JPH1017623A - New water-soluble polymer, antireflection film material containing the same, and method for forming pattern by using the material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-soluble polymer which can form a good rectangular pattern without causing any decrease in the thickness of unexposed parts when jointly used with a chemically amplifying resist material, can reduce the influence of standing waves, and is useful as a water-soluble antireflection film material by selecting a specific polymer. SOLUTION: This polymer is represented by the formula [wherein R<1> and R are each H, F, or a (fluoro)alkyl provided at least one of them is a fluoroalkyl; n is 1-3; R<2> is H, a (fluoro)alkyl, or hydroxyalkyl; k and j are each a natural number; m is 0 or k; 0.05<=j/(k+j+m)<=0.7; and 0<=m/(k+j+m)<=0.7] and pref. has a wt.-average mol.wt. of 1,000-30,000. A resist film formed by applying a resist material to a substrate is coated with an antireflection film material contg. the above-mentioned polymer to be covered with an antireflection film, is then exposed to a radiation through a pattern formation mask, is heated, if necessary, and is developed with a developing soln., thus forming a desired pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-soluble polymer useful as an anti-reflective coating material used for the purpose of reducing the influence of multiple interference in a resist film, particularly in a lithography process for manufacturing a semiconductor device. And a pattern forming method using the same.

[0002]

2. Description of the Related Art With the recent high-density integration of semiconductor device elements and the like, the processing size of a lithography process has been reduced in the field of fine processing, and accordingly, the energy source of an exposure apparatus has become shorter and shorter. For example, KrF excimer laser light (248.4 nm), ArF excimer laser light (1
A method using a charged particle beam such as a deep ultraviolet ray such as 93 nm), an electron beam, and a synchrotron has been proposed, and some of the methods have been studied for practical use. When such radiation is used, the amount of irradiation energy is limited, and high sensitivity is required. As a countermeasure, a chemically amplified resist material using an acid generated by irradiation as a medium has been proposed [e.g.
Ito et al., Polym. Eng. Sci., 23 , 1012 (1983) etc.], and numerous reports have been made thereafter [for example, JP-A-2-209977, JP-A-2-19847, JP-A-3-1967. No. 206458, Japanese Unexamined Patent Publication No. H4-211258 (US Pat. No. 5,350,660),
JP-A-5-249682 (US Pat. No. 5,468,589)
etc]. In these chemically amplified resist materials, the acid generated by irradiation plays an extremely important role in achieving high sensitivity, but on the other hand, in an atmosphere such as a basic substance or moisture in the lithography process. Acid is easily deactivated, resulting in a T-shaped resist pattern (T-Shape shape)
Or dimensional fluctuations occur with the lapse of time between exposure and heat treatment (Po
st ExposureDelay: Abbreviated below as PED. ). In addition, due to the use of a short wavelength and single wavelength and the use of a chemically amplified resist material having high light transmittance, when radiation is irradiated, radiation incident on the resist film and radiation reflected at the upper and lower interfaces of the resist film are not affected by the resist. The effect of standing waves generated by interfering with each other in the film (also known as the effect of multiple interference; even if the exposure dose is constant, if the resist film thickness changes, the effective exposure dose will fluctuate due to the mutual interference of radiation in the resist film. Phenomena that adversely affect the formation of a resist pattern). For example, if there is a step on the substrate, a difference in the coating film thickness occurs. Or
There are problems such as a decrease in dimensional accuracy of the resist pattern.

[0003] In order to solve the problems of these chemically amplified resist materials, a method of coating a surface layer of a resist film with an antireflection film has been proposed and many reports have been made. For example, JP-A-3-222409 proposes a water-soluble resin film such as polyvinyl alcohol. Also, JP-A-7-2952
No. 10 discloses a material using a quaternary ammonium compound. However, any of these materials has an effect of protecting the resist film from an atmosphere such as a basic substance or moisture, but it is difficult to suppress the influence of a standing wave.

In order to suppress the influence of the standing wave, it is effective to suppress reflection at the interface of the resist film. The antireflection effect depends on the refractive index and the thickness of the antireflection film. The ideal refractive index of the antireflection film is Δn (n represents the refractive index of the resist film), and the film thickness is λ / 4m (λ is the wavelength of radiation, and m is the refractive index of the antireflection film, respectively). Odd number times) is said to be ideal. For example, the refractive index of the resist film is about
In the case of 1.66, the refractive index of the antireflection film is ideally 1.28 to 1.29. This refractive index can be achieved by using a fluorine-based compound such as perfluoroalkyl polyether as described in JP-A-62-62520. However, this material requires removal treatment with freon (chlorofluorocarbon compound) before development, and has problems such as being expensive and is not practical.

[0005] In order to solve such problems, various antireflection film materials containing a compound containing a fluorine atom as a constituent have been reported. JP-A-5-188598, JP-A-6-148896, JP-A-6-273926 and JP-A-7-
No. 160002 discloses a material comprising a water-soluble polymer such as polyvinyl alcohol, polyacrylic acid or polyvinylpyrrolidone and a fluorinated alkyl carboxylic acid, a fluorinated alkyl sulfonic acid or a salt thereof as a constituent. However, when these materials are used, the acidity is too strong due to the use of the fluorinated alkyl carboxylic acid or the fluorinated alkyl sulfonic acid or salts thereof, so that the surface layer portion of the resist pattern after development is rounded. The problem is that the surface layer of the unexposed part is chemically amplified and the film is reduced due to the chemical amplification reaction. I have

Further, Japanese Patent Application Laid-Open Nos.
JP-A-234514 discloses a material composed of a monomer unit having a fluoroalkyl group in an ester portion and a monomer unit having a carboxyl group or a sulfonic acid group. Those materials having a sulfonic acid group also have a too strong acidity, so that the surface layer of the resist pattern after development becomes round, and the surface layer of the unexposed portion due to the sulfonic acid group or the fluoroalkyl ester group is also formed. There are problems such as the film being reduced due to the chemical amplification reaction and the device manufacturing equipment being damaged to cause a product defect.

[0007] Further, Japanese Patent Application Laid-Open Nos.
Japanese Patent No. 253674 discloses a material using a fluorinated alkyl polyether compound or a fluororesin. Since these materials do not dissolve in a normal aqueous alkaline solution during development, they require a complicated operation of removing them with an organic solvent such as toluene, xylene or Freon and then developing them, so that they are not practical.

[0008] As described above, a chemically amplified resist film is coated using the antireflection film material reported so far,
When forming a pattern on a resist film, the influence of an atmosphere such as a basic substance or moisture can be suppressed in common, but the effect of standing waves is not suppressed in non-fluorine-based materials, and a water-soluble fluorine-based compound is used. Even so, the pattern surface layer is rounded due to too strong acidity, causing a problem in etching, and the film loss of the unexposed portion is large, and the devices are damaged, resulting in product failure. In addition, the use of a water-insoluble fluorine-based compound has a problem that the treatment is required before development and the operation is complicated. Accordingly, there is a need for a practical water-soluble anti-reflective coating material which has solved these problems.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and when used in combination with a chemically amplified resist material, has a good rectangular resist pattern shape without film reduction in unexposed portions. To reduce the effects of standing waves, overcome the drawbacks of chemically amplified resist materials, such as not causing variations in PED and sensitivity, and remove the resist together with the resist during development. It is an object of the present invention to provide a practical water-soluble anti-reflective coating material which does not damage the kind, a water-soluble polymer used for the same, and a pattern forming method using the anti-reflective coating material.

[0010]

The present invention provides a compound represented by the general formula [1]:

[0011]

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Wherein R ¹ and n R each independently represent a hydrogen atom, a fluorine atom, an alkyl group or a fluorine-containing alkyl group (provided that at least one of R ¹ and n R is Represents a fluorine-containing alkyl group.), N represents an integer of 1 to 3, R ² represents a hydrogen atom, an alkyl group, a fluorine-containing alkyl group or a hydroxyalkyl group, and k and j each independently represent a natural number. And m represents 0 or a natural number (provided that 0.05 ≦ j / (k + j + m) ≦ 0.7 and 0 ≦
m / (k + j + m) ≦ 0.7. ). ] The invention of the polymer shown by this.

