WO2013146715A1 - Pattern forming method - Google Patents

Abstract

The present invention is a pattern forming method having a step for forming a self-assembled film using a self-assembled composition for pattern formation and having a phase separation structure, and a step for removing a phase of the self-assembled film using an organic solvent. The pattern forming method is characterized in that the boiling point of the organic solvent is 100ºC or higher. It is preferred that the organic solvent contains at least one selected from the group consisting of C₇ or higher hydrocarbons and C₇ or higher ethers. Further, It is preferred that the self-assembled composition is a composition containing two or more polymers or a composition containing a block copolymer. Furthermore, before the step for forming a self-assembled film, it is preferred that there is further provided a step for forming an underlayer film on the substrate and a step for forming a prepattern on the underlayer film.

Description

Pattern formation method

The present invention relates to a pattern forming method.

With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, pattern miniaturization in the lithography process is required. Currently, for example, a fine pattern having a line width of about 40 nm can be formed using ArF excimer laser light. However, a finer pattern formation has been required.

In response to the above requirements, several pattern forming methods using so-called self-organized phase separation structures that spontaneously form ordered patterns have been proposed. For example, a method for forming an ultrafine pattern by self-assembly using a block copolymer obtained by copolymerizing a monomer compound having one property and a monomer compound having a different property is known. (See JP 2008-149447 A and JP 2003-218383 A). According to this method, by annealing the composition containing the block copolymer, polymer structures having the same properties tend to gather together, so that a pattern can be formed in a self-aligned manner. Also known are methods for forming a fine pattern by self-organizing a composition containing a plurality of polymers having different properties from each other (Japanese Patent Application Publication No. 2002-519728, US Patent Application Publication No. 2009/0214823). And Japanese Patent Application Laid-Open No. 2010-58403).

In such a pattern forming method by self-organization, a part of phases of the self-organized film is selectively dissolved with an organic solvent to form a pattern. However, when a conventional organic solvent is used, there is an inconvenience that a polymer remains undissolved in a phase to be dissolved, thereby causing development defects.

JP 2008-149447 A JP 2003-218383 A JP-T-2002-519728 US Patent Application Publication No. 2009/0214823 JP 2010-58403 A

The present invention has been made based on the above circumstances, and its object is to provide a pattern forming method capable of reducing the occurrence of development defects by reliably selectively dissolving a part of a phase of a self-assembled film. Is to provide.

The invention made to solve the above problems is
Pattern formation comprising a step of forming a self-assembled film having a phase separation structure using a self-assembled composition for pattern formation, and a step of removing a part of the phase of the self-assembled film using an organic solvent A method,
In the pattern forming method, the boiling point of the organic solvent is 100 ° C. or higher.

According to the pattern forming method of the present invention, the occurrence of development defects can be reduced by using the organic solvent used for removing a part of the phase of the self-assembled film as the specific solvent. This is because the use of a high-boiling organic solvent suppresses the volatilization of the organic solvent during development and suppresses the deposition of some phases of the removed self-assembled film on the pattern. This is presumed to be possible. In addition, according to the pattern forming method, the boiling point of the organic solvent is 100 ° C. or higher, and it is difficult to volatilize. Therefore, the working environment and the like can be improved.

The organic solvent preferably contains at least one selected from the group consisting of hydrocarbons having 7 or more carbon atoms and ethers having 7 or more carbon atoms. By using the organic solvent as the specific solvent, development defects can be further reduced. This is because volatilization of the organic solvent during development is suppressed due to the high boiling point of the specific hydrocarbon and ether, and a part of the phase of the removed self-assembled film is deposited and deposited on the pattern. It is inferred that this can be suppressed.

The self-assembling composition is preferably a composition containing two or more polymers or a composition containing a block copolymer. As a result, a part of the phase of the self-assembled film can be efficiently removed, and as a result, development defects can be reliably reduced.

Before the self-assembled film forming step,
A step of forming a lower layer film on the substrate, and a step of forming a pre-pattern on the lower layer film,
In the self-assembled film forming step, a self-assembled film is formed in a region on the lower film separated by the pre-pattern,
After the above self-assembled film forming step,
It is preferable to further include a step of removing the prepattern.

When the pattern forming method further includes an underlayer film and a pre-pattern, the phase separation of the self-assembled composition can be precisely controlled, and the resulting pattern can be further refined.

The pattern obtained by the pattern forming method of the present invention is preferably a line and space pattern or a hole pattern. Since the pattern forming method uses the above-described method, it is suitable for forming a fine line and space pattern or a hole pattern.

Here, “boiling point” refers to the boiling point at 1 atmosphere. In addition, when using 2 or more types of organic solvents together, boiling point is the main component (component with the largest content rate (mass%) in the components which comprise an organic solvent) among the organic solvents used together. The boiling point of the organic solvent.

According to the pattern forming method of the present invention, the occurrence of development defects in the formed pattern can be reduced. Therefore, the pattern forming method can be suitably used in a lithography process in manufacturing various electronic devices such as semiconductor devices and liquid crystal devices that are required to be further miniaturized.

In the pattern formation method of this invention, it is a schematic diagram which shows an example of the state after forming a lower layer film | membrane on a board | substrate. In the pattern formation method of this invention, it is a schematic diagram which shows an example of the state after forming a pre pattern on a lower layer film. In the pattern formation method of this invention, it is a schematic diagram which shows an example of the state after apply | coating the self-organizing composition for pattern formation to the area | region on the lower layer film | membrane pinched | interposed by the pre pattern. In the pattern formation method of this invention, it is a schematic diagram which shows an example of the state after forming a self-organization film | membrane in the area | region on the lower layer film pinched | interposed by the pre pattern. In the pattern formation method of this invention, it is a schematic diagram which shows an example of the state after removing the one part phase and pre pattern of a self-organization film | membrane.

<Pattern formation method>
The pattern forming method of the present invention comprises:
A step of forming a self-assembled film having a phase separation structure using the self-assembled composition for pattern formation (hereinafter also referred to as “self-assembled film forming step”), and a part of the phase of the self-assembled film Is removed using an organic solvent (hereinafter, also referred to as “removal step”), and preferably, a step of forming a lower layer film on the substrate (hereinafter referred to as “removal step”). A step of forming a pre-pattern on the lower layer film (hereinafter also referred to as a “pre-pattern formation step”), and a step of removing the pre-pattern after the self-assembled film formation step. (Hereinafter also referred to as “pre-pattern removal step”).

