TWI781943B - Method for producing coating composition and method for producing photoresist laminate - Google Patents

Abstract

The present invention provides a composition for coating that can increase the film thickness without increasing the concentration of film constituent substances in a coating liquid and without using additives such as thickeners. In the present invention, a coating composition is obtained by filtering a solution to be treated containing a fluorine-containing polymer and a solvent through a filter material with a fluorine atom content of 70% by mass or less. The above-mentioned fluorine-containing polymer has -[CX ¹ X ² -CY ¹ (Rf ¹ -COOM ¹ )] - unit indicated. X ¹ and X ² are H, F or Cl; Y ¹ is H, F, Cl, methyl or trifluoromethyl; Rf ¹ is a perfluoroalkylene group that may contain an etheric oxygen atom between carbon-carbon atoms , or an oxyperfluoroalkylene group that may contain an etheric oxygen atom between carbon-carbon atoms; -COOM ¹ is -COOH or COOZ ¹ (Z ¹ is an ammonium ion that can be replaced by a hydrogen atom).

Description

Method for producing coating composition and method for producing photoresist laminate

The present invention relates to a method for producing a coating composition, in particular to a method for producing a coating composition useful for forming an antireflection film on a photoresist layer. It also relates to a method for manufacturing a photoresist laminate with an antireflection film on its surface.

Optical lithography is used in the manufacturing process of semiconductors, for example, a step of forming a resist pattern is included in the manufacturing process of semiconductor circuits. When the photoresist layer formed on the substrate is irradiated with exposure light, in addition to the light incident on the photoresist layer, reflected light from the surface of the substrate and light reflected on the surface of the photoresist layer by the reflected light are also generated. , the reflected light will form interference and produce standing waves. Such standing waves cause dimensional fluctuations, shape collapse, and the like of photoresist patterns. In addition, there may be a case where a fine photoresist pattern is formed on a surface with a difference in height. In this case, especially the dimensional change or shape collapse caused by the standing wave is exacerbated (standing wave effect).

So far, as a method of suppressing the standing wave effect, a method of adding a light absorbing agent to the photoresist material, a method of disposing an anti-reflection film on the upper surface of the photoresist layer (TARC method), and disposing an antireflection film on the lower surface of the photoresist layer have been proposed. Membrane method (BARC method), etc. The TARC method or BARC method is a method in which an anti-reflection film layer with a lower refractive index than the photoresist layer is placed adjacent to the photoresist layer, and the lower the refractive index of the anti-reflection film, the higher the anti-reflection effect can be obtained.

Patent Document 1 describes a composition that can be used as a coating composition used in the TARC method. The composition is made by polymerizing CF ₂ ═CFOCF ₂ CF ₂ CF ₂ COOCH ₃ to obtain a linear oxy-perfluoro After the alkylene group is used as the side chain precursor polymer, the methyl ester group at the end of the side chain of the precursor polymer is converted into -COOH to obtain a polymer, and the polymer is dissolved in a mixed solvent of water and methanol.

It is known that generally in the TARC method, in order to obtain an excellent anti-reflection effect, the ideal refractive index of the anti-reflective film is the square root (√n) of the refractive index n of the photoresist layer, and the ideal film thickness is λ/4m(λ is the wavelength of the radiation, and m is an odd multiple of the refractive index of the antireflection film (for example, paragraph [0004] of Patent Document 2). Prior Art Documents Patent Documents

Patent Document 1: Japanese Patent No. 3965740 Patent Document 2: Japanese Patent No. 4910829

SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION In recent years, miniaturization of semiconductor circuits has been continuously pursued along with the high integration and high speed of LSIs. In order to meet such demands, the wavelength reduction of the exposure light source used for forming a resist pattern continues. For example, in the mass production process of 64M-bit DRAM (Dynamic Random Access Memory), KrF excimer laser (248nm) is used as the exposure light source, while in the manufacture of 256M-bit or more than 1G-bit DRAM, ArF excimer laser (193nm) or F2 laser (157nm ₎ with shorter wavelength is used.

If semiconductor circuits are miniaturized as mentioned above, even tiny defects that are almost negligible on the conventionally thicker line widths will be greatly affected. Therefore, TARC requires a high anti-reflection effect that can suppress even such small defects, and the technology of finer adjustment of the film thickness of the anti-reflection film becomes more and more important. As a method of adjusting the film thickness of the antireflection film, for example, a method of reducing the concentration of the film constituent substance in the coating liquid in order to reduce the film thickness is effective and simple. On the other hand, to increase the film thickness, increasing the concentration of film constituent substances is the easiest method, but it will increase the viscosity of the coating liquid and increase the burden on the device. As a result, the number of processes will increase and the cost will increase significantly. Therefore, although a method of increasing the viscosity by adding a thickener can be considered, there is a problem that the refractive index of the antireflection film increases when the thickener is added. The subject of the present invention is to provide a method for producing a coating composition and a method for producing a photoresist laminate using the composition, which can reduce the film thickness without increasing the concentration of film constituent substances and without using additives such as thickeners. thickened. means to solve problems

