JP2007065504A - Resist composition and method for producing polymer for resist - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a resist composition having high transparency with respect to far-ultraviolet rays and radiation and moreover, superior in basic properties as a resist, such as sensitivity, resolution, dry etching resistance, pattern shape and line edge roughness. <P>SOLUTION: The resist composition contains a polymer having at least one kind of repeating unit derived from an acrylic ester derivative or the like and having an acid dissociable group which increases the solubility with respect to alkali developer, and an acid generator capable of generating an acid upon irradiation with light or radiation. The polymer has an absorbance at 193 nm of ≤1.0 (l/μm) and degree of dispersion of ≤1.4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resist composition and a method for producing a resist polymer.

  In recent years, in the manufacture of semiconductor elements and liquid crystal display elements, miniaturization has rapidly progressed due to advances in lithography technology. As a technique for miniaturization, the wavelength of an exposure light source is generally shortened. Specifically, ultraviolet rays typified by g-line and i-line have been used in the past, but now far-ultraviolet rays typified by KrF excimer laser (248 nm) and ArF excimer laser (193 nm) have been introduced into mass production. ing.

  A resist using these as a radiation source is required to have high resolution and high sensitivity capable of reproducing a pattern with a fine dimension. As one of the resists satisfying such conditions, a chemically amplified positive resist composition containing a base resin whose alkali solubility is increased by the action of an acid and an acid generator that generates an acid upon exposure is known.

  In a chemically amplified positive resist, an acid is generated from an acid generator in the resist by exposure, and a reaction between the acid and the base resin occurs. The acid-catalyzed chain reaction proceeds by baking after exposure, and the solubility of the base resin in the alkaline solution changes. Thereby, very high sensitivity can be obtained as compared with the conventional non-chemically amplified resist.

In addition to resolution, the resist is required to have various characteristics such as sensitivity, dry etch resistance, low line edge roughness of the pattern, and low density dependency of the pattern. In particular, the finer the pattern, the greater the influence of line edge roughness, so a resist that satisfies the low line edge roughness is required. As a means for satisfying this, a resin having a low dispersion is used for the resist material. The low dispersion resin can be obtained by a living polymerization method. Such conventional living polymerization methods are described in Patent Documents 1 to 3.
JP 2004-352989 A JP 2005-139250 A JP 2005-10488 A

  However, the conventional living polymerization method has a problem that it is difficult to obtain a resin having a dispersion of 1.4 or less with high efficiency and stability. In addition, since polymerization is performed using a chain transfer agent, there is a problem in that a compound derived from the chain transfer agent is bonded to the terminal group of the resin, and transparency that satisfies the characteristics as a resist cannot be obtained.

  The present invention enables realization of a resist composition having high transparency to deep ultraviolet rays and radiation, and excellent basic characteristics as a resist such as sensitivity, resolution, dry etch resistance, pattern shape, and line edge roughness. With the goal.

  In order to solve the above-mentioned object, the present invention is configured such that the resist composition contains a monodispersed polymer having low absorbance.

  Specifically, the resist composition according to the present invention comprises (A) a polymer having at least one repeating unit represented by the general formula (I) and having an acid-dissociable group that increases solubility in an alkaline developer, (B) It contains an acid generator that generates an acid upon irradiation with light or radiation, and the polymer (A) has an absorbance at 193 nm of 1.0 (1 / μm) or less and a dispersity of 1.4 or less. It is characterized by being.

  According to the resist composition of the present invention, since the polymer (A) has an absorbance at 193 nm of 1.0 (1 / μm) or less and a dispersity of 1.4 or less, the transparency of the resist is high, In addition to exhibiting excellent characteristics as a resist, it is possible to keep line edge roughness low.

In the resist composition of the present invention, in general formula (I), R ₁ is a hydrogen atom or an alkyl group having 4 or less carbon atoms, and R ₂ is an isobutyl group, a tert-butyl group, a tert-amyl group, a benzyl group, Group, cyclohexyl group, anthracenyl group, hydroxyethyl group, cinnamyl group, adamantyl group, methyladamantyl group, ethyladamantyl group, isobornyl group, ethoxyethyl group, methoxypropyl group, methoxyethoxyl group, oxotetrahydrofuran group, hydroxytrimethylpropyl group, It is preferably any one group selected from the group consisting of an oxo-oxatricyclononyl group, a naphthyl group, a phenylethyl group, and a phenyl group. By setting it as such a structure, the polymer (A) containing an acid dissociable group can be obtained reliably.

