JP2008310159A - Method for forming fine hollow body and fine hollow body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for easily forming a fine hollow body by applying heat lithography and a fine hollow body formed by the method. <P>SOLUTION: The method for forming a fine hollow body includes subjecting a resist laminate having a resist underlayer film which absorbs light of a wavelength of an exposing source used in heat lithography between a support and a resist layer to selective exposure with light of a wavelength which is absorbed in the resist underlayer film. The fine hollow body formed by the method for forming a fine hollow body is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming a fine hollow body to which thermal lithography is applied, and a fine hollow body formed by the forming method.

In the lithography technique, a photosensitive organic material called a photoresist has been conventionally used. As a photoresist, solubility in an alkali developer (hereinafter, sometimes referred to as “alkali solubility”) is changed by irradiation (exposure) of radiation such as short-wavelength light such as vacuum ultraviolet rays or electron beam. Things are commonly used. Such a photoresist changes its alkali solubility due to, for example, partial decomposition 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, thereby making it possible to form a resist pattern. That is, when the photoresist is selectively exposed, the alkali solubility of the photoresist partially changes, and the photoresist is composed of a portion having a high alkali solubility and a portion having a low alkali solubility. It will have a pattern. When this photoresist is developed with an alkali, a portion having high alkali solubility is dissolved and removed, whereby a resist pattern is formed.
The photoresist includes a positive type in which the alkali solubility in the exposed area is increased and a negative type in which the alkali solubility in the exposed area is decreased.
As one of photoresists having high sensitivity to an exposure light source with a short wavelength, a photoacid generator (PAG) that generates acid by the action of radiation, and a base material component whose alkali solubility changes by the action of the acid Chemically amplified resist compositions containing these are known (see, for example, Patent Documents 1 and 2).

In the data writing process of an optical ROM (Read Only Memory) disk, in the near future, a lithography technique that realizes pits of at least 100 nm or less is desired in order to realize ultra-high density recording.
As described above, the development of a method using a light source having a shorter wavelength or a method using an electron beam has been performed so far, but as the wavelength of the light source used for exposure becomes shorter, only the light source is used. In addition, various difficult problems related to optical factors occur. For example, exposure machines tend to increase in price and size as the wavelength of the light source decreases, and when using an electron beam, high voltage conditions, a vacuum chamber, etc. are required to generate an electron beam. As a result, large-scale facilities are required. These problems increase the manufacturing cost of products such as optical CD-ROM discs.

One technique that has been recently developed is thermal lithography. In this method, light is not used directly, but heat distribution generated by light is used. According to thermal lithography, it is possible to perform fine drawing less than the spot diameter of light, and it is possible to form a fine pattern and achieve high speed and low cost.
As an already reported thermal lithography method, there is a method using an inorganic material whose properties are rapidly changed when the temperature becomes a certain level or more. For example, Non-Patent Document 1 describes a method using a laminate in which a ZnS—SiO ₂ layer, a TbFeCo layer, and a ZnS—SiO ₂ layer are laminated in this order on a substrate. This method is thermal lithography using a change in volume due to heat. In such a method, the TbFeCo layer absorbs laser light and generates heat, and when the temperature exceeds 200 ° C., the volume starts to increase. The pattern is formed by increasing the film thickness of the irradiated portion of the laser beam.
In addition, a method using platinum oxide as the inorganic material has been reported (for example, see Non-Patent Document 2). This method uses the property that platinum oxide evaporates explosively when the temperature exceeds a certain temperature. Blue oxide light is applied to the platinum oxide applied to the substrate surface to heat it, and the parts required for processing are removed. I try to remove it. According to this method, it is said that fine pattern formation of 100 nm or less can be realized with blue laser light (wavelength 405 nm).
For example, Non-Patent Document 3 describes a method of using a laminate in which a Ge ₂ Sb ₂ Te ₅ layer, a ZnS—SiO ₂ layer, and a photoresist film are laminated in this order on a polycarbonate substrate. Yes. In this method, first, when irradiated with red laser from the lower side of the substrate, the laser light is absorbed in the _Ge 2 _Sb 2 Te ₅ layer, _Ge 2 _Sb 2 Te ₅ layer of that portion generates heat. This heat is transmitted to the upper resist film (negative), and due to the action of the heat, the alkali solubility of the resist film in the exposed portion is lowered. Therefore, a resist pattern is formed by alkali developing this.

Lithography technology that excels in the production of fine structures is used for the production of microdevices in the chemical and biochemical fields such as microreactors in addition to the production of various electronic devices such as semiconductor devices and liquid crystal devices. Here, the microreactor is a micro reaction vessel having a fine recess or a flow path (micro flow path), and is mainly used in a chemical reaction or a biochemical reaction. By micronizing the reaction system using a microreactor, in addition to resource saving and energy saving, it is possible to achieve rapid reaction and high efficiency. This is presumably because the reaction conditions can be precisely controlled by performing the reaction in a micro space such as a micro flow path.
Japanese Patent No. 2881969 JP 2003-241385 A Jpn. J. et al. Appl. Phys. Vol. 43, no. 8B (2004) pp. L1045-L1047 53rd Joint Conference on Applied Physics, Preliminary Proceedings, pp. 1051 (Spring 2006), 22a-D-9 Jpn. J. et al. Appl. Phys. Vol. 41, no. 9A / B (2002) pp. L1022-L1024

Usually, a fine pattern formed on a substrate by a lithography technique is a pattern having a minute uneven structure, and it is difficult to form a tubular structure. For this reason, in order to form a microreactor having a fine hollow structure such as a microtunnel or a microtube, it is necessary to adhere a substrate on which a concave microchannel is formed to another flat substrate, There was a problem of being complicated.
This invention is made | formed in view of the said situation, Comprising: It aims at providing the method of forming a fine hollow body easily, and the fine hollow body formed by this method.

  The first aspect of the present invention that solves the above problem is a resist laminate having a resist underlayer film that absorbs light having a wavelength of an exposure light source used in thermal lithography between a support and a resist film. A method for forming a fine hollow body, wherein selective exposure is performed using light having a wavelength absorbed by the resist underlayer film.

  The second aspect of the present invention is a fine hollow body formed by using the method for forming a fine hollow body described above.

  A third aspect of the present invention is a nanochannel having a fine hollow body formed by using the method for forming a fine hollow body described above.

