JP2005042119A - POLYMER OF ACRYLIC ACID HAVING alpha-HYDROXYALKYL GROUP OR ITS ESTER OR COPOLYMER OF THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer or copolymer highly transparent to an ArF excimer laser beam, capable of giving a resist pattern which has high resolution and is not swollen and of which the cross-sectional shape is vertical, and suitable for a resin component of a negative-type resist composition. <P>SOLUTION: This polymer, or the copolymer, is formed out of at least one kind of monomer selected from an α-(hydroxyalkyl)acrylic acid and its alkyl ester. Further, the copolymer is formed out of (a) at least one kind of monomer selected from the α-(hydroxyalkyl)acrylic acid and its alkyl ester and (b) at least one kind of monomer selected from an ethylenic unsaturated carboxylic acid other than the monomer (a) and its ester. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel polymer or copolymer suitably used as a resin component of a chemically amplified negative resist composition.

Conventionally, a chemically amplified negative containing a combination of an acid generator, an alkali-soluble resin such as a novolak resin or polyhydroxystyrene, and an amino resin such as a melamine resin or a urea resin as a basic component for making the exposed portion alkali-insoluble. A type resist is known (see Patent Document 1).
In such a negative resist, an alkali-soluble resin and an amino resin cause a crosslinking reaction by the action of an acid generated by irradiation of radiation, the exposed part is changed to alkali-insoluble, and the unexposed part is dissolved with alkali. A negative pattern is formed.

  A chemically amplified negative resist composed of a combination of such an acid generator, an alkali-soluble resin, and an amino resin can be sufficiently used for a process using i-line or KrF excimer laser light (248 nm) as a light source. In recent years, resists for ArF that have been developed to cope with high integration of semiconductor elements are not necessarily satisfactory.

  By the way, for negative resists for ArF, for example, (1) a copolymer of 5-methylene-bicyclo [2.2.1] -2-heptane and maleic acid, A negative resist for ArF (see Non-Patent Document 1), which is obtained by esterifying a carboxyl group of a base resin component, and a crosslinking agent and an acid generator composed of an aliphatic cyclic polyhydric alcohol. A copolymer of an acrylic ester having an epoxy group-containing cyclic hydrocarbon group in the ester portion and an acrylic ester having a carboxyl group-containing cyclic hydrocarbon group in the ester portion is used as a base resin component, and the same crosslinking as described above Negative resist for ArF containing an agent and an acid generator (see Non-Patent Document 2), and (3) an accelerator having a hydroxyl group-containing cyclic hydrocarbon group in the ester moiety. A negative type for ArF in which a copolymer of a acrylate ester and an acrylate ester having a carboxyl group-containing cyclic hydrocarbon group in the ester portion is used as a base resin component, and a crosslinking agent and an acid generator similar to those described above are blended therein A resist (see Non-Patent Document 3) has been proposed.

  These negative resists for ArF introduce a carboxyl group-containing bridged polycyclic hydrocarbon group into the resin in order to increase the transparency of the base resin component to ArF excimer laser light and to make it soluble in alkali. The main feature is that an epoxy group or an alcoholic hydroxyl group is introduced into the resin for crosslinking.

  However, in a negative resist having such a composition, a negative pattern can be formed as a result of an ester or ether bond between a crosslinking agent and a base resin component in the presence of an acid by ArF excimer laser light. Since uncrosslinked carboxyl groups and alcoholic hydroxyl groups remain at the portions, there is a drawback that they swell during alkali development, resulting in a rounded resist pattern shape.

Japanese Patent Publication No. 8-3635 (Claims and others) “Journal of Photopolymer Science and Technology (J. Photopolym. Sci. Tech.)”, 1997, Vol. 10, No. 4, p. 579-584 “Journal of Photopolymer Science and Technology (J. Photopolym. Sci. Tech.)”, 1998, Vol. 11, No. 3, p. 507-512 “SPIE Advances in Resist Technology and Processing XIV”, 1998, 3333, p. 417-424

  Under such circumstances, the present invention is a negative resist that provides a resist pattern that is highly transparent to ArF excimer laser light, has high resolution, does not swell, and has a vertical sectional shape. It was made for the purpose of providing a polymer and a copolymer suitable as a resin component of the composition.

