JP2001215731A - Resist developer and developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist developer which attains development in a relatively short development time even in the case of a practically allowable does of electron beams and gives an excellent pattern shape. SOLUTION: A mixed solvent comprising an aliphatic straight chain ether solvent or an aromatic ether solvent and a ketone solvent having >=5 carbon atoms is used as the resist developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing solution and a developing method for a resist used for manufacturing a photomask, and more particularly to a developing solution and a developing method for an electron beam resist used for forming a pattern by an electron beam. .

[0002]

2. Description of the Related Art A photomask is a component in which a pattern of an electronic circuit is formed of a light-shielding material on a transparent substrate, and is selectively irradiated with light on a substrate on which a resist film is formed by a photolithography technique. , An original used when projecting a pattern image of an electronic circuit. The photomask is, for example, a semiconductor element, a magnetic bubble memory element, a semiconductor integrated circuit (LSI), a liquid crystal display (L
CD) and printed circuit boards (PWB). In the photolithography technique, a material obtained by dissolving a photosensitive polymer material called a resist in an organic solvent is applied to a substrate having a layer to be processed formed on a surface thereof. Next, the organic solvent is evaporated by pre-baking to form a resist film. After partially irradiating the resist film with light, unnecessary portions of the resist film are dissolved and removed using a developing solution to form a resist pattern on the substrate. Next, the resist pattern is etched by immersing it in a solution of an acid or the like that dissolves the layer to be processed on the substrate. Finally, the unnecessary resist is removed. The photomask is used as an original for partially irradiating the resist film with light.

In many photomask manufacturing processes, a mask pattern is formed using an electron beam lithography system or a laser lithography system. A hard mask suitable for miniaturization will be described as an example. To manufacture a photomask, first, a light-shielding film made of a metal thin film is formed on a transparent substrate such as a transparent glass plate to prepare a mask substrate. Chromium is generally used as the metal thin film material. There is also a two-layer type in which a chromium oxide interference film is formed on a chromium metal film in order to reduce the reflectance of the chromium metal film.
A radiation-sensitive resist film is formed on the light-shielding film or the interference film on the mask substrate. Based on mask pattern data created in advance, an electron beam or laser beam is used to scan a resist film with an electron beam or laser beam to form a latent image of the pattern. Next, a resist pattern is formed by developing using a developing solution compatible with the used resist. This development utilizes a difference in solubility or a difference in dissolution rate between an exposed portion and a non-exposed portion in a developer. After the development, the light shielding film is etched. The etching of the metal chromium film is performed by wet etching or dry etching.
As an etchant used for wet etching, an aqueous solution of ceric ammonium nitrate is generally used. As a gas used for dry etching, a mixed gas of chlorine and oxygen is generally used. After the etching, the unnecessary resist film is removed. As a result, a photomask in which an electronic circuit pattern (mask pattern) made of a light-shielding film is formed on a transparent substrate is obtained.

In the photomask manufacturing process described above,
The developing method will be described in more detail. As a developing method, a method of immersing the substrate in a bath filled with the developer (dip method), a method of spraying the developer on the substrate (spray method), and a method of applying the developer using the surface tension of the substrate are used. A method of mounting on a surface (paddle method) is generally used. Of these methods, the most commonly used method at present is the spray method. In the case of the spray method, unlike other methods, the developer must be continuously sprayed during the development, so that a large amount of the developer is required for long-term development. If the development can be performed in a short time, the amount of the developer used can be reduced, the cost reduction effect can be obtained, and the burden on the environment can be reduced.

At present, it is said that the allowable amount of electron beam irradiation when considering productivity is 10 μC / cm ² or less. A developer for a resist material is disclosed in
In 292141, in order to form a fine pattern,
As a developing solution for a resist material containing an α-methylstyrene-based polymer, a mixed solvent of a good solvent for the copolymer and a cyclic solvent having 4 to 6 membered rings and a poor solvent for the copolymer is used. It has been proposed. But,
When this developer is used, the amount of electron beam irradiation is 10 μC / c.
To obtain the desired pattern in m ² or less, a very long development time (450-600 seconds) is required.

