JP2001022073A - Resin for resist and chemically amplified resist composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist resin and a chemically amplified resist composition suitable for DUV excimer laser lithography or electron beam lithography having high adhesion to a substrate. SOLUTION: The resist resin is soluble in an aqueous alkali solution by an acid, and contains a monomer unit having at least one kind of structure selected from formulas (1) and (2). Resist resin. [Formula 5] (R is a hydrogen atom or an alkyl group, and n is an integer of 0 to 4.) (R is a hydrogen atom or an alkyl group, n is an integer of 0 to 4)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a resist resin and a chemically amplified resist composition, and more particularly to a resist resin and a chemically amplified resist composition suitable for fine processing using an excimer laser or an electron beam.

[0002]

2. Description of the Related Art In recent years, in the field of microfabrication in the production of semiconductor devices or liquid crystal devices, miniaturization has rapidly progressed due to advances in lithography technology. As a method of miniaturization, a shorter wavelength of an exposure light source is generally used.
Specifically, from the ultraviolet rays represented by the conventional g-line and i-line,
It is changing to UV.

At present, a KrF excimer laser (248 n
m) lithography techniques are introduced to the market, further it is about to be introduced ArF excimer laser (193 nm) lithographic technique that measure the shorter wavelength is, F ₂ excimer laser (157 nm) lithographic technique is a further next generation technology research Have been. Also, electron beam lithography, which is a slightly different type of lithography, has been energetically studied.

As a high-resolution resist for such a short wavelength light source or an electron beam, International Business Machines (IBM) has proposed a "chemically amplified resist". Development is being actively pursued.

[0005] In addition, when the wavelength of the light source is shortened, the resin used for the resist is also required to change its structure. In KrF excimer laser lithography, 248 nm is required.
Polyhydroxystyrene having high transparency and its hydroxyl group protected by an acid dissociable, dissolution inhibiting group are used. In ArF excimer laser lithography, the above resin has insufficient transparency at 193 nm and is almost used. Since it is impossible, acryl-based resins or cycloolefin-based resins transparent at 193 nm have attracted attention. As the acrylic resin, Japanese Patent Application Laid-Open
JP-A-39665, JP-A-10-20769 and the like are mentioned, and as for the cycloolefin-based resin, JP-A-10-153864 and the like are mentioned.

[0006] However, even when these resins are used, their performance is still insufficient, and higher resolution is required.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a resist resin and a chemically amplified resist composition suitable for DUV excimer laser lithography or electron beam lithography having high resolution.

[0008]

Means for Solving the Problems In view of the above problems, the present inventors have made intensive studies on the structure of a resist resin, and as a result, using a resin having a specific structure makes it suitable for DUV excimer laser lithography or electron beam lithography. The present inventors have found that a novel resist resin and a chemically amplified resist composition can be obtained, and have reached the present invention.

That is, the present invention relates to a resist resin which is soluble in an alkaline aqueous solution by an acid, and contains a monomer unit having at least one structure selected from formulas (1) and (2). And a resist resin.

[0010]

Embedded image (R is a hydrogen atom or an alkyl group, n is an integer of 0 to 4)

[0011]

[Formula 4] (R is a hydrogen atom or an alkyl group, n is an integer of 0 to 4)

The present invention is also a chemically amplified resist composition containing the resist resin and a photoacid generator.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

First, a resin which becomes soluble in an aqueous alkali solution by an acid will be described. The resin soluble in an aqueous alkali solution by an acid must contain a monomer unit having at least one structure selected from the formulas (1) and (2). These monomer units are present in the resin in a concentration of 0.1.
It is preferably contained in an amount of 5 to 20 mol%, particularly 1 to
10 mol% is preferred.

The inventors of the present application have found that by introducing such a cyclic and highly polar structure into a resin, it is possible to prevent the resist from falling down after development and to improve the resolution.

