JP2004341479A5 - - Google Patents

Description

Composition for forming antireflection film

The present invention, in the resist material used in the production of semiconductor devices by lithography, it relates to an antireflection film-forming composition for providing intermediate the base substrate and the resist film.

  In recent years, with the progress of miniaturization of semiconductor elements, further miniaturization of a lithography process used for its manufacture has been required. In general, in manufacturing a semiconductor, a resist pattern is formed on a base material such as a silicon wafer, a silicon oxide film, and an interlayer insulating film by using a lithography technique, and the base material is etched using the resist pattern as a mask. However, for miniaturization, it is necessary to control the resist pattern line width with high precision while resolving a fine pattern in the resist.

  To realize this, the reflection of radiation applied to the resist at the time of pattern formation, which occurs at the boundary between the resist film and the base material, has a significant meaning. That is, when radiation is reflected between the resist film and the base material, the radiation intensity in the resist changes, and as a result, the line width of the resist pattern fluctuates and an accurate pattern cannot be obtained.

  In order to suppress such obstacles, it has been performed to provide a coating such as an antireflection film or a protective film between the resist and the base material.However, the etching rate of a material constituting these coatings is Since it is similar to that of resist, it becomes an obstacle when transferring the resist pattern, and when removing these films, troubles such as loss of the resist pattern and deterioration of the shape occur, and processing of the base material It has the disadvantage of reducing accuracy.

  In addition, in order to ensure sufficient etching resistance, the thickness of the resist film is also increased. However, if the thickness is excessively increased, the aspect ratio between the line width of the resist pattern and the thickness of the resist film becomes large. Therefore, there is a disadvantage that a resist pattern, particularly an isolate pattern, collapses in the developing step, and the resolution of the resist decreases in the exposure step.

  In addition, there is also a three-layer resist process in which an intermediate layer is provided between the resist film and the film, that is, the lower organic layer, and a resist pattern with good reproducibility is formed on the intermediate layer in a good form. Properties such as high resistance to plasma etching, high plasma etching selectivity with the lower organic layer, and resistance to alkali developing solution are required. Therefore, some materials have been proposed to meet this requirement.

  For example, it has been proposed to provide an intermediate layer made of a hydrolyzate and / or condensate of an inorganic or organic silane compound (see Patent Document 1). Due to the use, when forming a film, a conventional spin coating method cannot be used, and a special coater track must be used.In addition, in order to remove by-products generated during the condensation reaction, Since it requires baking at a high temperature of 300 ° C. or higher, and it is not possible to stably introduce a chromophore for radiation, it has drawbacks such as difficulty in providing an antireflection ability.

  Further, an organic anti-reflection hard mask including an inorganic element selected from the periodic table IIIa, IVa, Va, VIa, VIIa, VIII, Ib, IIb, IIIb, IVb or Vb group on the dielectric layer has also been proposed. However, this method also has a drawback that it is not possible to stably introduce a chromophore to radiation, and thus it is not possible to adjust the necessary antireflection ability on a case-by-case basis.

JP-A-2002-40668 (Claims, etc.) JP 2001-53068 A (Claims, etc.)

The present invention is soluble in an organic solvent, can be easily applied by a conventional spin coating method, has good storage stability, and can adjust its antireflection ability by introducing a chromophore that absorbs radiation. An object of the present invention is to provide a composition for forming an antireflection film that can be used.

  The present inventors have conducted various studies on an intermediate layer capable of efficiently preventing reflection by being provided between a resist film and a base substrate, that is, a hard mask material of a so-called three-layer resist process. A composition containing a ladder-type silicone copolymer, an acid generator, and a crosslinking agent is soluble in an organic solvent, can be easily applied by a conventional spin coating method, and easily introduces a chromophore that absorbs radiation. Thus, the present inventors have found that a stable antireflection film having an appropriately adjusted antireflection ability can be formed, and the present invention has been accomplished based on this finding.

That is, the present invention, (A) (a ₁₎ (hydroxyphenyl alkyl) silsesquioxane units 10 to 90 mole%, (a ₂₎ (alkoxyphenyl alkyl) silsesquioxane units 0-50 mol% and ( a ₃₎ alkyl or phenyl silsesquioxane ladder silicone copolymer consisting San units 10 to 90 mol%, (B) dissolving an acid generator, and (C) a crosslinking agent generating an acid by heat or light in an organic solvent A composition for forming an antireflection film, wherein the composition can form an antireflection film having an optical parameter (k value) for an ArF laser in the range of 0.002 to 0.95. .

  The composition for forming an antireflection film of the present invention contains (A) a ladder-type silicone copolymer, (B) an acid generator that generates an acid by heat or light, and (C) a crosslinking agent as essential components. Things.

