Composition for forming spin-on carbon films, method for producing a spin-on carbon film formation composition, underlayer film for lithography, method for forming resist patterns, and method for forming circuit patterns

Abstract

This spin-on-carbon film-forming composition comprises a dendritic polymer and is a composition for forming a spin-on-carbon film that functions as a lithographic underlayer film.

Description

[Technical Field]

[0001] The present invention relates to a composition for forming a spin-on carbon film, a method for producing a spin-on carbon film, a lithography underlayer film, a resist pattern formation method, and a circuit pattern formation method. [Background technology]

[0002] In semiconductor device manufacturing, microfabrication is performed using lithography with photoresist materials. However, in recent years, with the increasing integration and speed of LSIs (large-scale integrated circuits), further miniaturization using pattern rules has become necessary. Furthermore, the light sources used for lithography in resist pattern formation have been shortened from KrF excimer lasers (wavelength 248 nm) to ArF excimer lasers (wavelength 193 nm), and the introduction of extreme ultraviolet light (EUV; wavelength 13.5 nm) is also anticipated.

[0003] As resist patterns become finer, problems arise such as resolution issues or the resist pattern collapsing after development, making it desirable to thin the resist. However, simply thinning the resist makes it difficult to obtain a sufficient resist pattern thickness for substrate processing. Therefore, a process is needed that not only thins the resist pattern but also creates an underlayer film between the resist and the semiconductor substrate to be processed, and this underlayer film also functions as a mask during substrate processing. Conventional underlayer films have functions to improve the resist pattern shape by providing anti-reflective properties and suppressing resist pattern collapse. For such conventional underlayer films, materials with high etching rates have been used from the viewpoint of easy removal. On the other hand, in processes where the underlayer film is required to function as a mask during substrate processing, an underlayer film with a low selectivity ratio for etching rate, similar to the resist, is used. Such an underlayer film is also called a "spin-on carbon film".

[0004] Currently, various types of underlayer films for lithography are known. For example, an underlayer film forming material for multilayer resist processes has been proposed that contains a resin component having at least substituents that detach terminal groups to produce sulfonic acid residues when a predetermined energy is applied, and a solvent (see, for example, Patent Document 1). In addition, an underlayer film material containing a polymer having specific repeating units has been proposed to realize an underlayer film for lithography with a selectivity ratio for dry etching rate smaller than that of a resist (see, for example, Patent Document 2). Furthermore, a resist underlayer film material has been proposed that contains a polymer copolymerized with repeating units of acenaphthylenes and repeating units having substituted or unsubstituted hydroxyl groups to realize an underlayer film for lithography with a selectivity ratio for dry etching rate smaller than that of a semiconductor substrate (see, for example, Patent Document 3). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2004-177668 [Patent Document 2] Japanese Patent Publication No. 2004-271838 [Patent Document 3] Japanese Patent Publication No. 2005-250434 [Overview of the project] [Problems that the invention aims to solve]

[0006] The lithography film-forming materials described in Patent Documents 1 to 3 still have room for improvement in terms of storage stability, thin film formation ability, etching resistance, embedding ability, and flatness, as well as in providing a good resist pattern shape.

[0007] The present invention has been made in view of the above problems, and aims to provide a spin-on carbon film formation composition, etc., that is excellent in storage stability, thin film formation ability, etching resistance, embedding ability and flatness, and that can impart a good resist pattern shape. [Means for solving the problem]

[0008] The inventors of this invention conducted extensive research to solve the aforementioned problems and, as a result, discovered that the above problems could be solved by using dendritic polymers, thus completing the present invention.

[0009] In other words, the present invention is as follows. [1] A composition for forming a spin-on carbon film as an underlayer for lithography, A composition for forming spin-on carbon films, containing a dendritic polymer. [2] The spin-on carbon film forming composition according to [1], wherein the dendritic polymer has ester bonds, ketone bonds, amide bonds, imide bonds, urea bonds, urethane bonds, ether bonds, thioether bonds, imino bonds and / or azomethine bonds in its molecule. [3] The spin-on carbon film forming composition according to [1] or [2], wherein the dendritic polymer has a chemical structure represented by the following formula (1) in its molecule. R(R')C=N- (1) (In formula (1) above, R and R' each independently represent an arylene group which may have substituents.) [4] The spin-on carbon film forming composition according to any one of [1] to [3], wherein the thermogravimetric polymer starts at a temperature of 300°C or higher. [5] The spin-on carbon film forming composition according to any one of [1] to [4], wherein the solubility of the dendritic polymer in a semiconductor coating solvent is 0.5% by mass or more. [6] A spin-on carbon film forming composition according to any one of [1] to [5], wherein the carbon content of the dendritic polymer is 70% or more, and / or the oxygen content of the dendritic polymer is less than 20%. [7] The spin-on carbon film-forming composition according to any one of [1] to [6], further containing a solvent. [8] The spin-on carbon film-forming composition according to any one of [1] to [7], further containing at least one selected from the group consisting of an acid generator and a crosslinking agent. [9] A lower layer film for lithography, comprising the spin-on carbon film-forming composition according to any one of [1] to [8], The lower layer film for lithography, having an etching rate measured by the following method of 60 nm / min or less. <Measurement of etching rate> The etching rate of the lower layer film for lithography is measured by subjecting the lower layer film for lithography to the following etching test. (Etching test) Output: 100 W Pressure: 8 Pa Etching gas: CF4 gas (flow rate 20 (sccm))

[10] A lower layer film forming step of forming a lower layer film on a substrate using the spin-on carbon film-forming composition according to any one of [1] to [8], A photoresist layer forming step of forming at least one photoresist layer on the lower layer film formed by the lower layer film forming step, A resist pattern forming method including a step of irradiating a predetermined region of the photoresist layer formed by the photoresist layer forming step with radiation and developing.

[11] A lower layer film forming step of forming a lower layer film on a substrate using the spin-on carbon film-forming composition according to any one of [1] to [8], An intermediate layer film forming step of forming an intermediate layer film on the lower layer film formed by the lower layer film forming step, A photoresist layer forming step of forming at least one photoresist layer on the intermediate layer film formed by the intermediate layer film forming step, A resist pattern formation step involves irradiating a predetermined area of ​​the photoresist layer formed by the photoresist layer formation step with radiation and developing it to form a resist pattern, An intermediate layer pattern formation step is performed by using the resist pattern formed in the resist pattern formation step as a mask to etch the intermediate layer film and form an intermediate layer pattern, A lower layer pattern formation step is performed by using the intermediate layer pattern formed in the intermediate layer pattern formation step as a mask to etch the lower layer to form a lower layer pattern, A circuit pattern formation method comprising a substrate pattern formation step, which involves etching the substrate using the underlying film pattern formed in the underlying film pattern formation step as a mask to form a pattern on the substrate.

[12] A method for producing a spin-on carbon film forming composition according to any one of [1] to [8], A manufacturing method comprising an extraction step of contacting a solution containing the dendritic polymer and an organic solvent that is not arbitrarily miscible with water with an acidic aqueous solution for extraction.

[13] A method for producing a spin-on carbon film forming composition according to any one of [1] to [8], comprising the step of passing a solution obtained by dissolving the dendritic polymer in a solvent through a filter.

[14] A method for producing a spin-on carbon film forming composition according to any one of [1] to [8], comprising the step of contacting an ion exchange resin with a solution obtained by dissolving the dendritic polymer in a solvent. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a spin-on carbon film formation composition and the like that is excellent in storage stability, thin film formation ability, etching resistance, embedding ability and flatness, and that can impart a good resist pattern shape. [Modes for carrying out the invention]

[0011] The following describes in detail embodiments for carrying out the present invention (hereinafter also referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0012] <Composition for forming spin-on carbon films> The spin-on carbon film formation composition of this embodiment is a composition for forming a spin-on carbon film as an underlayer film for lithography, and contains a dendritic polymer. Because the spin-on carbon film formation composition of this embodiment is configured as described above, it has excellent storage stability, thin film formation properties, etching resistance, embedding properties, and flatness, and can impart a good resist pattern shape.

[0013] In this embodiment, a spin-on carbon film refers to a carbon-rich film formed by a rotary coating method, and means a functional film that is resistant to etching. A spin-on carbon film forming composition refers to a composition used for forming the spin-on carbon film. The dendritic polymer, which will be described in detail later, is suitable for the above application because, due to its structure, it can achieve high density when formed into a film. The spin-on carbon film in this embodiment is used as an underlayer film for lithography. The fact that it is a spin-on carbon film is not limited to the following, but can typically be confirmed by the etching rate measured in the etching rate measurement described later, which is 60 nm / min or less. Furthermore, it is preferable that the spin-on carbon film in this embodiment has excellent embedding properties into stepped substrates and flatness.

[0014] [Dendritic polymers] Dendritic polymers are polymers that have a branched structure within their polymer chains, meaning they are composed of molecular structures that frequently repeat regular branching. In dendritic polymers, the branched structure allows them to become nano-sized functional polymers. Furthermore, because the backbone of dendritic polymers is three-dimensionally crowded due to the repeating branching structure, they tend to have a structure in which atoms are densely concentrated. Thus, dendritic polymers tend to form high-density polymer films, resulting in a carbon-rich structure, and when used as an underlayer film for lithography, it provides high etching resistance.

[0015] While there are no particular limitations on dendritic polymers, those described in "Dendritic Polymers" (The Society of Polymer Science, Japan, Kyoritsu Shuppan (2013)) can be used, for example. Dendritic polymers are characterized by the number of terminal groups. While general linear polymers have 2 terminal groups and 0 branching, dendritic polymers typically tend to have 3 or more terminal groups and 1 or more branching.

[0016] The term "generation" is sometimes used to describe the degree of polymerization of dendritic polymers. A structure in which one layer of molecules with terminal groups are bonded around a core (described later) is called the "first generation," and one with two layers is called the "second generation." A dendritic polymer may have a structure that is specifically defined as having one or more layers of molecules with terminal groups bonded around a core. The dendritic polymer used in this embodiment is not particularly limited, but from the viewpoint of solubility and flatness, fifth generation or lower is preferred, and fourth generation or lower is even more preferred.

