Resist underlayer composition and method of forming pattern using the same

Abstract

To provide a resist underlayer film which does not cause pattern collapse of a resist even in a fine patterning process, has improved sensitivity to an exposure light source, and has improved patterning performance and energy efficiency, and to provide a pattern forming method using the same.SOLUTION: The resist underlayer composition may include a polymer including a hydroxystyrene structural unit having a specific structure and a structural unit represented by Chemical Formula 2, and a solvent, wherein the hydroxystyrene structural unit having a specific structure and the structural unit represented by Chemical Formula 2 may be included in a mole ratio of about 13:1 to about 1:1.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present description relates to a composition for a resist underlayer film and a pattern forming method using the same. [Background technology]

[0002] In recent years, the semiconductor industry has evolved from patterns of hundreds of nanometers to ultrafine technology with patterns of several to tens of nanometers, and effective lithography techniques are essential to realize such ultrafine technology.

[0003] Lithography is a processing method in which a thin film of photoresist is coated on a semiconductor substrate such as a silicon wafer to form a thin film, which is then irradiated with activating radiation such as ultraviolet light through a mask pattern on which a device pattern is drawn, and then developed.The resulting photoresist pattern is used as a protective film to etch the substrate, thereby forming a fine pattern on the surface of the substrate that corresponds to the pattern described above.

[0004] As semiconductor patterns become increasingly finer, the thickness of the photoresist layer must be smaller, which in turn requires a thinner resist underlayer. The resist underlayer must not collapse the photoresist pattern even at a thin thickness, have good adhesion to the photoresist, and be formed with a uniform thickness. Additionally, the resist underlayer must have a high refractive index and a low absorption coefficient for the light used in photolithography, as well as a faster etching rate than the photoresist layer. Summary of the Invention [Problem to be solved by the invention]

[0005] The composition for a resist underlayer film according to one embodiment provides a resist underlayer film that does not cause resist pattern collapse even in a fine patterning process, has improved sensitivity to an exposure light source, and has improved patterning performance and energy efficiency.

[0006] In another embodiment, there is provided a pattern forming method using the above-described resist underlayer film composition. [Means for solving the problem]

[0007] A composition for a resist underlayer film according to one embodiment includes a polymer including a structural unit represented by the following Chemical Formula 1 and a structural unit represented by the following Chemical Formula 2, and a solvent, wherein the structural unit represented by Chemical Formula 1 and the structural unit represented by Chemical Formula 2 are contained in the polymer in a molar ratio of 13:1 to 1:1.

[0008] [ka]

[0009] In the above chemical formula 1, R 1 and R 2 are each independently hydrogen, deuterium, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, n is 1 or 2, and * is a linking site.

[0010] [ka]

[0011] In the above chemical formula 2, Z 1 is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 20 carbon atoms, -(C=O)0R a (where R a is hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.), -S(=O)R b (where R bis a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms), -SiR c R d R e (where R c ~R e are each independently a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, or a combination thereof, R 3 and R 4 are each independently hydrogen, deuterium, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, m is an integer from 1 to 3; * indicates the linkage site.

[0012] Z in Chemical Formula 2 1 is -(C=O)0R a (where R a is hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.

[0013] In Chemical Formula 2, m may be 1.

[0014] Chemical Formula 1 can be represented by the following Chemical Formula 1-1 or Chemical Formula 1-2.

[0015] [ka]

[0016] Chemical formula 2 can be represented by the following chemical formula 2-1.

[0017] [ka]

[0018] The structural unit represented by Chemical Formula 1 and the structural unit represented by Chemical Formula 2 may be contained in the polymer in a molar ratio of 6:1 to 1:1.

[0019] The weight average molecular weight of the polymer may be from 1,000 g / mol to 100,000 g / mol.

[0020] The polymer may be contained in an amount of 0.1% by weight to 2% by weight based on the total weight of the composition for a resist underlayer film.

[0021] The composition may further include one or more polymers selected from acrylic resins, epoxy resins, novolac resins, glycoluril resins, and melamine resins.

[0022] The composition can further include an additive that is a surfactant, a thermal acid generator, a photoacid generator, a plasticizer, or a combination thereof.