又は

（式中のｎは１〜３の整数である）
で表わされる構成単位１０〜９０モル％と、（ａ₂）（アルコキシフェニルアルキル）シルセスキオキサン単位、すなわち一般式

又は

（式中のＲは炭素数１〜４の直鎖状又は枝分れ状低級アルキル基、ｎは１〜３の整数である）
で表わされる構成単位０〜５０モル％と、（ａ₃）アルキル又はフェニルシルセスキオキサン単位、すなわち式

又は

（式中のＲ⁵は炭素数１〜２０の直鎖状又は炭素数２〜２０の枝分かれ状又は炭素数５〜２０の脂環状又は単環又は多環式アルキル基又はフェニル基である）
で表わされる構成単位１０〜９０モル％からなるラダー型シリコーン共重合体を用いることが必要である。上記一般式（ＩＩ）又は（ＩＩ´）中のＲとしては、メチル基が最も好ましい。この一般式（ＩＩＩ）又は（ＩＩＩ´）中のＲ⁵としては、炭素数１〜５の低級アルキル基、炭素数５〜６のシクロアルキル基又はフェニル基が光学パラメーター（ｋ値）を調整しやすいので好ましい。また、上記一般式（Ｉ）と（ＩＩ）における−ＯＨ基と−ＯＲ基は、ｏ位、ｍ位及びｐ位のいずれの位置に結合していてもよいが、工業的にはｐ位に結合しているのが好ましい。また、（ａ₁）、（ａ₂）及び（ａ₃）単位は、通常上記一般式（Ｉ）、（ＩＩ）及び（ＩＩＩ）で表わされたり、（Ｉ´）、（ＩＩ´）、（ＩＩＩ´）と表わされたりするが、同じものである。
このラダー型シリコーン共重合体は、質量平均分子量（ポリスチレン換算）が１５００〜３００００の範囲にあるものが好ましく、３０００〜２００００の範囲にあるものが最も好ましい。分子量の分散度は１．０〜５．０の範囲であることが好ましく、１．２〜３．０であることが最も好ましい。 As the ladder type silicone copolymer of the component (A), (a ₁ ) (hydroxyphenylalkyl) silsesquioxane unit,

Or

(Where n is an integer of 1 to 3)
And (a ₂ ) (alkoxyphenylalkyl) silsesquioxane unit represented by the following general formula:

Or

(In the formula, R is a linear or branched lower alkyl group having 1 to 4 carbon atoms, and n is an integer of 1 to 3)
In the structural unit 0-50 mol% represented, (a ₃₎ alkyl or phenyl silsesquioxane units, i.e. formula

Or

(In the formula, R ⁵ is a straight chain having 1 to 20 carbon atoms, a branched chain having 2 to 20 carbon atoms, or an alicyclic or monocyclic or polycyclic alkyl group having 5 to 20 carbon atoms or a phenyl group.)
It is necessary to use a ladder type silicone copolymer composed of 10 to 90 mol% of the structural unit represented by the following formula: R in the general formula (II) or (II ′) is most preferably a methyl group. As R ⁵ in the general formula (III) or (III ′), a lower alkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 5 to 6 carbon atoms or a phenyl group adjusts an optical parameter (k value). It is preferable because it is easy. Further, the —OH group and the —OR group in the above general formulas (I) and (II) may be bonded to any of the o-position, m-position and p-position. Preferably they are linked. The (a ₁ ), (a ₂ ) and (a ₃ ) units are usually represented by the above general formulas (I), (II) and (III), or (I ′), (II ′), (III ') is the same .
The ladder type silicone copolymer preferably has a mass average molecular weight (in terms of polystyrene) of from 1500 to 30,000, and most preferably from 3,000 to 20,000. The molecular weight dispersity is preferably in the range of 1.0 to 5.0, and most preferably 1.2 to 3.0.

  Next, the acid generator which generates an acid by the heat or light of the component (B) is a substance which is usually used as a component of a chemically amplified resist composition, and in the present invention, any of these may be used. Although it can be used selectively, onium salts and diazomethane compounds are particularly preferable.

  Examples of such an acid generator include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, and triphenylsulfonium trifluoromethanesulfonate or nonafluorobutanesulfonate. Onium salts such as trifluorobutanesulfonate, trifluoromethanesulfonate of tri (4-methylphenyl) sulfonium or nonafluorobutanesulfonate, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, bis ( Isopropylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenyl) Nirusuruhoniru) can be exemplified diazomethane-based compounds such as diazomethane. Of these, particularly preferred are onium salts having a decomposition point of 250 ° C. or less, such as triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluorobutanesulfonate, and 7,7-dimethyl-bis (pt-butylphenyl) iodonium. And bicyclo- [2,2,1] -heptane-2-one-1-sulfonate.

  The acid generator (B) may be used alone or in combination of two or more. The content is selected in the range of usually 0.5 to 20 parts by mass, preferably 1 to 10 parts by mass, based on 100 parts by mass of the component (A). When the amount of the acid generator is less than 0.5 part by mass, it is difficult to form an antireflection film, and when the amount exceeds 20 parts by mass, a uniform solution is not obtained, and storage stability is reduced.

