Patent Application
20250226218
The present disclosure relates to a film forming method, an article manufacturing method, and a curable composition.
For semiconductor devices and MEMS, requirements of micronization are increasing, and as a micropatterning technique, an imprint technique (optical imprint technique) has received a great deal of attention as a microfabrication technique. In the imprint technique, a curable composition is cured in a state in which a mold with a fine concave-convex pattern formed on the surface is in contact with the curable composition supplied (applied) onto a substrate. Thus, the pattern of the mold is transferred to the cured film of the curable composition, thereby forming the pattern on the substrate. According to the imprint technique, it is possible to form, on a substrate, a fine pattern (structure) on a several nanometer order (see Japanese Patent No. 6584578).
An example of a pattern forming method using the imprint technique will be described. First, a curable composition in liquid form is discretely dropped (arranged) in a pattern formation region on a substrate. The droplets of the curable composition arranged in the pattern formation region spread on the substrate. This phenomenon is called pre-spreading. Next, a mold is brought into contact with (pressed against) the curable composition on the substrate. Thus, the droplets of the curable composition spread to the whole region of the gap between the substrate and the mold by a capillary phenomenon. This phenomenon is called spreading. Also, by the capillary phenomenon, the curable composition fills concave portions that form the pattern of the mold. This phenomenon is called filling. Note that the time until spreading and filling are completed is called a filling time. If the filling of the curable composition is completed, the curable composition is irradiated with light to cure the curable composition. Then, the mold is released from the cured curable composition on the substrate. By executing these steps, the pattern of the mold is transferred to the curable composition on the substrate, and the pattern of the curable composition is formed. Here, the pattern of the curable composition formed on the substrate includes a residual film. The residual film is a cured film remaining between the substrate and a concave portion of the cured film of the curable composition (a convex portion of the pattern of the mold).
A photolithography step of fabricating a semiconductor device requires planarization of a substrate. For example, in an extreme ultraviolet exposure technique (EUV) as a photolithography technique attracting attention in recent years, the depth of focus at which a projected image is formed decreases as miniaturization advances, so the unevenness on the surface of a substrate to which a curable composition is supplied must be decreased to a few tens of nm or less. Flatness equivalent to that of EUV is required in an imprint technique as well, in order to improve the filling properties of a curable composition and the line width accuracy (see Proc. SPIE 11324-11 (2020)). As a planarization technique, there is known a technique of obtaining a flat surface by discretely dropping, on an uneven substrate, droplets of a curable composition in an amount corresponding to the unevenness, and curing the curable composition in a state in which a mold having a flat surface is in contact with the curable composition (see Japanese Patent Laid-Open No. 2019-140394 and US-2020-0286740).
In the pattern forming method or planarization technique using the imprint technique, since the mold is brought into contact in a state in which the droplets of the curable composition dropped onto the substrate are not in contact with each other, bubbles may be entrapped between the mold, the substrate, and the curable composition. A long time is needed until the bubbles are diffused to the mold or the substrate and disappear, and this is one of factors for lowering productivity (throughput). Hence, there is provided bonding the droplets of the curable composition to each other before the curable composition on the substrate and the mold are brought into contact with each other (see Japanese Patent Laid-Open No. 2010-530641 and Japanese Patent Laid-Open No. 2022-188736).
However, in the technique described in Japanese Patent Laid-Open No. 2022-188736, after the droplets of the curable composition spread to such an extent that the droplets bond to each other, the curable composition needs to be filled up to an end portion of the contact region between the mold and the substrate by bringing the mold into contact with the curable composition. Filling the curable composition up to the end portion of the contact region between the mold and the substrate is called edge filling. The speed of edge filling is called an edge filling speed. In the pattern forming method or planarization technique using the imprint technique, since the mold is brought into contact with the droplets of the curable composition on the substrate, time is required until the curable composition is filled up to an end portion of a desired region, and this is one of factors for lowering productivity (throughput). Also, in some cases, edge filling excessively progresses, and the curable composition protrudes from an edge and crawls up the side wall of the mold. The cured product of the curable composition adhered to the side wall remains as an unnecessary cured product on the substrate, remains on the mold side wall and drops to the substrate at an unexpected timing after the next shot, or causes a large defect on the substrate. The phenomenon that the curable composition crawls up the side wall of the mold will be referred to as “extrusion” hereinafter. Time until the curable composition spreads to the whole contact region between the substrate and the mold and extrudes from the contact surface of the mold, and the height of the curable composition crawling up the side wall of the mold reaches 50 nm will be referred to as an “extrusion grace time”.
In the technique described in Japanese Patent Laid-Open No. 2022-188736, it is necessary to simultaneously achieve the edge filling speed and extrusion suppression.
The present disclosure provides a technique advantageous in simultaneously achieving the edge filling speed and extrusion suppression.
The present invention in its one aspect provides a film forming method of forming a film of a curable composition on a substrate using a mold, including discretely arranging a plurality of droplets of the curable composition on the substrate, after the arranging, bringing the plurality of droplets on the substrate and the mold into contact with each other, thereby forming a liquid film between the substrate and the mold, after the bringing the droplets and the mold into contact with each other, curing the liquid film, thereby forming a cured film, and after the curing, separating the cured film and the mold from each other, wherein a viscosity μ [mPa·s] of a nonvolatile composition in the curable composition and an average liquid film thickness h [m] formed by the nonvolatile composition have values satisfying
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Hereinafter, embodiments will be described in detail with reference to the attached drawings. Note, the following embodiments are not intended to limit the scope of the claimed invention. Multiple features are described in the embodiments, but limitation is not made to an invention that requires all such features, and multiple such features may be combined as appropriate. Furthermore, in the attached drawings, the same reference numerals are given to the same or similar configurations, and redundant description thereof is omitted.
A curable composition (A) of the present disclosure can be a curable composition for inkjet. The curable composition (A) of the present disclosure is a composition containing at least a component (a) as a polymerizable compound, and a component (b) as a photopolymerization initiator. Also, the curable composition (A) of the present disclosure may contain a component (d) as a solvent. In this specification, a nonvolatile composition (A′) is a composition made of the component (a), the component (b), and the component (c), which remains after the component (d) that is the solvent of the curable composition (A) volatilizes. Note that the “component (d)” may be referred to as the “solvent (d)” hereinafter.
In this specification, a cured film means a film cured by polymerizing the curable composition on a substrate. Note that the shape of the cured film is not particularly limited, so the film can have a pattern shape on the surface. Also, a cured film remaining between a recessed portion of the cured film of the curable composition (a projecting portion of a mold pattern) and the substrate will be called a residual film.
The component (a) is a polymerizable compound. In this specification, the polymerizable compound is a compound that reacts with a polymerizing factor (for example, a radical) generated from a polymerization initiator (the component (b)), and forms a film made of a polymer compound by a chain reaction (polymerization reaction).
An example of the polymerizable compound as described above is a radical polymerizable compound. The polymerizable compound as the component (a) can be formed by only one type of a polymerizable compound, and can also be formed by a plurality of types of polymerizable compounds.
Examples of the radical polymerizable compound are a (meth)acrylic compound, a styrene-based compound, a vinyl-based compound, an allylic compound, a fumaric compound, and a maleic compound.
The (meth)acrylic compound is a compound having one or more acryloyl groups or methacryloyl groups. Examples of a monofunctional (meth)acrylic compound having one acryloyl group or methacryloyl group are as follows, but the compound is not limited to these examples.
Phenoxyethyl (meth)acrylate, phenoxy-2-methylethyl (meth)acrylate, phenoxyethoxyethyl (meth)acrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate, 2-phenylphenoxyethyl (meth)acrylate, 4-phenylphenoxyethyl (meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate, (meth)acrylate of EO-modified p-cumylphenol, 2-bromophenoxyethyl (meth)acrylate, 2,4-dibromophenoxyethyl (meth)acrylate, 2,4,6-tribromophenoxyethyl (meth)acrylate, EO-modified phenoxy (meth)acrylate, PO-modified phenoxy (meth)acrylate, polyoxyethylenenonylphenylether (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, bornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-butylcyclohexyl(meth)acrylate, acryloylmorpholine, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, benzyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethyleneglycol (meth)acrylate, polyethyleneglycol mono(meth)acrylate, polypropyleneglycol mono(meth)acrylate, methoxyethyleneglycol (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypolyethyleneglycol (meth)acrylate, methoxypolypropyleneglycol (meth)acrylate, diacetone (meth)acrylamide, isobutoxymethyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, t-octyl (meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 7-amino-3,7-dimethyloctyl (meth)acrylate, N,N-diethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, 1- or 2-naphthyl (meth)acrylate, 1- or 2-naphthylmethyl (meth)acrylate, 3- or 4-phenoxybenzyl (meth)acrylate, cyanobenzyl (meth)acrylate, naphthalene methyl (meth)acrylate.
Examples of commercially available products of the above-described monofunctional (meth)acrylic compounds are as follows, but the products are not limited to these examples.
ARONIX® M101, M102, M110, M111, M113, M117, M5700, TO-1317, M120, M150, and M156 (manufactured by TOAGOSEI); MEDOL10, MIBDOL10, CHDOL10, MMDOL30, MEDOL30, MIBDOL30, CHDOL30, LA, IBXA, 2-MTA, HPA, and Viscoat #150, #155, #158, #190, #192, #193, #220, #2000, #2100, and #2150 (manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY); Light Acrylate BO-A, EC-A, DMP-A, THF-A, HOP-A, HOA-MPE, HOA-MPL, PO-A, P-200A, NP-4EA, NP-8EA, Epoxy Ester M-600A, POB-A, and OPP-EA (manufactured by KYOEISHA CHEMICAL); KAYARAD® TC110S, R-564, and R-128H (manufactured by NIPPON KAYAKU); NK Ester AMP-10G, AMP-20G, and A-LEN-10 (manufactured by SHIN-NAKAMURA CHEMICAL); FA-511A, 512A, and 513A (manufactured by Hitachi Chemical); PHE, CEA, PHE-2, PHE-4, BR-31, BR-31M, and BR-32 (manufactured by DKS); VP (manufactured by BASF); ACMO, DMAA, and DMAPAA (manufactured by Kohjin); and HRD-01 (manufactured by NIPPON SHOKUBAI).
Examples of a polyfunctional (meth)acrylic compound having two or more acryloyl groups or methacryloyl groups are as follows, but the compound is not limited to these examples.
Trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, EO- and PO-modified trimethylolpropane tri(meth)acrylate, dimethylol tricyclodecane di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,3-adamantanedimethanol di(meth)acrylate, tris(2-hydoxyethyl)isocyanurate tri(meth)acrylate, tris(acryloyloxy)isocyanurate, bis(hydroxymethyl)tricyclodecane di(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, EO-modified 2,2-bis(4-((meth)acryloxy)phenyl)propane, PO-modified 2,2-bis(4-((meth)acryloxy)phenyl)propane, EO- and PO-modified 2,2-bis(4-((meth)acryloxy)phenyl)propane, o-, m-, or p-benzene di(meth)acrylate, and o-, m-, or p-xylylene di(meth)acrylate.
