JP2018189731A - Composition for forming resist overlay film, and pattern forming method and method for manufacturing electronic device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming a resist overlay film, which allows formation of an underlay pattern having fewer defects and excellent roughness performance when the underlay is etched by using a fine resist pattern (for example, a line pattern having a line width of about 75 nm) as a process mask, and a pattern forming method and a method for manufacturing an electronic device.SOLUTION: The composition for forming a resist overlay film comprises a polymer (P) having a repeating unit represented by general formula (1) below, in which the total content of metals is 25 ppb or less. A pattern forming method and a method for manufacturing an electronic device using the above composition are also provided. In general formula (1), L represents a single bond, -COO- or -CONR-; and R, Rand R each independently represent a hydrogen atom or a monovalent organic group.SELECTED DRAWING: None

Description

  The present invention relates to a composition for forming a resist upper layer film that is suitably used particularly for immersion exposure, and a pattern forming method and an electronic device manufacturing method using the same.

Conventionally, in a manufacturing process of a semiconductor device such as an IC, fine processing by lithography using various resist compositions has been performed. As a method, a resist film is formed on a substrate with a resin composition containing a polymer having an acid-dissociable group, exposed by irradiation with short-wavelength radiation such as an excimer laser, and processed with a developer. A resist pattern is formed. Under the present circumstances, the chemical amplification type resist which contained the radiation sensitive acid generator which generate | occur | produces an acid by irradiation and improved the sensitivity by the effect | action of the acid is utilized.
Nowadays, for example, as a method for forming a resist pattern having a line width of about 90 nm, the use of an immersion exposure method is expanding. This method has the advantage that even when the numerical aperture (NA) of the lens is increased, the depth of focus is unlikely to decrease and high resolution can be obtained.

  On the other hand, when a chemically amplified resist is applied to immersion exposure, the resist layer comes into contact with the immersion liquid at the time of exposure, so that the resist layer is altered and components that adversely affect the immersion liquid are leached from the resist layer. It has been known.

  As a solution for avoiding such a problem, a method is known in which a resist upper layer film is provided between a resist and a lens so that the resist and water do not come into direct contact with each other (for example, Patent Documents 1 and 2).

JP 2014-56194 A International Publication No. 2013/069750

However, in recent years, the need for pattern miniaturization has further increased, and in response to this, a particularly fine resist pattern (for example, a line pattern having a line width of about 75 nm) is formed from a resist film. When trying to etch a lower layer using a pattern as a processing mask, it is required to obtain a lower layer pattern having better performance.
The present invention has been made in view of the above problems, and its purpose is that when the lower layer is etched using a fine resist pattern (for example, a line pattern having a line width of about 75 nm) as a processing mask, there are few defects, And it is providing the composition for resist upper layer film formation which can form the lower layer pattern excellent in roughness performance, the pattern formation method using the same, and the manufacturing method of an electronic device.

  The present invention has the following configuration, whereby the above object of the present invention is achieved.

[1]
A resist upper layer film-forming composition comprising a polymer (P) having a repeating unit represented by the following general formula (1), wherein the total metal content is 25 ppb or less.

In the general formula (1), L represents a single bond, —COO—, or —CONR—. R ₀ , R ₅ and R each independently represent a hydrogen atom or a monovalent organic group.
[2]
The composition for forming a resist upper layer film according to [1], wherein the polymer (P) is a polymer having a repeating unit represented by the following general formula (i) or (ii).

In the general formula (i), R ₁ represents a single bond or a divalent linking group. R ₂ and R ₃ each independently represents a monovalent organic group having a fluorine atom. R ₄ represents a hydrogen atom or a base dissociable group. R ₅ represents a monovalent organic group.
In the general formula (ii), Ra represents a monovalent organic group. Rf represents a hydrocarbon group having a fluorine atom.
[3]
The composition for forming a resist upper layer film according to [1] or [2], wherein the solid content concentration of the composition for forming a resist upper layer film is 0.1 to 15% by mass.
[4]
A method for producing a polymer, wherein the polymer (P) having a repeating unit represented by the following general formula (1) is purified by liquid-liquid extraction using an organic solvent and water containing an acidic compound. .

In the general formula (1), L represents a single bond, —COO—, or —CONR—. R ₀ , R ₅ and R each independently represent a hydrogen atom or a monovalent organic group.
[5]
Furthermore, the method for producing a polymer according to [4], wherein any one of the following liquid separation purification (1) to (4) is performed on the polymer (P).
(1) Purification by liquid-liquid extraction using a plurality of organic solvents that can be separated from each other (2) Purification by liquid-liquid extraction using an organic solvent and water (3) Precipitating the polymer (P) in the polymerization apparatus The polymer (P) is dissolved in the organic solvent in the polymerization apparatus and the polymer (P) is obtained in a state dissolved in the organic solvent without obtaining the polymer (P) as powder. (4) After depositing the polymer (P) in the polymerization apparatus, the polymer (P) is dissolved in the organic solvent in the polymerization apparatus, and the polymer (P) dissolved in the organic solvent is further dissolved. A method of obtaining a polymer (P) in a state dissolved in an organic solvent without purifying the polymer (P) as a powder by purification by liquid-liquid extraction [6]
A step of forming a resist upper layer film on the resist film by the resist upper layer film forming composition according to any one of [1] to [3];
Exposing the resist film; and
A pattern forming method comprising a step of developing the exposed resist film with a developer.
[7]
The pattern forming method according to [6], wherein the exposure is immersion exposure.
[8]
The pattern forming method according to [6] or [7], wherein the developer is a developer containing an organic solvent.
[9]
The pattern forming method according to [6] or [7], wherein the developer is an alkali developer.
[10]
The manufacturing method of an electronic device containing the pattern formation method of any one of [6]-[9].

  According to the present invention, when a lower layer is etched using a fine resist pattern (for example, a line pattern having a line width of about 75 nm) as a processing mask, a lower layer pattern with few defects and excellent roughness performance can be formed. A composition for forming a resist upper layer film, a pattern forming method using the composition, and a method for manufacturing an electronic device can be provided.

Hereinafter, modes for carrying out the present invention will be described.
In addition, in the description of group (atomic group) in this specification, the description which is not describing substitution and non-substitution includes what has a substituent with what does not have a substituent. For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
“Actinic light” or “radiation” in the present specification means, for example, an emission line spectrum of a mercury lamp, far ultraviolet rays represented by an excimer laser, extreme ultraviolet rays (EUV light), X-rays, electron beams and the like. In the present invention, light means actinic rays or radiation. In addition, the term “exposure” in the present specification is not limited to exposure with far ultraviolet rays such as mercury lamps and excimer lasers, X-rays, EUV light, etc., but also particle beams such as electron beams and ion beams, unless otherwise specified. Include drawing in exposure.
In the present specification, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the dispersity (Mw / Mn) of the polymer in the resist upper layer film forming composition and the resin in the resist composition are GPC ( GPC measurement (solvent: tetrahydrofuran, flow rate (sample injection amount): 10 μl, column: TSK gel Multipore HXL-M (× 4), column temperature: 40 by Gel Permeation Chromatography) apparatus (HLC-8120GPC manufactured by Tosoh Corporation) (° C., flow rate: 1.0 mL / min, detector: differential refractive index (RI) detector).

  The resist upper layer film-forming composition according to the present invention contains a polymer (P) having a repeating unit represented by the following general formula (1), and the total content of metals is 25 ppb or less.

In the general formula (1), L represents a single bond, —COO—, or —CONR—. R ₀ , R ₅ and R each independently represent a hydrogen atom or a monovalent organic group.

  The resist upper layer film formed by the resist upper layer film forming composition is usually removed in the development process of the exposed resist film, but even when the lower layer is etched using the resist pattern as a processing mask, In order to form a lower layer pattern having few defects and excellent roughness performance, the present inventors have focused attention on the characteristics of the composition for forming a resist upper layer film. As a result, surprisingly, even when the lower layer is etched using a fine resist pattern (a line pattern having a line width of about 75 nm) as a processing mask, even the total content of metals in the resist upper layer film forming composition is surprising. It has been found that it cannot be ignored and can affect the performance of the resulting lower layer pattern. And based on this knowledge, the present inventors set the total content of metals in the resist upper layer film forming composition to 25 ppb or less, and when the lower layer was etched using the ultrafine resist pattern as a processing mask, It has been found that a lower layer pattern with few defects and excellent roughness performance can be formed.

  Hereinafter, each component which a polymer (P) may contain is demonstrated.

<Polymer (P)>
As described above, the resist upper layer film forming composition according to the present invention contains the polymer (P) having a repeating unit represented by the following general formula (1).

In the general formula (1), L represents a single bond, —COO—, or —CONR—. R ₀ , R ₅ and R each independently represent a hydrogen atom or a monovalent organic group.

The monovalent organic group as R ₀ , R ₅ and R preferably has 1 to 30 carbon atoms, and examples thereof include an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group and an alkenyl group. Can do. These groups may further have a substituent. Examples of the further substituent include an alkyl group (1 to 4 carbon atoms), a halogen atom, a hydroxyl group, an alkoxy group (1 to 4 carbon atoms), a carboxyl group, and an alkoxycarbonyl group (2 to 6 carbon atoms). It is done.
At least one of R ₀ , R ₅ and R is preferably an organic group having a fluorine atom or a silicon atom.

  The polymer (P) is preferably a polymer having a repeating unit represented by the following general formula (i) or (ii).

In the general formula (i), R ₁ represents a single bond or a divalent linking group. R ₂ and R ₃ each independently represents a monovalent organic group having a fluorine atom. R ₄ represents a hydrogen atom or a base dissociable group. R ₅ represents a monovalent organic group.
In the general formula (ii), Ra represents a monovalent organic group. Rf represents a hydrocarbon group having a fluorine atom.

The divalent linking group as R ₁ is, for example, a divalent chain hydrocarbon group (preferably having 1 to 20 carbon atoms), a divalent alicyclic hydrocarbon group (having 3 to 20 carbon atoms). A group in which one or more of the chain hydrocarbon group and the alicyclic hydrocarbon group are combined with -O-, and the like. R ₁ is preferably a single bond, a methanediyl group, an alkanediyloxy group having 2 to 4 carbon atoms, or a cycloalkanediyloxy group having 7 to 10 carbon atoms, and is a single bond, methanediyl group, 1,2- An ethanediyloxy group, a 1,2-propanediyloxy group, or a 2,6-norbornanediyloxy group is more preferable, and a 1,2-ethanediyloxy group is still more preferable.

The monovalent organic group having a fluorine atom as R ₂ and R ₃ is more preferably a trifluoromethyl group.

The monovalent organic group as R ₅ and Ra is preferably an alkyl group, more preferably an alkyl group having 1 to 3 carbon atoms, and still more preferably an alkyl group having 1 or 2 carbon atoms. .

The base dissociable group as R ₄ is, for example, a group that replaces a hydrogen atom of a hydroxy group, and is a group that dissociates in the presence of an alkali (for example, in an aqueous solution of 2.38% by mass of tetramethylammonium hydroxide (TMAH)). Say. The monovalent base dissociable group preferably has a carbonyl group or a sulfonyl group. With this base dissociable group, the solubility of the upper layer film composition in the developer can be improved particularly when an alkali developer is used as the developer, and defects such as bridge defects and blob defects are further suppressed. I can expect that.
R ₄ is more preferably a hydrogen atom.

  The hydrocarbon group having a fluorine atom as Rf is preferably a hydrocarbon group having 1 to 15 carbon atoms, and more preferably a hydrocarbon group having 1 to 10 carbon atoms.

  Specific examples of the monomer corresponding to the repeating unit represented by the general formula (1) are shown below, but the present invention is not limited thereto. Hereinafter, TMS represents a trimethylsilyl group.

The polymer (P) may have one type of repeating unit represented by the general formula (1), or may have two or more types.
The content of the repeating unit represented by the general formula (1) is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, based on all repeating units of the polymer (P). Preferably, it is 80-100 mol%, and it is still more preferable.

The polymer (P) can be synthesized according to a conventional method (for example, radical polymerization). For example, as a general synthesis method, a monomer polymerization method and a polymerization initiator are dissolved in a solvent and the polymerization is carried out by heating, and a solution of the monomer species and the polymerization initiator is added to the heating solvent over 1 to 10 hours. Examples thereof include a dropping polymerization method which is added dropwise, and a dropping polymerization method is preferred.
Examples of the reaction solvent include ethers such as tetrahydrofuran, 1,4-dioxane and diisopropyl ether; ketones such as methyl ethyl ketone and methyl isobutyl ketone; ester solvents such as ethyl acetate; amide solvents such as dimethylformamide and dimethylacetamide; And a solvent for dissolving the resist composition of the present invention, such as propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and cyclohexanone. More preferably, polymerization is performed using the same solvent as the solvent used in the composition for forming a resist upper layer film described later.

