KR20090049204A - Polymer for immersion photoresist and resist compositions thereof - Google Patents

Abstract

The present invention relates to a immersion photoresist polymer and a composition for immersion photoresist comprising the same, and more particularly, to a immersion photoresist polymer represented by the following formula (100).

Formula 100

R _{1 in the} above formula And R ₄ each independently represent a hydrogen atom, an ether group, an ester group, a carbonyl group, an acetal group, an epoxy group, a nitrile group, or an alkyl group having 1 to 20 carbon atoms, including or without an aldehyde group, and R ₂ is hydrogen or a methyl group R ₃ is a linear, branched alkyl or cycloalkyl group having 1 to 10 carbon atoms, X is H or CF ₃ , and l, m, n are each a number representing a repeating unit in the main chain, and l + m + n = 1, 0.1 <l / (l + m + n) ≦ 0.6, 0.1 <m / (l + m + n) ≦ 0.6, 0.1 <n / (l + m + n) ≦ 0.4.

The immersion photoresist polymer of the present invention has sufficient transmittance at KrF (248 nm) and ArF (193 nm) exposure wavelengths during immersion exposure, and modifies the properties of the resist film surface after photoresist coating to form a stable film against water. It is possible to prevent the elution from the surface and to adjust the appropriate receiving angle value required for the immersion exposure. In addition, it is possible to minimize water mark defects or bubble defects that may occur during irradiation.

Additives for immersion photoresists, immersion photoresist

Description

Polymer for immersion photoresist and composition comprising the same

The present invention relates to a liquid immersion photoresist polymer and a composition comprising the same, and more particularly, by being used as an additive in an immersion photoresist composition, damage of the resist by water used during immersion exposure, or leaching of various additives into water in the resist. The present invention relates to a polymer which prevents the phenomenon of leaching, adjusts to have an appropriate contact angle value, reduces defects after light irradiation and reduces line edge roughness of the resist.

In manufacturing a semiconductor device or the like, a stepper-type or step-and-scan type projection exposure apparatus is used which transfers a reticle pattern as a photomask to each shot region on a photoresist-coated wafer via a projection optical system.

The resolution of the projection optical system provided in the projection exposure apparatus increases as the exposure wavelength to be used is shorter and the numerical aperture of the projection optical system is larger. For this reason, the exposure wavelength, which is the radiation wavelength used in the projection exposure apparatus, is shortening year by year as the integrated circuit becomes finer, and the numerical aperture of the projection optical system is also increasing.

In addition, when performing exposure, the depth of focus is also important as is the resolution. The resolution R and the depth of focus δ are each represented by the following equation.

R = k1λ / NA

δ = k2λ / NA ²

Here, lambda is the exposure wavelength, NA is the numerical aperture of the projection optical system, and k1 and k2 are the process coefficients. When the same resolution R is obtained, radiation having a shorter wavelength can be used to obtain a larger depth of focus.

In this case, a photoresist film is formed on the exposed wafer surface, and the pattern is transferred to the photoresist film. In the conventional projection exposure apparatus, the space in which the wafer is placed is filled with air or nitrogen. At this time, if the space between the wafer and the lens of the projection exposure apparatus is filled with a medium having a refractive index n, the resolution R and the depth of focus δ are each represented by the following equation (λ / n).

R = k1 (λ / n) / NA

δ = k2nλ / NA ²

For example, in the ArF process, when water is used as the medium, when the refractive index (n) in the water of light having a wavelength of 193 nm (n) = 1.44 is used, the resolution (R ) Is 69.4% (R = k1 · (λ / 1.44) / NA), and the depth of focus is 144% (δ = k2 · 1.44λ / NA ^{2 )} .

The projection exposure method capable of shortening the wavelength of radiation for exposure and transferring a finer pattern is called immersion exposure, and is considered to be an essential technique for miniaturization of lithography, especially lithography on the order of tens of nm. Application on the wafer in the immersion exposure method. The formed photoresist film and the lens of the projection exposure apparatus are in contact with water. Therefore, water may penetrate into the photoresist film and the resolution of the photoresist may be lowered. In addition, the lens of the projection exposure apparatus may contaminate the lens surface by eluting the components constituting the photoresist in water.

Accordingly, an object of the present invention is to replace the upper layer film or the upper layer film which can prevent the dissolution into the water layer through the photoresist surface modification coated on the wafer and reduce various defects that may be caused by using water during immersion exposure. It is to provide a polymer for liquid immersion photoresist that reduces affinity with water.

Another object of the present invention is to provide a composition for immersion photoresist comprising the above polymer.

In order to achieve the above object, the present invention provides a polymer for immersion photoresist represented by the following formula (100).

Formula 100

Wherein R ₁ and R ₄ each independently represent a hydrogen atom, an ether group, an ester group, a carbonyl group, an acetal group, an epoxy group, a nitrile group, or an alkyl group having 1 to 20 carbon atoms with or without an aldehyde group, and R ₂ Is a hydrogen or methyl group, R ₃ is a linear, branched alkyl or cycloalkyl group having 1 to 10 carbon atoms, X is H or CF ₃ , and l, m, n are each a number representing a repeating unit in the main chain, l + m + n = 1, 0.1 <l / (l + m + n) ≤0.6, 0.1 <m / (l + m + n) ≤0.6, 0.1 <n / (l + m + n) ≤0.4 to be.

The copolymer used in the present invention is a compound consisting of a (meth) acrylate derivative represented by the repeating unit l, a fluorine derivative represented by the repeating unit m, norbornene represented by n, and a derivative thereof, Represented by the formula 1 to 3, respectively.

Formula 1

Formula 2

Formula 3

Resists currently used for immersion exposure may or may not use a top coat material, but the limit of elution from resist to water is generally 1.0 x ^10-12 mol / cm ² , regardless of whether or not it is used. If this condition is not used, there may be a problem in the pattern implemented by the resist, but above all, the higher the amount of the photoacid generator or other additives, the more the contamination of the lens used during exposure may increase.

In addition, water mark defects or bubble defects occur due to the different degree of defects depending on the contact angle value in the resist coating. This tendency is closely related to the scan speed of the exposure machine. This can be a factor in lowering the hourly yield of the device chip.

Therefore, as a method to reduce the amount of elution and reduce the number of defects, there is a method of adjusting the Receding Angle value on the surface of the resist. By measuring the amount of the elution, the amount of the elution can be estimated to some extent and the degree of the defect can be estimated.

Therefore, the receding angle value can reduce the degree of contamination of the exposure lens by estimating the amount of elution of various additives in the resist, and can increase the scan speed of the exposure machine by reducing defects. The adjustment of the receding angle value is hardly controlled by the resist itself, and therefore, a method using a top coat material can be used or a fluorine-based additive as in the present invention.

Examples of the monomer of Formula 1 are preferably as follows, but the structure of the cycloolefin is not limited thereto. The content is preferably used more than 10 mol% to 40 mol%.

Examples of the monomer of Chemical Formula 2 are preferably as follows, and the content thereof is more than 10 mol% to 60 mol%.

Examples of the monomer of Formula 3 are preferably as follows, but the structure of (meth) acrylate is not limited thereto.

R ₂ in the above means hydrogen or a methyl group.

The fluorine-based (meth) acrylate compound of the formula (2) includes a repeating unit having a group containing a fluorine atom in its side chain, and a repeating unit having a group containing the fluorine atom in its side chain is at least It contains a trifluoroalkyl group in the (alpha) position.

Formula 3 preferably includes an acid dissociable functional group. It is because alkali-soluble resin by the carboxyl group produced | generated after exposure is possible, and usually more than 10 mol%-60 mol% is preferable.

If the content is too small, the solubility in the alkaline aqueous solution, which is a developer, becomes low, which may cause a problem after development. In addition, when there are too many of these repeating units, the stability with respect to the water at the time of immersion exposure may become low, and it may elute in water at the time of exposure, and may contaminate the lens of a projection exposure apparatus.

The resin can be used as an additive to the resist to control hydrophilicity or hydrophobicity on the surface of the resist. In terms of defects, the resin tends to be different depending on the receding angle value. In general, when the amount of the additive in the resist was increased, the receding angle value increased, and the defect pattern caused by the increase of the water mark defect decreased significantly with the increase of the amount, whereas the bubble defect showed a slight decrease. Showed a significant increase from a peak. When the amount of the additive was increased and the amount of the photoacid generator eluted in the resist was measured, the amount of the eluted was significantly decreased as the amount thereof increased.

The norbornene or norbornene derivative of the repeating unit selected from Chemical Formula 1 of the resin has a property of leading to a copolymer having a modified helical structure, so that the solubility with a solvent of the conventional (meth) acrylate copolymer is not good. There is a characteristic that greatly improves the point.

In addition, when copolymerizing only (meth) acryl, it is difficult to control the molecular weight and it is not easy to prepare a polymer having a relatively low molecular weight, but when introducing norbornene derivatives such as the above formula into the polymerization reaction, Compared to the case where no norbornene derivatives are used, a polymer having a relatively low molecular weight can be produced, and as a radical quencher, it can act as a molecular weight regulator and improve etching resistance.

Such multicomponent copolymers may be block copolymers, random copolymers or graft copolymers.

The polymerization method of the polymer of the present invention may be polymerized by conventional methods, but radical polymerization is preferred. Radical polymerization initiators are common such as azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), lauryl peroxide, azobisisocapronitrile, azobisisovaleronitrile, and t-butyl hydroperoxide. There is no particular limitation as long as it is used as a radical polymerization initiator. The polymerization method can be carried out by bulk polymerization, solution polymerization, suspension polymerization, bulk suspension polymerization, emulsion polymerization, etc.The polymerization solvent is benzene, toluene, xylene, halogenated benzene, diethyl ether, tetrahydrofuran, esters, etc. At least one selected from ethers, lactones, ketones, amides and alcohols.

 The polymerization temperature of the polymers of the present invention is appropriately selected and used depending on the type of catalyst. The molecular weight distribution of the polymer can be appropriately adjusted by changing the amount of use of the polymerization initiator and the reaction time. It is preferable to remove the unreacted monomers and by-products remaining in the reaction mixture after the polymerization is completed by precipitation with a solvent.

The polystyrene reduced weight average molecular weight (hereinafter referred to as "Mw") by gel permeation chromatography (GPC) of the polymer of the present invention is usually 2,000 to 1,000,000, and considering the sensitivity, developability, applicability, heat resistance, etc. as a photoresist, 3,000-50,000 are preferable. 1.0-5.0 are preferable and, as for the molecular weight distribution of a polymer, 1.0-3.0 are especially preferable.

In another aspect, the present invention provides a composition for immersion photoresist comprising a polymer, a photoacid generator and an organic solvent for the immersion photoresist represented by the formula (100).

The liquid immersion photoresist composition of the present invention contains, as an additive, 0.01 mol% to 10 mol% of at least one polymer selected from the photoresist polymers represented by Chemical Formula 100 as an additive.

If the content is less than 0.1 mol%, elution of the acid generator on the resist surface occurs, and if it is more than 10 mol%, the problem of the receiving angle during immersion exposure becomes large.

As described above in detail, during the immersion exposure, a polymer containing a fluorinated compound and a cycloolefin in the photoresist is prepared and adjusted to have an appropriate contact angle value when used as an additive in the resist composition to reduce the elution of water from the surface of the resist. By reducing the affinity with water, it was possible to reduce defects such as water mark defects and bubble defects.

        EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely based on a synthesis example and an Example, but this invention is not limited by the following synthesis example and an Example.

Polymer Synthesis

Example 1 Preparation of Polymer for Immersion Photoresist

1.79 g of norbornene, a monomer for polymerization, and 11.78 g of 1,4-dioxane, 1,4-dioxane, which was a polymerization solvent, were placed in a reactor. 2-methyl 2-adamantyl acrylate / 1,1,1,3,3,3-hexafluoro isopropyl methacrylate (1,1) 6.99g / 3g of 1,3,3,3-hexafluoro isopropyl methacrylate) were added, respectively, 1.45g of AIBN (2,2-azobis isobutyronitrile) as a polymerization initiator, 0.29g of thioglycolate as a polymerization regulator and a polymerization solvent. The solution mixed with 47.2 g of 1,4-dioxane was slowly added dropwise while refluxing at 75 ° C. for 2 hours under nitrogen gas injection. After the reaction was carried out for 3 hours while maintaining the temperature of the reactor at 75 ℃, it was cooled to room temperature. The reaction solution cooled to room temperature was precipitated in methanol solvent and filtered. After filtration, washing with the same solvent several times and drying under reduced pressure to obtain 4.77 g of a copolymer represented by the following formula (4).

 The weight average molecular weight (Mw) of this copolymer of polystyrene was 4,020, and dispersion degree was 1.53. In addition, the structure was confirmed by NMR (Varian), the results are shown in Figure 1, the results of GPC (gel permeation chromatography) is shown in Figure 11.

[Formula 4]

Example 2   Chemical formula 5 with  Displayed Immersion For photoresist  Polymer manufacturing

3-bicyclo [2,2,1] hept-5-en-2-yl-3-hydroxy propionic acid t-butyl ester (3-bicyclo-2,2, The same compound was used as in Example 1, except that 4.53 g of 1-hept-5-ene-2-yl-3-hydroxy propionic acid t-butyl ester was used. 3.31 g of a copolymer represented by the formula (5) was obtained.

The polystyrene reduced weight average molecular weight of this copolymer (Mw) was 4,610 and dispersion degree was 1.32. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 2, the results of GPC (gel permeation chromatography) is shown in Figure 12.

[Formula 5]

Example 3   Chemical formula 6 with  Displayed Immersion For photoresist  Polymer manufacturing

2,2,2-trifluoroethyl methacrylate instead of 1,1,1,3,3,3-hexafluoro isopropyl methacrylate (1,1,1,3,3,3-hexafluoro isopropyl methacrylate) Except for using 3 g of (2,2,2-trifluoro ethyl methacrylate), the same compound as in Example 1 was used, and 8 g of a copolymer represented by the following Chemical Formula 6 was obtained under similar reaction conditions.

The polystyrene reduced weight average molecular weight of this copolymer (Mw) was 4,370 and dispersion degree was 1.67. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 3, the results of GPC (gel permeation chromatography) is shown in Figure 13.

[Formula 6]

Example 4   Chemical formula 7 with  Displayed Immersion For photoresist  Polymer manufacturing

1.90g norbornene, a monomer for polymerization, and 2-methyl-2-adamantyl methacrylate / 1,1,1,3,3,3-hexafluoroisopropyl The same compound was used as in Example 1, except that 7.91 g / 3 g of acrylate (1,1,1,3,3,3-hexafluoro isopropyl acrylate) was used. Next, 6.5 g of a copolymer represented by Chemical Formula 7 was obtained.

The polystyrene reduced weight average molecular weight of this copolymer (Mw) was 4,950 and dispersion degree was 1.57. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 4, and the results of GPC (gel permeation chromatography) is shown in Figure 14.

[Formula 7]

Example 5 Preparation of Polymer for Immersion Photoresist

1-isopropyl 1-adamantyl methacrylate (1-isopropyl-1-adamatane methacrylate) was used instead of 2-methyl 2-adamantyl methacrylate as a polymerization monomer. Except for using the same compound as in Example 4, 10.4 g of a copolymer represented by the following Chemical Formula 8 was obtained under similar reaction conditions.

The polystyrene reduced weight average molecular weight of this copolymer was (Mw) 7,220 and dispersion degree was 1.99. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 5, the results of GPC (gel permeation chromatography) is shown in Figure 15.

[Formula 8]

Example 6   Chemical formula 9 with  Displayed Immersion For photoresist  Polymer manufacturing

In Example 5, t-butyl acrylate (tert-butyl acrylate) is mixed and used, and 1,1,1,3,3,3-hexafluoro isopropyl acrylate (1,1,1,3,3, Example 5 using 1,1,1,3,3,3-hexafluoro isopropyl methacrylate (1,1,1,3,3,3-hexafluoro isopropyl methacrylate) instead of 3-hexafluoro isopropyl acrylate) As in the same compound was used, and 6.17 g of a copolymer represented by the following Chemical Formula 9 was obtained under similar reaction conditions.

The weight average molecular weight (Mw) of this copolymer of polystyrene was 5,890, and dispersion degree was 1.43. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 6, the results of GPC (gel permeation chromatography) is shown in Figure 16.

[Formula 9]

Example 7   Chemical formula 10 with  Displayed Immersion For photoresist  Polymer manufacturing

Instead of tert-butyl acrylate (tert-butyl acrylate) of the polymerization monomer of Example 6, using the same compound using 2-methyl cyclopentyl acrylate (2-methyl cyclopentyl acrylate) and under the same reaction conditions 6.47 g of a copolymer represented by 10 was obtained.

