JP4094272B2 - Resist polymer and chemically amplified resist composition - Google Patents

Description

【００４８】
【発明の効果】
本発明のレジスト用（共）重合体および化学増幅型レジスト組成物を用いることにより、より高い解像度でＤＵＶエキシマレーザーリソグラフィー、電子線リソグラフィー等のリソグラフィーを行うことができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resist (co) polymer and a chemically amplified resist composition, and particularly to a resist (co) polymer and a chemically amplified resist composition suitable for fine processing using an excimer laser or an electron beam.
[0002]
[Prior art]
In recent years, in the field of microfabrication in the manufacture of semiconductor elements or liquid crystal elements, miniaturization has rapidly progressed due to advances in lithography technology. As the miniaturization technique, generally, the wavelength of an exposure light source is shortened, and specifically, the conventional ultraviolet ray typified by g-line and i-line is changed to DUV.
[0003]
At present, KrF excimer laser (248 nm) lithography technology has been introduced to the market, and ArF excimer laser (193 nm) lithography technology with a shorter wavelength is being introduced. The next generation technology is F ₂ excimer laser. Lithography technology is being studied (157 nm). In addition, an electron beam lithography technique has been energetically studied as a slightly different type of lithography technique.
[0004]
As a high-resolution resist for such short-wavelength light sources or electron beams, International Business Machines (IBM) has proposed “Chemically Amplified Resist”, and is currently energetically improving and developing this chemically amplified resist. Is underway.
[0005]
In addition, as the wavelength of the light source is shortened, the resin used for the resist is also forced to change its structure. In KrF excimer laser lithography, polyhydroxystyrene having high transparency with respect to 248 nm and its hydroxyl group are dissolved in an acid-dissociable manner. In the ArF excimer laser lithography, since the resin has insufficient transparency at 193 nm and is almost unusable, an acrylic resin or cycloolefin resin transparent at 193 nm is used. Attention has been paid. Examples of the acrylic resin include JP-A-4-39665 and JP-A-10-207069, and examples of the cycloolefin resin include JP-A-10-153864.
[0006]
[Problems to be solved by the invention]
However, with the miniaturization of patterns, higher resolution is required. Accordingly, an object of the present invention is to provide a resist (co) polymer and a chemically amplified resist composition that can obtain higher resolution in lithography such as DUV excimer laser lithography and electron beam lithography.
[0007]
[Means for Solving the Problems]
The present invention is a resist (co) polymer that is soluble in an alkaline aqueous solution by an acid, and is a homopolymerization of a monomer having an optically active lactone skeleton and an optical purity of 80% ee or more. It is a resist (co) polymer obtained by copolymerization with a monomer. The monomer having an optically active lactone skeleton has an optical activity of a (meth) acrylate having a γ-butyrolactone ring which may have a substituent other than a substituent containing a (meth) acryloyloxy group on the lactone ring. It is preferable that it is a body.
[0008]
The other monomer is preferably a monomer having an alicyclic skeleton. Monomers having an alicyclic skeleton include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentadienyl (meth) acrylate, and these At least one monomer selected from the group consisting of derivatives having a substituent on the alicyclic ring is preferred.
[0009]
The present invention also provides a chemically amplified resist composition containing this (co) polymer for resist and a photoacid generator.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The monomer having an optically active lactone skeleton used in the present invention needs to have a vinyl group-containing substituent on the lactone ring. Examples of the vinyl group-containing substituent include an acryloyloxy group, a methacryloyloxy group, a vinyl group, and an allyl group. Among them, an acryloyloxy group and a methacryloyloxy group (hereinafter referred to as a (meth) acryloyloxy group) are preferable.
[0011]
Moreover, you may have substituents other than a vinyl group containing substituent on the lactone ring of the monomer which has an optically active lactone skeleton used for this invention. Examples of such a substituent include an alkyl group, a hydroxyl group, a carboxyl group, and an alkoxyl group, and among them, an alkyl group, a hydroxyl group, and a carboxyl group are preferable.
[0012]
Examples of the lactone skeleton contained in this monomer include a γ-butyrolactone ring and a δ-valerolactone ring. Among them, a γ-butyrolactone ring is preferable.
