Resist underlayer film-forming composition and method for manufacturing semiconductor substrate

Abstract

Provided are: a resist underlayer film-forming composition from which it is possible to form a film having excellent embedding properties and bending resistance; and a method for manufacturing a semiconductor substrate. This resist underlayer film-forming composition comprises a sulfur-containing compound and a solvent. The sulfur-containing compound is represented by formula (1). (In formula (1), each Ar represents a substituted or unsubstituted aromatic ring having 3-20 carbon atoms. Each X represents a sulfur atom, -S(=O)-, or -S(=O)2-. n represents an integer of 4-8. The plurality of Ar's are identical or different from each other and the plurality of X's are identical or different from each other.)

Description

Composition for forming a resist underlayer film and method for manufacturing a semiconductor substrate

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

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

[0003] Various studies have been conducted on materials used in such resist underlayer formation compositions (International Publication No. 2011 / 108365).

[0004] International Publication No. 2011 / 108365

[0005] Recently, substrates with patterns such as trenches and holes have been increasingly used, and the resist underlayer film formation composition is required to have sufficient embedding properties to be embedded in the substrate pattern. Furthermore, regardless of whether or not there is a pattern, the resist underlayer film is required to have bending resistance.

[0006] The present invention has been made based on the circumstances described above, and its purpose is to provide a resist underlayer film formation composition capable of forming a film with excellent embedding properties and bending resistance, and a method for manufacturing a semiconductor substrate.

[0007] In one embodiment, the present invention relates to a composition for forming a resist underlayer film, which contains a sulfur-containing compound (hereinafter also referred to as "[A] compound") and a solvent (hereinafter also referred to as "[B] solvent), wherein the sulfur-containing compound is a compound represented by the following formula (1). (In formula (1), Ar is a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. X is a sulfur atom, -S(=O)- or -S(=O) ２- n is an integer between 4 and 8. Multiple Ars and X are either identical or different from one another.

[0008] The resist underlayer film formation composition in question can form a resist underlayer film with excellent embedding properties and bending resistance. Although the reason for this is not entirely clear, it is presumed to be as follows: Compound [A] has a calixarene-like structure and exhibits excellent fluidity due to its oligomeric form. Furthermore, the introduction of a sulfur atom (sulfide bond (thioether bond)) or a sulfur atom-containing linking group (sulfinyl group or sulfonyl group) into compound [A] increases the electron density in compound [A], resulting in a higher modulus of elasticity of the resist underlayer film. It is presumed that these combined effects enable the formation of a resist underlayer film with excellent embedding properties and bending resistance.

[0009] In other embodiments, the present invention relates to a method for manufacturing a semiconductor substrate, comprising the steps of: coating a resist underlayer film forming composition directly or indirectly onto a substrate; directly or indirectly forming a resist pattern on the resist underlayer film formed by the coating step; and etching using the resist pattern as a mask, wherein the resist underlayer film forming composition contains a sulfur-containing compound and a solvent, and the sulfur-containing compound is a compound represented by the following formula (1). (In formula (1), Ar is a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. X is a sulfur atom, -S(=O)- or -S(=O) ２ - n is an integer between 4 and 8. Multiple Ars and X are either identical or different from one another.

[0010] According to the semiconductor substrate manufacturing method, by using a predetermined resist underlayer film forming composition in the coating step, a resist underlayer film with excellent embedding properties and bending resistance can be formed due to the fluidity of the [A] compound and the high modulus of elasticity after curing, thereby enabling the manufacture of a semiconductor substrate with a good pattern shape.

[0011] In this specification, "calixarene" refers to a cyclic oligomer in which aromatic rings or heteroaromatic rings to which hydroxy groups are bonded are cyclically bonded through hydrocarbon groups. "Fused ring" refers to a polycyclic structure formed by two adjacent rings sharing one side (two adjacent atoms). "Ring assembly" refers to a structure in which two rings are bonded by a single bond. "Organic group" refers to a group containing at least one carbon atom.

[0012] According to the composition for forming a resist underlayer film, a film excellent in embedding property and bending resistance can be formed. According to the method for manufacturing a semiconductor substrate, a resist underlayer film excellent in embedding property and bending resistance can be formed, so that a semiconductor substrate having a good pattern shape can be obtained. Therefore, these can be suitably used for manufacturing semiconductor devices and the like, which are expected to further miniaturize in the future.

[0013] It is a schematic plan view for explaining a method for evaluating bending resistance.

[0014] Hereinafter, the composition for forming a resist underlayer film and the method for manufacturing a semiconductor substrate according to each embodiment of the present invention will be described in detail. Combinations of preferred embodiments are also preferred.

[0015] 《Composition for Forming a Resist Underlayer Film》 The composition for forming a resist underlayer film contains [A] a compound and [B] a solvent. The composition for forming a resist underlayer film may contain optional components as long as the effects of the present invention are not impaired.

[0016] Hereinafter, each component contained in the composition for forming a resist underlayer film will be described.

[0017] <[A] Compound> The [A] compound is a compound represented by the following formula (1). The composition for forming a resist underlayer film may contain one or more [A] compounds. (In formula (1), Ar is a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. X is a sulfur atom, —S(═O)— or —S(═O) ２ —. n is an integer of 4 to 8. A plurality of Ar and X are the same as or different from each other, respectively.).

