JP4987837B2 - High molecular compound - Google Patents

Description

  The present invention provides an alkali solubilization in response to an acid such as a base polymer of a chemically amplified resist composition used for patterning of a semiconductor integrated circuit by lithography or a dissolution control agent added to the resist composition as necessary. The present invention relates to a polymer compound excellent in transparency suitable as a resin compound to be insolubilized with alkali.

  It is no exaggeration to say that miniaturization of semiconductor integrated circuit patterns has been achieved by advancements in photolithography and peripheral technologies. As is well known, optical lithography is broadly supported by two techniques. One is the exposure wavelength and numerical aperture of a reduction projection exposure apparatus called a stepper, and the other is mainly the transfer resolution of a photoresist composition to which a mask pattern is transferred by the stepper. Resist characteristics. These have acted like two wheels of a car and have improved the processing accuracy of semiconductor integrated circuit patterns by photolithography.

The light source used for the stepper has been increasingly shortened in response to the demand for higher resolution circuit patterns. In general, when the resist resolution is about 0.5 μm, the g-line with a main spectrum of the mercury lamp of 436 nm is used, and when about 0.5 to 0.30 μm, the main spectrum of the mercury lamp is the i-line with the same wavelength of 365 nm. 30 to 0.15 μm uses 248 nm KrF excimer laser light, and about 0.15 μm or less uses 193 nm ArF excimer laser light. For further miniaturization, 157 nm F ₂ excimer laser light or 126 nm The use of Ar ₂ excimer laser light has been studied.

On the other hand, looking at the photoresist composition, there is a combination with an organic or inorganic antireflective film and a lighting system, and in the lithography using KrF excimer laser light, the life of the photoresist for KrF is extended. Development of a photoresist composition with a view of about 110 nm of λ / 2 or less is underway. In addition, in lithography using ArF excimer laser light, it is desired to provide a suitable ArF photoresist composition for future mass production of about 90 nm node or less. Lithography using the F ₂ excimer laser is attracting attention as a future responsible for microfabrication technology of about 65 nm or less, and can be sufficiently applied to microfabrication by lithography using the F ₂ excimer laser. Development of photoresist compositions is underway.

  As is well known, in lithography, a photoresist layer coated on a laminated semiconductor substrate is irradiated with light having a short wavelength through a mask reflecting a negative or positive pattern of a semiconductor integrated circuit pattern to be realized (exposure). The photoresist composition contains, as a main component, a photosensitive polymer that becomes insoluble (negative) or soluble (positive) in alkali in response to irradiation light. After irradiation with pattern light, the resist layer is exposed by exposure. A photoresist pattern layer that accurately reflects the circuit pattern to be realized is formed by performing post exposure bake firing to ensure the reaction, and then developing and removing the soluble portion. It is formed on a semiconductor substrate. Thereafter, the patterned photoresist layer may be sufficiently cured by heating (post bake) to have resistance to etching in the next step. In the etching step, the surface layer or the upper layer of the laminated semiconductor substrate is dry-etched along the pattern using the patterned photoresist layer as a mask.

  Therefore, the most important characteristic required for the photoresist composition is to obtain resolution first. For this purpose, not only the surface portion of the resist layer but also the bottom surface portion on the substrate side is irradiated with pattern irradiation light (exposure). Light), and having “transparency with respect to irradiated light” that can sufficiently expose the resist layer of the irradiated portion to the bottom portion.

  As is well known, so-called chemically amplified resist compositions have become mainstream in recent resist compositions in order to realize the above-mentioned demands for miniaturization of lithography. This chemically amplified resist composition contains at least a polymer compound having a group highly reactive with an acid, an acid generator that generates an acid upon exposure, and a solvent that dissolves the acid generator. When pattern light is irradiated onto the coating film of this resist composition, acid is released from the acid generator present in the exposed area to the exposed area, and acts on the base polymer (the polymer compound) in the exposed area. In a positive resist composition, the base polymer is alkali-soluble by removing a protecting group (also referred to as an acid dissociable, dissolution inhibiting group) due to the catalytic action of an acid. By developing the resist layer, a positive resist pattern is obtained with respect to the mask pattern. On the other hand, the negative resist composition uses a developer-soluble polymer, and the exposed portion becomes a developer-insoluble type due to the catalytic action of the acid. In addition, a dissolution control agent is added to this chemically amplified resist composition as another polymer component as required. This dissolution control agent is a high molecular compound having a molecular weight of 5000 or 3000 and a relatively low molecular weight, and the protective group is released by the action of an acid generated from the acid generator to increase the solubility in an alkali developer. The portion remaining as an insoluble portion in the resist film by exposure (unexposed portion) suppresses the solubility by the alkali developer, and the soluble portion (exposed portion) exerts the action of promoting the solubility by the alkali developer. .

