KR102309953B1 - Process for forming resist pattern - Google Patents

Abstract

An object of the present invention is to provide a resist pattern forming method capable of suppressing the occurrence of watermark defects and residue defects.
The present invention provides a step of coating a photoresist composition on the surface of a substrate, a step of laminating a top coating layer on the surface of the photoresist film obtained by the coating step, and an immersion liquid between the top coating layer surface and the projection optical system of the exposure apparatus. A method of forming a resist pattern comprising a step of immersion exposure of the photoresist film through an interposer, and a step of developing the photoresist film, comprising a step of removing a portion of the top coating layer between the immersion exposure step and the developing step do it with It is preferable to perform removal in the said removal process using a peeling liquid.

Description

Resist pattern formation method {PROCESS FOR FORMING RESIST PATTERN}

The present invention relates to a method for forming a resist pattern.

With the miniaturization of structures of various electronic devices such as semiconductor devices and liquid crystal devices, miniaturization of resist patterns in a lithography process is required. In response to such a request, an immersion exposure method in which exposure is performed by filling a space between the lens and the photoresist film with an immersion medium such as pure water or a fluorine-based inert liquid is used. According to this immersion exposure method, the numerical aperture (NA) of a lens can be enlarged, and there exists an advantage that high resolution is obtained.

In the pattern formation method by this immersion exposure method, it is required to suppress the elution of the photoresist film component into the immersion liquid and pattern defects caused by droplets of the immersion liquid remaining on the photoresist film surface. As a technique for satisfying these requirements, forming a top coating layer between a photoresist film and an immersion liquid is being performed (International Publication Nos. 2004/74937, Japanese Patent Application Laid-Open No. 2007-324385, and Japanese Patent Laid-Open No. 2008). -See Publication No. 42019).

International Publication No. 2004/74937 Japanese Patent Laid-Open No. 2007-324385 Japanese Patent Laid-Open No. 2008-42019

When providing such a top coating layer, in order to improve scanning performance, it is performed to increase the water repellency of the surface of a top coating layer. However, if the fluorine content in the top coating layer is increased in order to increase the water repellency of the top coating layer surface, there is a problem in that watermark defects and residue defects are generated in the resist pattern to be formed.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a resist pattern forming method capable of suppressing the occurrence of watermark defects and residue defects.

The invention made to solve the above problems is a process of coating a photoresist composition on the surface of a substrate (hereinafter also referred to as a "coating process"), and a process of laminating a top coating layer on the surface of the photoresist film obtained by this coating process ( Hereinafter, also referred to as a “lamination step”), a step of immersion exposure of the photoresist film by interposing an immersion liquid between the surface of the top coating layer and the projection optical system of an exposure apparatus (hereinafter also referred to as “immersion exposure step”); A resist pattern forming method comprising a step of developing a photoresist film (hereinafter also referred to as a “development step”), and a step of removing a part of the top coating layer between the immersion exposure step and the development step (hereinafter also referred to as a “removal step”) ) is characterized in that it is provided.

According to the resist pattern forming method of the present invention, a resist pattern with few watermark defects and residual defects can be formed. Therefore, the resist pattern forming method can be suitably used in a semiconductor device processing process, etc., which are expected to be further miniaturized in the future.

<Resist pattern formation method>

The resist pattern forming method includes a coating step, a lamination step, an immersion exposure step, and a developing step, and includes a removal step between the immersion exposure step and the developing step.

According to this resist pattern forming method, a resist pattern with few watermark defects and residual defects can be formed. Although the reason why the said resist pattern formation method exhibits the said effect by having the said structure is not necessarily clear, it can estimate, for example as follows. That is, the said resist pattern formation method can suppress the generation|occurrence|production of a watermark defect in the immersion exposure process by providing the process of laminating|stacking a top coating layer on the photoresist film|membrane surface. In addition, after the immersion exposure step and before the developing step, a step of removing a portion of the top coating layer is provided, and from among the polymers constituting the top coating layer, polymers that cannot be completely dissolved in the developer are removed in advance, thereby suppressing the occurrence of residual defects. I think it can In addition, the polymer of the top coating layer that has not been removed by the removal step contributes to suppression of the occurrence of the residue defects, and in the development step, low-solubility polymers in the photoresist film that can cause residue defects, etc. It is thought that it is based on improving the solubility with respect to a developing solution. Hereinafter, each process is demonstrated.

[coating process]

In this process, a photoresist composition is coated on the substrate surface. Thereby, a photoresist film is formed on the substrate surface. As a board|substrate to be used, a silicon wafer, the silicon wafer coat|covered with aluminum, etc. are mentioned normally. In addition, in order to maximize the characteristics of the photoresist film to be formed, it is preferable to form an organic or inorganic antireflection film described in, for example, Japanese Patent Publication No. Hei 6-12452 on the surface of the substrate in advance.

(Photoresist composition)

The type of the photoresist composition is not particularly limited, and it can be appropriately selected from among the photoresist compositions conventionally used for forming the photoresist film according to the purpose of use of the resist. Among them, a photoresist composition containing a polymer containing an acid-dissociable group (hereinafter also referred to as “polymer (P)”) and a radiation-sensitive acid generator (hereinafter also referred to as “acid generator (Q)”) is desirable.

In the polymer (P), examples of the structural unit containing an acid dissociable group (hereinafter also referred to as “structural unit (p)”) include a structural unit represented by the following formula (A).

In said formula (A), R ^P is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^p1 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^p2 and R ^p3 each independently represent a monovalent hydrocarbon group having 1 to 20 carbon atoms, or an alicyclic structure having 3 to 20 reduced numbers formed by combining these groups with the carbon atom to which they are bonded.

Examples of R ^P, in terms of the copolymerizable monomer to give a structural unit (p), the hydrogen atom and methyl group are preferred, and more preferably a methyl group.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and 6 carbon atoms. to 20 monovalent aromatic hydrocarbon groups; and the like.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl group, ethyl group, n-propyl group, i-butyl group and n-butyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic alicyclic hydrocarbon groups such as cyclobutyl group, cyclopentyl group, cyclohexyl group and cyclohexenyl group; Polycyclic alicyclic hydrocarbon groups, such as a norbornyl group, an adamantyl group, norbornenyl group, etc. are mentioned.