In the present specification and claims, “exposure” is a concept including general radiation irradiation.
Unless otherwise specified, the “alkyl group” includes linear, branched and cyclic monovalent saturated hydrocarbon groups.
A “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” and “unit” mean a monomer unit (monomer unit) constituting a resin (polymer, copolymer).
“(Meth) acrylic acid” means one or both of acrylic acid having a hydrogen atom bonded to the α-position and methacrylic acid having a methyl group bonded to the α-position.
“(Meth) acrylic acid ester” means one or both of an acrylic acid ester having a hydrogen atom bonded to the α-position and a methacrylic acid ester having a methyl group bonded to the α-position.
“(Meth) acrylate” means one or both of an acrylate having a hydrogen atom bonded to the α-position and a methacrylate having a methyl group bonded to the α-position.

  ADVANTAGE OF THE INVENTION According to this invention, the formation method of the micro hollow body which can form a micro air body of a desired shape on a support body simply by applying a thermal lithography can be provided.

≪Method for forming fine hollow body≫
The method for forming a fine hollow body according to the present invention is such that the resist underlayer film has a resist underlayer film that absorbs light having a wavelength of an exposure light source used in thermal lithography between the support and the resist film. Selective exposure is performed using light having a wavelength absorbed by the light.

<Support>
The support is not particularly limited, and a conventionally known support can be used. 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. Further, an inorganic and / or organic antireflection film may be provided on the substrate.

<Resist film>
Although it does not specifically limit as a resist film, It is preferable that it is a resist film formed using the negative resist composition. The negative resist composition includes a base component (A) (hereinafter referred to as component (A)) whose solubility in an alkaline developer is reduced by the action of an acid, and an acid generator component (B) that generates an acid by heat. ) (Hereinafter referred to as “component (B)”) and a negative resist composition containing a crosslinking agent component (C) (hereinafter referred to as “component (C)”). .
In addition, since a fine hollow body faithful to a desired pattern can be formed, the resist film is formed using a negative resist composition that is not sensitive to light having a wavelength absorbed by the resist underlayer film. More preferred.
The thickness of the resist film can be appropriately determined in consideration of the pore size and size of the desired fine hollow body, but is preferably 30 to 1000 nm, more preferably 50 to 600 nm, and still more preferably 50 to 450 nm. It is.

<(A) component>
The component (A) is not particularly limited, and any component can be selected and used from among a large number of components that have been proposed as base material components for negative resist compositions. The base material component is soluble in an alkali developer before exposure. However, when an acid is generated from the component (B) after exposure, the base material component reacts with the crosslinking component described later by the action of the acid. Thus, the solubility in an alkaline developer is reduced.

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.
The organic compound having a molecular weight of 500 or more includes a low molecular weight organic compound having a molecular weight of 500 or more and less than 2000 (hereinafter referred to as a low molecular compound) and a high molecular weight organic compound having a molecular weight of 2000 or more (hereinafter referred to as a polymer compound). )). As the low molecular weight compound, a non-polymer is usually used. As the polymer compound, a resin (polymer, copolymer) is usually used. In the case of a resin, a polystyrene-reduced weight average molecular weight by GPC (gel permeation chromatography) is used as the “molecular weight”. Hereinafter, the term “resin” refers to a resin having a molecular weight of 2000 or more.
The component (A) may be a low-molecular compound whose solubility in an alkali developer is reduced by the action of an acid, or a resin whose solubility in an alkali developer is reduced by the action of an acid. It may be a mixture of

(A) As a component, what has a hydrophilic group is preferable.
The hydrophilic group in the component (A) includes 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 is preferred. Among these, a hydroxyl group (particularly an alcoholic hydroxyl group, a phenolic hydroxyl group, a group having a fluorine atom or a fluorinated alkyl group on the carbon atom to which the hydroxyl group is bonded (fluorinated alcohol)), a carboxy group, and an ester group are more preferable. Particularly preferred are groups, alcoholic hydroxyl groups, phenolic hydroxyl groups, and fluorinated alcohols.

As the component (A) of the negative resist composition, an alkali-soluble resin is usually used. Examples of the alkali-soluble resin include α- (hydroxyalkyl) acrylic acid, or lower alkyl ester of α- (hydroxyalkyl) acrylic acid, 1-methacryloyloxy-3-hydroxyadamantane, 1-acryloyloxy-3-hydroxyadamantane, Norbornane hexafluoroalcohol acrylate, 2-[{5- (1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl} norbornyl] methacrylate, and 2-[{5- Resin having a unit derived from at least one selected from (1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl} norbornyl] acrylate is excellent in low swelling A favorable pattern 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.
Further, as an alkali-soluble resin, a novolak resin having a hydrophilic group, a hydroxystyrene resin, an (α-lower alkyl) acrylate resin, a structural unit derived from hydroxystyrene and an (α-lower alkyl) acrylate ester Examples thereof include a copolymer resin containing a derived structural unit.
Examples of the (α-lower alkyl) acrylate resin include a structural unit derived from an (α-lower alkyl) acrylate ester having a hydroxyl group-containing group such as a fluorinated hydroxyalkyl group or a hydroxyalkyl group. Resin.
The mass average molecular weight (Mw; polystyrene-equivalent mass average molecular weight by GPC) of the alkali-soluble resin is preferably 2000 to 30000, more preferably 2000 to 10000, and still more preferably 3000 to 8000. By setting it within this range, a good dissolution rate in an alkali developer can be obtained, which is preferable from the viewpoint of high resolution. When the weight average molecular weight is lower within this range, good characteristics tend to be obtained.

<(B) component>
The component (B) is a component that generates an acid by the action of heat. Here, “generating an acid by the action of heat” means generating an acid by heating at 80 ° C. or more and 200 ° C. or less.
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, and poly (bissulfonyl) diazomethanes. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators, and the like.
These acid generators are generally known as photoacid generators (PAGs) that generate acid upon exposure, but may also be used as thermal acid generators (TAG) that generate acid by the action of heat. Function. Therefore, as the component (B), a PAG that has been conventionally used in photolithography can be used.

  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 the oxime sulfonate-based acid generator include, for example, general formula> C═N—O—SO ₂ —R ³¹ [wherein R ³¹ is an alkyl group or an aryl group which may have a substituent. ] The oxime sulfonate type compound which has a structure represented by this is mentioned.
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- (methylsulfonyl) And (oxyimino) -p-bromophenylacetonitrile, compounds represented by the following formula (B-1), and the like. Among these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile and the compound represented by the formula (B-1) are preferable.

  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, sufficient pattern formation is performed.

