JP2008203536A - Surface treating agent for pattern formation and pattern forming method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treating agent for a freezing process by which when a first resist pattern is formed on a first resist film, a second resist film is formed on the first resist pattern and in order to form a second resist pattern, the first resist pattern is chemically treated to change properties so that it is not dissolved in a second resist liquid, wherein the surface treating agent is used for chemically treating the first resist pattern so as to satisfy the requirements that the first resist pattern does not dissolve in the second resist liquid, the dimensions of the first resist pattern undergo no change, and the first and second resist patterns have the same dry etching resistance, and a pattern forming method using the surface treating agent. <P>SOLUTION: The surface treating agent for pattern formation contains a polyhydric alcohol compound. The pattern forming method using the surface treating agent is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a surface treatment agent for forming a resist pattern used in a semiconductor manufacturing process such as an IC, a circuit board such as a liquid crystal or a thermal head, and a lithography process for other photo applications, and pattern formation using the same. It is about the method.
In particular, the present invention relates to a surface treatment agent for forming a resist pattern suitable for exposure with an immersion type projection exposure apparatus that uses far ultraviolet light having a wavelength of 200 nm or less as a light source, and a pattern forming method using the same.

  Since the resist for KrF excimer laser (248 nm), an image forming method called chemical amplification has been used as an image forming method for a resist in order to compensate for sensitivity reduction due to light absorption. An example of a positive-type chemical amplification image forming method will be described. When exposed, the acid generator in the exposed area decomposes to generate an acid, and the acid generated in the exposure bake (PEB) is a reaction catalyst. Is used to change an alkali-insoluble group to an alkali-soluble group, and an exposed portion is removed by alkali development.

With the miniaturization of semiconductor elements, the wavelength of an exposure light source has been shortened and the projection lens has a high numerical aperture (high NA). Currently, an exposure machine using an ArF excimer laser having a 193 nm wavelength as a light source has been developed. The degree of achievement of miniaturization of a semiconductor element can be expressed by resolving power, and can be expressed by the following equation as is generally well known.
(Resolving power) = k ₁ · (λ / NA)
Here, λ is the wavelength of the exposure light source, NA is the numerical aperture of the projection lens, and k ₁ is a coefficient related to the process.

As a technique for increasing the resolving power, a so-called immersion method in which a high refractive index liquid (hereinafter also referred to as “immersion liquid”) is filled between the projection lens and the sample has been proposed.
This “immersion effect” means that when λ ₀ is the wavelength of the exposure light in the air, n is the refractive index of the immersion liquid with respect to air, θ is the convergence angle of the light beam, and NA ₀ = sin θ. The above-described resolving power and depth of focus can be expressed by the following equations.
(Resolving power) = k ₁ · (λ ₀ / n) / NA ₀
That is, the immersion effect is equivalent to using an exposure wavelength having a wavelength of 1 / n. In other words, in the case of a projection optical system with the same NA, the depth of focus can be increased n times by immersion.
Further, as a technique for increasing the resolution, a pattern forming method using a special process has been proposed. This is equivalent to decreasing k ₁ in the above-described resolving power equation. One of them is a freezing process (Patent Document 1, Non-Patent Document 1).

  The freezing process is, for example, as described in Patent Document 1, in which a first resist pattern is formed on a first resist film, and a second resist film is formed on the first resist pattern. In the step of forming the second resist pattern, the first resist pattern is not dissolved in the second resist solution or mixed with the second resist film when forming the second resist film. It refers to a process for changing the properties of one resist pattern by chemical or physical treatment. By using this technique, it is possible to form a desired resist pattern by dividing it twice, and it is possible to realize double resolution as compared with a normal exposure process. Here, the first and second are the order of steps for forming the first and second layers as shown in FIG.

As a known example of the freezing process, Patent Document 1 described above can be cited. In this example, after forming the first resist pattern, the first resist pattern is irradiated with vacuum ultraviolet rays, and the first resist pattern is used as the second resist pattern. The properties of the first resist pattern are changed so as not to dissolve in the liquid. In this method, it is clearly shown in this known example that the dimension of the first resist pattern changes before and after the irradiation with vacuum ultraviolet rays. A measure is taken by correcting the dimension of one resist pattern. However, the amount of dimensional variation is expected to vary depending on the size of the resist pattern, and it is practically impossible to design a dimensional-corrected mask for an actual semiconductor device pattern in which patterns of various sizes and shapes exist. It is. Therefore, basic characteristics required for the freezing process include (i) that the first resist pattern does not dissolve in the second resist solution, and (ii) the first resist before and after the property change of the first resist pattern. It is necessary to make it compatible that the dimension of the pattern does not change. Further, normally, in the manufacturing process of a semiconductor circuit, the resist pattern is used to transfer the pattern onto the substrate by etching using itself as a mask. At this time, it is required that all resist patterns have the same etching resistance in an arbitrary pattern. Accordingly, in the freezing process, (iii) the first resist pattern and the second resist pattern are required to have the same dry etching resistance, but materials and processes that satisfy all these three characteristics have not yet been found. It has not been issued.

JP 2005-197349 A J. Vac. Sci. Technol. B 4, 426 (1986)

  The present invention has been made in view of the above circumstances, and after forming a first resist pattern on a first resist film, a second resist film is formed on the first resist pattern. In the freezing process in which the first resist pattern is chemically treated to change its properties so as not to be dissolved in the second resist solution in order to form the resist pattern, (i) the first resist pattern Does not dissolve in the second resist solution, and (ii) the dimension of the first resist pattern does not change. Furthermore, (iii) the first resist pattern and the second resist pattern have the same dry etching resistance. A surface treatment agent for a freezing process for chemically treating the first resist pattern so as to satisfy all the requirements of the Providing a pattern forming method.

The above problem has been solved by the following configuration.
(1) The surface used in the previous step of forming the second resist pattern by forming the second resist film on the first resist pattern after forming the first resist pattern on the first resist film A surface treatment agent for pattern formation, comprising a polyhydric alcohol compound as the surface treatment agent.
(2) The polyhydric alcohol compound is at least one compound selected from a derivative of an aliphatic hydrocarbon compound having at least two alcoholic hydroxyl groups, a derivative of an aliphatic cyclic hydrocarbon compound, or an aromatic compound derivative. The surface treatment agent for pattern formation as described in (1) above, wherein

(3) The surface treatment agent for pattern formation according to any one of (1) to (2), further comprising an organic solvent.
(4) The first resist pattern is surface-treated with the surface treatment agent for pattern formation according to any one of (1) to (3), and then the first resist pattern is subjected to surface treatment on the first resist pattern. A pattern forming method comprising forming a second resist film and forming a second resist pattern.