Examples of commercially available products of the above-described polyfunctional (meth)acrylic compounds are as follows, but the products are not limited to these examples.
Yupimer® UV SA1002 and SA2007 (manufactured by Mitsubishi Chemical); Viscoat #195, #230, #215, #260, #335HP, #295, #300, #360, #700, GPT, and 3PA (manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY); Light Acrylate 4EG-A, 9EG-A, NP-A, DCP-A, BP-4EA, BP-4PA, TMP-A, PE-3A, PE-4A, and DPE-6A (manufactured by KYOEISHA CHEMICAL); KAYARAD® PET-30, TMPTA, R-604, DPHA, DPCA-20, -30, -60, and -120, HX-620, D-310, and D-330 (manufactured by NIPPON KAYAKU); ARONIX® M208, M210, M215, M220, M240, M305, M309, M310, M315, M325, and M400 (manufactured by TOAGOSEI); Ripoxy® VR-77, VR-60, and VR-90 (manufactured by Showa Highpolymer); OGSOL EA-0200 and OGSOL EA-0300 (manufactured by Osaka Gas Chemicals); and SR295 and SR355 (manufactured by Sartomer).
Note that in the above-described compound county, (meth)acrylate means acrylate or methacrylate having an alcohol residue equal to acrylate. A (meth)acryloyl group means an acryloyl group or a methacryloyl group having an alcohol residue equal to the acryloyl group. EO indicates ethylene oxide, and an EO-modified compound A indicates a compound in which a (meth)acrylic acid residue and an alcohol residue of a compound A bond via the block structure of an ethylene oxide group. Also, PO indicates a propylene oxide, and a PO-modified compound B indicates a compound in which a (meth)acrylic acid residue and an alcohol residue of a compound B bond via the block structure of a propylene oxide group.
Practical examples of the styrene-based compound are as follows, but the compound is not limited to these examples.
Alkylstyrene such as styrene, 2,4-dimethyl-α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 2,6-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene, 2,4,5-trimethylstyrene, pentamethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene 2,4-diisopropylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; styrene halide such as fluorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, o-bromostyrene, m-bromostyrene, p-bromostyrene, dibromostyrene, and iodostyrene; and a compound having a styryl group as a polymerizable functional group, such as nitrostyrene, acetylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2-vinylbiphenyl, 3-vinylbiphenyl, 4-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, 4-vinyl-p-terphenyl, 1-vinylanthracene, α-methylstyrene, o-isopropenyltoluene, m-isopropenyltoluene, p-isopropenyltoluene, 2,3-dimethyl-α-methylstyrene, 3,5-dimethyl-α-methylstyrene, p-isopropyl-α-methylstyrene, α-ethylstyrene, α-chlorostyrene, divinylbenzene, diisopropylbenzene, and divinylbiphenyl.
Practical examples of the vinyl-based compound are as follows, but the compound is not limited to these examples.
Vinylpyridine, vinylpyrrolidone, vinylcarbazole, vinyl acetate, and acrylonitrile; conjugated diene monomers such as butadiene, isoprene, and chloroprene; vinyl halide such as vinyl chloride and vinyl bromide; a compound having a vinyl group as a polymerizable functional group, for example, vinylidene halide such as vinylidene chloride, vinyl ester of organic carboxylic acid and its derivative (for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, and divinyl adipate), and (meth)acrylonitrile.
Note that in this specification, (meth)acrylonitrile is a general term for acrylonitrile and methacrylonitrile.
Examples of the allylic compound are as follows, but the compound is not limited to these examples.
Allyl acetate, allyl benzoate, diallyl adipate, diallyl terephthalate, diallyl isophthalate, and diallyl phthalate.
Examples of the fumaric compound are as follows, but the compound is not limited to these examples.
Dimethyl fumarate, diethyl fumarate, diisopropyl fumarate, di-sec-butyl fumarate, diisobutyl fumarate, di-n-butyl fumarate, di-2-ethylhexyl fumarate, and dibenzyl fumarate.
Examples of the maleic compound are as follows, but the compound is not limited to these examples.
Dimethyl maleate, diethyl maleate, diisopropyl maleate, di-sec-butyl maleate, diisobutyl maleate, di-n-butyl maleate, di-2-ethylhexyl maleate, and dibenzyl maleate.
Other examples of the radical polymerizable compound are as follows, but the compound is not limited to these examples.
Dialkylester of itaconic acid and its derivative (for example, dimethyl itaconate, diethyl itaconate, diisopropyl itaconate, di-sec-butyl itaconate, diisobutyl itaconate, di-n-butyl itaconate, di-2-ethylhexyl itaconate, and dibenzyl itaconate), an N-vinylamide derivative of organic carboxylic acid (for example, N-methyl-N-vinylacetamide), and maleimide and its derivative (for example, N-phenylmaleimide and N-cyclohexylmaleimide).
If the component (a) is formed by a plurality of types of compounds having one or more polymerizable functional groups, both a monofunctional polymerizable compound and a polyfunctional polymerizable compound are preferably included. The ratio of the polyfunctional polymerizable compound in the component (a) is preferably 20 wt % or more, more preferably 25 wt % or more, and particularly preferably 40 wt % or more. This is because if a monofunctional compound and a polyfunctional compound are combined, a cured film having well-balanced performance, for example, a high mechanical strength, a high dry etching resistance, and a high heat resistance can be obtained.
The film forming method of the present disclosure requires a few milliseconds to a few hundreds of seconds until droplets of the curable composition (A) discretely arranged on a substrate combine with each other and form a practically continuous liquid film, so a waiting step (to be described later) is necessary. In this waiting step, the solvent (d) is volatilized, but the polymerizable compound (a) must not be volatilized. Accordingly, the boiling points of one or more types of polymerizable compounds included in the polymerizable compound (a) at normal pressure are preferably 250° C. or more, more preferably 300° C. or more, and further preferably 350° C. or more. Also, to obtain a high dry etching resistance and a high heat resistance, the cured film of the curable composition (A) preferably contains at least a compound having a cyclic structure such as an aromatic structure, an aromatic heterocyclic structure, or an alicyclic structure. Note that the normal pressure is 1 atm (atmospheric pressure).
The boiling point of the polymerizable compound (a) is almost correlated with the molecular weight. Therefore, the molecular weights of one or more types of polymerizable compounds included in the polymerizable compound (a) are preferably 200 or more, more preferably 240 or more, and further preferably 250 or more. However, even when the molecular weight is 200 or less, the compound is preferably usable as the polymerizable compound (a) of the present disclosure if the boiling point is 250° C. or more. As described above, the boiling points of one or more types of polymerizable compounds included in the polymerizable compound (a) are preferably 250° C. or more at normal pressure.
In addition, the vapor pressure at 80° C. and at 1 atm of the polymerizable compound (a) is preferably 0.001 mmHg or less. If the polymerizable compound (a) includes one or more types of polymerizable compounds, the vapor pressures of the one or more types of polymerizable compounds at 80° C. and at 1 atm are preferably 0.001 mmHg or less. This is so because, although it is favorable to heat the curable composition when accelerating volatilization of the solvent (component (d)) (to be described later), it is necessary to suppress volatilization of the polymerizable compound (a) during heating.
Note that the boiling point and the vapor pressure of each of various kinds of organic compounds at normal pressure can be calculated by, for example, Hansen Solubility Parameters in Practice (HSPiP) 5th Edition. 5.3.04.
<Ohnishi Parameter of Component (a)>
It is known that a dry etching rate V of an organic compound, a number N of all atoms in the organic compound (in a molecule), a number NC of all carbon atoms in a composition (in the molecule), and a number NO of all oxygen atoms in the composition (in the molecule) have a relationship of equation (1) below (see NPL 1).
where N/(NC−NO) is also called “Ohnishi Parameter” (to be referred to as “OP” hereinafter). For example, US-2020-0286740 has disclosed a technique of obtaining a photocurable composition having a high dry etching resistance by using a polymerizable compound having a small OP.
Equation (1) indicates that an organic compound having many oxygen atoms in a molecule or having few aromatic ring structures or alicyclic structures has a large OP and a high dry etching rate.
In the curable composition (A) according to the present disclosure, the OP of the component (a) is 1.80 or more and 4.00 or less. The OP of the component (a) is more preferably 2.00 or more and 3.50 or less, and particularly preferably 2.40 or more and 3.00 or less. When the OP of the component (a) is 4.00 or less, the cured film of the curable composition (A) has a high dry etching resistance. Also, when the OP of the component (a) is 1.80 or more, the cured film of the curable composition (A) can easily be removed when the underlayer is processed by using the cured film of the curable composition (A). When the component (a) is formed by a plurality of types polymerizable compounds a1, a2, . . . , an, the OP is calculated as a weighted average value (molar fraction weighted average value) based on the molar fraction as indicated by equation (2) below. If the component (a) contains one or more types of polymerizable compounds, the OP of the component (a) can be calculated as the molar fraction weighted average value of an N/(NC−NO) value of each molecule of the one or more types of polymerizable compounds.
where OP1 is the OP of the component an, and nn is the molar fraction occupied by the component an in the entire component (a).
To set the OP of the component (a) to 1.80 or more and 2.70 or less, a compound (a-1) having two or more cyclic structures, in which at least one of the cyclic structures is an aromatic structure or an aromatic heterocyclic structure, is preferably contained at least as the component (a).
<Compound (a-1): Polymerizable Compound Having Aromatic Structure, Aromatic Heterocyclic Structure, or Alicyclic Structure>
The polymerizable compound (a) according to the present disclosure may contain a polymerizable compound (a-1) having an aromatic structure, an aromatic heterocyclic structure, or an alicyclic structure. Also, the ratio of the component (a-1) in the component (a) is preferably 65 wt % or more. When the ratio of the component (a-1) is 65 wt % or more, the OP can be suppressed to 2.70 or less.
Examples of the cyclic structure are an aromatic structure, an aromatic heterocyclic structure, and an alicyclic structure.
The carbon number of the aromatic structure is preferably 6 to 22, more preferably 6 to 18, and further preferably 6 to 10. Practical examples of the aromatic ring are as follows.
A benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a phenalene ring, a fluorene ring, a benzocyclooctene ring, an acenaphthylene ring, a biphenylene ring, an indene ring, an indane ring, a triphenylene ring, a pyrene ring, a chrysene ring, a perylene ring, and a tetrahydronaphthalene ring.
Note that, of the above-described aromatic rings, a benzene ring or a naphthalene ring is preferable, and a benzene ring is more preferable. The aromatic ring can have a structure in which a plurality of rings are connected. Examples are a biphenyl ring and a bisphenyl ring.