  As a result of intensive research to develop a polymer or copolymer suitable as a resin component of a chemically amplified negative resist composition, the present inventors formed esters by reacting with each other in the molecule. A polymer or copolymer having two kinds of functional groups, that is, a hydroxyl group and a carboxyl group, forms an ester in the molecule in the presence of an acid, and becomes alkali-insoluble. When used in combination with an acid generator that generates light by light as a resin component of a negative resist composition, unreacted alkaline hydroxyl groups, carboxyl groups, and carboxylate ester groups are less likely to remain in the resin, so there is little swelling It has been found that a resist pattern can be obtained, and the present invention has been completed based on this finding.

  That is, the present invention relates to a polymer (homopolymer) or copolymer of at least one monomer selected from α- (hydroxyalkyl) acrylic acid and alkyl esters thereof, and (a) α- (hydroxyalkyl). ) Copolymerization of at least one monomer selected from acrylic acid and alkyl ester thereof with at least one monomer selected from (b) ethylenically unsaturated carboxylic acid other than (a) and ester thereof It provides a unity.

  The polymer or copolymer of the present invention includes (1) a polymer (monopolymer) of at least one monomer selected from α- (hydroxyalkyl) acrylic acid and α- (hydroxyalkyl) acrylic acid alkyl ester. A copolymer or copolymer), (2) (a) at least one monomer selected from α- (hydroxyalkyl) acrylic acid and α- (hydroxyalkyl) acrylic acid alkyl ester, and (b) other And a copolymer with at least one monomer selected from ethylenically unsaturated carboxylic acid and ethylenically unsaturated carboxylic acid ester.

  As the polymer of (1), a copolymer of α- (hydroxyalkyl) acrylic acid and α- (hydroxyalkyl) acrylic acid alkyl ester is preferable, and as the copolymer of (2), ( b) What used at least 1 sort (s) chosen from acrylic acid, methacrylic acid, acrylic acid alkylester, and methacrylic acid alkylester as other ethylenically unsaturated carboxylic acid and ethylenically unsaturated carboxylic acid ester of a component preferable.

  Examples of the hydroxyalkyl group in the α- (hydroxyalkyl) acrylic acid and α- (hydroxyalkyl) acrylic acid alkyl ester include lower hydroxyalkyl groups such as hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, hydroxybutyl group, etc. Is mentioned. Among these, a hydroxyethyl group or a hydroxymethyl group is preferable because of the ease of forming an ester.

Examples of the alkyl group of the alkyl ester portion of α- (hydroxyalkyl) acrylic acid alkyl ester include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group. , lower alkyl groups such as amyl group, bicyclo [2.2.1] heptyl, bornyl, adamantyl, tetracyclo [4.4.0.1 ^{2. 5.} 1 ^7.10] dodecyl group, a tricyclo [5.2.1.0 ^{2. 6]} such bridged polycyclic cyclic hydrocarbon group and a decyl group. Those in which the alkyl group of the ester moiety is a polycyclic hydrocarbon group is effective for improving the dry etching resistance. Among these alkyl groups, lower alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group are preferred because alcohol components that form esters can be easily obtained at low cost.

  In the case of a lower alkyl ester, esterification with a hydroxyalkyl group occurs like a carboxyl group, but in the case of an ester with a bridged polycyclic hydrocarbon, such esterification hardly occurs. Therefore, when an ester with a bridged polycyclic hydrocarbon is introduced into the resin, it is preferable that a carboxyl group is present in the resin side chain at the same time.