  According to the present invention, the first resist pattern is formed on the first resist film, and then the second resist film is formed on the first resist pattern to form the second resist pattern. In the freezing process in which the resist pattern is chemically or physically treated to change its properties so that it does not dissolve in the second resist solution, (i) the first resist pattern dissolves in the second resist solution And (ii) the dimension of the first resist pattern does not change, and (iii) satisfies all the requirements that the first resist pattern and the second resist pattern have the same dry etching resistance. Provided is a surface treatment agent for a freezing process for performing chemical or physical treatment on the first resist pattern, and further improves productivity. It is possible to form a fine pattern.

Hereinafter, the present invention will be described in detail.
In the present specification, the first resist and the second resist are a resist composition for forming a first resist layer that is first formed in a pattern forming process described later, and thereafter It is a term used to distinguish the resist composition for forming the second resist layer to be formed for convenience.
In addition, in the description of the group (atomic group) in this specification, the description that does not indicate substitution and non-substitution includes those that have no substituent and those that have a substituent. . For example, the “alkyl group” includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).

The surface treatment agent for pattern formation of the present invention (hereinafter also simply referred to as “treatment agent”) is formed on the first resist pattern after the first resist pattern is formed on the first resist film. A processing agent used in a pre-process for forming a resist film and forming a second resist pattern, which contains a polyhydric alcohol.
Any polyhydric alcohol may be used as long as it acts on the surface of the first resist pattern and can cause an acid-catalyzed esterification reaction of the alcohol, and preferably has at least two or more alcoholic hydroxyl groups. It is a derivative of an aliphatic hydrocarbon compound, a derivative of an aliphatic cyclic hydrocarbon compound, or an aromatic compound derivative.

The polyhydric alcohol preferably does not contain other polar groups other than alcoholic hydroxyl groups in the molecule. Examples of polar groups that are preferably not included include divalent groups having a hetero atom, such as ether groups, thioether groups, ester groups, amide groups, sulfonamide groups, carbonyl groups, carboxyl groups, and the like. Can do.
The polyhydric alcohol is preferably a divalent to octavalent alcohol, and more preferably a divalent to tetravalent alcohol. That is, from the viewpoint of reducing remaining unreacted alcoholic hydroxyl groups, the valence of the polyhydric alcohol is preferably 8 or less, and more preferably 4 or less.
The molecular weight of the polyhydric alcohol is generally 50 to 1000, preferably 50 to 700, more preferably 100 to 500. That is, the molecular weight is preferably 700 or less, more preferably 500 or less, from the viewpoint of suppressing the increase in size of the first resist pattern. Further, the molecular weight is preferably 100 or more from the viewpoint of inhibiting dissolution of the first resist pattern.

Examples of the aliphatic hydrocarbon compound having at least two alcoholic hydroxyl groups include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, , 2-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-tridecanediol, 1,15-hexadecanediol, polyethylene glycol, polyoxypropylene glycol, Examples thereof include polyoxypropylene-polyoxyethylene glycol, glycerin, trimethylolpropane, 1,2,8-octanetriol, pentaerythritol, sorbitol, mannitol and the like.

  Examples of the aliphatic cyclic hydrocarbon compound having at least two alcoholic hydroxyl groups include cyclohexane-1,2-diol, cyclohexane-1,4-diol, 1,3-adamantanediol, 1,5-adamantanediol, , 5-dihydroxymethyl-adamantane, 1,5-dihydroxyethyl-adamantane, 1,3,5-adamantanetriol, bicyclo [2,2,1] heptane-2,3-diol, 2,3-norbornanediol, 2, , 5-norbornanediol, 2,6-norbornanediol, pinanediol, sucrose, galactose, glucose and the like.

  Examples of the aromatic hydrocarbon compound having at least two alcoholic hydroxyl groups include (1,2-dihydroxymethyl) benzene, (1,3-dihydroxymethyl) benzene, (1,2-dihydroxymethyl) naphthalene, (1 , 2-dihydroxymethyl) anthracene, (3,4-dihydroxyphenyl) methanol, 1,2-diphenylethane-1,2-diol, 1,1,2,2-tetraphenylethane-1,2-diol, , 3-naphthalenediethanol, 1,2-dihydroxybenzene and the like.

Among these, from the viewpoint of suppressing dissolution in the second resist solution, part or all of the hydrocarbon groups of the polyhydric alcohol may be fluorinated. For example, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octanediol, 2,2,3,3,4,4,5,5 6,6,7,7,8,8-tridecafluoro-1,9-nonanediol, 1,2-dihydroxy-perfluorodecalin, 1,2-dihydroxy-perfluorocyclohexane, 3,3,4,4 -Tetrafluoro-1,6-hexanediol or the like can be used.
However, the present invention is not limited to these compounds.

In this invention, the usage-amount of a polyhydric alcohol is generally 1-100 mass% with respect to the whole quantity of a processing agent, Preferably it is 5-95 mass%, More preferably, it is 10-90 mass%. In order to obtain a sufficient effect, the content is preferably 1% by mass or more, more preferably 5% by mass or more.
These polyhydric alcohols may be used alone or in combination of two or more.

As a general synthesis method of the polyhydric alcohol of the present invention, JP-A-60-152431, JP-A-62-222040, JP-A-1-85939, JP-A-5-301828, JP-A-5-301828, The methods exemplified in JP-A-6-25040 and JP-A-11-343254 can be used.
Moreover, a commercial item can also be used as it is, and in that case, it can be purchased from Sigma Aldrich Co., Ltd., Wako Pure Chemical Industries, Ltd., Tokyo Chemical Industry Co., Ltd., Daikin Industries, Ltd., etc.

  Furthermore, the treatment agent of the present invention preferably contains an organic solvent other than the polyhydric alcohol in order to control the solubility of the first resist pattern. As such an organic solvent, any solvent that does not dissolve the first resist pattern and dissolves the polyhydric alcohol can be used. Here, when the first resist pattern is not dissolved, a line-and-space pattern with a film thickness of 0.2 μm and 200 nm is formed under the condition of 23 ° C., and the pattern dimensions are measured when the pattern is immersed in an organic solvent for 1 minute. It shows that the variation and the variation in the height of the pattern are both within ± 1%. Examples of such solvents include alcohol solvents, fluorine solvents, saturated hydrocarbon solvents, and the like. Among these, monohydric alcohol is preferable from the viewpoints of environmental safety, storage stability, and safety to the human body. In particular, a secondary or tertiary monohydric alcohol is more preferable from the viewpoint of not inhibiting the reaction between the polyhydric alcohol in the treating agent and the first resist pattern. These can be used alone or in combination.

  Specific examples of the alcohol solvent include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, tert-pentyl alcohol, and n-hexyl alcohol. N-heptyl alcohol, 2-heptyl alcohol, n-octyl alcohol, n-decanol, 3-methyl-3-pentanol, 2,3-dimethyl-2-pentanol, 4-phenyl-2-methyl-2- Examples include hexanol, 1-phenyl-2-methyl-2-propanol, s-amyl alcohol, t-amyl alcohol, isoamyl alcohol, 2-ethyl-1-butanol. In particular, isopropyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, tert-pentyl alcohol, 2-heptyl alcohol, 3-methyl-3-pentanol, 2,3-dimethyl-2-pentanol, 4 -Phenyl-2-methyl-2-hexanol and 1-phenyl-2-methyl-2-propanol are preferred. Among them, isopropyl alcohol, isobutyl alcohol, tert-butyl alcohol, tert-pentyl alcohol, 3-methyl-3-pentanol, 2,3-dimethyl-2-pentanol, 4-phenyl-2-methyl-2-hexanol, 1-phenyl-2-methyl-2-propanol is preferred.