  Therefore, in order to improve the transparency to the exposure light of the chemically amplified resist composition, the base polymer and the polymer used for the dissolution control agent added as necessary have high transparency to the exposure light. It will be necessary to comprise from the high molecular compound which has.

The base polymer of the resist composition and the resin component of the dissolution control agent that can be used for lithography with F ₂ excimer laser light, which is the light source for next-generation steppers, are highly transparent at 157 nm, which is the main spectrum of F ₂ excimer laser light. Sexuality is required. Regarding the desired transparency of the resist film by exposure at a wavelength of 157 nm, in order to obtain sufficient pattern transfer resolution, the absorption coefficient (optical constant) of the resist film with normalized film thickness is 3.0 (μm). ^-1 ) It has been found that the following is necessary (Non-Patent Document 1).

  On the other hand, since the existing resist material has absorption at this wavelength of 157 nm, that is, it has low transparency with respect to the irradiation light of wavelength 157 nm, the next generation resist composition can be obtained from the existing resist material. I can't.

  Thus, in the technical field of providing a photoresist composition, the development of a polymer compound having high transparency at a wavelength of 157 nm is currently an issue. Up to now, by introducing fluorine (F) and silicon (Si), transparency to irradiation light having a wavelength of 157 nm as a main spectrum is ensured, and alkali-solubility that affects development characteristics after exposure, pattern transfer, etc. Development of new polymers that have resist performance such as resolution and etching resistance is underway. However, the degree of fluorine or silicon introduced into any part of any polymer of any composition aims at transparency to exposure light while maintaining other characteristics such as dry etching resistance. It is not clear whether it can be improved beyond the level.

  As a base polymer for a resist composition pursuing transparency to exposure light by an ArF excimer laser, conventionally disclosed is an acrylic acid having an alicyclic group structure and a δ-lactone structure bonded to an androsterone derivative. Copolymers of ester monomers (Patent Document 1) and acrylic acid having an electron withdrawing group at the α-position and cyclopentadiene or dicyclopentadiene are subjected to Diels-Alder reaction to obtain a polycyclic unsaturated carboxylic acid. A polymer of a polycyclic unsaturated hydrocarbon derivative in which a hydrogen atom of a hydroxyl group of a carboxylic acid is substituted with an acid dissociable, dissolution inhibiting group (Patent Document 2), or an alicyclic ring having a polymerizable carbon-carbon double bond in the ring A copolymer having a polymer unit derived from a hydrocarbon and a polymer unit derived from (meth) acrylonitrile (Patent Document 3), A polymer having a monomer having a lactone structure bonded to a benzene group as a polymerization unit (Patent Document 4), a copolymer of an acrylate monomer and a vinyl ether derivative having a fluorine atom introduced at the α-position (Patent Document 5), etc. Is mentioned. In the copolymer disclosed in Patent Document 1, fluorine atoms are not introduced in order to improve transparency. In the polymer disclosed in Patent Document 2, fluorine is introduced into part of the polymer units or part of the side chain ring, but the relationship between the introduction and transparency is not clear. In the copolymer disclosed in Patent Document 3, fluorine is introduced into a part of the terminal protecting group of the side chain ring, but the relationship between the introduction and transparency is not clear. In the polymer disclosed in Patent Document 4, fluorine is not introduced in order to improve transparency. Examples of the copolymer disclosed in Patent Document 5 include those in which some or about half of the hydrogen atoms on the side chain ring are fluorine-substituted, but the relationship between the substitution and transparency is not clear. .

As described above, various polymer compounds have been proposed to improve the transparency to exposure light having a wavelength of 200 nm or less. However, what kind of fluorine is present at what part of the polymer having any composition. It is not clear whether the transparency of exposure light can be improved beyond the intended level while maintaining other characteristics such as dry etching resistance.
M.M. K. Crawford, et al. , “New Material for 157 nm Photographers: Characterization and Properties” Proceedings of SPIE, Vol. 3999, (2000) pp. 1980. 357-364 JP 2001-174993 A JP 2001-328964 A JP 2002-196495 A JP 2002-278069 A JP 2002-293840 A

The present invention has been made in view of the above circumstances, and relates to a highly transparent polymer compound that can be used in a photoresist composition for next-generation microfabrication. More specifically, the present invention relates to exposure light having a wavelength of 157 nm. In contrast, the present invention relates to a polymer compound having transparency of an absorption coefficient of 3.0 μm ⁻¹ or less.