で表わされる２，４，６，８‐テトラ‐ｎ‐ブトキシメチル‐ビシクロ［１．０．１］‐２，４，６，８‐テトラアザオクタン‐３，７‐ジオンや、式

で表わされるヘキサメトキシメチルメラミンが好ましい。
これらの架橋剤は、（Ａ）１００質量部当り１〜１０質量部の範囲内で用いるのがよい。 The crosslinking agent of the component (C) is not particularly limited as long as it can form a coating suitable as a hard mask material by crosslinking the component (A) when the composition of the present invention is heated or fired. No, but compounds having two or more reactive groups, such as divinylbenzene, divinylsulfone, triacrylformal, glyoxal, acrylic acid esters or methacrylic acid esters of polyhydric alcohols, melamine, urea, benzoguanamine, amino acids of glycoluril It is preferred that at least two of the groups are substituted with a methylol group or a lower alkoxymethyl group. Among them, especially the formula

2,4,6,8-tetra-n-butoxymethyl-bicyclo [1.0.1] -2,4,6,8-tetraazaoctane-3,7-dione represented by the formula:

Hexamethoxymethylmelamine represented by
These crosslinking agents are preferably used in the range of 1 to 10 parts by mass per 100 parts by mass of (A).

The composition for forming an antireflection film of the present invention is a solution obtained by dissolving the above components (A), (B) and (C) in an organic solvent. The necessary amounts of these three components can be arbitrarily selected from those which can be dissolved, but those having a boiling point of 150 ° C. or higher are preferable in consideration of the calcination conditions. Examples of the solvent include ketones such as acetone, methyl ethyl ketone, cyclohexanone, and methyl isoamyl ketone, ethylene glycol, ethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, diethylene glycol or diethylene glycol monoacetate monomethyl ether, monoethyl ether, Monopropyl ether, polyhydric alcohols such as monobutyl ether or monophenyl ether and derivatives thereof, and cyclic ethers such as dioxane, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, Esters such as ethyl pyruvate are used. These may be used alone or as a mixture of two or more.
The organic solvent is used in an amount of 1 to 20 times, preferably 2 to 10 times the amount based on the total mass of the solid content.

The composition for forming an antireflection film of the present invention has an optical parameter (k value) of 0.002 to 0.95, preferably 0.1 to 0.7, more preferably 0.1 to 0.7 for an ArF laser, that is, light having a wavelength of 193 nm. It must be adjusted so that an anti-reflective coating in the range of 15-0.4 is formed. This adjustment can be performed, for example, by increasing or decreasing the content ratio of the component (a ₂ ) in the component (A). By adjusting to such a range, a low and stable reflectance is exhibited when the thickness of the antireflection film is set to 40 to 200 nm.

  Next, the composition for forming an antireflection film of the present invention further contains a linear polymer as a component (D), if necessary, in addition to the components (A), (B) and (C). be able to.

  In the composition of the present invention, the linear polymer used as the component (D) is a polymer containing at least a hydroxyl group-containing (meth) acrylate unit as a constitutional unit, that is, a homopolymer of a hydroxyl group-containing (meth) acrylate ester or a hydroxyl group. It is preferably a copolymer of the contained (meth) acrylic acid ester and another copolymerizable monomer.

  By using a polymer containing a hydroxyl group as the component (D), the hydroxyl group promotes a high molecular weight as a crosslinking aid, and the effect of significantly improving the stability to a resist solvent and a developing solution is exhibited. This effect is particularly enhanced when a hydroxyl group-containing (meth) acrylate having an aliphatic polycyclic group such as an adamantyl group as a side chain is used.

  When the linear polymer is a copolymer of a hydroxyl group-containing (meth) acrylate, the monomer component to be copolymerized with the hydroxyl group-containing (meth) acrylate is not particularly limited, and a known monomer conventionally used in ArF resists is used. Can be arbitrarily selected and used.

（式中、Ｒ¹は水素原子又はメチル基、Ｒ²は低級アルキル基である）
で表わされる構成単位１０〜６０モル％、好ましくは２０〜４０モル％、（ｄ₂）一般式

（式中のＲ³は水素原子又はメチル基である）
で表わされる構成単位３０〜８０モル％、好ましくは２０〜５０モル％、及び（ｄ₃）一般式

（式中、Ｒ⁴は水素原子又はメチル基である）
で表わされる構成単位１０〜５０モル％、好ましくは２０〜４０モル％からなる線状共重合体を挙げることができる。
上記一般式（Ｖ）中のＲ²としては、炭素数１〜５の低級アルキル基、特にメチル基やエチル基が工業的な面から好ましい。 Among the above-mentioned linear polymers containing a hydroxyl group-containing (meth) acrylic acid ester unit, particularly preferred are those represented by the general formula (d ₁ )

(Wherein, R ¹ is a hydrogen atom or a methyl group, and R ² is a lower alkyl group)
10 to 60 mol%, preferably 20 to 40 mol%, of a structural unit represented by the formula: (d ₂ )

(Wherein R ³ is a hydrogen atom or a methyl group)
30 to 80 mol%, preferably 20 to 50 mol%, represented by the following formula: and (d ₃ )

(Wherein R ⁴ is a hydrogen atom or a methyl group)
And a linear copolymer consisting of 10 to 50 mol%, preferably 20 to 40 mol%, represented by the following formula:
As R ² in the general formula (V), a lower alkyl group having 1 to 5 carbon atoms, particularly a methyl group or an ethyl group is preferable from an industrial viewpoint.

