WO2008075860A1

WO2008075860A1 - High etch resistant hardmask composition having antireflective properties, method for forming patterned material layer using the hardmask composition and semiconductor integrated circuit device produced using the method

Info

Publication number: WO2008075860A1
Application number: PCT/KR2007/006574
Authority: WO
Inventors: Chang Il Oh; Dong Seon Uh; Kyung Hee Hyung; Min Soo Kim; Jin Kuk Lee; Jong Seob Kim
Original assignee: Cheil Industries Inc.
Priority date: 2006-12-21
Filing date: 2007-12-17
Publication date: 2008-06-26
Also published as: KR20080057927A; TW200834236A; TWI380129B; KR100865684B1

Abstract

Provided is a hardmask composition having antireflective properties that is suitable for lithography. The hardmask composition provides excellent characteristics in terms of optical properties and mechanical properties. In addition, the composition can be readily applied by spin-on application techniques. Particularly, the composition is highly resistant to dry etching. Therefore, the composition can be used to provide a multilayer thin film that is patterned with high aspect ratio. Further provided is a method for forming a pattern using the composition.

Description

HIGH ETCH RESISTANT HARDMASK COMPOSITION HAVING ANTIREFLECTIVE PROPERTIES, METHOD FOR FORMING PATTERNED MATERIAL LAYER USING THE HARDMASK COMPOSITION AND SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE PRODUCED USING THE

METHOD Technical Field

[1] The present invention relates to a hardmask composition having antireflective properties that is suitable for lithography. More specifically, the present invention relates to a hardmask composition comprising an aromatic ring-containing polymer with a strong absorption in the short wavelength region (e.g., 157 nm, 193 nm and 248 nm).

[2]

Background Art

[3] There is a continuous demand to reduce the size of structural shapes in the microelectronics industry as well as other related industries, including manufacture of microscopic structures (for example, micromachines and magneto-resist heads). In the microelectronics industry, there exists a need to reduce the size of microelectronic devices so as to provide a number of circuits in a given chip size.

[4] Effective lithographic techniques are essential to achieve a reduction in the size of structural shapes. Lithography affects the manufacture of microscopic structures from the viewpoint of directly imaging patterns on particular substrates and producing masks typically used for such imaging.

[5] A typical lithographic process involves patternwise exposure of a radiation-sensitive resist to imaging radiation to form a patterned resist layer. Thereafter, an image is developed by bringing the exposed resist layer into contact with a certain substance (typically, an aqueous alkaline developing solution). Then, the substance present in openings of the patterned resist layer is etched to transfer a pattern to an underlying material. After completion of the transfer, remaining portions of the resist layer are removed.

[6]

Disclosure of Invention Technical Problem [7] For better resolution in most lithographic processes, an antireflective coating (ARC) is used to minimize the reflectivity between an imaging layer, e.g., a radiation-sensitive resist material layer, and an underlying layer. However, since many portions of the imaging layer are removed during etching of ARC after patterning, patterning may be further required in the subsequent etching step.

[8] That is, in some lithographic imaging processes, the used resist does not provide sufficient resistance to the subsequent etching step to an extent sufficient to effectively transfer the desired pattern to a layer underlying the resist. In actual applications (for example, in the case where an extremely thin resist layer is required, an underlying material to be etched is thick, a large etching depth is needed, and/or the use of a particular etchant is required depending on the type of an underlying material), a so- called 'hardmask layer' is used as an intermediate layer between the patterned resist layer and the underlying material that can be patterned by transfer from the patterned resist. The hardmask layer must be able to accommodate the pattern from the patterned resist layer and withstand etching required to transfer the pattern to the underlying material.