[0017] As the dendritic polymer, various known dendritic polymers such as dendrimers, hyperbranch polymers, star polymers, and polymer brushes may be used. The dendritic polymer can be used individually or in combination of two or more types.

[0018] In this embodiment, dendrimers are preferred from the viewpoint of stability of various physical properties, and hyperbranched polymers are preferred from the viewpoint of ease of manufacture. They can be appropriately selected and used depending on the required performance.

[0019] Various known dendrimers can be used as dendritic polymers in this embodiment, and are not limited to the following, but examples include those described as dendrimers in Japanese Patent Publication Nos. 2000-344836, 2004-331850, 2009-029753, 2008-088275, and Hei 10-310545.

[0020] Various known hyperbranched polymers can be used as dendritic polymers in this embodiment, and are not limited to the following, but include, for example, those described as hyperbranched polymers in Japanese Patent Publication No. 2000-344836, International Publication No. 2006-25236, International Publication No. 2012-60286, and International Publication No. 2015-87969.

[0021] The dendritic polymer may have, for example, a core with 2 to 100 carbon atoms and a valent or greater valentity, and the core may contain an arylene group (an organic group derived from aromatic compounds such as a benzene ring, biphenyl ring, naphthalene ring, anthracene ring, pyrene ring, dibenzochrysene ring, or fluorene ring). The organic group may have substituents. The substituents are not particularly limited, but from the viewpoint of solubility, hydroxyl groups, thiol groups, sulfonic acid groups, hexafluoropropanol groups, amino groups, or carboxyl groups are preferred. The core may also contain heteroatoms, and it is preferable that it contains a triazine group. The number of carbon atoms in the core is preferably 2 to 80 from the viewpoint of ensuring various physical properties, more preferably 2 to 60 from the viewpoint of storage stability, even more preferably 2 to 40 from the viewpoint of thin film formation, and even more preferably 2 to 20 from the viewpoint of solubility.

[0022] The dendritic polymer may contain the structures described above as being included in the core, but may also contain them in parts other than the core. Furthermore, the dendritic polymer may contain alkyl groups having 1 to 40 carbon atoms that may be substituted, aryl groups having 6 to 40 carbon atoms that may be substituted, alkenyl groups having 2 to 40 carbon atoms that may be substituted, alkynyl groups having 2 to 40 carbon atoms that may be substituted, alkoxy groups having 1 to 40 carbon atoms that may be substituted, halogen atoms, thiol groups, amino groups, nitro groups, carboxyl groups and / or hydroxyl groups, and may also contain alkylene groups having 1 to 40 carbon atoms that may be substituted, alkenylene groups and / or alkynylene groups. Moreover, the dendritic polymer may contain ester bonds, ketone bonds, amide bonds, imide bonds, urea bonds, urethane bonds, ether bonds, thioether bonds, imino bonds and / or azomethine bonds. Dendritic polymers may contain one or more of the aforementioned functional groups or bonds.

[0023] In this embodiment, the dendritic polymer preferably has alkylene groups, alkenylene groups, alkylylene groups, ester bonds, ketone bonds, amide bonds, imide bonds, urea bonds, urethane bonds, ether bonds, thioether bonds, imino bonds and / or azomethine bonds in its molecule from the viewpoint of heat resistance; more preferably has ester bonds, ketone bonds, amide bonds, imide bonds, urea bonds, urethane bonds, ether bonds, thioether bonds, imino bonds and / or azomethine bonds from the viewpoint of storage stability; particularly preferably has imino bonds and / or azomethine bonds from the viewpoint of etching resistance; and even more preferably has azomethine bonds from the viewpoint of further improving heat resistance, storage stability, thin film formation, etching resistance, embedding ability and flatness, and providing a better resist pattern shape. In this embodiment, from the viewpoint of storage stability, it is preferable that the dendritic polymer does not contain an ethynyl group in its molecule. Furthermore, in this embodiment, from the viewpoint of further improving heat resistance, storage stability, thin film formation properties, etching resistance, embedding properties, and flatness, and providing a better resist pattern shape, it is preferable that the dendritic polymer does not contain alicyclic rings in its molecule.

[0024] In this embodiment, the dendritic polymer preferably has an organic group derived from an aromatic compound such as a benzene ring, biphenyl ring, naphthalene ring, anthracene ring, pyrene ring, dibenzochrysene ring, or fluorene ring, or a dissociable group or a crosslinkable group as its terminal group, and these may have substituents, and from the viewpoint of solubility, a hydroxyl group, thiol group, sulfonic acid group, hexafluoropropanol group, amino group, or carboxyl group is preferred as such substituent. In this embodiment, the dendritic polymer is more preferably to have a phenolic hydroxyl group or a dissociable group as its terminal group.

[0025] In this embodiment, from the viewpoint of further improving heat resistance, storage stability, thin film formation ability, etching resistance, embedding ability, and flatness, and providing a better resist pattern shape, it is preferable that the dendritic polymer has a chemical structure represented by the following formula (1) in its molecule. R(R')C=N- (1) (In formula (1) above, R and R' each independently represent an arylene group which may have substituents.) The arylene group in formula (1) above is not particularly limited, but examples include optionally substituted phenylene group, optionally substituted biphenylene group, optionally substituted naphthylene group, optionally substituted anthracenylene group, optionally substituted pyrenylene group, optionally substituted fluorenylene group, etc. The substituent is not particularly limited, but from the viewpoint of solubility, a hydroxyl group, a thiol group, a sulfonic acid group, a hexafluoropropanol group, an amino group, or a carboxyl group is preferred. In this embodiment, from the viewpoint of further improving heat resistance, storage stability, thin film formation, etching resistance, embedding ability, and flatness, and providing a better resist pattern shape, R and R' are each preferably independently arylene groups having -OH, -OC(=O)-CH3, or -O-CH2-O-CH3 as a substitution, and more preferably phenylene groups having -OH, -OC(=O)-CH3, or -O-CH2-O-CH3 as a substitution.

[0026] Specific examples of structures that may be included in dendritic polymers include, but are not limited to, the following divalent groups or combinations thereof, which may have substituents. [ka] [ka] [ka]

[0027] In this embodiment, unless otherwise defined, "substitution" means that at least one hydrogen atom bonded to a carbon atom constituting an aromatic ring, and at least one hydrogen atom in a certain functional group, is substituted with a substituent. Unless otherwise defined, examples of "substituents" include halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, thiol groups, heterocyclic groups, alkyl groups with 1 to 30 carbon atoms, aryl groups with 6 to 20 carbon atoms, alkoxyl groups with 1 to 30 carbon atoms, alkenyl groups with 2 to 30 carbon atoms, alkynyl groups with 2 to 30 carbon atoms, acyl groups with 1 to 30 carbon atoms, and amino groups with 0 to 30 carbon atoms. In this embodiment, unless otherwise defined, "alkyl group" may be any of the following: a linear aliphatic hydrocarbon group, a branched aliphatic hydrocarbon group, or a cyclic aliphatic hydrocarbon group.

[0028] In this embodiment, "dissociable group" refers to a group that dissociates in the presence or absence of a catalyst. Among dissociable groups, an acid-dissociable group refers to a group that cleaves in the presence of an acid and changes into an alkali-soluble group, etc. The alkali-soluble group is not particularly limited, but examples include phenolic hydroxyl groups, carboxyl groups, sulfonic acid groups, and hexafluoroisopropanol groups. Among these, phenolic hydroxyl groups and carboxyl groups are preferred from the viewpoint of the availability of the introduction reagent, and phenolic hydroxyl groups are more preferred. To enable highly sensitive and high-resolution pattern formation, it is preferable that the acid-dissociable group has the property of undergoing a chain reaction of cleavage in the presence of an acid. The acid-dissociable group is not particularly limited, but can be appropriately selected from those proposed for use in hydroxystyrene resins and (meth)acrylic acid resins used in chemically amplified resist compositions for KrF and ArF. Specific examples of acid-dissociable groups include those described in International Publication No. 2016 / 158168. Suitable acid-dissociable groups include 1-substituted ethyl groups, 1-substituted n-propyl groups, 1-branched alkyl groups, silyl groups, acyl groups, 1-substituted alkoxymethyl groups, cyclic ether groups, alkoxycarbonyl groups, and alkoxycarbonylalkyl groups, which have the property of dissociating with acid.

[0029] In this embodiment, "crosslinkable group" refers to a group that crosslinks in the presence or absence of a catalyst. The crosslinkable group is not particularly limited, but examples include alkoxy groups having 1 to 20 carbon atoms, groups having an allyl group, groups having a (meth)acryloyl group, groups having an epoxy(meth)acryloyl group, groups having a hydroxyl group, groups having a urethane(meth)acryloyl group, groups having a glycidyl group, groups having a vinylphenylmethyl group, groups having various alkynyl groups, groups having a carbon-carbon double bond, groups having a carbon-carbon triple bond, and groups containing these groups. Preferred examples of groups containing these groups include the alkoxy group-ORx of the above-mentioned groups (where Rx is a group having an allyl group, a group having a (meth)acryloyl group, a group having an epoxy(meth)acryloyl group, a group having a hydroxyl group, a group having a urethane(meth)acryloyl group, a group having a glycidyl group, a group having a vinylphenylmethyl group, a group having various alkynyl groups, a group having a carbon-carbon double bond, a group having a carbon-carbon triple bond, and a group containing these groups).

[0030] The dendritic polymer in this embodiment is not limited to the following, but for example, the following compounds can be used. [ka] [ka] [ka] (In the formula, R0 is a hydroxyl group, alkoxy group, thiol group, sulfonic acid group, hexafluoropropanol group, amino group, carboxyl group, or a group in which the hydrogen atoms of these groups are substituted with a dissociable group or a crosslinking group, and it is preferable that at least one R0 is a hydroxyl group, and more preferably that all R0 are hydroxyl groups.)

[0031] The dendritic polymer in this embodiment is not limited to the following, but for example, the following compounds can also be used. [ka] TIFF0007861318000008.tif59170 (wherein R0 is a hydroxyl group, alkoxy group, thiol group, sulfonic acid group, hexafluoropropanol group, amino group, carboxyl group, or a group in which the hydrogen atoms of these groups are substituted with a dissociable group or a crosslinking group, preferably at least one R0 is a hydroxyl group, and more preferably all R0 are hydroxyl groups.)