[0013]
As such a monomer, an optically active substance of (meth) acrylate having a γ-butyrolactone ring which may have a substituent other than a substituent containing a (meth) acryloyloxy group on the lactone ring is preferable. Specifically, (R) -β-methacryloyloxy-γ-butyrolactone, (S) -β-methacryloyloxy-γ-butyrolactone, (R) -β-methacryloyloxy-β-methyl-γ-butyrolactone, Examples include S) -β-methacryloyloxy-β-methyl-γ-butyrolactone, (R) -α-methacryloyloxy-γ-butyrolactone, (S) -α-methacryloyloxy-γ-butyrolactone, and the like. Among these, (R) -β-methacryloyloxy-γ-butyrolactone and (S) -β-methacryloyloxy-γ-butyrolactone are preferable.
[0014]
The optical purity of the monomer having a lactone skeleton is preferably 80% ee or more, more preferably 90% ee or more, and particularly preferably 95% ee or more.
[0015]
Moreover, the monomer which has lactone skeleton can be used individually or in combination of 2 or more types as needed.
[0016]
A monomer having a lactone skeleton imparts adhesion to a substrate to a (co) polymer obtained by polymerization and a resin composition thereof, and particularly contains a protecting group that is eliminated by an acid. Can give high sensitivity at 193 nm. Further, it is believed that the use of a monomer having an optically active lactone skeleton changes the conformation of the (co) polymer and improves the resolution as a resist.
[0017]
The resist (co) polymer of the present invention is obtained by homopolymerizing a monomer having an optically active lactone skeleton or copolymerizing with another monomer. Examples of the other monomer include a monomer having an alicyclic skeleton, a monomer having a polar group such as a hydroxy group, a carboxyl group, and a cyano group. Among them, a monomer having an alicyclic skeleton Is preferred. A monomer having a polar group such as a hydroxy group, a carboxyl group, or a cyano group can improve the solubility of the copolymer, and can be copolymerized within a range that does not impair the performance as a resist. Two or more other monomers may be combined.
[0018]
A monomer having an alicyclic skeleton imparts high dry etching resistance to a copolymer obtained by polymerization and a resin composition thereof, and particularly contains a protective group that is eliminated by an acid. Can also provide high sensitivity at 193 nm.
[0019]
Monomers having an alicyclic skeleton include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentadienyl (meth) acrylate, and Derivatives having a substituent such as an alkyl group, a hydroxyl group or a carboxyl group on the alicyclic ring of these monomers are preferred. In particular, 1-isobornyl methacrylate, 2-methacryloyloxy-2-methyladamantane, cyclohexyl methacrylate, adamantyl methacrylate, tricyclodecanyl methacrylate, and dicyclopentadienyl methacrylate are preferable.
[0020]
In the resist (co) polymer of the present invention, the copolymer composition ratio of the monomer unit having an optically active lactone skeleton is preferably 5 to 90 mol%, more preferably 10 to 70 mol%, and more preferably 20 to 50 mol%. % Is particularly preferred.
[0021]
The weight average molecular weight of the resist (co) polymer of the present invention is not particularly limited, but is preferably in the range of 1,000 to 100,000, more preferably 3,000 to 30,000. 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.
[0022]
As a method for producing the resist (co) polymer of the present invention, for example, a monomer solution obtained by dissolving a monomer and a polymerization initiator in an organic solvent in advance is dropped into an organic solvent kept at a constant temperature. The so-called drop polymerization method is simple and suitable.
[0023]
The organic solvent used in the dropping polymerization method is not particularly limited, but a solvent capable of dissolving both the monomer and the obtained copolymer is preferable, and examples thereof include 1,4-dioxane, isopropyl alcohol, acetone, tetrahydrofuran and the like. .
[0024]
The polymerization initiator used in the dropping polymerization method is not particularly limited. For example, azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis (2- And azo compounds such as methyl propionate) and organic peroxides such as benzoyl peroxide. Further, mercaptans such as n-butyl mercaptan and n-octyl mercaptan may be used in combination as a chain transfer agent.
[0025]
The polymerization temperature in the drop polymerization method is not particularly limited, but is preferably in the range of 50 to 150 ° C. Although the dropping time is not particularly limited, it is preferably 3 hours or more, and it is preferable to hold the temperature for about 2 hours after completion of the dropping to complete the polymerization.
[0026]
A resist (co) polymer solution that is soluble in an alkaline aqueous solution by an acid produced by a dropping polymerization method is diluted with a good solvent such as tetrahydrofuran or 1,4-dioxane to an appropriate solution viscosity, and then heptane. , And dropped in a large amount of poor solvent such as methanol or water. Thereafter, the precipitate is filtered off and sufficiently dried. This step is called reprecipitation, and may be unnecessary depending on circumstances, but is very effective for removing unreacted monomers remaining in the polymerization solution, a polymerization initiator or the like. If these unreacted substances remain as they are, there is a possibility of adversely affecting the resist performance. Therefore, it is preferable to remove them if possible.