On the other hand, examples of other ethylenically unsaturated carboxylic acid and ethylenically unsaturated carboxylic acid ester of component (b) in the resin (2) include unsaturated acids such as acrylic acid, methacrylic acid, maleic acid and fumaric acid. Examples thereof include carboxylic acids and alkyl esters of these unsaturated carboxylic acids such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, n-hexyl and octyl esters. Further, the alkyl group of the ester moiety, bicyclo [2.2.1] heptyl, bornyl, adamantyl, tetracyclo [4.4.0.1 ^{2. 5.} 1 ^7.10] dodecyl group, a tricyclo [5.2.1.0 ^{2. 6]} can also be used esters of acrylic acid or methacrylic acid having a bridged polycyclic cyclic hydrocarbon group such as a decyl group.
Among these, lower alkyl esters such as methyl, ethyl, propyl and n-butyl esters of acrylic acid and methacrylic acid are preferred because they are inexpensive and easily available.

  In the copolymer (2), the ratio of the unit derived from the monomer of the component (a) and the unit derived from the monomer of the component (b) is 20:80 to 90:10 by weight ratio. A range of 50:50 to 85:15 is preferred. If the ratio of both units is in the above range, an ester can be easily formed within a molecule or between molecules, and a good resist pattern can be obtained.

  Next, regarding the reaction in which the polymer or copolymer of the present invention forms an ester by dehydration condensation within the molecule by the action of an acid, and the reaction to form an ester between molecules, the hydroxyalkyl group is a hydroxymethyl group. Will be described as an example.

（式中のＲ¹は水素原子、メチル基、エチル基、プロピル基、イソプロピル基、ｎ‐ブチル基、ｓｅｃ‐ブチル基、ｔｅｒｔ‐ブチル基、アミル基などの低級アルキル基、ビシクロ［２．２．１］ヘプチル基、ボルニル基、アダマンチル基、テトラシクロ［４．４．０．１^{2. 5}．１^{7. 10}］ドデシル基、トリシクロ［５．２．１．０^{2. 6}］デシル基などの橋かけ型多環式環状炭化水素基であり、分子内の各Ｒ¹は同一であってもよいし、異なっていてもよい）
で示されるように、酸により分子内でエステル化反応を起こし、環状エステルを形成する。 In the case of the homopolymer or copolymer of (1) (i) Intramolecular ester formation Chemical reaction formula

(In the formula, R ¹ represents a hydrogen atom, a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group or an amyl group; .1] heptyl, bornyl, adamantyl, tetracyclo [4.4.0.1 ^{2. 5} .1 ^{7. 10]} dodecyl group, a tricyclo [5.2.1.0 ^{2. 6]} such as decyl (It is a bridged polycyclic cyclic hydrocarbon group, and each R ¹ in the molecule may be the same or different.)
As shown in FIG. 1, an acid causes an esterification reaction in the molecule to form a cyclic ester.

（式中のＲ¹は前記と同じ意味をもつ）
で示されるように、酸により分子間でエステル化反応を起こし、エステルを形成する。 (B) Formation of intermolecular ester Chemical reaction formula

(R ¹ in the formula have the same meanings as defined above)
As shown in the above, an esterification reaction occurs between molecules with an acid to form an ester.

（式中のＲ¹は前記と同じ意味をもつ）
で示されるように、酸により分子内でエステル化反応を起こし、環状エステルを形成する。 In the case of the copolymer (2) (c) Formation of intramolecular ester Chemical reaction formula

(Wherein R ¹ has the same meaning as above)
As shown in the above, an esterification reaction is caused in the molecule with an acid to form a cyclic ester.

（式中のＲ¹は前記と同じ意味をもつ）
で示されるように、酸により分子間でエステル化反応を起こし、エステルを形成する。
本発明の重合体又は共重合体の分子量は、重量平均分子量２，０００〜２０，０００、好ましくは４，０００〜１５，０００の範囲である。 (D) Formation of intermolecular esters Chemical reaction formula

(Wherein R ¹ has the same meaning as above)
As shown in the above, an esterification reaction occurs between molecules with an acid to form an ester.
The molecular weight of the polymer or copolymer of the present invention ranges from 2,000 to 20,000, preferably from 4,000 to 15,000.

