Resist Underlayer Composition and Method of Forming a Pattern Using the Composition

Abstract

The present invention discloses a resist underlayer composition, comprising a polymer containing a structural unit represented by Chemical Formula 1 and a solvent, and a method of forming a pattern using the resist underlayer composition. In Chemical Formula 1, each substituent is the same as defined in the detailed description. [Chemical Formula 1]

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2020 - 0011629, filed on January 31, 2020, with the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference. Technical field

[0003] The present disclosure relates to a resist underlayer composition and a method of forming a pattern using the composition. Background art

[0004] Recently, the semiconductor industry has developed ultra - fine technologies with patterns sized from a few nanometers to dozens of nanometers. Such ultra - fine technologies essentially require effective lithography techniques.

[0005] Performing exposure during the formation of a photoresist pattern is one of the important factors for obtaining a photoresist image with high resolution.

[0006] By exposing a photoresist using actinic radiation, the actinic radiation is generally reflected and thus limits the resolution of the patterned image in the photoresist layer. In particular, when the radiation is reflected at the interface between the substrate and the photoresist layer or on an interlayer hard mask, the actinic radiation scatters into the photoresist region, and the photoresist line width may become uneven and may obscure the pattern form.

[0007] In addition, a resist underlayer composition should absorb the reflected radiation, and at the same time have a high etch selectivity to the photoresist, and require chemical resistance to solvents and excellent adhesion to the photoresist in subsequent processes after thermal curing to assist in patterning the photoresist.

[0008] To reduce the reflected radiation, an organic layer (i.e., a so - called resist underlayer) has been provided between the substrate and the photoresist layer to attempt to absorb the light passing through the photoresist and at the same time improve the etch selectivity, chemical resistance, and adhesion to the photoresist.

[0009] In particular, as semiconductor patterns have gradually become finer, the use of actinic radiation for photoresist exposure has expanded to short wavelengths such as i - line (wavelength of 365 nm), KrF excimer laser (wavelength of 248 nm), ArF excimer laser (wavelength of 193 nm), etc., and thus, the demand for a resist underlayer suitable for a patterning process for forming ultra - fine patterns of about 10 nm by using an extreme ultraviolet (EUV) light source has increased. Summary of the invention

[0010] An embodiment provides a resist underlayer composition that can exhibit improved light absorption efficiency for EUV and thereby improve the sensitivity of a photoresist.

[0011] Another embodiment provides a method of forming a pattern using the resist underlayer composition.

[0012] According to an embodiment, the resist underlayer composition includes: a polymer including a structural unit represented by Chemical Formula 1 and a solvent.

[0013] [Chemical Formula 1]

[0014]

[0015] In Chemical Formula 1,

[0016] L 1 、L 2 and L 3 are independently a substituted or unsubstituted C1 to C10 alkylene, a substituted or unsubstituted C1 to C10 heteroalkylene, a substituted or unsubstituted C3 to C20 cycloalkylene, a substituted or unsubstituted C2 to C20 heterocycloalkylene, a substituted or unsubstituted C6 to C20 arylene, a substituted or unsubstituted C1 to C10 heteroarylene, a carbonyl group, an ester group, or a combination thereof,

[0017] R is hydrogen, deuterium, a halogen (-F, -Cl, -Br, or -I), a substituted or unsubstituted C1 to C10 alkyl, a substituted or unsubstituted C2 to C20 alkenyl, a substituted or unsubstituted C2 to C20 alkynyl, a substituted or unsubstituted C3 to C20 cycloalkyl, a substituted or unsubstituted C6 to C20 aryl, a substituted or unsubstituted C1 to C10 heteroalkyl, a substituted or unsubstituted C2 to C20 heteroalkenyl, a substituted or unsubstituted C3 to C20 heterocycloalkyl, or a substituted or unsubstituted C6 to C20 heteroaryl,

[0018] X 1 and X 2 are independently a halogen (-F, -Cl, -Br, or -I), a substituted or unsubstituted C1 to C10 alkyl, a substituted or unsubstituted C1 to C10 heteroalkyl, a substituted or unsubstituted C3 to C20 cycloalkyl, a substituted or unsubstituted C3 to C20 heterocycloalkyl, a substituted or unsubstituted C6 to C20 aryl, or a substituted or unsubstituted C6 to C20 heteroaryl, provided that at least one of X 1 and X 2 is selected from a halogen (-F, -Cl, -Br, or -I), and

[0019] k is an integer from 1 to 10, and * is a bonding point.

