Patent Application
20240201592
The present invention relates to a resist underlayer film-forming composition that exhibits an excellent embedding property, favorable dry etching rate ratio and optical constant, and can form a resist underlayer film exhibiting a good coatahility even to a so-called uneven substrate and having a planarity and superior hardness; a resist underlayer film formed from the resist underlayer film-forming composition; and a method of producing a semiconductor device.
In recent years, resist underlayer film materials for multi-layer resist processes have been required to function as an anti-reflective coating particularly against exposure light of short wavelength, to have an appropriate optical constant, and to exhibit an etching resistance during substrate processing. Thus, a proposal has been made to use a polymer having a repeating unit containing a benzene ring (Patent Document 1).
Patent Document 2 proposes the use of a polymer produced from an aromatic ring and an aldehyde compound. However, the polymer is not necessarily satisfactory from the viewpoint of optical constant.
Patent Document 1: JP 2004-354554 A
Patent Document 2: JP 2019-044022 A
There has been known a lithographic process wherein at least two resist underlayer films are formed, and the resist underlayer films are used as mask materials, in order to achieve a decrease in thickness of a resist layer required in association with the formation of a finer resist pattern. This process involves formation of at least one organic film (lower-layer organic film) and at least one inorganic underlayer film on a semiconductor substrate; patterning of the inorganic underlayer film by using, as a mask, a resist pattern formed on an upper-layer resist film; and patterning of the lower-layer organic film by using the pattern as a mask. This process can form a pattern having a high aspect ratio. The materials for forming the aforementioned at least two layers are, for example, a combination of an organic resin (e.g., acrylic resin or novolac resin) and an inorganic material (e.g., silicon resin (e.g., organopolysiloxane) or an inorganic silicon compound (e.g., SiON or SiO2)). In recent years, a double patterning technique (including two lithographic steps and two etching steps) has also been widely used for obtaining one pattern, wherein the aforementioned multi-layer process is used in each step. In this case, the organic film formed after formation of the first pattern is required to have a property of flattening the step.
However, a so-called uneven substrate (i.e., a resist pattern formed on a to-be-processed substrate has a difference in level or in denseness) poses problems in that the substrate is insufficiently coated with a resist underlayer film-forming composition, and a flat film is difficult to be formed due to a large difference in film thickness after embedding.
The present invention has been made for solving the aforementioned problems, and an object of the present invention is to provide a resist underlayer film-forming composition that exhibits a high etching resistance, favorable dry etching rate ratio and optical constant, and can form a film exhibiting a good coatability even to a so-called uneven substrate, providing a small difference in film thickness after embedding, and having a planarity and superior hardness. Another object of the present invention is to provide a resist underlayer film formed from the resist underlayer film-forming composition, and a method of producing a semiconductor device.
The present invention encompasses the followings.
1. A resist underlayer film-forming composition comprising a polymer having at least one repeating unit of the following Formula (1), (2), (3), or (4), and a solvent:
(in Formulae (1) to (4), Ar1 and Ar2 are each independently a benzene ring or naphthalene ring substitutable with R1 or R2; R1 and R2 are each a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxyl group, a C1-10 alkyl group, a C2-10 alkenyl group, or any combination of these possibly containing an ether bond, a ketone bond, or an ester bond; R3 is a tetravalent C1-2 organic group; R4 is a C1-3 alkyl group, a C2-3 alkenyl group, or a C2-3 alkynyl group; and n1 and n2 are each an integer of 1 to 3 when Ar1 and Ar2 are each a benzene ring, or an integer of 1 to 5 when Ar1 and Ar2 are each a naphthalene ring; in Formulae (1) and (2), R5 is a C2-10 alkyl group; and in Formulae (3) and (4), X is a single bond, a saturated or unsaturated linear or cyclic organic group having a carbon atom number of 1 to 30 and possibly containing a nitrogen atom, or a C6-30 arylene group).
2. The resist underlayer film-forming composition according to 1 above, wherein, in Formulae (1) to (4), Ar1 and Ar2 are each a benzene ring.
3. The resist underlayer film-forming composition according to 1 or 2 above, wherein, in Formulae (1) to (4), R1 and R2 are each a hydrogen atom.
4. The resist underlayer film-forming composition according to any one of 1 to 3 above, wherein the composition further comprises a crosslinking agent.
5. The resist underlaver film-forming composition according to any one of 1 to 4 above, wherein the composition further comprises an acid and/or an acid generator.
6. The resist underlaver film-forming composition according to any one of 1 to 5 above, wherein the solvent is a solvent having a boiling point of 160° C. or higher.
7. A resist underlayer film characterized by being a baked product of a coating film formed from the resist underlayer film-forming composition according to any one of 1 to 6 above.
8. A method of producing a semiconductor device comprising a step of forming, on a semiconductor substrate, a resist underlayer film from the resist underlayer film-forming composition according to any one of 1 to 6 above; a step of forming a resist film on the formed resist underlayer film; a step of irradiating the formed resist film with light or electron beams, and developing the resist film, to thereby form a resist pattern; a step of etching the resist underlayer film with the formed resist pattern, to thereby pattern the resist underlayer film; and a step of processing the semiconductor substrate with the patterned resist underlaver film.
The resist underlayer film-forming composition of the present invention exhibits a high etching resistance, favorable dry etching rate ratio and optical constant, and the resist underlayer film formed from the composition exhibits a good coatability even to a so-called uneven substrate, provides a small difference in film thickness after embedding, and has a planarity and superior hardness. Thus, the resist un aver film enables finer substrate processing.
In particular, the resist underlayer film-forming composition of the present invention is effective for a lithographic process wherein at least two resist underlayer films are formed for the purpose of decreasing the thickness of a resist film, and the resist underlayer films are used as etching masks.
The resist underlayer film-forming composition of the present invention contains a polymer having at least one repeating unit of the following Formula (1), (2), (3), or (4), and a solvent:
(in Formulae (1) to (4), Ar1 and Ar2 are each independently a benzene ring or naphthalene ring substitutable with R1 or R2; R1 and R2 are each a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxyl group, a C1-10 alkyl group, a C2-10 alkenyl group, or any combination of these possibly containing an ether bond, a ketone bond, or an ester bond; R3 is a tetravalent C1-2 organic group; R4 is a C1-3 alkyl group, a C2-3 alkenyl group, or a C2-3 alkynyl group; and n1 and n 2 are each an integer of 1 to 3 when Ar1 and Ar2 are each a benzene ring, or an integer of 1 to 5 when Ar1 and Ar2 are each a naphthalene ring; in Formulae (1) and (2), R5 is a C2-10 alkyl group; and in Formulae (3) and (4), X is a single bond, a saturated or unsaturated linear or cyclic organic group having a carbon atom number of 1 to 30 and possibly containing a nitrogen atom, or a C6-30 arylene group).
In Formulae (1) to (4), Ar1 and Ar2 are each independently a benzene ring or naphthalene ring substitutable with R1 or R2; R1 and R2 are each a hydrogen atom, a halogen atom, a nitro group, an amino group, a hydroxyl group, a C1-10 alkyl group, a C2-10 alkenyl group, or any combination of these possibly containing an ether bond, a ketone bond, or an ester bond; R3 is a tetravalent C1-2 organic group; R4 is a C1-3 alkyl group, a C2-3 alkenyl group, or a C23 alkynyl group; and n1 and n2 are each an integer of 1 to 3 when Ar1 and Ar2 are each a benzene ring, or an integer of 1 to 5 when Ar1 and Ar2 are each a naphthalene ring. In Formulae (1) and (2), R5 is a linear or branched alkyl group having a carbon atom number of 2 to 10. In Formulae (3) and (4), X is a single bond, a saturated or unsaturated linear or cyclic organic group having a carbon atom number of 1 to 30 and possibly containing a nitrogen atom, or a C6-30 arylene group.