Next, in order to prepare a negative resist composition using the polymer or copolymer of the present invention as a resin component, a compound that generates an acid upon irradiation with radiation (hereinafter simply referred to as an acid generator). ). The acid generator can be appropriately selected from known acid generators used in conventional chemically amplified negative photoresists, and particularly contains an alkyl or halogen-substituted alkyl sulfonate ion as an anion. Onium salts are preferred.
Examples of the cation of the onium salt include a lower alkyl group such as a methyl group, an ethyl group, a propyl group, an n-butyl group and a t-butyl group, and a lower alkoxy group such as a methoxy group and an ethoxy group. Preferred examples include phenyliodonium and sulfonium, and dimethyl (4-hydroxynaphthyl) sulfonium.

  On the other hand, the anion is preferably a fluoroalkylsulfonic acid ion in which some or all of the hydrogen atoms of the alkyl group having about 1 to 10 carbon atoms are substituted with fluorine atoms, and the longer the carbon chain, the more the fluorination rate ( Since the strength as a sulfonic acid decreases as the proportion of the fluorine atom in the alkyl group decreases, a fluoroalkylsulfonic acid ion in which all of the hydrogen atoms of the alkyl group having 1 to 5 carbon atoms are substituted with fluorine atoms is preferred. .

Examples of such onium salts include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate or Nonafluorobutanesulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate or nonafluorobutanesulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate, or nonafluorobutanesulfonate.
In this invention, this acid generator may be used 1 type, and may be used in combination of 2 or more type.

  This negative resist composition can form a negative resist pattern by including only the polymer or copolymer of the present invention and an acid generator, but the intramolecular or molecular in the polymer or copolymer of the present invention. In addition to the formation of interester groups, the formation of ether groups further improves the crosslink density, and in order to improve the resist pattern shape, resolution, and dry etching resistance, a crosslinking agent may be included as desired. it can.

The crosslinking agent is not particularly limited, and any known crosslinking agent conventionally used in chemically amplified negative resists can be appropriately selected and used. Examples of this cross-linking agent include: (1) 2,3-dihydroxy-5-hydroxymethylnorbornane, 2-hydroxy-5,6-bis (hydroxymethyl) norbornane, cyclohexanedimethanol, 3,4,8 (or 9 ) -Trihydroxytricyclodecane, 2-methyl-2-adamantanol, 1,4-dioxane-2,3-diol, 1,3,5-trihydroxycyclohexane, hydroxyl group or hydroxyalkyl group or both An aliphatic cyclic hydrocarbon or an oxygen-containing derivative thereof, and (2) reacting an amino group-containing compound such as melamine, acetoguanamine, benzoguanamine, urea, ethylene urea, glycoluril with formaldehyde or formaldehyde and a lower alcohol, The hydrogen atom of And compounds substituted with a dialkyl group or a lower alkoxymethyl group, such as hexamethoxymethylmelamine, bismethoxymethylurea, bismethoxymethylbismethoxyethyleneurea, tetrakismethoxymethylglycoluril, tetrakisbutoxymethylglycoluril, and the like. Particularly preferred is tetrakisbutoxymethylglycoluril.
In this invention, this crosslinking agent may be used independently and may be used in combination of 2 or more type.

  In this negative resist composition, the acid generator is preferably blended at a ratio of 0.5 to 30 parts by weight with respect to 100 parts by weight of the polymer or copolymer of the present invention. When this amount is less than 0.5 parts by weight, no image is formed. When it exceeds 30 parts by weight, it is difficult to form a uniform solution and storage stability is lowered. In consideration of image forming property and storage stability, the acid generator is particularly preferably blended at a ratio of 1 to 10 parts by weight.

