JP7206852B2 - METHOD FOR MANUFACTURING CONDUCTIVE COMPOSITION - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrically conductive composition and a method for producing the same.

Pattern formation technology using charged particle beams such as electron beams and ion beams is expected to be the next-generation technology of photolithography. When using a charged particle beam, it is important to improve the sensitivity of the resist layer to improve productivity.
Therefore, a highly sensitive chemically amplified resist is produced by generating acid in the exposed portion or the portion irradiated with the charged particle beam, followed by a heat treatment called a post-exposure bake (PEB) treatment to promote a cross-linking reaction or a decomposition reaction. usage is prevalent.
In recent years, along with the trend toward miniaturization of semiconductor devices, there has been a demand for control of resist shapes on the order of several nanometers.

By the way, in the pattern formation method using a charged particle beam, especially when the substrate is insulating, the trajectory of the charged particle beam is bent due to the electric field generated by the charge-up of the substrate, and the desired pattern is obtained. There is a problem that it is difficult to
As a means for solving this problem, it is effective to apply a conductive composition containing a conductive polymer to the surface of a resist layer to form a conductive film, and to coat the surface of the resist layer with the conductive film. already known.

Conductive polymers having acidic groups are known as conductive polymers. A conductive polymer having an acidic group can exhibit conductivity without adding a dopant.
For example, Patent Document 1 discloses a conductive composition containing a conductive polymer having an acidic group, a basic compound such as tetrabutylammonium hydroxide, and a solvent.

WO2014/017540

However, when the conductive composition described in Patent Document 1 is applied to a chemically amplified resist, the resist layer may be thinned.
Also, the conductive composition is required to have good coatability when applied onto the surface of the resist layer.
An object of the present invention is to provide a conductive composition that can form a conductive film with good coatability and less film loss of the resist layer, and a method for producing the same.

The inventors of the present invention have found that the use of an organic solvent as a part of the solvent for the electrically conductive composition improves the coatability, but the film thickness of the resist layer tends to decrease in some cases. Then, the inventors have found that by using a specific amount of a purified alcohol-based solvent, it is possible to achieve both improvement in coatability and suppression of film loss, and have completed the present invention.

The present invention has the following aspects.
[1] A conductive composition containing a conductive polymer having an acidic group, water, and a lower alcohol having 1 to 3 carbon atoms, the content of the lower alcohol relative to the total mass of the conductive composition. is 0.1 to 15% by mass, and the content of nitrate ions, sulfate ions, phosphate ions, and propionate ions derived from the lower alcohol is 1000 mass ppm or less with respect to the total mass of the lower alcohol. and the content of calcium, magnesium, and zinc derived from the lower alcohol is 10 mass ppb or less with respect to the total mass of the lower alcohol.
[2] The conductive composition of [1] for antistatic use during charged particle beam drawing.
[3] A method for producing a conductive composition, comprising mixing a conductive polymer having an acidic group, water, and a lower alcohol having 1 to 3 carbon atoms, wherein the total mass of the conductive composition includes On the other hand, the content of the lower alcohol is 0.1 to 15% by mass, and the content of nitrate ions, sulfate ions, phosphate ions, and propionate ions in the lower alcohol is 1000 mass ppm or less. , a method for producing a conductive composition, wherein the contents of calcium, magnesium and zinc in the lower alcohol are each 10 mass ppb or less.

ADVANTAGE OF THE INVENTION According to this invention, the coating property is favorable and the electrically conductive composition which can form an electrically conductive film with little film loss of a resist layer, and its manufacturing method can be provided.

The present invention will be described in detail below. The following embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention only to these embodiments. The present invention can be implemented in various forms without departing from its spirit.

In the present invention, “conductivity” means having a surface resistance value of 1×10 ¹¹ Ω/□ or less. The surface resistance value is obtained from the potential difference between the electrodes when a constant current is passed.
In addition, the term "solubility" as used herein refers to 10 g (liquid temperature 25 ° C.), it means that 0.1 g or more is uniformly dissolved. In addition, "water-soluble" means solubility in water in relation to the above-mentioned solubility.
Moreover, in the present specification, the term "terminal" of the "terminal hydrophobic group" means a site other than the repeating units constituting the polymer.
Moreover, in this specification, "mass average molecular weight" is a mass average molecular weight (converted to sodium polystyrene sulfonate) measured by gel permeation chromatography (GPC).

[Conductive polymer]
The conductive polymer (A) in the present invention has an acidic group. If the conductive polymer (A) has an acidic group, the water solubility will be enhanced. As a result, the coating property of the conductive composition containing the conductive polymer (A) is enhanced, and a coating film having a uniform thickness can be easily obtained.
The conductive polymer (A) is not particularly limited as long as it has at least one group selected from the group consisting of a sulfonic acid group and a carboxyl group in the molecule, as long as it has the effect of the present invention, and is known. of conductive polymers can be used. For example, JP-A-61-197633, JP-A-63-39916, JP-A-1-301714, JP-A-5-504153, JP-A-5-503953, JP-A-4-32848 Publications, JP-A-4-328181, JP-A-6-145386, JP-A-6-56987, JP-A-5-226238, JP-A-5-178989, JP-A-6-293828, JP-A-7-118524, JP-A-6-32845, JP-A-6-87949, JP-A-6-256516, JP-A-7-41756, JP-A-7-48436, JP-A-H9 4-268331, JP-A-2014-65898, and the like are preferable from the viewpoint of solubility.

Specific examples of the conductive polymer (A) include phenylene vinylene substituted with at least one group selected from the group consisting of a sulfonic acid group and a carboxyl group at the α-position or β-position, vinylene, thienylene, A π-conjugated conductive polymer containing, as a repeating unit, at least one selected from the group consisting of pyrrolylene, phenylene, iminophenylene, isothianaphthene, furylene, and carbazolylene.
Further, when the π-conjugated conductive polymer contains at least one repeating unit selected from the group consisting of iminophenylene and galbazolylene, on the nitrogen atom of the repeating unit, from a sulfonic acid group and a carboxy group or an alkyl group substituted with at least one group selected from the group consisting of a sulfonic acid group and a carboxyl group, or an alkyl group containing an ether bond at the nitrogen atom Conductive polymers having thereon may be mentioned.
Among these, from the viewpoint of conductivity and solubility, thienylene, pyrrolylene, iminophenylene, phenylene vinylene, carbazolylene, and β-position substituted with at least one group selected from the group consisting of a sulfonic acid group and a carboxy group. A conductive polymer having, as a monomer unit (unit), at least one selected from the group consisting of isothianaphthene is preferably used.

The conductive polymer (A) contains one or more monomer units selected from the group consisting of units represented by the following general formulas (1) to (4) from the viewpoint of being able to exhibit high conductivity and solubility, A conductive polymer containing 20 to 100 mol % in all units (100 mol %) constituting the conductive polymer is preferred.

