Method for manufacturing a semiconductor substrate and composition for forming a resist underlayer film.

Abstract

The purpose of the present invention is to provide a method for producing a semiconductor substrate that uses a resist underlayer film forming composition that can form a resist underlayer film with excellent pattern rectangularity and that has exceptional preservation stability, and to provide a resist underlayer film forming composition. The method for producing a semiconductor substrate comprises a step of directly or indirectly applying a resist underlayer film forming composition to a substrate, a step of applying a resist film forming composition to the resist underlayer film formed in the resist underlayer film forming composition application step, a step of exposing the resist film formed in the resist film forming composition application step by radiation, and a step of developing at least the exposed resist film, the resist underlayer film forming composition containing a polymer, an onium salt that generates at least one polar group selected from the group consisting of a carboxyl group and a hydroxyl group by radiation or heat, and a solvent.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing a semiconductor substrate and a composition for forming a resist underlayer film. [Background technology]

[0002] In the manufacturing of semiconductor devices, for example, a multilayer resist process is used to form a resist pattern by exposing and developing a resist film that has been laminated on a substrate via a resist underlayer film such as an organic underlayer film or a silicon-containing film. In this process, the resist pattern is used as a mask to etch the resist underlayer film, and the substrate is further etched using the resulting resist underlayer film pattern as a mask, thereby forming a desired pattern on the semiconductor substrate.

[0003] In recent years, semiconductor devices have become even more highly integrated, and the exposure light used is tending to be shortened from KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm) to extreme ultraviolet light (13.5 nm, hereinafter also referred to as "EUV"). Various studies have been conducted on compositions for forming resist underlayer films in such EUV exposure (see International Publication No. 2013 / 141015). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2013 / 141015 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] As the line width of resist patterns formed by exposure and development under extreme ultraviolet light has been miniaturized to levels of 20 nm or less, the underlying resist film is required to have pattern rectangularity, which suppresses pattern trailing at the bottom of the resist film and ensures the rectangularity of the resist pattern.

[0006] The present invention has been made based on the circumstances described above, and its purpose is to provide a method for manufacturing a semiconductor substrate using a resist underlayer film forming composition that can form a resist underlayer film with good pattern rectangularity and also has excellent storage stability, as well as a resist underlayer film forming composition. [Means for solving the problem]

[0007] In one embodiment, the present invention is A step of coating a resist underlayer film formation composition directly or indirectly onto a substrate, A step of coating the resist film-forming composition onto the resist film-forming composition formed by the above resist film-forming composition coating step, A step of exposing the resist film formed by the above resist film forming composition coating step with radiation, At least the process of developing the exposed resist film and Equipped with, The above resist underlayer film forming composition, Polymers (hereinafter also referred to as "[A] polymers") and An onium salt (hereinafter also referred to as "[B] onium salt") that generates at least one polar group selected from the group consisting of carboxyl groups and hydroxyl groups upon radiation or heat, The solvent (hereinafter also referred to as "[C] solvent") and This invention relates to a method for manufacturing a semiconductor substrate containing [a specific substance].

[0008] In other embodiments, the present invention Polymers and An onium salt that generates at least one polar group selected from the group consisting of carboxyl groups and hydroxyl groups by radiation or heat, solvent and This invention relates to a composition for forming a resist underlayer film, which contains the following: [Effects of the Invention]

[0009] The semiconductor substrate manufacturing method uses a resist underlayer film formation composition that enables the formation of a resist underlayer film with good pattern rectangularity and excellent storage stability, thus enabling the efficient manufacture of semiconductor substrates with good pattern shapes. The resist underlayer film formation composition provides excellent storage stability and enables the formation of a film with good pattern rectangularity. Therefore, these can be suitably used in the manufacture of semiconductor devices, where further miniaturization is expected in the future. [Modes for carrying out the invention]

[0010] The following describes in detail the method for manufacturing semiconductor substrates and the compositions for forming resist underlayer films according to each embodiment of the present invention. Preferred combinations of embodiments are also preferred.

[0011] Method for manufacturing semiconductor substrates The method for manufacturing the semiconductor substrate comprises the steps of: coating the substrate directly or indirectly with a resist underlayer film forming composition (hereinafter also referred to as "coating step (I)"); coating the resist underlayer film formed by the resist underlayer film forming composition coating step with a resist film forming composition (hereinafter also referred to as "coating step (II)"); exposing the resist film formed by the resist film forming composition coating step with radiation (hereinafter also referred to as "exposure step"); and developing at least the exposed resist film (hereinafter also referred to as "development step").

[0012] According to the semiconductor substrate manufacturing method, by using a predetermined resist underlayer film formation composition in the coating step (I), a resist underlayer film with excellent pattern rectangularity can be formed, making it possible to manufacture a semiconductor substrate with a good pattern shape.

[0013] The method for manufacturing the semiconductor substrate may further include, if necessary, a step of forming a silicon-containing film directly or indirectly on the substrate before the coating step (I) (hereinafter also referred to as the "silicon-containing film formation step").

[0014] The following describes the resist underlayer film formation composition used in the semiconductor substrate manufacturing method, and each step when the method includes an optional silicon-containing film formation step.

[0015] <Composition for forming a resist underlayer film> The resist underlayer film forming composition (hereinafter also simply referred to as "the composition") contains [A] a polymer, [B] an onium salt, and [C] a solvent. The composition may contain optional components as long as they do not impair the effects of the present invention. By containing [A] a polymer, [B] an onium salt, and [B] a solvent, the resist underlayer film forming composition can improve the storage stability of the composition and form a resist underlayer film with excellent pattern rectangularity. The reason for this is not clear, but it is presumed to be as follows: Since the resist underlayer film forming composition contains an onium salt (i.e., [B] an onium salt) as an acid generator, the acid generated from the onium salt in the resist underlayer film suppresses oxygen deficiency at the bottom of the resist film in the exposed area, improves solubility in the developer at the bottom of the resist film, and allows for pattern rectangularity to be exhibited. Furthermore, since at least one polar group selected from the group consisting of carboxyl groups and hydroxyl groups present in the [B]onium salt is generated by radiation or heat during exposure or baking, unintended reactions during storage can be suppressed, thereby improving the storage stability of the resist underlayer film forming composition. In addition, the polar groups generated by radiation or heat cause electrostatic or chemical interactions between the [B]onium salt and the [A]polymer, suppressing excessive diffusion of the [B]onium salt into the resist film and enabling the formation of a rectangular pattern.

[0016] <[A] Polymer> [A] As the polymer, known polymers used for forming the resist underlayer film can be suitably used. The composition may contain one or more [A] polymers. Acrylic polymers are preferred as the [A] polymer.

[0017] [A] When the polymer is an acrylic polymer, it is preferable that it has repeating units represented by the following formula (1) (hereinafter also referred to as "repeating unit (1)"). [ka] (In formula (1), R 1 L is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, either substituted or unsubstituted. 1 (This is a single bond or a divalent linking group.)

[0018] R 1 Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms, as represented by , include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof.

[0019] In this specification, "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. This "hydrocarbon group" includes saturated hydrocarbon groups and unsaturated hydrocarbon groups. "Linear hydrocarbon group" means a hydrocarbon group that does not contain a ring structure and consists only of a linear structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only an alicyclic structure as its ring structure and does not contain an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups (however, it is not necessary to consist only of an alicyclic structure, and it may contain a linear structure as part of it). "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure (however, it is not necessary to consist only of an aromatic ring structure, and it may contain an alicyclic structure or a linear structure as part of it).

[0020] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, and tert-butyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0021] Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include cycloalkyl groups such as cyclopentyl and cyclohexyl groups; cycloalkenyl groups such as cyclopropenyl, cyclopentenyl, and cyclohexenyl groups; bridged ring saturated hydrocarbon groups such as norbornyl, adamantyl, and tricyclodecyl groups; and bridged ring unsaturated hydrocarbon groups such as norbornyl and tricyclodecenyl groups.

[0022] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include phenyl, tolyl, naphthyl, anthracenyl, and pyrenyl groups.

[0023] R 1 If the compound has substituents, examples of substituents include monovalent chain hydrocarbon groups having 1 to 10 carbon atoms, halogen atoms such as fluorine, chlorine, bromine, and iodine atoms, alkoxy groups such as methoxy, ethoxy, and propoxy groups, alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl groups, alkoxycarbonyloxy groups such as methoxycarbonyloxy and ethoxycarbonyloxy groups, acyl groups such as formyl, acetyl, propionyl, and butyryl groups, cyano groups, nitro groups, and hydroxyl groups.

[0024] Among them, R 1 From the viewpoint of copolymerization of the monomer that gives the repeating unit (1), a hydrogen atom or a methyl group is preferred.

[0025] In the above formula (1), L 1 The divalent linking group represented by is preferably a divalent hydrocarbon group, a carbonyl group, an oxygen atom (-O-), an imino group (-NH-), or a combination thereof.

[0026] L 1 The divalent hydrocarbon group in is the above R 1 Examples include groups obtained by removing one hydrogen atom from a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0027] Among them, L1 Examples thereof include a single bond, an alkanediyl group obtained by removing one hydrogen atom from an alkyl group having 1 to 10 carbon atoms, an arylene group obtained by removing one hydrogen atom from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a carbonyl group, an oxygen atom, an imino group, or a combination thereof. A single bond, an alkanediyl group having 1 to 5 carbon atoms, a phenylene group, a carbonyl group, an oxygen atom, an imino group, or a combination thereof are more preferable.

[0028] Specific examples of the repeating unit (1) include, for example, repeating units represented by the following formulas (1-1) to (1-10).

[0029]

Chemical formula

[0030] In the above formulas (1-1) to (1-10), R 1 has the same meaning as in the above formula (1). Among them, the repeating units represented by the above formulas (1-1), (1-5), and (1-9) are preferable.