The present invention provides a method for producing and using a coating composition having the following constitutions [1] to [12], and a method for producing a photoresist laminate. [1] A method for producing a coating composition, characterized in that the coating composition is obtained by filtering a solution to be treated containing a fluorine-containing polymer and a solvent through a filter medium having a fluorine atom content of 70% by mass or less. Fluoropolymers have units represented by the following formula (1): -[CX ¹ X ² -CY ¹ (Rf ¹ -COOM ¹ )]- ･･･(1) (wherein, X ¹ and X ² independently represent hydrogen atom, fluorine atom or chlorine atom; Y ¹ represents a hydrogen atom, fluorine atom, chlorine atom, methyl or trifluoromethyl; Rf ¹ represents a linear or branched chain that may contain an etheric oxygen atom between carbon-carbon atoms Dendritic perfluoroalkylene groups, or linear or branched oxyperfluoroalkylene groups that may contain etheric oxygen atoms between carbon-carbon atoms, and the number of carbon atoms in Rf ¹ does not have the aforementioned etheric oxygen atoms When it is 1~10, it is 2~10 when it has the aforementioned etheric oxygen atom; -COOM ¹ means -COOH or COOZ ¹ (Z ¹ is an ammonium ion that can be substituted)).

[2] The production method according to [1], wherein X ¹ , X ² and Y ¹ are all fluorine atoms. [3] The production method according to [1] or [2], wherein the content of the units represented by the aforementioned formula (1) is 50 to 100 mol% with respect to the total units constituting the fluoropolymer. [4] The production method according to any one of [1] to [3], wherein the number average molecular weight of the fluoropolymer is 1,000 to 30,000. [5] The production method according to any one of [1] to [4], wherein the content of the fluoropolymer in the solution to be treated is 1 to 25% by mass. [6] The production method according to any one of [1] to [5], wherein the solvent is water, a hydrophilic organic solvent, or a mixed solvent of water and a hydrophilic organic solvent. [7] The production method according to any one of [1] to [6], wherein the filter material is polyvinylidene fluoride, polyamide, polypropylene or glass fiber. [8] The production method according to any one of [1] to [7], wherein the filter material has a pore diameter of 0.2 to 5.0 μm.

[9] A method of using the coating composition, which is to use the coating composition prepared by the production method of any one of the above-mentioned [1] to [8] to form a coating on the surface of the photoresist layer. anti-reflective film. [10] A method for producing a photoresist laminate, characterized in that: a coating containing the composition is obtained from the coating composition prepared by the production method according to any one of the aforementioned [1] to [8]. coating solution, and then coating the aforementioned coating solution on the surface of the photoresist layer to manufacture a photoresist laminate with an anti-reflection film on the surface of the photoresist layer. [11] The production method according to [10], wherein the content of the polymer containing the fluoropolymer in the coating solution is 1 to 10% by mass, and the content of the fluoropolymer in the polymer content is 50% ~100% by mass. [12] The production method according to [10] or [11], wherein the coating liquid is applied by a spin coating method. Invention effect

According to the production method of the coating composition of the present invention, a coating composition that can increase the film thickness without increasing the concentration of film constituent substances and without using additives such as thickeners can be produced. According to the manufacturing method of the photoresist laminated body of the present invention, the antireflection film formed on the surface of the photoresist layer can be thickened without increasing the concentration of the film constituent substances in the coating solution and without using additives such as thickeners. thick.

Modes for Carrying Out the Invention [Method for Producing Coating Composition] In the method for producing the coating composition of the present invention, a unit having the above formula (1) (hereinafter also referred to as "unit (1) )")) (hereinafter also referred to as "fluoropolymer (A)") and a solvent to be treated are filtered, and the obtained filtrate is used for a coating composition. The coating composition may contain polymers other than the fluorinated polymer (A) (hereinafter also referred to as "other polymers") within the range that does not impair the effect of the present invention. Fluoropolymers are sometimes collectively referred to as "polymers" together with other polymers. When other polymers are contained in the coating composition, they may be added before or after filtration. From the viewpoint of improving the stability of the composition, it is preferable to add it before filtration. The coating composition may contain components other than the aforementioned polymers (hereinafter also referred to as "other components") as needed. When other components are contained in the coating composition, they may be added before filtration or after filtration. From the viewpoint of improving the stability of the composition, it is preferable to add it before filtration.

In unit ( ¹ ), X1 and X2 each independently represent a ^hydrogen atom, a fluorine atom or a chlorine atom. From the viewpoint of easy availability of raw materials, hydrogen atoms or fluorine atoms are preferred. From the point of view that the content of fluorine atoms in the fluoropolymer (A) is high enough and the short ^- wavelength band refractive index of the antireflection film made by using the fluoropolymer ( ^A ) is likely to be low, X1 and X2 are in the range of Fluorine atoms are preferred. Y ¹ represents a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group or a trifluoromethyl group. From the viewpoint of easy availability of raw materials, fluorine atoms are preferable.

