TWI617884B - Polymer, negative resist composition, and pattern forming process - Google Patents

Abstract

The present invention provides a base resin which is a base resin which is superior to a conventional negative photoresist material and has a low line edge roughness and a low line edge roughness, is an ideal polymer, a negative photoresist material containing the polymer, and is used. A pattern forming method of the negative photoresist material. A polymer comprising a repeating unit represented by the following formula (a), a repeating unit represented by the following formula (b), and a repeating unit represented by the following formula (c), and having a weight average molecular weight of 1,000 to 500,000.  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="403" he="187" file="01_image002.gif" img- Format="jpg"></img></td></tr></TBODY></TABLE>

Description

Polymer, negative photoresist material and pattern forming method

This invention relates to polymers, negative photoresist materials, and patterning methods.

With the high integration and speed of LSI, the miniaturization of pattern rules is rapidly progressing. Mass production of logic devices close to 10 nm is approaching, and devices with quantities close to 20 nm are in mass production for DRAM. They are formed using double patterned ArF lithography. In addition, extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm has also been discussed.

On the other hand, the flash memory is pulled up to a refinement of 15 nm, and then has begun to shift to a 3-dimensional memory that increases the capacity by using a three-dimensional stack. At this time, an ultra-thick film processing technique exceeding 10 μm is required to process a plurality of laminated films.

In the case of ArF double-patterned lithography, as the number of masks increases, the accuracy of alignment of a plurality of masks is required to be improved, and the size of the pattern is increased. In the mask for EUV lithography, it is also necessary to form a finer pattern with ArF lithography and to increase the precision of each pattern.

When the mask pattern is produced, the photoresist pattern formation is performed by electron beam (EB) lithography. In order to increase the productivity of EB lithography, chemically amplified photoresists are generally used. The chemically amplified photoresist may, for example, be a polymer obtained by substituting a part of a hydroxyl group of polyhydroxystyrene with an acid labile group as a base resin, and doping an acid generator, a quencher for controlling acid diffusion, Surfactant and organic solvent. The chemically amplified photoresist has the advantage of high sensitivity, but on the other hand, there is a disadvantage that the image is blurred due to acid diffusion, resulting in a decrease in the resolution and the accuracy of the pattern.

As the resolution of the photoresist pattern caused by EB lithography increases, the aspect ratio of the photoresist pattern increases, thereby causing a problem of pattern collapse due to stress during rinsing and drying after development. . In order to prevent this, thin film formation of the photoresist film is already underway. In the meantime, it is necessary to improve the dry etching resistance, and in order to improve the dry etching resistance of the photoresist film, polyhydroxystyrene substituted with an acid labile group, and anthracene (Patent Document 1) and vinyl naphthalene (Patent Document 2) have been proposed. The polymer obtained by copolymerization is used as a basic positive photoresist. By copolymerizing ruthenium and vinyl naphthalene, not only the dry etching resistance but also the benefits of controlling acid diffusion are promoted, and the resolution is also improved.

In the case of a negative photoresist, in some cases, not only in the use of a crosslinking agent or in a negative photoresist using a base polymer containing a crosslinking unit, but also in the hydrophilicity, the dehydration reaction due to acid is lowered. As the negative photoresist, a polymer containing a repeating unit derived from hydrazine or ethylene naphthalene is used (Patent Document 4).

In recent years, an oxide film-based hard mask has been gradually used as a mask substrate without excessively improving the dry etching resistance of the photoresist film. In addition to improving the resolution, the reduction of edge roughness (LER, LWR) has become more important in recent years than the improvement in dry etching resistance. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. JP-A No. 2004-169702 [Patent Document 3] JP-A-2004-61794 (Patent Document 4) JP-A-2013-164588 Bulletin

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and it is an object of the invention to provide a base resin which is a negative resistive material having a high resolution and a small edge roughness which is superior to the conventional negative photoresist material. a polymer; a negative photoresist material using the polymer, particularly suitable for i-ray, ArF excimer laser, EB, EUV exposure negative photoresist materials; and providing pattern formation using the negative photoresist material method. [Means for solving the problem]

The inventors of the present invention have diligently studied in order to obtain a negative-type photoresist material having high resolution and low edge roughness which has been expected in recent years, and as a result, found that a polymer containing a specific repeating unit is used as a base of a negative-type photoresist material. The resin is extremely effective and is completed in the present invention.

The polymer containing a repeating unit derived from hydrazine or ethylene naphthalene described in Patent Document 4 is excellent in acid diffusion control and has reduced edge roughness, but further improvement in performance is required. By copolymerizing hydrazine and ethylene naphthalene, the main chain becomes rigid, and the glass transition point of the polymer is increased, so that the acid diffusion distance is shortened. The aforementioned copolymer has a higher effect of acid diffusion control than the styrene copolymer. On the other hand, since hydrazine and ethylene naphthalene are hydrophobic aromatic compounds, the hydrophilic portion and the hydrophobic portion are mixed in the polymer, and the solubility of the alkali developing solution becomes uneven, causing swelling and deterioration of edge roughness. The reason.

The copolymerized polymer of hydroxystyrene and coumarin which is partially substituted with an acid labile group described in Patent Document 3 has an ester group, so the hydrophobicity is lower than that of oxime and vinyl naphthalene, and it is suppressed. Swelling in an alkali developer to reduce edge roughness. However, since the coumarin has low polymerizability, it is difficult to uniformly introduce it into the polymer, and the edge roughness of the predetermined target is not reduced.

The inventors of the present invention have diligently studied in order to further suppress acid diffusion, improve alkali dissolution uniformity, and reduce edge roughness. As a result, it has been found that by using a repeating unit derived from vinyl anthracene, a carboxyl group containing a carboxyl group is bonded. The repeating unit of the benzene ring of the alkyl group and the polymer derived from the repeating unit of the hydroxystyrene are used as the base resin of the negative resist material, and the alkali dissolution rate before and after the exposure can be high, and the effect of suppressing acid diffusion is high. High resolution, good pattern shape and edge roughness after exposure, and particularly suitable as a negative photoresist material for fine pattern forming materials for super LSI manufacturing or photomasks.

The vinyl anthracene and the styrene derivative are also highly polymerizable, so that they can be uniformly introduced into the polymer. Since it has two carbonyl groups and has moderate hydrophilicity, the difference in hydrophilicity and hydrophobicity in the polymer is small, and alkali solubility is uniformized. Two carbonyl groups also have the property of controlling acid diffusion. With the above characteristics, a photoresist pattern having high resolution and small edge roughness can be obtained.

The negative-type photoresist material of the invention has high dissolution contrast when formed into a photoresist film, high effect of inhibiting acid diffusion, high resolution, exposure margin, excellent processing adaptability, and good pattern shape after exposure. . Therefore, since it has such excellent characteristics, it is highly practical, and it is very effective to cover a pattern forming material as a photoresist material for a super LSI.

That is, the present invention provides the following polymers, negative photoresist materials, and pattern forming methods. A polymer comprising a repeating unit represented by the following formula (a), a repeating unit represented by the following formula (b), and a repeating unit represented by the following formula (c), and having a weight average molecular weight of 1,000 to 500,000; 】 <TABLE border="1"borderColor="#000000"width="85%"><TBODY><tr><td><imgwi="403"he="187"file="02_image001.jpg" img -format="jpg"></img></td></tr></TBODY></TABLE> wherein R ^{A is} independently a hydrogen atom or a methyl group; R ¹ represents a hydroxyl group, a linear chain Or a branched alkyl group having 1 to 4 carbon atoms, a linear or branched carbon group having 1 to 4 carbon atoms, an ethoxy group, or a halogen atom; and R ² and R ⁵ are each independently a linear chain. a linear or branched alkyl group having 1 to 6 carbon atoms or a halogen atom; and R ³ and R ⁴ are each independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, or R ³ Bonded to R ⁴ and form a ring together with the carbon atom to which they are bonded; X ¹ and X ² are each independently a single bond or an ester group; m is 1 or 2; and p and q are each independently 0 or 1; r is an integer from 0 to 4. 2. The polymer of 1, further comprising at least one selected from the group consisting of the repeating units represented by the following formulas (f1) to (f3); [Chemical 2] <TABLE border="1"borderColor="#000000" width= "85%"><TBODY><tr><td><img wi="509"he="194"file="02_image003.jpg"img-format="jpg"></img></td></tr></TBODY></TABLE> wherein R ^{A is} each independently a hydrogen atom or a methyl group; R ²¹ is a single bond, a phenyl group, -OR ³¹ -, or -C(=O)-Z ¹ -R ³¹ -, Z ¹ is -O- or -NH-, and R ³¹ is a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, a linear chain, a branched chain or a cyclic group. The alkenyl group having 2 to 6 carbon atoms or the phenyl group may also contain a carbonyl group, an ester group, an ether group or a hydroxyl group; and Rf ¹ to Rf ⁴ are each independently a fluorine atom, a hydrogen atom or a trifluoromethyl group, but Rf At least one of ¹ to Rf ⁴ is a fluorine atom; and R ²² to R ²⁹ are each independently a linear, branched or cyclic carbon number of 1 to 12 which may also contain a carbonyl group, an ester group or an ether group. a group having an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a nonylphenyl group; Y ¹ being a single bond or a carbon number of an ester group, an ether group or a lactone ring 1~ 12 linkage; Y ² is single bond, methylene, stretch Ethyl, phenyl, phenylphenyl, -OR ³² -, or -C(=O)-Z ² -R ³² -, Z ² is -O- or -NH-, R ³² is linear a branched or cyclic carbon group having 1 to 6 carbon atoms, a phenyl group, or a linear, branched or cyclic carbon group having 2 to 6 carbon atoms, an ester group, or a carbonyl group or an ester group. Ether or hydroxyl; M ^{- is a} non-nucleophilic relative ion. 3. A negative photoresist material comprising a base resin comprising a polymer such as 1 or 2. 4. A negative-type photoresist material such as 3, which is a chemically amplified photoresist material further comprising an organic solvent and an acid generator. 5. A negative photoresist material such as 3 or 4, further comprising a basic compound. 6. The negative-type photoresist material according to any one of 3 to 5, further comprising a surfactant. A pattern forming method comprising the steps of: applying a negative-type photoresist material according to any one of 3 to 6 to a substrate, performing heat treatment to form a photoresist film; and using the high-energy ray for the photoresist film Exposure; and developing the exposed photoresist film with a developer. 8. The pattern forming method of 7, wherein the substrate is a blank mask. 9. The pattern forming method according to 7 or 8, wherein the high energy ray is ultraviolet light having a wavelength of from 180 to 400 nm. 10. The pattern forming method according to 7 or 8, wherein the high energy ray is an electron beam or an extreme ultraviolet ray having a wavelength of 3 to 15 nm. A blank mask coated with a negative photoresist material as in any one of 3 to 6. [Effects of the Invention]

The negative-type photoresist material containing the polymer of the present invention has a high contrast ratio of alkali dissolution rate before and after exposure, high resolution, good pattern shape and line edge roughness after exposure, and particularly suppresses acid diffusion rate. Therefore, it is particularly suitable as a pattern forming material for fine pattern forming materials for super LSI manufacturing or photomasks, EB, EUV exposure, and ArF excimer laser exposure. Further, the negative-type photoresist material of the present invention can be applied not only to lithography at the time of formation of a semiconductor circuit but also to formation of a mask circuit pattern, formation of a micro-machine, a thin film magnetic head circuit, and the like.

[Polymer] The polymer of the present invention comprises a repeating unit represented by the following formula (a) (hereinafter referred to as repeating unit a), a repeating unit represented by the following formula (b) (hereinafter referred to as repeating unit b), and The repeating unit represented by the following formula (c) (hereinafter referred to as repeating unit c) has a weight average molecular weight (Mw) of 1,000 to 500,000. [化3]  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="403" he="187" file="02_image001.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

In the formula, R ^{A is} each independently a hydrogen atom or a methyl group. R ¹ represents a hydroxyl group, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, an ethoxy group or a halogen atom. R ² and R ⁵ are each independently a linear or branched alkyl group having 1 to 6 carbon atoms or a halogen atom. R ³ and R ⁴ are each independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, and R ³ and R ⁴ may be bonded to each other to form a ring together with the carbon atom to which they are bonded. X ¹ and X ² are each independently a single bond or an ester group. m is 1 or 2. p and q are each independently 0 or 1. r is an integer from 0 to 4.

The monomer used to obtain the repeating unit a can be exemplified below, but is not limited thereto. 【化4】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="586" he="594" file="02_image005.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

The monomer used to obtain the repeating unit b can be exemplified below, but is not limited thereto. Further, in the following formula, R ^{A is the} same as defined above. [化5] <TABLE border="1"borderColor="#000000"width="85%"><TBODY><tr><td><imgwi="586"he="940"file="02_image007.Jpg"img-format="jpg"></img></td></tr></TBODY></TABLE>

The monomer used to obtain the repeating unit c may be exemplified below, but is not limited thereto. Further, in the following formula, R ^{A is the} same as defined above. 【化6】 <TABLE border="1"borderColor="#000000"width="85%"><TBODY><tr><td><imgwi="579"he="497"file="02_image009.Jpg"img-format="jpg"></img></td></tr></TBODY></TABLE>

The polymer of the present invention may further comprise a repeating unit d containing an adhesion group selected from the group consisting of a hydroxyl group, a lactone ring, an ether group, an ester group, a carbonyl group, and a cyano group. The monomer to which the repeating unit d is given may be exemplified below, but is not limited thereto. Further, in the following formula, R ^{A is the} same as defined above. 【化7】

【化8】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="606" he="442" file="02_image013.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

【化9】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="596" he="612" file="02_image015.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

【化10】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="585" he="924" file="02_image017.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

【化11】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="610" he="447" file="02_image019.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

【化12】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="584" he="629" file="02_image021.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

【化13】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="584" he="592" file="02_image023.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

【化14】

When it is a monomer containing a hydroxyl group, the hydroxyl group may be substituted with an acetal group which is easily deprotected by an acid such as an ethoxyethoxy group during polymerization, and may be deprotected by weak acid and water after polymerization, or may be first The ethyl hydrazide group, the decyl group, the trimethyl ethane group and the like are substituted and subjected to alkali hydrolysis after the polymerization.

The polymer of the present invention may also comprise a repeating unit f derived from a phosphonium salt containing a polymerizable olefin. A sulfonium salt or a phosphonium salt containing a polymerizable olefin having a specific sulfonic acid is proposed in the Japanese Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. A sulfonium salt in which a sulfonic acid is directly bonded to a main chain has been proposed in Japanese Laid-Open Patent Publication No. 2006-178317.

The preferred repeating unit f is a repeating unit represented by the following formula (f1) (hereinafter referred to as repeating unit f1), a repeating unit represented by the following formula (f2) (hereinafter referred to as repeating unit f2), and the following formula ( F3) Repetitive unit indicated (hereinafter referred to as repeating unit f3.). In addition, the repeating units f1 to f3 may be used alone or in combination of two or more. 【化15】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="509" he="194" file="02_image003.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

In the formula, R ^{A is} each independently a hydrogen atom or a methyl group. R ²¹ is a single bond, a phenyl group, -OR ³¹ -, or -C(=O)-Z ¹ -R ³¹ -, Z ¹ is -O- or -NH-, and R ³¹ is linear or branched. Or a cyclic alkyl group having 1 to 6 carbon atoms, a linear chain, a branched or a cyclic group having 2 to 6 carbon atoms, or a phenyl group, or a carbonyl group, an ester group or an ether group. Hydroxyl. Rf ¹ to Rf ⁴ are each independently a fluorine atom, a hydrogen atom or a trifluoromethyl group, but at least one of Rf ¹ to Rf ⁴ is a fluorine atom; and each of R ²² to R ²⁹ may independently contain a carbonyl group or an ester. A linear, branched or cyclic alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or a nonylphenyl group. Y ¹ is a single bond or a linking group having 1 to 12 carbon atoms which may also contain an ester group, an ether group or a lactone ring. Y ² is a single bond, a methylene group, an ethyl group, a phenyl group, a phenyl fluoride group, -OR ³² -, or -C(=O)-Z ² -R ³² -, and Z ² is -O- Or -NH-, R ³² is a linear, branched or cyclic carbon group having 1 to 6 carbon atoms, a phenyl group, or a linear, branched or cyclic carbon number of 2 to 6 The alkenyl group may also contain a carbonyl group, an ester group, an ether group or a hydroxyl group. M ^{- is a} non-nucleophilic relative ion.

The non-nucleophilic relative ion represented by M ^- may, for example, be a halide ion such as a chloride ion or a bromide ion; a triflate, a 1,1,1-trifluoroethanesulfonate or a nonafluorobutanesulfonate; Fluoroalkylsulfonate such as acid; arylsulfonate such as tosylate, benzenesulfonate, 4-fluorobenzenesulfonate, 1,2,3,4,5-pentafluorobenzenesulfonate; methanesulfonate, butane Alkylsulfonate such as sulfonate; bis(trifluoromethylsulfonyl) quinone imine, bis(perfluoroethylsulfonyl) quinone imine, bis(perfluorobutylsulfonyl) quinone imine, etc. A methylated acid such as quintonic acid; ginseng (trifluoromethylsulfonyl) methide or ginseng (perfluoroethylsulfonyl) methide.

The above-mentioned non-nucleophilic relative ions may further include a sulfonic acid ion substituted with fluorine at the α-position represented by the following formula (K-1), a sulfonic acid substituted with fluorine at the α and β positions represented by the following formula (K-2) Ions, etc. 【化16】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="256" he="103" file="02_image027.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

In the formula (K-1), R ¹⁰¹ is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, a linear, branched or cyclic carbon number of 2 to 30. a base, a linear chain, a branched or a cyclic carbon group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aryloxy group, and may also contain an ether group, an ester group, a carbonyl group, a lactone ring, A decylamine ring, a sultone ring, an amine group, a sulfonic acid group, a sulfonate group, a carbonate group, a hydroxyl group, a thiol group, a carboxyl group, a carbamate group, a decylamino group, a quinone imine group.

In the formula (K-2), R ¹⁰² is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 30 carbon atoms, a linear, branched or cyclic carbon number of 2 to 30. a base, a linear chain, a branched or a cyclic carbon group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aryloxy group, and may also contain an ether group, an ester group, a carbonyl group, a lactone ring, A decylamine ring, a sultone ring, an amine group, a sulfonic acid group, a sulfonate group, a carbonate group, a hydroxyl group, a thiol group, a carboxyl group, a carbamate group, a decylamino group, a quinone imine group. R ¹⁰³ is a hydrogen atom, a methyl group, an ethyl group or a trifluoromethyl group.

The repeating unit f functions as an acid generator. By bonding the acid generator to the polymer main chain, acid diffusion is reduced, and deterioration of resolution due to blurring of acid diffusion can be prevented. Further, the edge roughness is improved by uniform dispersion of the acid generator.

In the polymer of the present invention, the ratio of the repeating units a to d and f is preferably 0 < a < 1.0, 0 < b < 1.0, 0 < c < 1.0, 0 ≦ d ≦ 0.7, and 0 ≦ f ≦ 0.3, respectively. Preferably, it is 0.03≦a≦0.5, 0.05≦b≦0.6, 0.1≦c≦0.9, 0≦d≦0.6 and 0≦f≦0.25, more preferably 0.05≦a≦0.4, 0.1≦b≦0.5, 0.2≦c ≦0.8, 0≦d≦0.5 and 0≦f≦0.2. Further, when the repeating unit f is at least one selected from the repeating units f1 to f3, f = f1 + f2 + f3. Also, a+b+c+d+f≦1. Further, for example, a+b+c=1 means that in the polymer comprising the repeating units a, b and c, the total of the repeating units a, b and c is 100 mol% of all repeating units; a+ b+c<1 means that the total of repeating units a, b and c is less than 100 mol% of all repeating units, and other repeating units are included in addition to repeating units a, b and c.

The polymer of the present invention has a Mw of 1,000 to 500,000, preferably 2,000 to 30,000. If the Mw is too small, the heat resistance of the photoresist material is poor; if it is too large, the alkali solubility is lowered, and the tailing phenomenon is likely to occur after the pattern is formed. Further, Mw is a polystyrene conversion measurement obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

Further, when the molecular weight distribution (Mw/Mn) of the polymer of the present invention is large, since a polymer having a low molecular weight and a high molecular weight is present, foreign matter may appear in the pattern after the exposure, or the shape of the pattern may deteriorate. Since the influence of Mw and the molecular weight distribution tends to increase as the pattern rule is refined, the molecular weight distribution of the polymer of the present invention is 1.0 to 2.0, especially 1.0 to 1.5, in order to obtain a photoresist material suitable for a fine pattern size. Dispersion is preferred.

In order to synthesize the polymer of the present invention, for example, a desired polymerization of a monomer given to a monomer of the repeating units a to d and f may be carried out by adding a radical polymerization initiator to an organic solvent and heating.

Examples of the organic solvent used in the polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, and dioxane. The polymerization initiator may, for example, be 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2-azobis (2) -Methylpropionic acid) dimethyl ester, benzammonium peroxide, lauric acid peroxide, and the like. The temperature during polymerization is preferably from 50 to 80 °C. The reaction time is preferably from 2 to 100 hours, more preferably from 5 to 20 hours.

When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, ethoxylated styrene, ethoxylated vinyl naphthalene may be used instead of hydroxystyrene, hydroxyvinylnaphthalene, and alkali hydrolysis after polymerization. The ethoxy group is deprotected to form hydroxystyrene and hydroxyvinylnaphthalene.

As the base in the alkaline hydrolysis, ammonia water, triethylamine or the like can be used. Further, the reaction temperature is preferably from -20 to 100 ° C, more preferably from 0 to 60 ° C. The reaction time is preferably from 0.2 to 100 hours, more preferably from 0.5 to 20 hours.

The polymer of the present invention is suitable as a base resin for a negative photoresist material.

[Negative Photoresist Material] The negative photoresist material of the present invention contains a base resin containing the aforementioned polymer. When the polymer is used as the base resin of the negative-type photoresist material, the base resin may be obtained by blending two or more kinds of polymers having different composition ratios, molecular weight distributions, and molecular weights.

The negative-type photoresist material of the present invention preferably contains an organic solvent, an acid generator, a dissolution controlling agent, a basic compound, a surfactant, and the like in a more appropriate combination for the purpose. By forming the negative-type photoresist material in this manner, the dissolution rate of the polymer in the exposed portion due to the catalyst reaction is lowered, so that it can be an extremely high-sensitivity negative-type photoresist material. Therefore, the photoresist film has high dissolution contrast and resolution, has an exposure margin, is excellent in processing suitability, has a good pattern shape after exposure, and exhibits superior etching resistance, and particularly inhibits acid diffusion, so that the density is poor. It is small and therefore highly practical, and is very effective as a photoresist material for ultra LSI. In particular, when a chemically amplified negative-type photoresist material containing an acid generator and reacted with an acid catalyst is used, it can be made into a higher sensitivity, and various characteristics are more excellent, which is extremely useful.

Examples of the organic solvent include ketones such as cyclohexanone and methyl-2-n-pentanone described in paragraphs [0144] to [0145] of JP-A-2008-111103, 3-methoxybutanol, and 3 - alcohols such as methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol Ethers such as diethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, acetic acid Butyl esters such as butyl ester, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono-tert-butyl acetate, etc. a lactone such as butyrolactone, and a mixed solvent thereof. The blending amount of the organic solvent is preferably 50 to 10,000 parts by mass, more preferably 100 to 5,000 parts by mass, per 100 parts by mass of the base resin.

The negative photoresist material of the present invention may also comprise an acid generator for effecting the chemically amplified negative photoresist material. The acid generator may be a compound (photoacid generator) which generates an acid by inducing active light or radiation. The component of the photoacid generator can be used as long as it is a compound which generates an acid by irradiation with high energy rays. Preferred photoacid generators are phosphonium salts, phosphonium salts, sulfonyldiazomethane, N-sulfonyloxyquinone imine, anthracene-O-sulfonate type acid generator, and the like. These may be used alone or in combination of two or more. Specific examples of the acid generator include those described in paragraphs [0122] to [0142] of JP-A-2008-111103. The blending amount of the acid generator is preferably 0.01 to 100 parts by mass, more preferably 0.1 to 80 parts by mass, per 100 parts by mass of the base resin.

The negative photoresist material of the present invention may also contain a dissolution control agent. By blending the dissolution control agent, the difference in dissolution rate between the exposed portion and the unexposed portion can be further increased, and the resolution can be further improved. Specific examples of the dissolution controlling agent include those described in paragraphs [0155] to [0178] of JP-A-2008-122932. The blending amount of the dissolution controlling agent is preferably 0 to 50 parts by mass, more preferably 0 to 40 parts by mass, per 100 parts by mass of the base resin.