In formulas (1) to (4), X represents a sulfur atom or a nitrogen atom, and R ¹ to R ¹⁵ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, linear or branched alkoxy group, acidic group, hydroxy group, nitro group, halogen atom (-F, -Cl, -Br or I), -N(R ¹⁶ ) ₂ , -NHCOR ¹⁶ , of number 1 to 24, represents -SR ¹⁶ , -OCOR ¹⁶ , -COOR ¹⁶ , -COR ¹⁶ , -CHO or -CN; R ¹⁶ represents an alkyl group having 1 to 24 carbon atoms, an aryl group having 1 to 24 carbon atoms, or an aralkyl group having 1 to 24 carbon atoms.
However, at least one of R ¹ and R ² in general formula (1), at least one of R ³ to R ⁶ in general formula (2), and R ⁷ to R ¹⁰ in general formula (3) At least one of them, at least one of R ¹¹ to R ¹⁵ in general formula (4) is an acidic group or a salt thereof.

Here, "acidic group" means a sulfonic acid group (sulfo group) or a carboxylic acid group (carboxy group).
The sulfonic acid group may be contained in an acid state (--SO ₃ H) or in an ionic state (--SO ₃ ⁻ ). Further, the sulfonic acid group also includes a substituent (-R ¹⁷ SO ₃ H) having a sulfonic acid group.
On the other hand, the carboxylic acid group may be contained in an acid state (--COOH) or in an ionic state ( ^--COO.sup.- ). Further, the carboxylic acid group also includes substituents (-R ¹⁷ COOH) having a carboxylic acid group.
R ¹⁷ is a linear or branched alkylene group having 1 to 24 carbon atoms, a linear or branched arylene group having 1 to 24 carbon atoms, or a linear or branched aralkylene group having 1 to 24 carbon atoms. show.

Salts of acidic groups include alkali metal salts, alkaline earth metal salts, ammonium salts, or substituted ammonium salts of sulfonic acid groups or carboxylic acid groups.
Examples of alkali metal salts include lithium sulfate, lithium carbonate, lithium hydroxide, sodium sulfate, sodium carbonate, sodium hydroxide, potassium sulfate, potassium carbonate, potassium hydroxide and derivatives having these skeletons.
Examples of alkaline earth metal salts include magnesium salts and calcium salts.
Examples of substituted ammonium salts include aliphatic ammonium salts, saturated alicyclic ammonium salts and unsaturated alicyclic ammonium salts.
Examples of aliphatic ammonium salts include methylammonium, dimethylammonium, trimethylammonium, ethylammonium, diethylammonium, triethylammonium, methylethylammonium, diethylmethylammonium, dimethylethylammonium, propylammonium, dipropylammonium, isopropylammonium, diisopropyl ammonium, butylammonium, dibutylammonium, methylpropylammonium, ethylpropylammonium, methylisopropylammonium, ethylisopropylammonium, methylbutylammonium, ethylbutylammonium, tetramethylammonium, tetramethylolammonium, tetraethylammonium, tetra-n-butylammonium, tetra sec-butylammonium, tetra-t-butylammonium and the like.
Saturated alicyclic ammonium salts include, for example, piperidinium, pyrrolidinium, morpholinium, piperazinium and derivatives having these skeletons.
Examples of unsaturated alicyclic ammonium salts include pyridinium, α-picolinium, β-picolinium, γ-picolinium, quinolinium, isoquinolinium, pyrrolinium, and derivatives having these skeletons.

The conductive polymer (A) preferably has a unit represented by the above general formula (4) from the viewpoint of being able to express high conductivity, and among them, from the viewpoint of excellent solubility, the following general formula It is more preferable to have a monomer unit represented by (5).

In formula (5), R ¹⁸ to R ²¹ are each independently a hydrogen atom, a straight or branched alkyl group having 1 to 24 carbon atoms, a straight or branched alkoxy group having 1 to 24 carbon atoms, It represents an acidic group, a hydroxy group, a nitro group, or a halogen atom (-F, -Cl, -Br or I). At least one of R ¹⁸ to R ²¹ is an acidic group or a salt thereof.

As the unit represented by the general formula (5), any one of R ¹⁸ to R ²¹ is a linear or branched alkoxy group having 1 to 4 carbon atoms in terms of ease of production, Preferably any one of the other is a sulfonic acid group and the rest are hydrogen.

The conductive polymer (A), from the viewpoint of excellent solubility in water and organic solvents regardless of pH, among all units (100 mol%) constituting the conductive polymer (A), the general formula (5) It preferably contains 10 to 100 mol %, more preferably 50 to 100 mol %, and particularly preferably 100 mol % of the unit represented by.
Moreover, from the viewpoint of excellent conductivity, the conductive polymer (A) preferably contains 10 or more units represented by the general formula (5) in one molecule.

In addition, in the conductive polymer (A), from the viewpoint of further improving the solubility, the number of aromatic rings to which acidic groups are bonded to the total number of aromatic rings in the polymer is preferably 50% or more, preferably 70%. 80% or more is more preferable, 90% or more is particularly preferable, and 100% is most preferable.
The number of aromatic rings to which an acidic group is bonded with respect to the total number of aromatic rings in the polymer refers to a value calculated from the charging ratio of the monomers when the conductive polymer (A) is produced.

In the conductive polymer (A), the substituent other than the acidic group on the aromatic ring of the monomer unit is preferably an electron-donating group from the viewpoint of imparting reactivity to the monomer. Alkyl groups having 24 carbon atoms, alkoxy groups having 1 to 24 carbon atoms, halogen groups (-F, -Cl, -Br or I) and the like are preferable, and among these, alkoxy groups having 1 to 24 carbon atoms are preferable from the viewpoint of electron donating properties. is most preferred.

Further, the conductive polymer (A) may contain substituted or unsubstituted aniline, thiophene, It may contain one or more units selected from the group consisting of pyrrole, phenylene, vinylene, divalent unsaturated groups, and divalent saturated groups.

The conductive polymer (A) is preferably a compound having a structure represented by the following general formula (6) from the viewpoint of being able to exhibit high conductivity and solubility, and is represented by the following general formula (6). Among the compounds having the structure, poly(2-sulfo-5-methoxy-1,4-iminophenylene) is particularly preferred.

In formula (6), each of R ²² to R ³⁷ is independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, It represents an acidic group, a hydroxy group, a nitro group, or a halogen atom (-F, -Cl, -Br or I). At least one of R ²² to R ³⁷ is an acidic group or a salt thereof. Also, n indicates the degree of polymerization. In the present invention, n is preferably an integer of 5-2500.

At least part of the acidic groups contained in the conductive polymer (A) is desirably in the free acid form from the viewpoint of improving conductivity.