[0018] Examples of aromatic rings having 3 to 20 carbon atoms in Ar include aromatic hydrocarbon rings having 6 to 20 carbon atoms such as benzene rings, naphthalene rings, anthracene rings, phenalene rings, phenanthrene rings, pyrene rings, fluorene rings, perylene rings, and biphenyl rings; aromatic heterocyclic rings having 3 to 20 carbon atoms such as triazole rings, imidazole rings, furan rings, pyrrole rings, thiophene rings, phosphole rings, pyrazole rings, oxazole rings, isoxazole rings, thiazole rings, pyridine rings, pyrazine rings, pyrimidine rings, pyridazine rings, and triazine rings; or combinations thereof. These combinations of rings may be fused rings, ring aggregates, or spirostructures. Benzene rings are preferred among the aromatic rings.

[0019] In Ar, the aromatic ring preferably has at least one monovalent group as a substituent, selected from the group consisting of a hydroxyl group, a sulfanyl group, a nitro group, and a monovalent organic group having 1 to 20 carbon atoms.

[0020] Examples of monovalent organic groups having 1 to 20 carbon atoms in Ar include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups having a divalent heteroatom-containing linking group between the carbon atoms of the hydrocarbon group or at the terminal end of the hydrocarbon group (hereinafter also referred to as "group (x)"), groups in which some or all of the hydrogen atoms of the hydrocarbon group or group (x) are replaced with monovalent heteroatom-containing substituents, or groups that combine these. Furthermore, the monovalent organic groups having 1 to 20 carbon atoms also include cyano groups, carboxyl groups, and formyl groups.

[0021] Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or groups combining these.

[0022] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, and t-butyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0023] Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include cycloalkyl groups such as cyclopentyl and cyclohexyl groups; cycloalkenyl groups such as cyclopropenyl, cyclopentenyl, and cyclohexenyl groups; bridged ring saturated hydrocarbon groups such as norbornyl, adamantyl, and tricyclodecyl groups; and bridged ring unsaturated hydrocarbon groups such as norbornyl and tricyclodecenyl groups.

[0024] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, anthracenyl, pyrenyl, and fluorenyl groups; and aralkyl groups such as benzyl and phenethyl groups.

[0025] Examples of heteroatoms that constitute a divalent heteroatom-containing linking group or a monovalent heteroatom-containing substituent include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

[0026] Examples of divalent heteroatom-containing linking groups include -CO-, -CS-, -NR'-, -O-, -S-, and -SO ２ - and combinations thereof are examples. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0027] Examples of monovalent heteroatom-containing substituents include hydroxyl groups, sulfanyl groups, cyano groups, nitro groups, amino groups, and halogen atoms.

[0028] n is preferably 4 or 6, and more preferably 4.

[0029] [A] The compound is preferably a compound represented by the following formula (1-1). (In formula (1-1), R １ and R ２ are each independently a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. X and n are as defined in the above formula (1).)

[0030] R １ and R ２ As the monovalent organic group having 1 to 20 carbon atoms represented by, the monovalent organic group having 1 to 20 carbon atoms shown in the substituents that the aromatic ring of Ar in the above formula (1) may have can be preferably employed.

[0031] R １ When is the above monovalent organic group, R １ is preferably a group containing a crosslinkable group in terms of the elastic modulus of the resist underlayer film. Examples of the group containing a crosslinkable group include a group containing a polymerizable carbon-carbon double bond, a group containing a polymerizable carbon-carbon triple bond, a group containing an epoxy group (such as an oxiranyl group, an oxetanyl group, etc.), an alkoxymethyl group, a group containing a formyl group, a group containing an acyl group, a dialkylaminomethyl group, a dimethylolaminomethyl group, etc. Among these, R １ is preferably a group containing a polymerizable carbon-carbon double bond, a group containing a polymerizable carbon-carbon triple bond, a group containing an epoxy group, an alkoxymethyl group, and more preferably a propargyl group, an allyl group, a vinylbenzyl group, an ethynylbenzyl group, a glycidyl group, a methoxymethyl group, an ethoxymethyl group, a (meth)acryloyl group.

[0032] R １ When is the above monovalent organic group, R １ may not contain a crosslinkable group. As R １ not containing a crosslinkable group, an alkyl group and an alkoxycarbonyl group are preferable, and a 2-ethylhexyl group and a t-butoxycarbonyl group are more preferable.

[0033] R ２ is preferably a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or a monovalent saturated chain hydrocarbon group having 1 to 10 carbon atoms, and even more preferably a hydrogen atom or a monovalent branched saturated hydrocarbon group having 1 to 5 carbon atoms.

[0034] [A] Specific examples of compounds include, but are not limited to, compounds represented by the following formula. In the following formula, R in -OR is the modifying group indicated as R on the right side of the corresponding structural formula. * represents the bond with O in -OR. The ratio in R indicates the relative abundance of each structure (on a molar basis, total 1).