The monomer unit having at least one kind of structure selected from the above formulas (1) and (2) is a (meth) acrylate monomer unit which can be easily introduced into a resin skeleton by copolymerization. Is preferred. Specifically, 2- (meth) acryloyloxy succinic anhydride, 2- (meth) acryloyloxy glutaric anhydride, 2- (meth) acryloyloxy adipic anhydride, 2- (meth) acryloyloxy pimelic anhydride, -(Meth) acryloyloxysuberic anhydride, 1,3-dioxolan-2-one-4-yl methacrylate, 1,3-dioxen-2-
On-4-yl methacrylate, 1,3-dioxepan-2-one-4-yl methacrylate, 1,3-dioxocan-2-one-4-yl methacrylate, 1,3-
And dioxonan-2-one-4-yl methacrylate. Among them, 2- (meth) acryloyloxysuccinic anhydride and 1,3-dioxen-2-one-4
-Il (meth) acrylate is particularly preferred in that it has high adhesion to the substrate.

It is preferable to introduce into the resist resin of the present invention a structure having a functional group which is easily released by the action of an acid and a structure having high dry etching resistance.
As other monomer units used to introduce such a structure, those which have heretofore been known as a resin for a chemically amplified resist composition can be used. These are arbitrarily selected depending on the light source used for lithography.

For example, when a KrF excimer laser or an electron beam is used as a light source, considering its high etching resistance,
A resin obtained by copolymerizing p-hydroxystyrene or a derivative thereof is preferably used. In this case, in order to use the composition as a chemically amplified resist composition, it is essential that the copolymer has a functional group which is eliminated by an acid and becomes soluble in an alkaline developer.

Specifically, the hydroxyl group of p-hydroxystyrene is protected with an acetoxy group, a t-butyl group, a tetrahydropyranyl group, a methyl adamantyl group, or the like, and the carboxyl group of a copolymerizable monomer is protected. It is preferred to do so.

When the light source is an ArF excimer laser, a resin obtained by copolymerizing p-hydroxystyrene or a derivative thereof cannot be used due to its low light transmittance because the wavelength is short. Therefore, a resin having an alicyclic skeleton is preferably used in consideration of the balance with the etching resistance.

Specifically, acrylic resins described in JP-A-9-090637 or JP-A-10-2070069, and olefin-based resins described in JP-A-10-207070 or 10-218941 are disclosed. Resins.

Above all, an acrylic copolymer obtained by polymerizing a monomer having an alicyclic skeleton and a monomer having a lactone skeleton is particularly suitable as a resin for ArF excimer laser lithography.

The monomer having an alicyclic skeleton imparts high dry etching resistance to a copolymer obtained by polymerization and a resin composition thereof, and particularly has a protective group which is eliminated by an acid. Those containing can also provide high sensitivity at 193 nm. Monomers having an alicyclic skeleton can be used alone or in combination of two or more as necessary.

Examples of the monomer having an alicyclic skeleton include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentadienyl (meth) At least one selected from the group consisting of acrylates and derivatives having a substituent such as an alkyl group, a hydroxyl group or a carboxyl group on the alicyclic ring of these monomers is preferable. Specifically, 1-isobonyl methacrylate, 2-methacryloyloxy-2
-Methyladamantane, cyclohexyl methacrylate, adamantyl methacrylate, tricyclodecanyl methacrylate, dicyclopentadienyl methacrylate and the like.

The monomer having a lactone skeleton imparts adhesion to a substrate to a copolymer obtained by polymerization and a resin composition thereof, and particularly contains a protecting group which is eliminated by an acid. Those can provide high sensitivity at 193 nm. Monomers having a lactone skeleton can be used alone or in combination of two or more as needed.

Examples of the monomer having a lactone skeleton include (meth) acrylate having a δ-valerolactone ring, (meth) acrylate having a γ-butyrolactone ring, and At least one selected from the group consisting of derivatives having a substituent such as an alkyl group, a hydroxyl group, and a carboxyl group is preferable.