The inventors of the present invention have made extensive studies in order to solve the above-mentioned problems. As a result, in order to ensure etching resistance, the side chain portion has an alicyclic group, and the alicyclic group on the ring is provided. It has been found that if an arbitrary number of hydrogen atoms or more are replaced by fluorine atoms, a transparency having an absorption coefficient of 3.0 μm ⁻¹ or less can be secured for light having a wavelength of 157 nm. The alicyclic group is preferably a polycyclic group, and the high degree of substitution with fluorine is desirably all substitution of hydrogen atoms on the ring, that is, preferably a perfluoroalicyclic group. found.

The present invention has been made on the basis of such findings, and the polymer compound according to the present invention is a polymer compound having a polymerizable unit having a side chain of an alicyclic group, and the alicyclic group is highly advanced. It is characterized by having transparency with an absorption coefficient of 3.0 μm ⁻¹ or less for light having a wavelength of 157 nm.

  The resist composition in the present specification contains the polymer compound. The resist composition may contain the polymer compound as a base polymer, may be contained as a dissolution control agent added as necessary, and may be a system using these simultaneously. . However, when used as a base polymer of a resist composition, the weight average molecular weight is 1,000 to 20,000, preferably 3,000 to 20,000, and 1,000 to 5, when used as a dissolution control agent. 000 is preferred.

As described above, the polymer compound according to the present invention is a polymer compound having a polymerizable unit having an alicyclic group in the side chain, and the alicyclic group is highly fluorinated and has a wavelength of 157 nm. It has a transparency with an absorption coefficient of 3.0 μm ⁻¹ or less with respect to light. When this polymer compound is expressed by a general formula, it can be shown as a polymer having a polymer unit represented by the following general formula (1).

、エーテル基（−Ｏ−）、−ＣＨ_２−Ｏ−またはアルキリデン基

であり、丸で囲んだＺは高度にフッ素化された脂環式基で、好ましくは多環式基であり、Ｒ^１、Ｒ^２，Ｒ^３，Ｒ^５，Ｒ^６，およびＲ^７は、それぞれ独立して、水素原子、低級アルキル基、フッ素原子、またはフッ化低級アルキル基から選択される１種であり、ｌは０〜３の整数であり、Ｒ^４は水酸基である。 In the general formula (1), n is an arbitrary integer, X is an ester group of a carboxylic acid,

, Ether group (—O—), —CH ₂ —O— or alkylidene group

And Z encircled is a highly fluorinated alicyclic group, preferably a polycyclic group, R ¹ , R ² , R ³ , R ⁵ , R ⁶ , and R ⁷ are Each is independently one selected from a hydrogen atom, a lower alkyl group, a fluorine atom, or a fluorinated lower alkyl group, l is an integer of 0 to 3, and R ⁴ is a hydroxyl group.

  The alicyclic group represented by Z in the general formula (1) is preferably an adamantyl group which is a tricyclic alicyclic hydrocarbon group, and the hydrogen atom on the ring is highly fluorine. Preferably, it is perfluoro.

The polymer compound according to the present invention is a polymer compound comprising a polymerizable unit having an alicyclic group, wherein the alicyclic group is highly fluorinated and has an absorption coefficient for light having a wavelength of 157 nm. It has a transparency of 3.0 μm ⁻¹ or less.

  Therefore, according to the present invention, it is possible to provide a polymer compound having high transparency, a resist composition having the polymer compound, and a dissolution control agent that can be used in a photoresist composition for next-generation microfabrication. it can.

As described above, the polymer compound according to the present invention is a polymer compound having a polymerizable unit having an alicyclic group in the side chain, and the alicyclic group is highly fluorinated and has a wavelength of 157 nm. It has a transparency with an absorption coefficient of 3.0 μm ⁻¹ or less with respect to light.

  In such a configuration, it is desirable that all of the hydrogen atoms on the alicyclic group are fluorinated. However, when the ring has a hydrophilic substituent other than a hydrogen atom (for example, a hydroxyl group), the substituent is not fluorinated. The alicyclic group is preferably a polycyclic group.

  The alicyclic group may contain a hydrophilic group. The presence of this hydrophilic group improves the adhesion of the resist film and resist pattern to the substrate when a coating film is formed on the substrate when this polymer compound is used as the base polymer or dissolution control agent of the resist composition. Can be expected.