  Moreover, it is preferable to mix | blend the crosslinking agent used depending on necessity in the ratio of 1-50 weight part with respect to 100 weight part of polymers or copolymers of this invention. If this amount is less than 1 part by weight, the effect of improving the crosslinking density is not sufficiently exhibited, and if it exceeds 50 parts by weight, it is difficult to form a uniform solution and storage stability is lowered. Considering the effect of improving the crosslinking density and storage stability, it is particularly preferable to blend this crosslinking agent in a proportion of 5 to 20 parts by weight.

  The negative resist composition is preferably used in the form of a solution in which the above components are dissolved in a solvent. Examples of such solvents include ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptane; ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, diester Polyhydric alcohols and derivatives thereof such as propylene glycol or dipropylene glycol monoacetate or their monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether; cyclic ethers such as dioxane; and lactic acid Methyl, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methoxypro Methyl propionic acid, esters such as ethyl ethoxypropionate, N, N- dimethylformamide, N, N- dimethylacetamide, and the like amide solvents such as N- methyl-2-pyrrolidone. These may be used alone or in combination of two or more.

  In this negative resist composition, if desired, miscible additives such as additional resins, plasticizers, stabilizers, colorants, surfactants and the like for improving the performance of the resist film are commonly used. Can be added and contained.

  With this negative resist composition, a resist pattern can be formed in the same manner as the resist pattern formation of conventionally used photoresist technology. However, in order to carry out the resist pattern suitably, first, on a support such as a silicon wafer. The resist composition solution is applied with a spinner or the like, dried to form a photosensitive layer, which is irradiated with ArF excimer laser light or the like through a desired mask pattern by a reduction projection exposure apparatus or the like, and heated. . Next, this is developed using a developer, for example, an alkaline aqueous solution such as an aqueous solution of 1 to 10% by weight of tetramethylammonium hydroxide. With this formation method, an image faithful to the mask pattern can be obtained.

  The substrate for forming the resist pattern at this time is not particularly limited, and various substrates to which a negative resist is conventionally applied, such as a silicon wafer, a silicon wafer provided with an organic or inorganic antireflection film, Any of a glass substrate etc. may be sufficient.

  The negative resist composition comprising the polymer or copolymer of the present invention as a resin component is a chemically amplified type, is highly transparent to ArF excimer laser light, has high resolution, and swells. And a resist pattern having a vertical cross-sectional shape can be formed.

  Next, the best mode for carrying out the present invention will be described by way of examples, but the present invention is not limited to these examples.

Preparation of α- (hydroxymethyl) ethyl acrylate homopolymer (polymer 1) 32.5 g (10.25 ml) of ethyl α- (hydroxymethyl) acrylate was dissolved in 200 g of tetrahydrofuran, and azobisiso was used as a reaction initiator. 1.62 g of butyronitrile was added and a polymerization reaction was carried out at 70 ° C. for 3 hours. After completion of the reaction, the operation of pouring the reaction product into 1 liter of n-heptane and precipitating the polymer was repeated twice. The polymer thus obtained was dried under reduced pressure at room temperature.
In this way, an α- (hydroxymethyl) ethyl acrylate homopolymer was obtained. The yield of this polymer was 20.5 g, the weight average molecular weight was 12500, and the degree of dispersion was 2.1.

Production of Copolymer (Polymer 2) of α- (hydroxymethyl) acrylic acid and α- (hydroxymethyl) ethyl acrylate 5.1 g (0.05 mol, based on the total amount of monomers) of α- (hydroxymethyl) acrylic acid 20% by mole) and 26.0 g of ethyl α- (hydroxymethyl) acrylate (0.20 mole, 80% by mole based on the total monomers) are dissolved in 200 g of tetrahydrofuran, and azobisiso is used as a reaction initiator. 1.62 g of butyronitrile was added and a polymerization reaction was carried out at 70 ° C. for 3 hours. After completion of the reaction, the operation of pouring the reaction product into 1 liter of n-heptane and precipitating the polymer was repeated twice. The obtained copolymer was dried under reduced pressure at room temperature.
In this way, a copolymer of α- (hydroxymethyl) acrylic acid and ethyl α- (hydroxymethyl) acrylate was obtained. The yield of this copolymer was 23.0 g, the weight average molecular weight was 13500, and the degree of dispersion was 2.2.