[9] Although a number of hardmask materials are known, there is a continuous need for an improved hardmask composition. Since conventional hardmask materials are difficult to apply to substrates, the use of chemical and physical vapor deposition, special solvents, and/or high-temperature baking may be required. However, these methods not only necessitate the use of expensive equipment or the introduction of advanced techniques but also involve complicated processes, thus incurring considerable production costs of devices. Thus, a hardmask composition is preferred that can be applied by spin-coating techniques. Another hardmask composition is preferred that can be selectively etched using an overlying photoresist layer as a mask in an easy manner and is resistant to etching necessary to pattern an underlying metal or silicon compound layer using a hardmask layer as a hardmask. Another hardmask composition is preferred that provides superior storage properties and avoids negative interactions ( e.g., acid pollution from a hardmask) with an imaging resist layer. Another hardmask composition is preferred that has particular optical properties against imaging radiation at shorter wavelengths (e.g., 157 nm, 193 nm, and 248 nm).

[10] Numerous technical difficulties remain in patterning relatively thick underlying layers by dry etching. For example, an overlying hardmask layer formed by spin coating may have an isotropic (e.g., bowed) etch profile during dry etching, which makes it difficult to allow the hardmask layer to function as a hardmask of a relatively thick underlying layer. Attempts have been made to prevent the occurrence of isotropic etch profiles, for example, by varying dry etching conditions. However, device makers suffer from limitations in the operation of mass-production facilities. [H] Under such circumstances, the present inventors have endeavored to prepare a high- density networking polymer with high carbon content in an amorphous structure that can be used to form a hardmask having an anisotropic profile.

[12]

Technical Solution [13] The present invention has been made in view of the problems of the prior art, and it is one object of the present invention to provide a novel hardmask composition suitable for use in a lithographic process that exhibits high etch selectivity, is sufficiently resistant to multiple etching, and minimizes the reflectivity between a resist and an underlying layer.

[14] It is another object of the present invention to provide a method for patterning an underlying material layer on a substrate using the hardmask composition. [15] In accordance with one aspect of the present invention, there is provided an antire- flective hardmask composition comprising

[16] (a) an aromatic ring-containing polymer represented by any one of Formulae 1 to 3:

[18] wherein R₁ is selected from -CH₂-

CH₂-

-∞oo™>-

-CH-

and

-CH-

, R₂ and R₃ are independently selected from hydrogen, hydroxyl, Ci-Ci₀ alkyl, C₆-Ci₀ aryl, allyl and halogen, and 1 < n < 750;

[19]

[20] wherein R₁ is selected from -CH₂-

-^H=^C-00-^CH-

-CH-

and

-CH-

, R₄ is selected from hydrogen, hydroxyl, Ci-Ci₀ alkyl, C₆-Ci₀ aryl, allyl and halogen, and 1 < n < 750; and

[22] wherein Ri is selected from -CH₂-

-H₂C-^-CH₂-

-CH-

and

-CH- , and 1 < n < 750,

[23] (b) an initiator, and

[24] (c) an organic solvent.

[25] The hardmask composition of the present invention may further comprise (d) a crosslinking component and (e) an acid catalyst.

[26] In this case, the hardmask composition of the present invention may comprise 1 to

20% by weight of the aromatic ring-containing polymer (a), 0.001 to 5% by weight of the initiator (b), 75 to 98.8% by weight of the organic solvent (c), 0.1 to 5% by weight of the crosslinking component (d), and 0.001 to 0.05% by weight of the acid catalyst (e).

[27] The hardmask composition of the present invention may further comprise an imidazole compound as a base catalyst (d).

[28] In this case, the hardmask composition of the present invention may comprise 1 to

20% by weight of the aromatic ring-containing polymer (a), 0.001 to 5% by weight of the initiator (b), 75 to 98.8% by weight of the organic solvent (c), and 0.001 to 5% by weight of the base catalyst (d).

[29] The aromatic ring-containing polymer preferably has a weight average molecular weight of 1,000 to 30,000.

[30] The hardmask composition of the present invention may further comprise a surfactant.

[31] The initiator may be selected from the group consisting of peroxides, persulfates, azo compounds, and mixtures thereof.

[32] The crosslinking component may be selected from the group consisting of etherified amino resins, alkoxyalkyl melamine resins, alkyl urea resins, glycoluril derivatives, 2,6-bis(hydroxymethyl)-/?-cresol, bisepoxy compounds, and mixtures thereof.

[33] The acid catalyst may be selected from the group consisting of /?-toluenesulfonic acid monohydrate, pyridinium /?-toluenesurfonate, 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, alkyl esters of organic sulfonic acids, and mixtures thereof.