Rf ¹ is a linear or branched perfluoroalkylene group, or a linear or branched oxyperfluoroalkylene group. The perfluoroalkylene group or oxyperfluoroalkylene group may contain an etheric oxygen atom between carbon-carbon atoms. Perfluoroalkylene refers to a group in which all the hydrogen atoms bonded to the carbon atoms of the alkylene group are replaced by fluorine atoms. The oxyperfluoroalkylene group refers to that the perfluoroalkylene group is bonded to the carbon atom to which Y1 in formula ( ¹ ) is bonded via an ether bond (-O-). "Containing an etheric oxygen atom between carbon-carbon atoms" means that an ether-bonding oxygen atom is inserted in the middle of the carbon chain (between carbon-carbon atoms) constituting the perfluoroalkylene group or oxyperfluoroalkylene group. When Rf ¹ does not have an etheric oxygen atom between carbon-carbon atoms, the carbon number of Rf ¹ is 1-10, preferably 1-6, especially preferably 3-6. The carbon number of Rf ¹ is ^{2~10, preferably 2~6, especially 3~6, when Rf 1 has} an etheric oxygen atom between carbon-carbon atoms. If the carbon number is above the lower limit of the aforementioned range, the content of fluorine atoms in the fluoropolymer (A) will become sufficiently high, and the short-wavelength antireflection film made of the fluoropolymer (A) will The refractive index in the ribbon will become lower. When this carbon number is below the upper limit of the said range, the solubility with respect to water of a fluoropolymer (A) is excellent.

In unit (1), -COOM ¹ is -COOH or COOZ ¹ (Z ¹ is an ammonium ion which may be substituted by a hydrogen atom). Z ¹ is NH ₄ ⁺ , or one or more hydrogen atoms of NH ₄ ⁺ are substituted with an alkyl group or an alkyl group having a hydroxyl group. The alkyl group is preferably an alkyl group with 1 to 6 carbon atoms. Z ¹ is preferably -NR ¹ R ² R ³ R ⁴⁺ (R ¹ to R ⁴ are each independently a hydrogen atom or an alkyl group with 1 to 3 carbons), especially from the viewpoint of being applicable to various purposes and low cost Viewpoint is best with NH ₄₊ ^.

As a desirable example of the unit (1), the following units (a1)-(a6) are mentioned.

[chemical 1]

The fluorine-containing polymer (A) may also contain a unit not containing -COOM ¹ (hereinafter also referred to as "unit (2)"). Unit (2) can be polymerizable perfluorinated compounds such as fluoroethylenes such as CF ₂ =CF ₂ , CH ₂ =CF ₂ , CF ₂ =CFCl, perfluorovinyl ethers, perfluoroolefins with 3 or more carbon atoms A class is a unit of a subject, etc.

Relative to the total units constituting the fluoropolymer (A), the content of the unit (1) in the fluoropolymer (A) is preferably at least 50 mol%, preferably at least 70 mol%, especially 100 mol%. good. When the content of the unit (1) is more than the lower limit of the aforementioned range, the solubility of the fluoropolymer (A) to an aqueous alkali solution is excellent.

The number average molecular weight of the fluoropolymer (A) is preferably 1,000-30,000, more preferably 1,500-5,000, and especially preferably 2,500-3,500. When the number average molecular weight is more than the above lower limit, the fluoropolymer (A) has excellent film-forming properties and excellent uniformity of film thickness in the flat portion. If it is below the aforementioned upper limit, the fluorine-containing polymer (A) is excellent in compliance with height differences during coating, so that when the surface of the photoresist layer has unevenness, it is necessary to cover the entire surface of the protrusions and recesses. A small amount of coating is sufficient. It also has excellent solubility in alkaline aqueous solution.

The method for producing a polymer in which -COOM ¹ is -COOH which is the fluoropolymer (A) is not particularly limited, but the following method (1) or method (2) is preferable. Method (1): After polymerizing a monomer having a precursor functional group that can be converted to "-COOH" to polymerize a precursor polymer, the method of converting the precursor functional group to "-COOH". Method (2): After polymerizing a fluorine-containing monomer without a precursor functional group, introduce "-COOH" into a part of the polymer.

Method (1) can be exemplified as follows: CX ¹ X ² =CY ¹ (Rf ¹ -COOCH ₃ ) [Here, X ¹ , X ² , Y ¹ , Rf ¹ are the same as formula (1)] After polymerizing the fluorine-containing monomer (hereinafter also referred to as "fluorine-containing monomer (1)") to obtain a precursor polymer, the -COOCH ₃ part is hydrolyzed.

