JP7135570B2 - Conductive composition, method for producing conductor, and method for forming resist pattern - Google Patents

Description

TECHNICAL FIELD The present invention relates to a conductive composition, a method for producing a conductor, and a method for forming a resist pattern.

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 to improve productivity.
Therefore, the use of highly sensitive chemically amplified resists that generate acid in exposed areas or areas irradiated with charged particle beams, followed by heat treatment called post-exposure baking (PEB) to promote cross-linking or decomposition reactions. has become mainstream.

By the way, in the pattern forming method using a charged particle beam, especially when the base material is insulating, the trajectory of the charged particle beam is bent due to the electric field generated by the charge-up of the base material, and the desired pattern is formed. is difficult to obtain.
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.

Polyaniline having acidic groups is known as a conductive polymer. Polyaniline having an acidic group can develop electrical conductivity without adding a dopant.
Polyaniline having an acidic group can be obtained, for example, by polymerizing aniline having an acidic group with an oxidizing agent in the presence of a basic reaction aid.
However, polyaniline having an acidic group thus obtained is obtained as a reaction mixture in which raw material monomers (unreacted monomers) and by-products such as decomposition products of oxidizing agents (for example, sulfate ions) are mixed. In addition, the acidic group of polyaniline having an acidic group is susceptible to hydrolysis and is unstable, and the acidic group may be eliminated. In particular, when heat is applied to polyaniline having an acidic group, the acidic group tends to be eliminated or the polyaniline itself tends to decompose.

Therefore, when polyaniline having an acidic group is applied to a chemically amplified resist, when exposure, PEB processing and development are performed while a conductive film is formed on the resist layer, raw material monomers, decomposition products of polyaniline, and released acidic groups , sulfuric acid ions, which are decomposition products of the oxidizing agent (hereinafter collectively referred to as "acidic substances"), etc. tend to migrate to the resist layer. As a result, the pattern shape tends to change and the sensitivity tends to fluctuate, which affects the resist layer.
Specifically, when the resist layer is a positive type, if acidic substances migrate from the conductive film to the resist layer, the unexposed areas of the resist layer will dissolve during development, resulting in a reduction in the thickness of the resist layer and a thinning of the pattern. , sensitivity variation toward the high sensitivity side, and the like.
Further, when the resist layer is of a negative type, when an acidic substance or the like migrates from the conductive film to the resist layer, the acid in the exposed portion is deactivated, causing a change in pattern shape and sensitivity fluctuation toward the low sensitivity side.

Therefore, a conductive composition has been proposed which is excellent in conductivity and causes less film loss of the resist layer.
For example, Patent Document 1 discloses a conductive composition containing a conductive polymer having an acidic group and a basic compound such as tetrabutylammonium hydroxide.

WO2014/017540

However, there is still room for improvement in the conductivity of the conductive composition described in Patent Document 1 and in the prevention of film reduction of the resist layer, and further improvement in conductivity and prevention of film reduction of the resist layer are required.

The present invention has been made in view of the above circumstances, and provides a conductive composition capable of forming a conductive film having excellent conductivity with less film loss of the resist layer, a method for producing a conductor, and formation of a resist pattern. The purpose is to provide a method.

The present invention has the following aspects.
[1] A conductive polymer (A) having an acidic group and a basic compound having a boiling point of 110°C or higher and a pH of 11.50 or higher at 25°C in an aqueous solution with a concentration of 0.1 mol/l. A conductive composition comprising (B), a basic compound (C-1) having a pH of less than 11.50 at 25° C. in an aqueous solution with a concentration of 0.1 mol/l, and water (D). thing.
[2] A conductive polymer (A) having an acidic group and a basic compound having a boiling point of 110°C or higher and a pH of 11.50 or higher at 25°C in an aqueous solution with a concentration of 0.1 mol/l. A conductive composition comprising (B), a basic compound (C-2) having a boiling point of less than 40°C, and water (D).
[3] The mass ratio of the basic compound (B) to the basic compound (C-1) or the basic compound (C-2) is basic compound (B): basic compound (C-1 ) or the conductive composition according to [1] or [2], wherein the basic compound (C-2) is 5:95 to 95:5.
[4] The conductive composition according to any one of [1] to [3], wherein the basic compound (B) has a valence of 1.
[5] The conductive composition according to any one of [1] to [4], wherein the basic compound (C-1) and the basic compound (C-2) are monovalent. .
[6] The conductive composition according to any one of [1] to [5], wherein the conductive polymer (A) has units represented by the following general formula (1).

In formula (1), R ¹ to R ⁴ 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, represents an acidic group, a hydroxy group, a nitro group, or a halogen atom, and at least one of R ¹ to R ⁴ is an acidic group or a salt thereof. Here, the acidic group is a sulfonic acid group or a carboxy group.

[7] The conductive composition according to any one of [1] to [6], which is used for antistatic resist.
[8] A step of applying the conductive composition according to any one of [1] to [6] on at least one surface of a substrate, and heating the applied conductive composition at 40 ° C. or higher. A method for manufacturing a conductor, comprising the step of treating.
[9] The conductive composition according to any one of [1] to [7] is applied to the surface of the resist layer of a substrate having a resist layer made of a chemically amplified resist on one side, and is applied. forming a conductive film by heat-treating the conductive composition at 40° C. or higher; and patternwise irradiating the substrate with an electron beam from the conductive film side. Method.

According to the present invention, it is possible to provide a conductive composition, a method for producing a conductor, and a method for forming a resist pattern, which can form a conductive film having excellent conductivity with less film loss of the resist layer.

The present invention will be described in detail below.
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.
Further, in the present invention, the "acidic substance" means a substance having a negative charge, specifically, a raw material monomer of the conductive polymer (A), a decomposition product of the conductive polymer (A), a conductive polymer It means an acidic group (free acidic group) eliminated from (A) and a decomposition product (for example, sulfate ion) of an oxidizing agent used in the production of the conductive polymer (A).
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 polystyrenesulfonate or polyethylene glycol) measured by gel permeation chromatography (GPC).

[Conductive composition]
The conductive composition of the first aspect of the present invention comprises the following conductive polymer (A), a basic compound (B), and a basic compound (C-1) or a basic compound (C-2) and water (D).
In this specification, the basic compound (C-1) and the basic compound (C-2) are collectively referred to as "basic compound (C)".