[0035]

[0036]

[0037]

[0038] [A] The molecular weight of the compound is preferably 500 or more. [A] The lower limit of the molecular weight of the compound is more preferably 550, and even more preferably 600. [A] The upper limit of the molecular weight of the compound is preferably 2000, more preferably 1600, and even more preferably 1200. [A] The molecular weight of the compound is the weight-average molecular weight measured by gel permeation chromatography using monodisperse polystyrene as the standard.

[0039] The content of compound [A] in the components other than the solvent in the above resist underlayer film forming composition is preferably 1% by mass or more. The above content of compound [A] may be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 100% by mass.

[0040] <Method for Producing Compound [A]> Known methods can be suitably employed as the method for producing Compound [A]. Taking Compound [A] represented by formula (1-1) as a representative example, Compound [A] in which X in formula (1-1) is a sulfur atom can be produced by reacting substituted or unsubstituted phenol with elemental sulfur or sulfur halide. This reaction may be carried out in the presence of a base such as sodium hydroxide. Furthermore, in Compound [A] in which X in formula (1-1) is a sulfur atom, the sulfur atom can be oxidized with an oxidizing agent such as sodium perborate or hydrogen peroxide, thereby converting X in formula (1-1) to -S(=O)- or -S(=O) ２ - Compound [A] can be produced. Along with or instead of oxidation of the sulfur atom, known chemical modifications such as etherification and esterification of the hydroxyl group derived from phenol may be carried out. Other structures can also be produced by using other aromatic compounds having hydroxyl groups instead of the starting material phenol, or by carrying out appropriate chemical modifications. A commercially available product may be used as compound [A].

[0041] <[B] Solvent> The [B] solvent is not particularly limited as long as it can dissolve or disperse the [A] compound and any optional components contained therein as needed.

[0042] [B] Examples of solvents include hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, and nitrogen-containing solvents. [B] Solvents can be used individually or in combination of two or more.

[0043] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and cyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, and xylene.

[0044] Examples of ester solvents include carbonate solvents such as diethyl carbonate, acetic acid monoester solvents such as methyl acetate and ethyl acetate, lactone solvents such as γ-butyrolactone, polyhydric alcohol partial ether carboxylate solvents such as diethylene glycol acetate monomethyl ether and propylene glycol acetate monomethyl ether, and lactate ester solvents such as methyl lactate and ethyl lactate.

[0045] Examples of alcohol-based solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, and 1-butanol, and polyhydric alcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0046] Examples of ketone solvents include linear ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and cyclic ketone solvents such as cyclohexanone.

[0047] Examples of ether-based solvents include linear ether solvents such as n-butyl ether, cyclic ether solvents such as tetrahydrofuran and dioxane, polyhydric alcohol ether solvents such as ethylene glycol dimethyl ether, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether.

[0048] Examples of nitrogen-containing solvents include linear nitrogen-containing solvents such as N,N-dimethylacetamide and N,N-dimethylformamide, and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0049] [B] As the solvent, ester solvents or ketone solvents are preferred, polyhydric alcohol partial ether carboxylate solvents or cyclic ketone solvents are more preferred, and propylene glycol acetate monomethyl ether or cyclohexanone is even more preferred.

[0050] The lower limit of the content of solvent [B] in the resist underlayer film forming composition is preferably 50% by mass, more preferably 60% by mass, and still more preferably 70% by mass. The upper limit of the above content is preferably 99.9% by mass, more preferably 99% by mass, and still more preferably 98% by mass.

[0051] [Optional Components] The resist underlayer film forming composition may contain optional components as long as they do not impair the effects of the present invention. Examples of optional components include acid generators, base generators, crosslinking agents, surfactants, defoaming agents, etc. Specific examples of base generators include, for example, "U-CAT (registered trademark) SA1", "U-CAT (registered trademark) SA102", "U-CAT (registered trademark) SA102-50", "U-CAT (registered trademark) SA106", "U-CAT (registered trademark) SA112", "U-CAT (registered trademark) SA506", "U-CAT (registered trademark) SA603", "U-CAT (registered trademark) 1000", "U-CAT (registered trademark) 1102", "U-CAT (registered trademark) 2000", "U-CAT (registered trademark) 2024", "U-CAT (registered trademark) 2026", "U-CAT (registered trademark) 2030", "U-CAT (registered trademark) Examples include "Trademark 2110", "U-CAT (Registered Trademark) 2313", "U-CAT (Registered Trademark) 651M", "U-CAT (Registered Trademark) 660M", "U-CAT (Registered Trademark) 18X", "TMED", "U-CAT (Registered Trademark) 201G", "U-CAT (Registered Trademark) 202", "U-CAT (Registered Trademark) 420A", "U-CAT (Registered Trademark) 130", "U-CAT (Registered Trademark) 891", "POLYCAT (Registered Trademark) 8", "POLYCAT (Registered Trademark) 9", "POLYCAT (Registered Trademark) 12", and "POLYCAT (Registered Trademark) 41" (all are product names, manufactured by Sunapro Co., Ltd.). These compounds may be used individually or in combination of two or more. As defoaming agents, known defoaming agents can be used, including alcohol defoaming agents, phosphate ester defoaming agents, fatty acid ester defoaming agents, polyether defoaming agents, and silicone defoaming agents. Examples of fatty acid ester defoaming agents include methyl laurate, methyl palmitate, methyl stearate, propyl butyrate, butyl butyrate, ethyl isovalerate, and isobutyl propionate, with propyl butyrate and butyl butyrate being preferred. Ketone solvents such as 2-heptanone may also be used as defoaming agents. Optional components can be used individually or in combination of two or more. The content ratio of the optional components in the resist underlayer film forming composition can be appropriately determined depending on the type of optional component.