Here, “Directed Self-Assembly” refers to a phenomenon in which an organization or structure is spontaneously constructed without being caused only by control from an external factor. In the present invention, a film having a phase separation structure by self-organization (self-organized film) is formed by applying a self-organizing composition for pattern formation onto a substrate and performing annealing or the like. A pattern is formed by removing a part of the phase in the chemical film.

The boiling point of the organic solvent is 100 ° C. or higher. The occurrence of development defects can be reduced by using the organic solvent used for removing a part of the phase of the self-assembled film as the specific solvent. Hereinafter, each step will be described in detail with reference to FIGS.

[Lower layer formation process]
This step is a step of forming a lower layer film on the substrate using the lower layer film forming composition. Thereby, as shown in FIG. 1, a substrate with a lower layer film in which the lower layer film 102 is formed on the substrate 101 can be obtained. A self-assembled film is formed on the lower layer film 102. The phase-separated structure (microdomain structure) of the self-assembled film is based on the interaction between different types of polymers contained in the self-assembling composition for pattern formation or the interaction between each block of the block copolymer. In addition, since it also changes due to the interaction with the lower layer film 102, the structure control is possible by having the lower layer film 102, and a desired pattern can be obtained. Further, when the self-assembled film is a thin film, the transfer process can be improved by having the lower layer film 102.

Examples of the substrate 101 include a silicon wafer and a wafer coated with aluminum.

A commercially available composition for forming an underlayer film can be used as the composition for forming an underlayer film.

The method for forming the lower layer film 102 is not particularly limited. For example, a coating film formed by applying the composition for forming the lower layer film on the substrate 101 by a known method such as a spin coating method is exposed and / or Alternatively, it can be formed by curing by heating. Examples of the radiation used for this exposure include visible light, ultraviolet light, far ultraviolet light, X-rays, electron beams, γ-rays, molecular beams, and ion beams. The temperature at which the coating film is heated is not particularly limited, but is preferably 90 ° C to 550 ° C, more preferably 90 ° C to 450 ° C, and further preferably 90 ° C to 300 ° C. The thickness of the lower layer film 102 is not particularly limited, but is preferably 10 nm to 20,000 nm, and more preferably 20 nm to 1,000 nm. The lower layer film 102 preferably includes an SOC (Spin on carbon) film.

[Pre-pattern forming process]
In this step, as shown in FIG. 2, a prepattern 103 is formed on the lower layer film 102 using a composition for forming a prepattern. The pre-pattern 103 controls the phase separation of the self-assembling composition for pattern formation, and a desired fine pattern can be formed. That is, among the blocks of different polymers or block copolymers contained in the self-assembling composition for pattern formation, a polymer having a high affinity with the side surface of the prepattern (hereinafter referred to as “first polymer”). Or a block having a high affinity with the side surface of the pre-pattern (hereinafter also referred to as “first block”) forms a phase along the pre-pattern and has a lower affinity than the first polymer ( Hereinafter, the block having the affinity lower than that of the first block (hereinafter also referred to as “second block”) forms a phase at a position away from the pre-pattern. As a result, a desired pattern can be formed. Further, the phase separation structure of the self-assembling composition for pattern formation can be finely controlled by the material, length, thickness, shape and the like of the prepattern. The pre-pattern can be appropriately selected according to the pattern to be finally formed, and examples thereof include a line and space pattern and a hole pattern.

As a method for forming the pre-pattern 103, a method similar to a known resist pattern forming method can be used. Further, as the pre-pattern forming composition, a conventional resist film-forming composition can be used. As a specific method for forming the pre-pattern 103, for example, a commercially available chemically amplified resist composition is used and applied onto the lower layer film 102 to form a resist film. Next, a desired region of the resist film is irradiated with radiation through a mask having a specific pattern, and immersion exposure or the like is performed. Examples of the radiation include ultraviolet rays, far ultraviolet rays, X-rays, and charged particle beams. Among these, far ultraviolet rays are preferable, ArF excimer laser light and KrF excimer laser light are more preferable, and ArF excimer laser light is more preferable. Next, after performing post-exposure baking (PEB), development is performed using a developer such as an alkaline developer, and a desired pre-pattern 103 can be formed.

Note that the surface of the pre-pattern 103 may be subjected to a hydrophobic treatment or a hydrophilic treatment. As a specific treatment method, a hydrogenation treatment by exposing to hydrogen plasma for a certain period of time can be cited. By increasing the hydrophobicity or hydrophilicity of the surface of the pre-pattern 103, self-organization of the self-assembling composition for pattern formation can be promoted.

Since the pattern forming method includes the lower layer film and the pre-pattern, the phase separation of the self-assembled composition is precisely controlled, and the resulting pattern can be further refined.

[Self-assembled film formation process]
This step is a step of forming a self-assembled film having a phase separation structure using the self-assembled composition for pattern formation. When the lower layer film and the pre-pattern are not used, the self-assembled composition for pattern formation is directly applied on the substrate to form a coating film, thereby forming a self-assembled film having a phase separation structure. When the lower layer film and the prepattern are used, as shown in FIGS. 3 and 4, a pattern forming self-assembling composition is used to coat the region on the lower layer film 102 sandwiched between the prepatterns 103. In this process, a film 104 is formed, and a self-assembled film 105 having a phase separation structure having an interface substantially perpendicular to the substrate 101 is formed on the lower layer film 102 formed on the substrate 101. That is, by applying a self-assembling composition for pattern formation onto a substrate and performing annealing or the like, the so-called self-organization that promotes the so-called self-organization in which sites having the same properties accumulate and form an ordered pattern spontaneously is promoted. be able to. Thereby, a self-assembled film having a phase separation structure such as a sea-island structure, a cylinder structure, a bicontinuous structure, or a lamella structure can be formed. These phase separation structures are substantially perpendicular to the substrate 101. A phase separation structure having an interface is preferable.