The carbon number of the aromatic heterocyclic structure is preferably 1 to 12, more preferably 1 to 6, and further preferably 1 to 5. Practical examples of the aromatic heterocycle are as follows.
A thiophene ring, a furan ring, a pyrolle ring, an imidazole ring, a pyrazole ring, a triazole ring, a tetrazole ring, a thiazole ring, a thiadiazole ring, an oxadiazole ring, an oxazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, pyridazine ring, an isoindole ring, an indole ring, an indazole ring, a purine ring, a quinolizine ring, an isoquinoline ring, a quinoline ring, a phthalazine ring, a naphthyridine ring, a quinoxaline ring, a quinazoline ring, a cinnoline ring, a carbazole ring, an acridine ring, a phenazine ring, a phenothiazine ring, a phenoxathiine ring, and a phenoxazine ring.
The carbon number of the alicyclic structure is preferably 3 or more, more preferably 4 or more, and further preferably 6 or more. In addition, the carbon number of the alicyclic structure is preferably 22 or less, more preferably 18 or less, further preferably 6 or less, and still further preferably 5 or less. Practical examples are as follows.
A cyclopropane ring, a cyclobutane ring, a cyclobutene ring, a cyclopentane ring, a cyclohexane ring, a cyclohexene ring, a cycloheptane ring, a cyclooctane ring, a dicyclopentadiene ring, a spirodecane ring, a spirononane ring, a tetrahydro dicyclopentadiene ring, an octahydronaphthalene ring, a decahydronaphthalene ring, a hexahydroindane ring, a bornane ring, a norbornane ring, a norbornene ring, an isobornane ring, a tricyclodecane ring, a tetracyclododecane ring, and an adamantane ring.
Practical examples of the polymerizable compound (a-1) having a boiling point of 250° C. or more are as follows, but the compound is not limited to these examples.
3-phenoxybenzyl acrylate (mPhOBzA, OP=2.54, boiling point=367.4° C., 80° C. vapor pressure=0.0004 mmHg, molecular weight=254.3)
1-naphthyl acrylate (NaA, OP=2.27, boiling point=317° C., 80° C. vapor pressure=0.0422 mmHg, molecular weight=198)
2-phenylphenoxyethyl acrylate (PhPhOEA, OP=2.57, boiling point=364.2° C., 80° C. vapor pressure=0.0006 mmHg, molecular weight=268.3)
1-naphthylmethyl acrylate (NalMA, OP=2.33, boiling point=342.1° C., 80° C. vapor pressure=0.042 mmHg, molecular weight=212.2)
2-naphthylmethyl acrylate (Na2MA, OP=2.33, boiling point=342.1° C., 80° C. vapor pressure=0.042 mmHg, molecular weight=212.2)
DPhPA indicated by the formula below (OP=2.38, boiling point=354.5° C., 80° C. vapor pressure=0.0022 mmHg, molecular weight=266.3)
PhBzA indicated by the formula below (OP=2.29, boiling point=350.4° C., 80° C. vapor pressure=0.0022 mmHg, molecular weight=238.3)
FLMA indicated by the formula below (OP=2.20, boiling point=349.3° C., 80° C. vapor pressure=0.0018 mmHg, molecular weight=250.3)
ATMA indicated by the formula below (OP=2.13, boiling point=414.9° C., 80° C. vapor pressure=0.0001 mmHg, molecular weight=262.3)
DNaMA indicated by the formula below (OP=2.00, boiling point=489.4° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=338.4)
BPh44DA indicated by the formula below (OP=2.63, boiling point=444° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=322.3)
BPh43DA indicated by the formula below (OP=2.63, boiling point=439.5° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=322.3)
DPhEDA indicated by the formula below (OP=2.63, boiling point=410° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=322.3)
BPMDA indicated by the formula below (OP=2.68, boiling point=465.7° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=364.4)
Na13MDA indicated by the formula below (OP=2.71, boiling point=438.8° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=296.3)
Formula below (a-1-1) (OP=2.40, boiling point=333.4° C., 80° C. vapor pressure=0.0181 mmHg, molecular weight=199.2)
Formula below (a-1-2) (OP=2.40, boiling point=333.4° C., 80° C. vapor pressure=0.0181 mmHg, molecular weight=199.2)
Formula below (a-1-3) (OP=1.86, boiling point=369.5° C., 80° C. vapor pressure=0.0053 mmHg, molecular weight=193.3)
Formula below (a-1-4) (OP=2.85, boiling point=438.8° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=296.3)
Formula below (a-1-5) (OP=2.71, boiling point=438.8° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=296.3)
Formula below (a-1-6) (OP=2.87, boiling point=421.0° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=338.4)
Formula below (a-1-7) (OP=2.87, boiling point=465.2° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=338.4)
Formula below (a-1-8) (OP=2.68, boiling point=465.7° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=364.4)
Formula below (a-1-9) (OP=2.50, boiling point=433.1° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=320.3)
Formula below (a-1-10) (OP=2.64, boiling point=468.1° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=326.4)
Formula below (a-1-11) (OP=3.25, boiling point=553.4° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=358.4)
Formula below (a-1-12) (OP=2.63, boiling point=443.9° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=322.4)
Formula below (a-1-13) (OP=2.89, boiling point=509.3° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=406.4)
Formula below (a-1-14) (OP=2.63, boiling point=450.0° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=322.4)
Formula below (a-1-15) (OP=3.00, boiling point=476.5° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=366.4)
Formula below (a-1-16) (OP=2.68, boiling point=447.4° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=364.4)
Formula below (a-1-17) (OP=2.36, boiling point=543.8° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=398.5)
Formula below (a-1-18) (OP=3.27, boiling point=526.9° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=396.4)
Formula below (a-1-19) (OP=2.71, boiling point=333.7° C., 80° C. vapor pressure=0.0302 mmHg, molecular weight=244.3)
Formula below (a-1-20) (OP=2.73, boiling point=333.7° C., 80° C. vapor pressure=0.0134 mmHg, molecular weight=258.3)
Formula below (a-1-21) (OP=2.71, boiling point=319.2° C., 80° C. vapor pressure=0.0566 mmHg, molecular weight=262.3)
Formula below (a-1-22) (OP=2.71, boiling point=336.9° C., 80° C. vapor pressure=0.0055 mmHg, molecular weight=244.3)
Formula below (a-1-23) (OP=3.00, boiling point=370.9° C., 80° C. vapor pressure=0.0021 mmHg, molecular weight=274.4)
Formula below (a-1-24) (OP=3.00, boiling point=376.4° C., 80° C. vapor pressure=0.0005 mmHg, molecular weight=274.4)
Formula below (a-1-25) (OP=3.00, boiling point=379.4° C., 80° C. vapor pressure=0.0002 mmHg, molecular weight=288.4)
Formula below (a-1-26) (OP=2.33, boiling point=360.8° C., 80° C. vapor pressure=0.0006 mmHg, molecular weight=252.3)
Formula below (a-1-27) (OP=2.54, boiling point=371.5° C., 80° C. vapor pressure=0.0003 mmHg, molecular weight=254.3)
Formula below (a-1-28) (OP=2.57, boiling point=381.2° C., 80° C. vapor pressure=0.0001 mmHg, molecular weight=268.3)
Formula below (a-1-29) (OP=2.57, boiling point=381.8° C., 80° C. vapor pressure=0.0004 mmHg, molecular weight=268.3)
Formula below (a-1-30) (OP=2.50, boiling point=487.4° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=374.4
Formula below (a-1-31) (OP=2.67, boiling point=417.2° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=268.3)
Formula below (a-1-32) (OP=2.67, boiling point=417.2° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=268.3)
Formula below (a-1-33) (OP=2.67, boiling point=417.2° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=268.3)
Formula below (a-1-34) (OP=2.67, boiling point=417.2° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=268.3)
Formula below (a-1-35) (OP=2.71, boiling point=438.8° C., 80° C. vapor pressure <0.0001 mmHg, molecular weight=296.3)
<Compound (a-2): Polymerizable Compound Containing at Least Si Atoms>
The polymerizable compound (a) according to the present disclosure may contain a polymerizable compound (a-2) containing at least Si atoms. Furthermore, if the polymerizable compound (a) contains the polymerizable compound (a-2), the curable composition (A) from which the solvent (d) is removed preferably contains Si atoms of 10 wt % or more with respect to the whole curable composition (A).
As an example of the polymerizable compound (a-2) containing at least Si atoms, it may have a linear structure or a branched structure. For example, as cyclic siloxane compounds, the following structures can be used. An example of a polymerizable functional group in a group Q having a polymerizable functional group is a radical polymerizable functional group. Practical examples of the radical polymerizable functional group are a (meth)acrylic group, a (meth)acrylamide group, a vinylbenzene group, an allyl ether group, a vinylether group, and a maleimide group. The group Q having a polymerizable functional group need only be a group having the above-described polymerizable functional group.
Other examples of the polymerizable compound (a-2) are a silsesquioxane skeleton as indicated by chemical formula (I) below and a silicone skeleton as indicated by chemical formula (II). In chemical formula (I), m+n=8 (8≥m≥1), and R1 is a bivalent organic group. Additionally, in chemical formula (II), A, B, R2, and R3 are independently an alkyl group, a cycloalkyl group, an alkoxy group, a phenyl group, and hydroxyl group whose carbon number is 1 to 6, t is an integer of 1 to 3, and at least one of A and B is a polymerizable functional group.
An example of a polymerizable functional group in groups Q, A, and B having a polymerizable functional group is a radical polymerizable functional group. Detailed examples of the radical polymerizable functional group are a (meth)acrylate-based compound, a (meth)acrylamide-based compound, a vinylbenzene-based compound, an aryl ether-based compound, a vinyl ether-based compound, and a maleimide-based compound. The group Q having a polymerizable functional group can be a group having the above-described polymerizable functional group.
A silicon-containing (meth)acrylate-based compound is a compound having one or more acryloyl groups or methacryloyl groups. Examples of a silicon-containing monofunctional (meth)acrylate-based compound having one acryloyl group or methacryloyl group are as follows, but the compound is not limited to these examples.
Examples of the commercially available products of the above-described silicon-containing monofunctional (meth)acrylic compounds are as follows, but the products are not limited to these examples.