Specifically, β-methacryloyloxy-β-
Methyl-δ-valerolactone, β-methacryloyloxy-γ-butyrolactone, β-methacryloyloxy-
β-methyl-γ-butyrolactone, α-methacryloyloxy-γ-butyrolactone, 2- (1-methacryloyloxy) ethyl-4-butanolide, pantolactone methacrylate and the like.

The weight average molecular weight of the resin soluble in an aqueous alkali solution with an acid is not particularly limited, but is preferably 1,0.
The range is from 00 to 100,000. The larger the weight average molecular weight, the better the dry etching resistance and the better the resist shape, and the smaller the weight average molecular weight, the better the solubility in the resist solvent and the better the resolution.

As a method for producing a resin which becomes soluble in an aqueous alkali solution by an acid, for example, an organic solvent in which a monomer solution obtained by dissolving a monomer and a polymerization initiator in an organic solvent is kept at a predetermined temperature is used. A so-called drop polymerization method in which the solution is dropped into the inside is simple and suitable.

[0030] The organic solvent used in the drop polymerization method is not particularly limited, but a solvent that can dissolve both the monomer and the obtained copolymer is preferable, and examples thereof include 1,4-dioxane, isopropyl alcohol, acetone, and tetrahydrofuran. Is mentioned.

[0031] The polymerization initiator used in the drop polymerization method is not particularly limited. For example, azobisisobutyronitrile,
Examples include azo compounds such as 2,2'-azobis (2,4-dimethylvaleronitrile) and organic peroxides such as benzoyl peroxide. N-butyl mercaptan, n
-Mercaptans such as octyl mercaptan may be used in combination as a chain transfer agent.

[0032] The polymerization temperature in the drop polymerization method is not particularly limited, but is preferably in the range of 50 to 150 ° C. The dropping time is not particularly limited, but is 6 hours or more, and it is preferable to maintain the temperature for about 2 hours after the completion of the dropping to complete the polymerization.

A resin solution which is made soluble in an aqueous alkali solution by an acid produced by a drop polymerization method is diluted to an appropriate solution viscosity with a good solvent such as tetrahydrofuran or 1,4-dioxane, and then diluted with heptane, methanol, It is deposited by dropping into a large amount of poor solvent such as water. Thereafter, the precipitate is separated by filtration and dried sufficiently. This step is called reprecipitation, and may be unnecessary in some cases. However, it is very effective for removing unreacted monomers or a polymerization initiator remaining in the polymerization solution. If these unreacted substances remain as they are, they may adversely affect the resist performance. Therefore, it is preferable to remove these unreacted substances if possible.

Thereafter, the resin powder which becomes soluble in the aqueous alkali solution by the dried acid is dissolved in the solvent. This solvent
The solvent is arbitrarily selected depending on the purpose, but the choice of the solvent is also restricted by reasons other than the solubility of the resin, for example, the uniformity, appearance, safety and the like of the coating film.

Examples of the solvent satisfying these conditions include:
Linear ketones such as 2-pentanone and 2-hexanone;
Cyclic ketones such as cyclopentanone and cyclohexanone; propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate; ethylene glycol monoethylene such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate Alkyl ether acetates; propylene glycol monomethyl ether,
Propylene glycol monoalkyl ethers such as propylene glycol monoethyl ether; ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; diethylene glycol alkyl ethers such as diethylene glycol dimethyl ether and diethylene glycol diethyl ether; ethyl acetate, lactic acid Esters such as ethyl; alcohols such as cyclohexanol and 1-octanol; ethylene carbonate and γ-butyrolactone. These solvents can be used alone or in combination of two or more.

Next, the photoacid generator used in the present invention will be described.

The photoacid generator can be arbitrarily selected from those which can be used as an acid generator in a chemically amplified resist composition. The photoacid generators can be used alone or in combination of two or more.

[0038] Specific examples include onium salt compounds, sulfonimide compounds, sulfone compounds, sulfonic acid ester compounds, quinonediazide compounds, and diazomethane compounds. Among them, onium salt compounds are preferred,
For example, sulfonium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts and the like can be mentioned.