[0020] According to another embodiment, a method of forming a pattern includes: forming an etch target layer on a substrate, coating an underlayer resist composition according to an embodiment on the etch target layer to form an underlayer resist, forming a photoresist pattern on the underlayer resist, and sequentially etching the underlayer resist and the etch target layer using the photoresist pattern as an etch mask.

[0021] The underlayer resist composition according to an embodiment may exhibit improved light absorption efficiency for EUV, thereby improving the sensitivity of the photoresist. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figures 1 to 5 FIG. is a cross-sectional view for explaining a method of forming a pattern using an underlayer resist composition according to an embodiment.

[0023] DESCRIPTION OF REFERENCE NUMERALS

[0024] 100: semiconductor substrate;

[0025] 102: thin film;

[0026] 104: underlayer resist;

[0027] 106: photoresist layer;

[0028] 106a: exposed area;

[0029] 106b: unexposed area;

[0030] 108: photoresist pattern;

[0031] 110: exposure mask;

[0032] 112: organic layer pattern;

[0033] 114: thin film pattern. DETAILED DESCRIPTION

[0034] Exemplary embodiments of the present disclosure will be described in detail below and can be easily carried out by those skilled in the art. However, the present disclosure can be implemented in many different forms and should not be construed as limited to the exemplary embodiments set forth herein.

[0035] In the drawings, the thickness of layers, films, panels, regions, etc. may be exaggerated for clarity, and the same reference numerals throughout the specification denote the same elements. It will be understood that when an element, such as a layer, film, region, or substrate, is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, no intervening elements are present.

[0036] As used herein, when no definition is otherwise provided, "substituted" means that a hydrogen atom of a compound is replaced by a substituent selected from the following: a halogen group (-F, -Br, -Cl or -I), a hydroxyl group, an alkoxy group, a nitro group, a cyano group, an amino group, an azide group, an amidino group, a hydrazino group, a hydrazo 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, a vinyl group, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, a C6-C30 aryl group, a C7-C30 aralkyl group, a C6-C30 allyl group, a C1-C30 alkoxy group, a C1-C20 heteroalkyl group, a C3-C20 heteroarylalkyl group, a C3-C30 cycloalkyl group, a C3-C15 cycloalkenyl group, a C6-C15 cycloalkynyl group, a C3-C30 heterocycloalkyl group and combinations thereof.

[0037] As used herein, when no definition is otherwise provided, "hetero" means a heteroatom containing 1 to 3 heteroatoms selected from N, O, S and P.

[0038] Unless otherwise specified in this specification, the weight average molecular weight is measured by dissolving a powder sample in tetrahydrofuran (THF), and then using a 1200 series Gel Permeation Chromatography (GPC) from Agilent Technologies (the column is LF-804 from Shodex Company, and the standard sample is polystyrene from Shodex Company).

[0039] The resist underlayer composition according to an embodiment is described below.

[0040] The resist underlayer composition according to an embodiment includes: a polymer including a structural unit represented by Chemical Formula 1 and a solvent.

[0041] [Chemical Formula 1]

[0042]

[0043] In Chemical Formula 1,

[0044] L 1 、L 2 and L 3 are independently a substituted or unsubstituted C1-C10 alkylene group, a substituted or unsubstituted C1-C10 heteroalkylene group, a substituted or unsubstituted C3-C20 cycloalkylene group, a substituted or unsubstituted C2-C20 heterocycloalkylene group, a substituted or unsubstituted C6-C20 arylene group, a substituted or unsubstituted C1-C10 heteroarylene group, a carbonyl group, an ester group or a combination thereof.

[0045] R is hydrogen, deuterium, a halogen (-F, -Cl, -Br or -I), a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C1-C10 heteroalkyl group, a substituted or unsubstituted C2-C20 heteroalkenyl group, a substituted or unsubstituted C3-C20 heterocycloalkyl group or a substituted or unsubstituted C6-C20 heteroaryl group,

[0046] X 1 and X 2 are independently a halogen (-F, -Cl, -Br or -I), a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C10 heteroalkyl group, a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C3-C20 heterocycloalkyl group, a substituted or unsubstituted C6-C20 aryl group or a substituted or unsubstituted C6-C20 heteroaryl group, provided that at least one of X 1 and X 2 is selected from a halogen (-F, -Cl, -Br or -I),

[0047] k is an integer from 1 to 10, and

[0048] * is a bonding point where two or more structural units are bonded to each other.