The linear polymer of the component (D) preferably has a weight average molecular weight of 5,000 to 20,000.
The component (D) is blended at a ratio of 10 to 100 parts by mass per 100 parts by mass of the component (A).

  Next, in addition to the components (A), (B) and (C), and optionally the component (D), the composition for forming an antireflection film of the present invention further has a dispersibility. Conventional ionic or non-ionic surfactants can be added to impart coating uniformity.

  These surfactants are added at a ratio of 0.05 to 1.0 part by mass per 100 parts by mass of the total solid content.

  The composition for forming an antireflection film of the present invention can be easily applied to a substrate such as a silicon wafer by using a conventional spin coating method, and can form an antireflection film having a desired thickness. . Considering that it has been necessary to form an oxide film on a base material by vapor deposition and apply a resist film on the oxide film in the conventional resist process, it can be seen that the process is extremely simplified.

  In order to form this antireflection film, it is spin-coated on a substrate, dried and heated at a temperature lower than the boiling point of the solvent, for example, at 100 to 120 ° C for 60 to 120 seconds, and then at 200 to 250 ° C for 60 to 120 seconds. It is preferable to use a multi-stage heating method. After forming an antireflection film having a thickness of 40 to 200 nm in this manner, a resist material is provided thereon with a thickness of 100 to 300 nm by a conventional method to produce a resist material. In this case, a three-layer resist material may be formed by first providing an organic film with a thickness of 200 to 600 nm on the base material, and forming the antireflection film as an intermediate layer between the organic film and the resist film. it can.

The ladder-type silicone copolymer of the component (A) used in the composition for forming an antireflection film is a base resin component of the composition for forming an antireflection film, particularly an ArF laser of the composition, that is, a 193 nm wavelength. This is important as a component when the optical parameter (k value) for light is adjusted to 0.002 to 0.95, and such adjustment can be performed effectively. Further, the copolymer has a high silicon content and a high O ₂ plasma resistance, which is preferable.
The ladder-type silicone copolymer can be synthesized by a method known per se, for example, the method described in Production Example 1 of Japanese Patent No. 2567984.

  Further, among the ladder-type silicone copolymers of the component (A), a copolymer containing a combination of a (hydroxyphenylalkyl) silsesquioxane unit and an alkylsilsesquioxane unit is a novel compound not described in any literature. . For use in the composition for forming an antireflection film of the present invention, the content ratio of (hydroxyphenylalkyl) silsesquioxane units to alkylsilsesquioxane units is in the range of 10:90 to 90:10 by molar ratio. Those having a mass average molecular weight of 1500 to 30,000, particularly 3000 to 20,000, and a dispersity of 1.0 to 5.0, particularly 1.2 to 3.0 are preferred.

According to the present invention, it can be easily applied by a spin coating method using a conventional resist coater, storage stability, oxygen plasma etching resistance is good, and a mask pattern having an excellent profile shape can be provided. Since the solution is prepared in a well-dispersed solution in an organic solvent, it is easy to introduce a chromophore that absorbs radiation, and a composition for forming an antireflection film capable of adjusting the antireflection ability is provided.

Next, best modes for carrying out the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In each example, the following compounds were used as the acid generator (B) component, the crosslinking agent (C) component, and the linear polymer (D) component.

（２）架橋剤；
（Ｃ₁）成分

又は
（Ｃ₂）成分

（３）線状ポリマー；
（Ｄ）成分
２‐エチル‐２‐アダマンチルアクリレート単位、一般式（ＶＩ）におけるＲ³が水素原子である単位及び３‐ヒドロキシ‐１‐アダマンチルアクリレート単位をそれぞれ３０モル％、４０モル％及び３０モル％含むアクリレートタイプポリマー
質量平均分子量１００００ (1) an acid generator;
(B) component

(2) a crosslinking agent;
(C ₁ ) component

Or (C ₂ ) component

(3) linear polymers;
(D) Component 2-ethyl-2-adamantyl acrylate unit, 30 mol%, 40 mol% and 30 mol of a unit in which R ³ in the general formula (VI) is a hydrogen atom and a 3-hydroxy-1-adamantyl acrylate unit, respectively. % Acrylate type polymer Mass average molecular weight 10,000

The optical parameter (k value: extinction coefficient) in each example is a value measured by the following method.
That is, the sample was applied on an 8-inch silicon wafer to form a coating film having a thickness of 50 nm, which was measured by spectroscopic ellipsometry (“VUV-VASE”, manufactured by JA WOOLLAM Co., Ltd.). Analysis was performed using analysis software (WVASE32).