As specific examples, triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalene sulfonate, (hydroxyphenyl) benzylmethylsulfonium toluenesulfonate, diphenyliodonium triflate, diphenyliodonium pyrene sulfonate, diphenyliodonium Dodecylbenzene sulfonate, diphenyliodonium hexafluoroantimonate and the like can be mentioned.

The amount of the photoacid generator used is appropriately determined depending on the type of the photoacid generator to be used, and is usually 0.1 to 20 parts by weight, preferably 0.1 to 20 parts by weight, per 100 parts by weight of the resin soluble in an aqueous alkali solution by an acid. Is 0.5 to 10 parts by weight. If the amount of the photoacid generator is too small, it may be difficult to sufficiently generate a chemical reaction due to the catalytic action of the acid generated by exposure, and if the amount is too large, the stability of the resist composition decreases. Or unevenness in application of the composition, or scum or the like during development.

Further, various additives such as a surfactant, a quencher, a sensitizer, an antihalation agent, a storage stabilizer and an antifoaming agent may be added to the chemically amplified resist composition of the present invention, if necessary. You can also.

Examples of the surfactant include nonionic surfactants such as polyoxyethylene lauryl ether and polyethylene glycol dilaurate. 75 (manufactured by Kyoeisha Yushi Kagaku Kogyo),
Megafax F173 (manufactured by Dainippon Ink and Chemicals),
Surflon SC-105 (made by Asahi Glass), L-70001
(Manufactured by Shin-Etsu Chemical Co., Ltd.).

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Here, “parts” means “parts by weight” unless otherwise specified.

The measurement of the physical properties of the copolymer and the evaluation of the resist were carried out by the following methods.

<Weight average molecular weight> Gel permeation
It was determined by chromatography (GPC) in terms of polymethyl methacrylate. Chloroform or tetrahydrofuran was used as the solvent.

<Average copolymer composition (mol%) of copolymer> ¹ H
-Determined by NMR measurement. Heavy chloroform or heavy acetone was used as the solvent.

<Sensitivity> Immediately after exposing the resist film formed on the silicon wafer, post-exposure baking was performed, then developed with an alkali developing solution, washed with water, and dried to form a resist pattern. The exposure was measured as the sensitivity to form a line and space pattern (L / S = 1/1) with a line width of 1/1.

<Resolution> The minimum dimension (μm) of the resist pattern resolved when exposed at the above exposure amount was defined as the resolution.

<Adhesion with substrate> Observation of the resist pattern that was resolved when exposed at the above-mentioned exposure amount was observed. Was evaluated.

(Synthesis Example 1) A flask equipped with a nitrogen inlet, a stirrer, a condenser, and a thermometer was placed under a nitrogen atmosphere.
20.0 parts of 1,4-dioxane was added, and the temperature of the hot water bath was raised to 80 ° C. while stirring. 22.0 parts of pt-butoxystyrene (abbreviation: PTBST, molecular weight = 176), 13.5 parts of p-hydroxystyrene (abbreviation: HS, molecular weight = 120)
Part, 2-methacryloyloxysuccinic anhydride (abbreviation: M
AMA, molecular weight = 184) 2.3 parts, 1,4-dioxane 6
A monomer solution obtained by mixing 2.5 parts of azobisisobutyronitrile and 1.9 parts of azobisisobutyronitrile was dropped into the flask over a period of 6 hours at a constant speed, and then the temperature at 80 ° C. was maintained for 2 hours. Next, the obtained reaction solution was diluted about 2-fold with tetrahydrofuran, and added dropwise to about 10-fold amount of water while stirring to obtain a white precipitate (copolymer A-1). The obtained precipitate was separated by filtration and dried under reduced pressure at 60 ° C. for about 40 hours.

Next, each physical property of the obtained copolymer A-1 was measured. The weight average molecular weight was 9,000, and the copolymer composition ratio was PTBST / HS / MAMA = 50/45/5 mol%.

