JP2009042459A - Resist pattern coating film forming material and resist pattern coating film forming method - Google Patents

Abstract

A resist pattern coating film forming material capable of forming an organic coating film on a resist pattern surface, and a resist pattern coating film forming method using the resist pattern coating film forming material.
A resist pattern coating film forming material for forming a coating film on a resist pattern surface, comprising a water-soluble resin (A1) having a portion which is ionized in an aqueous solution and has a positive charge. A resist pattern coating film-forming material comprising: a first aqueous solution to be formed; and a second aqueous solution containing a water-soluble resin (A2) having a negatively charged portion in the aqueous solution.
[Selection figure] None

Description

  The present invention relates to a resist pattern coating film forming material and a resist pattern coating film forming method for coating a resist pattern surface.

Lithography technology is frequently used to manufacture fine structures in various electronic devices such as semiconductor devices and liquid crystal devices.
In the lithography technique, a photosensitive organic material called a resist is conventionally used. As the resist, a resist whose solubility (alkali solubility) in an alkali developer is changed by irradiation (exposure) of radiation such as light having a short wavelength such as vacuum ultraviolet rays or electron beam is generally used. Such a resist changes its alkali solubility due to, for example, decomposition of a part of the structure or formation of a cross-linkage upon exposure. For this reason, a difference in alkali solubility occurs between the exposed portion and the unexposed portion, whereby a resist pattern can be formed. That is, when selective exposure is performed on a resist film formed using a resist, the alkali solubility of the resist film partially changes. And when this resist film is alkali-developed, a part with high alkali solubility will melt | dissolve and will be removed and a resist pattern will be formed.
There are two types of resists: a positive type in which the alkali solubility in the exposed area increases and a negative type in which the alkali solubility in the exposed area decreases.

In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization has rapidly progressed due to advances in lithography technology. As a means for miniaturization, the wavelength of exposure light is generally shortened. Specifically, conventionally, ultraviolet rays typified by g-line and i-line have been used, but now KrF is used. An excimer laser (248 nm) is introduced, and an ArF excimer laser (193 nm) is further introduced.
As one of resists having high sensitivity to such short-wavelength exposure light sources, it contains an acid generator component that generates acid by the action of radiation and a base material component that changes alkali solubility by the action of the acid. A chemically amplified resist composition is known (see, for example, Patent Documents 1 and 2).
Japanese Patent No. 2881969 JP 2003-241385 A

Currently, with the miniaturization of patterns, there is a tendency to reduce the thickness of the resist film in order to further improve the resolution. However, as the resist film becomes thinner, the etching resistance of the resist pattern formed on the resist film decreases. For this reason, the etching resistance is reduced when the underlying portion (substrate or the like) is etched using the resist pattern as a mask, the shape of the resist pattern is lost, or the resist pattern disappears during the etching, and the underlying portion is removed. This causes a problem that the pattern cannot be transferred accurately. Such a problem is more likely to occur as the resist pattern becomes finer and the pattern density increases.
Further, along with the miniaturization of resist patterns, improvement of line edge roughness (LER) has become an important issue. LER is rough on the surface of the resist pattern side wall and may cause adverse effects on the formation of fine semiconductor elements due to distortion around the hole in the hole pattern and variation in line width in the line and space pattern. There is.

As one means for solving the above problem, it is conceivable to form a film (coating film) on the resist pattern surface and protect the surface.
A material for forming a coating film (resist pattern coating film) used for such applications needs to have high selectivity capable of selectively coating the resist pattern surface. That is, when the selectivity is low, when the resist pattern coating film is formed on the resist pattern surface, the coating film is formed even on the substrate surface where the resist pattern is missing (space part). In addition, it is important that a thin film can be formed as a material for forming the resist pattern coating film. That is, if the thin film cannot be formed, the space portion of the resist pattern may be filled with the material, and such a problem is more likely to occur as the resist pattern becomes finer.
However, to date, there are few known materials that can form a resist pattern coating film that satisfies the above requirements, in particular, an organic resist pattern coating film.
The present invention has been made in view of the above circumstances, and is a resist pattern coating film forming material capable of forming an organic coating film on the resist pattern surface, and a resist using the resist pattern coating film forming material It aims at providing the pattern coating film formation method.

So far, various methods have been proposed as a method for forming an organic thin film, and one of them is an alternate adsorption method. In the alternate adsorption method, a positively charged resin (cationic polymer) and a negatively charged resin (anionic polymer) solution are alternately brought into contact with the material surface to adsorb each resin to the material surface. (See, for example, “21st Century Thin Film Manufacturing Application Handbook”, pages 520 to 524 (NTS Corporation, published on April 22, 2003)). So far, the use of the alternate adsorption method for coating the resist pattern surface has not been studied, and materials suitable for the use have not been studied.
As a result of intensive studies, the present inventors have found that a resist pattern coating film can be effectively formed by an alternate adsorption method, and have completed the present invention.
That is, the first aspect of the present invention is a resist pattern coating film forming material for forming a coating film on the resist pattern surface,
A first aqueous solution containing a water-soluble resin (A1) having a positively charged site in the aqueous solution and a second aqueous solution containing a water-soluble resin (A2) having a negatively charged site in the aqueous solution And a resist pattern coating film forming material.
According to a second aspect of the present invention, there is provided a resist pattern coating film formation in which a coating film is formed on the resist pattern surface formed on a support using the resist pattern coating film forming material of the first aspect. A method,
A resist pattern coating film forming method, comprising: bringing the first aqueous solution into contact with the resist pattern surface; and bringing the second aqueous solution into contact with the resist pattern surface after contacting the first aqueous solution It is.

In the present specification and claims, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups unless otherwise specified.
The “lower alkyl group” is an alkyl group having 1 to 5 carbon atoms.
The “alkylene group” includes linear, branched and cyclic divalent saturated hydrocarbon groups unless otherwise specified.
“Structural unit” means a monomer unit (monomer unit) constituting a resin (polymer).
“Exposure” is a concept that includes general irradiation of radiation.

  The present invention can provide a resist pattern coating film forming material capable of forming an organic coating film on the resist pattern surface, and a resist pattern coating film forming method using the resist pattern coating film forming material.

≪Material for forming resist pattern coating film≫
The resist pattern coating film forming material of the present invention has a first aqueous solution containing the water-soluble resin (A1) having a positive charge in an aqueous solution and a negative charge in the aqueous solution. And a second aqueous solution containing the water-soluble resin (A2).
By using such a resist pattern coating film forming material, an organic coating film can be formed on the resist pattern surface. That is, first, when the first aqueous solution is brought into contact with the resist pattern surface, the water-soluble resin (A1) in the first aqueous solution is adsorbed on the resist pattern surface by the positive charge, thereby A layer of water-soluble resin (A1) (hereinafter sometimes referred to as (A1) layer) is formed on the pattern surface. Next, when the second aqueous solution is brought into contact therewith, the water-soluble resin (A2) in the second aqueous solution is adsorbed on the (A1) layer, and the water-soluble resin (A2) layer (hereinafter referred to as ( A2) layer)) is formed. As a result, an organic film (resist pattern coating film) in which the (A1) layer and the (A2) layer are laminated is formed on the resist pattern surface.
Further, when the first aqueous solution and the second aqueous solution are alternately brought into contact with each other, the (A1) layer and the (A2) layer are alternately laminated, whereby the resist pattern coating film The film thickness can be further increased.

<First aqueous solution>
The first aqueous solution contains a water-soluble resin (A1) having a positively charged portion in the aqueous solution.
As the water-soluble resin (A1), for example, a cationic resin that has been used in the alternate adsorption method so far can be used. Especially, what has the salt formation site | part which is ionized in aqueous solution and has a positive charge in the polymer principal chain or side chain part of the said resin is preferable. The salt-forming site is a site comprising a group containing a positively charged atom (hereinafter referred to as a positively charged group) and a counter ion that forms a salt by neutralizing the charge of the positively charged group. Examples of the positively charged group include a group having N ⁺ and a group having S ⁺ .
Examples of the group having a N ^+, for example, (+ _-NH ³⁾ NH ₄ from one group other than a hydrogen atom, or a group substituted for some or all substituents of the hydrogen atom; from NH ₄ A group in which two hydrogen atoms have been removed (> NH ₂ ⁺ ), or a group in which some or all of the hydrogen atoms have been substituted with substituents; a group in which three hydrogen atoms have been removed from NH ₄ (≡NH ⁺ Or a group in which the hydrogen atom is substituted with a substituent. As said substituent, an alkyl group, an alkoxy group, an aryl group etc. are mentioned, for example, Among these, a C1-C5 alkyl group is preferable.
The counter ion of the positively charged group is not particularly limited as long as it forms a salt with the positively charged group, and examples thereof include halogen ions such as chlorine ion, bromine ion, fluorine ion and iodine ion. Among these, halogen ions are preferable, and chlorine ions or bromine ions are particularly preferable.
In addition to the above, examples of the site that is ionized in an aqueous solution and has a positive charge include —NH ₂ ,> NH, and the like.

  More specifically, examples of the water-soluble resin (A1) include resins having any one or more of structural units represented by the following formulas (11) to (19). Specific examples of such resins include polydimethyldiallylammonium salts (PDDA) such as polydimethyldiallylammonium chloride (PDDA-Cl) and polydimethyldiallylammonium bromide (PDDA-Br), polyallylamine (PAH), polyethyleneimine ( PEI), poly-2-vinyl-1-methylpyridinium bromide (P2VMP), poly-4-vinyl-1-methylpyridinium bromide (P4VMP), poly-2-methacryloxyethyltrimethylammonium bromide (PMEA), and the like.

In said formula, R < ¹⁰¹ > -R < ¹¹⁰ > is a C1-C5 alkyl group each independently.
X ^{11 to} X ¹⁸ are each independently a halogen ion or an anionic organic ion. Examples of halogen ions include chlorine ions and bromine ions. Examples of anionic organic ions include anionic organic ions such as paratoluenesulfonic acid.

