An acetal compound, an additive comprising said compound, and a composition for a resist comprising said compound

Abstract

[Problem] To provide a resist composition for a thick film capable of forming a pattern with good surface condition and suppressing cracking of the resist film, and an acetal compound that enables the same. [Solution] An acetal compound represented by the following formula (1): (wherein R1 represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, or an acyl group having 1 to 12 carbon atoms. n is an integer from 1 to 5. m represents an integer from 2 to 4. Ar is a residue excluding a hydroxyl group from a polyvalent phenol with a valence of m.) and a composition for a thick film resist comprising the same.

Description

Technology Field

[0001] The present invention relates to acetal compounds, particularly acetal compounds useful for compositions for resists. Furthermore, the present invention relates to an additive comprising said acetal compound used in compositions for resists. Additionally, the present invention relates to a composition for resist comprising said acetal compound, particularly a composition for a thick film resist in which solubility in a developer changes due to the action of an acid. Background Technology

[0002] With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. Currently, lithography technology using KrF excimer laser light (wavelength 248 nm) or ArF excimer laser light (wavelength 193 nm) is being used in mass production. In addition, research and development is underway on lithography technology using F2 excimer laser light (wavelength 157 nm), which has a shorter wavelength, as well as EUV (extreme ultraviolet) and X-rays, which have shorter wavelengths than these excimer lasers, and electron beams.

[0003] Meanwhile, in memory ICs, three-dimensionalization of memory layers, such as 3D-NAND, is becoming mainstream in order to increase memory capacity. Since three-dimensionalization of memory layers requires increasing the number of processing steps in the vertical direction, thickening of the resist film is desired. For example, Patent Document 1 discloses a chemically amplified positive type photoresist composition for thick films used to form a thick photoresist layer with a film thickness of 5 to 150 μm. Prior art literature

[0004] Patent Document 1: Japanese Patent Publication No. JP 2008-191218 The problem to be solved

[0005] However, in thick film resists, since the resin is applied thickly, there was a problem that cracks were prone to occur in the resist film after baking. In addition, during the etching process of the resist film, microscopic bubbles were generated within the resist due to the decomposition of the acid generator, and when etched, irregularities originating from the bubbles occurred on the pattern surface.

[0006] Accordingly, the object of the present invention is to provide a compound useful for a resist composition capable of suppressing the occurrence of cracks in a thick film resist and forming a resist pattern with a smooth surface condition. Additionally, the object of the present invention is to provide a resist composition comprising said compound. means of solving the problem

[0007] The inventors, after repeated careful consideration to achieve the above objective, discovered that by including an acetal compound, which is a reaction product of a polyhydric phenol and a vinyl ether having an oxyethylene chain, in a composition for a resist, it is possible to suppress the occurrence of cracks even in thick film resists and form a resist pattern with a smooth surface condition, and thus completed the present invention.

[0008] That is, according to the present invention, the following invention is provided.

[0009] [1] The following general formula (1):

[0010]

[0011] (of general formula (1), R 1 represents a C1–C12 alkyl group, a C5–C12 cycloalkyl group, or a C1–C12 acyl group. n is an integer from 1 to 5. m represents an integer from 2 to 4. Ar is a residue of a polyvalent phenol with valence m, excluding the hydroxyl group.

[0012] Acetal compound represented by

[0013] [2] The vinyl ether having the oxyethylene chain above is the following general formula (2):

[0014]

[0015] (In general formula (2), R 1 and n is R in general formula (1) 1 and is synonymous with n.)

[0016] The acetal compound described in [1], represented by.

[0017] [3] The above polyphenol is a phenol having 10 to 30 carbon atoms, an acetal compound described in [1] or [2]

[0018] [4] The above polyphenol is a bisphenol-type compound, an acetal compound described in [1] or [2].

[0019] [5] The above polyphenol is a naphthalenediol, an acetal compound described in [1] or [2].

[0020] [6] The acetal compound described in [1] or [2], wherein the polyphenol is at least one compound selected from the group consisting of bisphenol A, 1,1,1-tris(4-hydroxyphenyl)ethane and 1,5-dihydroxynaphthalene.

[0021] [7] An acetal compound described in any one of [1] to [6] used in a composition for a resist.

[0022] [8] An additive used in a composition for a resist, comprising an acetal compound described in any one of [1] to [7].

[0023] [9] A composition for a resist comprising a polymer whose solubility in a developer changes due to the action of an acid, an acid generator, a solvent, and an acetal compound described in any one of [1] to [7].

[0024]

[10] A method for preparing an acetal compound as described in any one of [1] ~ [7],

[0025] Polyphenols of 2 to 4 valence and the following general formula (2):

[0026]

[0027] (In general formula (2), R 1 and n is R in general formula (1) 1 and is synonymous with n.)