(Synthesis Example 2) 2-methacryloyloxysuccinic anhydride of Synthesis Example 1 (abbreviation: MAMA, molecular weight = 184)
Synthesis was performed in the same manner except that 3 parts was changed to 2.3 parts of 1,3-dioxan-2-one-5-yl methacrylate (abbreviation: DOMA, molecular weight = 186) to obtain a copolymer A-2. .

Then, each physical property of the obtained copolymer A-2 was measured. The weight average molecular weight was 9,500, and the copolymer composition ratio was PTBST / HS / DOMA = 50/45/5 mol%.

(Synthesis Example 3) In a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer, under a nitrogen atmosphere,
20.0 parts of 1,4-dioxane was added, and the temperature of the hot water bath was raised to 80 ° C. while stirring. 2-methacryloyloxy-2-methyladamantane (abbreviation: MAdMA, molecular weight
= 234) 29.3 parts, β-methacryloyloxy-γ-butyrolactone (abbreviation: HGBMA, molecular weight = 170)
1 part, 2-methacryloyloxysuccinic anhydride (abbreviation:
MAMA, molecular weight = 184) A monomer solution obtained by mixing 2.3 parts, 62.5 parts of 1,4-dioxane, and 1.9 parts of azobisisobutyronitrile was placed in a flask at a constant speed for 6 hours. After that, the temperature was kept at 80 ° C. for 2 hours.
Then, the obtained reaction solution was washed with tetrahydrofuran for about 2 hours.
The mixture was diluted 1-fold and added dropwise to about 10-fold amount of methanol with stirring to obtain a white precipitate (copolymer A-3). The obtained precipitate was separated by filtration and dried under reduced pressure at 60 ° C. for about 40 hours. Next, each physical property of the obtained copolymer A-3 was measured. The weight average molecular weight is 9,200, and the copolymer composition ratio is MAdMA / HGBMA / MAMA = 50/45/5.
Mole%.

Synthesis Example 4 2-Methacryloyloxysuccinic anhydride of Synthesis Example 3 (abbreviation: MAMA, molecular weight = 184)
The same synthesis was conducted except that 3 parts was changed to 2.3 parts of 1,3-dioxan-2-one-5-yl methacrylate (abbreviation: DOMA, molecular weight = 186) to obtain a copolymer A-4. .

Next, each physical property of the obtained copolymer A-4 was measured. The weight average molecular weight was 9,600, and the copolymer composition ratio was MAdMA / HGBMA / DOMA = 50/45/5 mol%.

(Comparative Synthesis Example 1) A flask equipped with a nitrogen inlet, a stirrer, a condenser, and a thermometer was charged with 20.0 parts of 1,4-dioxane under a nitrogen atmosphere, and the temperature of the hot water bath was stirred. Increased to 80 ° C. 22.0 parts of pt-butoxystyrene (abbreviation: PTBST, molecular weight = 176), p
-Hydroxystyrene (abbreviation: HS, molecular weight = 120) 1
A monomer solution obtained by mixing 5.0 parts, 62.5 parts of 1,4-dioxane, and 1.9 parts of azobisisobutyronitrile was dropped into the flask at a constant speed over a period of 6 hours.
A temperature of 0 ° C. was maintained for 2 hours. Next, the obtained reaction solution was diluted about 2-fold with tetrahydrofuran, and added dropwise to about 10-fold amount of water while stirring to obtain a white precipitate (copolymer AH-1). The obtained precipitate was separated by filtration and dried under reduced pressure at 60 ° C. for about 40 hours.

Next, each physical property of the obtained copolymer AH-1 was measured. The weight average molecular weight was 12,000, and the copolymer composition ratio was PTBST / HS = 51/49 mol%.