  In the resist composition of the present invention, the polymer (A) is preferably a polymer polymerized by a living radical polymerization method using cyanopropyldithionaphthoate (CPDN) as a chain transfer agent. By setting it as such a structure, it becomes possible to obtain a polymer (A) with low dispersion degree reliably. Also, the absorbance can be kept low.

  In the resist composition of the present invention, the polymer (A) is preferably a polymer having a terminal group treated with 2,2'-azobisisobutyronitrile (AIBN). By setting it as such a structure, the light absorbency of a polymer (A) can be reliably made into 1.0 or less.

  In the resist composition of the present invention, the polymer (A) has a residue derived from cyanopropyldithionaphthoate (CPDN) or 2,2′-azobisisobutyronitrile (AIBN) in at least a part of the molecular terminals. It is preferable to have. By setting it as such a structure, the light absorbency of a polymer (A) can be reliably made into 1.0 or less.

  The method for producing a resist polymer according to the present invention comprises a resist polymer having an acid dissociable group having at least one repeating unit represented by formula (I) and having increased solubility in an alkali developer. A production method comprising a living radical polymerization step using cyanopropyldithionaphthoate (CPDN) as a chain transfer agent.

  According to the method for producing a resist polymer of the present invention, since it has a living radical polymerization step using cyanopropyldithionaphthoate (CPDN) as a chain transfer agent, the resist polymer has low absorbance and low dispersity. Can be obtained reliably.

In the method for producing a resist polymer of the present invention, in general formula (I), R ₁ is a hydrogen atom or an alkyl group having 4 or less carbon atoms, and R ₂ is an isobutyl group, a tert-butyl group, a tert- Amyl group, benzyl group, cyclohexyl group, anthracenyl group, hydroxyethyl group, cinnamyl group, adamantyl group, methyladamantyl group, ethyladamantyl group, isobornyl group, ethoxyethyl group, methoxypropyl group, methoxyethoxyl group, oxotetrahydrofuran group, hydroxy It is preferably any one group selected from the group consisting of trimethylpropyl group, oxo-oxatricyclononyl group, naphthyl group, phenylethyl group and phenyl group.

  The method for producing a resist polymer of the present invention preferably further comprises a step of end group treatment with 2,2'-azobisisobutyronitrile (AIBN). By setting it as such a structure, the light absorbency of the polymer for resists can further be reduced.

  According to the method for producing a resist composition and a resist polymer of the present invention, basic properties as a resist such as high transparency to deep ultraviolet rays and radiation, and sensitivity, resolution, dry etch resistance, pattern shape, line edge roughness, etc. Can realize an excellent resist composition.

  The resist composition and resist polymer of the present invention are described in detail below.

-Polymer (A)-
The polymer (A) of the present invention has at least one structural unit introduced from an acrylic ester or methacrylic ester represented by the general formula (I). R ₁ is not limited to acrylic acid ester or methacrylic acid ester, and R ₁ is selected from the group consisting of hydrogen atom and methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and tert-butyl group. Any group may be used. R ₂ is an isobutyl group, tert-butyl group, tert-amyl group, benzyl group, cyclohexyl group, anthracenyl group, hydroxyethyl group, cinnamyl group, adamantyl group, methyladamantyl group, ethyladamantyl group, isobornyl group, ethoxyethyl Any group selected from the group consisting of a group, a methoxypropyl group, a methoxyethoxyl group, an oxotetrahydrofuran group, a hydroxytrimethylpropyl group, an oxo-oxatricyclononyl group, a naphthyl group, a phenylethyl group and a phenyl group may be used.

  Further, the degree of dispersion (weight average molecular weight / number average molecular weight, Mw / Mn) of the polymer (A) is 1.4 or less. When the molecular weight dispersity exceeds 1.4, the line edge roughness of the resist pattern increases, and the characteristics as a resist deteriorate significantly.

  In order to reduce the degree of dispersion of the polymer (A), polymerization may be carried out using living radical polymerization (RAFT multiple method) using a chain transfer agent CPDN represented by the formula (II). According to this polymerization method, since there is almost no chain termination reaction or chain transfer reaction, the active species at the growth end is retained for a long time. For this reason, all the monomers enter the polymer, and the terminal active species are alive without being deactivated even when the polymerization is completed. In general, a polymer having this kind of active terminal is called a living polymer. According to this polymerization method, a polymer having a narrow molecular weight distribution can be obtained.