SIA0160.0, SIA0180.0, SIA0182.0, SIA0184.0, SIA0186.0, SIA0190.0, SIA0194.0, SIA0196.0, SIA0197.0, SIA0198.0, SIA0199.0, SIA0200.0, SIA0200.A1, SIA0210.0, SIA0315.0, SIA0320.0, SIM6483.0, SIM6487.5, SIM6480.76, SIM6481.2, SIM6486.1, SIM6481.1, SIM6481.46, SIM6481.43, SIM6482.0, SIM6487.4, SIM6487.35, SIM6480.8, SIM6486.9, SIM6486.8, SIM6486.5, SIM6486.4, SIM6481.3, SIM6487.3, SIM6487.1, SIM6487.6, SIM6486.14, SIM6481.48, SIM6481.5, SIM6491.0, SIM6485.6, SIM6481.15, SIM6487.0, SIM6481.05, SIM6485.8, SIM6481.0, SIM6487.4LI, SIM6481.16, SIM6487.8, SIM6487.6HP, SIM6487.17, SIM6486.7, SIM6487.2, SIM6486.0, SIM6486.2, SIM6487.6-06, SIM6487.6-20, SIM6485.9, SST-R8C42, SLT-3R01, and SIM6486.65 (manufactured by GELEST), and TM-0701T, FM-0711, FM-0721, and FM-0725 (manufactured by JNC)
A silicon-containing (meth)acrylamide-based compound is a compound having one or more acrylamide groups or methacrylamide groups. Examples of a silicon-containing monofunctional (meth)acrylamide-based compound having one acrylamide group or methacrylamide group are as follows, but the compound is not limited to these examples.
Examples of the commercially available products of the above-described silicon-containing monofunctional (meth)acrylamide compounds are as follows, but the products are not limited to these examples.
Examples of a polyfunctional (meth)acrylate-based compound having two or more acryloyl groups or methacryloyl groups are as follows, but the compound is not limited to these examples.
Examples of the commercially available products of the above-described silicon-containing monofunctional (meth)acrylate compounds are as follows, but the products are not limited to these examples.
Also, according to, for example, “Ultraviolet curable branched siloxanes as low-k dielectrics for imprint lithography” by Ogawa et al., the following can be synthesized and/or obtained.
linear modified polydimethylsiloxane with methacryloxypropyl groups on both ends (MA-Si-12), 8-membered ring siloxane modified with four methacryloxypropyl groups (8-ring), and 10-membered ring siloxane modified with five methacryloxypropyl groups (10-ring).
The blending ratio of the component (a) in the curable composition (A) is preferably 40 wt % or more and 99 wt % or less with respect to the sum of the component (a), a component (b) (to be described later), and a component (c) (to be described later), that is, the total mass of all the components except the solvent (d). The blending ratio is more preferably 50 wt % or more and 95 wt % or less, and further preferably 60 wt % or more and 90 wt % or less. When the blending ratio of the component (a) is 40 wt % or more, the mechanical strength of the cured film of the curable composition increases. Also, when the blending ratio of the component (a) is 99 wt % or less, it is possible to increase the blending ratios of the components (b) and (c), and obtain characteristics such as a high photopolymerization rate. At least a part of the component (a) including one or more types of polymerizable compounds can be polymers having a polymerizable functional group. A polymer like this preferably contains at least a cyclic structure such as an aromatic structure, an aromatic heterocyclic structure, or an alicyclic structure. For example, the polymer preferably contains at least one of constituent units represented by structures (1) to (6) below:
In the structures (1) to (6), a substituent group R is a substituent group containing partial structures each independently containing an aromatic ring, and R1 is a hydrogen atom or a methyl group. In this specification, in constituent units represented by the structures (1) to (6), a portion other than R is the main chain of a specific polymer. The formula weight of the substituent group R is 80 or more, preferably 100 or more, more preferably 130 or more, and further preferably 150 or more. The upper limit of the formula weight of the substituent group R is practically 500 or less.
A polymer having a polymerizable functional group is normally a compound having a weight-average molecular weight of 500 or more. The weight-average molecular weight is preferably 1,000 or more, and more preferably 2,000 or more. The upper limit of the weight-average molecular weight is not particularly determined, but is preferably, for example, 50,000 or less. When the weight-average molecular weight is set at the above-described lower limit or more, it is possible to set the boiling point at 250° C. or more, and further improve the mechanical properties after curing. Also, when the weight-average molecular weight is set at the above-described upper limit or less, the solubility to the solvent increases, and the flowability of discretely arranged droplets is maintained because the viscosity is not too high. This makes it possible to further improve the flatness of the liquid film surface. Note that the weight-average molecular weight (Mw) in the present disclosure is a molecular weight measured by gel permeation chromatography (GPC) unless it is specifically stated otherwise.
Practical examples of the polymerizable functional group of the polymer are a (meth)acryloyl group, an epoxy group, an oxetane group, a methylol group, a methylol ether group, and a vinyl ether group. A (meth)acryloyl group is particularly favorable from the viewpoint of polymerization easiness.
When adding the polymer having the polymerizable functional group as at least a part of the component (a), the blending ratio can freely be set as long as the blending ratio falls within the range of the viscosity regulation to be described later. For example, the blending ratio to the total mass of all the components except for the solvent (d) is preferably 0.1 wt % or more and 60 wt % or less, more preferably 1 wt % or more and 50 wt % or less, and further preferably 10 wt % or more and 40 wt % or less. When the blending ratio of the polymer having the polymerizable functional group is set at 0.1 wt % or more, it is possible to improve the heat resistance, the dry etching resistance, the mechanical strength, and the low volatility. Also, when the blending ratio of the polymer having the polymerizable functional group is set at 60 wt % or less, it is possible to make the blending ratio fall within the range of the upper limit regulation of the viscosity (to be described later).
The component (b) is a photopolymerization initiator. In this specification, the photopolymerization initiator is a compound that senses light having a predetermined wavelength and generates a polymerization factor (radical) described earlier. More specifically, the photopolymerization initiator is a polymerization initiator (radical generator) that generates a radical by light (infrared light, visible light, ultraviolet light, far-ultraviolet light, X-ray, a charged particle beam such as an electron beam, or radiation). The component (b) can be formed by only one type of a photopolymerization initiator, and can also be formed by a plurality of types of photopolymerization initiators.
Examples of the radical generator are as follows, but the radical generator is not limited to these examples.
2,4,5-triarylimidazole dimers that can have substituent groups, such as a 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, a 2-(o-chlorophenyl)-4,5-di(methoxyphenyl)imidazole dimer, a 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, and a 2-(o- or p-methoxyphenyl)-4,5-diphenylimidazole dimer; benzophenone derivatives such as benzophenone, N,N′-tetramethyl-4,4′-diaminobenzophenone (Michiler's ketone), N,N′-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, and 4,4′-diaminobenzophenone; α-amino aromatic ketone derivatives such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-one; quinones such as 2-ethylanthraquinone, phenanthrenequinone, 2-t-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylamthraquinone, 1-chloroanthraquinone, 2-methylanthraquinone, 1,4-naphtoquinone, 9,10-phenanthraquinone, 2-methyl-1,4-naphtoquinone, and 2,3-dimethylanthraquinone; benzoin ether derivatives such as benzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether; benzoin derivatives such as benzoin, methyl benzoin, ethyl benzoin, and propyl benzoin; benzyl derivatives such as benzyldimethylketal; acridine derivatives such as 9-phenylacridine and 1,7-bis(9,9′-acrydinyl)heptane; N-phenylglycine derivatives such as N-phenylglycine; acetophenone derivatives such as acetophenone, 3-methylacetophenone, acetophenone benzylketal, 1-hydroxycylohexyl phenylketone, and 2,2-dimethoxy-2-phenyl acetophenone; thioxanthone derivatives such as thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, and 2-chlorothioxanthone; acylphosphine oxide derivatives such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide; oxime ester derivatives such as 1,2-octanedione, 1-[4-(phenylthiol)-,2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-, and 1-(0-acetyloxime); and xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 1-(4-isopropylphenyl)-2-hydroxy-2-methylprapane-1-one, and 2-hydroxy-2-methyl-1-phenylpropane-1-one.
Examples of commercially available products of the above-described radical generators are as follows, but the products are not limited to these examples.
Irgacure 184, 369, 651, 500, 819, 907, 784, and 2959, CGI-1700, -1750, and -1850, CG24-61, Darocur 1116 and 1173, Lucirin® TPO, LR8893, and LR8970 (manufactured by BASF), and Ubecryl P36 (manufactured by UCB).
Of the above-described radical generators, the component (b) is preferably an acylphosphine oxide-based polymerization initiator. Note that of the above-described radical generators, the acylphosphine oxide-based polymerization initiators are as follows.
Acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.
The blending ratio of the component (b) in the curable composition (A) is preferably 0.1 wt % or more and 50 wt % or less with respect to the sum of the component (a), the component (b), and a component (c) (to be described later), that is, the total mass of all the components except for the solvent (d). Also, the blending ratio of the component (b) in the curable composition (A) is more preferably 0.1 wt % or more and 20 wt % or less, and further preferably 1 wt % or more and 20 wt % or less with respect to the total mass of all the components except for the solvent (d). When the blending ratio of the component (b) is set at 0.1 wt % or more, the curing rate of the composition increases, so the reaction efficiency can be improved. Also, when the blending ratio of the component (b) is set at 50 wt % or less, a cured film having mechanical strength to some extent can be obtained.
In addition to the components (a) and (b) described above, the curable composition (A) of the present disclosure can further contain a nonpolymerizable compound as the component (c) within a range that does not impair the effect of the present disclosure. An example of the component (c) is a compound that does not contain a polymerizable functional group such as a (meth)acryloyl group, and does not have the ability to sense light having a predetermined wavelength and generate the polymerization factor (radical) described previously. Examples of the nonpolymerizable compound are a sensitizer, a hydrogen donor, a surfactant (c1), an antioxidant, a polymer component, and other additives. The component (c) can contain a plurality of types of the above-described compounds.
The sensitizer is a compound that is properly added for the purpose of promoting the polymerization reaction and improving the reaction conversion rate. As the sensitizer, it is possible to use one type of a compound alone, or to use two or more types of compounds by mixing them.
An example of the sensitizer is a sensitizing dye. The sensitizing dye is a compound that is excited by absorbing light having a specific wavelength and has an interaction with a photopolymerization initiator as the component (b). The “interaction” herein mentioned is energy transfer or electron transfer from the sensitizing dye in the excited state to the photopolymerization initiator as the component (b). Practical examples of the sensitizing dye are as follows, but the sensitizing dye is not limited to these examples.
An anthracene derivative, an anthraquinone derivative, a pyrene derivative, a perylene derivative, a carbazole derivative, a benzophenone derivative, a thioxanthone derivative, a xanthone derivative, a coumarin derivative, a phenothiazine derivative, a camphorquinone derivative, an acridinic dye, a thiopyrylium salt-based dye, a merocyanine-based dye, a quinoline-based dye, a styryl quinoline-based dye, a ketocoumarin-based dye, a thioxanthene-based dye, a xanthene-based dye, an oxonol-based dye, a cyanine-based dye, a rhodamine-based dye, and a pyrylium salt-based dye.
The hydrogen donor is a compound that reacts with an initiation radical generated from the photopolymerization initiator as the component (b) or a radical at a polymerization growth end, and generates a radical having higher reactivity. The hydrogen donor is preferably added when the photopolymerization initiator as the component (b) is a photo-radical generator.
Practical examples of the hydrogen donor as described above are as follows, but the hydrogen donor is not limited to these examples.