[0023] According to another embodiment, there is provided a pattern forming method including the steps of: forming a film to be etched on a substrate; applying a resist underlayer film composition according to an embodiment onto the film to be etched to form a resist underlayer film; forming a photoresist pattern on the resist underlayer film; and sequentially etching the resist underlayer film and the film to be etched using the photoresist pattern as an etching mask. [Effects of the Invention]

[0024] The composition for a resist underlayer film according to one embodiment can provide a resist underlayer film that does not cause resist pattern collapse even in a fine patterning process, has improved sensitivity to an exposure light source, and can improve patterning performance and energy efficiency. [Brief explanation of the drawings]

[0025] [Figure 1]1 is a cross-sectional view illustrating a pattern forming method using a resist underlayer film composition according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Although the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein, the present invention will be described in detail below so as to enable those skilled in the art to easily practice the present invention.

[0027] In the drawings, the thickness of various layers and regions has been exaggerated to clearly show them, and the same reference numerals have been used to refer to similar parts throughout the specification. When a layer, film, region, plate, or other part is said to be "on" another part, this includes not only the case where it is "directly on" another part, but also the case where there is another part between them. Conversely, when a part is said to be "directly on" another part, it means that there is no other part between them.

[0028] Hereinafter, unless otherwise defined in this specification, "substituted" means that a hydrogen atom in a compound has been replaced with a deuterium atom, a halogen atom (F, Br, Cl, or I), a hydroxy group, a nitro group, a cyano group, an amino group, an azide group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamoyl group, a thiol group, an ester group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, It means being substituted with a substituent selected from an alkynyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a heteroalkyl group having 1 to 20 carbon atoms, a heteroarylalkyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a cycloalkenyl group having 3 to 15 carbon atoms, a cycloalkynyl group having 6 to 15 carbon atoms, a heterocyclic group having 2 to 30 carbon atoms, and combinations thereof.

[0029] Furthermore, two adjacent substituents selected from a substituted halogen atom (F, Br, Cl, or I), a hydroxy group, a nitro group, a cyano group, an amino group, an azide group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamoyl group, a thiol group, an ester group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an alkynyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a heteroalkyl group having 1 to 20 carbon atoms, a heteroarylalkyl group having 3 to 20 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, a cycloalkenyl group having 3 to 15 carbon atoms, a cycloalkynyl group having 6 to 15 carbon atoms, or a heterocyclic group having 2 to 30 carbon atoms may be fused to form a ring.

[0030] As used herein, the term "heterocyclic group" encompasses heteroaryl groups and also refers to groups containing at least one heteroatom selected from N, O, S, P, and Si in place of carbon (C) in a ring compound such as an aryl group, a cycloalkyl group, a fused ring thereof, or a combination thereof. When a heterocyclic group is a fused ring, the entire heterocyclic group or each ring may contain one or more heteroatoms.

[0031] More specifically, the substituted or unsubstituted aryl group and / or the substituted or unsubstituted heterocyclic group are a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted anthracenyl group, a substituted or unsubstituted phenanthryl group, a substituted or unsubstituted naphthacenyl group, a substituted or unsubstituted pyrenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted quaterphenyl group, a substituted or unsubstituted chrysenyl group, a substituted or unsubstituted triphenyl group, a substituted or unsubstituted thiazolinyl ... A phenylenyl group, a substituted or unsubstituted perylenyl group, a substituted or unsubstituted indenyl group, a substituted or unsubstituted furanyl group, a substituted or unsubstituted thiophenyl group, a substituted or unsubstituted pyrrolyl group, a substituted or unsubstituted pyrazolyl group, a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted triazolyl group, a substituted or unsubstituted oxazolyl group, a substituted or unsubstituted thiazolyl group, a substituted or unsubstituted oxadiazolyl group, a substituted or unsubstituted thiadiazolyl group, a substituted or unsubstituted pyridinyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted benzofuranyl group, a substituted or unsubstituted benzothiophenyl group, a substituted or unsubstituted benzimidazolyl group, a substituted or unsubstituted indolyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted isoquinolinyl group, a substituted or unsubstituted quinazolinyl group, a substituted or unsubstituted quinoxalinyl group, a substituted or unsubstituted naphthyridinyl group, a substituted or unsubstituted substituted or unsubstituted benzoxazinyl group, substituted or unsubstituted benzothiazinyl group, substituted or unsubstituted acridinyl group, substituted or unsubstituted phenazinyl group, substituted or unsubstituted phenothiazinyl group, substituted or unsubstituted phenoxazinyl group, substituted or unsubstituted fluorenyl group, substituted or unsubstituted dibenzofuranyl group, substituted or unsubstituted dibenzothiophenyl group, substituted or unsubstituted carbazolyl group, pyridoindolyl group, benzopyridoxazinyl group, benzopyridothiazinyl group, 9,9-dimethyl-9,10-dihydroacridinyl group, a combination thereof, or a fused form of a combination thereof, but is not limited thereto.

