JP4749232B2 - Resist upper layer antireflection film material and pattern forming method - Google Patents

Description

  The present invention relates to an antireflection material that enables high-precision fine processing even on an uneven substrate, and a method of forming a resist pattern using the same, particularly in photolithography using a photoresist.

In recent years, with the higher integration and higher speed of LSIs, there is a demand for finer pattern rules. In light exposure currently used as a general-purpose technology, the intrinsic resolution limit derived from the wavelength of the light source Is approaching.
As exposure light used for forming a resist pattern, light exposure using a g-ray (436 nm) or i-line (365 nm) of a mercury lamp as a light source is widely used. As a means for further miniaturization, exposure light is used. The method of shortening the wavelength has been considered effective. For this reason, in the mass production process of DRAM (Dynamic Random Access Memory) 64Mbit (process size is 0.25μm or less), KrF excimer laser (248nm) with short wavelength instead of i line (365nm) as exposure light source Has been used. However, in order to manufacture DRAMs having an integration degree of 256M and 1G or more that require a finer processing technique (processing dimension is 0.2 μm or less), a light source with a shorter wavelength is required, particularly an ArF excimer laser (193 nm). Photography using is being studied.

  In the early stages of KrF lithography, steppers were developed that combine achromatic lenses or reflective optics with broadband light. However, since the accuracy of the achromatic lens or the aspherical reflecting optical system is not sufficient, a combination of monochromatic light and a refractive optical system lens has become mainstream. Here, in half-wavelength exposure, incident light and reflected light from the substrate interfere with each other to generate a standing wave, which is a well-known phenomenon for a long time. Both standing waves caused dimensional fluctuations such as the line width of the pattern and shape collapse. The use of coherent monochromatic light further amplifies standing waves and halation with shorter wavelengths. As a method for suppressing the standing wave, a method of putting a light absorber in the resist, a resist upper surface (ARCOR method, Patent Documents 1 to 3), and a method of laying an antireflection film on the substrate surface (BARC method, Patent Document 4) were proposed. . The ARCOR method is a method that includes a step of forming a transparent antireflection film on the resist and peeling it off after exposure, and is a method for forming a fine pattern with high accuracy and high alignment accuracy by this simple method. When a perfluoroalkyl compound (perfluoroalkyl polyether, perfluoroalkylamine), which is a low refractive index material, is used as the antireflection film, the reflected light at the resist-antireflection film interface is greatly reduced and the dimensional accuracy is improved.

  However, since the perfluoroalkyl compound has low compatibility with organic substances, chlorofluorocarbon is used as a diluent for controlling the coating film thickness. Therefore, its use has become a problem. Moreover, the said compound had a problem in uniform film formability, and it could not be said that it was enough as an antireflection film. In addition, the antireflection film had to be peeled off with CFC before developing the photoresist. For this reason, there has been a great practical disadvantage in that it is necessary to add a system for removing the antireflection film to the conventional apparatus, and the cost of the fluorocarbon solvent is considerably increased.

  If the antireflection film is peeled off without adding to the conventional apparatus, it is most desirable to peel off using the developing unit. Since the solution used in the photoresist developing unit is an alkaline aqueous solution as a developer and pure water as a rinse solution, it can be said that an antireflection film material that can be easily peeled off with these solutions is desirable. Therefore, many water-soluble antireflection film materials and pattern forming methods using these have been proposed (Patent Documents 5 to 15).

  Here, the refractive index of the upper antireflection film for reducing the standing wave to 0 is ideally the square root of the refractive index of the resist, and the refractive index of the polyhydroxystyrene-based resist used in KrF. Although 1.8 is 1.34, the refractive index of the alicyclic resist used for ArF decreases. For example, polyacrylate is 1.7, and the ideal value is 1.30. Examples of such a material having a low refractive index include a fluorine-based material, but the refractive index of Teflon (registered trademark) is 1.38, which does not reach the target value. Here, Patent Document 16 shows that the refractive index of polyvinyl naphthalene at a wavelength of 193 nm is 1.2. There is a limit to lowering the refractive index to 1.35 or less with a fluorine-based polymer, and an antireflection film in which the refractive index is lowered using an aromatic polymer has been proposed (Non-patent Document 1).