[0028] A method of manufacturing by reacting a vinyl ether represented by in the presence of an acid. Effects of the invention

[0029] According to the present invention, a good resist pattern can be formed in a thick film resist without cracks occurring, and the pattern surface is smooth. Brief explanation of the drawing

[0030] [Fig. 1] Compound A synthesized in Example 1 1 This is the spectrum of H-NMR. [Fig. 2] Compound A synthesized in Example 1 13 This is the spectrum of C-NMR. [Fig. 3] Compound B synthesized in Example 2 1 This is the spectrum of H-NMR. [Fig. 4] Compound B synthesized in Example 2 13 This is the spectrum of C-NMR. [Fig. 5] Compound C synthesized in Example 3 1 This is the spectrum of H-NMR. [Fig. 6] Compound C synthesized in Example 3 13 This is the spectrum of C-NMR. [Fig. 7] Compound D synthesized in Example 4 1 This is the spectrum of H-NMR. [Fig. 8] Compound D synthesized in Example 4 13 This is the spectrum of C-NMR. [Fig. 9] Compound E synthesized in Example 5 1 This is the spectrum of H-NMR. [Fig. 10] Compound E synthesized in Example 5 13This is the spectrum of C-NMR. [Fig. 11] Compound F synthesized in Comparative Example 1 1 This is the spectrum of H-NMR. [Fig. 12] Compound F synthesized in Comparative Example 1 13 This is the spectrum of C-NMR. [Fig. 13] Compound G synthesized in Comparative Example 2 1 This is the spectrum of H-NMR. [Fig. 14] Compound G synthesized in Comparative Example 2 13 This is the spectrum of C-NMR. Specific details for implementing the invention

[0031] [Acetal Compounds]

[0032] The acetal compound of the present invention is a reaction product of a polyvalent phenol and a vinyl ether having an oxyethylene chain. This acetal compound can be used as a useful additive in a composition for a resist that suppresses the occurrence of cracks in the thick film resist and forms a good resist pattern with a smooth surface condition.

[0033] The acetal compound of the present invention is represented by the following general formula (1).

[0034]

[0035] Among the general formula (1), R 1 is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, or an acyl group having 1 to 12 carbon atoms, preferably an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, or an acyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms or an acyl group having 1 to 12 carbon atoms. n is an integer from 1 to 5, preferably an integer from 1 to 3, more preferably 1 or 2. m is an integer from 2 to 4. Ar is a residue excluding the hydroxyl group from a polyvalent phenol with a valence of m.

[0036] The acetal compound of the present invention can be obtained by acetalizing a polyvalent phenol and a vinyl ether having an oxyethylene chain in the presence of an acid catalyst. In the reaction of the polyvalent phenol and the vinyl ether having an oxyethylene chain, it is preferable to react an equivalent amount of vinyl ether corresponding to the hydration of the phenol so that all phenolic hydroxyl groups are converted into acetals.

[0037] Polyvalent phenol is a phenol having multiple phenolic hydroxyl groups. Furthermore, in this specification, phenol refers to all compounds in which a hydroxyl group is bonded to an aromatic ring. Polyvalent phenol is a divalent to tetravalent phenol, preferably a divalent or trivalent phenol, and more preferably a divalent phenol. In addition, polyvalent phenol is preferably a phenol having 10 to 30 carbon atoms, more preferably 10 to 26 carbon atoms, and even more preferably 12 to 20 carbon atoms.

[0038] Specific examples of polyphenols include various bisphenols, naphthalenediol, anthracendiol, pyrenediol, 1,1,1-tris(4-hydroxyphenyl)ethane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, or biphenylenediol. Among these, it is preferable to use at least one compound selected from bisphenol A, 1,1,1-tris(4-hydroxyphenyl)ethane, and 1,5-dihydroxynaphthalene.

[0039] A vinyl ether having an oxyethylene chain is preferably a compound represented by formula (2).

[0040]

[0041] R in general formula (2) 1 and n is R in general formula (1) 1 and is synonymous with n.

[0042] Examples of bases represented by the general formula (2) include the following.

[0043]

[0044] ※ In the formula, n represents the number of repetitions of the oxyethylene chain.

[0045] Examples of acid catalysts used in the acetalization reaction include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid; carboxylic acids such as formic acid, acetic acid, butyric acid, and trifluoroacetic acid; sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid; and phosphonic acids such as methanephosphonic acid and benzenephosphonic acid. Among these, carboxylic acids or sulfonic acids are preferred from the perspective of inhibiting the polymerization reaction of vinyl ethers.

[0046] The amount of acid catalyst used cannot be uniformly specified as it varies depending on the type of acid used, but it is typically 1 to 5,000 ppm for the entire reaction system, and preferably 1 to 2,000 ppm. If the amount of acid catalyst used is within the above range, side reactions such as the polymerization of vinyl ethers are unlikely to occur, and it is also easy to obtain a sufficient reaction rate.

[0047] The solvent used in the acetalization reaction may be a solvent capable of stably dissolving the raw material, a polymer having phenolic hydroxyl groups, a vinyl ether, an acid catalyst, and the product obtained from the acetalization reaction. Specifically, examples of solvents include esters such as methyl acetate, ethyl acetate, isopropyl acetate, propyl acetate, butyl acetate, methyl propionate, methyl lactate, and ethyl lactate; glycol ether esters such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; ethers such as tetrahydrofuran, 1,4-dioxane, and ethylene glycol dimethyl ether; and aromatic hydrocarbons such as toluene and xylene, and these may be used individually or in a mixture of two or more.