As a C6-C20 monovalent|monohydric aromatic hydrocarbon group, For example, Aryl groups, such as a phenyl group, a tolyl group, a xylyl group, and a naphthyl group; Aralkyl groups, such as a benzyl group, a phenethyl group, and a naphthylmethyl group, etc. are mentioned.

Examples of the alicyclic structure having 3 to 20 reduced numbers formed by combining the groups of R ^p2 and R ^p3 together with the carbon atom to which they are bonded include monocyclic alicyclic structures such as a cyclopentane structure, a cyclohexane structure, and a cyclohexene structure; Polycyclic alicyclic structures, such as a norbornane structure, an adamantane structure, and a norbornene structure, etc. are mentioned.

Examples of the structural unit (p) include (meth)acrylates having a 1-alkyl-1-monocyclic alicyclic hydrocarbon group such as 1-ethyl-1-cyclopentyl (meth)acrylate; and structural units derived from (meth)acrylates having a 2-alkyl-2-polycyclic alicyclic hydrocarbon group such as 2-i-propyl-2-adamantyl (meth)acrylate.

The polymer (P) preferably further has, in addition to the structural unit (p), a structural unit (hereinafter also referred to as “structural unit (q)”) containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. do.

As the structural unit (q), for example,

As a lactone structure, a norbornanlactone structure, a butyrolactone structure, etc.;

As a cyclic carbonate structure, an ethylene carbonate structure, a propylene carbonate structure, etc.;

As a sultone structure, the structural unit derived from (meth)acrylic acid ester containing a norbornane sultone structure, a propane sultone structure, etc. are mentioned.

In addition, the polymer (P) may have other structural units other than the structural unit (p) and the structural unit (q). Examples of the other structural unit include a structural unit containing a hydrocarbon group having 4 or more and 20 or less carbon atoms (hereinafter also referred to as "structural unit (r)"), a structural unit containing a polar group such as a hydroxyl group, and the like. Examples of the structural unit (r) include a structural unit derived from tricyclodecanyl (meth)acrylate.

As a lower limit of the content rate of a structural unit (p), 25 mol% is preferable with respect to all the structural units which comprise a polymer (P), and 35 mol% is more preferable. As an upper limit of the said content rate, 60 mol% is preferable and 50 mol% is more preferable. By making the content rate of a structural unit (p) into the said range, the resolution of a photoresist composition can be improved.

As a lower limit of the content rate of a structural unit (q), 20 mol% is preferable with respect to all the structural units which comprise a polymer (P), and 30 mol% is more preferable. As an upper limit of the said content rate, 70 mol% is preferable and 60 mol% is more preferable. By making the content rate of a structural unit (q) into the said range, while being able to adjust suitably the solubility with respect to the developing solution of the photoresist film formed from a photoresist composition, the adhesiveness of a photoresist film and a board|substrate can be improved.

As an upper limit of the content rate of another structural unit, 20 mol% is preferable with respect to all the structural units which comprise a polymer (P), and 15 mol% is more preferable.

The acid generator (Q) is a component that generates an acid upon exposure. It is thought that the acid generated by exposure plays two functions in the said radiation-sensitive composition by the intensity|strength of the acid. As a 1st function, the function which an acid generated by exposure dissociates the acid-dissociable group which the structural unit (p) of a polymer (P) has, and produces a carboxy group etc. is mentioned. The acid generator having this first function is called an acid generator (Q1). As a second function, in the unexposed portion, the acid generator (Q1) does not substantially dissociate the acid dissociable group or the like of the structural unit (p) of the polymer (P) under pattern formation conditions using the radiation-sensitive composition. ) to inhibit the diffusion of acid generated from The acid generator (Q) having this second function is called an acid generator (Q2). The acid generated from the acid generator (Q2) can be said to be a relatively weak acid (an acid with a large pKa) than the acid generated from the acid generator (Q1). Whether the acid generator functions as (Q1) or (Q2) is determined using the energy required for the acid dissociable group of the structural unit (p) of the polymer (P) to dissociate and a radiation-sensitive composition to determine the pattern. It is determined by the thermal energy conditions etc. which are provided at the time of formation. As a content form of the acid generator (Q) in the said radiation-sensitive resin composition, the form of a compound as mentioned later, the form inserted as a part of a polymer, or both these forms may be sufficient.

When the radiation-sensitive resin composition contains the acid generator (Q1), the polarity of the polymer (P) in the exposed portion increases, and the polymer (P) in the exposed portion becomes soluble in the developer in the case of aqueous alkali solution development. , On the other hand, in the case of organic solvent development, it becomes poorly soluble in a developer.

By containing the acid generator (Q2), the radiation-sensitive composition can form a resist pattern excellent in pattern developability and LWR performance.

Examples of the acid generator (Q) include an onium salt compound, a sulfonimide compound, a halogen-containing compound, and a diazoketone compound. Examples of the onium salt compound include a sulfonium salt, a tetrahydrothiophenium salt, an iodonium salt, a phosphonium salt, a diazonium salt, and a pyridinium salt. Among these, a sulfonium salt and an iodonium salt are preferable.

Examples of the acid generated by exposure include those that generate sulfonic acid, carboxylic acid, and sulfonimide by exposure. As these acids,

(1) a compound in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted for carbon atoms adjacent to a sulfo group;

(2) a compound in which a carbon atom adjacent to a sulfo group is not substituted with a fluorine atom or a fluorinated hydrocarbon group

can be heard

As carboxylic acid generated by exposure,

(3) a compound in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted for carbon atoms adjacent to the carboxy group;

(4) a compound in which a carbon atom adjacent to a carboxy group is not substituted with a fluorine atom or a fluorinated hydrocarbon group

can be heard Among these, as the acid generator (Q1), those corresponding to the above (1) are preferable, and those having a cyclic structure are particularly preferable. As the acid generator (Q2), those corresponding to (2), (3) or (4) are preferable, and those corresponding to (2) or (4) are particularly preferable.

In addition to the polymer (P) and the acid generator (Q), the photoresist composition may contain other components such as an acid diffusion control agent (R), a water repellent resin (F), and a surfactant. Examples of the acid diffusion controlling agent (R) include amine compounds such as trioctylamine and triethanolamine; N-t-alkoxycarbonyl-containing amide compounds such as R-(+)-(t-butoxycarbonyl)-2-piperidinemethanol and N-t-butoxycarbonyl-4-hydroxypiperidine; and photodegradable bases such as triphenylsulfonium 10-camphorsulfonate and triphenylsulfonium salicylate. Examples of the water-repellent resin (F) include a fluorine-based resin, and specifically, a resin having a fluorinated hydrocarbon group, a chain perfluoroalkyl polyether, a cyclic perfluoroalkyl polyether, polychlorotrifluoroethylene, poly tetrafluoroethylene, a tetrafluoroethylene-perfluoroalkoxyethylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, etc. are mentioned.