[0032] The method for producing the dendritic polymer in this embodiment is not particularly limited and can be synthesized by various known methods. Furthermore, commercially available dendritic polymers can also be used.

[0033] In this embodiment, from the viewpoint of heat resistance, the temperature at which the thermal weight loss of the dendritic polymer begins is preferably 300°C or higher, more preferably 350°C or higher, even more preferably 400°C or higher, even more preferably 450°C or higher, and even more preferably 500°C or higher. The thermogravimetric analysis onset temperature can be measured based on the method described in the examples below. The thermogravimetric reduction initiation temperature can be adjusted to the range described above by, for example, appropriately selecting the raw materials for the dendritic polymer to have the preferred chemical structure described above, or by adjusting the carbon content and / or oxygen content to the preferred range described later.

[0034] In this embodiment, from the viewpoint of facilitating the application of wet processes, the solubility of the dendritic polymer in the semiconductor coating solvent is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 5% by mass or more, and even more preferably 10% by mass or more. In this embodiment, the semiconductor coating solvent refers to propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), cyclohexanone (CHN), cyclopentanone (CPN), ethyl lactate (EL), and methyl hydroxyisobutyrate (HBM). Solubility can be measured based on the method described in the examples below. The solubility can be adjusted to the range described above by, for example, appropriately selecting the raw materials for the dendritic polymer to have the preferred chemical structure described above, or by controlling the molecular weight to the preferred range described later.

[0035] In this embodiment, from the viewpoint of etching resistance, it is preferable that the carbon content of the dendritic polymer is 70% or more and / or the oxygen content of the dendritic polymer is less than 20%, and at least the oxygen content of the dendritic polymer is less than 20%. More specifically, from the viewpoint of etching resistance, the carbon content of the dendritic polymer is preferably 70% or more, more preferably 75% or more, even more preferably 80% or more, and particularly preferably 85% or more. From a similar viewpoint, the oxygen content is preferably less than 20%, more preferably less than 17.5%, even more preferably less than 15%, and particularly preferably less than 10%. The carbon content and oxygen content can be measured based on the method described in the examples below. The carbon content and oxygen content can be adjusted to the above-mentioned ranges, for example, by appropriately selecting the raw materials for the dendritic polymer to have the preferred chemical structure described above. The dendritic polymer may be subjected to treatments such as high-temperature baking or reaction with other compounds, and the resulting carbon content and / or oxygen content may fall within the above range.

[0036] In this embodiment, the dendritic polymer has a Si content and / or F content of less than 1%, and preferably a Si content and / or F content of 0%. When the dendritic polymer contains Si or F, the etching resistance tends to decrease significantly under fluorocarbon gas conditions suitable for processing inorganic materials such as silicon wafers. By having a Si content and / or F content of less than 1%, sufficient etching resistance can be ensured even under the conditions described in the (etching test) described later.

[0037] In this embodiment, from the viewpoint of heat resistance, the molecular weight of the dendritic polymer is preferably 400 to 1,000,000, more preferably 800 to 50,000, and even more preferably 1,200 to 10,000 from the viewpoint of resolution. When the molecular weight of the dendritic polymer is 1,200 or more, the molecules tend to form a dense film that is close to spherical, which is thought to improve resolution, but this is not intended to limit the mechanism of action to the above. Furthermore, from the viewpoint of flatness, 350 to 5,000 is preferred, 500 to 3,000 is more preferred, and 950 to 2,000 is even more preferred. Molecular weight can be measured by liquid chromatography-mass spectrometry (LC-MS) for molecules with a molecular weight of less than approximately 2000, and by gel permeation chromatography (GPC) analysis for molecules with a larger molecular weight. Specifically, it can be measured based on the method described in the examples below.

[0038] In this embodiment, if the dendritic polymer molecule contains hydroxyl groups, at least one of them may be protected by a protecting group. The spin-on carbon film forming composition of this embodiment preferably includes a dendritic polymer having at least one hydroxyl group in its molecule and a dendritic polymer in which at least one of the hydroxyl groups in the molecule is protected by a protecting group. In this case, a film containing both protected and unprotected groups is formed, which is thought to improve adhesion to the resist film and suppress pattern collapse and distortion, but the mechanism of action is not intended to be limited to the above. Various known protecting groups can be used as the protecting group, but from the same viewpoint as above, -CH2OCH3 is preferred.

[0039] [Other ingredients] The spin-on carbon film-forming composition of this embodiment contains the dendritic polymer as an essential component, and considering its use as a lithography underlayer film-forming material, it may further contain various optional components. Specifically, the spin-on carbon film-forming composition of this embodiment preferably further contains at least one selected from the group consisting of solvents, acid generators, and crosslinking agents.

[0040] In this embodiment, the content of the dendritic polymer is preferably 1 to 100% by mass, more preferably 10 to 100% by mass, even more preferably 50 to 100% by mass, and particularly preferably 100% by mass, relative to the total solid content (components other than the solvent in the spin-on carbon film forming composition of this embodiment), from the viewpoint of coatability and quality stability.

[0041] When the spin-on carbon film forming composition of this embodiment contains a solvent, the content of the dendritic polymer in this embodiment is not particularly limited, but is preferably 0.5 to 33 parts by mass, more preferably 0.5 to 25 parts by mass, and even more preferably 0.5 to 20 parts by mass, per 100 parts by mass of the total amount including the solvent.

[0042] The spin-on carbon film formation composition of this embodiment can be applied to wet processes and has excellent heat resistance and etching resistance. Furthermore, because the spin-on carbon film formation composition of this embodiment contains the dendritic polymer of this embodiment, film degradation during high-temperature baking is suppressed, and an underlayer film with excellent etching resistance to oxygen plasma etching and the like can be formed. In addition, the spin-on carbon film formation composition of this embodiment has excellent adhesion to the resist layer, so an excellent resist pattern can be obtained. Note that the spin-on carbon film formation composition of this embodiment may contain already known lithography underlayer film formation materials, etc., to the extent that the desired effects of this embodiment are not impaired.

[0043] (solvent) As the solvent used in the spin-on carbon film forming composition of this embodiment, any known solvent can be used as appropriate, as long as it can at least dissolve the dendritic polymer of this embodiment.

[0044] Specific examples of solvents are not limited to those described in International Publication No. 2013 / 024779. These solvents can be used individually or in combination of two or more.

[0045] Among the solvents mentioned above, cyclohexanone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, methyl hydroxyisobutyrate, and anisole are particularly preferred from a safety standpoint.

[0046] The solvent content is not particularly limited, but from the viewpoint of solubility and film formation, it is preferably 100 to 30,000 parts by mass, more preferably 200 to 20,000 parts by mass, and even more preferably 250 to 15,000 parts by mass per 100 parts by mass of the dendritic polymer in this embodiment.

[0047] (Crosslinking agent) The spin-on carbon film forming composition of this embodiment may contain a crosslinking agent as needed, from the viewpoint of suppressing intermixing, etc. The crosslinking agent usable in this embodiment is not particularly limited, but for example, those described in International Publication Nos. 2013 / 024778, 2013 / 024779, and 2018 / 016614 can be used. In this embodiment, the crosslinking agent can be used alone or in combination of two or more.

[0048] Specific examples of crosslinking agents usable in this embodiment include, but are not limited to, phenol compounds, epoxy compounds, cyanate compounds, amino compounds, benzoxazine compounds, acrylate compounds, melamine compounds, guanamine compounds, glycoluryl compounds, urea compounds, isocyanate compounds, and azide compounds. These crosslinking agents can be used individually or in combination of two or more. Among these, benzoxazine compounds, epoxy compounds, or cyanate compounds are preferred, and benzoxazine compounds are more preferred from the viewpoint of improving etching resistance. Melamine compounds and urea compounds are more preferred from the viewpoint of having good reactivity. Examples of melamine compounds include the compound represented by formula (a) (Nicalac MW-100LM (trade name), manufactured by Sanwa Chemical Co., Ltd.) and the compound represented by formula (b) (Nicalac MX270 (trade name), manufactured by Sanwa Chemical Co., Ltd.).

[0049] [ka]

[0050] The phenol compound can be any known compound and is not particularly limited. In this embodiment, from the viewpoint of improving etching resistance, a phenol compound containing a condensed aromatic ring is more preferred as the crosslinking agent. Furthermore, from the viewpoint of improving planarity, a phenol compound containing a methylol group is more preferred.

[0051] From the viewpoint of improving planarity, methylol group-containing phenol compounds used as crosslinking agents are preferred if they are represented by the following formulas (11-1) or (11-2). [ka]

[0052] In the crosslinking agent represented by general formula (11-1) or (11-2), V is a single bond or an n-valent organic group, R2 and R4 are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R3 and R5 are each independently an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 40 carbon atoms. n is an integer from 2 to 10, and r is each independently an integer from 0 to 6.

[0053] Specific examples of general formulas (11-1) or (11-2) include compounds represented by the following formulas. However, general formulas (11-1) or (11-2) are not limited to compounds represented by the following formulas, and include general formulas (11-24) to (11-34). Compounds represented by general formulas (11-32) to (11-34) are preferred from the viewpoint of heat resistance and are applicable at higher temperatures.

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] The epoxy compound can be any known compound and is not particularly limited, but preferably, in terms of heat resistance and solubility, it is an epoxy resin that is solid at room temperature, such as epoxy resins obtained from phenol aralkyl resins or biphenyl aralkyl resins.

[0058] The cyanate compound can be any known compound having two or more cyanate groups in one molecule, and there are no particular limitations on such compounds. In this embodiment, preferred cyanate compounds include those in which the hydroxyl groups of a compound having two or more hydroxyl groups in one molecule are substituted with cyanate groups. Furthermore, cyanate compounds having aromatic groups are preferred, and those in which the cyanate group is directly bonded to the aromatic group can be suitably used. Such cyanate compounds are not particularly limited, but examples include those in which a hydroxyl group is substituted with a cyanate group, such as bisphenol A, bisphenol F, bisphenol M, bisphenol P, bisphenol E, phenol novolac resin, cresol novolac resin, dicyclopentadiene novolac resin, tetramethylbisphenol F, bisphenol A novolac resin, brominated bisphenol A, brominated phenol novolac resin, trifunctional phenol, tetrafunctional phenol, naphthalene-type phenol, biphenyl-type phenol, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin, dicyclopentadiene aralkyl resin, alicyclic phenol, phosphorus-containing phenol, etc. Furthermore, the above-mentioned cyanate compounds may be in any form, such as monomers, oligomers, or resins.