The weight average molecular weight of the conductive polymer (A) is preferably 1,000 to 1,000,000, more preferably 1,500 to 800,000, more preferably 1,500 to 800,000, and more preferably 2,000, in terms of conductivity, solubility and film-forming properties, in terms of sodium polystyrene sulfonate by GPC. ~500,000 is more preferable, and 2,000 to 100,000 is particularly preferable. When the weight average molecular weight of the conductive polymer (A) is less than 1000, the solubility is excellent, but the conductivity and film formability may be insufficient. On the other hand, when the weight average molecular weight exceeds 1,000,000, the solubility may be insufficient although the conductivity is excellent.
Here, "film formability" refers to the property of forming a uniform film without repelling or the like, and can be evaluated by a method such as spin coating on glass.

<Method for producing conductive polymer (A)>
A known method can be used as the method for producing the conductive polymer (A), and is not particularly limited as long as the effect of the present invention is achieved.
Specific examples include a method of polymerizing a polymerizable monomer (raw material monomer) having any of the monomer units described above by various synthetic methods such as chemical oxidation and electrolytic oxidation. As such a method, for example, the synthesis methods described in JP-A-7-196791 and JP-A-7-324132 can be applied.
An example of the method for producing the conductive polymer (A) is described below.
The method for producing the conductive polymer (A) of the present embodiment includes a step (polymerization step) of polymerizing raw material monomers for the conductive polymer (A) in the presence of a polymerization solvent and an oxidizing agent. Furthermore, it is preferable to include a step of purifying the reaction product obtained in the polymerization step (purification step).

(Polymerization process)
The polymerization step is a step of polymerizing raw material monomers of the conductive polymer (A) in the presence of a polymerization solvent and an oxidizing agent.
Specific examples of raw material monomers include polymerizable monomers from which the above-mentioned monomer units are derived. At least one selected from the group consisting of salts is included.
Examples of acidic group-substituted anilines include sulfonic acid group-substituted anilines having a sulfonic acid group as an acidic group.
Typical sulfone-substituted anilines are aminobenzenesulfonic acids, specifically o-, m-, p-aminobenzenesulfonic acid, aniline-2,6-disulfonic acid, aniline-2,5- Disulfonic acid, aniline-3,5-disulfonic acid, aniline-2,4-disulfonic acid, aniline-3,4-disulfonic acid and the like are preferably used.

Examples of sulfonic group-substituted anilines other than aminobenzenesulfonic acids include methylaminobenzenesulfonic acid, ethylaminobenzenesulfonic acid, n-propylaminobenzenesulfonic acid, iso-propylaminobenzenesulfonic acid, n-butylaminobenzenesulfonic acid, Alkyl-substituted aminobenzenesulfonic acids such as sec-butylaminobenzenesulfonic acid and t-butylaminobenzenesulfonic acid; Alkoxy-substituted aminobenzenesulfones such as methoxyaminobenzenesulfonic acid, ethoxyaminobenzenesulfonic acid and propoxyaminobenzenesulfonic acid Acids; hydroxy group-substituted aminobenzenesulfonic acids; nitro group-substituted aminobenzenesulfonic acids; halogen-substituted aminobenzenesulfonic acids such as fluoroaminobenzenesulfonic acid, chloroaminobenzenesulfonic acid and bromoaminobenzenesulfonic acid.
Among these, alkyl group-substituted aminobenzenesulfonic acids, alkoxy group-substituted aminobenzenesulfonic acids, hydroxy group-substituted aminobenzenesulfonic acids, or Halogen-substituted aminobenzenesulfonic acids are preferred, and alkoxy group-substituted aminobenzenesulfonic acids, alkali metal salts, ammonium salts and substituted ammonium salts thereof are particularly preferred in terms of ease of production.
Any one of these sulfonic acid group-substituted anilines may be used alone, or two or more of them may be mixed and used in an arbitrary ratio.

Examples of the polymerization solvent include water, organic solvents, mixed solvents of water and organic solvents, and the like. Examples of organic solvents include alcohols such as methanol, ethanol, isopropyl alcohol, propyl alcohol and butanol; ketones such as acetone and ethyl isobutyl ketone; ethylene glycols such as ethylene glycol and ethylene glycol methyl ether; propylene glycol and propylene glycol. Propylene glycols such as methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether, and propylene glycol propyl ether; Amides such as N,N-dimethylformamide and N,N-dimethylacetamide; N-methylpyrrolidone, N-ethylpyrrolidone, etc. pyrrolidones and the like.
As the polymerization solvent, water or a mixed solvent of water and an organic solvent is preferable.

The oxidizing agent is not limited as long as it has a standard electrode potential of 0.6 V or more, but for example, peroxodisulfates such as peroxodisulfuric acid, ammonium peroxodisulfate, sodium peroxodisulfate and potassium peroxodisulfate; Hydrogen peroxide etc. are mentioned.
Any one of these oxidizing agents may be used alone, or two or more thereof may be mixed and used at any ratio.

In the polymerization step, the raw material monomers may be polymerized in the presence of a basic reaction aid in addition to the polymerization solvent and oxidizing agent.
Examples of basic reaction aids include inorganic bases such as sodium hydroxide, potassium hydroxide and lithium hydroxide; ammonia; methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylmethylamine, ethyldimethylamine, diethyl fatty amines such as methylamine; saturated cyclic amines; and unsaturated cyclic amines such as pyridine, α-picoline, β-picoline, γ-picoline and quinoline.
Among these, inorganic bases, fatty amines, and cyclic unsaturated amines are preferred, and cyclic unsaturated amines are more preferred.
Any one of these basic reaction auxiliaries may be used alone, or two or more thereof may be mixed and used in an arbitrary ratio.

Examples of polymerization methods include a method of dropping the raw material monomer solution into the oxidizing agent solution, a method of dropping the oxidizing agent solution into the raw material monomer solution, and a method of dropping the raw material monomer solution and the oxidizing agent solution simultaneously into a reaction vessel or the like. etc. The raw material monomer solution may contain a basic reaction aid, if necessary.
As the solvent for the oxidizing agent solution and the raw material monomer solution, the polymerization solvent described above can be used.

The reaction temperature of the polymerization reaction is preferably 50°C or less, more preferably -15 to 30°C, and still more preferably -10 to 20°C. If the reaction temperature of the polymerization reaction is 50° C. or lower, particularly 30° C. or lower, it is possible to suppress the progress of side reactions and the decrease in conductivity due to changes in the redox structure of the main chain of the conductive polymer (A) to be produced. If the reaction temperature of the polymerization reaction is −15° C. or higher, a sufficient reaction rate can be maintained and the reaction time can be shortened.

Through the polymerization step, the conductive polymer (A), which is a reaction product, is obtained in a dissolved or precipitated state in the polymerization solvent.
When the reaction product is dissolved in the polymerization solvent, the polymerization solvent is distilled off to obtain the reaction product.
When the reaction product is precipitated in the polymerization solvent, the polymerization solvent is filtered off using a filter such as a centrifugal separator to obtain the reaction product.