Examples of the aforementioned halogen atom include fluorine atom, chlorine atom, bromine atom, and iodine atom.
Examples of the aforementioned C110 alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, cyclopropyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, cyclobutyl group, 1-methyl-cyclopropyl group, 2-methyl-cyclopropyl group, n-pentyl group, 1-methyl-n-butyl group, 2-methyl-n-butyl group, 3-methyl-n-butyl group, 1,1-dimethyl-n-propyl group, 1,2-dimethyl-n-propyl group, 2,2-dimethyl-n-propyl group, 1-ethyl-n-propyl group, cyclopentyl group, 1-methyl-cyclobutyl group, 2-methyl-cyclobutyl group, 3-methyl-cyclobutyl group, 1,2-dimethyl-cyclopropyl group, 2,3-dimethyl-cyclopropyl group, 1-ethyl-cyclopropyl group, 2-ethyl-cyclopropyl group, n-hexyl group, 1-methyl-n-pentyl group, 2-methyl-n-pentyl group, 3-methyl-n-pentyl group, 4-methyl-n-pentyl group, 1,1-dimethyl-n-butyl group, 2-dimethyl-n-butyl group, 1,3-dimethyl-n-butyl group, 2,2-dimethyl-n-butyl group, 2,3-dimethyl-n-butyl group, 3,3-dimethyl-n-butyl group, 1-ethyl-n-butyl group, 2-ethyl-n-butyl group, 1,1,2-trimethyl-n-propyl group, 1,2,2-trimethyl-n-propyl group, 1-ethyl-1-methyl-n-propyl group, 1-ethyl-2-methyl-n-propyl group, cyclohexyl group, 1-methyl-cyclopentyl group, 2-methyl-cyclopentyl group, 3-methyl-cyclopentyl group, 1-ethyl-cyclobutyl group, 2-ethyl-cyclobutyl group, 3-ethyl-cyclobutyl group, 1,2-dimethyl-cyclobutyl group, 1,3-dimethyl-cyclobutyl group, 2,2-dimethyl-cyclobutyl group, 2,3-dimethyl-cyclobutyl group, 2,4-dimethyl-cyclobutyl group, 3,3-dimethyl-cyclobutyl group, 1-n-propyl-cyclopropyl group, 2-n-propyl-cyclopropyl group, 1-i-propyl-cyclopropyl group, 2-i-propyl-cyclopropyl group, 1,2,2-trimethyl-cyclopropyl group, 1,2,3-trimethyl-cyclopropyl group, 2,2,3-trimethyl-cyclopropyl group, 1-ethyl-2-methyl-cyclopropyl group, 2-ethyl-1-methyl-cyclopropyl group, 2-ethyl-2-methyl-cyclopropyl group, and 2-ethyl-3-methyl-cyclopropyl group,
Examples of the aforementioned C1-3 alkyl group and C2-10 alkyl group are included in the examples described above.
The C2-10 alkyl group is preferably a C1-7 alkyl group.
Examples of the aforementioned. C2-10 alkenyl group include ethenyl group, 1-propenyl group, 2-propenyl group, 1-methyl-1-ethenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-ethylethenyl group, 1-methyl-1-propenyl group, 1-methyl-2-propenyl group, 1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-pentenyl group, 1-n-propylethenyl group, 1-methyl-1-butenyl group, 1-methyl-2-butenyl group, 1-methyl-3-butenyl group, 2-ethyl-2-propenyl group, 2-methyl-1-butenyl group, 2-methyl-2-butenyl group, 2-methyl-3-butenyl group, 3-methyl-1-butenyl group, 3-methyl-2-butenyl group, 3-methyl-3-butenyl group, 1,1-dimethyl-2-propenyl group, 1-i-propylethenyl group, 1,2-dimethyl-1-propenyl group, 1,2-dimethyl-2-propenyl group, 1-cyclopentenyl group, 2-cyclopentenyl group, 3-cyclopentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-methyl-1-pentenyl group, 1-methyl-2-pentenyl group, 1-methyl-3-pentenyl group, 1-methyl-4-pentenyl group, 1-n-butylethenyl group, 2-methyl-1-pentenyl group, 2-methyl-2-pentenyl group, 2-methyl-3-pentenyl group, 2-methyl-4-pentenyl group, 2-n-propyl-2-propenyl group, 3-methyl-1-pentenyl group, 3-methyl-2-pentenyl group, 3-methyl-3-pentenyl group, 3-methyl-4-pentenyl group, 3-ethyl-3-butenyl group, 4-methyl-1-pentenyl group, 4-methyl-2-pentenyl group, 4-methyl-3-pentenyl group, 4-methyl-4-pentenyl group, 1,1-dimethyl-2-butenyl group, 1,1-dimethyl-3-butenyl group, 1,2-dimethyl-1-butenyl group, 1,2-dimethyl-2-butenyl group, 1,2-dimethyl-3-butenyl group, 1-methyl-2-ethyl-2-propenyl group, 1-s-butylethenyl group, 1,3-dimethyl-1-butenyl group, 1,3-dimethyl-2-butenyl group, 1,3-dimethyl-3-butenyl group, 1-i-butylethenyl group, 2,2-dimethyl-3-butenyl group, 2,3-dimethyl-1-butenytl group, 2,3-dimethyl-2-butenyl group, 2,3-dimethyl-3-butenyl group, 2-i-propyl-2-propenyl group, 3,3-dimethyl-1-butenyl group, 1-ethyl-1-butenyl group, 1-ethyl-2-butenyl group, 1-ethyl-3-butenyl group, 1-n-propyl-1-propenyl group, 1-n-propyl-2-propenyl group, 2-ethyl-1-butenyl group, 2-ethyl-2-butenyl group, 2-ethyl-3-butenyl group, 1,1,2-trimethyl-2-propenyl group, 1-t-butylethenyl group, 1-methyl-1-ethyl-2-propenyl group, 1-ethyl-2-methyl-1-propenyl group, 1-ethyl-2-methyl-2-propenyl group, 1-i-propyl-1-propenyl group, 1-i-propyl-2-propenyl group, 1-methyl-2-cyclopentenyl group, 1-methyl-3-cyclopentenyl group, 2-methyl-1-cyclopentenyl group, 2-methyl-2-cyclopentenyl group, 2-methyl-3-cyclopentenyl group, 2-methyl-4-cyclopentenyl group, 2-methyl-5-cyclopentenyl group, 2-methylene-cyclopentyl group, 3-methyl-1-cyclopentenyl group, 3-methyl-2-cyclopentenyl group, 3-methyl-3-cyclopentenyl group, 3-methyl-4-cyclopentenyl group, 3-methyl-5-cyclopentenyl group, 3-methylene-cyclopentyl group, 1-cyclohexenyl group, 2-cyclohexenyl group, and 3-cyclohexenyl group.
Examples of the aforementioned C2-3 alkenyl group are included in the examples described above.
Examples of the C2-3 alkynyl group include ethynyl group and 1-propynyl group.
R3 is a tetravalent C1-2 organic group, and R4 is a C1-3 alkyl group, a C2-3 alkenyl group, or a C2-3 alkynyl group. Specific examples of the groups represented by R3 and R4 include groups described below.