[0059] While known amino compounds can be used and are not particularly limited, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, and 4,4'-diaminodiphenyl ether are preferred from the viewpoint of heat resistance and raw material availability.

[0060] While known benzoxazine compounds can be used and are not particularly limited, Pd-type benzoxazines obtained from bifunctional diamines and monofunctional phenols are preferred from the viewpoint of heat resistance.

[0061] While known melamine compounds can be used and are not particularly limited, hexamethylmelamine, hexamethoxymethylmelamine, compounds in which 1 to 6 methylol groups of hexamethylmelamine are methoxymethylated, or mixtures thereof are preferred from the viewpoint of raw material availability.

[0062] The guanamine compound can be any known compound and is not particularly limited, but tetramethylolguanamine, tetramethoxymethylguanamine, a compound in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated, or a mixture thereof is preferred from the viewpoint of heat resistance.

[0063] While known glycoluryl compounds can be used and are not particularly limited, tetramethylol glycoluryl and tetramethoxyglycoluryl are preferred from the viewpoint of heat resistance and etching resistance.

[0064] The urea compound can be any known compound and is not particularly limited, but tetramethylurea and tetramethoxymethylurea are preferred from the viewpoint of heat resistance.

[0065] Furthermore, in this embodiment, a crosslinking agent having at least one allyl group may be used from the viewpoint of improving crosslinkability. Among these, allylphenols such as 2,2-bis(3-allyl-4-hydroxyphenyl)propane, 1,1,1,3,3,3-hexafluoro-2,2-bis(3-allyl-4-hydroxyphenyl)propane, bis(3-allyl-4-hydroxyphenyl)sulfone, bis(3-allyl-4-hydroxyphenyl)sulfide, and bis(3-allyl-4-hydroxyphenyl)ether are preferred.

[0066] In the spin-on carbon film-forming composition of this embodiment, the crosslinking agent content is not particularly limited, but is preferably 5 to 50 parts by mass, and more preferably 10 to 40 parts by mass, per 100 parts by mass of the dendritic polymer in this embodiment. By setting the content within the above preferred range, the occurrence of mixing with the resist layer tends to be suppressed, the anti-reflective effect is enhanced, and the film-forming ability after crosslinking tends to be improved.

[0067] (Crosslinking promoter) The spin-on carbon film forming composition of this embodiment may optionally contain a crosslinking accelerator to promote the crosslinking and curing reactions.

[0068] The aforementioned crosslinking accelerator is not particularly limited as long as it promotes the crosslinking and curing reactions, but examples include amines, imidazoles, organophosphines, Lewis acids, etc. These crosslinking accelerators can be used individually or in combination of two or more. Among these, imidazoles or organophosphines are preferred, and from the viewpoint of lowering the crosslinking temperature, imidazoles are more preferred.

[0069] The aforementioned crosslinking accelerator can be any known one and is not particularly limited, but examples include those described in International Publication No. 2018 / 016614. From the viewpoint of heat resistance and curing acceleration, 2-methylimidazole, 2-phenylimidazole, and 2-ethyl-4-methylimidazole are particularly preferred.

[0070] The crosslinking accelerator is typically contained in an amount of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.1 to 3 parts by mass, based on a total mass of 100 parts by mass of the composition.

[0071] (Radical polymerization initiator) The spin-on carbon film forming composition of this embodiment may optionally contain a radical polymerization initiator. The radical polymerization initiator may be a photopolymerization initiator that initiates radical polymerization by light, or a thermal polymerization initiator that initiates radical polymerization by heat. The radical polymerization initiator may be at least one selected from the group consisting of, for example, ketone-based photopolymerization initiators, organic peroxide-based polymerization initiators, and azo-based polymerization initiators.

[0072] Such radical polymerization initiators are not particularly limited, and conventionally used ones can be used as appropriate. For example, those described in International Publication No. 2018 / 016614 can be cited. Among these, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, and t-butylcumyl peroxide are particularly preferred from the viewpoint of raw material availability and storage stability.

[0073] The radical polymerization initiator used in this embodiment may be one of these used alone, or two or more used in combination, or it may be used in combination with other known polymerization initiators.

[0074] (Acid generator) The spin-on carbon film forming composition of this embodiment may optionally contain an acid generator to further promote the thermal crosslinking reaction. Known acid generators include those that generate acid by thermal decomposition and those that generate acid by light irradiation, and any of these can be used.

[0075] The acid generator is not particularly limited, but for example, one described in International Publication No. 2013 / 024779 can be used. In this embodiment, the acid generator can be used alone or in combination of two or more types.

[0076] In the spin-on carbon film forming composition of this embodiment, the content of the acid generator is not particularly limited, but is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 40 parts by mass, per 100 parts by mass of the polymer in this embodiment. By setting the content within the above preferred range, the amount of acid generated tends to increase, thereby enhancing the crosslinking reaction, and the occurrence of mixing with the resist layer tends to be suppressed.

[0077] (Basic compounds) Furthermore, the spin-on carbon film forming composition of this embodiment may contain a basic compound, from the viewpoint of improving storage stability, etc.

[0078] Basic compounds act as quenchers for acids, preventing trace amounts of acid generated by the acid generator from advancing the crosslinking reaction. Examples of such basic compounds include, but are not limited to, primary, secondary, or tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amide derivatives, and imide derivatives.

[0079] The basic compound used in this embodiment is not particularly limited, but for example, one described in International Publication No. 2013 / 024779 can be used. In this embodiment, the basic compound can be used alone or in combination of two or more.

[0080] In the spin-on carbon film forming composition of this embodiment, the content of the basic compound is not particularly limited, but is preferably 0.001 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, per 100 parts by mass of the dendritic polymer in this embodiment. By keeping it within the above preferred range, storage stability tends to be improved without excessively impairing the crosslinking reaction.

[0081] (Other additives) Furthermore, the spin-on carbon film forming composition of this embodiment may contain other resins and / or compounds for the purpose of imparting thermosetting properties or controlling absorbance. Examples of such other resins and / or compounds include, but are not limited to, naphthol resins, xylene resin naphthol-modified resins, phenol-modified resins of naphthalene resins, polyhydroxystyrene, dicyclopentadiene resins, (meth)acrylate, dimethacrylate, trimethacrylate, tetramethacrylate, vinylnaphthalene, polyacenaphthylene and other naphthalene rings, biphenyl rings such as phenanthrenequinone and fluorene, heteroatoms such as thiophene and indene, heterocycles containing heteroatoms, and resins that do not contain aromatic rings; rosin-based resins, cyclodextrins, adamantane(poly)ol, tricyclodecane(poly)ol and their derivatives and other resins or compounds containing alicyclic structures. Substrates used as resists for g-line, i-line, KrF excimer laser (248 nm), ArF excimer laser (193 nm), extreme ultraviolet (EUV) lithography (13.5 nm), and electron beam (EB) lithography are also applicable. Examples include phenol novolac resins, cresol novolac resins, hydroxystyrene resins, (meth)acrylic resins, hydroxystyrene-(meth)acrylic copolymers, cycloolefin-maleic anhydride copolymers, cycloolefins, vinyl ether-maleic anhydride copolymers, and inorganic resist materials having metallic elements such as titanium, tin, hafnium, and zirconium, as well as derivatives thereof. Derivatives are not particularly limited, but examples include derivatives with introduced dissociable groups and derivatives with introduced crosslinkable groups. Furthermore, the spin-on carbon film forming composition of this embodiment may contain known additives. The above known additives are not limited to the following, but examples include ultraviolet absorbers, surfactants, colorants, nonionic surfactants, etc.

[0082] The spin-on carbon film formation composition of this embodiment is particularly preferably to include, in addition to (i) below, at least one selected from the group consisting of (ii) to (iv) below, from the viewpoint of further improving storage stability, thin film formation ability, etching resistance, embedding ability, and flatness, and to impart a better resist pattern shape: (i) At least one dendritic polymer selected from the group consisting of a dendritic polymer containing a phenyl group, a biphenyl group and / or a bisphenylene group (wherein "bisphenyl group" is a divalent group having any divalent group between two phenylene groups such as -Ph-C(=O)-Ph-, -Ph-CH2-Ph-, -Ph-C(CH3)2-Ph-) in the molecule, a dendritic polymer containing an aromatic ring which may have a heteroatom in the molecule (e.g., a benzene ring and / or a triazine ring, etc.), and / or a dendritic polymer containing an azomethine bond in the molecule (preferably a chemical structure in which, in formula (1) above, R and R' are each independently phenylene groups having -OH, -OC(=O)-CH3 or -O-CH2-O-CH3 as substitutions); (ii) an acid generator selected from the group consisting of triphenylsulfonium nonafluorobutanesulfonate (e.g., available under the trade name "TPS-109"), ditertically butyldiphenyliodonium nonafluorobutanesulfonate (DTDPI), and pyridinium p-toluenesulfonic acid (PPTS); (iii) A crosslinking agent selected from the group consisting of a compound represented by formula (a) (for example, available under the trade name "Nicalac MW-100LM", etc.), a compound represented by formula (b) (for example, available under the trade name "Nicalac MX270", etc.), and a methylol group-containing phenol compound represented by formula (11-2); (iv) A solvent selected from the group consisting of cyclohexanone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, methyl hydroxyisobutyrate, and anisole, preferably a solvent selected from the group consisting of cyclohexanone, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.