<Conductive polymer (A)>
A conductive polymer (A) has an acidic group. If the conductive polymer (A) has an acidic group, the water solubility will be enhanced.
The conductive polymer having an acidic group 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 its molecule, as long as it has the effects of the present invention. Known 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 having an acidic group include phenylene vinylene, vinylene, and thienylene substituted with at least one group selected from the group consisting of a sulfonic acid group and a carboxyl group at the α- or β-position. , pyrrolylene, phenylene, iminophenylene, isothianaphthene, furylene, and carbazolylene as a repeating unit.
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 at least one monomer unit selected from the group consisting of units represented by the following general formulas (2) to (5) from the viewpoint of being able to exhibit high conductivity and solubility, It is preferably contained in an amount of 20 to 100 mol % in all units (100 mol %) constituting the conductive polymer.

In formulas (2) to (5), X represents a sulfur atom or a nitrogen atom, and R ⁵ to R ¹⁹ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, carbon linear or branched alkoxy group, acidic group, hydroxy group, nitro group, halogen atom (-F, -Cl, -Br or I), -N(R ²⁰ ) ₂ , -NHCOR ²⁰ , of number 1 to 24, represents -SR ²⁰ , -OCOR ²⁰ , -COOR ²⁰ , -COR ²⁰ , -CHO, or -CN; R ²⁰ 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 ⁵ and R ⁶ in general formula (2), at least one of R ⁷ to R ¹⁰ in general formula (3), and R ¹¹ to R ¹⁴ in general formula (4) At least one of them, at least one of R ¹⁵ to R ¹⁹ in formula (5) 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 having a sulfonic acid group (--R ²¹ SO ₃ H).
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 ²¹ COOH) having a carboxylic acid group.
R ²¹ 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 (5) 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 (1).

In formula (1), R ¹ to R ⁴ 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 ¹ to R ⁴ is an acidic group or a salt thereof.

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

The conductive polymer (A), from the viewpoint of excellent solubility in water and organic solvents regardless of pH, out of all the units (100 mol%) constituting the conductive polymer (A), 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 (1) in one molecule.

In the conductive polymer (A), from the viewpoint of very good 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. If 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.

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 conductive polymer (A) can be obtained, for example, by polymerizing raw material monomers using an oxidizing agent in the presence of a basic reaction aid.
Specific examples of raw material monomers include at least one selected from the group consisting of acidic group-substituted anilines, alkali metal salts, ammonium salts and substituted ammonium salts thereof.
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.
Each of these sulfonic acid group-substituted anilines may be used alone, or two or more of them may be used by mixing at any ratio.

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 and γ-picoline.
Among these, inorganic bases, aliphatic amines, and cyclic unsaturated amines are preferred, and inorganic bases are more preferred.
Each of these basic reaction auxiliaries may be used alone, or two or more of them may be used by mixing them in an arbitrary ratio.

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.
Each of these oxidizing agents may be used singly, or two or more of them may be mixed and used at any ratio.

As the polymerization method, for example, a method of dropping a mixed solution of raw material monomers and a basic reaction aid into an oxidizing agent solution, a method of dropping an oxidizing agent solution into a mixed solution of raw material monomers and a basic reaction auxiliary, and a method of For example, a mixed solution of raw material monomers and a basic reaction aid and an oxidizing agent solution are added dropwise to a container or the like at the same time.

After polymerization, the solvent is usually filtered off using a filter such as a centrifugal separator. Furthermore, after washing the filtrate with a washing liquid as necessary, it is dried to obtain the conductive polymer (A).

The conductive polymer (A) obtained in this way contains oligomers, acidic substances, basic substances (basic reaction aids, ammonium ions that are decomposed products of oxidizing agents, etc.) associated with side reactions. May contain low molecular weight substances. These low-molecular-weight substances are factors that hinder electrical conductivity.

Therefore, it is preferable to purify the conductive polymer (A) to remove low molecular weight substances.
The method for purifying the conductive polymer (A) is not particularly limited, and any method such as an ion exchange method, acid washing in a protonic acid solution, removal by heat treatment, neutralization precipitation, etc. can be used. The ion exchange method is particularly effective from the viewpoint that the conductive polymer (A) can be easily obtained.
By using an ion exchange method, it is possible to effectively remove basic substances present in a state of forming a salt with the acidic groups of the conductive polymer (A), acidic substances, etc., and to obtain a highly pure conductive polymer (A). can be obtained.

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.
In the case of purifying the conductive polymer (A) by an ion exchange method, the reaction mixture obtained by polymerization is dissolved in an aqueous medium so as to have a desired solid content concentration, and the polymer solution is brought into contact with the ion exchange resin. It is preferable to let
Examples of aqueous media include water, organic solvents, and mixed solvents of water and organic solvents. Examples of the organic solvent include those similar to the organic solvents exemplified in the optional components described later.
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 electrically conductive polymer (A) purified in this manner is sufficiently free of oligomers, acidic substances, basic substances and the like, and exhibits superior electrical conductivity. The conductive polymer (A) after purification is in a state of being dispersed or 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. may be used.

The content of the conductive polymer (A) is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and 0.1 to 2% by mass with respect to the total mass of the conductive composition. More preferred. If the content of the conductive polymer (A) is within the above range, a conductive film with better conductivity can be formed.

<Basic compound (B)>
The basic compound (B) is a compound having a boiling point of 110° C. or higher and a pH of 11.50 or higher at 25° C. in an aqueous solution with a concentration of 0.1 mol/l.
By including the basic compound (B) in the conductive composition, the basic compound (B) efficiently acts on the acidic groups in the conductive polymer (A) to increase the stability of the conductive polymer (A). is considered to be possible. Here, efficiently acting on the acidic groups in the conductive polymer (A) means that the conductive polymer (A) can be stably neutralized, and the acidic groups of the conductive polymer (A) and the basic compound (B ) to form a stable salt. That is, the conductive polymer (A) is neutralized with the basic compound (B). As a result, destabilization of the acidic groups of the conductive polymer (A) due to hydrolysis in the conductive composition can be suppressed, making it difficult for the acidic groups to leave. In addition, by forming a stable salt with the acidic group of the conductive polymer (A) and the basic compound (B), decomposition of the conductive polymer (A) itself can be suppressed. In addition, the basic compound (B) also forms a stable salt with a decomposition product (such as sulfate ion) of the oxidizing agent used in the production of the conductive polymer (A). Therefore, generation of acidic groups derived from the conductive polymer (A) and sulfate ions derived from the oxidizing agent in the conductive composition can be suppressed. In addition, the content of decomposition products of the conductive polymer (A) in the conductive composition can also be reduced.
Therefore, especially in the pattern formation method using a charged particle beam using a chemically amplified resist, migration of acidic substances from the conductive film to the resist layer side can be suppressed, and effects such as thinning of the resist layer can be suppressed.