The polymerization reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon. As a polymerization initiator, a commercially available radical initiator (azo initiator, peroxide, etc.) is used to initiate the polymerization. As the radical initiator, an azo initiator is preferable, and an azo initiator having an ester group, a cyano group, or a carboxyl group is preferable. Preferred examples of the initiator include azobisisobutyronitrile, azobisdimethylvaleronitrile, dimethyl 2,2′-azobis (2-methylpropionate) and the like. Add initiator or add in portions as desired. The solid content concentration in the reaction solution is 5 to 50% by mass, preferably 10 to 45% by mass.
The reaction temperature is usually 10 ° C to 150 ° C, preferably 30 ° C to 120 ° C, more preferably 60-100 ° C.

  As described above, the composition for forming a resist upper layer film of the present invention is not particularly limited as long as the total metal content is 25 ppb or less. However, the resist film formed from the composition for forming a resist upper layer film has a large size. Since the portion can be occupied by the polymer (P), the total of the metal contents can be preferably 25 ppb or less by reducing the metal contained in the polymer (P) by purification. As a purification method of the polymer (P) for that purpose, it is preferable to perform purification by liquid-liquid extraction using an organic solvent and water containing an acidic compound on the polymer (P).

  Therefore, the present invention purifies the polymer (P) having the repeating unit represented by the general formula (1) by liquid-liquid extraction using an organic solvent and water containing an acidic compound. The present invention also relates to a method for producing a polymer.

  This is a metal contained in the polymer (P) synthesized by performing liquid-liquid extraction with an organic solvent in which the polymer (P) is dissolved and water containing an acidic compound. Surprisingly, the metal that can affect the performance of the lower layer pattern when the lower layer is etched using a resist pattern (line pattern with a line width of about 75 nm) as a processing mask is highly removed by water containing an acidic compound. This is based on the knowledge of the present inventors.

The organic solvent in the purification is preferably a nonpolar solvent, and examples of the nonpolar solvent include hydrocarbon solvents, ester solvents and ether solvents, preferably hexane, heptane, methyl acetate, Ethyl acetate, isopropyl acetate, butyl acetate (n-butyl acetate), pentyl acetate, hexyl acetate, isoamyl acetate, butyl propionate (n-butyl propionate), butyl butyrate, isobutyl butyrate, butyl butanoate, toluene, diethyl ether, Examples thereof include isopropyl ether, chloroform, and methylene chloride. As the nonpolar solvent, a solvent in which the polymer (P) is dissolved is preferable.
Moreover, as an acidic compound, hydrochloric acid, a sulfuric acid, phosphoric acid etc. can be mentioned, for example. The concentration of the acidic compound in the water containing the acidic compound is preferably 0.001 to 3N, and more preferably 0.01 to 1N.

  In the method for producing a polymer of the present invention, any one of the following liquid separation purification (1) to (4) may be further performed on the polymer (P). The following method is used in a reaction vessel (polymerization apparatus) in which the polymerization reaction of the polymer (P) is carried out from the viewpoint of preventing contamination of metal impurities during contact with the outside air of the synthesized polymer (P) and transfer. It is preferable to carry out as it is.

(1) Purification by liquid-liquid extraction using a plurality of organic solvents that can be separated from each other (2) Purification by liquid-liquid extraction using an organic solvent and water (3) Precipitating the polymer (P) in the polymerization apparatus And then the polymer (P) is dissolved in an organic solvent in the polymerization apparatus to obtain the polymer (P) in a state dissolved in the organic solvent without obtaining the polymer (P) as a powder. (4) After the polymer (P) is precipitated in the polymerization apparatus, the polymer (P) is dissolved in an organic solvent in the polymerization apparatus, and the polymer (P) dissolved in the organic solvent is further dissolved. A method for obtaining a polymer (P) in a state of being dissolved in an organic solvent without being purified as a powder and obtaining the polymer (P) as a powder.

The above (1) is a method of purifying the polymer (P) by liquid-liquid extraction using a plurality of types of organic solvents that can be separated from each other. Each of the plural types of organic solvents may be a single solvent or a mixed solvent. The combination of a plurality of types of organic solvents is not particularly limited as long as it is a combination that can be separated from each other. For example, a combination of hexane and methanol is preferable. According to the method (1), the effect of reducing impurities such as low molecular components and oligomers is also great.
The above (2) is a method of purifying the polymer (P) by liquid-liquid extraction using an organic solvent and water. The organic solvent is preferably a nonpolar solvent, and examples of the nonpolar solvent include those listed above. The water used for this purification does not contain the acidic compound.
The above (3) is a method for obtaining the polymer (P) as a liquid (in a state dissolved in an organic solvent) without obtaining the polymer (P) as a powder, and between the polymer (P) and the outside air. There is little concern about contamination due to contact.
The above (4) is a method for purifying the polymer (P) by liquid-liquid extraction in addition to the above (3). The reduction effect is great for any of low molecular components, oligomer components, and metal impurities.
Examples of “liquid-liquid extraction” in (4) above include purification by liquid-liquid extraction in (1) and (2) above.

  The above (1) to (4) may be performed before or after “purification by liquid-liquid extraction using an organic solvent and water containing an acidic compound”.

  As long as the total content of metals in the resist upper layer film-forming composition satisfies the above range, purification of the polymer (P) is not more than the above (1) to (4) and has a specific molecular weight or less. A purification method in a solution state such as ultrafiltration for extracting and removing only the resin, a reprecipitation method for removing residual monomers by coagulating the resin in the poor solvent by dropping the resin solution into the poor solvent, A solid state purification method such as washing the filtered resin slurry with a poor solvent may be appropriately performed.

  Dissolved in an organic solvent obtained through “liquid-liquid extraction of an organic solvent and water containing an acidic compound” and any of the above (1) to (4) that may be additionally performed. When the organic solvent and the solvent used in the resist upper layer film-forming composition are the same solvent, the polymer (P) in the state is the same as the polymer (P) dissolved in the organic solvent. It can be used as a solution for preparing a composition for forming an upper layer film. On the other hand, when the organic solvent that dissolves the polymer (P) and the solvent used in the resist upper layer film-forming composition are different solvents, in order to suppress the concern about contamination due to contact with the outside air, Without obtaining the polymer (P) in a dry state, the organic solvent for dissolving the polymer (P) was replaced with the solvent used for the resist upper layer film forming composition, and this was replaced with the resist upper layer film forming composition. It is preferable to use it as a solution for preparation.

The weight average molecular weight of the polymer (P) is preferably 1,000 to 200,000, more preferably 3,000 to 20,000, and most preferably 5,000 to 15 in terms of polystyrene by GPC method. , 000. By setting the weight average molecular weight to 1,000 to 200,000, deterioration of heat resistance and dry etching resistance can be prevented, and developability is deteriorated, and viscosity is increased, resulting in deterioration of film forming property. Can be prevented.
Another particularly preferable form of the weight average molecular weight of the polymer (P) is 3,000 to 9,500 in terms of polystyrene by GPC method.
The degree of dispersion (molecular weight distribution) is usually 1 to 5, preferably 1 to 3, more preferably 1.2 to 3.0, particularly preferably 1.2 to 2.0. .

  In the composition for forming a resist upper layer film, the polymer (P) may be used alone or in combination.

  The content of the polymer (P) is preferably 50 to 99.9% by mass and more preferably 60 to 99.0% by mass with respect to the total solid content of the resist upper layer film-forming composition.

The composition for forming a resist upper layer film is further selected from the group consisting of (A1) a basic compound or a base generator, or (A2) an ether bond, a thioether bond, a hydroxyl group, a thiol group, a carbonyl bond and an ester bond. It is preferable to contain at least one compound selected from the group consisting of compounds containing a bond or group.
Specific examples and preferred examples of the above compounds, and preferred ranges of the content of the composition for forming a resist upper layer film with respect to the total solids are the contents described in paragraphs [0141] to [0256] of International Publication No. 2016/136596. Can be used.

<Surfactant>
The composition for forming a resist upper layer film of the present invention may further contain a surfactant.
The surfactant is not particularly limited, and an anionic surfactant can be used as long as the composition for forming a resist upper layer film can be uniformly formed and can be dissolved in the solvent for the composition for forming a resist upper layer film. Any of cationic surfactants and nonionic surfactants can be used.
The addition amount of the surfactant is preferably 0.001 to 20% by mass, and more preferably 0.01 to 10% by mass.
Surfactant may be used individually by 1 type and may use 2 or more types together.

Examples of the surfactant include alkyl cationic surfactants, amide type quaternary cationic surfactants, ester type quaternary cationic surfactants, amine oxide surfactants, betaine surfactants, alkoxy Rate surfactants, fatty acid ester surfactants, amide surfactants, alcohol surfactants, ethylenediamine surfactants, and fluorine and / or silicon surfactants (fluorine surfactants, Those selected from silicon-based surfactants and surfactants having both fluorine atoms and silicon atoms can be preferably used.
Specific examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether; polyoxyethylene octylphenol ether, polyoxyethylene Polyoxyethylene alkyl allyl ethers such as nonylphenol ether; polyoxyethylene / polyoxypropylene block copolymers; sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate Sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene Nso sorbitan mono palmitate - DOO, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, surfactants such as polyoxyethylene sorbitan tristearate; commercial surfactants listed below; and the like.
Examples of commercially available surfactants that can be used include EFTOP EF301 and EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430, 431 and 4430 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F173 and F176. , F189, F113, F110, F177, F120, R08 (manufactured by Dainippon Ink & Chemicals, Inc.), Surflon S-382, SC101, 102, 103, 104, 105, 106 (manufactured by Asahi Glass Co., Ltd.), Troisol S -366 (manufactured by Troy Chemical Co., Ltd.), GF-300, GF-150 (manufactured by Toagosei Co., Ltd.), Surflon S-393 (manufactured by Seimi Chemical Co., Ltd.), F-top EF121, EF122A, EF122B, RF122C , EF125M, EF135M, EF351, 352, EF801, EF802, F601 (manufactured by Gemco), PF636, PF656, PF6320, PF6520 (manufactured by OMNOVA), FTX-204D, 208G, 218G, 230G, 204D, 208D, 212D, 218, 222D (manufactured by Neos) Fluorine type surfactant or silicon type surfactant can be mentioned. Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can also be used as a silicon-based surfactant.

<Solvent>
The composition for forming a resist upper layer film in the present invention usually contains a solvent.
In order to form a good pattern without dissolving the resist film, the composition for forming a resist upper layer film in the present invention preferably contains a solvent that does not dissolve the resist film, and a developer (organic) containing an organic solvent. In the case of developing using a system developer, it is more preferable to use a solvent having a component different from that of the organic developer.
Further, from the viewpoint of preventing elution into the immersion liquid, it is preferable that the solubility in the immersion liquid is low, and it is more preferable that the solubility in water is low. In the present specification, “low solubility in immersion liquid” indicates that the immersion liquid is insoluble. Similarly, “low solubility in water” indicates water insolubility. In addition, from the viewpoint of volatility and coatability, the boiling point of the solvent is preferably 90 ° C to 200 ° C.
The low solubility in the immersion liquid means that, for example, the solubility in water, the resist upper layer film-forming composition is applied onto a silicon wafer, dried and formed into a pure water after forming a film. It means that the decreasing rate of the film thickness after dipping for 10 minutes at 23 ° C. and drying is within 3% of the initial film thickness (typically 50 nm).
In the present invention, from the viewpoint of uniformly applying the resist upper layer film, the solid content concentration of the resist upper layer film forming composition is preferably 0.01 to 20% by mass, more preferably 0.1 to 15% by mass, and most preferably. Uses a solvent so that it may become 1-10 mass%. In the composition for forming a resist upper layer film satisfying such a solid content concentration range, the effects of the present invention can be reliably obtained when the total metal content is 25 ppb or less as described above.

  The solvent that can be used is preferably a solvent that dissolves the polymer (A) and does not dissolve the resist film, as described above. For example, alcohol solvents, ether solvents, ester solvents, fluorine solvents And hydrocarbon solvents are preferable, and it is more preferable to use a non-fluorinated alcohol solvent. Thereby, the insolubility with respect to the resist film is further improved, and when the composition for forming a resist upper layer film is applied onto the resist film, the top coat can be formed more uniformly without dissolving the resist film. The viscosity of the solvent is preferably 5 cP (centipoise) or less, more preferably 3 cP or less, still more preferably 2 cP or less, and particularly preferably 1 cP or less. The centipoise to Pascal second can be converted by the following formula: 1000 cP = 1 Pa · s.