[0032] Unless otherwise specified herein, "combination" means blending or copolymerization.

[0033] In addition, in this specification, the term "polymer" can include both oligomers and polymers.

[0034] Unless otherwise specified in this specification, the "weight average molecular weight" is measured by dissolving a powder sample in tetrahydrofuran (THF) and then using Agilent Technologies' 1200 series gel permeation chromatography (GPC) (using a Shodex LF-804 column and Shodex polystyrene as the standard sample).

[0035] Additionally, unless otherwise defined herein, "*" refers to a structural unit of a polymer or a linking site of a moiety of a polymer.

[0036] The semiconductor industry is constantly seeking to reduce chip size. To meet this trend, the linewidth of resist patterns formed in lithography must be reduced to the tens of nanometers. This pattern can then be used to etch the underlying substrate, thereby transferring the pattern to the underlying material. However, as the resist pattern size decreases, the aspect ratio of the resist that can be maintained at that linewidth becomes limited, which can result in the resist not being sufficiently durable during the etching process. Therefore, resist underlayers have been used to compensate for this when using thin resist materials, when the substrate to be etched is thick, or when deep patterns are required.

[0037] As the resist thickness decreases, the resist underlayer film must become thinner. However, even if the resist underlayer film is thin, the photoresist pattern must not collapse. Therefore, the resist underlayer film must have excellent adhesion to the photoresist. Furthermore, when a thin resist underlayer film is formed, the coating uniformity of the resist underlayer film composition and the flatness of the resist underlayer film formed therefrom must be improved. Furthermore, the sensitivity to the exposure light source must be improved, thereby improving pattern formability and energy efficiency.

[0038] According to one embodiment, the composition for an underlayer film includes a polymer including a structural unit represented by the following Chemical Formula 1 and a structural unit represented by the following Chemical Formula 2, and a solvent, wherein the structural unit represented by Chemical Formula 1 and the structural unit represented by Chemical Formula 2 are contained in the polymer in a molar ratio of 13:1 to 1:1.

[0039] [ka]

[0040] In the above chemical formula 1, R 1 and R 2 are each independently hydrogen, deuterium, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, n is 1 or 2, and * is a linking site.

[0041] [ka]

[0042] In the above chemical formula 2, Z 1 is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 20 carbon atoms, -(C=O)0R a (where R ais hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.), -S(=O)R b (where R b is a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms), -SiR c R d R e (where R c ~R e are each independently a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, or a combination thereof, R 3 and R 4 are each independently hydrogen, deuterium, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, m is an integer from 1 to 3; * indicates the linkage site.

[0043] In one embodiment, the composition is such that, upon exposure, the substituent -(OZ 1 )'s Z 1 is dissociated by the acid. As a result, the polymer is 1 ) is converted to a hydroxy group, thereby increasing the content of hydroxy groups in the polymer. This improves the adhesion between the resist underlayer film formed from the composition and the photoresist, and suppresses pattern collapse.

[0044] In addition, in one embodiment of the composition for a resist underlayer film, the polymer contains a structural unit represented by Chemical Formula 1 and a structural unit represented by Chemical Formula 2 in a molar ratio of 13:1 to 1:1, thereby increasing the adhesion of the resist underlayer film prepared from the composition to the photoresist, thereby suppressing pattern collapse.

[0045] In Chemical Formula 2, Z 1 is, for example, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 20 carbon atoms, -(C=O)0R a (where R a is hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.), -S(=O)R b (where R b is a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms), or a combination thereof, such as a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 20 carbon atoms, -(C=O)0R a (where R a is hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, or a combination thereof, such as -(C=O)0R a (where R a is hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.) However, it is not limited to these. As an example, R a is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, but is not limited thereto.

[0046] In Chemical Formula 1 and Chemical Formula 2, R1 ~R 4 are each independently hydrogen, deuterium, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, such as, but not limited to, hydrogen.

[0047] As an example, Chemical Formula 1 can be represented by the following Chemical Formula 1-1 or Chemical Formula 1-2.

[0048] [ka]

[0049] As an example, Chemical Formula 2 can be represented by the following Chemical Formula 2-1.