[0049] In an embodiment, each of L 1 、L 2 and L 3 can be the same as or different from each other.

[0050] In an embodiment, L 1 、L 2 and L 3 can independently be a substituted or unsubstituted C1-C10 alkylene group, a substituted or unsubstituted C1-C10 heteroalkylene group, a substituted or unsubstituted C3-C20 cycloalkylene group, a substituted or unsubstituted C2-C20 heterocycloalkylene group, a carbonyl group, an ester group or a combination thereof.

[0051] In an embodiment, at least one of L 1 、L 2 and L 3 can be a substituted or unsubstituted C1-C10 alkylene group, a substituted or unsubstituted C1-C10 heteroalkylene group, a carbonyl group or a combination thereof. For example, L 1 、L 2 and L 3At least one of them may be a substituted or unsubstituted C1-C10 heteroalkylene group, or a substituted or unsubstituted C1-C10 alkylene group, or a combination of a substituted or unsubstituted C1-C10 heteroalkylene group and a carbonyl group.

[0052] In an embodiment, L 1 , L 2 and L 3 At least one of them may be a halogen-substituted C1-C10 heteroalkylene group or a halogen-substituted C1-C10 alkylene group.

[0053] In an embodiment, X 1 and X 2 Each of them may be the same as or different from each other. When X 1 and X 2 are the same, X 1 and X 2 may be the same functional group selected from halogen groups (for example, -F).

[0054] Meanwhile, in an embodiment, one of X 1 and X 2 may be selected from halogen groups, and the other may be a halogen-substituted C1-C10 alkyl group, a halogen-substituted C1-C10 heteroalkyl group, a halogen-substituted C3-C20 cycloalkyl group, or a halogen-substituted C3-C20 heterocycloalkyl group. Specifically, when X 1 is a halogen group, X 2 may be a halogen-substituted C1-C10 alkyl group or a halogen-substituted C1-C10 heteroalkyl group. In the halogen-substituted C1-C10 alkyl group or the halogen-substituted C1-C10 heteroalkyl group, at least one of the hydrogen atoms bonded to the terminal portion may be substituted by a halogen group.

[0055] Specifically, the structural unit represented by Chemical Formula 1 may include the structural unit represented by Chemical Formula 2.

[0056] [Chemical Formula 2]

[0057]

[0058] In Chemical Formula 2,

[0059] L 11 and L 13 are independently a substituted or unsubstituted C1-C10 alkylene group, a substituted or unsubstituted C1-C10 heteroalkylene group, a substituted or unsubstituted C3-C20 cycloalkylene group, a substituted or unsubstituted C2-C20 heterocycloalkylene group, a carbonyl group, an ester group, or a combination thereof,

[0060] L 12is a substituted or unsubstituted C1-C10 alkylene, substituted or unsubstituted C1-C10 heteroalkylene, substituted or unsubstituted C3-C20 cycloalkylene or substituted or unsubstituted C2-C20 hetero cycloalkylene,

[0061] R 1 is hydrogen, deuterium, halogen (-F, -Cl, -Br, -I), substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C1-C10 heteroalkyl, substituted or unsubstituted C3-C20 heterocycloalkyl or substituted or unsubstituted C6-C20 heteroaryl,

[0062] X 11 and X 12 are independently halogen (-F, -Cl, -Br or -I), substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 heteroalkyl, substituted or unsubstituted C3-C20 cycloalkyl or substituted or unsubstituted C3-C20 heterocycloalkyl, provided that at least one of X 11 and X 12 is selected from halogen (-F, -Cl, -Br, -I),

[0063] k1 is an integer from 1 to 10,

[0064] n is an integer from 2 to 100, and

[0065] * is a bonding point.

[0066] Meanwhile, the polymer containing the structural unit may contain one or more of the structural units represented by Chemical Formula 3 to Chemical Formula 6.

[0067] [Chemical Formula 3]

[0068]

[0069] [Chemical Formula 4]

[0070]

[0071] [Chemical Formula 5]

[0072]

[0073] [Chemical Formula 6]

[0074]

[0075] In Chemical Formula 3 to Chemical Formula 6, * is a bonding point.