  Any fluorine-based solvent may be used as long as a part or all of the hydrocarbon moiety in the solvent is substituted with a fluorine atom. From the viewpoint of solvent volatility, Is an alkane having 5 or more, a cycloalkane having 5 or more carbon, an alcohol having 5 or more carbon, a ketone having 5 or more carbon, an ether having 5 or more carbon, or an ester having 5 or more carbon. And a solvent in which some or all of the hydrogen atoms are substituted with fluorine atoms. More preferably, it is a solvent in which some or all of hydrogen atoms of hydrocarbons of alkanes having 7 or more carbon atoms, cycloalkanes having 7 or more carbon atoms, or alcohols having 7 or more carbon atoms are substituted with fluorine atoms. . These fluorine-based solvents include perfluoro-2-butyltetrahydrofuran, perfluorotetrahydrofuran, perfluorohexane, perfluoroheptane, perfluoromethylcyclohexanone, perfluoro-1-heptanol, perfluorotetrapentylamine, perfluorotetrahexylamine. Etc. can be used. These organic solvents can be used alone or in combination.

  Although it does not specifically limit as a saturated hydrocarbon type solvent, From a volatile viewpoint of a solvent, a C5-C or more compound is preferable, More preferably, a C7 or more compound is mentioned. Specific examples of the saturated hydrocarbon solvent include pentane, 2-methylbutane, 3-methylpentane, hexane, 2,2-dimethylbutane, 2,3-dimethylbutane, heptane, octane, 2,2,4-trimethylpentane, Examples include 2,2,3-trimethylhexane, decane, undecane, dodecane, 2,2,4,6,6-pentamethylheptane, tridecane, tetradecane, and hexadecane. These organic solvents can be used alone or in combination.

  As long as the organic solvent does not dissolve the first resist pattern and dissolves the treatment agent made of a polyhydric alcohol compound, an organic solvent other than an alcohol solvent, a fluorine solvent, a saturated hydrocarbon solvent, or the like may be used. However, it is preferable to use these solvents in an amount of 80% by mass or more, preferably 100% by mass.

As the other organic solvent, any one or more of ester, ether, ketone, amide, aromatic hydrocarbon and cyclic ketone can be appropriately selected and used. For example, esters such as ethyl lactate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, dimethyl glycol monoacetate monomethyl ether, monoethyl ether, or mono Examples thereof include ethers such as phenyl ether and derivatives thereof, and ketones such as acetone, methyl ethyl ketone, cyclohexanone, and 2-heptanone.

  The amount of the organic solvent used is not particularly limited as long as it dissolves the polyhydric alcohol compound of the present invention, but is usually 0 to 99 mass%, preferably 5 to 95 mass%, more preferably 10 to 10 mass% with respect to the polyhydric alcohol compound. 90% by mass.

Furthermore, in order to accelerate the reaction with the first resist pattern, the treating agent of the present invention may contain an acid or a compound that generates an acid by heating, if necessary.
As the acid to be added, a low molecular acid such as carboxylic acid or sulfonic acid can be used. Preferably, a low molecular weight such as carboxylic acid partially fluorinated or sulfonic acid partially fluorinated. Examples include acids. Specific examples include trifluorobutanesulfonic acid, heptafluoropropanesulfonic acid, perfluorobenzenesulfonic acid, and the like.
As a compound that generates an acid by heating, various compounds known in this field can be used. Examples thereof include known compounds such as sulfonium salt type compounds, anilinium salt type compounds, pyridinium salt type compounds, phosphonium salt type compounds, iodonium salt type compounds. Examples of the counter anion of these onium salt compounds include SbF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , PF ₆ ⁻ , toluenesulfonate, and triflate. The temperature for generating the acid is usually 200 ° C. or lower, preferably 160 ° C. or lower.
The addition amount of the acid or the compound that generates acid by heating is generally 0.01 to 20% by mass, preferably 0.1 to 10% by mass, based on the total amount of the treatment agent.

Moreover, it is preferable that the processing agent of this invention contains various surfactant. As the surfactant, various surfactants known in the art can be used. For example, ionic or nonionic fluorine-based and / or silicon-based surfactants can be used. Examples of these fluorine and / or silicon surfactants include, for example, JP-A No. 62-36663, JP-A No. 61-226746, JP-A No. 61-226745, JP-A No. 62-170950, JP 63-34540 A, JP 7-230165 A, JP 8-62834 A, JP 9-54432 A, JP 9-5988 A, US Pat. No. 5,405,720, etc. The surfactants described in US Pat. Nos. 5,360,692, 5,529,881, 5,296,330, 5,346,098, 5,576,143, 5,294,511, and 5,824,451 can be mentioned. The following commercially available surfactants can also be used as they are.
Examples of commercially available surfactants that can be used include F-top EF301, EF303 (manufactured by Shin-Akita Kasei Co., Ltd.), Florard FC430, 431, 4430 (manufactured by Sumitomo 3M Co., Ltd.), MegaFuck F171, F176, F189, R08. (Manufactured by Dainippon Ink & Chemicals, Inc.), Surflon S-382, SC101, 102, 103 (manufactured by Asahi Glass Co., Ltd.), Troisol S-366 (manufactured by Troy Chemical Co., Ltd.), PF6320, PF6520 (manufactured by OMNOVA) ) And the like, and silicon surfactants.
In addition to the known surfactants described above, the surfactant is derived from a fluoroaliphatic compound produced by a telomerization method (also called telomer method) or an oligomerization method (also called oligomer method). A surfactant using a polymer having a fluoroaliphatic group can be used. The fluoroaliphatic compound can be synthesized by the method described in JP-A-2002-90991.
In the present invention, other surfactants other than fluorine-based and / or silicon-based surfactants can also be used.
These surfactants may be used alone or in several combinations.
The amount of the surfactant used is preferably 0.0001 to 2% by mass, more preferably 0.001 to 1% by mass, based on the total amount of the processing agent.
By adding a surfactant to the treatment agent, the coating property when applying the treatment agent is improved.

  If necessary, the treatment agent may further contain a photoacid generator, a photosensitizer, a freezing reaction accelerator other than the acid, a resin, and the like.

<First resist>
In the present invention, after the first resist pattern is formed on the first resist film, the acid-catalyzed esterification reaction between the treatment agent containing polyhydric alcohol and the first resist is controlled, and the first resist pattern It is important to change the properties so that is not dissolved in the second resist solution. Control of the esterification reaction can be achieved not only by changing the properties of the treatment agent, but also by changing the properties of the first resist and / or the process conditions when the treatment agent is applied.