The boiling point of the basic compound (B) is 110°C or higher, preferably 115°C or higher, more preferably 120°C or higher. Generally, a conductive film is formed by applying a conductive composition to an object such as a substrate and then heat-treating it. If the boiling point of the basic compound (B) is 110° C. or higher, the basic compound (B) is less likely to volatilize during formation of the conductive film (particularly during heat treatment). Therefore, the stability of the conductive polymer (A) is maintained even in the conductive film, elimination of acidic groups and decomposition of the conductive polymer (A) are suppressed, and thinning of the resist layer can be suppressed.

The basic compound (B) has a pH of 11.50 or higher, preferably 12.00 or higher. If the pH is 11.50 or more, the stability of the conductive polymer (A) in the conductive film can be maintained, elimination of acidic groups and decomposition of the conductive polymer (A) are suppressed, and the film of the resist layer decrease can be suppressed.
The pH of the basic compound (B) is a value measured as follows. Specifically, the basic compound (B) is dissolved in water to a concentration of 0.1 mol/l, and the pH of the resulting aqueous solution at 25°C is measured using a pH meter.

The valence of the basic compound (B), ie, the valence of the base, is preferably monovalent. If the valence of the basic compound (B) is monovalent, it can stably exist in the conductive composition without impairing the solubility of the conductive polymer (A).
Here, the "valence of the base" is the amount of potassium hydroxide equivalent to hydrochloric acid or perchloric acid required to neutralize 1 g of the sample, expressed in milligrams.

Examples of the basic compound (B) include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, diazabicyclononene, diazabicycloundecene, and those having 2 to 6 carbon atoms. Examples include monoalkylamines, dialkylamines having 2 to 6 carbon atoms, and trialkylamines having 2 to 6 carbon atoms.
Any one of these compounds may be used alone, or two or more of these compounds may be used as a mixture in an arbitrary ratio.

The content of the basic compound (B) is preferably 5 to 70 mol parts, more preferably 10 to 70 mol parts, per 100 mol parts of units having an acidic group among the units constituting the conductive polymer (A). If the content of the basic compound (B) is within the above range, it will efficiently interact with the acidic groups in the solution of the conductive polymer (a).

<Basic compound (C)>
The basic compound (C) is a basic compound (C-1) or a basic compound (C-2) shown below. That is, the conductive composition is an embodiment containing a conductive polymer (A), a basic compound (B), a basic compound (C-1), and water (D), or a conductive polymer ( A), a basic compound (B), a basic compound (C-2), and water (D).
The basic compound (C-1) is a compound having a pH of less than 11.50 at 25° C. in an aqueous solution with a concentration of 0.1 mol/l.
The basic compound (C-2) is a compound having a boiling point of less than 40°C.

As described above, the stability of the conductive polymer (A) is enhanced by the basic compound (B), making it difficult for the acidic groups of the conductive polymer (A) to leave, but this stability is maintained even in the conductive film. The Rukoto. That is, even in the conductive film, the acidic group of the conductive polymer (A) maintains the state of forming a salt with the basic compound (B). However, if the proportion of acidic groups forming a salt with the basic compound (B) in the conductive film is too high, the original performance of the conductive polymer (A), that is, the conductivity, becomes difficult to sufficiently develop.

If the conductive composition contains a basic compound (C), a conductive film having excellent conductivity is formed while maintaining the stability of the conductive polymer (A) in the conductive composition and the conductive film. can. The reason for this is considered as follows.
The basic compound (C), like the basic compound (B), can form a salt with the acidic groups in the conductive polymer (A) to increase the stability of the conductive polymer (A).
However, when the conductive composition becomes a conductive film, at least part of the basic compound (C) is volatilized by heat treatment. By volatilizing the basic compound (C), the acidic groups of the conductive polymer forming a salt with the volatilized basic compound (C) are freed, and conductivity is easily developed.

The basic compound (C-1) has a pH of less than 11.50, preferably 11.00 or less. If the pH is less than 11.50, the basic compound (C-1) is easily volatilized during the formation of the conductive film, and a conductive film with excellent conductivity can be formed.
The pH of the basic compound (C-1) is a value measured as follows. That is, the basic compound (C-1) is dissolved in water to a concentration of 0.1 mol/l, and the pH of the resulting aqueous solution at 25°C is measured using a pH meter.
The boiling point of the basic compound (C-1) is not particularly limited.

The boiling point of the basic compound (C-2) is less than 40°C, preferably 35°C or less. If the boiling point is less than 40° C., the basic compound (C) is easily volatilized during the formation of the conductive film, and a conductive film with excellent conductivity can be formed.
The pH of the basic compound (C-2) is not particularly limited.
The pH of the basic compound (C-2) is a value measured as follows. That is, the basic compound (C-2) is dissolved in water to a concentration of 0.1 mol/l, and the pH of the resulting aqueous solution at 25°C is measured using a pH meter.

The valence of the basic compound (C), ie, the valence of the base, is preferably monovalent. If the valence of the basic compound (C) is monovalent, it can stably exist in the conductive composition without impairing the solubility of the conductive polymer (A).

Basic compounds (C-1) include, for example, pyridine and picoline.
Basic compounds (C-2) include, for example, ammonia, methylamine, dimethylamine, and trimethylamine.
Any one of these compounds may be used alone, or two or more of these compounds may be used as a mixture in an arbitrary ratio.
The basic compound (C-2) may be used in the form of an aqueous solution.

The content of the basic compound (C) is preferably 5 to 90 mol parts, more preferably 5 to 80 mol parts, per 100 mol parts of units having an acidic group among the units constituting the conductive polymer (A). More preferably 5 to 70 mol parts. If the content of the basic compound (C) is within the above range, it will efficiently interact with the acidic groups in the solution of the conductive polymer (a).