The photoresist composition is prepared, for example, by dissolving a polymer (P), an acid generator (Q) and, if necessary, an acid diffusion controller (R) or the like in a solvent. In addition, as for the photoresist composition, what filtered with a filter with a pore diameter of about 30 nm is used normally. From a viewpoint of coating easiness, 0.2 mass % is preferable as the lower limit, and, as for the solid content concentration of a photoresist composition, 1 mass % is more preferable. As an upper limit of the said solid content concentration, 20 mass % is preferable and 10 mass % is more preferable.

As a coating method of a photoresist composition, conventionally well-known coating methods, such as rotation coating, casting coating, roll coating, etc. are mentioned. After coating a photoresist composition on a board|substrate, in order to volatilize a solvent, you may perform prebaking (PB). As a lower limit of the temperature of the said PB, 50 degreeC is preferable and 70 degreeC is more preferable. As an upper limit of the said temperature, 150 degreeC is preferable and 120 degreeC is more preferable. As a lower limit of the time of the said PB, 10 second is preferable and 30 second is more preferable. As an upper limit of the said time, 600 second is preferable and 300 second is more preferable.

[Lamination process]

In this process, a top coating layer is laminated|stacked on the photoresist film surface obtained by the said coating process. Lamination of this top coating layer is normally performed by coating a top coating composition on the surface of a photoresist film.

(Top Coating Composition)

The top coating composition usually contains a polymer (hereinafter also referred to as “[A] polymer”) and a solvent (hereinafter also referred to as “[B] solvent”). The top coating composition may contain other components, such as surfactant, in addition to the [A] polymer and the [B] solvent.

[A] As the polymer, any polymer capable of forming a top coating layer and subject to immersion exposure can be used. Moreover, it is preferable that the polymer [A] contains 2 or more types of polymers from which a characteristic differs. As a characteristic of this polymer, the dissolution rate with respect to a stripper, the etching rate in dry etching, the receding contact angle in a film-forming state, etc. are mentioned, for example.

[A] As a polymer, a water-repellent resin, an acidic resin, etc. are mentioned, for example. "Water-repellent resin" refers to a resin having a receding contact angle with water of 80° or more in a film-forming state. An "acidic resin" means resin which has a pKa of 10 or less acidic functional group. [A] The polymer may contain other resin than the water-repellent resin and the acidic resin.

Examples of the water-repellent resin include a fluorine-based resin, and specifically, a resin having a fluorinated hydrocarbon group, a chain perfluoroalkyl polyether, a cyclic perfluoroalkyl polyether, polychlorotrifluoroethylene, polytetrafluoro ethylene, a tetrafluoroethylene-perfluoroalkoxyethylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, etc. are mentioned.

As a minimum of the mass content rate of the fluorine atom in a fluorine-type resin, 0.1 mass % is preferable, 1 mass % is more preferable, 5 mass % is still more preferable. As an upper limit of the said mass content, 30 mass % is preferable and 25 mass % is more preferable.

As acidic resin, resin which has an oxo-acid group, resin which has phenolic hydroxyl group, etc. are mentioned, for example. As an oxo acid group, a sulfo group, a carboxy group, etc. are mentioned, for example.

When the top coating composition contains two or more kinds of polymers having different properties as the [A] polymer, it is preferable to have a water repellent resin and an acidic resin as the two or more kinds of polymers.

[B] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

As an alcohol solvent, for example,

Methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert- Pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, 4-methyl-2-pentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n -Octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl monoalcohol solvents such as alcohol, sec-heptadecyl alcohol, furfuryl alcohol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, and diacetone alcohol;

Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, polyhydric alcohol solvents such as 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol;

Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethyl butyl ether, diethylene glycol mono Methyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene Polyhydric alcohol partial ether solvents, such as glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, and dipropylene glycol monopropyl ether, etc. are mentioned.

As an etheric solvent, for example,

dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether and diisoamyl ether;

Aromatic ring containing ether solvents, such as anisole and diphenyl ether;

Cyclic ether solvents, such as tetrahydrofuran and a dioxane, are mentioned.

As a ketone solvent, for example,

Acetone, 2-butanone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-amyl ketone, ethyl-n-butyl ketone, methyl-n- chain ketone solvents such as hexyl ketone, di-iso-butyl ketone, trimethylnonanone, 2,4-pentanedionone, acetonylacetone, and acetophenone;

Cyclic ketone solvents, such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone, etc. are mentioned.

As an amide solvent, for example,

Chain amides such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide menstruum;

Cyclic amide solvents, such as N,N'- dimethylimidazolidinone and N-methylpyrrolidone, etc. are mentioned.

As an ester solvent, for example,

Methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec acetate -pentyl, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate , ethyl propionate, n-butyl propionate, iso-amyl propionate, methyl lactate, ethyl lactate, n-butyl lactate, and n-amyl lactate monocarboxylic acid ester solvents;

Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene acetate polyhydric alcohol partial ether carboxylate solvents such as glycol monoethyl ether, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, and dipropylene glycol monoethyl ether acetate;

carbonate solvents such as dimethyl carbonate, diethyl carbonate, ethylene carbonate, and propylene carbonate;

lactone solvents such as γ-butyrolactone and δ-valerolactone;

dicarboxylic acid ester solvents such as diethyl oxalate, din-butyl oxalate, diethyl malonate, dimethyl phthalate, and diethyl phthalate;

Glycol diacetic acid, methoxytriglycol acetate, etc. are mentioned.

As a hydrocarbon solvent, for example,

Aliphatic such as n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, and methylcyclohexane hydrocarbon-based solvents;

Benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene, n -Aromatic hydrocarbon solvents, such as amylnaphthalene, etc. are mentioned.

[B] As the solvent, an ether solvent, an alcohol solvent and a fluorine solvent are preferable, a dialkyl ether solvent, a monoalcohol solvent and a fluorine-containing amine are more preferable, diisoamyl ether, 4-methyl-2-pentane ol and perfluorotributylamine are more preferred.