The alcohol solvent is preferably a monohydric alcohol, more preferably a monohydric alcohol having 4 to 8 carbon atoms, from the viewpoint of applicability. As the monohydric alcohol having 4 to 8 carbon atoms, a linear, branched or cyclic alcohol can be used, but a linear or branched alcohol is preferable. Examples of such alcohol solvents include those described in paragraph [0052] of International Publication No. 2016/136596.
Examples of the ether solvent include dioxane, tetrahydrofuran, isoamyl ether and the like in addition to the glycol ether solvent. Among ether solvents, ether solvents having a branched structure are preferable.
Examples of the ester solvent include those described in paragraph [0052] of International Publication No. 2016/136596. Of the ester solvents, ester solvents having a branched structure are preferable.

Examples of the fluorine-based solvent include those described in paragraph [0053] of International Publication No. 2016/136596. Among these, a fluorinated alcohol or a fluorinated hydrocarbon solvent can be preferably used.
Examples of the hydrocarbon solvent include those described in paragraph [0053] of International Publication No. 2016/136596.

These solvents may be used alone or in combination.
When a solvent other than the above is mixed, the mixing ratio is usually 0 to 30% by mass, preferably 0 to 20% by mass, more preferably 0 to 10%, based on the total amount of the solvent in the resist upper layer film-forming composition. % By mass. By mixing a solvent other than the above, the solubility in the resist film, the solubility of the polymer in the resist upper layer film-forming composition, the elution characteristics from the resist film, and the like can be appropriately adjusted.

  The composition for forming a resist upper layer film of the present invention is preferably subjected to filter filtration by dissolving the above-described components in a solvent. The filter is preferably made of polytetrafluoroethylene, polyethylene, or nylon having a pore size of 0.1 μm or less, more preferably 0.05 μm or less, and still more preferably 0.03 μm or less. Note that a plurality of types of filters may be connected in series or in parallel. Moreover, the composition may be filtered a plurality of times, and the step of filtering a plurality of times may be a circulating filtration step. Furthermore, you may perform a deaeration process etc. with respect to a composition before and after filter filtration.

As described above, the composition for forming a resist upper layer film containing the polymer (P) of the present invention has a total metal content of 25 ppb or less, preferably 15 ppb or less, and preferably 10 ppb or less. More preferably, it is more preferably 5 ppb or less, and it is further more preferable that it is not substantially contained (below the detection limit of the measuring device).
The total metal content is typically 0.1 ppb or more.

  The metal content is measured by inductively coupled plasma mass spectrometry (ICP-MS). Specifically, an inductively coupled plasma (ICP) mass spectrometer manufactured by Perkin Elmer “ It can be measured using “NexION 2000”.

The metal content is typically Na atom, K atom, Mg atom, Al atom, Ca atom, Cr atom, Mn atom, Fe atom, Ni atom, Cu atom, Zn atom, Pb atom, Sn atom, It is the sum total of the content in each of Co atom, Li atom, Ti atom, Ag atom, W atom, V atom, Ba atom, Au atom, As atom, Cd atom, Mo atom, and Zr atom.
Here, Na atom, K atom, Mg atom, Al atom, Ca atom, Cr atom, Mn atom, Fe atom, Ni atom, Cu atom, Zn atom, Pb atom, Sn atom, Co atom, Li atom, Ti atom , Ag atom, W atom, V atom, Ba atom, Au atom, As atom, Cd atom, Mo atom, and Zr atom are each preferably 1 ppb or less.

<Pattern formation method>
The pattern forming method of the present invention includes a step of forming an upper layer film on the resist film by the above-described composition for forming an upper layer film of the present invention, a step of exposing the resist film, and developing the exposed resist film It is a pattern formation method which has the process to do.
The pattern forming method of the present invention may be a negative pattern forming method or a positive pattern forming method.

The resist film is preferably formed by step a in which a resist composition is applied on a substrate to form a resist film.
The step of forming the upper layer film on the resist film with the composition for forming an upper layer film according to the present invention is performed by applying the composition for forming an upper layer film on the resist film to the upper layer on the resist film. The step b of forming a film is preferable.
The step of exposing the resist film will be described later as step c of exposing the resist film having the upper layer film formed thereon.
The step of developing the exposed resist film is preferably a step d of developing the exposed resist film using a developer to form a pattern.

<Step a>
In step a, a resist composition is applied on a substrate to form a resist film. A coating method is not particularly limited, and a conventionally known spin coating method, spray method, roller coating method, dipping method, or the like can be used, and a spin coating method is preferable.
After applying the resist composition, the substrate may be heated (pre-baked) as necessary. Thereby, the film | membrane from which the insoluble residual solvent was removed can be formed uniformly. Although the temperature of prebaking is not specifically limited, 50 to 160 degreeC is preferable, More preferably, it is 60 to 140 degreeC.
The thickness of the resist film is preferably 20 to 200 nm, and more preferably 30 to 100 nm.

The substrate on which the resist film is formed is not particularly limited, such as silicon, SiN, inorganic substrates such as SiO ₂ and SiN, coated inorganic substrates such as SOG, semiconductor manufacturing processes such as IC, liquid crystal, thermal head, etc. A substrate generally used in the circuit board manufacturing process, and also in the lithography process of other photo applications can be used.

Before forming the resist film, an antireflection film may be coated on the substrate in advance.
As the antireflection film, any of an inorganic film type such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon, and amorphous silicon, and an organic film type made of a light absorber and a polymer material can be used. In addition, as an organic antireflection film, ARC series such as DUV30 series manufactured by Brewer Science, DUV-40 series, AR-2, AR-3, AR-5 manufactured by Shipley, ARC29A manufactured by Nissan Chemical Co., etc. Commercially available organic antireflection films can also be used.

<Process b>
In step b, an upper layer film-forming composition (topcoat composition) is applied on the resist film formed in step a, and then heated (pre-baked (PB)) as necessary. An upper film (hereinafter also referred to as “top coat”) is formed on the film. Thereby, as described above, in the resist pattern after development, a trench pattern or a hole pattern having an ultrafine width or hole diameter (for example, 60 nm or less) can be formed with high DOF performance.
For the reason that the effect of the present invention is more excellent, the pre-baking temperature in the step b (hereinafter also referred to as “PB temperature”) is preferably 100 ° C. or higher, more preferably 105 ° C. or higher, further preferably 110 ° C. or higher, 120 C. or higher is particularly preferable, and a temperature exceeding 120 ° C. is most preferable.
Although the upper limit of PB temperature is not specifically limited, For example, 200 degrees C or less is mentioned, 170 degrees C or less is preferable, 160 degrees C or less is more preferable, 150 degrees C or less is still more preferable.

When the exposure in step c described later is immersion exposure, the top coat is disposed between the resist film and the immersion liquid and functions as a layer that does not directly contact the resist film with the immersion liquid. In this case, it is preferable that the top coat (top coat composition) has properties such as suitability for application to a resist film, transparency to radiation, particularly 193 nm, and poor solubility in an immersion liquid (preferably water). Further, it is preferable that the top coat is not mixed with the resist film and can be uniformly applied to the surface of the resist film.
In addition, in order to apply | coat a topcoat composition uniformly on the surface of a resist film, without melt | dissolving a resist film, it is preferable that a topcoat composition contains the solvent which does not melt | dissolve a resist film. As the solvent that does not dissolve the resist film, it is more preferable to use a solvent having a component different from the organic developer described later. A method for applying the top coat composition is not particularly limited, and a conventionally known spin coat method, spray method, roller coat method, dipping method, or the like can be used.
The details of the top coat composition are as described above.

The thickness of the top coat is not particularly limited, but is usually 5 nm to 300 nm, preferably 10 nm to 300 nm, more preferably 20 nm to 200 nm, and still more preferably 30 nm to 100 nm, from the viewpoint of transparency to the exposure light source. .
After forming the top coat, the substrate is heated as necessary.
The refractive index of the top coat is preferably close to the refractive index of the resist film from the viewpoint of resolution.
The top coat is preferably insoluble in the immersion liquid, and more preferably insoluble in water.
The receding contact angle of the top coat is preferably 50 to 100 degrees, and preferably 80 to 100 degrees, from the viewpoint of immersion liquid followability. More preferred.
In immersion exposure, the immersion head needs to move on the wafer following the movement of the exposure head to scan the wafer at high speed and form an exposure pattern. In order to obtain better resist performance, it is preferable to have a receding contact angle in the above range.

  When peeling the top coat, an organic developer described later may be used, or a separate release agent may be used. As the release agent, a solvent having a small penetration into the resist film is preferable. From the viewpoint that the top coat can be peeled off simultaneously with the development of the resist film, the top coat is preferably peelable by an organic developer. The organic developer used for the stripping is not particularly limited as long as it can dissolve and remove the low-exposed portion of the resist film, and will be described later ketone solvents, ester solvents, alcohol solvents, amide solvents, ether solvents. Developers containing polar solvents and hydrocarbon solvents such as ketone solvents, ester solvents, alcohol solvents, ether solvents are preferred, and developers containing ester solvents are more preferred. A developer containing butyl acetate is more preferred.

From the viewpoint of peeling with an organic developer, the topcoat preferably has a dissolution rate in the organic developer of 1 to 300 nm / sec, more preferably 10 to 100 nm / sec.
Here, the dissolution rate of the top coat in the organic developer is a film thickness reduction rate when the top coat is formed and then exposed to the developer. In the present invention, the top coat is immersed in a butyl acetate solution at 23 ° C. Speed.
By setting the dissolution rate of the top coat in the organic developer to 1 nm / sec or more, preferably 10 nm / sec or more, there is an effect of reducing development defects after developing the resist film. In addition, by setting it to 300 nm / sec or less, preferably 100 nm / sec or less, the line edge roughness of the pattern after developing the resist film becomes better, possibly due to the effect of reducing the exposure unevenness during immersion exposure. There is an effect.
The top coat may be removed using another known developer, for example, an alkaline aqueous solution. Specific examples of the aqueous alkali solution that can be used include an aqueous solution of tetramethylammonium hydroxide.

<Process c>
The exposure in step c can be performed by a generally known method. For example, the resist film on which the top coat is formed is irradiated with actinic rays or radiation through a predetermined mask. At this time, preferably, the actinic ray or radiation is irradiated through the immersion liquid, but is not limited thereto. Although an exposure amount can be set suitably, it is 1-100 mJ / cm < ² > normally.
The wavelength of the light source used in the exposure apparatus of the present invention is not particularly limited, but it is preferable to use light having a wavelength of 250 nm or less. Examples thereof include KrF excimer laser light (248 nm) and ArF excimer laser light (193 nm). F ₂ excimer laser light (157 nm), EUV light (13.5 nm), electron beam, and the like. Among these, it is preferable to use ArF excimer laser light (193 nm).

When immersion exposure is performed, the surface of the film may be washed with an aqueous chemical solution before exposure and / or after exposure and before heating described later.
The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of ArF excimer laser light (wavelength: 193 nm), it is preferable to use water from the viewpoints of availability and ease of handling in addition to the above-mentioned viewpoints.
When water is used, an additive (liquid) that reduces the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the substrate and can ignore the influence on the optical coating on the lower surface of the lens element. As water to be used, distilled water is preferable. Further, pure water filtered through an ion exchange filter or the like may be used. Thereby, distortion of the optical image projected on the resist film due to mixing of impurities can be suppressed.
Further, a medium having a refractive index of 1.5 or more can be used in that the refractive index can be further improved. This medium may be an aqueous solution or an organic solvent.

  The pattern formation method of this invention may have the process c (exposure process) in multiple times. In this case, the same light source or different light sources may be used for the multiple exposures, but ArF excimer laser light (wavelength: 193 nm) is preferably used for the first exposure.

After exposure, preferably, heating (also referred to as baking or PEB) is performed and development (preferably further rinsing) is performed. Thereby, a good pattern can be obtained. The temperature of PEB is not particularly limited as long as a good resist pattern can be obtained.
0 ° C. PEB may be performed once or multiple times.

<Process d>
The developer used in step d may be an alkali developer or a developer containing an organic solvent. You may combine the image development process by an alkali developing solution, and the image development process by the developing solution containing the organic solvent.
As the alkaline developer, a quaternary ammonium salt typified by tetramethylammonium hydroxide is usually used. In addition, an alkaline aqueous solution such as an inorganic alkali, a primary to tertiary amine, an alcohol amine, or a cyclic amine is also used. Is possible.
Specifically, examples of the alkali developer include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia; first amines such as ethylamine and n-propylamine. Secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; tetramethylammonium hydroxide and tetraethylammoniumhydroxy Alkaline aqueous solutions such as quaternary ammonium salts such as pyrrole; cyclic amines such as pyrrole and piperidine; and the like can be used. Among these, it is preferable to use an aqueous solution of tetraethylammonium hydroxide.
Furthermore, an appropriate amount of alcohol or surfactant may be added to the alkaline developer. The alkali concentration of the alkali developer is usually from 0.1 to 20% by mass. The pH of the alkali developer is usually from 10.0 to 15.0.
The time for developing with an alkali developer is usually 10 to 300 seconds.
The alkali concentration (and pH) and development time of the alkali developer can be appropriately adjusted according to the pattern to be formed.
You may wash | clean using a rinse solution after image development using an alkali developing solution. As the rinse solution, pure water can be used and an appropriate amount of a surfactant can be added.
Further, after the development process or the rinsing process, a process of removing the developer or the rinsing liquid adhering to the pattern with a supercritical fluid can be performed.
Further, after the rinsing process or the supercritical fluid process, a heat treatment can be performed to remove moisture remaining in the pattern.