In the present invention, the water-soluble resin (A1) preferably has a cyclic group. Thereby, the etching resistance of the coating film to be formed is improved, and as a result, the etching resistance of the resist pattern covered with the coating film is also improved.
The cyclic group may be an aliphatic cyclic group or an aromatic cyclic group.
Here, in the present specification and claims, “aliphatic” is a relative concept with respect to aromatics, and means a group, a compound, or the like that does not have aromaticity. The “aliphatic cyclic group” indicates a monocyclic group or polycyclic group having aromaticity. The “aromatic cyclic group” indicates a monocyclic group or polycyclic group having aromaticity.
In the aliphatic cyclic group, the basic ring structure excluding the substituent may be a group consisting of carbon and hydrogen (aliphatic hydrocarbon group), and on the ring skeleton of the aliphatic hydrocarbon group. It may be an aliphatic heterocyclic group in which a carbon atom is substituted with a heteroatom such as a nitrogen atom or a sulfur atom.
The aliphatic hydrocarbon group may be saturated or unsaturated, but is usually preferably saturated. Specific examples of the aliphatic hydrocarbon group include a group in which one or more hydrogen atoms have been removed from a monocycloalkane; one or more hydrogen atoms have been removed from a polycycloalkane such as a bicycloalkane, tricycloalkane, or tetracycloalkane. The group etc. can be illustrated. Specifically, a group obtained by removing one or more hydrogen atoms from a monocycloalkane such as cyclopentane or cyclohexane, or one or more polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Examples include a group excluding a hydrogen atom. In these groups, some or all of the hydrogen atoms may be substituted with a substituent (for example, a lower alkyl group, a fluorine atom or a fluorinated alkyl group).
In the aromatic cyclic group, the basic ring structure excluding the substituent may be a group consisting of carbon and hydrogen (aromatic hydrocarbon group), and the carbon atom on the ring skeleton is a nitrogen atom or sulfur. It may be an aromatic heterocyclic group substituted with a heteroatom such as an atom. Examples of the aromatic hydrocarbon group include an aromatic hydrocarbon group having 6 to 16 carbon atoms, specifically, a group in which one or more hydrogen atoms are removed from benzene, naphthalene, anthracene, phenanthrene, pyrene, or the like. Can be illustrated.

In the present invention, it is particularly preferable that the water-soluble resin (A1) is a resin having a structural unit derived from a diallyldialkylammonium salt (hereinafter referred to as resin (A1-1)). Resin (A1-1) has high adsorptivity to the resist pattern surface. Moreover, since the structural unit contains a cyclic group, the etching resistance is excellent.
Here, in the present specification and claims, the “structural unit derived from diallyldialkylammonium salt” means that an ethylenic double bond (a double bond of an allyl group) of diallyldialkylammonium salt is cleaved. It means the structural unit to be formed.
Examples of the structural unit derived from a diallyldialkylammonium salt include structural units represented by the following general formula (a-1-1) or (a-1-2).

［式中、Ｒ^１〜Ｒ^４はそれぞれ独立に炭素数１〜５のアルキル基であり；Ｍ_１〜Ｍ_２はそれぞれ独立に１価のアニオンである。］

[Wherein, R ^{1 to} R ⁴ are each independently an alkyl group having 1 to 5 carbon atoms; and M _{1 to} M ₂ are each independently a monovalent anion. ]

As the alkyl group for R ^{1 to} R ⁴ , a linear or branched alkyl group having 1 to 5 carbon atoms is preferable, a methyl group or an ethyl group is more preferable, and a methyl group is particularly preferable.
Examples of M _{1 to} M ₂ are the same as those mentioned as the counter ion.

In the resin (A1-1), the proportion of the structural unit derived from the diallyldialkylammonium salt is preferably 50 to 100 mol% with respect to the total of all the structural units constituting the resin (A1-1), and 75 to 100 Mole% is more preferred. When it is 50 mol% or more, the adsorptivity to the resist pattern surface is high, and the film formability of the resist pattern coating film is improved.
The resin (A1-1) is most preferably a resin composed of structural units derived from a diallyldialkylammonium salt, that is, a polydiallyldialkylammonium salt.

  The resin (A1-1) may have a structural unit other than the structural unit derived from the diallyldialkylammonium salt as long as the effects of the present invention are not impaired. Such a structural unit may be any one derived from a monomer copolymerizable with a diallyldialkylammonium salt.

Resin (A1-1) may be used individually by 1 type, and may use 2 or more types together.
Further, as the water-soluble resin (A1), a mixed resin of the resin (A1-1) and other water-soluble resins may be used.

The water-soluble resin (A1) preferably has a mass average molecular weight (polystyrene equivalent weight average molecular weight by gel permeation chromatography (GPC), the same shall apply hereinafter) of 50,000 to 1,000,000, more preferably 100,000 to 800,000. More preferably, it is 100,000 to 500,000. Adhesiveness with a dry etching resistant resist pattern etc. are in the said range.
A commercially available water-soluble resin (A1) may be used or synthesized.

  In the first aqueous solution, the concentration of the water-soluble resin (A1) is preferably 0.01 to 50% by mass, more preferably 0.05 to 10% by mass with respect to the total mass of the first aqueous solution, Most preferably, it is -5 mass%. Within the above range, the adhesion to the resist pattern is improved.

In addition to the water-soluble resin (A1), the first aqueous solution contains, as an optional component, a surfactant, an ionic strength adjusting agent, a pH adjusting agent and the like as optional components as long as the effects of the present invention are not impaired. It can be added and contained as appropriate.
Examples of the ionic strength adjusting agent include inorganic salts (alkali metal ions) such as NaCl, and organic salts such as sodium paratoluenesulfonate and tetramethyl bromide.
As the pH adjusting agent, general acid, alkali, pH adjusting buffer and the like can be used.
The pH of the first aqueous solution is preferably from 0.1 to 11, more preferably from 0.2 to 9, and most preferably from 0.1 to 7.

<Second aqueous solution>
The second aqueous solution contains a water-soluble resin (A2) having a negatively charged portion in the aqueous solution.
As the water-soluble resin (A2), for example, an anionic resin that has been used in the alternate adsorption method so far can be used. Examples of such an anionic resin include resins having a group (hereinafter referred to as a negatively charged group) that is negatively charged in an aqueous solution in the polymer main chain or side chain portion of the resin. Specific examples of the negative charge groups, for ^{_{example, -SO 3 H, -SO 3 -}} M 3, -COOH, -COO - M 3 , and the like, _-SO 3 H Of these, -SO ₃ ^- M ₃ is preferred. In the formula, M ₃ is a monovalent cation, and examples thereof include alkali metal ions such as sodium ion and potassium ion.
More specifically, examples of the water-soluble resin (A2) include resins having any one or more of structural units represented by the following formulas (21) to (29). Any one of these resins may be used alone, or two or more thereof may be mixed and used.
Specific examples of the water-soluble resin (A2) include, for example, polystyrene sulfonic acid (PSS), polyvinyl sulfate, polyacrylic acid (PAA), polymaleic acid (PMA), polymaleic acid ammonium salt (PMAA), PSS and poly (2, 3-Dihydrothieno (3,4-b-1,4-dioxin)) (PDHD) and mixed resin (PSS-PDHD) and the like. Examples of PSS-PDHD include those represented by the following formula (30).

In the present invention, the water-soluble resin (A2) preferably has a cyclic group. Thereby, the etching resistance of the coating film to be formed is improved, and as a result, the etching resistance of the resist pattern covered with the coating film is also improved.
Examples of the cyclic group include those similar to the cyclic group mentioned in the section of the water-soluble resin (A2).

In the present invention, the water-soluble resin (A2) is particularly preferably a resin having a structural unit derived from styrenesulfonic acid or a salt thereof (hereinafter referred to as resin (A2-1)).
Here, in the present specification and claims, the “structural unit derived from styrene sulfonic acid or a salt thereof” is a component constituted by cleavage of an ethylenic double bond of styrene sulfonic acid or a salt thereof. Means a unit.
Examples of the structural unit derived from styrene sulfonic acid or a salt thereof include a structural unit represented by the following general formula (a-2-1).

［式中、Ｒは水素原子、炭素数１〜５のアルキル基、ハロゲン原子またはハロゲン化アルキル基であり；Ｒ^５は炭素数１〜５のアルキル基であり；Ｍ_３は水素原子または１価のカチオンであり；ｐは１〜２の整数であり；ｑは０〜２の整数である。］

[Wherein, R is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogen atom or a halogenated alkyl group; R ⁵ is an alkyl group having 1 to ⁵ carbon atoms; M ₃ is a hydrogen atom or monovalent] P is an integer of 1-2; q is an integer of 0-2. ]

Specific examples of the alkyl group for R include lower linear chains such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, and neopentyl. Or a branched alkyl group. Examples of the halogen atom for R include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the halogenated alkyl group for R include groups in which some or all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms have been substituted with the halogen atoms.
R is preferably a hydrogen atom or a lower alkyl group, and most preferably a hydrogen atom or a methyl group in terms of industrial availability.
As the alkyl group for R ^5, the same alkyl groups as those for R can be used.
The cation of M _3, is not particularly limited, such as sodium ions, alkali metal ions such as potassium ions.
M ₃ is most preferably a hydrogen atom.
p is most preferably 1.
q is preferably 0 or 1, and most preferably 0.

In the resin (A2-1), the proportion of structural units derived from styrene sulfonic acid is preferably 50 to 100 mol%, preferably 75 to 100 mol based on the total of all structural units constituting the resin (A2-1). % Is more preferable. When it is 50 mol% or more, the adsorptivity to the water-soluble resin (A1) is high, and the film formability of the resist pattern coating film is improved.
In particular, the resin (A2-1) is most preferably a resin composed of structural units derived from styrenesulfonic acid, that is, polystyrenesulfonic acid.

  The resin (A2-1) may have a structural unit other than the structural unit derived from styrenesulfonic acid as long as the effects of the present invention are not impaired. Such a structural unit may be derived from a monomer copolymerizable with styrene sulfonic acid. Examples of the monomer include ethylene and its derivatives, vinyl alcohol and its derivatives, acrylic acid and its derivatives, acrylamide and Examples thereof include acrylonitrile and derivatives thereof, methacrylic acid and derivatives thereof, styrene and derivatives thereof, and the like.

Resin (A2-1) may be used individually by 1 type, and may use 2 or more types together.
Further, as the water-soluble resin (A2), a mixed resin of the resin (A2-1) and other water-soluble resins may be used. Examples of such a mixed resin include the above-described PSS-PDHD.

The water-soluble resin (A2) has a mass average molecular weight of preferably 500 to 1500,000, more preferably 500 to 1200000, and further preferably 500 to 1000000. It is excellent in the adhesiveness etc. to a resist pattern as it is the said range.
A commercially available water-soluble resin (A2) may be used or synthesized.