[0076] For example, when the polymer constituting the resist underlayer composition contains an isocyanurate compound having a halogen introduced into the side chain, specifically, an isocyanurate compound having a chemical bond in the main chain and / or side chain in the form of “-O-CH 2 -C(-halogen)-”, the isocyanurate compound can improve the light absorption efficiency of the exposure light source during the exposure of the resist underlayer composition.

[0077] Therefore, when forming a resist underlayer composition to form a resist underlayer, secondary electrons can be additionally generated during the light treatment. The additionally generated secondary electrons can affect the photoresist during the light treatment, and thereby maximize the acid generation efficiency, and thus, increase the light treatment rate of the photoresist and enhance the sensitivity of the photoresist.

[0078] In addition, even when polymerized in a relatively high molecular weight state, the polymer containing the isocyanurate compound has excellent solubility in organic solvents such as propylene glycol methyl ether (PGME). Therefore, due to the excellent solubility in organic solvents, the resist underlayer composition can exhibit excellent coating properties and peel resistance.

[0079] Furthermore, since the polymer is stable with respect to organic solvents and heat, when the resist underlayer composition containing the polymer is formed into a resist underlayer, during the process of forming a photoresist pattern or generating by-products due to the generation of chemical substances, etc., the resist underlayer can minimize its peeling by solvent or heat, and in addition, its thickness loss due to the upper photoresist solvent can be minimized.

[0080] On the other hand, in the chemical bond in the form of “-O-CH 2 -C(-halogen)-” contained in the polymer, when the halogen group is a fluorine group (-F), more excellent film density and secondary ion generation of the resist underlayer can be obtained compared to when using other halogen groups.

[0081] In addition, since the etching rate of the resist underlayer can be increased by the halogen contained in the chemical bond in the form of “-O-CH 2 -C(-halogen)-” during the dry etching process, the resist underlayer can exhibit an improved pattern form.

[0082] In addition, since the polymer has excellent solubility and can thus form an underlayer resist having excellent coating uniformity and strong peel resistance, when the polymer is used as a material for the underlayer resist, a uniform thin film can be formed not only without reducing the thickness distribution or forming pinholes and voids during the baking process, but also excellent gap filling and planarization characteristics can be provided when there is a step difference in the underlying substrate (or film) or when a pattern is formed.

[0083] The underlayer resist composition according to one embodiment can achieve excellent coating uniformity and stability as well as a high refractive index, and also achieve a fast etching rate, and thus, an EUV (extreme ultraviolet) lithography process can be applied thereto. The EUV lithography process is a lithography technique that uses light having a wavelength of about 10 nm to about 20 nm (e.g., an extremely short wavelength, e.g., about 13.5 nm) to form an ultra-fine pattern having a width of less than or equal to about 20 nm.

[0084] Meanwhile, the polymer may have a weight average molecular weight (Mw) of about 1,000 g / mol to about 100,000 g / mol. More specifically, the polymer may have a weight average molecular weight of about 1,000 g / mol to about 50,000 g / mol or about 1,000 g / mol to about 30,000 g / mol. When the weight average molecular weight is within the above range, the carbon content and solubility in the solvent of the underlayer resist composition containing the polymer can be adjusted and thus optimized.

[0085] As long as the solvent has sufficient solubility or dispersibility in the polymer, the solvent is not particularly limited and may be at least one of the following: propylene glycol, propylene glycol diacetate, methoxypropylene glycol, diethylene glycol, diethylene glycol butyl ether, tri(ethylene glycol) monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, ethyl lactate, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-methylpyrrolidinone, acetylacetone, and ethyl 3-ethoxypropionate.

[0086] Based on the total amount of the underlayer resist composition, the polymer may be included in an amount of about 0.1 wt% to about 50 wt%, about 0.1 wt% to about 30 wt%, or about 0.1 wt% to about 15 wt%. Within the above range, the thickness, surface roughness, and degree of planarization of the underlayer resist can be adjusted.

[0087] In addition, in addition to the polymer described above, the underlayer resist composition may further include at least one other polymer such as an acrylic resin, an epoxy resin, a novolak resin, a glycoluril resin, and a melamine resin, but is not limited thereto.

[0088] The resist underlayer composition may further contain additives such as surfactants, thermal acid generators, plasticizers, or combinations thereof.