Reaction products include low-molecular-weight components such as unreacted raw material monomers, oligomers accompanying side reactions, acidic substances, and basic substances (basic reaction aids, ammonium ions, which are decomposed products of oxidizing agents, etc.). may contain. These low-molecular-weight components are impurities, and become factors that hinder electrical conductivity.
The acidic substance includes an acidic group eliminated from the conductive polymer (A) (e.g., a free acidic group derived from carboxylic acid, sulfonic acid, sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, etc.), Decomposition products of the oxidizing agent used in the production (for example, sulfate ions), components by-produced during the reaction (for example, nitric acid), and the like can be mentioned. Acidic substances also cause film thinning of the resist layer.
Therefore, it is preferable to obtain the conductive polymer (A) by purifying the reaction product after the polymerization step.

It is preferable that the conductive polymer (A) does not substantially contain an acidic substance from the viewpoint of further suppressing film reduction of the resist layer.
Here, "substantially free of acidic substances" means that the content of acidic substances having a molecular weight of 100 or less is 10000 mass ppm or less relative to the total mass of the conductive polymer (A).
The content of acidic substances can be measured by ion chromatography. Specifically, the content of nitrate ions, sulfate ions, phosphate ions, and propionate ions in the lower alcohol (B1) can be measured in the same manner as described below.

(Refining process)
The purification step is a step of purifying the reaction product obtained in the polymerization step.
As a method for purifying the reaction product, any method such as a washing method using a washing solvent, a membrane filtration method, an ion exchange method, removal of impurities by heat treatment, and neutralization precipitation can be used. Among these, the washing method and the ion exchange method are effective from the viewpoint of easily obtaining a highly pure conductive polymer (A). Among them, the washing method is particularly preferable from the viewpoint of efficiently removing raw material monomers, oligomers, and acidic substances. Also, the washing method and the ion exchange method may be used in combination.

When using the washing method, washing solvents include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, 2-butanol, 3-butanol, t-butanol, 1-pentanol, 3-methyl-1 -Alcohols such as butanol, 2-pentanol, n-hexanol, 4-methyl-2-pentanol, 2-ethylbutynol, benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol; ethylene glycol monomethyl ether, ethylene glycol Polyhydric alcohol derivatives such as monoethyl ether, methoxymethoxyethanol, propylene glycol monoethyl ether, glyceryl monoacetate; acetone; acetonitrile; N,N-dimethylformamide; N-methylpyrrolidone; Among these, methanol, ethanol, isopropanol, acetone and acetonitrile are effective.

By drying the reaction product after washing, that is, the washed conductive polymer (A), a solid conductive polymer (A) from which raw material monomers, oligomers and acidic substances are sufficiently removed can be obtained.

The conductive polymer (A) after washing may be further purified by an ion exchange method, if necessary. By using the ion exchange method, it is possible to effectively remove metals and the like present in the state of forming salts with the acidic groups of the conductive polymer (A).
The conductive polymer (A) preferably does not substantially contain Na, K, Mg, Ca, Cr, Fe, Ni, Cu and Zn.
Here, "substantially free" means that the content of Na, K, Mg, Ca, Cr, Fe, Ni, Cu and Zn is 1 mass ppm with respect to the total mass of the conductive polymer (A). means that:
The content of these metals is determined by metal analysis with an inductively coupled plasma mass spectrometer (ICP-MS-Inductively Coupled Plasma Mass Spectrometer).

Examples of ion exchange methods include column-type and batch-type treatments using ion exchange resins such as cation exchange resins and anion exchange resins; and electrodialysis methods.
When purifying the reaction product by an ion exchange method, it is preferable to dissolve the reaction product in an aqueous medium so as to obtain a desired solid concentration, form a polymer solution, and then contact the ion exchange resin.
Examples of the aqueous medium include those similar to the solvent (B) described below.
The concentration of the conductive polymer (A) in the polymer solution is preferably 0.1 to 20% by mass, more preferably 0.1 to 10% by mass, from the viewpoint of industrial efficiency and purification efficiency.

In the case of the ion exchange method using an ion exchange resin, the volume of the sample solution relative to the ion exchange resin is preferably up to 10 times the volume of the ion exchange resin, for example, in the case of a polymer solution having a solid concentration of 5% by mass. Up to double the volume is more preferred. Examples of the cation exchange resin include "Amberlite IR-120B" manufactured by Organo Corporation. Examples of the anion exchange resin include "Amberlite IRA410" manufactured by Organo Corporation.

The conductive polymer (A) after ion exchange treatment is dissolved in an aqueous medium. Therefore, if the aqueous medium is completely removed by an evaporator or the like, a solid conductive polymer (A) can be obtained. good too.

[Conductive composition]
The conductive composition of the present invention contains a conductive polymer (A) and a solvent (B). The solvent (B) contains water and a lower alcohol having 1 to 3 carbon atoms (B1).
The conductive composition may contain a basic compound (C), a surfactant (D) and the like, if necessary.

<Conductive polymer (A)>
The conductive polymer (A) is the conductive polymer (A) described above, and the description thereof is omitted.
The content of the conductive polymer (A) is preferably 0.1 to 5% by mass, more preferably 0.2 to 3% by mass, and 0.5 to 2% by mass, relative to the total mass of the conductive composition. is more preferred.
In addition, the content of the conductive polymer (A) is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, more preferably 95 to 100% by mass, based on the total mass of the solid content of the conductive composition. More preferred. The solid content of the conductive composition is the residue after removing the solvent (B) from the conductive composition.
When the content of the conductive polymer (A) is within the above range, the coating property of the conductive composition and the conductivity of the coating film formed from the conductive composition are well balanced.

<Solvent (B)>
The solvent (B) is a mixed solvent containing water and a lower alcohol having 1 to 3 carbon atoms (B1). Other solvents may be included in addition to water and lower alcohol (B1). The other solvent is not particularly limited as long as it is a solvent capable of dissolving the conductive polymer (A), the basic compound (C) and the surfactant (D) described later, as long as it has the effect of the present invention. Other solvents include organic solvents (excluding lower alcohols having 1 to 3 carbon atoms) among the polymerization solvents previously exemplified in the description of the method for producing the conductive polymer (A).
Examples of water include ion-exchanged water, pure water, and distilled water.
As the lower alcohol (B1), one or more selected from the group consisting of methanol, ethanol, n-propanol and isopropyl alcohol is used. The lower alcohol (B1) contributes to improving the applicability of the conductive composition. When the number of carbon atoms in the lower alcohol (B1) is 3 or less, the uniformity of the conductive composition is excellent, and the smoothness of the coating film is excellent.