(* represents a point of bonding with a nitrogen atom.)
In the present invention, when each of Ar1 and Ar2 is a benzene ring substituted with R1 or R2 in Formula (1) or (3), examples of the carbazole structure contained in the repeating unit include carbazole, N-methylcarbazole, N-ethylcarbazole, 1,3,6,8-tetranitrocarbazole, 3,6-diaminocarbazole, 3,6-dibromo-9-ethylcarbazole, 3,6-dibromo-9-phenylcarbazole, 3,6-dibromocarbazole, 3,6-dichlorocarbazole, 3-amino-9-ethylcarbazole, 3-bromo-9-ethylcarbazole, 4,4′-bis(9H-carbazol-9-yl)biphenyl, 9-ethylcarbazole, 4-glycidylcarbazole, 4-hydroxycarbazole, 9-(1H-benzotriazol-1-ylmethyl)-9H-carbazole, 9-acetyl-3,6-diiodocarbazole, 9-benzoylcarbazole, 9-benzoylcarbazole-6-dicarboxaldehyde, 9-benzylcarbazole-3-carboxaldehyde, 9-methylcarbazole, 9-phenylcarbazole, 9-vinylcarbazole, carbazole potassium, carbazole-N-carbonyl chloride, N-ethylcarbazole-3-carboxaldehyde, and N-((9-ethylcarbazol-3-yl)methylene)-methyl-1-indolinylamine.
In the present invention, X in Formula (3) or (4) is a single bond, a saturated or unsaturated linear or cyclic organic group having a carbon atom number of 1 to 30 and possibly containing a nitrogen atom, or a C6-30 arylene group. X (except for a single bond) may be any of groups of the following Formulae.
(* represents a point of bonding with carbon.)
The polymer having at least one repeating unit of Formula (1), (2), (3), or (4) may be produced by, for example, a method including reacting a compound of the following Formula (1-a) or (2-a) with a compound of the following Formula (3-a) or (4-a) to thereby prepare a reaction product A, and then reacting the reaction product A with a compound of the following Formula (5-a). Needless to say, the synthesis method for the aforementioned polymer is not limited to this reaction method.
In the aforementioned Formulae, Ar1, Ar2, R1, R2, R3, R4, R5, and X have the same meanings as defined above. R9 is a C1-10 alkyl group or a C1-10 haloalkyl group.
Examples of the carbazole compound of Formula (1-a) include carbazole, N-methylcarbazole, N-ethylcarbazole, 1,3,6,8-tetranitrocarbazole, 3,6-diaminocarbazole, 3,6-dibromo-9-ethylcarbazole, 3,6-dibromo-9-phenylcarbazole, 3,6-dibromocarbazole, 3,6-dichlorocarbazole, 3-amino-9-ethylcarbazole, 3-bromo-9-ethylcarbazole, 4,4′-bis(9H-carbazol-9-yl)biphenyl, 9-ethylcarbazole, 4-glycidylcarbazole, 4-hydroxycarbazole, 9-(1H-benzotriazol-1-ylmethyl)-9H-carbazole, 9-acetyl-3,6-diiodocarbazole, 9-benzoylcarbazole, 9-benzoylcarbazole-6-dicarboxaldehyde, 9-benzylcarbazole-3-carboxaldehyde, 9-methylcarbazole, 9-phenylcarbazole, 9-vinylcarbazole, carbazole potassium, carbazole-N-carbonyl chloride, N-ethylcarbazole-3-carboxaldehyde, and N-((9-ethylcarbazol-3-yl)methylene)-2-methyl-1-indolinylamine. These compounds may be used alone or in combination of two or more species.
Examples of the dialdehyde compound of Formula (3-a) are compounds of the following Formulae.
The dialdehyde compound of Formula (3-a) is preferably a dialdehyde compound wherein X is a single bond or a saturated or unsaturated linear or cyclic organic group having a carbon atom number of 1 to 30 and possibly containing a nitrogen atom, particularly preferably a dialdehyde compound wherein X is a single bond.
Since such a dialdehyde compound is readily available, the production cost of the resultant resist underlayer film composition can be reduced.
An equivalent of the above-exemplified dialdehyde compound may also be used. For example, the equivalent of the compound of Formula (3-a) may be a compound of the following Formula:
(wherein X has the same meaning as defined above, and R's are each a monovalent C1-10 hydrocarbon group and may be identical to or different from each other);
(wherein X has the same meaning as defined above, and R″ is a divalent C1-10 hydrocarbon group); or
(wherein X′ is an organic group prepared by removal of one hydrogen atom from the aforementioned group of X, and R′ is a monovalent C1-10 hydrocarbon group) when a hydrogen atom is bonded to the α-carbon atom of a formyl group.
Specific examples of the equivalent of Formula (3A) are as follows.
Other similar dialdehyde compounds may also be used.
Specific examples of the equivalent of Formula (3B) are as follows.
Other similar dialdehyde compounds may also be used.
Specific examples of the equivalent of Formula (3C) are as follows.
Other similar dialdehyde compounds may also be used.
Regarding the ratio of the dialdehyde compound of Formula (3-a) to the compound of Formula (1-a) or (2-a), the amount of the dialdehyde compound of Formula (3-a) is preferably 0.01 to 5 mol, more preferably 0.1 to 2 mol, relative to 1 mol of the compound of Formula (1-a) or (2-a).
The resist underlayer film material of the present invention may contain at least one polymer produced by reaction of a compound of Formula (5-a) with a polymer (reaction product A) prepared by condensation between one compound or two or more compounds of Formula (1-a) or (2-a) and one or more compounds of Formula (3-a) and/or an equivalent thereof.
So long as the effects of the present invention are not impaired, the resist underlayer film material of the present invention may contain at least one polymer produced by reaction of a compound of Formula (5-a) with a polymer (reaction product A) prepared by condensation between an aromatic compound other than a compound of Formular (1-a) or (2-a) (hereinafter the aromatic compound will be referred to as “additional aromatic compound”) and a compound of Formula (3-a).
Examples of the additional aromatic compound include phenol compounds, naphthol compounds, bisphenol compounds, and polyphenol compounds.
The reaction product A is a polymer prepared by condensation between the compound of Formula (1-a) or (2-a) or the additional aromatic compound (if necessary) and the compound of Formula (3-a). As described above, the present invention may involve the use of one compound or two or more compounds of Formula (1-a) or (2-a), and one additional aromatic compound or two or more additional aromatic compounds. Thus, the aforementioned polymer produced by reaction of the reaction product A with a compound of Formula (5-a) may be a multi-component copolymer.
A monomer other than the compound of Formula (1-a) or (2-a) and the compound of Formula (3-a) may be used for reaction in such an amount that the effects of the present invention are not impaired (e.g., less than 50% by mole, less than 30% by mole, less than 20% by mole, less than 10% by mole, or less than 5% by mole).
Examples of the acid catalyst used for the reaction include mineral acids such as sulfuric acid, phosphoric acid, and perchloric acid; organic sulfonic acids such as p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, and methanesulfonic acid; and carboxylic acids such as formic acid and oxalic acid. The amount of the acid catalyst used is appropriately determined depending on the type of the acid used, The amount of the acid catalyst used is generally 0.001 to 10,000 parts by mass, preferably 0.01 to 1,000 parts by mass, more preferably 0.1 to 100 parts by mass, relative to 100 parts by mass of the compound of Formula (1-a) or (2-a).
