JPH09236915A - Antireflection composition and method for forming resist pattern - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a water-solvent antireflection composition that gives an antireflection film excellent in various properties. An antireflection composition having a polyvinyl alcohol resin as a film forming component, water as a solvent, and a pH of 4 or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for forming an antireflection film in photolithography, which is preferably used for fine processing such as production of semiconductor elements.

[0002]

2. Description of the Related Art In recent years, fine processing technology represented by the manufacture of integrated circuits has been increasingly improved in processing accuracy. For example, in the case of dynamic random access memory (DRAM), sub-micron processing technology is now available. Has been established as a mass production level technology. For this submicron processing, g line (436 nm), i line (365 nm) K
A photolithography technique using short-wavelength light such as rF excimer laser light (248 nm) is used.
In these photolithography techniques, a photoresist composition is used, and the photoresist composition has been repeatedly improved and various high performance compositions have been proposed (for example, JP-A-59-45439). JP-A-62-1
36637, Japanese Patent Laid-Open No. 62-153950,
JP-A-4-136860, JP-A-4-13694
No. 1).

The characteristics required of the photoresist composition are, of course, high resolution, but it is important that the dimensions of the transferred pattern do not vary depending on the coating thickness of the photoresist composition. Is. However, in photolithography, there is a limit to suppressing the dimensional variation of the pattern with respect to the variation of the resist film thickness because it is affected by the light interference.

That is, since the light to be irradiated is usually monochromatic light, the light incident on the photoresist film is reflected on the substrate and further reflected on the upper surface of the photoresist film. Cause reflection. As a result, due to the interference effect, the intensity of light is generated according to the change in the coating film thickness, and the sensitivity changes periodically. As a result, the finished dimension of the line width of the transferred pattern periodically changes in accordance with the variation of the coating film thickness, and the dimensional accuracy of the pattern is limited. In addition, the in-film multiple reflection also causes the intensity of light in the vertical direction in the resist film to generate irregularities on the side wall of the pattern called standing waves.

Further, when the radiated light is reflected on the substrate, the light is also radiated to the portion of the resist which is not originally irradiated with the light, and as a result, the transfer pattern is deformed. There was also. In general, the reflectance increases as the wavelength of light becomes shorter, and thus the problem of the reflection of light from the substrate as described above becomes a greater problem due to the shortening of the wavelength of irradiation light in recent years.

It is known to form an antireflection film between a photoresist film and a substrate in order to reduce reflection of light from the substrate (eg, monthly Semicondu).
center World, June 1994, p. 83-). Such an antireflection film is usually formed by coating and baking an antireflection composition having sufficient absorption for an exposure wavelength on a substrate, and a photoresist film is formed thereon. This antireflection film is removed from the substrate by a method such that it is dissolved at the same time as the resist film during development after exposure, or after the resist pattern is formed by development and the antireflection film is selectively etched by dry etching using oxygen plasma or the like. To be done.

The performance required for the antireflection film is as follows. When the photoresist composition is applied, if the antireflection film is dissolved in the components and both components are mixed, the resolution is lowered and the pattern shape is deteriorated. Therefore, the photoresist composition applied on the antireflection film. Do not cause mutual mixing (hereinafter sometimes referred to as mixing).

The antireflection film is required to have a uniform film thickness over the entire substrate, but since the substrate used usually has a step, the substrate having such a step, particularly the step portion ( Also in the edge portion, an antireflection film having the same film thickness as the other portions can be formed. That is, good step coverage. The antireflection film that is removed by dry etching is easily etched, that is, it has low dry etching resistance (in contrast, the photoresist film is required to have high etching resistance). Also, if the film thickness is large and etching takes a long time, the photoresist film will also be etched, so the film thickness should be as thin as possible.

It must have a sufficient absorbance for the light used for exposing the antireflection film. In particular, in order to obtain good step coverage, the coating film thickness may be increased. On the other hand, there is also a demand for thinning the film thickness. Therefore, an antireflection composition having good step coverage even when thinly applied is required. Was there. Even in the past, an attempt was made to use an antireflection film by adding a light-absorbing material to an existing quinonediazide-based photoresist composition or a polyimide-based polymer to form an antireflection composition, and heat-curing the coating to insolubilize it. But
With such an antireflection composition, it was difficult to solve all of the above problems.