[0052] [Method for preparing the composition] The resist underlayer film forming composition can be prepared by mixing [A] compound, [B] solvent, and optionally any other components in a predetermined ratio, and preferably by filtering the resulting mixture through a membrane filter with a pore size of 0.5 μm or less.

[0053] 《Method for Manufacturing Semiconductor Substrates》 The method for manufacturing a semiconductor substrate comprises the steps of: coating a resist underlayer film formation composition directly or indirectly onto a substrate (hereinafter also referred to as the "coating step"), forming a resist pattern directly or indirectly onto the resist underlayer film formed by the coating step (hereinafter also referred to as the "resist pattern formation step"), and performing etching using the resist pattern as a mask (hereinafter also referred to as the "etching step").

[0054] The method for manufacturing the semiconductor substrate may further include, if necessary, a step of heating the resist underlayer film formed by the coating step before the resist pattern formation step (hereinafter also referred to as the "heating step").

[0055] The method for manufacturing the semiconductor substrate may further include, if necessary, a step of forming a silicon-containing film directly or indirectly on the resist underlayer film before forming the resist pattern (hereinafter also referred to as the "silicon-containing film formation step").

[0056] The following describes each step, including the heating step and the silicon-containing film formation step.

[0057] [Coating Process] In this process, the resist underlayer film formation composition is coated onto the substrate either directly or indirectly. In this process, the resist underlayer film formation composition described above is used.

[0058] The coating method for the resist underlayer film formation composition is not particularly limited and can be carried out by any suitable method, such as rotary coating, casting coating, or roll coating. A coating film is formed thereafter, and the resist underlayer film is formed by the volatilization of solvent [B].

[0059] Examples of substrates include metal or metalloid substrates such as silicon substrates, aluminum substrates, nickel substrates, chromium substrates, molybdenum substrates, tungsten substrates, copper substrates, tantalum substrates, and titanium substrates, with silicon substrates being preferred among these. The above substrates may also be substrates on which silicon nitride films, alumina films, silicon dioxide films, tantalum nitride films, titanium nitride films, etc., are formed.

[0060] The substrate may have patterns. The resist underlayer film forming composition has excellent embedding properties, so even if the substrate has patterns, it can form a good film while filling the gaps between patterns. Examples of the pattern shapes include trench patterns, line-and-space patterns, hole patterns, and pillar patterns. Examples of trench patterns and line-and-space patterns include patterns containing recesses with a width of 5 nm to 100 nm and patterns containing recesses with a depth of 5 nm to 500 nm. Examples of hole patterns include patterns containing holes with a diameter of 5 nm to 100 nm and patterns containing holes with a depth of 5 nm to 500 nm. Examples of pillar patterns include patterns containing pillars with a width of 5 nm to 100 nm and patterns containing pillars with a height of 5 nm to 500 nm.

[0061] Examples of indirectly coating a substrate with a resist underlayer film formation composition include coating a low-dielectric insulating film or an organic underlayer film formed on the substrate with the resist underlayer film formation composition.

[0062] [Heating Process] In this process, the coated film formed by the above coating process is heated. Heating the coated film promotes the formation of the resist underlayer film. More specifically, heating the coated film promotes the volatilization of solvent [B], etc.

[0063] The above-mentioned coating film may be heated in an atmospheric environment or in a nitrogen atmosphere. The lower limit of the heating temperature is preferably 200°C, more preferably 250°C, and even more preferably 300°C. The upper limit of the heating temperature is preferably 600°C, more preferably 500°C, and even more preferably 450°C. The lower limit of the heating time is preferably 15 seconds, more preferably 30 seconds. The upper limit of the heating time is preferably 1,200 seconds, and even more preferably 600 seconds.

[0064] Furthermore, the resist underlayer may be exposed after the above coating process. The resist underlayer may be exposed to plasma after the above coating process. Ion implantation may be performed on the resist underlayer after the above coating process. Exposure of the resist underlayer improves the etching resistance of the resist underlayer. Exposure of the resist underlayer improves the etching resistance of the resist underlayer. Ion implantation of the resist underlayer improves the etching resistance of the resist underlayer.

[0065] The radiation used for exposure of the resist underlayer film is appropriately selected from electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and gamma rays; and particle beams such as electron beams, molecular beams, and ion beams.

[0066] Methods for exposing the resist underlayer film to plasma include, for example, a direct method in which the substrate is placed in a gas atmosphere and plasma discharge is performed. The conditions for plasma exposure are typically a gas flow rate of 50 cc / min to 100 cc / min and a power supply of 100 W to 1,500 W.

[0067] The lower limit of the plasma exposure time is preferably 10 seconds, more preferably 30 seconds, and even more preferably 1 minute. The upper limit of the above time is preferably 10 minutes, more preferably 5 minutes, and even more preferably 2 minutes.