Production of copolymer of α- (hydroxymethyl) ethyl acrylate and methacrylic acid (Polymer 3) 26.0 g of ethyl α- (hydroxymethyl) acrylate (0.2 mol, mol% based on the total monomer is 80 mol) %) And 4.3 g of methacrylic acid (0.05 mol, 20 mol% based on the total monomers) are dissolved in 200 g of tetrahydrofuran, and 1.62 g of azobisisobutyronitrile is added as a reaction initiator at 70 ° C. The polymerization reaction was performed for 3 hours. After completion of the reaction, the operation of pouring the reaction product into 1 liter of n-heptane and precipitating the polymer was repeated twice. The obtained copolymer was dried under reduced pressure at room temperature.
In this way, a copolymer of ethyl α- (hydroxymethyl) acrylate and methacrylic acid was obtained. The yield of this copolymer was 19.0 g, the weight average molecular weight was 15500, and the degree of dispersion was 1.9.

で表わされるメタクリル酸カルボキシテトラシクロ［４．４．０．１^{2. 5}．１^{7. 10}］ドデシルエステル１４．５ｇ（０．０５モル）を用いた以外は、実施例３と同様にして、α‐（ヒドロキシメチル）アクリル酸エチルと上記化合物との共重合体を得た。
この共重合体の収量は２０．２ｇであり、重量平均分子量は１４０００で、分散度は１．８であった。 alpha-(hydroxymethyl) ethyl acrylate and methacrylic acid carboxymethyl tetracyclo [4.4.0.1 ^{2. 5. 17.10} ] Production of copolymer with dodecyl ester (polymer 4) In Example 3, instead of 4.3 g of methacrylic acid, the formula

In methacrylic acid represented carboxymethyl tetracyclo [4.4.0.1 ^{2. 5.} 1 ^{7. 10]} except for using the dodecyl ester 14.5 g (0.05 mol) in the same manner as in Example 3, alpha-obtain a copolymer of (hydroxymethyl) acrylate and the compound .
The yield of this copolymer was 20.2 g, the weight average molecular weight was 14000, and the degree of dispersion was 1.8.

Comparative Example 1
Production of Copolymer of Hydroxyethyl Methacrylate and Methacrylic Acid (Polymer 5) 26.0 g of hydroxyethyl methacrylate (0.2 mol, 80% by mol based on the total monomers) and 4.3 g of methacrylic acid (0 0.05 mol, 20% by mol relative to the total monomer) was dissolved in 200 g of tetrahydrofuran, 1.62 g of azobisisobutyronitrile was added as a reaction initiator, and a polymerization reaction was carried out at 70 ° C. for 3 hours. After completion of the reaction, the reaction product was poured into 1 liter of n-heptane to precipitate a polymer, and the obtained copolymer was dried under reduced pressure at room temperature.
In this way, a copolymer of hydroxyethyl methacrylate and methacrylic acid was obtained. The yield of this copolymer was 20.0 g, the weight average molecular weight was 11000, and the degree of dispersion was 1.75.

Comparative Example 2
Hydroxyethyl methacrylate and methacrylic acid carboxymethyl tetracyclo [4.4.0.1 ^{2. 5.} 1 ^7.10] copolymers of dodecyl ester in Comparative Production Example 1 of (Polymer 6), in place of methacrylic acid 4.3 g, methacrylic acid carboxymethyl tetracyclo [4.4.0.1 ^{2. 5.} 1 ^7.10] except for using the dodecyl ester 14.5 g (0.05 mol) is in the same manner as in Comparative Example 1, to obtain a copolymer of hydroxyethyl methacrylate and the compound.
The yield of this copolymer was 14.0 g, the weight average molecular weight was 16000, and the degree of dispersion was 2.0.