  Moreover, as said alicyclic group, the alicyclic of ArF resist until now, Especially as a polycyclic group, it can use arbitrarily from what is known. For example, a group obtained by removing one hydrogen element from bicycloalkane, tricycloalkane, teracycloalkane, or the like can be exemplified. Specific examples include groups in which one hydrogen atom has been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Of these, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are industrially preferable. In particular, an adamantyl group is preferred. Since an adamantyl group is highly transparent not only for light having a wavelength of 300 nm or less but also for light having a wavelength of 300 nm or more, it is highly versatile and preferable for use in a resist composition.

  In addition, as the polymerizable unit, a unit derived by cleavage of an ethylenic double bond of acrylic acid ester or methacrylic acid ester, vinyl ether or allyl ether can be preferably used.

  Furthermore, the polymer compound of the present invention is preferably a copolymer. That is, it may further contain a second polymerizable unit. If the second polymerizable unit is contained, an acid-sensitive substituent is bonded to the second polymerizable unit, thereby controlling alkali solubilization or alkali insolubilization by acid catalysis of the polymer compound. And the degree of freedom in setting sensitivity to the acid catalyst can be increased. That is, the second polymerizable unit may have an acid dissociable group or may have an insoluble group with respect to an acid.

  As the second polymerizable unit, a polymerizable unit derived from an acrylate ester or a methacrylic acid ester, or a unit derived by cleavage of an ethylenic double bond such as tetrafluoroethylene is preferably used. be able to.

  Examples of the acrylic acid ester or methacrylic acid ester suitable for the polymerizable unit include compounds having the following structure.

  Moreover, as a vinyl ether suitable as said polymeric unit, the compound of the following structure can be mentioned, for example.

  Moreover, as an allyl ether suitable as the polymerizable unit, a compound having the following structure can be used.

  A preferred specific example of the polymer having a polymerizable unit containing an adamantyl group suitable as the alicyclic group is 1-perfluoroadamantyl having a polymerizable unit represented by the following general formula (2). Examples thereof include a polymer having a unit derived from methacrylate or 3-hydroxy-1-perfluoroadamantyl acrylate having a polymerizable unit represented by the general formula (3). Note that m and n are arbitrary integers.

  The 1-perfluoroadamantyl methacrylate and 3-hydroxy-1-perfluoroadamantyl acrylate can be obtained by, for example, the following synthesis method. 1 equivalent of 1-hydroxyperfluoroadamantane or 1 part of perfluoroadamantanediol and 1.2 equivalent of triethylamine are dissolved in diethyl ether, and then 1 equivalent of acrylic acid chloride or methacrylic acid chloride is slowly added dropwise to the solution under ice cooling. To do. After completion of the reaction, water is added and extracted with diethyl ether, and then the organic layer is dried over magnesium sulfate. After magnesium sulfate is filtered off, the resulting diethyl ether solution is concentrated and then separated by column to obtain 1-perfluoroadamantyl (meth) acrylate or 3-hydroxy-1-perfluoroadamantyl (meth) acrylate. If these monomers are obtained, a polymer compound having the unit can be obtained by a known radical polymerization method using a polymerization initiator such as azobisisobutyronitrile (AIBN).

  Examples of the compound having a polymerizable unit derived from an acrylic ester or methacrylic ester suitable for the second polymerizable unit include compounds having the following structure.

  Examples of the compound having a polymerizable unit that is derived by cleavage of another vinyl double bond suitable for the second polymerizable unit include compounds having the following structure.

In addition to these, it is also possible to use a fluorine-containing monocyclic polymerizable unit disclosed in JP-A No. 2002-90997. The fluorine-containing monocyclic polymer disclosed in Japanese Patent Application Laid-Open No. 2002-90997 is a monomer of a diene monomer (a) comprising a compound represented by the formula: CH ₂ ═CH—Y—CH═CH ₂ or a derivative thereof. A fluorine-containing monocyclic polymer containing a repeating unit of a cyclic structure in which a unit and a monomer unit of the fluorine-containing vinyl monomer (b) are cyclized and having a blocked acidic group derived from the fluorine-containing vinyl monomer is there. In the above formula, Y represents a methylene group or an oxygen atom. The derivative (a) includes an alkyl substituent and a hydroxyl group substituent, and the substituted alkyl group is preferably a lower alkyl group having 1 to 4 carbon atoms. These second polymerizable units require a unit having an acid dissociable, dissolution inhibiting group when used in a positive resist, and require a unit having an acid insoluble group when used in a negative resist. . Furthermore, in order to increase the adhesion between the substrate and the resist pattern, the polymer compound of the present invention such as a unit having a γ-butyrolactone group or tetrafluoroethylene for improving the transparency is further used as necessary in ternary or quaternary. Alternatively, two or more kinds may be used in combination as appropriate in order to obtain a ternary copolymer. The structural formula showing a specific example of the polymer compound of the present invention is as follows.