[34] In accordance with another aspect of the present invention, there is provided a method for forming a patterned material layer on a substrate using the hardmask composition.

[35] Specifically, the method of the present invention comprises the steps of (a) providing a material layer on a substrate, (b) forming an antireflective hardmask layer using the hardmask composition on the material layer, (c) forming a radiation-sensitive imaging layer on the antireflective hardmask layer, (d) patternwise exposing the radiation- sensitive imaging layer to radiation to form a pattern of radiation-exposed regions in the imaging layer, (e) selectively removing portions of the radiation-sensitive imaging layer and the antireflective hardmask layer to expose portions of the material layer, and (f) etching the exposed portions of the material layer to pattern the material layer.

[36] The method of the present invention may further comprise the step of forming a hardmask layer using a silicon-containing composition prior to step (c). The method of the present invention may further comprise the step of forming a bottom antireflective coating (BARC) on the silicon-containing hardmask layer prior to step (c).

[37] In accordance with yet another aspect of the present invention, there is provided a semiconductor integrated circuit device produced using the method. [38]

Best Mode for Carrying Out the Invention

[39] Exemplary embodiments of the present invention will now be described in greater detail. [40] The present invention provides an antireflective hardmask composition comprising (a) an aromatic ring-containing polymer with a strong absorption in the short wavelength region (e.g., 193 nm and 248 nm), (b) an initiator and (c) an organic solvent.

[41] The aromatic ring-containing polymer (a) is represented by any one of Formulae 1 to 3:

[43] wherein R₁ is selected from -CH₂-

-^«'^c-00-^CH-

-CH-

and

-CH- , R₂ and R₃ are independently selected from hydrogen, hydroxyl, Ci-Ci₀ alkyl, C₆-Ci₀ aryl, allyl and halogen, and 1 < n < 750;

[45] wherein Ri is selected from -CH₂-

-H₂C ^^- -CC H₂-

-^H-^C→O-O""-

— CH-

and

-CH-

[47] wherein Ri is selected from -CH₂-

— H₂C — {^ H — CH₂-

-CH-

and

, and 1 < n < 750.

[48] It is preferred that the aromatic ring-containing polymer contains aromatic rings in the skeleton of the polymer. It is preferred that the aromatic ring-containing polymer has a number of reactive sites capable of reacting with a crosslinking component and distributed along the backbone chain of the polymer. In addition, the hardmask composition of the present invention must have solution- and film-forming characteristics, which assist in the formation of a layer by a conventional spin-coating technique.

[49] Specifically, the hardmask composition of the present invention satisfies all the above requirements. A blend of the polymers of Formulae 1, 2 and 3 and a copolymer of the units (i.e. monomers) constituting the polymers may be also used in the present invention.

[50] The aromatic ring-containing polymer preferably has a weight average molecular weight of 1,000 to 30,000.

[51] The aromatic ring-containing polymer (a) is preferably used in an amount of 1 to 30 parts by weight, based on 100 parts by weight of the organic solvent (c). When the amount of the aromatic ring-containing polymer used is less than 1 part by weight or exceeds 30 parts by weight, a desired coating thickness is not attained (i.e. it is difficult to accurately regulate a coating thickness).

[52] There is no particular limitation on the type of the initiator (b) so long as the initiator can thermally crosslink vinyl groups of the aromatic ring-containing polymer (a) upon baking immediately after coating. Examples of suitable initiators for use in the present invention include peroxides, persulfates, and azo compounds. These initiators may be used alone or as a mixture of two or more thereof.

[53] There is no particular limitation on the kind of the organic solvent (c) so long as the aromatic ring-containing polymer (a) can be sufficiently dissolved in the organic solvent (c). As suitable organic solvents, there may be exemplified, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone and ethyl lactate (EL).

[54] The initiator is activated upon heating to crosslink the vinyl groups of the polymer.

That is, the initiator is decomposed by heating to form reactive radicals, which attack the monomers having vinyl groups to crosslink the vinyl groups.

[55] The antireflective hardmask composition of the present invention may further comprise (d) a crosslinking component and (e) an acid catalyst.