Further, the present invention relates to the above general formula [1]
An antireflection film material comprising a polymer represented by the formula:

Further, the present invention is a method for forming a resist pattern on a substrate, comprising: (1) a step of applying a resist material on the substrate and then heating to form a resist film; A step of applying the antireflection film material according to claim 3 on the resist film to form a film, and (3) a step of irradiating radiation through a mask for forming a pattern and heating as necessary. And 4) developing using a developer to form a desired pattern.

That is, the present inventors have made intensive studies to achieve the above object, and as a result, the polymer represented by the above general formula [1] has an appropriate acidity as an aqueous solution, and has a fluorine atom in the molecule. Since the effects of standing waves can be reduced due to the inclusion, it has been found that the object as a water-soluble surface anti-reflective coating material can be achieved, and the present invention has been completed.

In the general formula [1], the alkyl group represented by R ² may be linear or branched, and may be a lower alkyl group, for example, an alkyl group having 1 to 6 carbon atoms. Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, pentyl, isopentyl, and tert.
-Pentyl group, 1-methylpentyl group, n-hexyl group,
And an isohexyl group. The fluorine-containing alkyl group refers to a group in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom, and includes a group in which all hydrogen atoms are substituted with fluorine atoms. Specific examples of these fluorine-containing alkyl groups include, for example, fluoromethyl group, fluoroethyl group, fluoropropyl group, fluorobutyl group, fluoropentyl group, fluorohexyl group,
Difluoromethyl group, difluoroethyl group, difluoropropyl group, difluorobutyl group, difluoropentyl group, difluorohexyl group, trifluoromethyl group, 2,
2,2-trifluoroethyl group, 3,3,3-trifluoropropyl group, trifluorobutyl group, trifluoropentyl group, trifluorohexyl group, 1,1,2,2,2-pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 3,
3,4,4,4-pentafluorobutyl group, 4,4,5,5,5-pentafluoropentyl group, 5,5,6,6,6-pentafluorohexyl group, perfluoro-n-propyl group , Perfluoroisopropyl group, perfluoro-n-butyl group, perfluoroisobutyl group, perfluoro-tert-butyl group, perfluoro-sec-butyl group, perfluoropentyl group, perfluoroisopentyl group, 2-perfluoro -tert-pentyl group, perfluoro-n-hexyl group, perfluoroisohexyl group and the like. Examples of the hydroxyalkyl group include a 2-hydroxyethyl group, a 3-hydroxypropyl group, a 4-hydroxybutyl group, and a 2,3-dihydroxypropyl group in which one or two hydrogen atoms of the alkyl group are substituted with a hydroxyl group. And the like.

In the general formula [1], the alkyl group of the fluorine-containing alkyl group represented by R ¹ and R may be linear or branched and may be a lower alkyl group such as 1 to 6 alkyl groups, specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group,
n-butyl group, isobutyl group, sec-butyl group, pentyl group, isopentyl group, tert-pentyl group, 1-methylpentyl group, n-hexyl group, isohexyl group and the like. It refers to an alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and includes an alkyl group in which all hydrogen atoms are substituted with fluorine atoms. Specific examples of these fluorine-containing alkyl groups include, for example, fluoromethyl group, fluoroethyl group, fluoropropyl group, fluorobutyl group, fluoropentyl group, fluorohexyl group, difluoromethyl group, difluoroethyl group, difluoropropyl group, difluorobutyl Group, difluoropentyl group, difluorohexyl group,
Trifluoromethyl group, 2,2,2-trifluoroethyl group,
3,3,3-trifluoropropyl group, trifluorobutyl group, trifluoropentyl group, trifluorohexyl group, 1,1,2,2,2-pentafluoroethyl group, 2,2,3,3,3 -Pentafluoropropyl group, 3,3,4,4,4-pentafluorobutyl group, 4,4,5,5,5-pentafluoropentyl group, 5,5,6,
6,6-pentafluorohexyl group, perfluoro-n-propyl group, perfluoroisopropyl group, perfluoro-
n-butyl group, perfluoroisobutyl group, perfluoro-tert-butyl group, perfluoro-sec-butyl group, perfluoropentyl group, perfluoroisopentyl group, 2-
Examples thereof include a perfluoro-tert-pentyl group, a perfluoro-n-hexyl group, and a perfluoroisohexyl group. Among them, a perfluoroalkyl group in which all hydrogen atoms of an alkyl group are substituted with fluorine is particularly preferable.

The polymer represented by the above general formula [1] of the present invention has the general formula [2] for enhancing water solubility.

[0019]

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An α-hydroxyacrylic acid monomer unit represented by the following formula and a general formula [3] used for bringing the refractive index of the antireflection film close to an ideal value:

[0021]

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(Wherein R, R ¹ and n are as defined above)
And a monomer unit represented by the general formula [4] optionally used for controlling acidity or improving water solubility:

[0023]

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(Wherein R ² is the same as described above).

The polymer of the present invention has high water solubility due to the high content of hydroxyl groups and carboxyl groups.
Further, although the acidic group is derived only from the carboxylic acid of the weak acid, the acidity required for the antireflection film is also sufficient to suppress the influence of the basic substance. In addition, since the acidic groups of the polymer of the present invention are only those derived from a weak acid carboxylic acid, a conventional anti-reflective coating material having an acidic group derived from a strong acid such as sulfonic acid or fluorinated alkyl carboxylic acid is used. In this case, problems such as poor pattern shape (roundness of the resist film surface layer) due to chemical amplification of the unexposed portion caused at the interface with the resist and film reduction in the unexposed portion hardly occur.

The monomer unit represented by the general formula [3] is
Although those derived from a fluorinated alkyloxymethyl olefin carboxylic acid, specific examples of these monomers include, for example, α-trifluoromethyloxymethyl acrylic acid, α-2,2,2-trifluoroethyloxy Methyl acrylic acid, α-perfluoroethyloxymethyl acrylic acid, α-3,3,3-trifluoropropyloxymethyl acrylic acid, α-perfluoropropyloxymethyl acrylic acid, α-hexafluoroisopropyloxymethyl acrylic acid, α-2,2,3,3,3-pentafluoropropyloxymethyl acrylic acid, α-3,3,4,4,4-pentafluorobutyloxymethyl acrylic acid, α-α-4,4,4- Trifluorobutyloxymethylacrylic acid, α-perfluorobutyloxymethylacrylic acid and the like.
These monomers may be in the form of a salt, for example, an alkali metal salt such as sodium or potassium or an ammonium salt.

The monomer unit represented by the general formula [4] is
Olefin carboxylic acid, alkyl olefin carboxylic acid, those derived from fluorinated alkyl olefin carboxylic acid and the like, specific examples of these monomers include, for example, acrylic acid, methacrylic acid, α-trifluoromethyl acrylic acid, α-hydroxymethylacrylic acid, α-ethylacrylic acid, α-2,2,2-trifluoroethylacrylic acid and the like. In addition, these monomers are
For example, it may be in the form of a salt such as an alkali metal salt such as sodium or potassium or an ammonium salt.

The composition ratio of the monomer unit represented by the general formula [3] in the polymer represented by the general formula [1] is considered assuming that the monomer unit is used as an antireflection film material for a resist. A range of 5 to 70 mol% that can suppress the influence of standing waves while maintaining water solubility (that is,
In the general formula [1], 0.05 ≦ j / (k + j + m) ≦ 0.
7. ) Is preferred, and 10 to 50 mol% (that is, 0.1 ≦ j /
(K + j + m) ≦ 0.5. Is more preferable. The proportion of the monomer unit represented by the general formula [4] in the polymer represented by the general formula [1] is usually set at 0 to improve the water solubility of the polymer and secure an appropriate acidity. -70 mol% (that is, 0 ≦ m / (k + j + m) ≦ 0.7 in the general formula [1]).
Is appropriately selected from the following, but in the range of 0 to 50 mol% (ie,
0 ≦ m / (k + j + m) ≦ 0.5) is more preferable.