  Further, the acid dissociable, dissolution inhibiting group is not limited as long as it has been proposed as a chemically amplified positive resist, but in particular, a tertiary alkyl group, more specifically, tert. -What consists of chain alkyl groups, such as a butyl group and a tert-amyl group, What consists of cyclic alkyl groups, such as 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, and a chain alkyl group, etc. Can be mentioned.

  Furthermore, examples of the insoluble group for the acid include those in which a hydroxycarboxylic acid such as δ-hydroxycarboxylic acid as described in Patent Document 1 can form a lactone by the action of an acid.

  The polymer compound of the present invention contains a polymerizable unit having the above-described highly fluorinated alicyclic group, and preferably has this and a second polymerizable unit. The polymer compound can be used as a base polymer for a chemically amplified resist and as a dissolution control agent. When used as a dissolution control agent, an acid dissociable, dissolution inhibiting group is essential as in the case of use as the base polymer of the positive resist described above, and its weight average molecular weight may be about 2,000 to 5,000. In that case, you may use together with the high molecular compound of this invention, and may use it in combination with another well-known base polymer.

  The polymer compound of the present invention can be easily produced by a known polymerization method, typically radical polymerization. For example, a necessary monomer is dissolved in a solvent such as tetrahydrofuran, ethyl acetate, methyl isobutyl ketone, and methyl ethyl ketone, a radical polymerization initiator is added, and the mixture is heated. As the polymerization initiator, azobisisobutyronitrile (AIBN) (use temperature 60 to 90 ° C.), 2,2′-azobis- (2,4-dimethylvaleronitrile (use temperature 45 to 70 ° C.)), 2,2′-azobis- (2-methylisobutyronitrile) (use temperature 60 to 95 ° C.), tert-butyl peroctoate (use temperature 75 to 100 ° C.), 1,1′-azobis- (cyclohexane- 1-carbonitrile) (use temperature: 80 to 110 ° C.), 1-[(1-diazo-1-methylethyl) azo] formamide (temperature: 95 to 120 ° C.) and the like. Can be used. In particular, AIBN is preferably used as a general-purpose polymerization initiator.

  Thereafter, the reaction solution containing the polymer compound thus obtained is dropped into a large amount of poor solvent such as isopropanol, methanol, water, n-heptane, and n-hexane to precipitate the polymer compound. Let Then, the polymer compound (resin) of the present invention can be obtained by filtering and drying the obtained precipitate. Although this step may be unnecessary depending on circumstances, it is effective for removing unreacted monomers and polymerization initiators remaining in the reaction solution. If these unreacted substances remain as they are, there is a possibility that the resist performance may be adversely affected. And in order to prepare a resist composition, it is necessary to mix | blend an acid generator component simultaneously.

  As the acid generator component in the resist composition of the present specification, any conventionally known acid generator for chemically amplified resists can be appropriately selected and used.

  Examples of the acid generator include diphenyliodonium trifluoromethanesulfonate, (4-methoxyphenyl) phenyliodonium trifluoromethanesulfonate, bis (p-tert-butylphenyl) iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, (4 -Methoxyphenyl) diphenylsulfonium trifluoromethanesulfonate, (4-methylphenyl) diphenylsulfonium nonafluorobutanesulfonate, (p-tert-butylphenyl) diphenylsulfonium trifluoromethanesulfonate, diphenyliodonium nonafluorobutanesulfonate, bis (p-tert- Butylphenyl) iodonium nonafluorobutanesulfonate, Including onium salts such as sulfonium nonafluorobutane sulfonates. Of these, onium salts having a fluorinated alkyl sulfonate ion as an anion are preferable.

  As the acid generator component, one kind of acid generator may be used alone, or two or more kinds may be used in combination.

  The amount of the acid generator component used is 0.5 to 30 parts by mass, preferably 1 to 10 parts by mass, with respect to 100 parts by mass of the base polymer. If the amount is less than 0.5 parts by mass, pattern formation is not sufficiently performed. If the amount exceeds 30 parts by mass, a uniform solution is difficult to obtain, which may cause a decrease in storage stability.