[56] The crosslinking component (c) used in the hardmask composition of the present invention is preferably one capable of being crosslinked with the hydroxyl groups of the polymer by the catalytic activity of a generated acid. It is preferred that the acid catalyst (e) be thermally activated.

[57] The thermally activated acid catalyst catalyzes the crosslinking between the crosslinking component and the hydroxyl groups of the polymer. That is, the thermally activated acid catalyst promotes the crosslinking function of the crosslinking component and serves to crosslink the hydroxyl groups within the polymer and between the adjacent polymer molecules.

[58] Any crosslinking component capable of reacting with the hydroxyl groups of the aromatic ring-containing polymer in a manner that can be catalyzed by a generated acid may be used without any particular limitation in the present invention. Specific examples of suitable crosslinking components for use in the hardmask composition of the present invention include: etherified amino resins, alkoxyalkyl melamine resins ( e.g., N-methoxymethyl-melamine resins and N-butoxymethyl- melamine resins), alkyl urea resins (e.g., Cymel U-65 Resin and UFR 80 Resin), glycoluril derivatives (e.g., Powderlink 1174 of Formula 4), 2,6-bis(hydroxymethyl)-/?-cresol, and bisepoxy compounds.

}

[60] As the acid catalyst (e), an organic acid, e.g., /?-toluenesulfonic acid monohydrate, can be used. For improved storage stability, a thermal acid generator (TAG) compound can be used as the acid catalyst (e). TAG is a compound that generates an acid upon thermal treatment. Examples of preferred TAGs include pyridinium/? - toluenesulfonate, 2,4,4,6-tetrabromocyclohexadienol, benzoin tosylate, 2-nitrobenzyl tosylate, alkyl esters of organic sulfonic acids, and mixtures thereof.

[61] Other radiation- sensitive acid catalysts known in the field of resists can also be used so long as they are compatible with the other components of the antireflective composition.

[62] In the hardmask composition of the present invention, the aromatic ring-containing polymer (a) with a strong absorption in the short wavelength region is preferably present in an amount of 1 to 20% by weight and more preferably 3 to 10% by weight, the initiator (b) is preferably present in an amount of 0.001 to 5% by weight and more preferably 0.01 to 3% by weight, the organic solvent (c) is preferably present in an amount of 75 to 98.8% by weight, the crosslinking component (d) is preferably present in an amount of 0.1 to 5% by weight and more preferably 0.1 to 3% by weight, and the acid catalyst (e) is preferably present in an amount of 0.001 to 0.05% by weight and more preferably 0.001 to 0.03% by weight. [63] When the content of the aromatic ring-containing polymer is outside the range defined above, a desired coating thickness is not attained (i.e. it is difficult to accurately regulate a coating thickness).

[64] When the content of the initiator is less than 0.001% by weight, suitable crosslinking properties may be not exhibited. Meanwhile, when the content of the initiator is more than 5% by weight, a portion of the initiator may be unreacted, which causes deformation of a pattern profile and intermixing at the interface with a photoresist or an overlying second hardmask, and as a result, the optical properties of a coating film may be varied.

[65] When the content of the crosslinking component is less than 0.1% by weight, crosslinking properties may be not exhibited. Meanwhile, when the content of the crosslinking component is greater than 5% by weight, deformation of a pattern profile may be cause and redeposition contamination may occur due to the occurrence of volatile components upon baking.

[66] When the content of the acid catalyst is less than 0.001% by weight, crosslinking properties may be not exhibited. Meanwhile, when the content of the acid catalyst exceeds 0.05% by weight, the storage stability may be adversely affected due to increased acidity.

[67] When the content of the organic solvent is outside the range defined above, a desired coating thickness is not attained (i.e. it is difficult to accurately regulate a coating thickness).

[68] The hardmask composition of the present invention may further comprise an imidazole compound as a (d) base catalyst.

[69] The base catalyst is activated upon heating to crosslink the hydroxyl groups and the terminal methoxy groups within the polymer and between the adjacent polymer molecules. Examples of the base catalysts include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1 -benzyl-2-methylimidazole, 1 -benzyl-2-phenylimidazole and 2-phenylimidazole.