The aforementioned condensation reaction and addition reaction may be performed without use of a solvent, but generally performed with use of a solvent. Any solvent may be used, so long as it does not inhibit the reaction. Examples of the solvent include ethers, such as 1,2-dimethoxyethane, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, tetrahydrofuran, and dioxane.
If necessary, a polymerization inhibitor (radical trapping agent) may be added during the reaction. Specific examples of the polymerization initiator include 2,6-diisobutylphenol, 3,5-di-tert-butylphenol, 3,5-di-tert-butylcresol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, tert-butylcatechol, and 4-methoxy-1-naphthol. In the case of addition of a polymerization inhibitor, the amount of the polymerization inhibitor added is preferably 1% by mass or less relative to the total solid content.
The reaction temperature is generally 40° C. to 200° C. The reaction time is appropriately determined depending on the reaction temperature, and is generally about 30 minutes to 50 hours.
The polymer prepared as described above has a weight average molecular weight Mw of generally 500 to 1,000,000 or 600 to 500,000.
The polymer suitably used in the present invention will be described in Examples hereinbelow.
Regarding the compound of Formula (5-a), R3 and R4 have the same meanings as defined in Formulae (1) to (4), and R9 is a C1-10 alkyl group or a C1-10 haloalkyl group. Examples of the compound include propargyl bromide, 2-butynyl bromide, 2-pentynyl chloride, and 1-chloro-2-octyne.
No particular limitation is imposed on the solvent used in the resist underlayer film-forming composition of the present invention, so long as the solvent can dissolve the aforementioned polymer. In particular, the resist underlayer film-forming composition of the present invention is used in the form of homogeneous solution. Thus, in consideration of the coating performance of the composition, the solvent is recommended to be used in combination with a solvent commonly used in a lithographic process.
Examples of such a solvent include methylcellosolve acetate, ethylcellosolve acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, methyl isobutyl carbinol, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropinoate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol mooethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, ethyl lactate, propyl lactate, isopropyl lactate, butyl lactate, isobutyl lactate, methyl formate, ethyl formate, propyl formate, isopropyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl acetate, ethyl acetate, amyl acetate, isoamyl acetate, hexyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, butyl propionate, isobutyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, ethyl hydroxyacetate, ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-methoxybutyl acetate, 3-methoxypropyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, toluene, xylene, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 4-methyl-2-pentanol, and γ-butyrolactone. These solvents may be used alone or in combination of two or more species.
The following compound described in WO2018/131562A1 may also be
used:
(in Formula (i), R6, R7, and R8 are each a hydrogen atom or a C1-20 alkyl group that may be interrupted by an oxygen atom, a sulfur atom, or an amide bond, may be identical to or different from one another, and may be bonded together to form a ring structure).
The C1-20 alkyl group is, for example, a linear or branched alkyl group that may have or may not have a substituent. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, n-heptyl group, n-octyl group, cyclohexyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, p-tert-butylcyclohexyl group, n-decyl group, n-dodecylnonyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group. Preferred is a C1-12 alkyl group, more preferred is a C1-8 alkyl group, and still more preferred is a C1-4 alkyl group.
The C1-20 alkyl group interrupted by an oxygen atom, a sulfur atom, or an amide bond is, for example, one containing a structural unit —CH2—O—, —CH2—S—, —CH2—NHCO—, or —CH2—CONH—. The alkyl group may contain one unit or two or more units of —O—, —S—, —NHCO—, or —CONH—. Specific examples of the C1-20 alkyl group interrupted by the —O—, —S—, —NHCO—, or —CONH— unit include methoxy group, ethoxy group, propoxy group, butoxy group, methylthio group, ethylthio group, propylthio group, butylthio group, methylcarbonylamino group, ethylcarbonylamino group, propylcarbonylamino group, butylcarbonylamino group, methylaminocarbonyl group, ethylaminocarbonyl group, propylaminocarbonyl group, and butylaminocarbonyl group. Other examples include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, and octadecyl group, wherein each of these groups is substituted with, for example, methoxy group, ethoxy group, propoxy group, butoxy group, methylthio group, ethylthio group, propylthio group, butylthio group, methylcarbonylamino group, ethylcarbonylamino group, methylaminocarbonyl group, or ethylaminocarbonyl group. Preferred is a methoxy group, an ethoxy group, a methylthio group, or an ethylthio group, and more preferred is a methoxy group or an ethoxy group.
Since any of these solvents has a relatively high boiling point, the solvent is effective for providing the resist underlayer film-forming composition with a high embedding property and high flattening property.
Specific examples of preferred compounds of Formula (i) are as follows.
Among the aforementioned compounds, preferred are 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutylamide, and compounds of the following formula:
and particularly preferred compounds of Formula (i) are 3-methoxy-N,N-dimethylpropionamide and N,N-dimethylisobutylamide.
These solvents may be used alone or in combination of two or more species. Among these solvents, preferred are solvents having a boiling point of 160° C. or higher, for example, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, cyclohexanone, 3-methoxy-N,N-dimethylpropionamide, N,N-dimethylisobutylamide, 2,5-dimethylhexane-1,6-diyl diacetate (DAH; cas, 89182-68-3), and 1,6-diacetoxyhexane (cas, 6222-17-9). Particularly preferred are propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and N,N-dimethylisobutylamide.
The resist underlayer film-forming composition of the present invention may contain a crosslinking agent component. The crosslinking agent is, for example, a melamine compound, a substituted urea compound, or a polymer thereof. The crosslinking agent is preferably a crosslinking agent having at least two crosslinkable substituents, for example, a compound such as methoxymethylated glycoluril (e.g., tetramethoxymethyl glycoluril), butoxymethylated glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, or methoxymethylated thiourea. A condensate of such a compound may also be used.
The aforementioned crosslinking agent may be a crosslinking agent having a high thermal resistance. The crosslinking agent having a high thermal resistance is preferably a compound containing a crosslinkable substituent having an aromatic ring (e.g., a benzene ting or a naphthalene ring) in the molecule.
Examples of the compound include a compound of the following Formula (5) or a condensation product composed of at least one compound of the following Formula (5), and a polymer or oligomer having a repeating unit of the following Formula (6).
The benzene ring of each of the compounds of Formulae (5) and (6) may be substituted with a C1-10 alkyl group. In the aforementioned formulae, R11, R12, R13, and R14 are each a hydrogen atom or a C1-10 alkyl group, and these alkyl groups may be those exemplified above. In the aforementioned formulae, n3 is an integer of 1 to 4, n4 is an integer of 1 to (5−n3), (n3+n4) is an integer of 2 to 5, n5 is an integer of 1 to 4, n6 is 0 to (4−n5), and (n5+n6) is an integer of 1 to 4. Each of the oligomer and the polymer may have 2 to 100 or 2 to 50 repeating unit structures.
Examples of the compound of Formula (5) or the condensation product composed of at least one compound of Formula (5) are as follows.
The aforementioned compounds can be obtained as products available from ASAHI YTJKIZAI CORPORATION and Honshu Chemical Industry Co., Ltd. For example, among the aforementioned crosslinking agents, the compound of Formula (5-24) can be obtained as trade name TM-BIP-A available from ASAHI YUKIZAI CORPORATION.
The amount of the crosslinking agent added may vary depending on, for example, the type of a coating solvent used, the type of an underlying substrate used, the viscosity of a solution required, or the shape of a film required. The amount of the crosslinking agent is 0.001 to 80% by mass, preferably 0.01 to 50% by mass, more preferably 0.05 to 40% by mass, relative to the total solid content. Such a crosslinking agent may cause a crosslinking reaction by its self-condensation. When a crosslinkable substituent is present in the aforementioned polymer of the present invention, such a crosslinking agent may cause a crosslinking reaction with the crosslinkable substituent.