[0083] <Method for producing a spin-on carbon film forming composition> The method for producing the spin-on carbon film-forming composition of this embodiment is not particularly limited and can be produced as appropriate by mixing each component. In this embodiment, from the viewpoint of further improving etching resistance, it is preferable to produce the spin-on carbon film-forming composition by the following method. That is, the method for producing the spin-on carbon film-forming composition of this embodiment preferably includes an extraction step of contacting a solution containing the dendritic polymer and an organic solvent that is not arbitrarily miscible with water with an acidic aqueous solution for extraction. The purification method of this embodiment specifically includes the steps of dissolving a dendritic polymer in water and an organic solvent that is arbitrarily immiscible to obtain an organic phase, bringing the organic phase into contact with an acidic aqueous solution to perform an extraction treatment (first extraction step), thereby transferring the metal components contained in the organic phase containing the dendritic polymer and organic solvent to the aqueous phase, and then separating the organic phase and the aqueous phase. This step can significantly reduce the content of various metals that may be encompassed with the dendritic polymer.

[0084] In addition to the above, the method for producing the spin-on carbon film-forming composition of this embodiment preferably includes a step of passing a solution obtained by dissolving the dendritic polymer in a solvent through a filter. Furthermore, the method for producing the spin-on carbon film-forming composition of this embodiment preferably includes a step of contacting a solution obtained by dissolving the dendritic polymer in a solvent with an ion exchange resin. These manufacturing methods can also significantly reduce the content of various metals that may be entrained in the dendritic polymer. In this embodiment, "liquid passage" means that the solution moves from outside the filter, through the inside of the filter, and back to outside the filter. For example, simply bringing the solution into contact with the surface of the filter, or moving the solution outside the ion exchange resin while it is in contact with the surface (i.e., simply making contact), are excluded.

[0085] <Method for forming a lithography underlayer film> The method for forming a lithography underlayer film (manufacturing method) of this embodiment includes the step of forming an underlayer film on a substrate using the spin-on carbon film formation composition of this embodiment.

[0086] [Method for forming resist patterns using a spin-on carbon film formation composition] The resist pattern formation method using the spin-on carbon film formation composition of this embodiment includes the steps of forming a base layer on a substrate using the spin-on carbon film formation composition of this embodiment (A-1), and forming at least one photoresist layer on the base layer (A-2). The resist pattern formation method may also include the step of irradiating a predetermined area of ​​the photoresist layer with radiation and developing it to form a resist pattern (A-3).

[0087] [Method for forming circuit patterns using a spin-on carbon film formation composition] The circuit pattern formation method using the spin-on carbon film formation composition of this embodiment comprises the steps of: forming a lower layer film on a substrate using the spin-on carbon film formation composition of this embodiment (B-1); forming an intermediate layer film on the lower layer film using a resist intermediate layer film material containing silicon atoms (B-2); forming at least one photoresist layer on the intermediate layer film (B-3); irradiating a predetermined area of ​​the photoresist layer with radiation after step (B-3) to develop and form a resist pattern (B-4); etching the intermediate layer film using the resist pattern as a mask after step (B-4) to form an intermediate layer film pattern (B-5); etching the lower layer film using the obtained intermediate layer film pattern as an etching mask to form a lower layer film pattern (B-6); and etching the substrate using the obtained lower layer film pattern as an etching mask to form a pattern on the substrate (B-7).

[0088] The lithography underlayer film of this embodiment is formed from the spin-on carbon film forming composition of this embodiment, but the method of formation is not particularly limited, and known methods can be applied. For example, the spin-on carbon film forming composition of this embodiment can be applied to a substrate by known coating or printing methods such as spin coating or screen printing, and then the underlayer film can be formed by removing it by volatilizing the organic solvent.

[0089] When forming the lower layer film, it is preferable to bake it in order to suppress the mixing phenomenon with the upper layer resist and to promote the crosslinking reaction. In this case, the bake temperature is not particularly limited, but is preferably in the range of 80 to 450°C, and more preferably in the range of 200 to 400°C. The bake time is also not particularly limited, but is preferably in the range of 10 to 300 seconds. The thickness of the lower layer film can be appropriately selected according to the required performance and is not particularly limited, but is usually preferably around 30 to 20,000 nm, and more preferably 50 to 15,000 nm.

[0090] After fabricating the lower layer film, in the case of a two-layer process, it is preferable to fabricate a silicon-containing resist layer or a single-layer resist containing ordinary hydrocarbons on top of it, and in the case of a three-layer process, it is preferable to fabricate a silicon-containing intermediate layer on top of it, and a silicon-free single-layer resist layer on top of that. In this case, known photoresist materials can be used to form these resist layers.

[0091] After fabricating a base layer on a substrate, in the case of a two-layer process, a silicon-containing resist layer or a single-layer resist containing ordinary hydrocarbons can be fabricated on the base layer. In the case of a three-layer process, a silicon-containing intermediate layer can be fabricated on the base layer, and a silicon-free single-layer resist layer can be fabricated on the silicon-containing intermediate layer. In these cases, the photoresist material for forming the resist layer can be appropriately selected from known materials and is not particularly limited.

[0092] For silicon-containing resist materials used in two-layer processes, a positive-type photoresist material is preferably used, from the viewpoint of oxygen gas etching resistance, in which a silicon atom-containing polymer such as a polysilsesquioxane derivative or vinylsilane derivative is used as the base polymer, and further containing an organic solvent, an acid generator, and optionally a basic compound. Here, known polymers used in this type of resist material can be used as the silicon atom-containing polymer.

[0093] For a three-layer process, a polysilsesquioxane-based intermediate layer is preferably used as the silicon-containing intermediate layer. By giving the intermediate layer an anti-reflective effect, reflection tends to be effectively suppressed. For example, in a 193nm exposure process, if a material containing many aromatic groups and having high substrate etching resistance is used as the lower layer, the k value tends to increase and substrate reflection tends to increase. However, by suppressing reflection with the intermediate layer, substrate reflection can be reduced to 0.5% or less. While not limited to the following, polysilsesquioxane that can be crosslinked with acid or heat and into which phenyl groups or light-absorbing groups having silicon-silicon bonds are introduced is preferably used for 193nm exposure.

[0094] Furthermore, an intermediate layer formed by the Chemical Vapor Deposition (CVD) method can also be used. While not limited to the following, a highly effective intermediate layer as an anti-reflective coating produced by the CVD method is known, for example, a SiON film. Generally, forming the intermediate layer by wet processes such as spin coating or screen printing is simpler and more cost-effective than the CVD method. In the three-layer process, the top resist can be either positive or negative, and the same type of single-layer resist commonly used can be used.

[0095] Furthermore, the underlayer film in this embodiment can also be used as an anti-reflective film for ordinary single-layer resists or as a base material for suppressing pattern deformation. Since the underlayer film in this embodiment has excellent etching resistance for base processing, it can also be expected to function as a hard mask for base processing.

[0096] When forming a resist layer using the above-mentioned photoresist material, a wet process such as spin coating or screen printing is preferably used, similar to the process used to form the underlying film. After applying the resist material by spin coating or the like, pre-baking is usually performed, preferably at 80-180°C for 10-300 seconds. Subsequently, exposure is performed according to a conventional method, followed by post-exposure baking (PEB) and development to obtain the resist pattern. The thickness of the resist film is not particularly limited, but is generally preferred to be 30-500 nm, and more preferably 50-400 nm.

[0097] Furthermore, the exposure light should be appropriately selected depending on the photoresist material being used. Generally, high-energy rays with wavelengths of 300 nm or less can be used, specifically excimer lasers at 248 nm, 193 nm, and 157 nm, soft X-rays, electron beams, and X-rays at 3 to 20 nm.

[0098] The resist pattern formed by the above method has pattern distortion suppressed by the underlayer film in this embodiment. Therefore, by using the underlayer film in this embodiment, a finer pattern can be obtained, and the amount of exposure required to obtain that resist pattern can be reduced.

[0099] Next, etching is performed using the obtained resist pattern as a mask. In a two-layer process, gas etching is preferably used for etching the lower layer film. As for gas etching, etching using oxygen gas is preferred. In addition to oxygen gas, inert gases such as He and Ar, or CO, CO2, NH3, SO2, N2, NO 2、 It is also possible to add H2 gas. Furthermore, without using oxygen gas, CO, CO2, NH3, N2, NO 2、 Gas etching can also be performed using only H2 gas. The latter gas is particularly preferred for sidewall protection to prevent undercutting of the pattern sidewalls.

[0100] On the other hand, gas etching is also preferably used for etching the intermediate layer in the three-layer process. The same gas etching methods as those described in the two-layer process above can be applied. In particular, it is preferable to process the intermediate layer in the three-layer process using a fluorocarbon-based gas to mask the resist pattern. Subsequently, as described above, the underlying film can be processed by using the intermediate layer pattern as a mask and performing, for example, oxygen gas etching.

[0101] In this case, when forming an inorganic hard mask intermediate layer, a silicon oxide film, silicon nitride film, or silicon oxynitride film (SiON film) is formed by methods such as CVD or atomic layer deposition (ALD). The method for forming the nitride film is not limited to the following, but for example, the method described in Japanese Patent Application Publication No. 2002-334869 and International Publication No. 2004 / 066377 can be used. A photoresist film can be formed directly on such an intermediate layer, but an organic anti-reflective coating (BARC) may be formed on the intermediate layer by spin coating, and then a photoresist film may be formed on top of that.

[0102] A polysilsesquioxane-based intermediate layer is also preferably used as an intermediate layer. By giving the resist intermediate layer film an anti-reflective effect, reflection tends to be effectively suppressed. The specific material of the polysilsesquioxane-based intermediate layer is not limited to the following, but for example, those described in Japanese Patent Publication No. 2007-226170 and Japanese Patent Publication No. 2007-226204 can be used.

[0103] Furthermore, etching of the substrate can also be performed by conventional methods. For example, if the substrate is SiO2 or SiN, etching can be performed mainly with fluorocarbon gases, while etching can be performed mainly with chlorine-based or bromine-based gases for p-Si, Al, or W. When etching the substrate with fluorocarbon gases, the silicon-containing resist in a two-layer resist process and the silicon-containing intermediate layer in a three-layer resist process are stripped simultaneously with the substrate processing. On the other hand, when etching the substrate with chlorine-based or bromine-based gases, the silicon-containing resist layer or silicon-containing intermediate layer is stripped separately, and generally, dry etching stripping with fluorocarbon gas is performed after the substrate processing.