[0089] The surfactant may be, for example, alkylbenzenesulfonate, alkylpyridinium salt, polyethylene glycol, quaternary ammonium salt, or the like, but is not limited thereto.

[0090] The thermal acid generator may be an acidic compound such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonate, salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, hydroxybenzoic acid, naphthalenecarboxylic acid, and / or 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, and other organic sulfonic acid alkyl esters may be used, but are not limited thereto.

[0091] Based on 100 parts by weight of the resist underlayer composition, the additive may be included in an amount of about 0.001 part by weight to about 40 parts by weight. Within the above range, the solubility can be improved without changing the optical properties of the resist underlayer composition.

[0092] According to another embodiment, a resist underlayer prepared using the foregoing resist underlayer composition is provided. The resist underlayer can be formed by coating the foregoing resist underlayer composition on, for example, a substrate and then curing it via a heat treatment process. The resist underlayer may be, for example, an antireflection coating.

[0093] Hereinafter, reference Figures 1 to 5 describes a method of forming a pattern using the foregoing resist underlayer composition.

[0094] Figures 1 to 5 is a cross-sectional view showing a method of forming a pattern using the resist underlayer composition according to the present invention.

[0095] Reference Figure 1 , an etching target is prepared. The etching target may be a thin film 102 formed on a semiconductor substrate 100. Hereinafter, the etching target is limited to the thin film 102. The entire surface of the thin film 102 is washed to remove residual impurities and the like thereon. The thin film 102 may be, for example, a silicon nitride layer, a polysilicon layer, or a silicon oxide layer.

[0096] Subsequently, the resist underlayer composition containing a polymer having moieties represented by Chemical Formula 1 and Chemical Formula 2 and a solvent is coated on the surface of the cleaned thin film 102 by applying a spin coating method.

[0097] Next, the coated composition is dried and baked to form a resist underlayer 104 on the thin film 102. The baking can be carried out at about 100°C to about 500°C (for example, about 100°C to about 300°C). Specifically, the resist underlayer composition is described in detail above and will therefore be omitted.

[0098] ReferenceFigure 2 , a photoresist layer 106 is formed by coating a photoresist on the underlying resist layer 104.

[0099] Examples of the photoresist may include a positive photoresist containing a naphthoquinone diazide compound and a novolak resin, a chemically amplified positive photoresist containing an acid generator capable of dissociating an acid upon exposure, a compound that decomposes in the presence of an acid and has increased solubility in an alkaline aqueous solution, and a chemically amplified positive photoresist containing an alkali-soluble resin and a resin capable of applying to increase the solubility in an alkaline aqueous solution, etc.

[0100] Next, the substrate 100 having the photoresist layer 106 is prebaked. The prebaking can be carried out at about 90 °C to about 120 °C.

[0101] Reference Figure 3 , the photoresist layer 106 can be selectively exposed.

[0102] The exposure of the photoresist layer 106 can be carried out, for example, by placing an exposure mask having a predetermined pattern on the mask stage of an exposure apparatus and aligning the exposure mask 110 over the photoresist layer 106. Subsequently, by irradiating light onto the exposure mask 110, a predetermined region of the photoresist layer 106 formed on the substrate 100 selectively reacts with the light passing through the exposure mask.

[0103] For example, the light used during exposure may include short-wavelength light, such as actinic radiation i-line having a wavelength of 365 nm, KrF excimer laser having a wavelength of 248 nm, and ArF excimer laser having a wavelength of 193 nm. Additionally, EUV (extreme ultraviolet) having a wavelength of 13.5 nm corresponding to extreme ultraviolet light can be used.

[0104] Compared with the unexposed region 106b of the photoresist layer, the exposed region 106a of the photoresist layer has relatively hydrophilicity. Therefore, the exposed region 106a and the unexposed region 106b of the photoresist layer may have different solubilities from each other.

[0105] Subsequently, the substrate 100 is postbaked. The postbaking can be carried out at about 90 °C to about 150 °C. The exposed region of the photoresist layer becomes easily soluble in a predetermined solvent due to the postbaking.

[0106] Reference Figure 4 , the exposed region 106a of the photoresist layer is dissolved and removed by a developing solution to form a photoresist pattern 108. Specifically, the exposed region 106a of the photoresist layer is dissolved and removed by using a developing solution (such as tetra-methyl ammonium hydroxide (TMAH), etc.) to complete the photoresist pattern 108.

