JP2013218308A - Method for purifying developing solution, purified developing solution and method for forming resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying a developing solution, which can suppress generation of a development defect in a resist pattern and improve a yield in manufacturing a semiconductor device.SOLUTION: A method for purifying a developing solution essentially comprising an organic solvent is provided, the developing solution to be used for forming a negative pattern by using a chemically amplified resist composition. The method for purifying a developing solution is carried out by using a filtration device having a filter (I) having a pore diameter of 0.05 μm or less, and by circulating the developing solution in the filtration device to pass through the filter (I) at least twice.

Description

  The present invention relates to a developer purification method, a purified developer, and a resist pattern forming method.

  Along with miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, miniaturization of resist patterns in lithography processes is required. At present, a fine resist pattern having a line width of about 90 nm can be formed by using, for example, an ArF excimer laser, but further fine pattern formation will be required in the future.

  On the other hand, the so-called immersion exposure, in which the projection lens and the wafer are filled with a high-refractive-index liquid for exposure, uses the same exposure wavelength light source as in the case of using a shorter wavelength light source. Resolution can be achieved. Therefore, immersion exposure is used as a technique for achieving high resolution while reducing an increase in cost in the manufacture of semiconductor elements that require a large capital investment.

  As a technique for further enhancing the resolution, a double exposure technique and a double patterning technique using the characteristics of a chemically amplified resist material are known. Further, as a technique for increasing the resolution without increasing the number of steps using an existing apparatus, a technique using a developer whose main component is an organic solvent having a polarity lower than that of an alkaline aqueous solution is disclosed (for example, JP, A 2008-292975, JP 2008-309878, and JP 2008-309879). It is difficult to form a fine pattern due to poor optical contrast when forming a trench pattern or a hole pattern using an alkaline aqueous solution as a developer, but when an organic solvent is used, This is because a fine pattern can be formed because the optical contrast can be increased.

  In such a lithography process, as the demand for miniaturization increases, in order to suppress a decrease in the yield of semiconductor device manufacturing, further improvement for development defects is required. In particular, when development is performed using a developer containing the organic solvent as a main component, it is expected that the amount used will need to be reduced due to problems such as cost and environment.

  In addition, when forming a positive pattern of a chemically amplified resist composition using a general-purpose alkaline water-soluble developer, it is generally expected that foreign substances with high polarity will be removed together with the developer. Control of the amount of foreign matter is not strictly required. On the other hand, when using a developer containing an organic solvent as a main component, unlike a general-purpose alkaline water-soluble developer, it is difficult to be removed together with the developer. As a result, it is considered that a developer containing an organic solvent as a main component is strongly required to reduce the amount of foreign matter per volume used, particularly a highly polar foreign matter, compared to a conventionally used alkaline water-soluble developer. .

JP 2008-292975 A JP 2008-309878 A JP 2008-309879 A

  The present invention has been made based on the above-described circumstances, and its object is to provide a developer purification method capable of suppressing the occurrence of development defects in a resist pattern and improving the yield of semiconductor device manufacturing. Is to provide.

The invention made to solve the above problems is
A method for purifying a developer that is used in a method of forming a negative pattern using a chemically amplified resist composition and that contains an organic solvent as a main component,
Using a filtration device having a filter medium (I) with a pore size of 0.05 μm or less,
It is a method for purifying a developing solution, wherein the filtering material (I) is passed twice or more by circulating the developing solution in the filtration device.

  The purified developer of the present invention is purified by the developer purification method.

The resist pattern forming method of the present invention comprises:
Forming a resist film using the chemically amplified resist composition;
A step of exposing the resist film, and a step of forming a negative pattern by developing using the purified developer.

  According to the developer purification method, purified developer, and resist pattern forming method of the present invention, development defects (residue defects, particle defects, etc.) are less likely to occur, and a resist pattern useful for microfabrication can be formed. The yield of semiconductor device manufacturing can be improved.

It is a schematic diagram which shows an example of the filtration apparatus used for the refinement | purification method of the developing solution concerning this invention. It is a schematic diagram which shows the other example of the filtration apparatus used for the purification method of the developing solution which concerns on this invention. It is a schematic diagram which shows the further another example of the filtration apparatus used for the refinement | purification method of the developing solution which concerns on this invention. It is a schematic diagram which shows the further another example of the filtration apparatus used for the refinement | purification method of the developing solution which concerns on this invention. It is a schematic diagram which shows the further another example of the filtration apparatus used for the refinement | purification method of the developing solution which concerns on this invention. It is a schematic diagram which shows the further another example of the filtration apparatus used for the refinement | purification method of the developing solution which concerns on this invention.

[Developer Purification Method]
The developing solution purification method of the present invention is applied to a developing solution mainly composed of an organic solvent used in a method of forming a negative pattern using a chemically amplified resist composition. In the purification method, a filter device having a filter medium (I) having a pore size of 0.05 μm or less is used, and the developer is circulated in the filter device, whereby the filter medium (I) is passed twice or more.

  According to the purification method, it is possible to efficiently remove hardly soluble or insoluble foreign matters such as foreign matters (for example, carboxylates), particles, and metal impurities having high polarity in the developer. As a result, it is considered that development defects caused by poorly soluble or insoluble foreign matters, development defects caused by the interaction between the foreign matters in the developer and the resist pattern, and the like can be suppressed.

  Specifically, according to the purification method, the number of particles having a particle size of 0.15 μm or more contained in the developer can be, for example, 20 particles / mL or less, 10 particles / mL or less, and even 5 particles. / ML or less is also possible.

