Naphthol resin, resin composition for resist undercoat, and method for manufacturing semiconductor device

Abstract

To provide a naphthol resin with improved etching resistance. [Solution] Naphthol resin has repeating units represented by general formula (1). TIFF2026066520000008.tif39153

Description

[Technical Field]

[0001] The present invention relates to naphthol resin, resin composition for resist undercoats, and method for manufacturing semiconductor devices. [Background technology]

[0002] Conventionally, a processing method is known in which a photoresist film is applied to a semiconductor substrate such as a silicon wafer to form a thin film, exposure is performed through a mask pattern on which the device pattern is drawn, and then the substrate is etched using the resulting photoresist pattern as a protective film to form a fine pattern corresponding to the above-mentioned photoresist pattern on the substrate surface.

[0003] Furthermore, it is known that a resist underlayer film is used beneath the photoresist film to suppress the reflection of active light rays from the substrate during exposure and to eliminate minute steps on the substrate surface between the substrate and the photoresist.

[0004] In recent years, due to the miniaturization of resist patterns, the thinning of resist films has progressed. Therefore, the resist underlayer film also needs to function as a mask during substrate processing. For example, Patent Document 1 (International Publication No. 2017 / 183612) discloses a resist underlayer film having a naphthol skeleton. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2017 / 183612 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, as semiconductor devices become more miniaturized and denser, the photoresist film and the resist underlayer film become thinner, and there is room for improvement in the etching resistance of conventional resist underlayer films, such as those disclosed in Patent Document 1. The inventors of this invention conducted thorough research to improve the etching resistance of the resist underlayer film and developed a new naphthol resin having a predetermined structure. They then found that excellent etching resistance could be obtained in the resist underlayer film using this naphthol resin, thus completing the present invention. [Means for solving the problem]

[0007] According to the present invention, the following naphthol resin and related technologies are provided.

[0008] [1] A naphthol resin having repeating units represented by the following general formula (1). [ka] (In formula (1), A represents phenols. n is an integer between 1 and 30.) [2] [1] The naphthol resin described above, Naphthol resin in which the Onishi parameter, calculated by the following equation (2), is 1.95 or higher. Onishi parameter = N / (N C -N O ) (2) (In equation (2), in the monomer corresponding to the repeating unit, the total number of atoms is N and the total number of carbon atoms is N C , total oxygen number N O (Let's assume that.) [3] The naphthol resin described in [1] or [2], Naphthol resin with a softening point of 90-150°C. [4] A naphthol resin as described in any one of [1] to [3], Naphthol resin with a weight-average molecular weight of 2,000 to 50,000. A resin composition for a resist undercoat, comprising the naphthol resin described in any one of [1] to [4]. [6] The resin composition for an underlayer film of a resist according to [5], The resin composition for an underlayer film of a resist, further comprising a crosslinking agent. [7] The resin composition for an underlayer film of a resist according to [5] or [6], The resin composition for an underlayer film of a resist, further comprising an acid generator. [8] A step of forming an underlayer film of a resist on a substrate using the resin composition for an underlayer film of a resist according to any one of [5] to [7], A step of forming an upper layer film of a resist on the underlayer film of the resist, A step of exposing and developing the upper layer film of the resist to form a resist pattern, A step of etching the underlayer film of the resist using the resist pattern, A step of processing the substrate using the etched underlayer film of the resist, A method for manufacturing a semiconductor device, comprising: [Advantages of the Invention]

[0009] According to the present invention, a naphthol resin capable of obtaining excellent etching resistance of an underlayer resist film is provided. [Brief Description of the Drawings]

[0010] [Figure 1] It is a figure which shows the 1H-NMR spectrum of naphthol resin A1 of an Example. [Modes for Carrying Out the Invention]

[0011] Hereinafter, embodiments of the present invention will be described. In this specification, the notation "a to b" in the description of a numerical range means "a or more and b or less" unless otherwise specified. For example, "5 to 90% by mass" means "5% by mass or more and 90% by mass or less".

[0012] Each component and material exemplified in this specification may be used alone or in combination of two or more, unless otherwise specified.

[0013] <Naphthol resin> Naphthol resin has repeating units represented by the following formula (1). That is, by including a cyclic skeleton in which phenols are further bonded to the aralkyl of naphthol aralkyl as repeating units, a rigid chemical structure is obtained, which is presumed to effectively improve resistance to dry etching. In addition, good heat resistance is obtained.