  Further, after the monomer is consumed and the polymerization is completed, when the monomer is added again, the growth reaction is resumed. When a different monomer is added, a block copolymer is formed. It is also an advantage of this method that the continuous length of each monomer can be freely adjusted.

  For example, 2,2′-azobisisobutyronitrile (AIBN), which is a polymerization initiator represented by the formula (III), is added to 1 part by weight of the repeating unit represented by the general formula (I). 50 to 600 parts by weight of the original monomer and 0.1 to 10 parts by weight of CPDN as a chain initiator are added and stirred in a benzene solution for 1 to 50 hours. More preferably, with respect to 1 mol of the polymerization initiator, the monomer is added in an amount of 20 to 300 mol, and the chain initiator is added in an amount of 0.5 to 5 mol, followed by stirring in a tetrahydrofuran solution for 4 to 15 hours. Thereby, a polymer (A) having a narrow molecular weight distribution with a dispersity of 1.4 or less can be obtained. The solution used as the reaction field is not limited to tetrahydrofuran.

  When CPDN is used as the chain initiator, the resin end group is a compound represented by the formula (III) which is a coloring group, and therefore, the transparency to the wavelength of 193 nm is high, and the transmittance is 30% to 60% (1 / μm) of polymer is obtained. This polymer has an absorbance of 1.0 (1 / μm) and has transparency necessary for a resist.

  Furthermore, by reacting with AIBN in tetrahydrofuran as a terminal group treatment method, the terminal group represented by the formula (III) is substituted with a cyano group which is a compound derived from AIBN, and the transparency of the resin is further improved.

  For example, 0.1 to 10 parts by weight of AIBN is used for 1 part by weight of the polymer (A), and the reaction is performed in tetrahydrofuran for 1 to 50 hours. More preferably, 0.5 to 5 parts by weight of AIBN is added to 1 part by weight of the polymer (A), and the reaction is carried out in tetrahydrofuran for 2 to 20 hours. As a result, a polymer (A) having a further improved transmittance of 10% to 20% (1 / μm) is obtained.

-Acid generator (B)-
The acid generator (B) is a photoacid generator, and is a compound that generates an acid when irradiated with high-energy radiation. Preferred acid generators (B) include sulfonium salts, iodonium salts, sulfonyldiazomethane, and N-sulfonyloxyimide. These photoacid generators can be used alone or in admixture of two or more. The usage-amount of an acid generator is 0.1-25 weight part per 100 weight part of solids in a composition, Preferably it is 1-15 weight part. In this case, if the amount of the acid generator used is too small, the sensitivity and resolution are lowered. On the other hand, when the amount is too large, transparency to radiation is lowered, and it tends to be difficult to obtain a rectangular resist pattern.

  Specifically, the acid generator (B) is a triphenylsulfonium salt compound, such as triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium 2-bicyclo [2.2. 1] Hept-2-yl-1,1,2,2 tetrafluoroethanesulfonate, triphenylsulfonium camphorsulfonate and the like are preferable.

  Also, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-, which are 4-cyclohexylphenyldiphenylsulfonium salt compounds. Octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium-2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, etc. It may be.

  Further, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n, which are 4-cyclohexylphenyldiphenylsulfonium salt compounds. -Octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, etc. It may be.

  Further, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2, which are diphenyliodonium salt compounds. -Yl-1,1,2,2-tetrafluoroethanesulfonate, diphenyliodonium camphorsulfonate, etc. may be sufficient.

  Further, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, which is a bis (4-t-butylphenyl) iodonium salt compound, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2 -Tetrafluoroethane sulfonate, bis (4-t-butylphenyl) iodonium camphor sulfonate, etc. may be sufficient.

  Further, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium salt compound, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- ( 4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1 -(4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4 -N-Butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate It may be equal.

  In addition, 1- (6-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, which is a 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium salt compound, 1- ( 6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1 -(6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (6 -N-Butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfo It may be an over door or the like.

  In addition, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium salt compound, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- ( 3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1 -(3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3 , 5-Dimethyl-4-hydroxyphenyl) tetrahydrothiofe It may be um camphorsulfonate and the like.