[0048] The temperature of the acetalization reaction is preferably 25 to 120°C, preferably 30 to 100°C, and more preferably 30 to 80°C.

[0049] After the acetalization reaction, it is desirable to neutralize the acid catalyst by adding an alkaline compound to the reaction solution or to remove the acid catalyst using an anion exchange resin. Specifically, alkaline compounds include alkali metal compounds such as hydroxides, carbonates, and bicarbonates of alkali metals such as sodium and potassium; water and ammonia gas; amines such as trimethylamine and triethylamine; pyridines such as pyridine and methylpyridine; and quaternary ammonium compounds such as tetraalkylammonium hydroxide. Preferably, neutralization by amines and quaternary ammonium compounds, and removal of the acid catalyst by an anion exchange resin.

[0050] <Composition for Resist>

[0051] The resist composition of the present invention comprises, at least, a polymer whose solubility in a developer changes due to the action of an acid, an acid generator, a solvent, and the acetal compound of the present invention, and may also include other additives such as an acid diffusion inhibitor. In particular, the acetal compound of the present invention can be suitably used in a thick film resist composition used to form a thick film resist with a film thickness of 1 μm or more, preferably 1 μm or more and 100 μm or less.

[0052] In the case of a composition for a thick film resist, the content of the acetal compound of the present invention in the composition is preferably 1 to 50 mass%, more preferably 1 to 30 mass%, even more preferably 1 to 20 mass%, and particularly preferably 1 to 15 mass%. In addition, the content of the polymer is preferably 10 to 80 mass%, more preferably 20 to 60 mass%, and even more preferably 25 to 50 mass%.

[0053] The polymer used in the resist composition of the present invention is a polymer whose solubility in a developer changes due to the action of an acid, and can be arbitrarily selected from those generally used for chemically amplified resists.

[0054] In particular, a polymer comprising repeating units having a structure in which a unit derived from hydroxystyrene or a hydroxyl group of hydroxystyrene is protected by an acid-dissociable group (hereinafter referred to as an acid-dissociable group) is preferred.

[0055] In addition, it may also include repeating units having a structure in which the carboxyl group of acrylic acid or methacrylic acid is protected by an acid-dissociating group.

[0056] The acid-dissociable group has various known structures and is not particularly limited. Specifically, tert-butyl group, tert-amyl group, 1-methyl-1-cyclopentyl group, 1-ethyl-1-cyclopentyl group, 1-methyl-1-cyclohexyl group, 1-ethyl-1-cyclohexyl group, 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, 2-propyl-2-adamantyl group, 2-(1-adamantyl)-2-propyl group, 8-methyl-8-tricyclo[5.2.1.0 2,6 ]Decanyl group, 8-ethyl-8-tricyclo[5.2.1.0 2,6 ]Decanyl group, 8-methyl-8-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecanyl group, 8-ethyl-8-tetracyclo[4.4.0.1 2,5 .1 7,10 ]Saturated hydrocarbon groups such as dodecanyl groups; 1-methoxyethyl group, 1-ethoxyethyl group, 1-iso-propoxyethyl group, 1-n-butoxyethyl group, 1-tert-butoxyethyl group, 1-cyclopentyloxyethyl group, 1-cyclohexyloxyethyl group, 1-tricyclo[5.2.1.0 2,6 ]Decanyloxyethyl group, methoxymethyl group, ethoxymethyl group, iso-propoxymethyl group, n-butoxymethyl group, tert-butoxymethyl group, cyclopentyloxymethyl group, cyclohexyloxymethyl group, tricyclo[5.2.1.0 2,6 Examples include oxygen-containing hydrocarbon groups such as ]decanyloxymethyl group, tetrahydropyranyl group, tert-butoxycarbonyl group, etc.

[0057] In addition to the repeating units mentioned above, the polymer may include repeating units containing polar groups such as alcoholic hydroxyl groups, lactones, and sulfones for the purpose of improving substrate adhesion. Examples of monomers that impart such repeating units include 2-hydroxyethyl (meth)acrylate, 3-hydroxy-1-adamantyl methacrylate, γ-butyrolactone-α-(meth)acrylate, norbonan lactone (meth)acrylate, 2-methacryloyloxyacetoxy-4,5-oxathiaticyclo[4.2.1.03,7]nonane=5,5-dioxide.

[0058] In addition, the polymer may include other repeating units that do not have acid-dissociable groups. Examples of monomers that impart such repeating units include styrene, 2-vinylnaphthalene, methyl (meth)acrylate, 1-adamantyl (meth)acrylate, etc.

[0059] The acid generator can be appropriately selected from those proposed so far as acid generators for chemically amplified resists. Examples of such agents include onium salts such as iodium salts or sulfonyl salts, oximesulfonates, diazomethanes such as bisalkyl or bis-arylsulfonyldiazomethanes, nitrobenzylsulfonates, iminosulfonates, and disulfones. Among these, onium salts are preferred. These may be used alone or in combination of two or more.