In the case of having a pre-pattern, the phase separation structure is preferably formed along the pre-pattern, and the interface formed by phase separation is more preferably substantially parallel to the side surface of the pre-pattern. For example, when a composition containing two types of polymers is used as the self-assembling composition for pattern formation, the phase 105b of the first polymer is formed along the side surface of the pre-pattern 103 and is adjacent to the phase 105b. Then, the second polymer phase 105a is formed, and a lamellar phase separation structure in which the first polymer phase 105b and the second polymer phase 105a are alternately arranged in this order is formed. Further, when a composition containing a block copolymer is used as the self-assembling composition for pattern formation, the first block is formed in parallel along the pre-pattern 103, and in the following order, the second block and the first block. An alternately arranged lamellar phase separation structure or the like is formed. The phase separation structure formed in this step is composed of a plurality of phases, and the interface formed from these phases is generally perpendicular to the substrate 101, but the interface itself is not necessarily clear. It's okay.

The method for applying the self-assembling composition for pattern formation onto a substrate is not particularly limited, and examples thereof include a method of applying by a spin coating method.

As an annealing method, for example, a method of heating at a temperature of 80 ° C. to 400 ° C. by an oven, a hot plate or the like can be mentioned. The annealing time is usually 30 seconds to 120 minutes, preferably 30 seconds to 90 minutes. The film thickness of the self-assembled film 105 to be formed is preferably 0.1 nm to 500 nm, and more preferably 0.5 nm to 100 nm.

[Removal process]
This step is a step of removing a part of the phase of the self-assembled film 105 using an organic solvent. This removal is performed by an etching process by using a difference in etching rate of each phase separated by self-organization. FIG. 5 shows a state after the phase 105a and the prepattern 103 in the phase separation structure are removed. In addition, the said organic solvent may be used independently and may use 2 or more types together. Moreover, you may irradiate a radiation as needed before the said etching process. This radiation can be appropriately selected according to the type of the self-assembling composition for pattern formation used.

The boiling point of the organic solvent used in the pattern forming method of the present invention is 100 ° C. or higher. As a minimum of the boiling point of this organic solvent, 110 degreeC or more is preferable, 120 degreeC or more is more preferable, and 130 degreeC or more is further more preferable. Moreover, as an upper limit of the boiling point of the said organic solvent, 400 degrees C or less is preferable, 300 degrees C or less is more preferable, 250 degrees C or less is more preferable, 200 degrees C or less is especially preferable.

As the organic solvent, for example,
As chain hydrocarbons, n-octane (boiling point: 125 ° C), n-nonane (boiling point: 150 ° C), n-decane (boiling point: 174 ° C), n-undecane (boiling point: 196 ° C), 2-methylheptane (Boiling point: 116 ° C), 3-methylheptane (boiling point: 118 ° C), 2-methyloctane (boiling point: 140 ° C), 2,2-dimethylhexane (boiling point: 107 ° C), 2,2,5-trimethylhexane (Boiling point: 124 ° C.) and the like;
As alicyclic hydrocarbons, cycloheptane (boiling point: 118 ° C), cyclooctane (boiling point: 149 ° C), cyclononane (boiling point: 178 ° C), cyclodecane (boiling point: 201 ° C), ethylcyclopentane (boiling point: 103 ° C) , Methylcyclohexane (boiling point: 101 ° C), ethylcyclohexane (boiling point: 130 ° C), propylcyclohexane (boiling point: 157 ° C), isopropylcyclohexane (boiling point: 151 ° C), butylcyclohexane (boiling point: 171 ° C), t-butylcyclohexane (Boiling point: 171 ° C), saturated cycloaliphatic hydrocarbons such as cyclooctane (boiling point: 149 ° C), cycloheptene (boiling point: 115 ° C), cyclodecene (boiling point: 232 ° C), 3-methyl-1-cyclohexene (boiling point: 104 ° C), 1,5-cyclooctadiene (boiling point: 151 ° C), 1 3,5 cycloheptatriene (boiling point: 116 ° C.) unsaturated alicyclic hydrocarbons such as;
As ethers, n-hexyl methyl ether (boiling point: 125 ° C.), tert-amyl ethyl ether (boiling point: 102 ° C.), dibutyl ether (boiling point: 140 ° C.), diamyl ether (boiling point: 186 ° C.), diisoamyl ether ( Boiling point: 172 ° C), dialkyl ether such as dihexyl ether (boiling point: 226 ° C), triethylene glycol dimethyl ether (boiling point: 216 ° C), diethylene glycol methyl ethyl ether (boiling point: 176 ° C), diethylene glycol diethyl ether (boiling point: 189 ° C) , Alkylene glycol dialkyl ethers such as diethylene glycol dibutyl ether (boiling point: 255 ° C.), dipropylene glycol dimethyl ether (boiling point: 171 ° C.), ethylene glycol monomethyl ether acetate (boiling point) 145 ° C.), ethylene glycol monoethyl ether acetate (boiling point: 156 ° C.), ethylene glycol monobutyl ether acetate (boiling point: 188 ° C.), propylene glycol monomethyl ether acetate (boiling point: 146 ° C.), propylene glycol monoethyl ether acetate (boiling point: 158 ° C.), alkylene glycol monoalkyl ether acetate such as diethylene glycol monoethyl ether acetate (boiling point: 217 ° C.), allyl butyl ether (boiling point: 117 ° C.), 1,8-cineole (boiling point: 176 ° C.), anisole (boiling point: 155 ° C), ethyl benzyl ether (boiling point: 189 ° C), diphenyl ether (boiling point: 259 ° C), dibenzyl ether (boiling point: 297 ° C), phenetole (boiling point: 170 ° C), etc .;
Carboxylic acid esters include n-butyl acetate (boiling point: 126 ° C), i-butyl acetate (boiling point: 118 ° C), n-pentyl acetate (boiling point: 149 ° C), i-pentyl acetate (boiling point: 142 ° C), propion Propyl acid (boiling point: 122 ° C.), butyl propionate (boiling point: 145 ° C.), etc .;
As ketones, 2-pentanone (boiling point: 101 ° C.), 3-pentanone (boiling point: 102 ° C.), 2-hexanone (boiling point: 127 ° C.), 3-hexanone (boiling point: 123 ° C.), 4-methyl-2-pentanone (Boiling point: 117 ° C), 2-heptanone (boiling point: 149 ° C), 3-heptanone (boiling point: 146 ° C), etc .;
As alcohols, 1-butanol (boiling point: 118 ° C.), 1-pentanol (boiling point: 138 ° C.), 2-pentanol (boiling point: 118 ° C.), 3-pentanol (boiling point: 114 ° C.), 4-methyl- 2-pentanol (boiling point: 134 ° C), 1-hexanol (boiling point: 157 ° C), 2-methyl-2-hexanol (boiling point: 141 ° C), 2-ethyl-1-hexanol (boiling point: 183 ° C), 1 -Heptanol (boiling point: 176 ° C) etc .;
Examples of the carboxylic acid include acetic acid (boiling point: 118 ° C.).