The resist underlayer film-forming composition of the present invention may contain an acid and/or an acid generator.
Examples of the acid include p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonic acid, pyridinium phenol sulfonic acid, salicylic acid, 5-sulfosalicylic acid, 4-phenolsulfonic acid, camphorsulfonic acid, 4-chlorobenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, hydroxybenzoic acid, and naphthalenecarboxylic acid.
A single acid may be used alone, or two or more acids may be used in combination. The amount of the acid is generally 0.0001 to 20% by mass, preferably 0.0005 to 10% by mass, more preferably 0.01 to 3% by mass, relative to the total solid content.
The acid generator may be, for example, a thermal acid generator or a photoacid generator.
Examples of the thermal acid generator include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, K-PURE [registered trademark] CXC-1612, CXC-1614, TAG-2172, TAG-2179, TAG-2678, TAG-2689, and TAG2700 (available from King Industries Inc.), SI-45, SI-60, SI-80, SI-100, SI-110, and SI-150 (available from SANSHIN CHEMICAL INDUSTRY CO., LTD.), and other organic sulfonic acid alkyl esters.
A photoacid generator generates an acid during the exposure of a resist. Thus, the acidity of an underlayer film can be adjusted. This is one method for adjusting the acidity of an underlayer film to the acidity of a resist serving as an upper layer of the underlayer film. Furthermore, the adjustment of the acidity of an underlayer film enables the control of the pattern shape of a resist formed as an upper layer of the underlayer film.
Examples of the photoacid generator contained in the resist underlayer film-forming composition of the present invention include an onium salt compound, a sulfonimide compound, and a disulfonyldiazomethane compound.
Examples of the onium salt compound include iodonium salt compounds, such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro normal butanesulfonate, diphenyliodonium perfluoro normal octanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate; and sulfonium salt compounds, such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoro normal butanesulfonate, triphenylsulfonium camphorsulfonate, and triphenylsulfonium trifluoromethanesulfonate.
Examples of the sulfonimide compound include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoro normal butane sulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.
Examples of the disulfonyldiazomethane compound include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.
A single acid generator may be used alone, or two or more acid generators may be used in combination.
When an acid generator is used, the amount thereof is 0.01 to 5 parts by mass, or 0.1 to 3 parts by mass, or 0.5 to 1 part by mass, relative to 100 parts by mass of the solid content of the resist underlayer film-forming composition.
The resist underlayer film-forming composition of the present invention may contain a surfactant for further improving the applicability of the composition to an uneven surface without causing, for example, pinholes or striations. Examples of the surfactant include nonionic surfactants, for example, polyoxyethylene alkyl ethers, such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether, polyoxyethylene alkylallyl ethers, such as polyoxyethylene octylphenol ether and polyoxyethylene nonylphenol ether, polyoxyethylene-polyoxypropylene block copolymers, sorbitan fatty acid esters, such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate, polyoxyethylene sorbitan fatty acid esters, such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate; fluorine-containing surfactants, such as EFTOP EF301, EF303, and EF352 (trade name, available from Tohkem Products Corporation), MEGAFACE F171, F173, R-40, R-40N, and R-40LM (trade name, available from DIC Corporation), Fluorad FC430 and FC431 (trade name, available from Sumitomo 3M Limited), Asahi Guard AG710 and SURFLON S-382, SC101, SC102, SC103, SC104, SC105, and SC106 (trade name, available from Asahi Glass Co., Ltd.); and Organosiloxane Polymer KP341 (available from Shin-Etsu Chemical Co., Ltd.). The amount of such a surfactant is generally 2.0% by mass or less, preferably 1.0% by mass or less, relative to the total solid content of the resist underlayer film material. These surfactants may be used alone or in combination of two or more species. When a surfactant is used, the amount thereof is 0.0001 to 5 parts by mass, or 0.001 to 1 part by mass, or 0.01 to 0.5 parts by mass, relative to 100 parts by mass of the solid content of the resist underlayer film-forming composition.
The resist underlayer film-forming composition of the present invention may contain a light-absorbing agent, a rheology controlling agent, an adhesion aid, etc. The rheology controlling agent is effective for improving the fluidity of the underlayer film-forming composition. The adhesion aid is dfective for improving the adhesion between a semiconductor substrate or a resist and an underlayer film.
Preferred examples of the light-absorbing agent include commercially available light-absorbing agents described in “Kogyoyo Shikiso no Gijutsu to Shijo (Technology and Market of Industrial Colorant)” (CMC Publishing Co., Ltd.) or “Senryo Binran (Dye Book)” (edited by The Society of Synthetic Organic Chemistry, Japan), such as C. I. Disperse Yellow 1, 3, 4, 5, 7, 8, 13, 23, 31, 49, 50, 51, 54, 60, 64, 66, 68, 79, 82, 88, 90, 93, 102, 114, and 124; C. I. Disperse Orange 1, 5, 13, 25, 29 30, 31, 44, 57, 72, and 73; C. I. Disperse Red 1, 5, 7, 13, 17, 19, 43, 50, 54, 58, 65, 72, 73, 88, 117, 137, 143, 199, and 210; C. I. Disperse Violet 43; C. I. Disperse Blue 96; C. I. Fluorescent Biightening Agent 112, 135, and 163; C. I. Solvent Orange 2 and 45; C. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, and 49; C. I. Pigment Green 10; and C. I. Pigment Brown 2. The light-absorbing agent is incorporated in an amount of generally 10% by mass or less, preferably 5% by mass or less, relative to the total solid content of the resist underlayer film-forming composition.
The rheology controlling agent is incorporated for the main purpose of improving the fluidity of the resist underlayer film-forming composition; in particular, the purpose of improving the thickness uniformity of a resist underla.yer film or improving filling of the interior of a hole with the resist underlayer film-forming composition in a baking process. Specific examples of the rheology controlling agent include phthalic acid derivatives, such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate, and butyl isodecyl phthalate; adipic acid derivatives, such as di-normal butyl adipate, diisobutyl adipate, diisooctyl adipate, and octyldecyl adipate; maleic acid derivatives, such as di-normal butyl maleate, diethyl maleate, and dinonyl maleate; oleic acid derivatives, such as methyl oleate, butyl oleate, and tetrahydrofurfuryl oleate; and stearic acid derivatives, such as normal butyl stearate and glyceryl stearate. Such a rheology controlling agent is incorporated in an amount of generally less than 30% by mass relative to the total solid content of the resist underlayer film-forming composition.
The adhesion aid is incorporated for the main purpose of improving the adhesion between a substrate or a resist and the resist underlayer film-forming coinposition; in particular, the purpose of preventing peeling of the resist during development. Specific examples of the adhesion aid include chlorosilane compounds, such as trimethylchlorosilane, dimethylmethylolchlorosilane, methyldiphenylchlorosilane, and chloromethyldimethylchlorosilane; alkoxysilane compounds, such as trimethylmethoxysilane, dimethyldiethoxysilane, methyldimethoxysilane, dimethylmethylolethoxysilane, diphenyldimethoxysilane, and phenyltriethoxysilane; silazane compounds, such as hexamethyldisilazane, N,N′-bis(trimethylsilyl)urea, dimethyltrimethylsilylamine, and trimethylsilylimidazole; silane compounds, such as methyloltrichlorosilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane; heterocyclic compounds, such as benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, urazole, thiouracil, mercaptoimidazole, and mercaptopyrimidine; and urea or thiourea compounds, such as 1,1-dimethylurea and 1,3-dimethylurea. Such an adhesion aid is incorporated in an amount of generally less than 5% by mass, preferably less than 2% by mass, relative to the total solid content of the resist underlayer film-forming composition.