Non-patent document 2 states that aromatics have absorption at a wavelength of 193 nm, but that the antireflection effect is enhanced by providing absorption in the resist upper layer antireflection film. According to this, a sufficient antireflection effect can be achieved even with a value larger than the square root of the resist by using a resist upper layer antireflection film that absorbs light. However, when there is absorption in the upper antireflection film, there is a concern that the resist size may change greatly due to the film thickness variation of the upper antireflection film on the step. Non-Patent Document 3 reports dimensional fluctuations due to film thickness fluctuations of resist and CEL on a step when contrast enhancer (CEL) is applied. CEL having absorption at the beginning of exposure and upper layer reflection having absorption It is conceivable that a similar phenomenon occurs with the prevention film. Therefore, it is necessary to optimize the absorbance and film thickness of the upper antireflection film according to the height of the step.
JP-A-62-62520 JP-A-62-62521 JP 60-38821 A JP 62-159143 A JP-A-6-273926 JP-A-6-289620 JP 7-160002 A JP 7-234514 A JP-A-7-333855 JP-A-8-44066 Japanese Patent Laid-Open No. 9-50129 JP-A-9-291228 JP-A-9-325500 Japanese Patent Laid-Open No. 11-124531 Japanese Patent No. 2803549 JP 2004-205658 A Proc. SPIE Vol. 6153-28 New 193-nm top antireflective coatings for superior swing reduction (2006) Proceedings of the 45th Symposium on Semiconductor and Integrated Circuit Technology p62 Proceedings of the 45th Symposium on Semiconductor and Integrated Circuit Technology p14

  The resist upper layer antireflection film is required to have a high antireflection effect, be able to be removed together with development of the resist, have high process simplicity, and have a performance that does not change the resist shape without causing mixing with the resist.

（上式中、Ｒ²¹とＲ²²は、独立して同一又は非同一のメチル基又は水素原子を表し、ＸとＹはそれぞれ単結合、酸素原子又はエステル基を表し、ｍとｎは１又は２であり、ａとｂは０≦ａ≦１．０、０≦ｂ≦１．０、０＜ａ＋ｂ≦１．０を満足する数である。）
を含む。また、本発明は、基板にフォトレジスト層を形成する工程と、フォトレジスト層の上層としてこの反射防止膜材料を用いて反射防止膜を形成する工程と、反射防止膜を形成後のレジスト層を露光する露光工程と、露光工程後に、現像液を用いる現像と上記反射防止膜の除去をこの順序もしくは反対の順序もしくは同時に行う現像・反射防止膜除去工程とを含んでなるパターン形成方法を提供する。現像・反射防止膜除去工程は、アルカリ水溶液を用いる現像によるレジストの現像と同時に上記反射防止膜の除去を行うことが好ましい。 The present invention relates to an antireflection film material comprising a polymer compound having a hydroxynaphthyl group or a carboxynaphthyl group suitable as a base resin for an antireflection film material used for microfabrication in a manufacturing process of a semiconductor element or the like, particularly ArF excimer laser light. The present invention relates to a pattern forming method suitable for using (193 nm) as an exposure light source.
Specifically, the present invention provides an antireflection film material containing a polymer compound having a hydroxy naphthyl group or a carboxy naphthyl group. This polymer compound is preferably a repeating unit A or B represented by the following general formula

(In the above formula, R ²¹ and R ²² independently represent the same or non-identical methyl group or hydrogen atom, X and Y each represents a single bond, an oxygen atom or an ester group, and m and n are 1 or 2 and a and b are numbers satisfying 0 ≦ a ≦ 1.0, 0 ≦ b ≦ 1.0, and 0 <a + b ≦ 1.0.)
including. The present invention also includes a step of forming a photoresist layer on a substrate, a step of forming an antireflection film using the antireflection film material as an upper layer of the photoresist layer, and a resist layer after forming the antireflection film. providing an exposure step of exposing, after eXPOSURE step, the development and the antireflection film that order or reverse order or pattern forming method of performing comprising a developer-antireflection film removing process at the same time the removal of the used developer solution To do. In the development / antireflection film removing step, it is preferable to remove the antireflection film simultaneously with development of the resist by development using an alkaline aqueous solution.