The top coating composition is prepared, for example, by dissolving the [A] polymer and, if necessary, other components in the [B] solvent. In addition, as for the top coating composition, what filtered with a filter with a pore diameter of about 30 nm is used normally. The lower limit of the solid content concentration of the top coating composition is preferably 0.2 mass %, more preferably 1 mass %, from the viewpoint of coating easiness. As an upper limit of the said solid content concentration, 20 mass % is preferable and 10 mass % is more preferable.

As a coating method of a top coating composition, the method similar to the coating method of the photoresist composition in the said coating process, etc. are mentioned. It is preferable to perform prebaking (PB) after application of a top coating composition. As a lower limit of the temperature of the said PB, 50 degreeC is preferable and 70 degreeC is more preferable. As an upper limit of the said temperature, 150 degreeC is preferable and 120 degreeC is more preferable. As a lower limit of the time of the said PB, 10 second is preferable and 30 second is more preferable. As an upper limit of the said time, 600 second is preferable and 300 second is more preferable.

(top coating layer)

By removing the [B] solvent from the applied top coating composition, the top coating layer composed of the [A] polymer or the like is formed.

The lower limit of the average thickness of the formed top coating layer is preferably 5 nm, more preferably 10 nm, still more preferably 15 nm. As an upper limit of the said average thickness, 100 nm is preferable, 70 nm is more preferable, and 50 nm is still more preferable.

It is preferable that the average thickness of the top coating layer to be formed approaches as much as possible an odd multiple of λ/4m (λ: wavelength of radiation, m: refractive index of protective film). By doing in this way, the effect of suppressing reflection at the upper interface of the photoresist film can be increased.

It is preferable that the top coating layer contains two or more types of polymers from which characteristics differ, and it is more preferable as said two or more types of polymers to have a water repellent resin and an acidic resin. Moreover, in this case, it is preferable that the polymer removed in a removal process is a water-repellent resin.

[Liquid immersion exposure process]

In this step, immersion exposure of the photoresist film is performed by interposing an immersion liquid between the surface of the top coating layer and the projection optical system of the exposure apparatus. The "projection optical system of an exposure apparatus" refers to an optical device that projects a predetermined pattern toward a photoresist film, including a projection lens or the like. This immersion exposure is performed by disposing an immersion liquid between the top coating layer surface and the projection optical system of the exposure apparatus, usually between the top coating layer surface and the projection lens, and exposing through the immersion liquid.

As the immersion liquid, a liquid having a higher refractive index than that of air is usually used. As the immersion liquid, it is preferable to use water, and it is more preferable to use pure water. Moreover, you may adjust the pH of an immersion liquid as needed. In a state in which the immersion liquid is interposed, that is, in a state in which the immersion liquid is filled between the lens of the exposure apparatus and the photoresist film, exposure light is irradiated from the exposure apparatus, and the photoresist film is exposed through a mask having a predetermined pattern. do.

The exposure light used for this immersion exposure can be appropriately selected according to the type of the photoresist film or the top coating layer, for example, visible light; ultraviolet rays such as g-rays and i-rays; far ultraviolet rays such as excimer laser light; X-rays such as synchrotron radiation; Charged particle beams, such as an electron beam, etc. are mentioned. Among these, far ultraviolet rays are preferable, ArF excimer laser beams (wavelength 193 nm) and KrF excimer laser beams (wavelength 248 nm) are more preferable, and ArF excimer laser beams are still more preferable. In addition, the irradiation conditions of exposure light, for example, exposure amount, etc. can be set suitably according to the compounding composition of a photoresist composition or a top coating composition, the kind of additive contained in these, etc.

After immersion exposure, in order to improve the resolution, pattern shape, developability, etc. of the resist pattern obtained, it is preferable to perform post-exposure baking (PEB). Although the temperature of PEB can be suitably set according to the kind etc. of the photoresist composition and top coating composition used, 50 degreeC is preferable as the lower limit, and 80 degreeC is more preferable. As an upper limit of the said temperature, 200 degreeC is preferable and 150 degreeC is more preferable. As a lower limit of the time of PEB, 5 second is preferable and 10 second is more preferable. As an upper limit of the said time, 600 second is preferable and 300 second is more preferable.

[removal process]

In this step, a part of the top coating layer is removed. A part of the top coating layer to be removed is usually a surface layer of the top coating layer.

When the top coating layer contains two or more types of polymers having different properties, in the removal step, it is preferable to remove at least the polymers localized on the surface side. Further, when the top coating layer has a water-repellent resin and an acidic resin as the two or more types of polymers, it is preferable that the polymer to be removed in the removal step is at least a part of the water-repellent resin.

The method for removing a part of the top coating layer is not particularly limited, and for example, a method of dissolving and removing the surface layer of the top coating layer using a stripper, a method of removing the surface layer of the top coating layer by dry etching, etc. have. Among these, the method of carrying out using a peeling liquid is preferable from a point more easily and adjustment of the part to be removed is easier.

(Removing solution)

As a stripping solution, it has an organic solvent as a main component normally. As a lower limit of the content rate of the organic solvent in a peeling liquid, 50 mass % is preferable, 80 mass % is more preferable, 95 mass % is still more preferable. As an upper limit of the said content rate, it is 100 mass %, for example.

Examples of the organic solvent contained in the stripper include organic solvents similar to those exemplified as the organic solvent contained in the top coating composition. As the stripper, it is preferable to mainly contain an ether-based solvent, a hydrocarbon-based solvent, an alcohol-based solvent and/or a fluorine-based solvent among them.

As the ether solvent, diisoamyl ether and dibutyl ether are preferable.

As the hydrocarbon solvent, decane and cyclohexane are preferable.

As the alcohol solvent, 1-decanol and 4-methyl-2-pentanol are preferable.

As the fluorine-based solvent, perfluoro(2-butyltetrahydrofuran) is preferable.

The stripper may be added to the solvent mainly contained above, and may contain an ester solvent such as propylene glycol monomethyl ether acetate.

