Patent Application
20240142876
The present disclosure relates to a method for manufacturing a semiconductor substrate and a composition.
A semiconductor device is produced using, for example, a multilayer resist process in which a resist pattern is formed by exposing and developing a resist film laminated on a substrate with a resist underlayer film, such as an organic underlayer film or a silicon-containing film, being interposed between them. In this process, the resist underlayer film is etched using this resist pattern as a mask, and the substrate is further etched using the obtained resist underlayer film pattern as a mask so that a desired pattern is formed on the semiconductor substrate.
In recent years, highly enhanced integration of semiconductor devices has further advanced, and exposure light to be used tends to have a shorter wavelength, as from a KrF excimer laser beam (248 nm) or an ArF excimer laser beam (193 nm) to an extreme ultraviolet ray (13.5 nm; hereinafter also referred to as “EUV”). Various studies have been conducted on compositions for forming a resist underlayer film in such EUV exposure (see WO 2013/141015 A).
According to an aspect of the present disclosure, a method for manufacturing a semiconductor substrate, includes: directly or indirectly applying a composition for forming a resist underlayer film to a substrate to form a resist under film directly or indirectly on the substrate; applying a composition for forming a resist film to the resist underlayer film to form a resist film on the resist underlayer film;
According to another aspect of the present disclosure, a composition includes: a polymer; an onium salt that is capable of generating at least one polar group selected from the group consisting of a carboxy group and a hydroxy group by radiation or heat; and a solvent.
As used herein, the words “a” and “an” and the like carry the meaning of “one or more.” When an amount, concentration, or other value or parameter is given as a range, and/or its description includes a list of upper and lower values, this is to be understood as specifically disclosing all integers and fractions within the given range, and all ranges formed from any pair of any upper and lower values, regardless of whether subranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, as well as all integers and fractions within the range. As an example, a stated range of 1-10 fully describes and includes the independent subrange 3.4-7.2 as does the following list of values: 1, 4, 6, 10.
While the line width of a resist pattern formed through exposure to extreme ultraviolet rays and development is being miniaturized to a level of 20 nm or less, a resist underlayer film is requested to have pattern rectangularity of securing rectangularity of a resist pattern by inhibiting trailing of a pattern at a bottom part of a resist film.
The present disclosure relates to, in one embodiment, a method for manufacturing a semiconductor substrate, the method including: directly or indirectly applying a composition for forming a resist underlayer film to a substrate; applying a composition for forming a resist film to a resist underlayer film formed by applying the composition for forming a resist underlayer film; exposing the resist film formed by applying the composition for forming a resist film to radiation; and developing at least the exposed resist film, wherein the composition for forming a resist underlayer film includes a polymer (hereinafter, also referred to as a “polymer [A]”), an onium salt that generates at least one polar group selected from the group consisting of a carboxy group and a hydroxy group by radiation or heat (hereinafter, also referred to as an “onium salt [B]”), and a solvent (hereinafter, also referred to as a “solvent [C]”).
In another embodiment, the present disclosure relates to a composition for forming a resist underlayer film, including: a polymer; an onium salt that generates at least one polar group selected from the group consisting of a carboxy group and a hydroxy group by radiation or heat; and a solvent.
According to the method for manufacturing a semiconductor substrate, because of the use of a composition for forming a resist underlayer film, the composition being superior in storage stability and also capable of forming a resist underlayer film having good pattern rectangularity, a semiconductor substrate having a good pattern shape can be efficiently manufactured. The composition for forming a resist underlayer film is superior in storage stability and can form a film superior in pattern rectangularity. Therefore, they can suitably be used for, for example, producing semiconductor devices expected to be further microfabricated in the future.
Hereinafter, a method for manufacturing a semiconductor substrate and a composition for forming a resist underlayer film according to each embodiment of the present disclosure will be described in detail. Combinations of suitable modes in the embodiments are also preferred.
The method for manufacturing a semiconductor substrate includes directly or indirectly applying a composition for forming a resist underlayer film to a substrate (this step is hereinafter also referred to as “application step (I)”); applying a composition for forming a resist film to the resist underlayer film formed by applying the composition for forming a resist underlayer film (this step is hereinafter also referred to as “application step (II)”); exposing the resist film formed by applying the composition for forming a resist film to radiation (this step is hereinafter also referred to as “exposure step”); and developing at least the exposed resist film (this step is hereinafter also referred to as “development step”).
By the method for manufacturing a semiconductor substrate, a resist underlayer film superior in pattern rectangularity can be formed due to the use of a prescribed composition for forming a resist underlayer film in the application step (I), so that a semiconductor substrate having a favorable pattern shape can be manufactured.
The method for manufacturing a semiconductor substrate may further include, as necessary, directly or indirectly forming a silicon-containing film on the substrate (this step is hereinafter also referred to as “silicon-containing film formation step”) before the application step (I).
Hereinafter, the composition for forming a resist underlayer film to be used in the method for manufacturing a semiconductor substrate, and the respective steps in the case of including the silicon-containing film formation step, which is an optional step, will be described.
The composition for forming a resist underlayer film (this composition is hereinafter also simply referred to as “composition”) includes a polymer [A], an onium salt [B], and a solvent [C]. The composition may contain any optional component as long as the effect of the present disclosure is not impaired. The composition for forming a resist underlayer film can have an enhanced storage stability and can form a resist underlayer film superior in pattern rectangularity owing to containing the polymer [A], the onium salt [B], and the solvent [C]. The reason for this is not clear, but can be expected as follows. Since the composition for forming a resist underlayer film contains an onium salt as an acid generator (that is, the onium salt [B]), an acid generated from the onium salt in a resist underlayer film can inhibit acid deficiency at the bottom of a resist film in an exposed portion, enhance solubility in a developer at the bottom of the resist film, and eventually exhibit pattern rectangularity. In addition, since at least one polar group selected from the group consisting of a carboxy group and a hydroxy group of the onium salt [B] is generated by radiation or heat during exposure to light or baking, an unintended reaction during storage can be inhibited, so that the storage stability of the composition for forming a resist underlayer film can be improved. Furthermore, due to the polar group generated by radiation or heat, the onium salt [B] and the polymer [A] electrostatically or chemically interact with each other, so that excessive diffusion of the onium salt [B] into the resist film is inhibited and pattern rectangularity can be exhibited.
As the polymer [A], a publicly known polymer used for forming a resist underlayer film can be suitably employed. The composition may contain one kind or two or more kinds of the polymer [A]. The polymer [A] is preferably an acrylic polymer.
When the polymer [A] is an acrylic polymer, the polymer [A] preferably has a repeating unit represented by formula (1) (this unit is hereinafter also referred to as “repeating unit (1)”).
In the formula (1), R1 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms; and L1 is a single bond or a divalent linking group.
Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R1 include monovalent chain 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.
As used herein, the “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” includes a saturated hydrocarbon group and an unsaturated hydrocarbon group. The “chain hydrocarbon group” means a hydrocarbon group that contains no cyclic structure and is composed only of a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The “alicyclic hydrocarbon group” means a hydrocarbon group that contains only an alicyclic structure as a ring structure and contains no aromatic ring structure, and includes both a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic hydrocarbon group (however, the alicyclic hydrocarbon group is not required to be composed of only an alicyclic structure, and may contain a chain structure as a part thereof). The “aromatic hydrocarbon group” means a hydrocarbon group containing an aromatic ring structure as a ring structure (however, the aromatic hydrocarbon group is not required to be composed of only an aromatic ring structure, and may contain an alicyclic structure or a chain structure as a part thereof).
Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group; alkenyl groups such as an ethenyl group, a propenyl group and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group and a butynyl group.
Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group; cycloalkenyl groups such as a cyclopropenyl group, a cyclopentenyl group, and a cyclohexenyl group; bridged cyclic saturated hydrocarbon groups such as a norbornyl group, an adamantyl group, and a tricyclodecyl group; and bridged cyclic unsaturated hydrocarbon groups such as a norbornenyl group and a tricyclodecenyl group.
Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a tolyl group, a naphthyl group, an anthracenyl group, and a pyrenyl group.