The organic solvent is preferably a hydrocarbon and an ether, more preferably a hydrocarbon having 7 or more carbon atoms and an ether having 7 or more carbon atoms. By using the organic solvent as the solvent, development defects can be further reduced.

The hydrocarbon having 7 or more carbon atoms is preferably an alicyclic hydrocarbon having 7 or more carbon atoms, more preferably a saturated alicyclic hydrocarbon having 7 or more carbon atoms, cycloheptane, propylcyclohexane, isopropylcyclohexane, butylcyclohexane. T-butylcyclohexane, cyclooctane and nonane are more preferred.

The ether having 7 or more carbon atoms is preferably a dialkyl ether having 7 or more carbon atoms, more preferably diamyl ether, diisoamyl ether, or dihexyl ether.

[Pre-pattern removal process]
This step is a step of removing the prepattern. The pre-pattern removal method is not particularly limited, and examples thereof include a method of removing the pre-pattern by an etching process using a difference in etching rate with the formed self-assembled film 105. This pre-pattern removal step can be performed after the self-assembled film forming step, and may be performed before the removal step, at the same time as the removal step or after the removal step. In addition, when performing this pre pattern removal process simultaneously with the said removal process, it is preferable that a pre pattern can be easily removed with the said organic solvent.

Usually, after the process of removing a part of the phase of the self-assembled film using an organic solvent, the substrate is patterned by etching the lower layer film and the substrate using the pattern of the remaining phase as a mask. After the patterning on the substrate is completed, the phase used as a mask is removed from the substrate by a dissolution process or the like, and a finally patterned substrate can be obtained. As the etching method, a method similar to the removal step can be used, and the etching gas and the etching solution can be appropriately selected depending on the material of the lower layer film and the substrate. For example, when the substrate is made of a silicon material, a mixed gas of chlorofluorocarbon gas and SF ₄ can be used. When the substrate is a metal film, a mixed gas of BCl ₃ and Cl ₂ or the like can be used. In addition, the pattern obtained by the said pattern formation method is used suitably for a semiconductor element etc. Furthermore, the said semiconductor element is widely used for LED, a solar cell, etc.

<Self-assembled composition for pattern formation>
The self-assembling composition for pattern formation is a composition that forms a phase separation structure by self-organization. The pattern forming self-assembled composition used in the pattern forming method of the present invention is preferably a composition containing two or more polymers or a composition containing a block copolymer. As a result, a part of the phase of the self-assembled film can be efficiently removed, and as a result, development defects can be reliably reduced.

The preferable pattern-forming self-assembling composition contains, for example, a component comprising two or more polymers or a component comprising a block copolymer (hereinafter also referred to as “[A] polymer component”). Moreover, the said self-organizing composition for pattern formation may contain a [B] solvent as a suitable component. Furthermore, the self-assembling composition for pattern formation may contain other components as long as the effects of the present invention are not impaired. Hereinafter, each component will be described in detail.

<[A] Polymer component>
[A] The polymer component is a polymer component that forms a phase separation structure by self-assembly. This [A] polymer component is a component comprising two or more types of polymers or a block copolymer. Each will be described below.

[Components containing two or more polymers]
The component containing two or more kinds of polymers is not particularly limited as long as the included polymers are incompatible with each other. For example, a component containing polystyrene and a poly (meth) acrylate, polystyrene, Examples include components containing polysiloxane. The polymer of the same kind is obtained by dissolving the polymer component [A] containing such a plurality of polymers in an appropriate solvent, applying the solution to a substrate or the like to form a coating film, and then performing a treatment such as annealing. They aggregate together to form a phase consisting of the same kind of polymer. At this time, phases formed from different types of polymers do not mix with each other, so that a phase separation structure having an ordered pattern in which different types of phases are periodically and alternately repeated can be formed.

Examples of the poly (meth) acrylate ester include poly (meth) acrylate methyl, poly (meth) ethyl acrylate, poly (meth) acrylate propyl, poly (meth) acrylate butyl, and poly (meth) acrylic. Acid phenyl etc. are mentioned. Note that some or all of the hydrogen atoms of the poly (meth) acrylic acid ester may be substituted with a substituent. Of these, methyl poly (meth) acrylate and phenyl poly (meth) acrylate are preferred.

The polysiloxane is not particularly limited as long as it is a polymer having a siloxane bond, but is preferably a hydrolysis condensate of a compound containing a hydrolyzable silane compound. The polysiloxane can be synthesized using a known method. Moreover, you may use a commercial item.