In addition to the water-soluble resin (A2), the second aqueous solution contains, as an optional component, a surfactant, an ionic strength adjusting agent, a pH adjusting agent and the like as optional components, as long as the effects of the present invention are not impaired. It can be added and contained as appropriate.
Examples of the ionic strength adjusting agent include inorganic salts (alkali metal ions) such as NaCl, and organic salts such as sodium paratoluenesulfonate and tetramethyl bromide.
As the pH adjusting agent, general acid, alkali, pH adjusting buffer and the like can be used.
3-13 are preferable, as for pH of a 2nd aqueous solution, 4-11 are more preferable, and 6-8 are the most preferable.

  In the second aqueous solution, the concentration of the water-soluble resin (A2) is preferably 0.01 to 50% by mass, more preferably 0.05 to 10% by mass with respect to the total mass of the second aqueous solution, Most preferably, it is -5 mass%. Within the above range, the adhesion to the resist pattern is improved.

  The resist pattern coating film forming material of the present invention is used for forming a coating film on the resist pattern surface, and particularly preferably used in the resist pattern coating film forming method of the present invention described below.

≪Method for forming resist pattern coating film≫
The resist pattern coating film forming method of the present invention comprises a step of bringing the first aqueous solution into contact with the resist pattern surface formed on a support (hereinafter referred to as a first contact step), and the first aqueous solution. A step of bringing the second aqueous solution into contact with the resist pattern surface after the contact (hereinafter referred to as a second contact step). Thereby, as described above, an organic coating film can be formed on the resist pattern surface.

In the first contact step, the resist pattern with which the first aqueous solution is brought into contact is not particularly limited, and may be formed by a known lithography method using a conventionally known resist material. On the resist pattern surface, there are usually hydrophilic groups (hydroxyl group, carboxy group, etc.) that enhance the solubility in a developer (alkaline aqueous solution). Therefore, when the first aqueous solution is brought into contact with the resist pattern surface, the positively charged portion of the water-soluble resin (A1) in the first aqueous solution is adsorbed to the hydrophilic group on the resist pattern surface. As a result, a water-soluble resin (A1) layer ((A1) layer) is formed on the resist pattern surface. At this time, if the water-soluble resin (A1) has the salt-forming site, the adsorption to the resist pattern surface becomes stronger.
The method of bringing the first aqueous solution into contact with the resist pattern surface formed on the support is not particularly limited. For example, the method of immersing the support having the resist pattern formed in the first aqueous solution. And a method of applying the first aqueous solution on the resist pattern by a spin coating method.
The contact time between the resist pattern surface and the first aqueous solution is not particularly limited. For example, even if the contact time is changed between 10 and 60 seconds, there is almost no effect on the thickness of the coating film to be formed. It is presumed that this is because adsorption of the water-soluble resin (A1) to the resist pattern surface is completed instantaneously upon contact.

After the first contact step and before the second contact step, the resist pattern surface after contacting the first aqueous solution may be dried.
The drying method is not particularly limited, and a known method can be used. For example, baking treatment may be performed, a drying gas such as nitrogen gas may be used, and application of the first aqueous solution using a spinner In the case of carrying out, it may be shaken off and dried as it is.

Next, a second contact step is performed in which the second aqueous solution is brought into contact with the resist pattern surface after the first aqueous solution is brought into contact therewith. Thereby, the water-soluble resin (A2) in the second aqueous solution is adsorbed to the water-soluble resin (A1), and a layer of the water-soluble resin (A2) ((A2) layer) is formed on the (A1) layer. It is formed.
The method of bringing the second aqueous solution into contact is not particularly limited. For example, a method of immersing a support having the resist pattern formed in the second aqueous solution, the second aqueous solution on the resist pattern. The method of apply | coating by a spin coat method etc. is mentioned.
The contact time between the resist pattern surface and the second aqueous solution is not particularly limited. For example, even if the contact time is changed between 10 and 60 seconds, there is almost no effect on the thickness of the coating film to be formed. It is presumed that this is because the adsorption of the water-soluble resin (A2) to the water-soluble resin (A1) is completed instantaneously upon contact.
Similarly, the film thickness of the coating film to be formed is not affected by the concentration of the water-soluble resin (A1) in the second aqueous solution, and the content ranges from 0.1 to 0.5% by mass, for example. The film thickness of the coating film to be formed is almost the same even if it is changed within the range.

  By performing the first contact step and the second contact step, an organic film (resist pattern coating film) in which the (A1) layer and the (A2) layer are laminated is formed on the resist pattern surface. The resist pattern coating film thus formed is usually a thin film of several nanometers to several tens of nanometers.

In the present invention, after the second contact step, a step of bringing the first aqueous solution and the second aqueous solution into contact with the resist pattern surface alternately (hereinafter referred to as an alternating contact step) is further performed. preferable. By performing this step, the (A1) layer and the (A2) layer are alternately laminated on the (A2) layer formed in the second contact step, and thereby the film thickness of the resist pattern coating film. Can be made even thicker. Moreover, the film thickness of a resist pattern coating film can be adjusted by adjusting the frequency | count of making a 1st aqueous solution and said 2nd aqueous solution contact alternately.
What is necessary is just to set suitably the frequency | count of making a 1st aqueous solution and said 2nd aqueous solution contact alternately (alternate contact process) according to a desired film thickness. As the number of times increases, the thickness of the resist pattern coating film to be formed increases.

In the alternating contact step, the resist pattern surface may be dried before contacting the first aqueous solution or the second aqueous solution. The density of the coating film to be formed can be adjusted by selecting whether or not to perform the drying.
The drying method is not particularly limited, and a known method can be used. For example, baking treatment may be performed, a drying gas such as nitrogen gas may be used, and application of the first aqueous solution using a spinner In the case of carrying out, it may be shaken off and dried as it is.

  The film thickness of the coating film formed on the resist pattern surface by the resist pattern coating film forming method of the present invention is preferably 0.1 to 50 nm, more preferably 1 to 30 nm, and further preferably 1 to 10 nm. By setting it within this range, there are effects such as improving the etching resistance of the resist pattern coated with the coating film and improving LER.

In the present invention, it is preferable to further perform a step of cleaning the resist pattern surface after contacting the first aqueous solution or the second aqueous solution. As a result, even if excess water-soluble resin (A1) and / or water-soluble resin (A2) is attached to the surface of the support where there is no resist film (non-patterned portion), Since the adhesion is very weak, it is washed away by the washing or the concentration becomes very thin. At this time, the water-soluble resin (A1) and the water-soluble resin (A2) adsorbed on the resist pattern surface remain intact because they are firmly attached. Therefore, the coating film is sufficiently formed on the resist pattern surface, but the coating film is not formed or hardly formed on the surface of the non-pattern part on the support. As a result, the resist pattern surface is highly selective. A coating film can be formed. Further, by washing, it is possible to prevent the resin from being deposited on the surface of the formed coating film due to the formation of salt.
For cleaning, a known method can be used, for example, water may be used.

In the present invention, it is preferable to dry the resist pattern surface after the second contact step or after the alternating contact step and optionally after performing a cleaning step. Thereby, the film thickness uniformity of the coating film formed on the resist pattern surface, the adhesion to the resist pattern surface, and the like are improved.
The drying method is not particularly limited, and a known method can be used. For example, baking may be performed, a drying gas such as nitrogen gas may be used, and the first aqueous solution and the spinner may be used. When the second aqueous solution is applied, it may be shaken and dried as it is.
In the present invention, it is particularly preferable to perform a baking treatment.
In the baking process, the baking temperature is preferably 100 to 120 ° C.
The baking time is not particularly limited, and is usually in the range of 30 to 90 seconds.

[Resist material]
In the present invention, the resist material for forming the resist pattern covered with the resist pattern coating film is not particularly limited, and any resist material proposed so far may be appropriately selected and used. There are two types of resist materials: a positive type in which the alkali solubility in the exposed area increases, and a negative type in which the alkali solubility in the exposed area decreases. In the present invention, the resist pattern is formed using a positive resist material. It is preferred that

As the resist composition, a chemically amplified resist composition is preferable because of excellent sensitivity, resolution, and the like.
There is no restriction | limiting in particular as a chemically amplified resist composition, It can select suitably from many chemically amplified resist compositions proposed until now and can use it. The chemically amplified resist composition includes a base material component (A ′) whose alkali solubility is changed by the action of an acid (hereinafter referred to as “component (A ′)”) and an acid generator that generates an acid upon irradiation with radiation. Generally, the component (B ′) (hereinafter referred to as “component (B ′)”) is dissolved in an organic solvent (S ′) (hereinafter referred to as “component (S ′)”).
Here, the “base material component” is an organic compound having a film forming ability, and an organic compound having a molecular weight of 500 or more is preferably used. When the molecular weight of the organic compound is 500 or more, the film forming ability is improved and a nano-level pattern is easily formed.
The organic compound having a molecular weight of 500 or more is roughly classified into a low molecular weight organic compound having a molecular weight of 500 to 2000 (hereinafter referred to as a low molecular compound) and a high molecular weight resin having a molecular weight of more than 2000 (polymer). Is done. As the low molecular weight compound, a non-polymer is usually used. In the case of a resin (polymer), a polystyrene-reduced weight average molecular weight by GPC (gel permeation chromatography) is used as the “molecular weight”. Hereinafter, the term “resin” simply means a resin having a molecular weight of more than 2000.
The component (A ′) may be a low molecular compound whose alkali solubility is changed by the action of an acid, or a resin whose alkali solubility is changed by the action of an acid, or a mixture thereof. Also good.

As the component (A ′), an organic compound that is usually used as a base component for a chemically amplified resist can be used singly or in combination of two or more.
As the component (A ′) of the chemically amplified resist composition used in the present invention, those having a hydrophilic group are preferable. By having a hydrophilic group, when a resist pattern is formed using the chemically amplified resist composition, a coating film having excellent adhesion can be formed on the resist pattern. That is, when the component (A ′) has a hydrophilic group, the hydrophilic group exists on the resist pattern surface. Then, the water-soluble resin (A1) in the first aqueous solution is adsorbed to the hydrophilic group, whereby a coating film can be formed on the resist pattern.
Examples of the hydrophilic group in the component (A ′) include a hydroxyl group, a carboxy group, a carbonyl group (—C (O) —), an ester group (ester bond; —C (O) —O—), an amino group, and an amide group. One or more selected from the group consisting of Among these, a hydroxyl group (particularly an alcoholic hydroxyl group or a phenolic hydroxyl group), a carboxy group, and an ester group are more preferable.
Among these, a carboxy group, an alcoholic hydroxyl group, and a phenolic hydroxyl group are particularly preferable because they easily form a coating film on the pattern surface. In addition, a pattern with small line edge roughness (unevenness on the pattern side wall) can be formed at the nano level, which is preferable.