  As a resist upper layer antireflection film, an antireflection film having a naphthalene skeleton has been devised in order to provide appropriate absorption for obtaining a high antireflection effect. As described above, polyvinyl naphthalene has a very low refractive index of 1.2 at a wavelength of 193 nm. In addition, since the absorption at 193 nm is relatively small, as described above, the resist size variation due to the film thickness variation of the upper antireflection film on the step can be suppressed as much as possible. Furthermore, the present invention is characterized by a repeating unit of a naphthyl group pendant with a hydroxy group or a carboxy group. Thus, an upper layer antireflection film capable of alkali development can be obtained.

The present invention provides an antireflection film material containing a polymer compound having a hydroxy naphthyl group or a carboxy naphthyl group, but preferably an antireflection film having a refractive index of 1.42 or less at a wavelength of 200 to 180 nm. .
Specific examples of the vinyl naphthalene having a hydroxy group as a repeating unit in the polymer contained in the resist upper layer film material of the present invention are shown below.

  Specific examples of the vinyl naphthalene having a carboxyl group can be given below.

Next, preferably a fluorine-containing group for lowering the refractive index can be copolymerized.
The fluorine-containing repeating unit can be represented by the following general formula C (C1, C2). In addition, the molar fraction of the repeating unit C is represented by c.

(In the above formula, R ^{1 to} R ⁴ are each a hydrogen atom, a fluorine atom, an alkyl group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms partially or entirely substituted with fluorine, and 1 carbon atom. Is a group selected from alkyl ether groups partially or wholly substituted with fluorine, and may have a hydroxy group, and R ³ and R ⁴ are bonded to each other together with a carbon atom to which these are bonded. Any one of R ^{1 to} R ⁴ contains at least one fluorine atom, and R ⁵ represents a hydrogen atom, a fluorine atom, a methyl group, a trifluoromethyl group, or —CH _2. C (═O) OH R ⁶ is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, and may have an ester group, an ether group, a hydroxy group or an amide group. Good, but at least one fluorine atom No.)

  Specific examples of the monomer for obtaining the repeating unit (C1) are shown below.

  Specific examples of the monomer for obtaining the repeating unit (C2) include the following.

  In order to lower the refractive index, vinyl naphthalene having no hydroxy group can be copolymerized as a repeating unit D component (the molar fraction of the repeating unit D is d). Specific examples of vinyl naphthalenes are given below.

Next, copolymerization of repeating units E (E1 to E5) having a carboxyl group or a sulfo group (with the molar fraction of the repeating unit E as e) in order to improve alkali solubility and in some cases become water-soluble. Can do.

(In the formula, R ⁷ and R ⁹ are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ⁸ is a single bond or a linear, branched or cyclic group having 1 to 4 carbon atoms. An alkylene group which may be substituted with fluorine or an ether group, and R ¹² is a single bond, a straight chain having 1 to 4 carbon atoms, branched or A cyclic alkylene group, R ¹⁰ is an alkylene group having 1 to 10 carbon atoms, R ⁹ and R ¹¹ are a hydrogen atom or a methyl group, X is a carboxyl group or a sulfo group, and Y is − O- or -NH-, p is an integer of 0 to 10, q is an integer of 1 to 10. The sulfo group may be an amine salt.)

  Specific examples of the monomer for obtaining the repeating unit represented by the general formula (E1) can be given below.

  Specific examples of the repeating unit represented by the general formula (E3) can be given below.

  Specific examples of the repeating unit represented by the general formula (E4) include the following.

  Specific examples of the repeating unit represented by the general formula (E5) include the following.