<(C) component>
The component (C) is not particularly limited, and can be arbitrarily selected from the crosslinking agents used in the chemically amplified negative resist compositions known so far.
Specifically, for example, 2,3-dihydroxy-5-hydroxymethylnorbornane, 2-hydroxy-5,6-bis (hydroxymethyl) norbornane, cyclohexanedimethanol, 3,4,8 (or 9) -trihydroxytrimethyl Aliphatic cyclic carbonization having a hydroxyl group or a hydroxyalkyl group or both such as cyclodecane, 2-methyl-2-adamantanol, 1,4-dioxane-2,3-diol, 1,3,5-trihydroxycyclohexane Examples thereof include hydrogen or oxygen-containing derivatives thereof.
In addition, amino group-containing compounds such as melamine, acetoguanamine, benzoguanamine, urea, ethylene urea, propylene urea, glycoluril are reacted with formaldehyde or formaldehyde and a lower alcohol, and the hydrogen atom of the amino group is converted into a hydroxymethyl group or a lower alkoxymethyl. And a compound substituted with a group, a compound having an epoxy group, and the like.
Of these, those using melamine are melamine crosslinking agents, those using urea are urea crosslinking agents, those using alkylene ureas such as ethylene urea and propylene urea are alkylene urea crosslinking agents, and glycoluril is used. This was called a glycoluril-based crosslinking agent.
The component (C) is preferably at least one selected from the group consisting of melamine-based crosslinking agents, urea-based crosslinking agents, alkylene urea-based crosslinking agents, epoxy-based crosslinking agents, and glycoluril-based crosslinking agents, and particularly melamine. System crosslinking agents are preferred.
The content of the component (C) is preferably 1 to 50 parts by mass, more preferably 3 to 30 parts by mass, and still more preferably 3 to 15 parts by mass with respect to 100 parts by mass of the component (A). When the content of the component (C) is at least the lower limit value, the crosslinking formation proceeds sufficiently and a good resist pattern can be obtained. Moreover, when it is below this upper limit, the storage stability of the resist coating solution is good, and the deterioration of sensitivity with time is suppressed.

<Other optional components>
As a negative resist composition, a nitrogen-containing organic compound (D) (hereinafter referred to as “component (D)”) can be blended as an optional component.
Since a wide variety of components (D) have already been proposed, any known one may be used. Among them, aliphatic amines, particularly secondary aliphatic amines and tertiary aliphatic amines are used. preferable. Here, “aliphatic” in the claims and the specification is a relative concept with respect to aromatics, and is defined to mean groups, compounds, and the like that do not have aromaticity.
“Aliphatic cyclic group” means a monocyclic group or polycyclic group having no aromaticity. An aliphatic amine is an amine having one or more aliphatic groups, and the aliphatic groups preferably have 1 to 12 carbon atoms.
Examples of the aliphatic amine include amines (alkyl amines or alkyl alcohol amines) or cyclic amines in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group or hydroxyalkyl group having 12 or less carbon atoms.
Specific examples of alkylamines and alkyl alcohol amines include monoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; diethylamine, di-n-propylamine, di- -Dialkylamines such as n-heptylamine, di-n-octylamine, dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine , Tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decanylamine, tri-n-dodecylamine, and the like; diethanolamine, triethanolamine, diisopropanolamine Triisopropanolamine, di -n- octanol amines, alkyl alcohol amines tri -n- octanol amine. Among these, alkyl alcohol amines and trialkyl amines are preferable, and alkyl alcohol amines are more preferable. Of the alkyl alcohol amines, triethanolamine and triisopropanolamine are most preferred.
Examples of the cyclic amine include heterocyclic compounds containing a nitrogen atom as a hetero atom. The heterocyclic compound may be monocyclic (aliphatic monocyclic amine) or polycyclic (aliphatic polycyclic amine).
Specific examples of the aliphatic monocyclic amine include piperidine and piperazine.
As the aliphatic polycyclic amine, those having 6 to 10 carbon atoms are preferable. Specifically, 1,5-diazabicyclo [4.3.0] -5-nonene, 1,8-diazabicyclo [5. 4.0] -7-undecene, hexamethylenetetramine, 1,4-diazabicyclo [2.2.2] octane, and the like.
These may be used alone or in combination of two or more.
(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

The negative resist composition further includes at least one compound (E) selected from the group consisting of organic carboxylic acids and phosphorus oxo acids and derivatives thereof for the purpose of preventing sensitivity deterioration and the like. (Hereinafter referred to as “component (E)”).
As the organic carboxylic acid, for example, acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.
Examples of phosphorus oxo acids and derivatives thereof include phosphoric acid, phosphonic acid, phosphinic acid and the like, and among these, phosphonic acid is particularly preferable.
Examples of the oxo acid derivative of phosphorus include esters in which the hydrogen atom of the oxo acid is substituted with a hydrocarbon group, and the hydrocarbon group includes an alkyl group having 1 to 5 carbon atoms and 6 to 6 carbon atoms. 15 aryl groups and the like.
Examples of phosphoric acid derivatives include phosphoric acid esters such as di-n-butyl phosphate and diphenyl phosphate.
Examples of phosphonic acid derivatives include phosphonic acid esters such as phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, and phosphonic acid dibenzyl ester.
Examples of the phosphinic acid derivatives include phosphinic acid esters such as phenylphosphinic acid.
(E) A component may be used individually by 1 type and may use 2 or more types together.
As the component (E), an organic carboxylic acid is preferable, and salicylic acid is particularly preferable.
(E) A component is normally used in the ratio of 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

In addition, the resist composition can be in the form of a solution by dissolving the above components in an organic solvent (S) (hereinafter referred to as the (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 or two of conventionally known solvents for resist compositions can be used. More than one species 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 , Methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, may be mentioned methyl methoxypropionate, and esters such as ethyl ethoxypropionate. Among these, 2-heptanone, 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.
Although the usage-amount of (S) component is not specifically limited, The quantity used as the liquid of the density | concentration which the said negative resist composition can apply | coat on a resist underlayer film is used.

<Resist underlayer film>
The resist underlayer film is not particularly limited as long as it absorbs light having a wavelength of an exposure light source used in thermal lithography, and may be a film formed using an inorganic material. It may be a film (organic film) formed using. Since it is cheaper and has excellent processability, it is preferably an organic film, and used in thermal lithography with an organic compound (A ′) having a film-forming ability (hereinafter referred to as “component (A ′)”). More preferably, the organic film contains a dye (B ′) that absorbs light having a wavelength of an exposure light source (hereinafter referred to as “component (B ′)”).
Note that the resist underlayer film does not necessarily require sensitivity to light or an electron beam.
In addition, the resist underlayer film is formed by applying a solution prepared by dissolving the composition for the resist underlayer film containing the component (A ′) and the component (B ′) in an appropriate organic solvent on the support. It can be performed by baking or the like.