[0068] Plasma is, for example, H ２ Plasma is generated in an atmosphere of a mixed gas of gas and Ar gas. Also, H ２ In addition to gas and Ar gas, CF ４ Gas and CH ４ It is also possible to introduce carbon-containing gases such as gases.２ Instead of either or both of gas and Ar gas, CF ４ Gas, NF ３ Gas, CHF ３ Gas, CO ２ Gas, CH ２ F ２ Gas, CH ４ Gas and C ４ F ８ At least one of the gases may be introduced.

[0069] Ion implantation into the resist underlayer involves implanting dopants into the resist underlayer. Dopants can be selected from a group consisting of boron, carbon, nitrogen, phosphorus, arsenic, aluminum, and tungsten. The implantation energy used to apply voltage to the dopant ranges from approximately 0.5 keV to 60 keV, depending on the type of dopant used and the desired implantation depth.

[0070] The lower limit of the average thickness of the resist underlayer film formed is preferably 30 nm, more preferably 50 nm, and even more preferably 80 nm. The upper limit of the average thickness is preferably 3,000 nm, more preferably 1,500 nm, and even more preferably 400 nm. The method for measuring the average thickness is as described in the examples.

[0071] [Silicon-containing film formation process] In this process, a silicon-containing film is formed directly or indirectly on the resist underlayer film formed by the coating process or the heating process described above. An example of indirect formation of a silicon-containing film on the resist underlayer film is when a surface modification film of the resist underlayer film is formed on the resist underlayer film. The surface modification film of the resist underlayer film is, for example, a film whose contact angle with water is different from that of the resist underlayer film.

[0072] Silicon-containing films can be formed by coating with a silicon-containing film-forming composition, chemical vapor deposition (CVD), atomic layer deposition (ALD), etc. A method for forming a silicon-containing film by coating with a silicon-containing film-forming composition includes, for example, directly or indirectly coating the resist underlayer with the silicon-containing film-forming composition, and then curing the resulting coated film by exposure and / or heating. Commercially available silicon-containing film-forming compositions include, for example, "NFC SOG01," "NFC SOG04," and "NFC SOG080" (all manufactured by JSR Corporation). Silicon oxide films, silicon nitride films, silicon oxidnitride films, and amorphous silicon films can be formed by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0073] Examples of radiation used in the above exposure include electromagnetic waves such as visible light, ultraviolet rays, far ultraviolet rays, X-rays, and gamma rays, as well as particle beams such as electron beams, molecular beams, and ion beams.

[0074] The lower limit of the temperature when heating the coating film is preferably 90°C, more preferably 150°C, and even more preferably 180°C. The upper limit of the above temperature is preferably 550°C, more preferably 450°C, and even more preferably 350°C. The temperature may be gradually increased within the above temperature range.

[0075] The lower limit of the average thickness of the silicon-containing film is preferably 1 nm, more preferably 10 nm, and even more preferably 20 nm. The upper limit is preferably 20,000 nm, more preferably 1,000 nm, and even more preferably 100 nm. The average thickness of the silicon-containing film is the value measured using the spectroscopic ellipsometer, similar to the average thickness of the resist underlayer film.

[0076] [Resist Pattern Formation Process] In this process, a resist pattern is formed directly or indirectly on the resist underlayer film. Methods for performing this process include, for example, using a resist composition, using a nanoimprint method, or using a self-assembled composition. An example of indirectly forming a resist pattern on the resist underlayer film is forming a resist pattern on the silicon-containing film.

[0077] Examples of the above-mentioned resist compositions include positive or negative type chemically amplified resist compositions containing a radiation-sensitive acid generator, positive type resist compositions containing an alkali-soluble resin and a quinone diazide-based photosensitive agent, negative type resist compositions containing an alkali-soluble resin and a crosslinking agent, and metal-containing resist compositions containing metals such as tin, zirconium, and hafnium.

[0078] Examples of coating methods for the resist composition include rotary coating. The pre-baking temperature and time can be appropriately adjusted depending on the type of resist composition used.

[0079] Next, the resist film formed above is exposed by selective radiation irradiation. The radiation used for exposure can be appropriately selected depending on the type of radiation-sensitive acid generator used in the resist composition, and examples include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and gamma rays, as well as particle beams such as electron beams, molecular beams, and ion beams. Among these, far ultraviolet light is preferred, and KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F ２ Excimer laser light (wavelength 157 nm), Kr ２ Excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), or extreme ultraviolet light (wavelength 13.5 nm, etc., hereinafter also referred to as "EUV") is more preferred, and KrF excimer laser light, ArF excimer laser light, or EUV is even more preferred.

[0080] After the exposure described above, post-baking can be performed to improve resolution, pattern profile, developability, etc. The temperature and time of this post-baking can be appropriately determined depending on the type of resist composition used, etc.

[0081] Next, the exposed resist film is developed with a developer to form a resist pattern. This development may be alkaline development or organic solvent development. Examples of developers for alkaline development include basic aqueous solutions such as ammonia, triethanolamine, tetramethylammonium hydroxide (TMAH), and tetraethylammonium hydroxide. These basic aqueous solutions may also have appropriate amounts of water-soluble organic solvents such as methanol and ethanol, or surfactants added to them. For organic solvent development, examples of developers include the various organic solvents exemplified as solvent [B] in the resist underlayer film forming composition described above.