Amine compounds such as n-butylamine, di-n-butylamine, tri-n-butylphosphine, allylthiourea, s-benzylisothiuronium-p-toluenesulfinate, triethylamine, diethylaminoethyl methacrylate, triethylenetetramine, 4,4′-bis(dialkylamino)benzophenone, N,N-dimethylamino ethylester benzoate, N,N-dimethylamino isoamylester benzoate, pentyl-4-dimethylamino benzoate, triethanolamine, and N-phenylglycine; and mercapto compounds such as 2-mercapto-N-phenylbenzoimidazole and mercapto propionate ester.
It is possible to use one type of a hydrogen donor alone, or to use two or more types of hydrogen donors by mixing them. The hydrogen donor can also have a function as a sensitizer.
An internal mold release agent can be added to the curable composition for the purpose of reducing the interface bonding force between a mold and the curable composition, that is, reducing the mold release force in a mold release step (to be described later). In this specification, “internal” means that the mold release agent is added to the curable composition in advance before a curable composition arranging step. As the internal mold release agent, it is possible to use surfactants such as a silicon-based surfactant, a fluorine-based surfactant, and a hydrocarbon-based surfactant. Note that the internal mold release agent according to the present disclosure is not polymerizable. It is possible to use one type of an internal mold release agent alone, or to use two or more types of internal mold release agents by mixing them.
The fluorine-based surfactant includes the following.
A polyalkylene oxide (for example, polyethylene oxide or polypropylene oxide) adduct of alcohol having a perfluoroalkyl group, and a polyalkylene oxide (for example, polyethylene oxide or polypropylene oxide) adduct of perfluoropolyether.
Note that the fluorine-based surfactant can have a hydroxyl group, an alkoxy group, an alkyl group, an amino group, or a thiol group in a portion (for example, a terminal group) of the molecular structure. An example is pentadecaethyleneglycol mono 1H,1H,2H,2H-perfluorooctylether.
It is also possible to use a commercially available product as the fluorine-based surfactant. Examples of the commercially available product of the fluorine-based surfactant are as follows.
MEGAFACE® F-444, TF-2066, TF-2067, and TF-2068, and DEO-15 (abbreviation) (manufactured by DIC); Fluorad FC-430 and FC-431 (manufactured by Sumitomo 3M); Surflon® S-382 (manufactured by AGC); EFTOP EF-122A, 122B, 122C, EF-121, EF-126, EF-127, and MF-100 (manufactured by Tochem Products); PF-636, PF-6320, PF-656, and PF-6520 (manufactured by OMNOVA Solutions); UNIDYNE® DS-401, DS-403, and DS-451 (manufactured by DAIKIN); and FUTAGENT® 250, 251, 222F, and 208G (manufactured by NEOS).
The surfactant (c1) can also be a hydrocarbon-based surfactant. The hydrocarbon-based surfactant includes an alkyl alcohol polyalkylene oxide adduct obtained by adding alkylene oxide having a carbon number of 2 to 4 to alkyl alcohol having a carbon number of 1 to 50, and polyalkylene oxide.
Examples of the alkyl alcohol polyalkylene oxide adduct are as follows.
A methyl alcohol ethylene oxide adduct, a decyl alcohol ethylene oxide adduct, a lauryl alcohol ethylene oxide adduct, a cetyl alcohol ethylene oxide adduct, a stearyl alcohol ethylene oxide adduct, and a stearyl alcohol ethylene oxide/propylene oxide adduct.
Note that the terminal group of the alkyl alcohol polyalkylene oxide adduct is not limited to a hydroxyl group that can be manufactured by simply adding polyalkylene oxide to alkyl alcohol. This hydroxyl group can also be substituted by a polar functional group such as a carboxyl group, an amino group, a pyridyl group, a thiol group, or a silanol group, or by a hydrophobic group such as an alkyl group or an alkoxy group.
Examples of polyalkylene oxide are as follows.
Polyethylene glycol, polypropylene glycol, their mono or dimethyl ether, mono or dioctyl ether, mono or dinonyl ether, and mono or didecyl ether, monoadipate, monooleate, monostearate, and monosuccinate.
A commercially available product can also be used as the alkyl alcohol polyalkylene oxide adduct. Examples of the commercially available product of the alkyl alcohol polyalkylene oxide adduct are as follows.
Polyoxyethylene methyl ether (a methyl alcohol ethylene oxide adduct) (BLAUNON MP-400, MP-550, and MP-1000) manufactured by AOKI OIL INDUSTRIAL, polyoxyethylene decyl ether (a decyl alcohol ethylene oxide adduct) (FINESURF D-1303, D-1305, D-1307, and D-1310) manufactured by AOKI OIL INDUSTRIAL, polyoxyethylene lauryl ether (a lauryl alcohol ethylene oxide adduct) (BLAUNON EL-1505) manufactured by AOKI OIL INDUSTRIAL, polyoxyethylene cetyl ether (a cetyl alcohol ethylene oxide adduct) (BLAUNON CH-305 and CH-310) manufactured by AOKI OIL INDUSTRIAL, polyoxyethylene stearyl ether (a stearyl alcohol ethylene oxide adduct) (BLAUNON SR-705, SR-707, SR-715, SR-720, SR-730, and SR-750) manufactured by AOKI OIL INDUSTRIAL, randomly polymerized polyoxyethylene polyoxypropylene stearyl ether (BLAUNON SA-50/50 1000R and SA-30/70 2000R) manufactured by AOKI OIL INDUSTRIAL, polyoxyethylene methyl ether (Pluriol® A760E) manufactured by BASF, and polyoxyethylene alkyl ether (EMULGEN series) manufactured by KAO.
A commercially available product can also be used as polyalkylene oxide. An example is an ethylene oxide/propylene oxide copolymer (Pluronic PE6400) manufactured by BASF.
Examples of a silicone surfactant are as follows. For example, product name SI-10 series (manufactured by TAKEMOTO OIL & FAT), MEGAFACE Paintad 31 (manufactured by DIC), and KP-341 (manufactured by Shin-Etsu Chemical) can be used.
The surfactant may contain at least both fluorine atoms and silicone atoms. Examples of the surfactant containing both fluorine atoms and silicone atoms are as follows.
Product names X-70-090, X-70-091, X-70-092, X-70-093 (manufactured by Shin-Etsu Chemical), and product names MEGAFACE R-08 and XRB-4 (manufactured by DIC)
The blending ratio of the component (c) in the curable composition (A) except for the surfactant is preferably 0.01 wt % or more and 50 wt % or less with respect to the sum of the components (a), (b), and (c), that is, the total mass of all the components except for the solvent (d). The blending ratio of the component (c) in the curable composition (A) except for the surfactant is more preferably 0.01 wt % or more and 50 wt % or less, and further preferably 0.01 wt % or more and 20 wt % or less with respect to the total mass of all the components except for the solvent (d). When the blending ratio of the component (c) except for the surfactant is set at 50 wt % or less, a cured film having mechanical strength to some extent can be obtained.
The curable composition (A) of the present disclosure may contain a solvent having a boiling point of 100° C. or more and less than 250° C. at normal pressure as the component (d). The component (d) is a solvent that dissolves the components (a), (b), and (c). Examples are an alcohol-based solvent, a ketone-based solvent, an ether-based solvent, and a nitrogen-containing solvent. As the component (d), it is possible to use one type of a component alone, or to use two or more types of components by combining them. The boiling point at normal pressure of the component (d) is 100° C. or more, preferably 140° C. or more, and particularly preferably 150° C. or more. The boiling point at normal pressure of the component (d) is less than 250° C., and preferably less than 200° C. If the boiling point of the component (d) at normal pressure is less than 100° C., the volatilization speed in the waiting step to be described later is too high. For this reason, the component (d) may volatilize before the droplets of the curable composition (A) bond to each other, and the droplets of the curable composition (A) may not bond to each other. Also, if the boiling point at normal pressure of the component (d) is 250° C. or more, it is possible that the volatilization of the solvent (d) is insufficient in the waiting step to be described later, so the component (d) remains in the cured product of the curable composition (A). Here, if the component (d) includes one or more types of solvents, the boiling point of each of the one or more types of solvents at normal pressure is preferably 100° C. or more and less than 250° C. (for example, 100° C. or more and less than 200° C.).
Examples of the alcohol-based solvent are as follows.
Monoalcohol-based solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethylheptanol-4, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, phenylmethylcarbinol, diacetone alcohol, and cresol; and polyalcohol-based solvents such as ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, and glycerin.
Examples of the ketone-based solvent are as follows.
Acetone, methylethylketone, methyl-n-propylketone, methyl-n-butyketone, diethylketone, methyl-iso-butylketone, methyl-n-pentylketone, ethyl-n-butylketone, methyl-n-hexylketone, di-iso-butylketone, trimethylnonanon, cyclohexanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone, and fenthion.
Examples of the ether-based solvent are as follows.
Ethyl ether, iso-propyl ether, n-butyl ether, n-hexyl ether, 2-ethylhexyl ether, ethylene oxide, 1,2-propylene oxide, dioxolane, 4-methyldioxolane, dioxane, dimethyldioxane, 2-methoxyethanol, 2-ethoxyethanol, ethylene glycol diethyl ether, 2-n-butoxyethanol, 2-n-hexoxyethanol, 2-phenoxyethanol, 2-(2-ethylbutoxy)ethanol, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol di-n-butyl ether, diethylene glycol mono-n-hexyl ether, ethoxy triglycol, tetraethylene glycol di-n-butyl ether, 1-n-butoxy-2-propanol, 1-phenoxy-2-propanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran.
Examples of the ester-based solvent are as follows.
Diethyl carbonate, methyl acetate, ethyl acetate, amyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, methoxy triglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate, and diethyl phthalate.
Examples of the nitrogen-containing solvent are as follows.
N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetoamide, N-methylacetoamide, N,N-dimethylacetoamide, N-methylpropionamide, and N-methylpyrrolidone.
Of the above-described solvents, the ether-based solvent and the ester-based solvent are favorable. Note that an ether-based solvent and an ester-based solvent each having a glycol structure are more favorable from the viewpoint of good film formation properties.
Further favorable examples of the solvent are as follows.
Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monopropyl ether acetate.
A particularly favorable example is propylene glycol monomethyl ether acetate. Note that (ethyl)isocyanurate di(meth)acrylate is also favorable.
In the present disclosure, a favorable solvent is a solvent having at least one of an ester structure, a ketone structure, a hydroxyl group, and an ether structure. More specifically, a favorable solvent is one solvent or a solvent mixture selected from propylene glycol monomethyl ether acetate (boiling point=146° C.), propylene glycol monomethyl ether, cyclohexanone, 2-haptanone, γ-butyrolactone, and ethyl lactate.
In the present disclosure, a polymerizable compound having a boiling point of 80° C. or more and less than 250° C. at normal pressure is also usable as the component (d). Examples of the polymerizable compound having a boiling point of 80° C. or more and less than 250° C. at normal pressure are as follows.