The total content of the basic compound (B) and the basic compound (C) is preferably 10 mol parts or more per 100 mol parts of units having an acidic group among the units constituting the conductive polymer (A). , more preferably 15 mol parts or more, and more preferably 20 mol parts or more. If the total content of the basic compound (B) and the basic compound (C) is at least the above lower limit, the conductive polymer (A) is sufficiently neutralized, and the stability of the conductive polymer (A) is better. In addition, aggregation or precipitation of the conductive polymer (A) can be suppressed, and the liquid stability of the conductive composition is also improved.
The effect of improving the stability of the conductive polymer (A) and the liquid stability of the conductive composition tends to increase as the total content of the basic compound (B) and the basic compound (C) increases. If it is too much, it will only hit the head. Therefore, the total content of the basic compound (B) and the basic compound (C) is 90 mol parts or less per 100 mol parts of units having an acidic group among the units constituting the conductive polymer (A). is preferred, and 85 mol parts or less is more preferred.

The mass ratio of the basic compound (B) to the basic compound (C) is preferably basic compound (B): basic compound (C) = 5:95 to 95:5, and 10:90 to 95:5. More preferably, 10:90 to 90:10 is even more preferable. If the mass ratio of the basic compound (B) and the basic compound (C) is within the above range, the basic compound (B) that remains in the conductive film without volatilizing when the conductive film is formed, and the volatilizing The ratio with the basic compound (C) to be used becomes more appropriate. As a result, in the conductive film, the ratio of the acidic group forming a salt with the basic compound (B) and the acidic group in the free state becomes more moderate, suppressing film loss of the resist layer and increasing the conductivity. Excellent balance with film conductivity.

<Water (D)>
Examples of water include tap water, ion-exchanged water, pure water, and distilled water.
The content of water (D) is preferably 50 to 99.85% by mass, more preferably 60 to 99.85% by mass, and even more preferably 70 to 99.85% by mass with respect to the total mass of the conductive composition. .
The conductive polymer (A) is used in a state of being purified and dispersed or dissolved in an aqueous medium such as water (hereinafter, the conductive polymer (A) in this state is also referred to as a "conductive polymer solution"). When using an aqueous solution of the basic compound (C-2), the water derived from the conductive polymer solution, the water derived from the aqueous solution of the basic compound (C-2) is also the water (D) in the conductive composition. included in the content of

<Optional component>
The conductive composition may optionally contain components (optional components) other than the conductive polymer (A), basic compound (B), basic compound (C) and water (D).
Examples of optional components include surfactants, organic solvents, polymer compounds, pigments, antifoaming agents, ultraviolet absorbers, antioxidants, heat resistance improvers, leveling agents, anti-sagging agents, matting agents, preservatives, and the like. is mentioned.

(Surfactant)
If the conductive composition contains a surfactant, the coatability of the conductive composition is improved when the conductive composition is applied to the surface of the resist layer.
Examples of surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorine-based surfactants, and the like. These surfactants may be used singly or as a mixture of two or more in any ratio.
Among these, nonionic surfactants are preferred because they have little effect on the resist layer, and water-soluble polymers having nitrogen-containing functional groups and terminal hydrophobic groups are particularly preferred. 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.

The content of the surfactant is preferably 5 to 80 parts by mass when the total of the conductive polymer (A), the basic compound (B), the basic compound (C) and the surfactant is 100 parts by mass. , more preferably 10 to 70 parts by mass, more preferably 10 to 65 parts by mass. If the content of the surfactant is within the above range, the applicability of the conductive composition to the resist layer is further improved.

(Organic solvent)
Examples of organic solvents include alcohols such as methanol, ethanol, isopropyl alcohol, propyl alcohol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and ethyl isobutyl ketone, ethylene glycol, ethylene glycol methyl ether, ethylene glycol mono -ethylene glycols such as n-propyl ether, propylene glycols such as propylene glycol, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether and propylene glycol propyl ether, amides such as dimethylformamide and dimethylacetamide, N- pyrrolidones such as methylpyrrolidone and N-ethylpyrrolidone; and hydroxyesters such as methyl lactate, ethyl lactate, methyl β-methoxyisobutyrate and methyl α-hydroxyisobutyrate.
When the conductive composition contains an organic solvent, the mass ratio of water (D) to the organic solvent (water/organic solvent) is preferably 1/100 to 100/1, and 2/100 to 100/2. It is more preferable to have

(Polymer compound)
The conductive composition may contain a polymer compound, if necessary, for the purpose of improving coating film strength and surface smoothness.
Specific 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; Polyvinylpyrrolidone, polyacrylic acids, water-soluble alkyd resin, water-soluble melamine resin, water-soluble urea resin, water-soluble phenol resin, water-soluble epoxy resin, water-soluble polybutadiene resin, water-soluble acrylic resin, water-soluble urethane resin, water-soluble acrylic Examples include styrene copolymer 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.

<Manufacturing method>
The conductive composition is obtained by mixing a conductive polymer (A), a basic compound (B), a basic compound (C), water (D), and optionally optional components. .
As the conductive polymer (A), a purified conductive polymer (A) is preferably used. The conductive polymer (A) after purification is obtained in the form of a conductive polymer solution as described above. Therefore, the basic compound (B), the basic compound (C), and optional components are added to the conductive polymer solution, and if necessary, water is added to dilute the conductive composition. can manufacture things.
When a solid conductive polymer (A) is used, the solid conductive polymer (A) and water (D) are mixed in advance to prepare a conductive polymer solution, and the obtained conductive polymer It is preferable to add the basic compound (B) and the basic compound (C), and optionally optional components, to the solution.
The method of mixing each component is not particularly limited, and the conductive polymer (A), the basic compound (B), and the basic compound (C) may be uniformly mixed in the water (D). As a mixing method, an aqueous solution containing a conductive polymer (A), a basic compound (B), a basic compound (C), and water (C) is prepared using a stirring rod, a stirrer, a shaker, or the like. and a method of stirring.

When the conductive polymer (A), the basic compound (B) and the basic compound (C) come into contact with each other, a neutralization reaction proceeds. Although this neutralization reaction proceeds even at room temperature, the reaction is slow and is accelerated by heating. Therefore, it is preferable to heat an aqueous solution containing the conductive polymer (A), the basic compound (B), the basic compound (C), and water (D) to promote the neutralization reaction (neutralization process). Specifically, it is preferable to heat the conductive polymer solution and add the basic compound (B) and the basic compound (C) while stirring. Here, "room temperature" means 25°C.