When R1 has a substituent, examples of the substituent include monovalent chain hydrocarbon groups having 1 to 10 carbon atoms, halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, alkoxy groups such as a methoxy group, an ethoxy group, and a propoxy group, alkoxycarbonyl groups such as a methoxycarbonyl group and an ethoxycarbonyl group, alkoxycarbonyloxy groups such as a methoxycarbonyloxy group and an ethoxycarbonyloxy group, acyl groups such as a formyl group, an acetyl group, a propionyl group, and a butyryl group, a cyano group, a nitro group, and a hydroxy group.
Among them, a hydrogen atom or a methyl group is preferable as R1 from the viewpoint of the copolymerizability of a monomer that affords the repeating unit (1).
In the above formula (1), the divalent linking group represented by L1 is preferably a divalent hydrocarbon group, a carbonyl group, an oxygen atom (—O—), an imino group (—NH—), or a combination thereof.
Examples of the divalent hydrocarbon group as L1 include a group obtained by removing one hydrogen atom from the monovalent hydrocarbon group having 1 to 20 carbon atoms as R1.
Among them, 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 is preferable as L1, and 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 is more preferable.
Examples of the repeating unit represented by the formula (1) include repeating units represented by formulas (1-1) to (1-10).
In the above formulas (1-1) to (1-10), R1 has the same definition as that in the above formula (1). Among them, the repeating units represented by the formulas (1-1), (1-5), and (1-9) are preferable.
When the polymer [A] includes the repeating unit (1), the lower limit of the content ratio of the repeating unit (1) containing a sulfonic acid group accounting for among all the repeating units constituting the polymer is preferably 1 mol %, more preferably 5 mol %, still more preferably 10 mol %, and particularly preferably 20 mol %. The upper limit of the content ratio is preferably 100 mol %, more preferably 70 mol %, still more preferably 40 mol %, and particularly preferably 30 mol %. When the content ratio of the repeating unit (1) is set within the above range, pattern rectangularity can be exhibited at a high level. Within the above range, when a basic solution is used as a developer in a step of developing a resist film, a resist underlayer film can be removed together with the resist film.
The polymer [A] preferably has a repeating unit represented by formula (2) (this unit is hereinafter also referred to as “repeating unit (2)”).
In the formula (2), as the substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R2, a group disclosed as the substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R1 in the formula (1) can be suitably employed. A hydrogen atom or a methyl group is preferable as R2 from the viewpoint of the copolymerizability of a monomer that affords the repeating unit (2). When R2 has a substituent, examples of the substituent suitably include a substituent that can be possessed by R1 of the above formula (1).
In the formula (2), as the divalent linking group represented by L2, the group disclosed as the divalent linking group represented by L1 in the formula (1) can be suitably employed. As L2, 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 is a preferable, and 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 is more preferable.
Examples of the repeating unit represented by the formula (2) include repeating units represented by formulas (2-1) to (2-8).
In the above formulas (2-1) to (2-8), R2 has the same definition as that in the above formula (2).
When the polymer [A] has the repeating unit (2), the lower limit of the content ratio of the repeating unit (2) accounting for among all the repeating units constituting the polymer [A] is preferably 10 mol %, more preferably 15 mol %, and still more preferably 20 mol %. The upper limit of the content is preferably 99 mol %, more preferably 90 mol %, and still more preferably 80 mol %.
The polymer [A] preferably has a repeating unit represented by formula (3) (excluding the case of being the formula (2)) (this unit is hereinafter also referred to as “repeating unit (3)”).
In the formula (3), as each of the substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by R3 and R4, a group disclosed as the substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R1 in the formula (1) can be suitably employed. A hydrogen atom or a methyl group is preferable as R3 from the viewpoint of the copolymerizability of a monomer that affords the repeating unit (3). A monovalent chain hydrocarbon group having 1 to 15 carbon atoms is preferable as R4, and a monovalent branched alkyl group having 1 to 10 carbon atoms is more preferable. When R3 or R4 has a substituent, examples of the substituent preferably include a substituent that can be possessed by R1 of the above formula (1).
In the formula (3), as the divalent linking group represented by L3, the group disclosed as the divalent linking group represented by L1 in the formula (1) can be suitably employed. As L3, 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 is a preferable, 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 is more preferable, and a single bond is still more preferable.
Examples of the repeating unit represented by the formula (3) include repeating units represented by formulas (3-1) to (3-18).
In the formulas (3-1) to (3-18), R3 has the same definition as that in the above formula (3).
When the polymer [A] has the repeating unit (3), the lower limit of the content ratio of the repeating unit (3) accounting for among all the repeating units constituting the polymer [A] is preferably 10 mol %, more preferably 15 mol %, and still more preferably 20 mol %. The upper limit of the content is preferably 90 mol %, more preferably 85 mol %, and still more preferably 80 mol %.
The polymer [A] preferably has a repeating unit represented by formula (4) (excluding the cases of being the formulas (1), (2), and (3)) (this unit is hereinafter also referred to as “repeating unit (4)”).
In the present specification, the term “ring members” refers to the number of atoms constituting the ring. For example, a biphenyl ring has 12 ring members, a naphthalene ring has 10 ring members, and a fluorene ring has 13 ring members.
In the formula (4), as the substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R5, a group disclosed as the substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R1 in the formula (1) can be suitably employed. A hydrogen atom or a methyl group is preferable as R5 from the viewpoint of the copolymerizability of a monomer that affords the repeating unit (4). When R5 has a substituent, examples of the substituent suitably include a substituent that can be possessed by R1 of the above formula (1).
In the formula (4), as the divalent linking group represented by L4, the group disclosed as the divalent linking group represented by L1 in the formula (1) can be suitably employed. As L4, 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 is a preferable, 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 is more preferable, and a single bond is still more preferable.
In the above formula (4), examples of the aromatic ring having 6 to 20 ring numbers as Ar1 include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, an indene ring, and a pyrene ring, aromatic heterocyclic rings such as a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, and a triazine ring, or a combination thereof. The aromatic ring of the Ar1 is preferably at least one aromatic hydrocarbon ring selected from the group consisting of a benzene ring, a naphthalene ring, an anthracene ring, a phenalene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, a perylene ring, and a coronene ring, and more preferably a benzene ring, a naphthalene ring, or a pyrene ring.
In the formula (4), suitable examples of the monovalent group having an aromatic ring having 6 to 20 ring members represented by Ar1 include a group obtained by removing one hydrogen atom from the aromatic ring having 6 to 20 ring members in the Ar1.
In the formula (4), the monovalent group having an aromatic ring having 6 to 20 ring members represented by Ar1 may have a substituent. As the substituent in that case, substituents disclosed as examples when R1 in the above formula (1) has a substituent can be suitably employed.
Examples of the repeating unit represented by the formula (4) include repeating units represented by formulas (4-1) to (4-11).
In the formulas (4-1) to (4-11), R5 has the same definition as that in the above formula (4). Among them, the repeating units represented by the formulas (4-1) and (4-9) are preferable.
When the polymer [A] has the repeating unit (4), the lower limit of the content ratio of the repeating unit (4) accounting for among all the repeating units constituting the polymer [A] is preferably 10 mol %, more preferably 20 mol %, and still more preferably 30 mol %. The upper limit of the content is preferably 90 mol %, more preferably 80 mol %, and still more preferably 70 mol %.
The polymer [A] may have a repeating unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure (this unit is hereinafter also referred to as “repeating unit (5)”). Examples of the repeating unit (5) include repeating units represented by formulas (T-1) to (T-10).
In the above formula, RL1 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. RL2 to RL5 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. RL4 and RL5 may be combined with each other and constitute a divalent alicyclic group having 3 to 8 carbon atoms together with the carbon atom to which they are bonded. L2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3.
The divalent alicyclic group having 3 to 8 carbon atoms composed of the RL4 and the RL5 combined together with the carbon atom to which the RL4 and the RL5 are bonded is not particularly limited as long as it is a group formed by removing two hydrogen atoms from the same carbon atom contained in a carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the aforementioned number of carbon atoms. The group may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group, and the polycyclic hydrocarbon group may be either a bridged alicyclic hydrocarbon group or a fused alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. It is to be noted that the fused alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two or more alicyclic rings share a side (a bond between two adjacent carbon atoms).