Reference Example 1
Into a 500 ml three-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, 1.00 mol (84.0 g) of sodium hydrogencarbonate and 400 ml of water were charged, and then p-methoxybenzyltriethyl was added from the dropping funnel. A solution obtained by dissolving 0.36 mol (92.0 g) of chlorosilane and 0.14 mol (29.6 g) of phenyltrichlorosilane in 100 ml of diethyl ether was added dropwise with stirring over 2 hours, and the mixture was heated under reflux for 1 hour. After completion of the reaction, the reaction product was extracted from the reaction mixture with diethyl ether, and diethyl ether was distilled off from the extract under reduced pressure to collect a hydrolysis product.
0.33 g of a 10% by mass aqueous solution of potassium hydroxide was added to the hydrolysis product thus obtained, and the mixture was heated at 200 ° C. for 2 hours, whereby 72 mol% of p-methoxybenzylsilsesquioxane unit and phenylsilyl were added. A copolymer A ₁ (64.4 g) consisting of 28 mol% of sesquioxane units was produced. Proton NMR of the copolymer A _1, infrared absorption spectrum, the analysis of GPC (gel permeation chromatography) are shown below.
¹ H-NMR (DMSO-d ₆ ): δ = 2.70 ppm (—CH ₂ —), 3.50 ppm (—OCH ₃ ), 6.00 to 7.50 ppm (benzene ring)
IR (cm ^-1 ): ν = 1178 (-OCH ₃ ), 1244, 1039 (-SiO-)
Mass average molecular weight (Mw): 7500, degree of dispersion (Mw / Mn): 1.8

Then, the copolymer A ₁ to a solution obtained by dissolving in acetonitrile 150 ml, was added trimethylsilyl iodide 0.4 mol (80.0 g), After stirring 24 hours under reflux, water 50ml was added, further The mixture was stirred and reacted under reflux for 12 hours. After cooling, free iodine was reduced with an aqueous solution of sodium hydrogen sulfite, then the organic layer was separated and the solvent was distilled off. The residue was reprecipitated with acetone and n-hexane, and dried by heating under reduced pressure to obtain a copolymer A ₂ (p-hydroxybenzylsilsesquioxane unit: 72 mol% and phenyl silsesquioxane unit: 28 mol%) 39.0 g). Proton NMR of the copolymer A _2, infrared absorption spectrum, the analysis of GPC (gel permeation chromatography) are shown below.
¹ H-NMR (DMSO-d ₆ ): δ = 2.70 ppm (—CH ₂ —), 6.00 to 7.50 ppm (benzene ring), 8.90 ppm (—OH)
IR (cm ^-1 ): ν = 3300 (-OH), 1244, 1047 (-SiO-)
Weight average molecular weight (Mw): 7000, degree of dispersion (Mw / Mn): 1.8

Reference Example 2
To a solution of the copolymer A ₁ prepared in Reference Example 1 was obtained by dissolving in acetonitrile 150 ml, was added trimethylsilyl iodide 0.250 mol (50.0 g), After stirring 24 hours under reflux, water 50ml was added The reaction was further stirred for 12 hours under reflux. After cooling, free iodine was reduced with an aqueous solution of sodium hydrogen sulfite, then the organic layer was separated and the solvent was distilled off. The residue was reprecipitated with acetone and n-hexane, and dried by heating under reduced pressure to obtain 36 mol% of p-hydroxybenzylsilsesquioxane unit, 36 mol% of p-methoxybenzylsilsesquioxane unit and phenylsilsesquioxane. A copolymer A ₃ (40.3 g) consisting of 28 mol% of sun units was produced. Proton NMR of the copolymer A _3, infrared absorption spectrum, the analysis of GPC (gel permeation chromatography) are shown below.
¹ H-NMR (DMSO-d ₆ ): δ = 2.70 ppm (—CH ₂ —), 3.50 ppm (—OCH ₃ ), 6.00 to 7.50 ppm (benzene ring), 8.90 ppm (—OH )
^{IR (cm -1): ν =} 3300 (-OH), 1178 (-OCH 3), 1244,1047 (-SiO-)
Weight average molecular weight (Mw): 7000, degree of dispersion (Mw / Mn): 1.8

Reference Example 3
To a solution of the copolymer A ₁ prepared in Reference Example 1 was obtained by dissolving in acetonitrile 150 ml, was added trimethylsilyl iodide 0.347 mol (69.4 g), After stirring 24 hours under reflux, water 50ml was added The reaction was further stirred for 12 hours under reflux. After cooling, free iodine was reduced with an aqueous solution of sodium hydrogen sulfite, then the organic layer was separated and the solvent was distilled off. The residue was reprecipitated with acetone and n-hexane, and dried by heating under reduced pressure to give 50 mol% of p-hydroxybenzylsilsesquioxane unit, 22 mol% of p-methoxybenzylsilsesquioxane unit and phenylsilsesquioxane. A copolymer A ₄ (39.8 g) consisting of 28 mol% of sun units was produced. Proton NMR of the copolymer A _4, infrared absorption spectrum, the analysis of GPC (gel permeation chromatography) are shown below.
¹ H-NMR (DMSO-d ₆ ): δ = 2.70 ppm (—CH ₂ —), 3.50 ppm (—OCH ₃ ), 6.00 to 7.50 ppm (benzene ring), 8.90 ppm (—OH )
^{IR (cm -1): ν =} 3300 (-OH), 1178 (-OCH 3), 1244,1047 (-SiO-)
Weight average molecular weight (Mw): 7000, degree of dispersion (Mw / Mn): 1.8