It is preferable that the solubility parameter value of the stripper is smaller than the solubility parameter value of the [B] solvent of the top coating composition. By setting the solubility parameter value of the stripper to be within the above range, it is possible to more selectively and efficiently remove portions of the top coating layer that tend to cause defects. Here, the "solubility parameter" can use the value (unit: (MPa) ^1/2 ) described in Polymer Handbook (4th edition) (Wiley, 1999), for example. In addition, when the solvent is a mixed solvent of two types of solvent 1 and solvent 2, the solubility parameter δm is δm=X ₁ ×δ ₁ +(1-X ₁ ) × δ ₂ (δ _{1 )} and δ ₂ are the solubility parameter values of solvent 1 and solvent 2, respectively. X ₁ can be calculated|required by the molar fraction of the solvent 1 in a solvent).

The lower limit of the value obtained by subtracting the solubility parameter value of the stripper from the parameter value of the [B] solvent of the top coating composition is preferably 0.1, more preferably 0.5. As an upper limit of the said subtracted value, 8 is preferable and 5 is more preferable.

As an upper limit of the solubility parameter value of a stripper, 21 is preferable, 19 is more preferable, 18 is still more preferable, and 17 is especially preferable. As a lower limit of the said solubility parameter value, 11 is preferable and 12 is more preferable.

As the stripper, it is preferable to satisfy the following conditions.

Conditions: When the photoresist film is formed on the surface of the substrate, the top coating layer having a thickness of 30 nm is further formed on the surface of the photoresist film, and the stripper is brought into contact with the top coating layer for 60 seconds, the top coating layer has a thickness It dissolves so as to remain 2 nm or more and 28 nm or less.

The lower limit of the ratio of the average thickness of the top coating layer remaining after the removal process to the average thickness of the top coating layer formed in the lamination step (top coating layer residual ratio) is preferably 30%, more preferably 50%, further 60% desirable. The upper limit of the residual ratio of the top coating layer is preferably 90%, more preferably 85%, and still more preferably 80%.

The removal process can be performed at any time point between the liquid immersion exposure process and the image development process. For example, when performing PEB after immersion exposure, any of before PEB, simultaneous with PEB, and after PEB may be used, but from the viewpoint of making the shape of the resist pattern more favorable, after PEB is preferable.

As a method of removing a part of the top coating layer using a stripper, for example, a method in which the stripper is spin-coated on the top coating layer, then left standing for a certain period of time, and then spin-drying is exemplified.

The lower limit of the value (θ1-θ2) obtained by subtracting the receding contact angle θ2 of the top coating layer surface after the removal process from the receding contact angle θ1 of the surface of the top coating layer formed in the lamination step is preferably 10°, more preferably 15°, and 20° is more preferable. As an upper limit of the said value, 65 degrees is preferable, 55 degrees is more preferable, and 35 degrees is still more preferable.

[Development process]

In this step, the photoresist film is developed. This development is performed by bringing the photoresist film exposed by immersion into contact with a developer. Thereby, while removing the part of the top coating layer which was not removed in the removal process, a desired resist pattern can be obtained.

As a developing solution, an alkali developing solution, an organic solvent developing solution, etc. are mentioned, for example.

As an alkali developer, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethyl Amine, dimethylethanolamine, triethanolamine, tetraalkylammonium hydroxides (eg, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, etc.), pyrrole, piperidine, choline, 1,8- The alkaline aqueous solution etc. which melt|dissolved at least 1 sort(s) of alkaline compounds, such as diazabicyclo-[5.4.0]-7-undecene and 1, 5- diazabicyclo-[4.3.0]-5- nonane, are mentioned. Among these, an aqueous solution of tetraalkylammonium hydroxides is preferable, and an aqueous TMAH solution is more preferable.

Examples of the organic solvent developer include the same organic solvents as those exemplified as the organic solvent contained in the stripper. Among them, ether solvents, ketone solvents and ester solvents are preferable, and n-butyl acetate, isopropyl acetate, amyl acetate, anisole, 2-butanone, methyl-n-butyl ketone and methyl-n-amyl ketone are preferable. This is more preferable. These organic solvents may be used independently and may use 2 or more types together.

As a lower limit of content of the organic solvent in an organic solvent developing solution, 80 mass % is preferable, 90 mass % is more preferable, and 99 mass % is still more preferable. When the content of the organic solvent in the organic solvent developer is within the above range, the dissolution contrast between the exposed portion and the unexposed portion can be further improved, and as a result, a resist pattern having excellent lithographic properties can be formed. As a component other than an organic solvent, water, silicone oil, etc. are mentioned, for example.

The developing solution may contain a nitrogen-containing compound. When the developer contains the nitrogen-containing compound, it is possible to further reduce the reduction in the film of the formed resist pattern.

Examples of the nitrogen-containing compound include (cyclo)alkylamines, nitrogen-containing heterocyclic compounds, amide group-containing compounds, and urea compounds.

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

As the developing method, for example, a method of immersing the substrate in a tank filled with a developer for a certain period of time (immersion method), a method of developing by raising the developer on the surface of the substrate by surface tension and stopping for a certain period of time (paddle method), on the surface of the substrate A method of spraying a developer (spray method), a method of continuously extracting a developer while scanning a developer extraction nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispensing method), etc. are mentioned.

It is preferable to include a rinse step of cleaning the photoresist film with a rinse solution after the developing step. As the rinsing liquid in the rinsing step, an organic solvent can be used. By using an organic solvent as a rinse liquid, the generated scum can be washed efficiently.

As the organic solvent used as the rinsing liquid, hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents and amide solvents are preferable. Among these, alcohol solvents and ester solvents are more preferable, and alcohol solvents are still more preferable. Among the alcohol solvents, monohydric alcohol solvents having 6 to 8 carbon atoms are preferable.

Examples of the monohydric alcohol solvent having 6 to 8 carbon atoms include chain monohydric alcohols and cyclic monohydric alcohols, and specifically, 1-hexanol, 1-heptanol, 1-octanol, 4-methyl-2-pentanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, benzyl alcohol, etc. are mentioned. have. Among these, 1-hexanol, 2-hexanol, 2-heptanol and 4-methyl-2-pentanol are preferable.

Each component in a rinse liquid can use 1 type, or 2 or more types. As an upper limit of the moisture content in a rinse liquid, 10 mass % is preferable, 5 mass % is more preferable, 3 mass % is still more preferable. When the moisture content in the rinse liquid is below the upper limit, good developing characteristics can be obtained. In addition, a surfactant may be added to the rinse solution.

As a method of cleaning treatment with a rinse solution, for example, a method of continuously drawing a rinse solution onto a substrate rotating at a constant speed (rotation coating method), a method of immersing the substrate in a bath filled with a rinse solution for a certain period of time ( immersion method), the method of spraying a rinse liquid on the substrate surface (spray method), etc. are mentioned.