Cyclohexyl acrylate (boiling point=198° C.), benzyl acrylate (boiling point=229° C.), isobornyl acrylate (boiling point=245° C.), tetrahydrofurfuryl acrylate (boiling point=202° C.), trimethylcyclohexyl acrylate (boiling point=232° C.), isooctyl acrylate (217° C.), n-octyl acrylate (boiling point=228° C.), ethoxyethoxyethyl acrylate (boiling point=230° C.), divinylbenzene (boiling point=193° C.), 1,3-diisopropenylbenzene (boiling point=218° C.), styrene (boiling point=145° C.), and α-methylstyrene (boiling point=165° C.).
In the present disclosure, when the whole of the curable composition (A) is 100 vol %, the content of the solvent (d) can be more than 5 vol % and 95 vol % or less, preferably 15 vol % or more and 85 vol % or less, and further preferably 40 vol % or more and 80 vol % or less. For example, the content of the solvent (d) can be 40 vol % or more and 85 vol % or less. If the content of the solvent (d) is smaller than 5 vol %, it is difficult to obtain a thin film after the solvent (d) volatilized under the condition that a practically continuous liquid film can be obtained. On the other hand, if the content of the solvent (d) is larger than 95 vol %, it is difficult to obtain a thick film after the solvent (d) volatilized even when droplets are closely dropped by an inkjet method.
<Temperature when Blending Curable Composition>
When preparing the curable composition (A) of the present disclosure, at least the components (a), (b), and (d) are mixed and dissolved under a predetermined temperature condition. More specifically, the predetermined temperature condition can be 0° C. or more and 100° C. or less. Note that the same applies to a case in which the curable composition (A) contains the component (c).
The curable composition (A) of the present disclosure is a liquid. This is so because droplets of the curable composition (A) are discretely dropped on a substrate by an inkjet method. The viscosity of the curable composition (A) according to the present disclosure is 1.3 mPa·s or more and 60 mPa·s or less at 23° C. and at 1 atm, preferably 2 mPa·s or more and 30 mPa·s or less, and more preferably 5 mPa·s or more and 15 mPa·s or less. If the viscosity of the curable composition (A) is smaller than 2 mPa·s, the discharge property of droplets by an inkjet method may be unstable. Also, if the viscosity of the curable composition (A) is larger than 60 mPa·s, it is difficult to form droplets having a volume of about 1.0 to 3.0 μL favorable in the present disclosure.
The viscosity μ of the nonvolatile composition (A′) according to the present disclosure is preferably 20 mPa·s or more and 135 mPa·s or less at 23° C. and at 1 atm. Also, concerning the nonvolatile composition (A′), the viscosity at 23° C. and at 1 atm is more preferably 40 mPa·s or more and 100 mPa·s or less, and further preferably 60 mPa·s or more and 80 mPa·s or less. Note that if the viscosity is lower, for example, less than 20 mPa·s, the fluidity of the nonvolatile composition (A′) is high, and when the nonvolatile composition (A′) and the mold are brought into contact with each other, the nonvolatile composition (A′) readily flows out from an end portion of the mold, and the extrusion grace time is short. If the viscosity is more than 135 mPa·s, the fluidity of the nonvolatile composition (A′) is low, and the edge filling speed is low when the nonvolatile composition (A′) and the mold are brought into contact with each other. Hence, when the curable composition (A) of the present disclosure obtained by adjusting the viscosity of the nonvolatile composition (A′) to 20 mPa·s or more and 135 mPa·s or less is used, it is possible to execute imprint processing at high throughput and suppress defects on the substrate caused by extrusion.
The surface tension yl of the nonvolatile composition (A′) of the present disclosure is preferably 5 mN/m or more and 70 mN/m or less at 23° C. and at 1 atm. Also, the surface tension of the composition containing the components except for the solvent (component (d)) is more preferably 7 mN/m or more and 50 mN/m or less at 23° C. and at 1 atm, and further preferably 10 mN/m or more and 40 mN/m or less. Note that when the surface tension is high, for example, 5 mN/m or more, the capillarity strongly acts, so filling (spreading and filling) is complete within a short time period when the nonvolatile composition (A′) and a mold are brought into contact with each other. Also, when the surface tension is 70 mN/m or less, a cured film obtained by curing the curable composition has surface smoothness.
The contact angle of the curable composition (A) of the present disclosure is preferably 0° or more and 900 or less with respect to the surface of a substrate. If the contact angle is larger than 90°, the droplets on the substrate do not come into contact with each other, and a continuous liquid film cannot be formed.
The contact angle of the nonvolatile composition (A′) of the present disclosure is preferably 0° or more and 90° or less with respect to both the surface of a substrate and the surface of a mold. If the contact angle is larger than 90°, the capillarity acts in a negative direction (a direction in which the contact interface between the mold and the curable composition is shrunk) inside a pattern of the mold or in a gap between the substrate and the mold, and the nonvolatile composition (A′) may not be filled in the mold. When the contact angle is small, the capillarity strongly acts, and the filling speed increases.
The curable composition (A) of the present disclosure preferably contains impurities as little as possible. Note that impurities mean components other than the components (a), (b), (c), and (d) described above. Therefore, the curable composition (A) of the present disclosure is favorably a composition obtained through a refining step. A refining step like this is preferably filtration using a filter.
As this filtration using a filter, it is favorable to mix the components (a), (b), and (c) described above, and filtrate the mixture by using, for example, a filter having a pore diameter of 0.001 μm or more and 5.0 μm or less. When performing filtration using a filter, is it further favorable to perform the filtration in multiple stages, or to repetitively perform the filtration a plurality of times (cycle filtration). It is also possible to re-filtrate a liquid once filtrated through a filter, or perform filtration by using filters having different pore diameters. Examples of the filter for use in filtration are filters made of, for example, a polyethylene resin, a polypropylene resin, a fluorine resin, and a nylon resin, but the filter is not particularly limited. Impurities such as particles mixed in the curable composition can be removed through the refining step as described above. Consequently, it is possible to prevent impurities mixed in the curable composition from causing pattern defects by forming unexpected unevenness on a cured film obtained after the curable composition is cured.
Note that when using the curable composition of the present disclosure in order to fabricate a semiconductor integrated circuit, it is favorable to avoid mixing of impurities (metal impurities) containing metal atoms in the curable composition as much as possible so as not to obstruct the operation of a product. The concentration of the metal impurities contained in the curable composition is preferably 10 ppm or less, and more preferably 100 ppb or less.
If a glass transition temperature (Tg) is much higher than the temperature at the time of mold release, the cured product at the time of mold release exhibits a firm glass state, that is, a high mechanical strength, and therefore, pattern collapse or breakage due to impact of mold release hardly occurs. Hence, when executing the mold release step at room temperature, the glass transition temperature of the cured product (cured film) of the nonvolatile composition (A′) is preferably 70° C. or more, more preferably 100° C. or more, and particularly preferably 150° C. or more.
As a method of measuring the glass transition temperature of the cured product (photocured product), a method of performing measurement using differential scanning calorimetry (DSC) or a dynamic viscoelasticity measuring apparatus can be applied. For example, glass transition temperature measurement can be done using DSC as follows.
An example of a major apparatus is STA-6000 (manufactured by Perkin Eimer). On the other hand, when measuring the glass transition temperature using a dynamic viscoelasticity measuring apparatus, a temperature at which the loss sine (tan δ) of the cured product is maximum is defined as the glass transition temperature. An example of a major apparatus for measuring dynamic viscoelasticity is MCR301 (manufactured by Anton Paar).
In this specification, a member on which droplets of the curable composition (A) are discretely dropped is explained as a substrate.
This substrate is a substrate to be processed, and a silicon wafer is normally used. The substrate can have a layer to be processed on the surface. On the substrate, another layer can also be formed below the layer to be processed. When a quartz substrate is used as the substrate, a replica (replica mold) of a mold for imprinting can be manufactured. However, the substrate is not limited to a silicon wafer or a quartz substrate. The substrate can freely be selected from those known as semiconductor device substrates such as aluminum, a titanium-tungsten alloy, an aluminum-silicon alloy, an aluminum-copper-silicon alloy, silicon oxide, and silicon nitride. Note that the surface of the substrate or the layer to be processed is preferably treated by a surface treatment such as a silane coupling treatment, a silazane treatment, or deposition of an organic thin film, thereby improving the adhesion to the curable composition (A). As a practical example of the organic thin film to be deposited as the surface treatment, an adhesive layer described in Japanese Patent Laid-Open No. 2009-503139 can be used.
The pattern forming method of the present disclosure will be explained with reference to
An example in which the film forming method of the present disclosure is applied to the pattern forming method will be explained below. The pattern forming method includes, for example, a forming step, an arranging step, a waiting step, a contact step, a curing step, and a mold release step (separation step). The forming step is a step of forming an underlayer. The arranging step is a step of discretely arranging droplets of the curable composition (A) on the underlayer. The waiting step is a step of waiting until the droplets of the curable composition (A) bond to each other and the solvent (d) volatilizes. The contact step is a step of bringing the curable composition (A) and a mold in contact with each other. The curing step is a step of curing the curable composition (A). The mold release step is a step of releasing the mold from the cured film of the curable composition (A). The arranging step is performed after the forming step, the waiting step is performed after the arranging step, the contact step is performed after the waiting step, the curing step is performed after the contact step, and the mold release step is performed after the curing step.
In the arranging step, as schematically shown in
An inkjet method is particularly favorable as the arranging method of arranging the droplets 102 of the curable composition (A) on the substrate. It is favorable to arrange the droplets 102 of the curable composition (A) densely on that region of the substrate 101, which faces a region in which recesses forming the pattern of a mold 106 densely exist, and sparsely on that region of the substrate 101, which faces a region in which recesses forming the pattern of the mold 106 sparsely exist. Consequently, a film (residual film) 109 (to be described later) of the curable composition (A) formed on the substrate 101 is controlled to have a uniform thickness regardless of the sparsity and density of the pattern of the mold 106.
An index called an average liquid film thickness is defined in order to prescribe the volume of the nonvolatile composition (A′) to be arranged. The average liquid film thickness is a value obtained by dividing the volume of the nonvolatile composition (A′) to be arranged in the arranging step by the area of a film formation region of the mold. The volume of the nonvolatile composition (A′) is the sum total of the volumes of the individual droplets of the curable composition (A) after the solvent (d) volatilized. According to this definition, the average liquid film thickness can be prescribed regardless of the state of unevenness even when the substrate surface is uneven. Here, the average liquid film thickness may be understood as a value obtained by dividing the volume of the nonvolatile composition (A′) remaining after the waiting step to be described later by the area of the film formation region of the mold, and is preferably 5 nm or more and 170 nm or less.