The resist underlayer film-forming composition of the present invention has a solid content of generally 0.1 to 70% by mass, preferably 0.1 to 60% by mass. The term “solid content” as used herein refers to the amount of all components (except for the solvent) contained in the resist underlayer film-forming composition. The amount of the aforementioned polymer in the solid content is 1 to 100% by mass, 1 to 99.9% by mass, 50 to 99.9% by mass, 50 to 95% by mass, or 50 to 90% by mass (preferably in this order).
One measure for evaluating whether the resist underlayer film-forming composition is in the form of homogeneous solution is to observe the permeation of the composition through a specific microfilter. The resist underlayer film-forming composition of the present invention permeates through a microfilter having a pore size of 0.1 μm, and thus is in the form of homogeneous solution.
Examples of the material of the aforementioned microfilter include fluororesins such as PTFE (polytetrafluoroethylene) and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PE (polyethylene), UPE (ultra-high molecular weight polyethylene), PP (polypropylene), PSF (polysulfone), PES (polyethersulfone), and nylon. Preferably, the microfilter is formed of PTFE (polytetrafluoroethylene).
Next will be described methods of producing a resist underlayer film and a semiconductor device using the resist underlayer film-forming composition of the present invention.
The resist underlayer film-forming composition of the present invention is applied onto a substrate used for the production of a semiconductor device (e.g., a silicon wafer substrate, a silicon/silicon dioxide-coated substrate, a silicon nitride substrate, a glass substrate, an ITO substrate, a polyimide substrate, or a substrate coated with a low dielectric constant material (low-k material)) by an appropriate application method with, for example, a spinner or a coater, followed by baking of the composition, to thereby form a resist underlayer film. The baking is performed under appropriately determined conditions; i.e., a baking temperature of 80° C. to 400° C. and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 150° C. to 350° C., and the baking time is 0.5 to 2 minutes. The thickness of the thus-formed underlayer film is, for example, 10 to 1,000 nm, or 20 to 500 nm, or 30 to 400 nm, or 50 to 300 nm.
An inorganic resist underlayer film (hard mask) may be formed on the organic resist underlayer film of the present invention. For example, an inorganic resist underlayer film may be formed by spin coating of the silicon-containing resist underlayer film (inorganic resist underlayer film)-forming composition described in WO 2009/104552A1, or an Si-containing inorganic material film may be formed by the CVD method, etc.
The resist underlayer film-forming composition of the present invention may be applied onto a semiconductor substrate having a stepped portion and a non-stepped portion (i.e., an uneven substrate), followed by baking of the composition, to thereby form a resist underlayer film wherein a difference in level between the stepped portion and the non-stepped portion falls within a range of 3 to 70 nm.
Subsequently, a resist film (a photoresist layer) is formed on the resist underlayer film. The photoresist layer may be formed by a well-known process; i.e., application of a photoresist composition solution onto the underlayer film, and subsequent baking. The thickness of the photoresist layer is, for example, 50 to 10,000 nm, or 100 to 2,000 nm, or 200 to 1,000 nm.
No particular limitation is imposed on the photoresist formed on the resist underlayer film, so long as the photoresist is sensitive to light used for exposure. The photoresist may be either of negative and positive photoresists. Examples of the photoresist include a positive photoresist formed of a novolac resin and a 1,2-naphthoquinone diazide sulfonic acid ester; a chemically amplified photoresist formed of a binder having a group that decomposes with an acid to thereby increase the alkali dissolution rate and a photoacid generator; a chemically amplified photoresist formed of a low-molecular-weight compound that decomposes with an acid to thereby increase the alkali dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator; and a chemically amplified photoresist formed of a binder having a group that decomposes with an acid to thereby increase the alkali dissolution rate, a low-molecular-weight compound that decomposes with an acid to thereby increase the alkali dissolution rate of the photoresist, and a photoacid generator. Specific examples of the photoresist include trade name APEX-E, available from Shipley, trade name PAR710, available from Sumitomo Chemical Company, Limited, and trade name SEPR430, available from Shin-Etsu Chemical Co., Ltd. Other examples of the photoresist include fluorine atom-containing polymer-based photoresists described in Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).
Subsequently, a resist pattern is formed by irradiation with light or electron beams and development. Firstly, light exposure is performed through a predetermined mask. The light exposure is performed with, such as near-ultraviolet rays, far-ultraviolet rays, or extreme-ultraviolet rays (e.g., EUV, wavelength: 13.5 nm). Specifically, the light exposure may involve the use of, for example, a KrF excimer laser (wavelength: 248 nm), an ArF excimer laser (wavelength: 193 nm), and an F2 excimer laser (wavelength: 157 nm). Of these, an ArF excimer laser (wavelength: 193 nm) and EUV (wavelength: 13.5 nm) are preferred. After the light exposure, post exposure bake may be performed as appropriate. The post exposure bake is performed under appropriately determined conditions; i.e., a heating temperature of 70° C. to 150° C. and a heating time of 0.3 to 10 minutes.
In the present invention, a resist for electron beam lithography may be used in place of the photoresist. The electron beam resist may be either of negative and positive resists. Examples of the electron beam resist include a chemically amplified resist formed of an acid generator and a binder having a group that decomposes with an acid to thereby change the alkali dissolution rate; a chemically amplified resist formed of an alkali-soluble binder, an acid generator, and a low-molecular-weight compound that decomposes with an acid to thereby change the alkali dissolution rate of the resist; a chemically amplified resist formed of an acid generator, a binder having a group that decomposes with an acid to thereby change the alkali dissolution rate, and a low-molecular-weight compound that decomposes with an acid to thereby change the alkali dissolution rate of the resist; a non-chemically amplified resist formed of a binder having a group that decomposes with electron beams to thereby change the alkali dissolution rate; and a non-chemically amplified resist formed of a binder having a moiety that is cut with electron beams to thereby change the alkali dissolution rate. Also in the case of use of such an electron beam resist, a resist pattern can be formed by using electron beams as an irradiation source in the same manner as in the case of using the photoresist.
Subsequently, development is performed with a developer. When, for example, a positive photoresist is used, an exposed portion of the photoresist is removed to thereby form a pattern of the photoresist.
Examples of the developer include alkaline aqueous solutions, for example, aqueous solutions of alkali metal hydroxides, such as potassium hydroxide and sodium hydroxide; aqueous solutions of quaternary ammonium hydroxides, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline; and aqueous solutions of arnines, such as ethanolamine, propylamine, and ethylenediamine. Such a developer may also contain, for example, a surfactant. The development is performed under appropriately determined conditions; i.e., a temperature of 5° C. to 50° C. and a time of 10 to 600 seconds.
The resultant patterned photoresist (upper layer) is used as a protective film for removing the inorganic underlayer film (intermediate layer). Subsequently, the patterned photoresist and the patterned inorganic underlayer film (intermediate layer) are used as protective films for removing the organic underlayer film (lower layer). Finally, the patterned inorganic underlayer film (intermediate layer) and the patterned organic underlayer film (lower layer) are used as protective films for processing the semiconductor substrate.