Developers containing organic solvents (hereinafter also referred to as organic developers) include polar solvents such as ketone solvents, ester solvents, alcohol solvents, amide solvents, ether solvents, and hydrocarbon solvents. Developing solution.
Examples of the ketone solvent include those described in paragraph [0276] of International Publication No. 2016/136596.
Examples of the ester solvent include those described in paragraph [0276] of International Publication No. 2016/136596.
Examples of the alcohol solvent include those described in paragraph [0276] of International Publication No. 2016/136596.
Examples of the ether solvent include dioxane, tetrahydrofuran and the like in addition to the glycol ether solvent described in paragraph [0276] of International Publication No. 2016/136596.
Examples of the amide solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidinone and the like. Can be used.
Examples of the hydrocarbon solvent include aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as pentane, hexane, octane and decane;
The aliphatic hydrocarbon solvent that is a hydrocarbon solvent may be a mixture of compounds having the same number of carbon atoms and different structures. For example, when decane is used as the aliphatic hydrocarbon solvent, 2-methylnonane, 2,2-dimethyloctane, 4-ethyloctane, isooctane, etc., which are compounds having the same carbon number and different structures, are aliphatic hydrocarbon solvents. May be included. In addition, the compounds having the same number of carbon atoms and different structures may include only one kind or plural kinds as described above.
A plurality of the above solvents may be mixed, or may be used by mixing with a solvent other than those described above or water. However, in order to fully achieve the effects of the present invention, the water content of the developer as a whole is preferably less than 10% by mass, and more preferably substantially free of moisture.
That is, the amount of the organic solvent used with respect to the organic developer is preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less with respect to the total amount of the developer.

  Among these, the organic developer is preferably a developer containing at least one organic solvent selected from the group consisting of ketone solvents, ester solvents, alcohol solvents, amide solvents and ether solvents. More preferably, a developer containing a ketone solvent or an ester solvent is more preferred, and a developer containing butyl acetate, butyl propionate, or 2-heptanone is more preferred.

The vapor pressure of the organic developer at 20 ° C. is preferably 5 kPa or less, more preferably 3 kPa or less, and even more preferably 2 kPa or less. By setting the vapor pressure of the organic developer to 5 kPa or less, the evaporation of the developer on the substrate or in the developing cup is suppressed, and the temperature uniformity in the wafer surface is improved. As a result, the dimensions in the wafer surface are uniform. Sexuality improves.
Specific examples having a vapor pressure of 5 kPa or less (2 kPa or less) include the solvents described in paragraph [0165] of JP-A No. 2014-71304.

An appropriate amount of a surfactant can be added to the organic developer as required.
The surfactant is not particularly limited, and for example, ionic or nonionic fluorine-based and / or silicon-based surfactants can be used. Examples of these fluorine and / or silicon surfactants include, for example, JP-A No. 62-36663, JP-A No. 61-226746, JP-A No. 61-226745, JP-A No. 62-170950, JP-A-63-334540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, US Pat. No. 5,405,720, The surfactants described in the specifications of US Pat. Preferably, it is a nonionic surfactant. Although it does not specifically limit as a nonionic surfactant, It is still more preferable to use a fluorochemical surfactant or a silicon-type surfactant.
The amount of the surfactant used is usually 0.001 to 5% by mass, preferably 0.005 to 2% by mass, and more preferably 0.01 to 0.5% by mass with respect to the total amount of the developer.
The organic developer may contain a basic compound. Specific examples and preferred examples of the basic compound that can be contained in the organic developer used in the present invention are the same as those described below as the basic compound that can be contained in the resist composition.

  As a development method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle) Method), a method of spraying the developer on the substrate surface (spray method), a method of continuously discharging the developer while scanning the developer discharge nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

  Moreover, you may have the process of stopping image development, substituting with another solvent after the process developed using the developing solution containing an organic solvent.

After the step of developing using a developer containing an organic solvent, a step of washing with a rinse solution may be included.
The rinsing liquid is not particularly limited as long as it does not dissolve the resist pattern, and a solution containing a general organic solvent can be used. The rinsing liquid is, for example, at least selected from the hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents listed above as the organic solvent contained in the organic developer. It is preferable to use a rinse liquid containing one type of organic solvent. More preferably, the cleaning step is performed using a rinse solution containing at least one organic solvent selected from hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, and amide solvents. More preferably, the washing step is performed using a rinsing liquid containing a hydrocarbon solvent, an alcohol solvent or an ester solvent. Particularly preferably, the cleaning step is performed using a rinse solution containing a monohydric alcohol.

  Here, examples of the monohydric alcohol used in the rinsing step include linear, branched, and cyclic monohydric alcohols, and specifically include 1-butanol, 2-butanol, and 3-methyl-1. -Butanol, 3-methyl-2-butanol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-methyl-2-pentanol, 4-methyl-2-pentanol, 1-hexanol, 2- Hexanol, 3-hexanol, 4-methyl-2-hexanol, 5-methyl-2-hexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4-methyl-2-heptanol, 5-methyl-2-heptanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, 4-methyl-2-octanol, 5 Methyl-2-octanol, 6-methyl-2-octanol, 2-nonanol, 4-methyl-2-nonanol, 5-methyl-2-nonanol, 6-methyl-2-nonanol, 7-methyl-2-nonanol, 2-decanol and the like can be used, and preferably 1-hexanol, 2-hexanol, 1-pentanol, 3-methyl-1-butanol, and 4-methyl-2-heptanol.

Examples of the hydrocarbon solvent used in the rinsing step include aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as pentane, hexane, octane, decane (n-decane), and undecane. And the like.
When an ester solvent is used as the rinsing liquid, a glycol ether solvent may be used in addition to the ester solvent (one or more). Specific examples in this case include using an ester solvent (preferably butyl acetate) as a main component and a glycol ether solvent (preferably propylene glycol monomethyl ether (PGME)) as a subcomponent. Thereby, residue defects are suppressed.

A plurality of the above components may be mixed, or may be used by mixing with an organic solvent other than the above.
The water content in the rinse liquid is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. By setting the water content to 10% by mass or less, good development characteristics can be obtained.
The vapor pressure of the rinsing liquid is preferably 0.05 to 5 kPa, more preferably 0.1 to 5 kPa, further preferably 0.12 to 3 kPa at 20 ° C. By setting the vapor pressure of the rinsing liquid to 0.05 to 5 kPa, the temperature uniformity in the wafer surface is improved, and further, the swelling due to the penetration of the rinsing liquid is suppressed, and the dimensional uniformity in the wafer surface is good. Turn into.
An appropriate amount of a surfactant can be added to the rinse solution.

  In the rinsing step, the wafer that has been developed using the developer containing the organic solvent is cleaned using the rinse solution containing the organic solvent. The method of the cleaning treatment is not particularly limited. For example, a method of continuously discharging the rinse liquid onto the substrate rotating at a constant speed (rotary coating method), and immersing the substrate in a bath filled with the rinse liquid for a certain period of time. A method (dip method), a method of spraying a rinsing liquid on the substrate surface (spray method), and the like can be applied. Among them, a cleaning treatment is performed by a spin coating method, and after cleaning, the substrate is rotated at a speed of 2000 rpm to 4000 rpm. It is preferable to rotate and remove the rinse liquid from the substrate. Moreover, it is also preferable to include a heating process (PostBake) after the rinsing process. The developing solution and the rinsing solution remaining between the patterns and inside the patterns are removed by baking. The heating step after the rinsing step is usually 40 to 160 ° C., preferably 70 to 95 ° C., and usually 10 seconds to 3 minutes, preferably 30 seconds to 90 seconds.

  Moreover, the pattern formation method of this invention may have the image development process using an organic type developing solution, and the image development process using an alkali developing solution. A portion with low exposure intensity is removed by development using an organic developer, and a portion with high exposure intensity is also removed by development using an alkali developer. In this way, the multiple development process in which development is performed a plurality of times enables pattern formation without dissolving only the intermediate exposure intensity region, so that a finer pattern than usual can be formed (paragraph of JP 2008-292975 A). [Mechanism similar to [0077]).

Various materials (for example, a resist solvent, a developer, a rinse solution, an antireflection film forming composition, etc.) other than the resist upper layer film forming composition used in the resist composition and the pattern forming method of the present invention are used. It is preferable that impurities such as metals are not included. The content of impurities contained in these materials is preferably 1 ppm or less, more preferably 100 ppt or less, still more preferably 10 ppt or less, and particularly preferably (not more than the detection limit of the measuring device).
Examples of a method for removing impurities such as metals from the various materials include filtration using a filter. The pore size of the filter is preferably 10 nm or less, more preferably 5 nm or less, and still more preferably 3 nm or less. As a material of the filter, a filter made of polytetrafluoroethylene, polyethylene, or nylon is preferable. A filter that has been washed in advance with an organic solvent may be used. In the filter filtration step, a plurality of types of filters may be connected in series or in parallel. When a plurality of types of filters are used, filters having different pore diameters and / or materials may be used in combination. Moreover, various materials may be filtered a plurality of times, and the step of filtering a plurality of times may be a circulating filtration step.
Moreover, as a method for reducing impurities such as metals contained in the various materials, a raw material having a low metal content is selected as a raw material constituting the various materials, and filter filtration is performed on the raw materials constituting the various materials. For example, the inside of the apparatus may be lined with Teflon (registered trademark), and distillation may be performed under a condition in which contamination is suppressed as much as possible. The preferable conditions for filter filtration performed on the raw materials constituting the various materials are the same as those described above.
In addition to filter filtration, impurities may be removed with an adsorbent, or a combination of filter filtration and adsorbent may be used. As the adsorbent, known adsorbents can be used. For example, inorganic adsorbents such as silica gel and zeolite, and organic adsorbents such as activated carbon can be used.

In addition, you may produce the mold for imprint using the resist composition of this invention, For the details, please refer to patent 4109085 and Unexamined-Japanese-Patent No. 2008-162101, for example.
The pattern forming method of the present invention can also be used for guide pattern formation in DSA (Directed Self-Assembly) (see, for example, ACSano Vol. 4 No. 8 Pages 4815-4823).
The resist pattern formed by the above method can be used as a core material (core) of a spacer process disclosed in, for example, Japanese Patent Application Laid-Open Nos. 3-270227 and 2013-164509.
A method for improving the surface roughness of the pattern may be applied to the pattern formed by the method of the present invention. As a method for improving the surface roughness of the pattern, for example, a method of treating a resist pattern with a plasma of a hydrogen-containing gas disclosed in WO2014 / 002808A1 can be mentioned. In addition, JP2004-235468, US2010 / 0020297A, JP2009-19969, Proc. of SPIE Vol. 8328 83280N-1 “EUV Resist Curing Technique for LWR Reduction and Etch Selectivity Enhancement” may be applied.

[4] Resist Composition Next, the resist composition used in the pattern forming method of the present invention will be described.

(A) Resin The resist composition in the present invention may be a negative resist composition or a positive resist composition. Typically, the polarity is increased by the action of an acid, and an organic solvent is removed. It contains a resin whose solubility in the developer is reduced.
Resins whose polarity increases by the action of an acid and whose solubility in a developer containing an organic solvent decreases (hereinafter also referred to as “resin (A)”) are the main chain or side chain of the resin, or the main chain and side chain. Both of these resins have a group (hereinafter also referred to as “acid-decomposable group”) that decomposes by the action of an acid to generate a polar group (hereinafter referred to as “acid-decomposable group”) It is also preferred that
Furthermore, the resin (A) is more preferably a resin having a monocyclic or polycyclic alicyclic hydrocarbon structure (hereinafter also referred to as “alicyclic hydrocarbon-based acid-decomposable resin”). A resin having a monocyclic or polycyclic alicyclic hydrocarbon structure has high hydrophobicity, and it is considered that developability is improved when a region with low light irradiation intensity of a resist film is developed with an organic developer.

  The resist composition of the present invention containing the resin (A) can be suitably used when irradiating ArF excimer laser light.