In the present disclosure, the waiting step is provided after the arranging step and before the contact step, in which processing waits until bonding of the plurality of droplets on the substrate progresses, and volatilization of the solvent contained in the liquid film progresses. Here, a value obtained by dividing the total volume of the droplets of the curable composition (A) dropped in one-time pattern formation by the total area of regions (pattern formation regions) in which patterns are formed in one-time pattern formation is defined as an average initial liquid film thickness. In the waiting step, as schematically shown in
A flow behavior during the waiting step of the droplets of the curable composition (A) arranged on the substrate will be explained with reference to
In addition, as schematically shown in
In the waiting step, it is possible to perform a baking step of heating the substrate 101 and the curable composition (A), or ventilate the atmospheric gas around the substrate 101, for the purpose of accelerating the volatilization of the solvent (d). Heating is performed at, for example, 30° C. or more and 200° C. or less, preferably 80° C. or more and 150° C. or less, and particularly preferably 90° C. or more and 110° C. or less. The heating time can be 10 sec or more and 600 sec or less. The baking step can be performed by using a known heater such as a hotplate or an oven.
The waiting time of the waiting step is, for example, 0.1 to 600 sec, and can preferably be 10 to 300 sec. If the waiting step is shorter than 0.1 sec, the bonding of the droplets of the curable composition (A) becomes insufficient, so no practically continuous liquid film is formed. If the waiting step exceeds 600 sec, the productivity decreases. To suppress the decrease in productivity, therefore, it is also possible to sequentially move substrates completely processed in the arranging step to the waiting step, perform the waiting step in parallel to a plurality of substrates, and sequentially move the substrates completely processed in the waiting step to the contact step. Note that in the related art, a few thousands of seconds to a few tens of thousands of seconds are theoretically required before a practically continuous liquid film is formed. In practice, however, no continuous liquid film can be formed because the spread of the droplets of the curable composition stagnates due to the influence of volatilization.
When the solvent (d) volatilizes in the waiting step, the practically continuous liquid film 104 of the nonvolatile composition (A′) containing the components (a), (b), and (c) remains. The average liquid film thickness of the practically continuous liquid film 104 from which the solvent (d) volatilized (was removed) becomes smaller than the liquid film 103 by the volatilized amount of the solvent (d). A state in which the entire pattern formation region of the substrate 101 is covered with the practically continuous liquid film 104 of the curable composition (A) from which the solvent (d) was removed is maintained in the entire region.
In the contact step, as schematically shown in
The contact step can be performed under any condition such as a normal air atmosphere, a reduced-pressure atmosphere, or an inert-gas atmosphere, and is preferably performed under a reduced-pressure atmosphere or an inert-gas atmosphere because it is possible to prevent oxygen or water from affecting the curing reaction. Practical examples of an inert gas used when performing the contact step under an inert-gas atmosphere are nitrogen, carbon dioxide, helium, argon, various freon gases, and gas mixtures thereof. A gas containing 10% or more of carbon dioxide or helium in a molar ratio is preferable, and a gas containing 10% or more of carbon dioxide in a molar ratio is particularly preferable. Since the helium gas readily diffuses to the mold, the substrate, the curable composition, and the like, the atmospheric gas confined in the pattern of the mold quickly disappears. Since carbon dioxide readily dissolves to the curable composition or the underlayer on the substrate, the atmospheric gas confined in the pattern of the mold quickly disappears. The solubility coefficient of carbon dioxide to the curable composition is preferably 0.5 kg/m3·atm or more and 10 kg/m3·atm or less. Details are disclosed in Japanese Patent Laid-Open No. 2022-99271. When performing the contact step under the atmosphere of a specific gas, including the normal air atmosphere, the pressure is preferably 0.0001 atm or more and 10 atm or less.
In the present disclosure, the curable composition (A) forms the practically continuous liquid film 104 of the nonvolatile composition (A′) from which the solvent (d) is removed in the waiting step, so the volume of a gas involved between the mold 106 and the substrate 101 becomes small. Accordingly, spreading of the nonvolatile composition (A′) in the contact step is rapidly completed.
When spreading and filling of the nonvolatile composition (A′) are quickly completed in the contact step, it is possible to shorten the time (the time required for the contact step) for maintaining the state in which the mold 106 is in contact with the nonvolatile composition (A′). Since shortening the time required for the contact step leads to shortening the time required for pattern formation (film formation), the productivity improves. The contact step is preferably 0.1 sec or more and 3 sec or less, and particularly preferably 0.1 sec or more and 1 sec or less. If the contact step is shorter than 0.1 sec, spreading and filling become insufficient, so many defects called incomplete filling defects tend to occur.
Let μ [mPa·s] be the viscosity of the nonvolatile composition (A′). Let h [m] be the average liquid film thickness when the droplets of the nonvolatile composition (A′) bond to each other to form the practically continuous liquid film 104. At this time, in this embodiment, h is calculated such that the viscosity μ [mPa·s] and the average liquid film thickness h [m] formed by the nonvolatile composition satisfy Expressions 1 and 2 below.
Let v [m/sec] be the edge filling speed that is the speed of the nonvolatile composition (A′) spreading to the entire region of the gap between the substrate 101 and the mold 106, and t [sec] be the extrusion grace time that is the time until extrusion occurs. At this time, if the viscosity μ [mPa·s] and the average liquid film thickness h [m] satisfy Expressions 1 and 2 above, v is 20 [μm/sec] or more, and t is 0.5 [sec] or more.
In the present disclosure, in the contact step, the time (the time required for the contact step) for maintaining the state in which the mold 106 is in contact with the nonvolatile composition (A′) can be shortened. Since shortening the time required for the contact step leads to shortening the time required for pattern formation (film formation), the productivity (throughput) is improved. The contact step is preferably 0.1 sec or more and 3 sec or less, and particularly preferably 0.1 sec or more and 1 sec or less. If the contact step is shorter than 0.1 sec, edge filling is insufficient, resulting in many defects called incomplete filling defects.
As described above, a phenomenon called extrusion may occur in the contact step. This is a phenomenon that the nonvolatile composition (A′) protrudes from the contact surface of the mold 106 and adheres to (crawls up) the side wall (side surface) of the mold in the contact step. The concept of extrusion will be described with reference to
Hence, when the nonvolatile composition (A′) of the present disclosure is used, it is possible to execute imprint processing at high productivity (throughput) and suppress defects on the substrate caused by extrusion.
When the curing step includes a photoirradiation step, a mold made of a light-transmitting material is used as the mold 106 by taking this into consideration. Favorable practical examples of the type of the material forming the mold 106 are glass, quartz, PMMA, a photo-transparent resin such as a polycarbonate resin, a transparent metal deposition film, a soft film such as polydimethylsiloxane, a photo-cured film, and a metal film. When using the photo-transparent resin as the material forming the mold 106, a resin that does not dissolve in components contained in a curable composition is selected. Quartz is suitable as the material forming the mold 106 because the thermal expansion coefficient is small and pattern distortion is small.
A pattern formed on the surface of the mold 106 has a height of, for example, 4 nm or more and 200 nm or less. As the pattern height of the mold 106 decreases, it becomes possible to decrease the force of releasing the mold 106 from the cured film of the curable composition, that is, the mold release force in the mold release step, and this makes it possible to decrease the number of mold release defects remaining in the mold 106 because the pattern of the curable composition is torn off. Also, in some cases, the pattern of the curable composition elastically deforms due to the impact when the mold is released, and adjacent pattern elements come in contact with each other and adhere to each other or break each other. Note that to avoid these inconveniences, it is advantageous to make the height of pattern elements be about twice or less the width of the pattern elements (make the aspect ratio be 2 or less). On the other hand, if the height of pattern elements is too small, the processing accuracy of the substrate 101 decreases.
A surface treatment can also be performed on the mold 106 before performing the contact step, in order to improve the detachability of the mold 106 with respect to the curable composition (A). An example of this surface treatment is to form a mold release agent layer by coating the surface of the mold 106 with a mold release agent. Examples of the mold release agent to be applied on the surface of the mold 106 are a silicon-based mold release agent, a fluorine-based mold release agent, a hydrocarbon-based mold release agent, a polyethylene-based mold release agent, a polypropylene-based mold release agent, a paraffine-based mold release agent, a montane-based mold release agent, and a carnauba-based mold release agent. It is also possible to suitably use a commercially available coating-type mold release agent such as Optool® DSX manufactured by Daikin. Note that it is possible to use one type of a mold release agent alone, or use two or more types of mold release agents together. Of the mold release agents described above, fluorine-based and hydrocarbon-based mold release agents are particularly favorable.
In the contact step, the pressure to be applied to the curable composition (A) when bringing the mold 106 into contact with the nonvolatile composition (A′) is not particularly limited, and can be, for example, 0 MPa or more and 100 MPa or less. When bringing the mold 106 into contact with the nonvolatile composition (A′), the pressure to be applied to the curable composition (A) is preferably 0 MPa or more and 50 MPa or less. The pressure to be applied to the curable composition (A) is more preferably 0 MPa or more and 30 MPa or less, and further preferably 0 MPa or more and 20 MPa or less.
The contact step can be performed in any of a normal air atmosphere, a reduced-pressure atmosphere, and an inert-gas atmosphere. However, the reduced-pressure atmosphere or the inert-gas atmosphere is favorable because it is possible to prevent the influence of oxygen or water on the curing reaction. Practical examples of an inert gas to be used when performing the contact step in the inert-gas atmosphere are nitrogen, carbon dioxide, helium, argon, various freon gases, and gas mixtures thereof. A gas containing 10% or more of carbon dioxide or helium in a molar ratio is preferable, and a gas containing 10% or more of carbon dioxide in a molar ratio is particularly preferable. Since the helium gas readily diffuses to the mold, the substrate, the curable composition, and the like, the atmospheric gas confined in the mold pattern quickly disappears. Since carbon dioxide readily dissolves to the curable composition or the underlayer on the substrate, the atmospheric gas confined in the mold pattern quickly disappears (see Japanese Patent Laid-Open No. 2022-99271). When performing the contact step in a specific gas atmosphere including a normal air atmosphere, a favorable pressure is 0.0001 atm or more and 10 atm or less.
In the curing step, as schematically shown in
The irradiation light 107 is selected in accordance with the sensitivity wavelength of the nonvolatile composition (A′). More specifically, the irradiation light 107 is properly selected from ultraviolet light, X-ray, and an electron beam each having a wavelength of 150 nm or more and 400 nm or less. Note that the irradiation light 107 is particularly preferably ultraviolet light. This is so because many compounds commercially available as curing assistants have sensitivity to ultraviolet light. Examples of a light source that emits ultraviolet light are a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a low-pressure mercury lamp, a Deep-UV lamp, a carbon arc lamp, a chemical lamp, a metal halide lamp, a xenon lamp, a KrF excimer laser, an ArF excimer laser, and an F2 laser. Note that the ultrahigh-pressure mercury lamp is particularly favorable as the light source for emitting ultraviolet light. It is possible to use one light source or a plurality of light sources. Light can be emitted to the entire region of the curable composition (A) filled in the fine pattern of the mold, or to only a partial region thereof (by limiting the region). It is also possible to intermittently emit light to the entire region of the substrate a plurality of times, or to continuously emit light to the entire region of the substrate. Furthermore, a first region of the substrate can be irradiated with light in a first irradiation process, and a second region different from the first region of the substrate can be irradiated with light in a second irradiation process.