[0107] Subsequently, the photoresist pattern 108 is used as an etching mask to etch the underlying resist. Through etching, an organic layer pattern 112 is formed. The etching can be, for example, dry etching using an etching gas, and the etching gas can be, for example, CHF 3 , CF 4 , Cl 2 , O 2 and a mixed gas thereof. As described above, since the underlying resist formed from the underlying resist composition according to the embodiment has a fast etching rate, a smooth etching process can be performed in a short time.

[0108] Reference Figure 5 , the photoresist pattern 108 is applied as an etching mask to etch the exposed thin film 102. Thus, the thin film is formed into a thin film pattern 114. In the previously performed exposure process, the thin film pattern 114 formed by the exposure process using a short-wavelength light source such as, for example, actinic radiation i-line (wavelength of 365 nm), KrF excimer laser (wavelength of 248 nm), and ArF excimer laser (wavelength of 193 nm) can have a width of several tens of nanometers to several hundreds of nanometers, and the thin film pattern 114 formed by the exposure process using an EUV light source can have a width of less than or equal to about 20 nm.

[0109] Hereinafter, the present disclosure will be described in more detail via examples regarding the synthesis of a polymer and the preparation of an underlying resist composition containing the same. However, the present disclosure is not technically limited by the following example embodiments.

[0110] Synthesis Examples

[0111] Synthesis Example 1

[0112] 5.0 of 1-[(hydroxyethyl]-3,5-bis[3-[(2-hydroxyethyl)thio]propyl]-1,3,5-triazine-2,4,6-trione, 5.0 g of 2-acrylic acid, 1,1'-(2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediyl) ester, 0.22 g of AIBN, and 16 g of N,N-dimethylformamide (DMF) were placed in a 100-ml round flask equipped with a condenser, and then heated while stirring with a magnetic bar to perform a polymerization reaction at 80°C. After the reaction proceeded for 10 hours, the resulting product was cooled to room temperature (23°C) and purified three times using toluene and hexane to obtain a polymer containing a structural unit represented by Chemical Formula 3 (molecular weight (Mw) = 4,000 g / mol).

[0113] Synthesis Example 2

[0114] 5.0 g of 1,3 - diallyl - 5 - (2 - hydroxyethyl) - 1,3,5 - triazinan - 2,4,6 - trione, 5.0 g of 1,1' - (2,2,3,3 - tetrafluoro - 1,4 - butanediyl) diacrylate, 0.22 g of AIBN, and 16 g of N,N - dimethylformamide (DMF) were placed in a 100 - mL round - bottom flask equipped with a condenser, and then heated while stirring with a magnetic stirrer to carry out a polymerization reaction at 80°C. After the reaction proceeded for 10 hours, the resulting product was cooled to room temperature (23°C), and purified three times using toluene and hexane to obtain a polymer containing a structural unit represented by Chemical Formula 4 (molecular weight (Mw) = 3,800 g / mol).

[0115] Synthesis Example 3

[0116] 5.0 g of 1,3 - diallyl - 5 - (2 - hydroxyethyl) - 1,3,5 - triazinan - 2,4,6 - trione, 5.0 g of 1,1' - (2,2,3,3,4,4 - hexafluoro - 1,5 - pentanediyl) diacrylate, 0.22 g of AIBN, and 16 g of N,N - dimethylformamide (DMF) were placed in a 100 - mL round - bottom flask equipped with a condenser, and then heated while stirring with a magnetic stirrer to carry out a polymerization reaction at 80°C. After the reaction proceeded for 10 hours, the resulting product was cooled to room temperature (23°C), and purified three times using toluene and hexane to obtain a polymer containing a structural unit represented by Chemical Formula 5 (molecular weight (Mw) = 4,100 g / mol).

[0117] Synthesis Example 4

[0118] 2 g of 1,3 - diallyl - 5 - (2 - hydroxyethyl) - 1,3,5 - triazinan - 2,4,6 - trione and 3.7 g of 1,6 - dihydroxy - 2,2,3,3,4,4,5,5 - octafluorohexane were dissolved in 50 g of propylene glycol monomethyl ether. Subsequently, 3.5 g of iodine was slowly added to the reaction solution at 0°C, and then heated to room temperature (23°C). When the reaction starting materials were completely consumed, the reaction solution was quenched with 10% aqueous Na 2 S 2 O 5 (500 mL) to obtain a polymer containing a structural unit represented by Chemical Formula 6 (molecular weight (Mw) = 5,300 g / mol).