[0050] [ka]

[0051] In one embodiment, the polymer comprises the structural units represented by Chemical Formula 1 and the structural units represented by Chemical Formula 2 in a molar ratio of, but not limited to, 12:1 to 1:1, 11:1 to 1:1, 10:1 to 1:1, 9:1 to 1:1, 8:1 to 1:1, 7:1 to 1:1, 6:1 to 1:1, or 5:1 to 1:1.

[0052] The polymer may have a weight-average molecular weight of 1,000 g / mol to 100,000 g / mol, such as, but not limited to, 3,000 g / mol to 100,000 g / mol, 3,000 g / mol to 90,000 g / mol, 3,000 g / mol to 70,000 g / mol, 3,000 g / mol to 70,000 g / mol, 3,000 g / mol to 50,000 g / mol, 5,000 g / mol to 50,000 g / mol, or 5,000 g / mol to 30,000 g / mol. By having a weight-average molecular weight within this range, the carbon content and solubility in a solvent of a resist underlayer film composition containing the polymer can be adjusted and optimized.

[0053] The polymer may be contained in an amount of 0.1 wt % to 2 wt % based on the total weight of the composition for a resist underlayer film. More specifically, the polymer may be contained in an amount of, for example, 0.1 wt % to 1.5 wt %, 0.1 wt % to 1.0 wt %, or 0.1 wt % to 0.5 wt % based on the total weight of the composition for a resist underlayer film, but is not limited thereto. By containing the polymer in the composition in the above ranges, the thickness, surface roughness, and level of planarization of the resist underlayer film can be adjusted.

[0054] The resist underlayer film composition according to an embodiment may contain a solvent. The solvent is not particularly limited as long as it has sufficient solubility and / or dispersibility for the polymer and compound according to an embodiment. For example, the solvent may include, but is not limited to, propylene glycol, propylene glycol diacetate, methoxypropanediol, diethylene glycol, diethylene glycol butyl ether, tri(ethylene glycol) monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, gamma-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, methylpyrrolidone, methylpyrrolidinone, methyl 2-hydroxyisobutyrate, acetylacetone, ethyl 3-ethoxypropionate, or a combination thereof.

[0055] The composition for a resist underlayer film according to an embodiment may further include, in addition to the polymer and the solvent, one or more polymers selected from an acrylic resin, an epoxy resin, a novolac resin, a glycoluril resin, and a melamine resin, but is not limited thereto.

[0056] In addition, the composition for a resist underlayer film according to another embodiment may further include additives including a surfactant, a thermal acid generator, a plasticizer, or a combination thereof.

[0057] The surfactant may be used to improve coating defects caused by an increase in solid content during the formation of the resist underlayer film. Examples of surfactants that may be used include, but are not limited to, alkylbenzene sulfonates, alkylpyridinium salts, polyethylene glycols, and quaternary ammonium salts.

[0058] Examples of the thermal acid generator that can be used include, but are not limited to, acidic compounds such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonate, salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, hydroxybenzoic acid, and naphthalenecarboxylic acid, and / or benzoin tosylate, 2-nitrobenzyl tosylate, and other organic sulfonic acid alkyl esters.

[0059] The plasticizer is not particularly limited, and various known plasticizers can be used. Examples of the plasticizer include low molecular weight compounds such as phthalates, adipates, phosphates, trimellitates, and citrates, as well as polyether, polyester, and polyacetal compounds.

[0060] The additive may be contained in an amount of 0.001 to 40 parts by weight relative to 100 parts by weight of the composition for a resist underlayer film. By containing the additive in the above range, the solubility of the composition for a resist underlayer film can be improved without changing the optical properties of the composition for a resist underlayer film.

[0061] According to another embodiment, there is provided a resist underlayer film formed using the composition for a resist underlayer film. The resist underlayer film may be in a form obtained by, for example, coating the composition for a resist underlayer film on a substrate and then curing it through a heat treatment process.

[0062] A method for forming a pattern using the above-described composition for a resist underlayer film will be described below with reference to Fig. 1. Fig. 1 is a cross-sectional view illustrating the method for forming a pattern using the composition for a resist underlayer film according to the present invention.

[0063] Referring to FIG. 1(a), first, an etching target is prepared. An example of the etching target may be a thin film 102 formed on a semiconductor substrate 100. The following description will be given of the case where the etching target is the thin film 102. The surface of the thin film 102 is cleaned to remove contaminants remaining on the thin film 102. The thin film 102 may be, for example, a silicon nitride film, a polysilicon film, or a silicon oxide film.