The content ratio of the hydrophilic group in the component (A ′) affects the amount per unit area of the hydrophilic group present on the pattern surface. Therefore, the adhesion and density of the coating film formed on the pattern can be affected.
When the component (A ′) is a low molecular compound, the component (A ′) preferably has 1 to 20 equivalents of hydrophilic groups per molecule, more preferably 2 to 10 equivalents. Here, “having 1 to 20 equivalents of hydrophilic group per molecule” means that 1 to 20 hydrophilic groups are present in one molecule.
When the component (A ′) is a resin, the component (A) preferably has a hydrophilic group of 0.2 equivalent or more, more preferably 0.5 to 0.8 equivalent, and still more preferably 0.6 to It is the range of 0.75 equivalent. This is because if the resin is composed of a structural unit having a hydrophilic group and other structural units, the former structural unit is 20 mol% or more, more preferably 50 to 80 mol%, still more preferably 60 mol% to It means 75 mol%.

When the chemically amplified resist composition is a negative resist composition, as the component (A ′), a base material component whose alkali solubility is reduced by the action of an acid is used. Furthermore, a crosslinking agent is blended.
In such a negative resist composition, when an acid is generated from the component (B ′) by exposure, crosslinking occurs between the component (A ′) and the crosslinking agent by the action of the acid, and the component (A ′) is an alkali. Changes from soluble to insoluble in alkali. Therefore, in the formation of the resist pattern, when the resist film obtained by applying the negative resist composition on the substrate is selectively exposed, the exposed portion turns into alkali-insoluble while the unexposed portion is alkali-soluble. Since it remains unchanged, alkali development can be performed.
As the component (A ′) of the negative resist composition, an alkali-soluble resin is usually used. As the alkali-soluble resin, α- (hydroxyalkyl) acrylic acid, or lower of α- (hydroxyalkyl) acrylic acid is used. A resin having a unit derived from at least one selected from alkyl esters is preferable because a good resist pattern with less swelling can be formed. Note that α- (hydroxyalkyl) acrylic acid includes acrylic acid in which a hydrogen atom is bonded to the α-position carbon atom to which the carboxy group is bonded, and a hydroxyalkyl group (preferably having 1 carbon atom) in the α-position carbon atom. One or both of [alpha] -hydroxyalkylacrylic acids to which (5) hydroxyalkyl groups) are attached.
As the crosslinking agent, for example, it is usually preferable to use an amino crosslinking agent such as glycoluril having a methylol group or an alkoxymethyl group because a good resist pattern with less swelling can be formed. It is preferable that the compounding quantity of a crosslinking agent is 1-50 mass parts with respect to 100 mass parts of alkali-soluble resin.

When the chemically amplified resist composition is a positive resist composition, as the component (A ′), a base material component having an acid dissociable, dissolution inhibiting group and increasing alkali solubility by the action of an acid is used. .
Such a positive resist composition is insoluble in alkali before exposure. When an acid is generated from the component (B ′) upon exposure during the formation of the resist pattern, the acid dissociable, dissolution inhibiting group is dissociated by the action of the acid, The component A ′) changes to alkali-soluble. Therefore, in the formation of the resist pattern, when the resist film obtained by applying the positive resist composition on the substrate is selectively exposed, the exposed portion turns into alkali-soluble while the unexposed portion is alkali-insoluble. Since it remains unchanged, alkali development can be performed.

As the (A ′) component of the positive resist composition, those having a hydrophilic group and an acid dissociable, dissolution inhibiting group are preferable, and the following (A′-1) component and / or (A′-2) component are: More preferred. The hydrophilic group may also serve as an acid dissociable, dissolution inhibiting group.
-(A'-1) component: Resin which has a hydrophilic group and an acid dissociable, dissolution inhibiting group.
Component (A′-2): a low molecular compound having a hydrophilic group and an acid dissociable, dissolution inhibiting group.
Hereinafter, the preferable aspect of (A-1) component and (A'-2) component is demonstrated more concretely.

[(A′-1) component]
As the component (A′-1), a resin having a structural unit having a hydrophilic group and a structural unit having an acid dissociable, dissolution inhibiting group is preferable.
The proportion of the structural unit having the hydrophilic group in the resin is preferably 20 to 80 mol%, more preferably 20 to 70 mol%, based on the total amount of all the structural units constituting the resin. 20 to 60 mol% is more preferable.
The proportion of the structural unit having the acid dissociable, dissolution inhibiting group in the resin is preferably 20 to 80 mol% with respect to the total amount of all structural units constituting the resin. Is more preferable, and 30 to 60 mol% is more preferable.
Preferably, the structural unit having a hydrophilic group is a structural unit having a carboxy group, an alcoholic hydroxyl group or a phenolic hydroxyl group, more preferably an acrylic acid, methacrylic acid or an alcoholic hydroxyl group (α-lower alkyl). A unit derived from an acrylate ester and hydroxystyrene.

More specifically, the component (A′-1) is derived from a novolak resin having a hydrophilic group and an acid dissociable, dissolution inhibiting group, a hydroxystyrene resin, an (α-lower alkyl) acrylate resin, or hydroxystyrene. And a copolymer resin containing a structural unit derived from an (α-lower alkyl) acrylate ester are preferably used.
In this specification, “(α-lower alkyl) acrylic acid” refers to one or both of acrylic acid (CH ₂ ═CH—COOH) and α-lower alkylacrylic acid. α-Lower alkyl acrylic acid refers to one in which a hydrogen atom bonded to a carbon atom to which a carbonyl group in acrylic acid is bonded is substituted with a lower alkyl group. “(Α-Lower alkyl) acrylic acid ester” is an ester derivative of “(α-lower alkyl) acrylic acid” and represents one or both of acrylic acid ester and α-lower alkyl acrylic acid ester.
The “structural unit derived from (α-lower alkyl) acrylic acid ester” is a structural unit formed by cleavage of an ethylenic double bond of (α-lower alkyl) acrylic acid ester. -Lower alkyl) acrylate structural unit. “(Α-lower alkyl) acrylate” refers to one or both of acrylate and α-lower alkyl acrylate.
The “structural unit derived from hydroxystyrene” is a structural unit formed by cleaving an ethylenic double bond of hydroxystyrene or α-lower alkylhydroxystyrene, and may hereinafter be referred to as a hydroxystyrene unit. “Α-lower alkylhydroxystyrene” indicates that the lower alkyl group is bonded to the carbon atom to which the phenyl group is bonded.
In the “structural unit derived from an α-lower alkyl acrylate ester” and the “structural unit derived from an α-lower alkylhydroxystyrene”, the lower alkyl group bonded to the α-position has 1 to 5 carbon atoms. An alkyl group, preferably a linear or branched alkyl group, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group Etc. Industrially, a methyl group is preferable.

Although it does not specifically limit as a resin component suitable as (A'-1) component, For example, the unit which has a phenolic hydroxyl group like the following structural unit (a'1), and the following structural unit (a ' 2) and a structural unit having at least one acid dissociable, dissolution inhibiting group selected from the group consisting of the following structural units (a′3), and alkali-insoluble such as (a′4) used as necessary The resin component which has a unit (it may hereafter be called (A'-11) component).
In the component (A′-11), cleavage occurs in the structural unit (a′2) and / or the structural unit (a′3) by the action of an acid generated from the acid generator upon exposure. Increases the alkali solubility in a resin that is insoluble in an alkaline developer. As a result, a chemically amplified positive pattern can be formed by exposure and development.

..Structural unit (a'1)
The structural unit (a′1) is a unit having a phenolic hydroxyl group, and is preferably a unit derived from hydroxystyrene represented by the following general formula (I ′).

（式中、Ｒは水素原子、炭素数１〜５のアルキル基、ハロゲン原子またはハロゲン化アルキル基を示す。）

(In the formula, R represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogen atom or a halogenated alkyl group.)

R is the same as R in the formula (a-2-1), and is preferably a hydrogen atom or a methyl group. The description of R is the same below.
The bonding position of —OH to the benzene ring is not particularly limited, but the position 4 (para position) described in the formula is preferred.
The structural unit (a′1) is contained in the component (A′-11) in an amount of 40 to 80 mol%, preferably 50 to 75 mol%, from the viewpoint of forming a pattern. By setting it as 40 mol% or more, the solubility with respect to an alkali developing solution can be improved, and the improvement effect of a pattern shape is also acquired. The balance with other structural units can be taken by setting it as 80 mol% or less.
In view of the formation of a coating film on the pattern, the structural unit (a′1) is preferably contained in the component (A′-11) in an amount of 50 mol% or more, more preferably 60 mol. % Or more, more preferably 75 mol% or more. Although an upper limit is not specifically limited, It is 80 mol% or less. Within the above range, due to the presence of the phenolic hydroxyl group, a good coating film can be formed on the pattern, and a pattern with a good shape can be obtained. In addition, the adhesion between the pattern and the coating film is improved.

..Structural unit (a'2)
The structural unit (a′2) is a structural unit having an acid dissociable, dissolution inhibiting group, and is represented by the following general formula (II ′).

（式中、Ｒは上記と同じであり、Ｘは酸解離性溶解抑制基を示す。）

(In the formula, R is the same as above, and X represents an acid dissociable, dissolution inhibiting group.)

The acid dissociable, dissolution inhibiting group X is an alkyl group having a tertiary carbon atom, and the tertiary carbon atom of the tertiary alkyl group is bonded to the ester group [—C (O) O—]. Examples thereof include acid-dissolving dissolution inhibiting groups, cyclic acetal groups such as a tetrahydropyranyl group and a tetrahydrofuranyl group.
As such an acid dissociable, dissolution inhibiting group X, for example, those other than the above can be arbitrarily used from among those used in a chemically amplified positive resist composition.

  As the structural unit (a′2), for example, those represented by general formula (III ′) shown below are preferred.

In the formula, R is the same as above, and R ¹¹ , R ¹² , and R ¹³ are each independently a lower alkyl group (which may be linear or branched. Preferably, it has 1 to 5 carbon atoms.) It is. Or, among R ¹¹ , R ¹² and R ¹³ , R ¹¹ may be a lower alkyl group, and R ¹² and R ¹³ may be bonded to form a monocyclic or polycyclic aliphatic cyclic group. . The aliphatic cyclic group preferably has 5 to 12 carbon atoms.
Here, “aliphatic” means that the group or compound does not have aromaticity, and “aliphatic cyclic group” means a monocyclic group or polycyclic group having no aromaticity. Means group.
When R ¹¹ , R ¹² and R ¹³ do not have an aliphatic cyclic group, for example, it is preferable that R ¹¹ , R ¹² and R ¹³ are all methyl groups.
In the case where any of R ¹¹ , R ¹² and R ¹³ has an aliphatic cyclic group, when the aliphatic cyclic group is a monocyclic aliphatic cyclic group, as the structural unit (a′2), For example, those having a cyclopentyl group or a cyclohexyl group are preferred.
When the aliphatic cyclic group is a polycyclic alicyclic group, preferred examples of the structural unit (a′2) include those represented by the following general formula (IV ′).