[0031] When the [A] polymer contains the repeating unit (1), the lower limit of the content ratio of the repeating unit (1) containing the sulfonic acid group in all the repeating units constituting the [A] polymer is preferably 1 mol%, more preferably 5 mol%, still more preferably 10 mol%, and particularly preferably 20 mol%. The upper limit of the above content is preferably 100 mol%, more preferably 70 mol%, still more preferably 40 mol%, and particularly preferably 30 mol%. By setting the content ratio of the repeating unit (1) within the above range, pattern rectangularity can be exhibited at a high level. Further, within the above range, when a basic solution is used as the developer in the development step of the resist film, the resist underlayer film can be removed together with the resist film.

[0032] The [A] polymer preferably has a repeating unit represented by the following formula (2) (hereinafter, also referred to as "repeating unit (2)").

Chemical formula

[0033] In equation (2) above, R 2 As a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above formula (1), R 1 The group shown as a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by R, can be suitably adopted. 2 As such, a hydrogen atom or a methyl group is preferred from the viewpoint of copolymerization of the monomer that gives the repeating unit (2). 2 If it has substituents, the substituent is R of formula (1) above. 1 Preferred substituents that it may have include.

[0034] In the above formula (2), L 2 The divalent linking group represented by is L in formula (1) above. 1 The group shown as a divalent linking group represented by L can be suitably adopted. 2 Preferably, the group consists of a single bond, an alkanediyl group obtained by removing one hydrogen atom from an alkyl group having 1 to 10 carbon atoms, a cycloalkylene group obtained by removing one hydrogen atom from a cycloalkyl group having 5 to 10 carbon atoms, an arylene group obtained by removing one hydrogen atom from a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof. More preferably, the group consists of a single bond, an alkanediyl group having 1 to 5 carbon atoms, a cycloalkylene group having 5 to 7 carbon atoms, a phenylene group, a carbonyl group, an oxygen atom, or a combination thereof.

[0035] Specific examples of repeating units (2) include, for example, the repeating units represented by the following equations (2-1) to (2-8).

[0036] [ka]

[0037] In the above equations (2-1) to (2-8), R 2 This is equivalent to equation (2) above.

[0038] [A]When the polymer has repeating units (2), the lower limit of the content of repeating units (2) to the total repeating units constituting the polymer is preferably 10 mol%, more preferably 15 mol%, and even more preferably 20 mol%. The upper limit of the above content is preferably 99 mol%, more preferably 90 mol%, and even more preferably 80 mol%.

[0039] [A] The polymer preferably has repeating units represented by the following formula (3) (except in the case of formula (2) above) (hereinafter also referred to as "repeating unit (3)"). [ka] (In formula (3), R 3 L is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, either substituted or unsubstituted. 3 R is a single bond or a divalent linking group. 4 (This refers to a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.)

[0040] In equation (3) above, R 3 and R 4 The substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by the above formula (1) are R 1 The group shown as a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by R, can be suitably adopted. 3 As such, a hydrogen atom or a methyl group is preferred from the viewpoint of copolymerizability of the monomer that gives the repeating unit (3). 4 Preferably, a monovalent linear hydrocarbon group having 1 to 15 carbon atoms is preferred, and a monovalent branched alkyl group having 1 to 10 carbon atoms is more preferred. 3 and R 4 If it has substituents, the substituent is R of formula (1) above. 1 Preferred substituents that it may have include.

[0041] In the above formula (3), L 3 The divalent linking group represented by is L in formula (1) above. 1 The group shown as a divalent linking group represented by L can be suitably adopted. 3 Preferably, the group consists of a single bond, an alkanediyl group obtained by removing one hydrogen atom from an alkyl group having 1 to 10 carbon atoms, a cycloalkylene group obtained by removing one hydrogen atom from a cycloalkyl group having 5 to 10 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof. More preferably, the group consists of a single bond, an alkanediyl group having 1 to 5 carbon atoms, a cycloalkylene group having 5 to 7 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof, and even more preferably, a single bond.

[0042] Specific examples of repeating units (3) include, for example, the repeating units represented by the following formulas (3-1) to (3-18).

[0043] [ka]

[0044] In the above equations (3-1) to (3-18), R 3 This is equivalent to equation (3) above.

[0045] [A]When the polymer has repeating units (3), the lower limit of the content of repeating units (3) to the total repeating units constituting the polymer is preferably 20 mol%, more preferably 30 mol%, and still more preferably 35 mol%. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and still more preferably 65 mol%.

[0046] [A] The polymer preferably has repeating units represented by the following formula (4) (except in the cases of formulas (1), (2), and (3) above) (hereinafter also referred to as "repeating unit (4)"). [ka] (In formula (4), R 5L is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, either substituted or unsubstituted. 4 Ar is a single bond or a divalent linking group. 1 (It is a monovalent group having an aromatic ring with 6 to 20 members.)

[0047] In this specification, "ring member number" refers to the number of atoms that make up a ring. For example, the ring member number of a biphenyl ring is 12, the ring member number of a naphthalene ring is 10, and the ring member number of a fluorene ring is 13.

[0048] In the above equation (4), R 5 As a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above formula (1), R 1 The group shown as a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, represented by R, can be suitably adopted. 5 As such, a hydrogen atom or a methyl group is preferred from the viewpoint of copolymerizability of the monomer that gives the repeating unit (4). 5 If it has substituents, the substituent is R of formula (1) above. 1 Preferred substituents that it may have include.

[0049] In the above formula (4), L 4 The divalent linking group represented by is L in formula (1) above. 1 The group shown as a divalent linking group represented by L can be suitably adopted. 4 Preferably, the group consists of a single bond, an alkanediyl group obtained by removing one hydrogen atom from an alkyl group having 1 to 10 carbon atoms, a cycloalkylene group obtained by removing one hydrogen atom from a cycloalkyl group having 5 to 10 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof. More preferably, the group consists of a single bond, an alkanediyl group having 1 to 5 carbon atoms, a cycloalkylene group having 5 to 7 carbon atoms, a carbonyl group, an oxygen atom, or a combination thereof, and even more preferably, a single bond.

[0050] In the above formula (4), Ar 1Examples of aromatic rings with 6 to 20 members in the above include aromatic hydrocarbon rings such as benzene rings, naphthalene rings, anthracene rings, indene rings, and pyrene rings; aromatic heterocycles such as pyridine rings, pyrazine rings, pyrimidine rings, pyridazine rings, and triazine rings; or combinations thereof. 1 The aromatic ring is preferably at least one aromatic hydrocarbon ring selected from the group consisting of a benzene ring, naphthalene ring, anthracene ring, phenalene ring, phenanthrene ring, pyrene ring, fluorene ring, perylene ring, and coronene ring, and is more preferably a benzene ring, naphthalene ring, or pyrene ring.

[0051] In the above formula (4), Ar 1 As a monovalent group having an aromatic ring with 6 to 20 members represented by the above Ar 1 Suitable examples include groups obtained by removing one hydrogen atom from an aromatic ring with 6 to 20 members.

[0052] In the above formula (4), Ar 1 The monovalent group having an aromatic ring with 6 to 20 members, represented by the formula (1), may have substituents. In that case, the substituent may be R in formula (1) above. 1 When the molecule has substituents, the substituents exemplified can be suitably adopted.

[0053] Specific examples of repeating units (4) include, for example, the repeating units represented by the following equations (4-1) to (4-11).

[0054] [ka]

[0055] In the above equations (4-1) to (4-11), R 5 This is equivalent to formula (4) above. Among these, repeating units represented by formulas (4-1) and (4-9) above are preferred.

[0056] [A]When the polymer has repeating units (4), the lower limit of the content of repeating units (4) to the total repeating units constituting the polymer is preferably 10 mol%, more preferably 20 mol%, and still more preferably 30 mol%. The upper limit of the above content is preferably 90 mol%, more preferably 80 mol%, and still more preferably 70 mol%.

[0057] [A] The polymer may have repeating units (hereinafter also referred to as "repeating units (5)") that include at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. Examples of repeating units (5) include repeating units represented by the following formulas (T-1) to (T-10).

[0058] [ka]

[0059] In the above formula, R L1 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5 These are, independently, a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxyl group, a hydroxymethyl group, and a dimethylamino group. L4 and R L5 These may be divalent alicyclic groups having 3 to 8 carbon atoms, which can be combined with each other and formed together with the carbon atoms to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0060] The above R L4 and R L5The divalent alicyclic groups having 3 to 8 carbon atoms, which are formed when these groups are combined with each other and bonded together with the carbon atoms, are not particularly limited as long as they are groups obtained by removing two hydrogen atoms from the same carbon atom constituting the carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon of the above number of carbon atoms. Either monocyclic or polycyclic hydrocarbon groups may be used, and as polycyclic hydrocarbon groups, either bridged alicyclic hydrocarbon groups or condensed alicyclic hydrocarbon groups may be used, and either saturated or unsaturated hydrocarbon groups may be used. A condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which multiple alicyclics share an edge (a bond between two adjacent carbon atoms).

[0061] Among monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups, while preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups. Among polycyclic alicyclic hydrocarbon groups, bridged alicyclic saturated hydrocarbon groups are preferred, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1 3,7 A decane-2,2-diyl group (adamantane-2,2-diyl group) is preferred. One or more hydrogen atoms on this alicyclic group may be substituted with hydroxyl groups.

[0062] The above L 2T Examples of divalent linking groups represented by include divalent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of the groups -CO-, -O-, -NH-, and -S-.

[0063] Among these, repeating units (5) that include a lactone structure are preferred.

[0064] [A]When the polymer has repeating units (5), the lower limit of the content of repeating units (5) to the total repeating units constituting the polymer is preferably 3 mol%, more preferably 8 mol%, and still more preferably 10 mol%. The upper limit of the above content is preferably 40 mol%, more preferably 30 mol%, and still more preferably 25 mol%.

[0065] [A] The polymer may have repeating units containing heteroatom-containing groups (hereinafter also referred to as "repeating unit (6)") (except for those corresponding to repeating units (1) to (5)). Examples of the heteroatom-containing groups include hydroxyl groups, carboxyl groups, cyano groups, nitro groups, sulfonamide groups, etc. Among these, hydroxyl groups and carboxyl groups are preferred, and hydroxyl groups are more preferred.