The polar group in the acid-decomposable group typically includes an acid group, and specifically includes a phenolic hydroxyl group, a carboxylic acid group, a fluorinated alcohol group, a sulfonic acid group, a sulfonamide group, a sulfonylimide group, (Alkylsulfonyl) (alkylcarbonyl) methylene group, (alkylsulfonyl) (alkylcarbonyl) imide group, bis (alkylcarbonyl) methylene group, bis (alkylcarbonyl) imide group, bis (alkylsulfonyl) methylene group, bis (alkylsulfonyl) ) Groups having an imide group, a tris (alkylcarbonyl) methylene group, a tris (alkylsulfonyl) methylene group, and the like.
Preferred polar groups include carboxylic acid groups, fluorinated alcohol groups (preferably hexafluoroisopropanol), sulfonic acid groups and the like.
A preferable group as an acid-decomposable group (acid-decomposable group) is a group obtained by substituting a hydrogen atom of these polar groups with a group capable of leaving with an acid.
As the acid eliminable group, there can be, for _{example, -C (R 36) (R} 37) (R 38), - C (R 36) (R 37) (OR 39), - C (R 01) (R 02 ) (OR ₃₉ ) and the like.
In the formula, R _{36 to} R ₃₉ each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, or an alkenyl group. R ₃₆ and R ₃₇ may be bonded to each other to form a ring.
R _{01 to} R ₀₂ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.
The acid-decomposable group is preferably a cumyl ester group, an enol ester group, an acetal ester group, a tertiary alkyl ester group or the like. More preferably, it is a tertiary alkyl ester group.

  The resin (A) is at least one selected from the group consisting of repeating units having a partial structure represented by the following general formula (pI) to general formula (pV) and repeating units represented by the following general formula (II-AB). It is preferable that it is resin containing.

In general formulas (pI) to (pV),
R ₁₁ represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, or a sec-butyl group, and Z is an atom necessary for forming a cycloalkyl group together with a carbon atom. Represents a group.
R _{12 to} R ₁₆ each independently represents a linear or branched alkyl group or cycloalkyl group having 1 to 4 carbon atoms. However, at least one of R _{12 to} R ₁₄ , or any of R ₁₅ and R ₁₆ represents a cycloalkyl group.
R _{17 to} R ₂₁ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group. However, at least one of R _{17 to} R ₂₁ represents a cycloalkyl group. Further, any one of R ₁₉ and R ₂₁ represents a linear or branched alkyl group or cycloalkyl group having 1 to 4 carbon atoms.
R _{22 to} R ₂₅ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a cycloalkyl group. However, at least one of R _{22 to} R ₂₅ represents a cycloalkyl group. R ₂₃ and R ₂₄ may be bonded to each other to form a ring.

In general formula (II-AB),
R ₁₁ ′ and R ₁₂ ′ each independently represents a hydrogen atom, a cyano group, a halogen atom or an alkyl group.
Z ′ represents an atomic group for forming an alicyclic structure containing two bonded carbon atoms (C—C).

  The general formula (II-AB) is more preferably the following general formula (II-AB1) or general formula (II-AB2).

In the formulas (II-AB1) and (II-AB2),
R ₁₃ ′ to R ₁₆ ′ each independently represents a hydrogen atom, a halogen atom, a cyano group, —COOH, —COOR ₅ , a group that decomposes by the action of an acid, —C (═O) —X—A′—R. ₁₇ ′ represents an alkyl group or a cycloalkyl group. R _{l3'~R 16} may form a ring of at least two members to one of '.
Here, R ₅ represents an alkyl group, a cycloalkyl group, or a group having a lactone structure.
X represents an oxygen atom, a sulfur atom, -NH -, - NHSO ₂ - or an -NHSO ₂ NH-.
A ′ represents a single bond or a divalent linking group.
R ₁₇ ′ represents —COOH, —COOR ₅ , —CN, a hydroxyl group, an alkoxy group, —CO—NH—R ₆ , —CO—NH—SO ₂ —R ₆ or a group having a lactone structure.
R ₆ represents an alkyl group or a cycloalkyl group.
n represents 0 or 1.

In the general formulas (pI) to (pV), the alkyl group in R _{12 to} R ₂₅ represents a linear or branched alkyl group having 1 to 4 carbon atoms.

The cycloalkyl group in R _{11 to} R ₂₅ or the cycloalkyl group formed by Z and the carbon atom may be monocyclic or polycyclic. Specific examples include groups having a monocyclo, bicyclo, tricyclo, tetracyclo structure or the like having 5 or more carbon atoms. The carbon number is preferably 6-30, and particularly preferably 7-25. These cycloalkyl groups may have a substituent.

  Preferred cycloalkyl groups include adamantyl group, noradamantyl group, decalin residue, tricyclodecanyl group, tetracyclododecanyl group, norbornyl group, cedrol group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, A cyclodecanyl group and a cyclododecanyl group can be mentioned. More preferable examples include an adamantyl group, norbornyl group, cyclohexyl group, cyclopentyl group, tetracyclododecanyl group, and tricyclodecanyl group.

  As further substituents of these alkyl groups and cycloalkyl groups, alkyl groups (1 to 4 carbon atoms), halogen atoms, hydroxyl groups, alkoxy groups (1 to 4 carbon atoms), carboxyl groups, alkoxycarbonyl groups (carbon numbers) 2-6). Examples of the substituent that the alkyl group, alkoxy group, alkoxycarbonyl group and the like may further have include a hydroxyl group, a halogen atom, and an alkoxy group.

  The structures represented by the general formulas (pI) to (pV) in the resin can be used for protecting polar groups. Examples of the polar group include various groups known in this technical field.

  Specific examples include a structure in which a hydrogen atom of a carboxylic acid group, a sulfonic acid group, a phenol group, or a thiol group is substituted with a structure represented by the general formulas (pI) to (pV), preferably a carboxylic acid Group, a hydrogen atom of a sulfonic acid group is substituted with a structure represented by general formulas (pI) to (pV).

  As the repeating unit having a polar group protected by the structure represented by the general formulas (pI) to (pV), a repeating unit represented by the following general formula (pA) is preferable.

Here, R represents a hydrogen atom, a halogen atom, or a linear or branched alkyl group having 1 to 4 carbon atoms. A plurality of R may be the same or different.
A is a single bond, an alkylene group, an ether group, a thioether group, a carbonyl group, an ester group, an amide group, a sulfonamide group, a urethane group, or a urea group, or a combination of two or more groups Represents. A single bond is preferable.
Rp ₁ represents any group of the above formulas (pI) to (pV).

  The repeating unit represented by the general formula (pA) is particularly preferably a repeating unit composed of 2-alkyl-2-adamantyl (meth) acrylate and dialkyl (1-adamantyl) methyl (meth) acrylate.

  Specific examples of the repeating unit represented by the general formula (pA) include those described in paragraphs [0313] and [0314] of International Publication No. 2016/136596.

Examples of the halogen atom in the general formula (II-AB), R ₁₁ ′, and R ₁₂ ′ include a chlorine atom, a bromine atom, a fluorine atom, and an iodine atom.

Examples of the alkyl group in R ₁₁ ′ and R ₁₂ ′ include a linear or branched alkyl group having 1 to 10 carbon atoms.

  The atomic group for forming the alicyclic structure of Z ′ is an atomic group that forms a repeating unit of an alicyclic hydrocarbon which may have a substituent in a resin, and among them, a bridged type alicyclic group. An atomic group for forming a bridged alicyclic structure forming a cyclic hydrocarbon repeating unit is preferred.

Examples of the skeleton of the alicyclic hydrocarbon formed include the same alicyclic hydrocarbon groups as R _{12 to} R ₂₅ in the general formulas (pI) to (pV).

The alicyclic hydrocarbon skeleton may have a substituent. Examples of such a substituent include R ₁₃ ′ to R ₁₆ ′ in the general formula (II-AB1) or (II-AB2).

  The resin (A) is preferably a resin having a repeating unit having an acid-decomposable group, and the acid-decomposable group has, for example, a partial structure represented by the above general formula (pI) to general formula (pV). It is contained in at least one type of repeating unit among the repeating unit, the repeating unit represented by formula (II-AB), and the repeating unit of the copolymerization component described below. The acid-decomposable group is preferably contained in a repeating unit having a partial structure represented by general formula (pI) to general formula (pV).

  One type of repeating unit having an acid-decomposable group contained in the resin (A) may be used, or two or more types may be used in combination.

The resin (A) preferably contains a repeating unit having a lactone structure or a sultone (cyclic sulfonate ester) structure.
Any lactone group or sultone group can be used as long as it has a lactone structure or a sultone structure, but it is preferably a 5- to 7-membered lactone structure or a sultone structure, and a 5- to 7-membered lactone A structure in which another ring structure is condensed to form a bicyclo structure or a spiro structure in the structure or sultone structure is preferable. It is more preferable to have a repeating unit having a lactone structure or a sultone structure represented by any of the following general formulas (LC1-1) to (LC1-17), (SL1-1) and (SL1-2). A lactone structure or a sultone structure may be directly bonded to the main chain. Preferred lactone structures or sultone structures are (LC1-1), (LC1-4), (LC1-5), (LC1-8), and more preferably (LC1-4). By using a specific lactone structure or sultone structure, LWR and development defects are improved.

The lactone structure portion or the sultone structure portion may or may not have a substituent (Rb ₂ ). Preferred substituents (Rb ₂ ) include an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 4 to 7 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an alkoxycarbonyl group having 2 to 8 carbon atoms, and a carboxyl group. , Halogen atom, hydroxyl group, cyano group, acid-decomposable group and the like. More preferably, they are a C1-C4 alkyl group, a cyano group, and an acid-decomposable group. n ₂ represents an integer of 0-4. When n ₂ is 2 or more, a plurality of substituents (Rb ₂ ) may be the same or different, and a plurality of substituents (Rb ₂ ) may be bonded to form a ring. .

The resin (A) preferably has a repeating unit containing an organic group having a polar group, particularly a repeating unit having an alicyclic hydrocarbon structure substituted with a polar group. This improves the substrate adhesion and developer compatibility. The alicyclic hydrocarbon structure of the alicyclic hydrocarbon structure substituted with a polar group is preferably an adamantyl group, a diamantyl group, or a norbornane group. The polar group is preferably a hydroxyl group or a cyano group.
As the alicyclic hydrocarbon structure substituted with a polar group, partial structures represented by the following general formulas (VIIa) to (VIId) are preferable.

In general formulas (VIIa) to (VIIc),
R _{2c to} R _4c each independently represents a hydrogen atom, a hydroxyl group, or a cyano group. However, at least one of R _{2c to} R _4c represents a hydroxyl group or a cyano group. Preferably, one or two of R _{2c to} R _4c are a hydroxyl group and the remainder is a hydrogen atom.
In general formula (VIIa), it is more preferable that two of R _{2c to} R _4c are a hydroxyl group and the remaining is a hydrogen atom.

As the repeating unit having a group represented by the general formulas (VIIa) to (VIId), at least one of R ₁₃ ′ to R ₁₆ ′ in the general formula (II-AB1) or (II-AB2) is the above. has a group represented by the general formula (VII) (e.g., represents a _{group R 5} in -COOR ₅ is a represented by the general formula (VIIa) ~ (VIId)) , or the following general formula (AIIa) ~ ( A repeating unit represented by AId) can be mentioned.

In general formulas (AIIa) to (AIId),
R _1c represents a hydrogen atom, a methyl group, a trifluoromethyl group, or a hydroxymethyl group.
R _<2c > -R < _4c > is synonymous with R < _2c > -R < _4c > in general formula (VIIa)-(VIIc).

  Although the specific example of the repeating unit which has a structure represented by general formula (AIIa)-(AIId) is given to the following, this invention is not limited to these.

The weight average molecular weight of the resin (A) is preferably 1,000 to 200,000, more preferably 1,000 to 20,000, and still more preferably 1,000 to 15, as a polystyrene-converted value by the GPC method. 000. By setting the weight average molecular weight to 1,000 to 200,000, deterioration of heat resistance and dry etching resistance can be prevented, and developability is deteriorated, and viscosity is increased and film formability is deteriorated. Can be prevented.
The degree of dispersion (molecular weight distribution) is usually 1 to 5, preferably 1 to 3, more preferably 1.2 to 3.0, particularly preferably 1.2 to 2.0. . The smaller the degree of dispersion, the better the resolution and the resist shape, the smoother the side wall of the resist pattern, and the better the roughness.

The content of the resin (A) is preferably 50 to 99.9% by mass, more preferably 60 to 99.0% by mass, based on the total solid content of the resist composition.
In the present invention, the resin (A) may be used alone or in combination.

  The resin (A), preferably the resist composition of the present invention, preferably contains no fluorine atom and no silicon atom from the viewpoint of compatibility with the topcoat composition.

