JP2001027806A - Chemical amplification type resist composition and resist pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve dry etching resistance and to reduce chapping of a resist surface after dry etching by incorporating multifunctional epoxy compound and/or multifunctional vinyl ether compound into a composition. SOLUTION: A chemical amplification type resist composition contains a resin which becomes dissolvable in an alkali aqueous solution by an acid and an optical acid generating agent and further contains the multifunctional epoxy compound and/or multifunctional vinyl ether compound. The multifunctional epoxy compound and the multifunctional vinyl ether compound are compounds respectively having two or more epoxy groups or vinyl ether groups in a molecule and are used as a crosslinking agent. The resin which becomes dissolvable in the alkali aqueous solution by the acid includes a monomer unit having an alicyclic skeleton and a monomer unit having a lactone skeleton. The monomer unit having the alicyclic skeleton is selected from cyclohexyl (meth)acrylate or the like and the monomer unit having the lactone skeleton is selected from (meth)acrylate having a δ-valerolactone ring or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically amplified resist composition and a method of forming a resist pattern, and more particularly to a chemically amplified resist composition and a method of forming a resist pattern 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.

However, even when these resins are used, their performance is still insufficient, and higher dry etching resistance is required.

[0007]

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

[0008]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies for the purpose of improving the dry etching resistance of a chemically amplified resist composition.
The present inventors have found that a chemically amplified resist composition suitable for DUV excimer laser lithography or electron beam lithography can be obtained by adding a polyfunctional epoxy compound and / or a polyfunctional vinyl ether compound.

That is, the present invention provides a chemically amplified resist composition containing a resin which becomes soluble in an aqueous alkali solution with an acid and a photoacid generator, comprising a polyfunctional epoxy compound and / or a polyfunctional vinyl ether compound. Characteristic chemically amplified resist composition.

The present invention also provides a method of forming a resist using the chemically amplified resist composition, irradiating the resist with actinic rays such as UV, DUV, EB and / or far infrared rays or a heat source before performing dry etching. A resist pattern forming method, wherein a heat treatment is performed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The polyfunctional epoxy compound and the polyfunctional vinyl ether compound used in the present invention are compounds having two or more epoxy groups or vinyl ether groups in one molecule. In the present invention, a polyfunctional epoxy compound and a polyfunctional vinyl ether compound are used as a crosslinking agent. The polyfunctional epoxy compound and the polyfunctional vinyl ether compound can be used alone or in combination of two or more as needed.

[0012] The present inventors have made it possible to improve the dry etching resistance by including a polyfunctional epoxy compound and / or a polyfunctional vinyl ether compound in a resist composition, and to improve the roughness of the resist surface after dry etching. Was found to be reduced.

As the polyfunctional epoxy compound and the polyfunctional vinyl ether compound, specifically, 1,4-bis [(3-
Dioxetanes such as ethyl-3-oxetanylmethoxy) methyl] cyclohexane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, bis (3,4-epoxycyclohexyl)
Epoxy chlorohexanes such as adipate, triethylene glycol divinyl ether, cyclohexane dimethanol divinyl ether, diethylene glycol divinyl ether, dipropylene glycol divinyl ether,
Examples include divinyl ethers such as hexanediol divinyl ether and butanediol divinyl ether, and triglycidyl isocyanurate.

[0014] The amount of the polyfunctional epoxy compound and the polyfunctional vinyl ether compound to be used is appropriately selected depending on the kind thereof, and is usually 0.01 to 10 parts by weight based on 100 parts by weight of the resin which becomes soluble in an aqueous alkali solution by an acid. Department. The more the polyfunctional epoxy compound and the polyfunctional vinyl ether compound are, the more the dry etching resistance is improved, and the less the polyfunctional epoxy compound and the polyfunctional vinyl ether compound, the less the sensitivity and the resolution are reduced.

[0015] The structures of the polyfunctional epoxy compound and the polyfunctional vinyl ether compound are not particularly limited, but when a wavelength of 200 nm or less is used as a light source in lithography, a compound having no aromatic ring is preferable.

Next, a resin which becomes soluble in an alkaline aqueous solution by an acid will be described. This resin is not particularly limited as long as it has a property of being soluble in an aqueous alkali solution by an acid, and those which have been used 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 that case, in order to use it 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 by an acetoxy group, a t-butyl group, a tetrahydropyranyl group, a methyladamantyl 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.

Among them, 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, and 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 its resin composition, 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 with an acid, for example, an organic solvent in which a monomer solution in which a monomer and a polymerization initiator are dissolved 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.

The organic solvent used in the drop polymerization method is not particularly limited, but is preferably a solvent that can dissolve both the monomer and the obtained copolymer, such as 1,4-dioxane, isopropyl alcohol, acetone, and tetrahydrofuran. Is mentioned.

[0030] 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.

[0031] 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 the drop polymerization method is diluted with a good solvent such as tetrahydrofuran or 1,4-dioxane to an appropriate solution viscosity, 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, a resin powder which becomes soluble in an aqueous alkali solution with a dried acid is dissolved in a 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.

[0034] Solvents satisfying these conditions include, for example,
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 for a chemically amplified resist composition. The photoacid generators can be used alone or in combination of two or more.