<(A ') component>
As the component (A ′), any organic compound having film-forming ability may be used, and an organic compound having a molecular weight of 500 or more is preferable because of excellent film-forming ability.
The component (A ′) is not particularly limited, and is an organic compound or low-molecular compound generally used as a film-forming resin in the production of semiconductor elements or liquid crystal display elements, such as resist films, organic antireflections. Resins and low-molecular compounds used as substrate components such as membranes can be used. Examples of the resin include a novolak resin, a resin having a structural unit derived from hydroxystyrene (polyhydroxystyrene, hydroxystyrene-styrene copolymer, etc.), a resin having a structural unit derived from an acrylate ester, and a cycloolefin. Resins having a structural unit derived from the above, soluble polyimide, and the like. In particular, those having as a main component at least one selected from the group consisting of novolak resins, acrylic resins and soluble polyimides are preferably used as the component (A ′). Among these, novolak resins and acrylic resins having an alicyclic moiety or aromatic ring in the side chain are inexpensive and widely used and are preferably used.

As the novolak resin, those generally used in positive resist compositions can be used, and i-line and g-line positive resists containing novolak resin as a main component can also be used.
As the novolak resin, a commercially available one may be used or synthesized.
The novolak resin can be obtained, for example, by addition condensation of an aromatic compound having a phenolic hydroxyl group (hereinafter simply referred to as “phenols”) and an aldehyde under an acid catalyst.
Examples of phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p-butylphenol, 2, 3 -Xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol , P-phenylphenol, resorcinol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, phloroglicinol, hydroxydiphenyl, bisphenol A, gallic acid, gallic acid ester, α-naphthol, β-naphthol and the like.
In particular, a novolac resin obtained using phenols containing m-cresol is preferable because it has good embedding characteristics. The proportion of m-cresol in the phenols used for obtaining such novolak resin is preferably 20 to 100 mol%, more preferably 40 to 90 mol%.
Moreover, it is preferable that the phenols further contain p-cresol in addition to m-cresol, since the film formability of the lower layer film is improved. When the film formability of the lower layer film is improved, the occurrence of intermixing when the resist composition is applied on the lower layer film to provide the resist film is prevented.
When p-cresol is included, the proportion is preferably 10 to 50 mol%, more preferably 15 to 30 mol% in phenols.
Examples of aldehydes include formaldehyde, furfural, benzaldehyde, nitrobenzaldehyde, acetaldehyde and the like. In view of industrial productivity and the like, formaldehyde is most preferable.
The catalyst for the addition condensation reaction is not particularly limited. For example, hydrochloric acid, nitric acid, sulfuric acid, formic acid, oxalic acid, acetic acid and the like are used as the acid catalyst.

The mass average molecular weight (Mw) of the novolak resin is preferably 3000 or more, more preferably 5000 or more, more preferably 6000 or more, further preferably 7000 or more, and particularly preferably 8000 or more. Further, Mw is preferably 50000 or less, more preferably 30000 or less, further preferably 10,000 or less, and particularly preferably 9000 or less.
When Mw is 3000 or more, it is difficult to sublime when baked at a high temperature, and the device or the like is hardly contaminated. Moreover, the embedding characteristic with respect to the board | substrate which has fine unevenness | corrugation is more excellent as Mw is 50000 or less.

In the novolak resin, the content of low nuclei having a molecular weight of 500 or less, particularly the content of low nuclei having a molecular weight of 200 or less, is preferably 1% by mass or less, preferably 0.8% by mass or less in the GPC method. Is more preferable. The content of the low nucleus is preferably as small as possible, and is desirably 0% by mass.
In the novolak resin having Mw within the above range, the content of the low nucleus having a molecular weight of 500 or less is 1% by mass or less, so that the embedding characteristic with respect to the substrate having fine irregularities is improved. Although the reason why the embedding property is improved by reducing the content of the low nuclei is not clear, it is presumed that the degree of dispersion becomes small. Furthermore, since the content of the low nucleus is reduced, the resistance of the lower layer film containing the resin to the organic solvent is also improved. Therefore, when the resist composition is applied onto the lower layer film, intermixing due to the organic solvent contained in the resist composition is unlikely to occur.
Here, the “low molecular weight having a molecular weight of 500 or less” is detected as a low molecular fraction having a molecular weight of 500 or less when analyzed by GPC using polystyrene as a standard. “Low molecular weight less than 500 molecular weight” includes monomers that have not been polymerized and those that have a low degree of polymerization, such as those in which 2 to 5 molecules of phenols are condensed with aldehydes, depending on the molecular weight. .
The content (mass%) of the low nuclei having a molecular weight of 500 or less is graphed by taking the analysis result by the GPC method with the fraction number on the horizontal axis and the concentration on the vertical axis, and the molecular weight of 500 or less with respect to the area under the entire curve. It is measured by determining the percentage (%) of the area under the curve of the low molecular fraction.

The adjustment of Mw of the novolak resin and the removal of the low nuclei having a molecular weight of 500 or less can be performed, for example, by the following fractional precipitation treatment. First, a novolak resin is dissolved in a polar solvent, and a poor solvent such as water, heptane, hexane, pentane, or cyclohexane is added to the solution. At this time, since the low nuclei having a molecular weight of 500 or less remain dissolved in the poor solvent, a novolac resin having a reduced content of the low nuclei having a molecular weight of 500 or less can be obtained by filtering the precipitate. it can.
Examples of the polar solvent include alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, glycol ether esters such as ethylene glycol monoethyl ether acetate, and cyclic ethers such as tetrahydrofuran.

As the acrylic resin, those generally used for resist compositions can be used. For example, the acrylic resin is derived from a structural unit derived from a polymerizable compound having an ether bond and a polymerizable compound having a carboxy group. And an acrylic resin containing the structural unit.
Examples of the polymerizable compound having an ether bond include 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxy polyethylene glycol (meta And (meth) acrylic acid derivatives having an ether bond and an ester bond such as acrylate, methoxypolypropylene glycol (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate. Any one of these compounds may be used alone, or two or more thereof may be used in combination. In the present specification, (meth) acrylate represents one or both of acrylate and methacrylate.
Examples of the polymerizable compound having a carboxy group include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; 2-methacryloyloxyethyl succinic acid, and 2-methacryloyloxyethyl. Examples include maleic acid, 2-methacryloyloxyethylphthalic acid, 2-methacryloyloxyethylhexahydrophthalic acid, and other compounds having a carboxy group and an ester bond, and acrylic acid and methacrylic acid are preferred. Any one of these compounds may be used alone, or two or more thereof may be used in combination.