<Effect>
As described above, when a conductive film is formed on a resist layer, if an acidic substance or the like migrates from the conductive film to the resist layer side, if the resist is of a positive type, the pattern becomes thinner, the film decreases, and the sensitivity increases. Sensitivity fluctuations were likely to occur. On the other hand, when the resist is of a negative type, changes in pattern shape and variations in sensitivity to the low sensitivity side tend to occur.
Further, there is a possibility that the acidic groups released from the conductive polymer (A) due to heating during formation of the conductive film or the like may migrate to the resist side.

However, according to the conductive composition of the first aspect of the present invention, since it contains the above-described conductive polymer (A), the basic compound (B), and the basic compound (C), the basic compound (B) and the basic compound (C) form a stable salt with the acidic group of the conductive polymer (A). Therefore, it becomes difficult for the acidic groups to leave or the conductive polymer (A) to decompose, and a conductive composition with a reduced proportion of acidic substances can be obtained. Specifically, the total content of acidic groups (free acidic groups) eliminated from the conductive polymer (A) and decomposition products (such as sulfate ions) of the oxidizing agent used in the production of the conductive polymer (A) can be reduced to 0.1% by mass or less with respect to the total mass of the conductive composition. In addition, the total content of the raw material monomers of the conductive polymer (A) and the decomposition products of the conductive polymer (A) can be reduced to 0.1% by mass or less with respect to the total mass of the conductive composition. For example, when the acidic group is a sulfonic acid group, the free acidic group is a sulfate ion.
As described above, the conductive composition of the first aspect of the present invention has a reduced proportion of acidic substances. Hard to migrate to the resist layer side.
Therefore, especially in the pattern formation method using a charged particle beam using a chemically amplified resist, migration of acidic substances from the conductive film to the resist layer side can be suppressed, and effects such as thinning of the resist layer can be suppressed.

Moreover, the basic compound (C) volatilizes during the formation of the conductive film. By volatilizing the basic compound (C), some of the acidic groups of the conductive polymer (A) become free, so sufficient conductivity can be exhibited.
On the other hand, since the basic compound (B) remains in the conductive film, it maintains the state of forming a salt with the acidic group of the conductive polymer (A) even in the conductive film. Therefore, since the acidic group forming the salt is stable, it is difficult to detach even when heated, and migration to the resist side can be suppressed.

<Application>
The conductive composition of the first aspect of the present invention is suitable for antistatic resist. Specifically, the conductive composition of the first aspect 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 first aspect of the present invention can also be used as a material for capacitors, transparent electrodes, semiconductors, and the like.

[Manufacturing method of conductor]
A method for producing a conductor according to the second aspect of the present invention comprises a step of applying the conductive composition of the first aspect of the present invention on at least one surface of a substrate (application step); and a step of heat-treating the conductive composition at 40° C. or higher (heat treatment step).

<Coating process>
The coating step is a step of coating the conductive composition of the first aspect of the present invention on the substrate.
The substrate is not particularly limited as long as it has the effect of the present invention, but polyester resins such as PET and PBT, polyethylene, polyolefin resins represented by polypropylene, vinyl chloride, nylon, polystyrene, polycarbonate, epoxy resin, fluororesin, Polysulfone, polyimide, polyurethane, phenolic resin, silicone resin, synthetic paper, and other high-molecular compound moldings, films, paper, iron, glass, quartz glass, various wafers, aluminum, copper, zinc, nickel, stainless steel, etc. , and those in which the surface of these substrates is coated with various paints, photosensitive resins, resists, or the like.
The shape of the substrate is not particularly limited, and may be a plate shape or a shape other than the plate shape.

The conductive composition is preferably applied onto the substrate so that the thickness of the coating film after drying is 5 to 30 nm.
The method of applying the conductive composition to the substrate is not particularly limited as long as the effect of the present invention is achieved, and may be spin coating, spray coating, dip coating, roll coating, gravure coating, or reverse coating. , a roll brush method, an air knife coating method, a curtain coating method, and the like.

The coating step may be performed before or during the manufacturing process of the substrate, such as uniaxial stretching, biaxial stretching, molding, or embossing. can also be done.
Moreover, it is also possible to overcoat the conductive composition on the above base material coated with various paints or photosensitive materials.

<Heating process>
A heating process is a process of heat-processing the electrically conductive composition apply|coated on the base material at 40 degreeC or more.
The heat treatment can be performed under atmospheric pressure or reduced pressure.
The heating temperature is 40°C or higher, preferably 40 to 200°C, more preferably 50 to 180°C. When the heating temperature is 40° C. or higher, the basic compound (C) in the conductive composition is sufficiently volatilized, and a conductive film having excellent conductivity can be formed.
The heating time is preferably 0.5 minutes to 1 hour, more preferably 1 to 50 minutes.

[Method of forming a resist pattern]
<Third aspect>
The method for forming a resist pattern according to the third aspect of the present invention comprises:
The conductive composition of the first aspect of the present invention is applied to the surface of the resist layer of a substrate having a resist layer made of a chemically amplified resist on one side, and the applied conductive composition is heated at 40° C. or higher. A step of processing to form a conductive film (lamination step);
a step of patternwise irradiating the substrate with an electron beam from the conductive film side (exposure step);
After the exposure step, a step of heating the substrate (post-exposure bake step, hereinafter also referred to as “PEB step”);
After the PEB step, a step of removing the conductive film by washing with water and developing the resist layer to form a resist pattern (washing/developing step);
have

(Lamination process)
In the lamination step, the conductive composition of the first aspect of the present invention is applied to the surface of the resist layer of a substrate having a resist layer made of a chemically amplified resist on one side, and the applied conductive composition is applied to the surface of the resist layer. C. or higher to form a conductive film.
The substrate is not particularly limited as long as it has the effect of the present invention, but glass, quartz glass, various wafers, aluminum, copper, zinc, nickel, tantalum, stainless steel, etc., and various paints and photosensitive resins on the surface of these substrates. are coated.