  In addition, N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene which is a bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide compound or the like. -2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n- Octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2 , 2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (2- (3-tetracyclo [4.4.0.1.1.1). ] Dodecany ) -1,1-difluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept- 5-ene-2,3-dicarboximide or the like may be used.

-Additives-
The resist composition of the present invention includes an acid diffusion controller, an alicyclic additive having an acid dissociable group, an alicyclic additive not having an acid dissociable group, a surfactant, and a sensitizer as necessary. Various additives such as these may be blended.

  The acid diffusion control agent is a component having an action of controlling a diffusion phenomenon of an acid generated from an acid generator upon irradiation in a resist film and suppressing an undesirable chemical reaction in a non-irradiated region.

  By blending such an acid diffusion controller, the storage stability of the resulting radiation-sensitive resin composition is improved, and the resolution as a resist is further improved. Furthermore, a change in the line width of the resist pattern due to fluctuations in the holding time (PED) from irradiation to development processing can be suppressed, and a composition excellent in process stability can be obtained.

  As the acid diffusion controller, a nitrogen-containing organic compound whose basicity does not change by irradiation or heat treatment during the resist pattern forming process is preferable. Examples of such nitrogen-containing organic compounds include “tertiary amine compounds”, “amide group-containing compounds”, “quaternary ammonium hydroxide compounds”, “nitrogen-containing heterocyclic compounds”, and the like.

  Examples of the “tertiary amine compound” include triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n. -Tri (cyclo) alkylamines such as octylamine, cyclohexyldimethylamine, tricyclohexylamine; alkanolamines such as triethanolamine, diethanolaniline; N, N, N ', N'-tetramethylethylenediamine, N, N , N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzenetetramethylenediamine, 2,2-bis (4-amino) Phenyl) propane, 2- (3-aminophenyl) -2- (4) -Aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-aminophenyl) -2- (4-hydroxyphenyl) propane, 1,4-bis [ 1- (4-aminophenyl) -1-methylethyl] benzene, 1,3-bis [1- (4-aminophenyl) -1-methylethyl] benzene, bis (2-dimethylaminoethyl) ether, bis ( 2-diethylaminoethyl) ether and the like.

  Examples of the “amide group-containing compound” include Nt-butoxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, N- t-butoxycarbonyldicyclohexylamine, N-t-butoxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-N-methyl-1-adamantylamine, N, N-di-t-butoxycarbonyl-1-adamantylamine N, N-di-t-butoxycarbonyl-N-methyl-1-adamantylamine, Nt-butoxycarbonyl-4,4′-diaminodiphenylmethane, N, N′-di-t-butoxycarbonylhexamethylenediamine N, N, N ′, N′-tetra-t-butoxycarbonylhexamethyl Tylenediamine, N, N′-di-t-butoxycarbonyl-1,7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t- Butoxycarbonyl-1,9-diaminononane, N, N′-di-t-butoxycarbonyl-1,10-diaminodecane, N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N '-Di-t-butoxycarbonyl-4,4'-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenz Imidazole, Nt-butoxycarbonyl-pyrrolidine, Nt-butoxycarbonyl-piperidine, Nt-buto In addition to Nt-butoxycarbonyl group-containing amino compounds such as cycarbonyl-4-hydroxy-piperidine, Nt-butoxycarbonyl-morpholine, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N- Examples thereof include methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like.

  Examples of the “quaternary ammonium hydroxide compound” include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, and the like.

  Examples of the “nitrogen-containing heterocyclic compound” include imidazoles such as imidazole, 4-methylimidazole, 1-benzyl-2-methylimidazole, 4-methyl-2-phenylimidazole, benzimidazole, 2-phenylbenzimidazole; In addition to piperazines such as piperazine, 1- (2-hydroxyethyl) piperazine, pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 3-piperidino-1,2-propanediol, morpholine, 4-methylmorpholine, Examples include 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane and the like.

  Of the nitrogen-containing heterocyclic compounds, tertiary amine compounds, amide group-containing compounds, and nitrogen-containing heterocyclic compounds are preferred, and among the amide group-containing compounds, Nt-butoxycarbonyl group-containing amino compounds are preferred, and nitrogen-containing compounds are preferred. Among the complex compounds, imidazoles are preferable.