[0014] [ka]

[0015] (In formula (1), A represents phenols. n is an integer between 1 and 30.)

[0016] In formula (1), A represents phenols, and specific examples include monocyclic phenols such as phenol, cresol, resorcinol, and catechol; condensed polycyclic phenols such as naphthol, dihydroxynaphthalene, and anthraquinol; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; and polycyclic phenols such as phenylphenol and biphenol. Among these, phenol and biphenol are preferred because they improve etching resistance.

[0017] The naphthol resin of this embodiment has repeating units represented by formula (1), 1 This can be confirmed by H-NMR spectroscopy and IR spectroscopy. Further details will be explained in the examples.

[0018] In this embodiment, the naphthol resin preferably has an Onishi parameter calculated by the following formula (2) of 1.95 or higher, more preferably 1.98 or higher, and even more preferably 2.00 or higher. This ensures that good etching resistance is stably obtained.

[0019] Onishi parameter = N / (N C -NO ) (2) (In the monomer corresponding to the repeating unit in Formula (2), let the total number of atoms be N, the total number of carbon atoms be N C , and the total number of oxygen atoms be N O .)

[0020] The Ohmori parameter is a parameter generally used to represent carbon density. The larger the value of the Ohmori parameter, the lower the carbon density. That is, by reducing the carbon density, the etching resistance can be improved.

[0021] On the other hand, the upper limit of the Ohmori parameter obtained by Formula (2) is preferably 2.3 or less, more preferably 2.1 or less.

[0022] The softening point of the naphthol resin is preferably 90 to 150 °C, more preferably 92 to 130 °C, and still more preferably 94 to 125 °C. By setting the softening point to be not less than the above lower limit value, it can be solid at room temperature and has excellent handleability. By setting the softening point to be not more than the above upper limit value, it can be used by heat melting.

[0023] The softening point can be measured by the ring and ball method described in JIS K7234. The softening point of the naphthol resin can be adjusted by controlling the reaction ratio with the compound that reacts with naphthols.

[0024] The weight average molecular weight of the naphthol resin is preferably 2500 to 50000, more preferably 3000 to 30000, still more preferably 4000 to 20000, and even more preferably 5000 to 10000. By setting the weight average molecular weight to be not less than the above lower limit value, it can be solid at room temperature, so the handleability can be improved. By setting the weight average molecular weight to be not more than the above upper limit value, it can be heat melted.

[0025] The weight-average molecular weight can be measured using gel permeation chromatography (GPC) to obtain a polystyrene equivalent. The weight-average molecular weight of naphthol resin can be adjusted by controlling the reaction ratio between naphthols and the compounds they react with.

[0026] The gelation time of naphthol resin at 150°C is preferably in the range of 50 seconds or more and 200 seconds or less, and more preferably in the range of 60 seconds or more and 160 seconds or less. By setting the gelation time above the lower limit, a more uniform film can be obtained with the resin composition for the resist undercoat. On the other hand, by setting the gelation time below the upper limit, good curability of the resin composition for the resist undercoat can be obtained, and the production cycle can be shortened.

[0027] <Method for producing naphthol resin> A method for producing naphthol resin includes at least a step of reacting naphthols with phenols. The reaction is preferably carried out under an acidic catalyst.

[0028] Examples of naphthols include 1-naphthol and 2-naphthol. When using naphthols, a mixture of 1-naphthol and 2-naphthol may also be used.

[0029] Examples of phenols include monocyclic phenols such as phenol, cresol, resorcinol, and catechol; condensed polycyclic phenols such as naphthol, dihydroxynaphthalene, and anthraquinol; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; and polycyclic phenols such as phenylphenol and biphenol.

[0030] Furthermore, it is preferable to use a condensing agent in the reaction system between naphthols and phenols. Examples of condensing agents include p-xylylene glycol, p-xylylene glycol dimethyl ether, p-xylylenedichloride, 4,4'-dimethoxymethylbiphenyl, 4,4'-dichloromethylbiphenyl, dimethoxymethylnaphthalenes, and dichloromethylnaphthalenes.

[0031] For every mole of naphthol, phenols can be used in a ratio of preferably 0.05 moles to 2 moles, more preferably 0.1 moles to 1.5 moles, and even more preferably 0.1 moles to 1.0 mole.