Specific examples of the polymer represented by the general formula [1] of the present invention include poly (α-hydroxyacrylic acid / α-trifluoromethyloxymethylacrylic acid) and poly (α-hydroxyacrylic acid / α -Trifluoromethyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-
Trifluoromethyloxymethylacrylic acid / methacrylic acid, poly (α-hydroxyacrylic acid / α-trifluoromethyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid / α-trilic acid) Fluoromethyloxymethylacrylic acid / acrylic acid), poly (α-hydroxyacrylic acid / α-2,2,
2-trifluoroethyloxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α-hydroxyacrylic acid) / Α-2,2,
2-trifluoroethyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid / methacrylic acid), poly (α -Hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid / acrylic acid), poly (α-hydroxyacrylic acid / α-perfluoroethyloxymethylacrylic acid), poly (α-hydroxyacrylic) Acid / α-perfluoroethyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α-hydroxyacrylic acid /
α-perfluoroethyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid / α-perfluoroethyloxymethylacrylic acid / methacrylic acid), poly (α-hydroxyacrylic acid / α) -Perfluoroethyloxymethylacrylic acid / acrylic acid), poly (α-hydroxyacrylic acid / α-
3,3,3-trifluoropropyloxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-3,3,3-trifluoropropyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α -Hydroxyacrylic acid / α-3,3,3-trifluoropropyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid / α-3,3,3-trifluoropropyloxy) Methylacrylic acid / methacrylic acid), poly (α-hydroxyacrylic acid / α-3,3,3-trifluoropropyloxymethylacrylic acid / acrylic acid), poly (α-hydroxyacrylic acid / α-hexafluoroisopropyloxy) Methylacrylic acid), poly (α-hydroxyacrylic acid / α-hexafluoroisopropyloxymethylacrylic acid / α-hydroxymethylacrylic acid), (Α-hydroxyacrylic acid / α-hexafluoroisopropyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid / α-hexafluoroisopropyloxymethylacrylic acid / methacrylic acid), poly ( α-hydroxyacrylic acid / α-hexafluoroisopropyloxymethylacrylic acid / acrylic acid), poly (α-hydroxyacrylic acid / α-perfluoropropyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α-
Hydroxyacrylic acid / α-perfluoropropyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid / α-perfluoropropyloxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-perfluoropropyloxymethylacrylic acid / methacrylic acid), poly (α-hydroxyacrylic acid / α-perfluoropropyloxymethylacrylic acid / acrylic acid), poly (α-hydroxyacrylic acid / α-3,3, 3-trifluoropropyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-3,3,3-trifluoropropyloxymethylacrylic acid / α-trifluoromethylacrylic acid) , Poly (α-hydroxyacrylic acid / α-
3,3,3-trifluoropropyloxymethylacrylic acid /
Methacrylic acid), poly (α-hydroxyacrylic acid / α-
3,3,3-trifluoropropyloxymethylacrylic acid /
Acrylic acid), poly (α-hydroxyacrylic acid / α-3,
3,3-trifluoropropyloxymethylacrylic acid),
Poly (α-hydroxyacrylic acid / α-2,2,3,3,3-pentafluoropropyloxymethylacrylic acid), poly (α
-Hydroxyacrylic acid / α-2,2,3,3,3-pentafluoropropyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-
2,2,3,3,3-pentafluoropropyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-
Hydroxyacrylic acid / α-2,2,3,3,3-pentafluoropropyloxymethylacrylic acid / methacrylic acid), poly (α-hydroxyacrylic acid / α-2,2,3,3,3-pentafluoro) Propyloxymethylacrylic acid / acrylic acid), poly (α-hydroxyacrylic acid / α-3,3,4,4,4-
Pentafluorobutyloxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-3,3,4,4,4-pentafluorobutyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α-hydroxy Acrylic acid /
α-3,3,4,4,4-pentafluorobutyloxymethylacrylic acid / methacrylic acid, poly (α-hydroxyacrylic acid / α-3,3,4,4,4-pentafluorobutyloxymethylacrylic) Acid / acrylic acid), poly (α-hydroxyacrylic acid / α-3,3,4,4,4-pentafluorobutyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid) / Α-4,4,4-trifluorobutyloxymethylacrylic acid), poly (α-
Hydroxyacrylic acid / α-4,4,4-trifluorobutyloxymethylacrylic acid / α-hydroxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-4,4,4-trifluorobutyloxymethylacrylic) Acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid / α-4,4,4-trifluorobutyloxymethylacrylic acid / methacrylic acid), poly (α-hydroxyacrylic acid / α-4) , 4,4-trifluorobutyloxymethylacrylic acid / acrylic acid, poly (α-hydroxyacrylic acid / α-perfluorobutyloxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-perfluorobutyloxy) Methylacrylic acid / α-hydroxymethylacrylic acid), poly (α-hydroxyacrylic acid / α-
Perfluorobutyloxymethylacrylic acid / α-trifluoromethylacrylic acid), poly (α-hydroxyacrylic acid / α-perfluorobutyloxymethylacrylic acid / methacrylic acid), poly (α-hydroxyacrylic acid / α-par) Fluorobutyloxymethyl acrylic acid /
Acrylic acid) and the like, but are not limited to these.

The polymer represented by the general formula [1] of the present invention, especially when used as an antireflection film material, is formed by the functional group containing a fluorine atom in the general formula [1]. Since the refractive index can be made close to an ideal value, the effect of standing waves can be reduced, and at the same time, the compound has water solubility due to hydroxyl groups and carboxyl groups contained in the molecule, and has an appropriate acidity. For this reason, it is only necessary to add a surfactant for the purpose of controlling the film formation as needed, and various problems caused by the conventional antireflection film material, particularly, the roundness of the resist pattern surface layer and the load on the device manufacturing equipment ( For example, a product defect is generated due to the generation of rust.

The polymer represented by the general formula [1] according to the present invention can be easily obtained, for example, by the following method.

That is, first, the general formula [5]

[0033]

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(Wherein R ⁵ represents an alkyl group or an acyl group, and R ⁶ represents a lower alkyl group), and an arbitrary amount of the general formula [6]

[0035]

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(Wherein R ⁷ represents a lower alkyl group;
R, R ¹ and n are the same as above. ) Monomer,
If necessary, the general formula [7]

[0037]

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[0038] (wherein, R ⁸ represents a lower alkyl group, R ²
Is the same as above. ) In an inert gas stream in a suitable organic solvent in the presence of (i) a catalytic amount of a radical polymerization initiator, and optionally a chain transfer agent in the presence of 20 to 150
The polymerization reaction is carried out at a temperature of -78 to 0 ° C for 0.5 to 20 hours in the presence of a living anionic polymerization initiator. After the reaction, a post-treatment is carried out according to a conventional method for obtaining a polymer to obtain a compound represented by the general formula [8]:

[0039]

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Where R, R ¹ , R ² , R ⁵ , R ⁶ , R ⁷ ,
R ⁸ , k, j and m are the same as above. ) Can be obtained.

In the general formulas [5] and [8], the alkyl group represented by R ⁵ may be linear, branched or cyclic, and may be a lower alkyl group such as 1 to 6 alkyl groups, specifically, methyl, ethyl, n-propyl, isopropyl, n-
Butyl group, isobutyl group, sec-butyl group, pentyl group,
Examples include an isopentyl group, a tert-pentyl group, a 1-methylpentyl group, an n-hexyl group, an isohexyl group, a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group. As the acyl group, for example, an acyl group having 1 to 7 carbon atoms derived from a carboxylic acid is preferable, and specifically, an acetyl group,
Examples include a propionyl group, a butyryl group, a pentanoyl group, a hexanoyl group, a heptanoyloxy group, and a benzoyloxy group. In the general formulas [5], [6], [7] and [8], the lower alkyl groups represented by R ⁶ , R ⁷ and R ⁸ are each independently a linear or branched one. May be any of cyclic or cyclic, and examples thereof include an alkyl group having 1 to 6 carbon atoms. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a sec. -Butyl, pentyl, isopentyl, tert-pentyl, 1-methylpentyl, n-hexyl, isohexyl, cyclopropyl, cyclopentyl, cyclohexyl and the like.

