] Under a nitrogen atmosphere, intermediate 1-3 (3.26 g, 10.0 mmol) and acetonitrile (20.0 ml) were placed in a reaction vessel, and diisopropylcarbamyl chloride (1.96 g, 12.0 mmol) was added dropwise. The mixture was reacted at room temperature for 6 hours, and the precipitate was removed by filtration. The filtrate was concentrated under reduced pressure, and the mixture was crystallized and washed with diisopropyl ether to obtain intermediate 1-4 (3.54 g, 8.20 mmol, yield 82.0%) represented by the following structural formula.

[0148] [ka]

[0149] In a reaction vessel under a nitrogen atmosphere, H4[SiW 12 O 40 ] (2.77 g, 0.811 mmol) dissolved in purified water (18.5 ml) was added, and a solution of intermediate 1-4 (3.50 g, 8.11 mmol) in CH2Cl2 (18.5 ml) was added dropwise. The mixture was reacted at 20°C for 0.5 hours, and the precipitate was collected by filtration and dried under reduced pressure to obtain compound 1 (2.69 g) represented by the following structural formula. 1 H-NMR (400MHz, DMSO-d6): δ8.08-8.10 (2H, m, ArH), 7.47-7.50 (2H, m, ArH), 3.26 (6H, s, C H3), 3.18(2H, m, CH), 1.21(6H, d, CH3), ESI(+)-MS:282.15, ESI(-)-MS:1437.60(H2[SiW 12 O 40 ] 2- ).

[0150] [ka]

[0151] <Preparation of resist solution> The compound 1 synthesized as described above was dissolved in cyclohexanone to a concentration of 5% by mass, and filtered through a 0.2 μm filter to prepare resist solution 1.

[0152] <Sensitivity evaluation> A resist film was formed using the prepared resist solution 1, and patterning was performed. Specifically, the resist solution 1 was applied to a pattern formation substrate (silicon wafer) by spin coating to form a resist film with a thickness of about 50 nm. The resist film obtained was baked at 90°C for 90 seconds, and then a pattern was drawn using an electron beam lithography device (electron beam acceleration voltage: 100 keV). After the pattern was written, it was developed with cyclohexanone or ethyl lactate to obtain a negative pattern. The sensitivity was evaluated by changing the dose of electron beam writing, measuring the film thickness of the developed pattern with a contact step gauge, and determining the dose of electron beam irradiation when the increase in film thickness was maximum. The evaluation results are shown in Table 1.

[0153] <Evaluation of resolution> Next, the resolution of the resist solution 1 was evaluated using an electron beam lithography device. The resolution was evaluated by drawing a line and space (line:space=1:1) pattern with hp (half pitch) of 100 nm and hp of 50 nm, developing the pattern, and observing each pattern with a scanning electron microscope to evaluate the quality (good / bad) of the drawn pattern. The evaluation results are shown in Table 2.

[0154] [Comparative Example 1] <Synthesis of photosensitive compound 2> Under a nitrogen atmosphere, intermediate 1-3 (3.19 g, 9.73 mmol) from Example 1 and acetonitrile (20.0 ml) were placed in a reaction vessel, and methacrylic acid chloride (1.13 ml, 11.68 mmol) was added dropwise. The mixture was reacted at room temperature for 6 hours, and the precipitate was removed by filtration. The filtrate was concentrated under reduced pressure, and crystallized and washed with diisopropyl ether to obtain intermediate 2-1 (3.54 g, 8.20 mmol, yield 82.0%) represented by the following structural formula.

[0155] [ka]

[0156] In a reaction vessel under a nitrogen atmosphere, H4[SiW 12 O 40 ] (1.93 g, 0.56 mmol) dissolved in purified water (13.0 ml) was added, and a solution of intermediate 2-1 (2.10 g, 5.64 mmol) in CH2Cl2 (13.0 ml) was added dropwise. The mixture was reacted at 20°C for 0.5 hours, and the precipitate was collected by filtration and dried under reduced pressure to obtain compound 2 (2.60 g) represented by the following structural formula. 1 H-NMR (400MHz, DMSO-d6): δ8.14-8.16 (2H, m, ArH), 7.58-7.60 (2H, m, ArH), 6.33 (1H, d, CH2), 5.98 (1H, d, CH2), 3.27 (6H, s, CH3). 2.02(3H,s,CH3), ESI(+)-MS:223.08, ESI(-)-MS:1437.60(H2[SiW 12 O 40 ] 2- ).

[0157] [ka]

[0158] <Preparation and evaluation of resist solution> Resist solution 2 was prepared in the same manner as in Example 1, except that compound 2 was used instead of compound 1, and the sensitivity test was carried out in the same manner. The results are shown in Table 1.

[0159] [Comparative Example 2] <Synthesis of photosensitive compound 3> Under a nitrogen atmosphere, intermediate 1-3 (3.19 g, 9.73 mmol) from Example 1 and acetonitrile (20.0 ml) were placed in a reaction vessel, and nonanoyl chloride (2.20 ml, 11.68 mmol) was added dropwise. The mixture was reacted at room temperature for 6 hours, and the precipitate was removed by filtration. The filtrate was concentrated under reduced pressure, and crystallized and washed with diisopropyl ether to obtain intermediate 3-1 (3.20 g, 7.20 mmol, yield 74.0%) represented by the following structural formula.