Among the monocyclic alicyclic hydrocarbon groups, as the saturated hydrocarbon group, a cyclopentanediyl group, a cyclohexanediyl group, a cycloheptanediyl group, a cyclooctanediyl group, and the like are preferable, and as the unsaturated hydrocarbon group, a cyclopentenediyl group, a cyclohexenediyl group, a cycloheptenediyl group, a cyclooctenediyl group, a cyclodecenediyl group, and the like are preferable. As the polycyclic alicyclic hydrocarbon group, bridged alicyclic saturated hydrocarbon groups are preferable, and for example, a bicyclo[2.2.1]heptane-2,2-diyl group (norbornane-2,2-diyl group), a bicyclo[2.2.2]octane-2,2-diyl group, and a tricyclo[3.3.1.13,7]decane-2,2-diyl group (adamantane-2,2-diyl group) are preferable. One or more hydrogen atoms on the alicyclic group may be replaced by a hydroxy group.
Examples of the divalent linking group represented by L2T include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, and a group composed of one or more among these hydrocarbon groups and at least one group among —CO—, —O—, —NH—, and —S.
Among these, a repeating unit containing a lactone structure is preferable as the repeating unit (5).
When the polymer [A] has the repeating unit (5), the lower limit of the content ratio of the repeating unit (5) accounting for among all the repeating units constituting the polymer [A] is preferably 3 mol %, more preferably 8 mol %, and still more preferably 10 mol %. The upper limit of the content is preferably 40 mol %, more preferably 30 mol %, and still more preferably 25 mol %.
The polymer [A] may have a repeating unit containing a heteroatom-containing group (this repeating unit is hereinafter also referred to as “repeating unit (6)”), provided that those corresponding to the repeating units (1) to (5) are excluded. Examples of the heteroatom-containing group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among them, a hydroxy group and a carboxy group are preferable, and a hydroxy group is more preferable.
Examples of the repeating unit (6) include repeating units represented by the following formulas.
In the above formulas, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.
When the polymer [A] has the repeating unit (5), the lower limit of the content ratio of the repeating unit (5) accounting for among all the repeating units constituting the polymer [A] is preferably 5 mol %, more preferably 10 mol %, and still more preferably 15 mol %. The upper limit of the content ratio is preferably 40 mol %, more preferably 30 mol %, and still more preferably 25 mol %.
Other repeating units include repeating units used in polymers of resist compositions such as a repeating unit in which a structure of an onium salt [B] described later is incorporated.
The lower limit of the weight average molecular weight of the polymer [A] is preferably 500, more preferably 1000, still more preferably 1500, and particularly preferably 2000. The upper limit of the molecular weight is preferably 10000, more preferably 9000, still more preferably 8000, and particularly preferably 7000. The weight average molecular weight is measured as described in EXAMPLES.
The lower limit of the content ratio of the polymer [A] in the composition for forming a resist underlayer film is preferably 1% by mass, more preferably 2% by mass, still more preferably 3% by mass, and particularly preferably 4% by mass in the total mass of the polymer [A] and the solvent [C]. The upper limit of the content ratio is preferably 20% by mass, more preferably 15% by mass, still more preferably 12% by mass, and particularly preferably 10% by mass in the total mass of the polymer [A], the onium salt and the solvent [C].
The lower limit of the content ratio of the polymer [A] accounting for among the components other than the solvent [C] in the composition for forming a resist underlayer film is preferably 10% by mass, more preferably 20% by mass, still more preferably 30% by mass, and particularly preferably 40% by mass. The upper limit of the content ratio is preferably 90% by mass, more preferably 80% by mass, and still more preferably 70% by mass.
The polymer [A] can be synthesized by performing radical polymerization, ion polymerization, polycondensation, polyaddition, addition condensation, or the like depending on the type of the monomer. For example, when the polymer [A] is synthesized by radical polymerization, the polymer can be synthesized by polymerizing monomers which will afford respective repeating units using a radical polymerization initiator of the like in an appropriate solvent.
Examples of the radical polymerization initiator include azo 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 (other name: dimethyl 2,2′-azobis(2-methylpropionate)); and peroxide radical initiators, such as benzoyl peroxide, t-butyl hydroperoxide and cumene hydroperoxide. These radical initiators may be used singly, or two or more of them may be used in combination.
As the solvent to be used for the polymerization, the solvent [C] described later can be suitably employed. The solvents to be used for the polymerization may be used singly, or two or more solvents may be used in combination.
The reaction temperature in the polymerization is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.
The onium salt [B] is a compound that has an anion moiety and a cation moiety and generates at least one polar group selected from the group consisting of a carboxy group and a hydroxy group by radiation or heat. Although a polar group may be generated by radiation or heat at one or both of the anion moiety and the cation moiety of the onium salt [B], it is preferable that the polar group is generated by radiation or heat at least the anion moiety. The hydroxy group may be either an alcoholic hydroxy group or a phenolic hydroxy group. The onium salt [B] can also function as a component that generates an acid by the action of heat or radiation. The onium salt [B] may be used singly, or two or more types thereof may be used in combination.
Examples of the onium salt [B] include a sulfonium salt, a tetrahydrothiophenium salt, an iodonium salt, a phosphonium salt, a diazonium salt, and a pyridinium salt. Among them, a sulfonium salt or an iodonium salt is preferable.
The anion moiety of the onium salt [B] preferably has a sulfonate 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 sulfonate anion is bonded. With these configurations, a sufficient amount of a strong acid can be supplied to the bottom portion of a resist film, and pattern rectangularity can be further improved through inhibition of trailing of a pattern.
The carboxy group or hydroxy group as the polar group preferably has a structure protected by a protecting group. Through deprotection by radiation or heat, a carboxy group or a hydroxy group is generated. The protective structure is not particularly limited, and examples thereof include an ester structure in the case of a carboxy group, an acetal structure, an ester structure, and a (silyl) ether structure in the case of an alcoholic hydroxy group, and an ether structure in the case of a phenolic hydroxy group.
The anion moiety of the onium salt [B] preferably contains a ring structure. As the ring structure, a polycyclic structure is preferable, and a norbornane structure is more preferable.
The onium salt [B] preferably has a structure represented by formula (c). It is considered that owing to the onium salt [B] having the following structure, the diffusion length in a resist film of an acid generated during the exposure step of the resist film is further appropriately shortened. As a result, a resist underlayer film superior in pattern rectangularity can be formed.
In the formula (c), Rp1 is a monovalent organic group having 1 to 40 carbon atoms. Rp2 is a divalent linking group. Rp3 and Rp4 are each 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. Rp5 and Rp6 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. np1 is an integer of 0 to 10. np2 is an integer of 0 to 10. np3 is an integer of 1 to 10. When np1 is 2 or more, a plurality of Rp2s may be identical or different. When np2 is 2 or more, a plurality of Rp3s may be identical or different, and a plurality of Rp4s is identical or different. When np3 is 2 or more, a plurality of Rp5s may be identical or different, and a plurality of Rp6s are identical or different. X+ is a monovalent radiation-sensitive onium cation.
The monovalent organic group having 1 to 40 carbon atoms represented by Rp1 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 may either be saturated or unsaturated and linear or branched. Examples of the cyclic structure include cyclic hydrocarbon groups that may be alicyclic, aromatic, or heterocyclic. Among them, the monovalent organic group is preferably a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof. Other examples of the organic group include a group obtained by substituting a part or all of hydrogen atoms contained in a group having a chain structure or a group having a cyclic structure by a substituent and a group containing, between carbon atoms of such a group, CO, CS, O, S, SO2, or NR′ or a combination of two or more of them. R′ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.
Examples of the substituent that substitutes some or all of the hydrogen atoms of the organic group include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, or a group in which a hydrogen atom of these groups has been substituted with a halogen atom; and an oxo group (═O).
Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms and a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.
Examples of the alicyclic hydrocarbon group having 3 to 20 carbon atoms include a monocyclic or polycyclic saturated hydrocarbon group and a monocyclic or polycyclic unsaturated hydrocarbon group. Preferred examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Preferred examples of the polycyclic cycloalkyl group include bridged alicyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that constitute an alicyclic ring and are not adjacent to each other are bonded by a bonding chain containing one or more carbon atoms.
Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include: aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.
Examples of the heterocyclic cyclic hydrocarbon group include a group obtained by removing one hydrogen atom from an aromatic heterocyclic structure and a group obtained by removing one hydrogen atom from an alicyclic heterocyclic structure. A 5-membered aromatic structure having aromaticity due to introducing a heteroatom is also included in the heterocyclic structure. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.