Examples of the radical polymerization initiator used in the production method include azobisisobutyronitrile,
2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (methyl 2-methylpropionate), 2,2 ' Azo polymerization initiators such as -azobis (2,4-dimethyl-4-methoxyvaleronitrile),
For example, benzoyl peroxide, lauroyl peroxide, bis (4-tert-butylcyclohexyl) peroxydicarbonate, tert-butylperoxy-2-ethylhexanoate, ditert-butyl peroxide, tert-butylperoxybenzoate, Examples include peroxide-based polymerization initiators such as 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane. Examples of the living anionic polymerization initiator include n-butyllithium, sec-butyllithium, tert-butyllithium, naphthalene sodium, naphthalene potassium, cumyl potassium, and the like. When a living anionic polymerization initiator is used, the copolymer represented by the general formula [8] can be obtained as a monodisperse copolymer.

Examples of the chain transfer agent to be added as needed include mercaptans such as lauryl mercaptan, octyl mercaptan, butyl mercaptan, dodecyl mercaptan, 2-mercaptoethanol, and butyl thioglycolate.

As the organic solvent used in the reaction, in each case, for example, hydrocarbons such as benzene, toluene, xylene and cyclohexane, for example, ethyl acetate, n-acetic acid
Esters such as -butyl, for example, ethyl ether, 1,2-
Ethers such as dimethoxyethane, tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane, for example, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and the like.As the polymerization initiator, an azo polymerization initiator or a peroxide is used. When a system polymerization initiator is used, in addition to the organic solvent as described above, for example, alcohols such as ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, iso-butanol and tert-butanol Can also be used. In addition, it is preferable to use these organic solvents which were dried.

Examples of the inert gas include nitrogen gas, argon gas and the like.

Next, the copolymer represented by the above general formula [8] is mixed with a solvent in an appropriate solvent in the presence of an alkaline substance.
The mixture is stirred and reacted at 100100 ° C. for 0.5 to 20 hours. After the reaction, the polymer of the present invention represented by the general formula [1] can be obtained by performing post-treatment according to a conventional method for obtaining a polymer.

The reaction solvent includes water, for example, alcohols such as ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, iso-butanol and tert-butanol.

Examples of the alkaline substance include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and quaternary ammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide. Can be

As the starting material, the monomer represented by the above general formula [5] may be prepared, for example, as follows. That is, first, commercially available pyruvic acid and an arbitrary amount of the general formula [9]

[0050]

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(Wherein R ⁶ is the same as above) in the presence of a catalytic amount of an acid such as sulfuric acid, p-toluenesulfonic acid, phosphoric acid, hydrochloric acid, oxalic acid, etc. The reaction is carried out in an organic solvent such as benzene, toluene, xylene, ethyl acetate, methyl isobutyl ketone, cyclohexane or the like at 50 to 150 ° C. for 0.5 to 20 hours without solvent. After the reaction, a post-treatment is carried out in accordance with a conventional method usually used in this field to obtain a compound represented by the general formula [10]:

[0052]

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(Wherein R ⁶ is the same as described above).

Next, the pyruvate obtained as described above is combined with an acid anhydride such as acetic anhydride, propionic anhydride, benzoic anhydride or the like, or acetyl chloride, acetyl bromide, propanoyl chloride, benzoyl chloride or the like. The acid halide is used in the absence of a catalyst or in the presence of a catalytic amount of, for example, pyridinium p-toluenesulfonate, for example, benzene, toluene, n-hexane, ethyl acetate, acetone, methyl ethyl ketone, 1,4-dioxane, 1,3 The reaction is carried out at 30 to 150 ° C. for 1 to 20 hours in the presence of a basic substance such as triethylamine, diethylamine, pyridine, piperidine or γ-collidine in a solvent such as -dioxolane or cyclohexane. After the reaction, a post-treatment is carried out in accordance with a conventional method usually used in this field to obtain the above-mentioned general formula [5]
Can be obtained.

Further, the monomer represented by the general formula [6] is a compound represented by the general formula [11]:

[0056]

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[0057] (wherein, R ⁹ represents a lower alkyl group, R ⁷
Is the same as above. ) And any amount of formaldehyde in the presence of a basic substance such as potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, triethylamine, piperidine, etc. In a solvent such as ethanol, n-propanol, isopropanol, acetone, etc.
The mixture is stirred and reacted at 85 ° C. for 0.5 to 20 hours. After the reaction, a post-treatment is carried out according to a conventional method generally used in this field to obtain a compound represented by the general formula [12]:

[0058]

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(Wherein R ⁷ is the same as described above).

Next, the α-hydroxymethyl acrylate obtained as described above and an arbitrary amount of, for example, thionyl chloride, thionyl bromide, phosphorus trichloride, phosphorus tribromide, phosphorus pentachloride, phosphorus oxychloride And a halogenating agent such as phosphorus oxybromide in a solvent free or in a solvent such as ethyl ether, isopropyl ether, benzene, toluene, n-hexane, methylene chloride, 1,2-dichloroethane, etc. ~
Incubate for 20 hours. After the reaction, a post-treatment is carried out according to a conventional method usually used in this field to obtain a compound of the general formula [1]
3]

[0061]

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(In the formula, X represents a halogen atom, and R ⁷ is the same as described above.) Α-chloromethyl acrylate can be obtained.

In the general formula [13], examples of the halogen atom represented by X include fluorine, chlorine, bromine and iodine.

Further, α-chloromethyl acrylate and an optional amount of the general formula [14]

[0065]

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(Wherein R ³ and R ⁴ are the same as described above) and an alcohol compound represented by the following formula: in the presence of a basic substance such as triethylamine, diethylamine, pyridine, piperidine or morpholine, for example, benzene, toluene, Ethyl acetate, ethyl ether, tetrahydrofuran, dimethoxyethane, methylene chloride, N, N-dimethylformamide, N, N-dimethylacetamide
React at ~ 100 ° C for 0.5-20 hours. After the reaction, the monomer represented by the above general formula [6] can be obtained by performing post-treatment according to a usual method usually performed in this field.

Further, the monomer represented by the above general formula [7] is a commercially available acrylic acid and its ester, methacrylic acid and its ester, α-trifluoromethyl acrylate or the above general formula [12]. α-Hydroxymethyl acrylate and the like are used.

The molecular weight of the polymer represented by the general formula [1] according to the present invention is not particularly limited. For example, when the polymer is used as a binder for an antireflection film material, the preferred range is polystyrene. The molecular weight determined by a GPC (gel permeation chromatography) measurement method using the standard as a weight average molecular weight is about 1,000 to 50,000, more preferably 1,000 to 30,000.
And the ratio (dispersion degree) between the weight average molecular weight and the number average molecular weight is usually 1 to 3, but is more preferably in the range of 1 to 2 which enables more uniform film formation.

The anti-reflective coating material of the present invention is mainly composed of a water-soluble polymer represented by the above general formula [1] and a solvent, and various additives may be added as necessary as long as the desired effect is not impaired. Agents can be used. Examples of the additive include a water-soluble polymer other than the polymer represented by the general formula [1], an alkali-soluble polymer, and a surfactant.

As the water-soluble polymer and the alkali-soluble polymer other than the polymer represented by the general formula [1] used as the additive according to the present invention, the water-solubility of the anti-reflective coating material can be improved by adding it. It can increase the dissolution rate in an alkali developer, and specific examples thereof include, for example, polyvinyl alcohol, polyacrylic acid,
Examples thereof include, but are not limited to, poly (p-hydroxystyrene), polyethylene glycol, styrene / maleic anhydride copolymer and / or hydrolyzate thereof. The water-soluble polymer and the alkali-soluble polymer may be used alone or in any combination of two or more, and the amount of use (the total amount of two or more) may be used. The amount is usually 20 parts by weight or less, preferably 10 parts by weight or less based on 100 parts by weight of the aqueous polymer of the present invention.