Further, in the quinonediazide type photoresist composition and the polyimide type antireflection composition, a large amount of organic solvent is contained, and an antireflection composition using water as a solvent has been desired from the viewpoint of environment. . An antireflection composition using a water-soluble organic compound has been studied (Japanese Patent Laid-Open No. 1-1475).
No. 35, etc.). However, although the antireflection film thus formed does not cause mixing with the photoresist composition, it has a drawback that the antireflection film is too easily dissolved in the developing solution during development of the photoresist film after exposure. is there. Therefore, even the antireflection film under the photoresist film that should be left as a pattern is dissolved and removed in the developing solution, and problems such as peeling disappearance of the fine pattern occur. Therefore, an antireflection composition using water as a solvent,
In addition, the antireflection film formed is desired to be insoluble in the developing solution.

As a means for solving these problems, the present inventor has already proposed an antireflection composition using polyvinyl alcohol in Japanese Patent Application No. 7-273963.
In the antireflection composition according to this proposal, since a resin that does not have an aromatic ring is used for the coating film forming material, it is preferable in that dry etching resistance is low, but a light absorber is used to obtain sufficient light absorption. It was necessary to use them together, and it was necessary to adjust them so that both dry etching resistance and absorptivity would exhibit sufficient performance.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to suppress mixing with a photoresist and to provide good step coverage even with a thin film thickness. It is an object of the present invention to provide an antireflection composition that does not dissolve during development of a photoresist film, has a large absorbance even when the amount of a light absorber added is small, and provides an antireflection film having good dry etching properties. Another object of the present invention is to provide an antireflection composition using water or an aqueous solvent containing water as a main component. Still another object of the present invention is to provide a pattern forming method in which the deterioration of the resolution and the deformation of the resist pattern are small and the change in the sensitivity due to the change in the coating film thickness is suppressed.

[0013]

The antireflection composition according to the present invention is characterized in that it contains water and polyvinyl alcohol, and its liquid property is acidic at a pH of 4 or less. Then, a step of applying the antireflection composition on a substrate to form an antireflection film, a step of applying a photoresist composition on the antireflection film to form a photoresist film, and exposing the photoresist film The predetermined pattern can be accurately and efficiently reproduced on the substrate by sequentially performing the steps of transferring the predetermined pattern with the developer and developing the exposed photoresist film with a developing solution.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail. It is essential that the antireflection composition according to the present invention contains a polyvinyl alcohol resin as a constituent component. Polyvinyl alcohol resin is manufactured by hydrolyzing polyvinyl acetate to convert acetyl groups in the polyvinyl acetate molecule into hydroxyl groups. A value in which the ratio of the hydroxyl groups is expressed in mol% is called a saponification degree, and polyvinyl alcohol resins are known to have various properties depending on the saponification degree. For example, it is generally known that polyvinyl acetate is water-insoluble and polyvinyl alcohol resin is water-soluble, but even polyvinyl alcohol resin has a saponification degree of 6
If it is less than 0%, the solubility in water becomes poor and the saponification degree becomes 30%.
% Or less, it does not substantially dissolve. On the other hand, if the degree of saponification is too high, the solubility will be low, with 85 to 90% having the highest solubility. In the present invention, it is preferable to use a polyvinyl alcohol resin having a saponification degree of 70% or more. If the saponification degree is less than 70%, for example, the developer resistance at the time of development may deteriorate, or mixing may occur at the time of forming the photoresist film. Generally, the higher the degree of saponification, the better the resistance to developing solution. Therefore, it is preferable to use a polyvinyl alcohol resin having a degree of saponification of 75% or more. However, on the contrary, if the saponification degree is too high, the storage stability of the composition (generation of insoluble foreign matter) tends to deteriorate, so that the saponification degree of the polyvinyl alcohol resin is 99% or less, further 98% or less. Is preferred.