Japanese Patent Application Laid-Open No. 61-249049 discloses a developing solution for a positive radiation resist material containing a copolymer having an α-methylstyrene unit and a (meth) acrylate unit. It has been proposed to use Although many developers are proposed here, only isoamyl acetate can be used in a resist material containing α-methylstyrene / fluorinated acrylic acid ester resin at 10 μC with a relatively short developing time of 90 seconds. It is shown that a sensitivity of / cm ² or less can be obtained. JP-A-3-132760 discloses that α-
As a developer for a resist material containing a copolymer of methylstyrene and α-methyl methyl acrylate, it has been proposed to use a hydrocarbon-based solvent or a ketone-based solvent, and when using methyl ethyl ketone or methyl isobutyl ketone, A relatively short development time of 120 seconds or less has been achieved, despite a practically acceptable amount of electron beam irradiation.

[0007]

However, as a result of experiments by the present inventors, the pattern obtained using isoamyl acetate, methyl ethyl ketone or methyl isobutyl ketone swells, and a good pattern cannot be obtained. It turns out. Based on such prior art, the inventors have conducted intensive studies to obtain a developing solution which can be developed in a relatively short developing time and has an excellent pattern shape while having a practically acceptable amount of electron beam irradiation. An aliphatic linear ether-based solvent or an aromatic ether-based solvent as a resist developer for developing a resist material containing a copolymer of a styrene monomer and an acrylic monomer, The inventors have found that the above problems can be achieved with a resist developer containing 5 or more ketone solvents, and have completed the present invention based on this finding.

[0008]

According to the present invention, there is provided a resist developer for developing a resist material containing a copolymer of a styrene monomer and an acrylic monomer, comprising Provided is a resist developer containing a group III linear ether solvent or aromatic ether solvent and a ketone solvent having 5 or more carbon atoms.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (1) Resist Material The resist material contains a copolymer of a styrene monomer and an acrylic monomer, and is suitable for pattern formation by electron beam irradiation. The structural unit ratio (on a molar basis) of the copolymer is the ratio of structural units derived from a styrene monomer /
80/20 to 20 in structural units derived from acrylic monomers
/ 80, preferably 75/25 to 25/75, more preferably 70/30 to 30/70.

The styrene monomer is a monomer having a styrene structure. Specific examples thereof include styrene, 4-methylstyrene, 4-propylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-isobutylstyrene, Styrene, such as 4,4-dimethylstyrene, 4-ethyl-3-methylstyrene, 4-hydroxystyrene, 4-hydroxy-3-methylstyrene, and 4-methoxystyrene, a 4-substituted product thereof, or a 3-, 4-substituted product thereof; α-methylstyrene, 4-methyl-α-methylstyrene, 4-propyl-α-methylstyrene, 4-isopropyl-α-methylstyrene, 4-butyl-α-methylstyrene, 4-isobutyl-α-methylstyrene, 3,
4-dimethyl-α-methylstyrene, 4-ethyl-3-
Α-methylstyrene such as methyl-α-methylstyrene, 4-hydroxy-α-methylstyrene, 4-hydroxy-3-methyl-α-methylstyrene, 4-methoxy-α-methylstyrene, a 4-substituted product thereof, or Part 3
4-position substituent;

Α-chlorostyrene, 4-methyl-α-chlorostyrene, 4-propyl-α-chlorostyrene,
-Isopropyl-α-chlorostyrene, 4-butyl-α
-Chlorostyrene, 4-isobutyl-α-chlorostyrene, 3,4-dimethyl-α-chlorostyrene, 4-ethyl-3-methyl-α-chlorostyrene, 4-hydroxy-α-chlorostyrene, 4-hydroxy- 3-methyl-
α-chlorostyrene such as α-chlorostyrene and 4-methoxy-α-chlorostyrene, a 4-substituted product thereof, or a 3- and 4-substituted product thereof; and the like.

Of these, α-methylstyrene compounds (α-methylstyrene, 4-substituted products thereof, or 3-, 4-substituted products thereof) are particularly preferred in that they give good pattern shapes.