Examples of the aromatic heterocyclic structure include:
Examples of the alicyclic heterocyclic structure include:
Examples of the cyclic structure include a lactone structure, a cyclic carbonate structure, a sultone structure, and a structure containing a cyclic acetal. Examples of such structures include structures represented by formulas (H-1) to (H-11).
In the above formulas, m is an integer of 1 to 3.
Two or more of the structures represented by the above formulas (H-1) to (H-11) may form together a fused ring structure or a spiro structure. Alternatively, any of the structures represented by the above formulas (H-1) to (H-11) and another cyclic structure may form together a fused ring structure or a spiro structure.
Examples of the divalent linking group represented by Rp2 include a carbonyl group, an ether linkage, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group, or a combination thereof. A cyclic structure represented by Rp1 may be present between these groups.
Examples of the monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by Rp3 and Rp4 include alkyl groups having 1 to 20 carbon atoms. Examples of the monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms represented by Rp3 and Rp4 include fluorinated alkyl groups having 1 to 20 carbon atoms. As Rp3 and Rp4, a hydrogen atom, a fluorine atom, and fluorinated alkyl groups are preferable, a fluorine atom and perfluoroalkyl groups are more preferable, and a fluorine atom and a trifluoromethyl group are still more preferable.
Examples of the monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms represented by Rp5 and Rp6 include fluorinated alkyl groups having 1 to 20 carbon atoms. As Rp5 and Rp6, a fluorine atom and fluorinated alkyl groups are preferable, a fluorine atom and perfluoroalkyl groups are more preferable, a fluorine atom and a trifluoromethyl group are still more preferable, and a fluorine atom is particularly preferable.
As np1, integers of 0 to 5 are preferable, integers of 0 to 3 are more preferable, integers of 0 to 2 are still more preferable, and 0 and 1 are particularly preferable.
As np2, integers of 0 to 5 are preferable, integers of 0 to 2 are more preferable, integers of 0 and 1 are still more preferable, and 0 is particularly preferable.
As np3, integers of 1 to 5 are preferable, integers of 1 to 4 are more preferable, integers of 1 to 3 are still more preferable, and 1 and 2 are particularly preferable.
The monovalent radiation-sensitive onium cation represented by X+ is a cation that is decomposed by irradiation with exposure light. In an exposure section, a sulfonic acid is generated from a proton generated through the decomposition of the photolyzable onium cation and a sulfonate anion. Examples of the monovalent radiation-sensitive onium cation represented by X+ include a cation represented by formula (c-a) (hereinafter, also referred to as “cation (c-a)”), a cation represented by formula (c-b) (hereinafter, also referred to as “cation (c-b)”), and a cation represented by formula (c-c) (hereinafter, also referred to as “cation (c-c)”).
In the formula (c-a), RC3, RC4 and RC5 each independently represent 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, —OSO2—RCC1 or —SO2—RCC2, or a ring structure constituted by combining two or more of these groups with each other. RCC1 and RCC2 are each 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 an integer of 0 to 5. When there are pluralities of RC3s to RC5s, RCC1s and RCC2s, the pluralities of RC3s to RC5s, RCC1s and RCC2s each may be identical or different.
In the above formula (c-b), RC6 is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms. c4 is an integer of 0 to 7. When there are a plurality of RC6s, the plurality of RC6s may be identical or different, and the plurality of RC6 may represent a ring structure constituted by combining them with each other. RC7 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. c5 is an integer of 0 to 6. When there are a plurality of RC7s, the plurality of RC7s may be identical or different, and the plurality of RC7s may represent a ring structure constituted by combining them with each other. nc2 is an integer of 0 to 3. RC8 is a single bond or a divalent organic group having 1 to 20 carbon atoms. nc1 is an integer of 0 to 2.
In the formula (c-c), RC9 and RC10 each independently represent 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, —OSO2—RCC3 or —SO2—RCC4, or a ring structure constituted by combining two or more of these groups with each other. RCC3 and RCC4 are each 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 an integer of 0 to 5. When there are pluralities of RC9s, RC10s, RCC3s and RCC4s, the pluralities of RC9s, RC10s, RCC3s and RCC4s each may be identical or different.
Examples of the unsubstituted linear alkyl groups represented by RC3, RC4, RC5, RC6, RC7, RC9, and RC10 include a methyl group, an ethyl group, a n-propyl group, and a n-butyl group.
Examples of the unsubstituted linear alkyl groups represented by RC3, RC4, RC5, RC6, RC7, RC9, and RC10 include an isopropyl group, an isobutyl group, a sec-butyl group, and a t-butyl group.
Examples of the unsubstituted aromatic hydrocarbon groups represented by RC3, RC4, RC5, RC9, and RC10 include:
Examples of the unsubstituted aromatic hydrocarbon groups represented by RC6 and RC7 include a phenyl group, a tolyl group, and a benzyl group.
Examples of the divalent organic group represented by RC8 include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group (a) containing a divalent heteroatom-containing group between two carbon atoms of the foregoing hydrocarbon group or at an end located on a bonding side of the foregoing hydrocarbon group, and a group removing one hydrogen atom from a group obtained by replacing some or all of the hydrogen atoms of the foregoing hydrocarbon group and the group (a) with a monovalent heteroatom-containing group.
Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include groups the same as the groups disclosed as examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by Rp1 of the above formula (c).
Examples of the divalent heteroatom-containing group include —O—, —CO—, —CO—O—, —S—, —CS—, —SO2—, —NR′—, and groups in which two or more of the foregoing are combined. R′ is a hydrogen atom or a monovalent hydrocarbon group.
Examples of the monovalent heteroatom-containing group include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom; a hydroxy group, a carboxy group, a cyano group, an amino group, and a sulfanyl group (—SH).
Examples of the substituent that may substitute a hydrogen atom of the alkyl group or the aromatic hydrocarbon group include halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group. Among them, halogen atoms are preferable, and a fluorine atom is more preferable.
It is preferable that at least one of Rp1 to Rp6 in the formula (c), RC3 to RC5 in the formula (c-a), RC6 to RC7 in the formula (c-b), and RC9 to RC10 in the formula (c-c) has a protective structure that is to be deprotected by radiation or heat to generate a carboxy group or a hydroxy group, and it is more preferable that at least one of Rp1 to Rp6 in the formula (c) has a protective structure that is to be deprotected by radiation or heat to generate a carboxy group or a hydroxy group.
Examples of the onium salt [B] represented by the formula (c) include the compounds represented by formulas (c1) to (c21) (hereinafter also referred to as “compounds (c1) to (c21)”). In the formula, “Bu” represents “n-butyl group”.
The lower limit of the content of the onium salt [B] in the composition for forming a resist underlayer film 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 the polymer [A]. The upper limit of the content is preferably 50 parts by mass, more preferably 45 parts by mass, and still more preferably 40 parts by mass.
The solvent [C] is not particularly limited as long as it can dissolve or disperse the compound [A], the onium salt [B], and optional components contained as necessary.
Examples of the solvent [C] include a hydrocarbon-based solvent, an ester-based solvent, an alcohol-based solvent, a ketone-based solvent, an ether-based solvent, and a nitrogen-containing solvent. The solvent [C] may be used singly or two or more kinds thereof may be used in combination.
Examples of the hydrocarbon-based solvent include aliphatic hydrocarbon-based solvents such as n-pentane, n-hexane, and cyclohexane, and aromatic hydrocarbon-based solvents such as benzene, toluene, and xylene.
Examples of the ester-based solvent include carbonate-based solvents such as diethyl carbonate, acetic acid monoacetate ester-based solvents such as methyl acetate and ethyl acetate, lactone-based solvents such as y-butyrolactone, polyhydric alcohol partial ether carboxylate-based solvents such as diethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, and lactate ester-based solvents such as methyl lactate and ethyl lactate.
Examples of the alcohol-based solvent include monoalcohol-based solvents such as methanol, ethanol, and n-propanol, 4-methyl-2-pentanol, and polyhydric alcohol-based solvents such as ethylene glycol and 1,2-propylene glycol.
Examples of the ketone-based solvent include chain ketone-based solvents such as methyl ethyl ketone and methyl isobutyl ketone, 2-heptanone, and cyclic ketone-based solvents such as cyclohexanone.