The degree of polymerization of the polyvinyl alcohol resin is usually represented by the viscosity of a 4% aqueous solution (20 ° C.).
It is generally about 80 cps (mPa · s). Among them, the polyvinyl alcohol resin used in the present invention preferably has a viscosity of usually 5 cps or more, particularly 10 cps or more. The upper limit of viscosity is 70c
It is preferably ps, especially 65 cps.

The polyvinyl alcohol resin may be a resin modified by substituting a part of the hydroxyl groups with an alkyl ether group, an alkyloxymethyl group, an acetyl acetate group or the like. In the antireflection composition according to the present invention, another water-soluble resin may coexist as long as it does not adversely affect the formed antireflection film. Examples of these resins include polyacrylic acid, polyvinylpyrrolidone, polyvinyl methyl ether, and water-soluble cellulose derivatives. If the coexisting amount of these resins is too large, it adversely affects. Therefore, it is usually preferable to limit the amount to 30% by weight or less, particularly 10% by weight or less based on the polyvinyl alcohol resin.

The antireflection composition according to the present invention is basically prepared by dissolving the above water-soluble resin in water. If desired, an organic solvent may be mixed with water, and examples of the organic solvent used include alcohols such as isopropyl alcohol, butanol, methoxyethanol, ethoxyethanol, methoxypropanol, and diacetone alcohol; ethylene glycol, propylene glycol. And the like; dialkyl ethers of glycols such as dipropylene glycol dimethyl ether; hydroxy or oxyalkylcarboxylic acid alkyl esters such as ethyl lactate and ethyl pyruvate; amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone And the like. The amount of these organic solvents is preferably as small as possible, and is usually 50% by weight or less, preferably 30% by weight or less with respect to water. The ratio of the resin to the solvent is appropriately selected in consideration of coating properties and coating film thickness,
Usually, the lower limit is 0.1% by weight with respect to the solvent, and the upper limit is about 50% by weight. Preferably, the lower limit is 1% by weight and the upper limit is about 30% by weight.

The antireflection film formed of the antireflection composition according to the present invention has a considerable antireflection effect even if it does not contain a light-absorbing material. Can be enhanced. Any light absorbing material may be used as long as it absorbs light near the exposure wavelength such as g-line, i-line, or excimer region. Specific examples of these light-absorbing materials include phenylsulfate and 2- (2 '
-Hydroxy-5'-methylphenyl) -benzotriazole, (4-benzoylbenzyl) trimethylammonium chloride, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2
-Hydroxy-4-dodecyloxybenzophenone, 2
-Hydroxy-4-benzyloxybenzophenone,
2,2 ', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2', 3,4,4'-pentahydroxybenzophenone, 2,3,3 ', 4, 4', 5'-
Hexahydroxybenzophenone, 2-hydroxy-4
-Methoxybenzophenone-5-sulfonic acid, 2,
2'-dihydroxy-4,4'-dimethoxybenzophenone-5-sulfonic acid, 4-aminoazobenzene,
4,4'-diethylaminoazobenzene, 4-chloro-
4'-dimethylaminoazobenzene, 4-hydroxyazobenzene, 4-hydroxy-4'-dimethylaminoazobenzene, 2- (4'-hydroxyphenylazo) benzoic acid, 4- (4'-hydroxyphenylazo) benzoic acid, 4 -(4'-hydroxyphenylazo) benzenesulfonic acid, 4- (2'-hydroxynaphthylazo) azobenzene, 4- (3'-methyl-4'-hydroxyphenylazo) azobenzene, 2-methyl-4- (4 ′-
(Hydroxyphenylazo) -5-methoxyazobenzene, cresol red, methyl red, neutral red, bromophenol red, methyl yellow, thymol blue, sudan III, sudan red B, sudan orange G, CI-direct yellow 28, CI-direct yellow 50 , CI-Direct Yellow 86, Acid Yellow 25, Acid Yellow 38, Acid Yellow 76, Modant Yellow 7, Mod Dan Yellow 10, Mod Dan Yellow 12, Alizarin Yellow GG and the like.