[0032] In the reaction system between naphthols and phenols, it is preferable to continuously distill off the methanol produced.

[0033] As the acid catalyst, known catalysts can be used, but examples include one or more selected from organic acids such as acetic acid, formic acid, oxalic acid, malonic acid, succinic acid, maleic acid, glutaric acid, adipic acid, benzoic acid, salicylic acid, sulfonic acid, phenolsulfonic acid, and p-toluenesulfonic acid; or inorganic acids such as hydrochloric acid, sulfuric acid, sulfuric acid esters, phosphoric acid, and phosphoric acid esters.

[0034] Polymerization conditions are set as appropriate, but it is preferable to set them at 120-240°C for 30-240 minutes. This allows the reaction to proceed efficiently and sufficiently. Furthermore, by carrying out the reaction under heating, the starting materials are uniformly mixed, and the molecular weight of the resulting naphthol resin can be made uniform through intermolecular entanglement and interaction. The heating temperature may be increased in stages. There are no particular restrictions on the polymerization time; it can be determined appropriately depending on the type of starting materials, the molar ratio of the materials, the amount and type of catalyst used, and the reaction conditions.

[0035] Water or an organic solvent may be used as the reaction solvent. Specific examples of organic solvents include alcohols, ketones, and aromatics. Specific examples of alcohols include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, ethylene glycol monomethyl ether, triethylene glycol, and glycerin. Specific examples of ketones include acetone and methyl ethyl ketone. Specific examples of aromatics include toluene and xylene.

[0036] After the reaction, the mixture may be neutralized, and then the volatile components may be distilled out of the system under reduced pressure.

[0037] Through the above process, a naphthol resin having at least one of the repeating units represented by formula (1) is obtained.

[0038] <Application> The naphthol resin of this embodiment is suitable for applications where conventional naphthol aralkyl resins are used, but is particularly good in resin compositions for resist undercoats where etching resistance is required. The following describes resin compositions for resist undercoats.

[0039] <Resin composition for resist undercoat> The resin composition for the resist undercoat of this embodiment contains a naphthol resin having repeating units represented by the above general formula (1). This provides excellent etching resistance.

[0040] The content of naphthol resin having repeating units represented by general formula (1) is preferably 1 to 100% by mass, more preferably 1 to 99% by mass, and even more preferably 50 to 99% by mass, based on the total amount of the resin composition for the resist undercoat. By increasing the naphthol resin content above the lower limit mentioned above, etching resistance can be improved. By keeping the crosslinking agent content below the lower limit mentioned above, good etching resistance can be obtained while maintaining performance as a resist undercoat.

[0041] The resin composition for resist undercoats is a mixture of the naphthol resin described above and optional components depending on the function and application. The optional components are not particularly limited, but examples include crosslinking agents, acid generators, basic compounds, organic solvents, thermosetting resins other than naphthol resin, thermoplastic resins, elastomers, curing agents, curing accelerators, fillers, coupling agents, release agents, thixotropes, thickeners, dispersants, and pigments.

[0042] [Crosslinking agent] Crosslinking agents are used to accelerate the crosslinking and hardening reaction. Examples of the crosslinking agents mentioned above include one or more selected from the following: melamine compounds substituted with at least one group selected from methylol, alkoxymethyl, and acyloxymethyl groups; guanamine compounds; glycoluryl compounds; urea compounds; epoxy compounds; isocyanate compounds; azide compounds; or compounds containing double bonds such as alkenyl ether groups.

[0043] The crosslinking agent content is preferably 0.001 to 80% by mass, more preferably 0.01 to 50% by mass, and even more preferably 0.05 to 40% by mass, based on the total amount of the resin composition for the resist undercoat. By setting the crosslinking agent content above the lower limit mentioned above, the crosslinking reaction can be promoted. By setting the crosslinking agent content below the lower limit mentioned above, good crosslinking properties can be maintained while suppressing the migration of acid to the outside of the resist underlayer film.