[0119] Comparative Synthesis Example 1

[0120] 23.31 g of 1,3-bis(isocyanatomethyl)cyclohexane, 62.7 g of triethylol isocyanurate, 0.67 g of DABCO, and 201 g of tetrahydrofuran (THF) were placed in a 500 mL two-necked round flask, and a condenser was connected thereto. The obtained mixture was heated to 75 °C and reacted for 5 hours, and the corresponding reaction solution was cooled to room temperature (23 °C). Subsequently, the reaction solution was transferred to a 1 L wide-mouth bottle, washed three times with hexane, and then washed with pure water. The obtained resin in a jelly state was completely dissolved in 80 g of THF, and then slowly added dropwise to 800 g of toluene with stirring. After pouring out the solvent, the residual solvent was removed using a vacuum pump to obtain a polymer containing a structural unit represented by Chemical Formula 7 (Mw = 5,200 g / mol).

[0121] [Chemical Formula 7]

[0122]

[0123] In Chemical Formula 7, * is a bonding point.

[0124] Comparative Synthesis Example 2

[0125] 9.3 g of tris(2-hydroxyethyl) isocyanurate, 10.0 g of dimethyl 3,3'-(5-allyl-isocyanurate-1,3-diyl)dipropionate, 0.2 g of p-toluenesulfonic acid, and 45 g of anisole were placed in a 100 mL round flask equipped with a condenser, and then the polymerization reaction was initiated while heating with a magnetic stirrer. After 1 hour, when the internal temperature reached 150 °C or higher, 20 g of reaction by-products and solvents were removed by reduced pressure to create an environment that increased the internal solids and promoted the reaction. After the reaction proceeded for 15 minutes, the resulting product was cooled to room temperature (23 °C), and purified 5 times using isopropyl alcohol and hexane to remove small molecules and the catalyst, and finally a polymer containing a structural unit represented by Chemical Formula 8 (molecular weight (Mw) = 8,000 g / mol) was obtained.

[0126] [Chemical Formula 8]

[0127]

[0128] In Chemical Formula 8, * is a bonding point.

[0129] Preparation of the resist underlayer composition

[0130] Examples 1 to 5 and Comparative Examples 1 to 2

[0131] Dissolve 1 g of each polymer according to Synthesis Examples 1 to 5 and Comparative Synthesis Examples 1 to 2, 0.15 g of PD1174 (hardener, TCI), and 0.01 g of pyridinium para-toluenesulfonate (PPTS) in 98.84 g of a mixed solvent of propylene glycol monomethyl ether and ethyl lactate (volume ratio = 1:1), and then stir for 6 hours to prepare resist bottom layer compositions respectively.

[0132] Coating uniformity evaluation

[0133] Take 2 mL of each resist bottom layer composition according to Examples 1 to 5 and Comparative Examples 1 to 2, and then apply it onto an 8-inch wafer, and spin-coat for 20 seconds at 1,500 revolutions per minute using an automatic track (ACT-8, TEL (Tokyo Electron Ltd.)), and then cure at 210 °C for 90 seconds to form a 300-nm-thick resist bottom layer respectively. Subsequently, measure the thickness at 51 points on the horizontal axis to compare the coating uniformity, and the results are shown in Table 1.

[0134] In Table 1, the smaller the coating uniformity (%), the more excellent the coating uniformity.

[0135] (Table 1)

[0136] Coating uniformity (%) Example 1 1.1 Example 2 1.2 Example 3 1.1 Example 4 1.0 Comparative Example 1 1.5 Comparative Example 2 1.8

[0137] Referring to Table 1, compared with the films formed from the resist bottom layer compositions according to Comparative Examples 1 to 2, the films formed from the resist bottom layer compositions according to Examples 1 to 4 exhibit excellent coating uniformity.

[0138] Film density evaluation

[0139] Spin-coat the resist bottom layer compositions according to Examples 1 to 4 and Comparative Examples 1 to 2 on silicon substrates respectively, and then heat-treat on a hot plate at 205 °C for 1 minute to form a resist bottom layer with a thickness of about 30 nm.