Among these, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2,2'-
Dihydroxy-4,4'-dimethoxybenzophenone-
An acidic light absorbing material having a sulfonic acid group such as 5-sulfonic acid is preferable. Among them, an acidic light-absorbing material is preferable from the viewpoint of being able to make the pH of the antireflection composition acidic and also having the effect of increasing the absorbance. The proportion of the light-absorbing material in the antireflection composition is appropriately selected depending on the light absorption coefficient of the light-absorbing material and the film thickness of the antireflection film, but it is preferably as small as possible to achieve the desired effect, excluding the solvent in the composition. The content is usually 50 parts by weight or less, preferably 40 parts by weight per 100 parts by weight of total weight (solid content).
It is not more than 30 parts by weight, more preferably not more than 30 parts by weight.
Further, in order to exert the effect, 1 part by weight is usually necessary, preferably 3 parts by weight or more, more preferably 5 parts by weight or more.

The antireflective composition according to the present invention must be acidic with a pH of 4 or less. Since the pH of the aqueous solution of the polyvinyl alcohol resin alone is weakly acidic, usually 5 to 7,
Absorbing material having a sulfonic acid group, hydrochloric acid, sulfuric acid,
The pH is adjusted to 4 or less by addition of an inorganic acid such as nitric acid, or an acidic substance such as an organic acid such as trifluoromethylsulfonic acid or p-toluenesulfonic acid. As described above, the addition of the light absorbing material is preferable because it also has the effect of increasing the absorbance.

When the pH of the antireflection composition is adjusted to 4 or less, the solvent resistance of the antireflection film formed by applying the composition to a substrate and heating the composition is improved, and at the same time, the absorbance of ultraviolet light is increased. It is extremely preferable in terms of performance of the antireflection film. The preferred pH of the composition is 3.5 or less, especially 3 or less. However, when the pH is lowered to some extent, the effect is saturated, and even if the pH is further lowered, the effect is hardly improved. Therefore, the pH of the composition is usually 0 or higher, preferably 1 or higher. The antireflection composition according to the present invention may further contain a surfactant and other auxiliaries for improving the coating property. The amount of addition is appropriately selected according to the desired performance required.

In the present invention, the above antireflection composition is applied to a substrate and heated to form an antireflection film, and then a photoresist composition is applied thereon by a conventional method to form a photoresist film. As the photoresist composition coated on the antireflection film, various conventionally known radiation-sensitive compositions can be used. For example, conventional g
Line, i line, excimer laser light (248 nm, 193n
The photoresist composition for m) can be used, and the material can be either a positive type or a negative type.

Specific photoresist compositions include:
Polyvinyl cinnamate-based and polyisoprene cyclized rubber-based photocrosslinking photoresist compositions (for example, Journal of Organic Synthetic Chemistry, Vol. 42, No. 11, p. 979), 1, 2.
A quinonediazide compound and an alkali-soluble resin dissolved in an organic solvent (for example, Journal of Synthetic Organic Chemistry,
Volume 42, No. 11, pp. 979, JP-A-62-1366
37, JP-A-62-153950, etc.),
A so-called chemically amplified photoresist composition which exhibits radiation-sensitive performance by polymerizing or depolymerizing with an acid or a base generated by light irradiation (for example, JP-A-59-45439 and JP-A-4-136860). Japanese Patent Laid-Open No. 4-13
6941).

The resin used in the photoresist composition is a polyvinyl cinnamate resin produced from a polyvinyl alcohol resin and cinnamic acid chloride, or a cyclized rubber resin containing 1,4-cis polyisoprene as a main component. Is mentioned. If necessary, a photo-crosslinking agent such as 4,4′-diazidochalcone or 2,6-di- (4′-azidobenzylidene) cyclohexanone may be added to these resins.