Reference example 4
Into a 500 ml three-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, 1.00 mol (84.0 g) of sodium hydrogencarbonate and 400 ml of water were charged, and then p-methoxybenzyltriethyl was added from the dropping funnel. A solution obtained by dissolving 0.36 mol (92.0 g) of chlorosilane and 0.14 mol (24.9 g) of n-propyltrichlorosilane in 100 ml of diethyl ether was added dropwise with stirring over 2 hours, and then heated to reflux for 1 hour. did. After completion of the reaction, the reaction product was extracted with diethyl ether, and diethyl ether was distilled off from the extract under reduced pressure.
0.33 g of a 10 mass% aqueous potassium hydroxide solution was added to the hydrolysis product thus obtained, and the mixture was heated at 200 ° C. for 2 hours, whereby 72 mol% of p-methoxybenzylsilsesquioxane unit and n- a copolymer consisting of propyl silsesquioxane units 28 mol% was prepared a ₅ (60.6g). Proton NMR of the copolymer A _5, the infrared absorption spectrum, the analysis of GPC (gel permeation chromatography) are shown below.
¹ H-NMR (DMSO-d ₆ ): δ = 1.00 to 2.00 ppm (-n-Propyl), 2.70 ppm (-CH _2- ), 3.50 ppm (-OCH ₃ ), 6.00 7.50 ppm (benzene ring)
IR (cm ^-1 ): ν = 1178 (-OCH ₃ ), 1244, 1039 (-SiO-)
Mass average molecular weight (Mw): 7500, degree of dispersion (Mw / Mn): 1.8

Then, the copolymer A ₅ solution obtained by dissolving in acetonitrile 150 ml, was added trimethylsilyl iodide 0.4 mol (80.0 g), After stirring 24 hours under reflux, water 50ml was added, further The mixture was stirred and reacted under reflux for 12 hours. After cooling, free iodine was reduced with an aqueous solution of sodium hydrogen sulfite, then the organic layer was separated and the solvent was distilled off. The residue was reprecipitated with acetone and n-hexane, and dried by heating under reduced pressure to give a copolymer A comprising 72 mol% of p-hydroxybenzylsilsesquioxane units and 28 mol% of n-propylsilsesquioxane units. ₆ (36.6 g) was produced. The analysis results of the proton A, infrared absorption spectrum and GPC (gel permeation chromatography) of the copolymer A ₆ are shown below.
¹ H-NMR (DMSO-d ₆ ): δ = 1.00 to 2.00 ppm (-n-Propyl), 2.70 ppm (-CH _2- ), 6.00 to 7.50 ppm (benzene ring), 8 .90 ppm (-OH)
IR (cm ^-1 ): ν = 3300 (-OH), 1244, 1047 (-SiO-)
Weight average molecular weight (Mw): 7000, degree of dispersion (Mw / Mn): 1.8

Reference example 5
Into a 500 ml three-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, 1.00 mol (84.0 g) of sodium hydrogencarbonate and 400 ml of water were charged, and then p-methoxybenzyltriethyl was added from the dropping funnel. A solution obtained by dissolving 0.32 mol (81.8 g) of chlorosilane and 0.18 mol (38.1 g) of phenyltrichlorosilane in 100 ml of diethyl ether was added dropwise with stirring over 2 hours, and the mixture was heated under reflux for 1 hour. After completion of the reaction, the reaction product was extracted with diethyl ether, and diethyl ether was distilled off from the extract under reduced pressure.
0.33 g of a 10% by mass-aqueous potassium hydroxide solution was added to the hydrolysis product thus obtained, and heated at 200 ° C. for 2 hours, whereby 64 mol% of p-methoxybenzylsilsesquioxane unit and phenylsilyl A copolymer A ₇ (62.9 g) consisting of 36 mol% of sesquioxane units was produced. Proton NMR of the copolymer A _7, infrared absorption spectrum, the analysis of GPC (gel permeation chromatography) are shown below.
¹ H-NMR (DMSO-d ₆ ): δ = 2.70 ppm (—CH ₂ —), 3.50 ppm (—OCH ₃ ), 6.00 to 7.50 ppm (benzene ring)
IR (cm ^-1 ): ν = 1178 (-OCH ₃ ), 1244, 1039 (-SiO-)
Mass average molecular weight (Mw): 7500, degree of dispersion (Mw / Mn): 1.8

Then, the copolymer A ₇ in a solution obtained by dissolving in acetonitrile 150 ml, was added trimethylsilyl iodide 0.4 mol (80.0 g), After stirring 24 hours under reflux, water 50ml was added, further The mixture was stirred and reacted under reflux for 12 hours. After cooling, free iodine was reduced with an aqueous solution of sodium hydrogen sulfite, then the organic layer was separated and the solvent was distilled off. The residue was reprecipitated with acetone and n-hexane, and dried by heating under reduced pressure to obtain a copolymer A ₈ (64 mol% of p-hydroxybenzylsilsesquioxane units and 36 mol% of phenylsilsesquioxane units) ( 38.4 g). Proton NMR of the copolymer A _8, the infrared absorption spectrum, the analysis of GPC (gel permeation chromatography) are shown below.
¹ H-NMR (DMSO-d ₆ ): δ = 2.70 ppm (—CH ₂ —), 6.00 to 7.50 ppm (benzene ring), 8.90 ppm (—OH)
IR (cm ^-1 ): ν = 3300 (-OH), 1244, 1047 (-SiO-)
Weight average molecular weight (Mw): 7000, degree of dispersion (Mw / Mn): 1.8