  In the above general formula, the molar fractions a, b, c, d, e of the repeating units A, B, C, D, E are 0 ≦ a ≦ 1.0, 0 ≦ b ≦ 1.0, 0 <a + b. ≦ 1.0, 0 ≦ c ≦ 0.9, 0 ≦ d ≦ 0.9, 0 ≦ e ≦ 0.9, preferably 0 ≦ a ≦ 0.9, 0 ≦ b ≦ 0.9, 0.05 ≦ a + b ≦ 0.9, 0 ≦ c ≦ 0.8, 0 ≦ d ≦ 0.8, 0 ≦ e ≦ 0.8, more preferably 0 ≦ a ≦ 0.8, 0 ≦ b ≦ 0.8, The ranges are 0.07 ≦ a + b ≦ 0.8, 0 ≦ c ≦ 0.7, 0 ≦ d ≦ 0.7, 0 ≦ e ≦ 0.7, and a + b + c + d + e = 1.

  By adjusting the ratio of the total of hydroxyl group, carboxyl group naphthalene olefin, fluorine-containing repeat unit, and repeat unit having carboxyl group and sulfo group, alkali-soluble, low refractive index and preventing mixing with resist Polymer. When the ratio of c which is a fluorine-containing group is high, mixing with the resist can be prevented and the refractive index is lowered, but when it is too high, the alkali solubility is lowered. If the ratio of e which is an alkali-soluble group is high, the alkali solubility is improved, but if it is too high, the refractive index increases.

  The polymer compound used for the resist protective film material of the present invention has a polystyrene-reduced weight average molecular weight of 1,000 to 500,000, preferably 2,000 to 30,000, as determined by gel permeation chromatography (GPC). It is preferable. If the weight average molecular weight is too small, mixing with the resist material may occur. If the weight average molecular weight is too large, problems may occur in the film-forming properties after spin coating, or alkali solubility may be reduced.

In order to synthesize these polymer compounds, one method is to add a monomer having an unsaturated bond to obtain repeating units A to E in an organic solvent, add a radical initiator, perform heat polymerization, and then polymer compound. Can be obtained. Examples of the organic solvent used at the time of polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane, methanol, ethanol, and isopropanol. Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile (AIBN), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2′-azobis (2-methylpropyl). Pionate), benzoyl peroxide, lauroyl peroxide and the like can be exemplified, and the polymerization is preferably carried out by heating to 50 to 80 ° C. The reaction time is 2 to 100 hours, preferably 5 to 20 hours. The sulfo group in the monomer stage is an alkali metal salt and may be converted to a sulfonic acid residue by acid treatment after polymerization.
The solvent used is not particularly limited, but a solvent that dissolves the resist layer is not preferable. For example, ketones such as cyclohexanone and methyl-2-n-amyl ketone used as a resist solvent, 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol Alcohols such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate , Ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, 3-ethoxy Ethyl propionate, acetate tert- butyl, tert- butyl propionate, and esters such as propylene glycol monobutyl -tert- butyl ether acetate is not preferable.

Examples of the solvent that does not dissolve the resist layer include non-polar solvents such as higher alcohols having 4 or more carbon atoms, toluene, xylene, anisole, hexane, cyclohexane, decane, and ether. In particular, higher alcohols having 4 or more carbon atoms and ethers having 8 to 12 carbon atoms are preferably used. Specifically, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2- Pentanol, 3-pentanol, tert-amyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-diethyl-1-butanol, 2-methyl- 1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl- 3-pentanol, cyclohexanol, diisopropyl ether, diisobutyl ether, diisopentyl ether, di-n-pentyl ether, methylcyclopentyl ether, methylcyclohexyl ether, di-n-butyl ether, di-secbutyl ether, diisopentyl ether, Examples include di-sec-pentyl ether, di-t-amyl ether, and di-n-hexyl ether.
By making the sulfo group of the repeating unit E into an amine salt, the base polymer can be made water-soluble, and water can be used as a solution for dilution.