[0066] Examples of repeating units (6) include the repeating unit represented by the following formula.

[0067] [ka]

[0068] In the above formula, R A This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0069] [A]When the polymer has repeating units (5), the lower limit of the content of repeating units (5) to the total repeating units constituting the polymer is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%. The upper limit of the above content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol%.

[0070] Other repeating units include repeating units used in polymers of resist compositions, such as repeating units incorporating the structure of the [B] onium salt described later.

[0071] [A] The lower limit of the weight-average molecular weight of the polymer is preferably 500, more preferably 1000, even more preferably 1500, and particularly preferably 2000. The upper limit of the molecular weight is preferably 10000, more preferably 9000, even more preferably 8000, and particularly preferably 7000. The method for measuring the weight-average molecular weight is as described in the examples.

[0072] The lower limit of the content of the polymer [A] in the resist underlayer film forming composition is preferably 1% by mass, more preferably 2% by mass, even more preferably 3% by mass, and particularly preferably 4% by mass, based on the total mass of the polymer [A], the onium salt [B], and the solvent [C]. The upper limit of the above content is preferably 20% by mass, more preferably 15% by mass, even more preferably 12% by mass, and particularly preferably 10% by mass, based on the total mass of the polymer [A] and the solvent [C].

[0073] The lower limit of the content of the [A] polymer in the components other than the [C] solvent in the resist underlayer film forming composition is preferably 10% by mass, more preferably 20% by mass, even more preferably 30% by mass, and particularly preferably 40% by mass. The upper limit of the above content is preferably 90% by mass, more preferably 80% by mass, and even more preferably 70% by mass.

[0074] [[A] Method for synthesizing polymers] [A] polymers can be synthesized by radical polymerization, ionic polymerization, polycondensation, polyaddition, addition condensation, etc., depending on the type of monomer. For example, when synthesizing [A] polymer by radical polymerization, the monomers that give each repeating unit can be polymerized in a suitable solvent using a radical polymerization initiator, etc.

[0075] Examples of the radical polymerization initiators mentioned above include azo-based radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl-2,2'-azobisisobutyrate (also known as 2,2'-azobis(2-methylpropionic acid)dimethyl); and peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. These radical initiators can be used individually or in combination of two or more.

[0076] As the solvent used in the polymerization described above, the [C] solvent described later can be suitably used. These solvents used in polymerization may be used alone or in combination of two or more.

[0077] The reaction temperature in the above polymerization is typically 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is typically 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0078] <[B] Onium salt> [B]onium salt is a compound having an anionic moiety and a cationic moiety, and upon exposure to radiation or heat, generates at least one polar group selected from the group consisting of a carboxyl group and a hydroxyl group. Although the polar group may be generated in one or both of the anionic and cationic moieties upon exposure to radiation or heat, it is preferable that the above polar group is generated in at least the anionic moiety of the [B]onium salt upon exposure to radiation or heat. The hydroxyl group may be either an alcoholic hydroxyl group or a phenolic hydroxyl group. [B]onium salt can also function as a component that generates acid upon the action of heat or radiation. [B]onium salt can be used alone or in combination of two or more types.

[0079] [B] Examples of onium salts include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, and pyridinium salts. Among these, sulfonium salts or iodonium salts are preferred.

[0080] [B] The anionic portion of the onium salt preferably has a sulfonic acid anion. Furthermore, it is more preferable that at least one selected from the group consisting of a fluorine atom and a fluorinated hydrocarbon group is bonded to the carbon atom to which the sulfonic acid anion is bonded. With these configurations, a sufficient amount of strong acid can be supplied to the bottom of the resist film, suppressing pattern trailing and further improving the rectangularity of the pattern.

[0081] The carboxyl group or hydroxyl group, as a polar group, preferably has a structure protected by a protecting group. Deprotection by radiation or heat will result in the formation of the carboxyl group or hydroxyl group. The protecting structure is not particularly limited, but examples include an ester structure for carboxyl groups, an acetal structure, an ester structure, or a (silyl) ether structure for alcoholic hydroxyl groups, and an ether structure for phenolic hydroxyl groups.

[0082] [B] The anionic portion of the onium salt preferably contains a ring structure. A polycyclic ring structure is preferred, and a norbondunane structure is more preferred.

[0083] [B] The onium salt preferably has the structure represented by the following formula (c). It is believed that the diffusion length of the acid generated in the resist film during the exposure process of the resist film is shortened to a more appropriate degree when the [B] onium salt has the following structure, and as a result, a resist underlayer film with excellent pattern rectangularity can be formed.

[0084] [ka]

[0085] In the above formula (c), R p1R is a monovalent organic group having 1 to 40 carbon atoms. p2 R is a divalent linking group. p3 and R p4 Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. p5 and R p6 Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. p1 n is an integer between 0 and 10. p2 n is an integer between 0 and 10. p3 n is an integer between 1 and 10. p1 If there are 2 or more, multiple R p2 n can be the same or different. p2 If there are 2 or more, multiple R p3 They may be the same or different, and multiple R p4 n can be the same or different. p3 If there are 2 or more, multiple R p5 They may be the same or different, and multiple R p6 They may be the same or different. + It is a monovalent radiation-sensitive onium cation.

[0086] R p1The monovalent organic group having 1 to 40 carbon atoms represented by is not particularly limited and may have a chain structure, a cyclic structure, or a combination thereof. Examples of the chain structure include chain hydrocarbon groups that are saturated or unsaturated, linear or branched. Examples of the cyclic structure include cyclic hydrocarbon groups that are alicyclic, aromatic, or heterocyclic. Among these, preferred monovalent organic groups are substituted or unsubstituted monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, substituted or unsubstituted monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, substituted or unsubstituted monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof. Also, groups in which some or all of the hydrogen atoms in a chain structure or a cyclic structure are substituted with substituents, and groups containing CO, CS, O, S, SO2, or NR', or a combination of two or more of these, between carbon atoms. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0087] Examples of substituents that substitute for some or all of the hydrogen atoms of the above organic group include halogen atoms such as fluorine, chlorine, bromine, and iodine; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, or groups in which the hydrogen atoms of these groups are substituted with halogen atoms; and oxo groups (=O).

[0088] Examples of the above-mentioned monovalent linear hydrocarbon groups having 1 to 20 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 20 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms.

[0089] Examples of the above-mentioned alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms constituting the alicyclic ring that are not adjacent to each other are bonded by a bond chain containing one or more carbon atoms.

[0090] Examples of the monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthyl groups; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups.

[0091] Examples of the heterocyclic cyclic hydrocarbon groups mentioned above include groups obtained by removing one hydrogen atom from an aromatic heterocyclic structure and groups obtained by removing one hydrogen atom from an alicyclic heterocyclic structure. Aromatic structures with five membered rings that acquire aromaticity by introducing heteroatoms are also included in heterocyclic structures. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0092] Examples of the above aromatic heterocyclic structures include, for example, Oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; Nitrogen-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; Sulfur atom-containing aromatic heterocyclic structures such as thiophene; Examples include aromatic heterocyclic structures containing multiple heteroatoms such as thiazole, benzothiazole, thiazine, and oxazine.

[0093] Examples of the above alicyclic heterocyclic structures include, for example, Oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, dioxane and other oxygen atom-containing alicyclic heterocyclic structures; Aziridine, pyrrolidine, piperidine, piperazine and other nitrogen atom-containing alicyclic heterocyclic structures; Thietane, thiolane, thiane and other sulfur atom-containing alicyclic heterocyclic structures; Alicyclic heterocyclic structures containing a plurality of heteroatoms such as morpholine, 1,2-oxathiolane, 1,3-oxathiolane, etc. may be mentioned.

[0094] As the cyclic structure, a structure including a lactone structure, a cyclic carbonate structure, a sultone structure and a cyclic acetal may also be mentioned. Such structures include, for example, structures represented by the following formulas (H-1) to (H-11).

[0095]

Chemical formula

[0096] In the above formula, m is an integer from 1 to 3.

[0097] Two or more of the structures represented by the above formulas (H-1) to (H-11) may form a condensed ring structure or a spiro structure. Alternatively, the structure represented by the above formulas (H-1) to (H-11) and another cyclic structure may form a condensed ring structure or a spiro structure.

[0098] R p2 As the divalent linking group represented by, for example, a carbonyl group, an ether bond, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group or a combination thereof, etc. may be mentioned. A cyclic structure shown in R p1 between these groups may also be present.

[0099] R p3 And R p4 As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by, for example, an alkyl group having 1 to 20 carbon atoms, etc. may be mentioned. R p3 And R p4Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by include fluorinated alkyl groups having 1 to 20 carbon atoms. R p3 and R p4 are preferably a hydrogen atom, a fluorine atom, and a fluorinated alkyl group, more preferably a fluorine atom and a perfluoroalkyl group, and even more preferably a fluorine atom and a trifluoromethyl group.

[0100] R p5 and R p6 Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by include fluorinated alkyl groups having 1 to 20 carbon atoms. R p5 and R p6 are preferably a fluorine atom and a fluorinated alkyl group, more preferably a fluorine atom and a perfluoroalkyl group, even more preferably a fluorine atom and a trifluoromethyl group, and particularly preferably a fluorine atom.

[0101] n p1 is preferably an integer of 0 to 5, more preferably an integer of 0 to 3, even more preferably an integer of 0 to 2, and particularly preferably 0 and 1.

[0102] n p2 is preferably an integer of 0 to 5, more preferably an integer of 0 to 2, even more preferably 0 and 1, and particularly preferably 0.

[0103] n p3 is preferably an integer of 1 to 5, more preferably an integer of 1 to 4, even more preferably an integer of 1 to 3, and particularly preferably 1 and 2.

[0104] X + The monovalent radiation-sensitive onium cation represented by is a cation that decomposes upon irradiation with exposure light. In the exposed area, sulfonic acid is generated from the proton generated by the decomposition of this photodegradable onium cation and the sulfonate anion. The above X +Examples of monovalent radiation-sensitive onium cations represented by the formula (ca) below (hereinafter also referred to as "cation (ca)"), cations represented by the formula (cb) below (hereinafter also referred to as "cation (cb)"), and cations represented by the formula (cc) below (hereinafter also referred to as "cation (cc)") are shown below.