1, 2 used in the photoresist composition
As the quinonediazide compound, usually, 1,2-benzoquinonediazide-4-sulfonic acid ester compound or amide compound, 1,2-naphthoquinonediazide-4-sulfonic acid ester compound or amide compound, 1,2-naphthoquinonediazide-5 -Sulfonic acid ester compounds, amide compounds and the like are listed.

More specifically, compounds having an aliphatic hydroxyl group such as methanol and ethylene glycol; phenols such as phenol and cresol; bisphenols such as bisphenol A: 4,4 ', 4 "-methylidine trisphenol , 4,4 ′-[1- [4- (4-hydroxyphenyl) -1-methylethyl] phenyl] ethylidene] bisphenol and other trisphenols: 4,
Tetrakisphenols such as 4 ′, 4 ″, 4 ′ ″-(1,4-phenylenedimethylidine) tetrakisphenol: pyrogallol, pyrogallol derivatives such as gallic acid ester: 2,3,4-trihydroxybenzophenone,
Polyhydroxybenzophenones such as 2,3,4,4′-tetrahydroxybenzophenone: compounds having a phenolic hydroxyl group such as novolak resin described later,
1,2-benzoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-4-sulfonic acid ester, 1,2-naphthoquinonediazide-5-sulfonic acid ester and the like can be mentioned. Further, compounds having an aliphatic amino group such as ethylamine and butylamine: and /
Alternatively, 1,2-benzoquinonediazide-4-sulfonic acid amide, 1,2-naphthoquinonediazide-4-sulfonic acid amide, 1,2-naphthoquinonediazide of a compound having an aromatic amino group such as aniline and paraphenylenediamine -5-sulfonic acid amide etc. are mentioned.

As the alkali-soluble resin, a novolac resin and a polyvinylphenol resin are generally mentioned, and a novolac resin is particularly preferable. Examples of novolac resins include phenols; o-cresol, m-cresol, p-cresol, 3-ethylphenol,
2,5-xylenol, 3,4-xylenol, 3,5
-Alkylphenols such as xylenol; alkoxy or aryloxyphenols such as 2-methoxyphenol, 4-methoxyphenol, 4-phenoxyphenol; alkyl groups such as α-naphthol, β-naphthol, 3-methyl-α-naphthol Optionally substituted naphthols; resorcinol, 2-methylresorcinol, pyrogallol, compounds having a phenolic hydroxyl group such as polyhydroxybenzenes optionally substituted with an alkyl group such as 5-methylpyrogallol, and formaldehyde, Aliphatic aldehydes such as paraformaldehyde, acetaldehyde and paraaldehyde; aromatic aldehydes such as benzaldehyde; carbonyl compounds such as alkyl ketones such as acetone;
Examples thereof include those produced by heating and polycondensing in the presence of an acidic catalyst such as sulfuric acid or oxalic acid. In addition, this polycondensation reaction can be performed in a solvent inert to the reaction of ethanol, ethyl cellosolve acetate, methyl 3-methoxypropionate, or the like, or without a solvent.

The photoresist composition (1) may be a resin having an acid-labile group such as poly (p-tert-butoxycarbonyloxy) styrene and a light irradiation of triphenylsulfonium hexafluoroarsenate. Examples thereof include a photoresist composition which comprises a compound that generates an acid and whose light-irradiated portion is solubilized or insoluble in a developing solution (for example, JP-A-59-45439). Further, it is composed of a novolak resin obtained by polycondensing a phenol and an aldehyde, a cross-linking agent such as alkoxymethylated melamine and alkoxymethylated urea, and a compound that generates an acid by light irradiation such as halogenated methyltriazine. A photoresist composition whose part is insolubilized in a developing solution is also included (for example, JP-A-4-136860).
Japanese Patent Laid-Open No. 4-136941).