[0044] [Acid Generator] The acid generator is used to promote the crosslinking reaction and may be one that generates acid by thermal decomposition, one that generates acid by light irradiation, or any other type. Acid generators include onium salts such as tetramethylammonium trifluoromethanesulfonate, tetramethylammonium nonafluorobutanesulfonate, and triethylammonium nonafluorobutanesulfonate; diazomethane derivatives such as bis(benzenesulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(xylenesulfonyl)diazomethane, and bis(cyclohexylsulfonyl)diazomethane; and glyoxates such as bis-o-(p-toluenesulfonyl)-α-dimethylglyoxime and bis-o-(p-toluenesulfonyl)-α-diphenylglyoxime. Examples include one or more selected from the following: sym derivatives; bissulfone derivatives such as bisnaphthylsulfonylmethane; β-ketosulfone derivatives such as 2-cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane and 2-isopropylcarbonyl-2-(p-toluenesulfonyl)propane; sulfonic acid ester derivatives such as 1,2,3-tris(methanesulfonyloxy)benzene; and sulfonic acid ester derivatives of N-hydroxyimide compounds such as N-hydroxynaphthalimidomethanesulfonic acid ester and N-hydroxynaphthalimidobenzenesulfonic acid ester.

[0045] The acid generator content is preferably 0.0001 to 20 parts by mass, more preferably 0.0005 to 10 parts by mass, and even more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the naphthol resin. By setting the acid generator content above the lower limit mentioned above, the crosslinking reaction can be promoted. By setting the acid generator content below the lower limit mentioned above, good crosslinking properties can be maintained while suppressing the migration of acid to the outside of the resist underlayer film.

[0046] [Basic compounds] Basic compounds are used to improve storage stability. Specifically, basic compounds neutralize the acid generated by the acid generator, thereby suppressing the interference of the crosslinking reaction caused by that acid. Examples of basic compounds include one or more selected from primary, secondary, and tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amide derivatives, imide derivatives, and the like.

[0047] The content of the basic compound is preferably 0.0001 to 20 parts by mass, more preferably 0.0005 to 10 parts by mass, and even more preferably 0.01 to 3 parts by mass, per 100 parts by mass of the naphthol resin. By setting the content of the basic compound above the lower limit mentioned above, the acid can be neutralized. By setting the content of the basic compound below the lower limit mentioned above, an appropriate crosslinking effect by the acid generator can be obtained.

[0048] [organic solvent] Organic solvents are used to adjust the concentration and viscosity of the resist underlayer material, and to improve its applicability and handling properties, among other things. The above-mentioned organic solvent is not particularly limited as long as it can dissolve the naphthol resin, crosslinking agent, acid generator, and other additives, and any known organic solvent can be used. Examples include one or more selected from ketones such as cyclohexanone and methyl-2-amyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; and esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol monomethyl ether acetate, and propylene glycol monotert-butyl ether acetate.

[0049] The organic solvent content is preferably 200 to 10,000 parts by mass, and more preferably 300 to 5,000 parts by mass, per 100 parts by mass of the naphthol resin.

[0050] [Manufacturing method] A known method can be used to manufacture the resin composition for the resist undercoat. This method involves dissolving naphthol resin and optional components in an organic solvent, and preferably removing foreign matter using a filter or the like. The pore size of the filter is preferably 0.2 μm or less, and the filter material can be polytetrafluoroethylene, polyamide, polyethylene, or the like.

[0051] <Manufacturing method for semiconductor devices> The method for manufacturing the semiconductor device in this embodiment is a method using the resin composition for the resist undercoat described above, and is specifically as follows.

[0052] The method for manufacturing a semiconductor device according to this embodiment is: A step of forming a resist underlayer on a substrate using a resin composition for resist underlayers containing naphthol resin having repeating units represented by general formula (1), The process of forming a resist upper film on the resist lower film, The process of exposing the resist film and developing it to form a resist pattern, A step of etching the resist underlayer using the resist pattern, A step of processing the substrate using the etched resist underfilm, Includes. The following explains the details of each step.

[0053] First, the resin composition for the resist underlayer of this embodiment is coated onto a substrate by a spin coating method or the like, similar to known photoresists, to form a resist underlayer film. After coating, the organic solvent is evaporated and baking may be performed to reduce mixing with the upper resist film described later. The baking temperature may be 80 to 300°C for 10 to 300 seconds.

[0054] The thickness of the resist underlayer can be set as appropriate, but 30 to 20,000 nm is preferred, and 50 to 15,000 nm is more preferred.

[0055] Examples of substrates include glass substrates, silicon wafers, ceramic substrates, aluminum substrates, SiC wafers, GaN wafers, copper substrates, and copper-plated substrates. The substrate may be an unprocessed substrate or a substrate with electrodes or elements formed on its surface.