The surfactant is used for the purpose of improving the coating performance, striation, and wettability of the anti-reflective coating material, and has the effect of lowering the refractive index of the anti-reflective coating. Any surfactant can be used as long as it does not corrode the device manufacturing equipment. Examples thereof include polyoxyethylene nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, polyoxyethylene lauryl ether, and polyoxyethylene lauryl ether. Nonionic surfactants such as oxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene octyl phenyl ether are usually preferably used, and among them, fluorine-containing nonionic surfactants are more preferably used. Such commercially available fluorine-containing nonionic surfactants include:
For example, Florard (trade name, Sumitomo 3M), Surflon (trade name, Asahi Glass), Unidyne (trade name, Daikin Industries), Megafac (trade name, Dainippon Ink), Ftop (trade name, Tochem) Products), but are not limited to these. In addition, various surfactants other than the nonionic surfactants as described above, that is, cationic surfactants, fluorine-containing cationic surfactants, anionic surfactants, and fluorine-containing anionic surfactants Naturally, any kind can be used as long as it satisfies the requirements as described above.
These surfactants may be used alone or in any combination of two or more kinds, and the amount of the surfactant used is based on 100 parts by weight of the water-soluble polymer of the present invention. It is usually at most 100 parts by weight, preferably at most 50 parts by weight, particularly preferably at most 25 parts by weight.

As the solvent used in the antireflection film material of the present invention, it is particularly important that the antireflection film material does not mix with the lower layer film (resist film) at the interface between the lower layer film and the solvent which usually does not dissolve the resist film. As the additive, for example, when a fluorine-based surfactant or the like is used as an additive, water is used as a main solvent for the purpose of improving the solubility, for example, ethanol, n-propanol, isopropanol, 2 It is also possible to use a mixture of alcohols such as -methoxyethanol, ethylene glycol, propylene glycol and the like. The proportion of these alcohols used is such that they do not mix at the interface with the underlying resist film.
0% by weight or less is desirable. The total amount of these solvents is 2 to 199 parts by weight, assuming that the total amount of the polymer of the present invention and other additives is 1 part by weight, but 4 to 100 parts by weight is more preferable.

In the pattern forming method of the present invention, the resist used for forming the resist pattern is not particularly limited, and can be appropriately selected according to the purpose of use of the resist. These resist agents include a dissolution-inhibiting positive resist agent composed of a novolak resin and a naphthoquinonediazide derivative, a dissolution-inhibiting negative resist agent composed of an alkali-soluble polymer and a crosslinking agent, and a polyvinylphenol-based alkali-soluble polymer. A chemically amplified positive resist comprising an acid generator, a chemically amplified negative resist comprising an alkali-soluble polymer, a crosslinking agent and an acid generator are exemplified.

In order to form a resist pattern using the antireflection coating material of the present invention, for example, the following may be performed. That is, for example, a chemically amplified positive resist agent having a thickness of 0.5 to 2.0 on a semiconductor substrate such as a silicon wafer.
Apply to a thickness of about μm, and apply this in an oven to 70-130
° C, 10-30 minutes, or 70-130 on a hot plate
C., pre-baking for 1 to 2 minutes to form a resist film, and the anti-reflective coating material of the present invention having a thickness of 30 to
Apply to a thickness of about 1000 Å. In this case, as the thickness of the antireflection film approaches an odd multiple of λ / 4n (where λ represents the wavelength of the radiation and n represents the refractive index of the antireflection film), the reflection at the interface of the resist film surface layer is increased. Great effect of prevention. Further, since the antireflection film material of the present invention is not mixed with the resist film, it does not impair the resist pattern shape at the time of development. Next, a mask for forming a target pattern is held over the resist film, and for example, X-rays such as ultraviolet rays of 400 nm or less, far ultraviolet rays, electron beams or synchrotrons.
After selectively irradiating radiation such as radiation, baking is performed on a hot plate at 70 to 150 ° C. for 1 to 2 minutes. Furthermore, 0.1-5%
Using a developing solution such as an aqueous solution of tetramethylammonium hydroxide (TMAH), develop for about 0.5 to 3 minutes by a conventional method such as a dipping method, a puddle method, a spray method, and then wash with water. Then, a desired resist pattern is formed on the substrate. In this case, since the antireflection film of the present invention is easily dissolved in an alkali developing solution, it is completely removed together with the resist film in the exposed area during development. Therefore, since a step of performing a peeling treatment before development is not required, the step can be simplified.

Examples of the developer used for forming the resist pattern according to the present invention include organic amines such as tetramethylammonium hydroxide (TMAH), choline and triethanolamine, and inorganic alkalis such as NaOH and KOH. An aqueous solution containing compounds and the like is included, and the concentration is 0.1 to 5% by weight. Also, in these developers, for example, water-soluble alcohols such as methanol and ethanol,
Surfactants can be added as needed.

Hereinafter, the present invention will be described in more detail with reference to Examples, Reference Examples and Comparative Examples, but the present invention is not limited by these. The polymer and the acid generator for the resist used in Examples and Comparative Examples are described in, for example, Japanese Patent Application Laid-Open No. H4-211258 (US Pat. No. 5,350,
No. 660, European Patent No. 0,440,374), JP-A-4-210960
Gazette (US Pat. No. 5,216,135, European Patent 0,440,375)
JP-A-5-249682 (US Pat. No. 5,468,589)
No .: European Patent Publication No. 0,520,642) and the like.

[0077]

【Example】

Reference Example 1. Synthesis of methyl α-acetyloxyacrylate 102.1 g (1 mol) of methyl pyruvate was added to acetic anhydride 204.2
g (2 mol), 5.0 g (20 mmol) of pyridinium p-toluenesulfonate was added, and the mixture was stirred and reacted at 100 to 110 ° C for 7 hours. Then, the mixture was stirred and refluxed for 11 hours.
After completion of the reaction, the reaction solution was poured into 5 L of water, and the oily substance was extracted with ethyl ether. The organic layer was washed with water and dried over anhydrous magnesium sulfate. The solvent was concentrated, and the residue was distilled under reduced pressure to obtain 50.0 g of a target methyl α-acetyloxyacrylate of a bp. 65 to 68 ° C./11 mmHg fraction, 50.0 g. ¹ H NMR δ ppm (CDCl ₃ ): 2.24 (3H, s, CH ₃ CO), 3.
81 (3H, s, COOCH ₃ ), 5.48 and 6.05 (1H, d, J = 1.46Hz,
CH ₂ = C-).

Reference Example 2 Synthesis of ethyl α-2,2,2-trifluoroethyloxymethyl acrylate (1) Synthesis of ethyl α-hydroxymethyl acrylate 179.2 g (0.8 mol) of triethyl phosphonoacetate and 37
284.7 g (3.5 mol) of a 60% aqueous formaldehyde solution in water 60
A solution of 192 g of potassium carbonate in 210 ml of water was added dropwise at 30 ° C. or lower, and the mixture was stirred and reacted at 30 ± 2 ° C. for 3 hours. After completion of the reaction, 300 L of a saturated aqueous solution of ammonium chloride was poured into the reaction solution, and ethyl ether (100 L ×
Extracted in 3). The organic layer was separated, washed with water (100 L), and dried over anhydrous magnesium sulfate. The solvent was concentrated, and 91 g of the obtained oil residue was distilled under reduced pressure to obtain a bp.
There was obtained 70.0 g of a target colorless oily substance of ethyl α-hydroxymethyl acrylate at -95 ° C / 10 mmHg fraction. _{^{1 HNMR δppm (CDCl 3):}} 1.31 (3H, t, J = 7Hz, COOCH 2
CH ₃ ), 2.77 (1H, brs, OH), 4.24 (2H, q, J = 7Hz, COOCH ₂ C
_{H 3), 4.32 (2H,} brs, CH 2 OH), 5.85 and 6.26 (each 1H, s,
CH ₂ = C-). IR λcm ^-1 (KBr tablet): 3542 (OH), 1731 (COO).