[0082] After development with the above-mentioned developer, the resist pattern is formed by washing and drying.

[0083] [Etching Process] In this process, etching is performed using the resist pattern described above as a mask. The etching may be performed once or multiple times, i.e., sequentially using the pattern obtained by etching as a mask. From the viewpoint of obtaining a pattern with a better shape, multiple etchings are preferred. When multiple etchings are performed, for example, the silicon-containing film, the resist underlayer film, and the substrate are etched sequentially. Examples of etching methods include dry etching and wet etching. From the viewpoint of obtaining a better shape for the substrate pattern, dry etching is preferred. For this dry etching, for example, a gas plasma such as oxygen plasma is used. By performing the above etching, a semiconductor substrate having a predetermined pattern is obtained.

[0084] Dry etching can be performed, for example, using a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the mask pattern, the elemental composition of the film to be etched, etc., for example, CHF ３ CF ４ , C ２ F ６ , C ３ F ８ SF ６ Fluorine-based gases such as Cl２ , BCl ３ Chlorine-based gases such as O ２ , O ３ , H ２ Oxygen-based gases such as O, H ２ CO, CO ２ ,CH ４ , C ２ H ２ , C ２ H ４ , C ２ H ６ , C ３ H ４ , C ３ H ６ , C ３ H ８ , HF, HI, HBr, HCl, NO, NH ３ , BCl ３ Reducing gases such as He, N ２ Examples include inert gases such as Ar. These gases can also be used in mixtures. When etching a substrate using the pattern of the resist underlayer as a mask, fluorine-based gases are usually used.

[0085] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0086] [Weight-average molecular weight (Mw)] The Mw of the polymer was measured by gel permeation chromatography (detector: differential refractometer) using monodisperse polystyrene as the standard, under analytical conditions of flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40°C, using GPC columns from Tosoh Corporation (two "G2000HXL" columns and one "G3000HXL" column).

[0087] [Average film thickness] The average film thickness was determined by measuring the film thickness at nine arbitrary points at 5 cm intervals, including the center of the resist underlayer film formed on a silicon wafer (substrate), using a spectroscopic ellipsometer (J.A. WOOLLAM's "M2000D"). The average of these film thicknesses was then calculated.

[0088] <Synthesis of Compound [A]> Compounds (A-1) to (A-5) and (b-1) to (b-7) listed below were used as raw materials for the synthesis of Compound [A].

[0089]

[0090]

[0091] Using the above raw materials, compounds (A-6) to (A-18) were synthesized as [A] compounds represented by the following formulas according to the procedure shown below. Compounds (A-1) to (A-5) were used as is. In the formulas below, R in -OR is the modifying group indicated as R on the right side of the corresponding structural formula. * indicates a bond with O in -OR. The ratio in R indicates the relative abundance of each structure (molar basis, total 1). In some cases, the right column of the formulas below also shows the overall structure in which the modifying group as R is directly bonded to the aromatic ring via -O-. The left and right columns represent the same structure.

[0092]

[0093]

[0094]

[0095]

[0096] [Example 1-1] (Synthesis of compound (A-6)) In a reaction vessel, under a nitrogen atmosphere, 20.0 g of compound (A-1), 36.1 g of cesium carbonate, and 140 g of N,N-dimethylformamide were added and heated to 40°C. Then, 13.2 g of compound (b-1), which had been pre-dissolved in 60 g of N,N-dimethylformamide, was slowly added dropwise, and the reaction was carried out at 90°C for 12 hours. After the reaction was complete, the reaction solution was transferred to a separatory funnel, and the organic phase was washed with 500 g of methyl isobutyl ketone and 500 g of 1% oxalic acid solution. After separating the aqueous phase, the obtained organic phase was washed several times with water. Then, it was concentrated in an evaporator, and the residue was added dropwise to 400 g of methanol / water = 7 / 3 (v / v) solution to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 200 g of methanol. Then, compound (A-6) was obtained by drying in a vacuum dryer at 60°C for 12 hours. The Mw of compound (A-6) was 873.

[0097] [Examples 1-2 to 1-6, 1-8 to 1-13] (Synthesis of compounds (A-7) to (A-11), (A-13) to (A-18)) Compounds (A-7) to (A-11) and (A-13) to (A-18) were obtained as products under the same reaction conditions as in Example 1-1, except that the starting compounds shown in Table 1 were used.

[0098] [Example 1-7] (Synthesis of Compound (A-12)) In a reaction vessel under a nitrogen atmosphere, 20.0 g of Compound (A-1), 3.39 g of N,N-dimethylaminopyridine, and 140 g of N,N-dimethylformamide were added. 24.2 g of Compound (b-7), which had been pre-dissolved in 60 g of N,N-dimethylformamide, was added dropwise, and the reaction was carried out at 60°C for 4 hours. After the reaction was complete, the reaction solution was transferred to a separatory funnel, and the organic phase was washed with 500 g of methyl isobutyl ketone and 500 g of 1% oxalic acid solution. After separating the aqueous phase, the obtained organic phase was washed several times with water. Then, it was concentrated using an evaporator, and the residue was added dropwise to 400 g of methanol / water = 7 / 3 (v / v) solution to obtain a precipitate. The precipitate was collected by suction filtration and washed several times with 200 g of methanol. Then, Compound (A-12) was obtained by drying in a vacuum dryer at 60°C for 12 hours. The Mw of compound (A-12) was 1122.