In the conductive composition of the present invention, the content of nitrate ions, sulfate ions, phosphate ions, and propionate ions derived from the lower alcohol (B1) is 1000 mass each with respect to the total mass of the lower alcohol (B1). ppm or less.
That is, the contents of nitrate ions, sulfate ions, phosphate ions, and propionate ions in the lower alcohol (B1) are each 1000 mass ppm or less.
If the content of these acid ions is 1000 ppm by mass or less, when the conductive composition containing the lower alcohol (B1) is applied to the surface of the resist layer to form a conductive film, the conductive film is transferred to the resist layer. migration of acid ions can be reduced, and thinning of the resist layer can be suppressed.
The contents of nitrate ions, sulfate ions, phosphate ions, and propionate ions in the lower alcohol (B1) are each 1000 mass ppm or less, more preferably 500 mass ppm or less, and even more preferably 100 mass ppm or less. .
The lower the content of these acid ions, the better, and the lower limit is preferably 0 mass ppm.

The contents of nitrate ions, sulfate ions, phosphate ions, and propionate ions in the lower alcohol (B1) can be measured by ion chromatography. Specifically, it can be measured as follows.
First, sodium carbonate is added to water so that the solid concentration becomes 1.8 mmol/L to prepare an aqueous sodium carbonate solution. Similarly, sodium hydrogencarbonate is added to water so that the solid content concentration becomes 1.7 mmol/L to prepare an aqueous sodium hydrogencarbonate solution. The aqueous sodium carbonate solution and the aqueous sodium hydrogencarbonate solution thus obtained are mixed at a mass ratio of 1:1 to obtain an eluent. A lower alcohol (B1) is added to and dissolved in the resulting eluent to prepare a test solution.
Concentrations of nitrate ions, sulfate ions, phosphate ions, and propionate ions of the obtained test solution are measured using an ion chromatograph to obtain a chromatogram. Read the area or height of the peak corresponding to each acid ion on this chromatogram, and from the calibration curve prepared in advance, each nitrate ion, sulfate ion, phosphate ion, and propionate ion in the lower alcohol Find the content.

In order to reduce the contents of nitrate ions, sulfate ions, phosphate ions, and propionate ions in the lower alcohol (B1) to the above upper limits or less, the lower alcohol (B1) is subjected to, for example, ion exchange treatment, It may be distilled or purified before use.

In the conductive composition of the present invention, the content of calcium (Ca), magnesium (Mg) and zinc (Zn) derived from the lower alcohol (B1) is 10 mass each with respect to the total mass of the lower alcohol (B1). ppb or less.
That is, the contents of calcium (Ca), magnesium (Mg) and zinc (Zn) in the lower alcohol (B1) are each 10 mass ppb or less with respect to the total mass of the lower alcohol.
If the content of each of these metals in the lower alcohol (B1) is 10 mass ppb or less, the amount of metal in the conductive film obtained by applying a conductive composition containing the lower alcohol (B1) to the surface of the resist layer can be reduced. That is, since a conductive film with less foreign substances can be obtained, problems such as disconnection of lines are less likely to occur after drawing with a charged particle beam, and patterning defects can be suppressed.
The contents of Ca, Mg and Zn in the lower alcohol (B1) are each preferably 7 mass ppb or less.
The lower the content of these metals, the better, and the lower limit is preferably 0 mass ppb.

The metal content in the lower alcohol (B1) is determined by metal analysis with an inductively coupled plasma mass spectrometer (ICP-MS-Inductively Coupled Plasma Mass Spectrometer).

In order to reduce the contents of Ca, Mg and Zn in the lower alcohol (B1) to the above upper limits or less, the lower alcohol (B1) is purified, for example, by ion exchange treatment or distillation. You can use it.

The content of the solvent (B) is preferably 1 to 99.9% by mass, more preferably 10 to 98% by mass, even more preferably 50 to 98% by mass, based on the total mass of the conductive composition.
In addition, the conductive polymer (A) is purified and dissolved in an aqueous medium (hereinafter, the conductive polymer (A) in this state is also referred to as a "conductive polymer solution"). An aqueous medium derived from a solution is also included in the content of the solvent (B) in the conductive composition.

The content of the lower alcohol (B1) is 0.1 to 15% by mass, preferably 0.1 to 13% by mass, more preferably 1 to 9% by mass, relative to the total mass of the conductive composition. When it is at least the lower limit of the above range, the effect of improving the applicability of the conductive composition is excellent, and when it is at most the upper limit, film reduction of the resist layer tends to be suppressed.

<Basic compound (C)>
The conductive composition may contain a basic compound (C).
If the conductive composition contains the basic compound (C), it is considered possible to enhance the stability of the conductive polymer (A).

The basic compound (C) is not particularly limited as long as it is a compound having basicity. For example, the following quaternary ammonium salt (c-1), basic compound (c-2), basic compound (c -3).
Quaternary ammonium salt (c-1): A quaternary ammonium compound in which at least one of the four substituents bonded to the nitrogen atom is a hydrocarbon group having 3 or more carbon atoms.
Basic compound (c-2): Basic compound having one or more nitrogen atoms (excluding quaternary ammonium salt (c-1) and basic compound (c-3)).
Basic compound (c-3): A basic compound having a basic group and two or more hydroxy groups in the same molecule and having a melting point of 30°C or higher.

In the quaternary ammonium compound (c-1), the nitrogen atom to which the four substituents are bonded is the nitrogen atom of the quaternary ammonium ion.
In the quaternary ammonium compound (c-1), examples of the hydrocarbon group bonded to the nitrogen atom of the quaternary ammonium ion include an alkyl group, an aralkyl group, and an aryl group.
Examples of the quaternary ammonium compound (c-1) include tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, and benzyltrimethylammonium hydroxide.

Basic compounds (c-2) include, for example, ammonia, pyridine, triethylamine, 4-dimethylaminopyridine, 4-dimethylaminomethylpyridine, 3,4-bis(dimethylamino)pyridine, 1,5-diazabicyclo[4 .3.0]-5-nonene (DBN), 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), and derivatives thereof.

In the basic compound (c-3), basic groups include, for example, basic groups defined as Arrhenius bases, Bronsted bases, Lewis bases and the like. Specifically, ammonia etc. are mentioned. A hydroxy group may be in the state of —OH or in the state of being protected by a protecting group. Examples of protective groups include acetyl group; silyl groups such as trimethylsilyl group and t-butyldimethylsilyl group; acetal type protective groups such as methoxymethyl group, ethoxymethyl group and methoxyethoxymethyl group; benzoyl group; mentioned.
Basic compounds (c-3) include 2-amino-1,3-propanediol, tris(hydroxymethyl)aminomethane, 2-amino-2-methyl-1,3-propanediol, 2-amino-2 -ethyl-1,3-propanediol, 3-[N-tris(hydroxymethyl)methylamino]-2-hydroxypropanesulfonic acid, N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid and the like. .

Any one of these basic compounds may be used alone, or two or more thereof may be mixed and used at any ratio.
Among these, at least one selected from the group consisting of a quaternary ammonium salt (c-1) and a basic compound (c-2) from the viewpoint of easily forming a salt with an acidic group of the conductive polymer (A) is preferably included.