Examples of the ether-based solvent include chain ether-based solvents such as n-butyl ether, cyclic ether-based solvents such as tetrahydrofuran, polyhydric alcohol ether-based solvents such as propylene glycol dimethyl ether, and polyhydric alcohol partial ether-based solvents such as diethylene glycol monomethyl ether, propylene glycol monomethyl ether.
Examples of the nitrogen-containing solvent include chain nitrogen-containing solvents such as N,N-dimethylacetamide, and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.
As the solvent [C], an alcohol-based solvent, an ether-based solvent, or an ester-based solvent is preferable, a monoalcohol-based solvent, a polyhydric alcohol partial ether-based solvent, or a polyhydric alcohol partial ether carboxylate-based solvent is more preferable, and 4-methyl-2-pentanol, propylene glycol monomethyl ether, or propylene glycol monomethyl ether acetate is still more preferable.
The lower limit of the content ratio of the solvent [C] in the composition for forming a resist underlayer film is preferably 50% by mass, more preferably 60% by mass, and still more preferably 70% by mass. The upper limit of the content ratio is preferably 99.9% by mass, more preferably 99% by mass, and still more preferably 95% by mass.
The composition for forming a resist underlayer film may include an optional component as long as the effect of the composition is not impaired. Examples of the optional component include a crosslinking agent, an acid diffusion controlling agent, and a surfactant. The optional component may be used singly or two or more kinds thereof may be used in combination.
The type of the crosslinking agent [D] is not particularly limited, and a publicly known crosslinking agent can be freely selected and used. Preferably, at least one selected from polyfunctional (meth)acrylates, cyclic ether-containing compounds, glycolurils, diisocyanates, melamines, benzoguanamines, polynuclear phenols, polyfunctional thiol compounds, polysulfide compounds, and sulfide compounds is preferably used as the crosslinking agent. Thanks to that the composition contains the crosslinking agent [D], electrostatic or chemical interaction (mainly crosslinking or hydrogen bonding) with the onium salt [B] occurs, and excessive diffusion of an acid generated from the onium salt [B] into a resist film can be more efficiently inhibited.
The polyfunctional (meth)acrylate is not particularly limited as long as it is a compound having two or more (meth)acryloyl groups, and examples thereof include a polyfunctional (meth)acrylate obtained by reacting an aliphatic polyhydroxy compound with (meth)acrylic acid, a caprolactone-modified polyfunctional (meth) acrylate, an alkylene oxide-modified polyfunctional (meth)acrylate, a polyfunctional urethane (meth)acrylate obtained by reacting a (meth)acrylate having a hydroxy group with a polyfunctional isocyanate, and a polyfunctional (meth)acrylate having a carboxyl group obtained by reacting a (meth)acrylate having a hydroxy group with an acid anhydride.
Specifically, examples of the polyfunctional (meth)acrylate include 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, ethylene glycol 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.
Examples of the cyclic ether-containing compound include oxiranyl group-containing compounds such as 1,6-hexanediol diglycidyl ether, 3′,4′-epoxycyclohexenylmethyl-3′,4′-epoxycyclohexenecarboxylate, vinylcyclohexene monooxide 1,2-epoxy-4-vinylcyclohexene, and 1,2:8,9 diepoxylimonene; and oxetanyl group-containing compounds such as 3-ethyl-3-hydroxymethyloxetane, 2-ethylhexyloxetane, xylylene bisoxetane, and 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane. These cyclic ether-containing compounds can be used singly, or two or more types thereof may be used in combination.
Examples of the glycolurils include compounds derived from tetramethylolglycoluril, tetramethoxyglycoluril, tetramethoxymethylglycoluril, and tetramethylolglycoluril through methoxymethylation of 1 to 4 methylol groups thereof, or mixtures of the compounds, compounds derived from tetramethylolglycoluril through acyloxymethylation of 1 to 4 methylol groups thereof, and glycidylglycolurils.
Examples of the glycidylglycolurils include 1-glycidylglycoluril, 1,3-diglycidylglycoluril, 1,4-diglycidylglycoluril, 1,6-diglycidylglycoluril, 1,3,4-triglycidylglycoluril, 1,3,4,6-tetraglycidylglycoluril, 1-glycidyl-3a-methylglycoluril, 1-glycidyl -6a-methylglycoluril, 1,3-diglycidyl-3a-methylglycoluril, 1,4-diglycidyl-3a-methylglycoluril, 1,6-diglycidyl-3a-methylglycoluril, 1,3,4-triglycidyl-3a-methylglycoluril, 1,3,4-triglycidyl-6a-methyglycoluril, 1,3,4,6-tetraglycidyl-3a-methylglycoluril, 1-glycidyl-3a, 6a-dimethylglycoluril, 1,3-diglycidyl-3a,6a-dimethylglycoluril, 1,4-diglycidyl-3a,6a-dimethylglycoluril, 1,6-diglycidyl-3a,6a-dimethylglycoluril, 1,3,4-triglycidyl-3a,6a-dimethylglycoluril, 1,3,4,6-tetraglycidyl-3a,6a-dimethylglycoluril, 1-glycidyl-3a,6a-diphenylglycoluril, 1,3-diglycidyl-3a, 6a-diphenylglycoluril, 1,4-diglycidyl-3a,6a-diphenylglycoluril, 1,6-diglycidyl-3a,6a-diphenylglycoluril, 1,3,4-triglycidyl-3a,6a-diphenylglycoluril, and 1,3,4,6-tetraglycidyl-3a,6a-diphenylglycoluril. These glycolurils can be used singly, or two or more types thereof may be used in combination.
Examples of the diisocyanates include 2,3-tolylenediisocyanate, 2,4-tolylenediisocyanate, 3,4-tolylenediisocyanate, 3,5-tolylenediisocyanate, 4,4′-diphenylmethanediisocyanate, hexamethylenediisocyanate, and 1,4-cyclohexanediisocyanate.
Examples of the melamines include melamine, monomethylolmelamine, dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, hexamethylolmelamine, monobutylolmelamine, dibutylolmelamine, tributylolmelamine, tetrabutylolmelamine, pentabutylolmelamine, and hexabthyolmelamine, and alkylated derivatives of these methylolmelamines or butylolmelamines. These melamines can be used singly, or two or more types thereof may be used in combination.
Examples of the benzoguanamines include:
These benzoguanamines can be used singly, or two or more types thereof may be used in combination.
Examples of the polynuclear phenols include binuclear phenols such as 4,4′-biphenyldiol, 4,4′-methylenebisphenol, 4,4′-ethylidenebisphenol, and bisphenol A; trinuclear phenols such as 4,4′,4″-methylidenetrisphenol, 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 singly, or two or more types thereof may be used in combination.
The polyfunctional thiol compound is a compound having two or more mercapto groups in one molecule, and specifically, examples thereof include compounds having two mercapto groups such as 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-l-propanol, dithioerythritol, 2,3-dimercaptosuccinic acid, 1,2-benzenedithiol, 1,2-benzenedimethanethiol, 1,3-benzenedithiol, 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol, 3,4-dimercaptooluene, 4-chloro-1,3-benzenedithiol, 2,4,6-trimethyl-1,3-benzenedimethanethiol, 4,4′-thiodiphenol, 2-hexylamino-4,6-dimercapto-1,3,5-triazine, 2-diethylamino-4,6-dimercapto-1,3,5-triazine, 2-cyclohexylamino-4,6-dimercapto-1,3,5-triazine, 2-di-n-butylamino-4,6-dimercapto-1,3,5-triazine, ethylene glycol bis(3-mercaptopropionate), butanediol bisthioglycolate, ethylene glycol bisthioglycolate, 2,5-dimercapto-1,3,4-thiadiazole, 2,2′-(ethylenedithio)diethanethiol, and 2,2-bis(2-hydroxy-3-mercaptopropoxyphenylpropane); compounds having three mercapto groups such as 1,2,6-hexanetrioltrithioglycolate, 1,3,5-trithiocyanuric acid, trimethylolpropane tris(3-mercaptopropionate), and trimethylolpropane tristhioglycolate; and compounds having 4 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 singly, or two or more types thereof may be used in combination.
When the composition for forming a resist underlayer film contains the crosslinking agent [D], the lower limit of the content of the crosslinking agent [D] 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 the polymer [A]. The upper limit of the content is preferably 60 parts by mass, more preferably 50 parts by mass, and still more preferably 40 parts by mass.