(B) Compound that generates acid upon irradiation with actinic ray or radiation Typically, the resist composition in the present invention is a compound that generates acid upon irradiation with actinic ray or radiation ("photoacid generator" or "compound (B) ").
The compound (B) may be in the form of a low molecular compound or may be incorporated in a part of the polymer. Moreover, you may use together the form incorporated in a part of polymer and the form of a low molecular compound.
When the compound (B) is in the form of a low molecular compound, the molecular weight is preferably 3000 or less, more preferably 2000 or less, and even more preferably 1000 or less.
When the compound (B) is in a form incorporated in a part of the polymer, it may be incorporated in a part of the acid-decomposable resin described above, or may be incorporated in a resin different from the acid-decomposable resin. .
In the present invention, the compound (B) is preferably in the form of a low molecular compound.
As compound (B), photoinitiator of photocationic polymerization, photoinitiator of radical photopolymerization, photodecoloring agent of dyes, photochromic agent, irradiation of actinic ray or radiation used for micro resist, etc. The known compounds that generate an acid and mixtures thereof can be appropriately selected and used.

  Examples thereof include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.

  Further, a group that generates an acid upon irradiation with these actinic rays or radiation, or a compound in which a compound is introduced into the main chain or side chain of the polymer, for example, US Pat. No. 3,849,137, German Patent No. 3914407. JP, 63-26653, JP, 55-164824, JP, 62-69263, JP, 63-146038, JP, 63-163452, JP, 62-153853, The compounds described in JP-A 63-146029 can be used.

  Furthermore, compounds capable of generating an acid by light described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

The compound (B) is preferably a compound that generates an acid having a cyclic structure when irradiated with actinic rays or radiation. As the cyclic structure, a monocyclic or polycyclic alicyclic group is preferable, and a polycyclic alicyclic group is more preferable. The carbon atom constituting the ring skeleton of the alicyclic group preferably does not contain a carbonyl carbon.
As the compound (B), for example, a compound (specific acid generator) that generates an acid upon irradiation with actinic rays or radiation represented by the following general formula (3) can be preferably exemplified.

(Anion)
In general formula (3),
Xf each independently represents a fluorine atom or an alkyl group substituted with at least one fluorine atom.
R ₄ and R ₅ each independently represent a hydrogen atom, a fluorine atom, an alkyl group, or an alkyl group substituted with at least one fluorine atom, and when there are a plurality of R ₄ and R ₅ , R ₄ and R ₅ are the same But it can be different.
L represents a divalent linking group, and when there are a plurality of L, L may be the same or different.
W represents an organic group containing a cyclic structure.
o represents an integer of 1 to 3. p represents an integer of 0 to 10. q represents an integer of 0 to 10.

Xf represents a fluorine atom or an alkyl group substituted with at least one fluorine atom. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms. The alkyl group substituted with at least one fluorine atom is preferably a perfluoroalkyl group.
Xf is preferably a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms. Xf is more preferably a fluorine atom or CF ₃ . In particular, it is preferable that both Xf are fluorine atoms.

R ₄ and R ₅ each independently represent a hydrogen atom, a fluorine atom, an alkyl group, or an alkyl group substituted with at least one fluorine atom, and when there are a plurality of R ₄ and R ₅ , R ₄ and R ₅ are the same But it can be different.
The alkyl group as R ₄ and R ₅ may have a substituent, and preferably has 1 to 4 carbon atoms. R ₄ and R ₅ are preferably a hydrogen atom.
Specific examples and preferred embodiments of the alkyl group substituted with at least one fluorine atom are the same as the specific examples and preferred embodiments of Xf in formula (3).

L represents a divalent linking group, and when there are a plurality of L, L may be the same or different.
Examples of the divalent linking group include —COO — (— C (═O) —O—), —OCO—, —CONH—, —NHCO—, —CO—, —O—, —S—, — SO—, —SO ₂ —, an alkylene group (preferably having 1 to 6 carbon atoms), a cycloalkylene group (preferably having 3 to 10 carbon atoms), an alkenylene group (preferably having 2 to 6 carbon atoms), or a combination thereof And divalent linking groups. Among them, -COO -, - OCO -, - CONH -, - NHCO -, - CO -, - O -, - SO 2 -, - COO- alkylene group -, - OCO- alkylene group -, - CONH- alkylene group - or -NHCO- alkylene group - are preferred, -COO -, - OCO -, - CONH -, - SO 2 -, - COO- alkylene group - or -OCO- alkylene group - is more preferable.

W represents an organic group containing a cyclic structure. Of these, a cyclic organic group is preferable.
Examples of the cyclic organic group include an alicyclic group, an aryl group, and a heterocyclic group.
The alicyclic group may be monocyclic or polycyclic. Examples of the monocyclic alicyclic group include monocyclic cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Examples of the polycyclic alicyclic group include polycyclic cycloalkyl groups such as a norbornyl group, a tricyclodecanyl group, a tetracyclodecanyl group, a tetracyclododecanyl group, and an adamantyl group. Among them, an alicyclic group having a bulky structure having 7 or more carbon atoms such as a norbornyl group, a tricyclodecanyl group, a tetracyclodecanyl group, a tetracyclododecanyl group, a diamantyl group, and an adamantyl group is formed by PEB (heating after exposure). ) From the viewpoint of suppressing diffusibility in the film and improving MEEF (Mask Error Enhancement Factor).

The aryl group may be monocyclic or polycyclic. Examples of the aryl group include a phenyl group, a naphthyl group, a phenanthryl group, and an anthryl group. Among these, a naphthyl group having a relatively low light absorbance at 193 nm is preferable.
The heterocyclic group may be monocyclic or polycyclic, but the polycyclic group can suppress acid diffusion more. Moreover, the heterocyclic group may have aromaticity or may not have aromaticity. Examples of the heterocyclic ring having aromaticity include a furan ring, a thiophene ring, a benzofuran ring, a benzothiophene ring, a dibenzofuran ring, a dibenzothiophene ring, and a pyridine ring. Examples of the heterocyclic ring that does not have aromaticity include a tetrahydropyran ring, a lactone ring, a sultone ring, and a decahydroisoquinoline ring. As the heterocyclic ring in the heterocyclic group, a furan ring, a thiophene ring, a pyridine ring, or a decahydroisoquinoline ring is particularly preferable. Examples of the lactone ring and sultone ring include the lactone structure and sultone structure exemplified in the aforementioned resin.

  The cyclic organic group may have a substituent. Examples of the substituent include an alkyl group (which may be linear or branched, preferably 1 to 12 carbon atoms), and a cycloalkyl group (monocyclic, polycyclic or spirocyclic). Well, preferably having 3 to 20 carbon atoms), aryl group (preferably having 6 to 14 carbon atoms), hydroxyl group, alkoxy group, ester group, amide group, urethane group, ureido group, thioether group, sulfonamide group, and sulfonic acid An ester group is mentioned. The carbon constituting the cyclic organic group (carbon contributing to ring formation) may be a carbonyl carbon.

o represents an integer of 1 to 3. p represents an integer of 0 to 10. q represents an integer of 0 to 10.
In one embodiment, o in the general formula (3) is an integer of 1 to 3, p is an integer of 1 to 10, and q is preferably 0. Xf is preferably a fluorine atom, R ₄ and R ₅ are preferably both hydrogen atoms, and W is preferably a polycyclic hydrocarbon group. o is more preferably 1 or 2, and still more preferably 1. p is more preferably an integer of 1 to 3, further preferably 1 or 2, and particularly preferably 1. W is more preferably a polycyclic cycloalkyl group, and further preferably an adamantyl group or a diamantyl group.

(Cation)
In the general formula (3), X ⁺ represents a cation.
X ⁺ is not particularly limited as long as it is a cation, but a preferable embodiment includes, for example, a cation (part other than Z ⁻ ) in the general formula (ZI) described later.

(Preferred embodiment)
As a suitable aspect of a specific acid generator, the compound represented by the following general formula (ZI) is mentioned, for example.

In the general formula (ZI),
R ₂₀₁ , R ₂₀₂ and R ₂₀₃ each independently represents an organic group.
The carbon number of the organic group as R ₂₀₁ , R ₂₀₂ and R ₂₀₃ is generally 1 to 30, preferably 1 to 20.
Two of R _{201 to} R ₂₀₃ may be bonded to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. Examples of the group formed by combining two of R _{201 to} R ₂₀₃ include an alkylene group (eg, butylene group, pentylene group).
Z ⁻ represents an anion in the general formula (3), and specifically represents the following anion.

In addition, the compound which has two or more structures represented by general formula (ZI) may be sufficient. For example, at least one of R _{201 to} R ₂₀₃ of the compound represented by the general formula (ZI) is a single bond or at least one of R _{201 to} R ₂₀₃ of another compound represented by the general formula (ZI) It may be a compound having a structure bonded through a linking group.
A compound (B) can be used individually by 1 type or in combination of 2 or more types.
The content of the compound (B) in the composition (when there are a plurality of types) is preferably 0.1 to 30% by mass, more preferably 0.5 to 0.5% based on the total solid content of the composition. 25 mass%, More preferably, it is 3-20 mass%, Most preferably, it is 3-15 mass%.

(C) Solvent The resist composition usually contains a solvent (C).
Examples of the solvent (C) include alkylene glycol monoalkyl ether carboxylate, alkylene glycol monoalkyl ether, alkyl lactate ester, alkyl alkoxypropionate, cyclic lactone (preferably having 4 to 10 carbon atoms), and a ring. Examples thereof include organic solvents such as good monoketone compounds (preferably having 4 to 10 carbon atoms), alkylene carbonates, alkyl alkoxyacetates, and alkyl pyruvates.
Specific examples of these solvents include those described in US Patent Application Publication No. 2008/0187860 [0441] to [0455].

In the present invention, a mixed solvent obtained by mixing a solvent containing a hydroxyl group in the structure and a solvent not containing a hydroxyl group may be used as the organic solvent.
As the solvent containing a hydroxyl group and the solvent not containing a hydroxyl group, the above-mentioned exemplary compounds can be appropriately selected. As the solvent containing a hydroxyl group, alkylene glycol monoalkyl ether, alkyl lactate or the like is preferable, and propylene glycol monomethyl Ether (PGME, also known as 1-methoxy-2-propanol), methyl 2-hydroxyisobutyrate, or ethyl lactate is more preferable. As the solvent not containing a hydroxyl group, an alkylene glycol monoalkyl ether acetate, an alkyl alkoxypropionate, a monoketone compound which may contain a ring, a cyclic lactone, an alkyl acetate or the like is preferable, and among these, propylene glycol monomethyl Ether acetate (PGMEA, also known as 1-methoxy-2-acetoxypropane), ethyl ethoxypropionate, 2-heptanone, γ-butyrolactone, cyclohexanone, or butyl acetate is more preferable, propylene glycol monomethyl ether acetate, γ-butyrolactone, ethyl More preferred is ethoxypropionate or 2-heptanone.
The mixing ratio (mass ratio) of the solvent containing a hydroxyl group and the solvent not containing a hydroxyl group is 1/99 to 99/1, preferably 10/90 to 90/10, more preferably 20/80 to 60/40. is there. A mixed solvent containing 50% by mass or more of a solvent not containing a hydroxyl group is particularly preferred from the viewpoint of coating uniformity.
The solvent preferably contains propylene glycol monomethyl ether acetate, and is preferably a propylene glycol monomethyl ether acetate single solvent or a mixed solvent of two or more containing propylene glycol monomethyl ether acetate.

(D) Hydrophobic resin The resist composition in the present invention may contain (D) a hydrophobic resin. As the hydrophobic resin, the aforementioned polymer (P) described in the resist upper film forming composition can be preferably used. The hydrophobic resin is preferably solid at room temperature (25 ° C.). Furthermore, the glass transition temperature (Tg) is preferably 50 to 250 ° C, more preferably 70 to 250 ° C, still more preferably 80 to 250 ° C, particularly preferably 90 to 250 ° C, and most preferably 100 to 250 ° C. The hydrophobic resin preferably has a repeating unit having a monocyclic or polycyclic cycloalkyl group. The monocyclic or polycyclic cycloalkyl group may be contained in either the main chain or the side chain of the repeating unit.

The weight average molecular weight of the hydrophobic resin (D) in terms of standard polystyrene is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, and still more preferably 2,000 to 15,000. is there.
The hydrophobic resin (D) may be used alone or in combination.
Content in the composition of hydrophobic resin (D) is generally 0.01-30 mass% with respect to the total solid in the resist composition of this invention, 0.01-10 mass% Is preferable, 0.05-8 mass% is more preferable, 0.1-7 mass% is still more preferable.

(E) Basic compound The resist composition in the present invention preferably contains (E) a basic compound in order to reduce a change in performance over time from exposure to heating.
Preferred examples of the basic compound include compounds having structures represented by the following formulas (A) to (E).

In general formulas (A) to (E),
R ²⁰⁰ , R ²⁰¹ and R ²⁰² may be the same or different and are a hydrogen atom, an alkyl group (preferably having 1 to 20 carbon atoms), a cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group (having a carbon number). 6-20), wherein R ²⁰¹ and R ²⁰² may combine with each other to form a ring.