From the viewpoint of further improving the coatability of the conductive composition, the content of the basic compound (C) is 0.00 per 1 mol of units having an acidic group among the units constituting the conductive polymer (A). 1 to 1 mol equivalent is preferred, and 0.1 to 0.9 mol equivalent is more preferred. Furthermore, from the viewpoint of excellent retention of performance as a conductive film and more stable acidic groups in the conductive polymer (A), 0.25 to 0.85 mol equivalent is particularly preferred.

<Surfactant (D)>
The conductive composition may contain a surfactant (D).
If the conductive composition contains the surfactant (D), the coatability of the conductive composition is improved when the conductive composition is applied to the substrate or the surface of the resist layer.
Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Any one of these surfactants may be used alone, or two or more of them may be used as a mixture in an arbitrary ratio.

Examples of anionic surfactants include sodium octanoate, sodium decanoate, sodium laurate, sodium myristate, sodium palmitate, sodium stearate, perfluorononanoic acid, sodium N-lauroylsarcosinate, sodium cocoyl glutamate, alpha sulfo fatty acid methyl ester salts, sodium lauryl sulfate, sodium myristyl sulfate, sodium laureth sulfate, sodium polyoxyethylene alkylphenol sulfonate, ammonium lauryl sulfate, lauryl phosphate, sodium lauryl phosphate, potassium lauryl phosphate, and the like.

Examples of cationic surfactants include tetramethylammonium chloride, tetramethylammonium hydroxide, tetrabutylammonium chloride, dodecyldimethylbenzylammonium chloride, alkyltrimethylammonium chloride, octyltrimethylammonium chloride, decyltrimethylammonium chloride, and dodecyl chloride. Trimethylammonium, Tetradecyltrimethylammonium chloride, Cetyltrimethylammonium chloride, Stearyltrimethylammonium chloride, Alkyltrimethylammonium bromide, Hexadecyltrimethylammonium bromide, Benzyltrimethylammonium chloride, Benzyltriethylammonium chloride, Benzalkonium chloride, Benzyl bromide Ruconium, benzethonium chloride, dialkyldimethylammonium chloride, didecyldimethylammonium chloride, distearyldimethylammonium chloride, monomethylamine hydrochloride, dimethylamine hydrochloride, trimethylamine hydrochloride, butylpyridinium chloride, dodecylpyridinium chloride, cetylpyridinium chloride, etc. mentioned.

Examples of amphoteric surfactants include betaine lauryldimethylaminoacetate, betaine stearyldimethylaminoacetate, dodecylaminomethyldimethylsulfopropylbetaine, octadecylaminomethyldimethylsulfopropylbetaine, cocamidopropylbetaine, cocamidopropylhydroxysultaine, 2 -alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, sodium lauroyl glutamate, potassium lauroyl glutamate, lauroylmethyl-β-alanine, lauryldimethylamine-N-oxide, oleyldimethylamine N-oxide and the like. .

Examples of nonionic surfactants include glyceryl laurate, glyceryl monostearate, sorbitan fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkyl ether, pentaethylene glycol monododecyl ether, octaethylene glycol monododecyl ether, poly Oxyethylene alkylphenyl ether, octylphenol ethoxylate, nonylphenol ethoxylate, polyoxyethylene polyoxypropylene glycol, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene hexitane fatty acid ester, sorbitan fatty acid ester polyethylene glycol, lauric acid diethanolamide, oleic acid diethanolamide, stearic acid diethanolamide, octyl glucoside, decyl glucoside, lauryl glucoside, cetanol, stearyl alcohol, oleyl alcohol and the like.

As the nonionic surfactant, in addition to those mentioned above, a water-soluble polymer having a nitrogen-containing functional group and a terminal hydrophobic group may be used. Unlike conventional surfactants, this water-soluble polymer has surface activity due to the main chain portion (hydrophilic portion) having a nitrogen-containing functional group and the hydrophobic group portion at the end, and has the effect of improving coating properties. is high. Therefore, excellent applicability can be imparted to the conductive composition without using other surfactants in combination. Moreover, this water-soluble polymer does not contain an acid or a base and hardly produces by-products due to hydrolysis, so that it has little adverse effect on the resist layer or the like.

From the viewpoint of solubility, the nitrogen-containing functional group is preferably an amide group.
Examples of terminal hydrophobic groups include alkyl groups, aralkyl groups, aryl groups, alkoxy groups, aralkyloxy groups, aryloxy groups, alkylthio groups, aralkylthio groups, arylthio groups, primary or secondary alkylamino groups, and aralkylamino groups. , an arylamino group, and the like. Among these, an alkylthio group, an aralkylthio group, and an arylthio group are preferred.
The number of carbon atoms in the terminal hydrophobic group is preferably 3-100, more preferably 5-50, and particularly preferably 7-30.
The number of terminal hydrophobic groups in the water-soluble polymer is not particularly limited. Moreover, when two or more terminal hydrophobic groups are present in the same molecule, the terminal hydrophobic groups may be of the same type or of different types.

The water-soluble polymer is mainly a homopolymer of a vinyl monomer having a nitrogen-containing functional group, or a copolymer of a vinyl monomer having a nitrogen-containing functional group and a vinyl monomer having no nitrogen-containing functional group (other vinyl monomer). A compound having a chain structure and having a hydrophobic group at a site other than the repeating unit constituting the polymer is preferred.
Examples of the vinyl monomer having a nitrogen-containing functional group include acrylamide and derivatives thereof, heterocyclic monomers having a nitrogen-containing functional group, etc. Among them, those having an amide bond are preferred. Specifically, acrylamide, N,N-dimethylacrylamide, N-isopropylacrylamide, N,N-diethylacrylamide, N,N-dimethylaminopropylacrylamide, t-butylacrylamide, diacetoneacrylamide, N,N'-methylene bisacrylamide, N-vinyl-N-methylacrylamide, N-vinylpyrrolidone, N-vinylcaprolactam and the like. Among these, acrylamide, N-vinylpyrrolidone, N-vinylcaprolactam and the like are particularly preferable from the viewpoint of solubility.
Other vinyl monomers are not particularly limited as long as vinyl monomers having nitrogen-containing functional groups can be copolymerized, and examples thereof include styrene, acrylic acid, vinyl acetate, and long-chain α-olefins.

Although the method for introducing the terminal hydrophobic group into the water-soluble polymer is not particularly limited, it is usually preferable to introduce it by selecting a chain transfer agent during vinyl polymerization because of its simplicity. In this case, as the chain transfer agent, a group containing a hydrophobic group such as an alkyl group, an aralkyl group, an aryl group, an alkylthio group, an aralkylthio group, an arylthio group, etc. is introduced at the end of the resulting polymer. There are no particular restrictions. For example, when obtaining a water-soluble polymer having an alkylthio group, an aralkylthio group, or an arylthio group as a terminal hydrophobic group, a chain transfer agent having a hydrophobic group corresponding to these terminal hydrophobic groups, specifically a thiol , disulfide, thioether and the like are preferably used for vinyl polymerization.