[70] The hardmask composition of the present invention may comprise 1 to 20% by weight of the aromatic ring-containing polymer (a), 0.001 to 5% by weight of the initiator (b), 75 to 98.8% by weight of the organic solvent (c), and 0.001 to 5% by weight of the base catalyst (d).

[71] When the content of the base catalyst is less than 0.001% by weight, crosslinking effects are insufficient, and as a result, intermixing with a material of an overlying layer may be induced, making it difficult to form a pattern image. Meanwhile, when the content of the base catalyst is more than 5% by weight, a portion of the initiator may be unreacted, causing the problem of poor storage stability.

[72] The hardmask composition of the present invention may further comprise a surfactant.

[73] The present invention also provides a method for patterning an underlying material layer on a substrate using the hardmask composition.

[74] Specifically, the method of the present invention comprises the steps of (a) providing a material layer on a substrate, (b) forming an antireflective hardmask layer using the hardmask composition on the material layer, (c) forming a radiation-sensitive imaging layer on the antireflective hardmask layer, (d) patternwise exposing the radiation- sensitive imaging layer to radiation to form a pattern of radiation-exposed regions in the imaging layer, (e) selectively removing portions of the radiation-sensitive imaging layer and the antireflective hardmask layer to expose portions of the material layer, and (f) etching the exposed portions of the material layer to pattern the material layer.

[75] The method may further comprise the step of forming a silicon-containing hardmask layer prior to step (c). The method may further comprise the step of forming a bottom antireflective coating (BARC) on the silicon-containing hardmask layer prior to step

(C).

[76] The method of the present invention can be carried out in accordance with the following procedure. First, a material, such as aluminum or silicon nitride (SiN), to be patterned is applied to a silicon substrate by a common technique. As the material to be patterned, an electrically conductive, semi-conductive, magnetic or insulating material can be used. Thereafter, the hardmask composition of the present invention is spin- coated to a thickness of 500 to 4,00OA and is then baked at 100-300⁰C for 10 seconds to 10 minutes to form a hardmask layer. A radiation-sensitive image layer is formed on the hardmask layer. Developing is conducted to expose portions where a pattern is to be formed by exposure through the imaging layer. Subsequently, the imaging layer and the antireflective layer are selectively removed to expose portions of the material layer, and then dry etching is performed using a gas, such as a mixed gas of CHF₃/CF₄. After formation of a patterned material layer, the remaining portions of the resist are removed using a common photoresist stripper. A semiconductor integrated circuit device can be provided by using the method of the present invention.

[77] Accordingly, the composition of the present invention and the lithographic structure formed using the composition of the present invention can be used in the fabrication and design of integrated circuit devices in accordance with general semiconductor manufacturing processes. For example, the composition of the present invention can be used in the formation of patterned material layer structures, such as metal wirings, holes for contacts and biases, insulating sections (e.g., damascene trenches (DTs)) and shallow trench isolation (STI)), and trenches for capacitor structures. It should be appreciated that the present invention is not restricted to any particular lithographic techniques and device structures. [78]

Mode for the Invention [79] Hereinafter, the present invention will be explained in more detail with reference to the following examples. However, these examples are given for the purpose of illustration only and are not intended to limit the scope of the invention.

[80] [81] EXAMPLES [82] [Synthesis Example 1] [83] (Synthesis of copolymer of 4,4'(9-fluorenylidene)divinylphenol and 1 ,4-bismethoxymethylbenzene)

[84] 116.35g (0.7 mol) of 1,4-bismethoxymethylbenzene, 3.08g (0.02 mol) of diethyl sulfate and 350g of propylene glycol monomethyl ether were completely dissolved with stirring in a 3 L four-neck flask equipped with a mechanical agitator and a condenser while maintaining the temperature of the reactor at 13O⁰C. 10 minutes after the dissolution, 445.58g (1.0 mol) of 4,4'(9-fluorenylidene)divinylphenol was added dropwise to the solution, and then the resulting mixture was allowed to react at the same temperature for 5 hours. To the reaction mixture was added 2.98g (0.02 mol) of triethanolamine as a neutralizing agent to quench the reaction. After completion of the reaction, the acid was removed from the reaction mixture using a mixture of water and methanol, and low-molecular weight compounds containing the oligomers and monomers were removed using methanol, yielding the polymer represented by Formula 5 (M_w = 11,000, polydispersity = 2.1, n = 20).