[0060] Acid diffusion inhibitors can be appropriately selected from those proposed so far as acid diffusion inhibitors for chemically amplified resists. Examples of such compounds include nitrogen-containing organic compounds, and primary to tertiary alkylamines or hydroxyalkylamines are preferred. Tertiary alkylamines and tertiary hydroxyalkylamines are particularly preferred. Among these, triethanolamine and triisopropanolamine are particularly preferred. These may be used alone or in combination of two or more.

[0061] The solvent only needs to be capable of dissolving each component constituting the resist composition and forming a homogeneous solution. For example, any known solvent for film formation may be used as a single solvent or a mixture of two or more solvents. Since it has excellent solubility, a solvent having at least one polar group selected from ketone bonds, ester bonds, ether bonds, and hydroxyl groups is preferred. Among these, a solvent having a boiling point of 110 to 220°C at atmospheric pressure is particularly preferred because it has a suitable evaporation rate during baking after spin coating and excellent film-forming properties. Specific examples of such solvents include solvents having ketone bonds such as methyl isobutyl ketone, methyl isoamyl ketone, methyl amyl ketone, and cyclohexanone; solvents having ether bonds and hydroxyl groups such as propylene glycol monomethyl ether (PGME) and propylene glycol monoethyl ether; solvents having ether bonds and ester bonds such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, and 3-ethoxypropionate ethyl; solvents having ester bonds and hydroxyl groups such as methyl lactate and ethyl lactate; and solvents having ester bonds such as γ-butyrolactone. Among these, PGMEA, PGME, γ-butyrolactone, and ethyl lactate are preferred.

[0062] In addition, if desired, the composition for the resist may appropriately contain compounds commonly used as additives for the resist, such as organic carboxylic acids or phosphoric oxo acids for preventing the deterioration of sensitivity of acid generators or improving the shape and storage stability of the resist pattern, additional resins for improving the performance of the resist film, surfactants for improving coating properties, dissolution inhibitors, plasticizers, stabilizers, colorants, anti-halation agents, dyes, etc.

[0063] Examples

[0064] The embodiments of the present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples in any way. Furthermore, in the following examples, unless specifically determined otherwise, parts are based on mass.

[0065] The analysis in this embodiment was carried out as follows.

[0066] [Identification of Compounds]

[0067] The identification of the compound synthesized below is, 1 H-NMR and 13 It was performed using C-NMR. Each compound 1 H-NMR spectrum and 13 The C-NMR spectra are shown in Figures 1 to 14. In addition, since the synthesized compound was analyzed as a solution containing the solvent without isolation, the NMR spectrum contains a mixed peak of the solvent, propylene glycol monomethyl ether acetate. Furthermore, 1 The peaks of propylene glycol monomethyl ether acetate in H-NMR are ppm=1.16(d), 1.95, 3.27, 3, 32-3.38(dd), and 4.98(m), and 13 The peaks of propylene glycol monomethyl ether acetate in the C-NMR spectrum are ppm=16.86, 21.03, 58.91, 69.52, 75.42, and 170.23.

[0068] Device: Burka AVANCE

[0069] Frequency: 500MHz

[0070] Deuterium solvent: Acetone-d6

[0071] Internal Standard: TMS

[0072] Measured temperature: 30℃

[0073] [Weight Average Molecular Weight and Dispersion of Polymers]

[0074] The weight average molecular weight (Mw) and dispersion (Mw / Mn) of the polymer synthesized below were measured by GPC (gel permeation chromatography) using polystyrene as a standard.

[0075] Measuring device: Tosos HPLC-8220GPC

[0076] Detector: Parallax Refractive Index (RI) Detector

[0077] Column: Shodex GPC KF804 x 3 (Showa Denko)

[0078] Eluent: Tetrahydrofuran

[0079] Flow rate: 1.0 mL / min

[0080] Temperature: 40℃

[0081] Calibration curve: Prepared using polystyrene standard samples (tossoze).

[0082] [Polymer Composition]

[0083] The composition ratio of each monomer in the synthesized polymer 13 Analysis was performed using C-NMR. An analytical sample was prepared by dissolving 2.0 g of the polymer solution after concentration adjustment and 0.1 g of Cr(III) acetylacetonate in 1.0 g of biacetone.

[0084] Device: Burka-made AVANCE400

[0085] Nuclides: 13 C

[0086] Measurement method: Inverse gate decoupling

[0087] [Synthesis of Additives for Resist]

[0088] [Example 1] Synthesis of Compound A

[0089] Bisphenol A and propylene glycol monomethyl ether acetate (hereinafter PGMEA) were placed in an eggplant flask and concentrated under reduced pressure at 40°C to prepare a solution having a water content of 500 ppm or less and a Bis-A concentration of 40 mass%. In a reaction vessel equipped with a thermometer, a cooling tube, and a stirring device, 2680.0 g of the aforementioned Bis-A / PGMEA solution and 63.8 g of a 20 mass% trifluoroacetic acid / PGMEA solution were placed, and the mixture was heated to 60°C while stirring under a nitrogen stream. To this, a mixed solution of 1055.4 g of 2-methoxyethyl vinyl ether (hereinafter MOVE) and 468.2 g of PGMEA was added dropwise over a period of 60 minutes, and the reaction was continued for 4 hours after the addition was completed. After the reaction was finished, the reaction solution was passed through 243.5 g of Amberlist B20-HG·DRY packed in a column for 6 hours to remove the catalyst, trifluoroacetic acid. Subsequently, the solution was concentrated under reduced pressure at 40°C to obtain a PGMEA solution with a concentration of 50 mass% of compound A.