The method for obtaining the fluoropolymer (A) by hydrolyzing the -COOCH ₃ moiety of the precursor polymer is not particularly limited. Examples include stirring the precursor polymer together with water or a medium containing water. And the aforementioned stirring is preferably implemented under heating. At this time, the temperature of the water or the aforementioned medium should be 50~150°C. The aforementioned medium is preferably a mixed solvent of water and a hydrophilic organic solvent. Alcohols are preferred as the hydrophilic organic solvent from the viewpoint of excellent solubility in water, and among them, fluorine-containing alcohols are preferred from the viewpoint of excellent solubility with the precursor polymer. The fluorine-containing alcohol is preferably a compound with a fluorine atom content of more than 50% by weight, such as 2-(perfluorobutyl)ethanol, 2-(perfluorohexyl)ethanol, hexafluoroisopropanol, 2,2,3 , 3-Tetrafluoropropanol, etc. The mass ratio of water in the mixed solvent to the hydrophilic organic solvent is preferably 3:7~9:1, especially 4:6~6:4. When it is the said range, a precursor polymer will dissolve easily.

As an example of method (2), the following method can be cited: After polymerizing the fluorine-containing monomer represented by CX ¹ X ² =CY ¹ (Rf ¹ -CCl ₃ ), sulfuric acid and water are added to convert -CCl ₃ into COOH .

The method for producing a polymer that is both a fluorine-containing polymer (A) and -COOM ¹ is -COOZ ¹ can be exemplified as follows: a polymer with -COOH is prepared by method (1) or method (2), and then adding Ammonia or an organic amine to convert -COOH to -COOZ ¹ . Examples of organic amines include monoalkylamines such as ethylamine and propylamine; dialkylamines such as diethylamine; trialkylamines such as triethylamine; and alkanolamines such as ethanolamine and diethanolamine. These may be used individually by 1 type and may use 2 or more types together.

Examples of other polymers include polyacrylic acid. The number average molecular weight of other polymers is preferably 1,000-30,000, more preferably 1,500-5,000, and most preferably 2,500-3,500. In the present invention, the total of the fluoropolymer (A) and other polymers is referred to as the polymer content. In the polymer content, the content of the fluoropolymer (A) is preferably at least 50% by mass, preferably at least 70% by mass, particularly preferably 100% by mass.

Surfactants and additives other than surfactants may be contained as other components within the range that does not impair the effects of the present invention. The surfactant helps to improve, for example, wettability at the time of coating, uniformity of formed film. Surfactants include, for example, amine salts of fluorine-based organic acids. Specifically, compounds having polyfluoroalkyl groups and polyoxyethylene groups (manufactured by 3M Corporation, product names: Fluorad "FC-430", "FC-4430", etc.), acetylene glycol, and addition thereof Polyoxyethylene compounds (manufactured by Air Products, product names: "Surfynol 104", "Surfynol 420"), alkylsulfonic acids and alkylbenzenesulfonic acids (such as Nikko Chemicals, product names: NIKKOL "SBL-2N -27", etc.) and compounds containing hydroxyl groups and not containing polyoxyethylene groups (polyglyceryl fatty acid esters, etc.). If the content of the surfactant is too high, it may cause the whitening of the anti-reflection film, and further diffuse into the photoresist film under the anti-reflection film, causing poor exposure. In addition, the addition of surfactants other than perfluorinated compounds will increase the refractive index of the antireflection film, so the content of surfactants should be less than 10% by mass, preferably less than 5% by mass, relative to the polymer content.

Additives other than the surfactant include well-known additives for coating compositions for antireflection film formation. Specific examples include photoacid generators such as onium salts, halogenated alkyl-containing compounds, o-quinone diazide compounds, nitrobenzyl compounds, sulfonate compounds, and phosphonium compounds. Since the addition of additives other than perfluorinated compounds will increase the refractive index of the antireflection film, the total content of additives other than surfactants in the coating composition is preferably 10% by mass or less, 5% by mass or less in the polymer content Excellent.

The solution to be treated to be filtered by the filter material contains the fluoropolymer (A) and the solvent. And the fluorine-containing polymer (A) is preferably produced by the aforementioned method (1) or method (2). The solvent in the solution to be treated is preferably water, a hydrophilic organic solvent, or a mixed solvent of water and a hydrophilic organic solvent. Examples of the hydrophilic organic solvent include alcohols such as methanol, ethanol, isopropanol, 2-butanol, and fluorine-containing alcohols. The fluorine-containing alcohols are exemplified by the fluorine-containing alcohols listed as the hydrophilic organic solvent used in the aforementioned hydrolysis. The solvent in the solution to be treated may be the solvent used in the production of the fluoropolymer (A), or the solvent added after the production of the fluoropolymer (A), or a mixture of the two. That is, the liquid obtained by producing the fluoropolymer (A) using a solvent can be subjected to filtration as a solution to be treated. A solvent may be added to a liquid obtained by producing the fluorinated polymer (A) using a solvent to make a solution to be treated. A solvent may be added to the liquid obtained by producing the fluorine-containing polymer (A) using a solvent, after drying, as a solution to be treated. Moreover, the fluorine-containing polymer (A) can also be produced without using a solvent, it can make it dry as needed, and a solvent can be added and it can make it the solution to be processed.