[86] [87] [Synthesis Example 2] [88] (Synthesis of copolymer of 5 -hydroxy acenaphthalene and 1 ,4-bismethoxymethylbenzene)

[89] The procedure of Synthesis Example 1 was repeated, except that 169.2Og (1 mol) of 5 -hydroxy acenaphthalene was used instead of 445.58g (1.0 mol) of 4,4'(9-fluorenylidene)divinylphenol to yield the polymer of Formula 6.

[90]

[91] The molecular weight and the polydispersity of the copolymer were measured by gel permeation chromatography (GPC) in tetrahydrofuran. As a result, the copolymer was found to have a molecular weight of 12,000 and a polydispersity of 2.3.

[92] [93] [Synthesis Example 3] [94] (Synthesis of copolymer of vinylphenol and 1,4-bismethoxymethylbenzene) [95] The procedure of Synthesis Example 1 was repeated, except that 120.15g (1 mol) of vinylphenol was used instead of 445.58g (1.0 mol) of 4,4'(9-fluorenylidene)divinylphenol to yield the polymer of Formula 7.

[97] The molecular weight and the polydispersity of the copolymer were measured by gel permeation chromatography (GPC) in tetrahydrofuran. As a result, the copolymer was found to have a molecular weight of 13,000 and a polydispersity of 2.2.

[98] [99] [Examples 1 to 3] [100] 0.8g of each of the polymers prepared in Synthesis Examples 1 to 3, 0.08g of 2,2'azobisisobutyronitrile (AIBN) as an initiator, 0.2g of the crosslinking agent (Powderlink 1174) of Formula 4, and 2 mg of pyridinium /^-toluene sulfonate were dissolved in 9g of propylene glycol monomethyl ether acetate (PGMEA), and filtered to prepare a sample solution.

[102] The sample solution was spin-coated on a silicon wafer, followed by baking at 200⁰C for 60 seconds to form a 4,000 Athick film.

[103] The refractive index (n) and extinction coefficient (k) of the films were measured using an ellipsometer (J. A. Woollam). The results are shown in Table 1.

[104] The results reveal that the films had a refractive index and an absorbance suitable for use as antireflective films at wavelengths of 193 nm (ArF) and 248 nm (KrF), with the proviso that the film formed in Example 3 had a very low extinction coefficient at 248 nm.

[105] [106] [Examples 4 to 6] [107] 0.8g of each of the polymers prepared in Synthesis Examples 1 to 3, 0.08g of 2,2'azobisisobutyronitrile (AIBN) as an initiator and 0.008g of l-benzyl-2-phenylimidazole as a base catalyst were dissolved in 9g of propylene glycol monomethyl ether acetate (PGMEA), and filtered to prepare a sample solution.

[108] The sample solution was spin-coated on a silicon wafer, followed by baking at 200⁰C for 60 seconds to form a 4,00OA thick film. [109] The refractive index (n) and extinction coefficient (k) of the films were measured using an ellipsometer (J. A. Woollam). The results are shown in Table 1. [HO] The results reveal that the films had a refractive index and an absorbance suitable for use as antireflective films at wavelengths of 193 nm (ArF) and 248 nm (KrF).

[111] [112] [Synthesis Example 4] [113] (Synthesis of copolymer of fluorenylidenediphenol and 1 ,4-bismethoxymethylbenzene)

[114] The procedure of Synthesis Example 1 was repeated, except that 393.50g (1 mol) of fluorenylidenediphenol was used instead of 445.58g (1.0 mol) of 4,4'(9-fluorenylidene)divinylphenol to yield the polymer of Formula 8.

[116] The molecular weight and the polydispersity of the copolymer were measured by gel permeation chromatography (GPC) in tetrahydrofuran. As a result, the copolymer was found to have a molecular weight of 14,000 and a polydispersity of 2.5.