The acrylic monomer is an acrylic acid derivative, and specific examples thereof include methyl (meth) acrylate,
(Meth) alkyl acrylates such as ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and butyl (meth) acrylate; phenyl (meth) acrylate, 4- (meth) acrylate Aryl (meth) acrylates such as chlorophenyl; benzyl (meth) acrylate, 3,4- (meth) acrylate
Aralkyl (meth) acrylate such as dimethylbenzyl; α-halo such as α-methyl chloroacrylate, ethyl α-chloroacrylate, propyl α-bromoacrylate, isopropyl α-chloroacrylate, and butyl α-bromoacrylate Alkyl acrylate; aryl α-haloacrylate such as phenyl α-chloroacrylate;
Benzyl bromoacrylate, α-chloroacrylate 3,
Aralkyl α-haloacrylates such as 4-dimethylbenzyl;

Methyl α-cyanoacrylate, ethyl α-cyanoacrylate, propyl α-cyanoacrylate, α
Α-alkyl cyanoacrylates such as isopropyl cyanoacrylate and butyl α-cyanoacrylate; aryl α-cyanoacrylates such as phenyl α-cyanoacrylate; benzyl α-cyanoacrylate, and α-cyanoacrylate 3, Α-aralkyl cyanoacrylates such as 4-dimethylbenzyl; substitutionable acrylonitriles such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-bromoacrylonitrile; acrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N-phenyl N- such as acrylamide
Substitutable acrylamide; N-substituted methacrylamide such as methacrylamide, N-methylmethacrylamide, N, N-dimethylmethacrylamide, N-phenylmethacrylamide; α-chloroacrylamide, α-bromoacrylamide, N-methyl-α -Chloroacrylamide, N, N-dimethyl-α-chloroacrylamide,
Examples thereof include N-substituted α-haloacrylamides such as N-phenyl-α-chloroacrylamide.

Among them, α is high in sensitivity.
A haloacrylate compound such as an alkyl-haloacrylate, an aryl α-haloacrylate, or an aralkyl α-haloacrylate is preferred, and an alkyl α-haloacrylate is particularly preferred. Those containing no fluorine atom are advantageous for obtaining a good pattern.

The copolymer can be obtained by solution polymerization, bulk polymerization, suspension polymerization, or emulsion polymerization of each of the above monomers so as to form a polymer in the ratio of each of the above structural units. The weight average molecular weight of the copolymer is not particularly limited, but the weight average molecular weight in terms of polystyrene (hereinafter sometimes referred to as Mw) calculated by gel permeation chromatography using tetrahydrofuran is from 50,000 to 1,000. Is preferred.

In general, a resist material is obtained by dissolving the above copolymer in an organic solvent such as methyl phenyl ether, diethylene glycol dimethyl ether, o-dichlorobenzene and the like, and if necessary, additives such as a surfactant. Can be included. A resist material is prepared by dissolving all the components such as the copolymer in the organic solvent and, if necessary, filtering the solution using a membrane filter or the like.

(2) Developer The developer of the present invention comprises at least one kind of an aliphatic linear ether solvent or an aromatic ether solvent (hereinafter sometimes collectively referred to as an ether solvent) and at least one solvent. It is a mixed solvent of various ketone solvents having 5 or more carbon atoms. Examples of the aliphatic linear ether-based solvent, aromatic ether-based solvent, and ketone-based solvent having 5 or more carbon atoms (hereinafter, may be simply referred to as ketone-based solvent) include the following solvents.