  According to the purification method, when the amount of particles contained in the developer is evaluated by the amount of wet particles, the amount of particles having a particle size of 0.10 μm or more can be set to 180 pcs / wf or less. For example, after depositing a specified amount of developer on a substrate and spinning it off at a specified number of revolutions, the wet particle amount is further dried at a specified number of revolutions, and then the number of defects on the substrate is determined by KLA-Tencor. This is a value (pcs / wf: number of foreign matter per wafer) obtained by measurement using a defect detection device such as a bright field inspection device.

  Further, according to the purification method, the amount of metal impurities in the developer can be, for example, 20 ppb or less, or 10 ppb or less, and further 5 ppb or less. Here, the amount of metal impurities in the developer is a value obtained by measurement using, for example, ICP-MS (Inductively Coupled Plasma Mass Spectrometer).

  As described above, since the number of particles and the amount of metal impurities in the developer can be within the above ranges, development defects such as residue defects and particle defects generated during development can be appropriately suppressed.

  Here, the “residue defect” refers to a defect in which components in the resist composition remain undissolved. This residual defect occurs mainly in a space portion where the resist film has been removed by development. In the purification method, the developer can be purified to such an extent that the number of residual defects can be reduced to at least 20 pcs / wf or less, and in many cases, 10 pcs / wf or less. The number of residual defects here is a value measured using a defect detection device such as a bright field inspection device manufactured by KLA-Tencor.

  On the other hand, the “particle defect” refers to a defect caused by particles such as metal impurities, or foreign matter generated by the interaction between the particle and a component in the resist composition. This particle defect occurs mainly in a pattern portion where the resist composition remains without being removed by development or the space portion. In the purification method, the developer can be purified to such an extent that the number of particle defects can be reduced to at least 100 pcs / wf or less, and in many cases to 50 pcs / wf or less. The number of particle defects here is a value measured using a defect detection device such as a bright field inspection device manufactured by KLA-Tencor, for example, as with the residual defects.

  The purification method can provide a purified developer capable of keeping the number of residual defects and the number of particle defects within the above ranges, so that the generation of so-called Bridge defects can be suppressed. Here, the “Bridge defect” refers to a defect in which foreign matter exists in a space portion removed by development, and the foreign matter bridges between remaining line patterns that are not removed after development. . This Bridge defect is mainly caused by a foreign substance having a high polarity and hardly soluble in the developer. If there are many such Bridge defects, an electrical short-circuit may occur when a device energization test is performed after the etching process. Therefore, by providing a purified developer capable of reducing the number of residual defects and the number of particle defects as in the purification method, it is possible to reduce the occurrence of processability defects during etching of the substrate, leading to an improvement in yield. it can.

<Filtration device>
The filtration device has a configuration in which the developer can be circulated twice or more by the filter medium (I) by circulating the developer, and is configured as shown in FIGS.

  1A includes a filtration unit 11 and three-way valves B1 and B2. The filtration device 1A can filter the developer in a batch manner by circulating the developer using power such as a pump.

  The filtration unit 11 has a filter medium (I) having a pore diameter of 0.05 μm or less. Details of the filter medium (I) will be described later.

  The three-way valve B1 switches between a state in which an unfiltered developer is supplied to the filtration unit 11 and a state in which the developer that has been filtered and circulated by the filtration unit 11 is supplied to the filtration unit 11.

  The three-way valve B2 switches between a state in which the developer filtered by the filtration unit 11 is discharged as a purified developer and a state in which the developer filtered by the filtration unit 11 is circulated and supplied to the filtration unit 11. .

  The three-way valves B1 and B2 are not particularly limited, and various known three-way valves can be used.

  In such a filtration apparatus 1A, the developer filtered by the filtration unit 11 can be circulated and supplied to the filtration unit 11 by appropriately switching the three-way valves B1 and B2, so that the filtration unit 11 (filter medium (I)) is used. Multiple filtrations are possible. In addition, by appropriately switching the three-way valves B1 and B2, the number of times that the developer is filtered by the filtration unit 11 (filter medium (I)) can be appropriately selected. The number of times of filtration is, for example, 2 to 20 times, preferably 2 to 10 times, and more preferably 2 to 7 times. If the number of times of filtration is out of the above range, the effect corresponding to the number of times is poor, and the filtration efficiency tends to deteriorate.

  2 is configured such that a part of the developer filtered by the filtration unit 11 is discharged as a purified developer, and the remaining developer can be circulated to the filtration unit 11. In the filtration unit 11, supply, circulation, and discharge of the developer are selected by three valves B3, B4, and B5. Specifically, the valve B3 selects whether or not to supply unfiltered developer to the filtration unit 11. The valve B4 selects whether or not to discharge the developer filtered by the filtration unit 11 as a purified developer. The valve B5 is used to select whether or not to circulate the developer filtered by the filtration unit 11 to the filtration unit 11.

  In such a filtering device 1B, the developer is not filtered batchwise like the filtering device 1A, and a part of the developer is continuously discharged, so that the purification efficiency of the developer is improved. Is possible.

  The filtration device 1C of FIG. 3 is configured by arranging two filtration units 11 and 12 in the main flow path from the three-way valve B1 to the three-way valve B2. The filtration unit 11 is the same as the filtration unit 11 of the filtration device 1 of FIG. 1, but the filtration unit 12 has a configuration different from that of the filtration unit 11. Specifically, the filtration unit 12 has the filter medium (II), and is disposed on the downstream side of the filtration unit 11 (filter medium (I)). Although details of the filter medium (II) will be described later, the filter medium (I) of the filtration unit 11 is at least different in pore diameter or material.