[0090] The obtained compound A was confirmed to have the structure of formula (3) below by NMR analysis. In addition, the HPLC purity of the obtained compound was 98.7%.

[0091] Compound A:

[0092]

[0093] The results of the NMR analysis of compound A are as follows.

[0094] 1 H-NMR (500MHz, acetone-d6): δppm=1.41(6H), 1.61(6H), 3.24(6H), 3.45(4H), 3.60(2H), 3.77(2H), 5.40(2H), 6.91(4H), 7.11(4H)

[0095] 13C-NMR (500MHz, acetone-d6): δppm=20.49, 31.33, 42.24, 58.91, 65.52, 72.29, 100.31, 117.53, 128.26, 144.78, 155.67

[0096] [Example 2] Synthesis of Compound B

[0097] 1,1,1-tris(4-hydroxyphenyl)ethane (hereinafter THPE) and PGMEA were placed in a flask and concentrated under reduced pressure at 40°C to prepare a solution having a water content of 500 ppm or less and a THPE concentration of 20 mass%. In a reaction vessel equipped with a thermometer, a cooling tube, and a stirring device, 2966.5 g of the aforementioned THPE / PGMEA solution and 4.2 g of a 1 mass% methanesulfonic acid / PGMEA solution were placed, and the mixture was heated to 60°C while stirring under a nitrogen stream. To this, a mixed solution of 672.5 g of 2-methoxyethyl vinyl ether (hereinafter MOVE) and 552.4 g of PGMEA was added dropwise over a period of 120 minutes, and the reaction was continued for 2 hours after the addition was finished. After the reaction was finished, the reaction solution was passed through 243.5 g of Amberlist B20-HG·DRY packed in a column over a period of 6 hours to remove the catalyst, methanesulfonic acid. Subsequently, the solution was concentrated under reduced pressure at 40°C to obtain a PGMEA solution with a concentration of 50 mass% of compound B.

[0098] The obtained compound B was confirmed to have the structure of formula (4) below by NMR analysis. In addition, the HPLC purity of the obtained compound was 94.2%.

[0099] Compound B:

[0100]

[0101] The results of the NMR analysis of compound B are as follows.

[0102] 1H-NMR (400MHz, acetone-d6): δppm=1.41(9H), 2.08(3H), 3.24(9H), 3.46(6H), 3.61(3H), 3.77(3H), 5.42(3H), 6.91(6H), 6.97(6H)

[0103] 13 C-NMR (400MHz, acetone-d6): δppm=20.47, 31.04, 51.40, 58.90, 63.56, 72.28, 100.26, 117.26, 130.18, 143.49, 155.88

[0104] [Example 3] Synthesis of Compound C

[0105] Bisphenol A and PGMEA were placed in a flask and concentrated under reduced pressure at 40°C to obtain a solution having a water content of 500 ppm or less and a Bis-A concentration of 40 mass%. In a reaction vessel equipped with a thermometer, a cooling tube, and a stirring device, 200.8 g of the aforementioned 40 mass% bisphenol A / PGMEA solution and 6.8 g of a 20 mass% trifluoroacetic acid / PGMEA solution were placed, and the mixture was heated to 60°C while stirring under a nitrogen stream. To this, a mixed solution of 147.2 g of 2-(2-(2-methoxyethoxy)ethoxy)ethyl vinyl ether (hereinafter TEGVE) and 101.6 g of PGMEA was added dropwise over a period of 60 minutes, and the reaction was continued for 6 hours after the addition was finished. After the reaction was finished, the reaction solution was passed through 26.1 g of Amberlist B20-HG·DRY packed in a column over a period of 6 hours to remove the catalyst, trifluoroacetic acid. Subsequently, the solution was concentrated under reduced pressure at 40°C to obtain a PGMEA solution with a concentration of 50 mass% of compound C.

[0106] The obtained compound C was confirmed to have the structure of formula (5) below by NMR analysis. In addition, the HPLC purity of the obtained compound was 94.9%.

[0107] Compound C:

[0108]

[0109] The results of the NMR analysis of compound C are as follows.