Aliphatic linear ether solvents: diethyl ether, di-n-propyl ether, di-n-butyl ether, di-n-pentyl ether, di-n-hexyl ether, di-n-heptyl ether, di-n-heptyl ether Dialkyl ethers such as -n-octyl ether, di-n-nonyl ether and di-n-decyl ether; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether , Ethylene glycol di-n-pentyl ether, ethylene glycol di-n-hexyl ether, ethylene glycol di-n-heptyl ether, ethylene glycol di-
ethylene glycol dialkyl ethers such as n-octyl ether, ethylene glycol di-n-nonyl ether, ethylene glycol di-n-decyl ether;
Diethylene glycol dimethyl ether (diglyme), diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, diethylene glycol di-n-pentyl ether, diethylene glycol di-n-hexyl ether, diethylene glycol di-
n-Peptyl ether, diethylene glycol di-n-
Diethylene glycol dialkyl ethers such as octyl ether, diethylene glycol di-n-nonyl ether and diethylene glycol di-n-decyl ether;

Triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol di-n-propyl ether, triethylene glycol di-n-butyl ether, triethylene glycol di-n-pentyl ether, triethylene glycol di-n- Triethylene glycol dialkyl ethers such as hexyl ether, triethylene glycol di-n-heptyl ether, triethylene glycol di-n-octyl ether, triethylene glycol di-n-nonyl ether, and triethylene glycol di-n-decyl ether And the like. Among these, diethylene glycol dialkyl ethers are preferable from the viewpoint of shortening the development time, and diethylene glycol dialkyl ether having 1 to 5 carbon atoms in the alkyl portion is particularly preferable.

Aromatic ether solvents: methyl phenyl ether (anisole), ethyl phenyl ether, n-
Propyl phenyl ether, isopropyl phenyl ether, n-butyl phenyl ether, isobutyl phenyl ether, s-butyl phenyl ether, t-butyl phenyl ether, n-pentyl phenyl ether, isopentyl phenyl ether, 3-methylbutyl phenyl ether, n- Alkylphenyl ethers such as hexylphenyl ether, cyclohexylphenylether, n-pentylphenylether, n-octylphenylether, n-nonylphenylether and n-decylphenylether; aralkylphenylethers such as benzylphenylether; diphenylether and the like Diaromatic ethers; and the like.
Among these, alkylphenyl ether is preferable from the viewpoint of shortening the development time, and the alkyl moiety has 1 to 1 carbon atoms.
5 alkylphenyl ethers are particularly preferred.

Ketone solvents having 5 or more carbon atoms: 2-pentanone, 3-pentanone, cyclopentanone, 3-methyl-2-butanone, 2-hexanone, 3-hexanone, cyclohexanone, 4-methyl-2-pentanone, 2-methyl-3-pentanone, 3-methyl-2-pentanone,
3,3-dimethyl-2-butanone, 2-heptanone, 3
-Heptanone, 4-heptanone, 5-methyl-2-hexanone, 5-methyl-3-hexanone, 2-methyl-3
-Hexanone, 4-methyl-2-hexanone, 4-methyl-3-hexanone, 3-methyl-2-hexanone,
-Ethyl-2-pentanone,

3,4-dimethyl-2-pentanone, 4,
4-dimethyl-2-pentanone, 2,2-dimethyl-3
-Pentanone, 2,4-dimethyl-3-pentanone,
3,3-dimethyl-2-pentanone, 2-octanone,
3-octanone, 4-octanone, 2-nonanone, 3-
Nonanone, 4-nonanone, 5-nonanone, 2-decanone, 3-decanone, 4-decanone, 5-decanone, methylphenylketone, ethylphenylketone, n-propylphenylketone, isopropylphenylketone, methylbenzylketone, ethylbenzyl Examples include ketone, n-propylbenzyl ketone, isopropylbenzylketone, methylcyclohexylketone, ethylcyclohexylketone, n-propylcyclohexylketone, isopropylcyclohexylketone, diphenylketone, dibenzylketone, dicyclohexylketone, and the like. Among them, those having 5 to 10 carbon atoms are preferable, and those having 5 to 7 carbon atoms are more preferable. When the number of carbon atoms is 4 or less, swelling of the pattern occurs, which is not preferable. On the other hand, if the carbon number is too large, the development tends to take a relatively long time.