A resist layer made of a positive or negative chemically amplified resist is provided on one side of the substrate.
The positive type chemically amplified resist is not particularly limited as long as it has sensitivity to electron beams, and known ones can be used. Typically, one containing an acid generator that generates an acid upon electron beam irradiation and a polymer containing a structural unit having an acid-decomposable group is used.
A positive resist layer can be formed by a known method. For example, a positive resist layer can be formed by applying an organic solvent solution of a chemically amplified resist onto one side of the substrate and, if necessary, heating (pre-baking) it.

The negative type chemically amplified resist is not particularly limited as long as it has sensitivity to electron beams, and known ones can be used. Typically, one containing an acid generator that generates an acid when irradiated with an electron beam, a developer-soluble polymer, and a cross-linking agent is used.
The negative resist layer can be formed by a known method, similarly to the positive resist layer.

The conductive film is formed by applying the conductive composition of the first aspect of the present invention described above to the surface of the resist layer, and heat-treating the applied conductive composition at 40° C. or higher. As a result, a laminate in which the substrate, the resist layer, and the conductive film are laminated in this order is obtained.
Examples of the coating method and heat treatment conditions of the conductive composition include the coating method and heat treatment conditions exemplified above in the description of the method for producing the conductor.
The film thickness of the conductive film is preferably 5 to 30 nm.

(Exposure process)
The exposure step is a step of patternwise irradiating the substrate with an electron beam from the conductive film side.
The exposure step forms a latent image in the resist layer between the substrate and the conductive film.
At this time, since the conductive film is provided on the surface of the resist layer, the conductive film can be grounded, and the entire substrate can be prevented from being charged. Therefore, it is possible to suppress the positional deviation of electrons incident on the resist layer due to the effects of charging, and to form a latent image corresponding to the desired resist pattern with high accuracy.

(PEB process)
The PEB process is a process of heating (PEB) the substrate after the exposure process.
By heating the substrate that has been irradiated with electron beams in the exposure process, in the case of a positive resist layer, the reaction is accelerated by the action of the acid generated from the acid generator in the electron beam irradiated area (exposed area), and the developing solution increased solubility in On the other hand, in the case of a negative resist layer, the solubility in the developer decreases.
Heating of the substrate can be performed by a known method such as using a hot plate. The heating conditions vary depending on the resist, but are preferably 200° C. or less and within 1 hour from the viewpoint of the heat resistance of the conductive film.

(Washing and developing process)
In the water washing/development step, after the PEB step, the conductive film is removed by washing with water, and the resist layer is developed to form a resist pattern.
Since the conductive film is water-soluble, the conductive film is dissolved and removed by washing with water.
Water washing indicates contacting with an aqueous liquid. Examples of the aqueous liquid include simple water, water containing at least one of a base and a basic salt, water containing an acid, a mixture of water and a water-soluble organic solvent, and the like.

When the positive resist layer is developed, the electron beam irradiated portions (exposed portions) of the positive resist layer are dissolved and removed, forming a resist pattern consisting of the electron beam unirradiated portions (unexposed portions) of the positive resist layer. be done.
On the other hand, when the negative resist layer is developed, the electron beam unirradiated portion (unexposed portion) is dissolved and removed in the opposite direction to the positive resist layer, and the electron beam irradiated portion (exposed portion) of the negative resist layer is removed. ) is formed.

The washing/development step can be performed, for example, by the following method (α) or (β).
Method (α): Using an alkaline developer for washing, the conductive film is removed and the resist layer is developed.
Method (β): Only the conductive film is removed by washing with water, and then the resist layer is developed with a developer.

The alkaline developer (aqueous alkaline solution) used in the method (α) is not particularly limited, and known ones can be used. For example, tetramethylammonium hydroxide aqueous solution and the like can be mentioned.
The water washing of the method (β) can be carried out using an aqueous solution that does not correspond to a developer, such as water. Development can be carried out using an alkaline developer as in method (α).

(other forms)
The method of forming a resist pattern according to the third aspect may include a step of storing the substrate (storage step) between the lamination step and the exposure step.
If a storage period is provided after the lamination process, the resist layer is affected by the conductive film during that time, and the thickness of the resist layer after development in the non-electron-beam-irradiated portion is thinner than when the storage period is not provided. tend to become
Storage conditions such as storage period, temperature, and humidity in the storage step are not particularly limited as long as the effect of the present invention is achieved, but preferably within 2 months, 5° C. to 30° C., and 70% or less.

Further, after the water washing/developing process, the substrate may be rinsed with pure water or the like, if necessary.
After the water washing/development step or after the rinse treatment, the substrate having the resist pattern formed thereon may be heated (post-baked), if necessary.

<Fourth Aspect>
The method for forming a resist pattern according to the fourth aspect of the present invention comprises:
The conductive composition of the first aspect of the present invention is applied to the surface of the resist layer of a substrate having a resist layer made of a chemically amplified resist on one side, and the applied conductive composition is heated at 40° C. or higher. A step of processing to form a conductive film (lamination step);
a step of patternwise irradiating the substrate with an electron beam from the conductive film side (exposure step);
After the exposure step, a step of removing the conductive film by washing with water (water washing step);
After the water washing step, a step of heating the substrate (PEB step);
After the PEB step, a step of developing the resist layer to form a resist pattern (development step);
have

The resist pattern forming method of the fourth aspect is the same as the resist pattern forming method of the third aspect except that the conductive film is removed by water washing after the exposure step and before the PEB step.

If the conductive film is present during PEB, the acid groups and the like released in the conductive film may migrate to the resist layer due to heat, affecting the resist pattern. In the resist pattern forming method of the fourth aspect, by removing the conductive film before the PEB process, the resist layer can be prevented from being affected by the conductive film during PEB, and the influence of the conductive film can be further reduced. A small number of resist patterns can be formed.
The water washing step can be carried out in the same manner as the water washing in the water washing/developing step of the resist pattern forming method of the third aspect.

The resist pattern forming method of the fourth aspect may include a step of storing the substrate (storage step) between the lamination step and the exposure step. The storage step is the same as the storage step of the resist pattern forming method of the third aspect.
After the development step, the substrate may be rinsed with pure water or the like, if necessary.
After developing or rinsing, the substrate having the resist pattern formed thereon may be heated (post-baked), if necessary.

<Effect>
According to the resist pattern forming methods of the third and fourth aspects of the present invention described above, the conductive film formed from the conductive composition of the first aspect of the present invention is provided on the surface of the resist layer. Since the exposure process is performed in this state, it is possible to prevent electrification of the entire substrate while suppressing thinning of the resist layer. Therefore, it is possible to suppress the positional deviation of electrons incident on the resist layer due to the effects of charging, and to form a latent image corresponding to the desired resist pattern with high accuracy.