The content of the fluoropolymer in the solution to be treated is preferably 1-25% by mass, more preferably 1-10% by mass, especially preferably 2-5% by mass. If the content of the fluoropolymer is above the lower limit of the aforementioned range, the film thickness of the antireflection film will become thick enough, and if it is below the upper limit, the filtration time will be shortened because the viscosity of the solution will become sufficiently low, and Not prone to blockage and other failures.

In the present invention, the solution to be treated is filtered using a filter material with a fluorine atom content of 70% by mass or less. The content of the fluoropolymer in the filtrate hardly changed even after filtration. By reducing the fluorine atom content of the filter material, the film thickness of the coating solution containing the filtrate will increase when the film is formed. The fluorine atom content of the filter material is preferably less than 70% by mass, more preferably less than 60% by mass. Can also be zero. If the fluorine atom content of the filter material is 70% by mass or less, the film thickness increase due to filtration is sufficiently large, so it is effective as a method for controlling the film thickness. Examples of the filter material having a fluorine atom content of 70% by mass or less include organic materials such as polyvinylidene fluoride (PVDF), polyamide, polypropylene (PP), and inorganic materials such as glass. Organic materials are preferable from the viewpoint that the possibility of increasing the concentration of metal impurities in the composition is low. When one filter material is composed of two or more materials with different fluorine atom contents, it is only necessary that the fluorine atom content of at least one material is within the aforementioned range.

The pore diameter of the filter material is preferably 0.2-5.0 μm, more preferably 0.2-1.0 μm, especially 0.2-0.5 μm. The shape of the filter material and the filtering method are not particularly limited. It can be carried out using well-known filtering devices and filtering methods. And the filtration can be carried out at normal temperature. For example, pressurized filtration using a capsule filter, which is generally used, is also effective. Although the filtration speed (linear speed) is not particularly limited, it is, for example, 0.001 to 1.0 cm/sec, preferably 0.003 to 0.5 cm/sec.

[Coating Liquid] The coating liquid in the present invention can be prepared using the aforementioned coating composition. The term "coating liquid" refers to a solution that is applied on an object to be coated (photoresist layer, etc.). The coating liquid may use the coating composition as it is, or may further add a solvent for use. The solvent in the coating solution is ideally the same as the solvent in the solution to be treated. Some or all of the above-mentioned other polymers and the above-mentioned other components are not contained in the coating composition but are added when preparing the coating liquid. It is also possible to make the above-mentioned other polymer and part of the above-mentioned other components contained in the composition for coating, and to add the rest when preparing a coating liquid. The polymer content in the coating liquid is preferably 10% by mass or less, preferably 7% by mass or less, particularly preferably 5% by mass or less, from the viewpoint of excellent coatability. From the viewpoint of easily forming an antireflection film having a necessary film thickness, it is preferably at least 1% by mass, preferably at least 2% by mass, and particularly preferably at least 4% by mass. The content of the fluoropolymer (A) is preferably at least 50% by mass, preferably at least 70% by mass, particularly preferably 100% by mass, based on the total of the fluoropolymer (A) and other polymers in the coating liquid .

[Manufacturing method of photoresist laminate] In the present invention, the so-called photoresist laminate system refers to a laminate provided with an antireflection film on the surface of the photoresist layer. The manufacturing method of the photoresist laminate of the present invention is to prepare the coating composition by the manufacturing method of the present invention, then prepare the coating liquid containing the aforementioned coating composition, and then apply the aforementioned coating liquid, and Manufacture a photoresist laminate with an antireflection film on the surface of the photoresist layer.

As a method of coating the coating liquid on the surface of the photoresist layer, a well-known method can be used. From the viewpoint of the uniformity of the antireflection film and the ease of manufacture, the spin coating method is preferable. After the coating liquid is applied, the solvent is removed as necessary. The method for removing the solvent is preferably heating and drying using, for example, a hot plate or an oven. In terms of drying conditions, for example, when using a hot plate, it is better to carry out at a temperature of 80-150°C for 5-30 minutes.

The method for producing a photoresist laminate of the present invention can be suitably used in the following method: forming a photoresist layer on a substrate, forming an anti-reflection film on the surface of the photoresist layer to make a photoresist laminate, and using the photoresist After the laminate is exposed, it is developed using an aqueous alkali solution to form a photoresist pattern. The coating liquid prepared by the manufacturing method of the present invention is used to form the aforementioned anti-reflection film, whereby the standing wave effect is suppressed and the dimensional change and shape collapse of the photoresist pattern can be suppressed. In addition, the anti-reflection film has good solubility in alkaline aqueous solution, so that the development and removal of the anti-reflection film can be carried out at the same time. Also, when the photoresist layer is a so-called chemically amplified photoresist (using the catalytic effect of protons generated by exposure), if the photoresist layer is left in the atmosphere after exposure, the photoresist surface will easily deteriorate. If there is an antireflection film obtained by the manufacturing method of the present invention on the surface of the photoresist layer, it can also function as a protective film to prevent the surface of the photoresist layer from deteriorating.