Reference example 1
A negative resist solution was obtained by dissolving 100 parts by weight of the polymer (polymer 1) obtained in Example 1 and 3 parts by weight of triphenylsulfonium trifluoromethanesulfonate in 670 parts by weight of propylene glycol monomethyl ether.
Next, this resist solution was applied onto a silicon wafer using a spinner and prebaked on a hot plate at 120 ° C. for 90 seconds to form a resist layer having a thickness of 0.5 μm. Next, ArF excimer laser light (193 nm) was selectively irradiated with an ArF exposure apparatus (manufactured by Nikon Corporation), followed by heating (PEB) at 150 ° C. for 30 minutes, and then 2.38 wt% tetramethylammonium hydroxide. Paddle development was carried out with an aqueous solution for 65 seconds, washed with water for 30 seconds and dried.
A resist pattern of 0.50 μm was formed by such an operation, and the exposure amount at that time was measured in mJ / cm ² (energy amount) unit as sensitivity, and it was 100 mJ / cm ² . Moreover, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a resist pattern without swelling.

Reference example 2
In Reference Example 1, a negative resist solution was prepared in the same manner as in Reference Example 1 except that the polymer 1 was replaced with the same amount of the polymer 2, and then a resist pattern was formed under the same conditions as in Reference Example 1.
Such resist pattern 0.40μm in operation is formed, was measured exposure amount in the mJ / cm ² (energy amount) as sensitivity units, it was 70 mJ / cm ^2. Moreover, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a resist pattern without swelling.

Reference example 3
In Reference Example 1, a negative resist solution was prepared in the same manner as in Reference Example 1 except that the polymer 1 was replaced with the same amount of the polymer 3, and then a resist pattern was formed under the same conditions as in Reference Example 1.
Such resist pattern 0.30μm in operation is formed, was measured exposure amount in the mJ / cm ² (energy amount) as sensitivity units, it was 68mJ / cm ^2. Moreover, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a resist pattern without swelling.

Reference example 4
In Reference Example 1, a negative resist solution was prepared by further blending 10 parts by weight of tetrakismethoxymethylglycoluril as a cross-linking agent. Then, in Reference Example 1, prebaking was performed at 100 ° C. for 90 seconds, and PEB at 120 ° C. for 90 seconds. A resist pattern was formed under the same conditions as described above.
Such resist pattern 0.30μm in operation is formed, was measured exposure amount in the mJ / cm ² (energy amount) as sensitivity units, it was 90 mJ / cm ^2. Moreover, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a trapezoidal resist pattern without swelling.

Reference Example 5
In Reference Example 2, a negative resist solution was prepared by further blending 10 parts by weight of tetrakismethoxymethylglycoluril as a cross-linking agent. Then, in Reference Example 2, prebaking was performed at 100 ° C. for 90 seconds, and PEB at 120 ° C. for 90 seconds. A resist pattern was formed under the same conditions as described above.
Such resist pattern 0.20μm in operation is formed, was measured exposure amount in the mJ / cm ² (energy amount) as sensitivity units, it was 40 mJ / cm ^2. Moreover, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a vertical resist pattern without swelling.

Reference Example 6
In Reference Example 3, a negative resist solution was prepared by further blending 10 parts by weight of tetrakismethoxymethylglycoluril as a cross-linking agent. Then, in Reference Example 3, pre-baking was performed at 100 ° C. for 90 seconds, and PEB at 120 ° C. for 90 seconds. A resist pattern was formed under the same conditions as described above.
Such resist pattern 0.18μm in operation is formed, was measured exposure amount in the mJ / cm ² (energy amount) as sensitivity units, it was 40 mJ / cm ^2. Moreover, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a very good vertical resist pattern without swelling.

Reference Example 7
In Reference Example 1, a negative resist solution was prepared in the same manner as in Reference Example 1 except that 10 parts by weight of tetrakismethoxymethylglycoluril was added as a crosslinking agent in place of the same amount of polymer 1 as polymer 4. Next, a resist pattern was formed under the same conditions as in Reference Example 4.
Such resist pattern 0.20μm in operation is formed, was measured exposure amount in the mJ / cm ² (energy amount) as sensitivity units, it was 35 mJ / cm ^2. Moreover, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a resist pattern without swelling.