[0104] The underlying film in this embodiment is characterized by excellent etching resistance of these substrates. The substrate can be appropriately selected from known materials and is not particularly limited, but examples include Si, α-Si, p-Si, SiO2, SiN, SiON, W, TiN, Al, etc. The substrate may also be a laminate having a film to be processed (substrate to be processed) on a base material (support). Examples of such films to be processed include various low-k films and stopper films thereon, such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, Al-Si, etc., and are usually made of a different material from the base material (support). The thickness of the substrate to be processed or the film to be processed is not particularly limited, but is usually preferably around 50 to 1,000,000 nm, and more preferably 75 to 500,000 nm.

[0105] <Underlayer film for lithography> The lithography underlayer film of this embodiment is obtained by spin-coating a composition for forming a spin-on carbon film that contains a solvent, as described in this embodiment. From the viewpoint of etching resistance, the lithography underlayer film of this embodiment preferably has an etching rate of 60 nm / min or less, as measured by the following method. <Measurement of etching rate> The lithography underlayer film is subjected to the following etching test to measure the etching rate. (Etching test) Output: 100W Pressure: 8 Pa Etching gas: CF4 gas (flow rate 20 (sccm)) The etching rate described above can be adjusted to the above range by using the spin-on carbon film forming composition containing the dendritic polymer and solvent in this embodiment. In particular, the etching rate tends to be lower by appropriately selecting the raw materials for the dendritic polymer so that the dendritic polymer in this embodiment has the preferred chemical structure described above, controlling the molecular weight to the preferred range described above, and appropriately adjusting conditions such as the use of acid generators and crosslinking agents, and the heating temperature during film formation. [Examples]

[0106] The embodiment will be described in more detail below with reference to examples, but this embodiment is not limited to these examples.

[0107] [Molecular weight] The molecular weight of the compound was determined by liquid chromatography-mass spectrometry (LC-MS) using a Water Acquity UPLC / MALDI-Synapt HDMS. Furthermore, gel permeation chromatography (GPC) analysis was performed under the following conditions to determine the weight-average molecular weight (Mw), number-average molecular weight (Mn), and degree of dispersion (Mw / Mn) in polystyrene equivalent. Equipment: Shodex GPC-101 (manufactured by Showa Denko Corporation) Columns: KF-80M x 3 Eluent: THF 1mL / min Temperature: 40℃

[0108] [Structure of the compound] The compound structure was determined using a Bruker Advance600II spectrometer under the following conditions: 1 This was confirmed by performing 1H-NMR measurements. Frequency: 400MHz Solvent: d6-DMSO Internal standard: TMS Measurement temperature: 23℃

[0109] [Thermogravimetric decrease start temperature] The thermogravimetric onset temperature of the compound was determined using the EXSTAR6000TG-DTA instrument manufactured by SII Nanotechnology. Approximately 5 mg of the sample was placed in an unsealed aluminum container and heated to 500°C at a heating rate of 10°C / min in a nitrogen gas (300 mL / min) stream. The point at which a decrease appeared on the baseline was defined as the thermal decomposition temperature.

[0110] (Reference Example 1) Synthesis of BisP-1 In a 500 mL container equipped with a stirrer, condenser, and burette, 34.0 g (200 mmol) of o-phenylphenol (Sigma-Aldrich reagent), 18.2 g (100 mmol) of 4-biphenylaldehyde (Mitsubishi Gas Chemical Co., Ltd.), and 200 mL of 1,4-dioxane were charged. 10 mL of 95% sulfuric acid was added, and the mixture was stirred at 100°C for 6 hours to carry out the reaction. Next, the reaction mixture was neutralized with a 24% sodium hydroxide aqueous solution, 100 g of pure water was added to precipitate the reaction product, and after cooling to room temperature, the product was separated by filtration. After drying the obtained solid, separation and purification by column chromatography yielded 25.5 g of the compound BisP-1, represented by the following formula (BisP-1). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming that the chemical structure is represented by the following formula (BisP-1). δ(ppm)9.1(2H,OH), 7.2~8.5(25H,Ph-H), 5.6(1H,CH) Furthermore, the LC-MS analysis described above confirmed that the molecular weight is 504, corresponding to the chemical structure shown in the following formula (BisP-1).

[0111] [ka]

[0112] <Synthesis Example 1> Synthesis of Compound D1 Except for using the above formula (BiP-1) instead of the calix[4]resorcinarene represented by formula (16) in Example 1 of Japanese Patent Publication No. 10-310545 (hereinafter also referred to as "Cited Example a"), the same procedure as in Cited Example a was carried out to obtain 1.2 g of compound D1 represented by the following formula (D1). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming that the chemical structure is represented by the following formula (D1). δ(ppm)(d6-DMSO): 9.1(8H,OH), 7.2~8.5(43H,Ph-H), 5.6(1H,CH), 5.2(12H,-CH2-) Furthermore, the LC-MS analysis described above confirmed that the molecular weight is 1236, corresponding to the chemical structure shown in formula (D1) below. Based on the above evaluation, it was confirmed that compound D1 is a dendritic polymer. Furthermore, based on the above evaluation, the carbon content was determined to be 76.7%, the oxygen content 18.1%, and the Si and F content 0%. The temperature at which thermogravimetric reduction began was between 300°C and 400°C. [ka]

[0113] <Synthesis Example 2> Synthesis of Compound D2 The reaction was carried out in the same manner as in Synthesis Example 1 of International Publication No. 2012 / 060286. Subsequently, the reaction mixture was concentrated and purified by column chromatography to obtain compound D2' represented by the following formula (D2'). Next, 8.6 g (40 mmol) of 4,4'-dihydroxybenzophenone (MW214), 4.0 g (10 mmol) of D2' (Mw399) obtained above, 11.2 g (100 mmol) of 1,4-diazabicyclo[2.2.2]octane (MW112), and 100 mL of chlorobenzene were added to the reactor. The mixture was heated to 90°C and stirred, and then 22.8 g (120 mmol) of titanium chloride (MW190) was added dropwise over 30 minutes. Subsequently, the temperature was raised to 125°C and stirring was continued for 24 hours. After that, the reaction mixture was concentrated and purified by column chromatography to obtain 0.5 g of the compound represented by the following formula (D2). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming that the chemical structure is represented by the following formula (D2). δ(ppm)(d6-DMSO): 9.8(6H,OH), 9.4(3H,NH), 6.6~7.8(36H,Ph-H) Furthermore, the LC-MS analysis described above confirmed that the molecular weight is 987, corresponding to the chemical structure shown in formula (D2) below. Based on the above evaluation, it was confirmed that compound D2 is a dendritic polymer. Furthermore, based on the above evaluation, the carbon content was determined to be 72.9%, the oxygen content 9.7%, and the Si and F content 0%. The temperature at which thermogravimetric reduction began was above 400°C. [ka] [ka]

[0114] <Synthesis Example 3> Synthesis of Compound D3 8.6 g (40 mmol) of 4,4'-dihydroxybenzophenone (MW214), 2.1 g (10 mmol) of 3,3'-diaminobenzidine (MW214), 11.2 g (100 mmol) of 1,4-diazabicyclo[2.2.2]octane (MW112), and 100 mL of chlorobenzene were added to the reactor. The mixture was heated to 90°C and stirred, and then 22.8 g (120 mmol) of titanium chloride (MW190) was added dropwise over 30 minutes. Subsequently, the temperature was raised to 125°C and stirring was continued for 24 hours. The reaction mixture was then concentrated and purified by column chromatography to obtain 2.5 g of compound D3, represented by the following formula (D3). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming that the chemical structure is represented by the following formula (D3). δ (ppm) (d6-DMSO): 9.9 (8H, OH), 6.8~7.8 (38H, Ph) Furthermore, the LC-MS analysis described above confirmed that the molecular weight is 998, corresponding to the chemical structure shown in formula (D3) below. Based on the above evaluation, it was confirmed that compound D3 is a dendritic polymer. Furthermore, based on the above evaluation, the carbon content was determined to be 76.9%, the oxygen content 12.8%, and the Si and F content 0%. The temperature at which thermogravimetric reduction began was above 400°C. [ka]

[0115] <Synthesis Example 4> Synthesis of Compound D4 8.6 g (40 mmol) of 4,4'-dihydroxybenzophenone (MW214), 2.2 g (10 mmol) of 4,4'-diaminobenzophenone (MW212), 11.2 g (100 mmol) of 1,4-diazabicyclo[2.2.2]octane (MW112), and 100 mL of chlorobenzene were added to the reactor. The mixture was heated to 90°C and stirred, and then 22.8 g (120 mmol) of titanium chloride (MW190) was added dropwise over 30 minutes. Subsequently, the temperature was raised to 125°C and stirring was continued for 24 hours. The reaction mixture was then concentrated and purified by column chromatography to obtain 1.0 g of compound D4, represented by the following formula (D4). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming that the chemical structure is represented by the following formula (D4). δ (ppm) (d6-DMSO): 9.9 (1H, OH), 6.8~7.8 (13H, Ph) Furthermore, the above GPC analysis confirmed that Mw=3,828, Mn=1,823, and Mw / Mn=2.1. Based on the above evaluation, it was confirmed that compound D4 is a dendritic polymer. Furthermore, based on the above evaluation, the carbon content was determined to be 70% or more, the oxygen content to be less than 20%, and the Si and F content to be 0%. The temperature at which thermogravimetric reduction began was above 400°C. [ka] (In the formula, n is an integer between 0 and 3.)