[Method for producing patterned substrate]
A method for manufacturing a substrate having a pattern formed thereon is a step of forming a resist pattern by the method for forming a resist pattern according to the above-described third and fourth aspects of the present invention to obtain a substrate having a resist pattern formed on one side thereof. (resist pattern forming step).
The resist pattern step yields a substrate having a resist pattern on one side.

The method for manufacturing a patterned substrate may further include, after the resist patterning step, etching the obtained substrate using the resist pattern as a mask (etching step).
Moreover, when the resist pattern remains on the substrate after the etching step, the method may further include a step of removing the resist pattern on the substrate with a remover.

A patterned substrate is obtained as described above. For example, a photomask can be manufactured by using a substrate including a transparent substrate and a light shielding film provided on the surface thereof, and etching the light shielding film in an etching process.

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 pH>
A measurement sample (basic compound) was dissolved in water to a concentration of 0.1 mol/l, and the pH of the resulting aqueous solution at 25°C was measured using a pH meter.

<Measurement of content of acidic substances>
A test solution was prepared by adding the following eluent to the conductive composition. For the resulting test solution, the concentration of acidic substances was measured under the following ion chromatography (IC) measurement conditions to obtain a chromatogram. The area or height of the peak corresponding to the acidic substance on the obtained chromatogram was read, and the content of the acidic substance with respect to the total mass of the conductive composition was determined from a previously prepared calibration curve. The content of the acidic substance is the total amount of the content of the raw material monomer of the conductive polymer (A) and the decomposition product of the conductive polymer (A) (collectively referred to as "residual monomer"), and the content of the conductive polymer (A). and the total content of the acidic groups eliminated from the conductive polymer (A) and the decomposition products of the oxidizing agent used in the production of the conductive polymer (A) (these are collectively referred to as "sulfate ions"). measured by
<<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

<Evaluation of conductivity>
1.3 mL of the conductive composition was dropped on a 4-inch silicon wafer as a substrate, and the entire substrate surface was coated with a spin coater at 2000 rpm for 60 seconds. C. for 3 minutes to form a conductive film having a film thickness of about 20 nm on the base material to obtain 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). A surface resistance value of less than 1×10 ¹⁰ Ω/□ was evaluated as “◯”, and a surface resistance value of 1×10 ¹⁰ Ω/□ or more was evaluated as “X”, and “◯” was evaluated as acceptable.

<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 layer thickness b [nm] 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)
By subtracting 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, components such as free acidic groups transferred from the conductive film to the resist layer and decomposition products of the conductive polymer (A) The amount of film reduction f [nm] (f=cd) of the resist layer caused by is calculated. A film reduction amount (f = cd) of less than 5 nm was evaluated as "◯", and a film reduction amount of 5 nm or more was evaluated as "X", and "◯" was evaluated as a pass.

<Evaluation of liquid stability>
The conductive composition was left at 25° C. for 1 week. The conductive composition after standing was visually observed, and the liquid stability of the conductive composition was evaluated according to the following evaluation criteria.
◯: Precipitates and aggregates are not observed.
x: At least one of precipitates and aggregates is confirmed.

[Production of conductive polymer (A)]
(Production Example 1: Production of conductive polymer (A-1))
1 mol of 3-aminoanisole-4-sulfonic acid was dissolved in 300 mL of a 4 mol/l concentration pyridine solution (solvent: water/acetonitrile=3/7 (mass ratio)) at 0° C. to obtain a monomer solution.
Separately, 1 mol of ammonium peroxodisulfate was dissolved in 1 L of a solution of water/acetonitrile=3/7 (mass ratio) to obtain an oxidant solution.
Then, while cooling the oxidant solution to 5° C., the monomer solution was added dropwise. After the dropwise addition was completed, the mixture was further stirred at 25° C. for 12 hours to obtain a conductive polymer. Thereafter, the resulting reaction mixture containing the conductive polymer was filtered using a centrifugal filter. Furthermore, it was washed with methanol and then dried to obtain 185 g of powdery conductive polymer (A-1).

(Production Example 2: Production of conductive polymer solution (A1-1))
20 g of the conductive polymer (A-1) obtained in Production Example 1 was dissolved in 980 g of pure water to obtain 1000 g of a conductive polymer solution (A-1-1) having a solid concentration of 2% by mass.
A column was packed with 500 mL of a cation exchange resin (“Amberlite IR-120B” manufactured by Organo Co., Ltd.) washed with ultrapure water.
1000 g of the conductive polymer solution (A-1-1) is passed through this column at a rate of 50 mL/min (SV=6) to remove basic substances and the like from the conductive polymer solution (A1-1- 1) was obtained in an amount of 900 g.
Next, a column was filled with 500 mL of an anion exchange resin (“Amberlite IRA410” manufactured by Organo Corporation) washed with ultrapure water.
900 g of the conductive polymer solution (A1-1-1) is passed through this column at a rate of 50 mL/min (SV=6) to remove the basic substances, etc. from the conductive polymer solution (A1-1). 800 g of was obtained.
Composition analysis of this conductive polymer solution (A1-1) by ion chromatography revealed that 80% by mass of residual monomers, 99% by mass of sulfate ions, and 99% by mass or more of basic substances (pyridine) were removed. . In addition, as a result of measuring the heating residue, it was 2.0% by mass. That is, the conductive polymer solution (A1-1) had a solid content concentration of 2.0% by mass.
Note that one sveldlap (SV) is defined as 1×106 m ³ /s (1 GL/s).

[Example 1]
While stirring 5 parts by mass of the conductive polymer solution (A1-1) (0.1 parts by mass in terms of solid content), tetrabutylammonium hydroxide (TBAH, boiling point: 135 ° C., pH: 13.06) 0.05 parts by mass and 0.008 parts by mass of pyridine (boiling point: 115 ° C., pH: 8.99) as a basic compound (C) are added, and 94.942 parts by mass of water is added. to obtain a conductive composition.
The content of acidic substances was measured for the obtained conductive composition. In addition, conductivity and liquid stability were evaluated, and a film reduction test was performed. These results are shown in Table 1.