[0110] 1 H-NMR (400MHz, acetone-d6): δppm=1.41(6H), 1.62(6H), 3.24(6H), 3.44-3.78(24H), 5.42(2H), 6.92(4H), 7.12(4H)

[0111] 13 C-NMR (400MHz, acetone-d6): δppm=20.50, 31.33, 42.24, 58.90, 65.65, 70.94-71.12, 72.54, 100.28, 117.56, 128.24, 144.75, 155.68

[0112] [Example 4] Synthesis of Compound D

[0113] 750.0 g of bisphenol A, 1768.4 g of 2-(vinyloxy)ethyl 1-adamantan carboxylate (hereinafter ACVE), and PGMEA were placed in a branch flask and concentrated under reduced pressure at 40°C to obtain a PGMEA solution in which the water content in the solution was 500 ppm or less and the total concentration of bisphenol A and ACVE was 55 mass%. 906.8 g of the above solution and 112.4 g of a 20 mass% trifluoroacetic acid / PGMEA solution were placed in a branch flask equipped with a thermometer, a condenser, and a stirring device, heated to 50°C while stirring under a nitrogen stream, and then continued the reaction for 8 hours. After the reaction was finished, the reaction solution was passed through 430.0 g of Amberlist B20-HG·DRY packed in a column over 6 hours to remove the catalyst, trifluoroacetic acid. After that, the solution was concentrated under reduced pressure at 40°C to obtain a PGMEA solution with a concentration of 50 mass% of compound D.

[0114] The obtained compound D was confirmed to have the structure of the following formula (6) by NMR analysis. In addition, the HPLC purity of the obtained compound was 98.5%.

[0115] Compound D:

[0116]

[0117] The results of the NMR analysis of compound D are as follows.

[0118] 1 H-NMR (400MHz, acetone-d6): δppm=1.43(6H), 1.61(6H), 1.67-1.70(12H), 1.85(12H), around 1,96(6H), 3.69(2H), 3.85(2H), 4.14(4H), 5.41(2H), 6.93(4H), 7.13(4H)

[0119] 13 C-NMR (400MHz, acetone-d6): δppm=20.24, 28.70, 31.35, 37.09, 39.46, 41.12, 42.27, 63.71, 63.78, 99.99, 117.54, 128.25, 144.82, 155.60, 177.04

[0120] [Example 5] Synthesis of Compound E

[0121] 1,5-dihydroxynaphthalene and PGMEA were placed in a branch flask and concentrated under reduced pressure at 40°C to prepare a solution having a water content of 500 ppm or less and a 1,5-dihydroxynaphthalene concentration of 40 mass%. In a branch flask equipped with a thermometer, a condenser, and a stirring device, 243.8 g of the aforementioned 1,5-dihydroxynaphthalene / PGMEA solution and 0.5 g of a 1 mass% methanesulfonic acid / PGMEA solution were added, and the mixture was heated to 60°C while stirring under a nitrogen stream. To this, a mixed solution of 138.1 g of 2-methoxyethylvinyl ether and 88.5 g of PGMEA was added dropwise over a period of 60 minutes, and the reaction was continued for 6 hours after the addition was completed. After the reaction was finished, the reaction solution was passed through 10.7 g of Amberlist B20-HG·DRY packed in a column over a period of 6 hours to remove the catalyst, methanesulfonic acid. Subsequently, the solution was concentrated under reduced pressure at 40°C to obtain a solution with a concentration of 50 mass% of compound E.

[0122] The obtained compound E was confirmed to have the structure of formula (7) below by NMR analysis. In addition, the HPLC purity of compound E was 88.8%.

[0123] Compound E:

[0124]

[0125] The results of the NMR analysis of compound E are as follows.

[0126] 1 H-NMR (400MHz, acetone-d6): δppm=1.56(6H), 3.24(6H), 3.4-3.9(8H), 5.66(2H), 7.12(2H), 7.36(2H), 7.88(2H)

[0127] 13 C-NMR (400MHz, acetone-d6): δppm=20.57, 58.72, 66.02, 72.31, 101.04, 110.45, 115.99, 126.07, 128.42, 153.45

[0128] [Comparative Example 1] Synthesis of Compound F

[0129] Bisphenol A and PGMEA were placed in a branch flask and concentrated under reduced pressure at 40°C to obtain a solution with a water content of 500 ppm or less and a Bis-A concentration of 40 mass%. In a branch flask equipped with a thermometer, a condenser, and a stirring device, 337.6 g of the aforementioned bisphenol A / PGMEA solution and 7.0 g of a 20 mass% trifluoroacetic acid / PGMEA solution were added, and the mixture was heated to 40°C while stirring under a nitrogen stream. A mixed solution of 98.1 g of ethyl vinyl ether and 25.0 g of PGMEA was added dropwise over 60 minutes, and the reaction was continued for 4 hours after the addition was finished. After the reaction was finished, the reaction solution was passed through 26.7 g of Amberlist B20-HG·DRY packed in a column over 6 hours to remove the catalyst, trifluoroacetic acid. After that, the solution was concentrated under reduced pressure at 40°C, and a solution with a concentration of 50 mass% of compound F was obtained.

[0130] The obtained compound F was confirmed to have the structure of formula (8) below by NMR analysis. In addition, the HPLC purity of the obtained compound was 96.6%.

[0131] Compound F:

[0132]

[0133] The results of the NMR analysis of compound F are as follows.