The photoresist composition usually contains an organic solvent. Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene; acetic acid esters such as ethyl acetate; mono- or diethylene glycol such as ethyl cellosolve. Mono or dialkyl ethers; mono or dialkyl ethers of mono or dipropylene glycol such as propylene glycol monomethyl ether; alkyl cellosolve acetates such as propylene glycol monomethyl ether acetate; esters of ethylene carbonate, γ-butyrolactone etc .; methyl ethyl ketone, 2-heptanone, Ketones such as cyclopentanone; and hydroxy, alkoxy or oxyalkylcarboxylates such as ethyl lactate, methyl 3-methoxypropionate, ethyl pyruvate and the like. These solvents are appropriately selected in consideration of the solubility of the resin and the photosensitizer, the stability of the photoresist composition, and the like. Further, these photoresist compositions may also contain a surfactant for improving the coating property, a sensitizer for improving the sensitivity, and the like, if necessary.

The substrate used for pattern formation is not particularly limited, but a substrate for IC production such as a silicon substrate or a gallium arsenide substrate is generally used, and a layer having a high reflectance such as aluminum is formed on the surface. Those that are also used.
The method of applying the antireflection composition on the substrate and the method of applying the photoresist composition on the formed antireflection film are not particularly limited, and a spin coater or the like is used according to a conventional method.

The applied antireflection composition is usually heat-treated using a hot plate or the like to remove the solvent, but if the temperature is too low, the solvent resistance of the formed antireflection film is not improved, In addition to the possibility that the antireflection film is also dissolved during development, the absorbance of the coating film is not large, which is not preferable. On the contrary, if the temperature is too high, the polyvinyl alcohol resin is decomposed and particles are generated, which is not preferable. In order to impart good solvent resistance to the antireflection film, it is preferably carried out at 130 ° C. or higher and 260 ° C. or lower, and preferably 140 ° C. or higher and 240 ° C. or higher.
Should be done below ℃. This heat treatment greatly improves the absorbance of the antireflection film. When the pH is out of the range specified in the present invention, the absorbance changes little even when heat-treated at high temperature. The reason why the absorbance is greatly improved only when the pH is 4 or less is acidic, but the polyvinyl alcohol itself is acidic and causes an intramolecular dehydration reaction.
It is considered that the formation of the conjugated double bond caused thermal denaturation and caused a change in absorbance.

The suitable range of the heat treatment temperature varies depending on the type of polyvinyl alcohol resin used.
The degree of saponification of polyvinyl alcohol and the heat treatment temperature are displayed in a two-dimensional graph with the vertical axis and the horizontal axis, respectively, and the point A
(Saponification degree 70%, heat treatment temperature 160 ° C), point B (saponification degree 70%, heat treatment temperature 240 ° C), point C (saponification degree 1
00%, heat treatment temperature 260 ° C., point D (saponification degree 100)
%, Heat treatment temperature 110 ° C.), particularly point E (saponification degree 75%, heat treatment temperature 170 ° C.), point F (saponification degree 75%, heat treatment temperature 230 ° C.), point The range surrounded by the points G (saponification degree 99%, heat treatment temperature 240 ° C.) and point H (saponification degree 99%, heat treatment temperature 115 ° C.) is preferable. Most preferred is point E (saponification degree 75
%, Heat treatment temperature 170 ° C.), point I (saponification degree 75%, heat treatment temperature 200 ° C.), point J (saponification degree 98%, heat treatment temperature 200 ° C.), point K (saponification degree 98%, heat treatment temperature 12)
(0 ° C.) is the range surrounded by each point. The heat treatment time is usually 30 seconds or longer and 600 seconds or shorter, preferably 50 seconds or longer and 300 seconds or shorter.

Since the antireflection film formed from the antireflection composition according to the present invention has a shrinkage ratio by heat treatment larger than that of the conventional one, it is applied as a relatively thick film so as to have good step coverage. Then, the film can be contracted by subsequent heat treatment to finally obtain an antireflection film having a thin film thickness. As a result, by using the antireflection composition according to the present invention, it is possible to form an antireflection film having good step coverage and a thin film thickness. In order to obtain good solvent resistance of the antireflection film, the heat treatment temperature of 200 ° C. or lower is sufficient as described above, but in order to obtain a thin antireflection film with a large shrinkage, a higher temperature is required. For example, the heat treatment can be performed at a high temperature of 200 to 220 ° C., further 220 to 260 ° C. However, if the heat treatment is performed at an excessively high temperature for a long time, the polyvinyl alcohol resin is decomposed and the film is deteriorated, which is not preferable.