［式中、Ｒは上記と同じであり、Ｒ^１４は低級アルキル基（直鎖、分岐鎖のいずれでもよい。好ましくは炭素数１〜５である。）］

[Wherein, R is the same as above, and R ¹⁴ is a lower alkyl group (which may be either linear or branched. Preferably, it has 1 to 5 carbon atoms.)]

  Moreover, what is represented by the following general formula (V ') as a thing which has an acid dissociable dissolution inhibiting group containing a polycyclic aliphatic cyclic group is also preferable.

［式中、Ｒは上記と同じであり、Ｒ^１５、Ｒ^１６は、それぞれ独立に低級アルキル基（直鎖、分岐鎖のいずれでもよい。好ましくは炭素数は１〜５である。）である。］

[Wherein, R is the same as defined above, and R ¹⁵ and R ¹⁶ each independently represent a lower alkyl group (which may be either a straight chain or a branched chain, preferably has 1 to 5 carbon atoms). . ]

  The structural unit (a′2) is preferably present in the component (A′-11) in the range of 5 to 50 mol%, preferably 10 to 40 mol%, more preferably 10 to 35 mol%. .

..Structural unit (a'3)
The structural unit (a′3) is a structural unit having an acid dissociable, dissolution inhibiting group, and is represented by the following general formula (VI ′).

（式中、Ｒは上記と同じであり、Ｘ’は酸解離性溶解抑制基を示す。）

(In the formula, R is the same as above, and X ′ represents an acid dissociable, dissolution inhibiting group.)

The acid dissociable, dissolution inhibiting group X ′ is a tertiary alkyloxycarbonyl group such as a tert-butyloxycarbonyl group or a tert-amyloxycarbonyl group; a tert-butyloxycarbonylmethyl group or a tert-butyloxycarbonylethyl group. Tertiary alkyloxycarbonylalkyl groups such as these; tertiary alkyl groups such as tert-butyl and tert-amyl groups; cyclic acetal groups such as tetrahydropyranyl and tetrahydrofuranyl groups; ethoxyethyl groups and methoxypropyl groups And the like.
Of these, a tert-butyloxycarbonyl group, a tert-butyloxycarbonylmethyl group, a tert-butyl group, a tetrahydropyranyl group, and an ethoxyethyl group are preferable.
As the acid dissociable, dissolution inhibiting group X ′, those other than those described above can be arbitrarily used from among those used in, for example, a chemically amplified positive resist composition.
In the general formula (VI ′), the bonding position of the group (—OX ′) bonded to the benzene ring is not particularly limited, but the position 4 (para position) shown in the formula is preferable.

  The structural unit (a′3) is in the range of 5 to 50 mol%, preferably 10 to 40 mol%, more preferably 10 to 35 mol% in the component (A′-11).

..Structural unit (a'4)
The structural unit (a′4) is an alkali-insoluble unit and is represented by the following general formula (VII ′).

（式中、Ｒは上記と同じであり、Ｒ^４’は低級アルキル基を示し、ｎ’は０または１〜３の整数を示す。）

(In the formula, R is the same as above, R ^{4 ′} represents a lower alkyl group, and n ′ represents 0 or an integer of 1 to 3).

The lower alkyl group for R ^{4 ′} may be either a straight chain or a branched chain, and preferably has 1 to 5 carbon atoms.
n ′ represents 0 or an integer of 1 to 3, and is preferably 0.

  The structural unit (a′4) is 1 to 40 mol%, preferably 5 to 25 mol%, in the component (A′-11). By setting it to 1 mol% or more, the effect of improving the shape (particularly, improving film loss) is enhanced, and by setting it to 40 mol% or less, it is possible to balance with other structural units.

In the component (A′-11), the constituent unit (a′1) and at least one selected from the group consisting of the constituent unit (a′2) and the constituent unit (a′3) are essential and optional. (A′4) may be included. In addition, a copolymer having all these units may be used, or a mixture of polymers having one or more of these units may be used. Or these may be combined.
Further, the component (A′-11) can optionally contain components other than the structural units (a′1), (a′2), (a′3), and (a′4). It is preferable that the proportion of the structural unit is 80 mol% or more, preferably 90 mol% or more (100 mol% is most preferred).

In particular, “any one of the copolymers having the structural units (a′1) and (a′3), or a mixture of two or more of the copolymers” or “the structural unit (a′1 ), Any one of the copolymers having (a′2) and (a′4), or a mixture of two or more of the copolymers ”, or a mode in which they are mixed or mixed, is simply effective. Is most preferable. Moreover, it is preferable also at the point of heat resistance improvement.
In particular, a mixture of polyhydroxystyrene protected with a tertiary alkyloxycarbonyl group and polyhydroxystyrene protected with a 1-alkoxyalkyl group is preferred. When such mixing is performed, the mixing ratio (mass ratio) of each polymer (polyhydroxystyrene protected with a tertiary alkyloxycarbonyl group / 1-polyhydroxystyrene protected with 1-alkoxyalkyl group) is, for example, 1/9 to The ratio is 9/1, preferably 2/8 to 8/2, and more preferably 2/8 to 5/5.

(Α-lower alkyl) acrylate resin in that a pattern with lower etching resistance can be formed as a resin component other than the above (A′-11) component suitable as the (A′-1) component. Is preferably a resin component ((α-lower alkyl) acrylate resin), more preferably a resin component comprising (α-lower alkyl) acrylate resin.
In the (α-lower alkyl) acrylate resin (hereinafter referred to as the component (A′-12)), a structural unit derived from an (α-lower alkyl) acrylate ester containing an acid dissociable, dissolution inhibiting group ( A resin having a′5) is preferred. The α-lower alkyl group is the same as described above.
The acid dissociable, dissolution inhibiting group of the structural unit (a′5) has an alkali dissolution inhibiting property that renders the entire resin component before exposure to alkali insolubility, and at the same time, due to the action of an acid generated from the (B ′) component after exposure. It is a group that dissociates and changes the entire component (A′-12) to alkali-soluble.
Further, in the (α-lower alkyl) acrylate resin component, when the acid dissociable, dissolution inhibiting group in the structural unit (a′5) is dissociated by the acid generated from the component (B ′), a carboxylic acid is generated. . Due to the presence of the generated carboxylic acid, the adhesion with the coating film formed on the resist pattern is improved.

As the acid dissociable, dissolution inhibiting group, for example, a resin for resist compositions of ArF excimer laser can be appropriately selected and used from among many proposed ones. In general, a group that forms a cyclic or chain tertiary alkyl ester with a carboxy group of (α-lower alkyl) acrylic acid, or a cyclic or chain alkoxyalkyl group is widely known.
Here, the “group forming a tertiary alkyl ester” is a group that forms an ester by substituting a hydrogen atom of a carboxy group of acrylic acid. That is, it shows a structure in which the tertiary carbon atom of a chain-like or cyclic tertiary alkyl group is bonded to the oxygen atom at the terminal of the carbonyloxy group [—C (O) —O—] of the acrylate ester. In this tertiary alkyl ester, when an acid acts, a bond is cut between an oxygen atom and a tertiary carbon atom.
The tertiary alkyl group is an alkyl group having a tertiary carbon atom.
Examples of the group that forms a chain-like tertiary alkyl ester include a tert-butyl group and a tert-amyl group.
Examples of the group that forms a cyclic tertiary alkyl ester include those exemplified in the “acid dissociable, dissolution inhibiting group containing an alicyclic group” described later.

The “cyclic or chain alkoxyalkyl group” forms an ester by substituting a hydrogen atom of a carboxy group. That is, a structure is formed in which the alkoxyalkyl group is bonded to the terminal oxygen atom of the carbonyloxy group [—C (O) —O—] of the acrylate ester. In such a structure, the bond between the oxygen atom and the alkoxyalkyl group is broken by the action of the acid.
Examples of such cyclic or chain alkoxyalkyl groups include 1-methoxymethyl group, 1-ethoxyethyl group, 1-isopropoxyethyl, 1-cyclohexyloxyethyl group, 2-adamantoxymethyl group, 1-methyladamant Examples thereof include a xymethyl group, a 4-oxo-2-adamantoxymethyl group, a 1-adamantoxyethyl group, and a 2-adamantoxyethyl group.

As the structural unit (a′5), a structural unit containing an acid dissociable, dissolution inhibiting group containing a cyclic group, particularly an aliphatic cyclic group, is preferable.
Here, “aliphatic” and “aliphatic cyclic group” are as defined above.
The aliphatic cyclic group may be monocyclic or polycyclic, and can be appropriately selected and used from among many proposed, for example, ArF resists. From the viewpoint of etching resistance, a polycyclic alicyclic group is preferred. The alicyclic group is preferably a hydrocarbon group, and particularly preferably a saturated hydrocarbon group (alicyclic group).
Examples of the monocyclic alicyclic group include groups in which one hydrogen atom has been removed from a cycloalkane. Examples of the polycyclic alicyclic group include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane, tetracycloalkane and the like.
Specifically, examples of the monocyclic alicyclic group include a cyclopentyl group and a cyclohexyl group. Examples of the polycyclic alicyclic group include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane.
Among these, an adamantyl group obtained by removing one hydrogen atom from adamantane, a norbornyl group obtained by removing one hydrogen atom from norbornane, a tricyclodecanyl group obtained by removing one hydrogen atom from tricyclodecane, and tetracyclo A tetracyclododecanyl group obtained by removing one hydrogen atom from dodecane is preferred industrially.

More specifically, the structural unit (a′5) is preferably at least one selected from the following general formulas (I ″) to (III ″).
And a unit derived from an (α-lower alkyl) acrylate ester having a cyclic alkoxyalkyl group as described above, specifically 2-adamantoxymethyl group, 1-methyladamant Aliphatic polycyclic alkyloxy lower alkyl (α which may have a substituent such as xymethyl group, 4-oxo-2-adamantoxymethyl group, 1-adamantoxyethyl group, 2-adamantoxyethyl group, etc. -Lower alkyl) It is preferably at least one selected from units derived from acrylic acid esters.