[0105] [ka]

[0106] In the above formula (ca), R C3 , R C4 and R C5 Each of these independently comprises a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, and -OSO2-R CC1 Or -SO2-R CC2 This represents a ring structure formed by combining two or more of these groups. CC1 and R CC2 Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. c1, c2, and c3 are each independently integers from 0 to 5. C3 ~R C5 R CC1 and R CC2 If each of them is multiple, then multiple R C3 ~R C5 R CC1 and R CC2 These may be the same or different.

[0107] In the above formula (cb), R C6c4 is an integer from 0 to 7. C6 If there are multiple, then multiple R C6 They may be the same or different, and there may be multiple R C6 R may represent a ring structure formed by combining with other elements. C7 c5 is an integer from 0 to 6. C7 If there are multiple, then multiple R C7 They may be the same or different, and there may be multiple R C7 n may represent a ring structure formed by combining with other elements. c2 R is an integer between 0 and 3. C8 This refers to a single bond or a divalent organic group having 1 to 20 carbon atoms. c1 This is an integer between 0 and 2.

[0108] In the above formula (cc), R C9 and R C10 Each of these independently comprises a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, and -OSO2-R CC3 Or -SO2-R CC4 This represents a ring structure formed by combining two or more of these groups. CC3 and R CC4 Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. C6 and C7 are each independently integers from 0 to 5. C9 , R C10 , R CC3 and R CC4 If each of them is multiple, then multiple R C9 , R C10 , RCC3 and R CC4 These may be the same or different.

[0109] R C3 , R C4 , R C5 , R C6 , R C7 , R C9 and R C10 Examples of unsubstituted linear alkyl groups represented by include methyl, ethyl, n-propyl, and n-butyl groups.

[0110] R C3 , R C4 , R C5 , R C6 , R C7 , R C9 and R C10 Examples of unsubstituted branched alkyl groups represented by include i-propyl group, i-butyl group, sec-butyl group, and t-butyl group.

[0111] R C3 , R C4 , R C5 , R C9 and R C10 Examples of unsubstituted aromatic hydrocarbon groups represented by include, for example, Aryl groups such as phenyl, tolyl, xylyl, mesityl, and naphthyl groups; Examples include aralkyl groups such as benzyl groups and phenethyl groups.

[0112] R C6 and R C7 Examples of unsubstituted aromatic hydrocarbon groups represented by include phenyl groups, tolyl groups, and benzyl groups.

[0113] R C8Examples of divalent organic groups represented by include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups (a) containing a divalent heteroatom-containing group between carbon atoms or at the end of the bond side of the hydrocarbon group, and groups obtained by removing one hydrogen atom from the above hydrocarbon group and group (a) in which some or all of the hydrogen atoms are replaced with a monovalent heteroatom-containing group.

[0114] Examples of the above monovalent hydrocarbon group having 1 to 20 carbon atoms include R in formula (c) above. p1 Examples include groups similar to those exemplified as monovalent hydrocarbon groups having 1 to 20 carbon atoms, represented by [the formula shown].

[0115] Examples of the divalent heteroatom-containing groups mentioned above include -O-, -CO-, -CO-O-, -S-, -CS-, -SO2-, -NR'-, and groups consisting of two or more of these. R' is a hydrogen atom or a monovalent hydrocarbon group.

[0116] Examples of the monovalent heteroatom-containing groups mentioned above include halogen atoms such as fluorine, chlorine, bromine, and iodine, as well as hydroxyl groups, carboxyl groups, cyano groups, amino groups, and sulfanyl groups (-SH).

[0117] Examples of substituents that may substitute hydrogen atoms in alkyl groups and aromatic hydrocarbon groups include halogen atoms such as fluorine, chlorine, bromine, and iodine, as well as hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups. Among these, halogen atoms are preferred, and fluorine atoms are more preferred.

[0118] R in equation (c) above p1 ~R p6 , R in the above equation (ca) C3 ~R C5 , R in the above equation (cb) C6 ~R C7 , R in the above formula (cc) C9 ~R C10Preferably, at least one of them has a protective structure that is deprotected by radiation or heat to generate a carboxyl group or a hydroxyl group, and R in formula (c) above p1 ~R p6 It is more preferable that at least one of these has a protective structure that is deprotected by radiation or heat, resulting in the formation of a carboxyl group or a hydroxyl group.

[0119] Examples of the [B]onium salt represented by formula (c) above include the compounds represented by the following formulas (c1) to (c21) (hereinafter also referred to as "compounds (c1) to (c21)"). In the formulas, "Bu" represents the "n-butyl group".

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] The lower limit of the content of [B]onium salt in the resist underlayer film forming composition is preferably 1 part by mass, more preferably 3 parts by mass, and still more preferably 5 parts by mass, per 100 parts by mass of [A]polymer. The upper limit of the above content is preferably 50 parts by mass, more preferably 45 parts by mass, and still more preferably 40 parts by mass.

[0125] <[C] Solvent> [C] The solvent is not particularly limited as long as it can dissolve or disperse the [A] polymer, [B] onium salt, and any optional components it may contain.

[0126] Examples of [C] solvents include hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, and nitrogen-containing solvents. [C] solvents can be used individually or in combination of two or more.

[0127] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and cyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, and xylene.

[0128] Examples of ester solvents include carbonate solvents such as diethyl carbonate, acetic acid monoester solvents such as methyl acetate and ethyl acetate, lactone solvents such as γ-butyrolactone, polyhydric alcohol partial ether carboxylate solvents such as diethylene glycol acetate monomethyl ether and propylene glycol acetate monomethyl ether, and lactate ester solvents such as methyl lactate and ethyl lactate.

[0129] Examples of alcohol-based solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, and 4-methyl-2-pentanol, and polyhydric alcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0130] Examples of ketone solvents include linear ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and 2-heptanone, and cyclic ketone solvents such as cyclohexanone.

[0131] Examples of ether-based solvents include linear ether solvents such as n-butyl ether, polyhydric alcohol ether solvents such as cyclic ether solvents such as tetrahydrofuran, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether and propylene glycol monomethyl ether.

[0132] Examples of nitrogen-containing solvents include linear nitrogen-containing solvents such as N,N-dimethylacetamide and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0133] [C] The solvent is preferably an alcohol-based solvent, an ether-based solvent, or an ester-based solvent, more preferably a monoalcohol-based solvent, a polyhydric alcohol partial ether-based solvent, or a polyhydric alcohol partial ether carboxylate-based solvent, and even more preferably 4-methyl-2-pentanol, propylene glycol monomethyl ether, or propylene glycol acetate monomethyl ether.

[0134] The lower limit of the [C] solvent content in the resist underlayer film forming composition is preferably 50% by mass, more preferably 60% by mass, and still more preferably 70% by mass. The upper limit of the above content is preferably 99.9% by mass, more preferably 99% by mass, and still more preferably 95% by mass.

[0135] [Optional ingredients] The resist underlayer film forming composition may contain optional components as long as they do not impair the effects of the present invention. Examples of optional components include crosslinking agents, acid diffusion control agents, and surfactants. Optional components can be used individually or in combination of two or more.

[0136] ([D] Crosslinking agent) [D] The type of crosslinking agent is not particularly limited, and known crosslinking agents can be freely selected and used. Preferably, at least one selected from polyfunctional (meth)acrylates, cyclic ether-containing compounds, glycoluryls, diisocyanates, melamines, benzoguanamines, polynuclear phenols, polyfunctional thiol compounds, polysulfide compounds, and sulfide compounds is used as the crosslinking agent. By including [D] the crosslinking agent in the composition, electrostatic or chemical interactions (mainly crosslinking and hydrogen bonding) occur with the [B] onium salt, and the excessive diffusion of the acid generated from the [B] onium salt into the resist film can be suppressed more efficiently.

[0137] Polyfunctional (meth)acrylates are not particularly limited as long as they are compounds having two or more (meth)acryloyl groups, but examples include polyfunctional (meth)acrylates obtained by reacting an aliphatic polyhydroxy compound with (meth)acrylic acid, caprolactone-modified polyfunctional (meth)acrylates, alkylene oxide-modified polyfunctional (meth)acrylates, polyfunctional urethane (meth)acrylates obtained by reacting a hydroxyl-containing (meth)acrylate with a polyfunctional isocyanate, and polyfunctional (meth)acrylates having carboxyl groups obtained by reacting a hydroxyl-containing (meth)acrylate with an acid anhydride.

[0138] Specifically, for example, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerin tri(meth)acrylate, tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate, ethyleneglycerin Examples include chol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and bis(2-hydroxyethyl) isocyanurate di(meth)acrylate.

[0139] Examples of cyclic ether-containing compounds include oxyranyl group-containing compounds such as 1,6-hexanediol diglycidyl ether, 3',4'-epoxycyclohexenylmethyl-3',4'-epoxycyclohexene carboxylate, vinylcyclohexene monooxide 1,2-epoxy-4-vinylcyclohexene, and 1,2:8,9-diepoxylimonene; and oxetanyl group-containing compounds such as 3-ethyl-3-hydroxymethyl oxetane, 2-ethylhexyl oxetane, xylylene bisoxetane, and 3-ethyl-3{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane. These cyclic ether-containing compounds can be used individually or in combination of two or more.

[0140] Examples of glycoluryl compounds include tetramethylol glycoluryl, tetramethoxy glycoluryl, tetramethoxymethyl glycoluryl, compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are replaced with methoxymethyl groups, or mixtures thereof, compounds in which 1 to 4 methylol groups of tetramethylol glycoluryl are replaced with acyloxymethyl groups, or glycidyl glycoluryl compounds.