[0116] <Synthesis Example 5> Synthesis of Compound D5 8.6 g (40 mmol) of 4,4'-diaminobenzophenone (MW 212), 2.1 g (10 mmol) of 3,3'-diaminobenzidine (MW 214), 11.2 g (100 mmol) of 1,4-diazabicyclo[2.2.2]octane (MW 112), and 100 mL of chlorobenzene were added to a reactor, heated to 90 °C, and stirred. Then, 22.8 g (120 mmol) of titanium chloride (MW 190) was added dropwise over 30 minutes. Subsequently, 17.2 g (80 mmol) of 4,4'-dihydroxybenzophenone (MW 214) was added, the temperature was raised to 125 °C, and stirring was continued for 24 hours. Thereafter, the reaction solution was concentrated and purified by column chromatography to obtain 0.8 g of Compound D5 represented by the following formula (D5). The obtained compound was subjected to the above 1 As a result of performing 1H-NMR measurement, the following peaks were found, and it was confirmed that it has the chemical structure of the following formula (D5). δ (ppm) (d6-DMSO): 9.9 (8H, OH), 6.8 - 7.8 (57H, Ph) Also, by the above GPC analysis, it was confirmed that Mw = 2,880, Mn = 1,440, and Mw / Mn = 2.0. From the above evaluations, it was confirmed that Compound D5 is a dendritic polymer. Also, based on the above evaluations, it was evaluated that the carbon content is 70% or more, the oxygen content is less than 20%, and the Si content and the F content are 0%. The starting temperature of thermal weight loss was over 400 °C. [Chemical formula] (In the formula, n is an integer from 0 to 3, and D5 is a mixture of n = 0 to 3.)

[0117] [Synthesis Example 6] Synthesis of Compound D6 Compound D3 (22 g, 0.022 mol) from Synthesis Example 3, 27 g (0.26 mol) of triethylamine, and 80 mL of tetrahydrofuran were charged into a reactor. 16 g (0.16 mol) of acetic anhydride was then added, and the reaction was carried out by stirring the mixture at 60°C for 5 hours. Next, 130 mL of 10% H2SO4 aqueous solution and 80 mL of ethyl acetate were added to the container, and the aqueous layer was removed by liquid-liquid separation. The reaction mixture was then concentrated and purified by column chromatography to obtain 21 g of compound D6, represented by the following formula (D6). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming that the chemical structure is represented by the following formula (D6). δ(ppm)(d6-DMSO):6.8~7.8(38H, Ph), 2.2(24H, -CH3) Furthermore, the LC-MS analysis described above confirmed that the molecular weight is 1334, corresponding to the chemical structure shown in formula (D6) below. Based on the above evaluation, it was confirmed that compound D6 is a dendritic polymer. Furthermore, based on the above evaluation, the carbon content was determined to be 72.0%, the oxygen content 19.2%, and the Si and F content 0%. The temperature at which thermogravimetric reduction began was above 400°C. [ka]

[0118] <Synthesis Example 7> Synthesis of Compound D7 Compound D3 (22 g, 0.022 mol) from Synthesis Example 3, 27 g (0.26 mol) of triethylamine, and 80 mL of tetrahydrofuran were charged into a reactor. 8 g (0.08 mol) of acetic anhydride was then added, and the reaction was carried out by stirring the mixture at 60°C for 5 hours. Next, 130 mL of 10% H2SO4 aqueous solution and 80 mL of ethyl acetate were added to the container, and the aqueous layer was removed by liquid-liquid separation. The reaction mixture was then concentrated and purified by column chromatography to obtain 19 g of compound D7, represented by the following formula (D7). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming the presence of a chemical structure. δ(ppm)(d6-DMSO): 9.9(4H, OH), 6.8~7.8(38H, Ph), 2.2(12H, -CH3) Based on the above evaluation, it was confirmed that compound D7 is a dendritic polymer. Furthermore, based on the above evaluation, the carbon content was determined to be 74.5%, the oxygen content 16.0%, and the Si and F content 0%. The temperature at which thermogravimetric reduction began was above 400°C. [ka] (D7 is a mixture of R=H and R=-CH2OCH3, as described above) 1 The protection rate was estimated to be approximately 50 mol% based on the integration ratio obtained from 1H-NMR measurements. This protection rate is consistent with the identification results for compound D6 and the relationship with the amount of acetic anhydride used.

[0119] <Synthesis Example 8> Synthesis of Compound D8 Compound D3 (22 g, 0.022 mol) from Synthesis Example 3, 27 g (0.26 mol) of triethylamine, and 80 mL of tetrahydrofuran were charged into a reactor. 16 g (0.16 mol) of methoxymethoxychloride was then added, and the reaction was carried out by stirring the mixture at 60°C for 5 hours. Next, 130 mL of 10% H2SO4 aqueous solution and 80 mL of ethyl acetate were added to the container, and the aqueous layer was removed by liquid-liquid separation. The reaction mixture was then concentrated and purified by column chromatography to obtain 20 g of compound D8, represented by the following formula (D8). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming the presence of a chemical structure. δ(ppm)(d6-DMSO):6.8~7.8(38H, Ph), 6.0(16H, -CH2-), 3.3(24H, -CH3) Furthermore, the LC-MS analysis described above confirmed that the molecular weight is 1351, corresponding to the chemical structure shown in formula (D8) below. Based on the above evaluation, it was confirmed that compound D8 is a dendritic polymer. Furthermore, based on the above evaluation, the carbon content was determined to be 71.3%, the oxygen content 17.7%, and the Si and F content 0%. The temperature at which thermogravimetric reduction began was above 400°C. [ka]

[0120] <Synthesis Example 9> Synthesis of Compound D9 Compound D3 (22 g, 0.022 mol) from Synthesis Example 3, 27 g (0.26 mol) of triethylamine, and 80 mL of tetrahydrofuran were charged into a reactor. 8 g (0.08 mol) of methoxymethoxychloride was then added, and the reaction was carried out by stirring the mixture at 60°C for 5 hours. Next, 130 mL of 10% H2SO4 aqueous solution and 80 mL of ethyl acetate were added to the container, and the aqueous layer was removed by liquid-liquid separation. The reaction mixture was then concentrated and purified by column chromatography to obtain 18 g of compound D9, represented by the following formula (D9). The obtained compound is described above 1 ¹H-NMR measurements revealed the following peaks, confirming the presence of a chemical structure. δ(ppm)(d6-DMSO): 9.9(4H, OH), 6.8~7.8(38H, Ph), 6.0(8H, -CH2-), 3.3(12H, -CH3) Based on the above evaluation, it was confirmed that compound D9 is a dendritic polymer. Furthermore, based on the above evaluation, the carbon content was determined to be 74.1%, the oxygen content 15.3%, and the Si and F content 0%. The temperature at which thermogravimetric reduction began was above 400°C. [ka] (D9 is a mixture of R=H and R=-CH2OCH3, as described above) 1 The protection rate was estimated to be approximately 50 mol% based on the integration ratio obtained from 1H-NMR measurements.

[0121] <Synthesis Comparison Example 1> Synthesis of AC-1 4.15 g of 2-methyl-2-methacryloyloxyadamantane, 3.00 g of methacryloyloxy-γ-butyrolactone, 2.08 g of 3-hydroxy-1-adamantyl methacrylate, and 0.38 g of azobisisobutyronitrile were dissolved in 80 mL of tetrahydrofuran to prepare the reaction solution. This reaction solution was polymerized under a nitrogen atmosphere at a reaction temperature of 63°C for 22 hours, after which the reaction solution was added dropwise to 400 mL of n-hexane. The resulting resin was coagulated and purified, and the resulting white powder was filtered and dried overnight under reduced pressure at 40°C to obtain compound AC-1, represented by the following formula. Compound AC-1 was evaluated as not being a dendritic polymer because it has 2 terminal groups and 0 branching degrees. The temperature at which thermogravimetric reduction began was below 300°C.

[0122] [ka] (In formula AC-1, "40", "40", and "20" represent the ratios of each constituent unit and do not represent the block copolymer.)

[0123] (Evaluation 1) Solubility test of the compound in semiconductor coating solvent The solubility of the compound in PGME, PGMEA, and CHN was evaluated using the amount of solubility in each solvent according to the following criteria. The amount of solubility was measured at 23°C by accurately weighing the compound into a test tube, adding the target solvent to the specified concentration, applying ultrasonic waves in an ultrasonic cleaner for 30 minutes, and then visually observing the state of the liquid. For a solubility of 0.5% by mass, the solvent was added to 0.05g of solute to a total of 10.00g as a guideline, and this was adjusted in each example. A: 0.5 mass% ≦ dissolved amount C: Dissolved amount <0.5% by mass

[0124] <Examples 1-1 to 9-1, Comparative Example 1-1> Table 1 shows the results of evaluating the solubility of the compounds obtained in Synthesis Examples 1-5 and Synthesis Comparative Example 1 in semiconductor coating solvents using the method described above.

[0125] [Table 1]

[0126] <Examples 1-2-1 to 9-2-2, and Comparative Example 1-2> Compositions for forming spin-on carbon films were prepared according to the compositions shown in Table 2 below. Next, these spin-on carbon film-forming compositions were rotationally coated onto a silicon substrate, and then baked at 110°C for 90 seconds to produce films with a thickness of 50 nm. The following acid generators, crosslinking agents, and organic solvents were used. Acid generator: Triphenylsulfonium nonafluorobutanesulfonate (TPS-109), manufactured by Midori Chemical Co., Ltd. Midori Chemical Co., Ltd. Ditase-butyldiphenyliodonium nonafluorobutanesulfonate (DTDPI) Pyridinium-p-toluenesulfonic acid manufactured by Kanto Chemical Co., Ltd. (indicated as "PPTS" in the table) Crosslinking agent: Sanwa Chemical Nikalac MW-100LM Sanwa Chemical Nikalac MX270 TMOM-BP manufactured by Honshu Chemical Industry Co., Ltd. Organic solvents: Propylene glycol monomethyl ether (PGME) manufactured by Kanto Chemical Co., Ltd. Propylene glycol monomethyl ether acetate (PGMEA) manufactured by Kanto Chemical Co., Ltd. Cyclohexanone (CHN) manufactured by Kanto Chemical Co., Ltd.

[0127] Next, each was evaluated using the method described below. The evaluation results are shown in Table 2.

[0128] (Evaluation 2) Storage stability and thin film formation of the spin-on carbon film formation composition After preparing the spin-on carbon film formation composition, it was left to stand at 23°C for 3 days, and the presence or absence of precipitation was evaluated by visual observation. Furthermore, the spin-on carbon film formation composition and the film formed using it as described above were evaluated as follows: "A" if it was a homogeneous solution and thin film formation was good, "B" if it was a homogeneous solution but the thin film had defects, and "C" if precipitation occurred.