(2) Synthesis of ethyl α-chloromethyl acrylate 69 g (0.53 mol) of ethyl α-hydroxymethyl acrylate obtained in the above (1) was treated with 69.3% of thionyl chloride in a nitrogen stream.
g (0.58 mol) was added dropwise at 10 ° C or lower. Then, the mixture was heated with stirring and reacted under stirring for 2 hours under reflux. After the completion of the reaction, the solvent was concentrated, and 70 g of a pale yellow oily residue was distilled under reduced pressure to obtain 65.5 g of a target α-chloromethyl ethyl acrylate colorless oily matter at a bp of 80 to 85 ° C./20 mmHg fraction. Obtained. _{^{1 HNMR δppm (CDCl 3):}} 1.37 (3H, t, J = 7Hz, COOCH 2
CH ₃ ), 4.31 (2H, q, J = 7 Hz, COOCH ₂ CH ₃ ), 4.34 (2H, s, CH
₂ Cl), 6.02 and 6.42 (1H, s, CH ₂ = C-, respectively). IR λcm ^-1 (KBr tablet): 1724 (COO).

(3) Synthesis of ethyl α-2,2,2-trifluoroethyloxymethyl acrylate 95% 2,2,2-trifluoroethanol 46.6 g (0.44 mol), tetrahydrofuran 266 ml and triethylamine
After mixing 44.8 g, 63.3 g (0.43 mol) of ethyl α-chloromethyl acrylate obtained in the above (2) was added dropwise at 30 ° C. or lower, and the mixture was stirred and reacted at 55 to 60 ° C. for 4 hours. After completion of the reaction, the mixture was cooled to 25 ° C., the precipitated crystals were separated by filtration, and the filtrate was concentrated.
The residue was dissolved in 100 ml of methylene chloride, washed once with 100 ml of water, and dried over anhydrous magnesium sulfate. The solvent was concentrated, and 86 g of the residual brown oil was distilled under reduced pressure to obtain a bp.
There was obtained 65.5 g of a target colorless oily substance of ethyl α-2,2,2-trifluoroethyloxymethyl acrylate at 75 ° C./15 to 17 mmHg fraction. _{^{1 HNMR δppm (CDCl 3):}} 1.31 (3H, t, J = 7Hz, COOCH 2
CH ₃ ), 3.89 (2H, q, J = 8.5Hz, OCH ₂ CF ₃ ), 4.24 (2H, q, J
= 7Hz, COOCH ₂ CH ₃ ), 4.36 (2H, s, -CH ₂ O-CH ₂ CH ₃ ), 5.89
And 6.36 (each _{1H, s, CH 2 = C-} ). IR λcm ^-1 (KBr tablet): 1716 (COO).

Embodiment 1 Synthesis of poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethyl acrylate) (1) Poly (α-methyl methyl acrylate / α-hydroxy)
Synthesis of 2,2,2-trifluoroethyloxymethyl acrylate) methyl α-acetyloxyacrylate obtained in Reference Example 8.
2 g (56.9 mmol) of α-2,2,2 obtained in (3) of Reference Example 2
Ethyl 2-trifluoroethyloxymethyl acrylate
A mixture of 2.0 g (9.4 mmol) and 35 ml of toluene was heated to 85 ° C. in a nitrogen stream, and a catalytic amount of V-601 [methyl 2,2′-azobis (2-methylpropionate) Wako Pure Chemical Industries ( Stock name. ] Is added dropwise at 85 ° C to a solution of toluene (10 ml).
The polymerization reaction was carried out at the same temperature for 5 hours. After completion of the reaction, the reaction solution was cooled to 25 ° C., and the reaction solution was mixed with isopropanol / n-hexane (10%).
0 ml / 400 ml), and the precipitated crystals were collected by filtration, dried under reduced pressure, and then dried at a desired poly (α-acetyloxymethyl acrylate / α-2,2,2-trifluoroethyloxymethyl acrylate). 8.4 g of white powdery crystals were obtained. The composition ratio of α-acetylmethyl acrylate units and α-2,2,2-trifluoroethyloxymethylmethylacrylate units in the obtained polymer was about 85:15 from ¹ HNMR measurement. GPC (gel permeation chromatography) measurement using polystyrene as a standard revealed that the weight average molecular weight (Mw) was about 6,600, and the ratio between the weight average molecular weight and the number average molecular weight (dispersion degree: Mw / Mn) was 1.90. . ¹ H NMR δ ppm (DMSO-d ₆ ): 0.94 to 1.39 (m, COOCH ₂ C
H ₃ , -CH ₂ -C- × 2), 1.74 to 2.26 (brs, OCOCH ₃ ), 2.63 to
_{4.27 (m, OCH 2 CF 3} , OCOCH 3, -CH 2 -OCH 2 CF 3).

(2) Poly (α-hydroxyacrylic acid)
Synthesis of α-2,2,2-trifluoroethyloxymethylacrylic acid) Poly (α-acetyloxyacrylate) / α-2,2,2-trifluoroethyloxymethylacrylate obtained in (1) above Ethyl) 7.8 g, ethanol 30 ml and water 30 ml
Was mixed, 60 g of a 15% aqueous solution of tetramethylammonium hydroxide was injected, and the mixture was stirred and reacted at 75 ° C. for 4 hours. After completion of the reaction, the solvent was distilled off, and the residue was passed through a column packed with 250 g of ion exchange resin (Amberlite IR-120B). The eluate was concentrated under reduced pressure, and the viscous oily residue was dried under reduced pressure. As a result, 4.5 g of white powdery crystals of the desired poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid) were obtained. The composition ratio of α-hydroxyacrylic acid units and α-2,2,2-trifluoroethyloxymethylacrylic acid units in the obtained polymer was about 85:15 by ¹ HNMR measurement. Mw about 4,30
0, Mw / Mn = 1.83 (GPC method: polystyrene standard). ¹ H NMR δ ppm (DMSO-d ₆ ): 0.81 to 1.32 (m, -CH ₂ -C-
× 2), 1.54 to 4.32 (m, CH ₂ —OCH ₂ CF ₃ , COOH × 2, OH).

Embodiment 2 FIG. Synthesis of poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid / α-hydroxymethylacrylic acid) (1) Poly (methyl α-acetyloxyacrylate / α-
Synthesis of ethyl 2,2,2-trifluoroethyloxymethyl acrylate / α-hydroxymethyl acrylate) Methyl α-acetyloxy acrylate obtained in Reference Example 5.
7 g (39.5 mol), 2.6 g of ethyl α-2,2,2-trifluoroethyloxymethyl acrylate obtained in (3) of Reference Example 2
(12.3 mol) and 1.3 g (10.0 mol) of ethyl α-hydroxymethyl acrylate obtained in (1) of Reference Example 2 and 40 ml of isopropanol were mixed, and heated to 70 ° C. in a nitrogen stream to obtain a catalytic amount of V. -65 [2,2'-azobis (2,4-dimethylvaleronitrile). Wako Pure Chemical Industries, Ltd. product name. ] And drops 70
The mixture was stirred and reacted at 7575 ° C. for 4 hours. After the reaction is completed,
After cooling to 25 ° C. and pouring into 500 ml of n-hexane, the precipitated crystals are collected by filtration and dried under reduced pressure to obtain the desired poly (methyl α-acetyloxyacrylate / α-2,2,2-trifluoroethyl). Ethyl oxymethyl acrylate / ethyl α-hydroxymethyl acrylate) 8.8 g of slightly yellow powdery crystals were obtained. The composition ratio of α-acetylmethyl acrylate units, α-2,2,2-trifluoroethyloxymethyl acrylate units and α-hydroxymethyl acrylate units in the obtained polymer was about 13 based on ¹ H NMR measurement. : 4: 3
Met. Mw: about 7,800, Mw / Mn = 1.75 (GPC method: polystyrene standard).

(2) Synthesis of poly (methyl α-hydroxyacrylate / α-2,2,2-trifluoroethyloxymethyl acrylate / α-hydroxymethylacrylic acid) The reaction and reaction were carried out in the same manner as in (2) of Example 1 using 8.5 g of (α-acetyloxymethyl acrylate / α-2,2,2-trifluoroethyloxymethyl acrylate / ethyl α-hydroxymethyl acrylate). After the post-treatment, 4.8 g of the target poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid / α-hydroxymethylacrylic acid) was obtained as 4.8 g of light brown caramel-like crystals. . The composition ratio of α-hydroxyacrylic acid unit, α-2,2,2-trifluoroethyloxymethylacrylic acid unit and α-hydroxymethylacrylic acid unit in the obtained polymer was about 13: 4 from ¹ HNMR measurement.
: 3. Mw 5,000, Mw / Mn = 1.75 (GPC
Method: polystyrene standard).