[Function, Mechanism] According to the present invention, as shown in the following examples, the composition for coating obtained by filtering the filter material with a fluorine atom content of 70% by mass or less is directly used as the coating composition before filtering. In comparison with the case of coating the composition, even if the polymer content is the same, the film thickness at the time of film formation will become thicker. Although the reason for obtaining such an effect is not clear, it is clearly known after the inventors of this case have investigated the composition changes before and after filtration in detail: when the fluorine atom content of the filter material is 70% by mass or less, after the filtration operation, at ¹⁹ F- In NMR, the content of the compound having a peak around -119 (minus 119) ppm based on chlorotrifluoromethane (hereinafter also referred to as "compound of -119 ppm") was significantly reduced. It is believed that a reduction in the content of this compound contributes to an increase in film thickness. It is also believed that this compound is easily adsorbed on filter materials with a fluorine atom content of 70% by mass or less. Specifically, the content of the -119 ppm compound in the coating liquid is preferably less than 0.95% by mass. Example

The following examples are used to further describe the present invention in detail, but the present invention is not limited to these examples. As the measurement method and evaluation method, the following methods were used.

[Number Average Molecular Weight] The value of the number average molecular weight of the polymer is a polystyrene (PS) equivalent molecular weight obtained by gel permeation chromatography (GPC) method. [Polymer content] 2 mL of the composition for coating was collected into a vial container (20 mL), and vacuum-dried at 80° C. for 3 hours. Calculate the polymer content in the solution by measuring the mass of the sample bottle before and after drying (unit: mass %). [Film thickness and refractive index] Spin coating (3,000 revolutions per minute, 180 seconds) to coat the coating solution on the silicon wafer, and dry it on a hot plate adjusted to 150°C for 5 minutes to form film (anti-reflection film). The film thickness and the refractive index at 193 nm were measured by an ellipsometer. The usage amount of the coating liquid is stipulated as 2mL. Here, the usage-amount of coating liquid and coating conditions were prescribed|regulated uniformly, and the film thickness of the obtained film was compared.

"Compound content of -119ppm" Mix heavy water and 1,1,1,3,3,3-hexafluoro-2-isopropanol (HFIP) in the coating composition, and adjust to make the polymer content ¹⁹ F-NMR was measured after reaching 2% by mass. From the obtained graph, the content (unit: mass %) of the compound having a peak near -119 ppm (compound of -119 ppm) was calculated using HFIP as a standard substance and based on chlorofluoromethane.

[Manufacturing Example 1: Manufacture of Fluoropolymer (A1) and Solution (1)] 50 g of CF ₂ =CFOCF ₂ CF ₂ CF _{2 COOCH 3 (molecular weight: 306) and 0.60 g of CF 2 =CFOCF 2 CF 2} COOCH ₃ (molecular weight: 306) and 0.60 g as The diisopropyl peroxydicarbonate solution of the starter solution (concentration: 50% by mass, and the solvent is CF ₃ CH ₂ OCF ₂ CF ₂ H), and then the system was replaced with nitrogen. Next, stirring was carried out while heating so that the internal temperature became 40° C., and a polymerization reaction was performed for 72 hours. After completion of the polymerization reaction, vacuum drying was carried out at 80° C. for 3 hours to obtain 21.5 g of a precursor polymer. The number average molecular weight of the precursor polymer was 3,300. Then, the methyl group at the end of the side chain of the precursor polymer is hydrolyzed and converted into a carboxyl group. That is, the precursor polymer and water were stirred and hydrolyzed at 80°C for 12 hours in a separable flask to obtain an aqueous solution (solution (1)) having a fluoropolymer (A1) content of 18% by mass. The fluoropolymer (A1) monomer can be taken out by vacuum-drying the solution (1) at 80° C. for 3 hours.

[Manufacture Example 2: Manufacture of Treated Solutions (2) to (4) and Coating Compositions Using Them] A treated solution containing the fluoropolymer (A1) obtained in Production Example 1 and in a different solvent was produced Solution (2)~(4). The content of the fluoropolymer in each solution to be treated is set to a concentration that is easy to form a film by spin coating. Preparation of the treated solution (2): The solution (1) was diluted with water to prepare the treated solution (2) with a fluoropolymer (A1) content of 5% by mass. Production of the treated solution (3): The fluoropolymer (A1) monomer was taken out from the solution (1), and 2-butanol was added to prepare a treated solution with a fluoropolymer (A1) content of 3% by mass (3). Preparation of the treated solution (4): Take out the fluoropolymer (A1) monomer from the solution (1), and add 2,2,3,3-tetrafluoropropanol (TFPO) to produce the fluoropolymer ( A1) The solution to be treated (4) having a content of 4% by mass.