［式（Ｉ”）中、Ｒは上記と同じであり、Ｒ^１は低級アルキル基である。］

[In the formula (I ″), R is the same as above, and R ¹ is a lower alkyl group.]

［式（ＩＩ”）中、Ｒは上記と同じであり、Ｒ^２及びＲ^３はそれぞれ独立に低級アルキル基である。］

[In the formula (II ″), R is the same as above, and R ² and R ³ are each independently a lower alkyl group.]

［式（ＩＩＩ”）中、Ｒは上記と同じであり、Ｒ^４は第３級アルキル基である。］

[In the formula (III ″), R is the same as above, and R ⁴ is a tertiary alkyl group.]

In formulas (I ″) to (III ″), the hydrogen atom or lower alkyl group for R is the same as described above for the hydrogen atom or lower alkyl group bonded to the α-position of the acrylate ester.
The lower alkyl group for R ¹ is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, and specifically includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. , A pentyl group, an isopentyl group, a neopentyl group, and the like. Among these, a methyl group and an ethyl group are preferable because they are easily available industrially.
The lower alkyl group for R ² and R ³ is preferably each independently a linear or branched alkyl group having 1 to 5 carbon atoms. Among them, when R ² and R ³ are both methyl groups is preferred industrially. Specific examples include structural units derived from 2- (1-adamantyl) -2-propyl acrylate.

R ⁴ is a chain-like tertiary alkyl group or a cyclic tertiary alkyl group. Examples of the chain-like tertiary alkyl group include a tert-butyl group and a tert-amyl group, and the tert-butyl group is industrially preferable.
The cyclic tertiary alkyl group is the same as that exemplified in the aforementioned “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group”, and includes a 2-methyl-2-adamantyl group, 2-ethyl- A 2-adamantyl group, 2- (1-adamantyl) -2-propyl group, 1-ethylcyclohexyl group, 1-ethylcyclopentyl group, 1-methylcyclohexyl group, 1-methylcyclopentyl group and the like can be mentioned.
The group —COOR ⁴ may be bonded to the 3 or 4 position of the tetracyclododecanyl group shown in the formula, but the bonding position cannot be specified. Similarly, the carboxy group residue of the acrylate structural unit may be bonded to the position 8 or 9 shown in the formula.

The structural unit (a′5) can be used alone or in combination of two or more.
In the component (A′-12), the proportion of the structural unit (a′5) is preferably 20 to 60 mol% with respect to the total of all the structural units constituting the component (A′-12). 30-50 mol% is more preferable, and 35-45 mol% is the most preferable. A pattern can be obtained by setting it to the lower limit value or more, and balancing with other structural units can be achieved by setting it to the upper limit value or less.

In addition to the structural unit (a′5), the component (A′-12) preferably further has a structural unit (a′6) derived from an acrylate ester having a lactone ring. The structural unit (a′6) is effective in increasing the adhesion of the resist film to the substrate and increasing the hydrophilicity with the developer. In addition, a coating film having high adhesion to the pattern can be formed.
In the structural unit (a′6), a lower alkyl group or a hydrogen atom is bonded to the α-position carbon atom. The lower alkyl group bonded to the α-position carbon atom is the same as described for the structural unit (a′5), and is preferably a methyl group.
Examples of the structural unit (a′6) include a structural unit in which a monocyclic group composed of a lactone ring or a polycyclic cyclic group having a lactone ring is bonded to the ester side chain portion of the acrylate ester. At this time, the lactone ring refers to one ring containing an —O—C (O) — structure, and this is counted as the first ring. Therefore, here, in the case of only a lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.
Examples of the structural unit (a′6) include a monocyclic group obtained by removing one hydrogen atom from γ-butyrolactone, and a polycyclic group obtained by removing one hydrogen atom from a lactone ring-containing bicycloalkane. Is mentioned.
More specifically, the structural unit (a′6) is preferably at least one selected from, for example, the following general formulas (IV ″) to (VII ″).

［式（ＩＶ”）中、Ｒは上記と同じであり、Ｒ^５、Ｒ^６は、それぞれ独立に、水素原子または低級アルキル基である。］

[In formula (IV ″), R is the same as defined above, and R ⁵ and R ⁶ each independently represent a hydrogen atom or a lower alkyl group.]

［式（Ｖ”）中、Ｒは上記と同じであり、ｍは０または１である。］

[In the formula (V ″), R is the same as above, and m is 0 or 1.]

［式（ＶＩ”）中、Ｒは上記と同じである。］

[In the formula (VI ″), R is as defined above.]

［式（ＶＩＩ”）中、Ｒは上記と同じである。］

[In the formula (VII ″), R is as defined above.]

In formula (IV ″), R ⁵ and R ⁶ each independently represent a hydrogen atom or a lower alkyl group, preferably a hydrogen atom. In R ⁵ and R ⁶ , the lower alkyl group is preferably A linear or branched alkyl group having 1 to 5 carbon atoms, such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, etc. Industrially, a methyl group is preferable.

Among the structural units represented by the general formulas (IV ″) to (VII ″), the structural unit represented by (IV ″) is inexpensive and industrially preferable, and among the structural units represented by (IV ″) R is a methyl group, R ⁵ and R ⁶ are hydrogen atoms, and the position of the ester bond between the methacrylic acid ester and γ-butyrolactone is α-methacryloyloxy-γ-butyrolactone, which is the α-position on the lactone ring. Most preferred.
The structural unit (a′6) can be used alone or in combination of two or more.
In the component (A′-12), the proportion of the structural unit (a′6) is preferably 20 to 60 mol% with respect to the total of all the structural units constituting the component (A′-12), and 20 to 50. More preferred is mol%, and most preferred is 30 to 45 mol%. Lithographic properties are improved by setting it to the lower limit value or more, and balance with other structural units can be achieved by setting the upper limit value or less.

The component (A′-12) includes a polar group-containing polycyclic group in addition to the structural unit (a′5) or in addition to the structural units (a′5) and (a′6). It is preferable to have a structural unit (a′7) derived from an acrylate ester.
The structural unit (a′7) increases the hydrophilicity of the entire component (A′-12), increases the affinity with the developer, improves the alkali solubility in the exposed area, and improves the resolution. Contribute. In addition, a coating film having high adhesion to the pattern can be formed.
In the structural unit (a′7), a lower alkyl group or a hydrogen atom is bonded to the α-position carbon atom. The lower alkyl group bonded to the α-position carbon atom is the same as described for the structural unit (a′5), and is preferably a methyl group.
Examples of the polar group include a hydroxyl group, a cyano group, a carboxy group, and an amino group, and a hydroxyl group is particularly preferable.
As the polycyclic group, among the aliphatic cyclic groups exemplified in the above-mentioned “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group” which is the unit (a′5), from the polycyclic ones It can be appropriately selected and used.
The structural unit (a′7) is preferably at least one selected from the following general formulas (VIII ″) to (IX ″).

［式（ＶＩＩＩ”）中、Ｒは上記と同じであり、ｎは１〜３の整数である。］

[In formula (VIII ″), R is the same as described above, and n is an integer of 1 to 3.]

R in the formula (VIII ″) is the same as R in the above formulas (I ″) to (III ″).
Among these, those in which n is 1 and the hydroxyl group is bonded to the 3-position of the adamantyl group are preferable.

［式（ＩＸ”）中、Ｒは上記と同じであり、ｋは１〜３の整数である。］

[In formula (IX ″), R is the same as described above, and k is an integer of 1 to 3.]

  Among these, those in which k is 1 are preferable. Moreover, it is preferable that the cyano group has couple | bonded with 5th-position or 6th-position of the norbornanyl group.

The structural unit (a′7) can be used alone or in combination of two or more.
In the component (A′-12), the proportion of the structural unit (a′7) is preferably 10 to 50 mol% with respect to the total of all the structural units constituting the component (A′-12), and 15 to 40 More preferably, mol% is more preferable, and 20-35 mol% is further more preferable. Lithographic properties are improved by setting it to the lower limit value or more, and balance with other structural units can be achieved by setting the upper limit value or less.

  In the component (A′-12), the total of these structural units (a′5) to (a′7) is preferably 70 to 100 mol% with respect to the total of all the structural units, 80 to More preferably, it is 100 mol%.

The component (A′-12) may contain a structural unit (a′8) other than the structural units (a′5) to (a′7).
The structural unit (a′8) is not particularly limited as long as it is another structural unit that is not classified into the structural units (a′5) to (a′7).
For example, a structural unit containing a polycyclic aliphatic hydrocarbon group and derived from an (α-lower alkyl) acrylate is preferable. The polycyclic aliphatic hydrocarbon group is appropriately selected from, for example, polycyclic ones among the aliphatic cyclic groups exemplified in the aforementioned “acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group”. Can be used. In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, a norbornyl group, and an isobornyl group is preferable in terms of industrial availability. The structural unit (a′8) is most preferably an acid non-dissociable group.
Specific examples of the structural unit (a′8) include those having the following structures (X ″) to (XII ″).

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

（式中、Ｒは上記と同じである。）

(In the formula, R is the same as above.)

  When the structural unit (a′8) is included, the proportion of the structural unit (a′8) in the component (A′-12) is based on the total of all structural units constituting the component (A′-12). 1-25 mol% is preferable and 5-20 mol% is more preferable.

  The component (A′-12) is preferably a copolymer having at least the structural units (a′5), (a′6) and (a′7). As such a copolymer, for example, a copolymer comprising the structural units (a′5), (a′6) and (a′7), the structural units (a′5), (a′6), Examples thereof include a copolymer comprising (a′7) and (a′8).

The component (A′-1) can be obtained by polymerizing the monomer related to the structural unit by a known method. For example, the monomer related to each structural unit can be obtained by polymerizing by a known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN).
The component (A′-1) is preferably 30000 or less, preferably 20000 or less, and preferably 12000 or less, in terms of mass average molecular weight (polystyrene-converted mass average molecular weight by gel permeation chromatography, the same shall apply hereinafter). Further preferred. The lower limit may be more than 2000, and is preferably 4000 or more, and more preferably 5000 or more in terms of suppressing pattern collapse and improving resolution.