Embodiment 3 FIG. Synthesis of poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid / methacrylic acid) (1) Poly (methyl α-acetyloxyacrylate / α-
Synthesis of 2,2,2-trifluoroethyloxymethyl acrylate / methyl methacrylate) 9.4 g (65.2 mmol) of poly (α-acetyloxy acrylate) obtained in Reference Example 1 and (3 5.3 g (25.0 mmol) of ethyl α-2,2,2-trifluoroethyloxymethyl acrylate obtained in), methyl methacrylate
1.0 g (10.0 mmol) and 40 ml of 1,4-dioxane were mixed, and the polymerization reaction and post-treatment were carried out in the same manner as (1) of Example 1 using a catalytic amount of V-601 to obtain the desired poly (α- (Methyl acetyloxyacrylate / α-2,2,2-trifluoroethyloxymethyl acrylate / methyl methacrylate) 13.3 g of slightly brown caramel-like crystals were obtained. The composition ratio of α-acetylmethyl acrylate units, α-2,2,2-trifluoroethyloxymethylethyl acrylate units and methyl methacrylate units in the obtained polymer was ¹
It was about 13: 5: 2 from 1 HNMR measurement. Mw about 5,20
0, Mw / Mn = 1.78 (GPC method: polystyrene standard).

(2) Poly (α-hydroxyacrylic acid /
Synthesis of α-2,2,2-trifluoroethyloxymethylacrylic acid / methacrylic acid) Poly (α-acetyloxymethyl acrylate / α-2,2,2-trifluoroethyloxy) obtained in (1) above Using 12.5 g of ethyl methyl acrylate / methyl methacrylate, the reaction and post-treatment were carried out in the same manner as in (2) of Example 1 to obtain the desired poly (α-hydroxyacrylic acid / α-2,2,2-triene). Fluoroethyloxymethylacrylic acid / methacrylic acid) 6.7
g of slightly brown carmel-like crystals were obtained. Α of the obtained polymer
The composition ratio of -hydroxyacrylic acid unit, α-2,2,2-trifluoroethyloxymethylacrylic acid unit and methacrylic acid unit was about 13: 5: 2 by ¹ HNMR measurement.
As a result of a GPC measurement using polystyrene as a standard, the weight average molecular weight was about 3,300 and the degree of dispersion was 1.70.

Embodiment 4 FIG. An antireflective coating material of the present invention having the following composition A and a chemically amplified positive resist material having the following composition X were prepared. [Composition A] Poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyl oxymethylacrylic acid) [Polymer of Example 1] 2.5 g Fluorine-containing nonionic surfactant: Unidyne DS-401 ( Daikin Industries, Ltd., trade name) 0.2g water 97.3g

[Composition X] Poly (p-1-ethoxyethoxystyrene / p-hydroxystyrene) 6.0 g Bis (1,1-dimethylethylsulfonyl) diazomethane 0.3 g Propylene glycol monomethyl ether acetate 23.7 g

The chemically amplified positive resist material having the composition X was spin-coated on 11 silicon wafers at different rotation speeds, and prebaked on a hot plate at 90 ° C. for 90 seconds to obtain a 0.89 to 1.01 μm A silicon wafer having a resist film thickness in the range was obtained. Then, an anti-reflective coating material having the above composition A was spin-coated on resist films of different thicknesses on each silicon wafer to form an anti-reflective coating having a thickness of about 450 angstroms. Further, using a KrF excimer laser stepper (NA 0.55), a Kr of 248.4 nm was used.
After selectively exposing F excimer laser light through a mask, post-baking is performed on a hot plate at 100 ° C. for 90 seconds, developed with an alkali developing solution (2.38% tetramethylammonium hydroxide aqueous solution) for 60 seconds, and then washed with water. As a result, a resist pattern was formed.

The dimensions of the 0.30 μm line and space pattern formed on each of the silicon wafers at the same exposure dose were measured by a scanning electron microscope. FIG. 1 shows the relationship (standing wave curve) between the actually measured line size and the resist film thickness. The maximum value of the dimensional variation was about 0.03 μm, which was within the practical range.

Comparative Example 1 A resist pattern was formed in the same manner as in Example 4 except that the antireflection film material of the present invention was not used, and the line dimensions were measured. FIG. 2 shows the relationship between the measured line size and the resist film thickness. In this case, the maximum value of the dimensional variation is about 0.10 μm, and the effect of the standing wave is too large, so that practical use is difficult.

As is clear from Example 4 and Comparative Example 1,
When the antireflection film material of the present invention is used, multiple reflection in the resist film is suppressed, and the effect of the standing wave is reduced. As a result, when the anti-reflection coating material was not used, the fluctuation in the effective sensitivity, which was too large and hindered the practical application, became small, and the practical use was allowed.

Embodiment 5 FIG. A chemically amplified positive resist material having the following composition Y was prepared. [Composition Y] Poly (p-1-ethoxyethoxystyrene / p-hydroxystyrene) 6.0 g biscyclohexylsulfonyldiazomethane 0.3 g propylene glycol monomethyl ether acetate 23.7 g

A method of forming a resist pattern using the antireflection coating material of the present invention composed of composition A and the chemically amplified positive resist material composed of composition Y described in Example 4 will be described with reference to FIG. A chemically amplified positive resist material 2 having the composition Y is spin-coated on a substrate 1 such as a semiconductor,
After pre-baking on a hot plate for 90 seconds, a resist material film having a thickness of 1.0 μm was obtained (FIG. 3A). Next, the antireflection film material 3 having the composition A was spin-coated on the resist film to obtain an antireflection film having a thickness of about 450 Å (FIG. 3B). Next, a KrF excimer laser stepper (NA
0.54) using a 248.4 nm KrF excimer laser beam 4
Was selectively exposed through a mask 5 (FIG. 3c). After post-baking on a hot plate at 100 ° C for 90 seconds, development with an alkaline developer (2.38% tetramethylammonium hydroxide aqueous solution) for 60 seconds, followed by washing with water to dissolve and remove the exposed portions of the antireflection film and the resist film. Thus, a positive pattern 2a was obtained (FIG. 3D). The obtained positive pattern has a 0.20 μm line and space (L /
It had the resolution performance of S), and the cross-sectional shape was a good rectangular shape from observation by a scanning electron microscope. The exposure amount at this time was 24 mJ / cm ² . Furthermore, the film loss of the unexposed area
It was less than 100 angstroms.

Comparative Example 2 A comparative antireflective coating material having the following composition B was prepared. [Composition B] Polyvinylpyrrolidone 1.2 g Ammonium perfluorooctanesulfonate 3.5 g Isopropanol 2.7 g Water 92.6 g

A resist pattern was formed in the same manner as in Example 5 using the chemically amplified positive resist material composed of Composition Y and the antireflection film material composed of Composition B described in Example 5, and a resist pattern of 24 mJ / cm ^{2 was obtained.} A positive pattern of 0.22 μm L / S was formed at the exposure amount of, but the cross-sectional shape was such that the surface layer of the resist film became round as shown in FIG. Further, the film loss of the unexposed portion was as large as 250 to 300 angstroms.

As is clear from Example 5 and Comparative Example 2,
When the antireflection film material of the present invention is used, the shape is good as a rectangular shape and the amount of film reduction in the unexposed portion is small as compared with the case of using the existing antireflection film material, and the problem is improved.

Embodiment 6 FIG. An antireflection coating material of the present invention having the following composition C and a chemically amplified positive resist material having the following composition Z were prepared. [Composition C] Poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid / α-hydroxymethylacrylic acid) [Polymer of Example 2] 2.8 g Fluorine-containing nonionic surfactant Agent: Unidyne DS-401 0.2g Water 97.0g

[Composition Z] poly (p-tert-butoxystyrene / p-hydroxystyrene) 6.0 g biscyclohexylsulfonyldiazomethane 0.3 g propylene glycol monomethyl ether acetate 23.7 g

A pattern was formed in the same manner as in Example 2 using the antireflection coating material having the composition C and the chemically amplified positive resist material having the composition Z. As a result, 25
A 0.30 μm L / S rectangular positive pattern was formed at an exposure dose of mJ / cm ² . After exposure for 3 hours, post-baking and development, a 0.30 μm L / S rectangular positive pattern was resolved.