  The acid diffusion controller can be used alone or in admixture of two or more. The compounding amount of the acid diffusion controller is usually 15 parts by weight or less, preferably 10 parts by weight or less, and more preferably 5 parts by weight or less with respect to 100 parts by weight of the acrylic polymer. In this case, when the compounding amount of the acid diffusion controller exceeds 15 parts by weight, the sensitivity as a resist and the developability of the radiation irradiated part tend to be lowered. In order to exhibit the function as an acid diffusion control agent, the blending amount is preferably 0.001 part by weight or more.

  In addition, an alicyclic additive having an acid dissociable group or an alicyclic additive not having an acid dissociable group is a component that further improves dry etching resistance, pattern shape, adhesion to a substrate, and the like. It is.

  Examples of such alicyclic additives include 1-adamantanecarboxylic acid t-butyl, 1-adamantanecarboxylic acid t-butoxycarbonylmethyl, 1-adamantanecarboxylic acid α-butyrolactone ester, 1,3-adamantane dicarboxylic acid diester. -T-butyl, 1-adamantane acetate t-butyl, 1-adamantane acetate t-butoxycarbonylmethyl, 1,3-adamantanediacetate di-t-butyl, 2,5-dimethyl-2,5-di (adamantylcarbonyl Adamantane derivatives such as oxy) hexane; deoxycholate t-butyl, deoxycholate t-butoxycarbonylmethyl, deoxycholate 2-ethoxyethyl, deoxycholate 2-cyclohexyloxyethyl, deoxycholate 3-oxocyclohexyl, Deoxycor Deoxycholic acid esters such as tetrahydropyranyl acid, deoxycholic acid mevalonolactone ester; tert-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid, 2-cyclohexyloxyethyl lithocholic acid, lithol Lithocholic acid esters such as 3-oxocyclohexyl acid, tetrahydropyranyl lithocholic acid, mevalonolactone ester of lithocholic acid; dimethyl adipate, diethyl adipate, dipropyl adipate, di-n-butyl adipate, di-t-butyl adipate And alkyl carboxylic acid esters.

  These alicyclic additives can be used alone or in admixture of two or more. The compounding amount of the alicyclic additive is usually 50 parts by weight or less, preferably 30 parts by weight or less, with respect to 100 parts by weight of the acrylic polymer. In this case, when the blending amount of the alicyclic additive exceeds 50 parts by weight, the heat resistance as a resist tends to decrease.

  Further, the surfactant as an additive is a component having an effect of improving coating property, striation, developability and the like.

  Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, and polyethylene glycol dilaurate. And nonionic surfactants such as polyethylene glycol distearate.

  Further, the sensitizer as an additive has an action of absorbing radiation energy and transmitting the energy to the acid generator, thereby increasing the amount of acid generated. The radiation-sensitive resin composition It has the effect of improving the apparent sensitivity.

  Examples of such a sensitizer include carbazoles, benzophenones, rose bengals, anthracenes, phenols and the like.

  These sensitizers can be used alone or in admixture of two or more. The blending amount of the sensitizer is preferably 50 parts by weight or less with respect to 100 parts by weight of the acrylic polymer.

  Further, additives other than those mentioned above include antihalation agents, adhesion assistants, storage stabilizers, antifoaming agents and the like.

-Solvent-
The resist composition of the present invention is usually dissolved in a solvent so that the total solid concentration is usually 3 to 50% by weight, preferably 5 to 25% by weight. A composition solution is prepared by filtering with a filter of about 2 μm.

  Examples of the solvent used for preparing the resist composition solution include linear or branched ketones such as 2-pentanone, 2-hexanone, 2-heptanone, and 2-octanone; and cyclopentanone and cyclohexanone. Cyclic ketones; propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate; 2-hydroxypropionate alkyls such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate; In addition to alkyl 3-alkoxypropionates such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate and ethyl 3-ethoxypropionate, ethylene glycol Monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, n-butyl acetate, methyl pyruvate, pyrubin Examples thereof include ethyl acid, N-methylpyrrolidone, and γ-butyrolactone.

  These solvents can be used alone or in admixture of two or more, but propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 2-heptanone, cyclohexanone, γ-butyrolactone, ethyl 2-hydroxypropionate, 3-ethoxy It is preferable to contain at least one selected from ethyl propionate. However, cyclohexanone is an effective solvent from the viewpoint of solubility, but it is preferable to avoid its use as much as possible because of its toxicity.

-Formation of resist pattern-
A resist pattern can be formed using the chemically amplified resist composition described above. The resist pattern is formed by a step of forming a resist film, a step of selectively irradiating the resist film with exposure light to perform pattern exposure, and developing the resist film subjected to pattern exposure to develop a resist pattern. Forming a pattern.

  When forming a resist pattern from the resist composition of the present invention, for example, a substrate or a substrate on which a lower layer film has been formed in advance by an appropriate application means such as spin coating, cast coating, roll coating or the like. To form a resist film. The formed resist film is subjected to heat treatment (hereinafter referred to as PB treatment) in advance as necessary, and then exposed to form a predetermined resist pattern. The radiation used at that time is preferably radiation having a wavelength of 200 nm or less, and particularly ArF excimer laser (wavelength 193 nm) is preferred.

  In the present invention, it is preferable to perform a heat treatment (hereinafter referred to as PEB treatment) after exposure. The heating condition for PEB treatment varies depending on the composition of the resist composition, but is usually 30 to 200 ° C, preferably 50 to 170 ° C.

  In the present invention, an organic or inorganic lower layer film can be formed on the substrate to be used, and a protective film can be provided on the resist film.

  Next, a predetermined resist pattern is formed by developing the exposed resist film. Examples of the developer used for development include sodium hydroxide, potassium hydroxide, aqueous ammonia, ethylamine, diethylamine, triethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo. An alkaline aqueous solution in which at least one of alkaline compounds such as [5.4.0] -7-undecene and 1,5-diazabicyclo- [4.3.0] -5-nonene is dissolved is preferable. Further, an organic solvent or a surfactant can be added to the developer composed of the alkaline aqueous solution. In addition, after developing with the developing solution which consists of alkaline aqueous solution, generally it wash | cleans with water and dries.

  The positive resist composition of the present invention has high transparency to deep ultraviolet rays and radiation. Moreover, when forming a resist pattern, it has various functions as a resist such as dry etch resistance, pattern shape, and line edge roughness. In addition, it is excellent in resolution and is extremely useful as a chemically amplified resist, and can be suitably used for the manufacture of LSIs that are expected to become increasingly finer in the future.

  Hereinafter, the embodiments of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

(Example)
-Synthesis of RAFT reagent (CPDN) used for RAFT polymerization-
A 300 ml 4-neck round bottom flask containing magnesium (1.29 g, 53 mmol) was charged with 20 ml of dry tetrahydrofuran (THF), and a solution of 1-bromonaphthalene (10.0 g, 48 mmol) diluted with 20 ml of THF was added dropwise. added. After the dropwise addition, the mixture was refluxed for 1 hour.

  Next, 3.68 g (48 mmol) of carbon disulfide was added to the solution at room temperature and refluxed for 6 hours.

  The reaction mixture was then poured into water and acidified with diluted hydrochloric acid. The solution was extracted with chloroform (40 ml) and the solvent was removed.

  40 ml of ethyl acetate was added to the residue, and reacted with 2.1 g of dimethyl sulfoxide (DMSO) under nitrogen flow for 10 hours at room temperature. 5.38 g (32.8 mmol) of AIBN was added to the mixture and refluxed for 23 hours. After removing the solvent, crude CPDN was obtained.

The CPDN of the composition was purified by column chromatography (silica, developing solvent: n-hexane: ethyl acetate = 5: 1). The yield was 9.01 g and the yield was 68.7%. When the obtained CPDN was analyzed by ¹ H-NMR, the results shown in Table 1 were obtained.

The measurement was performed by dissolving CPND in CDCl ₃ .

-Synthesis of acid-dissociable group-containing polymer-
3.000 g (17.6 mmol) of γ-butyrolactone-2-yl methacrylate (GBLMA), 6.864 g (29.3 mmol) of 2-methyl-2-adamantyl methacrylate (MADMA), and 1-methyl-1- 1.97 g (8.79 mmol) of (6-methyl-7-oxabicyclo [4.1.0] hept-3-yl) ethyl methacrylate (MOBH) and 114 mg (0.70 mmol) of AIBN as a polymerization initiator As a RAFT reagent, 189 mg (0.70 mmol) of CPDN was dissolved in 12.77 ml of THF and charged into the polymerization tube.

  After freeze degassing three times, the reaction was carried out at 55 ° C. for 5.5 hours. Purification by reprecipitation three times with methanol-THF system gave 6.14 g (yield 51.7%) of powdered orange polymer.

