JP4483438B2 - Composition for antireflection film - Google Patents

Description

  The present invention relates to an antireflective coating composition that does not contain PFAS (Perfluoroalkyl sulfates) and has excellent temporal stability of the coating.

  In the manufacture of semiconductor devices, a lithography technique is applied in which a photoresist film is formed on a substrate such as a silicon wafer, selectively irradiated with actinic rays, then developed, and a resist pattern is formed on the substrate. Has been.

  In recent years, in order to obtain a higher degree of integration in an LSI, the processing line width in a lithography process has been rapidly miniaturized. In proceeding with the miniaturization of the processing line width, various proposals have been made for all lithography processes and materials used, including photoresists, antireflection films, exposure methods, exposure devices, developers, development methods, development devices, etc. ing.

  For example, when an antireflection film having a refractive index lower than the refractive index of the resist is provided on the resist layer, the width of the amplitude of the resist film thickness vs. sensitivity curve is reduced, and even when the film thickness of the resist layer varies, There is an advantage that the sensitivity variation is reduced and the dimensional variation is reduced. In addition, the use of such an antireflection film has an advantage of reducing a standing wave due to interference between incident light and reflected light or reflected light.

  On the other hand, a compound containing a fluorine atom exhibits a low refractive index due to the characteristics of having a large molecular volume of fluorine atoms and a small atomic refraction, and therefore a fluorine-containing compound-containing composition is proposed as the composition for the antireflection film. (For example, refer to Patent Document 1).

  However, PFAS (Perfluoroalkyl sulfates), which is an essential component of the antireflective coating composition proposed in Patent Document 1, has been regarded as a problem regarding safety from the viewpoint of accumulation in the human body and the environment. For example, in the United States EPA (Environmental Protection Agency) SNUR (Significant New Use Rule, dated March 11, 2002, etc.), there is a movement to set restrictions when importing and manufacturing. Under such circumstances, there is a strong demand for an anti-reflection film composition that does not use PFAS, that is, PFAS-free.

JP 10-003001 A (page 4-7)

  In view of the above situation, an object of the present invention is to provide a composition for an antireflection film that is PFAS-free and excellent in film stability.

  As a result of diligent studies to solve the above problems, the present inventors have found that the above problems can be solved by using a combination of a perfluoroalkylalkyl sulfonic acid and a specific organic amine, thereby completing the present invention. did.

That is, the present invention provides the following general formula (1)
_{C n F 2n + 1 (CH} 2 CH 2) m SO 3 H (1)
(In the formula, n represents an integer of 1 to 20, and m is an integer of 1 to 20.)
Containing at least one N-substituted ethylenediamine (B) and / or N-alkylmorpholine (C) selected from the group consisting of dimethylethylenediamine and diethylethylenediamine. An antireflection film composition is provided.

  According to the present invention, it contains a fluorine compound having a low refractive index that is highly accumulative in the human body and the environment, and has excellent stability over time of the film without using PFAS, which is regarded as a problem in environmental safety. An antireflective film composition can be provided.

The following general formula (1) used in the present invention
_{C n F 2n + 1 (CH} 2 CH 2) m SO 3 H (1)
(In the formula, n represents an integer of 1 to 20, and m is an integer of 1 to 20.)
The perfluoroalkylalkyl sulfonic acid (A) represented by the formula (1) has a low refractive index derived from a fluorine atom, can be developed with water, and is an essential component for exhibiting antireflection performance. If the perfluoroalkylalkylsulfonic acid (A) represented by the general formula (1) is absent, the refractive index of the film increases, and sufficient antireflection performance cannot be exhibited.

  In general, the larger the number of carbon atoms in the perfluoroalkyl group is, the larger the fluorine atom content is. Therefore, the low refractive index is excellent, but in the general formula (1), n exceeds 20 Since the crystallinity becomes high, cracks and the like occur in the resulting film, and the temporal stability is poor, which is not preferable. Further, considering the stability of the film over time and the optimization of the refractive index based on the fluorine content, n in the formula is preferably a compound of 4 to 12, more preferably n = 6 to 8. In addition, it is not preferred that m in the formula exceeds 20 because the low refractive index property as the obtained antireflection film cannot be maintained. Further, from the viewpoint of easily exhibiting low refractive index properties, m is preferably a compound in the range of 1 to 3, and further, the water solubility of perfluoroalkylalkyl sulfonic acid (A), From the viewpoint of stability over time and ease of synthesis, a compound with m = 1 is particularly preferred. In addition, the perfluoroalkylalkylsulfonic acid (A) represented by the general formula (1) may be used alone or as a mixture of two or more.