In the mold release step, as schematically shown in
A method of releasing the mold 106 from the cured film 108 having the pattern can be any method provided that the method does not physically break a part of the cured film 108 having the pattern during the release, and various conditions and the like are not particularly limited. For example, it is possible to fix the substrate 101 and move the mold 106 away from the substrate 101. It is also possible to fix the mold 106 and move the substrate 101 away from the mold 106. Furthermore, the mold 106 can be released from the cured film 108 having the pattern by moving both the mold 106 and the substrate 101 in exactly opposite directions.
A series of steps (a fabrication process) having the above-described steps from the arranging step to the mold release step in this order make it possible to obtain a cured film having a desired uneven pattern shape (a pattern shape conforming to the uneven shape of the mold 106) in a desired position.
In the pattern forming method of the present disclosure, a repetition unit (shot) from the arranging step to the mold release step can repetitively be performed a plurality of times on the same substrate, so the cured film 108 having a plurality of desired patterns in desired positions of the substrate can be obtained.
An example in which the film forming method of the present disclosure is applied to a planarization film forming method will be explained below. The planarization film forming method includes, for example, an arranging step, a waiting step, a contact step, a curing step, and a mold release step. The arranging step is a step of arranging droplets of the curable composition (A) on a substrate. The waiting step is a step of waiting until the droplets of the curable composition (A) bond to each other and the solvent (d) volatilizes. The contact step is a step of bringing the nonvolatile composition (A′) and a mold into contact with each other. The curing step is a step of curing the nonvolatile composition (A′). The mold release step is a step of releasing the mold from the cured film of the nonvolatile composition (A′). In the planarization film forming method, a substrate having unevenness having a difference in height of about 10 to 1,000 nm is used as the substrate, a mold having a flat surface is used as the mold, and a cured film having a surface conforming to the flat surface of the mold is formed through the contact step, the curing step, and the mold release step. The flat surface indicates a flat (patternless) surface without a pattern to be formed on the substrate or a flat surface equal to or larger than the pattern formation region of the substrate. In the arranging step, the droplets of the curable composition (A) are densely arranged in recesses of the substrate, and sparsely arranged on projections of the substrate. The waiting step is performed after the arranging step, the contact step is performed after the waiting step, the curing step is performed after the contact step, and the mold release step is performed after the curing step.
An article manufacturing method can include a forming step of forming a film of a curable composition on a substrate using the above-described film forming method, a processing step of processing the substrate on which the film of the curable composition is formed in the forming step, and a manufacturing step of manufacturing an article from the substrate processed in the processing step. The film forming method is a pattern forming method or a planarization film forming method, as described above.
The cured film 108 having a pattern formed by the pattern forming method of the present disclosure can directly be used as at least a partial constituent member of various kinds of articles. Also, the cured film 108 having a pattern formed by the pattern forming method of the present disclosure can temporarily be used as a mask for etching or ion implantation with respect to the substrate 101 (a layer to be processed when the substrate 101 has the layer to be processed). This mask is removed after etching or ion implantation is performed in a processing step of the substrate 101. Consequently, various kinds of articles can be manufactured.
When removing a cured product in recesses of a pattern of the cured product by etching, a practical method is not particularly limited, and a conventionally known method such as dry etching can be used. A conventionally known dry etching apparatus can be used in this dry etching. A source gas for dry etching is appropriately selected in accordance with an element composition of the cured product to be etched. More specifically, it is possible to use halogen gases such as CF4, C2F6, C3F8, CCl2F2, CCl4, CBrF3, BC13, PCl3, SF6, and Cl2 as the source gas. As the source gas, it is also possible to use gases containing oxygen atoms such as O2, CO, and CO2, inert gases such as He, N2, and Ar, and gases such as H2 and NH3 as the source gas. Note that these gases can also be mixed and used as the source gas. In this case, the photo-cured film is required to have a high dry etching resistance in order to process the base substrate with high yield.
An article is, for example, an electric circuit element, an optical element, MEMS, a recording element, a sensor, or a mold. Examples of the electric circuit element are volatile or nonvolatile semiconductor memories such as a DRAM, an SRAM, a flash memory, and an MRAM, and semiconductor elements such as an LSI, a CCD, an image sensor, and an FPGA. Examples of the optical element are a micro lens, a light guide body, a waveguide, an antireflection film, a diffraction grating, a polarizer, a color filter, a light-emitting element, a display, and a solar battery. Examples of the MEMS are a DMD, a microchannel, and an electromechanical transducer. Examples of the recording element are optical disks such as a CD and a DVD, a magnetic disk, a magneto-optical disk, and a magnetic head. Examples of the sensor are a magnetic sensor, a photosensor, and a gyro sensor. An example of the mold is a mold for imprinting.
In addition, a well-known photolithography step such as an imprint lithography technique or an extreme ultraviolet exposure technique (EUV) can be performed on the planarization film formed by the planarization film forming method of the present disclosure. It is also possible to stack a spin-on-glass (SOG) film and/or a silicon oxide layer, and perform a photolithography step by applying a curable composition on that. Consequently, a device such as a semiconductor device can be fabricated. It is further possible to form an apparatus including the device, for example, an electronic apparatus such as a display, a camera, or a medical apparatus. Examples of the device are an LSI, a system LSI, a DRAM, an SDRAM, an RDRAM, a D-RDRAM, and a NAND flash memory.
To supplement the above-described embodiment, more detailed examples will be described.
In this example, using the viscosity μ [mPa·s] of the nonvolatile composition and the average liquid film thickness h [m], the edge filling speed v and the extrusion grace time t are represented by Equations E1 and E2 below. Also, it is indicated, using numerical calculation, that to satisfy conditions that v is 20 [μm/sec] or more, and t is 0.5 [sec] or more, Expressions 1 and 2 described above are preferably satisfied.
In this example, assuming the contact step, the edge filling speed and the extrusion grace time were obtained by solving simultaneously set Navier-Stokes equations approximated to a thin film sandwiched between wall surfaces and an equation of elastic deformation of a mold.
The mold 106 was a linear elastic body, the Young's modulus was 72 GPa, and the Poisson's ratio was 0.17. The surface tension coefficient of the liquid film was 30 mN/m. The initial conditions of the average liquid film thickness were uniform, and the distance between the initial position 110 of the end portion of the liquid film 102 and the end portion 109 of the pattern formation region was 100 μm. In a region in the negative direction of the x-axis from the initial position 110 of the end portion of the liquid film 102, the gap between the mold 106 and the substrate 101 was filled with the liquid film 102, and no gap existed between the liquid film 102 and the mold 106. Also, at the initial position 110 of the end portion of the liquid film 102, the liquid film 102 was in contact with the mold 106 and the substrate 101 at a contact angle of 0°. The liquid film 102 started from a stationary state. The numerical calculation method shown in this example is merely an example, and another calculation method can also be used.
As described above, the edge filling speed is expressed by Equation E1 including μ and h as variables, and the extrusion grace time is expressed by Equation E2 including μ and h as variables. It is therefore found that to satisfy conditions that the edge filling speed is 20 μm/sec or more and the extrusion grace time is 0.5 sec or more, it is preferable to satisfy inequalities represented by Expressions 1 and 2.
Table 2 shows the measurement result of the viscosity of the curable composition (A). The measurement was done in the following way. First, in accordance with abbreviations shown in Table 1, the components (a), (b), (c), and (d) were mixed such that a total ratio of 100 wt % was obtained, thereby obtaining the curable composition (A). Next, the viscosities of the curable composition (A) and a nonvolatile component (A′) mixed without using the component (d) at 23° C. were measured. After that, Tg of the curable composition after removal of the component (d) was measured by the above-described method. Note that as for the component (d) in Table 2, PGMEA is short for propylene glycol monomethyl ether, and Gly is short for glycerin.
To evaluate the edge filling speed, a commercially available industrial material printer DMP-2850 (manufactured by Fuji Film) was used. Under conditions that the liquid film after volatilization of the solvent (d) obtained thicknesses of 40 nm, 80 nm, and 120 nm, each of curable compositions (A) of Examples 2 to 6 and Comparative Examples 1 to 3 was discretely dropped (arranged) on a silicon substrate, and the waiting step and the contact step were executed. All the arranging step, the waiting step, and the contact step were executed under a carbon dioxide atmosphere, and a blank mold made of quartz was used in the contact step. Here, let D be the distance between the position of the end portion of the pattern formation region of the substrate and the initial position of the end portion of the liquid film of the curable composition (A) on the substrate immediately before the contact step, and T be the time needed until the nonvolatile component (A′) is filled up to the end portion of the pattern formation region of the substrate in the contact step. At this time, the edge filling speed is defined as D/T. The thus defined edge filling speed was evaluated based on the following determination criteria.
To evaluate the extrusion grace time, a commercially available industrial material printer DMP-2850 (manufactured by Fuji Film) was used. Under conditions that the liquid film after volatilization of the solvent (d) obtained thicknesses of 40 nm, 80 nm, and 120 nm, each of curable compositions (A) of Examples 2 to 6 and Comparative Examples 1 to 3 was discretely dropped (arranged) on a silicon substrate, and the waiting step and the contact step were executed. All the arranging step, the waiting step, and the contact step were executed under a carbon dioxide atmosphere, and a blank mold made of quartz was used in the contact step.
In the contact step, if the nonvolatile component (A′) and the mold are further kept in contact with each other immediately after the nonvolatile component (A′) is filled up to the end portion of the pattern formation region of the substrate, the nonvolatile component (A′) extrudes from the end portion of the mold and crawls up the side wall of the mold. The height of the component crawling up the side wall of the mold is measured as the extrusion height. Time until the extrusion height reaches 50 nm was measured, and evaluated based on the following determination criteria.
Table 3 shows the evaluation results of the edge filling speed and the extrusion grace time.
Consider that the following conditions are satisfied.
It is found that to satisfy the above-described conditions, the viscosity of the nonvolatile component (A′) is preferably 20 mPa·s or more and 60 mPa·s or less, as suggested by Expressions 1 and 2 described above.
Also, consider that the following conditions are satisfied.
It is found that to satisfy the above-described conditions, the viscosity of the nonvolatile component (A′) is preferably 20 mPa·s or more and 100 mPa·s or less.
Also, consider that the following conditions are satisfied.
It is found that to satisfy the above-described conditions, the viscosity of the nonvolatile component (A′) except for the solvent is preferably 60 mPa·s or more and 135 mPa·s or less.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2024-000803, filed Jan. 5, 2024, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2024-000803 | Jan 2024 | JP | national |