  In such a filtering device 1C, foreign substances in the developer that could not be removed by the filter medium (I) can be more effectively removed by the filter medium (II). As a result, the number of circulations when purifying the developer can be reduced, and the filtration efficiency can be improved.

  4 has a filtration unit 12 arranged in a circulation channel. Even in such a filtering device 1D, foreign substances in the developer that could not be removed by the filter medium (I) can be more effectively removed by the filter medium (II), and as a result, the filtration efficiency can be improved. Become.

  The filtration device 1E in FIG. 5 is configured such that a filtration unit 12 is disposed between two filtration units 11. The filtration device 1F in FIG. 6 is configured by arranging a filtration unit 11 between two filtration units 12. In such filtration devices 1E and 1F, since the number of filtration units 11 and 12 is large, the number of times the developer is circulated can be reduced, and thus the filtration efficiency is improved.

  Of course, the filtration devices 1A to 1F shown in FIGS. 1 to 6 are examples, and various modifications can be made without departing from the spirit of the present invention. For example, one filter medium (I) or filter medium (II) is arranged in each of the filtration units 11 and 12, but a plurality of identical or different filter media may be arranged in one filtration unit. Further, the arrangement and number of the filtration units 11 and 12 can be variously changed in addition to the illustrated form as long as at least two times of filtration can be performed by the filter medium (I) by circulating the developer. Furthermore, the developer circulation mode, the valve configuration, and the like can be changed.

<Filter medium (I) and filter medium (II)>
The filter medium (I) and the filter medium (II) are different from each other. Typically, the filter medium (I) and the filter medium (II) are different in at least one of the pore diameter and the constituent material.

  As described above, the filter medium (I) and the filter medium (II) have a pore diameter of 0.05 μm or less. As a hole diameter of filter medium (I) and filter medium (II), 0.01 micrometer or more and 0.04 micrometer or less are preferable, and 0.01 micrometer or more and 0.02 micrometer or less are more preferable. If the pore size of the filter medium (I) and the filter medium (II) is too small, the pressure required for the filtration of the developer is increased and the filtration efficiency is deteriorated, and the filter medium (I) is easily clogged and the filtration efficiency. Gets worse. On the other hand, if the pore sizes of the filter medium (I) and the filter medium (II) are too large, there is a possibility that foreign matters having a small particle diameter cannot be sufficiently removed.

  The filter medium (I) and the filter medium (II) are preferably made of polyamide, polyethylene, polypropylene or polytetrafluoroethylene, and more preferably made of polyamide. By using the filter medium (I) and the filter medium (II) formed of these materials, it is possible to effectively remove foreign substances with high polarity that easily cause residue defects and particle defects.

  The critical surface tension of the filter medium (I) and the filter medium (II) is preferably 70 mN / m or more, more preferably 95 mN / m or less, and particularly preferably 75 mN / m or more and 85 mN / m or less. In addition, the value of critical surface tension is a manufacturer's nominal value. By using the filter medium (I) and the filter medium (II) having a critical surface tension in the above range, it is possible to effectively remove foreign substances with high polarity that are likely to cause residue defects and particle defects.

  The filter medium (I) is incorporated into a filtration apparatus as a filtration unit such as a filtration funnel. For example, a “P-nylon filter made of polyamide (pore diameter 0.02 μm, critical surface tension 77 mN / m) is used as such a filtration unit. (Made by Nippon Pole Co., Ltd.), “PE / clean filter (pore size 0.02 μm)” made of high-density polyethylene; (made by Nippon Pole Co., Ltd.), and “PE · clean filter (pore size 0.01 μm) ) ”; (Nippon Pole Co., Ltd.) can be used.

<(Unpurified) developer>
A developing solution (unpurified developing solution) to be purified is used for forming a negative pattern using a chemically amplified resist composition, and contains an organic solvent as a main component.

  The organic solvent that is the main component of the developer is preferably at least one selected from the group consisting of ester solvents and ketone solvents. Here, the “main component” means containing 50% by mass or more, preferably containing 80% by mass or more.

  Examples of the ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec sec -Butyl, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, acetoacetic acid Methyl, ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol acetate Cole mono-n-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, diacetic acid Glycol, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate , Diethyl malonate, dimethyl phthalate, diethyl phthalate and the like.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-amyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl. Examples include ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, acetophenone, and the like.

  Of these, butyl acetate, methyl-n-amyl ketone, methyl isoamyl ketone, n-butyl acetate, isopropyl acetate, amyl acetate, methyl ethyl ketone, methyl-n-butyl ketone are preferred, butyl acetate, methyl-n-amyl ketone, methyl isoamyl ketone Is more preferable. These organic solvents may be used alone or in combination of two or more.

  The developer may contain an alcohol solvent, an ether solvent, an amide solvent, a hydrocarbon solvent, water, silicon oil, and the like in addition to the ester solvent and the ketone solvent.

  Examples of alcohol solvents include monoalcohol solvents and polyhydric alcohol solvents.

  Examples of the ether solvent include diethyl ether, dipropyl ether, dibutyl ether, tetrahydrofuran, dioxane, diphenyl ether, methoxybenzene and the like.

  Examples of the amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, N-methylpyrrolidone and the like can be mentioned.

  Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents and aromatic hydrocarbon solvents.

  An appropriate amount of a surfactant can be added to the developer as necessary. As the surfactant, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used.

[Purified developer]
The purified developer is obtained by purifying the unpurified developer by the purification method.