The ladder type silicone copolymer, that is, the copolymer A ₂ of Reference Example 1 comprising 72 mol% of p-hydroxybenzylsilsesquioxane units and 28 mol% of phenyl silsesquioxane units (weight average molecular weight) as the component (A) 7000), 83 parts by weight of the component (A), 3 parts by weight of the component (B) as the acid generator, and 5 parts by weight of the component (C ₁ ) as a crosslinking agent, and the acrylate as the component (D). The mixture obtained by adding 17 parts by mass of the type polymer was dissolved in 300 parts by mass of propylene glycol monopropyl ether to prepare a composition for forming an antireflection film.
Next, the above-mentioned composition is applied on a silicon wafer using a conventional resist coater, and a two-stage heat treatment is performed at 100 ° C. for 90 seconds, and then at 250 ° C. for 90 seconds to obtain a thick film. An antireflection film having a thickness of 55 nm was formed.
The optical parameter (k value) of this antireflection film was 0.67.
In this manner, coating films having different thicknesses were formed, and the reflectance with respect to the thickness was measured. The results are shown in FIG. 1 as a graph.
As can be seen from the figure, when the k value is 0.67, a stable low reflectance is exhibited in the used film thickness range of 40 to 150 nm.

(A) The copolymer of Reference Example 2 comprising 36 mol% of p-hydroxybenzylsilsesquioxane units, 36 mol% of p-methoxybenzylsilsesquioxane units and 28 mol% of phenylsilsesquioxane units as the component. A ₃ (mass average molecular weight 7000) was used, and 100 parts by mass of the component (A), 3 parts by mass of the component (B) as an acid generator, and 5 parts by mass of the component (C ₁ ) as a crosslinking agent were mixed with propylene glycol. The composition for forming an antireflection film was prepared by dissolving in 300 parts by mass of a mixture of monomethyl ether monoacetate and propylene glycol monomethyl ether (mass ratio 40/60).
Next, the above composition is applied on a silicon wafer using a conventional resist coater, and is subjected to a heat treatment in two stages under the conditions of 100 ° C. for 90 seconds, and then 250 ° C. for 90 seconds. An antireflection film having a thickness of about 50 nm was formed.
The optical parameter (k value) of this antireflection film was 0.67.

(A) The copolymer of Reference Example 3 comprising 50 mol% of p-hydroxybenzylsilsesquioxane units, 22 mol% of p-methoxybenzylsilsesquioxane units and 28 mol% of phenylsilsesquioxane units as the component. a ₄ using (weight average molecular weight 7000), and the said component (a) 100 parts by weight of an acid generator component (B) 3 parts by weight and the as a crosslinking agent (C ₁₎ component, 5 parts by mass propylene glycol The composition for forming an antireflection film was prepared by dissolving in 300 parts by mass of monomethyl ether monoacetate.
This composition was applied on a silicon wafer in the same manner as in Example 1 , heated at 100 ° C. for 90 seconds, and then heated at 230 ° C. for 90 seconds to form an antireflection film having a thickness of 70 nm. The optical parameter (k value) of this antireflection film was 0.90.

An anti-reflection film having a thickness of 70 nm was formed in exactly the same manner as in Example 3 , except that the heat treatment was changed to a single-stage heat treatment at 250 ° C. for 90 seconds.
The optical parameter (k value) of this antireflection film was 0.90.

As the component (A), 83 parts by mass of the copolymer A ₆ obtained in Reference Example 4 , 3 parts by mass of the component (B) as an acid generator, and 5 parts by mass of the component (C ₁ ) as a crosslinking agent were added. Further, a mixture obtained by adding 17 parts by mass of the component (D) as a linear polymer was dissolved in 300 parts by mass of propylene glycol monopropyl ether to prepare a composition for forming an antireflection film. Next, the above composition is applied on a silicon wafer using a conventional resist coater, and is subjected to a heat treatment in two stages under the conditions of 100 ° C. for 90 seconds, and then 250 ° C. for 90 seconds. An antireflection film having a thickness of 55 nm was formed.
The optical parameter (k value) of this antireflection film was 0.55.

As the component (A), a copolymer A ₈ (mass average molecular weight 7000) of Reference Example 5 consisting of 64 mol% of p-hydroxybenzylsilsesquioxane units and 36 mol% of phenylsilsesquioxane units was used. A) 83 parts by weight of the component, 3 parts by weight of the component (B) as an acid generator, and 5 parts by weight of the component (C ₂ ) as a crosslinking agent, and 17 parts by weight of the component (D) as a linear polymer The obtained mixture was dissolved in 300 parts by mass of propylene glycol monopropyl ether to prepare a composition for forming an antireflection film. Next, the above composition is applied on a silicon wafer using a conventional resist coater, and is subjected to a heat treatment in two stages under the conditions of 100 ° C. for 90 seconds, and then 250 ° C. for 90 seconds. An antireflection film having a thickness of 75 nm was formed.
The optical parameter (k value) of this antireflection film was 0.49.