The acid diffusion controlling agent [E] captures an acid and a cation. The acid diffusion controlling agent [E] may be used singly, or two or more types thereof may be used in combination.
Acid diffusion controlling agents [E] are classified into compounds having radiation reactivity and compounds having no radiation reactivity.
As the compounds having no radiation reactivity, basic compounds are preferable. Examples of the basic compounds include hydroxide compounds, carboxylate compounds, amine compounds, imine compounds, and amide compounds. More specific 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 hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, nitrogen-containing compounds having a carbamate group, amide compounds, and imide compounds. Among these, nitrogen-containing compounds having a carbamate group are preferable.
Further, the basic compounds may be Troger's bases; hindered amines such as diazabicycloundecene (DBU) and diazabicyclononene (DBM); and ionic quenchers such as tetrabutylammonium hydroxide (TBAH) and tetrabutylammonium lactate.
Examples of the 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, and tetraethylenepentamine.
Examples of the secondary aliphatic amine 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.
Examples of the tertiary aliphatic amine 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′-tetramethylmethylethylenediamine, N,N,N′,N′-tetramethylethylenediamine, and N,N,N′,N′-tetramethyltetraethylenepentamine.
Examples of the aromatic amine and heterocyclic amine 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-pyrroline; pyrrolidine derivatives such as pyrrolidine, N-methylpyrrolidine, pyrrolidinone, and N-methylpyrrolidone; imidazoline derivatives; imidazolidine derivatives; pyridine derivatives such as 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-pyrrolidinopyridine, 2-(1-ethylpropyl)pyridine, aminopyridine, and dimethylaminopyridine; pyridazine derivatives; pyrimidine derivatives; pyrazine derivatives; pyrazoline derivatives; pyrazolidine derivatives; piperidine derivatives; piperazine isoindole derivatives; 1H-indazole derivatives; indoline derivatives; quinoline derivatives such as quinoline and 3-quinolinecarbonitrile; isoquinoline derivatives; cinnoline derivatives; quinazoline derivatives; quinoxaline derivatives; phthalazine derivatives; purine derivatives; 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.
Examples of the nitrogen-containing compound having a carboxy group include aminobenzoic acid; indolecarboxylic acid; and amino acid derivatives such as nicotinic acid, alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine, methionine, phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic acid, and methoxyalanine.
Examples of the nitrogen-containing compound having a sulfonyl group include 3-pyridinesulfonic acid and pyridinium p-toluenesulfonate.
Examples of the nitrogen-containing compound having a hydroxy group, the nitrogen-containing compound having a hydroxyphenyl group, and the alcoholic nitrogen-containing compound 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-hydroxyethyl)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-hydroxyjulolidine, 3-quinuclidinol, 3-tropanol, 1-methyl-2-pyrrolidine ethanol, 1-aziridine ethanol, N-(2-hydroxyethyl)phthalimide, and N-(2-hydroxyethyl)isonicotinamide.
Examples of the nitrogen-containing compound 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-l-butanol, (R)-(+)-2-(tert-butoxycarbonylamino)-3-phenylpropanol, (S)-(−)-2-(tert-butoxycarbonylamino)-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)-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-butoxycarbonyl)ethylenediamine, N-(tert-butoxycarbonyl)-D-glucosamine, 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-methionine, 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-(tert-butoxycarbonyl)-S-trityl-L-cysteine, Nα-(tert-butoxycarbonyl)-L-tryptophan, N-(tert-butoxycarbonyl)-L-tyrosine, N-(tert-butoxycarbonyl)-L-methyl ester, N-(tert-butoxycarbonyl)-L-valine, N-(tert-butoxycarbonyl)-tyrosine, 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-butyl carbamate, tert-butyl carbazate, tert-butyl N-(benzyloxy) carbamate, tert-butyl 4-benzyl-1-piperazinecarboxylate, tert-butyl (1S,4S)-(−)-2,5-diazabicyclo[2.2.1]heptane-2-carboxylate, tert-butyl N-(2,3-dihydroxypropyl)carbamate, tert-butyl (S)-(−)-4-formyl-2,2-dimethyl-3-oxazolidinecarboxylate, tert-butyl [R-(R*,S*)]-N-[2-hydroxy-2-(3-hydroxyphenyl)-1-methylethyl]carbamate, tert-butyl 4-oxo-1-piperidinecarboxylate, tert-butyl 1-pyrrolecarboxylate, tert-butyl 1-pyrrolidinecarboxylate, and tert-butyl (tetrahydro-2-oxo-3-furanyl)carbamate.
Examples of the amide compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, and 1-cyclohexylpyrrolidone.
Examples of the imide compound include phthalimide, succinimide, and maleimide.
In addition, the compounds having radiation reactivity are classified into a compound that is degraded by radiation to lose acid diffusion controllability (radiation-degradable compound) and a compound that is generated by radiation to acquire acid diffusion controllability (radiation-generatable compound).
As the radiation-degradable compound, sulfonic acid salts and carboxylic acid salts each containing a radiation-degradable cation are preferred. As the sulfonic acid in the sulfonic acid salt, a weak acid is preferable, and a sulfonic acid that has a hydrocarbon group having 1 to 20 carbon atoms and containing no fluorine is more preferable. Examples of such a sulfonic acid include sulfonic acids such as alkyl sulfonic acids, benzene sulfonic acid, and 10-camphor sulfonic acid. As the carboxylic acid in the carboxylic acid salt, a weak acid is preferable, and a carboxylic acid having 1 to 20 carbon atoms is more preferable. Examples of such a carboxylic acid include carboxylic acids such as formic acid, acetic acid, propionic acid, tartaric acid, succinic acid, cyclohexylcarboxylic acid, benzoic acid, and salicylic acid. As the radiation-degradable cation in the carboxylic acid salt of the radiation-degradable cation, an onium cation is preferable, and examples of the onium cation include an iodonium cation and a sulfonium cation.
As the radiation-generatable compound, a compound that generates a base through exposure to light (radiation-sensitive base generating agent) is preferable, and a nitrogen-containing organic compound that generates an amino group is more preferable.
Examples of the radiation-sensitive base generating agent include the compounds described in JP-A-4-151156, JP-A-4-162040, JP-A-5-197148, JP-A-5-5995, JP-A-6-194834, JP-A-8-146608, JP-A-10 -83079, and European patent No. 622682.
Examples of the radiation-sensitive base generating agent include a compound containing a carbamate group (urethane linkage), a compound containing an acyloxyimino group, an ionic compound (anion-cation complex), and a compound containing a carbamoyloxyimino group, and a compound containing a carbamate group (urethane linkage), a compound containing an acyloxyimino group, and an ionic compound (anion-cation complex) are preferable.
Furthermore, as the radiation-sensitive base generating agent, a compound having a ring structure in the molecule is preferable. Examples of the ring structure include benzene, naphthalene, anthracene, xanthone, thioxanthone, anthraquinone, and fluorene.
Examples of the radiation-sensitive base generating agent include 2-nitrobenzylcarbamate, 2,5-dinitrobenzylcyclohexylcarbamate, N-cyclohexyl-4-methylphenylsulfonamide, and 1,1-dimethyl-2-phenylethyl-N-isopropylcarbamate.
When the composition for forming a resist underlayer film contains the acid diffusion controlling agent [E], the lower limit of the content of the acid diffusion controlling agent [E] is preferably 0.1 parts by mass, more preferably 1 part by mass, and still more preferably 3 parts by mass per 100 parts by mass of the polymer [A]. The upper limit of the content is preferably 40 parts by mass, more preferably 30 parts by mass, and still more preferably 20 parts by mass.
The composition for forming a resist underlayer film can be prepared by mixing the polymer [A], the onium salt [B], the solvent [C] and, as necessary, an optional component in a prescribed ratio and preferably filtering the resulting mixture through a membrane filter having a pore size of 0.5 μm or less, or the like.
In this step performed before the application step (I), a silicon-containing film is formed directly or indirectly on a substrate.
Examples of the substrate include metallic or semimetallic substrates such as a silicon substrate, an aluminum substrate, a nickel substrate, a chromium substrate, a molybdenum substrate, a tungsten substrate, a copper substrate, a tantalum substrate, and a titanium substrate. Among them, a silicon substrate is preferred. The substrate may be a substrate having a silicon nitride film, an alumina film, a silicon dioxide film, a tantalum nitride film, or a titanium nitride film formed thereon.