  The resist composition in the present specification can be produced by dissolving the base polymer, the acid generator component, and optionally the dissolution control agent, and further optional components described later in an organic solvent.

  Any organic solvent may be used as long as it can dissolve the above-described components to form a uniform solution. Conventionally, any one or more of the known solvents for chemically amplified resists may be used. It can be appropriately selected and used.

  For example, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol, or dipropylene Polyhydric alcohols such as glycol monoacetate monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof, cyclic ethers such as dioxane, methyl lactate, ethyl lactate, methyl acetate , Ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethoxypropionate Esters such as phosphate ethyl and the like. These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.

  In particular, propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) are preferable, and a mixed solvent of these and a polar solvent having a hydroxy group or lactone such as ethyl lactate (EL) or γ-butyrolactone is Since the storage stability of the resist composition is improved, it is preferable.

  Further, in the resist composition in the present specification, a known amine component, preferably a secondary lower aliphatic amine or a third amine, is further added as an optional component in order to improve the resist pattern shape, retention time stability, and the like. Grade lower aliphatic amines can be included.

  Here, the lower aliphatic amine refers to an alkyl or alkyl alcohol amine having 5 or less carbon atoms, and examples of the secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, Tri-n-propylamine, triventylamine, diethanolamine, triethanolamine and the like can be mentioned, and alkanolamines such as triethanolamine are particularly preferable.

  These may be used alone or in combination of two or more. Moreover, these amines are normally used in 0.01-1 mass% with respect to a base polymer component.

  The resist composition in the present specification further includes miscible additives as desired, for example, additional resins for improving the performance of the resist film, surfactants for improving coating properties, dissolution inhibitors, plastics. An agent, a stabilizer, a colorant, an antihalation agent and the like can be appropriately added and contained.

(Pattern formation method)
Next, a resist pattern forming method will be described.
First, after applying the resist composition of the present invention on a substrate such as a silicon wafer with a spinner or the like, pre-baking is performed. Subsequently, using an exposure apparatus or the like, the resist composition coating film is selectively exposed through a desired mask pattern, and then subjected to PEB (post-exposure heating). Subsequently, after developing using an alkali developer, water rinsing is performed using pure water. By a series of these operations, the resist composition coating film is patterned into a shape corresponding to the mask pattern to obtain a resist pattern.

The wavelength used for the exposure is not particularly limited, and radiation such as ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), electron beam, X-ray, soft X-ray is used. Can be done. In particular, the resist composition of the present invention is effective for F ₂ excimer laser.

  An organic or inorganic antireflection film can be provided between the substrate and the coating film of the resist composition.

  In addition, the polymer compound of the present invention may be a homopolymer of a highly fluorinated polymerizable unit having an alicyclic group in the side chain, or a copolymer with a second polymerizable unit. . In the case of a copolymer, the former unit is 5 to 40 mol%, preferably 10 to 35 mol%, and the second polymerizable unit is 60 to 95 mol%, preferably 65 to 90 mol%. In addition, you may use a 2nd monomer combining suitably 2 or more types.

  Examples of the present invention will be described below. However, these examples are merely examples for suitably explaining the present invention, and do not limit the present invention.

(Resin synthesis example 1)
5.0 g of 1-perfluoroadamantyl methacrylate was dissolved in 20 mL of tetrahydrofuran, and 0.1 g of azobisisobutyronitrile was added. After heating to reflux at 70 ° C. for 5 hours, it was added dropwise to 500 mL of methanol. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powdery resin. This resin was a polymer compound having a polymer unit as shown in the general formula (2). The yield of this resin was 1 g. Moreover, the weight average molecular weight (Mw) of this resin was 8,000, and dispersion degree (Mw / Mn) was 1.6. Hereinafter, this resin is referred to as “resin 1”.

(Resin synthesis example 2)
10.0 g of 3-hydroxy-1-perfluoroadamantyl acrylate was dissolved in 50 mL of tetrahydrofuran, and 0.1 g of azobisisobutyronitrile was added. The mixture was heated to reflux at 70 ° C. for 5 hours and then added dropwise to 1 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a resin. This resin was a polymer compound having a polymer unit as shown in the general formula (3). The yield of this resin was 5.1 g. Moreover, the weight average molecular weight (Mw) of this resin was 4800, and dispersion degree (Mw / Mn) was 1.28. Hereinafter, this resin is referred to as “resin 2”.