[(A′-2) component]
The component (A′-2) has a molecular weight of 500 or more and 2,000 or less, has a hydrophilic group, and has an acid dissociable, dissolution inhibiting group X as exemplified in the description of the component (A-1) or A low molecular compound having X ′ is preferred. Specific examples include those obtained by substituting a part of the hydrogen atoms of the hydroxyl group of the compound having a plurality of phenol skeletons with the acid dissociable, dissolution inhibiting group X or X ′.
The component (A′-2) is, for example, a part of the hydrogen atom of the hydroxyl group of a low molecular weight phenol compound known as a sensitizer or heat resistance improver for non-chemically amplified g-line or i-line resists. Those substituted with an acid dissociable, dissolution inhibiting group are preferred, and any of them can be used arbitrarily.
Examples of such low molecular weight phenol compounds include the following.
Bis (4-hydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2- (4-hydroxyphenyl) -2- (4′-hydroxyphenyl) propane, 2- (2,3,3) 4-trihydroxyphenyl) -2- (2 ′, 3 ′, 4′-trihydroxyphenyl) propane, tris (4-hydroxyphenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) -2- Hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4- Hydroxy-2,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4-hydroxy-3-methylphenol) Nyl) -3,4-dihydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) -3 , 4-dihydroxyphenylmethane, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene, phenol, m-cresol, p-cresol or xylenol And 2,3,4 nuclei of formalin condensates of phenols and the like. Of course, it is not limited to these.
The acid dissociable, dissolution inhibiting group is not particularly limited, and examples thereof include those described above.

<(B ′) component>
As the component (B ′), any conventionally known acid generator for chemically amplified resists can be appropriately selected and used. Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, poly (bissulfonyl) diazomethanes, and the like. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.

  Specific examples of the onium salt acid generator include diphenyliodonium trifluoromethanesulfonate, (4-methoxyphenyl) phenyliodonium trifluoromethanesulfonate, bis (p-tert-butylphenyl) iodonium trifluoromethanesulfonate, and triphenylsulfonium trifluoromethanesulfonate. (4-methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, (4-methylphenyl) diphenylsulfonium nonafluorobutanesulfonate, (p-tert-butylphenyl) diphenylsulfonium trifluoromethanesulfonate, diphenyliodonium nonafluorobutanesulfonate, bis (p -Tert-Butylphenyl) iodonium nonafluorobutans Honeto include triphenylsulfonium nonafluorobutanesulfonate. Of these, onium salts having a fluorinated alkyl sulfonate ion as an anion are preferable.

  Examples of oxime sulfonate compounds include α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -phenylacetonitrile, α -(Trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (methyl Sulfonyloxyimino) -p-bromophenylacetonitrile and the like. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

  Specific examples of the diazomethane acid generator include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (2, 4-dimethylphenylsulfonyl) diazomethane and the like.

As the component (B ′), one type of acid generator may be used alone, or two or more types may be used in combination.
(B ') The usage-amount of a component shall be 1-20 mass parts with respect to 100 mass parts of (A') component, Preferably it is 2-10 mass parts. By setting it to be equal to or higher than the lower limit value of the above range, pattern formation is sufficiently performed.

<Optional component>
In the chemically amplified resist composition, a nitrogen-containing organic compound (D ′) (hereinafter referred to as “(D ′) component”) is further added as an optional component in order to improve the pattern pattern shape, the stability over time. Can be blended.
Since a wide variety of components (D ′) have already been proposed, any known one may be used. However, amines, particularly secondary lower aliphatic amines and tertiary lower aliphatic amines, may be used. preferable.
Here, the lower aliphatic amine refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms. Examples of the secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, Tri-n-propylamine, tripentylamine, diethanolamine, triethanolamine, triisopropanolamine and the like can be mentioned, and tertiary alkanolamines such as triethanolamine and triisopropanolamine are particularly preferable.
These may be used alone or in combination of two or more.
The component (D ′) is usually used in the range of 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the component (A ′).

In addition, the chemically amplified resist composition further includes an organic carboxylic acid as an optional component for the purpose of preventing sensitivity deterioration due to the blending with the component (D ′) and improving the pattern shape, stability of placement, etc. Alternatively, phosphorus oxo acid or a derivative thereof (E ′) (hereinafter referred to as (E ′) component) can be contained. In addition, (D ') component and (E') component can also be used together, and any 1 type can also be used.
As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable.
The component (E ′) is usually used at a ratio of 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A ′).

  If desired, the chemically amplified resist composition may further contain miscible additives such as an additional resin for improving the performance of the coating film of the resist composition, a surfactant for improving the coating property, A dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent and the like can be appropriately contained.

The chemically amplified resist composition can be produced by dissolving the material in an organic solvent (S ′) (hereinafter referred to as (S ′) component).
As the component (S ′), any component can be used as long as it can dissolve each component to be used to form a uniform solution, and any one of conventionally known solvents for resist compositions can be used. Two or more types can be appropriately selected and used.
Specific examples include lactones such as γ-butyrolactone, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol. Polyhydric alcohols such as monoacetate, propylene glycol monomethyl ether acetate (PGMEA), dipropylene glycol, or monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate and derivatives thereof; , Cyclic ethers such as dioxane, methyl lactate, ethyl lactate (EL), vinegar Can methyl, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and the like esters such as ethyl ethoxypropionate. Among these, PGMEA, EL, and propylene glycol monomethyl ether (PGME) are preferable. These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.
The amount of the component (S ′) used is not particularly limited, but is used in such an amount that the chemically amplified resist composition becomes a liquid having a concentration that can be applied onto the support.

The method for forming the resist pattern on the support is not particularly limited, and a conventionally known method can be used. For example, it can be performed as follows.
First, the positive resist composition is applied onto a support with a spinner or the like, and pre-baked (post-apply bake (PAB)) for 40 to 120 seconds, preferably 60 to 90 seconds under a temperature condition of 80 to 150 ° C. After performing selective exposure using a commercially available exposure apparatus or the like, PEB (post-exposure heating) is applied for 40 to 120 seconds, preferably 60 to 90 seconds, at a temperature of 80 to 150 ° C. Next, this is developed using an alkali developer, for example, an aqueous solution of 0.1 to 10% by mass of tetramethylammonium hydroxide. In this way, a resist pattern can be obtained.
The support is not particularly limited, and a conventionally known one can be used, and examples thereof include a substrate for electronic components and a substrate on which a predetermined wiring pattern is formed. More specifically, a silicon substrate, a metal substrate such as copper, chromium, iron, and aluminum, a glass (quartz glass, etc.) substrate, and the like can be given. As a material for the wiring pattern, for example, copper, aluminum, nickel, gold or the like can be used. An inorganic and / or organic antireflection film may be provided on the substrate.
The wavelength used for the exposure is not particularly limited, and ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray, etc. Can be done using radiation. The present invention is particularly effective in applications for coating a resist pattern formed by a lithography method using an ArF excimer laser as an exposure light source.

[Test Example 1]
A resist film is formed on a silicon wafer substrate by using a commercially available positive resist composition for ArF excimer laser (product name: TArF-TS-H031, manufactured by Tokyo Ohka Kogyo Co., Ltd.). A contact hole (CH) having a height of 250 nm was formed with a dimension (hole inner diameter) of 160 nm as a target to obtain a resist pattern.
The silicon wafer substrate, 0.2 wt% PDDA solution (PDDA-Cl; polydiallyldimethylammonium chloride, Mw; 24 50,000) was immersed for 20 seconds, then, after cleaning the surface with pure water, blowing _{N 2} And dried. Then, it was immersed in 0.2 mass% PSS aqueous solution (PSS; polystyrene sulfonic acid, Mw; 70,000) for 20 seconds, and then the surface was washed with pure water and then sprayed with N ₂ and dried.
A series of operations (alternate contact treatment) from immersion in the PDDA aqueous solution to washing and drying after immersion in the PSS aqueous solution is set as one set, and the total number of times of this alternating contact treatment is set as shown in Table 1. And so on.
The “total number of times of setting” is the number of times of setting including the contact of the initial PDDA aqueous solution and PSS aqueous solution with the resist pattern. That is, for example, 5 sets means that the alternate contact treatment was further performed four times after the first immersion in the PSS aqueous solution.
After completion of the predetermined number of set operations, a baking process was performed at 110 ° C. for 60 seconds.

  As a control, the same treatment as described above was performed except that the resist pattern was not contacted with the PDDA aqueous solution and the PSS aqueous solution at all.

The dimension of CH of each resist pattern after processing was measured using a scanning electron microscope (SEM). The results are shown in Table 1.
As shown in this result, by performing 5 to 20 sets of alternating contact treatment, CH having a finer size than that of the control was formed. Further, there was almost no change in the height of the resist pattern, and from this result, it was confirmed that the coating film was formed mainly on the side wall portion of CH.
Furthermore, the larger the number of sets, the finer the dimension of CH. From this result, it was confirmed that the number of sets and the film thickness of the coating film were correlated.

[Test Example 2]
On a resist pattern of a contact hole (CH) having a size (hole inner diameter) of 160 nm and a height of 250 nm formed in the same manner as in Test Example 1, a 0.2 mass% PDDA aqueous solution (PDDA-Cl; polydiallyldimethylammonium chloride, Mw; 240,000) was applied uniformly with a spinner, allowed to stand for 20 seconds, then washed with pure water for 15 seconds, and then shaken and dried. Subsequently, a 0.2 mass% PSS aqueous solution (PSS; polystyrene sulfonic acid, Mw; 70,000) was uniformly applied with a spinner and then allowed to stand for 20 seconds, then washed with pure water for 15 seconds, and then shaken and dried. went.
A series of operations (alternate contact processing) from the application of the PDDA aqueous solution to the cleaning after the application of the PSS aqueous solution and the shake-off drying is set as one set, and the total number of times of the alternating contact processing is set as shown in Table 2. And so on.
After completion of the predetermined number of times of alternating contact processing, baking processing was performed at 110 ° C. for 60 seconds.

  As a control, the same treatment as described above was performed except that the resist pattern was not contacted with the PDDA aqueous solution and the PSS aqueous solution at all.

The CH dimension of each resist pattern after processing was measured using SEM. The results are shown in Table 2.
As shown in this result, by performing 1 to 5 sets of alternating contact treatment, CH with finer dimensions was formed as compared with the control. Further, there was almost no change in the height of the resist pattern, and from this result, it was confirmed that the coating film was formed mainly on the side wall portion of CH.
Furthermore, the larger the number of sets, the finer the dimension of CH. From this result, it was confirmed that the number of sets and the film thickness of the coating film were correlated.