Comparative Example 3 A pattern was formed in the same manner as in Example 6, except that the antireflection film material of the present invention was not used. As a result, 0.30 μm L / S at 25 mJ / cm ² exposure
Was formed. However, when post-baked after being left for 15 minutes from the exposure, the obtained pattern became T-Shape and had a poor shape. Also, 3
When post-baked after standing for 0 minutes, no pattern could be formed.

As is clear from Example 6 and Comparative Example 3,
When the surface anti-reflective coating material of the present invention is used, a standing time from exposure to heat treatment (post-bake) may be caused by an atmosphere of a basic substance or moisture in a lithography process peculiar to a chemically amplified resist material. The problem of so-called PED, in which a shape change and a dimensional change occur over time, has been overcome.

Embodiment 7 FIG. An antireflective coating material of the present invention having the following composition D was prepared. [Composition D] Poly (α-hydroxyacrylic acid / α-2,2,2-trifluoroethyloxymethylacrylic acid / methacrylic acid) [Polymer of Example 3] 2.5 g Fluorine-containing nonionic surfactant: Surflon S -145 (Asahi Glass Co., Ltd., trade name) 0.3 g isopropanol 2.0 g water 95.2 g

A pattern was formed in the same manner as in Example 5 using the antireflection film material having the composition D and the chemically amplified positive resist material having the composition Y described in Example 5. As a result, a good rectangular shape of 0.20 μm L / S was resolved at an exposure dose of 22 mJ / cm ² . Further, even when a metal piece of an iron-nickel alloy was brought into contact with the antireflection film material having the composition D at 25 ± 2 ° C. for 3 months, no corrosion such as rust was observed on the metal piece.

Comparative Example 4 A comparative antireflective coating material having the following composition E was prepared. [Composition E] Polyvinyl alcohol 2.0 g Perfluorooctanesulfonic acid 2.5 g Water 95.5 g

A pattern was formed in the same manner as in Example 5 using the antireflection film material having the composition E described above and the chemically amplified positive resist material having the composition Y described in Example 5. As a result, a pattern of 0.20 μm L / S was resolved at an exposure dose of 22 mJ / cm ² , but the cross-sectional shape was poor because the pattern had a rounded upper portion. Further, when a metal piece of an iron-nickel alloy was brought into contact with the antireflection film material having the composition E under the same conditions as in Example 7, rust was clearly observed.

As is clear from Example 7 and Comparative Example 4,
When the antireflection film material of the present invention is used, the pattern shape is rectangular and good as compared with the case where the existing antireflection film material is used. In addition, rust and corrosion are not recognized even when they come into contact with metal, and there is no fear of damaging various devices for manufacturing semiconductor elements.

[0108]

As is apparent from the above description, the polymer of the present invention is water-soluble despite having a fluorine atom in the molecule and has a property of being easily dissolved in an alkali developing solution. The anti-reflective coating material of the present invention using these polymers is a water-soluble and weakly acidic composition, and therefore, 1) does not mix with the resist film and its interface, and 2) has a basic property in the lithography process. The sensitivity change and PED problems are improved because they are not affected by substances or moisture. 3) Since they can be removed together with the resist film in the exposed area during development, the operation is not complicated. 4) The effects of standing waves can be suppressed or reduced. The device manufacturing method has an advantage such that the obtained pattern shape is rectangular even when compared with the recent technology utilizing perfluoroalkylsulfonic acid or perfluoroalkylcarboxylic acid or salts thereof. The advantages such as not corroding the metal used in the device are noted. Therefore, the present invention has great value for forming fine patterns in the semiconductor industry, for example.

[0109]

[Brief description of the drawings]

FIG. 1 shows a relationship between an actual measured line size and a film thickness obtained in Example 4 (the influence of a standing wave was suppressed).
It is a graph.

FIG. 2 is a graph showing a relationship between a measured line dimension value and a film thickness obtained in Comparative Example 1 (influence of a standing wave is large).

FIG. 3 is a process cross-sectional view of the pattern forming method obtained in Example 6.

FIG. 4 shows a good rectangular pattern shape observed in Example 5, Example 6, and Example 7.

FIG. 5 shows a poor pattern shape with a round surface layer observed in Comparative Examples 2 and 4.

FIG. 6 is a diagram showing a dimensional change (Post Exposure Degree) occurring with the lapse of time from exposure to heat treatment in Comparative Example 3.
lay: hereinafter abbreviated as PED), which is a poor pattern shape (T-Shape) observed at 15 minutes.

FIG. 7 is a cross-sectional view of a PED of Comparative Example 3, which was observed for 30 minutes and where a pattern could not be formed.

[0110]

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Chemically amplified positive resist material, 3 ... Anti-reflective coating material of the present invention, 4 ... Kr
F excimer laser beam, 5 ... mask, 2a ... resist pattern.

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[Procedure amendment]

[Submission date] May 27, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0071

[Correction method] Change

[Correction contents]

The surfactant is used for the purpose of improving the coating performance, striation, and wettability of the anti-reflective coating material, and has the effect of lowering the refractive index of the anti-reflective coating. Any surfactant can be used as long as it does not corrode the device manufacturing equipment. Examples thereof include polyoxyethylene nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, polyoxyethylene lauryl ether, and polyoxyethylene lauryl ether. Nonionic surfactants such as oxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene octyl phenyl ether are usually preferably used, and among them, fluorine-containing nonionic surfactants are more preferably used. Such commercially available fluorine-containing nonionic surfactants include:
For example, Florard (trade name, Sumitomo 3M), Surflon (trade name, Asahi Glass), Unidyne (trade name, Daikin Industries), Megafac (trade name, Dainippon Ink), Ftop (trade name, Tochem) Products), but are not limited to these. In addition, various surfactants other than the nonionic surfactants as described above, that is, cationic surfactants, fluorine-containing cationic surfactants, anionic surfactants, and fluorine-containing anionic surfactants Naturally, any kind can be used as long as it satisfies the requirements as described above.
These surfactants may be used alone or in any combination of two or more kinds, and the amount of the surfactant used is based on 100 parts by weight of the water-soluble polymer of the present invention. Usually 0.1 to 100 parts by weight , 0.1
It is preferably from 50 to 50 parts by weight , particularly preferably from 0.1 to 25 parts by weight .

Claims (5)

[Claims] 1. A compound of the general formula [1] [Wherein, R ¹ and n Rs each independently represent a hydrogen atom, a fluorine atom, an alkyl group or a fluorinated alkyl group (provided that at least one of R ¹ and n Rs is a fluorinated Represents an alkyl group.), N represents an integer of 1 to 3,
R ² represents a hydrogen atom, an alkyl group, a fluorinated alkyl group or a hydroxyalkyl group, k and j each independently represent a natural number, m represents 0 or a natural number (provided that 0.05 ≦
j / (k + j + m) ≦ 0.7 and 0 ≦ m / (k +
j + m) ≦ 0.7. ). ] The polymer shown by these. 2. The polymer according to claim 1, having a weight average molecular weight of 1,000 to 30,000. 3. In the general formula [1], 0.1 ≦ j / (k
+ J + m) ≦ 0.5 and 0 ≦ m / (k + j + m)
The polymer according to claim 1 or 2, wherein ≤ 0.5. 4. An anti-reflective coating material comprising the polymer represented by the general formula [1] according to claim 1. 5. A method for forming a resist pattern on a substrate, comprising: (1) applying a resist material on the substrate and then heating to form a resist film; and (2) forming a resist film on the resist film. 4. A step of applying the antireflection film material according to claim 3 to form a film, (3) irradiating radiation through a mask for forming a pattern, and heating as necessary, and (4) a developer. And forming a desired pattern by using the above method.