About the said alkyl group, as an alkyl group which has a substituent, a C1-C20 aminoalkyl group, a C1-C20 hydroxyalkyl group, or a C1-C20 cyanoalkyl group is preferable.
R ²⁰³ , R ²⁰⁴ , R ²⁰⁵ and R ²⁰⁶ may be the same or different and each represents an alkyl group having 1 to 20 carbon atoms.
The alkyl groups in these general formulas (A) to (E) are more preferably unsubstituted.

  Preferred compounds include guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine, piperidine and the like, and more preferred compounds include imidazole structure, diazabicyclo structure, onium hydroxide structure, onium carboxylate Examples thereof include a compound having a structure, a trialkylamine structure, an aniline structure or a pyridine structure, an alkylamine derivative having a hydroxyl group and / or an ether bond, and an aniline derivative having a hydroxyl group and / or an ether bond.

  Examples of the compound having an imidazole structure include imidazole, 2,4,5-triphenylimidazole, and benzimidazole. Examples of the compound having a diazabicyclo structure include 1,4-diazabicyclo [2,2,2] octane, 1,5-diazabicyclo [4,3,0] non-5-ene, and 1,8-diazabicyclo [5,4,0. ] Undec-7-ene etc. are mentioned. Examples of the compound having an onium hydroxide structure include triarylsulfonium hydroxide, phenacylsulfonium hydroxide, sulfonium hydroxide having a 2-oxoalkyl group, specifically triphenylsulfonium hydroxide, tris (t-butylphenyl) sulfonium. Examples thereof include hydroxide, bis (t-butylphenyl) iodonium hydroxide, phenacylthiophenium hydroxide, and 2-oxopropylthiophenium hydroxide. As the compound having an onium carboxylate structure, an anion portion of the compound having an onium hydroxide structure is converted to a carboxylate, and examples thereof include acetate, adamantane-1-carboxylate, and perfluoroalkylcarboxylate. Examples of the compound having a trialkylamine structure include tri (n-butyl) amine and tri (n-octyl) amine. Examples of the aniline compound include 2,6-diisopropylaniline, N, N-dimethylaniline, N, N-dibutylaniline, N, N-dihexylaniline and the like. Examples of the alkylamine derivative having a hydroxyl group and / or an ether bond include ethanolamine, diethanolamine, triethanolamine, and tris (methoxyethoxyethyl) amine. Examples of aniline derivatives having a hydroxyl group and / or an ether bond include N, N-bis (hydroxyethyl) aniline.

  Moreover, as a basic compound, what is described as a basic compound which the composition for upper-layer film formation (topcoat composition) mentioned above may contain can be used suitably.

These basic compounds are used alone or in combination of two or more.
The usage-amount of a basic compound is 0.001-10 mass% normally on the basis of solid content of the resist composition of this invention, Preferably it is 0.01-5 mass%.

  The use ratio of the photoacid generator and the basic compound in the resist composition is preferably photoacid generator / basic compound (molar ratio) = 2.5 to 300. That is, the molar ratio is preferably 2.5 or more from the viewpoints of sensitivity and resolution, and is preferably 300 or less from the viewpoint of suppressing the reduction in resolution due to the thickening of the resist pattern over time until post-exposure heat treatment. The photoacid generator / basic compound (molar ratio) is more preferably 5.0 to 200, and still more preferably 7.0 to 150.

(F) Surfactant The resist composition in the present invention preferably further contains (F) a surfactant, and is a fluorine-based and / or silicon-based surfactant (fluorine-based surfactant, silicon-based surfactant). , A surfactant having both a fluorine atom and a silicon atom), or more preferably two or more.

When the resist composition of the present invention contains the surfactant (F), when using an exposure light source of 250 nm or less, particularly 220 nm or less, a resist pattern with good sensitivity and resolution and less adhesion and development defects can be obtained. It becomes possible to give.
Examples of the fluorine-based and / or silicon-based surfactant include, for example, JP-A No. 62-36663, JP-A No. 61-226746, JP-A No. 61-226745, JP-A No. 62-170950, JP 63-34540 A, JP 7-230165 A, JP 8-62834 A, JP 9-54432 A, JP 9-5988 A, JP 2002-277862 A, US Patent Nos. 5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511, 5,824,451 Surfactant can be mentioned, The following commercially available surfactant can also be used as it is.

  These surfactants may be used alone or in several combinations.

  (F) The usage-amount of surfactant becomes like this. Preferably it is 0.01-10 mass% with respect to resist composition whole quantity (except a solvent), More preferably, it is 0.1-5 mass%.

(G) Carboxylic acid onium salt The resist composition in the present invention may contain (G) a carboxylic acid onium salt. Examples of the carboxylic acid onium salt include a carboxylic acid sulfonium salt, a carboxylic acid iodonium salt, and a carboxylic acid ammonium salt. In particular, the (G) carboxylic acid onium salt is preferably an iodonium salt or a sulfonium salt. Furthermore, it is preferable that the carboxylate residue of (G) carboxylic acid onium salt does not contain an aromatic group and a carbon-carbon double bond. As a particularly preferable anion moiety, a linear, branched, monocyclic or polycyclic alkylcarboxylic acid anion having 1 to 30 carbon atoms is preferable. More preferably, an anion of a carboxylic acid in which some or all of these alkyl groups are fluorine-substituted is preferable. The alkyl chain may contain an oxygen atom. This ensures transparency with respect to light of 220 nm or less, improves sensitivity and resolution, and improves density dependency and exposure margin.

  Fluoro-substituted carboxylic acid anions include fluoroacetic acid, difluoroacetic acid, trifluoroacetic acid, pentafluoropropionic acid, heptafluorobutyric acid, nonafluoropentanoic acid, perfluorododecanoic acid, perfluorotridecanoic acid, perfluorocyclohexanecarboxylic acid, 2 , 2-bistrifluoromethylpropionic acid anion and the like.

  These (G) carboxylic acid onium salts can be synthesized by reacting sulfonium hydroxide, iodonium hydroxide, ammonium hydroxide and carboxylic acid with silver oxide in a suitable solvent.

  (G) The content of the carboxylic acid onium salt in the composition is generally 0.1 to 20% by mass, preferably 0.5 to 10% by mass, more preferably, based on the total solid content of the resist composition. 1 to 7% by mass.

(H) Other additives The resist composition of the present invention further promotes solubility in dyes, plasticizers, photosensitizers, light absorbers, alkali-soluble resins, dissolution inhibitors and developers as necessary. The compound to be made (for example, a phenol compound having a molecular weight of 1000 or less, an alicyclic compound having a carboxyl group, or an aliphatic compound) and the like can be contained.

Such a phenol compound having a molecular weight of 1000 or less can be obtained, for example, by referring to the methods described in JP-A-4-1222938, JP-A-2-28531, US Pat. No. 4,916,210, European Patent 219294, and the like. Can be easily synthesized by those skilled in the art.
Specific examples of alicyclic or aliphatic compounds having a carboxyl group include carboxylic acid derivatives having a steroid structure such as cholic acid, deoxycholic acid, lithocholic acid, adamantane carboxylic acid derivatives, adamantane dicarboxylic acid, cyclohexane carboxylic acid, cyclohexane Examples thereof include, but are not limited to, dicarboxylic acids.

The solid content concentration of the resist composition is usually 1.0 to 10% by mass, preferably 2.0 to 5.7% by mass, and more preferably 2.0 to 5.3% by mass. By setting the solid content concentration within the above range, the resist solution can be uniformly applied on the substrate, and further, a resist pattern having excellent line width roughness can be formed. The reason for this is not clear, but perhaps the solid content concentration is 10% by mass or less, preferably 5.7% by mass or less, which suppresses aggregation of the material in the resist solution, particularly the photoacid generator. As a result, it is considered that a uniform resist film was formed.
The solid content concentration is a weight percentage of the weight of other resist components excluding the solvent with respect to the total weight of the resist composition.

  The resist composition of the present invention is used by dissolving the above components in a predetermined organic solvent, preferably the above mixed solvent, filtering the solution, and then applying the solution on a predetermined support (substrate). The pore size of the filter used for filter filtration is preferably 0.1 μm or less, more preferably 0.05 μm or less, and still more preferably 0.03 μm or less made of polytetrafluoroethylene, polyethylene, or nylon. In filter filtration, for example, as in JP-A-2002-62667, circulation filtration may be performed, or filtration may be performed by connecting a plurality of types of filters in series or in parallel. The composition may be filtered multiple times. Furthermore, you may perform a deaeration process etc. with respect to a composition before and behind filter filtration.

The present invention also relates to an electronic device manufacturing method including the pattern forming method of the present invention described above, and an electronic device manufactured by the manufacturing method.
The electronic device of the present invention is suitably mounted on electrical and electronic equipment (home appliances, OA / media related equipment, optical equipment, communication equipment, and the like).

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not limited by this.

<Synthesis Example 1: Synthesis of polymer (P-5)>
53.4 g of cyclohexanone was heated to 80 ° C. under a nitrogen stream. While stirring this liquid, 47.1 g of a monomer represented by the following structural formula (M-1), 43.3 g of a monomer represented by the following structural formula (M-2), 97.3 g of cyclohexanone, and 2, A mixed solution of 2.7 g of dimethyl 2′-azobisisobutyrate [V-601, manufactured by Wako Pure Chemical Industries, Ltd.] was added dropwise over 6 hours. After completion of dropping, the mixture was further stirred at 80 ° C. for 2 hours. This was processed by the following purification methods (1) and (2) to prepare a 10% by mass 4-methyl-2-pentanol solution of the polymer (P-5).

(1) The reaction solvent was removed from the polymerization reaction solution by distillation under reduced pressure, and 200 g of ethyl acetate and 200 g of 0.1N dilute hydrochloric acid as water containing an acidic compound were added. After stirring and separation, the upper layer was recovered, and 200 g of 0.1N diluted hydrochloric acid was added. After further stirring and separation, the upper layer was recovered and 200 g of water was added. After stirring and separation again, the upper layer was recovered, and the solvent in the polymer solution was replaced with 4-methyl-2-pentanol.
(2) After reprecipitation of the polymer by bringing a large amount of methanol into contact with the polymerization reaction solution, the solvent is removed from the reaction kettle (polymerization apparatus) (not distilled off), and 200 g of ethyl acetate and acidic compound are added. 200 g of 0.1N dilute hydrochloric acid as water to be added was added. After stirring and separation, the upper layer was recovered, and 200 g of 0.1N diluted hydrochloric acid was added. After further stirring and separation, the upper layer was recovered and 200 g of water was added. After stirring and separation again, the upper layer was recovered, and the solvent in the polymer solution was replaced with 4-methyl-2-pentanol.

  Similarly to the polymer (P-5), the polymers (P-1) to (P-4), and (P-6) to (P-8) are converted into the respective (1) and (2). Synthesized via purification method.

  Hereinafter, it shows about the structure of the repeating unit in each polymer, and the molar ratio of a repeating unit. In addition, the weight average molecular weight (Mw) and the dispersity (Mw / Mn) are different depending on which one of the above (1) and (2) is adopted, and are shown for each case.

<Synthesis Example 2: Synthesis of polymer (P'-1)>
268 g of 2-butanone, 160 g of a monomer represented by the following structural formula M-1, and 95.3 g of a monomer represented by the following structural formula M-2 were heated to 75 ° C. under a nitrogen stream. While stirring this solution, a solution prepared by dissolving 12.1 g of dimethyl 2,2-azobis (2-methylpropionate) in 18.3 g of 2-butanone was added dropwise over 5 minutes and aged for 6 hours.
Subsequently, 2-butanone was added to the resulting polymerization reaction solution to dilute to 222 g, and then transferred to a separatory funnel. The separatory funnel was charged with 222 g of methanol and 1,111 g of n-hexane to carry out separation purification. After separation, 168 g of the lower layer liquid was recovered. 168 g of methanol and 842 g of n-hexane were added to the recovered lower layer liquid, and liquid separation purification was performed. After separation, 219 g of the lower layer liquid was recovered. 109 g of 2-butanone and 656 g of n-hexane were added to the recovered lower layer liquid, and liquid separation purification was performed. After separation, 806 g of the upper layer liquid was recovered. The recovered upper layer liquid was replaced with 4-methyl-2-pentanol to obtain 400 g of a solution containing a fluorine atom-containing polymer. Next, the obtained solution was transferred to a separatory funnel, and 400 g of water was added to the separatory funnel, and after separation purification, 440 g of the upper layer liquid was recovered. The recovered upper layer liquid was replaced with 4-methyl-2-pentanol to obtain a solution containing a fluorine atom-containing polymer (P′-1). This purification method is referred to as “(3)” in the following table.