  A soluble polyimide is a polyimide that can be made liquid by an organic solvent.

  The component (A ′) may be a compound having a light absorption property (hereinafter referred to as “component (A′-1)”), or a compound having no light absorption property (hereinafter referred to as a component (A′-2)). It may be.) In view of excellent effects of the present invention, the component (A ′) is preferably the component (A′-1). That is, since the component (A ′) has a light absorption property, the amount of the component (B ′) necessary to achieve a desired absorbance can be reduced. Therefore, for example, it is possible to reduce risks that may occur due to the inclusion of the component (B ′), such as generation of sublimates due to heating during film formation, deterioration of yield accompanying the generation, and generation of precipitates when formed into a solution. .

Examples of the component (A′-1) include those having a molecular structure that absorbs light having a wavelength of an exposure light source used in thermal lithography among the organic compounds listed as the component (A ′).
As the component (A′-2), among the organic compounds mentioned as the component (A ′), those not corresponding to the component (A′-1), that is, absorbing light having a wavelength of an exposure light source used in thermal lithography. The thing which does not do is mentioned.
Whether or not the organic compound absorbs the light is determined by forming an organic film using an organic solvent of the organic compound in the same manner as in the previous method for measuring absorbance, and the absorbance at the wavelength of the exposure light source. It can be confirmed by measuring.

<(B ′) component>
The component (B ′) is not particularly limited as long as it is a dye organic compound that absorbs light having a wavelength of an exposure light source used in thermal lithography, and is appropriately selected from commercially available dyes depending on the wavelength of the exposure light source to be used. Select and use.
Whether or not the dye absorbs light having the wavelength of the exposure light source to be used may be determined by referring to a pamphlet or the like issued by the manufacturer, or by a conventional method using a spectrophotometer.

In the present invention, the “exposure light source used in thermal lithography” is not particularly limited as long as it is an exposure light source capable of performing thermal lithography, and the wavelength of the exposure light source ranges from several nm to approximately 800 nm. Can be used. Not only in the region on the long wavelength side such as visible light, but also in the case of using an exposure light source such as EUV, F ₂ , ArF, KrF, g-line, i-line used in photolithography, the heat distribution is This is because it is considered that it is possible to form a pattern by thermal lithography using the narrow spot of heat because it becomes narrower than the wavelength of each light.
As the component (B ′), a compound that absorbs light having a wavelength of 350 nm or more is preferable, and a dye that absorbs a visible light laser is more preferable. In particular, a dye that absorbs light having a wavelength of 350 to 800 nm is preferable, a dye that absorbs light having a wavelength of 350 to 550 nm is more preferable, and a dye that absorbs light having a wavelength of 350 to 450 nm is most preferable. The resist film formed using the negative resist composition is usually sensitive to light having a wavelength of 250 nm or less, such as an excimer laser such as a KrF excimer laser or an ArF excimer laser, or a light source having a shorter wavelength. This is because it is not sensitive to light having a wavelength of 350 nm or more, for example, visible light laser.
For example, as a compound that absorbs light having a wavelength near 400 nm, compounds mainly used as yellow dyes can be mentioned. Specific examples include trade names: OY-105, OY-107, OY-108, OY. -129, OY-3G, OY-GG-S (manufactured by Orient Chemical Co., Ltd.), Diaresin Yellow F, Diaresin A (manufactured by Mitsubishi Chemical), Soldan Yellow GRN (manufactured by Chugai Kasei Co., Ltd.), Sumiplast Yellow
GG, Sumiplast Yellow F5G, Sumiplast Yellow FG (manufactured by Sumitomo Chemical Co., Ltd.), CH-1002 (manufactured by Daito Chemix), and the like.

As the component (B ′), one type may be used alone, or two or more types may be mixed and used.
The blending amount of the component (B ′) may be appropriately adjusted according to the desired absorbance, the type of the component (B ′) to be used, whether the component (A ′) absorbs the wavelength of the exposure light source, and the like. (B ') The preferable compounding quantity of a component is 1-100 mass parts with respect to 100 mass parts of (A') components, More preferably, it is 5-80 mass parts, Most preferably, it is 10-60 mass parts. It is. When it is 1 part by mass or more, the absorbance is improved, and when it is 100 parts by mass or less, the coatability is improved.

      The resist underlayer film may not contain the component (B ′) when the component (A ′) is the component (A′-1). This is because the component (A′-1) also has a function as the component (B ′). In this case, for example, there is a risk that it may occur due to the inclusion of the component (B ′), such as generation of sublimates due to heating during film formation, deterioration of yield accompanying it, generation of precipitates when formed into a solution, and the like. Can be reduced.

<Other optional components>
When the component (A ′) is a novolac resin, the material for forming a lower layer film for thermolithography is further a phenol derivative (C ′) having a molecular weight of 200 or more esterified with naphthoquinonediazidesulfonic acid (hereinafter referred to as (C ′ ) Component)).
Here, the naphthoquinone diazide sulfonic acid includes a reactive derivative such as a naphthoquinone diazide sulfonic acid halide. Such reactive derivatives are suitably used for obtaining the component (C ′) because they are excellent in reactivity with phenol compounds.
That is, the component (C ′) includes a phenol derivative esterified with a halide such as naphthoquinone diazide sulfonic acid chloride as the naphthoquinone diazide sulfonic acid.
By containing the component (C ′), the film formability of the lower layer film for thermal lithography is improved.
The reason why the film forming property is improved by using the component (C ′) is considered to be that the component (C ′) acts as a crosslinking agent for the novolak resin by heating at a temperature of 200 ° C. or higher. In addition, when the component (C ′) is used, the generation of sublimates is less than when a generally used crosslinking agent is used. This is because the component (C ′) easily forms a cross-linkage with the novolac resin, and the generation of low-nucleated substances in the novolac resin and sublimates derived from the uncrosslinked (C ′) component is small. Guessed.
Moreover, since the film formability is improved, even when the film is formed by heating at a relatively low temperature, a lower layer film having excellent organic solvent resistance can be obtained. That is, although it differs depending on the novolak resin used as the component (A ′), when it does not contain the component (C ′), it is preferable to heat at a temperature of about 300 ° C. for sufficient film formation. By containing the component C ′), sufficient film formation can be performed even at a temperature of about 200 ° C., for example.