[0141] Examples of glycidyl glycoluryls include 1-glycidyl glycoluryl, 1,3-diglycidyl glycoluryl, 1,4-diglycidyl glycoluryl, 1,6-diglycidyl glycoluryl, 1,3,4-triglycidyl glycoluryl, 1,3,4,6-tetraglycidyl glycoluryl, 1-glycidyl-3a-methyl glycoluryl, 1-glycidyl-6a-methyl glycoluryl, 1,3-diglycidyl-3a-methyl glycoluryl, 1,4-diglycidyl-3a-methyl glycoluryl, 1,6-diglycidyl-3a-methyl glycoluryl, 1,3,4-triglycidyl-3a-methyl glycoluryl, 1,3,4-triglycidyl-6a-methyl glycoluryl, 1,3,4,6-tetraglycidyl-3a-methyl glycoluryl, and 1-glycidyl-3a,6a-diglycidyl-3a,6a- Examples include methyl glycoluryl, 1,3-diglycidyl-3a,6a-dimethyl glycoluryl, 1,4-diglycidyl-3a,6a-dimethyl glycoluryl, 1,6-diglycidyl-3a,6a-dimethyl glycoluryl, 1,3,4-triglycidyl-3a,6a-dimethyl glycoluryl, 1,3,4,6-tetraglycidyl-3a,6a-dimethyl glycoluryl, 1-glycidyl-3a,6a-diphenyl glycoluryl, 1,3-diglycidyl-3a,6a-diphenyl glycoluryl, 1,4-diglycidyl-3a,6a-diphenyl glycoluryl, 1,6-diglycidyl-3a,6a-diphenyl glycoluryl, 1,3,4,6-tetraglycidyl-3a,6a-diphenyl glycoluryl, and the like. These glycoluryl compounds can be used individually or in combination of two or more.

[0142] Examples of diisocyanates include 2,3-tole diisocyanate, 2,4-tole diisocyanate, 3,4-tole diisocyanate, 3,5-tole diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, and 1,4-cyclohexane diisocyanate.

[0143] Examples of melamines include melamine, monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, hexamethylolmelamine, monobutylolmelamine, dibutylolmelamine, tributylolmelamine, tetrabutylolmelamine, pentabutylolmelamine, hexabutylolmelamine, and alkylated derivatives of these methylolmelamines or butyrolmelamines. These melamines can be used individually or in combination of two or more.

[0144] Examples of benzoguanamines include benzoguanamines in which the amino group is modified with four alkoxymethyl groups (alkoxymethylol groups) (tetraalkoxymethylbenzoguanamines (tetraalkoxymethylolbenzoguanamines)), such as tetramethoxymethylbenzoguanamine; Benzoguanamine, in which the amino group is modified with a total of four alkoxymethyl groups (especially methoxymethyl groups) and hydroxymethyl groups (methylol groups); Benzoguanamine modified with three or fewer amino groups (especially methoxymethyl groups); Examples include benzoguanamine, which has a total of three or fewer amino groups modified with alkoxymethyl groups (especially methoxymethyl groups) and hydroxymethyl groups. These benzoguanamines can be used individually or in combination of two or more.

[0145] Examples of polynuclear phenols include dinuclear phenols such as 4,4'-biphenyldiol, 4,4'-methylenebisphenol, 4,4'-ethylidenebisphenol, and bisphenol A; trinuclear phenols such as 4,4',4”-methylidenttrisphenol, 4,4'-(1-(4-(1-(4-hydroxyphenyl)-1-methylethyl)phenyl)ethylidene)bisphenol, and 4,4'-(1-(4-(1-(4-hydroxy-3,5-bis(methoxymethyl)phenyl)-1-methylethyl)phenyl)ethylidene)bis(2,6-bis(methoxymethyl)phenol); and polyphenols such as novolac. These polynuclear phenols can be used individually or in combination of two or more.

[0146] Polyfunctional thiol compounds are compounds having two or more mercapto groups in one molecule. Specifically, for example, 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 2,3-dimercapto-1-propanol, dithioerythritol, 2,3-dimercaptosuccinic acid, 1,2-benzenedithiol, 1,2-benzenedimethanethiol, 1,3-benzenedithiol, 1,3-Benzene dimethanethiol, 1,4-Benzene dimethanethiol, 3,4-Dimercaptotoluene, 4-Chloro-1,3-Benzene dithiol, 2,4,6-Trimethyl-1,3-Benzene dimethanethiol, 4,4'-Thiodiphenol, 2-Hexylamino-4,6-Dimercapto-1,3,5-Triaidine, 2-Diethylamino-4,6-Dimercapto-1,3,5-Triaidine, 2-Cyclohexylamino-4,6-Dimercapto-1,3,5-Triaidine, 2-Di-n-Butylamino-4,6-Dimercapto-1,3,5-Triaidine Compounds having two mercapto groups, such as ethylene glycol bis(3-mercaptopropionate), butanediol bisthioglycolate, ethylene glycol bisthioglycolate, 2,5-dimercapto-1,3,4-thiadiazole, 2,2'-(ethylenedithio)diethanethiol, 2,2-bis(2-hydroxy-3-mercaptopropoxyphenylpropane), 1,2,6-hexanetriol trithioglycolate, 1,3,5-trithiocyanuric acid, trimethylolpropane tris(3-mercaptopropionate), trimethyl Examples include compounds having three mercapto groups, such as rollpropane tristhioglycolate, and compounds having four or more mercapto groups, such as pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol tetrakis(2-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.These polyfunctional thiol compounds can be used individually or in combination of two or more.

[0147] If the resist underlayer film forming composition contains a crosslinking agent [D], the lower limit of the [D] crosslinking agent content is preferably 1 part by mass, more preferably 2 parts by mass, and still more preferably 3 parts by mass, per 100 parts by mass of [A] polymer. The upper limit of the above content is preferably 60 parts by mass, more preferably 50 parts by mass, and still more preferably 40 parts by mass.

[0148] ([E] Acid diffusion control agent) [E] Acid diffusion control agents capture acids and cations. [E] Acid diffusion control agents can be used individually or in combination of two or more types.

[0149] The above [E] acid diffusion control agents can be divided into compounds that are radioactive and compounds that are not radioactive.

[0150] Basic compounds are preferred as compounds that do not exhibit the above-mentioned radioactivity. Examples of these basic compounds include hydroxide compounds, carboxylate compounds, amine compounds, imine compounds, amide compounds, etc. More specifically, examples include primary to tertiary aliphatic 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, nitrogen-containing compounds having a carbamate group, amide compounds, imide compounds, etc. Among these, nitrogen-containing compounds having a carbamate group are preferred.

[0151] Furthermore, the basic compounds may also be Troger's bases; hindered amines such as diazabicycloundecene (DBU) and diazabicyclononene (DBM); or ionic quenchers such as tetrabutylammonium hydroxide (TBAH) and tetrabutylammonium lactate.

[0152] Examples of the above primary aliphatic amines include ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, pentylamine, tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine, ethylenediamine, tetraethylenepentamine, and the like.

[0153] Examples of the above secondary aliphatic amines include dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine, dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine, N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, and N,N-dimethyltetraethylenepentamine.

[0154] Examples of the above-mentioned tertiary aliphatic amines include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tripentylamine, tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, tridodecylamine, tricetylamine, N,N,N',N'-tetramethylmethylenediamine, N,N,N',N'-tetramethylethylenediamine, and N,N,N',N'-tetramethyltetraethylenepentamine.

[0155] Examples of the aromatic amines and heterocyclic amines mentioned above include aniline derivatives such as aniline, N-methylaniline, N-ethylaniline, N-propylaniline, N,N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, ethylaniline, propylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline, 2,6-dinitroaniline, 3,5-dinitroaniline, and N,N-dimethyltoluidine; diphenyl(p-tolyl)amine; methyldiphenylamine Triphenylamine; phenylenediamine; naphthylamine; diaminonaphthalene; pyrrole derivatives such as pyrrole, 2H-pyrrole, 1-methylpyrrole, 2,4-dimethylpyrrole, 2,5-dimethylpyrrole, and N-methylpyrrole; oxazole derivatives such as oxazole and isoxazole; thiazole derivatives such as thiazole and isothiazole; imidazole derivatives such as imidazole, 4-methylimidazole, and 4-methyl-2-phenylimidazole; pyrazole derivatives; furazan derivatives; pyrroline derivatives such as pyrroline and 2-methyl-1-pyrrolin Conductors; pyrrolidine derivatives such as pyrrolidine, N-methylpyrrolidine, pyrrolidinone, N-methylpyrrolidone; imidazoline derivatives; imidazolidine derivatives; pyridine, methylpyridine, ethylpyridine, propylpyridine, butylpyridine, 4-(1-butylpentyl)pyridine, dimethylpyridine, trimethylpyridine, triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridine, 4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine, 4-pyrrolidine Pyridine derivatives such as nopyridine, 2-(1-ethylpropyl)pyridine, aminopyridine, and dimethylaminopyridine; pyridazine derivatives; pyrimidine derivatives; pyrazine derivatives; pyrazoline derivatives; pyrazolidine derivatives; piperidine derivatives; piperazine derivatives; morpholine derivatives; indole derivatives; isoindole derivatives; 1H-indazole derivatives; indoline derivatives; quinoline derivatives such as quinoline and 3-quinoline carbonnitrile; isoquinoline derivatives; sinnoline derivatives; quinazoline derivatives; quinoxaline derivatives; phthalazine derivatives; purine derivatives;Examples include pteridine derivatives; carbazole derivatives; phenanthridine derivatives; acridine derivatives; phenazine derivatives; 1,10-phenanthroline derivatives; adenine derivatives; adenosine derivatives; guanine derivatives; guanosine derivatives; uracil derivatives; and uridine derivatives.

[0156] Examples of nitrogen-containing compounds having the carboxyl group mentioned above include aminobenzoic acid; indolecarboxylic acid; nicotinic acid, alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine, methionine, phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic acid, methoxyalanine, and other amino acid derivatives.

[0157] Examples of nitrogen-containing compounds having the above-mentioned sulfonyl group include 3-pyridinesulfonic acid and pyridinium p-toluenesulfonate.