  The first resist may be either a positive resist or a negative resist, but is preferably a positive resist for the purpose of improving the reactivity with the treatment agent. Here, the “positive resist” refers to a resist in which an exposed portion is dissolved in a developer, and the “negative resist” refers to a resist in which a non-exposed portion is dissolved in a developer. Positive resists use chemical reactions such as polarity conversion to increase the solubility of exposed areas in the developer. On the other hand, negative resists generate intermolecular bonds such as cross-linking reactions and polymerization reactions. We are using.

The positive resist preferably contains a resin (A) that is decomposed by the action of an acid and increases the solubility in an alkaline developer, and a compound that generates an acid upon irradiation with actinic rays or radiation.
As the resin (A), the first resist pattern is used in order to cause esterification reaction with a treatment agent containing a polyhydric alcohol and to change the properties so that the first resist pattern is not dissolved in the second resist solution. It is preferable that a carboxylic acid is generated by a chemical reaction during the process of forming. Resin containing carboxylic acid may be contained in the first resist in advance before pattern formation.

The resin (A) contained in the first resist pattern preferably has a group (hereinafter also referred to as “acid-decomposable group”) that is decomposed by the action of an acid to increase the solubility in an alkaline developer.
The acid-decomposable group is preferably a group in which the hydrogen atom of the carboxyl group is protected by a group capable of leaving by the action of an acid, but may contain other groups at the same time. Examples of the group included at the same time include a group in which a hydrogen atom of an alkali-soluble group such as a hydroxyl group, a sulfonic acid group, or a thiol group is protected with a group capable of leaving by the action of an acid.
The group leaving by the action of an acid is preferably a group having a monocyclic or polycyclic alicyclic hydrocarbon structure. As groups capable of leaving by the action of these acids, various groups known in this field can be used, and groups exemplified in JP2007-17889A, JP2006-215526A, JP2006-349996A, and the like. Etc.

The resin (A) preferably further contains a resin having a carboxylic acid structure. As the group having a carboxylic acid structure, any group having a carboxylic acid structure can be used.

  The resin (A) preferably further has a repeating unit having a group having a lactone structure. As the group having a lactone structure, any group having a lactone structure can be used, but a group having a 5- to 7-membered ring lactone structure is preferable. A structure in which another ring structure is condensed to form a structure or a spiro structure is preferable. As these lactone groups, various groups known in this field can be used, and groups exemplified in JP-A 2007-17889, JP-A 2006-215526, JP-A 2006-349996, and the like can be exemplified.

  Other specific repeating units include a repeating unit having a polar functional group such as a hydroxyl group, a cyano group, a carbonyl group, and an ester group in consideration of dry etching resistance and alkali solubility, monocyclic or polycyclic cyclic carbonization. Examples thereof include a repeating unit that is not decomposed by the action of an acid having a hydrogen structure, a repeating unit having a fluoroalkyl group, or a repeating unit having a plurality of these functional groups.

  Examples of the resin used for the resist 1 of the present invention are shown below by way of specific examples, but the present invention is not limited thereto.

The weight average molecular weight of the resin (A) is not particularly limited, but is preferably 1,000 to 200,000, more preferably 3,000 to 20,000, most preferably as a value converted to polystyrene by the GPC method. 5,000 to 15,000.
The degree of dispersion (molecular weight distribution) is usually 1 to 5, preferably 1 to 3, more preferably 1.2 to 3.0, particularly preferably 1.2 to 2.0. .

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

The positive resist contains a compound that generates an acid upon irradiation with actinic rays or radiation (also referred to as a photoacid generator). Examples of such photoacid generators include photoinitiators for photocationic polymerization, photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, actinic rays used in microresists, etc. Known compounds that generate an acid upon irradiation with radiation and mixtures thereof can be appropriately selected and used.
Examples include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.

Further, a group that generates an acid upon irradiation with these actinic rays or radiation, or a compound in which a compound is introduced into the main chain or side chain of the polymer, for example, US Pat. No. 3,849,137, German Patent No. 3914407. JP, 63-26653, JP, 55-164824, JP, 62-69263, JP, 63-146038, JP, 63-163452, JP, 62-153853, The compounds described in Japanese Utility Model Laid-Open No. 63-146029 can also be used.
Furthermore, compounds capable of generating an acid by light described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

A photo-acid generator can be used individually by 1 type or in combination of 2 or more types.
The content of the photoacid generator is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 to 7% by mass, based on the total solid content of the positive resist. .

The positive resist of the present invention preferably contains a basic compound in order to reduce the change in performance over time from exposure to heating.
As the basic compound, those known in the art can be arbitrarily used, but preferably, compounds having structures represented by the following formulas (A) to (E) can be exemplified.

In general formulas (A) to (E),
R ²⁰⁰ , R ²⁰¹ and R ²⁰² may be the same or different, and are a hydrogen atom, an alkyl group (preferably having 1 to 20 carbon atoms), a cycloalkyl group (preferably having 3 to 20 carbon atoms) or an aryl group (having a carbon number). 6-20), wherein R ²⁰¹ and R ²⁰² may combine with each other to form a ring.
R ²⁰³ , R ²⁰⁴ , R ²⁰⁵ and R ²⁰⁶ may be the same or different and each represents an alkyl group having 1 to 20 carbon atoms.

These basic compounds can be used alone or in combination of two or more.
The amount of the basic compound used is usually 0.001 to 10% by mass, preferably 0.01 to 5% by mass, based on the solid content of the positive resist.

The positive resist of the present invention preferably further contains a resin (B) having at least one of a fluorine atom and a silicon atom.
The fluorine atom or silicon atom in the resin (B) may be contained in the main chain of the resin or may be substituted with a side chain.
The resin (B) is preferably a resin having an alkyl group having a fluorine atom, a cycloalkyl group having a fluorine atom, or an aryl group having a fluorine atom as a partial structure having a fluorine atom.
When the resin (B) has a fluorine atom, the content of the fluorine atom is preferably 5 to 80% by mass and more preferably 10 to 80% by mass with respect to the molecular weight of the resin (B). Moreover, it is preferable that the repeating unit containing a fluorine atom is 10-100 mass% in resin (B), and it is more preferable that it is 30-100 mass%.

The resin (B) is preferably a resin having an alkylsilyl structure (preferably a trialkylsilyl group) or a cyclic siloxane structure as a partial structure having a silicon atom.
When the resin (B) has a silicon atom, the content of the silicon atom is preferably 2 to 50% by mass and more preferably 2 to 30% by mass with respect to the molecular weight of the resin (B). Moreover, it is preferable that it is 10-100 mass% in resin (B), and, as for the repeating unit containing a silicon atom, it is more preferable that it is 20-100 mass%.