Comparative Example As a composition for forming an anti-reflection film, a coating solution mainly composed of a mixture of a co-hydrolyzate and a condensate of a commercially available tetraalkoxysilane and methyltrialkoxysilane (trade name “OCD T- manufactured by Tokyo Ohka Kogyo Co., Ltd.) 7 ML02 ”), coated on a silicon wafer with a SOG coater, heated at 80 ° C for 90 seconds, then at 150 ° C for 90 seconds, and finally heated at 250 ° C for 90 seconds in three stages. As a result, an antireflection film having a thickness of 50 nm was formed.
The above-mentioned coating liquid immediately produces a powdery precipitate as the solution dries, which becomes a contamination of a coating nozzle, a coater cup, a wafer, and the like, and thus cannot be applied by a conventional resist coater.

Application Examples The compositions for forming an anti-reflection film in the above Examples and Comparative Examples were tested for storage stability, applicability by a resist coater, and oxygen plasma etching resistance by the following method, and the results are shown in Table 1. Was.

(1) Storage stability (change in film thickness);
A composition prepared by storing the given composition at room temperature (20 ° C.) or under freezing (−20 ° C.) for 45 days is prepared, spin-coated on an 8-inch silicon wafer under the same coating conditions, dried, and dried. The thickness of each of the formed films was measured, and the case where the difference between the film thickness of the sample stored at room temperature and the sample stored at room temperature with respect to the frozen sample was within 5% was evaluated as ○, and the case where it was larger than that was evaluated as ×.

(2) storage stability (generation of particles);
Further, the number of particles having a particle size of 0.22 μm or more was measured with a particle counter [Rion, product name “Particle Sensor KS-41”] for the sample stored at room temperature of (1), and 300 particles were measured. The following cases were evaluated as ○, and the cases exceeding them were evaluated as ×.

(3) Possibility of applying a resist coater;
In order to be able to apply by a resist coater, it is necessary that no particles are generated in the edge rinsing step and the auto-dispensing step. Therefore, it was dissolved in propylene glycol methyl ether acetate, propylene glycol monomethyl ether and ethyl lactate used as an edge rinse solution, and the presence or absence of particles was observed. did.

(4) oxygen plasma etching resistance (etching rate);
The sample was etched under the following conditions, and the etching rate was determined. The smaller the value, the better the oxygen plasma etching resistance.
Etching equipment: GP-12 (Tokyo Ohka Kogyo Co., Ltd., oxygen plasma etching equipment)
Etching gas; O ₂ / N ₂ (60/40 sccm)
Pressure; 0.4 Pa
Output: 1600W
Bias power; 150W
Stage temperature; -10 ° C

  The composition for forming an antireflection film of the present invention has good storage stability, and furthermore, by introducing a chromophore that absorbs radiation, its antireflection ability can be adjusted. Since it can be easily applied by a spin coating method, it is suitable for manufacturing semiconductor devices.

9 is a graph showing the relationship between the film thickness and the reflectance of the composition of the present invention having an optical parameter (k value) of 0.67.

Claims (5)

(A) (a ₁₎ (hydroxyphenyl alkyl) silsesquioxane units 10 to 90 mole%, (a ₂₎ (alkoxyphenyl alkyl) silsesquioxane units 0-50 mol% and (a ₃₎ alkyl or phenyl A ladder type silicone copolymer comprising 10 to 90 mol% of silsesquioxane units, (B) an acid generator which generates an acid by heat or light, and (C) a crosslinking agent dissolved in an organic solvent, and ArF A composition for forming an antireflection film, wherein the composition can form an antireflection film having an optical parameter (k value) for laser in the range of 0.002 to 0.95.   The composition for forming an antireflection film according to claim 1, further comprising (D) a linear polymer in addition to the component (A), the component (B), and the component (C).   The composition for forming an antireflection film according to claim 2, wherein the (D) linear polymer is a polymer containing at least a hydroxyl group-containing (meth) acrylate unit.   The composition for forming an antireflection film according to claim 3, wherein the (D) linear polymer is a polymer containing a (meth) acrylate unit having at least a hydroxyl group-containing aliphatic polycyclic group. The linear polymer (D) is represented by the general formula (d ₁ )

(Wherein, R ¹ is a hydrogen atom or a methyl group, and R ² is a lower alkyl group)
10 to 60 mol% of a structural unit represented by the formula: (d ₂ )

(Wherein R ³ is a hydrogen atom or a methyl group)
30 to 80 mol% of a structural unit represented by the formula: and (d ₃ )

(Wherein R ⁴ is a hydrogen atom or a methyl group)
The composition for forming an antireflection film according to claim 3, which is a linear copolymer comprising 10 to 50 mol% of a structural unit represented by the following formula: