JP2007178455A - Composition for resist underlay film, and resist underlay film and method for forming pattern on substrate both using composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for a resist underlay film having excellent etching selectivity and preferable antireflection ability against short wavelengths and to provide a resist underlay film and a method for forming a pattern on a substrate both using the above composition. <P>SOLUTION: The composition for a resist underlay film contains a copolymer having structural units expressed by general formulae (1a), (1b), (1c), wherein the content of the structural unit expressed by general formula (1a) in the copolymer is 10 mol% to 75 mol%, the content of the structural unit expressed by general formula (1b) is 5 mol% to 20 mol%, and the content of the structural unit expressed by general formula (1c) is 5 mol% to 70 mol%. In the formulae, R<SP>1</SP>represents a monovalent organic group having crosslinking property, R<SP>2</SP>represents a monovalent organic group having light absorptive property, and R<SP>3</SP>represents a 1-3C lower alkyl group. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resist underlayer film composition used for a resist underlayer film used as an antireflection film when forming a resist pattern on a substrate, a resist underlayer film using the same, and a pattern forming method for the substrate.

  In the manufacture of semiconductor elements, pattern formation on a substrate is performed by a lithography process. The lithography process refers to a method in which a resist composition is applied on a substrate, exposed, further developed to form a resist pattern, and the resist pattern is transferred to a film to be processed such as a wiring layer or a dielectric layer. .

  In recent years, as the integration of semiconductor elements on a circuit board has progressed, standing waves generated during the exposure process have caused variations in the dimensions of the pattern. As a method for suppressing this standing wave, a method of adding a light-absorbing agent to the resist composition or laying an antireflection film on the upper surface of the formed resist layer or on the substrate has been proposed.

  In order to form a finer pattern, it is required to reduce the thickness of the antireflection film and the resist layer. However, since it is difficult to perform accurate etching along with the thinning of the resist layer, it is difficult to process the substrate with high accuracy. Therefore, a resist underlayer film (hard mask) used as an antireflection film is formed between the film to be processed such as the substrate to be processed and the resist layer, and the resist pattern is transferred to the resist underlayer film. A process of dry etching an oxide film or an interlayer insulating film is performed using the film as a mask.

  As a characteristic of the resist underlayer film, etching selectivity with the upper resist layer and the lower processed film is important when the resist underlayer film is etched. That is, it has been found that when etching the resist underlayer film, it is necessary to etch faster than the upper resist layer and to etch later than the lower processed film. Various studies have been made to satisfy such conditions (see Patent Documents 1 to 3).

  Patent Document 1 discloses that a siloxane polymer pendant with a carbonyl, ester, lactone, or ether group is used as an antireflection film (resist underlayer composition). According to Patent Document 1, it is possible to provide an antireflection film having etching selectivity and having an antireflection effect sufficient for exposure at a short wavelength.

  Patent Document 2 also has a functional group similar to that of Patent Document 1 and further has a hydroxy group, an alkyl group having 1 to 6 carbon atoms, and an alkoxy group bonded to a silicon atom to which a crosslinkable organic group is bonded. It is disclosed that the added siloxane polymer is used as an antireflection film (resist underlayer composition). According to this Patent Document 2, an antireflection film material having etching selectivity and storage stability can be provided.

Patent Document 3 discloses that a main chain is silsesquioxane and a siloxane polymer pendant with three silicon-silicon sigma bonds is used as an antireflection film (resist underlayer composition). According to Patent Document 3, it is possible to provide an antireflection film material that has etching selectivity and can maintain a good resist shape after patterning.
JP 2004-310019 A JP-A-2005-18054 JP 2005-48152 A

  In order to impart etching selectivity to the resist underlayer film, it is effective to control the contents of carbon atoms and silicon atoms in the resist underlayer film composition. However, none of the siloxane polymers disclosed in Patent Documents 1 to 3 has controlled contents of carbon atoms and silicon atoms. Therefore, sufficient improvement in etching selectivity is not seen.

  In view of the above problems, in the present invention, a resist underlayer film composition having excellent etching selectivity and good antireflection performance for short wavelengths, and a resist underlayer film and substrate pattern forming method using the same The purpose is to provide.

  In order to solve the above-mentioned problems, the present inventors reduced the content of carbon atoms in the copolymer in order to improve the etching selectivity in the silsesquioxane terpolymer. Was found to be achieved by introducing a lower alkyl group having a small number of carbon atoms into the side chain of one unit in the copolymer, and the present invention was completed. .

［式中、Ｒ^１は架橋性を有する１価の有機基であり、Ｒ^２は光吸収性を有する１価の有機基であり、Ｒ^３は炭素数１から３の低級アルキル基である。］
前記共重合体における一般式（１ａ）で示される構造単位の含有量は１０モル％から７５モル％であり、一般式（１ｂ）で示される構造単位の含有量は５モル％から２０モル％であり、一般式（１ｃ）で示される構造単位の含有量は５モル％から７０モル％であるレジスト下層膜用組成物。 (1) A resist underlayer film composition containing a copolymer having a structural unit represented by the following general formula (1a), (1b), (1c),

[Wherein, R ¹ is a monovalent organic group having crosslinkability, R ² is a monovalent organic group having light absorption, and R ³ is a lower alkyl group having 1 to 3 carbon atoms. ]
The content of the structural unit represented by the general formula (1a) in the copolymer is from 10 mol% to 75 mol%, and the content of the structural unit represented by the general formula (1b) is from 5 mol% to 20 mol%. A composition for a resist underlayer film, wherein the content of the structural unit represented by the general formula (1c) is from 5 mol% to 70 mol%.

According to the invention of (1), a resist underlayer film composition having good temporal stability can be provided by using a ladder-like silsesquioxane as the structure of the copolymer. Further, by using a ternary copolymer, the content of carbon atoms and silicon atoms in the copolymer can be controlled while maintaining high antireflection performance. Furthermore, by using R ³ as a lower alkyl group having 1 to 3 carbon atoms, the carbon number of the entire copolymer can be reduced. As a result, it is possible to etch faster than the upper resist compound. Moreover, content of each structural unit was made into said value, and content of a silicon atom can be made high. This enables etching slower than the underlying resist compound. As a result, the etching selectivity of the resist underlayer film can be improved. Furthermore, the curability of the formed resist underlayer film can be improved, and mixing with the upper layer and cracking can be prevented.

(2) The resist underlayer film composition according to (1), wherein R ³ is a methyl group.

According to the invention of (2), since R ³ is a methyl group, etching can be performed faster than the upper resist compound. As a result, the etching selectivity of the resist underlayer film can be further improved.

(3) The composition for a resist underlayer film according to (1) or (2), wherein R ¹ is an organic group having a molecular weight of 50 to 300 having an epoxy group or an oxetanyl group.

According to the invention of (3), the crosslinkability can be improved by making R ¹ a group having an epoxy group or an oxetanyl group. Further, by setting the molecular weight of R ¹ to the above value, crosslinkability can be imparted, and the Si content in the copolymer can be increased.

(4) The resist underlayer film composition according to any one of (1) to (3), wherein R ¹ is an organic group having 4 to 15 carbon atoms.

According to the invention of (4), by setting the carbon number of R ¹ to the above value, even if the molecular weight of R ¹ is a large value such as around 300, the carbon number of the entire copolymer is increased. Can be suppressed.

(5) The composition for a resist underlayer film according to any one of (1) to (4), wherein R ¹ further has at least one ether bond.

According to the invention of (5), by using R ¹ as a group having at least one ether bond, it is possible to prevent the acid used for the crosslinking reaction from moving into the resist film during baking. As a result, since the acid labile group in the resist film is not eliminated, the resist pattern can be prevented from being reversely tapered.

  (6) The content of the structural unit represented by the general formula (1a) in the copolymer is 45 mol% to 70 mol%, and the content of the structural unit represented by the general formula (1b) is from 10 mol%. The composition for a resist underlayer film according to any one of (1) to (5), which is 15 mol% and the content of the structural unit represented by the general formula (1c) is 20 mol% to 45 mol%.

  According to the invention of (6), by setting the content of each structural unit to the above value, it is possible to etch faster than the upper resist compound and slower than the lower resist compound. Thus, the etching selectivity can be further improved. Furthermore, the curability of the formed resist lower layer film can be further improved, and mixing with the upper layer and cracking can be prevented.

(7) The resist underlayer film composition according to any one of (1) to (6), wherein the copolymer is a structural unit represented by the following general formulas (2a), (2b), and (2c).

According to the invention of (7), since R ³ is a methyl group, the resist lower layer film can be etched faster than the upper resist compound. Further, by using R ² as a phenyl group, excellent light absorption can be imparted even at a short wavelength of 150 nm to 300 nm. In addition, when R ¹ has a structure having an ether bond and an oxetanyl group, the storage stability of the resist underlayer film composition can be increased. Therefore, by combining structural units having such characteristics, it is possible to provide a resist underlayer film composition having excellent etching selectivity and good antireflection performance for short wavelengths.

  (8) The composition for resist underlayer film according to any one of (1) to (7), further containing an acid generator.

  According to the invention of (8), by further adding the acid generator, it is possible to suppress the mixing phenomenon due to the acid moving to the upper resist layer during baking. The acid generator includes a thermal acid generator that generates an acid by heat and a photoacid generator that generates an acid by light, but either acid generator may be used. Or two or more types may be used in combination.

  (9) The composition for a resist underlayer film according to any one of (1) to (8), further containing a crosslinking agent.

  According to the invention of (9), by further adding a crosslinking agent, it is possible to further promote the crosslinking reaction and further improve the curability of the formed resist underlayer film.

  (10) A resist underlayer film obtained by applying the resist underlayer film composition according to any one of (1) to (9) to a substrate and baking at a predetermined temperature.

  (11) A method of forming a pattern on a film to be processed by lithography, wherein the composition for a resist underlayer film according to any one of (1) to (9) is applied to a film to be processed at a predetermined temperature. A step of baking to form a resist underlayer film, a step of applying a resist composition on the obtained resist underlayer film, baking at a predetermined temperature to form a resist film, and a pattern circuit region of the resist film A resist pattern is formed by developing with a developing solution after exposure, and the resist underlayer film and the processed film are etched using the resist pattern as a mask to form a predetermined pattern on the processed film And forming a pattern on the film to be processed.

  (12) A method of using the copolymer having the structural unit according to (1) or (6) for producing a resist underlayer film composition.

According to the present invention, by using a ternary silsesquioxane as the structure of the copolymer, it is possible to provide a resist underlayer film composition having high antireflection performance and good temporal stability. . Further, to control the content of carbon atoms to silicon atoms in the copolymer, i.e., a lower alkyl group of R ³ from 1 to 3 carbon atoms, the etching selectivity by controlling the content of each structural unit Can be improved. As a result, it is possible to provide a resist underlayer film composition having excellent etching selectivity and good antireflection performance for short wavelengths, and a resist underlayer film and substrate pattern forming method using the same.

  Hereinafter, embodiments of the present invention will be described in detail. The resist underlayer film composition according to the present invention contains a copolymer having a structural unit represented by the following general formula (1) (hereinafter, referred to as a siloxane compound as appropriate).

[Siloxane compound]
The copolymer according to the present invention has structural units represented by the following general formulas (1a), (1b), and (1c).

Here, R ¹ represents a monovalent organic group having crosslinkability. The “monovalent organic group having crosslinkability” is a substituent containing carbon, which can react with other functional groups, or can react with a separately added crosslinking agent. . The organic group having crosslinkability is preferably one that is crosslinked by heat, and examples thereof include a group having an ethylenic double bond, a group having an epoxy group, and an organic group having an oxetanyl group. These organic group having an ethylenic double bond, epoxy group and / or oxetanyl group may be interrupted by at least one ether bond, alkoxycarbonyl (—O (CO) —). It is preferably bonded to the silicon atom of the main skeleton through 1 to 20 alkylene groups. Of these crosslinking groups, those having an oxetanyl group with good storage stability are most preferred.

In addition, the molecular weight of R ¹ is preferably 50 to 300, and more preferably 100 to 200. By setting the molecular weight to 50 or more, crosslinkability can be imparted. Moreover, Si content in a copolymer can be made to increase, without making carbon number increase too much by making molecular weight 300 or less.

R ¹ is preferably an organic group having 4 to 15 carbon atoms, and more preferably an organic group having 7 to 10 carbon atoms. By setting the number of carbon atoms to 4 or more, sufficient crosslinkability can be provided. Moreover, Si content in a copolymer can be increased by making carbon number 15 or less. Specifically, it preferably has a structure as shown below.

R ² represents a monovalent organic group having light absorption. The “monovalent organic group having light absorptivity” is preferably a group having absorptivity for light having a wavelength of 120 to 300 nm. The organic group having light absorption preferably has good light absorption with respect to light having a wavelength of 150 nm to 200 nm. Specific examples include groups having a condensed ring such as a benzene ring, anthracene ring, and naphthalene ring which may have a substituent. In addition, the organic group having the light absorption property is a main skeleton silicon via an alkylene group having 1 to 20 carbon atoms which may be interrupted by one or more ether bonds and alkoxycarbonyl (—O (CO) —). It is preferably bonded to an atom. Of the condensed rings such as a benzene ring, an anthracene ring, and a naphthalene ring, it is preferable to use a benzene ring and a substituted product thereof because it has absorption in an ArF laser (wavelength 193 nm) or the like.

R ³ represents a lower alkyl group having 1 to 3 carbon atoms. The “lower alkyl group having 1 to 3 carbon atoms” refers to a lower alkyl group having 1 to 3 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Among them, it is preferable to use a methyl group or an ethyl group that has low reactivity and good resist selectivity.

  The content of each structural unit in the copolymer according to the present invention will be described. The content of the structural unit represented by the general formula (1a) is from 10 mol% to 75 mol%, more preferably from 20 mol% to 75 mol%, and from 45 mol% to 70 mol%. Most preferred. By setting it in this range, the curability of the formed antireflection film can be improved, and mixing with the upper layer, cracking, etc. can be made difficult to occur. As a specific method, the content of the monomer having the structural unit represented by the general formula (1a) is increased or decreased.

  Next, the content of the structural unit represented by the general formula (1b) is from 5 mol% to 20 mol%, more preferably from 7 mol% to 17 mol%, and from 10 mol% to 15 mol%. Most preferred. By setting it within this range, the light absorption characteristics can be improved. When an ArF laser (wavelength 193 nm) is used for exposure of the resist film, the optical parameter (k value) for light of this wavelength is 0.002 to 0.95, preferably 0.01 to 0.7, It is necessary to adjust the range of the structural unit represented by the general formula (1a) so as to form an antireflection film preferably in the range of 0.05 to 0.25. The method is carried out by increasing or decreasing the content of the monomer having the structural unit represented by the general formula (1a).

  Next, the content of the structural unit represented by the general formula (1c) is 5 mol% to 70 mol%, more preferably 10 mol% to 50 mol%, and 20 mol% to 45 mol%. Is most preferred. By setting this range, the resist selectivity can be improved.

  In addition, the arrangement | sequence of each structural unit is not specifically limited, A random copolymer may be sufficient and a block copolymer may be sufficient, but it is preferable to set it as a random copolymer. When the monomers are continuously arranged, the number of repetitions is preferably 2 or more and 20 or less.

  The mass average molecular weight (polystyrene conversion standard by gel permeation chromatography) of the siloxane compound is not particularly limited, but is preferably 200 to 10,000, and more preferably 500 to 5,000.

Such a siloxane compound has a compound having a structural unit represented by general formulas (2a), (2b), and (2c) and a structural unit represented by general formulas (3a), (3b), and (3c). Compounds and the like.

  The silicon atom content in the siloxane compound is preferably 10 mol% to 40 mol%, and more preferably 20 mol% to 35 mol%. Accordingly, the carbon atom content is preferably 50 mol% to 70 mol%, and more preferably 30 mol% to 60 mol%. By setting the content of each atom within this range, the resist selectivity can be improved.

[Method for producing siloxane compound]
Moreover, the siloxane compound according to the present invention can be obtained by hydrolyzing and copolymerizing each monomer containing each structural unit. The amount of water in the hydrolysis reaction is preferably 0.2 to 10 moles per mole of monomer. At this time, known catalysts such as metal chelate compounds, organic acids, inorganic acids, organic bases, and inorganic bases may be appropriately added.

  Specific examples of the metal chelate compound include tetraalkoxytitanium, trialkoxymono (acetylacetonato) titanium, tetraalkoxyzirconium, trialkoxymono (acetylacetonato) zirconium, and the like. Examples of the organic acid include acetic acid, propionic acid, oleic acid, stearic acid, linoleic acid, salicylic acid, benzoic acid, formic acid, malonic acid, phthalic acid, fumaric acid, citric acid, and tartaric acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, sulfonic acid, methyl sulfonic acid, tosylic acid, trifluoromethane sulfonic acid, and the like.

  Organic bases include pyridine, pyrrole, piperazine, pyrrolidine, piperidine, picoline, trimethylamine, triethylamine, monoethanolamine, diethanolamine, dimethylmonoethanolamine, monomethyldiethanolamine, triethanolamine, diazabicyclooctane, diazabicyclononane. , Diazabicycloundecene, tetramethylammonium hydroxide and the like. Examples of the inorganic base include ammonia, sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide and the like.

  Among these, use a basic catalyst such as ammonia or organic amines so as not to open the epoxy group or oxetanyl group contained as a crosslinking group at the time of polymerization, and so as not to mix alkali or metal impurities. Is preferred. Of these, tetraalkylammonium hydroxide is preferably used. Moreover, it is preferable to make the system into an atmosphere of pH 7 or higher so as not to open the epoxy group or the oxetanyl group. These catalysts can be used alone or in combination of two or more.

  As a reaction operation, first, each monomer is dissolved in an organic solvent, and water is added to start a hydrolysis reaction. The catalyst may be added to water or may be added to an organic solvent.

  As the organic solvent used in the reaction, those which are hardly soluble or insoluble in water are preferable. Specifically, tetrahydrofuran, toluene, hexane, ethyl acetate, cyclohexanone, methyl-2-n-amyl ketone, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, diethylene glycol Dimethyl ether and mixtures thereof are preferred.

  Next, the catalyst is neutralized and the organic solvent layer is separated and dehydrated. This is because the remaining water causes the condensation reaction of the remaining silanol to proceed. A known dehydration method such as an adsorption method using a salt such as magnesium sulfate or a molecular sieve, or an azeotropic dehydration method while removing the solvent may be used.

  Next, an organic solvent hardly soluble or insoluble in the above water is added, and the organic solvent layer is separated and washed with water to remove the catalyst used for hydrolysis condensation. At this time, you may neutralize as needed. Subsequently, the separated organic solvent layer is dehydrated to obtain the siloxane compound according to the present invention.

<Solvent>
The composition for resist underlayer film according to the present invention contains a solvent in addition to the siloxane compound. Specifically, monohydric alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, alcohols such as ethylene glycol, diethylene glycol, propylene glycol, glycerin, trimethylolpropane, hexanetriol, ethylene glycol monomethyl ether, ethylene Glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopro Ethers such as ether, propylene glycol monobutyl ether, esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, ketones such as acetone, methyl ethyl ketone, cycloalkyl ketone, methyl isoamyl ketone, ethylene glycol dimethyl ether, Hydroxyl groups of alcohols such as ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether (PGDM), propylene glycol diethyl ether, propylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether All alkylate Alcohol ethers were of the like.

  Of these, cycloalkyl ketone or alkylene glycol dialkyl ether is more preferable from the viewpoint of coating properties. Further, PGDM (propylene glycol dimethyl ether) is suitable as the alkylene glycol dimethyl ether. It is preferable to use it. These organic solvents may be used alone or in combination of two or more. This solvent is used in an amount of 1 to 50 times, preferably 2 to 20 times the amount of the siloxane compound.

<Crosslinking agent>
The composition for resist underlayer film according to the present invention may contain a crosslinking agent in addition to the siloxane compound. By adding a crosslinking agent, the crosslinking reaction of the monomer can be further promoted. As the crosslinking agent, those generally used may be used.

  Specific examples include epoxy compounds such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, and cresol novolak type epoxy resin. In addition, divinylbenzene, divinylsulfone, triacryl formal, glyoxal, polyhydric alcohol acrylic ester or methacrylic ester and the like are also used.

  In addition, compounds having two or more reactive groups such as compounds in which at least two amino groups of melamine, urea, benzoguanamine, and glycoluril are substituted with a methylol group or a lower alkoxymethyl group can be used.

  Examples of the compound in which at least two amino groups of melamine are substituted with a methylol group or a lower alkoxymethyl group include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 of hexamethylol melamine are methoxymethylated, and a mixture thereof , Hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 5 methylol groups of hexamethylol melamine are acyloxymethylated, or a mixture thereof.

  Examples of the compound in which at least two of the amino groups of urea are substituted with a methylol group or a lower alkoxymethyl group include 1 to 4 methylol groups of tetramethylol urea, tetramethoxymethyl urea, tetramethoxyethyl urea, and tetramethylol urea. Examples thereof include a methoxymethyl group-formed compound or a mixture thereof.

  Compounds in which at least two of the amino groups of benzoguanamine are substituted with a methylol group or a lower alkoxymethyl group include compounds in which one to four methylol groups of tetramethylolguanamine, tetramethoxymethylguanamine, and tetramethylolguanamine are methoxymethylated And mixtures thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, compounds in which one to four methylol groups of acylmethylolguanamine are acyloxymethylated, and mixtures thereof.

  Examples of the compound in which at least two of the amino groups of glycoluril are substituted with a methylol group or a lower alkoxymethyl group include tetramethylol glycoluril, tetramethoxyglycoluril, tetramethoxymethylglycoluril, and tetramethylolglycoluril methylol groups. From 4 to methoxymethyl group, a mixture thereof, a tetramethylol glycoluril methylol group from 1 to 4 acyloxymethylated compounds, or a mixture thereof.

  These cross-linking agents may be used alone or in combination of two or more. The crosslinking agent is used in an amount of 0.1 to 50 parts by weight, preferably 0.5 to 40 parts by weight, based on 100 parts by weight of the siloxane compound according to the present invention. When the addition amount is 0.1 parts by mass or more, the crosslinking reaction can be promoted, and when the addition amount is 50 parts by mass or less, not only the crosslinking reaction is promoted but also the formed resist lower layer. This is because the curability of the film can be improved.

<Acid generator>
The resist underlayer film composition according to the present invention may contain an acid generator in addition to the siloxane compound according to the present invention. The crosslinking efficiency can be further improved by adding an acid generator. Examples of such an acid generator include those that generate an acid by light or heat.

  Photosensitive acid generators that generate acid upon receiving light include onium salts, diazomethane derivatives, glyoxime derivatives, bissulfone derivatives, β-ketosulfone derivatives, disulfone derivatives, nitrobenzyl sulfonate derivatives, sulfonate ester derivatives, N-hydroxyimides A known acid generator such as a sulfonic acid ester derivative of a compound can be used.

  Examples of onium salts include tetramethylammonium trifluoromethanesulfonate, tetramethylammonium nonafluorobutanesulfonate, tetra-n-butylammonium nonafluorobutanesulfonate, tetraphenylammonium nonafluorobutanesulfonate, and tetramethyl p-toluenesulfonate. Ammonium, trifluoromethanesulfonic acid diphenyliodonium, trifluoromethanesulfonic acid (p-tert-butoxyphenyl) phenyliodonium, p-toluenesulfonic acid diphenyliodonium, p-toluenesulfonic acid (p-tert-butoxyphenyl) phenyliodonium, trifluoromethane Triphenylsulfonium sulfonate, trifluoromethanesulfonic acid (p-tert-butoxyphenyl) Phenylsulfonium, trifluoromethanesulfonic acid bis (p-tert-butoxyphenyl) phenylsulfonium, trifluoromethanesulfonic acid tris (p-tert-butoxyphenyl) sulfonium, p-toluenesulfonic acid triphenylsulfonium, p-toluenesulfonic acid (p -Tert-butoxyphenyl) diphenylsulfonium, bis (p-tert-butoxyphenyl) phenylsulfonium p-toluenesulfonate, tris (p-tert-butoxyphenyl) sulfonium p-toluenesulfonate, triphenylsulfonium nonafluorobutanesulfonate , Triphenylsulfonium butanesulfonate, trimethylsulfonium trifluoromethanesulfonate, trimethylsulfone p-toluenesulfonate , Cyclohexylmethyl trifluoromethanesulfonate (2-oxocyclohexyl) sulfonium, p-toluenesulfonate cyclohexylmethyl (2-oxocyclohexyl) sulfonium, trifluoromethanesulfonate dimethylphenylsulfonium, p-toluenesulfonate dimethylphenylsulfonium, trifluoromethane Dicyclohexylphenylsulfonium sulfonate, dicyclohexylphenylsulfonium p-toluenesulfonate, trinaphthylsulfonium trifluoromethanesulfonate, cyclohexylmethyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate, (2-norbornyl) methyl trifluoromethanesulfonate (2- Oxocyclohexyl) sulfonium, ethylenebis [Methyl (2-oxocyclopentyl) sulfonium trifluoromethanesulfonate], 1,2'-naphthylcarbonylmethyltetrahydrothiophenium triflate and the like.

  Diazomethane derivatives include bis (benzenesulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (xylenesulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (cyclopentylsulfonyl) diazomethane, bis (n-butylsulfonyl) diazomethane Bis (isobutylsulfonyl) diazomethane, bis (sec-butylsulfonyl) diazomethane, bis (n-propylsulfonyl) diazomethane, bis (isopropylsulfonyl) diazomethane, bis (tert-butylsulfonyl) diazomethane, bis (n-amylsulfonyl) diazomethane Bis (isoamylsulfonyl) diazomethane, bis (sec-amylsulfonyl) diazomethane, bis (tert-amylsulfur) Nyl) diazomethane, 1-cyclohexylsulfonyl-1- (tert-butylsulfonyl) diazomethane, 1-cyclohexylsulfonyl-1- (tert-amylsulfonyl) diazomethane, 1-tert-amylsulfonyl-1- (tert-butylsulfonyl) diazomethane Etc.

  Examples of glyoxime derivatives include bis-O- (p-toluenesulfonyl) -α-dimethylglyoxime, bis-O- (p-toluenesulfonyl) -α-diphenylglyoxime, bis-O- (p-toluenesulfonyl)- α-dicyclohexylglyoxime, bis-O- (p-toluenesulfonyl) -2,3-pentanedione glyoxime, bis-O- (p-toluenesulfonyl) -2-methyl-3,4-pentanedione glyoxime, Bis-O- (n-butanesulfonyl) -α-dimethylglyoxime, bis-O- (n-butanesulfonyl) -α-diphenylglyoxime, bis-O- (n-butanesulfonyl) -α-dicyclohexylglyoxime Bis-O- (n-butanesulfonyl) -2,3-pentanedione glyoxime, bis-O- ( -Butanesulfonyl) -2-methyl-3,4-pentanedione glyoxime, bis-O- (methanesulfonyl) -α-dimethylglyoxime, bis-O- (trifluoromethanesulfonyl) -α-dimethylglyoxime, bis -O- (1,1,1-trifluoroethanesulfonyl) -α-dimethylglyoxime, bis-O- (tert-butanesulfonyl) -α-dimethylglyoxime, bis-O- (perfluorooctanesulfonyl)- α-dimethylglyoxime, bis-O- (cyclohexanesulfonyl) -α-dimethylglyoxime, bis-O- (benzenesulfonyl) -α-dimethylglyoxime, bis-O- (p-fluorobenzenesulfonyl) -α- Dimethylglyoxime, bis-O- (p-tert-butylbenzenesulfonyl) α- dimethylglyoxime, bis -O- (xylene sulfonyl)-.alpha.-dimethylglyoxime, bis -O- (camphorsulfonyl)-.alpha.-dimethylglyoxime, and the like.

  Examples of bissulfone derivatives include bisnaphthylsulfonylmethane, bistrifluoromethylsulfonylmethane, bismethylsulfonylmethane, bisethylsulfonylmethane, bispropylsulfonylmethane, bisisopropylsulfonylmethane, bis-p-toluenesulfonylmethane, and bisbenzenesulfonylmethane. Can be mentioned.

  Examples of the β-ketosulfone derivative include 2-cyclohexylcarbonyl-2- (p-toluenesulfonyl) propane and 2-isopropylcarbonyl-2- (p-toluenesulfonyl) propane.

  Examples of disulfone derivatives include disulfone derivatives such as diphenyl disulfone derivatives and dicyclohexyl disulfone derivatives.

  Examples of the nitrobenzyl sulfonate derivative include nitrobenzyl sulfonate derivatives such as p-toluenesulfonic acid 2,6-dinitrobenzyl and p-toluenesulfonic acid 2,4-dinitrobenzyl.

  Examples of sulfonic acid ester derivatives include 1,2,3-tris (methanesulfonyloxy) benzene, 1,2,3-tris (trifluoromethanesulfonyloxy) benzene, 1,2,3-tris (p-toluenesulfonyloxy). And sulfonic acid ester derivatives such as benzene.

  Examples of sulfonic acid ester derivatives of N-hydroxyimide compounds include N-hydroxysuccinimide methanesulfonic acid ester, N-hydroxysuccinimide trifluoromethanesulfonic acid ester, N-hydroxysuccinimide ethanesulfonic acid ester, N-hydroxysuccinimide 1-propanesulfonic acid. Ester, N-hydroxysuccinimide 2-propanesulfonic acid ester, N-hydroxysuccinimide 1-pentanesulfonic acid ester, N-hydroxysuccinimide 1-octanesulfonic acid ester, N-hydroxysuccinimide p-toluenesulfonic acid ester, N-hydroxysuccinimide p-methoxybenzenesulfonic acid ester, N-hydroxysuccinimide 2-chloroethanesulfonic acid ester N-hydroxysuccinimide benzenesulfonic acid ester, N-hydroxysuccinimide 2,4,6-trimethylbenzenesulfonic acid ester, N-hydroxysuccinimide 1-naphthalenesulfonic acid ester, N-hydroxysuccinimide 2-naphthalenesulfonic acid ester, N-hydroxy 2-Phenylsuccinimide methanesulfonate, N-hydroxymaleimide methanesulfonate, N-hydroxymaleimide ethanesulfonate, N-hydroxy-2-phenylmaleimide methanesulfonate, N-hydroxyglutarimide methanesulfonate N-hydroxyglutarimide benzene sulfonate, N-hydroxyphthalimide methane sulfonate, N-hydroxy Phthalimidobenzenesulfonic acid ester, N-hydroxyphthalimide trifluoromethanesulfonic acid ester, N-hydroxyphthalimide p-toluenesulfonic acid ester, N-hydroxynaphthalimide methanesulfonic acid ester, N-hydroxynaphthalimide benzenesulfonic acid ester, N-hydroxy -5-norbornene-2,3-dicarboximide methanesulfonate, N-hydroxy-5-norbornene-2,3-dicarboximide trifluoromethanesulfonate, N-hydroxy-5-norbornene-2,3- Dicarboximide p-toluenesulfonic acid ester etc. are mentioned.

  These acid generators may be used alone or in combination of two or more. The acid generator and the base generator are used in an amount of 0.1 to 50 parts by mass, preferably 0.5 to 40 parts by mass with respect to 100 parts by mass of the siloxane compound according to the present invention. When the addition amount is 0.5 parts by mass or more, the crosslinking reaction can be promoted, and when the addition amount is 40 parts by mass or less, the acid or the like moves to the upper resist to be mixed. This is because it can be prevented or the curability of the completed resist underlayer film can be improved.

[Method for forming resist underlayer film]
In order to form a resist underlayer film using the composition for a resist underlayer film according to the present invention, it may be applied to a film to be processed using a spin coater method or the like, dried and then heated. For the heating, a one-step heating or a multi-stage heating method can be used. When the multistage heating method is used, for example, it is preferable to first heat at 100 ° C. to 120 ° C. for 60 seconds to 120 seconds, and then at 200 ° C. to 250 ° C. for 60 seconds to 120 seconds. The “film to be processed” in the present invention refers to a portion where a resist underlayer film is applied. Specifically, a surface portion of a silicon wafer as a substrate, a lower layer film (organic film) applied on the silicon wafer, and the like can be given. In the present invention, “film to be processed” and “layer to be processed” are synonymous.

  The resist underlayer film thus formed preferably has a thickness of 30 nm to 200 nm. Thereafter, a resist film composition is provided on the resist underlayer film at a thickness of 100 to 300 nm to produce a resist film.

[Pattern formation method]
The pattern forming method using the resist underlayer film according to the present invention includes the following steps.

  First, a resist underlayer film composition is applied to a film to be processed and baked at a predetermined temperature to form a resist underlayer film. Next, a resist composition is applied onto the obtained resist underlayer film and baked at a predetermined temperature to form a resist film. Further, after exposing the pattern circuit area of the resist film, development is performed with a developer to form a resist pattern. Then, using the resist pattern as a mask, the resist underlayer film and the substrate are etched to form a predetermined pattern on the substrate.

  The above method will be described with reference to the drawings. First, a resist underlayer film composition is applied onto a substrate 10 having a layer to be processed using a spin coating method or the like, and baked at a predetermined temperature to form a resist underlayer film 12. Next, the resist film composition is applied using a spin coating method or the like in the same manner as described above. Next, pre-baking is performed at a predetermined temperature to form a resist film 14 (see FIG. 1A). The prebaking conditions are 150 ° C. to 300 ° C., and preferably 30 seconds to 300 seconds.

  Next, after exposing the pattern circuit area of the resist film 14, development is performed with a developer to form a resist pattern (see FIG. 1B). Further, the resist underlayer film 12 is etched using the resist film 14 as a mask. For the etching, a fluorocarbon gas, a nitrogen gas, a fluorine-based gas, or the like can be used, but it is preferable to use a fluorine-based gas such that the resist underlayer film 12 is etched faster than the resist film 14. The etching rate of the resist underlayer film 12 is preferably adjusted as appropriate according to the etching rate of the resist film 14.

  Next, the substrate 10 is etched using the resist film 14 and the resist underlayer film 12 as a mask (see FIG. 1C). For the etching, a chlorofluorocarbon gas, a nitrogen gas, an oxygen gas, or the like can be used, but it is preferable to use an oxygen gas that causes the resist underlayer film 12 to be etched later than the substrate 10. The etching rate is preferably adjusted as appropriate according to the etching rate of the substrate 10.

  As the resist composition used for forming the resist film 14, for example, a known composition such as a mixture of a base resin, an organic solvent, and an acid generator can be used.

  Base resins include polyhydroxystyrene and derivatives thereof, polyacrylic acid and derivatives thereof, polymethacrylic acid and derivatives thereof, copolymers selected from hydroxystyrene, acrylic acid, methacrylic acid and derivatives thereof, cycloolefin and derivatives thereof. Examples thereof include at least one polymer selected from the group consisting of a derivative, maleimide, acrylic acid, and three or more copolymers selected from acrylic acid and derivatives thereof, polynorbornene, and a metathesis ring-opening polymer. In addition, the main skeleton remains after the induction, such as acrylic acid derivatives such as acrylic acid esters, methacrylic acid derivatives such as methacrylic acid derivatives, and alkoxystyrenes such as hydroxystyrene derivatives. Means what

  As a resist for a KrF excimer laser, a copolymer of any one of polyhydroxystyrene, hydroxystyrene, and styrene and any one of acrylic acid ester, methacrylic acid ester, and maleimide N carboxylic acid ester may be mentioned. . Further, as resists for ArF excimer laser, acrylic acid ester-based, methacrylic acid ester-based, alternating copolymerization of norbornene and maleic anhydride, alternating copolymerization of tetracyclododecene and maleic anhydride, polynorbornene-based And metathesis polymerization systems based on ring-opening polymerization, but are not limited to these polymerization polymers.

  Furthermore, the resist underlayer film formed from the resist underlayer film composition according to the present invention can be used as an intermediate layer of a multilayer resist process such as a three-layer resist process.

  As shown in FIG. 2A, a composition for an underlayer film is applied between a substrate 20 and a resist underlayer film 22 by using a spin coat method or the like, and baked at a predetermined temperature to form an underlayer film 26 ( Bottom layer). Next, a resist film 24 and a resist underlayer film 22 are formed by the same method as described above.

  By the same method as described above, the resist underlayer film 22 is etched using the resist film 24 on which the pattern is formed as a mask, and the resist pattern is transferred to the resist underlayer film 22 (see FIG. 2B). The lower layer film 26 is etched using the resist film 24 and the resist lower layer film 22 as a mask, and the resist pattern is transferred to the lower layer film 26 (see FIG. 2C). At this time, the resist film 24 is also etched away. Next, etching is performed in the same manner as described above to form a pattern on the substrate 20 (see FIG. 2D).

  Since this lower layer film 26 acts as a mask when etching the substrate 20, it is desirable that the lower layer film 26 has high etching resistance and is not required to be mixed with the upper resist lower layer film 22. Alternatively, it is desirable to crosslink with an acid. Specifically, it is preferable to use a resin such as cresol novolak, naphthol novolak, catol dicyclopentadiene novolak, amorphous carbon, polyhydroxystyrene, (meth) acrylate, polyimide, polysulfone.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.

[Example 1]
<Preparation of composition for resist underlayer film>
A monomer having the following structure was hydrolyzed and polymerized to obtain a copolymer. In that case, content in the copolymer obtained by adjusting the addition amount of each monomer was adjusted. The ethoxy group in the formula is not particularly limited as long as it is an alkoxy group having 1 to 4 carbon atoms.

The structure of the obtained copolymer is as shown below. Table 1 shows the content of each structural unit, the content of carbon atoms, and the content of silicon atoms.

  A composition obtained by mixing 3880 parts by mass of propylene glycol monomethyl ether acetate as a solvent with respect to 100 parts by mass of each of the above copolymers was used as a resist underlayer film composition.

The resist underlayer film was formed by the following procedure. First, a composition for forming an underlayer film containing a novolak resin is applied to a surface of a silicon wafer having a SiO ₂ layer having a thickness of 500 nm using a general-purpose resist coater, and heat-treated at 250 ° C. for 90 seconds. As a result, a bottom layer (lower layer film) having a thickness of 220 nm was formed.

  Next, the resist underlayer film composition described above was applied on the bottom layer, and heat treatment was performed at 250 ° C. for 90 seconds to form a resist underlayer film having a thickness of 12000 nm. Further, a resist composition was applied on the resist underlayer film (antireflection film) to form a resist layer, and exposed and developed with an ArF excimer laser to form a line pattern. These were designated as Sample 1 and Sample 2. Note that the k values of Sample 1 and Sample 2 were both 0.12.

２）酸発生剤１：下記の構造式の化合物・・・２．０質量部

３）酸発生剤２：下記の構造式の化合物・・・０．８質量部

４）酸失活剤１：トリエタノールアミン・・・０．２５質量部
５）酸失活剤２：γ−ブチロラクトン・・・２５．０質量部
６）溶剤：プロピレングリコールモノメチルエーテルアセテート：プロピレングリコールモノメチルエーテル＝６：４で混合した混合液 As the resist composition, a resin, an acid generator, an acid quencher, and a solvent mixed in a predetermined composition were used. Specifically, those having the following composition were used.
1) Resin: Resin having units (D1: D2: D3 = 4: 4: 2, weight average molecular weight 10,000) represented by the following structural formula: 100 parts by mass

2) Acid generator 1: Compound having the following structural formula: 2.0 parts by mass

3) Acid generator 2: Compound of the following structural formula: 0.8 part by mass

4) Acid quencher 1: Triethanolamine 0.25 parts by mass 5) Acid quencher 2: γ-butyrolactone 25.0 parts by mass 6) Solvent: Propylene glycol monomethyl ether acetate: Propylene glycol Monomethyl ether = 6: 4 mixed liquid

[Comparative Example 1]
A monomer having the following structure was hydrolyzed and polymerized to obtain a copolymer. In that case, content in the copolymer obtained by adjusting the addition amount of each monomer was adjusted.

The structure of the obtained copolymer is as shown below. Table 1 shows the content of each structural unit, the content of carbon atoms, and the content of silicon atoms. A comparative sample 1 was obtained by forming a pattern of this copolymer in the same manner as in Example 1.

[Examination of etching selectivity]
The etching selectivity of Samples 1 and 2 and Comparative Sample 1 was examined. The sample was formed by spin coating a silicon wafer and performing heat treatment at 250 ° C. for 90 minutes.

Specifically, the etching rate was determined under the conditions of the following processes 1) and 2).
Process 1) Comparison of resist layer and resist underlayer film Chamber pressure 3.00 mmTorr
RF power 1600W
Bias 150W
Temperature 20 ° C
Time 30sec
Etching gas _{C 4 F 8 / Ar = 38cc} / 100cc
Process 2) Comparison between resist underlayer film and underlayer film Chamber pressure 3.00 mmTorr
RF power 1600W
Bias 70W
Temperature -10 ° C
Time 3min
Etching gas O ₂ / N ₂ = 60cc / 40cc
Table 2 shows the etching rates in the above processes 1) and 2).

  From this, it was shown that the composition for resist underlayer films according to the present invention has excellent etching selectivity.

It is the figure which showed the process of forming a resist pattern using the composition for resist underlayer films concerning this invention. It is the figure which showed the process of forming a resist pattern using the composition for resist underlayer films concerning this invention.

Explanation of symbols

10, 20 Substrate 12, 22 Resist underlayer film 14, 24 Resist film 26 Underlayer film

Claims (12)

A resist underlayer film composition containing a copolymer having a structural unit represented by the following general formula (1a), (1b), (1c),

[Wherein, R ¹ is a monovalent organic group having crosslinkability, R ² is a monovalent organic group having light absorption, and R ³ is a lower alkyl group having 1 to 3 carbon atoms. ]
The content of the structural unit represented by the general formula (1a) in the copolymer is from 10 mol% to 75 mol%, and the content of the structural unit represented by the general formula (1b) is from 5 mol% to 20 mol%. A composition for a resist underlayer film, wherein the content of the structural unit represented by the general formula (1c) is from 5 mol% to 70 mol%. The composition for a resist underlayer film according to claim 1, wherein R ³ is a methyl group. 3. The resist underlayer film composition according to claim ¹ , wherein R ¹ is an organic group having a molecular weight of 50 to 300 having an epoxy group or an oxetanyl group. The composition for a resist underlayer film according to any one of claims 1 to 3, wherein R ¹ is an organic group having 4 to 15 carbon atoms. 5. The resist underlayer film composition according to claim 1, wherein R ¹ further has at least one ether bond.   The content of the structural unit represented by the general formula (1a) in the copolymer is 45 mol% to 70 mol%, and the content of the structural unit represented by the general formula (1b) is 10 mol% to 15 mol%. The composition for a resist underlayer film according to claim 1, wherein the content of the structural unit represented by the general formula (1c) is from 20 mol% to 45 mol%. The composition for a resist underlayer film according to any one of claims 1 to 6, wherein the copolymer is a structural unit represented by the following general formulas (2a), (2b), and (2c).

  The resist underlayer film composition according to any one of claims 1 to 7, further comprising an acid generator.   The composition for a resist underlayer film according to any one of claims 1 to 8, further comprising a crosslinking agent.   A resist underlayer film obtained by applying the resist underlayer film composition according to claim 1 to a substrate and baking it at a predetermined temperature. A method of forming a pattern on a work film by lithography,
Applying the composition for a resist underlayer film according to any one of claims 1 to 9 to a film to be processed and baking at a predetermined temperature to form a resist underlayer film;
Applying a resist composition on the obtained resist underlayer film and baking at a predetermined temperature to form a resist film;
Forming a resist pattern by developing with a developer after exposing the pattern circuit area of the resist film; and
Etching the resist underlayer film and the film to be processed using the resist pattern as a mask to form a predetermined pattern on the film to be processed; and
A method of forming a pattern on a film to be processed. The method which uses the copolymer which has a structural unit of Claim 1 or 6 in order to manufacture the composition for resist underlayer films.

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