[0134] 1 H-NMR (400MHz, acetone-d6): δppm=1.11(6H), 1.40(6H), 1.61(6H), 3.49(2H), 3.71(2H), 5.35(2H), 6.89(4H), 7.12(4H)

[0135] 13 C-NMR (400MHz, acetone-d6): δppm=15.52, 20.61, 31.34, 42.24, 61.55, 100.01, 117.38, 128.26, 144.63, 155.80

[0136] [Comparative Example 2] Synthesis of Compound G

[0137] Bisphenol A and PGMEA were placed in a branch flask and concentrated under reduced pressure at 40°C to prepare a PGMEA solution with a water content of 500 ppm or less and a bisphenol A concentration of 40 mass%. In a branch flask equipped with a thermometer, a condenser, and a stirring device, 2401.9 g of the aforementioned bisphenol A / PGMEA solution and 63.9 g of a 20 mass% trifluoroacetic acid / PGMEA solution were added, and the mixture was heated to 60°C while stirring under a nitrogen stream. A mixed solution of 1168.4 g of cyclohexyl vinyl ether and 637.0 g of PGMEA was added dropwise over 60 minutes, and the reaction was continued for 6 hours after the addition was finished. After the reaction was finished, the reaction solution was passed through 243.7 g of Amberlist B20-HG·DRY packed in a column over 6 hours to remove the catalyst, trifluoroacetic acid. After that, the solution was concentrated under reduced pressure at 40°C, and a solution with a concentration of 50 mass% of compound G was obtained.

[0138] The obtained compound G was confirmed to have the structure of formula (9) below by NMR analysis. In addition, the HPLC purity of the obtained compound was 97.8%.

[0139] Compound G:

[0140]

[0141] The results of the NMR analysis of compound G are as follows.

[0142] 1 H-NMR (400MHz, acetone-d6): δppm=1.18-1.50(12H), 1.39(6H), 1.61(6H), 1.65(4H), 1.81(4H), 3.64(2H), 5.49(2H), 6.89(4H), 7.12(4H)

[0143] 13C-NMR (400MHz, acetone-d6): δppm=21.47, 24.48, 24.65, 26, 31, 31.34, 32.96, 34.17, 42.26, 74.76, 98.95, 117.67, 128.29, 144.63, 155.74

[0144] [Synthesis of Polymers for Resist]

[0145] [Synthesization Example 1] Synthesis of p-hydroxystyrene / styrene / t-butyl methacrylate copolymer

[0146] 900.0 g of a p-ethylphenol solution (hereinafter referred to as PHS monomer solution) containing 24 mass% of p-hydroxystyrene, 23 mass% of methanol, and 10 mass% of water was placed in a branch flask equipped with a thermometer, a cooling tube, and a stirring device, and the temperature was raised to 80°C. In another container, 1350.0 g of the PHS monomer solution with the same composition as above, 184.6 g of styrene, 182.2 g of t-butyl acrylate, and 39.1 g of dimethyl 2,2'-azobis(2-methylpropionate) were added and stirred to make a homogeneous solution. This solution was added dropwise to the branch flask above over a period of 2 hours, and the polymerization reaction was carried out by continuing stirring for another hour. Afterwards, the polymer solution was cooled to room temperature and dropped into a mixed solution of 4023 g of methylcyclohexane and 603 g of 2-propanol to precipitate the polymer, and the supernatant was removed. In addition, for purification, the polymer was redissolved by adding 2-propanol, dropped into methylcyclohexane to precipitate the polymer, and the operation of removing the supernatant was repeated 5 times.

[0147] The recovered polymer was dissolved in 2600g of PGMEA and concentrated under reduced pressure at 40°C to prepare a PGMEA solution with a polymer concentration of 50 mass%. The obtained polymer had a composition ratio of p-hydroxystyrene:styrene:t-butyl methacrylate of 59.1:20.6:20.3, Mw=19,000, and Mw / Mn=1.83.

[0148] [Preparation of a composition for resist]

[0149] A composition for a resist was prepared by dissolving 60 parts by mass (30 parts by mass equivalent to Compound A) of a PGMEA solution containing 50% by mass of Compound A obtained in Example 1, 140 parts by mass (70 parts by mass equivalent to the polymer) of a polymer solution for the resist obtained in Synthesis Example 1, 1 part by mass of an acid generating agent (ADEKA, SP140), and 0.1 parts by mass of a surfactant (DIC, F447) in PGMEA to adjust the solid content concentration to 40% by mass, and then filtering it through a membrane filter with a pore diameter of 0.45 μm.

[0150] Likewise, compounds B to G obtained in Examples 2 to 5 and Comparative Examples 1 and 2 were mixed in the ratios shown in Table 1, and a resist composition was prepared for each.

[0151] In addition, as Comparative Example 3, a composition for a resist that does not contain compounds A to G was prepared.

[0152] Using the above-described resist composition, the physical properties of the resist composition were evaluated according to the following method.

[0153] [Crack Resistance · Surface Roughness]

[0154] Hexamethyldisilazane was applied to a 6-inch silicon wafer and heat-treated at 100°C for 60 seconds. After treatment, the above resist composition was spin-coated onto the silicon wafer and pre-baked on a hot plate at 100°C for 60 seconds to form a resist layer with a film thickness of 8 μm.

[0155] Etching was performed on the obtained resist layer under the following conditions.