(Resin synthesis example 3)
4.40 g of 2-methyl-2-adamantyl acrylate, 3.12 g of γ-butyrolactone acrylate, and 4.74 g of 3-hydroxyperfluoroadamantyl acrylate were dissolved in 50 mL of tetrahydrofuran to obtain 0.61 g of azobisisobutyro Nitrile was added. The mixture was heated to reflux at 70 ° C. for 5 hours and then added dropwise to 1 L of n-heptane. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a resin. This resin was a polymer compound having three types of polymerization units represented by the following general formulas (4) and (5) and the general formula (3). The yield of this resin was 7.0 g. Moreover, the weight average molecular weight (Mw) of this resin was 5100, and dispersion degree (Mw / Mn) was 2.37. Hereinafter, this resin is referred to as “resin 3”. In the following general formulas (4) and (5), p and q are arbitrary integers. This polymer compound is useful as a base polymer for a positive resist and a dissolution control agent.

(Resin synthesis example 4)
2.8 g lactone monomer and 2.4 g 3-hydroxyperfluoroadamantyl acrylate were dissolved in 90 mL tetrahydrofuran and 0.15 g azobisisobutyronitrile was added. The mixture was heated to reflux at 70 ° C. for 5 hours and then added dropwise to 1 L of n-heptane. The resulting solid was filtered and then vacuum dried at 40 ° C. for 3 hours. 3.0 g of the obtained resin was dissolved in 100 mL of tetrahydrofuran, and 110 g of TMAH (tetramethylammonium hydroxide) was added. After stirring at room temperature for 6 hours, the mixture was neutralized with 0.04N HCl. The hydrolyzed resin was extracted with ethyl acetate. The organic layer was washed with pure water and then added dropwise to 1 L of n-heptane. The precipitated resin was separated by filtration and vacuum dried at 30 ° C. for 2 hours to obtain a resin. This resin was a polymer compound having two kinds of polymerization units represented by the following general formula (6) and the chemical formula (3). The yield of this resin was 1.5 g. Moreover, the weight average molecular weight (Mw) of this resin was 1200, and dispersion degree (Mw / Mn) was 1.79. Hereinafter, this resin is referred to as “resin 4”. In the following general formula (6), r is an arbitrary integer. This polymer compound is useful as a base polymer for negative resists.

(Comparative resin synthesis example 1)
10.0 g of 1-adamantyl methacrylate was dissolved in 50 mL of tetrahydrofuran and 0.5 g of azobisisobutyronitrile was added. The mixture was heated to reflux at 70 ° C. for 5 hours and then added dropwise to 1 L of methanol. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a resin. This resin was a polymer compound having a polymerization unit represented by the following general formula (7). The yield of this resin was 8.0 g. Moreover, the weight average molecular weight (Mw) of this resin was 6,000, and dispersion degree (Mw / Mn) was 1.5. Hereinafter, this resin is referred to as comparative resin 1.

(Comparative resin synthesis example 2)
10.0 g of 3-hydroxy-1-adamantyl acrylate was dissolved in 50 mL of tetrahydrofuran and 0.5 g of azobisisobutyronitrile was added. The mixture was heated to reflux at 70 ° C. for 5 hours and then added dropwise to 1 L of methanol. The precipitated resin was separated by filtration and dried under reduced pressure to obtain a white powdery resin. This resin was a polymer compound having a polymerization unit represented by the following general formula (8). The yield of this resin was 8.0 g. Moreover, the weight average molecular weight (Mw) of this resin was 6100, and dispersion degree (Mw / Mn) was 2.8. Hereinafter, this resin is referred to as comparative resin 2.

Example 1
Measurement of transparency (absorption coefficient) of resin Resin 1 and comparative resin 1 are dissolved in toluene, respectively, and resin 2 and comparative resin 2 are dissolved in PGME (propylene glycol monomethyl ether), respectively. The film was applied on a magnesium fluoride wafer so that the film thickness after drying was 0.1 μm. These coating films were each pre-baked on a direct hot plate at 130 ° C. for 60 seconds to form four types of resin films. The transparency (absorption coefficient) of each resin film thus formed with respect to each light having a wavelength of 157 nm and 193 nm was measured using a vacuum ultraviolet spectrophotometer (manufactured by JASCO Corporation). The results are shown in Table 1.

As is clear from Table 1, the polymer compound according to the present invention has a very high transparency with respect to F ₂ excimer laser light having a wavelength of 157 nm, which has been difficult to ensure in the past, and is a base for next-generation resist compositions. It is understood that it is suitable for use in polymers constituting polymers and dissolution inhibitors.