[0129] (Evaluation 3) Etching resistance The film obtained in Evaluation 2 above was subjected to an etching test under the following conditions, and the etching rate was measured. Etching equipment: RIE-10NR manufactured by Samco International Corporation Output: 100W Pressure: 8 Pa Etching gas: CF4 gas (flow rate 20 (sccm)) (Evaluation Criteria) A: Etching rate less than 40 nm / min B: Etching rate between 40 nm / min and less than 60 nm / min C: Etching rate of 60 nm / min or higher

[0130] (Evaluation 4) Implantability A spin-on carbon film formation composition was applied to a 60 nm line-and-space SiO2 substrate and baked at 400°C for 60 seconds to form a film of approximately 100 nm thickness. A cross-section of the obtained film was cut and observed using an electron microscope (Hitachi High-Technologies Corporation's "S-4800"), and the embedding ability of the lithography underlayer film formation composition into stepped substrates was evaluated according to the following evaluation criteria. The results are shown in Table 2. <Evaluation Criteria> The underlying film was embedded without defects in the uneven areas of the S:SiO2 substrate (zero defects within a 1μm × 1.5μm area). A: The underlying film was embedded in the uneven areas of the SiO2 substrate with virtually no defects (1-2 defects within a 1μm x 1.5μm area). C: There were defects in the concavo-convex portions of the SiO2 substrate (the number of defects was 3 or more within a range of 1 μm × 1.5 μm), and the lower layer film was not embedded.

[0131] (Evaluation 5) Planarity The spin-on carbon film-forming composition was applied respectively on a SiO2 step substrate having trenches with a width of 60 nm, a pitch of 60 nm, and a depth of 200 nm. Then, it was baked at 400 °C for 60 seconds in an air atmosphere to form a lower layer film with a film thickness of 100 nm. The shape of this lower layer film was observed with a scanning electron microscope ("S-4800" of Hitachi High-Technologies Corporation), and the difference (ΔFT) between the minimum film thickness in the trench and the maximum film thickness in the portion without trenches was calculated, and the planarity was evaluated according to the following evaluation criteria. The results are shown in Table 2. <Evaluation Criteria> S: ΔFT < 20 nm (Excellent flatness) A: 20 nm ≤ ΔFT < 30 nm (Good flatness) C: 30 nm ≤ ΔFT (Poor flatness)

[0132]

Table 2

[0133] <Examples 1-3-1 to 9-3-2, Comparative Example 2> <Synthesis of MAR1> 0.5 g of compound AR1 (represented by the formula (AR1) below), 3.0 g of 2-methyl-2-adamantyl methacrylate, 2.0 g of γ-butyrolactone methacrylate, and 1.5 g of hydroxyadamantyl methacrylate were dissolved in 45 mL of tetrahydrofuran, and 0.20 g of azobisisobutyronitrile was added. After refluxing for 12 hours, the reaction solution was added dropwise to 2 L of n-heptane. The precipitated polymer was filtered off and dried under reduced pressure to obtain polymer MAR1, represented by the formula (MAR1) below, as a white powder. The weight-average molecular weight (Mw) of this polymer was 12,000, and the degree of dispersion (Mw / Mn) was 1.90. Furthermore, 13C-NMR measurements showed that the composition ratio (molar ratio) in the formula (MAR1) below was a:b:c:d = 40:30:15:15. Note that the following formula (MAR1) is a simplified representation to show the ratio of each constituent unit, but the order of the constituent units is random, and it is not a block copolymer where each constituent unit forms an independent block. For polystyrene monomers (compound AR1), the molar ratio was determined based on the integral ratio of the carbon at the base of the benzene ring, and for methacrylate monomers (2-methyl-2-adamantyl methacrylate, γ-butyrolactone methacrylate, and hydroxyadamantyl methacrylate), it was determined based on the integral ratio of the carbonyl carbon of the ester bond.

[0134] [ka]

[0135] [ka]

[0136] <Examples 1-3-1 to 9-3-2, and Comparative Example 2> (Preparation of the underlying film-forming solution) Compositions for forming spin-on carbon films were prepared according to the compositions shown in Table 3 below.

[0137] [evaluation] The spin-on carbon film-forming compositions prepared in each of the above-described Examples 1-2-1 to 9-2-2 were rotationally coated onto a SiO2 substrate with a thickness of 300 nm, and baked at 150°C for 60 seconds, and then at 400°C for 120 seconds, to form a 70 nm thick underlayer film. An ArF resist solution was applied to this underlayer film, and a 140 nm thick photoresist layer was formed by baking at 130°C for 60 seconds. The ArF resist solution used was prepared by combining 5 parts by mass of the compound represented by formula (MAR1), 1 part by mass of triphenylsulfonium nonafluorobutanesulfonate, 2 parts by mass of tributylamine, and 92 parts by mass of PGMEA.

[0138] Next, using an electron beam lithography system (ELS-7500, 50 keV, manufactured by Elionix Corporation), the photoresist layers were exposed to light at 45 nm / S (1:1), 50 nm / S (1:1), 55 nm / S (1:1), and 80 nm / S (1:1), baked (PEB) at 115°C for 90 seconds, and developed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution for 60 seconds to obtain positive-type resist patterns.

[0139] Table 3 shows the results of observing defects in the obtained 55 nmL / S (1:1) and 80 nmL / S (1:1) resist patterns. In the table, "Good" indicates that no major defects were observed in the resist patterns formed at the 55 nmL / S (1:1) and 80 nmL / S (1:1) linewidths after development, while "Poor" indicates that major defects were observed in the resist patterns formed at either linewidth. In the table, "Resolution" refers to the minimum linewidth that produces a pattern without distortion and with good rectangularity, and "Sensitivity" refers to the minimum electron beam energy that can produce a good pattern shape.

[0140] (Comparative Example 2) The evaluation was carried out in the same manner as in Example 1-3-1, except that the formation of the underlying film was not performed.

[0141] [Table 3]

[0142] As described above, the spin-on carbon film formation composition of this embodiment is excellent in storage stability, thin film formation ability, etching resistance, embedding ability, and flatness, and can impart a good resist pattern shape. Therefore, when these are used in compositions for photolithography film formation or underlayer film formation, it is possible to form films with high resolution and high sensitivity, and to create good resist patterns. These can be widely and effectively used in various applications where these performance characteristics are required. [Industrial applicability]

[0143] The spin-on carbon film formation composition of the present invention has industrial applicability as a composition material for photolithography film formation and underlayer film formation applications.

Claims

1. A composition for forming a spin-on carbon film as an underlayer for lithography, Contains dendritic polymers, A spin-on carbon film forming composition wherein the dendritic polymer has a chemical structure represented by the following formula (1) in its molecule. R(R')C=N-(1) (In formula (1) above, R and R' each independently represent an arylene group which may have substituents.)

2. The spin-on carbon film forming composition according to claim 1, wherein the dendritic polymer has ester bonds, ketone bonds, amide bonds, imide bonds, urea bonds, urethane bonds, ether bonds, thioether bonds, imino bonds and / or azomethine bonds in its molecule.

3. The spin-on carbon film forming composition according to claim 1, wherein the thermogravimetric polymer has a temperature of 300°C or higher at which the thermal weight loss begins.

4. The spin-on carbon film forming composition according to claim 1, wherein the solubility of the dendritic polymer in a semiconductor coating solvent is 0.5% by mass or more.

5. The spin-on carbon film forming composition according to claim 1, wherein the carbon content of the dendritic polymer is 70% or more, and / or the oxygen content of the dendritic polymer is less than 20%.

6. The spin-on carbon film forming composition according to claim 1, further comprising a solvent.

7. The spin-on carbon film forming composition according to claim 6, further comprising at least one selected from the group consisting of an acid generator and a crosslinking agent.

8. A lithography underlayer film comprising the spin-on carbon film forming composition according to claim 6 or 7, wherein the etching rate measured by the following method is 60 nm / min or less. <Measurement of etching rate> The lithography underlayer film is subjected to the following etching test to measure the etching rate. (Etching test) Output: 100W Pressure: 8 Pa Etching gas: CF 4 Gas (flow rate 20 (sccm))

9. A base layer formation step of forming a base layer on a substrate using the spin-on carbon film formation composition described in any one of claims 1 to 7, A resist pattern formation method comprising: a photoresist layer formation step of forming at least one photoresist layer on a lower layer formed by the lower layer formation step; and a step of irradiating a predetermined region of the photoresist layer formed by the photoresist layer formation step with radiation to perform development.

10. A base layer formation step of forming a base layer on a substrate using the spin-on carbon film formation composition described in any one of claims 1 to 7, An intermediate layer film formation step is performed to form an intermediate layer film on the lower layer film formed by the lower layer film formation step, A photoresist layer formation step, in which at least one photoresist layer is formed on the intermediate layer formed by the intermediate layer formation step, A resist pattern formation step involves irradiating a predetermined area of ​​the photoresist layer formed by the photoresist layer formation step with radiation and developing it to form a resist pattern, An intermediate layer pattern formation step is performed by using the resist pattern formed in the resist pattern formation step as a mask to etch the intermediate layer film and form an intermediate layer pattern, A lower layer pattern formation step is performed by using the intermediate layer pattern formed in the intermediate layer pattern formation step as a mask to etch the lower layer to form a lower layer pattern, A circuit pattern formation method comprising a substrate pattern formation step, which involves etching the substrate using the underlying film pattern formed in the underlying film pattern formation step as a mask to form a pattern on the substrate.

11. A method for producing a spin-on carbon film forming composition according to any one of claims 1 to 7, A manufacturing method comprising an extraction step of contacting a solution containing the dendritic polymer and an organic solvent that is not arbitrarily miscible with water with an acidic aqueous solution for extraction.

12. A method for producing a spin-on carbon film forming composition according to any one of claims 1 to 7, comprising the step of passing a solution obtained by dissolving the dendritic polymer in a solvent through a filter.

13. A method for producing a spin-on carbon film forming composition according to any one of claims 1 to 7, comprising the step of contacting an ion exchange resin with a solution obtained by dissolving the dendritic polymer in a solvent.

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