The main chain portion of the water-soluble polymer is water-soluble and has nitrogen-containing functional groups. The number of units (degree of polymerization) of the main chain portion is preferably 2 to 1,000, more preferably 3 to 1,000, and particularly preferably 5 to 10 per molecule. If the number of units of the main chain portion having a nitrogen-containing functional group is too large, the surface activity tends to decrease.
Molecular weight ratio (mass average of the main chain portion The molecular weight/mass average molecular weight of the terminal hydrophobic group portion) is preferably 0.3-170.

As the surfactant (D), nonionic surfactants are preferable among the above-mentioned surfactants because they have less influence on the resist layer.

The content of the surfactant (D) is preferably 5 to 80 parts by mass when the total of the conductive polymer (A), the basic compound (C) and the surfactant (D) is 100 parts by mass. 10 to 70 parts by mass is more preferable, and 10 to 60 parts by mass is even more preferable. If the content of the surfactant (D) is within the above range, the applicability of the conductive composition to the resist layer is further improved.

<Optional component>
The conductive composition may optionally contain components (optional components) other than the conductive polymer (A), solvent (B), basic compound (C) and surfactant (D).
Examples of optional components include polymer compounds (excluding conductive polymer (A), basic compound (C) and surfactant (D)), additives and the like.

Examples of polymer compounds include polyvinyl alcohol derivatives such as polyvinyl formal and polyvinyl butyral; polyacrylamides such as polyacrylamide, poly(Nt-butylacrylamide) and polyacrylamidemethylpropanesulfonic acid; Acrylic acids, water-soluble alkyd resins, water-soluble melamine resins, water-soluble urea resins, water-soluble phenol resins, water-soluble epoxy resins, water-soluble polybutadiene resins, water-soluble acrylic resins, water-soluble urethane resins, water-soluble acrylic styrene copolymers Resins, water-soluble vinyl acetate acrylic copolymer resins, water-soluble polyester resins, water-soluble styrene-maleic acid copolymer resins, water-soluble fluorine resins, and copolymers thereof.
Examples of additives include pigments, antifoaming agents, ultraviolet absorbers, antioxidants, heat resistance improvers, leveling agents, anti-sagging agents, matting agents and preservatives.

<Method for producing conductive composition>
The method for producing a conductive composition of the present invention includes a mixing step of mixing a conductive polymer (A), water and a lower alcohol (B1). In the mixing step, one or more of other solvent, basic compound (C), surfactant (D) and optional ingredients may be mixed. The order of mixing is not particularly limited.
The lower alcohol (B1) used is purified before being mixed with the conductive polymer (A).

<Effect>
As part of the solvent (B) in the conductive composition, 15% by mass of a lower alcohol (B1) in which the content of nitrate ions, sulfate ions, phosphate ions, and propionate ions is reduced to a specific range. By using the following addition amount, while suppressing the film reduction caused by the migration of the acidic component in the conductive film to the resist layer and the film reduction caused by the alcohol in the conductive film coming into contact with the resist layer. , the coatability can be improved.

<Application>
The conductive composition of the present invention is suitable for antistatic use during charged particle beam drawing. Specifically, the conductive composition of the present invention is applied to the surface of a resist layer formed by a pattern formation method using a charged particle beam using a chemically amplified resist to form a conductive film. The conductive film thus formed becomes the antistatic film of the resist layer.
In addition to the above, the conductive composition of the present invention can also be used as materials for capacitors, transparent electrodes, semiconductors, and the like.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the following examples are not intended to limit the scope of the present invention.
Various measurement and evaluation methods in Examples and Comparative Examples are as follows.
[Measurement/evaluation method]
<Measurement of content of nitrate ions, sulfate ions, phosphate ions, and propionate ions>
A test solution was prepared by adding 100 g of the following eluent to 0.1 g of lower alcohol (B1). Concentrations of nitrate ions, sulfate ions, phosphate ions, and propionate ions were measured for the resulting test solutions under the following ion chromatography (IC) measurement conditions to obtain chromatograms. Read the area or height of the peak corresponding to each ion on the obtained chromatogram, from the calibration curve prepared in advance, nitrate ions, sulfate ions, phosphate ions relative to the total mass of the lower alcohol (B1), Each propionate ion content was determined.
<<IC measurement conditions>>
・ Apparatus: Ion Chromatograph IC-2010 (manufactured by Tosoh Corporation)
・Column: TSKguard Column Super IC-Anion HS C-No W00052
Eluent: a mixture of a 1.8 mmol/L sodium carbonate aqueous solution and a 1.7 mmol/L solids concentration of sodium hydrogen carbonate (mass ratio 1:1)
・Flow rate: 1.5 mL/min ・Measurement temperature: 40°C
・Sample injection volume: 30 μL

<Measurement of metal content>
High-frequency inductively coupled plasma mass spectrometer (ICP-MS- Inductively Coupled Plasma Mass Spectrometer: 7500cs manufactured by Agilent Technologies) is subjected to metal analysis of Ca, Mg and Zn, and the content of each metal with respect to each total mass of lower alcohol (B1) asked for

<Evaluation of conductivity>
2.0 mL of a conductive composition was dropped on a glass substrate as a substrate, and a coating film was formed by spin coating with a spin coater at 2000 rpm for 60 seconds so as to cover the entire substrate surface. A heat treatment was performed on a hot plate at 80° C. for 2 minutes to form a conductive film having a thickness of about 30 nm on the substrate, thereby obtaining a conductor.
Using Hiresta UX-MCP-HT800 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.), the surface resistance value [Ω/□] of the conductive film was measured by a two-terminal method (distance between electrodes: 20 mm).

<Evaluation of coatability >
1 mL of the conductive composition was dropped onto a 4-inch silicon wafer and applied using a spin coater. Let A and B pass.
A: 80% or more of the wafer is evenly coated.
B: 80% or more of the wafer is coated, but there is unevenness.
C: Less than 80% of the wafer was coated.

<Evaluation by Film Reduction Test>
(Measurement of film reduction amount)
A chemically amplified electron beam resist (hereinafter abbreviated as “resist”) was used, and the film reduction amount of the resist layer was measured by the following procedures (1A) to (8A).
(1A) Formation of resist layer: A resist layer of 0.2 µm was spin-coated on a 4-inch silicon wafer as a base material with a spin coater at 2000 rpm for 60 seconds, and then pre-baked on a hot plate at 130°C for 90 seconds. , the solvent was removed, and a resist layer was formed on the substrate.
(2A) Thickness measurement of resist layer 1: Part of the resist layer formed on the substrate is peeled off, and the substrate surface is used as a reference position, and a stylus profiler (Stylus profiler P-16+, KLA-Tencor Corporation) was used to measure the initial film thickness a [nm] of the resist layer.
(3A) Formation of a conductive film: 2 mL of a conductive composition is dropped onto the resist layer, and is applied by a spin coater at 2000 rpm for 60 seconds so as to cover the entire surface of the resist layer. A heat treatment was performed at 80° C. for 2 minutes to form a conductive film having a thickness of about 30 nm on the resist layer.
(4A) Baking treatment: The substrate on which the conductive film and the resist layer are laminated is heated on a hot plate at 120 ° C. for 20 minutes in an air atmosphere, and the substrate in this state is heated at room temperature (25 ° C.) in the air at 90°C. Let stand for seconds.
(5A) Washing with water: After washing the conductive film with 20 mL of water, it was spun at 2000 rpm for 60 seconds with a spin coater to remove water on the surface of the resist layer.
(6A) Development: 20 mL of a developer consisting of a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution was dropped onto the surface of the resist layer. After standing still for 60 seconds, the resist layer was rotated at 2000 rpm for 60 seconds with a spin coater to remove the developer on the surface of the resist layer, and then dried by maintaining rotation for 60 seconds.
(7A) Thickness measurement of resist layer 2: After stripping part of the resist layer within 5 mm from the part where the resist layer was partially stripped in (2A), the resist after development using a stylus type step meter The film thickness b [nm] of the layer was measured.
(8A) Calculation of film thickness reduction amount: The film thickness reduction amount c [nm] (c=ab) of the resist layer was calculated by subtracting the film thickness b value from the film thickness a value.

(Measurement of reference film reduction amount)
The resist layer has a thickness reduction amount d [nm] peculiar to each resist (hereinafter referred to as "reference thickness reduction amount") depending on the storage period after the formation of the resist layer. This reference film reduction amount d not caused by the conductive film was measured by the following procedures (1B) to (6B).
(1B) Formation of resist layer: A resist layer was formed on the substrate in the same manner as in (1A) above.
(2B) Film thickness measurement 1 of resist layer: The initial film thickness a [nm] of the resist layer was measured in the same manner as in (2A) above.
(3B) Baking treatment: Baking treatment was performed in the same manner as in (4A) above, except that a base material laminated with a resist layer was used.
(4B) Development: Development was carried out in the same manner as in (6A) above.
(5B) Thickness measurement of resist layer 2: After stripping a part of the resist layer within 5 mm from the part where the resist layer was stripped in (2B), the resist layer after development was measured using a stylus profilometer. A film thickness e [nm] was measured.
(6B) Calculation of amount of film thickness reduction: Subtracting the value of film thickness e from the value of film thickness a, the reference film thickness reduction amount d (d=ae) of the resist layer was calculated.
The reference film thickness reduction amount d of the resist layer was 3 nm.

(Calculation of film reduction amount of resist layer caused by components in conductive film)
Subtract the value of the reference film reduction amount d of the resist layer from the value of the film reduction amount c of the resist layer, and the film reduction of the resist layer caused by the acidic substance having a molecular weight of 100 or less that has migrated from the conductive film to the resist layer. The amount f [nm] (f=cd) was calculated and evaluated according to the following evaluation criteria. The smaller the amount of film loss f, the better, and A and B are accepted.
A: The amount of film reduction f is less than 5 nm.
B: The film reduction amount f is 5 nm or more and less than 20 nm.
C: The film reduction amount f is 20 nm or more.

[Production Example 1]
Isopropyl alcohol (hereinafter also referred to as IPA) was used as the lower alcohol (B1). IPA was distilled under the following conditions to obtain purified IPA.
The contents of nitrate ions, sulfate ions, phosphate ions, and propionate ions in the purified IPA were all 100 mass ppm or less.
The content of nitrate ions in IPA before purification is 200 ppm by mass, the content of sulfate ions is 1100 ppm by mass, the content of phosphate ions is 800 ppm by mass, the content of propionate ions is 1500 ppm by mass, The Ca content was 4 mass ppb, the Mg content was 5 mass ppb, and the Zn content was 2 mass ppb.
<Distillation conditions>
A distillation operation was performed by adding IPA to a glass flask equipped with a cooling pipe and a Shizuki connecting pipe, distilling it off with heating, and collecting the outflowing IPA in a container washed with ultrapure water.

[Production Example 2]
<Production of conductive polymer (A)>
100 mmol of pyridine and 100 mL of water were added to 100 mmol of 2-aminoanisole-4-sulfonic acid to obtain a monomer solution.
An aqueous solution (oxidant solution) of 100 mmol of ammonium peroxodisulfate was added dropwise at 10° C. to the resulting monomer solution. After completion of dropping, the mixture was further stirred at 25°C for 15 hours, then heated to 35°C and further stirred for 2 hours to obtain a reaction liquid in which a reaction product precipitated (polymerization step).
The obtained reaction solution is filtered with a centrifugal filter, the precipitate (reaction product) is recovered, the reaction product is washed with 1 L of methanol and then dried to obtain a powdery conductive polymer (A1). was obtained (purification step).
The amount of methanol used in the purification step corresponds to 5000 parts by mass with respect to 100 parts by mass of the conductive polymer (A1).
The resulting conductive polymer (A1) did not substantially contain acidic substances.

[Example 1]
<Preparation of conductive composition>
1 part by mass of the conductive polymer (A1), 96 parts by mass of water, and 4 parts by mass of the purified IPA obtained in Preparation Example 1 were mixed to obtain a conductive composition.
The conductive composition thus obtained was evaluated for conductivity and coatability, and subjected to a film reduction test. These results are shown in Table 1.

[Examples 2-3, Comparative Examples 1-3]
A conductive composition was prepared in the same manner as in Example 1, except that the composition was changed as shown in Table 1, and evaluated and tested. Table 1 shows the results.

As shown in the results of Table 1, the conductive compositions of Examples 1 to 3, to which the purified lower alcohol (B1) was added so as to have a content of 15% by mass or less, had good applicability. , the film thinning was also suppressed.
Comparative Example 1, in which the lower alcohol (B1) was not used, was inferior in coatability.
Comparative Example 2 is an example in which the lower alcohol (B1) was not used and a surfactant was used instead, but the coatability was insufficient.
In Comparative Example 3, in which the amount of the purified lower alcohol (B1) added was too large, significant film loss occurred.

Claims (2)

Conductive, comprising a step of producing a purified conductive polymer having an acidic group , and a step of mixing the purified conductive polymer, water, and a purified lower alcohol having 1 to 3 carbon atoms A method for producing a composition comprising:
The content of the purified lower alcohol is 0.1 to 15% by mass with respect to the total mass of the conductive composition,
The contents of nitrate ions, sulfate ions, phosphate ions, and propionate ions in the purified lower alcohol are each 1000 mass ppm or less,
The content of calcium, magnesium, and zinc in the purified lower alcohol is each 10 mass ppb or less ,
A method for producing a conductive composition, wherein the content of an acidic substance having a molecular weight of 100 or less is 10000 mass ppm or less with respect to the total mass of the purified conductive polymer . 2. The method for producing a conductive composition according to claim 1, further comprising the step of purifying a lower alcohol having 1 to 3 carbon atoms to obtain the purified lower alcohol.