Examples of the hydrolyzable silane compound include:
Examples of the aromatic ring-containing trialkoxysilane include phenyltrimethoxysilane, phenyltriethoxysilane, 4-methylphenyltrimethoxysilane, 4-ethylphenyltrimethoxysilane, 4-hydroxyphenyltrimethoxysilane, 3-methylphenyltrimethoxysilane, 3-ethylphenyltrimethoxysilane, 3-hydroxyphenyltrimethoxysilane, 2-methylphenyltrimethoxysilane, 2-ethylphenyltrimethoxysilane, 2-hydroxyphenyltrimethoxysilane, 2,4,6-trimethylphenyltrimethoxy Silane, 4-t-butoxyphenethyltriethoxysilane, 4-t-butoxyphenyltriethoxysilane, etc .;
As alkyltrialkoxysilanes, methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, methyltri-iso-propoxysilane, methyltri-n-butoxysilane, methyltri-sec-butoxysilane, methyltri-t-butoxy Silane, methyltriphenoxysilane, methyltriacetoxysilane, methyltrichlorosilane, methyltriisopropenoxysilane, methyltris (dimethylsiloxy) silane, methyltris (methoxyethoxy) silane, methyltris (methylethylketoxime) silane, methyltris (trimethylsiloxy) silane , Methylsilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltri-n-propoxysilane, ethyltri-iso-propyl Poxysilane, ethyltri-n-butoxysilane, ethyltri-sec-butoxysilane, ethyltri-t-butoxysilane, ethyltriphenoxysilane, ethylbistris (trimethylsiloxy) silane, ethyldichlorosilane, ethyltriacetoxysilane, ethyltrichlorosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltri-n-propoxysilane, n-propyltri-iso-propoxysilane, n-propyltri-n-butoxysilane, n-propyltri-sec -Butoxysilane, n-propyltri-t-butoxysilane, n-propyltriphenoxysilane, n-propyltriacetoxysilane, n-propyltrichlorosilane, iso-propyltrimethoxysilane, i o-propyltriethoxysilane, iso-propyltri-n-propoxysilane, iso-propyltri-iso-propoxysilane, iso-propyltri-n-butoxysilane, iso-propyltri-sec-butoxysilane, iso-propyl Tri-t-butoxysilane, iso-propyltriphenoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-butyltri-n-propoxysilane, n-butyltri-iso-propoxysilane, n-butyltri- n-butoxysilane, n-butyltri-sec-butoxysilane, n-butyltri-t-butoxysilane, n-butyltriphenoxysilane, n-butyltrichlorosilane, 2-methylpropyltrimethoxysilane, 2-methylpropyltrie Toxisilane, 2-methylpropyltri-n-propoxysilane, 2-methylpropyltri-iso-propoxysilane, 2-methylpropyltri-n-butoxysilane, 2-methylpropyltri-sec-butoxysilane, 2-methylpropyl Tri-t-butoxysilane, 2-methylpropyltriphenoxysilane, 1-methylpropyltrimethoxysilane, 1-methylpropyltriethoxysilane, 1-methylpropyltri-n-propoxysilane, 1-methylpropyltri-iso- Propoxysilane, 1-methylpropyltri-n-butoxysilane, 1-methylpropyltri-sec-butoxysilane, 1-methylpropyltri-t-butoxysilane, 1-methylpropyltriphenoxysilane, t-butyltrimethoxysilane , T Butyltriethoxysilane, t-butyltri-n-propoxysilane, t-butyltri-iso-propoxysilane, t-butyltri-n-butoxysilane, t-butyltri-sec-butoxysilane, t-butyltri-t-butoxysilane, t-butyltriphenoxysilane, t-butyltrichlorosilane, t-butyldichlorosilane and the like;
As alkenyltrialkoxysilanes, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane, vinyltriisopropoxysilane, vinyltri-n-butoxysilane, vinyltri-sec-butoxysilane, vinyltri-t-butoxysilane Vinyltriphenoxysilane, allyltrimethoxysilane, allyltriethoxysilane, allyltri-n-propoxysilane, allyltriisopropoxysilane, allyltri-n-butoxysilane, allyltri-sec-butoxysilane, allyltri-t-butoxysilane, Allyltriphenoxysilane and the like;
Examples of tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-iso-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-t-butoxysilane, and the like;
Tetraarylsilanes such as tetraphenoxysilane;
Examples of epoxy group-containing silanes include 3-oxetanylmethyloxypropyltrimethoxysilane, 3-oxetanylethyloxypropyltrimethoxysilane, and 3-glycidyloxypropyltrimethoxysilane;
Examples of acid anhydride group-containing silanes include 3- (trimethoxysilyl) propyl succinic anhydride, 2- (trimethoxysilyl) ethyl succinic anhydride, 3- (trimethoxysilyl) propyl maleic anhydride, 2- (trimethoxy Silyl) ethyl glutaric anhydride and the like;
Examples of tetrahalosilanes include tetrachlorosilane.

Among these, an aromatic ring-containing trialkoxysilane is preferable, an aromatic ring-containing triethoxysilane is more preferable, and phenyltriethoxysilane, 4-t-butoxyphenethyltriethoxysilane, and 4-t-butoxyphenyltriethoxysilane are further included. preferable.

[A] When the polymer component is a component containing two or more kinds of polymers having polystyrene, the content of the polymer other than polystyrene is 10 parts by mass to 1 part by mass with respect to 100 parts by mass of polystyrene. 1,000 parts by mass, more preferably 20 parts by mass to 500 parts by mass, and still more preferably 50 parts by mass to 200 parts by mass. [A] By setting the content of polystyrene in the polymer component in the above range, a pattern having a finer microdomain structure can be formed.

[Components made of block copolymer]
Examples of the component composed of the block copolymer include a component composed of a block copolymer such as a polystyrene-poly (meth) acrylate block copolymer. Here, the block copolymer will be described below using a polystyrene-poly (meth) acrylate block copolymer as an example.

The polystyrene-poly (meth) acrylate block copolymer exemplified here (hereinafter also referred to as “(a) block copolymer”) has a polystyrene block having a styrene unit and an alkyl (meth) acrylate unit. It is a block copolymer containing a poly (meth) acrylate block.

(A) The block copolymer has a structure in which a plurality of blocks including at least a polystyrene block and a poly (meth) acrylate block are bonded. Each of the blocks has a chain structure of one kind of monomer compound. That is, the polystyrene block has a chain structure of styrene units, and the poly (meth) acrylate block has a chain structure of alkyl (meth) acrylate units. (A) A block copolymer having a plurality of such blocks is dissolved in an appropriate solvent, applied to a substrate or the like to form a coating film, and then subjected to a treatment such as annealing, whereby the same type of blocks are Agglomerate to form a phase consisting of the same type of blocks. At this time, since phases formed from different types of blocks do not mix with each other, a phase separation structure having an ordered pattern in which different types of phases are periodically and alternately repeated can be formed.