[0158] Examples of nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, and alcoholic nitrogen-containing compounds include 2-hydroxypyridine, aminocresol, 2,4-quinoline diol, 3-indole methanol hydrate, monoethanolamine, diethanolamine, triethanolamine, N-ethyldiethanolamine, N,N-diethylethanolamine, triisopropanolamine, 2,2'-iminodiethanol, 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, 4-(2-hydroxyethyl)morpholine, 2-(2-Hydro Examples include roxyethyl)pyridine, 1-(2-hydroxyethyl)piperazine, 1-[2-(2-hydroxyethoxy)ethyl]piperazine, piperidineethanol, 1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)-2-pyrrolidinone, 3-piperidino-1,2-propanediol, 3-pyrrolidino-1,2-propanediol, 8-hydroxyeuroridine, 3-quinoclidinol, 3-tropanol, 1-methyl-2-pyrrolidineethanol, 1-aziridineethanol, N-(2-hydroxyethyl)phthalimide, and N-(2-hydroxyethyl)isonicotinamide.

[0159] Examples of nitrogen-containing compounds having a carbamate group include N-(tert-butoxycarbonyl)-L-alanine, N-(tert-butoxycarbonyl)-L-alanine methyl ester, (S)-(-)-2-(tert-butoxycarbonylamino)-3-cyclohexyl-1-propanol, (R)-(+)-2-(tert-butoxycarbonylamino)-3-methyl-1-butanol, (R)-(+)-2-(tert-butoxycarbonylamino)-3-phenylpropanol, (S)-(-)-2-(tert-butoxycarbon Nylamino)-3-phenylpropanol, (R)-(+)-2-(tert-butoxycarbonylamino)-3-phenyl-1-propanol, (S)-(-)-2-(tert-butoxycarbonylamino)-3-phenyl-1-propanol, (R)-(+)-2-(tert-butoxycarbonylamino)-1-propanol, (S)-(-)-2-(tert-butoxycarbonylamino)-1-propanol, N-(tert-butoxycarbonyl)-L-aspartic acid 4-benzyl ester, N-(tert-butoxycarbonyl Bonyl)-O-benzyl-L-threonine, (R)-(+)-1-(tert-butoxycarbonyl)-2-tert-butyl-3-methyl-4-imidazolidinone, (S)-(-)-1-(tert-butoxycarbonyl)-2-tert-butyl-3-methyl-4-imidazolidinone, N-(tert-butoxycarbonyl)-3-cyclohexyl-L-alanine methyl ester, N-(tert-butoxycarbonyl)-L-cysteine ​​methyl ester, N-(tert-butoxycarbonyl)ethanolamine, N-(tert- Toxycarbonylethylenediamine, N-(tert-butoxycarbonyl)-D-glucoseamine, Nα-(tert-butoxycarbonyl)-L-glutamine, 1-(tert-butoxycarbonyl)imidazole, N-(tert-butoxycarbonyl)-L-isoleucine, N-(tert-butoxycarbonyl)-L-isoleucine methyl ester, N-(tert-butoxycarbonyl)-L-leucinol, Nα-(tert-butoxycarbonyl)-L-lysine, N-(tert-butoxycarbonyl)-L-methinonine,N-(tert-butoxycarbonyl)-3-(2-naphthyl)-L-alanine, N-(tert-butoxycarbonyl)-L-phenylalanine, N-(tert-butoxycarbonyl)-L-phenylalanine methyl ester, N-(tert-butoxycarbonyl)-D-prolinal, N-(tert-butoxycarbonyl)-L-proline, N-(tert-butoxycarbonyl)-L-proline-N'-methoxy-N'-methylamide, N-(tert-butoxycarbonyl)-1H-pyrazole-1-carboxyamidine, (S )-(-)-1-(tert-butoxycarbonyl)-2-pyrrolidinemethanol, (R)-(+)-1-(tert-butoxycarbonyl)-2-pyrrolidinemethanol, 1-(tert-butoxycarbonyl)3-[4-(1-pyrrolyl)phenyl]-L-alanine, N-(tert-butoxycarbonyl)-L-serine, N-(tert-butoxycarbonyl)-L-serine methyl ester, N-(tert-butoxycarbonyl)-L-threonine, N-(tert-butoxycarbonyl)-p-toluenesulfonamide, N-(t ert-butoxycarbonyl)-S-trityl-L-cysteine, Nα-(tert-butoxycarbonyl)-L-tryptophan, N-(tert-butoxycarbonyl)-L-tyrosine, N-(tert-butoxycarbonyl)-L-tyrosine methyl ester, N-(tert-butoxycarbonyl)-L-valine, N-(tert-butoxycarbonyl)-L-valine methyl ester, N-(tert-butoxycarbonyl)-L-valinol, tert-butyl N-(3-hydroxypropyl)carbamate, tert-butyl N- (6-aminohexyl)carbamate, tert-butylcarbamate, tert-butylcarbazate, tert-butyl-N-(benzyloxy)carbamate, tert-butyl-4-benzyl-1-piperazine carboxylate, tert-butyl(1S,4S)-(-)-2,5-diazabicyclo[2.2.1]heptan-2-carboxylate, tert-butyl-N-(2,3-dihydroxypropyl)carbamate, tert-butyl(S)-(-)-4-formyl-2,2-dimethyl-3-oxazolidine carboxylate,Examples include tert-butyl[R-(R*,S*)]-N-[2-hydroxy-2-(3-hydroxyphenyl)-1-methylethyl]carbamate, tert-butyl-4-oxo-1-piperidine carboxylate, tert-butyl-1-pyrrole carboxylate, tert-butyl-1-pyrrolidine carboxylate, and tert-butyl(tetrahydro-2-oxo-3-furanyl)carbamate.

[0160] Examples of the above-mentioned amide compounds include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, and 1-cyclohexylpyrrolidone.

[0161] Examples of the above-mentioned imide compounds include phthalimide, succinimide, and maleimide.

[0162] Furthermore, the above-mentioned radioactive compounds can be divided into compounds that decompose upon radiation and lose their ability to control acid diffusion (radiolysis compounds) and compounds that are generated upon radiation and gain the ability to control acid diffusion (radiation-generated compounds).

[0163] The above radioactive compounds are preferably sulfonates and carboxylates of radioactive cations. The sulfonic acid in the sulfonate is preferably a weak acid, and more preferably one having a hydrocarbon group with 1 to 20 carbon atoms, and the hydrocarbon group not containing fluorine. Examples of such sulfonic acids include alkyl sulfonic acid, benzenesulfonic acid, and 10-camphorsulfonic acid. The carboxylic acid in the carboxylate is preferably a weak acid, and more preferably a carboxylic acid with 1 to 20 carbon atoms. Examples of such carboxylic acids include formic acid, acetic acid, propionic acid, tartaric acid, succinic acid, cyclohexylcarboxylic acid, benzoic acid, and salicylic acid. The radioactive cation in the carboxylate of the radioactive cation is preferably an onium cation, and examples of such onium cations include iodonium cation and sulfonium cation.

[0164] The above-mentioned radiation-generating compounds are preferably compounds that generate bases upon exposure (radiation-sensitive base generators), and more preferably nitrogen-containing organic compounds that generate amino groups.

[0165] Examples of the above-mentioned radiation-sensitive base generating agents include the compounds described in Japanese Patent Publication Nos. 4-151156, 4-162040, 5-197148, 5-5995, 6-194834, 8-146608, 10-83079, and European Patent No. 622682.

[0166] Furthermore, examples of the above-mentioned radiation-sensitive base generating agent include compounds containing a carbamate group (urethane bond), compounds containing an acyloxyimino group, ionic compounds (anion-cation complexes), and compounds containing a carbamoyloxyimino group, with compounds containing a carbamate group (urethane bond), compounds containing an acyloxyimino group, and ionic compounds (anion-cation complexes) being preferred.

[0167] Furthermore, compounds having a ring structure within the molecule are preferred as radiation-sensitive base generators. Examples of such ring structures include benzene, naphthalene, anthracene, xanthone, thioxanthone, anthraquinone, and fluorene.

[0168] Examples of radiation-sensitive base generators include 2-nitrobenzylcarbamate, 2,5-dinitrobenzylcyclohexylcarbamate, N-cyclohexyl-4-methylphenylsulfonamide, and 1,1-dimethyl-2-phenylethyl-N-isopropylcarbamate.

[0169] When the resist underlayer film forming composition contains an [E] acid diffusion control agent, the lower limit of the [E] acid diffusion control agent content is preferably 0.1 parts by mass, more preferably 1 part by mass, and even more preferably 3 parts by mass, per 100 parts by mass of [A] polymer. The upper limit of the above content is preferably 40 parts by mass, more preferably 30 parts by mass, and even more preferably 20 parts by mass.

[0170] [Method for preparing a composition for forming a resist underlayer film] The resist underlayer film forming composition can be prepared by mixing [A] polymer, [B] onium salt, [C] solvent, and optionally any other components in predetermined proportions, and preferably by filtering the resulting mixture through a membrane filter with a pore size of 0.5 μm or less.

[0171] [Silicon-containing film formation process] In this step, which is performed before the coating step (I) described above, a silicon-containing film is formed on the substrate either directly or indirectly.

[0172] Examples of substrates include metal or metalloid substrates such as silicon substrates, aluminum substrates, nickel substrates, chromium substrates, molybdenum substrates, tungsten substrates, copper substrates, tantalum substrates, and titanium substrates, with silicon substrates being preferred among these. The above substrates may also be substrates on which silicon nitride films, alumina films, silicon dioxide films, tantalum nitride films, titanium nitride films, etc., are formed.

[0173] Silicon-containing films can be formed by coating with a silicon-containing film-forming composition, chemical vapor deposition (CVD), atomic layer deposition (ALD), etc. Methods for forming silicon-containing films by coating with a silicon-containing film-forming composition include, for example, directly or indirectly coating a substrate with the silicon-containing film-forming composition and then curing the resulting coating by exposure and / or heating. Commercially available silicon-containing film-forming compositions include, for example, "NFC SOG01," "NFC SOG04," and "NFC SOG080" (all from JSR Corporation). Silicon oxide films, silicon nitride films, silicon oxynitride films, and amorphous silicon films can be formed by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0174] Examples of radiation used in the above exposure include electromagnetic waves such as visible light, ultraviolet rays, far ultraviolet rays, X-rays, and gamma rays, as well as particle beams such as electron beams, molecular beams, and ion beams.