Specific examples include onium salt compounds, sulfonimide compounds, sulfone compounds, sulfonate 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 100 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 are added to the chemically amplified resist composition of the present invention, if necessary. You can also.

[0040] 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.).

Next, a method of using the chemically amplified resist composition of the present invention will be described. Before performing dry etching, a resist patterned with a chemically amplified resist composition is irradiated with actinic rays such as UV, DUV, and EB and / or heated for a certain period of time using a heat source such as far infrared rays or a hot plate. Is preferably performed.

When a chemically amplified resist composition is irradiated with an actinic ray or an electron beam, an acid is generated from the photoacid generator, and the protective group of the resist resin is eliminated, so that a hydroxyl group or a carboxyl group is formed in the resist resin. . However, when irradiation with energy much larger than the exposure amount at the time of normal pattern formation, the polyfunctional epoxy compound and / or polyfunctional vinyl ether compound which did not react with the light irradiation at the normal exposure amount are subjected to photocationic polymerization. It is presumed that dry etching resistance is improved because a three-dimensional cross-linked structure is formed by reacting as a cross-linking agent.

Therefore, it is most preferable to perform a heat treatment by, for example, irradiating active light again after forming a pattern by exposure, PEB, and development.

[0044]

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 performed 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.

<Dry Etching Resistance> The resist film formed on the silicon wafer was etched, and the etching rate of each resist (standardized with the etching rate of novolak resin as 1) was measured from the decrease in film thickness. Etching conditions were as follows: using an etching machine manufactured by Tokyo Electron, using a gas mixture of C ₄ F ₈ / Ar / O _{2 as a} gas;
The operation was performed at 00 W and 50 mTorr for 50 seconds.

Further, the resist surface after etching was observed with an electron microscope, and the resist surface having no unevenness was evaluated as “、”, and the one having unevenness and rough was evaluated as “×”.

(Synthesis Example 1) A flask equipped with a nitrogen inlet, a stirrer, a condenser, and a thermometer was placed in a nitrogen atmosphere 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. pt-butoxystyrene (abbreviation: PTBST, molecular weight = 176) 22.0 parts, p-hydroxystyrene (abbreviation: HS, molecular weight = 120) 15.0
, 62.5 parts of 1,4-dioxane and 1.9 parts of azobisisobutyronitrile were dropped into the flask at a constant rate over 6 hours, and then the temperature was 80 ° C. For 2 hours. Then, 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-
A precipitate of 1) was obtained. The resulting precipitate is filtered off and dried under reduced pressure.
Dried at 40 ° C. for about 40 hours.

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

(Synthesis Example 2) 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. 2-methacryloyloxy-2-methyladamantane (abbreviation: MAdMA, molecular weight
= 234) 29.3 parts, β-methacryloyloxy-γ-butyrolactone (abbreviation: HGBMA, molecular weight = 170)
A monomer solution obtained by mixing 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 a period of 6 hours.
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 A-2). 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-2 was 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.

Then, using an ultra-high pressure mercury lamp, about 1 J / cm
² of ultraviolet irradiation, 180 ° C. on a hot plate, 6
Heat treated for 0 seconds. Tables 2 and 3 show the results of measuring the etching rate of each resist under the conditions described above.
It was shown to.

As described above, in the embodiment, the dry etching resistance was improved without largely lowering the sensitivity and the resolution, and the resist surface after the etching was not roughened. On the other hand, in the comparative example, the dry etching resistance was not sufficient, and the surface of the resist after etching was rough.

[0058]

【table 1】

[0059]

[Table 2]

[0060]

[Table 3]

[0061]

As described above, the chemically amplified resist composition of the present invention comprises:
Roughness of the resist surface after etching does not occur, dry etching resistance is good, sensitivity and resolution are high, and a high-precision fine resist pattern can be stably formed. Therefore, for DUV excimer laser lithography and electron beam lithography, especially ArF
It can be suitably used for lithography using an excimer laser.

Further, by using the pattern forming method of the present invention, higher dry etching resistance can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01L 21/30 570 571 F term (Reference) 2H025 AA01 AA09 AB16 AC04 AC06 AC08 AD03 CB14 CB30 CB41 CC17 FA17 FA29 FA30 FA41 2H096 AA25 BA11 EA03 EA05 EA06 GA08 HA01 HA03 HA23 5F046 KA02 LA18 5F056 DA04 DA09

Claims (5)

[Claims] Claims: 1. A chemically amplified resist composition containing a resin soluble in an aqueous alkali solution by an acid and a photoacid generator, comprising a polyfunctional epoxy compound and / or a polyfunctional vinyl ether compound. Amplification type resist composition. 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. Chemically amplified resist composition. 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 chemically amplified resist composition according to claim 2, wherein the composition is at least one selected from the group consisting of meth) acrylates and derivatives thereof having a substituent on an alicyclic ring. 4. The monomer unit having a lactone skeleton is represented by δ
A (meth) acrylate having a valerolactone ring, γ
The chemical amplification according to claim 2 or 3, wherein the compound 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. -Type resist composition. 5. A resist is formed using the chemically amplified resist composition according to claim 1, and the resist is irradiated with actinic rays such as UV, DUV, EB and / or far infrared rays before performing dry etching. Alternatively, a method for forming a resist pattern, comprising performing heat treatment with a heat source.