[Example]

Hereinafter, the present invention will be more specifically described by way of Examples, but the present invention is not limited to these Examples. Methods for measuring various physical property values are shown below.

<Synthesis of polymer>

The monomers used for the synthesis of the polymer for photoresist composition and the polymer for top coating composition are shown below.

[Synthesis of polymer for photoresist composition]

[Synthesis Example 1] (Synthesis of Polymer 1)

53.93 g (50 mol%) of compound (M-1), 35.38 g (40 mol%) of compound (M-2) and 10.69 g (10 mol%) of compound (M-3) were dissolved in 200 g of 2-butanone and 5.58 g of dimethyl 2,2'-azobis(2-methylpropionate) as a polymerization initiator was further added to prepare a monomer solution. Next, a 500 mL three-necked flask into which 100 g of 2-butanone was added was purged with nitrogen for 30 minutes. After nitrogen purge, the reaction part was heated to 80°C while stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The initiation of dripping was made into polymerization initiation time, and the polymerization reaction was performed for 6 hours. After completion of the polymerization reaction, the polymerization reaction liquid was cooled to 30° C. or lower by cooling with water, then poured into 2,000 g of methanol, and the precipitated white powder was separated by filtration. The white powder separated by filtration was washed twice with 400 g of methanol in a slurry form, separated by filtration and dried at 50° C. for 17 hours to obtain a white powdery polymer 1 (amount 74 g, yield 74%). . Polymer 1 had Mw of 6,900 and Mw/Mn of 1.70. ^As a result of 13 C-NMR analysis, the content of each structural unit derived from (M-1), (M-2) and (M-3) was 53.0 mol%, 37.2 mol%, and 9.8 mol%, respectively. In addition, content of the low molecular-weight component derived from each monomer in the polymer 1 was 0.03 mass %.

[Synthesis Example 2] (Synthesis of Polymer 2)

85 mol% of the compound (M-2) and 15 mol% of the compound (M-4) were dissolved in 200 g of 2-butanone, and 7 mol of azobisisobutyronitrile as a polymerization initiator was added to the total of the compound. % was dissolved to prepare a monomer solution. The total mass of the monomers to be used was 100 g. Next, a 500 mL three-necked flask containing 100 g of 2-butanone was heated to 80° C. while stirring under a nitrogen atmosphere, and the prepared monomer solution was added dropwise over 3 hours. Polymerization reaction was performed by heating at 80 degreeC for further 3 hours after completion|finish of dripping. After completion of the polymerization reaction, the polymerization reaction solution was cooled to room temperature. After transferring the polymerization reaction solution to a separatory funnel, the polymerization reaction solution was uniformly diluted with 300 g of n-hexane, and 1,200 g of methanol was added and mixed. Then, 60 g of distilled water was thrown in, and it stirred and left still for 30 minutes. Next, the lower layer was collect|recovered and the propylene glycol monomethyl ether acetate solution of the polymer 2 was obtained by substituting the solvent with propylene glycol monomethyl ether acetate (yield 79%). Polymer 2 had Mw of 5,200 and Mw/Mn of 1.82. Moreover, as ^{a result of 13} C-NMR analysis, the content rates of each structural unit derived from (M-2) and (M-4) were 85.0 mol% and 15.0 mol%, respectively.

[Synthesis of polymer for top coating composition]

[Synthesis Example 3] (Synthesis of Polymer 3)

A polymerization initiator solution was prepared in which 25.0 g of 2,2-azobis(2-methylisopropionate) as a polymerization initiator was dissolved in 25.0 g of 2-butanone. On the other hand, 133.6 g (50 mol%) of the compound (M-4), 166.4 g (50 mol%) of the compound (M-5) and 2-butanone were placed in a 2,000 mL three-neck flask equipped with a thermometer and a dropping funnel. 575.0 g was added and nitrogen purged for 30 minutes. After nitrogen purge, the inside of the flask was heated to 80°C while stirring with a magnetic stirrer. Then, using a dropping funnel, the prepared polymerization initiator solution was added dropwise over 5 minutes and aged for 6 hours. Then, it cooled to 30 degrees C or less, and obtained the polymerization reaction liquid.

Then, after concentrating the obtained polymerization reaction liquid to 600 g, it transferred to the separatory funnel. 193 g of methanol and 1,542 g of n-hexane were put into this separatory funnel, and separation and purification were performed. After separation, the lower layer was recovered. 117 g of 2-butanone and 1,870 g of n-hexane were added to the recovered lower layer, and separation and purification were performed. After separation, the lower layer was recovered. Further, 93 g of methanol, 77 g of 2-butanone, and 1,238 g of n-hexane were added to the recovered lower layer solution, and separation and purification were performed. After separation, the lower layer was recovered. The recovered lower layer solution was substituted with 4-methyl-2-pentanol, and the solution was washed with distilled water and further substituted with 4-methyl-2-pentanol to obtain a solution containing polymer 3 (yield 79%). ). Polymer 3 had Mw of 7,700 and Mw/Mn of 1.61. ^As a result of 13 C-NMR analysis, the content of each structural unit derived from (M-4) and (M-5) was 49 mol% and 51 mol%, respectively.

[Synthesis Examples 4 and 5] (Synthesis of Polymers 4 and 5)

Polymers 4 and 5 were synthesized in the same manner as in Synthesis Example 3, respectively, except that the types and amounts of the monomers shown in Table 2 below were used. Table 2 shows the yield (%) of the synthesized polymers 4 and 5, Mw, Mw/Mn, and the content ratio (mol%) of structural units derived from each monomer.

[Synthesis Example 6] (Synthesis of Polymer 6)

A monomer solution was prepared in which 46.95 g (85 mol%) of the compound (M-5) and 6.91 g of 2,2'-azobis(2-methylpropionate) as a polymerization initiator were dissolved in 100 g of isopropanol. On the other hand, 50 g of isopropanol was put into a 500 mL three-neck flask equipped with a thermometer and a dropping funnel, and nitrogen purging was carried out for 30 minutes. After nitrogen purge, the inside of the flask was heated to 80°C while stirring with a magnetic stirrer. Then, using the dropping funnel, the above-prepared monomer solution was dripped over 2 hours. After completion of the dropwise addition, the reaction was further carried out for 1 hour. Thereafter, 10 g of an isopropanol solution of 3.05 g (15 mol%) of the compound (M-6) was added dropwise over 30 minutes, followed by reaction for an additional 1 hour, followed by cooling to 30° C. or less to obtain a polymerization reaction solution. .