Specific examples of the resin (B) are shown below, but the present invention is not limited thereto.
In the following (T-01) and (T-04), X represents a hydrogen atom or a methyl group.

The resin (B) is preferably stable to an acid and insoluble in an alkaline developer.
Resin (B) is decomposed by the action of (x) an alkali-soluble group, (y) an alkali (alkali developer), a group that increases the solubility in the alkali developer, and (z) an acid. From the viewpoint of the followability of the immersion liquid, it is preferable not to have a group that increases the solubility in the developer.
The total amount of repeating units having an alkali-soluble group in the resin (B) or a group whose solubility in a developer is increased by the action of an acid or alkali is preferably 20 with respect to all the repeating units constituting the resin (B). It is not more than mol%, more preferably 0 to 10 mol%, still more preferably 0 to 5 mol%.

  In addition, the resin (B) does not have a hydrophilic group such as an ionic bond or a (poly (oxyalkylene)) group unlike a surfactant generally used in a resist. When the resin (B) contains a hydrophilic polar group, the followability of immersion water tends to decrease, and therefore it is more preferable that the resin (B) does not have a polar group selected from a hydroxyl group, an alkylene glycol, and a sulfone group. . In addition, it is preferable not to have an ether group bonded to a carbon atom of the main chain through a linking group because hydrophilicity increases and immersion liquid followability deteriorates. On the other hand, an ether group directly bonded to a carbon atom of the main chain is preferable because a hydrophobic group may be expressed.

  The weight average molecular weight in terms of standard polystyrene of the resin (B) is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, still more preferably 2,000 to 15,000, and particularly preferably. Is 3,000 to 15,000.

  The resin (B) preferably has a residual monomer amount of 0 to 10% by mass, more preferably 0 to 5% by mass, and still more preferably 0 to 1% by mass. The molecular weight distribution (Mw / Mn, also referred to as dispersity) is preferably 1 to 5, more preferably 1 to 3, and still more preferably 1 in terms of resolution, resist shape, resist pattern sidewall, roughness, and the like. It is in the range of ~ 1.5.

The addition amount of the resin (B) in the positive resist composition is preferably 0.1 to 20% by mass, and preferably 0.1 to 10% by mass based on the total solid content of the resist composition. Is more preferable. Furthermore, it is preferable that it is 0.1-5 mass%, More preferably, it is 0.2-3.0 mass%, More preferably, it is 0.3-2.0 mass%.
Various commercially available products can be used as the resin (B), and the resin (B) can be synthesized according to a conventional method (for example, radical polymerization).

If necessary, the positive resist of the present invention may further include resins other than those mentioned above, acid-decomposable dissolution inhibiting compounds, dyes, plasticizers, photosensitizers, light absorbers, and compounds that promote solubility in a developer, etc. Can be contained.
The positive resist of the present invention is prepared by dissolving the above components in an arbitrary solvent. As the solvent, any of alcohols, ketones, ethers, esters, halogenated hydrocarbons, cyclic ketones, cyclic ethers and the like can be used. And a solvent having a boiling point of 130 ° C. or more. Specifically, cyclopentanone, γ-butyrolactone, cyclohexanone, ethyl lactate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, ethyl 3-ethoxypropionate, ethyl pyruvate, 2-ethoxyethyl acetate, acetic acid -2- (2-ethoxyethoxy) ethyl and propylene carbonate are mentioned.
The solvent is particularly preferably a mixed solvent of two or more containing propylene glycol monomethyl ether acetate.

<Second resist>
As the second resist used to form the second resist pattern, the same one as the first resist can be used, but the dry etching resistance of the first resist pattern and the second resist pattern is improved. From the viewpoint of making them the same, the resin used for the second resist is preferably substantially the same as the resin used for the first resist. Furthermore, in order to form a substantially identical pattern between the first resist and the second resist with respect to an actual semiconductor device mask in which patterns of various sizes and shapes exist, Most preferably, the second resist is made of the same resist.

The esterification reaction between the treatment agent containing polyhydric alcohol and the first resist can also be controlled by changing the process conditions when the treatment agent is applied.
Hereinafter, processes used for forming the first resist pattern, freezing by chemical treatment of the first resist pattern, and forming the second resist pattern will be described.

<Formation of first resist pattern>
In the present invention, the first resist composition is filtered and then applied to a predetermined support as follows. The filter used for filter filtration is preferably made of polytetrafluoroethylene, polyethylene, or nylon of 0.1 microns or less, more preferably 0.05 microns or less, and still more preferably 0.03 microns or less.

  For example, a resist film is formed by applying and drying a resist composition on a substrate (eg, silicon / silicon dioxide coating) used for manufacturing a precision integrated circuit element by an appropriate application method such as a spinner or a coater. .

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

[Dry exposure method]
The resist film is irradiated with actinic rays or radiation through a predetermined mask, preferably baked (heated), developed and rinsed. Thereby, a good pattern can be obtained.
Examples of the actinic ray or radiation include infrared light, visible light, ultraviolet light, far ultraviolet light, X-ray, electron beam, etc., preferably 250 nm or less, more preferably 220 nm or less, particularly preferably 1 to 1. Far-ultraviolet light having a wavelength of 200 nm, specifically, ArF excimer laser, F ₂ excimer laser, EUV (13 nm), and electron beam are preferable.

[Immersion exposure]
In immersion exposure, the resist film is exposed (immersion exposure) through immersion water through a mask or the like for pattern formation. For example, the exposure is performed in a state where the space between the resist film and the optical lens is filled with the immersion liquid. After exposure, the resist film is washed with an immersion liquid as necessary. Subsequently, preferably, spinning is performed to remove the immersion liquid. Examples of the actinic ray or radiation include infrared light, visible light, ultraviolet light, far ultraviolet light, X-ray, electron beam, etc., preferably 250 nm or less, more preferably 220 nm or less, particularly preferably 1 to 1. Far-ultraviolet light having a wavelength of 200 nm, specifically, ArF excimer laser, F ₂ excimer laser, EUV (13 nm), and electron beam are preferable.

The immersion liquid used for the immersion exposure will be described below.
The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient as small as possible so as to minimize distortion of the optical image projected onto the resist. In the case of an ArF excimer laser (wavelength: 193 nm), it is preferable to use water from the viewpoints of availability and ease of handling in addition to the above-described viewpoints.
Further, a medium having a refractive index of 1.5 or more can be used in that the refractive index can be further improved. This medium may be an aqueous solution or an organic solvent.

  When water is used as the immersion liquid, the surface tension of the water is reduced and the surface activity is increased, so that the resist layer on the wafer is not dissolved and the influence on the optical coating on the lower surface of the lens element can be ignored. An additive (liquid) may be added in a small proportion. The additive is preferably an aliphatic alcohol having a refractive index substantially equal to that of water, and specifically includes methyl alcohol, ethyl alcohol, isopropyl alcohol and the like.