(A) The block copolymer may be a block copolymer consisting of only a polystyrene block and a poly (meth) alkyl acrylate block, and in addition to the polystyrene block and the poly (meth) acrylate block, in addition to these. Other block may further be included, but from the viewpoint that a pattern having a finer microdomain structure can be formed, the block copolymer is composed of only a polystyrene block and a poly (meth) acrylate block. Is preferred.

Examples of the (a) block copolymer consisting only of a polystyrene block and a poly (meth) acrylate block include a diblock copolymer, a triblock copolymer, and a tetrablock copolymer.

Examples of the diblock copolymer include a copolymer in which a polystyrene block and a poly (meth) acrylate block are bonded.

Examples of the triblock copolymer include polystyrene block-poly (meth) alkyl acrylate block-polystyrene block, poly (meth) acrylate alkyl block-polystyrene block-poly (meth) acrylate block bonded in this order. A polymer is mentioned.

Examples of the tetrablock copolymer include a copolymer in which a polystyrene block, a poly (meth) acrylate block, a polystyrene block, and a poly (meth) acrylate block are bonded in this order.

Among these, from the viewpoint that a pattern having a desired fine microdomain structure can be easily formed, a diblock copolymer and a triblock copolymer are preferable, a diblock copolymer is more preferable, a polystyrene block and More preferred is a diblock copolymer in which a poly (meth) acrylate alkyl block is bonded.

The above polystyrene block has a styrene unit and can be formed by polymerizing styrene. The alkyl poly (meth) acrylate block has an alkyl (meth) acrylate unit and can be formed by polymerizing an alkyl (meth) acrylate.

As the styrene, a styrene compound in which some or all of the hydrogen atoms of styrene are substituted with substituents can also be used.

Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. In addition, a part or all of the hydrogen atoms of the alkyl (meth) acrylate may be substituted with a substituent. Of these, methyl methacrylate is preferred.

Examples of the other blocks include poly (meth) acrylic blocks other than poly (meth) acrylic acid alkyl blocks, polyvinyl acetal blocks, polyurethane blocks, polyurea blocks, polyimide blocks, polyamide blocks, Examples thereof include an epoxy block, a novolac type phenol block, and a polyester block.

The content ratio of the styrene unit is preferably 10 mol% to 90 mol%, more preferably 20 mol% to 80 mol%, and more preferably 30 mol% to 70 mol% with respect to all the units constituting the block copolymer (a). More preferred is mol%. (A) By making the content rate of the styrene unit in a block copolymer into the said range, the pattern which has a finer micro domain structure can be formed.

<(A) Method for synthesizing block copolymer>
(A) The block copolymer can be synthesized by polymerizing a polystyrene block, a polymethyl methacrylate block, and other blocks other than these in a desired order by, for example, living anion polymerization, living radical polymerization, or the like. .

For example, when synthesizing a block copolymer (a) which is a diblock copolymer composed of a polystyrene block and a polymethyl methacrylate block, first, styrene is polymerized in an appropriate solvent using an anionic polymerization initiator. This forms a polystyrene block. Next, it is connected to a polystyrene block, and methyl methacrylate is polymerized in the same manner to form a polymethyl methacrylate block. In addition, as a formation method of each block, the method of dripping the solution containing a monomer in the reaction solvent containing a polymerization initiator, and making it polymerize, etc. are mentioned, for example. Further, after the above synthesis, a specific structure may be introduced into the terminal of the block copolymer using a terminal treating agent such as 1,2-butylene oxide.

As the solvent used for the polymerization, for example,
As alkanes, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane and the like;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
As aromatic hydrocarbons, benzene, toluene, xylene, ethylbenzene, etc .;
As halogenated hydrocarbons, chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene, etc .;
Examples of saturated carboxylic acid esters include ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate;
As ketones, acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone, etc .;
Ethers such as tetrahydrofuran and dimethoxyethane;
Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol and the like. In addition, you may use these solvents individually or in combination of 2 or more types.

The reaction temperature in the polymerization may be appropriately determined according to the kind of the polymerization initiator, but is usually −150 ° C. to 50 ° C., preferably −80 ° C. to 40 ° C. The reaction time is usually 5 minutes to 24 hours, preferably 20 minutes to 12 hours.

Examples of the polymerization initiator used in the polymerization include alkyl lithium, alkyl magnesium halide, sodium naphthalene, alkylated lanthanoid compounds, and the like. Among these, when polymerizing using styrene and methyl methacrylate as monomers, it is preferable to use alkyllithium.

After completion of the polymerization, (a) the block copolymer is preferably recovered by a reprecipitation method. That is, the target copolymer is recovered as a powder by introducing the reaction solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes may be used alone or in combination of two or more. In addition to the reprecipitation method, (a) the block copolymer may be recovered by removing low molecular components such as monomers and oligomers by a liquid separation operation, a column operation, an ultrafiltration operation, or the like.

(A) The weight average molecular weight (Mw) of the block copolymer by gel permeation chromatography (GPC) is preferably 1,000 to 150,000, more preferably 1,500 to 120,000, and 2,000. More preferable is 100,000. (A) By making Mw of a block copolymer into the said range, the pattern which has a finer micro domain structure can be formed.

(A) The ratio (Mw / Mn) between the Mw and the number average molecular weight (Mn) of the block copolymer is usually 1 to 5, preferably 1 to 3, more preferably 1 to 2, .5 is more preferable, and 1 to 1.2 is particularly preferable. By setting Mw / Mn in the above range, a pattern having a finer and better microdomain structure can be formed.

The block copolymer is exemplified by a polystyrene-poly (meth) acrylate block copolymer, but the block copolymer used in the pattern forming method of the present invention is not limited to this. Absent.

<[B] Solvent>
The self-assembling composition for pattern formation usually contains a [B] solvent. [B] Examples of the solvent include the same solvents as those exemplified in the method for synthesizing the block copolymer (a). Of these, saturated carboxylic acid esters are preferred, and n-butyl acetate is more preferred.

<Other ingredients>
In addition to the above [A] polymer component and [B] solvent, the self-assembling composition for pattern formation may contain other components such as a surfactant as long as the effects of the present invention are not impaired. .
Preferable surfactants include nonionic surfactants, fluorine surfactants, and silicone surfactants. You may use these individually or in combination of 2 or more types.