Then, after concentrating the obtained polymerization reaction liquid to 150 g, it transferred to the separatory funnel. 50 g of methanol and 600 g of n-hexane were put into this separatory funnel, and separation and purification were performed. After separation, the lower layer was recovered. This lower layer liquid was diluted with isopropanol to make 100 g, and again transferred to a separatory funnel. Then, 50 g of methanol and 600 g of n-hexane were put into the separatory funnel, separation and purification were performed, and after separation, the lower layer liquid was recovered. The recovered lower layer solution was replaced with 4-methyl-2-pentanol, the total amount was adjusted to 250 g, and then 250 g of water was added to perform separation and purification, and after separation, the supernatant was recovered. Then, the recovered supernatant was replaced with 4-methyl-2-pentanol to obtain a solution containing polymer 6 (yield: 79%). Polymer 6 had Mw of 7,950 and Mw/Mn of 1.50. ^As a result of 13 C-NMR analysis, the content ratio of each structural unit derived from (M-5) and (M-6) was 95 mol% and 5 mol%, respectively.

[Synthesis Example 7] (Synthesis of Polymer 7)

Polymer 7 was synthesized in the same manner as in Synthesis Example 6 except that the type and amount of the monomers shown in Table 2 below were used. Table 2 shows the yield (%) of the synthesized polymer 7, Mw, Mw/Mn, and the content ratio (mol%) of structural units derived from each monomer.

<Preparation of composition>

[Preparation of photoresist composition]

[Preparation Example 1] (Preparation of photoresist composition 1)

100 parts by mass of polymer 1, 1.5 parts by mass of triphenylsulfonium nonafluoro-n-butanesulfonate as a radiation-sensitive acid generator, and 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium 6 parts by mass of nonafluoro-n-butanesulfonate and 0.65 parts by mass of R-(+)-(tert-butoxycarbonyl)-2-piperidinemethanol as an acid diffusion control agent are mixed, and to this mixture, a solvent Photoresist by adding 2,900 parts by mass of propylene glycol monomethyl ether acetate, 1,250 parts by mass of cyclohexanone, and 100 parts by mass of γ-butyrolactone, adjusting the solid content concentration to 5% by mass, and filtering with a filter having a pore diameter of 30 nm Composition 1 was prepared.

[Preparation Example 2] (Preparation of photoresist composition 2)

97 parts by mass of polymer 1, 3 parts by mass of polymer 2, 1.5 parts by mass of triphenylsulfonium nonafluoro-n-butanesulfonate as a radiation-sensitive acid generator, and 1-(4-n-butoxynaphthalen-1-yl) ) 6 parts by mass of tetrahydrothiophenium nonafluoro-n-butanesulfonate and 0.65 parts by mass of R-(+)-(tert-butoxycarbonyl)-2-piperidinemethanol as an acid diffusion control agent are mixed , to this mixture, 2,900 parts by mass of propylene glycol monomethyl ether acetate as a solvent, 1,250 parts by mass of cyclohexanone and 100 parts by mass of γ-butyrolactone are added, the solid content concentration is adjusted to 5% by mass, and a filter having a pore diameter of 30 nm By filtration in the photoresist composition 2 was prepared.

[Preparation of top coating composition]

[Production Example 3]

30 parts by mass of polymer 3 and 70 parts by mass of polymer 6 are mixed, and to this mixture, 1,000 parts by mass of 4-methyl-2-pentanol and 4,000 parts by mass of diisoamyl ether as a solvent are added, followed by filtration with a filter having a pore diameter of 30 nm. By doing so, top coating composition 1 was prepared.

[Preparation Examples 4 to 6]

Top coating compositions 2 to 4 were prepared in the same manner as in Production Example 3 except that each component of the type and content shown in Table 3 was used. In addition, "Demnum S-20" (Daikin Kogyo Co., Ltd.) used for manufacture of the top coating composition 4 is a chain|strand-shaped perfluoroalkyl polyether represented by the following formula (p-1), "Cytop" (Asahi Glass Corporation) ) is a cyclic perfluoroalkyl polyether represented by the following formula (p-2).

<Formation of resist pattern>

[Examples 1 to 13 and Comparative Examples 1 to 4]

A 12-inch silicon wafer surface was spin-coated with a composition for an antireflection film ("ARC66" manufactured by Nissan Chemical Industry Co., Ltd.) on the surface of a 12-inch silicon wafer using a coating/developing apparatus ("Lithius Pro-i" manufactured by Tokyo Electron Corporation), followed by PB. A lower antireflection film having an average thickness of 105 nm was formed. Then, using the coating/developing apparatus, spin coating the photoresist compositions shown in Table 4 below, PB was performed at 90° C. for 60 seconds, and then cooled at 23° C. for 30 seconds to form a photoresist film having an average thickness of 90 nm. . Subsequently, the top coating composition shown in Table 4 below was applied to the surface of the photoresist film, and PB was performed at 90° C. for 60 seconds to form a top coating layer having an average thickness of 30 nm.

Next, using an ArF immersion exposure apparatus ("S610C" manufactured by Nikon Corporation), exposure was performed through a mask for pattern formation of 45 nm line/90 nm pitch under optical conditions of NA: 1.30 and Dipole. Subsequently, after rinsing with ultrapure water for 60 seconds in the PIR module of the Lithius Pro-i, it was left still for 60 seconds in a state where water droplets were attached. Then, on a hotplate, PEB was performed at 90 degreeC for 60 second, and it cooled at 23 degreeC for 30 second.

Then, a portion of the top coating layer was peeled off by spin coating with the stripper shown in Table 4 below (when the stripper is a mixed solvent, the ratio is by mass). Then, paddle development was performed for 10 second using the 2.38 mass % TMAH aqueous solution as a developing solution. Thereafter, by spin-drying at 2,000 rpm and diffusion for 15 seconds, a substrate on which a resist pattern was formed was obtained. "-" in Comparative Example 1 indicates that the peeling was not performed with the peeling solution.

<Evaluation>

In the formation of the resist pattern, according to the following method, the receding contact angle (°) of the surface of the top coating layer before and after partial peeling, the remaining ratio of the top coating layer (%), and watermark defects and residual defects were evaluated according to the following method. The evaluation results are shown together in Table 4.