Coating compositions (2) to (4) are manufactured using the solutions to be treated (2) to (4), and directly used as coating liquids (2) to (4). Examples 1, 11, and 21 are comparative examples without filtration, examples 2, 12, 17, and 22 are comparative examples in which the fluorine atom content of the filter material exceeds 70%, and examples 3~5, 13~16, and 23~28 are For example. In the filtering step, the following filter materials (1) to (5) with different materials are used as filter materials. The fluorine atom content of each filter material is shown in Table 1~3.

[Used filter material] Filter material (1): The material is polytetrafluoroethylene, manufactured by TOMSIC Corporation, TITAN2-PTFE (product name). In addition, three types of pore sizes of 1.0 μm, 0.45 μm, and 0.2 μm were prepared. Filter material (2): The material is polyvinylidene fluoride, manufactured by TOMSIC, TITAN2-PVDF (product name). In addition, two types of 0.45 μm and 0.2 μm were prepared. Filter material (3): The material is polyamide, manufactured by TOMSIC, TITAN2-NYLON (product name). In addition, three types of pore diameters of 1.5 μm, 0.45 μm, and 0.2 μm were prepared. Filter material (4) PP: The material is polypropylene, manufactured by TOMSIC, TITAN2-Polypropylene (product name). In addition, two types of 0.45 μm and 0.2 μm were prepared. Filter material (5): made of borosilicate glass, TITAN2-Glass Microfiber (product name), manufactured by TOMSIC, with a pore size of 1.0 μm.

[Example 1: No filtration] The solution to be treated (2) was used as the coating solution (2) without filtering it. The polymer content and -119 ppm compound content in the coating solution (2) were measured. In addition, a film was formed by a spin coating method and the film thickness was measured. The results are shown in Table 1 (the same applies hereinafter).

[Example 2~5] Syringe-filter the solution (2) to be treated using the filter material shown in Table 1 at a filtration rate of 0.2 cm/sec, and use the filtrate as the coating solution (2). And carry out the same measurement as Example 1.

[Example 11: No filtration] The solution to be treated (3) was used as the coating solution (3) without filtration. The polymer content and -119 ppm compound content in the coating liquid (3) were measured. And the film was prepared by the spin coating method and the film thickness and refractive index were measured. The results are shown in Table 2 (the same applies hereinafter).

[Examples 12-16] Syringe-filter the solution (3) to be treated using the filter material shown in Table 2 at a filtration velocity (linear velocity) of 0.2 cm/sec, and use the filtrate as the coating solution (3). And carry out the same measurement as Example 11. "-" in the table means not determined (the same applies hereinafter).

[Example 17] A liquid in which polyacrylic acid was added to the treated solution (3) so that the concentration became 0.2% by mass was syringe-filtered using the filter material shown in Table 2 at a filtration speed (linear velocity) of 0.2 cm/sec, and the The filtrate was used as the coating liquid (3). And carry out the same measurement as Example 11.

[Example 21: No filtration] The solution to be treated (4) was used as the coating solution (4) without filtering it. The polymer content in the coating solution (4) was measured. In addition, a film was formed by a spin coating method and the film thickness was measured. The results are shown in Table 3 (the same applies hereinafter).

[Example 22~25] Use the filter material shown in Table 3 to syringe filter the solution (4) to be treated at a filtration speed (linear velocity) of 0.2 cm/sec, and use the filtrate as the coating solution (4). And the same measurement as in Example 21 was carried out.

[Example 26~28] Use a capsule filter equipped with a filter material (4), pressurize and filter the solution to be treated (3) at the filtration rate shown in Table 4, and use the filtrate as the coating solution (5). And carry out the same measurement as Example 1.

[Table 1]

[Table 2]

[table 3]

[Table 4]

Fig. 1 shows the relationship between the -119ppm compound content in the coating liquid and the film thickness after film formation in the chart for Examples 1 to 5.