  The purified developer has a reduced amount of foreign matter compared to the unpurified developer, but the composition other than the amount of foreign matter is the same as that of the unpurified developer described above. The purified developer is purified by the purification method so that, for example, the number of particles having a particle size of 0.15 μm or more is 20 particles / mL or less, preferably 10 particles / mL or less, more preferably 5 particles / mL or less. It is said that. When the purified developer is evaluated by the wet particle amount, it is preferable that the amount of particles having a particle size of 0.10 μm or more is 180 pcs / wf or less. The amount of metal impurities in the purified developer is, for example, 20 ppb or less, preferably 10 ppb or less, and more preferably 5 ppb or less.

  According to the refined developer, since the amount of particles and foreign matters such as metal impurities are reduced, it is possible to effectively suppress development defects when the resist film is developed.

[Resist pattern formation method]
The resist pattern forming method includes a step of forming a resist film using a chemically amplified resist composition (hereinafter referred to as “resist film forming step”) and a step of exposing the resist film (hereinafter referred to as “exposure step”). And a step of forming a negative pattern by developing using the purified developer (hereinafter referred to as “development step”).

<Resist film formation process>
This resist film forming step is performed by applying a chemically amplified resist composition on a substrate to form a resist film. The details of the chemically amplified resist composition used in the resist film forming step will be described later. This composition is a compound that reduces the solubility in the purified developer containing an organic solvent as a main component by the action of [A] acid. And a [B] radiation sensitive acid generator.

  Before performing the resist film formation step, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448 is formed on the substrate in advance. Also good. Moreover, after apply | coating the said resist composition to a board | substrate, you may volatilize the solvent in a coating film by prebaking (PB) as needed.

  Furthermore, a protective film can be provided on the resist layer after the resist film is formed. Examples of the protective film include those for preventing the influence of basic impurities and the like contained in the environmental atmosphere (see, for example, JP-A-5-188598), [B] a radiation sensitive acid generator from a resist film, and the like. For example, a liquid immersion protective film (see, for example, JP-A-2005-352384). Both of these protective films may be formed on the resist layer.

<Exposure process>
In this exposure step, exposure is performed by reducing and projecting a desired region of the resist film formed in the resist formation step through a mask having a specific pattern and, if necessary, an immersion liquid. The exposure may be performed twice or more depending on a desired pattern and a mask pattern.

  The radiation used for exposure is appropriately selected according to the type of [B] radiation-sensitive acid generator. Examples of radiation in this case include ultraviolet rays, far ultraviolet rays, X-rays, and charged particle beams. Of these radiations, far ultraviolet rays emitted from an excimer laser typified by an ArF excimer laser or a KrF excimer laser (wavelength 248 nm) are preferable. The exposure conditions such as the exposure amount are appropriately selected according to the composition of the resist composition, the type of additive, and the like.

  In addition, post-exposure baking (PEB) is preferably performed after exposure of the resist film. By performing PEB, the dissociation reaction of the acid dissociable group in the resist composition can proceed smoothly.

<Development process>
The development step is a step of forming a resist pattern by performing development using the purified developer after exposure of the resist film. By using a purified developer containing at least one selected from an ester solvent and a ketone solvent, the low-exposed portion and the unexposed portion can be selectively dissolved and removed.

  In the resist pattern forming method, the polarity of the polymer is increased particularly by the action of an acid by using the purified developer in a method for forming a negative pattern using the resist composition. For this reason, it is considered that the polymer present in the pattern portion having reduced solubility in the purified developer sufficiently suppresses the interaction with foreign substances having high polarity. As a result, the yield of semiconductor devices can be improved by suppressing the occurrence of defects.

[Chemically amplified resist composition]
As described above, the chemically amplified resist composition contains [A] a polymer whose solubility in a developer containing an organic solvent as a main component is reduced by the action of an acid, and [B] a radiation-sensitive acid generator. Furthermore, you may contain another component in the limit which does not impair the effect of this invention. Hereinafter, each component will be described in detail.

<[A] polymer>
[A] The polymer preferably has the structural unit (I) as a structural unit containing an acid-dissociable group. Here, the “acid-dissociable group” is a group that replaces a hydrogen atom in a polar functional group such as a carboxyl group, and is dissociated by the action of an acid generated from a radiation sensitive acid generator [B] upon exposure. Meaning a group. [A] Since the polymer has a structural unit containing an acid-dissociable group, the number of polar functional groups such as carboxyl groups is increased by exposure, and the polarity of the polymer as a whole increases. A good resist pattern can be formed by reducing the solubility in the developer contained therein.

  In addition to the structural unit (I), the [A] polymer preferably has a structural unit (II) containing a lactone-containing group or a cyclic carbonate-containing group (hereinafter referred to as “structural unit (II)”). And a structural unit (III) having a hydrophilic functional group (hereinafter referred to as “structural unit (III)”). [A] The polymer may have one or more of each structural unit. Hereinafter, each structural unit will be described.

(Structural unit (I))
[A] The polymer preferably has, as the structural unit (I), a structural unit derived from a (meth) acrylic acid ester having an acid dissociable group, and the structural unit represented by the following formula (1) is More preferred.

In the formula (1), R ¹ is hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^p is an acid dissociable group.

Group as the acid dissociable group represented by R ^p represented by the following formula (i) are preferred.

In said formula (i), R ^<p1> is a C1-C4 alkyl group or a C4-C20 monovalent alicyclic hydrocarbon group. R ^p2 and R ^p3 are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. R ^p2 and R ^p3 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atoms to which they are bonded.

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-4).