(Example 2)
Confirmation of Resolution by ArF Positive Exposure Using resin 3 containing 3-hydroxy-1-perfluoroadamantyl acrylate as a polymer unit as a base polymer, as shown below, triphenyl sulfone as an acid generator is used. A positive resist composition was prepared using nitroperfluorobutanesulfonate (TPS-PFBS) and triethanolamine as a quencher and PGMEA (propylene glycol monomethyl ether acetate) as a solvent.

100 parts by weight of resin 3
Acid generator: TPS-PFBS 2.5 parts by weight
Quencher: Triethanolamine 0.2 parts by weight
Solvent: 900 parts by weight of PGMEA

  The resolution of the positive resist obtained by forming this positive resist composition into a film was confirmed by exposure with ArF excimer laser light. The measured resolution and exposure dose are shown in Table 2 below.

Example 3
Confirmation of Resolution by ArF Negative Exposure Using resin 4 containing 3-hydroxy-1-perfluoroadamantylacrylic ester as a polymerizable unit as a base polymer, triphenylsulfonium as an acid generator as shown below Perfluoromethanesulfonate (TPS-PFMS) and triphenylsulfonium perfluorobutanesulfonate (TPS-PFBS) and 4-phenylpyridine as a quencher are added, and PGME and pure water are used as a solvent to form a negative resist composition. Prepared.

Resin 4 100 parts by weight
Acid generator: TPS-PFMS 1.0 part by weight
Acid generator: 0.68 parts by weight of TPS-PFBS
Quencher: 0.2 parts by weight of 4-phenylpyridine
Solvent: 1000 parts by weight of PGME
80 parts by weight of pure water

  The resolution of the negative resist formed from the negative resist composition was confirmed by exposure with ArF excimer laser light. The measured resolution and exposure dose are shown in Table 2 below. In the table, PB means pre-heating treatment (Pre Bake) performed before exposure, and PEB means heat treatment (Post Exposure Bake) performed after exposure.

As shown in Table 2, the resist composition containing the polymer compound of the present invention has excellent resolving power and exposure sensitivity, and these characteristics are the ArF of the polymer compound of the present invention used as the base polymer. It is understood that it is derived from excellent transparency to excimer laser light. From this, it is clear that the same effect can be obtained with the F ₂ excimer laser.

  In addition, although the example which used the high molecular compound of this invention as a base polymer of a resist composition was shown in the said Example, what controlled the weight average molecular weight smaller is added to a resist composition as needed. Obviously, it can also be used as a dissolution control agent.

Claims (9)

A high polymer having an adamantyl group in the side chain, a first polymerizable unit derived from an acrylate ester or a methacrylic ester, and a second polymerizable unit different from the first polymerizable unit. A molecular compound,
More than half of the hydrogen atoms on the ring of the adamantyl group are fluorinated and have a transparency with an absorption coefficient of 3.0 μm ⁻¹ or less with respect to light having a wavelength of 157 nm.   2. The polymer compound according to claim 1, wherein all of the hydrogen atoms on the ring of the adamantyl group are fluorinated.   The polymer compound according to claim 1, wherein the adamantyl group has a hydroxyl group on the ring.   The polymer compound according to any one of claims 1 to 3, wherein the second polymerizable unit has an acid dissociable group.   The polymer compound according to any one of claims 1 to 3, wherein the second polymerizable unit has a group having a hydroxycarboxylic acid structure that forms a lactone by the action of an acid.   The polymer compound according to any one of claims 1 to 5, wherein the second polymerizable unit is a polymerizable unit derived from an acrylate ester or a methacrylate ester.   The polymer compound according to any one of claims 1 to 5, wherein the second polymerizable unit is a polymerizable unit derived from a vinylic double bond. The following general formula (1)

Wherein n is an arbitrary integer, X is an ester group of a carboxylic acid,

, Ether group (—O—), —CH ₂ —O— or alkylidene group

Z surrounded by a circle is an adamantyl group in which more than half of the hydrogen atoms on the ring are fluorinated, and R ¹ , R ² , R ³ , R ⁵ , R ⁶ , and R ⁷ are each independently And a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a fluorine atom, or a fluorinated alkyl group having 1 to 5 carbon atoms, l is an integer of 0 to 3, and R ⁴ is It is a hydroxyl group. )
Transparent having an absorption coefficient of 3.0 μm ⁻¹ or less with respect to light having a wavelength of 157 nm, the first polymerizable unit represented by the formula (1) and a second polymerizable unit different from the first polymerizable unit. A polymer compound characterized by having properties.   The polymer compound according to claim 8, wherein the adamantyl group is a perfluoroadamantyl group.