(Comparative Synthesis Example 2) A flask equipped with a nitrogen inlet, a stirrer, a condenser, and a thermometer was charged with 20.0 parts of 1,4-dioxane under a nitrogen atmosphere, and the temperature of the hot water bath was reduced with stirring. Increased to 80 ° C. 29.3 parts of 2-methacryloyloxy-2-methyladamantane (abbreviation: MAdMA, molecular weight = 234), β-methacryloyloxy-γ
-Butyrolactone (abbreviation: HGBMA, molecular weight = 170) 2
A monomer solution obtained by mixing 1.2 parts, 62.5 parts of 1,4-dioxane, and 1.9 parts of azobisisobutyronitrile was dropped into the flask at a constant speed over 6 hours.
A temperature of 0 ° C. was maintained for 2 hours. Then, the obtained reaction solution was diluted about 2-fold with tetrahydrofuran, and added dropwise to about 10-fold amount of methanol with stirring to obtain a white precipitate (copolymer AH-2). The obtained precipitate was separated by filtration and dried under reduced pressure at 60 ° C. for about 40 hours.

Next, the physical properties of the obtained copolymer AH-2 were measured. The weight average molecular weight was 11,000, and the copolymer composition ratio was MAdMA / HGBMA = 50/50 mol%.

Examples 1 to 4 and Comparative Examples 1 to 2 The components shown in Table 1 were mixed to form a uniform solution, which was then filtered through a membrane filter having a pore size of 0.1 μm to prepare a resist composition solution. Thereafter, each composition solution was spin-coated on a silicon wafer, and then prebaked at 120 ° C. for 60 seconds using a hot plate to form a 0.5 μm-thick resist film. Then, KrF
After exposure using an excimer laser exposure machine or an ArF excimer laser exposure machine, a post-exposure bake was performed at 120 ° C. for 60 seconds using a hot plate. Then
The resist was developed with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide at room temperature, washed with pure water, and dried to form a resist pattern. Tables 2 and 3 show the evaluation results of the obtained resist patterns.

As described above, in the embodiment, the resolution was improved without significantly lowering the sensitivity, the adhesion to the substrate was improved, and the resist did not collapse. on the other hand,
In the comparative example, both the resolution and the adhesion to the substrate were not sufficient.

[0063]

【table 1】

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

EFFECTS OF THE INVENTION The resist resin and the chemically amplified resist composition of the present invention have good adhesion to a substrate, high sensitivity and high resolution, and stably form a high-precision fine resist pattern. be able to. Therefore, D
It can be suitably used for UV excimer laser lithography and electron beam lithography, particularly for lithography using an ArF excimer laser.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Naoshi Murata 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. Central Research Laboratory F-term (reference) 2H025 AA01 AA02 AA14 AB16 AB20 AC04 AC06 AC08 AD03 BE00 BE07 CB14 CB41 CB52 FA17 4J100 AL08P AL08Q AL08R BA11R BC04P BC07P BC09P BC26P BC28P BC53Q BC55R BC58R CA05 DA28 FA02 FA17

Claims (5)

[Claims] Claims: 1. A resist resin which is soluble in an aqueous alkali solution by an acid, wherein the resin contains a monomer unit having at least one structure selected from formulas (1) and (2). Characteristic resin for resist. [Formula 1] (R is a hydrogen atom or an alkyl group, and n is an integer of 0 to 4.) (R is a hydrogen atom or an alkyl group, n is an integer of 0 to 4) 2. The resist resin according to claim 1, wherein the resist resin soluble in an alkaline aqueous solution by an acid contains a monomer unit having an alicyclic skeleton and a monomer unit having a lactone skeleton. Resin for resist. 3. The monomer unit having an alicyclic skeleton includes cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, and dicyclopentadienyl ( 3. The resist resin according to claim 2, wherein the resin is at least one selected from the group consisting of meth) acrylates and derivatives having a substituent on an alicyclic ring thereof. 4. The monomer unit having a lactone skeleton is represented by δ
A (meth) acrylate having a valerolactone ring, γ
4. The resist according to claim 2, wherein the resist is at least one selected from the group consisting of (meth) acrylate having a butyrolactone ring and derivatives of these monomers having a substituent on the lactone ring. 5. For resin. 5. A chemically amplified resist composition comprising the resist resin according to claim 1 and a photoacid generator.