On the other hand, a fluorine-based solvent can be preferably used because it does not dissolve the resist layer.
Examples of such fluorine-substituted solvents include 2-fluoroanisole, 3-fluoroanisole, 4-fluoroanisole, 2,3-difluoroanisole, 2,4-difluoroanisole, 2,5-difluoroanisole, 5, 8-difluoro-1,4-benzodioxane, 2,3-difluorobenzyl alcohol, 1,3-difluoro-2-propanol, 2 ′, 4′-difluoropropiophenone, 2,4-difluorotoluene, trifluoroacetaldehyde Ethyl hemiacetal, trifluoroacetamide, trifluoroethanol, 2,2,2-trifluoroethyl butyrate, ethyl heptafluorobutyrate, ethyl heptafluorobutyl acetate, ethyl hexafluoroglutaryl methyl, ethyl-3-hydroxy 4,4,4-trifluorobutyrate, ethyl-2-methyl-4,4,4-trifluoroacetoacetate, ethyl pentafluorobenzoate, ethyl pentafluoropropionate, ethyl pentafluoropropynyl acetate, ethyl perfluoroocta Noate, ethyl-4,4,4-trifluoroacetoacetate, ethyl-4,4,4-trifluorobutyrate, ethyl-4,4,4-trifluorocrotonate, ethyltrifluorosulfonate, ethyl-3 -(Trifluoromethyl) butyrate, ethyl trifluoropyruvate, S-ethyl trifluoroacetate, fluorocyclohexane, 2,2,3,3,4,4,4-heptafluoro-1-butanol, 1,1,1 , 2,2,3,3-heptafluoro-7,7-dimethyl Til-4,6-octanedione, 1,1,1,3,5,5,5-heptafluoropentane-2,4-dione, 3,3,4,4,5,5,5-heptafluoro- 2-pentanol, 3,3,4,4,5,5,5-heptafluoro-2-pentanone, isopropyl 4,4,4-trifluoroacetoacetate, methyl perfluorodenanoate, methyl perfluoro (2 -Methyl-3-oxahexanoate), methyl perfluorononanoate, methyl perfluorooctanoate, methyl-2,3,3,3-tetrafluoropropionate, methyl trifluoroacetoacetate, 1,1, 1,2,2,6,6,6-octafluoro-2,4-hexanedione, 2,2,3,3,4,4,5,5-octafluoro-1-pentanol, 1H, H, 2H, 2H-perfluoro-1-decanol, perfluoro (2,5-dimethyl-3,6-dioxane anionic) acid methyl ester, 2H-perfluoro-5-methyl-3,6-dioxanonane, 1H 1H, 2H, 3H, 3H-perfluorononane-1,2-diol, 1H, 1H, 9H-perfluoro-1-nonanol, 1H, 1H-perfluorooctanol, 1H, 1H, 2H, 2H-perfluoro Octanol, 2H-perfluoro-5,8,11,14-tetramethyl-3,6,9,12,15-pentaoxaoctadecane, perfluorotributylamine, perfluorotrihexylamine, perfluoro-2,5 8-trimethyl-3,6,9-trioxadodecanoic acid methyl ester, perfluorotripentyl Min, perfluorotripropylamine, 1H, 1H, 2H, 3H, 3H-perfluoroundecane-1,2-diol, trifluorobutanol 1,1,1-trifluoro-5-methyl-2,4-hexanedione 1,1,1-trifluoro-2-propanol, 3,3,3-trifluoro-1-propanol, 1,1,1-trifluoro-2-propyl acetate, perfluorobutyltetrahydrofuran, perfluoro (butyl Tetrahydrofuran), perfluorodecalin, perfluoro (1,2-dimethylcyclohexane), perfluoro (1,3-dimethylcyclohexane), propylene glycol trifluoromethyl ether acetate, propylene glycol methyl ether trifluoromethyl acetate, trifluorome Butyl butyl acetate, methyl 3-trifluoromethoxypropionate, perfluorocyclohexanone, propylene glycol trifluoromethyl ether, butyl trifluoroacetate, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione 1,1,1,3,3,3-hexafluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 2,2,3,4 , 4,4-hexafluoro-1-butanol, 2-trifluoromethyl-2-propanol, 2,2,3,3-tetrafluoro-1-propanol, 3,3,3-trifluoro-1-propanol, 4,4,4-trifluoro-1-butanol and the like can be used, and one of these can be used alone or in admixture of two or more. But it is not limited thereto.

The pattern forming method using the water-insoluble and alkali-soluble antireflection film (upper layer film) material of the present invention will be described.
First, an alkali-soluble antireflection film (upper layer film) material is formed on the photoresist layer by spin coating or the like. The film thickness is preferably in the range of 10 to 500 nm, but a film thickness having a high antireflection effect is set. The film thickness having a high antireflection effect is an odd multiple of λ / 4n when considered with normal incident light, and is an odd multiple of 37 nm when λ (193 nm) and refractive index n (1.30).
The exposure method can exhibit a higher antireflection effect in dry exposure in which the space between the antireflection film and the projection lens is a gas such as air or nitrogen. In the case of immersion immersion lithography using water, the difference between the refractive index of water and the refractive index of the resist is smaller than the difference between the refractive index of the atmosphere and the refractive index of the resist. Decreases. Incidentally, when the refractive index of the resist protective film in the case of water immersion is obtained, the square root 1.54 of 1.44 (the refractive index of water) × 1.70 (the refractive index of the resist) has the highest antireflection effect. Is the refractive index.

The antireflection film of the present invention is formed on the resist film after pre-baking. Pre-baking after applying the antireflection film material can be appropriately performed, and the temperature is in the range of 50 to 150 ° C. and the time is in the range of 5 to 200 seconds.
After forming the antireflection film, exposure is performed by KrF or ArF lithography.

After the exposure, post-exposure baking (PEB) is preferably performed.
After the exposure, a development / antireflection film removing step is performed in which development using a developer, preferably an alkali developer, and removal of the antireflection film are performed in this order or in the opposite order or simultaneously.
Development is preferably performed for 10 to 300 seconds using an alkali developer.
2.38 mass% tetramethylammonium hydroxide aqueous solution is generally widely used as the alkali developer, and the resist protective film is peeled off and the resist film is developed simultaneously.
The antireflection film may be removed using water or an organic solvent before development with an alkali developer.
The development using the alkaline developer and the removal of the antireflection film may be performed in this order or in the reverse order, but preferably the antireflection film is removed simultaneously with the development of the resist by the development using the aqueous alkali solution.

  The type of resist material is not particularly limited. It may be a positive type or a negative type, and may be an ordinary hydrocarbon-based single layer resist material or a bilayer resist material containing silicon atoms. The resist material used in KrF exposure is a polyhydroxystyrene or polyhydroxystyrene- (meth) acrylate copolymer as a base resin, in which a part or all of the hydrogen atoms of hydroxy groups or carboxyl groups are substituted with acid labile groups. Coalescence is preferably used. In addition, (meth) arylate represents an acrylate and / or a methacrylate.

  The resist material in ArF exposure must have a structure that does not contain an aromatic as a base resin. Specifically, polyacrylic acid or a derivative thereof, norbornene derivative-maleic anhydride alternating polymer and polyacrylic acid or a derivative thereof are used. Tri- or quaternary copolymer, tetracyclododecene derivative-maleic anhydride alternating polymer and polyacrylic acid or a derivative thereof, or ternary copolymer, norbornene derivative-maleimide alternating polymer and polyacrylic acid or the like Tri- or quaternary copolymers with derivatives, tetracyclododecene derivative-maleimide alternating polymers and ternary or quaternary copolymers with polyacrylic acid or its derivatives, and two or more of these, or polynorbornene and One or more polymer polymerizations selected from metathesis ring-opening polymers It is preferably used.

EXAMPLES Hereinafter, although a synthesis example, an Example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In the examples, GPC is gel permeation chromatography, and the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were determined.
Moreover, the structural formula of the monomers 1-2 used by the synthesis example is shown below.