<Method for Preparing Self-Assembled Composition for Pattern Formation>
The self-assembling composition for pattern formation can be prepared, for example, by mixing [A] a polymer component, a surfactant and the like in a predetermined ratio in a [B] solvent. The solid content concentration of the self-assembling composition for pattern formation is preferably 0.01% by mass to 50% by mass, more preferably 0.05% by mass to 30% by mass, and 0.1% by mass to 10% by mass. Is more preferable. In addition, you may make it prepare the said self-organization composition for pattern formation by filtering with a filter with a hole diameter of about 200 nm after mixing each component.

Hereinafter, examples of the present invention will be described in more detail, but the present invention is not limited to these examples. In addition, each measurement in an Example and a comparative example was performed with the following method.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
Using Tosoh GPC columns (G2000HXL: 2, G3000HXL: 1, G4000HXL: 1), eluent: tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd.), flow rate: 1.0 mL / min, sample concentration: 1.0 mass %, Sample injection amount: 100 μL, detector: differential refractometer, column temperature: Measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under analysis conditions of 40 ° C. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[ ¹ H-NMR analysis]
Analysis was performed using JNM-ECX400 manufactured by JEOL Ltd. and DMSO-d ₆ as a measurement solvent. The content ratio of each structural unit in each polymer was calculated from the area ratio of the peaks corresponding to each structural unit in the spectrum obtained by ¹ H-NMR analysis.

<[A] Synthesis of each polymer constituting polymer component>
Synthesis examples of the polymers used in each Example and Comparative Example are shown below.

[Synthesis Example 1] (Synthesis of polymer (A1-1))
After drying the 1 L flask reaction vessel under reduced pressure, 500 g of cyclohexane subjected to distillation dehydration treatment was injected under a nitrogen atmosphere and cooled to 0 ° C. Next, 4.4 mL of a cyclohexane solution (1.8 mol / L) of n-butyllithium was added, and 40 g of styrene that had been subjected to distillation dehydration treatment was dropped into the vessel over 30 minutes. After ripening for 60 minutes after completion of dropping, 1 g of methanol was added to stop the reaction. The reaction solution was warmed to room temperature, concentrated, and replaced with propylene glycol methyl ether acetate (PGMEA). Thereafter, 1,000 g of a 2% by mass aqueous solution of oxalic acid was added, stirred and allowed to stand, and the lithium salt was removed by repeating the operation of removing the lower aqueous layer three times. Next, 1,000 g of ultrapure water was added and stirred, and the operation of removing the lower aqueous layer was repeated 3 times to remove oxalic acid. Then, this solution was concentrated and dropped into 500 g of n-hexane to form a polymer. Was precipitated. Next, this was filtered under reduced pressure, and this polymer was washed twice with n-hexane and then dried under reduced pressure at 60 ° C. to obtain 10.5 g of a white polymer (A1-1) as polystyrene. Mw of this polymer (A1-1) was 5,000, and Mw / Mn was 1.13.

[Synthesis Examples 2 to 7] (Synthesis of Polymers (A1-2) to (A1-7))
Polymers (A1-2) to (A1-7), which are polystyrenes, were synthesized in the same manner as in Synthesis Example 1 except that the aging time after completion of the styrene addition was changed to the time shown in Table 1. Table 1 shows Mw and Mw / Mn of each polymer obtained.

The hydrolyzable silane compounds (M-1) to (M-3) used for the synthesis of the polymers (A2-1) to (A2-4) are shown below. In the following formula, Et is —CH ₂ —CH ₃ .

[Synthesis Example 8] (Synthesis of Polymer (A2-1))
A maleic acid aqueous solution was prepared by dissolving 5 g of maleic anhydride in 100 g of water by heating. On the other hand, 23.0 g (30 mol%) of (M-1), 34.0 g (70 mol%) of (M-2) and 500 g of propylene glycol monopropyl ether were placed in a flask. And the dropping funnel which put the said maleic acid aqueous solution into this flask was set, and after heating the said flask at 60 degreeC with an oil bath, maleic acid aqueous solution was dripped slowly and it was made to react at 60 degreeC for 4 hours. After completion of this reaction, 1.0 g of concentrated hydrochloric acid was added and reacted at 60 ° C. for 1 hour. Then, after cooling the reaction solution, 500 g of PGMEA was added and set in an evaporator to remove ethanol generated during the reaction. Thereafter, 500 g of water was added to the reaction solution to extract the acid, washed, and concentrated by an evaporator to obtain a polymer (A2-1) which is a polysiloxane. This polymer (A2-1) had a solid content concentration of 15% by mass, Mw of 2,000, and Mw / Mn of 1.13. As a result of ¹ H-NMR analysis, the content ratios of structural units derived from (M-1) and (M-2) were 30 mol% and 70 mol%, respectively. In the present specification, “solid content” means a residue obtained by drying a sample on a hot plate at 175 ° C. for 1 hour to remove volatile substances.

[Synthesis Examples 9 to 11] (Synthesis of Polymers (A2-2) to (A2-4))
Polymers (A2-2) to (A2-) which are polysiloxanes were prepared in the same manner as in Synthesis Example 8 except that the types and amounts of hydrolyzable silane compounds shown in Table 2 were used and the reaction time was changed. 4) was synthesized. Table 2 shows Mw and Mw / Mn of each polymer obtained.

The compounds (M-4) and (M-5) used for the synthesis of the polymers (A2-5) to (A2-8) are shown below.