The negative photoresist material of the present invention may also contain a basic compound. By blending a basic compound, for example, the diffusion rate of the acid in the photoresist film can be suppressed, and the resolution is further enhanced. The basic compound may be a primary, secondary or tertiary amine compound described in paragraphs [0146] to [0164] of JP-A-2008-111103, and particularly has a hydroxyl group, an ether group, an ester group, a lactone ring, A cyano group or a sulfonate group-containing amine compound, and a compound having a urethane group described in Japanese Patent No. 3790649. Further, the basic compound may be a polymer type quenching agent described in JP-A-2008-239918. By aligning the surface of the photoresist after coating, the rectangularity of the patterned photoresist can be improved. The polymer type quenching agent also has an effect of preventing film loss of the pattern when the protective film for immersion exposure is used, and rounding the top of the pattern. The blending amount of the basic compound is preferably 0 to 100 parts by mass, more preferably 0.001 to 50 parts by mass, per 100 parts by mass of the base resin.

The negative photoresist material of the present invention may also comprise a surfactant. By blending the surfactant, the coating properties of the photoresist material can be further enhanced or controlled. Specific examples of the surfactant include those described in paragraphs [0165] to [0166] of JP-A-2008-111103. The blending amount of the surfactant is preferably from 0 to 10 parts by mass, more preferably from 0.0001 to 5 parts by mass, per 100 parts by mass of the base resin.

The photoresist material of the present invention may further contain acetylene alcohols. Examples of the acetylene alcohols include those described in paragraphs [0179] to [0182] of JP-A-2008-122932. The blending amount of the acetylene alcohol is preferably 0 to 5 parts by mass based on 100 parts by mass of the base resin.

[Pattern Forming Method] When the negative-type photoresist material of the present invention is used in the production of various integrated circuits, a well-known lithography technique can be employed.

For example, the negative-type photoresist material of the present invention is applied to a substrate for manufacturing an integrated circuit (Si, SiO ₂ , or the like by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, blade coating, or the like. SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflection film, etc.) or a substrate for manufacturing a mask circuit (Cr, CrO, CrON, MoSi ₂ , SiO _{2 ,} etc.), the coating film thickness is 0.01~ 2.0 μm. It is pre-baked on a hot plate, preferably at 60 to 150 ° C for 10 seconds to 30 minutes, more preferably at 80 to 120 ° C for 30 seconds to 20 minutes. Next, high-energy rays such as ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, soft X-rays, excimer lasers, gamma rays, synchrotron radiation, and the like are irradiated through a predetermined mask or directly by a target pattern. The exposure is preferably about 1 to 200 mJ/cm ² , particularly about 10 to 100 mJ/cm ² , or about 0.1 to 100 μC/cm ² , especially about 0.5 to 50 μC/cm ² . Then, it is preferably carried out on a hot plate at 60 to 150 ° C for 10 seconds to 30 minutes, more preferably at 80 to 120 ° C for 30 seconds to 20 minutes after exposure and baking (PEB).

A polythiophene or a polyaniline-based antistatic film may be provided on the photoresist film, or a surface coating film other than this may be formed.

It is preferred to use 0.1 to 10% by mass, more preferably 2 to 5% by mass of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylene. The developing solution of an aqueous alkali solution such as ammonium hydroxide (TBAH) is subjected to a usual method such as dip method, puddle method, or spray method for 3 seconds to 3 minutes, preferably 5 seconds to 2 seconds. Development in minutes, whereby a negative pattern in which the irradiated portion is insoluble in the developer and the unexposed portion is dissolved is formed on the substrate. Further, the photoresist material of the present invention is particularly preferably finely patterned by using EB, EUV, soft X-ray, X-ray, γ-ray, and synchrotron radiation in high-energy rays.

Compared with the widely used TMAH aqueous solution, TEAH, TPAH and TBAH having a long alkyl chain have an effect of reducing swelling during development and preventing pattern collapse. The TMAH developer most often uses an aqueous solution of 2.38 mass%. It corresponds to 0.26 N, and the TEAH, TPAH or TBAH aqueous solution is also preferably the same equivalent concentration. The concentrations of TEAH, TPAH, and TBAH which were 0.26 N were 3.84% by mass, 5.31% by mass, and 6.78% by mass, respectively.

In a pattern of 32 nm or less in which EB or EUV is imaged, a phenomenon in which a wire is twisted or a line entangled with each other and entangled is collapsed. It is considered that the lines which are swollen in the developing solution are entangled with each other. The swelled thread contains a developer and is soft like a sponge, so it is easily collapsed due to the stress of rinsing. A developer containing TEAH, TPAH, and TBAH having a long alkyl chain has an effect of preventing swelling and preventing pattern collapse. [Examples]

Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited to the following examples. In addition, the weight average molecular weight (Mw) is a polystyrene conversion measurement obtained by GPC using THF as a solvent. Further, the monomers 1 to 3 and the PAG monomers 1 to 4 used in the following examples are as follows. 【化17】

[1] Synthesis of polymer [Example 1-1] Synthesis of polymer 1 In a 2 L flask, 3.5 g of 2-vinyl fluorene, 4.1 g of a monomer, 7.2 g of 4-hydroxystyrene, and a solvent were added. THF 20g. The reaction vessel was cooled to -70 ° C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of azobisisobutyronitrile (AIBN) as a polymerization initiator was added, and the mixture was heated to 60 ° C, and then reacted for 15 hours. The reaction solution was concentrated to 1/2, and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration, and dried under reduced pressure at 60 ° C to give polymer 1. The composition of the polymer 1 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw/Mn were confirmed by GPC. 【化18】