In the above formulas (1-1) to (1-4), R ¹ has the same meaning as the above formula (1). R ^p1 , R ^p2 and R ^p3 are as defined in the above formula (i). n _p is an integer of 1 to 4.

  As a structural unit represented by the said Formula (1) or (1-1)-(1-4), the structural unit represented by a following formula is mentioned, for example.

In the above formula, ^{R 1} has the same meaning as the above formula (1).

  [A] In the polymer, the content of the structural unit (I) is preferably 30 mol% or more and 60 mol% or less with respect to all the structural units constituting the [A] polymer. By setting the content of the structural unit (I) in the above range, a contrast sufficient for pattern formation can be obtained.

(Structural unit (II))
[A] When the polymer has the structural unit (II), the adhesion of the resist film to the substrate can be improved. Here, the lactone-containing group of the structural unit (II) represents a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The cyclic carbonate-containing group of the structural unit (II) represents a cyclic group containing one ring (cyclic carbonate ring) containing a bond represented by —O—C (O) —O—. The lactone ring or cyclic carbonate ring is counted as the first ring, and if it has only a lactone ring or cyclic carbonate ring, it is called a monocyclic group, and if it has another ring structure, it is called a polycyclic group regardless of the structure. .

  As structural unit (II), the structural unit represented, for example by a following formula is mentioned.

In the above formula, R ^L1 represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  [A] In the polymer, the content of the structural unit (II) is preferably 30 mol% or more and 60 mol% or less with respect to all the structural units constituting the [A] polymer. By making the content rate of structural unit (II) into the said range, the adhesiveness of the resist pattern formed from the said chemically amplified resist composition further improves.

(Structural unit (III))
Examples of the “structural unit (III)” include structural units represented by the following formulae.

In the above formula, R ² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  [A] In the polymer, the content of the structural unit (III) is preferably 0 mol% or more and 30 mol% or less, and preferably 0 mol% or more and 20 mol% with respect to all the structural units constituting the [A] polymer. % Or less is more preferable.

  [A] The polymer may further have one or more structural units other than the structural units described above.

<[A] Polymer Synthesis Method>
[A] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

  [A] The weight average molecular weight (Mw) of the polymer by gel permeation chromatography (GPC) is preferably 1,000 or more and 100,000 or less, more preferably 1,000 or more and 50,000 or less, and 1,000. More preferably, it is 30,000 or less. [A] By making Mw of a polymer into the said range, dry etching resistance and a resist pattern cross-sectional shape can be improved.

<[B] Radiation sensitive acid generator>
[B] The radiation sensitive acid generator generates an acid upon exposure, and the acid dissociates an acid dissociable group present in the polymer [A] to generate a carboxyl group or the like. As a result, the [A] polymer becomes hardly soluble in the developer.

  [B] Examples of the radiation sensitive acid generator include onium salt compounds, N-sulfonyloxyimide compounds, halogen-containing compounds, diazoketone compounds, and the like. Of these [B] radiation-sensitive acid generators, onium salt compounds are preferred.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

  Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexyl Phenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldipheny Sulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2 -Yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, trifer Rusulfonium 1,1-difluoro-2- (2-adamantaneoxycarbonyl) -ethane-1-sulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantane carbonyloxy) -hexane Examples include -1-sulfonate. Of these, triphenylsulfonium 1,1-difluoro-2- (2-adamantanoxycarbonyl) -ethane-1-sulfonate and 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate are preferred.

  Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona. Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophene Ni-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate , 1- (6-n-butoxynaphthalen-2-yl) Trahydrothiophenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1 , 2,2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoro L-methanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro- n-octanesulfonate, 1- (3 -Dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl- 4-hydroxyphenyl) tetrahydrothiophenium camphorsulfonate and the like.

  Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethanesulfonate, diphenyliodonium camphorsulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, Bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2 1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t- butylphenyl) iodonium camphorsulfonate, and the like.

  Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy). ) Bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2 , 3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept- 5-ene-2,3-dicarboximide, N- (2- (3-tetracyclo [4.4.0.12,5.17,10] dodecanyl) -1,1-difluoroethane Sulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-di Carboximide etc. can be mentioned.

  These [B] radiation sensitive acid generators may be used alone or in combination of two or more. [B] The amount of the radiation-sensitive acid generator used is usually 0.1 parts by mass or more and 20 parts by mass with respect to 100 parts by mass of the polymer [A] from the viewpoint of ensuring sensitivity and developability as a resist. Part or less, preferably 0.5 part by mass or more and 15 parts by mass or less. In this case, when the amount of the [B] radiation-sensitive acid generator used is less than the above-mentioned parts by mass, the sensitivity and developability tend to decrease. On the other hand, if it exceeds 15 parts by mass, the transparency to radiation decreases. Thus, it tends to be difficult to obtain a desired resist pattern.

<[C] polymer>
The [C] polymer is a polymer having a higher fluorine atom content than the [A] polymer, and when the resist film is formed, its distribution depends on the oil-repellent characteristics of the [C] polymer in the film. Is a polymer that tends to be unevenly distributed on the surface layer of the resist film. For this reason, it is preferable that an acid generator, an acid diffusion controller, and the like are prevented from being eluted into the immersion medium during immersion exposure.

  [C] The polymer is not particularly limited as long as it has the above properties, but preferably has a fluorinated alkyl group.

  [C] The polymer is formed by polymerizing at least one monomer containing a fluorine atom in the structure. Examples of the monomer containing a fluorine atom in the structure include those containing a fluorine atom in the main chain, those containing a fluorine atom in the side chain, and those containing a fluorine atom in the main chain and the side chain.