[0175] The lower limit of the temperature when heating the coating film is preferably 90°C, more preferably 150°C, and even more preferably 200°C. The upper limit of the above temperature is preferably 550°C, more preferably 450°C, and even more preferably 300°C.

[0176] The lower limit of the average thickness of the silicon-containing film is preferably 1 nm, more preferably 10 nm, and even more preferably 15 nm. The upper limit is preferably 20,000 nm, more preferably 1,000 nm, and even more preferably 100 nm. The average thickness of the silicon-containing film can be measured in the same way as the average thickness of the resist underlayer film.

[0177] Examples of cases where a silicon-containing film is indirectly formed on a substrate include forming a silicon-containing film on a low-dielectric insulating film or an organic underlayer film formed on the substrate.

[0178] [Coating process (I)] In this process, the resist underlayer forming composition is coated onto the silicon-containing film formed on the substrate. The coating method for the resist underlayer forming composition is not particularly limited and can be carried out by any suitable method, such as rotary coating, casting coating, or roll coating. A coating film is formed as a result, and the resist underlayer is formed due to the volatilization of the [C] solvent, etc.

[0179] Furthermore, if the resist underlayer film formation composition is applied directly to the substrate, the silicon-containing film formation step described above may be omitted.

[0180] Next, the coating film formed by the above coating process is heated. Heating the coating film promotes the formation of the resist underlayer film. More specifically, heating the coating film promotes the volatilization of the [C] solvent, etc.

[0181] The above-mentioned coating film may be heated under an atmospheric environment or under a nitrogen atmosphere. The lower limit of the heating temperature is preferably 100°C, more preferably 150°C, and even more preferably 200°C. The upper limit of the heating temperature is preferably 400°C, more preferably 350°C, and even more preferably 280°C. The lower limit of the heating time is preferably 15 seconds, more preferably 30 seconds. The upper limit of the heating time is preferably 1,200 seconds, and even more preferably 600 seconds.

[0182] The lower limit of the average thickness of the resist underlayer film formed is preferably 0.5 nm, more preferably 1 nm, and even more preferably 2 nm. The upper limit of the average thickness is 100 nm, preferably 50 nm, more preferably 20 nm, and even more preferably 10 nm. The method for measuring the average thickness is as described in the examples.

[0183] [Coating Process (II)] In this step, the resist film-forming composition is applied to the resist film-forming composition formed in the resist film-forming composition coating step described above. The method for applying the resist film-forming composition is not particularly limited and can be, for example, a rotary coating method.

[0184] To explain this process in more detail, for example, after coating the resist composition so that the resist film to be formed has a predetermined thickness, the solvent in the coated film is evaporated by pre-baking (hereinafter also referred to as "PB") to form the resist film.

[0185] The PB temperature and PB time can be appropriately determined depending on the type of resist film-forming composition used. The lower limit of the PB temperature is preferably 30°C, and more preferably 50°C. The upper limit of the PB temperature is preferably 200°C, and more preferably 150°C. The lower limit of the PB time is preferably 10 seconds, and more preferably 30 seconds. The upper limit of the PB time is preferably 600 seconds, and more preferably 300 seconds.

[0186] Examples of resist film-forming compositions used in this process include positive or negative type chemically amplified resist compositions containing a radiation-sensitive acid generator, positive type resist compositions containing an alkali-soluble resin and a quinone diazide-based photosensitive agent, negative type resist compositions containing an alkali-soluble resin and a crosslinking agent, and metal-containing resist compositions containing metals such as tin and zirconium.

[0187] [Synthesis process] In this step, the resist film formed by the above resist film formation composition coating step is exposed to radiation.

[0188] The radiation used for exposure can be appropriately selected depending on the type of resist film-forming composition used. Examples include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and gamma rays, as well as particle beams such as electron beams, molecular beams, and ion beams. Among these, far ultraviolet light is preferred, with KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F2 excimer laser light (wavelength 157 nm), Kr2 excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), or extreme ultraviolet light (wavelength 13.5 nm, also called "EUV") being more preferred, and ArF excimer laser light or EUV being even more preferred. Furthermore, the exposure conditions can be appropriately determined depending on the type of resist film-forming composition used.

[0189] Furthermore, in this process, after exposure, post-exposure baking (hereinafter also referred to as "PEB") can be performed to improve the performance of the resist film, such as resolution, pattern profile, and developability. The PEB temperature and PEB time can be appropriately determined according to the type of resist film forming composition used. The lower limit of the PEB temperature is preferably 50°C, and more preferably 70°C. The upper limit of the PEB temperature is preferably 200°C, and more preferably 150°C. The lower limit of the PEB time is preferably 10 seconds, and more preferably 30 seconds. The upper limit of the PEB time is preferably 600 seconds, and more preferably 300 seconds.

[0190] [Development process] In this step, the exposed resist film is developed. At this time, a portion of the underlying resist film may also be developed. Examples of developers used for this development include alkaline aqueous solutions (alkaline developer) and organic solvent-containing solutions (organic solvent developer).

[0191] The basic solution for alkaline development is not particularly limited, and known basic solutions can be used. Examples of basic solutions for alkaline development include alkaline aqueous solutions in which at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene is dissolved. Among these, aqueous TMAH is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0192] Examples of organic solvent developers used in organic solvent development include those similar to those exemplified as the [C] solvent above. Preferred organic solvents include ester solvents, ether solvents, alcohol solvents, ketone solvents, and / or hydrocarbon solvents, with ketone solvents being more preferred, and 2-heptanone being particularly preferred.

[0193] In this process, washing and / or drying may be performed after the development described above.

[0194] [Etching process] In this process, etching is performed using the resist pattern (and the resist underlayer film pattern) as a mask. The number of etching times can be once or multiple times, that is, sequential etching may be performed using the pattern obtained by etching as a mask. From the viewpoint of obtaining a pattern with a better shape, multiple times are preferable. When performing multiple times of etching, for example, etching is sequentially performed in the order of the silicon-containing film and the substrate. Examples of the etching method include dry etching and wet etching. From the viewpoint of making the shape of the substrate pattern better, dry etching is preferable. For this dry etching, for example, gas plasmas such as oxygen plasma are used. Through the above etching, a semiconductor substrate having a predetermined pattern is obtained.

[0195] As dry etching, for example, it can be performed using a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected according to the mask pattern, the elemental composition of the film to be etched, etc. Examples include fluorine-based gases such as CHF3, CF4, C2F6, C3F8, SF6, chlorine-based gases such as Cl2, BCl3, oxygen-based gases such as O2, O3, H2O, reducing gases such as H2, NH3, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H4, C3H6, C3H8, HF, HI, HBr, HCl, NO, NH3, BCl3, and inert gases such as He, N2, Ar. These gases can also be used in combination. When etching the substrate using the pattern of the resist underlayer film as a mask, usually, a fluorine-based gas is used.

[0196] In addition, when a silicon-containing film remains on the substrate or the like after forming the substrate pattern, the silicon-containing film can be removed by performing the removal process described below.

[0197] 《Composition for Forming Resist Underlayer Film》 The composition for forming a resist underlayer film contains [A] a polymer, [B] an onium salt, and [C] a solvent. As such a composition for forming a resist underlayer film, the composition for forming a resist underlayer film used in the method for manufacturing the semiconductor substrate can be preferably adopted.

Example

[0198] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0199] [Weight average molecular weight (Mw)] The Mw of the polymer was measured by gel permeation chromatography (detector: differential refractometer) using Tosoh Corporation's GPC columns (two "G2000HXL" and one "G3000HXL") under the analysis conditions of a flow rate of 1.0 mL / min, an elution solvent of tetrahydrofuran, and a column temperature of 40°C, with monodisperse polystyrene as the standard.

[0200] [Average thickness of the film] The average thickness of the film was determined as the average value of the film thicknesses measured at nine arbitrary positions at 5 cm intervals including the center of the resist underlayer film using a spectroscopic ellipsometer ("M2000D" manufactured by J.A. WOLLAM).

[0201] <Synthesis of [A] polymer> Polymers represented by the following formulas (A-1) to (A-2) (hereinafter also referred to as "polymers (A-1) to (A-2)") were synthesized according to the procedures shown below.

[0202]

Chemical formula

[0203] In the above formulas (A-1) to (A-2), the numbers attached to each repeating unit indicate the content ratio (mol%) of that repeating unit.

[0204] [Synthesis Example 1] (Synthesis of polymer (A-1)) 36 g of 4-acetoxystyrene and 64 g of ethylhexyl methacrylate were dissolved in 130 g of 1-methoxy-3-propanol, and 10 g of 2,2'-azobis(2-methylpropionic acid)dimethyl was added to prepare a monomer solution. In a reaction vessel, 70 g of 1-methoxy-3-propanol was placed under a nitrogen atmosphere and heated to 80°C. The monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction. The polymerization reaction was carried out for 6 hours, and then cooled to below 30°C. 180 g of methanol, 48.1 g of triethylamine, and 8.6 g of water were added to the reaction solution, heated to 70°C, and reacted for 6 hours while stirring, then cooled to below 30°C. 300 g of methyl isobutyl ketone and 1000 g of 5% oxalic acid solution were added, and after liquid-liquid extraction, the mixture was added to hexane for reprecipitation. After removing the supernatant by decantation, 300 g of propylene glycol monomethyl ether acetate was added, and the mixture was concentrated under reduced pressure to obtain a solution of polymer (A-1) in propylene glycol monomethyl ether acetate. The Mw of polymer (A-1) was 3,600.