[Test Example 3]
A silicon wafer substrate on which a contact hole (CH) resist pattern having a dimension (hole inner diameter) of 160 nm and a height of 250 nm was formed in the same manner as in Test Example 1 was added to a 0.3 mass% PDDA aqueous solution (PDDA-Cl; polydiallyldimethyl). Ammonium chloride, Mw; 400,000) was immersed for 20 seconds, and then the surface was washed with pure water and then dried by spraying N ₂ . Then, it was immersed in 0.3 mass% PSS aqueous solution (PSS; polystyrene sulfonic acid, Mw; 1 million) for 20 seconds, and then the surface was washed with pure water, and then N ₂ was sprayed and dried.
A series of operations (alternative contact treatment) from immersion in the PDDA aqueous solution to washing and drying after immersion in the PSS aqueous solution is set as one set, and the total number of times of this alternating contact treatment is set as shown in Table 3. And so on.
After completion of the predetermined number of times of alternating contact processing, baking processing was performed at 110 ° C. for 60 seconds.

  As a control, the same treatment as described above was performed except that the resist pattern was not contacted with the PDDA aqueous solution and the PSS aqueous solution at all.

The CH dimension of each resist pattern after processing was measured using SEM. The results are shown in Table 3.
As shown in this result, by performing 1 to 10 sets of alternating contact treatment, CH having a finer dimension than that of the control was formed. Further, there was almost no change in the height of the resist pattern, and from this result, it was confirmed that the coating film was formed mainly on the side wall portion of CH.
Furthermore, the larger the number of sets, the finer the dimension of CH. From this result, it was confirmed that the number of sets and the film thickness of the coating film were correlated.

[Test Example 4]
On a resist pattern having a contact hole (CH) having a size (hole inner diameter) of 160 nm and a height of 250 nm formed in the same manner as in Test Example 1, a 0.3 mass% PDDA aqueous solution (PDDA-Cl; polydiallyldimethylammonium chloride, Mw; 400,000) was applied uniformly with a spinner, allowed to stand for 20 seconds, then washed with pure water for 15 seconds, and then shaken and dried. Subsequently, a 0.3 mass% PSS aqueous solution (PSS; polystyrene sulfonic acid, Mw; 1,000,000) was uniformly applied with a spinner and then allowed to stand for 20 seconds, then washed with pure water for 15 seconds, and then shaken and dried. went.
A series of operations (alternate contact treatment) from application of the PDDA aqueous solution to cleaning after application of the PSS aqueous solution and shaking-off drying is set as one set, and the total number of times of this alternating contact treatment is set as shown in Table 3. And so on.
After completion of the predetermined number of times of alternating contact processing, baking processing was performed at 110 ° C. for 60 seconds.

  As a control, the same treatment as described above was performed except that the resist pattern was not contacted with the PDDA aqueous solution and the PSS aqueous solution at all.

The CH dimension of each resist pattern after processing was measured using SEM. The results are shown in Table 4.
As shown in this result, by performing 1 to 5 sets of alternating contact treatment, CH with finer dimensions was formed as compared with the control. Further, there was almost no change in the height of the resist pattern, and from this result, it was confirmed that the coating film was formed mainly on the side wall portion of CH.
Furthermore, the larger the number of sets, the finer the dimension of CH. From this result, it was confirmed that the number of sets and the film thickness of the coating film were correlated.

[Test Example 5]
In Test Example 3, the concentrations of the PDDA aqueous solution and the PSS aqueous solution were changed to 0.1 mass%, 0.2 mass%, and 0.5 mass%, respectively, and the immersion time in each aqueous solution was 10 seconds, 20 seconds, 30 seconds, respectively. Change to the second or 60 seconds, and the series of operations (alternate contact treatment) from immersion in the PDDA aqueous solution to cleaning and drying after immersion in the PSS aqueous solution so that the total number of times set is as shown in Table 5. Repeatedly.
The CH dimension of each resist pattern after processing was measured using SEM. The results are shown in Table 5. From these results, the film thickness of the coating film formed on the resist pattern surface mainly depends on the set number of alternating contact treatments, is hardly affected by the immersion time, and the PDDA aqueous solution and the PSS aqueous solution It was confirmed that there was little influence of the concentration, and in particular, it was hardly influenced at a low concentration of 0.2% by mass or less.

[Test Example 6]
A resist film is formed on a silicon wafer substrate using a commercially available positive resist composition for ArF excimer laser (product name: TArF-P6071, manufactured by Tokyo Ohka Kogyo Co., Ltd.). A rectangular line structure having a height of 120 nm and a height of 280 nm was formed.
The silicon wafer substrate, 0.2 wt% PDDA solution (PDDA-Cl; polydiallyldimethylammonium chloride, Mw; 24 50,000) was immersed for 20 seconds, then, after cleaning the surface with pure water, blowing _{N 2} And dried. Then, it was immersed in 0.2 mass% PSS aqueous solution (PSS; polystyrene sulfonic acid, Mw; 70,000) for 20 seconds, and then the surface was washed with pure water and then sprayed with N ₂ and dried.
A series of operations (alternate contact treatment) from immersion in the PDDA aqueous solution to washing and drying after immersion in the PSS aqueous solution is taken as one set, and the total number of times of this alternating contact treatment is set as shown in Table 6. And so on.
After completion of the predetermined number of set operations, a baking process was performed at 110 ° C. for 60 seconds.

  As a control, the same treatment as described above was performed except that the resist pattern was not contacted with the PDDA aqueous solution and the PSS aqueous solution at all.

The dimension (line width of the rectangular line structure) of each resist pattern after processing was measured using a scanning electron microscope (SEM). The results are shown in Table 6.
Subsequently, the pattern formed with the organic thin film is etched with a CF ₄ / CHF ₃ / Ar mixed gas (gas flow rate 40/40/160 sccm, pressure 40 Pa, power 300 W, processing time 100 seconds) using an RIE apparatus. Went.
From the difference in resist film thickness before and after the etching treatment, the etching rate (nm / second) of each sample was determined. The results are shown in Table 6.
As is clear from this result, the etching rate was slower than the control in any sample on which the resist pattern coating film was formed, and it was confirmed that the etching resistance was improved.

As shown in the above results, according to the present invention, an organic coating film can be formed on the resist pattern surface, particularly on the sidewall surface of the resist pattern. Moreover, a fine pattern can be formed by increasing the film thickness of the coating film.
Further, by forming the coating film, the etching resistance of the resist pattern is improved as compared with the case where the coating film is not coated.
Further, since a coating film can be formed on the resist pattern side wall surface, an effect of improving LER can be expected.

[Test Example 7]
As the water-soluble resin (A1), PDDA-Br (polydiallyldimethylammonium bromide, Mw: 400,000), or P2VMP (poly-2-vinyl-1-methylpyridinium bromide), Mw: 50000), or P4VMP (poly-4- Vinyl-1-methylpyridinium bromide, Mw: 50000) or PMEA (poly-2-methacryloxyethyltrimethylammonium bromide, Mw: 50000) was used as the water-soluble resin (A2), and PSS (polystyrene sulfonic acid, Mw: 100). Or PMA (polymaleic acid, Mw: 800-1200), or PMAA (polymaleic acid ammonium salt, Mw: 15000), or PSS-PDHD (polystyrenesulfonic acid and poly (2,3-dihydrothieno) Using 3, 4-b-1,4-dioxin)) mixed resin (Aldrich)), the following tests were performed using these in combination shown in Table 7.

In the same manner as in Test Example 1, a resist pattern of contact holes (CH) having a dimension (hole inner diameter) of 160 nm and a height of 227 nm was formed on a silicon wafer substrate.
The substrate was immersed in a 0.5 mass% aqueous solution (cationic polymer aqueous solution) of the water-soluble resin (A1) shown in Table 7 for 20 seconds, immersed and washed with pure water for 20 seconds, and then dried by blowing nitrogen gas. went. Subsequently, after being immersed in a 0.5% by mass aqueous solution (anionic polymer aqueous solution) of the water-soluble resin (A2) shown in Table 7 for 20 seconds and immersed in pure water for 20 seconds, drying was performed by blowing nitrogen gas. It was.
A series of operations (alternate contact treatment) from application of the cationic polymer aqueous solution to washing after application of the anionic polymer aqueous solution and drying by blowing nitrogen gas is set as one set. The total number of sets was set to 10 times.
The cross section of each resist pattern after the treatment was observed and measured using SEM, and the height of the pattern cross section was measured. The results are shown in Table 7.
As a result, when the alternating contact process was not performed at all (control), the pattern height was 227 nm. However, when the alternating contact process was performed, the pattern height increased in any case. It was. Moreover, in any case, CH having a finer size was formed as compared with the control. From these results, it was confirmed that a uniform organic thin film was formed on the resist pattern surface in any case.

Subsequently, an etching process using a CF ₄ / CHF ₃ / Ar mixed gas (gas flow rate 40/40/160 sccm, pressure 40 Pa, power 300 W, process) is performed on the resist pattern having the organic thin film formed on the surface using an RIE apparatus. Time 100 seconds). In addition, as a control, the same etching treatment as described above was performed on the resist pattern that was not contacted with the cationic polymer aqueous solution and the anionic polymer aqueous solution at all.
From the difference in resist film thickness before and after the etching treatment, the etching rate (nm / second) of each sample was determined. The results are shown in Table 8. The numerical unit in the table is nm / second.

  When the organic thin film is not coated, the etching rate is 0.8 nm / second, and from these results, the organic thin film coating has an etching resistance equal to or higher than that when the organic thin film is not coated. It was confirmed that it was obtained.

Claims (6)

A resist pattern coating film forming material for forming a coating film on the resist pattern surface,
A first aqueous solution containing a water-soluble resin (A1) having a positively charged site in the aqueous solution and a second aqueous solution containing a water-soluble resin (A2) having a negatively charged site in the aqueous solution A resist pattern coating film forming material comprising:   The material for forming a resist pattern coating film according to claim 1, wherein the water-soluble resin (A1) is a resin having a structural unit derived from a diallyldialkylammonium salt.   The material for forming a resist pattern coating film according to claim 1 or 2, wherein the water-soluble resin (A2) is a resin having a structural unit derived from styrenesulfonic acid or a salt thereof. A resist pattern coating film forming method for forming a coating film on a resist pattern surface formed on a support using the resist pattern coating film forming material according to claim 1. There,
A resist pattern coating film forming method, comprising: bringing the first aqueous solution into contact with the resist pattern surface; and bringing the second aqueous solution into contact with the resist pattern surface after contacting the first aqueous solution .   5. The resist pattern coating film forming method according to claim 4, further comprising a step of alternately bringing the first aqueous solution and the second aqueous solution into contact with the resist pattern surface after the step of bringing the second aqueous solution into contact with each other. .   The resist pattern coating film forming method according to claim 4, further comprising a step of cleaning the resist pattern surface after contacting the first aqueous solution or the second aqueous solution.