  The production method of the perfluoroalkylalkyl sulfonic acid (A) is not particularly limited. For example, the method described in US Pat. No. 3,825,577, that is, the sulfonyl halide containing a fluorinated alkyl group is about A hydrolysis reaction is carried out by heating at 100 ° C. for 8 hours in the presence of 100 times equivalent of water and about 5 times equivalent of concentrated sulfuric acid. After completion of the reaction, the reaction solution is extracted with diethyl ether to extract the ether. There may be mentioned a method in which perfluoroalkylalkylsulfonic acid is dissolved therein, and then the ether is removed by distillation.

N-substituted ethylenediamine (B) used in the present invention is excellent in stability over time of the resulting film, dimethylethylenediamine, diethyl ethylenediamine.

Although it does not specifically limit as N-alkylmorpholine (C) used by this invention, The following general formula ( 2 )
RN (C ₂ H ₄ ) ₂ O ( 2 )
(In the formula, R is an alkyl group having 1 to 4 carbon atoms.)
Is preferable because the resulting film is excellent in stability over time.

  The N-substituted ethylenediamine (B) and the N-alkylmorpholine (C) have a role of neutralizing the perfluoroalkylalkylsulfonic acid (A) and adjusting the pH of the composition for antireflection film. These amines can be used alone or in combination of two or more.

  In addition, from the viewpoint of maintaining the low refractive index of the resulting antireflection film and good stability over time of the film, when the component (A) is 1, the sum of the components (B) and (C) Is preferably 0.01 to 0.3 by weight.

  The composition for an antireflection film of the present invention is not limited except that the perfluoroalkylalkylsulfonic acid (A) and the N-substituted ethylenediamine (B) and / or the N-alkylmorpholine (C) are used. In addition, various aqueous polymers, additives, organic solvents, water, etc. that are usually used in antireflection coating compositions are arbitrarily selected according to the intended film performance, coating method, etc. I can do it.

  The aqueous polymer is used as a resin that is soluble or dispersible in water within a range that does not impair the desired antireflection property when it is desired to obtain excellent film formation stability over time. When the antireflection film is used for a photoresist, it is preferably an aqueous polymer that can be easily removed after the completion of the photoresist process, that is, with water, such as poly (vinyl alcohol), poly (acrylic). Acid), poly (vinyl pyrrolidone), poly (α-trifluoromethylacrylic acid), poly (vinyl methyl ether-co-maleic anhydride), poly (ethylene glycol-co-propylene glycol), poly (N-vinyl pyrrolidone) -Co-vinyl acetate), poly (N-vinylpyrrolidone-co-vinyl alcohol), poly (N-vinylpyrrolidone-co-acrylic acid), poly (N-vinylpyrrolidone-co-methyl acrylate), poly (N -Vinylpyrrolidone-co-methacrylic acid), poly (N-vinylpyrrolidone-co-methyl methacrylate), Poly (N-vinylpyrrolidone-co-maleic acid), poly (N-vinylpyrrolidone-co-dimethyl maleate), poly (N-vinylpyrrolidone-co-maleic anhydride), poly (N-vinylpyrrolidone-co-maleic acid) Itaconic acid), poly (N-vinylpyrrolidone-co-methyl itaconic acid), poly (N-vinylpyrrolidone-co-itaconic anhydride), fluorinated polyether, and the like. Poly (acrylic acid), poly (vinyl) Pyrrolidone), fluorinated polyethers, and the like are preferred. These aqueous polymers can be used alone or in admixture of two or more.

  The molecular weight of the aqueous polymer is not particularly limited, and is selected according to mechanical properties such as elongation and strength of the target film, film thickness, compatibility, coating method, and the like. The weight average molecular weight is preferably 1,000 to 1,000,000, more preferably 2,000 to 100,000. The aqueous polymer may be a homopolymer of hydrophilic units that are easily dissolved or dispersed in water, or a copolymer with other components. It is also possible to select components to be copolymerized depending on the strength, compatibility and the like. Moreover, there is no restriction | limiting in particular as a manufacturing method in any case of a homopolymer and a copolymer.

  As the additive, the desired performance is achieved from the viewpoint of improving the leveling property when applying the obtained composition for an antireflective film on a substrate, workability, control of the film thickness, and performance expression as an antireflective film. The surfactant is appropriately selected and used, and includes surfactants such as nonionic surfactants, anionic surfactants, and amphoteric surfactants. Nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene fatty acid diester, polyoxyfatty acid monoester, polyoxyethylene polyoxyethylene. Oxypropylene block polymers, acetylene glycol derivatives, etc., and anionic surfactants include alkyl diphenyl ether disulfonic acid and its ammonium salt or organic amine salt, alkyl diphenyl ether sulfonic acid and its ammonium salt or organic amine salt, alkylbenzene sulfone Acid, and ammonium salt or organic amine salt thereof, polyoxyethylene alkyl ether sulfate, and ammonium salt thereof Umum salts or organic amine salts, alkyl sulfuric acid, and ammonium salts or organic amine salts thereof include amphoteric surfactants such as 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, amidopropyl laurate Examples include hydroxysulfone betaine.