[0064] Next, the above-mentioned resist underlayer film composition is coated on the surface of the cleaned thin film 102 by spin coating.

[0065] Thereafter, drying and baking steps are performed to form a resist underlayer film 104 on the thin film. The baking process is performed at 100°C to 300°C, for example, 100°C to 200°C. A more specific explanation of the composition for the resist underlayer film has already been given in detail, so it will be omitted to avoid duplication.

[0066] Referring to FIG. 1( b ), a photoresist is coated on the resist underlayer film 104 to form a photoresist film 106 .

[0067] Examples of photoresists include negative tone photoresists containing a naphthoquinone diazide compound and a novolak resin, chemically amplified negative tone photoresists containing an acid generator capable of dissociating an acid upon exposure, a compound that decomposes in the presence of acid to increase its solubility in organic solvents, and an organic solvent-soluble resin, and chemically amplified negative tone photoresists containing an acid generator and an organic solvent-soluble resin having a group that can decompose in the presence of acid to give a resin that increases its solubility in organic solvents.

[0068] Next, a first baking step is performed to heat the substrate 100 on which the photoresist film 106 is formed. The first baking step can be performed at a temperature of 90°C to 120°C.

[0069] 1(c), the photoresist film 106 is selectively exposed. To illustrate the exposure process for exposing the photoresist film 106, an exposure mask 110 having a predetermined pattern formed thereon is placed on a mask stage of an exposure tool, and the exposure mask 110 is then placed on the photoresist film 106. Next, light is irradiated onto the mask 110, so that predetermined portions of the photoresist film 106 formed on the substrate 100 selectively react with the light transmitted through the exposure mask.

[0070] Examples of light that can be used in the exposure process include short wavelength light such as activating radiation i-rays having a wavelength of 365 nm, KrF excimer lasers having a wavelength of 248 nm, and ArF excimer lasers having a wavelength of 193 nm, as well as extreme ultraviolet (EUV) light having a wavelength of 13.5 nm.

[0071] The photoresist film 106b in the exposed region has a relatively low solubility in an organic solvent compared to the photoresist film 106a in the unexposed region, and therefore the photoresist film in the exposed region 106b and the photoresist film in the unexposed region 106a have different solubilities.

[0072] Next, a second baking process is performed on the substrate 100. The second baking process can be performed at a temperature of 90° C. to 150° C. By performing the second baking process, the photoresist film corresponding to the unexposed region becomes less soluble in a particular organic solvent.

[0073] Referring to FIG. 1(d), specifically, the photoresist film 106a corresponding to the non-exposed region is dissolved and removed using n-butyl acetate, etc., and the remaining photoresist film 106b forms the photoresist pattern 108.

[0074] Next, the resist underlayer film 104 is etched using the photoresist pattern 108 as an etching mask. The above-described etching process forms an organic film pattern 112 as shown in FIG. 1(e). The etching can be performed, for example, by dry etching using an etching gas, such as CHF, CF, Cl, O, or a mixture thereof. As described above, the resist underlayer film formed using the resist underlayer film composition according to one embodiment has a high etching rate, allowing for a smooth etching process to be performed in a short time.

[0075] 1(f), the photoresist pattern 108 is used as an etching mask to etch the exposed thin film 102. As a result, the thin film 102 is shaped into a thin film pattern 114. The thin film pattern 114 formed by the previous exposure process using short wavelength light such as activating radiation i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), or ArF excimer laser (wavelength 193 nm) may have a width of tens to hundreds of nm, and the thin film pattern 114 formed by the exposure process using an EUV light source may have a width of 20 nm or less. [Example]

[0076] The present invention will be described in more detail below through examples of the synthesis of the above polymer and the formation of a resist underlayer film composition containing the same, but the present invention is not technically limited by the following examples.

[0077] Polymer synthesis Synthesis Example 1 The structural unit represented by the following chemical formula 1-1 was purchased from Nippon Soda Corporation as a VP-8000 product and used. The structural unit represented by the following chemical formula 2-2 was synthesized as follows: 15 g of poly(hydroxystyrene), 50 g of ethyl acetate, and 12 g of trimethylamine were added to 125 g of PGMEA in a 500 ml three-necked round-bottom flask, and the resulting reaction solution was heated to 70°C for 3 hours to carry out the reaction. The reaction solution was then cooled to room temperature. 7 g of acetic acid was added to neutralize the mixture, and after washing with water, the organic layer was dissolved in PGMEA.