The antireflection film formed from the antireflection composition according to the present invention has lower dry etching resistance than conventional resins such as novolac resin and polyimide resin even after the above heat treatment. There are advantages. The thickness of the antireflection film thus obtained varies depending on the concentration of the light absorber in the antireflection film, the requirements from the photolithography process, and the like, but is about 0.05 to 2 μm, usually about 0.1 to 1 μm. is there.

Various conventionally known methods can be adopted for the method of coating the photoresist composition on the antireflection film, the method of exposure, the method of development, and the like. The film thickness (dry film thickness) of the applied photoresist composition is usually 0.3 to 5
It is about μm. Further, after applying the photoresist composition, a heat-drying treatment may be carried out, usually using a hot plate or the like at 70 to 130 ° C. for 30 to 120 seconds.

The exposure wavelength used for image transfer to the formed photoresist film is usually g-line (436).
nm), i-line (365 nm), XeCl excimer laser light (308 nm), KrF excimer laser light (24
8 nm), ArF excimer laser light (193 nm), etc. are used. After exposure of the photoresist film, post-exposure heating may be performed if necessary. For example, using a hot plate or the like, heat treatment at 70 to 130 ° C. for about 60 to 120 seconds is suitable. A convection oven may be used instead of the hot plate, but this usually requires a longer time than when using a hot plate.

As a developing solution for developing the exposed photoresist film, an alkaline aqueous solution is usually used.
For example, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, aqueous ammonia, sodium silicate, and sodium metasilicate, ethylamine, n-
Primary amines such as propylamine, diethylamine,
Secondary amines such as di-n-propylamine, tertiary amines such as triethylamine and methyldiethylamine,
An aqueous solution of a quaternary ammonium salt such as tetramethylammonium hydroxide or trimethylhydroxyethylammonium hydroxide, or a solution obtained by adding an alcohol or the like to this is used. If necessary, a surfactant or the like can be added to the developing solution. The development time is preferably about 30 to 180 seconds, and the development temperature is preferably about 15 to 30 ° C. In addition, the developer is usually used after being filtered to remove insoluble matter at the time of use.

[0038]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples unless it exceeds the gist thereof. In the following examples, unless otherwise specified, the photoresist compositions were handled in a class 100 clean room using fluorescent lamps that shielded light of 500 nm or less (so-called yellow room). .

Example 1 Polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., K
H-20, saponification degree 78.5-81.5%), 5.0 g
And 2-hydroxy-4-methoxybenzophenone-5
-Sulfonic acid (trihydrate) (manufactured by Cypro Kasei Co., Ltd., SE
0.5 g of ESORB 101S) was dissolved in 100 g of water. This was filtered through a membrane filter having a pore size of 0.2 μm to prepare antireflection composition A.

M-cresol, p-cresol and 2,
14.0 g of a cresol-based novolak resin (average molecular weight 3,500) synthesized from a mixture of 5-xylenol (molar ratio = 5: 4: 1) and a mixture of formaldehyde and acetaldehyde (molar ratio = 8: 2), and m -7.3 g of a photosensitizer obtained by reacting a novolak resin (average molecular weight 1,000) synthesized from cresol and acetaldehyde with 1,2-naphthoquinonediazide-5-sulfonic acid chloride (average esterification rate 40%). To 3
-Dissolved in 56 g of methyl methoxypropionate. This was filtered with a membrane filter having a pore size of 0.2 μm to prepare a photoresist composition A.

This antireflection composition A was applied by a spin coater onto a silicon wafer on which aluminum was sputtered to a thickness of about 0.2 μm, and then 60 at 200 ° C.
Baking was carried out for 2 seconds on a hot plate to form an antireflection film having a thickness of 0.2 μm. A photoresist composition A was further applied onto this antireflection film by a spin coater in the same manner, and then baked on a hot plate at 80 ° C. for 90 seconds to form a 1.07 μm thick photoresist film.