The weight average molecular weight (Mw) of this copolymer of polystyrene was 5,450, and dispersion degree was 1.54. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 7, the results of GPC (gel permeation chromatography) is shown in Figure 17.

[Formula 10]

Example 8 Preparation of Polymer for Immersion Photoresist

Instead of tert-butyl acrylate (tert-butyl acrylate) of the polymerization monomer of Example 6, using the same compound using 2-ethyl cyclopentyl acrylate (2-ethyl cyclopentyl acrylate), 7.41 g of a copolymer represented by the formula (11) was obtained.

The polystyrene reduced weight average molecular weight of this copolymer (Mw) was 5,330 and dispersion degree was 1.56. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 8, the results of GPC (gel permeation chromatography) is shown in Figure 18.

[Formula 11]

Example 9 Preparation of Polymer for Immersion Photoresist

2-methyl-2-adamantyl methacrylate (2-methyl-2 instead of 2-methyl-2-adamantyl acrylate) which is a polymerization monomer of Example 2 -adamantyl methacrylate) was used, and 2-ethyl cyclopentyl acrylate was added thereto to obtain 1.66 g of a copolymer represented by the following Chemical Formula 12 using the same reaction conditions.

The polystyrene reduced weight average molecular weight of this copolymer (Mw) was 4,670 and dispersion degree was 1.32. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 9, the results of GPC (gel permeation chromatography) is shown in Figure 19.

[Formula 12]

Example 10   Represented by Formula 13 Immersion For photoresist  Polymer manufacturing

3-bicyclo [2,2,1] hept-5-en-2-yl-3-hydroxy propionic acid t-butyl ester as a monomer for polymerization of Example 9 (3-bicyclo-2,2 Norbornene was used in place of, 1-hept-5-ene-2-yl-3-hydroxy propionic acid t-butyl ester) to obtain 4.13 g of a copolymer represented by the following Chemical Formula 13 under similar reaction conditions.

The polystyrene reduced weight average molecular weight of this copolymer (Mw) was 4,670 and dispersion degree was 1.41. In addition, the structure was confirmed by 1H-NMR (Varian), the results are shown in Figure 10, the results of GPC (gel permeation chromatography) is shown in Figure 20.

 [Formula 13]

Example 11   Preparation of Polymer Represented by Formula 14

In a similar manner to Example 1, the four components of the compound were copolymerized to obtain the following polymer compound suitable for the ArF excimer laser.

 [Formula 14]

<Resist Composition and Photoresist Thin Film Preparation>

2.5 parts by weight of triphenyl sulfonium nonaplate as an acid generator and 0.5 parts by weight of tetra methyl ammonium hydroxide as a basic additive based on 100 parts by weight of the copolymer obtained in Example 11 and the above example 1.0 parts by weight of the polymer of 1 to 10 as an additive was dissolved in 800 parts by weight of propylene glycol methylethyl acetate, and then filtered through a 0.2 µm membrane filter to prepare a resist composition.

Comparative Example 1

In Comparative Example 1, the polymer of Examples 1 to 10 is not used as an additive by using the copolymer of Chemical Formula 14, and has a (meth) acrylate and an olefin derivative, which are used in conventional resist compositions, as repeating units. Yes.

The resist composition solution obtained in Examples and Comparative Examples was spin coated to a thickness of 0.25 μm, and then dried at 110 ° C. for 90 seconds to form a film. The contact angle was measured by dropping a predetermined amount of distilled water on the formed film. Table 1 shows the results of the contact angles of the examples.

Table 1

Receding angle (°) Advanced angle (°) Example 1 82 94 Example 2 81 94 Example 3 80 92 Example 4 68 80 Example 5 79 93 Example 6 81 93 Example 7 80 93 Example 8 79 92 Example 9 81 94 Example 10 82 95

The acid dissociative group showed a smaller change in contact angle values than those used in a single species. Also, as the fluorine content in the α-position increased, the contact angle value tended to increase. Fluorine-substituted monomers have a tendency to decrease the leaching of the acid diffusion agent due to the increase in the contact angle value of the meth (acrylate) than the acrylate.

1.0 to 3.0 parts by weight of the polymer of Examples 1 to 3 as an additive was dissolved in 800 parts by weight of propylene glycol methylethyl acetate, and then filtered through a 0.2 μm membrane filter to prepare a resist composition. The resist composition solution obtained in Examples and Comparative Examples was spin coated to a thickness of 0.25 μm, and then dried at 110 ° C. for 90 seconds to form a film. A certain amount of pure water was dropped on the formed film and it coat | covered with 1 mm thickness. In addition, using the ArF excimer laser scanner (NA: 1.2, ASML1700i) to the formed film was exposed to the upper part of the water surface through a photomask, the elution degree of the acid diffusion agent in the pure water was measured.

Table 2 shows the leaching amount according to the additive amount.

[Table 2]

From the results in Table 2, the chemically amplified photoresist prepared from the resist composition containing the additive of the present invention had less elution at the resist surface than the comparative example including the conventional polymer without the additive, and immersion exposure. We could get the proper receiving angle needed for.

1 shows the ¹ H-NMR results of the polymer represented by the formula (4) of the present invention,

Figure 2 shows the ¹ H-NMR results of the polymer represented by the formula (5),

Figure 3 shows the ¹ H-NMR results of the polymer represented by the formula (6),

Figure 4 shows the ¹ H-NMR results of the polymer represented by the formula (7),

Figure 5 shows the ¹ H-NMR results of the polymer represented by the formula (8),

Figure 6 shows the ¹ H-NMR results of the polymer represented by the formula (9),

Figure 7 shows the ¹ H-NMR results of the polymer represented by the formula (10),

8 shows the ¹ H-NMR results of the polymer represented by Formula 11,

Figure 9 shows the ¹ H-NMR results of the polymer represented by the formula (12),

10 shows the ¹ H-NMR results of the polymer represented by Formula 13,

11 shows the results of gel permeation chromatography (GPC) of a polymer represented by Formula 4,

12 shows the GPC results of the polymer represented by Formula 5,

FIG. 13 shows GPC results of a polymer represented by Chemical Formula 6.

14 shows the GPC results of the polymer represented by the formula (7),

15 shows GPC results of a polymer represented by Formula 8,

16 shows the GPC results of the polymer represented by Formula 9,

Figure 17 shows the GPC results of the polymer represented by the formula (10),

18 shows GPC results of a polymer represented by Formula 11,

19 shows GPC results of a polymer represented by Formula 12.

20 shows the results of GPC of the polymer represented by the formula (13).

Claims (4)

A polymer for immersion photoresist represented by the following formula (100). Formula 100

R _{1 in the} above formula And R ₄ each independently represent a hydrogen atom, an ether group, an ester group, a carbonyl group, an acetal group, an epoxy group, a nitrile group, or an alkyl group having 1 to 20 carbon atoms, including or without an aldehyde group, and R ₂ is hydrogen or a methyl group R ₃ is a linear, branched alkyl or cycloalkyl group having 1 to 10 carbon atoms, X is H or CF ₃ , and l, m, n are each a number representing a repeating unit in the main chain, and l + m + n = 1, 0.1 <l / (l + m + n) ≦ 0.6, 0.1 <m / (l + m + n) ≦ 0.6, 0.1 <n / (l + m + n) ≦ 0.4. The polymer for immersion photoresist according to claim 1, wherein the weight average molecular weight is 3,000 to 50,000. Immersion photoresist composition comprising a polymer for immersion photoresist represented by the formula (100), a photoacid generator and an organic solvent. Formula 100

R _{1 in the} above formula And R ₄ each independently represent a hydrogen atom, an ether group, an ester group, a carbonyl group, an acetal group, an epoxy group, a nitrile group, or an alkyl group having 1 to 20 carbon atoms, including or without an aldehyde group, and R ₂ is hydrogen or a methyl group R ₃ is a linear, branched alkyl or cycloalkyl group having 1 to 10 carbon atoms, X is H or CF ₃ , and l, m, n are each a number representing a repeating unit in the main chain, and l + m + n = 1, 0.1 <l / (l + m + n) ≦ 0.6, 0.1 <m / (l + m + n) ≦ 0.6, 0.1 <n / (l + m + n) ≦ 0.4. The method according to claim 4, wherein 0.01 to 10 mol% of one or more polymers selected from polymers for photoresists comprising repeating units represented by Formulas 1, 2 and 3 are included as additives. A composition for immersion photoresist, characterized in that.

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