The molecular weight of the component (C ′) may be 200 or more, preferably 300 or more, and more preferably 500 or more. The larger the molecular weight, the better the film formability.
The upper limit of the molecular weight is not particularly limited, but is preferably 2000 or less, more preferably 1000 or less in consideration of solubility.

  As the component (C ′), more specifically, for example, the following general formula (c′-1) or ((2) proposed as a photosensitive component of a positive photosensitive resin composition in JP-A No. 2002-278062) c′-2).

［式（ｃ’−１）中、Ｄ^１〜Ｄ^４は、それぞれ独立にナフトキノン−１，２−ジアジドスルホニル基または水素原子であって、それらの中の少なくとも１個がナフトキノン−１，２−ジアジドスルホニル基であり；ａ、ｂおよびｃはそれぞれ独立に０〜３の整数である。式（ｃ’−２）中、Ｄ^５〜Ｄ^８は、それぞれ独立にナフトキノン−１，２−ジアジドスルホニル基または水素原子であって、それらの中の少なくとも１個がナフトキノン−１，２−ジアジドスルホニル基であり；ｄ、ｅおよびｆはそれぞれ独立に０〜３の整数である。］

[In Formula (c′-1), D ^{1 to} D ⁴ are each independently a naphthoquinone-1,2-diazidosulfonyl group or a hydrogen atom, and at least one of them is naphthoquinone-1,2 -A diazidesulfonyl group; a, b and c are each independently an integer of 0 to 3; In formula (c′-2), D ^{5 to} D ⁸ are each independently a naphthoquinone-1,2-diazidosulfonyl group or a hydrogen atom, and at least one of them is naphthoquinone-1,2- A diazidosulfonyl group; d, e and f are each independently an integer of 0 to 3; ]

  As the component (C ′), in particular, esterification of bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -3,4-hydroxyphenylmethane and naphthoquinone-1,2-diazide-5-sulfonyl chloride The reaction product is preferable because it has an excellent effect of improving film formability.

As the component (C ′), one type may be used alone, or two or more types may be mixed and used.
The compounding amount of the component (C ′) is preferably 0.5 to 20 parts by mass, more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the component (A ′).

As the resist underlayer film, as an optional component, an additive miscible with the component (A ′) and the like within a range not impairing the effects of the present invention, for example, improvement of coating property and prevention of striation In addition, an additional resin for improving the performance of the lower layer film, a crosslinking agent, a dissolution inhibitor, a plasticizer, a stabilizer, an antihalation agent, and the like may be contained.
Examples of the surfactant include fluorine-based surfactants such as XR-104 (Dainippon Ink Co., Ltd.). These surfactants may be used alone or in combination of two or more.

Moreover, it can be set as the organic solvent solution of the composition for resist lower layer films | membranes by dissolving said each component in organic solvent (S ') (henceforth (S') component).
As the component (S ′), any component can be used as long as each component to be used can be dissolved into a uniform solution. For example, lactones such as γ-butyrolactone; acetone, methyl ethyl ketone, cyclohexanone, methyl-n-amyl ketone , Ketones such as methyl isoamyl ketone and 2-heptanone; polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol; ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate or dipropylene glycol mono Compounds having an ester bond such as acetate, monomethyl ether, monoethyl ether, monopropyl ether of the polyhydric alcohols or the compound having an ester bond Derivatives of polyhydric alcohols such as monoalkyl ethers such as monobutyl ether or compounds having an ether bond such as monophenyl ether [in these, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferred ]; Esters such as cyclic ethers such as dioxane, methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate Anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenetol, butyl phenyl ether, ethylbenzene, diethylbenzene, amylbe Zen, isopropylbenzene, toluene, xylene, cymene, and aromatic organic solvents mesitylene and the like.
Any one of these organic solvents may be used alone, or two or more thereof may be used as a mixed solvent.

  The thickness of the resist underlayer film is preferably 10 to 1000 nm, more preferably 50 to 800 nm, and still more preferably 100 to 600 nm. By setting it within the above range, there are effects such as good sensitivity.

<Resist laminate>
A resist laminated body can be obtained as follows, for example.
First, an organic solvent solution of the resist underlayer film composition is applied on a support with a spinner or the like, and baked to form a resist underlayer film.
The baking conditions are not particularly limited, and may be appropriately set in consideration of the heat resistance of the component (A ′) to be used. For example, when using a novolak resin, 150 to 350 ° C. for 30 to 300 seconds is preferable, and 200 to 300 ° C. for 60 to 180 seconds is more preferable.
When the resist underlayer film composition contains the component (C ′) described above, by performing the baking treatment, resistance to an organic solvent is increased, and a resist composition is applied onto the resist underlayer film by applying a resist composition. Intermixing is less likely to occur when forming the film. Moreover, the resist underlayer film to be formed becomes insoluble in the alkali developer.
Next, the negative resist composition is applied onto the resist underlayer film with a spinner or the like, and pre-baked (post-apply bake (PAB)) for 40 to 120 seconds under a temperature condition of 80 to 150 ° C., preferably By applying for 60 to 90 seconds, a resist film is formed.
Thus, the resist laminated body used in the formation method of the fine hollow body of the present invention by forming a resist film on the resist underlayer film formed on the support using the negative resist composition. Is obtained.

  A fine hollow body can be formed by subjecting the resist laminate to selective exposure using light having a wavelength absorbed by the resist underlayer film. That is, by using the method for forming a fine hollow body of the present invention, in a material system used in thermal lithography, by changing the energy amount during exposure (exposure amount per unit area of the resist film surface) condition, A fine hollow body can be formed.

  In normal thermal lithography, for example, a resist pattern is formed as follows. First, when the resist laminate is selectively exposed, the resist underlayer film absorbs the light and generates heat. This heat is transmitted to the resist film thereon, and the heat acts on the component (B) in the resist film to generate an acid. As a result of cross-linking between the component (A) and the component (C) by the action of the acid, the solubility of the exposed area in the alkaline developer is lowered. On the other hand, since the solubility of the unexposed portion in the alkali developer does not change, a resist pattern can be formed by alkali development. If the amount of energy is too small, the solubility of the exposed area in the alkaline developer is not sufficiently lowered, so that a resist pattern is not formed. If the amount is too large, the resist film expands. Is not formed. For this reason, the exposure conditions such as the amount of energy are usually appropriately determined in consideration of the type of the (B ′) component in the resist underlayer film, the type and thickness of the resist film, the shape of the desired pattern, and the like.