[0027]
Thereafter, the dried (co) polymer is dissolved in a solvent. Examples of such a solvent include linear ketones such as 2-pentanone and 2-hexanone; cyclic ketones such as cyclopentanone and cyclohexanone; propylene such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate. Glycol monoalkyl ether acetates; ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether and propylene glycol monoethyl ether; ethylene glycol Ethylene glycol mono, such as monomethyl ether and ethylene glycol monoethyl ether Ruki ethers; diethylene glycol dimethyl ether, diethylene glycol alkyl ethers such as diethylene glycol diethyl ether; an ester such as ethyl acetate or ethyl lactate; cyclohexanol, alcohols such as 1-octanol; ethylene carbonate, .gamma.-butyrolactone. These solvents can be used alone or in admixture of two or more.
[0028]
Next, the chemically amplified resist composition of the present invention will be described.
The photoacid generator that is a component of the chemically amplified resist composition of the present invention can be arbitrarily selected from those that can be used as the acid generator of the chemically amplified resist composition. Moreover, a photo-acid generator can be used individually or in combination of 2 or more types.
[0029]
Examples of such a photoacid generator include an onium salt compound, a sulfonimide compound, a sulfone compound, a sulfonic acid ester compound, a quinonediazide compound, and a diazomethane compound, and among them, an onium salt compound is preferable. Examples of the onium salt compounds include sulfonium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.
[0030]
Specific compounds that can be used as a photoacid generator include triphenylsulfonium triflate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium naphthalenesulfonate, (hydroxyphenyl) benzylmethylsulfonium toluenesulfonate, diphenyliodonium triflate, and diphenyl. Examples include iodonium pyrene sulfonate, diphenyl iodonium dodecyl benzene sulfonate, and diphenyl iodonium hexafluoroantimonate.
[0031]
The amount of the photoacid generator used is appropriately determined depending on the type of photoacid generator used, but is usually 0.1 to 20 parts by weight, preferably 0.1 to 100 parts by weight per 100 parts by weight of the resin that is soluble in an alkaline aqueous solution by acid. 5 to 10 parts by weight. If the amount of the photoacid generator used is too small, it may be difficult to cause a chemical reaction due to the catalytic action of the acid generated by exposure, and if it is too large, the stability of the resist composition will decrease. Or coating unevenness when applying the composition, or scum or the like may occur during development.
[0032]
Furthermore, the chemical amplification resist composition of the present invention may be blended with various additives such as surfactants, quenchers, sensitizers, antihalation agents, storage stabilizers, antifoaming agents, etc., as necessary. it can.
[0033]
Examples of the surfactant include nonionic surfactants such as polyoxyethylene lauryl ether and polyethylene glycol dilaurate, and the following trade names: Polyflow No. 75 (manufactured by Kyoeisha Chemical Co., Ltd.), Megafax F173 (manufactured by Dainippon Ink & Chemicals, Inc.), Surflon SC-105 (manufactured by Asahi Glass Co., Ltd.), L-70001 (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like.
[0034]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
The physical properties of the copolymer and the resist were evaluated by the following methods.
[0035]
<Weight average molecular weight>
It calculated | required in conversion of the polymethyl methacrylate by the gel permeation chromatography (GPC). As the solvent, chloroform or tetrahydrofuran was used.
[0036]
<Average copolymer composition ratio of copolymer (mol%)>
^It calculated | required by the measurement of < ¹ > H-NMR. As the solvent, deuterated chloroform or deuterated acetone was used.
[0037]
<Sensitivity>
The resist film formed on the silicon wafer was exposed and immediately post-exposure baked, then developed with an alkali developer, washed with water, and dried to form a resist pattern. The exposure amount for forming a line and space pattern (L / S = 1/1) with a line width of 1/1 was measured as sensitivity.
[0038]
<Resolution>
The minimum dimension (μm) of the resist pattern resolved when exposed with the above exposure amount was defined as the resolution.