Purification was confirmed by the disappearance of the double bond peak in ¹ H-NMR. At this time, the dispersity (Mw / Mn) of the polymer was 1.37, and the absorbance was 0.40 (1 / μm) with respect to the wavelength of 193 nm.

-Terminal AIBN treatment-
5.1 g (0.91 mmol) of the polymer synthesized in Example 2 and 3 equivalents of 447 mg (2.72 mmol) of AIBN with respect to the terminal dithioester were dissolved in 18.0 ml of 2 anhydrous THF, charged into a polymerization tube, and freeze-defrosted 3 times. After that, the reaction was carried out at 55 ° C. for 13 hours. After the reaction, it was dropped into methanol, and the obtained polymer was purified by reprecipitation once using a THF-methanol system. The weight of the obtained polymer was 4.44 g (yield 87%). It was confirmed from the vacuum ultraviolet spectral analysis that terminal conversion had progressed 90.3%.

  Further terminal conversion was performed. The operation is the same as above. The obtained polymer was 4.16 g (yield 94%). It was confirmed from the vacuum ultraviolet spectrum analysis that terminal conversion had progressed 96.8%. At this time, the dispersity (Mw / Mn) was 1.34, and the absorbance was 0.26 (1 / μm) for a wavelength of 193 nm.

The resist composition of the present invention is highly transparent to deep ultraviolet rays and radiation, and can realize a resist composition having excellent basic characteristics as a resist such as sensitivity, resolution, dry etch resistance, pattern shape, and line edge roughness. It has an effect and is useful as a method for producing a resist composition and a resist polymer.

Claims (8)

(A) a polymer having at least one repeating unit represented by formula (I) and having an acid-dissociable group that increases the solubility in an alkali developer;
(B) contains an acid generator that generates acid upon irradiation with light or radiation,
The polymer (A) has an absorbance at 193 nm of 1.0 (1 / μm) or less and a dispersity of 1.4 or less.

In the general formula (I), R ₁ is a hydrogen atom or an alkyl group having 4 or less carbon atoms,
R ₂ is an isobutyl group, tert-butyl group, tert-amyl group, benzyl group, cyclohexyl group, anthracenyl group, hydroxyethyl group, cinnamyl group, adamantyl group, methyladamantyl group, ethyladamantyl group, isobornyl group, ethoxyethyl group , A methoxypropyl group, a methoxyethoxyl group, an oxotetrahydrofuran group, a hydroxytrimethylpropyl group, an oxo-oxatricyclononyl group, a naphthyl group, a phenylethyl group, and a phenyl group. A resist composition characterized by the above.   The resist composition according to claim 1, wherein the polymer (A) is a polymer polymerized by a living radical polymerization method using cyanopropyldithionaphthoate (CPCN) as a chain transfer agent.   4. The resist composition according to claim 3, wherein the polymer (A) is a polymer that has been end-group-treated with 2,2'-azobisisobutyronitrile (AIBN).   The polymer (A) has a residue derived from cyanopropyldithionaphthoate (CPDN) or 2,2′-azobisisobutyronitrile (AIBN) at least at a part of the molecular terminals. The resist composition according to claim 3 or 4. A method for producing a resist polymer having an acid dissociable group that has at least one repeating unit represented by formula (I) and has increased solubility in an alkaline developer,
A method for producing a resist polymer, comprising a living radical polymerization step using cyanopropyldithionaphthoate (CPDN) as a chain transfer agent.

In the general formula (I), R ₁ is a hydrogen atom or an alkyl group having 4 or less carbon atoms,
R ₂ is an isobutyl group, tert-butyl group, tert-amyl group, benzyl group, cyclohexyl group, anthracenyl group, hydroxyethyl group, cinnamyl group, adamantyl group, methyladamantyl group, ethyladamantyl group, isobornyl group, ethoxyethyl group , A methoxypropyl group, a methoxyethoxyl group, an oxotetrahydrofuran group, a hydroxytrimethylpropyl group, an oxo-oxatricyclononyl group, a naphthyl group, a phenylethyl group, and a phenyl group. A method for producing a resist polymer, characterized in that: The method for producing a resist polymer according to claim 6, further comprising a step of subjecting the end group to 2,2'-azobisisobutyronitrile (AIBN).