The silicon-containing film can be formed by, for example, application, chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like of a composition for forming a silicon-containing film. Examples of a method for forming a silicon-containing film by application of a composition for forming a silicon-containing film include a method in which a coating film formed by applying a composition for forming a silicon-containing film directly or indirectly to the substrate is cured by exposure and/or heating. As a commercially available product of the composition for forming a silicon-containing film, for example, “NFC SOG01”, “NFC SOG04”, or “NFC SOG080” (all manufactured by JSR Corporation) can be used. By chemical vapor deposition (CVD) or atomic layer deposition (ALD), a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or an amorphous silicon film can be formed.
Examples of the radiation to be used for the exposure include electromagnetic waves such as visible rays, ultraviolet rays, far ultraviolet rays, X-rays, and γ-rays and corpuscular rays such as electron beam, molecular beams, and ion beams.
The lower limit of the temperature in heating the coating film is preferably 90° C., more preferably 150° C., and still more preferably 200° C. The upper limit of the temperature is preferably 550° C., more preferably 450° C., and still more preferably 300° C.
The lower limit of the average thickness of the silicon-containing film is preferably 1 nm, more preferably 10 nm, and still more preferably 20 nm. The upper limit is preferably 20,000 nm, more preferably 1,000 nm, and still more preferably 100 nm. The average thickness of the silicon-containing film can be measured in the same manner as for the average thickness of the resist underlayer film.
Examples of a case where the silicon-containing film is formed indirectly on the substrate include a case where the silicon-containing film is formed on a low dielectric insulating film or an organic underlayer film formed on the substrate.
In this step, a composition for forming a resist underlayer film is applied to the silicon-containing film formed on the substrate. The method of the application of the composition for forming a resist underlayer film is not particularly limited, and the application can be performed by an appropriate method such as spin coating, cast coating, or roll coating. As a result, a coating film is formed, and volatilization of the solvent [C] or the like occurs, so that a resist underlayer film is formed.
When the composition for forming a resist underlayer film is applied directly to the substrate, the silicon-containing film formation step may be omitted.
Next, the coating film formed by the application is heated. The formation of the resist underlayer film is promoted by heating the coating film. More specifically, volatilization or the like of the solvent [C] is promoted by heating the coating film.
The heating of the coating film may be performed either in the air atmosphere or in a nitrogen atmosphere. The lower limit of the heating temperature is preferably 100° C., more preferably 150° C., and still more preferably 200° C. The upper limit of the heating temperature is preferably 400° C., more preferably 350° C., and still more preferably 280° C. The lower limit of the heating time is preferably 15 seconds, and more preferably 30 seconds. The upper limit of the time is preferably 1,200 seconds, and more preferably 600 seconds.
The lower limit of an average thickness of the resist underlayer film to be formed is preferably 0.5 nm, more preferably 1 nm, and still more preferably 2 nm. The upper limit of the average thickness is 100 nm, preferably 50 nm, more preferably 20 nm, still more preferably 10 nm. The average thickness is measured as described in Examples.
In this step, a composition for forming a resist film is formed on the resist underlayer film formed by the step of applying a composition for forming a resist underlayer film. The method of applying the composition for forming a resist film is not particularly limited, and examples thereof include a spin coating method.
Describing this step more in detail, for example, a resist composition is applied such that a resist film formed comes to have a prescribed thickness, and then prebaking (hereinafter also referred to as “PB”) is performed to volatilize the solvent in the coating film. As a result, a resist film is formed.
The PB temperature and the PB time may be appropriately determined according to the type and the like of the composition for forming a resist film to be 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.
Examples of the composition for forming a resist film to be used in this step include a positive or negative chemically amplified resist composition containing a radiation-sensitive acid generating agent, a positive resist composition containing an alkali-soluble resin and a quinonediazide-based photosensitizer, a negative resist composition containing an alkali-soluble resin and a crosslinking agent, and a metal-containing resist composition containing a metal such as tin or zirconium.
In this step, a resist film formed in the step of applying a composition for forming a resist film is exposed to radiation.
Radiation to be used for the exposure can be appropriately selected according to the type or the like of the composition for forming a resist film to be used. Examples thereof include electromagnetic rays such as visible rays, ultraviolet rays, far-ultraviolet, X-rays, and γ-rays and corpuscular rays such as electron beam, molecular beams, and ion beams. Among these, far-ultraviolet rays are preferable, and 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 rays (wavelength: 13.5 nm, etc., also referred to as “EUV”) are more preferred, and ArF excimer laser light or EUV is even more preferred. Further, the exposure conditions can be determined as appropriate depending on the type of resist film forming composition used.
In this step, post exposure baking (hereinafter, also referred to as “PEB”) can be performed after the exposure in order to improve the resist film performance such as resolution, pattern profile, and developability. The PEB temperature and the PEB time may be appropriately determined according to the type and the like of the composition for forming a resist film to be 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.
In this step, the exposed resist film is developed. At this time, a part of the resist underlayer film may also be developed. Examples of the developer to be used for the development include an aqueous alkaline solution (alkaline developer) and an organic solvent-containing solution (organic solvent developer).
The basic solution for the alkali development is not particularly limited, and a publicly known basic solution can be used. Examples of the basic solution for the alkali development include, in the alkaline development, an alkaline aqueous solution obtained by dissolving at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia water, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethyl ammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among them, the aqueous TMAH solution is preferable, and a 2.38% by mass aqueous TMAH solution is more preferable.
Examples of the organic solvent developer in the case of performing organic solvent development include the same as those disclosed as the examples of the solvent [C] described above. As the organic solvent developer, an ester-based solvent, an ether-based solvent, an alcohol-based solvent, a ketone-based solvent and/or a hydrocarbon-based solvent is preferable, a ketone-based solvent is more preferable, and 2-heptanone is particularly preferable.
In this step, washing and/or drying may be performed after the development.
In this step, etching is performed using the resist pattern (and the resist underlayer film pattern) as a mask. The number of times of the etching may be once. Alternatively, etching may be performed a plurality of times, that is, etching may be sequentially performed using a pattern obtained by etching as a mask. From the viewpoint of obtaining a pattern having a favorable shape, etching is preferably performed a plurality of times. When performed a plurality of times, etching is performed to the silicon-containing film, and the substrate sequentially in order. Examples of an etching method include dry etching and wet etching. Dry etching is preferable from the viewpoint of achieving a favorable shape of the pattern of the substrate. In the dry etching, for example, gas plasma such as oxygen plasma is used. As a result of the etching, a semiconductor substrate having a prescribed pattern is obtained.
The dry etching can be performed using, for example, a publicly known dry etching apparatus. The etching gas used for dry etching can be appropriately selected according to the elemental composition of the film to be etched, and for example, fluorine-based gases such as CHF3, CF4, C2F6, C3F8, and SF6, chlorine-based gases such as Cl2 and BCl3, oxygen-based gases such as O2, O3, and H2O, reducing gases such as H2, NH3, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H4, C3H6, C3H8, HF, HI, HBr, HCl, NO, and BCl3, and inert gases such as He, N2 and Ar are used. These gases can also be mixed and used. When the substrate is etched using the pattern of the resist underlayer film as a mask, a fluorine-based gas is usually used.
When the silicon-containing film remains on the substrate or the like after the substrate pattern formation, the silicon-containing film can be removed by performing a removal step described later.
The composition for forming a resist underlayer film contains the polymer [A], the acid generating agent [B], and the solvent [C]. As such a composition for forming a resist underlayer film, the composition for forming a resist underlayer film to be used in the above-described method for manufacturing a semiconductor substrate can be suitably employed.
Hereinbelow, the present invention will specifically be described on the basis of examples, but is not limited to these examples.
The Mw of a polymer (x-1) was measured by gel permeation chromatography (detector: differential refractometer) with monodisperse polystyrene standards using GPC columns (“G2000HXL”×2 and “G3000HXL”×1) manufactured by Tosoh Corporation under the following analysis conditions: flow rate: 1.0 mL/min; elution solvent: tetrahydrofuran; column temperature: 40° C.
The average thickness of a resist underlayer film was determined as a value obtained by measuring the film thickness at arbitrary nine points at intervals of 5 cm including the center of the resist underlayer film using a spectroscopic ellipsometer (“M2000D” available from J. A. WOOLLAM Co.) and calculating the average value of the film thicknesses.