Specifically, a photoresist-removed portion of the inorganic underlayer film (intermediate layer) is removed by dry etching to thereby expose the semiconductor substrate. The dry etching of the inorganic underlayer film can be performed with any of gasses, such as tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride, chlorine trifluoride, chlorine, trichloroborane, and dichloroborane. The dry etching of the inorganic underlayer film is preferably performed with a halogen-containing gas, more preferably with a fluorine-containing gas. Examples of the fluorine-containing gas include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).
Thereafter, the patterned photoresist and the patterned inorganic underlayer film are used as protective films for removing the organic underlayer film. The dry etching of the organic underlayer film (lower layer) is preferably performed with an oxygen-containing gas, since the inorganic underlayer film, which contains numerous silicon atoms, is less likely to be removed by dry etching with an oxygen-containing gas.
Finally, the semiconductor substrate is processed. The processing of the semiconductor substrate is preferably performed by dry etching with a fluorine-containing gas.
Examples of the fluorine-containing gas include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).
An organic anti-reflective coating may be formed on the resist underlayer film before formation of the photoresist. No particular limitation is imposed on the composition used for formation of the anti-reflective coating, and the composition may be appropriately selected from anti-reflective coating compositions that have been conventionally used in a lithographic process. The anti-reflective coating can be formed by a commonly used method, for example, application of the composition with a spinner or a coater, and baking of the composition.
In the present invention, the organic underlayer film can be formed on the substrate, the inorganic underlayer film can then be formed on the organic underlayer film, and then the inorganic underlayer film can be coated with a photoresist. This process can narrow the pattern width of the photoresist. Thus, even when the photoresist is applied thinly for preventing a pattern collapse, the substrate can be processed through selection of an appropriate etching gas. For example, the resist underlayer film can be processed by using, as an etching gas, a fluorine-containing gas that achieves a significantly high etching rate for the photoresist. The substrate can be processed by using, as an etching gas, a fluorine-containing gas that achieves a significantly high etching rate for the inorganic underlayer film. The substrate can be processed by using, as an etching gas, an oxygen-containing gas that achieves a significantly high etching rate for the organic underlayer film.
The resist underlayer film formed from the resist underlayer film-forming composition may absorb light used in a lithographic process depending on the wavelength of the light. In such a case, the resist underlayer film can function as an anti-reflective coating having the effect of preventing reflection of light from the substrate. Furthermore, the underlayer film formed from the resist underlayer film-forming composition of the present invention can function as a hard mask. The underlayer film of the present invention can be used as, for example, a layer for preventing the interaction between the substrate and the photoresist; a layer having the function of preventing the adverse effect, on the substrate, of a material used for the photoresist or a substance generated during the exposure of the photoresist to light; a layer having the function of preventing diffusion of a substance generated from the substrate during heating and baking to the photoresist serving as an upper layer; and a barrier layer for reducing a poisoning effect of a dielectric layer of the semiconductor substrate on the photoresist layer.
The underlayer film formed from the resist underlayer film-forming composition can be applied to a substrate having via holes for use in a dual damascene process, and can be used as an embedding material to fill up the holes. The underlayer film can also be used as a flattening material for flattening the surface of a semiconductor substrate having irregularities.
The weight average molecular weight described in Synthesis Examples hereinbelow is measured by gel permeation chromatography (hereinafter abbreviated as “GPC”). The weight average molecular weight is measured with a GPC apparatus (HLC-8320GPC) available from TOSOH CORPORATION under the following conditions.
Column temperature: 40° C.
In a nitrogen atmosphere, a 300-mL four-necked flask was charged with 50 g (299.03 mmol) of carbazole (available from Tokyo Chemical Industry Co., Ltd.), 28.74 g (299.03 mmol) of methanesulfonic acid (available from Tokyo Chemical Industry Co., Ltd.), and 322.34 g of propylene glycol monomethyl ether acetate and heated to 140° C., and the mixture was stirred under reflux for three hours. The resultant reaction mixture was added dropwise to 4,500 mL of methanol (available from KANFO CHEMICAL CO., INC., special grade), to thereby precipitate a polymer (1-1).
Subsequently, 15 g of the above-prepared solid matter and 7.2 g of potassium hydroxide (available from Tokyo Chemical Industry Co., Ltd.) were dissolved in 109.4 g of N-methyl-2-pyrrolidone, and the solution was heated to 40° C. and stirred. To the resultant solution was added dropwise 7.2 g of propargyl bromide (available from Tokyo Chemical Industry Co., Ltd.), and the mixture was stirred for 12 hours. The resultant reaction mixture was filtered and cooled to room temperature, and then 150 g of methyl isobutyl ketone (available from Tokyo Chemical Industry Co., Ltd.) was added to the mixture. The resultant organic layer was washed five times with 50 g of pure water, and then the polymer was reprecipitated in 1,000 mL of hexane. The resultant precipitate was separated by filtration, and then dried under vacuum, to thereby produce a polymer (1). The molecular weight of the polymer was measured by GPC (in terms of standard polystyrene). As a result, the polymer was found to have a weight average molecular weight (Mw) of 4,517.
In a nitrogen atmosphere, a 300-mL four-necked flask was charged with 150 g (870 mmol) of carbazole (available from Tokyo Chemical industry Co., Ltd.), 38.8 g (260 mmol of glyoxal (available from Tokyo Chemical Industry Co., Ltd.), 4.97 g (26 mmol) of p-toluenesulfonic acid (available from Tokyo Chemical Industry Co., Ltd.), and 290 g of 1,4-dioxane (available from KANTO CHEMICAL CO., INC., special grade) and heated to 105° C., and the mixture was stirred under reflux for 11 hours. The resultant reaction mixture was added dropwise to 2,000 mL of methanol (available from KANTO CHEMICAL CO., INC., special grade), to thereby precipitate a polymer. The resultant precipitate was separated by filtration, and then dried under vacuum, to thereby prepare a polymer (2-1).
Subsequently, 15 g of the above-prepared solid matter and 6.5 g of potassium hydroxide (available from Tokyo Chemical industry Co., Ltd.) were dissolved in 109.4 g of dimethyl sulfoxide, and the solution was heated to 40° C. and stirred. To the resultant solution was added dropwise 27.81 g (229 mmol) of propargyl bromide (available from Tokyo Chemical Industry Co., Ltd.), and the mixture was stirred for 12 hours. The resultant reaction mixture was filtered and cooled to room temperature, and then 150 g of cyclohexanone was added to the mixture. The resultant organic layer was washed five times with 50 g of pure water, and then the organic layer was concentrated, to thereby produce a polymer (2) solution. The molecular weight of the polymer was measured by GPC (in terms of standard polystyrene). As a result, the polymer was found to have a weight average molecular weight (Mw) of 1,216.
In a nitrogen atmosphere, a 300-mL four-necked flask was charged with 50 g (299.03 mmol) of carbazole (available from Tokyo Chemical Industry Co., Ltd.), 28.74 g (299.03 mmol) of methanesulfonic acid (available from Tokyo Chemical Industry Co., Ltd.), and 322.34 g of propylene glycol monomethyl ether acetate and heated to 140° C., and the mixture was stirred under reflux for three hours. The resultant reaction mixture was added dropwise to 4,500 mL of methanol (available from KANTO CHEMICAL CO., INC., special grade), to thereby precipitate a polymer. The resultant precipitate was separated by filtration, and then dried under vacuum, to thereby produce a polymer. The molecular weight of the polymer was measured by GPC (in terms of standard polystyrene). As a result, the polymer was found to have a weight average molecular weight (Mw) of 3,404. The resultant polymer was diluted with propylene glycol monomethyl ether acetate to achieve a solid content concentration of 14.97%, to thereby produce a polymer (3) solution.