  [C] The structural unit for imparting a fluorine atom to the polymer is not particularly limited, but is a structural unit represented by the following formula (F1) (hereinafter also referred to as “structural unit (FI)”). Is preferably used as the fluorine-providing structural unit.

In the formula (F1), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a single bond or a divalent linking group. R ⁴ is a linear or branched alkyl group having 1 to 6 carbon atoms having at least one fluorine atom, or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof.

  Examples of the divalent linking group represented by A in the formula (F1) include an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylamide group, and a urethane group. .

  The said [C] polymer may contain only 1 type of this structural unit (FI), and may contain 2 or more types. The content of the structural unit (FI) is usually 5 mol% or more, preferably 10 mol% or more, and more preferably 15 mol% or more with respect to all the structural units in the [C] polymer. If the content of the structural unit (FI) is less than 5 mol%, a receding contact angle of 70 degrees or more may not be achieved, or elution of an acid generator or the like from the resist film may not be suppressed.

  [C] In addition to the structural unit having a fluorine atom in the structure, the polymer includes, for example, a structural unit having an acid dissociable group for controlling the dissolution rate in a developer, a lactone skeleton, and a cyclic carbonate. “Other structures such as structural units having a skeleton, a hydroxyl group, a carboxyl group, etc., or structural units having an alicyclic group, or structural units derived from aromatic compounds in order to suppress light scattering due to reflection from the substrate, etc. One or more “units” can be contained.

  As the other structural unit having an acid dissociable group, the same as the structural unit (I) of the polymer [A] (hereinafter, also referred to as “structural unit (F-II)”) can be used. .

  As the other structural unit containing the lactone skeleton or the cyclic carbonate skeleton, those similar to the structural unit (II) of the polymer [A] can be used. (Hereinafter also referred to as “structural unit (F-III)”)

  The content of the [C] polymer contained in the solid content (component excluding the solvent) of the chemically amplified resist composition is preferably 1% by mass to 10% by mass, and more preferably 1.5% by mass to 8% by mass. Is more preferable, and 2 mass% or more and 3 mass% or less are still more preferable. By setting the content of the [C] polymer in the above range, the pattern formability in immersion exposure can be further improved.

<[C] Polymer Synthesis Method>
[C] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

<[D] solvent>
[D] The solvent is not particularly limited as long as it can dissolve at least the above-mentioned [A] polymer, [B] radiation-sensitive acid generator, [C] polymer, and optional components added as necessary. Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and mixed solvents thereof.

  In addition to the [A] polymer, the [B] radiation sensitive acid generator, the [C] polymer, and the [D] solvent, the chemically amplified resist composition includes other solvents as long as the effects of the present invention are not impaired. [E] An acid diffusion controller, a surfactant, an alicyclic skeleton-containing compound, a sensitizer, and the like can be contained as components.

<[E] Acid diffusion controller>
The [E] acid diffusion controller controls the diffusion phenomenon of the acid generated from the [B] radiation-sensitive acid generator upon exposure in the resist film, and has the effect of suppressing undesirable chemical reactions in non-exposed areas. By containing such an acid diffusion controller, the resolution as a resist is further improved, and the change in the line width of the resist pattern due to fluctuations in the holding time (PED) from exposure to heat treatment after exposure is suppressed. Can do.

  [E] Examples of the acid diffusion controller include tertiary amine compounds, other amine compounds, amide group-containing compounds, urea compounds, and other nitrogen-containing heterocyclic compounds. In addition, these can be used individually by 1 type or in combination of 2 or more types.

  Further, as the acid diffusion controller, a photodegradable base that is exposed to light and generates a weak acid by exposure can also be used.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measuring method of various physical property values is shown below.

<Synthesis of polymer>
The monomers used for the synthesis of [A] polymer and [C] polymer are shown below.

<[A] Synthesis of polymer>
[Synthesis Example 1]
12.8 g (50 mol%) of the above compound (M-1), 3.6 g (10 mol%) of the above compound (M-3) and 13.6 g (40 mol%) of the above compound (M-4) A monomer solution was prepared by dissolving in 60 g of butanone and further dissolving 1.3 g (5 mol%) of AIBN. Next, a 200 mL three-necked flask charged with 30 g of 2-butanone was purged with nitrogen for 30 minutes, and then the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared above was added to the flask using a dropping funnel. It was added dropwise over time. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower, poured into 600 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was slurried with 150 g of methanol, washed twice, then filtered again and dried at 50 ° C. for 17 hours to obtain a white powder polymer (A-1).

[Synthesis Example 2]
10.5 g (45 mol%) of the above compound (M-1), 5.7 g (15 mol%) of the above compound (M-2) and 13.8 g (40 mol%) of the above compound (M-5) A monomer solution prepared by dissolving in butane (60 g) and further dissolving 1.1 g (2 mol%) of AIBN was prepared and used in the same manner as in Synthesis Example 1 to obtain a white powder polymer (A-2). .

<Synthesis of [C] polymer>
[Synthesis Example 3]
10.4 g (30 mol%) of the above compound (M-6) and 19.6 g (70 mol%) of the compound (M-7) are dissolved in 60 g of 2-butanone, and 1.6 g (8 mol%) of AIBN is further dissolved. The monomer solution prepared was prepared and used in the same manner as in Synthesis Example 1 to obtain a white powder polymer (C-1).