[Synthesis Example 1]
To a 200 mL flask, 8.5 g of 6-hydroxy-2-vinylnaphthalene, 7.5 g of monomer 1, 2.2 g of methacrylic acid, and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 1 was obtained.

[Synthesis Example 2]
To a 200 mL flask was added 12.7 g of 6-hydroxy-2-vinylnaphthalene, 4.5 g of monomer 1, 0.9 g of methacrylic acid, and 40 g of methanol as a solvent. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 3]
To a 200 mL flask, 11.9 g of 6-carboxy-2-vinylnaphthalene, 12.0 g of monomer 1 and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 4]
To a 200 mL flask was added 13.7 g of 5-hydroxy-1-methylnaphthyl methacrylate, 6.0 g of monomer 1, 1.7 g of methacrylic acid, and 40 g of methanol as a solvent. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 5]
To a 200 mL flask was added 8.5 g of 6-hydroxy-2-vinylnaphthalene, 8.9 g of 4-sulfobutyl acrylate and methacrylic acid, and 40 g of methanol as a solvent. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 6]
To a 200 mL flask, 13.6 g of 6-hydroxy-2-vinylnaphthalene, 9.4 g of perfluoro (4-methyl-3,6-dioxaoct-7-ene) sulfonyl fluoride, and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. This reaction solution was treated with a 5% aqueous sodium hydroxide solution, converted to sodium chloride, treated with a 3% aqueous nitric acid solution to form a sulfo group, washed with water several times, and then crystallized in hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 7]
To a 200 mL flask, 8.5 g of 6-hydroxy-2-vinylnaphthalene, 12.2 g of monomer 2, 2.2 g of methacrylic acid, and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 7 was obtained.

[Synthesis Example 8]
To a 200 mL flask, 17.0 g of 6-hydroxy-2-vinylnaphthalene and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 8 was obtained.

[Synthesis Example 9]
To a 200 mL flask, 13.6 g of 6-hydroxy-2-vinylnaphthalene, 2.0 g of methacrylic acid, and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, the molecular weight was confirmed by GPC, and Example polymer 9 was obtained.

[Synthesis Example 10]
To a 200 mL flask, 11.9 g of 6-carboxy-2-vinylnaphthalene, 6.2 g of 1-vinylnaphthalene, and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Synthesis Example 11]
To a 200 mL flask, 14.4 g of 6-hydroxy-2-vinylnaphthalene, 0.9 g of methacrylic acid, 1.5 g of 1-vinylnaphthalene, and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, and the molecular weight was confirmed by GPC.

[Comparative Synthesis Example 1]
Monomer 1 (15.0 g), methacrylic acid (4.9 g), and methanol (40 g) as a solvent were added to a 200 mL flask. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, the molecular weight was confirmed by GPC, and Comparative polymer 1 was obtained.

[Comparative Synthesis Example 2]
To a 200 mL flask, 8.1 g of 1-vinylnaphthalene, 7.5 g of monomer 1, 2.2 g of methacrylic acid, and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was ¹ H-NMR, the molecular weight was confirmed by GPC, and the polymer was Comparative Example 2.

[Comparative Synthesis Example 3]
To a 200 mL flask, 8.1 g of 1-vinylnaphthalene, 4.9 g of methacrylic acid, and 40 g of methanol as a solvent were added. The reaction vessel was cooled to −70 ° C. in a nitrogen atmosphere, and vacuum degassing and nitrogen flow were repeated three times. After raising the temperature to room temperature, 0.3 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was added as a polymerization initiator, and the temperature was raised to 65 ° C., followed by reaction for 25 hours. The reaction solution was crystallized from hexane to isolate the resin. The composition of the obtained resin was confirmed by ¹ H-NMR, the molecular weight was confirmed by GPC, and Comparative polymer 3 was obtained.