In a nitrogen atmosphere, a 300-mL four-necked flask was charged with 30 g (154 mmol) of ethylcarbazole (available from Tokyo Chemical Industry Co., Ltd.), 7.38 g (77 mmol) of methanesulfonic acid (available from Tokyo Chemical Industry Co., Ltd.), and 87.2 g of propylene glycol monomethyl ether acetate and heated to 140° C., and the mixture was stirred under reflux for 15 hours. The resultant reaction mixture was added dropwise to 900 mL of methanol (available from KANTO CHEMICAL CO., INC., special grade), to thereby precipitate a polymer. The resultant precipitate was separated by filtration, and then dried under vacuum, to thereby produce a polymer. The molecular weight of the polymer was measured by GPC (in terms of standard polystyrene). As a result, the polymer was found to have a weight average molecular weight (Mw) of 2,662. The resultant polymer was diluted with propylene glycol monomethyl ether acetate to achieve a solid content concentration of 30%, and a cation-exchange resin and an anion-exchange resin were each added in an amount equal to that of the solid content, The resultant mixture was stirred for four hours, and the ion-exchange resins were filtered, to thereby produce a polymer (4) solution.
11.99 g of a resin solution of the polymer (1) produced in Synthesis Example 1 was mixed with 1.63 g of propylene glycol monomethyl ether containing 2% TAG2689 (available from King Industries Inc., thermal acid generator), 0.33 g of TMOM-BP (available from Honshu Chemical Industry Co., Ltd., crosslinking agent), 0.16 g of propylene glycol monomethyl ether acetate containing 1% surfactant (available from DIC Corporation, product name: MEGAFACE [trade name] R-40, fluorine-containing surfactant), and 2.08 g of propylene glycol monomethyl ether acetate. Thereafter, the mixture was filtered with a polytetrafluoroethylene-made microfilter (pore size: 0.1 μm), to thereby prepare a resist underlayer film-forming composition solution.
4.1 g of a resin solution of the polymer (2) produced in Synthesis Example 2 was mixed with 0.27 g of propylene glycol monomethyl ether containing 2% pyridinium p-hydroxybenzenesulfonate, 0.12 g of TMOM-BP (available from Honshu Chemical Industry Co., Ltd., crosslinking agent), 3.64 g of propylene glycol monomethyl ether acetate containing 1% surfactant (available from DIC Corporation, product name: MEGAFACE [trade name] R-40, fluorine-containing surfactant), 1.59 g of propylene glycol monomethyl ether, and 0.21 g of cyclohexanone. Thereafter, the mixture was filtered with a polytetrafluoroethylene-made microfilter (pore size: 0.1 μm), to thereby prepare a resist underlayer film-forming composition solution.
4.65 g of a resin solution of the polymer (3) produced in Comparative Synthesis Example 1 was mixed with 1.11 g of propylene glycol monomethyl ether containing 2% pyridinium p-hydroxybenzenesulfonate, 0.22 g of tetramethoxymethyl glycoluril, 0.11 g of propylene glycol monomethyl ether acetate containing 1% surfactant available from DIC Corporation, product name: MEGAFACE [trade name] R-40, fluorine-containing surfactant), 5.89 g of propylene glycol monomethyl ether acetate, and 3.01 g of propylene glycol monomethyl ether. Thereafter, the mixture was filtered with a polytetrafluoroethylene-made microfilter (pore size: 0.1 μm), to thereby prepare a resist underlayer film-forming composition solution.
2.51 g of a resin solution of the polymer (4) produced in Comparative Synthesis Example 2 was mixed with 0.60 g of propylene glycol monomethyl ether containing 2% TAG2689 (available from King Industries Inc., thermal acid generator), 0.18 g of TMOM-BP (available from Honshu Chemical Industry Co., Ltd., crosslinking agent), 0.06 g of propylene glycol monomethyl ether acetate containing 1% surfactant (available from DIC Corporation, product name: MEGAFACE [trade name] R-40, fluorine-containing surfactant), 4.47 g of propylene glycol monomethyl ether acetate, and 2.17 g of propylene glycol monomethyl ether. Thereafter, the mixture was filtered with a polytetrafluoroethylene-made microfilter (pore size: 0.1 μm), to thereby prepare a resist underlayer film-forming composition solution.
Each of the resist underlayer film-forming compositions prepared in Example 1 to Comparative Example 2 was applied onto a silicon wafer with a spinner. Thereafter, the composition was baked on a hot plate at 240° C. for one minute, to thereby form a resist underlayer film (thickness: 0.2 μm). The resist underlayer film was immersed in a solvent used for a photoresist solution PGME/PGMEA mixed solvent (mixing ratio by mass: 70/30), and the film was found to be insoluble in the solvent. The results correspond to “◯” shown in Table 1 below.
Each of the resist underlayer film-forming compositions prepared in Example 1 to Comparative Example 2 was applied onto a silicon wafer with a spinner. Thereafter, the composition was baked on a hot plate at 240° C. for one minute, to thereby form a resist underlayer film (thickness: 0.2 μm). Subsequently, the refractive index (n value) and attenuation coefficient (k value) of the resist underlayer film were measured at a wavelength of 193 nm with an optical ellipsometer (VUV-VASE VU-302, available from J. A. Woollam). The results are shown in Table 1 below. The n value and k value at a wavelength of 193 nm are preferably 1.40 to 1.65 and 0.1 to 0.45, respectively in view that the resist underlayer film has a sufficient anti-reflective function.
Each of the resist underlayer film-forming composition solutions prepared in Example 1 to Comparative Example 2 was applied onto a silicon wafer having a silicon oxide coating film by using a spin coater. The composition solution was baked on a hot plate at 240° C. for 60 seconds, to thereby form a resist underlayer film (thickness: 200 nm). A silicon hard mask-forming composition solution was applied onto the resist underlayer film, and the composition solution was baked at 240° C. for one minute, to thereby form a silicon hard mask layer (thickness: 30 nm). A resist solution was applied onto the silicon hard mask layer and baked at 100° C. for one minute, to thereby form a resist layer (thickness: 150 nm). The resist layer was exposed through a mask to light having a wavelength of 193 nm, and thermal PEB was performed (at 105° C. for one minute) after the light exposure, followed by development, to thereby form a resist pattern. Thereafter, dry etching was performed with a fluorine-containing gas and an oxygen-containing gas, to thereby transfer the resist pattern onto the silicon wafer having the silicon oxide coating film. Thereafter, the pattern shape was observed with a CG-4100 available from Hitachi High-Technologies Corporation.
When a resist pattern is formed on a to-be-processed substrate through a lithographic process and an etching process, irregular bending of the pattern tends to occur in association with a decrease in the width of the formed pattern. Specifically, this phenomenon corresponds to left-to-right bending of a pattern (in particular, a pattern formed from an organic resin layer) on a resist underlayer film used as a mask material during etching of the to-be-processed substrate of interest. The occurrence of this phenomenon leads to failure of an accurate processing of the substrate. Thus, suppression of bending of the pattern enables finer substrate processing. The results are shown in the table below. Rating “×” was given to a sample wherein bending occurred in a resist pattern having a size of 40 nm, whereas rating “◯” was given to a sample wherein bending occurred in a resist pattern having a size of less than 40 nm. As shown in the table, the bending resistance is high in Examples 1 and 2, but the bending resistance is low in Comparative Examples 1 and 2.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-043846 | Mar 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/010341 | 3/9/2022 | WO |