<Preparation of chemically amplified resist composition>
Each component ([B] radiation sensitive acid generator, [D] solvent, and [E] constituting the chemically amplified resist composition other than the [A] polymer and [C] polymer synthesized in the above synthesis example. The acid diffusion controller is shown below.

([B] Radiation sensitive acid generator)
B-1: Compound represented by the following formula (B-1) B-2: Compound represented by the following formula (B-2)

([D] solvent)
D-1: Propylene glycol monomethyl ether acetate D-2: Cyclohexanone D-3: γ-butyrolactone

([E] acid diffusion controller)
E-1: Compound represented by the following formula (E-1) E-2: Compound represented by the following formula (E-2)

<Preparation of chemically amplified resist composition>
[Preparation Example 1]
100 parts by mass of polymer (A-1), 11.6 parts by mass of radiation sensitive acid generator (B-1), 3 parts by mass of polymer (C-1), 2,220 parts by mass of solvent (D-1) , 950 parts by mass of solvent (D-2), 30 parts by mass of solvent (D-3), and 1.8 parts by mass of compound (E-1) were mixed to obtain a uniform solution. Then, the chemically amplified resist composition (J-1) was prepared by filtering using a membrane filter having a pore diameter of 200 nm. The solid content concentration (total concentration of components other than the solvent) of the chemically amplified resist composition (J-1) was 3.5% by mass.

[Preparation Example 2]
100 parts by mass of polymer (A-2), 8.5 parts by mass of radiation sensitive acid generator (B-2), 3 parts by mass of polymer (C-1), 2,220 parts by mass of solvent (D-1) , 965 parts by mass of the solvent (D-2), 30 parts by mass of the solvent (D-3), and 4.5 parts by mass of the compound (E-2) were mixed to obtain a uniform solution. Then, the chemically amplified resist composition (J-2) was prepared by filtering using a membrane filter having a pore diameter of 200 nm. The solid content concentration (total concentration of components other than the solvent) of the chemically amplified resist composition (J-2) was 3.5% by mass.

<Purification of developer>
The developer was purified under the conditions shown in Table 1.

[Example 1]
Butyl acetate (BA) was used as a filter medium with a polyamide Ultiplez P-nylon filter (manufactured by Nippon Pole Co., Ltd., pore size 20 nm, critical surface tension 77 mN / m), filtration pressure 0.10 MPa, flow rate 600 mL / min. Filtration was performed to obtain a purified developer.

[Example 2]
A purified developer was obtained in the same manner as in Example 1 except that the number of filtrations was changed to 7.

[Example 3]
A purified developer was obtained in the same manner as in Example 1 except that the number of filtrations was changed to 10.

[Example 4]
Using butyl acetate as a filter medium, a high-density polyethylene (HDPE) PE / clean filter (manufactured by Nippon Pole Co., Ltd., pore size 10 nm) was filtered twice with a filtration pressure of 0.10 MPa and a flow rate of 500 mL / min to obtain a purified developer .

[Example 5]
Polybutyl pleated P-nylon filter (made by Nippon Pole Co., Ltd., pore diameter 20 nm, critical surface tension 77 mN / m) and PE / clean filter made of high-density polyethylene (HDPE) made of butyl acetate as a filter medium. Two types of products (manufactured by company, pore size: 10 nm) were used and filtered twice with a filtration pressure of 0.10 MPa and a flow rate of 600 mL / min to obtain a purified developer.

[Example 6]
High-density polyethylene (HDPE) PE / clean filter (Nippon Pole Co., Ltd., pore diameter 20 nm) and PE / clean filter (high-density polyethylene (HDPE) P. clean filter (Nippon Pole Co., Ltd., pore size 10 nm) with different pore sizes as the filter medium Were used and filtered twice with a filtration pressure of 0.10 MPa and a flow rate of 500 mL / min to obtain a purified developer.

[Example 7]
A purified developer was obtained in the same manner as in Example 5 except that butyl acetate was changed to methyl-n-amyl ketone (MAK) and the number of filtrations was changed to 7.

[Comparative Example 1]
Using butyl acetate as a filter medium, a high-density polyethylene (HDPE) PE / clean filter (manufactured by Nippon Pole Co., Ltd., pore size: 10 nm) is filtered once at a filtration pressure of 0.10 MPa and a flow rate of 600 mL / min. A liquid was obtained.

[Comparative Example 2]
A purified developer for comparison was obtained in the same manner as in Comparative Example 1 except that butyl acetate was changed to methyl-n-amyl ketone (MAK).

[Comparative Example 3]
Using a high-density polyethylene (HDPE) PE / clean filter (manufactured by Nippon Pole Co., Ltd., pore size 100 nm) as a filter medium, butyl acetate was filtered twice at a filtration pressure of 0.10 MPa and a flow rate of 600 mL / min, and purified for comparison Liquid.

[Comparative Example 4]
A comparative purified developer was obtained in the same manner as in Comparative Example 3 except that the filter medium was changed to a polyamide Ultiplez P-nylon filter (Nippon Pole Co., Ltd., pore size 150 nm).

<Formation of resist pattern>
A composition for forming a lower antireflection film (ARC66, manufactured by Brewer Science) was spin-coated on a 12-inch silicon wafer using a spin coater (CLEAN TRACK Lithius Pro i, manufactured by Tokyo Electron), and then at 205 ° C. for 60 seconds. A coating film having a film thickness of 105 nm was formed by performing PB. Next, the chemical amplification resist composition (J-1) or (J-2) obtained in Preparation Example 1 was spin-coated on the coating film using a clean track (Tokyo Electron, ACT12), After PB at 90 ° C. for 60 seconds, the resist film having a thickness of 90 nm was formed by cooling at 23 ° C. for 30 seconds.