Evaluation Example A resist upper layer antireflection film solution having the composition shown in Table 1 was mixed and filtered through a 0.2 micron polypropylene filter to prepare an upper layer antireflection film solution.
The resist upper layer antireflection film solution was spin-coated on the Si substrate and pre-baked at 100 ° C. for 60 seconds to prepare a resist upper layer antireflection film having a thickness of 50 nm.
J. et al. A. Using a spectroscopic ellipsometry manufactured by Woollam, n value (real part of refractive index) and k value (quenching coefficient: imaginary part of refractive index) were determined as the refractive index of the resist antireflection film at a wavelength of 193 nm.
Further, the wafer on which the resist protective film was formed by the above method was developed with an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution for 30 seconds, and the film thickness after development was measured. Table 1 shows the results.

  As shown in Table 1, in RTC-2, it was difficult to remove the antireflection film, and a 50 nm antireflection film remained.

Example of exposure evaluation Resist polymer 5 g, PAG 0.35 g and quencher 0.076 g shown below were dissolved in 45 g of propylene glycol monoethyl ether acetate (PGMEA) solution, filtered through a 0.2 micron polypropylene filter, A solution was made. A resist solution was spin-coated on a Si substrate subjected to hexamethyldisilazane (HMDS) vapor prime treatment, and baked at 110 ° C. for 60 seconds to prepare a resist film. At this time, a resist film having a film thickness of 200 to 300 nm was formed by changing the rotation speed. When forming the resist upper layer antireflection film, a protective film was spin-coated on the resist film and baked at 100 ° C. for 60 seconds.
Next, it is exposed with a Nikon ArF scanner S307E (NA0.85 σ0.93 4/3 annular illumination, 6% halftone phase shift mask), baked (PEB) at 100 ° C. for 60 seconds, and 2.38 mass. Development was performed with% TMAH developer for 30 seconds.
As the resist upper-layer antireflection film, a film thickness of 24 nm of TC-1 was used as an example, and a film thickness of no upper film (no Tarc) and a film thickness of 30 nm of RTC-1 were used as comparative examples. When there is no upper layer film, the exposure is 33 mJ / cm ² , RTC-1 is 34 mJ / cm ² , and TC-1 is 28 mJ / cm ^{2 with} a constant exposure of 100 nm CD when the resist film thickness is changed. The length was measured with (S-9380 manufactured by Hitachi, Ltd.). The results are shown in FIG. In addition, 100 nmCD shows the dimension of the resist width in the line width of a 100 nm line and space pattern.

As shown in FIG. 1, the resist upper layer antireflection film having a hydroxy naphthyl group or a carboxy naphthyl group of the present invention has good alkali solubility and has a dimension even when the resist film thickness varies due to a low refractive index. Fluctuation is small and has an excellent antireflection effect.
On the other hand, a film that does not use an antireflection film or RTC-1 has a low antireflection effect and a large dimensional variation when the resist film thickness is varied.

It is a figure which shows the relationship between a resist film thickness and 100 nmCD.

Claims (4)

A resist upper-layer antireflection film material comprising a polymer compound having a hydroxynaphthyl group or a carboxynaphthyl group. The polymer compound is a repeating unit A or B represented by the following general formula

(In the above formula, R ²¹ and R ²² independently represent the same or non-identical methyl group or hydrogen atom, X and Y each represents a single bond, an oxygen atom or an ester group, and m and n are 1 or 2 and a and b are numbers satisfying 0 ≦ a ≦ 1.0, 0 ≦ b ≦ 1.0, and 0 <a + b ≦ 1.0.)
The resist upper layer antireflection film material according to claim 1, comprising:   Forming a photoresist layer on the substrate; forming an antireflection film using the antireflection film material according to claim 1 or 2 as an upper layer of the photoresist layer; and forming the antireflection film. An exposure process for exposing the subsequent resist layer, and a development / antireflection film removal process in which development using a developer and removal of the antireflection film are performed in this order or in the opposite order or simultaneously after the exposure process. Pattern forming method.   The pattern formation method according to claim 3, wherein the development / antireflection film removing step removes the antireflection film simultaneously with development of the resist by development using an alkaline aqueous solution.

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