<Synthesis Example 3: Synthesis of polymer (P'-2)>
268 g of cyclohexanone was heated to 80 ° C. under a nitrogen stream. While stirring this liquid, 160 g of a monomer represented by the following structural formula M-1, 95.3 g of a monomer represented by the following structural formula M-2, 498 g of cyclohexanone, and dimethyl 2,2′-azobisisobutyrate [V -601, manufactured by Wako Pure Chemical Industries, Ltd.] was added dropwise over 6 hours. After completion of dropping, the mixture was further stirred at 80 ° C. for 2 hours. The reaction solution was allowed to cool, then reprecipitated with a large amount of methanol and filtered. The resulting wet solid was redissolved in 4-methyl-2-propanol, and the remaining methanol and cyclohexanone were driven off while heating under reduced pressure. Thereafter, the polymer solution was filtered through a polyethylene filter having a pore size of 0.05 μm to prepare 2210 g of a 4-methyl-2-pentanol solution containing 10% by mass of the polymer (P′-1). This purification method is described as “(4)” in the following table.

<Preparation of composition for resist upper layer film formation>
The components shown in the following table are dissolved in the solvent shown below to prepare a solution having a solid content concentration of 2.7% by mass, and this is filtered through a polyethylene filter having a pore size of 0.03 μm to form a composition for forming an upper layer film (1) to (10) were prepared. In the table of Table 1 below, the content (mass%) of the additive (AD) is based on the total solid content of the composition for forming an upper layer film.

  Each abbreviation in the table is as follows.

<Solvent (S)>
S-1: 4-methyl-2-pentanol S-2: 3-penten-2-one S-3: 2-nonanone S-4: decane S-5: 2-nonanone S-6: isoamyl ether S- 7: Isobutyl isobutyrate

<Additive (AD)>

[Examples 1-A to 24-A, Comparative Example 1-A ′ (ArF immersion exposure, positive development with an alkaline developer)]

<Preparation of resist composition>
Each component shown in Table 2 was dissolved in a solvent to prepare a solution having a solid content concentration of 4% by mass, and this was filtered through a polyethylene filter having a pore size of 0.05 μm to prepare a resist composition.

  The resin (A), photoacid generator, basic compound, surfactant and solvent in Table 2 are as follows.

[Resin (A)]
Hereinafter, the structure of the resin (A) is shown below. Table 3 below shows the molar ratio of repeating units in each resin (in order from the left in the structural formula), weight average molecular weight (Mw), and dispersity (Mw / Mn).

  [Photoacid generator]

  [Basic compounds]

[Surfactant]
W-1: Megafac F176 (Dainippon Ink Chemical Co., Ltd., fluorine-based)
W-2: Megafuck R08 (Dainippon Ink Chemical Co., Ltd., fluorine and silicon)
W-3: Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd., silicon-based)
W-4: Troisol S-366 (manufactured by Troy Chemical Co., Ltd.)
W-5: PF656 (manufactured by OMNOVA, fluorine-based)
W-6: PF6320 (manufactured by OMNOVA, fluorine-based)

〔solvent〕
SL-1 ′: cyclohexanone SL-2 ′: propylene glycol monomethyl ether acetate (PGMEA: 1-methoxy-2-acetoxypropane)
SL-3 ′: ethyl lactate SL-4 ′: propylene glycol monomethyl ether (PGME: 1-methoxy-2-propanol)
SL-5 ′: γ-butyrolactone SL-6 ′: propylene carbonate

<Pattern formation>
An organic antireflection film-forming composition ARC29SR (manufactured by Brewer Science) was applied onto a silicon wafer and baked at 205 ° C. for 60 seconds to form an antireflection film having a thickness of 98 nm. A resist composition shown in Table 2 was applied thereon and baked at 100 ° C. for 60 seconds to form a resist film having a thickness of 90 nm. Next, the upper film forming composition shown in Table 1 was applied to the upper layer of the resist film, and baked at 90 ° C. for 60 seconds to form a resist upper film having a thickness of 100 nm.
Using a ArF excimer laser immersion scanner (manufactured by ASML; XT1700i, NA1.20, C-Quad, outer sigma 0.730, inner sigma 0.630, XY deflection) on the resist film, the line width is 75 nm. Exposure was through a 6% halftone mask with a 1: 1 line and space pattern. As the immersion liquid, ultrapure water was used.
The resist film after exposure was baked at 120 ° C. for 60 seconds, developed with an aqueous tetramethylammonium hydroxide solution (2.38 mass%) for 30 seconds, and then rinsed with pure water for 30 seconds. Thereafter, this was spin-dried to obtain a positive resist pattern.

<Evaluation of resist pattern>
Using a scanning electron microscope (S-9220, manufactured by Hitachi, Ltd.), the obtained resist pattern was subjected to the following methods in the following manner: metal content, post-etching defects, post-etching line width roughness (Line Width Roughness; LWR). ) Was evaluated based on the following method. The results are shown in Table 4 below.

[Metal content]
Each composition for forming an upper layer film was diluted with N-methylpyrrolidone (NMP) so that the total solid content concentration was 0.27% by mass, and an ICP-mass spectrometer (“NexION” manufactured by PerkinElmer) was used. 2000 ”), the metals (Na atom, K atom, Mg atom, Al atom, Ca atom, Cr atom, Mn atom, Fe atom, Ni atom, Cu atom, Zn atom, Pb atom contained in each composition) , Sn atom, Co atom, Li atom, Ti atom, Ag atom, W atom, V atom, Ba atom, Au atom, As atom, Cd atom, Mo atom, Zr atom). The total content of the metal was calculated from the measured value of each content.

[Defect after etching]
Using the pattern formed as described above as a processing mask, a silicon wafer is dry-etched for 60 seconds using Ar / C ₄ F ₆ / O ₂ gas (mixed gas with a volume ratio of 100/4/2) with HITACHI U-621 Processed. After performing the dry etching process, a defect inspection apparatus KLA2360 (trade name) manufactured by KLA-Tencor is used for the obtained pattern, and the pixel size of the defect inspection apparatus is set to 0.16 μm. The threshold was set to 20, the measurement was performed in a random mode, the defects extracted from the difference caused by the overlap of the comparison image and the pixel unit were detected, and the number of defects per unit area (pieces / cm ² ) was calculated. . A value of less than 0.3 was designated as A, 0.3 or more and less than 0.8 as B, and 0.8 or more as C. A smaller value indicates better performance.

[LWR after etching]
Using the pattern formed as described above as a processing mask, a silicon wafer is dry-etched for 60 seconds using Ar / C ₄ F ₆ / O ₂ gas (mixed gas with a volume ratio of 100/4/2) with HITACHI U-621 Processed. After performing dry etching treatment, when the pattern obtained is observed from above the pattern using a length measurement scanning electron microscope (SEM (Hitachi, Ltd. S-9380II)), the line width can be arbitrarily set. When the roughness was observed at a point, the sample with little roughness was classified as A, the sample with slight roughness as B, and the sample with large roughness as C.

  The example using the composition for forming a resist upper layer film whose metal content satisfies the range specified in the present invention was found to be superior in post-etching LWR and post-etching defects compared to a comparative example not satisfying this. It was. That is, when a lower layer (silicon wafer in the above embodiment) is etched using a fine resist pattern as a processing mask, the lower layer pattern (silicon wafer pattern in the above embodiment) has few defects and excellent roughness performance. It was found that can be formed.

[Examples 1-B to 24-B, Comparative Example 1-B ′ (ArF immersion exposure, negative development by organic solvent development)]

<Preparation of resist composition>
The components shown in Table 5 below are dissolved in the solvent shown in Table 5 below to prepare a solution having a solid content concentration of 3.5% by mass, and this is filtered through a polyethylene filter having a pore size of 0.03 μm. Re-1 to Re-12 were prepared.

  Abbreviations in Table 5 are as follows.

<Resin>
Hereinafter, Table 6 summarizes the composition ratio (molar ratio; corresponding in order from the left), weight average molecular weight (Mw), and dispersity (Mw / Mn) of each repeating unit in the resins (1) ′ to (12) ′. Show.

<Photo acid generator>

<Hydrophobic resin>
As the hydrophobic resin, resins (B-1) to (B-8) shown in Table 7 were used.

<Basic compound>

<Solvent>
SL-1 ": Propylene glycol monomethyl ether acetate (PGMEA)
SL-2 ″: cyclohexanone SL-3 ″: propylene glycol monomethyl ether (PGME)
SL-4 ″: γ-butyrolactone

An organic antireflection film-forming composition ARC29SR (manufactured by Brewer Science) was applied onto a silicon wafer and baked at 205 ° C. for 60 seconds to form an antireflection film having a thickness of 98 nm. A resist composition shown in Table 5 was applied thereon and baked at 100 ° C. for 60 seconds to form a resist film having a thickness of 90 nm. The upper layer film-forming composition described in Table 1 was applied to the upper layer of the resist film, and baked at 90 ° C. for 60 seconds to form a resist upper layer film having a thickness of 100 nm.
Using a ArF excimer laser immersion scanner (manufactured by ASML; XT1700i, NA1.20, C-Quad, outer sigma 0.730, inner sigma 0.630, XY deflection) on the resist film, the line width is 75 nm. Exposure was through a 6% halftone mask with a 1: 1 line and space pattern. As the immersion liquid, ultrapure water was used.
The exposed resist film was baked at 120 ° C. for 60 seconds, developed with an organic developer shown in Table 8 for 30 seconds, and then rinsed with a rinse solution shown in Table 8 for 30 seconds. Thereafter, this was spin-dried to obtain a negative resist pattern.

<Evaluation of resist pattern>
Using a scanning electron microscope (S-9220, manufactured by Hitachi, Ltd.), the obtained resist pattern was evaluated in the following manner for the metal content, post-etch defect, and post-etch LWR based on the above-described methods. did. The results are shown in Table 8 below.

  The example using the composition for forming a resist upper layer film whose metal content satisfies the range specified in the present invention was found to be superior in post-etching LWR and post-etching defects compared to a comparative example not satisfying this. It was. That is, when a lower layer (silicon wafer in the above embodiment) is etched using a fine resist pattern as a processing mask, the lower layer pattern (silicon wafer pattern in the above embodiment) has few defects and excellent roughness performance. It was found that can be formed.

Claims (10)

A resist upper layer film-forming composition comprising a polymer (P) having a repeating unit represented by the following general formula (1), wherein the total metal content is 25 ppb or less.

In the general formula (1), L represents a single bond, —COO—, or —CONR—. R ₀ , R ₅ and R each independently represent a hydrogen atom or a monovalent organic group. The composition for forming a resist upper layer film according to claim 1, wherein the polymer (P) is a polymer having a repeating unit represented by the following general formula (i) or (ii).

In the general formula (i), R ₁ represents a single bond or a divalent linking group. R ₂ and R ₃ each independently represents a monovalent organic group having a fluorine atom. R ₄ represents a hydrogen atom or a base dissociable group. R ₅ represents a monovalent organic group.
In the general formula (ii), Ra represents a monovalent organic group. Rf represents a hydrocarbon group having a fluorine atom.   The composition for forming a resist upper layer film according to claim 1 or 2, wherein a solid content concentration of the composition for forming a resist upper layer film is 0.1 to 15% by mass. A method for producing a polymer, wherein the polymer (P) having a repeating unit represented by the following general formula (1) is purified by liquid-liquid extraction using an organic solvent and water containing an acidic compound. .

In the general formula (1), L represents a single bond, —COO—, or —CONR—. R ₀ , R ₅ and R each independently represent a hydrogen atom or a monovalent organic group. Furthermore, the manufacturing method of the polymer of Claim 4 which performs any of the following liquid separation refinement | purification (1)-(4) with respect to the said polymer (P).
(1) Purification by liquid-liquid extraction using a plurality of organic solvents that can be separated from each other (2) Purification by liquid-liquid extraction using an organic solvent and water (3) Precipitating the polymer (P) in the polymerization apparatus The polymer (P) is dissolved in the organic solvent in the polymerization apparatus and the polymer (P) is obtained in a state dissolved in the organic solvent without obtaining the polymer (P) as powder. (4) After depositing the polymer (P) in the polymerization apparatus, the polymer (P) is dissolved in the organic solvent in the polymerization apparatus, and the polymer (P) dissolved in the organic solvent is further dissolved. A method for obtaining a polymer (P) in a state of being dissolved in an organic solvent without being purified as a powder and obtaining the polymer (P) as a powder. A step of forming a resist upper layer film on the resist film with the resist upper layer film forming composition according to claim 1,
Exposing the resist film; and
A pattern forming method comprising a step of developing the exposed resist film with a developer.   The pattern forming method according to claim 6, wherein the exposure is immersion exposure.   The pattern forming method according to claim 6, wherein the developer is a developer containing an organic solvent.   The pattern forming method according to claim 6, wherein the developer is an alkali developer.   The manufacturing method of an electronic device containing the pattern formation method of any one of Claims 6-9.