Reference Example 8
100 parts by weight of the polymer obtained in Example 1, 3 parts by weight of triphenylsulfonium trifluoromethanesulfonate, and 10 parts by weight of tetrakisbutoxymethylglycoluril were dissolved in 500 parts by weight of propylene glycol monomethyl ether to obtain a negative resist solution.
Next, this resist solution was applied onto a silicon wafer using a spinner and prebaked on a hot plate at 100 ° C. for 90 seconds to form a resist layer having a thickness of 0.5 μm. Next, an ArF excimer laser (193 nm) was selectively irradiated with an ArF exposure apparatus (manufactured by Nikon Corporation), then subjected to PEB treatment at 120 ° C. for 90 seconds, and then 65% with a 2.38 wt% tetramethylammonium hydroxide aqueous solution. Paddle development was performed for 2 seconds, followed by washing with water for 30 seconds and drying.
Such resist pattern 0.20μm in operation is formed, was measured exposure amount in the mJ / cm ² (energy amount) as sensitivity units, it was 32 mJ / cm ^2. Moreover, when the cross-sectional shape of the resist pattern was observed with an SEM (scanning electron microscope) photograph, it was a good resist pattern with very high perpendicularity without swelling.

Reference Example 9
In Reference Example 1, a negative resist solution was prepared in the same manner as in Reference Example 1 except that the polymer 1 was replaced with the same amount of the polymer 5, and then a resist pattern was formed under the same conditions as in Reference Example 1.
When the cross-sectional shape of the resist pattern obtained by such an operation was observed with a SEM (scanning electron microscope) photograph, it was swollen and the resist pattern was connected.

Reference Example 10
In Reference Example 4, a negative resist solution was prepared in the same manner as in Reference Example 4 except that the polymer 1 was replaced with the same amount of the polymer 5, and then a resist pattern was formed under the same conditions as in Reference Example 4.
A resist pattern of 0.18 μm was formed by such an operation, and the exposure amount at that time was measured in mJ / cm ² (energy amount) unit as sensitivity, and it was 50 mJ / cm ² . However, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a defective resist pattern in which the swollen resist top portion protruded sideways.

Reference Example 11
In Reference Example 1, a negative resist solution was prepared in the same manner as in Reference Example 1 except that the polymer 1 was replaced with the same amount of the polymer 6 and 10 parts by weight of tetrakismethoxymethylglycoluril was further added as a crosslinking agent. Next, a resist pattern was formed under the same conditions as in Reference Example 4.
Such 0.25μm resist pattern operations is formed, the measured exposure amount at that time mJ / cm ² (energy amount) as sensitivity units, was 70 mJ / cm ^2. Moreover, when the cross-sectional shape of the resist pattern was observed with a SEM (scanning electron microscope) photograph, it was a swollen resist pattern.

  The polymer and copolymer of the present invention are useful as a resin component of a chemically amplified negative resist composition.

Claims (5)

  A polymer or copolymer of at least one monomer selected from α- (hydroxyalkyl) acrylic acid and alkyl esters thereof.   (A) at least one monomer selected from α- (hydroxyalkyl) acrylic acid and alkyl esters thereof; and (b) at least selected from ethylenically unsaturated carboxylic acids other than (a) and esters thereof. Copolymer with one monomer.   The copolymer according to claim 2, wherein the component (b) is at least one selected from acrylic acid, methacrylic acid, alkyl acrylate ester and alkyl methacrylate ester.   The ratio according to claim 2 or 3, wherein the ratio of the unit derived from the monomer of component (a) to the unit derived from the monomer of component (b) is in the range of 20:80 to 90:10 by weight. Polymer. The polymer or copolymer according to any one of claims 1 to 4, which has a weight average molecular weight in the range of 2,000 to 20,000.