[0099] [Comparative Synthesis Example 1-1] (Synthesis of Polymer (x-1)) In a reaction vessel, under a nitrogen atmosphere, 250.0 g of m-cresol, 125.0 g of 37% by mass formalin, and 2 g of oxalic anhydride were added. The mixture was reacted at 100°C for 3 hours and then at 180°C for 1 hour. After that, unreacted monomers were removed under reduced pressure to obtain polymer (x-1) represented by the following formula (x-1). The Mw of the obtained polymer (x-1) was 11,000.

[0100]

[0101]

[0102] <Preparation of composition for forming a resist underlayer film> The following describes the [A] compound, [B] solvent, [C] acid generator and base generator, [D] crosslinking agent and other components used in the preparation of the composition for forming a resist underlayer film (hereinafter also referred to as "the composition").

[0103] [[A] Compounds] A-1 to A-18: The compounds (A-1) to (A-18) prepared above.

[0104] [B Solvent] B-1: Propylene glycol monomethyl ether acetate B-2: Cyclohexanone

[0105] [C] Acid Generators and Base Generators C-1: Compound represented by the following formula (C-1) C-2: Compound represented by the following formula (C-2)

[0106] [D] Crosslinking agent: D-1: Compound represented by the following formula (D-1) D-2: Compound represented by the following formula (D-2)

[0107] [Other components] x-1: The polymer synthesized above (x-1)

[0108] [Example 2-1] [A] 3 parts by mass of (A-1) as compound was dissolved in [B] 97 parts by mass of (B-1) as solvent. The resulting solution was filtered through a polytetrafluoroethylene (PTFE) membrane filter with a pore size of 0.45 μm to prepare composition (J-1).

[0109] [Examples 2-2 to 2-27 and Comparative Example 2-1] Compositions (J-2) to (J-27) and (CJ-1) were prepared in the same manner as in Example 2-1, except that the types and amounts of each component shown in Table 2 below were used. A "-" in Table 2 indicates that the corresponding component was not used.

[0110]

[0111] <Evaluation> [Examples 3-1 to 3-27 and Comparative Example 3-1] The embedding properties and bending resistance were evaluated using the above-prepared resist underlayer film forming compositions by the following method. The evaluation results are shown in Table 3 below.

[0112] [Embedding Properties] The above resist underlayer film formation composition was applied to a substrate on which trench patterns with a depth of 65 nm and widths of 20 nm and 30 nm were formed, using a spin coater (LITHIUS Pro Z from Tokyo Electron Limited) by rotary coating. The rotation conditions of the spin coater were set to obtain a film-coated substrate with an average thickness of 100 nm. Next, the substrate was heated at 400°C for 90 seconds in an air atmosphere, and then cooled at 23°C for 60 seconds. The cross-sectional shape of the substrate was observed (200,000x magnification) using a scanning electron microscope (S-4800 from Hitachi High-Technologies Corporation) to evaluate its embedding properties. The embedding performance was evaluated as follows: "A" (good) if the resist underlayer film was embedded to the bottom of the 20 nm wide trench pattern on the substrate; "B" (fairly good) if it was not embedded to the bottom of the 20 nm wide trench pattern but was embedded to the bottom of the 30 nm wide trench pattern; and "C" (poor) if it was not embedded to the bottom of the 30 nm wide trench pattern.

[0113] [Bending Resistance] The above-prepared composition was coated onto a silicon substrate on which a silicon dioxide film with an average thickness of 500 nm had been formed, using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Limited) by rotary coating. Next, the substrate was heated at 350°C for 60 seconds in an air atmosphere, and then cooled at 23°C for 60 seconds to obtain a film-coated substrate on which a resist underlayer film with an average thickness of 200 nm had been formed. On the above-prepared film-coated substrate, a silicon-containing film-forming composition (NFC SOG080 from JSR Corporation) was coated by rotary coating, and then heated at 200°C for 60 seconds in an air atmosphere, and further heated at 300°C for 60 seconds to form a silicon-containing film with an average thickness of 50 nm. An ArF resist composition (AR1682J from JSR Corporation) was coated onto the silicon-containing film using a rotary coating method, and the resist film was heated (fired) at 130°C for 60 seconds in an air atmosphere to form a resist film with an average thickness of 200 nm. The resist film was exposed using an ArF excimer laser exposure apparatus (lens numerical aperture 0.78, exposure wavelength 193 nm) through a 1:1 line-and-space mask pattern with a target size of 100 nm, with varying exposure levels. After exposure, the resist film was heated (fired) at 130°C for 60 seconds in an air atmosphere, developed at 25°C for 1 minute using a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH), washed with water, and dried to obtain a substrate on which a line-and-space resist pattern with a 200 nm pitch and line widths ranging from 30 nm to 100 nm was formed.