[0078] Through the above process, a polymer consisting of structural units represented by the following chemical formula 1-1 and structural units represented by the following chemical formula 2-2 was obtained. The molar ratio of the structural units represented by the following chemical formula 1-1 to the structural units represented by the following chemical formula 2-2 was 3:1, and the weight average molecular weight (Mw) of the polymer was 14,000 g / mol.

[0079] [ka]

[0080] Synthesis Example 2 By varying the content of reactants, a polymer having a molar ratio of structural units represented by Chemical Formula 1-1 to structural units represented by Chemical Formula 2-2 of 5:1 was obtained in the same manner as in Synthesis Example 1 (weight average molecular weight (Mw): 10,000 g / mol).

[0081] Synthesis Example 3 By varying the content of reactants, a polymer having a molar ratio of structural units represented by Chemical Formula 1-1 to structural units represented by Chemical Formula 2-2 of 12:1 was obtained in the same manner as in Synthesis Example 1 (weight average molecular weight (Mw): 9,000 g / mol).

[0082] Comparative synthesis example 1 25.57 g of propylene glycol methyl ether acetate (PGMEA) was added to a 500 ml three-neck round-bottom flask (Solution 1), connected to a condenser, and nitrogen bubbling was performed for 10 minutes. A reaction solution (Solution 2) was prepared by mixing 32.04 g of methyl methacrylate, 22.74 g of glycidyl methacrylate, 16.58 g of dimethyl 2,2'-azobis(2-methylpropionate) (V-601; TCI), and 102.26 g of propylene glycol methyl ether acetate (PGMEA). The reaction solution was added dropwise to Solution 1 heated to 85°C for 1 hour. After the reaction solution was added, it was stirred for an additional 2 hours. After cooling to room temperature, the reaction solution was added dropwise to a beaker containing 600 g of heptane while stirring to form a gum, which was then dissolved in 120 g of PGMEA.

[0083] Comparative synthesis example 2 The polymer consisting of the structural unit represented by the following chemical formula 3 was purchased and used (Merck 81406).

[0084] [ka]

[0085] Comparative synthesis example 3 The polymer consisting of the structural unit represented by the following chemical formula 1-1 was purchased and used (Nippon Soda VP-8000).

[0086] [ka]

[0087] Comparative Synthesis Example 4 By varying the content of reactants, a polymer having a molar ratio of structural units represented by Chemical Formula 1-1 to structural units represented by Chemical Formula 2-2 of 1:2 was obtained in the same manner as in Synthesis Example 1 (weight average molecular weight (Mw): 15,000 g / mol).

[0088] Preparation of Resist Underlayer Film Composition Examples and Comparative Examples 1.2 g of each polymer obtained from the Synthesis Example and Comparative Synthesis Example, 0.4 g of a crosslinker (PL1174), and 0.04 g of pyridinium paratoluenesulfonate (PPTS) were mixed and completely dissolved in 15 g of propylene glycol monomethyl ether, and the mixture was diluted with additional solvent to prepare resist underlayer film compositions of the Examples and Comparative Examples, each containing 0.5 wt % of the polymer based on the total weight.

[0089] Evaluation: Line width roughness (LWR) and pattern collapse evaluation The compositions prepared in the Examples and Comparative Examples were spin-coated and then heat-treated on a hot plate at 205°C for 60 seconds to form a 5nm thick resist underlayer film. A photoresist solution was then spin-coated onto the underlayer film and heat-treated on a hot plate at 110°C for 1 minute to form a photoresist layer. The resist layer was exposed to light using an e-beam exposure tool (Elionix, accelerating voltage 100 keV) with a line width of 30nm and a space width of 30nm. The resist was then heat-treated at 95°C for 60 seconds and developed with n-butyl acetate for 60 seconds to form a resist pattern.

[0090] Pattern collapse was evaluated by observing the formed patterns with a scanning electron microscope (SEM) S-9260 (manufactured by Hitachi). The results are shown in Table 1 below. In Table 1, cases where pattern collapse was observed are indicated by O, and cases where it was not observed are indicated by X.

[0091] Line width roughness (LWR) was measured by observing a pattern formed with a width of 30 nm using a scanning electron microscope (SEM) S-9260 (manufactured by Hitachi) and measuring the distance that the edge deviated from the reference line where the edge should exist within a 2 μm range in the longitudinal direction of the pattern. The results are shown in Table 1, and the smaller the value of LWR, the better.