  On the other hand, in the method for forming a fine hollow body of the present invention, the fine hollow body can be formed by performing selective exposure under a higher energy amount condition than in the case of forming a pattern by ordinary thermal lithography. . The energy amount condition for forming the fine hollow body can be appropriately determined in consideration of the component (B ′) in the resist underlayer film, the type of the resist film, the desired pore diameter of the fine hollow body, and the like. For example, a fine hollow body can be formed by performing selective exposure under the condition of an energy amount of 2 to 10 times or more of an energy amount capable of forming a good resist pattern in thermal lithography. When the amount of energy is large, a fine hollow body having a larger pore diameter can be formed better.

  The energy amount condition can be controlled by appropriately adjusting the laser drawing linear velocity and laser power during exposure. Here, the laser drawing linear velocity means a constant exposure length per unit time. Laser power means the irradiation intensity of exposure light. For example, the energy amount can be increased as the laser drawing linear velocity is slower and the laser power is larger. In addition, when the exposure method is a pulse method, the amount of energy can be increased by increasing the duty ratio.

  For example, when the exposure method is a DC line method, the laser drawing linear velocity is set to 3 m / s or less and the laser power is set to 7 mW or more. When the exposure method is a pulse method, the duty ratio is set. By setting the laser drawing linear velocity to 3 m / s or less and the laser power to 7 mW or more, the amount of energy can be made sufficient, so that a fine hollow body can be formed satisfactorily.

  By appropriately adjusting the film thickness of the resist film, fine hollow bodies having various sizes and pore diameters can be formed. For example, a fine hollow body having a vertical height of 40 to 1300 nm can be formed by selectively exposing a resist laminated body having a resist film thickness of 30 to 1000 nm. Since a fine hollow body is formed in the exposure part, when the exposure method is a DC line method, a continuous fine hollow body having a tubular hollow structure can be formed, and the exposure method is a pulse method. In some cases, a fine hollow body having a spherical or elliptical hollow structure can be formed.

The fine hollow body formed by the method for forming a fine hollow body of the present invention is not particularly limited as long as it is obtained by selectively exposing the resist laminate, and is formed from a resist film. It may be formed from both a resist underlayer film and a resist film.
Further, in the resist laminate, by providing a layer that does not dissolve in an alkali developer between the resist film and the resist underlayer film, the exposed portion consists of a fine hollow body made only of the resist film and only the resist underlayer film. A fine hollow body can be formed simultaneously. It is assumed that the layer that does not dissolve in the alkali developer inhibits the fusion of the resist film and the resist underlayer film.
The layer that does not dissolve in the alkali developer is not particularly limited as long as it is a layer made of a composition that is insoluble in the alkali developer, and does not need to have photosensitivity. As such a layer that does not dissolve in an alkali developer, a conventionally known layer such as a hard mask made of a silica-based inorganic or organic film used in the lithography technique can be used.

  Thus, a nano level fine hollow body can be easily formed by the method for forming a fine hollow body of the present invention. The reason why such an effect is obtained is not clear, but the following can be considered. That is, as a result of a large amount of heat being generated from the resist underlayer film by exposure under a high energy amount condition, the resist film and the resist underlayer film, which are organic films, expand, and some organic compounds constituting the film Evaporates to generate gas. It is considered that a fine hollow structure is formed by the effect of such gas generation and membrane expansion. In particular, in the resist film, since the crosslinking reaction between the component (A) and the component (C) proceeds almost simultaneously, the generated gas is collected and a hollow structure is easily formed instead of a foamed structure. Conceivable. In addition, the resist underlayer film does not cause a cross-linking reaction unlike the resist film, but by selectively exposing to a very narrow area, the heat generation location is limited to a very small area. It is thought that it is easy to form.

  In the method for forming a fine hollow body of the present invention, after performing selective exposure, the resist laminate is treated with an alkaline developer, for example, 0.05 to 10% by mass, as is performed in ordinary thermal lithography. The development treatment can also be carried out preferably using a 0.05 to 3% by mass aqueous tetramethylammonium hydroxide solution. By this development treatment, the resist composition whose solubility in an alkaline developer has not changed can be dissolved and removed.

  Moreover, the fine hollow body of a desired shape can be formed by performing selective exposure. For example, when exposure is performed by the DC line method, a fine structure having a tubular hollow structure arranged in parallel on a support is formed. In addition, for example, when a pattern having a sufficiently long space portion (a portion having no pattern) is formed, that is, when a pattern having a sufficiently wide interval between patterns is formed, unexposed by performing development processing. Since the portions are removed, tubular microstructures separated one by one are formed. On the other hand, when a pattern having a short space portion is formed, since the adjacent tubular structures are fused on the side surfaces, a fine structure having a plurality of parallel tubular structures can be formed. Any of the above patterns can be formed by changing the pitch size and adjusting the width of the space portion. The pitch means the sum of the space width and the pattern width.

≪Micro hollow body≫
Since the micro hollow body formed by using the method for forming a micro hollow body of the present invention is a very fine hollow body, it can be used for manufacturing micro devices in various fields such as chemistry, biotechnology, medicine, food, and chemical conversion. Can be used. For example, a fine hollow body having a tubular hollow structure obtained by exposure by a DC line method can be used as it is as a microchannel. For this reason, it has a fine hollow structure such as a microtunnel or a microtube without requiring a complicated process of adhering a substrate on which a concave microchannel having a conventional structure is bonded to another flat plate substrate. A microdevice such as a microreactor can be formed. In particular, the nano-sized micro hollow body formed by the method for forming a micro hollow body of the present invention can be used as it is as a nanochannel.

  In addition, by performing selective exposure, it is possible to freely form a micro hollow body that functions as a micro flow path, particularly a nano flow path, on a support, and thus the degree of freedom in designing a micro device such as a bioreactor. Is expected to expand dramatically.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.
[Production Example 1] (Preparation of composition 1 for resist underlayer film)
100 parts by mass of the following (A′1-1) component, 10 parts by mass of the following (C′-1) component, and 0.06 parts by mass of a surfactant XR-104 (manufactured by Dainippon Ink & Chemicals, Inc.) Then, 190 parts by mass of PGMEA was mixed and dissolved to prepare a lower layer film solution.
Next, 100 parts by mass of the solution for the lower layer film, 28 parts by mass of a commercially available yellow dye CH-1002 (manufactured by Daitokemix Co., Ltd.), and 280 parts by mass of PGME were mixed and dissolved to prepare a resist underlayer film composition 1. .
Component (A′1-1): A novolak resin [M-cresol: mixture of m-cresol and p-cresol having an Mw of 20000 and a low nucleus content of 500 mass% or less of 0.9 mass%. p-cresol = 6: 4 (mass ratio)) and formaldehyde are condensed in a conventional manner in the presence of an oxalic acid catalyst, and an Mw 12000 novolac resin is dissolved in methanol at room temperature to obtain 15% by mass. A precipitate obtained by adding a solution twice as much water as methanol. ].
(C′-1) component: esterification reaction of bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -3,4-hydroxyphenylmethane and naphthoquinone-1,2-diazide-5-sulfonyl chloride Product.