[Example 1-2] Synthesis of Polymer 2 To a 2 L flask, 3.5 g of 2-vinylhydrazine, 4.1 g of a monomer 2, 7.8 g of 4-hydroxystyrene, and 40 g of THF as a solvent were added. The reaction vessel was cooled to -70 ° C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN as a polymerization initiator was added, and the mixture was heated to 60 ° C, and then reacted for 15 hours. The reaction solution was concentrated to 1/2, and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration, and dried under reduced pressure at 60 ° C to give polymer 2. The composition of the polymer 2 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw/Mn were confirmed by GPC. 【化19】

[Example 1-3] Synthesis of Polymer 3 In a 2 L flask, 3.5 g of 2-vinylhydrazine, 5.1 g of monomer 3, 4.2 g of 4-hydroxystyrene, and 4-hydroxyphenyl methacrylate were added. g, and THF 40g as a solvent. The reaction vessel was cooled to -70 ° C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN as a polymerization initiator was added, and the mixture was heated to 60 ° C, and then reacted for 15 hours. The reaction solution was concentrated to 1/2, and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration, and dried under reduced pressure at 60 ° C to give polymer 3. The composition of the polymer 3 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw/Mn were confirmed by GPC. 【化20】

[Example 1-4] Synthesis of polymer 4 In a 2 L flask, 3.5 g of 2-vinyl fluorene, 4.9 g of monomer 1, 4.8 g of 4-hydroxystyrene, 6.8 g of PAG monomer, and a solvent were added. THF 40g. The reaction vessel was cooled to -70 ° C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN as a polymerization initiator was added, and the mixture was heated to 60 ° C, and then reacted for 15 hours. The reaction solution was concentrated to 1/2, and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration, and dried under reduced pressure at 60 ° C to give polymer 4. The composition of the polymer 4 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw/Mn were confirmed by GPC. 【化21】

[Example 1-5] Synthesis of Polymer 5 4.5 g of 2-vinylindene, 4.9 g of monomer 1, 4.8 g of 4-hydroxystyrene, 5.9 g of PAG monomer 2, and a solvent were added to a 2 L flask. THF 40g. The reaction vessel was cooled to -70 ° C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN as a polymerization initiator was added, and the mixture was heated to 60 ° C, and then reacted for 15 hours. The reaction solution was concentrated to 1/2, and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration, and dried under reduced pressure at 60 ° C to give polymer 5. The composition of the polymer 5 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw/Mn were confirmed by GPC. 【化22】

[Example 1-6] Synthesis of Polymer 6 To a 2 L flask, 4.5 g of 2-vinyl anthracene, 4.9 g of a monomer 1, 5.3 g of 4-hydroxyphenyl methacrylate, and 3-side of methacrylic acid were added. Oxy-2,7-dioxatricyclo[4.2.1.0 ^4,8 ]decane-9-ester 2.2 g, PAG monomer 3 7.4 g, and THF 40 g as a solvent. The reaction vessel was cooled to -70 ° C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN as a polymerization initiator was added, and the mixture was heated to 60 ° C, and then reacted for 15 hours. The reaction solution was concentrated to 1/2, and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration, and dried under reduced pressure at 60 ° C to give polymer 6. The composition of the polymer 6 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw/Mn were confirmed by GPC. 【化23】

[Example 1-7] Synthesis of Polymer 7 2.3 g of 2-vinylindole, 4.9 g of monomer 1, 5.3 g of 4-hydroxyphenyl methacrylate, and α-methylene group were added to a 2 L flask. 2.0 g of γ-butyrolactone, 7.4 g of PAG monomer 4, and 40 g of THF as a solvent. The reaction vessel was cooled to -70 ° C under a nitrogen atmosphere, and degassing under reduced pressure and nitrogen blowing were repeated three times. After warming to room temperature, 1.2 g of AIBN as a polymerization initiator was added, and the mixture was heated to 60 ° C, and then reacted for 15 hours. The reaction solution was concentrated to 1/2, and added to a mixed solvent of 1 L of methanol and 0.1 L of water, whereby a white solid precipitated. The obtained white solid was separated by filtration and dried under reduced pressure at 60 ° C to give polymer 7. The composition of the polymer 7 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw/Mn were confirmed by GPC. 【化24】

[Comparative Example 1-1] Synthesis of Comparative Polymer 1 Synthesis of Comparative Polymer 1 was carried out in the same manner as in Example 1-1 except that 2.3 g of ethylene naphthalene was used instead of 2-vinyl anthracene. . The composition of the comparative polymer 1 was confirmed by ¹³ C-NMR and ¹ H-NMR, and Mw and Mw/Mn were confirmed by GPC. 【化25】

[2] Preparation of Negative Photoresist Material [Examples 2-1 to 2-9, Comparative Example 2-1] The components shown in Table 1 were dissolved in 100 ppm of a surfactant which was dissolved as a surfactant. A solution obtained by the company's surfactant surfactant FC-4430 was filtered through a 0.2 μm filter to prepare a negative photoresist material. The components in Table 1 are as follows. Polymers 1 to 7: Polymers obtained in Examples 1-1 to 1-7, Comparative Polymer 1: Polymer obtained in Comparative Example 1 : Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) CyH (cyclohexanone) ・Acid generator: PAG1 (see the following structural formula) ・Basic compound: quencher 1 (refer to the following structural formula)