The polymers represented by formulas (A-1) and (A-2) (hereinafter also referred to as “polymers (A-1) and (A-2)”) were each synthesized by the following procedure.
In the above formulas (A-1) to (A-2), the number attached to each repeating unit indicates the content ratio (mol %) of the repeating unit.
4-Acetoxystyrene (36 g) and ethylhexyl methacrylate (64 g) were dissolved in 130 g of 1-methoxy-3-propanol, and 10 g of dimethyl 2,2′-azobis(2-methylpropionate) was added to prepare a monomer solution. In a nitrogen atmosphere, 70 g of 1-methoxy-3-propanol was placed in a reaction vessel and heated to 80° C., and the monomer solution was added dropwise over 3 hours with stirring. A polymerization reaction was performed for 6 hours with the start of the dropwise addition regarded as the start time of the polymerization reaction, and then the resulting mixture was cooled to 30° C. or lower. Methanol (180 g), triethylamine (48.1 g) and water (8.6 g) were added to the reaction solution, and the resulting mixture was heated to 70° C., reacted with stirring for 6 hours, and then cooled to 30° C. or lower. Methyl isobutyl ketone (300 g) and 5% oxalic acid water (1000 g) were added thereto, and the resulting mixture was subjected to liquid-liquid separation extraction, and then the resulting organic phase was charged into hexane to perform reprecipitation. Following removal of the supernatant by decantation, 300 g of propylene glycol monomethyl ether acetate was added, and the resulting mixture was concentrated under reduced pressure, affording a propylene glycol monomethyl ether acetate solution of a polymer (A-1). The Mw of the polymer (A-1) was 3,600.
1-Ethylcyclopentyl methacrylate (43 g), 3-hydroxytricyclo(3.3.1.13,7)decan-1-yl methacrylate (33 g), 2-oxotetrahydrofuran-3-yl methacrylate (24 g), and dimethyl 2,2′-azobis(2-methylpropionate) (16.2 g) were added to prepare a monomer solution. In a nitrogen atmosphere, 300 g of methyl isobutyl ketone was placed in a reaction vessel and heated to 80° C., and the monomer solution was added dropwise over 3 hours with stirring. A polymerization reaction was performed for 6 hours with the start of the dropwise addition regarded as the start time of the polymerization reaction, and then the resulting mixture was cooled to 30° C. or lower. To the resulting reaction solution was added 300 g of propylene glycol monomethyl ether acetate, and methyl isobutyl ketone was removed by concentration under reduced pressure, affording a propylene glycol monomethyl ether acetate solution of a polymer (A-2). The Mw of the polymer (A-2) was 6,600.
The polymers [A], the onium salts [B], the solvents [C], and the crosslinking agents [D] used for the preparation of compositions are shown below.
In a mixed solvent of 1100 parts by mass of (C-1) and 200 parts by mass of (C-2) as the solvent [C] were dissolved 100 parts by mass of (A-1) as the polymer [A], 30 parts by mass of (B-1) as the onium salt [B], and 30 parts by mass of (D-1) as the crosslinking agent [D]. The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter having a pore size of 0.45 μm to prepare a composition (J-1).
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 of the types and contents shown in g Table 1 were used.
Using the compositions prepared as described above, the storage stability and the resist pattern rectangularity were evaluated by the following methods. The evaluation results are shown in Table 2.
Each of the compositions prepared as described above was applied to a 12-inch silicon wafer by a spin coating method using a spin coater (“CLEAN TRACK ACT12” available from Tokyo Electron Limited) at 1,500 rpm for 30 seconds, and the coating film obtained was heated at 90° C. for 60 seconds, thereby forming a resist underlayer film. Where the resist underlayer film obtained in the case of the composition for forming a resist underlayer film of the day of the preparation (T=0) was referred to as “resist underlayer film (a0)”, the resist underlayer film obtained in the case of the composition for forming a resist underlayer film prepared above and stored at 60° C. for 2 days (T=2) was referred to as “resist underlayer film (a1)”, the average thickness of the resist underlayer film (a0) was denoted by T0, and the average thickness of the resist underlayer film (al) was denoted by T1, the film thickness change rate (%) was determined by the following formula and used as an index 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 was evaluated as “B” (poor) when the film thickness change rate was 10% or more.
A resist composition for EUV exposure (R-1) was obtained by mixing 100 parts by mass of a polymer having a repeating unit (1) derived from 4-hydroxystyrene, a repeating unit (2) derived from styrene, and a repeating unit (3) derived from 4-t-butoxystyrene (content ratio of each structural unit: (1)/(2)/(3)=65/5/30 (mol %)), 1.0 parts by mass of triphenylsulfonium trifluoromethanesulfonate as a radiation-sensitive acid generating agent, and 4,400 parts by mass of ethyl lactate and 1,900 parts by mass of propylene glycol monomethyl ether acetate each as a solvent, and filtering the obtained solution through a filter having a pore size of 0.2 μm.
A material for forming an organic underlayer film (“HM8006”, available from JSR Corporation) was applied on a 12-inch silicon wafer by spin-coating using a spin-coater (“CLEAN TRACK ACT12”, available from Tokyo Electron Ltd.), and thereafter heating was conducted at 250° C. for 60 sec to form an organic underlayer film having an average thickness of 100 nm. To the organic underlayer film was applied a composition for forming a silicon-containing film (“NFC SOG080” manufactured by JSR Corporation), heated at 220° C. for 60 sec, and then cooled at 23° C. for 30 sec. Thus, a silicon-containing film having an average thickness of 20 nm was formed. To the silicon-containing film formed as described above was applied the composition for forming a resist underlayer film prepared above, heated at 250° C. for 60 sec, and then cooled at 23° C. for 30 sec. Thus, a resist underlayer film having an average thickness of 5 nm was formed. To the resist underlayer film formed as described above was applied a resist composition for EUV exposure (R-1), heated at 130° C. for 60 sec, and then cooled at 23° C. for 30 sec. Thus, a resist film having an average thickness of 50 nm was formed. Next, the resist film was irradiated with extreme ultraviolet rays using an EUV scanner (“TWINSCAN NXE:3300B”, available from ASML Co. (NA=0.3; Sigma=0.9; quadrupole illumination, with a 1:1 line and space mask having a line width of 16 nm in terms of a dimension on wafer)). After the irradiation with the extreme ultraviolet rays, the substrate was heated at 110° C. for 60 sec, followed by cooling at 23° C. for 60 sec. Thereafter, development was performed by a paddle method using a 2.38% by mass aqueous tetramethylammonium hydroxide solution (20° C. to 25° C.), followed by washing with water and drying, thereby affording a substrate for evaluation having a resist pattern formed thereon. A scanning electron microscope (“SU8220” available from Hitachi High-Technologies Corporation) was used for length measurement and observation of the resist pattern of the substrate for evaluation. The pattern rectangularity was evaluated as “A” (good) when the cross-sectional shape of the pattern was rectangular, “B” (slightly good) when trailing was present in the cross section of the pattern, and “C” (bad) when a residue (defect) was present in the pattern.
As can be seen from the results in Table 2, the compositions for forming a resist underlayer film of Examples had good storage stability. The resist underlayer films formed from the compositions for forming a resist underlayer film of Examples were superior in pattern rectangularity to the resist underlayer films formed from the compositions for forming a resist underlayer film of Comparative Examples.
By the method for manufacturing a semiconductor substrate of the present disclosure, it is possible to efficiently manufacture a semiconductor substrate because of using a composition for forming a resist underlayer film, the composition being superior in storage stability and capable of forming a resist underlayer film having superior pattern rectangularity. The composition for forming a resist underlayer film of the present disclosure can afford good storage stability, and can form a film superior in pattern rectangularity. Therefore, they can suitably be used for, for example, producing semiconductor devices expected to be further microfabricated in the future.
Obviously, numerous modifications and variations of the present invention(s) are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention(s) may be practiced otherwise than as specifically described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-095000 | Jun 2021 | JP | national |
The present application is a continuation-in-part application of International Patent Application No. PCT/JP2022/021673 filed May 27, 2022, which claims priority to Japanese Patent Application No. 2021-095000 filed Jun. 7, 2021. The contents of these applications are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP22/21673 | May 2022 | US |
| Child | 18528951 | US |