[0039]
[Example 1]
Under a nitrogen atmosphere, 20.0 g of 1,4-dioxane was added to a flask equipped with a nitrogen inlet, a stirrer, a condenser and a thermometer, and the temperature of the hot water bath was raised to 80 ° C. while stirring. 29.3 g of 2-methacryloyloxy-2-methyladamantane (abbreviation: MAdMA, molecular weight = 234), (S) -β-methacryloyloxy-γ-butyrolactone (abbreviation: (S) -HGBMA, molecular weight = 170, purity 99%) , Optical purity 93% ee) 21.2 g of 1,4-dioxane 62.5 g, azobisisobutyronitrile 2.1 g mixed monomer solution was dropped into the flask at a constant rate over 6 hours. Thereafter, the temperature of 80 ° C. was maintained for 2 hours. Next, the obtained reaction solution was diluted about 2-fold with tetrahydrofuran and dropped into about 10-fold methanol with stirring to obtain a white precipitate (copolymer A-1). The resulting precipitate was filtered off and dried under reduced pressure at 60 ° C. for about 40 hours.
[0040]
When the physical properties of the obtained resist copolymer A-1 were measured, the weight average molecular weight was 8,400, and the copolymer composition ratio was MAdMA / (S) -HGBMA = 50/50 mol%.
[0041]
Next, 100 parts by weight of copolymer A-1 for resist, 2 parts by weight of triphenylsulfonium triflate as a photoacid generator, and 500 parts by weight of propylene glycol monomethyl ether acetate as a solvent were mixed to obtain a uniform solution. The solution was filtered through a membrane filter having a pore size of 0.1 μm to prepare a chemically amplified resist composition solution.
[0042]
After spin-coating the resist composition solution on a silicon wafer, pre-baking was performed at 120 ° C. for 60 seconds using a hot plate to form a resist film having a thickness of 0.5 μm. Next, after exposure using an ArF excimer laser exposure machine, post-exposure baking was performed using a hot plate at 120 ° C. for 60 seconds. Next, development was performed at room temperature using a 2.38 wt% tetramethylammonium hydroxide aqueous solution, washed with pure water, and dried to form a resist pattern. The evaluation results of the obtained resist pattern are shown in Table 1.
[0043]
[Example 2]
(S) -β-methacryloyloxy-γ-butyrolactone was changed to (R) -β-methacryloyloxy-γ-butyrolactone (abbreviation: (R) -HGBMA, molecular weight = 170, purity 99%, optical purity 93% ee). A copolymer A-2 for resist was obtained in the same manner as in Example 1 except that. When the physical properties of the obtained resist copolymer A-2 were measured, the weight average molecular weight was 8,300, and the copolymer composition ratio was MAdMA / (R) -HGBMA = 50/50 mol%.
[0044]
Subsequently, the chemical amplification resist composition solution was prepared in the same manner as in Example 1 except that the resist copolymer A-1 was changed to A-2, and the results of evaluating the resist pattern are shown in Table 1.
[0045]
[Comparative Example 1]
(S) -β-methacryloyloxy-γ-butyrolactone was used for resist in the same manner as in Example 1 except that racemic β-methacryloyloxy-γ-butyrolactone (abbreviation: HGBMA, molecular weight = 170, purity 99%) was changed. Copolymer A-3 was obtained. When the physical properties of the obtained resist copolymer A-3 were measured, the weight average molecular weight was 8,400 and the copolymer composition ratio was MAdMA / HGBMA = 50/50 mol%.
[0046]
Subsequently, the chemical amplification resist composition solution was prepared in the same manner as in Example 1 except that the resist copolymer A-1 was changed to A-3, and the results of evaluating the resist pattern are shown in Table 1.
[0047]
[Table 1]

[0048]
【The invention's effect】
By using the resist (co) polymer and the chemically amplified resist composition of the present invention, lithography such as DUV excimer laser lithography and electron beam lithography can be performed with higher resolution.

Claims (5)

A (co) polymer for resist that becomes soluble in an alkaline aqueous solution by an acid, and is a monomer that has an optically active lactone skeleton and an optical purity of 80% ee or higher, either homopolymerized or co-polymerized with other monomers. (Co) polymer for resist obtained by polymerization. Optical activity of a (meth) acrylate having a γ-butyrolactone ring in which the monomer having an optically active lactone skeleton may have a substituent other than a substituent containing a (meth) acryloyloxy group on the lactone ring The resist (co) polymer according to claim 1, wherein the resist (co) polymer is a body. 3. The resist copolymer according to claim 1, wherein the other monomer is a monomer having an alicyclic skeleton. Monomers having an alicyclic skeleton include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentadienyl (meth) acrylate and these 4. The (co) polymer for resists according to claim 3, wherein the resist (co) polymer is at least one selected from the group consisting of derivatives having a substituent on the alicyclic ring. Resist (co) polymer and a photoacid generator chemically amplified resist composition containing as claimed in any one of claims 1-4.