[0160] [ka]

[0161] In a reaction vessel under a nitrogen atmosphere, H4[SiW 12 O 40 ] (2.46 g, 0.72 mmol) dissolved in purified water (16.4 ml) was added, and a solution of intermediate 3-1 (3.20 g, 7.20 mmol) in CH2Cl2 (16.4 ml) was added dropwise. The mixture was reacted at 20°C for 0.5 hours, and the precipitate was collected by filtration and dried under reduced pressure to obtain compound 3 (2.76 g) represented by the following structural formula. 1 H-NMR (400MHz, DMSO-d6): δ8.12-8.14(2H, m, ArH), 7.50-7.52(2H, m, ArH), 3.26(6H, s, CH3), 2.63(2H, t, CH 2), 1.66 (2H, m, CH2), 1.28 (10H, m, CH2), 0.88 (3H, t, CH3), ESI(+)-MS:295.17, ESI(-)-MS:1437.60(H2[SiW 12 O 40 ] 2- ).

[0162] [ka]

[0163] <Preparation and evaluation of resist solution> Resist solution 3 was prepared in the same manner as in Example 1, except that compound 3 was used instead of compound 1, and the sensitivity was evaluated in the same manner. The results are shown in Table 1.

[0164] [Comparative Example 3] Polyhydroxystyrene (PHS, weight average molecular weight 11000) manufactured by Aldrich was dissolved in propylene glycol monomethyl ether acetate at a concentration of 2% by mass, and the solution was filtered through a 0.2 μm filter to prepare resist solution 4.

[0165] [Comparative Example 4] Polystyrene (PS, weight average molecular weight 4000) manufactured by Aldrich was dissolved in propylene glycol monomethyl ether acetate at a concentration of 2% by mass, and the solution was filtered through a 0.2 μm filter to prepare resist solution 5. The sensitivity and resolution were evaluated in the same manner as in Example 1, except that Resist Solutions 4 and 5 were used instead of Resist Solution 1. The results are shown in Tables 1 and 2.

[0166] [Table 1]

[0167] From the results in Table 1 above, it can be seen that, compared with Comparative Examples 1 and 2, Example 1 using the photosensitive compound of the present invention has higher lithography sensitivity.

[0168] [Table 2]

[0169] As is clear from the results in Table 2 above, when the photosensitive composition of Example 1 using the photosensitive compound of the present invention was used, the resolution could be improved. For reference, considering the photoreaction mechanism of lithography resist, it can be easily inferred that the resolution is also high when exposed to EUV light (13.5 nm).

[0170] As described above, the photosensitive compound and photosensitive composition of the present invention are suitable for use in future EUV lithography. It is possible to form a resist pattern with reduced roughness even in the thin film. Its industrial value is enormous.< / g> < / q>

Claims

1. A photosensitive compound comprising a heteropolyacid anion, a photoreactive cation represented by the following formula (1), and a hydrogen cation: 【Chemistry 1】 (In the above formula (1), R １ and R ２ are each independently a chain saturated aliphatic hydrocarbon group having 1 to 10 carbon atoms, a chain unsaturated aliphatic hydrocarbon group having 2 to 10 carbon atoms, or an aromatic group having 3 to 10 carbon atoms, each of which may have a substituent; Q is a saturated aliphatic hydrocarbon chain or an aromatic chain, each of which may have a substituent; and G is a substituent having a monovalent cation.

2. 2. The photosensitive compound according to claim 1, which has a molecular weight of 110 to 500.

3. 3. The photosensitive compound according to claim 1, wherein the heteropolyacid anion is one or more anions selected from the group consisting of phosphotungstate anion, silicotungstate anion, phosphomolybdate anion, phosphotungstomolybdate anion, and phosphovanadomolybdate anion.

4. R in the formula (1) １ and R ２ each independently represents a chain saturated aliphatic hydrocarbon group having a secondary or tertiary carbon atom adjacent to the nitrogen atom in formula (1).

5. 5. The photosensitive compound according to claim 1, wherein Q in the formula (1) is a phenylene group which may have a substituent.

6. 6. The photosensitive compound according to claim 1, wherein G in the formula (1) is an ammonium cation, a sulfonyl cation, or a phosphonium cation.

7. A photosensitive composition comprising the photosensitive compound according to any one of claims 1 to 6.

8. 7. A photosensitive composition comprising the photosensitive compound according to claim 1 and a photoacid generator which generates an acid by the action of actinic radiation.

9. The photosensitive composition according to claim 7 or 8, which is for use with actinic radiation having a wavelength of 6.5 to 13.5 nm.

10. 10. A pattern forming method comprising the steps of: forming a photosensitive layer on a substrate using the photosensitive composition according to claim 7; irradiating predetermined regions of the photosensitive layer with actinic radiation to perform pattern exposure; and developing the exposed photosensitive layer with a developer to selectively remove exposed or unexposed regions of the photosensitive layer.

11. 11. The pattern formation method according to claim 10, wherein the developer is an organic solvent having a solubility parameter (SP value) of 7.5 to 11.

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