[Production Example 2] (Preparation of negative resist composition 1)
The following (A-1) component 100 parts by mass, the following (B-1) component 3 parts by mass, the following (C-1) component 10 parts by mass, the following (D-1) component 0.2 part by mass, A negative resist composition 1 was prepared by mixing and dissolving 0.1 part by mass of surfactant XR-104 (manufactured by Dainippon Ink & Chemicals, Inc.) and 1400 parts by mass of PGME.
Component (A-1): Formula (A-1) below [wherein, 1 / m / n = 50/17/33 (molar ratio). A resin having a mass average molecular weight of 6000 represented by the formula:
(B-1) Component: Compound (acid generator) represented by the following formula (B-1).
(C-1) Component: A compound (melamine-based crosslinking agent) represented by the following formula (C-1).
(D-1) Component: Triethanolamine.

[Production Example 3] (Production of resist laminate 1)
Using a spin coater (manufactured by MIKASA), the resist underlayer film composition 1 prepared in Production Example 1 is applied onto a quartz substrate and heated on a hot plate at 230 ° C. for 90 seconds to form an underlayer film having a thickness of 300 nm. did. Then, on this resist underlayer film, a hard mask forming material HM-31 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied, heated on a hot plate at 250 ° C. for 90 seconds, and dissolved in an alkali developer having a film thickness of 50 nm. A non-performing layer (silica coating) was formed. Furthermore, the negative resist composition 1 prepared in Production Example 2 was applied onto the layer that did not dissolve in the alkaline developer, and heated at 90 ° C. for 90 seconds on a hot plate to form a resist film having a thickness of 350 nm. A resist laminate 1 was obtained.

[Example 1]
In the nano-processing apparatus NEO-500 (manufactured by Pulstec Industrial Co., Ltd.), the resist laminate 1 obtained in Production Example 3 is subjected to blue laser light (semiconductor laser wavelength 405 nm) from the resist film side as shown in Table 1. Irradiated selectively depending on exposure conditions. More specifically, in the DC line method, exposure was performed using a line and space pattern having a line width of 160 nm and a pitch of 1200 nm as a target, and in the pulse method, exposure was performed using a dot and space pattern having a dot width of 200 nm and a pitch of 1200 nm as a target. Note that the pitch means the sum of the space width (portion where there is no pattern) and the pattern width. Then, PEB (post-exposure heating) treatment is performed at 110 ° C. for 90 seconds, and further development processing is performed at 23 ° C. with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 30 seconds. At 100 ° C. for 60 seconds.

  In Table 1, “CLV” indicates the laser drawing linear velocity, “LD Power” indicates the laser power, “Freq” indicates the laser modulation pulse, and “Level” indicates the exposure method.

The resist laminate surface was observed using a scanning electron microscope (SEM).
As a result, among the samples 1 to 16 exposed by the pulse method, only the sample 1 exposed under the exposure conditions where the duty ratio is 30%, the laser drawing linear velocity is 3 m / s, and the laser power is 7 mW is a fine hollow body. Was formed. FIG. 1 is an SEM photograph of a cross section of Sample 1. In sample 1, a hollow structure having a spherical hollow structure with a diameter of about 500 nm was formed in a dot shape on the resist film.
On the other hand, among samples 17 to 28 exposed by the DC line method, a fine hollow body was formed only in sample 25 exposed under exposure conditions of a laser drawing linear velocity of 3 m / s and a laser power of 7 mW. FIG. 2 is an SEM photograph of a cross section of the sample 25. In sample 25, hollow structures having a plurality of parallel tubular structures were respectively formed above and below the layer not dissolved in the alkali developer. In particular, a tubular structure (microtunnel) formed from a resist film on a layer that does not dissolve in an alkali developer has a width of about 600 nm and a height of about 450 nm, and can be used as a nanochannel. Met.
Therefore, it is clear from the results of Example 1 that a fine hollow body can be easily formed by using the method for forming a fine hollow body of the present invention.

2 is an SEM photograph of a cross section of Sample 1 obtained in Example 1. 2 is a SEM photograph of a cross section of a sample 25 obtained in Example 1.

Claims (10)

  Select a resist laminate having a resist underlayer film that absorbs light of the wavelength of an exposure light source used in thermal lithography between the support and the resist film, using light of the wavelength absorbed by the resist underlayer film. A method for forming a fine hollow body, which comprises performing a general exposure.   The method for forming a fine hollow body according to claim 1, wherein the resist film is a resist film formed using a negative resist composition.   The negative resist composition comprises a base component (A) whose solubility in an alkaline developer is reduced by the action of an acid, an acid generator component (B) that generates an acid by heat, and a crosslinking agent component (C). The method for forming a fine hollow body according to claim 2, which is a negative resist composition to be contained.   The resist underlayer film is an organic film containing an organic compound (A ') having film forming ability and a dye (B') that absorbs light having a wavelength of an exposure light source used in thermal lithography. The method for forming a fine hollow body according to claim 3. The formation method of the fine hollow body as described in any one of Claims 1-4 which performs selective exposure on condition of following (1), (2), (3).
(1) Exposure method: DC line method (2) Laser drawing linear velocity: 3 m / s or less (3) Laser power: 7 mW or more The formation method of the fine hollow body as described in any one of Claims 1-4 which performs selective exposure on condition of following (1), (2), (3).
(1) Exposure method: Pulse method (however, the duty ratio is 30% or more)
(2) Laser drawing linear velocity: 3 m / s or less (3) Laser power: 7 mW or more   The said resist laminated body is a resist laminated body which has a layer which is not melt | dissolved in an alkali developing solution between the said resist underlayer film and the said resist film, Formation of the fine hollow body as described in any one of Claims 1-6 Method.   The fine hollow body formed using the formation method of the fine hollow body as described in any one of Claims 1-7.   The microreactor which has the fine hollow body formed using the formation method of the fine hollow body as described in any one of Claims 1-7.   The nanochannel which has a fine hollow body formed using the formation method of the fine hollow body as described in any one of Claims 1-7.

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