[0056] Next, a resist top layer is formed on the resist underlayer. As the resist film, known photoresist materials can be used, and the resist film can be formed by methods such as spin coating, similar to known photoresists.

[0057] The thickness of the film on the resist can be set as appropriate, but 20 to 500 nm is preferred, and 50 to 400 nm is more preferred.

[0058] Subsequently, the resist film is exposed to light and developed to form a resist pattern. Exposure is typically performed by irradiating the resist film with active light through a suitable photomask. Examples of active light include X-rays, electron beams, ultraviolet light, and visible light. Light with a wavelength of 200-500 nm is preferred. For pattern resolution and ease of handling, the light source is preferably the g-line, h-line, or i-line of a mercury lamp. Alternatively, two or more light rays may be mixed and used. Preferred exposure apparatuses include contact aligners, mirror projection systems, or steppers. A resist pattern can be obtained by developing the exposed resist film with a suitable developer. Development can be performed using methods such as immersion, paddle, or rotary spray. During development, the exposed areas of the resist film are usually dissolved and removed by the developer, resulting in a positive-type resist pattern.

[0059] The usable developing solution is typically an alkaline aqueous solution. Specifically, examples of alkaline aqueous solutions include (i) inorganic alkaline aqueous solutions such as sodium hydroxide, sodium carbonate, sodium silicate, and ammonia; (ii) organic amine aqueous solutions such as ethylamine, diethylamine, triethylamine, and triethanolamine; and (iii) aqueous solutions of quaternary ammonium salts such as tetramethylammonium hydroxide and tetrabutylammonium hydroxide.

[0060] Next, the resist layer is etched using the obtained resist pattern. The resist underlayer is preferably formed by dry etching, using a plasma of a gas that is reactive with the object to be etched. The gas can be one or more selected from inert gases such as He and Ar, or from O2, CO, CO2, NH3, SO2, N2, NO2, and H2 gases, with oxygen gas being particularly preferred. Other gases may also be mixed with the oxygen gas.

[0061] A desired semiconductor device can be obtained by processing the substrate using the etched resist underlayer. Examples of substrate processing include etching with a halogen-based gas using a patterned resist underlayer film, and ion implantation into the substrate.

[0062] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted. [Examples]

[0063] The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited thereto.

[0064] <Examples and Comparative Examples> (1)Synthesis Each naphthol resin shown in Table 1 was synthesized using the following procedure. The weight-average molecular weight (Mw) was measured using gel permeation chromatography (GPC) to obtain a polystyrene equivalent.

[0065] <Polymerization of naphthol resin A1> In a reactor equipped with a reflux condenser and stirrer, 500 g of p-xylylene glycol dimethyl ether, 400 g of β-naphthol, 210 g of biphenol, 270 g of ethylene glycol monomethyl ether, and 2 g of diethyl sulfate were added and mixed and stirred, and the temperature was raised to 140°C. The reaction was carried out for 60 minutes while draining the methanol produced from the system. The temperature was then raised to 160°C, and the reaction was carried out for 180 minutes while continuing to drain the methanol from the system. The mixture was neutralized by adding 1.8 g of triethylamine, then 1000 g of pure water was added and allowed to stand. After separating the two layers, the aqueous layer was removed by washing four times. Subsequently, the temperature was raised to 200°C while reducing the pressure to 68 cmHg and discharging volatile components from the system. Then, 2000 g of propylene glycol 1-monomethyl ether 2-acetate was added to obtain 2700 g of a resin solution (non-volatile content 31%) containing naphthol resin A1 (naphthol aralkyl biphenol resin, Mw: 5100) having repeating units shown in the following formula (A1).

[0066] [ka]

[0067] <Polymerization of naphthol resin A2> Except for using 400 g of p-xylylene glycol dimethyl ether, 2600 g of naphthol resin A2 (naphthol aralkyl biphenol resin, Mw: 2700) having the repeating units shown in formula (A1) was obtained in the same manner as for naphthol resin A1 described above.

[0068] <Polymerization of naphthol resin A3> Except for replacing biphenol with phenol, the same method as for naphthol resin A1 was used for synthesis, yielding 2650 g of naphthol resin A3 (naphthol aralkyl phenol resin, Mw: 4500) having the repeating units shown in the following formula (A3).