[0114] Using the above resist pattern as a mask, the above etching apparatus is used to CF ４ Under the conditions of =200 sccm, PRESS. =85 mT, HF RF (high-frequency power for plasma generation) =500 W, LF RF (high-frequency power for bias) =0 W, DCS = -150 V, and RDC (gas center flow rate ratio) =50%, a silicon-containing film was etched to obtain a substrate with a pattern formed on the silicon-containing film. Next, using the silicon-containing film pattern as a mask, the etching apparatus was used to etch O ２Under the conditions of =400 sccm, PRESS. =25 mT, HF RF (high-frequency power for plasma generation) =400 W, LF RF (high-frequency power for bias) =0 W, DCS =0 V, and RDC (gas center flow rate ratio) =50%, the resist underlayer film was etched to obtain a substrate with a pattern formed on the resist underlayer film. Using the above resist underlayer film pattern as a mask, the above etching apparatus was used to CF ４ Under the conditions of 180 sccm, Ar = 360 sccm, PRESS. = 150 mT, HF RF (high-frequency power for plasma generation) = 1,000 W, LF RF (high-frequency power for bias) = ​​1,000 W, DCS = -150 V, RDC (gas center flow rate ratio) = 50%, and 60 seconds, a silicon dioxide film was etched to obtain a substrate with a pattern formed on the silicon dioxide film.

[0115] Subsequently, for the substrate on which the silicon dioxide film pattern was formed, images of the shape of the resist underlayer film pattern for each line width were obtained by magnifying 250,000 times using a scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4000"). By processing these images, as shown in Figure 1, the LER (line edge roughness) was defined as the standard deviation of 3 times the average position Xa calculated from the position Xn (n=1 to 10) in the line width direction, which was measured at 10 locations at 100 nm intervals on the lateral surface 3a of the resist underlayer film pattern 3 (line pattern) with a length of 1,000 nm, and the average position Xa of these positions in the line width direction. The LER, which indicates the degree of curvature of the resist underlayer film pattern, increases as the line width of the resist underlayer film pattern becomes narrower. Bending resistance was evaluated as follows: "A" (good) if the line width of the film pattern with a LER of 5.5 nm was less than 40.0 nm; "B" (fairly good) if it was between 40.0 nm and 45.0 nm; and "C" (poor) if it was 45.0 nm or more. Note that the degree of bending of the film pattern shown in Figure 1 is exaggerated compared to the actual degree.

[0116]

[0117] As can be seen from the results in Table 3, the compositions of the examples and the resist underlayer films formed from these compositions exhibited superior embedding properties and bending resistance compared to the comparative examples.

[0118] The resist underlayer film formation composition of the present invention makes it possible to form a resist underlayer film with excellent embedding properties and bending resistance. The semiconductor substrate manufacturing method of the present invention makes it possible to form a resist underlayer film that not only has sufficient embedding properties to adequately embed the substrate pattern, but also has excellent bending resistance after embedding. Therefore, these can be suitably used in the manufacture of semiconductor devices, for which further miniaturization is expected in the future.

[0119] 3. Resist underlayer pattern 3a. Side view of the resist underlayer pattern

Claims

1. A composition for forming a resist underlayer film, comprising a sulfur-containing compound and a solvent, wherein the sulfur-containing compound is a compound represented by the following formula (1). (In formula (1), Ar is a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. X is a sulfur atom, -S(=O)- or -S(=O) ２ - n is an integer between 4 and 8. Multiple Ars and X are either identical or different from one another.

2. The resist underlayer film forming composition according to claim 1, wherein the aromatic ring has at least one monovalent group selected from the group consisting of a hydroxyl group, a sulfanyl group, a nitro group, and a monovalent organic group having 1 to 20 carbon atoms.

3. The resist underlayer film forming composition according to claim 1 or 2, wherein the aromatic ring is a benzene ring.

4. The resist underlayer film forming composition according to claim 1 or 2, wherein n is 4 or 6.

5. A method for manufacturing a semiconductor substrate, comprising the steps of: coating a resist underlayer film forming composition directly or indirectly onto a substrate; directly or indirectly forming a resist pattern on the resist underlayer film formed by the coating step; and etching using the resist pattern as a mask, wherein the resist underlayer film forming composition contains a sulfur-containing compound and a solvent, and the sulfur-containing compound is a compound represented by the following formula (1). (In formula (1), Ar is a substituted or unsubstituted aromatic ring having 3 to 20 carbon atoms. X is a sulfur atom, -S(=O)- or -S(=O) ２ - n is an integer between 4 and 8. Multiple Ars and X are either identical or different from one another.

6. The method for manufacturing a semiconductor substrate according to claim 5, wherein the aromatic ring has at least one monovalent group selected from the group consisting of a hydroxyl group, a sulfanyl group, a nitro group, and a monovalent organic group having 1 to 20 carbon atoms.

7. The method for manufacturing a semiconductor substrate according to claim 5 or 6, wherein the aromatic ring is a benzene ring.

8. The method for manufacturing a semiconductor substrate according to claim 5 or 6, wherein n is 4 or 6.

Images