[3] EB lithography evaluation Each of the negative photoresist materials prepared in Examples 2-1 to 2-9 and Comparative Example 2-1 was spin-coated using a Clean track Mark 5 (manufactured by Tokyo Vision Co., Ltd.). On a Si substrate having a diameter of 6 吋φ, pre-baking was performed on a hot plate at 110 ° C for 60 seconds to obtain a 100 nm photoresist film. The HL-800D manufactured by Hitachi, Ltd. was used, and the vacuum chamber was drawn at a HV voltage of 50 kV. Immediately after the drawing, Clean Track Mark 5 (manufactured by Tokyo Vision Co., Ltd.) was used, and PEB was applied to a hot plate at a temperature shown in Table 1 for 60 seconds, and immersed and developed for 30 seconds with a 2.38 mass% TMAH aqueous solution. Obtain a negative pattern. The obtained photoresist pattern was evaluated in the following manner. The line size of 100 nm and the pitch were defined as the resolution of the minimum size of the 1:1 resolution, and the line edge roughness (LER) of 100 nm LS was measured by SEM. The results are also recorded in Table 1.

【Table 1】  <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td><img wi="638" he="506" file="02_image049.jpg" img- Format="jpg"></img></td></tr></TBODY></TABLE>

According to the results shown in Table 1, the photoresist material using the polymer of the present invention has sufficient resolution and sensitivity, and the LER is reduced.

Claims (11)

a polymer comprising a repeating unit represented by the following formula (a), a repeating unit represented by the following formula (b), and a repeating unit represented by the following formula (c), and having a weight average molecular weight of 1,000 to 500,000; Wherein R ^{A is} each independently a hydrogen atom or a methyl group; R ¹ represents a hydroxyl group, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched carbon number of 1 to 4 carbon atoms; An oxy group, an ethoxy group, or a halogen atom; each of R ² and R ^{5 is} independently a linear or branched alkyl group having 1 to 6 carbon atoms or a halogen atom; and R ³ and R ⁴ are each independently a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, or R ³ and R ⁴ may be bonded to form a ring together with the carbon atom to which they are bonded; X ¹ is a single bond, and X ² is Single bond or ester group; m is 1 or 2; p and q are each independently 0 or 1; r is an integer from 0 to 4. The polymer of claim 1 further comprising at least one selected from the group consisting of the repeating units represented by the following formulas (f1) to (f3); [Chem. 28] Wherein R ^{A is} each independently a hydrogen atom or a methyl group; R ²¹ is a single bond, a phenyl group, -OR ³¹ -, or -C(=O)-Z ¹ -R ³¹ -, and Z ¹ is -O - or -NH-, R ³¹ is a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched or cyclic carbon group having 2 to 6 carbon atoms, or The phenyl group may also contain a carbonyl group, an ester group, an ether group or a hydroxyl group; Rf ¹ to Rf ⁴ are each independently a fluorine atom, a hydrogen atom or a trifluoromethyl group, but at least one of Rf ¹ to Rf ⁴ is fluorine. Atom; R ²² to R ²⁹ are each independently a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 12 carbon atoms which may also contain a carbonyl group, an ester group or an ether group; An aralkyl group having 7 to 20 carbon atoms or a nonylphenyl group; Y ¹ being a single bond or a linking group having 1 to 12 carbon atoms of an ester group, an ether group or a lactone ring; Y ² being a single bond, Methylene, ethyl, phenyl, phenyl, -OR ³² -, or -C(=O)-Z ² -R ³² -, Z ² is -O- or -NH-, R ³² is a linear, branched or cyclic carbon group having 1 to 6 carbon atoms, a phenyl group, or a linear, branched or cyclic carbon group having 2 to 6 carbon atoms, and may also contain Carbonyl, ester, ether or Hydroxyl; M ^{- is a} non-nucleophilic relative ion. A negative photoresist material comprising a base resin comprising a polymer as claimed in claim 1 or 2. The negative-type photoresist material according to item 3 of the patent application is a chemically amplified photoresist material further comprising an organic solvent and an acid generator. A negative photoresist material as claimed in claim 3 or 4 further contains a basic compound. A negative photoresist material as claimed in claim 3 or 4, further comprising a surfactant. A pattern forming method comprising the steps of: applying a negative-type photoresist material according to any one of claims 3 to 6 to a substrate, performing heat treatment to form a photoresist film; and using the photoresist film The high-energy ray is exposed; and the exposed photoresist film is developed using a developing solution. The pattern forming method of claim 7, wherein the substrate is a blank mask. The pattern forming method of claim 7 or 8, wherein the high-energy ray is ultraviolet light having a wavelength of 180 to 400 nm. The pattern forming method of claim 7 or 8, wherein the high-energy ray is an electron beam or an extreme ultraviolet ray having a wavelength of 3 to 15 nm. A blank reticle coated with a negative photoresist material as claimed in any one of claims 3 to 6.