[Example 2]
Instead of tetrabutylammonium hydroxide, add 0.014 parts by mass of tetramethylammonium hydroxide (TMAH, boiling point: 135 ° C., pH: 13.01), change the amount of water added to 89.978 parts by mass, A conductive composition was produced in the same manner as in Example 1 except that 5 parts by mass of isopropyl alcohol (IPA) was further added, and various measurements and evaluations were performed. Table 1 shows the results.

[Example 3]
0.014 parts by mass of tetramethylammonium hydroxide was added instead of tetrabutylammonium hydroxide, and 25% by mass ammonia water (boiling point of ammonia: −33.3° C., pH: 11.07) was added instead of pyridine. 013 parts by mass (0.00325 parts by mass in terms of pure content) was added, the amount of water added was changed to 86.973 parts by mass, and 8 parts by mass of isopropyl alcohol was added. A conductive composition was produced in the same manner, and various measurements and evaluations were performed. Table 1 shows the results.

[Comparative Example 1]
In the same manner as in Example 1, except that 0.014 parts by mass of tetramethylammonium hydroxide was added instead of tetrabutylammonium hydroxide, pyridine was not added, and the amount of water added was changed to 94.986 parts by mass. A conductive composition was produced by the method, and various measurements and evaluations were performed. Table 1 shows the results.

[Comparative Example 2]
0.03 parts by mass of tetramethylammonium hydroxide was added instead of tetrabutylammonium hydroxide, pyridine was not added, the amount of water added was changed to 89.97 parts by mass, and isopropyl alcohol (IPA) 5 was added. A conductive composition was produced in the same manner as in Example 1 except that parts by mass were further added, and various measurements and evaluations were performed. Table 1 shows the results.

[Comparative Example 3]
Conductive composition in the same manner as in Example 1 except that tetrabutylammonium hydroxide was not added, the amount of pyridine added was changed to 0.025 parts by mass, and the amount of water added was changed to 94.975 parts by mass. A product was manufactured, and various measurements and evaluations were performed. Table 1 shows the results.

The blending amount of each component in Table 1 is in terms of solid content or pure content. The amount of water to be blended includes the amount of water derived from the conductive polymer solution (A1-1) and 25% by mass ammonia water.
Further, in Table 1, "(B)/(A)" represents the content (mol parts ). "(C)/(A)" is the content (mol parts) of the basic compound (C) with respect to 100 mol parts of units having an acidic group among the units constituting the conductive polymer (A).
Moreover, "(B):(C)" is the mass ratio of the basic compound (B) to the basic compound (C).

As is clear from Table 1, the conductive compositions of Examples 1 to 3 were able to form conductive films with less film loss in the resist layer and excellent conductivity. Moreover, the conductive compositions of Examples 1 to 3 were also excellent in liquid stability.
On the other hand, the conductive composition of Comparative Example 1 contained a large amount of acidic substances, and the resist layer was easily thinned. Moreover, the conductive composition of Comparative Example 1 was also inferior in liquid stability.
Since the conductive composition of Comparative Example 2 had a higher content of the basic compound (B) than that of Comparative Example 1, the film loss of the resist layer was small and the liquid stability was excellent. Poor conductivity. In the case of Comparative Example 2, an increase in the amount of acidic substances in the conductive composition was suppressed by an increase in the basic compound (B). However, the proportion of acidic groups in the conductive polymer (A) forming a salt with the basic compound (B) in the conductive film was greater than in Comparative Example 1, and sufficient conductivity was not exhibited. It is considered to be a thing.
The conductive composition of Comparative Example 3 was excellent in liquid stability and excellent in conductivity of the conductive film, but the resist layer was easily thinned. In the case of Comparative Example 3, an increase in acidic substances in the conductive composition was suppressed. However, since the basic compound (C) volatilized during the formation of the conductive film (heat treatment), many acidic groups of the conductive polymer (A) exist in a free state, and these free acidic groups desorbed from the conductive polymer (A) during the baking treatment and migrated to the resist layer.

INDUSTRIAL APPLICABILITY The conductive composition of the present invention can form a conductive film having excellent conductivity with less film loss of the resist layer, and is useful for antistatic of the resist.

Claims (7)

A conductive composition for antistatic resist,
A conductive polymer (A) having an acidic group;
a basic compound (B) having a boiling point of 110° C. or higher and a pH of 11.50 or higher at 25° C. in an aqueous solution with a concentration of 0.1 mol/l;
a basic compound (C-1) having a pH of less than 11.50 at 25° C. in an aqueous solution with a concentration of 0.1 mol/l;
water (D);
including
Conductivity , wherein the mass ratio of the basic compound (B) and the basic compound (C-1) is basic compound (B):basic compound (C-1) = 5:95 to 95:5. sex composition. A conductive composition for antistatic resist,
A conductive polymer (A) having an acidic group;
a basic compound (B) having a boiling point of 110° C. or higher and a pH of 11.50 or higher at 25° C. in an aqueous solution with a concentration of 0.1 mol/l;
a basic compound (C-2) having a boiling point of less than 40°C;
water (D);
including
Conductive , wherein the mass ratio of the basic compound (B) and the basic compound (C-2) is basic compound (B):basic compound (C-2) = 5:95 to 95:5. sex composition. The electrically conductive composition according to claim 1 or 2 , wherein the basic compound (B) has a monovalent valence. The conductive composition according to any one of claims 1 to 3 , wherein the basic compound (C-1) and the basic compound (C-2) have a valence of 1. The conductive composition according to any one of claims 1 to 4 , wherein the conductive polymer (A) has units represented by the following general formula (1).

In formula (1), R ¹ to R ⁴ 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, represents an acidic group, a hydroxy group, a nitro group, or a halogen atom, and at least one of R ¹ to R ⁴ is an acidic group or a salt thereof. Here, the acidic group is a sulfonic acid group or a carboxy group. A step of applying the conductive composition according to any one of claims 1 to 5 on at least one surface of a substrate, and a step of heat-treating the applied conductive composition at 40 ° C. or higher. A method for manufacturing a conductor, comprising: The conductive composition according to any one of claims 1 to 5 is applied to the surface of the resist layer of a substrate having a resist layer made of a chemically amplified resist on one side, and the coated conductive composition. is heated at 40° C. or higher to form a conductive film, and the substrate is irradiated with electron beams in a pattern from the conductive film side.