[Synthesis Example 12] (Synthesis of polymer (A2-5))
5 g of lithium chloride was put into a 1 L flask and dried at 130 ° C. for 12 hours. Then, ultra-dehydrated tetrahydrofuran (THF) was added, and water was removed under reduced pressure. Next, 500 g of THF subjected to distillation dehydration treatment was added under a nitrogen atmosphere and cooled to 0 ° C. Thereafter, 4.4 mL of a sec-butyllithium cyclohexane solution (1.8 mol / L) was added, and 40 g of (M-4) subjected to distillation dehydration was dropped into the cyclohexane solution over 30 minutes. After ripening for 60 minutes after completion of dropping, 1 g of methanol was added to stop the reaction. The solution was then warmed to room temperature, concentrated and replaced with PGMEA. Thereafter, 1,000 g of a 2% by mass aqueous solution of oxalic acid was added, stirred and allowed to stand, and the lithium salt was removed by repeating the operation of removing the lower aqueous layer three times. Next, 1,000 g of ultrapure water was added and stirred, and the operation of removing the lower aqueous layer was repeated 3 times to remove oxalic acid. Then, this solution was concentrated and dropped into 500 g of n-hexane to form a polymer. Was precipitated. Then, this was filtered under reduced pressure, and the polymer was washed twice with n-hexane, and then dried under reduced pressure at 60 ° C., so that a white polymer (A2-5) that is polymethyl methacrylate (PMMA) 10. 5 g was obtained. Mw of this polymer (A2-5) was 4,000, and Mw / Mn was 1.13.

[Synthesis Examples 13 to 15] (Synthesis of Polymers (A2-6) to (A2-8))
(M-4) Polyphenylmethacrylate (PPMA) was prepared in the same manner as in Synthesis Example 12 except that 50 g of (M-5) was used instead of 40 g and the aging time was changed to the time shown in Table 3. Polymers (A2-6) to (A2-8) were synthesized. Table 3 shows Mw and Mw / Mn of each polymer obtained.

<Preparation of self-assembling composition for pattern formation>
[Synthesis Example 16] (Preparation of self-assembling composition for pattern formation (J-1))
[A] 70 parts by mass of the polymer (A1-1) as a polymer component and 30 parts by mass of the polymer (A2-1) were mixed with [B] n-butyl acetate as a solvent (in Table 4, “B-1 The n-butyl acetate solution was prepared so that the concentration of each polymer was 0.75% by mass. Then, the n-butyl acetate solution was filtered through a membrane filter having a pore diameter of 200 nm to prepare a self-assembling composition for pattern formation (J-1).

[Synthesis Examples 17 to 25] (Preparation of self-assembling compositions for pattern formation (J-2) to (J-10))
A self-assembled composition for pattern formation was prepared in the same manner as in Synthesis Example 16 except that the [A] polymer component and the [B] solvent used were as shown in Table 4.

<Pattern formation>
[Example 1]
A composition for forming an organic underlayer film containing a crosslinking agent on a 12-inch silicon wafer was spin-coated using CLEAN TRACK ACT12 (manufactured by Tokyo Electron), and baked at 205 ° C. for 60 seconds to form a 77 nm-thick underlayer. A film was formed. Next, a resist composition containing an acid dissociable resin, a photoacid generator and an organic solvent is spin-coated on this lower layer film, and then pre-baked (PB) at 120 ° C. for 60 seconds to form a resist film having a film thickness of 60 nm. Formed. Next, using an ArF immersion exposure apparatus (NSR S610C, manufactured by Nikon), exposure was performed through a mask pattern under optical conditions of NA; 1.30, CrossPole, and σ = 0.997 / 0.78. Then, PEB was performed at 115 ° C. for 60 seconds, and then developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 30 seconds, washed with water, and dried to form a pre-pattern (diameter 55 nm hole / 110 nm pitch). Obtained. Next, the pre-pattern was irradiated with ultraviolet light of 254 nm under the condition of 150 mJ / cm ² and then baked at 170 ° C. for 5 minutes to obtain an evaluation substrate.
Next, the self-assembling composition for pattern formation (J-1) was applied to the evaluation substrate so as to have a thickness of 15 nm and heated at 120 ° C. for 1 minute to cause phase separation to form a microdomain structure. did. Thereafter, it was immersed in cycloheptane as an organic solvent for 1 minute to remove the polymer (A1-1), thereby forming a hole pattern.

[Examples 2 to 10 and Comparative Examples 1 and 2]
A pattern was formed using each self-assembling composition for pattern formation in the same manner as in Example 1 except that the self-assembling composition for pattern formation and the organic solvent were changed as shown in Table 5.

<Evaluation>
Each pattern formed as described above was evaluated for development defects by the following method. The results are shown in Table 5.

[Development defect evaluation]
The inside of the hole pattern and on the pattern of the formed hole pattern were observed using SEM (S-4800, manufactured by Hitachi, Ltd.) for the presence or absence of undissolved residue, and the observation result was evaluated as development defect evaluation. At this time, when the undissolved residue is not confirmed, the development defect evaluation can be evaluated as good “A”, and when the undissolved residue is confirmed, it can be evaluated as defective “B”.

As can be seen from the results in Table 5, in the development defect evaluation, all of the examples were good, but all of the comparative examples were bad.

The present invention can provide a pattern forming method capable of reducing the occurrence of development defects. Therefore, the pattern forming method can be suitably used in a lithography process in manufacturing various electronic devices such as semiconductor devices and liquid crystal devices that are required to be further miniaturized.

101 Substrate 102 Lower layer film 103 Pre-pattern 105 Self-assembled film 105a Second polymer phase 105b First polymer phase

Claims (5)

1. Pattern formation comprising a step of forming a self-assembled film having a phase separation structure using a self-assembled composition for pattern formation, and a step of removing a part of the phase of the self-assembled film using an organic solvent A method,
   The pattern forming method, wherein the organic solvent has a boiling point of 100 ° C. or higher.
2. The pattern forming method according to claim 1, wherein the organic solvent contains at least one selected from the group consisting of hydrocarbons having 7 or more carbon atoms and ethers having 7 or more carbon atoms.
3. The pattern forming method according to claim 1, wherein the self-assembling composition is a composition containing two or more kinds of polymers or a composition containing a block copolymer.
4. Before the self-assembled film forming step,
   A step of forming a lower layer film on the substrate, and a step of forming a pre-pattern on the lower layer film,
   In the self-assembled film forming step, a self-assembled film is formed in a region on the lower film separated by the pre-pattern,
   After the above self-assembled film forming step,
   The pattern formation method of Claim 1 which further has the process of removing a pre pattern.
5. The pattern forming method according to claim 1, wherein the obtained pattern is a line and space pattern or a hole pattern.

Images