As shown in the results of Table 1, the fluorine atom content of the filter material is 70% by mass or less in Examples 3-5, and the compound content of -119ppm in the coating solution is less than 0.95% by mass. Compared with Example 1, the polymer content is equal but the film thickness increased significantly. On the other hand, in Example 2 in which the fluorine atom content of the filter material is 76% by mass, the -119ppm compound content in the coating solution is 0.95% by mass or more, and the film thickness difference from Example 1 is small. Specifically, since the average value of the film thickness after film formation in Example 1 is 33.5nm (the number of samples is 5) and 3σ=1.5 (σ is the standard deviation), the film thickness of 35.0nm after film formation in Example 2 is judged as no Significant difference. According to the results in Table 2 and Table 3, the same tendency can be seen in the relationship between the fluorine atom content of the filter material and the film thickness. From the results in Figure 1, it can be seen that there is a relationship between the -119ppm compound content in the coating composition and the film thickness after film formation, and the lower the -119ppm compound content, the thicker the film thickness will become. As shown in Table 2, the compound at -119ppm will be reduced even more when filtered through a filter material with low fluorine atom content. When the material of the filter material is the same, there is a tendency that the smaller the pore size-119ppm compound is, the less it will be. Comparing Examples 11, 12 and 15 in Table 2, it can be seen that even if the content of the -119 ppm compound is reduced by filtration, the refractive index of the film is not affected. In the coating composition obtained in Example 17, polyacrylic acid with a thickening effect was added, so compared with Example 12, although the film thickness was increased, the refractive index was increased. From the results of Examples 15 and 26~28, it can be confirmed that if the filter material and pore size are the same, the film thickness can be increased regardless of the filtration speed and filtration method. By filtering using a filter material having a fluorine atom content of 70% by mass or less as described above, the film thickness can be increased without increasing the polymer content in the coating composition and without using additives such as thickeners. Industrial availability

The coating composition of the present invention is useful for forming an antireflection film provided on the surface of a photoresist layer. In addition, the entire contents of the specification, scope of claims, drawings and abstract of Japanese Patent Application No. 2016-138762 filed on July 13, 2016 are cited here, and incorporated as disclosure of the specification of the present invention.

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Fig. 1 is a graph showing the results of Examples and Comparative Examples.

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Claims (16)

A method for producing a coating composition, characterized in that the coating composition is obtained by filtering a solution to be treated containing a fluorine-containing polymer and a solvent without water through a filter material with a fluorine atom content of 70% by mass or less. The fluorine-containing polymer has a unit represented by the following formula (1): -[CX ¹ X ² -CY ¹ (Rf ¹ -COOM ¹ )]-. ． ． (1) (In the formula, X ¹ and X ² each independently represent a hydrogen atom, a fluorine atom or a chlorine atom; Y ¹ represents a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group or a trifluoromethyl group; Rf ¹ represents - Straight-chain or branched perfluoroalkylene groups containing etheric oxygen atoms between carbon atoms, or linear or branched oxyperfluoroalkylene groups that may contain etheric oxygen atoms between carbon-carbon atoms group, and the carbon number of Rf ¹ is 1~10 when it does not have the aforementioned etheric oxygen atom, and it is 2~10 when it has the aforementioned etheric oxygen atom; -COOM ¹ means -COOH or COOZ ¹ (Z ¹ can be Substituted ammonium ions)). The production method as claimed in item 1, wherein X ¹ , X ² and Y ¹ are all fluorine atoms. The production method according to claim 1 or 2, wherein the content of the units represented by the aforementioned formula (1) is 50-100 mol% relative to the total units constituting the fluoropolymer. The production method according to claim 1 or 2, wherein the number average molecular weight of the fluorine-containing polymer is 1,000-30,000. The production method according to claim 1 or 2, wherein the content of the fluoropolymer in the solution to be treated is 1 to 25% by mass. Such as the production method of claim 1 or 2, wherein the aforementioned solvent The agent is a hydrophilic organic solvent. The production method according to claim 6, wherein the aforementioned hydrophilic organic solvent contains alcohols. The production method according to claim 6, wherein the aforementioned hydrophilic organic solvent comprises: at least one selected from methanol, ethanol, isopropanol, 2-butanol, and fluorine-containing alcohols. The production method according to claim 6, wherein the aforementioned hydrophilic organic solvent contains fluorine-containing alcohol. The manufacturing method as claimed in item 1 or 2, wherein the aforementioned filter material is polyvinylidene fluoride, polyamide, polypropylene or glass fiber. The manufacturing method of claim 1 or 2, wherein the pore size of the aforementioned filter material is 0.2-5.0 μm. The manufacturing method of claim 1 or 2, wherein the aforementioned filter material is polyvinylidene fluoride, polyamide, polypropylene or glass fiber, and the pore size of the aforementioned filter material is 0.2-5.0 μm. A method of using the coating composition, which is to use the coating composition prepared by the manufacturing method according to any one of claims 1 to 12 to form an antireflection film on the surface of the photoresist layer. A method for manufacturing a photoresist laminate, characterized in that: a coating liquid containing the composition is prepared from the coating composition prepared by the manufacturing method according to any one of claims 1 to 12, and then the aforementioned The coating solution is coated on the surface of the photoresist layer to manufacture a photoresist laminate with an anti-reflection film on the surface of the photoresist layer. The manufacturing method as claimed in claim 14, wherein the aforementioned coating The content of the polymer containing the fluoropolymer in the liquid is 1 to 10% by mass, and the content of the fluoropolymer in the polymer content is 50 to 100% by mass. As in the manufacturing method of claim 14 or 15, the aforementioned coating liquid is applied by spin coating.

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