  The organic solvent is used for the purpose of improving applicability, and is preferably an organic solvent that dissolves 0.1% by weight or more in water, such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and the like. Alcohols, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate, ethyl acetate, and ethyl lactate, dimethylformamide, dimethyl sulfoxide, methyl cellosolve, cellosolve, butyl cellosolve, cellosolve acetate, alkyl cellosolve acetate, butyl carbitol, carbitol Examples include polar solvents such as acetate.

  There are no particular restrictions on the substrate on which the composition for antireflection film of the present invention is applied, for example, inorganic substances such as glass, quartz, and silicon, metals such as iron, copper, ferrite, cobalt, nickel, and aluminum, and alloys thereof. Thermoplastic resins such as polyethylene, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyesters such as polyethylene terephthalate, polyethylene 2,6 naphthalate, engineering plastics such as polyparaphenylene sulfite, polyamide resin, polyimide resin, NBR, Examples include various rubbers such as SBR, EPDM, silicone rubber, fluororubber, urethane resin, alkyd resin, phenol resin, ABS resin, epoxy resin, silicone resin, polycarbonate resin, paper, wood, and the like. When these substrates are coated with good adhesion, they can be subjected to various pretreatments such as primer treatment and plasma treatment as necessary.

  Also, there is no particular limitation on the coating method, and after adjusting to an appropriate concentration or viscosity with water or the organic solvent as necessary, for example, gravure coater, reverse coater, spin coater, brush coating, dipping coating, spray coating, etc. It can apply | coat on the above-mentioned various base materials by the method.

  Furthermore, the antireflection film formed by applying the antireflection film composition of the present invention on a target substrate can be used for various applications. For example, from temporary items required for processing, such as for photoresists, displays for TVs, personal computers, large outdoor bulletin boards, etc., display parts for various electronic and electrical devices such as mobile phones, electronic notebooks, calculators, audio, etc. Like this, when using each apparatus, it can be used for any use up to a semi-permanent one.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but it is needless to say that the present invention is not limited to these examples.

Example 1
2.58 parts by weight of perfluorooctylethylsulfonic acid, 0.74 parts by weight of poly (vinyl pyrrolidone) (BASF Takeda Vitamin Co., Ltd.) having a weight average molecular weight of 4,000 as an aqueous polymer, and pure water (distilled water) After adding 96.28 parts by weight and uniformly dissolving at room temperature (23 ° C.), 0.45 parts by weight of diethylethylenediamine was added and uniformly dissolved. This solution was filtered through a 0.1 μm filter to obtain a composition for an antireflection film.

  This antireflection film composition was applied onto a 4-inch silicon wafer using a spin coater (SC-308) manufactured by Oshikelle, and dried on a hot plate at 90 ° C. for 60 seconds to form a film on the silicon wafer. An antireflection film (film) having a thickness of about 0.5 μm was formed. The silicon wafer on which the film was formed was stored in a desiccator, and the appearance was observed and evaluated. The results are shown in Table 1 regarding the stability of the film over time. The appearance of the film was visually observed, and the film was transparent, the surface was homogeneous and smooth, and no peeling or cracking was indicated as ◯.

Examples 2 to 5 and Comparative Examples 1 to 3
The results shown in Table 1 and Table 2 were obtained in the same manner as in Example 1 except that the type and amount of amine used were as shown in Table 1.

Comparative Example 4
A film was formed on a silicon wafer in the same manner as in Example 1 with the composition shown in Table 3, and the appearance was evaluated.

Claims (4)

The following general formula (1)
_{C n F 2n + 1 (CH} 2 CH 2) m SO 3 H (1)
(In the formula, n represents an integer of 1 to 20, and m is an integer of 1 to 20.)
Containing at least one N-substituted ethylenediamine (B) and / or N-alkylmorpholine (C) selected from the group consisting of dimethylethylenediamine and diethylethylenediamine. A composition for an antireflection film, which is characterized. The composition for antireflection film according to claim 1, wherein n in the general formula (1) is 4 to 12, and m is 1. The N-alkylmorpholine (C) is represented by the following general formula ( 2 )
RN (C ₂ H ₄ ) ₂ O ( 2 )
(In the formula, R is an alkyl group having 1 to 4 carbon atoms.)
The composition for antireflection film according to claim 1, which is a compound represented by the formula: The perfluoroalkyl sulfonic acids and (A), said at N-substituted ethylene diamine (B) and / or the ratio of the N- alkyl morpholine component (C) weight ratio, when set to 1 (A), (B The sum of the component (C) and the component (C) is 0.01 to 0.3. The composition for an antireflection film according to any one of claims 1 to 3 .