An immersion liquid poorly soluble film (hereinafter also referred to as “top coat”) may be provided between the resist film and the immersion liquid so that the resist film is not directly brought into contact with the immersion liquid. The necessary functions for the top coat are suitability for application to the upper layer of the resist, radiation, especially transparency to 193 nm, and poor immersion liquid solubility. It is preferable that the top coat is not mixed with the resist and can be uniformly applied to the resist upper layer.
From the viewpoint of 193 nm transparency, the topcoat is preferably a polymer that does not contain an aromatic, and specifically, a hydrocarbon polymer, an acrylate polymer, a polymethacrylic acid, a polyacrylic acid, a polyvinyl ether, a silicon-containing polymer, And fluorine-containing polymers.

  When peeling the top coat, a developer may be used, or a separate release agent may be used. As the release agent, a solvent having a small penetration into the resist is preferable. It is preferable that the peeling process can be performed with an alkali developer in that the peeling process can be performed simultaneously with the resist development process. The top coat is preferably acidic from the viewpoint of peeling with an alkali developer, but may be neutral or alkaline from the viewpoint of non-intermixability with the resist.

  After the dry exposure and immersion exposure, preferably baking (heating) is performed, and development and rinsing are performed. Thereby, a good pattern can be obtained.

In the development step, an alkaline developer is used as follows. As an alkaline developer of the resist composition, inorganic hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia, primary amines such as ethylamine and n-propylamine, Secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide and the like Alkaline aqueous solutions such as quaternary ammonium salts, cyclic amines such as pyrrole and pihelidine can be used.
Furthermore, alcohols and surfactants can be added in appropriate amounts to the alkaline developer.
The alkali concentration of the alkali developer is usually from 0.1 to 20% by mass.
The pH of the alkali developer is usually from 10.0 to 15.0.

As the rinsing liquid, pure water can be used, and an appropriate amount of a surfactant can be added.
Further, after the development process or the rinsing process, a process of removing the developer or the rinsing liquid adhering to the pattern with a supercritical fluid can be performed.
Further, after the rinsing process or the supercritical fluid process, a heat treatment can be performed to remove moisture remaining in the pattern.

<Chemical treatment of the first resist pattern>
After forming the first resist pattern, the first resist pattern is chemically treated using the treating agent of the present invention.
The flow of the chemical treatment process is as follows. First, the treatment agent is infiltrated into the first resist pattern, and then a chemical reaction is caused between the infiltrated treatment agent and the resin present in the resist pattern. The surplus processing agent remaining on the substrate is removed by rinsing, and the rinsing liquid that has penetrated into the resist pattern is removed as necessary.

As a method for infiltrating the treatment agent into the first resist pattern, a method in which the substrate on which the first resist pattern is formed is immersed in the treatment agent solution, or the treatment agent solution is applied to the substrate on which the first resist pattern is formed. The method of doing is mentioned.
As a method of immersing the substrate on which the first resist pattern is formed in the treatment agent solution, a method of immersing the substrate in the treatment agent solution or paddle formation of the treatment agent solution on the substrate on the coating apparatus (liquid film formation) ).

When the substrate is immersed in the treatment agent solution, the treatment agent solution may be heated in advance. However, in order to prevent the treatment agent solution from evaporating, it is preferable to immerse the substrate at 50 ° C. or lower. Most preferably, the treatment solution is immersed in a temperature range of 20 ° C to 25 ° C.
The immersion time in the case of immersing in the treatment agent solution is preferably a long time in order to allow the treatment agent to penetrate into the first resist pattern, but in consideration of the throughput of the process, it is 20 seconds or more and 120 seconds or less. It is preferably 30 seconds or more and 90 seconds or less, more preferably 30 seconds or more and 60 seconds or less.

Examples of the method for applying the treatment agent solution to the substrate on which the first resist pattern is formed include a method of applying the treatment agent solution on a coating apparatus.
The temperature for applying the treatment agent solution on the substrate may be any temperature at which the treatment agent solution does not evaporate from room temperature, but is preferably applied at 20 to 25 ° C.

Examples of the coating method include spin coating.
In the case of spin coating, the processing agent solution is discharged from the nozzle while rotating the substrate, and the number of rotations of the substrate at that time is preferably 50 rpm to 2000 rpm, more preferably 100 rpm to 1500 rpm, and most preferably 100 rpm rpm to 1000 rpm. is there. Further, the discharge rate of the treatment agent solution at the time of spin coating is preferably 0.2 cc / second to 10 cc / second, more preferably 0.5 cc / second to 5 cc / second, and the most preferable range is It is 0.7 cc / second or more and 3 cc / second or less. Further, the discharge time of the treating agent solution at the time of spin coating is preferably 20 seconds or longer and 120 seconds or shorter, more preferably 30 seconds or longer and 90 seconds or shorter, and the most preferable range is 30 seconds or longer and 60 seconds or shorter. It is preferable that the substrate keeps rotating at the rotation speed while the treatment agent solution is being discharged.

In either case of immersing the substrate in the treatment agent solution or applying the treatment agent solution to the substrate, the substrate is rotated to shake off the treatment agent solution in order to remove the excess treatment agent solution remaining on the substrate. Preferably, the number of rotations of the substrate when shaken off is preferably 1000 rpm or more, and the rotation time at that time is preferably 10 seconds or more.
The chemical reaction between the permeating treatment agent and the resin present in the resist pattern proceeds even at room temperature, but generally the reaction efficiency is improved by heating. It is preferable to use a hot plate generally associated with the coating / developing apparatus because all the chemical treatment steps can be performed in the coating / developing apparatus.

  When the temperature is too low, the chemical reaction does not proceed sufficiently, and when the temperature is too high, the resist pattern may be deformed. The temperature is more preferably 180 ° C. or lower, and most preferably 100 ° C. or higher and 160 ° C. or lower. If the heating time is too short, the chemical reaction does not proceed sufficiently. If the heating time is too long, the throughput of the process is affected. Therefore, the heating time is preferably 30 seconds to 120 seconds, and preferably 40 seconds to 100 seconds. Further preferred.

After the heating step, it is preferable to cool the substrate to room temperature and proceed to the next step.
As a method of removing the surplus treating agent solution remaining on the substrate by rinsing, there is a method of discharging a rinsing liquid while rotating the substrate using a coating apparatus.
Although it is preferable to use the solvent used for the treating agent solution for the rinsing liquid, any solvent may be used as long as it does not dissolve the first resist pattern.
The number of rotations of the substrate in the case of rinsing is preferably 50 rpm to 2000 rpm, more preferably 100 rpm to 1500 rpm, and most preferably 100 rpm to 1000 rpm. The rinsing liquid discharge speed during rinsing is preferably 0.2 cc / sec or more and 10 cc / sec or less, more preferably 0.5 cc / sec or more and 5 cc / sec or less, and the most preferable range is 0.00. 7 cc / second or more and 3 cc / second or less. The rinsing liquid discharge time during rinsing is preferably 20 seconds or longer and 120 seconds or shorter, more preferably 30 seconds or longer and 90 seconds or shorter, and the most preferable range is 30 seconds or longer and 60 seconds or shorter. It is preferable that the substrate continues to rotate at the rotation speed while the liquid is being discharged.
After the rinsing, in order to remove the excess rinsing liquid remaining on the substrate, it is preferable to rotate the substrate and shake off the treatment agent solution. In this case, the rotation speed of the substrate is preferably 1000 rpm or more, and the rotation time is 10 It is preferable that it is more than second.