This wafer was exposed and developed by an ordinary method using an i-line stepper (NA = 0.5 manufactured by Nikon Corporation). Incidentally, the development was carried out by using a 2.38 wt% aqueous solution of tetramethylammonium hydroxide to prepare the wafer 23
It was performed by immersing at 60 ° C for 60 seconds. 1.0 μm
When the cross-sectional shape of the transferred pattern at the exposure amount that the line and space of 1 was finished at 1: 1 was observed using an electron microscope, the side wall of the pattern had no irregularities, and so-called standing waves were not observed. Further, there was no mixing between the antireflection film and the photoresist film, and the antireflection film under the photoresist film in the developed pattern portion remained without being dissolved and removed during development. Further, a fine pattern of 0.5 μm or more was present without peeling.

Comparative Example 1 Example 1 except that the antireflection composition A was not applied.
A wafer having a photoresist film was prepared, and exposed and developed in the same manner as in. When the cross-sectional shape of the transferred pattern was observed at an exposure amount at which a line and space of 1.0 μm was finished at 1: 1, the pattern side wall had severe irregularities, and so-called standing waves were largely observed.

Examples 2 to 6 and Comparative Examples 2 to 9 In the preparation of the antireflection composition A of Example 1, the polyvinyl alcohol and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid were replaced with those shown in Table-1. Antireflection composition B to in the same manner as in Example 1 except that the compound was used.
M was prepared. Each of the antireflection compositions A to M was coated on a glass substrate with a spin coater as in Example 1, and then baked on a hot plate at 90 ° C. for 60 seconds to form an antireflection film.

The absorbance of light at each wavelength of these antireflection films was measured. Then, each substrate was baked on a hot plate at 200 ° C. for 60 seconds, and then the absorbance of light at each wavelength was similarly measured. The measurement results of pH and absorbance of each composition are summarized in Table-2. In the present invention, the high temperature heating increases the absorbance at short wavelengths, and it can be seen that a large amount of light can be absorbed even with a small amount of the light absorbent.

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[Table 1]

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[Table 2]

Examples 7 to 9 The antireflection composition B was applied onto a glass substrate with a spin coater, and then baked on a hot plate at each temperature shown in Table 3 for 60 seconds to give a 0.2 μm thick reflection film. A protective film was formed. The results of measuring the absorbance of light at 248 nm and 365 nm for this antireflection film are shown in the table.
3 is shown.

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[Table 3]

Claims (10)

[Claims] 1. An antireflection composition applied between a substrate and a photoresist film, comprising water and a polyvinyl alcohol resin, and having an acidity of pH 4 or less. Stuff. 2. The antireflection composition according to claim 1, further comprising a light absorbing material. 3. The antireflection composition according to claim 2, wherein the light absorbing material is acidic. 4. The light absorbing material is a compound having at least one sulfonic acid group.
The antireflection composition described. 5. The content of the light-absorbing material is 1 to 50 parts by weight, based on 100 parts by weight of the total weight (solid content) excluding the solvent in the antireflection composition.
The antireflection composition described. 6. The antireflection composition according to claim 1, wherein the saponification degree of the polyvinyl alcohol resin is 70 to 99%. 7. The antireflection composition according to claim 1, wherein the polyvinyl alcohol resin has a viscosity of 5 to 75 cps at 20 ° C. in a 4% aqueous solution. 8. The antireflection composition according to claim 1, wherein the antireflection composition has a pH of 3.5 or less. 9. A step of applying an antireflection composition on a substrate to form an antireflection film, a step of applying a photoresist composition on the antireflection film to form a photoresist film, the photoresist film 9. A pattern forming method comprising a step of exposing a photoresist to transfer a predetermined pattern to a photoresist film, and a step of developing the photoresist film with a developing solution, wherein the antireflection composition comprises the antireflection composition.
A method for forming a pattern, which comprises using the antireflection composition as described in 1. 10. The heat treatment is performed at a temperature of 130 ° C. or higher after the application of the antireflection composition.
4. The pattern forming method according to 1.