[0205] [Synthesis Example 2] (Synthesis of polymer (A-2)) 1-Ethylcyclopentyl methacrylate 43g, 3-Hydroxytricyclo(3.3.1.1 3,7 33 g of decane-1-yl methacrylate, 24 g of 2-oxotetrahydrofuran-3-yl methacrylate, and 16.2 g of 2,2'-azobis(2-methylpropionic acid)dimethyl were added to prepare a monomer solution. In a reaction vessel, 300 g of methyl isobutyl ketone was placed under a nitrogen atmosphere and heated to 80°C. The monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours, after which it was cooled to below 30°C. 300 g of propylene glycol acetate monomethyl ether was added to the reaction solution, and the methyl isobutyl ketone was removed by vacuum concentration to obtain a propylene glycol acetate monomethyl ether solution of polymer (A-2). The Mw of polymer (A-2) was 6,600.

[0206] <Preparation of Composition> The [A] polymer, [B] onium salt, [C] solvent, and [D] crosslinking agent used in the preparation of the composition are shown below.

[0207] [[A] Polymer] The synthesized polymers (A-1) to (A-2)

[0208] [[B] Onium Salt] Examples B-1 to B-13: Compounds represented by the following formulas (B-1) to (B-13) Comparative Examples b-1 to b-2: Compounds represented by the following formulas (b-1) to (b-2)

[0209] [Chemical formula]

[0210] [Chemical formula]

[0211] [Chemical formula]

[0212] [Chemical formula]

[0213] [[C] Solvent] C-1: Propylene glycol monomethyl ether acetate C-2: 4-Methyl-2-pentanol

[0214] [[D] Crosslinking Agent] D-1: Compound represented by the following formula (D-1) D-2: Compound represented by the following formula (D-2)

[0215] [Chemical formula]

[0216] [Example 1] [A] 100 parts by mass of (A-1) as a polymer, [B] 30 parts by mass of (B-1) as an onium salt, and [D] 30 parts by mass of (D-1) as a crosslinking agent were dissolved in a mixed solvent of [C] 1100 parts by mass of (C-1) and 200 parts by mass of (C-2) as a solvent. The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare composition (J-1).

[0217] [Examples 2-15 and Comparative Examples 1-2] Compositions (J-2) to (J-15) and (CJ-1) to (CJ-2) were prepared in the same manner as in Example 1, except that the components used were of the types and in the amounts shown in Table 1 below.

[0218] [Table 1]

[0219] <Rating> The storage stability and rectangularity of the resist pattern were evaluated using the above-prepared compositions by the following method. The evaluation results are shown in Table 2 below.

[0220] [Storage stability] The above-mentioned prepared composition was applied to a 12-inch silicon wafer using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Ltd.) under the conditions of 1,500 rpm and 30 seconds. The resulting coated film was then heated at 90°C for 60 seconds to form a resist underlayer. The resist underlayer composition prepared on the day of preparation (T=0) was referred to as "resist underlayer (a0)," and the resist underlayer composition stored at 60°C for 2 days (T=2) was referred to as "resist underlayer (a1)." When the average thickness of resist underlayer (a0) was T0 and the average thickness of resist underlayer (a1) was T1, the rate of change in film thickness (%) was calculated using the following formula and used as an indicator of storage stability. Film thickness change rate (%) = (|T1-T0| / T0) × 100 The storage stability was evaluated as "A" (good) when the film thickness change rate was less than 10%, and "B" (bad) when it was 10% or more.

[0221] <Preparation of EUV Exposure Resist Composition> The EUV exposure resist composition (R-1) was obtained by mixing 100 parts by mass of a polymer having repeating units (1) derived from 4-hydroxystyrene, repeating units (2) derived from styrene, and repeating units (3) derived from 4-t-butoxystyrene (the content ratio of each repeating unit was (1) / (2) / (3) = 65 / 5 / 30 (mol%)), 1.0 part by mass of triphenylsulfonium trifluoromethanesulfonate as a radiation-sensitive acid generator, 4,400 parts by mass of ethyl lactate as a solvent, and 1,900 parts by mass of propylene glycol monomethyl ether acetate, and filtering the resulting solution through a filter with a pore size of 0.2 μm.

[0222] [Pattern Rectangularity (EUV Exposure)] An organic underlayer film with an average thickness of 100 nm was formed on a 12-inch silicon wafer by applying an organic underlayer film formation material (HM8006 from JSR Corporation) using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Limited) and then heating at 250°C for 60 seconds. A silicon-containing film formation composition (NFC SOG080 from JSR Corporation) was applied to this organic underlayer film, heated at 220°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a silicon-containing film with an average thickness of 20 nm. The above-prepared composition was applied to the silicon-containing film, heated at 250°C for 60 seconds, and then cooled at 23°C for 30 seconds to form a resist underlayer film with an average thickness of 5 nm. A resist composition for EUV exposure (R-1) was applied to the resist underlayer film formed above, and after heating at 130°C for 60 seconds, a resist film with an average thickness of 50 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was irradiated with extreme ultraviolet light using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadruple pole illumination, wafer-mounted 1:1 line-and-space mask with a line width of 16 nm)). After irradiation with extreme ultraviolet light, the substrate was heated at 110°C for 60 seconds, and then cooled at 23°C for 60 seconds. Subsequently, the substrate was developed using the paddle method with a 2.38 mass% tetramethylammonium hydroxide aqueous solution (20°C-25°C), washed with water, and dried to obtain an evaluation substrate with a resist pattern formed on it. A scanning electron microscope (Hitachi High-Technologies Corporation's "SU8220") was used to measure and observe the resist pattern on the evaluation substrate. Pattern rectangularity was evaluated as follows: "A" (good) if the cross-sectional shape of the pattern was rectangular, "B" (fairly good) if there was a trailing edge in the cross-section of the pattern, and "C" (poor) if there was residue (defects) in the pattern.

[0223] [Table 2]

[0224] As can be seen from the results in Table 2, the resist underlayer formation composition of the example showed good storage stability. Furthermore, the resist underlayer formed from the resist underlayer formation composition of the example showed superior pattern rectangularity compared to the resist underlayer formed from the resist underlayer formation composition of the comparative example. [Industrial applicability]

[0225] The semiconductor substrate manufacturing method of the present invention enables the formation of a resist underlayer film with excellent pattern rectangularity and uses a resist underlayer film formation composition that also exhibits excellent storage stability, thus allowing for efficient manufacturing of semiconductor substrates. The resist underlayer film formation composition of the present invention provides good storage stability and enables the formation of a film with excellent pattern rectangularity. Therefore, these can be suitably used in the manufacture of semiconductor devices, for which further miniaturization is expected in the future.

Claims

1. Polymers and, An onium salt that generates at least one polar group selected from the group consisting of carboxyl groups and hydroxyl groups by radiation or heat, solvent and It contains, The above polymer is an acrylic polymer. The anionic portion of the above onium salt has a sulfonate anion. A composition for forming a resist underlayer film, wherein at least one selected from the group consisting of a fluorine atom and a fluorinated hydrocarbon group is bonded to the carbon atom to which the above-mentioned sulfonic acid anion is bonded.

2. The resist underlayer film forming composition according to claim 1, wherein the polar group is generated in at least the anionic portion of the onium salt by radiation or heat.

3. The resist underlayer film forming composition according to claim 1, wherein the onium salt is a sulfonium salt or an iodonium salt.

4. The resist underlayer film forming composition according to any one of claims 1 to 3, wherein the anionic portion of the onium salt contains a ring structure.

5. The resist underlayer film forming composition according to any one of claims 1 to 3, wherein the resist underlayer film forming composition further comprises a crosslinking agent.

6. The resist underlayer film forming composition according to any one of claims 1 to 3, wherein the polymer has repeating units represented by the following formula (3). 【Chemistry 1】 (In formula (3), R ３ L is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ３ R is a single bond or a divalent linking group. ４ (This refers to a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.)

7. The resist underlayer film forming composition according to claim 6, wherein the content of the repeating unit represented by formula (3) in the total repeating units constituting the polymer is 20 mol% or more and 80 mol% or less.

8. The resist underlayer film forming composition according to any one of claims 1 to 3, wherein the polymer has repeating units represented by the following formula (4) (except in the case of formula (3)). 【Chemistry 2】 (In formula (4), R ５ L is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ４ Ar is a single bond or a divalent linking group. １ (This is a monovalent group having a substituted or unsubstituted aromatic ring with 6 to 20 members.)

9. A step of coating a resist underlayer film formation composition directly or indirectly onto a substrate, A step of coating the resist film-forming composition onto the resist film-forming composition formed by the above resist film-forming composition coating step, A step of exposing the resist film formed by the above resist film forming composition coating step with radiation, At least the process of developing the exposed resist film and Equipped with, The above resist underlayer film forming composition, Polymers and, An onium salt that generates at least one polar group selected from the group consisting of carboxyl groups and hydroxyl groups by radiation or heat, solvent and It contains, The above polymer is an acrylic polymer. The anionic portion of the above onium salt has a sulfonate anion. A method for manufacturing a semiconductor substrate, wherein at least one selected from the group consisting of a fluorine atom and a fluorinated hydrocarbon group is bonded to the carbon atom to which the above-mentioned sulfonate anion is bonded.

10. The method for manufacturing a semiconductor substrate according to claim 9, wherein the onium salt is a sulfonium salt or an iodonium salt.

11. The method for manufacturing a semiconductor substrate according to claim 9, wherein the polymer has repeating units represented by the following formula (3). 【Transformation 3】 (In formula (3), R3 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. L3 is a single bond or a divalent linking group. R4 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.)

12. The method for manufacturing a semiconductor substrate according to claim 11, wherein the content of the repeating unit represented by formula (3) in the total repeating units constituting the polymer is 20 mol% or more and 80 mol% or less.

13. The method for manufacturing a semiconductor substrate according to claim 9, wherein the radiation is extreme ultraviolet light.

14. A method for manufacturing a semiconductor substrate according to any one of claims 9 to 13, wherein in the step of developing the exposed resist film, a portion of the underlying resist film is further developed.

15. A method for manufacturing a semiconductor substrate according to any one of claims 9 to 13, wherein the developer used in the step of developing the exposed resist film is a basic solution.

16. Before the coating process of the composition for forming the resist underlayer film, A method for manufacturing a semiconductor substrate according to any one of claims 9 to 13, further comprising the step of forming a silicon-containing film directly or indirectly on the substrate.

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