An example of a method for removing the rinse liquid that has permeated into the resist pattern is heating.
It is preferable to use a hot plate generally associated with the coating / developing apparatus because all the chemical treatment steps can be performed in the coating / developing apparatus.
The heating temperature is preferably 60 ° C. or more and 200 ° C. or less, more preferably 80 ° C., since removal does not proceed sufficiently if the temperature is too low, and the resist pattern may be deformed if the temperature is too high. It is 100 degreeC or more and 160 degrees C or less most preferably.

Also, for the purpose of improving the efficiency of chemical treatment, after forming the first resist pattern, the first resist pattern is exposed without passing through a mask, and further heated to generate a carboxylic acid that serves as a base for chemical reaction. May be.
The exposure light source in this case is most preferably the exposure light source used when forming the first resist pattern, but the photoacid generator present in the first resist pattern is decomposed to generate an acid. Any exposure light source may be used as long as it is such an exposure light source.
The exposure amount is not particularly limited as long as the photoacid generator can be decomposed, but is preferably between 5 and 20 mJ / cm ² .
The heating temperature after the exposure is preferably 50 ° C. or more and 150 ° C. or less because the carboxylic acid generation does not proceed sufficiently if the temperature is too low, and the resist pattern may be deformed if the temperature is too high. The temperature is more preferably 140 ° C. or lower and the most preferable range is 80 ° C. or higher and 130 ° C. or lower.

<Formation of second resist pattern>
In the present invention, the second resist composition is filtered and then applied to a substrate on which a first resist pattern that has already been chemically treated is formed. The filter used for filter filtration is preferably made of polytetrafluoroethylene, polyethylene, or nylon of 0.1 microns or less, more preferably 0.05 microns or less, and still more preferably 0.03 microns or less.

  As for the application method, as in the formation of the first resist pattern, the resist film is formed by applying and drying by an appropriate application method such as a spinner or a coater. The resist pattern after coating can be formed using the same process and method as the first resist pattern.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this.

<Preparation of treatment agent>
The components shown in Table 1 below were dissolved in the solvent at the following concentrations, and then filtered through a 0.05 μm polyethylene filter to prepare a treating agent solution.

<Resist preparation>
The components shown in Table 2 below were dissolved in a solvent to prepare a solution having a solid content concentration of 6% by mass, and this was filtered through a 0.05 μm polyethylene filter to prepare a positive resist solution.

  Abbreviations in Table 1 and Table 2 are as follows.

<Treatment agent composition>
(Processing agent)

Commercially available products were used as they were for the treatment agents.
FG-01: Sigma-Aldrich Corporation, product number S948195
FG-02: Sigma-Aldrich Corporation, product number B3000
FG-03: Sigma-Aldrich Corporation, product number D1203
FG-04: Tokyo Chemical Industry Co., Ltd., product number T0480
FG-05: EXFLUOR Research Corporation, product number C9DIOL

(Additive)
X01: C ₃ F ₇ SO ₃ H

<Resist composition>
(resin)
[Synthesis of Resin PO-01]
Under a nitrogen stream, 20 g of a 6/4 (mass ratio) mixed solvent of propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether was placed in a three-necked flask and heated to 80 ° C. (solvent 1). γ-butyrolactone methacrylate, hydroxyadamantane methacrylate and 2-methyl-2-adamantyl methacrylate are mixed into propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether 6/4 (mass ratio) mixed solvent at a molar ratio of 40/22/38. It melt | dissolved and the 22 mass% monomer solution (200g) was prepared. Furthermore, 8 mol% of initiator V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the monomer, and the dissolved solution was added dropwise to (solvent 1) over 6 hours. After completion of dropping, the reaction was further carried out at 80 ° C. for 2 hours. The reaction solution was allowed to cool and then poured into 1800 ml of hexane / 200 ml of ethyl acetate, and the precipitated powder was collected by filtration and dried to obtain 37 g of Resin (B1). The obtained resin (PO-01) had a weight average molecular weight of 12,000 and a dispersity (Mw / Mn) of 1.9.

  Similarly, resins (PO-02), (PO-03), and (PO-B) were synthesized.

(Photoacid generator)

(Basic compound)
TPI: 2,4,5-triphenylimidazole PEA: N-phenyldiethanolamine DPA: 2,6-diisopropylphenyl alcohol (surfactant)
W-1: MegaFuck F176 (Dainippon Ink Chemical Co., Ltd.) (Fluorine)
W-2: Megafuck R08 (Dainippon Ink Chemical Co., Ltd.) (fluorine and silicon)
W-3: Polysiloxane polymer KP-341 (manufactured by Shin-Etsu Chemical Co., Ltd.) (silicon-based)

(solvent)
A1: Propylene glycol monomethyl ether acetate A2: Cyclohexanone B1: Propylene glycol monomethyl ether B2: Ethyl lactate C1: Tert-butanol C2: 2,3-dimethyl-2-pentanol C3: Perfluoro-2-butyltetrahydrofuran C4: Octane C5 : Cyclohexanone

The prepared treating agent solution and positive resist solution were used for evaluation by the following method.
<Evaluation method>
<ArF dry exposure>
Hereinafter, a pattern forming method subjected to a freezing process will be described with reference to FIG.

FIG. 1A:
An organic antireflection film ARC29A (manufactured by Nissan Chemical Industries, Ltd.) was applied on a silicon wafer and baked at 205 ° C. for 60 seconds to form a 78 nm antireflection film 4. The first positive resist composition prepared thereon was applied and baked at 115 ° C. for 60 seconds to form a first resist film 1 having a thickness of 160 nm.

(B) and (c) of FIG.
The wafer coated with the resist film 1 was subjected to pattern exposure using an ArF excimer laser scanner (PAS5500 / 1100, manufactured by ASML, NA0.75) through an exposure mask m1. After heating at 115 ° C. for 60 seconds, developing with an aqueous tetramethylammonium hydroxide solution (2.38% by mass) for 30 seconds, rinsing with pure water, spin drying, and a first 180 nm line width 90 nm first pitch. Resist patterns 1a and 1a ′ were obtained.

FIG. 1 (d), (e):
Subsequently, exposure with the ArF excimer laser scanner was performed at an exposure amount of 30 mJ / cm ² through a mask m2 so that the entire surface of the first resist pattern 1a ′ was exposed. After heating at 115 ° C. for 60 seconds, developing with an aqueous tetramethylammonium hydroxide solution (2.38 mass%) for 30 seconds, rinsing with pure water, spin drying, and resist film of resist pattern 1a ′ Was completely removed so that only the first resist pattern 1a remained on the wafer coated with the organic antireflection film.