[Retraction contact angle of the top coating layer surface before and after partial peeling]

The receding contact angle of water on the surface of each top coating layer before and after partial peeling of the top coating layer was measured. The top coating composition was spin-coated on an 8-inch silicon wafer, and PB was performed at 90° C. for 60 seconds on a hot plate to obtain a substrate (before partial peeling) with a top coating layer having a thickness of 30 nm. Next, the top coating layer of this substrate was spin-coated with the stripper shown in Table 4, left still for 60 seconds, and then spin-dried at 2,000 rpm and diffusion for 15 seconds to obtain a substrate with a top coating layer after partial peeling. .

For each of the obtained substrates on which the top coating layer was formed before and after partial peeling, using a contact angle meter ("DSA-10" manufactured by KRUS), quickly, in an environment of room temperature 23° C., humidity 45%, and atmospheric pressure, the following The receding contact angle was measured by the procedure.

First, the position of the wafer stage of the contact angle meter was adjusted, and the wafer was set on the adjusted stage. Then, water was injected into the needle, and the position of the needle was finely adjusted to the initial position where water droplets could be formed on the set wafer. Thereafter, water was drained from this needle to form 25 µL of water droplets on the wafer, and once the needle was withdrawn from this water droplet, the needle was again pulled down from the initial position and placed in the water droplet. Then, at a rate of 10 µL/min, a droplet was sucked with the needle for 90 seconds, and the contact angle was measured once per second for a total of 90 times. Among these, the average value regarding the contact angle for 20 seconds from the time when the measured value of the contact angle was stabilized was calculated, and it was set as the receding contact angle (unit: (°)).

[Residual rate of top coating layer]

The average thickness after partial peeling of the top coating layer was measured, and the top coating layer residual ratio was calculated|required. A photoresist composition was coated on an 8-inch silicon wafer using a spin coater (“CLEAN TRACK ACT8” by Tokyo Electron Corporation), and then heated at 90° C. for 60 seconds to form a photoresist film having an average thickness of 90 nm. Then, the top coating composition was coated using the spin coater and heated at 90° C. for 60 seconds to form a top coating layer having an average thickness of 30 nm. Next, the top coating layer formed on the surface of the photoresist film was peeled off using the stripping solution shown in Table 4 below, and then the average thickness of the remaining top coating layer was measured. The residual rate (%) of the coating layer was calculated|required.

[Watermark Defect Suppression and Residual Defect Suppression]

Watermark by performing defect inspection by a defect inspection apparatus ("KLA2810" by KLA-Tencor) and observation by a scanning electron microscope ("RS6000" by Hitachi High-Technologies) on the obtained substrate on which the resist pattern was formed. The number of defects and residual defects were respectively measured. The watermark defect suppression property was evaluated as "○" when the number of watermark defects per wafer was 0, and "x" when 1 or more. Since "-" in Comparative Example 1 has remarkably many residual defects, it shows that measurement is impossible. In addition, the residual defect suppression property was evaluated as "(circle)" when the number of residual defects was 100 or less per wafer, and when it exceeded 100, it evaluated as "x".

As can be seen from the results in Table 4, according to the resist pattern forming method of the example, it is possible to suppress both the occurrence of watermark defects and residual defects. On the other hand, in the resist pattern formation method of the comparative example, generation|occurrence|production of a residue defect could not be suppressed.

According to the resist pattern forming method of the present invention, a resist pattern with few watermark defects and residual defects can be formed. Therefore, the resist pattern forming method can be suitably used in a semiconductor device processing process, etc., which are expected to be further miniaturized in the future.

Claims (13)

A step of coating a photoresist composition on the surface of the substrate;
A step of laminating a top coating layer on the surface of the photoresist film obtained by this coating step;
immersion exposure of the photoresist film by interposing an immersion liquid between the surface of the top coating layer and a projection optical system of an exposure apparatus;
Process of developing the photoresist film
A method of forming a resist pattern comprising:
Between the immersion exposure process and the developing process, a process of removing a part of the top coating layer
to provide
the top coating layer contains two or more types of polymers having different properties, and as the two or more types of polymers, a water repellent resin and an acidic resin;
In the removal step, at least a polymer that is localized on the surface side is removed, and the polymer to be removed is at least a part of the water-repellent resin.
A method of forming a resist pattern. The resist pattern forming method according to claim 1, wherein the removal in the removing step is performed using a stripper. The method according to claim 2, wherein the stripper satisfies the following conditions.
Conditions: When the photoresist film is formed on the surface of the substrate, the top coating layer with a thickness of 30 nm is formed on the surface of the photoresist film, and the stripper is brought into contact with the top coating layer for 60 seconds, the top coating layer has a thickness It dissolves so as to remain 2 nm or more and 28 nm or less. The method for forming a resist pattern according to claim 2 or 3, wherein the stripper has an organic solvent as a main component. 5. The resist pattern forming method according to claim 4, wherein a solubility parameter value of the stripper is smaller than a solubility parameter value of a solvent contained in the composition for forming the top coating layer. The method of claim 4 , wherein the organic solvent mainly comprises an ether-based solvent. The method of claim 5 , wherein the organic solvent mainly includes an ether-based solvent. A step of coating a photoresist composition on the surface of the substrate;
A step of laminating a top coating layer on the surface of the photoresist film obtained by this coating step;
immersion exposure of the photoresist film by interposing an immersion liquid between the surface of the top coating layer and a projection optical system of an exposure apparatus;
Process of developing the photoresist film
A method of forming a resist pattern comprising:
Between the immersion exposure process and the developing process, a process of removing a part of the top coating layer
to provide
Removal in the removal step is performed using a stripper,
The stripper has an organic solvent as a main component,
The solubility parameter value of the stripper is smaller than the solubility parameter value of the solvent contained in the composition forming the top coating layer.
A method of forming a resist pattern. The method according to claim 8, wherein the stripper satisfies the following conditions.
Conditions: When the photoresist film is formed on the surface of the substrate, the top coating layer with a thickness of 30 nm is formed on the surface of the photoresist film, and the stripper is brought into contact with the top coating layer for 60 seconds, the top coating layer has a thickness It dissolves so as to remain 2 nm or more and 28 nm or less. The method of claim 8 , wherein the organic solvent mainly comprises an ether-based solvent. delete delete delete