[0140] Subsequently, measure the density of the resist bottom layer, and the results are shown in Table 2. The density of the resist bottom layer is measured by using an X-ray diffractometer (model: X'Pert PRO MPD, Malvern Panalytical Ltd.).

[0141] (Table 2)

[0142] Film density (g / cm³) Example 1 1.47 Example 2 1.45 Example 3 1.44 Example 4 1.43 Comparative Example 1 1.33 Comparative Example 2 1.34

[0143] Referring to Table 2, the films formed from the resist underlayer compositions according to Examples 1 to 4 exhibit a high density as compared with the films formed from the resist underlayer compositions according to Comparative Examples 1 to 2. In other words, when using the resist underlayer compositions according to the examples, the examples demonstrate that films having a denser structure than the comparative examples are formed.

[0144] Evaluation of Exposure Characteristics

[0145] The compositions of Examples 1 to 4 and Comparative Examples 1 to 2 were each spin-coated, and then heat-treated on a hot plate at 205 °C for 1 minute to form a resist underlayer having a thickness of about 10 nm.

[0146] Subsequently, a photoresist solution was spin-coated on the resist underlayer, and then heat-treated on a hot plate at 110 °C for 1 minute to form a photoresist layer. The photoresist layer was exposed to an acceleration voltage of 100 keV using an e-beam exposure apparatus (Elionix, Inc.), and then heat-treated at 110 °C for 60 seconds. Subsequently, the photoresist layer was developed with a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) at 23 °C, and then rinsed with pure water for 15 seconds to form a photoresist pattern of line and space (L / S).

[0147] Next, the optimum exposure dose of the photoresist pattern was evaluated, and the results are shown in Table 3.

[0148] Herein, the optimum exposure dose is the exposure dose for resolving 40 nm line and space at 1:1 (microcoulomb / cm², Eop), and in the optimum exposure dose, the minimum line width of the line and space is referred to as the resolution. The resolution was evaluated by measuring the ultimate resolution (nm) with a scanning electron microscope (SEM) S-9260 (Hitachi Ltd.).

[0149] (Table 3)

[0150]

[0151] Referring to Table 3, the resist underlayers formed from the compositions according to the examples exhibit an excellent optimum exposure dose of the photoresist pattern as compared with the resist underlayers formed from the compositions according to the comparative examples. In other words, as compared with the resist underlayer compositions according to the comparative examples, the resist underlayer compositions according to the examples demonstrate that photoresist patterns having more excellent sensitivity are formed.

[0152] In the foregoing, certain embodiments of the present invention have been described and illustrated. However, it will be apparent to those of ordinary skill in the art that the present invention is not limited to the embodiments as described, and various modifications and conversions can be made without departing from the spirit and scope of the present invention. Therefore, the modified or converted embodiments may not be understood separately from the technical concept and aspects of the present invention, and the modified embodiments are within the scope of the claims of the present invention.

Claims

1. A resist underlayer composition, comprising: a polymer containing one or more of the structural units represented by Chemical Formula 3 to Chemical Formula 6; and a solvent: [Chemical Formula 3] [Chemical Formula 4] [Chemical Formula 5] [Chemical Formula 6] wherein, in Chemical Formula 3 to Chemical Formula 6, * is a bonding point.

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

3. The resist underlayer composition according to claim 1, wherein, based on the total amount of the resist underlayer composition, the polymer is contained in an amount of 0.1 wt% to 50 wt%.

4. The resist underlayer composition according to claim 1, wherein the resist underlayer composition further comprises at least one polymer selected from acrylic resin, epoxy resin, novolak resin, glycoluril resin, and melamine resin.

5. The resist underlayer composition according to claim 1, further comprising additives such as a surfactant, a thermal acid generator, a plasticizer, or a combination thereof.

6. A method of forming a pattern, comprising: forming an etching target layer on a substrate, coating the resist underlayer composition according to any one of claims 1 to 5 on the etching target layer to form a resist underlayer, forming a photoresist pattern on the resist underlayer, and sequentially etching the resist underlayer and the etching target layer using the photoresist pattern as an etching mask.

7. The method of forming a pattern according to claim 6, wherein the formation of the photoresist pattern comprises: forming a photoresist layer on the resist underlayer, exposing the photoresist layer, and developing the photoresist layer.

8. The method of forming a pattern according to claim 6, wherein the formation of the resist underlayer further comprises a heat treatment performed at 100°C to 500°C after coating the resist underlayer composition.

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