(F) to (h) in FIG.
Subsequently, while rotating the wafer on which the first resist pattern 1a remains at 500 rpm, the processing agent 3 is discharged from the nozzle n at a flow rate of 2 cc / sec for 60 seconds, and then rotated at 2000 rpm for 60 seconds. Completely shaken out.
Next, after baking at 130 ° C. for 90 seconds to advance the reaction, the wafer is cooled to room temperature, rinsed with 2-heptanol for 20 seconds, and a first pattern 1b subjected to a freezing treatment with a processing agent is formed. did.

(J) in FIG.
The prepared second positive resist composition is applied to the wafer having the processed first resist pattern 1b and baked at 115 ° C. for 60 seconds to form a second resist film 2 of 160 nm. did. Of the obtained wafer, a portion where the first resist pattern 1b did not exist was subjected to pattern exposure using the ArF excimer laser scanner through a mask m3 having a pitch of 180 nm and a line width of 90 nm.

FIG. 1 (k), (l):
Subsequently, a portion where the first resist pattern 1b and the second resist film 2 are mixed is 30 mJ / cm by means of the ArF excimer laser scanner through a mask m4 which shields the portion consisting only of the second resist film. The film was exposed to an exposure amount of ² , and then heated at 115 ° C. for 60 seconds, developed with an aqueous tetramethylammonium hydroxide solution (2.38 mass%) for 30 seconds, rinsed with pure water, and then spin-dried. In this way, the exposed portion of the resist film 2 exposed through the mask m3 and the portion of the second resist film 2 where the first resist pattern 1b exists are completely removed, and the second resist pattern is removed. 2a was formed and the first resist pattern 1b was exposed. In this way, a pattern in which the first resist pattern 1b and the second resist pattern 2a were aligned on the wafer with a pitch of 180 nm and a line width of 90 nm was formed.

<ArF immersion exposure>
Pure water was used as the immersion liquid, PAS5500 / 1250i manufactured by ASML equipped with a lens of NA 0.85 was used as an ArF excimer laser scanner, the pattern dimensions were changed to a pitch of 130 nm, a line width of 65 nm, and a film thickness of 120 nm. A pattern was formed using the same method as that shown in the above-mentioned “ArF dry exposure” except for the above.

The results obtained by the above composition and method are shown in Table 3.
<ArF dry exposure>

* Indicates that the pattern 1a has completely disappeared after treatment with the treating agent.
<ArF immersion exposure>

(Measurement of pattern dimensions)
The dimension of the resist pattern created by the above method was measured using a scanning electron microscope for length measurement (SEM, S-9380II manufactured by Hitachi, Ltd.). The dimensions of the resist pattern 1 before processing with the processing agent and the dimensions of the resist pattern 1 after processing with the processing agent are measured, respectively, and the variation ratio of the pattern dimensions before and after processing (the dimension (1b) of the resist pattern 1 after processing). / The dimension (1a) of the resist pattern 1 before processing was determined. The closer this value is to 1, the smaller the dimensional variation after the treatment step with the treatment agent, and the better the performance. Similarly, the dimension of the resist pattern 1 and the dimension of the resist pattern 2 after processing with the processing agent are respectively measured, and the finished pattern dimension ratio of the resist 1 and the resist 2 (the dimension of the resist pattern 2 (2a) / the resist after processing) The dimension (1b) of pattern 1 was determined. The closer this value is to 1, the closer the finished dimensions of the resist pattern 1 and the resist pattern 2 are, and the better the performance when transferring the resist pattern to the substrate.

(Measurement of pattern height)
The height of the resist pattern created by the above method was measured by SEM Hitachi Ltd. S-4800. The height of the resist pattern 1 and the height of the resist pattern 2 after processing with the processing agent are measured, respectively, and the finished height ratio of the resist 1 and the resist 2 (the height of the resist pattern 2 (2a) / the resist pattern after the processing) 1 height (1b)) was determined. The closer this value is to 1, the higher the finished height of the resist pattern 1 and the resist pattern 2, and the better the performance when transferring the resist pattern to the substrate.

(Evaluation of dry etching resistance)
Each resist composition prepared in the same manner as described above was applied onto a silicon wafer subjected to hexamethyldisilazane treatment by spin coating, and baked at 115 ° C. for 60 seconds to form a resist film having a thickness of 200 nm. The resist film was etched using an ULVAC parallel plate type reactive ion etching apparatus under the conditions of an etching gas of oxygen, a pressure of 20 mTorr, and an applied power of 100 mW / cm ³ . The etching rate of the resist film was determined from the change in film thickness. The etching rate is calculated for the resist film with and without the freezing treatment using the treating agent, and finally the etching rate ratio (etching rate after processing / etching rate before processing). Calculated as

From the results of Tables 3 and 4, the pattern forming treatment agent of the present invention was compared with a comparative example in which the treatment agent was not used in the property evaluation by ArF dry exposure and ArF immersion exposure.
(I) The first resist pattern does not dissolve in the second resist solution. (Ii) As a result of greatly suppressing the dimensional variation of the first resist pattern,
The first resist pattern and the second resist pattern can be formed with the same dimensions. (Iii) Dry etching of the first resist-coated film and the second resist-coated film
As described above, the processing agent for forming a pattern according to the present invention acts on the resist pattern so as to satisfy all the characteristics required in the freezing process. Thus, it is clear that the processing agent for pattern formation of the present invention exhibits excellent pattern forming properties in the freezing process.

It is the schematic of the pattern formation method using a freezing process.

Explanation of symbols

1: Resist 1, 1a: Pattern formed using resist 1
1b: Resist pattern 1a after treatment with a treating agent
2: resist 2, 2a: pattern formed using resist 2: treatment agent 4: semiconductor substrate (including antireflection film layer)
m: Exposure mask m1 to m4: Represents a mask used in each step.
n: Discharge nozzle

Claims (4)

  After the first resist pattern is formed on the first resist film, the second resist film is formed on the first resist pattern, and the surface treatment agent used in the previous step for forming the second resist pattern is used. A surface treatment agent for pattern formation, comprising a polyhydric alcohol compound as the surface treatment agent.   The polyhydric alcohol compound is at least one compound selected from a derivative of an aliphatic hydrocarbon compound, a derivative of an aliphatic cyclic hydrocarbon compound, or an aromatic compound derivative having at least two alcoholic hydroxyl groups. The surface treatment agent for pattern formation according to claim 1.   Furthermore, the organic solvent is contained, The surface treatment agent for pattern formation of Claim 1 or 2 characterized by the above-mentioned.   The first resist pattern is surface-treated with the surface treatment agent for pattern formation according to any one of claims 1 to 3, and then a second resist film is formed on the surface-treated first resist pattern. And forming a second resist pattern.

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