[0069] [ka]

[0070] <Polymerization of naphthol resin B> In a reactor equipped with a reflux condenser and stirrer, 400 g of p-xylylene glycol dimethyl ether, 500 g of β-naphthol, and 2 g of diethyl sulfate were added, mixed and stirred, and the temperature was raised to 140°C. The reaction was carried out for 60 minutes while the methanol produced was discharged from the system. The temperature was then raised to 160°C, and the reaction was carried out for 180 minutes while the methanol was continued to be discharged from the system. The mixture was neutralized by adding 1.8 g of triethylamine, then 1000 g of pure water was added and allowed to stand. After separating the two layers, the aqueous layer was removed by washing four times. Subsequently, the temperature was raised to 200°C while reducing the pressure to 68 cmHg and discharging volatile components from the system. Then, 2000 g of propylene glycol 1-monomethyl ether 2-acetate was added to obtain 2750 g of a resin solution (non-volatile content 27%) containing naphthol resin (B) (naphthol aralkyl resin, Mw: 3200) having repeating units shown in the following formula (B).

[0071] [ka]

[0072] (2) Structural analysis Regarding naphthol resins A1 to A3, under the following conditions: 1 1H-NMR was measured.

[0073] < 1 H-NMR measurement conditions> Equipment: JEOL Ltd. JNM-ECA400 Solvent: Deuterated acetone Pulse angle: 45° Sample concentration: 3 wt% Total number of times: 16

[0074] As a result, peaks were observed at 3.5-4.5 ppm and 6.5-8.0 ppm. The presence of methylene crosslinking due to the 3.5-4.5 ppm peak and the presence of an aromatic ring peak due to the 6.5-8.0 ppm peak confirmed the structures of naphthol resins A1-A3. Note that Figure 1 shows the resin of A1. 1 The results of the 1H-NMR measurement are shown.

[0075] (3) Measurement and evaluation The following measurements and evaluations were performed on naphthol resins A1-A3 and B. The results are shown in Table 1.

[0076] [Softening point] Measurements were taken in accordance with the ring-sphere method described in JIS K7234.

[0077] [Onishi Parameters] The Onishi parameter was calculated using the following equation (2). Onishi parameter = N / (N C -N O ) (2) (In equation (2), in the monomer corresponding to the repeating unit, the total number of atoms is N and the total number of carbon atoms is N C , total oxygen number N O (Let's assume that.)

[0078] [Gelation time] The measurement was performed in accordance with the "gelation time" described in "JIS K 6910 Test Methods for Phenolic Resins".

[0079] Resist film compositions were prepared using the naphthol resins of the examples and comparative examples by known methods, and their etching resistance was evaluated. Examples 1 to 3, which used naphthol resins A1 to A3, showed superior etching resistance compared to Comparative Example 1, which used naphthol resin B.

[0080] [Table 1]

Claims

1. A naphthol resin having repeating units represented by the following general formula (1). 【Chemistry 1】 (In formula (1), A represents phenols. n is an integer from 1 to 30.)

2. The naphthol resin according to claim 1, Naphthol resin having an Onishi parameter of 1.95 or higher, which can be calculated using the following formula (2). Onishi parameter = N / (N) Ｃ -N Ｏ ) (2) (In formula (2), in the monomer corresponding to the repeating unit, the total number of atoms is N and the total number of carbon atoms is N Ｃ Total oxygen number N Ｏ (Let's assume that.)

3. The naphthol resin according to claim 1 or 2, Naphthol resin with a softening point of 90-150°C.

4. The naphthol resin according to claim 1 or 2, Naphthol resin with a weight-average molecular weight of 2,000 to 50,000.

5. A resin composition for a resist undercoat, comprising the naphthol resin according to claim 1 or 2.

6. A resin composition for a resist undercoat according to claim 5, A resin composition for resist undercoats, further comprising a crosslinking agent.

7. A resin composition for a resist undercoat according to claim 5, A resin composition for a resist undercoat, further comprising an acid generator.

8. A step of forming a resist underlayer on a substrate using the resist underlayer resin composition described in claim 5, The process of forming a resist upper film on the resist lower film, The process of exposing the resist film and developing it to form a resist pattern, A step of etching the resist underlayer using the resist pattern, A step of processing the substrate using the etched resist underfilm, A method for manufacturing a semiconductor device, including the method described above.

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