[0156] Crack resistance was evaluated by visually observing the surface of the resist layer after etching, with ○ indicating no cracks were detected and × indicating cracks were detected. The evaluation results are shown in Table 1.

[0157] <Etching Conditions>

[0158] Output: 180W

[0159] Chamber pressure: 18 Pa

[0160] Gas type: O2

[0161] Gas flow rate: 100 mL / min

[0162] Etching time: 10 minutes

[0163] In addition, surface roughness was calculated by measuring the surface of the resist layer after etching using an atomic force microscope (BRUKER, Dimension Icon) and determining the average surface roughness Ra over a 5 μm square range. Ra is the arithmetic mean roughness specified in JIS B 0601: 2013. Based on the Ra value of the resist composition not containing compounds A to G (Comparative Example 3), the Ra value was evaluated as ○ if it was 60% or less of the Ra value of Comparative Example 3, △ if it was greater than 60% and less than 100%, and × if it was 100% or more. The evaluation results are shown in Table 1.

[0164] [Evaluation of Sensitivity of Resist Compositions]

[0165] Hexamethyldisilazane was applied to a 6-inch silicon wafer and heat-treated at 100°C for 60 seconds. After treatment, the above resist composition was spin-coated onto the silicon wafer and dried on a hot plate at 100°C for 60 seconds to form a resist layer with a film thickness of 8 μm.

[0166] On the formed resist layer, light with a wavelength of 248 nm is applied by varying the exposure amount using an open-frame exposure device (light source: Hg-Xe lamp, Risotec Japan UVS-2000) to 10 mm 2 ×10mm 2After irradiating with 18 shots, the wafer was heat-treated at 100°C for 60 seconds. Subsequently, the exposed and heat-treated silicon wafer was developed using a resist development speed measuring device (RDA-790 manufactured by Risotec Japan) with a 2.38 mass% aqueous tetramethylammonium hydroxide solution at 23°C, and the change in resist film thickness over time for each exposure amount was measured. By analyzing this data, the sensitivity Eth of the resist was calculated. A smaller value of Eth indicates higher sensitivity. Eth: By drawing an approximate straight line on the residual film rate curve in the range of 10% to 70% residual film rate, the exposure amount (mJ / cm²) corresponding to a residual film rate of 0% 2 )

[0167] Based on the Eth value of the resist composition not containing compounds A to G (Comparative Example 3), the evaluation was ○ if the Eth value was 80% or less of the Eth value of Comparative Example 3, and △ if it was greater than 80%. The evaluation results are shown in Table 1.

[0168]

[0169] In Example 5, since compound E contains a naphthalene ring, it has strong absorption of light at a wavelength of 248 nm, and the sensitivity is lower compared to Example 2. However, it is presumed that it is possible to suppress cracks or surface irregularities of the resist film while maintaining sensitivity during exposure to i-line (365 nm), EUV, etc.

[0170] When the resist composition containing the acetal compound of the present invention is used as a film thickness resist, it is possible to suppress the occurrence of cracks in the resist film after etching and also suppress the surface irregularities of the resist film caused by the generation of bubbles.

[0171] Industrial applicability

[0172] The acetal compound of the present invention can be used in compositions for resists, particularly compositions for thick film resists.

Claims

Claim 1 The following general formula (1): (of general formula (1), R 1 An acetal compound represented by , where represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 5 to 12 carbon atoms. n is an integer from 1 to 3. m represents an integer from 2 to 4. Ar is a residue excluding the hydroxyl group from a polyvalent phenol with valence m. Claim 2 In claim 1, a polyhydric phenol having 2 to 4 hydrides and the following general formula (2): (In general formula (2), R 1 and n is R in general formula (1) 1 An acetal compound that is a reaction product with a vinyl ether having an oxyethylene chain represented by (and is synonymous with n). Claim 3 An acetal compound according to claim 1, wherein the polyvalent phenol is a phenol having 10 to 30 carbon atoms. Claim 4 An acetal compound according to claim 1, wherein the polyvalent phenol is at least one compound selected from the group consisting of bisphenols, naphthalenediol, anthracendiol, pyrenediol, 1,1,1-tris(4-hydroxyphenyl)ethane and 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane. Claim 5 In claim 1, the polyvalent phenol is an acetal compound, which is naphthalenediol. Claim 6 An acetal compound according to claim 1, wherein the polyhydric phenol is at least one compound selected from the group consisting of bisphenol A, 1,1,1-tris(4-hydroxyphenyl)ethane and 1,5-dihydroxynaphthalene. Claim 7 The acetal compound used in the composition for the resist according to claim 1. Claim 8 An additive comprising an acetal compound used in a composition for a resist, in any one of claims 1 to 7. Claim 9 A composition for a resist comprising a polymer whose solubility in a developer changes due to the action of an acid, an acid generator, a solvent, and an acetal compound described in any one of claims 1 to 7. Claim 10 A method for preparing an acetal compound as described in any one of claims 1 to 7, comprising a polyvalent phenol having 2 to 4 valence and the following general formula (2): (In general formula (2), R 1 and n is R in general formula (1) 1 A method of preparation in which a vinyl ether represented as (and is synonymous with n) is reacted in the presence of an acid.

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