[0092] The measured LWR evaluation values ​​of the examples and comparative examples were converted into a ratio using the LWR value of Comparative Example 3 as the reference value according to the following formula. The results are shown in Table 1 below. The smaller the line width roughness (LWR) value, the better the pattern formability and sensitivity. *LWR (%) = {(LWR in each experimental example - LWR in comparative example 3) / LWR in comparative example 3} × 100

[0093] [Table 1]

[0094] Referring to Table 1 above, it can be seen that the resist underlayer films obtained from the resist underlayer film compositions of Examples 1 to 3 have smaller line width roughness values ​​and no pattern collapse is observed compared to the thin films obtained from the compositions of Comparative Examples 1 to 4, and therefore have excellent fine pattern formability and sensitivity.

[0095] As mentioned above, although specific embodiments of the present invention have been described and illustrated, the present invention is not limited to the described embodiments, and it will be obvious to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, such modifications or variations should not be understood separately from the technical spirit and perspective of the present invention, and the modified embodiments should be considered to fall within the scope of the claims of the present invention. [Explanation of symbols]

[0096] 100: Substrate 102: Thin film 104: Resist underlayer film 106: Photoresist film 106a: Unexposed area 106b: Exposed area 108: Photoresist pattern 110: Mask 112: Organic film pattern 114: Thin film pattern

Claims

1. The present invention includes a polymer including a structural unit represented by the following Chemical Formula 1 and a structural unit represented by the following Chemical Formula 2, and a solvent, wherein the structural unit represented by the Chemical Formula 1 and the structural unit represented by the Chemical Formula 2 are contained in the polymer in a molar ratio of 13:1 to 1:1, 【Chemistry 1】 In the above Chemical Formula 1, R １ and R ２ are each independently hydrogen, deuterium, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms; n is 1 or 2, * is a linking point, 【Chemistry 2】 In chemical formula 2, Z １ represents a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted heterocycloalkyl group having 2 to 20 carbon atoms, -(C=O)OR ａ (wherein the R ａ is hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms), —S(═O) ２ R ｂ (wherein the R ｂ is a halogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms), —SiR ｃ R ｄ R ｅ (wherein the R ｃ ~R ｅ are each independently a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, or a combination thereof; R ３ and R ４ are each independently hydrogen, deuterium, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms; m is an integer from 1 to 3; * denotes a linking moiety. Resist underlayer film composition.

2. Z of Formula 2 １ is -(C=O)OR ａ (where R ａ is hydrogen, deuterium, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 20 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 20 carbon atoms.

3. The composition for a resist underlayer film according to claim 1 , wherein m in the formula (2) is 1.

4. The composition for a resist underlayer film according to claim 1, wherein the chemical formula 1 is represented by the following chemical formula 1-1 or 1-2: 【Transformation 3】

5. 2. The composition for a resist underlayer film according to claim 1, wherein the chemical formula 2 is represented by the following chemical formula 2-1: 【Chemistry 4】

6. 2. The composition for a resist underlayer film according to claim 1, wherein the structural unit represented by Chemical Formula 1 and the structural unit represented by Chemical Formula 2 are contained in the polymer in a molar ratio of 6:1 to 1:

1.

7. 2. The resist underlayer film composition according to claim 1, wherein the polymer has a weight average molecular weight of 1,000 g / mol to 100,000 g / mol.

8. 2. The composition for a resist underlayer film according to claim 1, wherein the polymer is contained in an amount of 0.1% by weight to 2% by weight based on the total weight of the composition for a resist underlayer film.

9. 2. The resist underlayer film composition according to claim 1, further comprising one or more polymers selected from the group consisting of acrylic resins, epoxy resins, novolac resins, glycoluril resins, and melamine resins.

10. The resist underlayer film composition according to claim 1 , further comprising an additive selected from the group consisting of a surfactant, a thermal acid generator, a photoacid generator, a plasticizer, and a combination thereof.

11. forming a film to be etched on a substrate; forming a resist underlayer film by applying the composition for a resist underlayer film according to any one of claims 1 to 10 onto the film to be etched; forming a photoresist pattern on the resist underlayer film; sequentially etching the resist underlayer film and the etching target film using the photoresist pattern as an etching mask; A pattern forming method comprising:

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