  Next, using an ArF immersion exposure apparatus (NSR-S610C, manufactured by Nikon Seiki Company, immersion liquid: water), optical conditions of NA = 1.3, annular outer sigma / inner sigma = 0.97 / 0.77 Then, exposure was performed under the best focus condition using a mask of 200 nm chromium / 512 nm pitch. Thereafter, PEB is carried out at 105 ° C. for 60 seconds, cooled at 23 ° C. for 30 seconds, then subjected to paddle development with a purified developer for 30 seconds, rinsed with 4-methyl-2-pentanol for 7 seconds, and 40 nm space / 128 nm. A pitch resist pattern was formed.

<Evaluation>
About the resist pattern formed by developing with the refinement | purification developer of Examples 1-7 and Comparative Examples 1-4, the residue defect and the particle defect were evaluated in accordance with the following method. The evaluation results are shown in Table 2. Table 2 also shows the results of measuring the amount of wet particles in the developer used.

[Amount of wet particles]
On the Bare-Si substrate, 20 mL of the purified developer purified by the method described in Examples was added for 30 seconds, spun off at 1000 rpm, and then dried by rotating at 2,000 rpm for 10 seconds. The number of foreign matters having a particle size of 0.10 μm or more on this substrate was measured using KLA2810 manufactured by KLA-TENCOR. The number of foreign particles was the wet particle amount (pcs / wf).

[Residue defects]
The number of defects in the 40 nm space formed by the above method was measured using KLA-TENCOR KLA2810. Furthermore, the defects measured by the KLA2810 were classified, and the defects that remained undissolved in the space were defined as residue defects (pcs / wf).

[Particle defect]
The number of defects in the 40 nm space part or 128 nm pattern part formed by the above method was measured by using KLA2810 manufactured by KLA-TENCOR. Further, the defects measured by the KLA2810 were classified, and the defects remaining as foreign matters in the space portion or pattern portion were defined as particle defects (pcs / wf).

  From the results of Table 2, the filtration was performed twice using Comparative Examples 1 and 2 in which filtration was performed once using a filter medium having a small pore diameter (pore diameter: 10 nm) and a filter medium having a large pore diameter (pore diameter: 100 nm or 150 nm). Further, when the resist was developed using the purified developer of Comparative Examples 3 and 4, the amount of wet particles was large and many residue defects and particle defects occurred.

  On the other hand, when the resist was developed using Examples 1 to 7 filtered using a filter medium having a small pore size (pore size: 10 nm or 20 nm) (2 to 10 times), the amount of wet particles was There were few occurrences of residue defects and particle defects.

  According to the developer purification method, purified developer, and resist pattern forming method of the present invention, development defects (residue defects, particle defects, etc.) are less likely to occur, and a resist pattern useful for microfabrication can be formed. The yield of semiconductor device manufacturing can be improved.

1A, 1B, 1C, 1D, 1E, 1F Filtration device 11, 12 Filtration unit B1, B2 Three-way valve B3, B4 valve

Claims (15)

A method for purifying a developer that is used in a method of forming a negative pattern using a chemically amplified resist composition and that contains an organic solvent as a main component,
Using a filtration device having a filter medium (I) with a pore size of 0.05 μm or less,
A method for purifying a developing solution, wherein the filtering material (I) is passed twice or more by circulating the developing solution in the filtering device.   The method for purifying a developer according to claim 1, wherein the organic solvent contains at least one selected from the group consisting of ester solvents and ketone solvents.   The method for purifying a developer according to claim 1, wherein the organic solvent contains at least one selected from the group consisting of butyl acetate, methyl-n-amyl ketone, and methyl isoamyl ketone.   The method for purifying a developing solution according to claim 1, wherein the filter medium (I) is made of polyamide, polyethylene, polypropylene, or polytetrafluoroethylene.   The method for purifying a developer according to claim 4, wherein the filter medium (I) is made of polyamide.   The method for producing a developer according to any one of claims 1 to 5, wherein the pore size of the filter medium (I) is 0.01 µm or more and 0.04 µm or less.   The method for purifying a developing solution according to claim 6, wherein the pore size of the filter medium (I) is 0.01 µm or more and 0.02 µm or less.   The method for purifying a developer according to any one of claims 1 to 7, wherein the filter medium (I) has a critical surface tension of 70 mN / m or more. The filtration device further includes a filter medium (II) disposed at least one of an upstream position and a downstream position of the filter medium (I),
The developer according to any one of claims 1 to 8, wherein the filter medium (II) is made of polyamide, polyethylene, polypropylene, or polytetrafluoroethylene, and has a pore diameter of 0.05 µm or less. Purification method.   The method for purifying a developing solution according to claim 9, wherein the filter medium (II) is formed of a material different from the filter medium (I).   The method for purifying a developer according to claim 9 or 10, wherein the filter medium (II) has a pore size different from that of the filter medium (I). The chemically amplified resist composition is
The developer according to any one of claims 1 to 11, comprising: [A] a polymer whose solubility in the developer is reduced by the action of an acid; and [B] a radiation-sensitive acid generator. Purification method.   The method for purifying a developer according to claim 12, wherein the polymer [A] has a structural unit derived from a (meth) acrylic acid ester having an acid dissociable group.   A purified developer purified by the developer purification method according to any one of claims 1 to 13. Forming a resist film using the chemically amplified resist composition;
A resist pattern forming method comprising: exposing the resist film; and developing a negative pattern by developing using the purified developer according to claim 14.

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