The ratio of the use ratio of these ether solvents and ketone solvents is from 10/90 to 70/3 on a weight basis.
0, preferably 15/85 to 65/35. Within this range, the pattern shape is good and high sensitivity can be obtained.
If the amount of the ether-based solvent is too large, the resist material dissolves and the thickness of the resist remaining after development is reduced, so that a desired pattern may not be obtained. Further, a third solvent can be used in combination, but its use ratio is 10% by weight based on the total developer.
The following is desirable in that the effects of the present invention can be sufficiently obtained.

(3) Developing Method The method of developing the resist material using the developing solution of the present invention is not particularly limited, but the effect is maximized in spray development. The specific method of spray development is as follows.

First, after irradiating the substrate coated with the resist material with an electron beam, the substrate is usually rotated at a speed of 100 to 500 revolutions per minute, usually at 10 to 30 ° C., preferably 15 to 2 ° C.
The developer at 5 ° C. is continuously sprayed on the substrate for a predetermined time.

Thereafter, if necessary, the remaining developer and the like are removed with a rinsing solution. Examples of the organic solvent used as the rinsing liquid include toluene, xylene, ethyl acetate, butyl acetate, isopropyl alcohol, methyl isobutyl ketone, and 2-heptanone. These solvents are used alone or in combination of two or more. The rinsing liquid preferably has a boiling point at normal pressure of 150 ° C. or lower, more preferably 120 ° C. or lower. Further, the developing step and the rinsing step can be alternately repeated about 2 to 10 times.

[0028]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Parts in the text are based on weight unless otherwise specified.

Examples 1 to 5 and Comparative Examples 1 to 8 α-methylstyrene / methyl α-chloroacrylate = 50/50
A resist material comprising a (mol fraction) copolymer (Mw = 331,000) and an organic solvent was prepared, and filtered through a high-density polyethylene (UPE) membrane filter having a pore size of 0.05 μm to prepare a resist solution. did.

After spin-coating a resist material on 6-inch blanks coated with 800 mm thick chromium,
The resist film was baked on a hot plate at 180 ° C. for 180 seconds to form a resist film having a thickness of 5000 °.

Next, an electron beam lithography system JBX-7000MV (manufactured by JEOL Ltd.) was used to adjust the amount of electron beam irradiation on the resist film formed on the blanks at an acceleration voltage of 20 kV. A line and space pattern of 0.0 μm was drawn. After pattern drawing, a developing solution having the composition shown in Table 1 was sprayed onto the substrate at 23 ° C. for a predetermined time while the substrate was rotated at 120 rpm to perform development. After the development, methyl isobutyl ketone was dropped as a rinsing liquid for 20 seconds while rotating the substrate at a speed of 300 revolutions per minute to perform rinsing. Finally, the rinse liquid was dried and removed by a nitrogen stream to obtain a positive resist pattern. The development time was varied and at an electron beam irradiation amount of 10 μC / cm ² ,
The development time was determined so that a 1.0 μm line & space pattern could be obtained with the designed dimensions.

The resist pattern obtained during the above development time was observed with an electronic scanning microscope. The ratio (T / B) of the length (T) of the upper side portion of the pattern cross section and the length (B) of the lower side portion (near the substrate interface) was calculated and used as an index of the pattern shape. Note that this index was set to zero for the case where no flat portion was observed on the upper side of the pattern due to swelling or the like. The closer T / B is to 1, the better the rectangular pattern. Table 1 shows the results obtained using the respective developing solutions.

[0033]

[Table 1]

[0034]

The resist developing solution of the present invention can be developed in a relatively short developing time while obtaining a practically acceptable amount of electron beam irradiation, and an excellent pattern shape can be obtained.

Claims (4)

[Claims] 1. A resist developer for developing a resist material containing a copolymer of a styrene monomer and an acrylic monomer, comprising: an aliphatic linear ether solvent or an aromatic ether. A resist developer containing a solvent and a ketone solvent having 5 or more carbon atoms. 2. The resist developer according to claim 1, wherein the ether solvent is at least one solvent selected from the group consisting of diethylene glycols and alkylphenyl ethers. 3. The resist developer according to claim 1, wherein the ketone solvent has 5 to 7 carbon atoms. 4. A development method by spray development using the resist developer according to claim 1.