[117] [118] [Comparative Example 1] [119] A film was formed in the same manner as in Examples 1 to 3, except that the polymer prepared in Synthesis Example 4 was used. The film was measured for re- fractive index (n) and extinction coefficient (k). The results are shown in Table 1.

[120] Table 1 [Table 1]

Optical properties C 193 run) Optical properties C248 nm)

Sainπle used in the formation of film Refractive Extinction Refractive Extinction index (n) coefficient (k) index (n) coefficient (k)

Example 1 1 49 0 68 1 91 0 21

Example 2 1 42 0 32 2 12 0 30

Example 3 1 45 0 75 1 82 0 05

Example 4 1 48 0 67 1 90 0 23

Example 5 1 42 0 31 2 11 0 31

Example 6 1 43 0 75 1 81 0 04

Comparative Example 1 1 44 0 70 1 97 0 27

[121] [122] [Examples 7 to 12] [123] Each of the sample solutions prepared in Examples 1 to 6 was spin-coated on a silicon wafer covered with silicon nitride and baked at 200⁰C for 60 seconds to form a 4,00OA thick film.

[124] A silicon antireflective coating (ARC) was formed on the film and baked at 24O⁰C for 60 seconds. Thereafter, an ArF photoresist (PR) was coated to a thickness of 1,70OA on the silicon ARC, baked at 11O⁰C for 60 seconds, exposed to light using an ArF exposure system (ASML, XT : 1400, NA 0.93), and developed with an aqueous solution of TMAH (2.38 wt%) to form a 63-nm line and space pattern. The patterns were observed using a field emission scanning electron microscope (FE-SEM). The patterns were measured for exposure latitude (EL) margin as a function of exposure energy and depth of focus (DoF) margin as a function of the distance from a light source. The results are recorded in Table 2.

[125] [126] [Comparative Example 2] [127] A pattern was formed in the same manner as in Examples 1 to 6, except that the sample solution prepared in Comparative Example 1 was used. The profile of the pattern was observed. The pattern was measured for exposure latitude (EL) and depth of focus (DoF). The results are shown in Table 2.

[128] As a result, there was no significant difference in pattern profile and margins between the patterns formed in Examples 1 to 6 and Comparative Example 2.

[129] Table 2 [Table 2]

Pattern properties EL margin (Δ mJ/exposure energy mJ) DoF margin (μm) Profile

Example 7 0.25 Cubic Example 8 0.25 Cubic Example 9 0.25 Cubic Example 10 0.25 Cubic Example 11 4 0.25 Cubic Example 12 4 0.25 Cubic

Comparative

0.25 Cubic

Example 2

[130] [131] [Examples 13 to 18] [132] Each of the silicon ARCs of the patterned specimens (Examples 7 to 12 and Comparative Example 2) was dry-etched using a mixed gas of CHF₃/CF₄ through a photoresist as a mask. The hardmask was dry-etched using a mixed gas of O₂/N₂ through the silicon ARC as a mask. Thereafter, the silicon nitride was dry-etched using a mixed gas of CHF₃/CF₄ through the hardmask as a mask. O₂ ashing and wet stripping were performed on the remaining portions of the hardmask and organic materials.

[133] Immediately after etching of the hardmask and the silicon nitride, the cross sections of the specimens were observed using an FE-SEM. The results are listed in Table 3. [134] The etched patterns all showed good profiles. The reason for good etching of the silicon nitride is believed to be because the hardmasks were highly resistant to the etching gas.

[135] [136] [Comparative Example 3] [137] The specimen formed in Comparative Example 2 was etched in accordance with the procedure described in Examples 7 to 12 to form a pattern. The pattern was observed and the results are shown in Table 3.

[138] The pattern showed an isotropic (bowed) etching profile after etching of the hardmask. The isotropic etching profile is believed to cause tapering of the pattern upon etching of the silicon nitride.

[139] Table 3 [Table 3]

Sample used in the Pattern shape Pattern shape formation of film after etching of hardmask after etching of silicon nitride

Example 13 Vertical (Anisotropic) Vertical (Anisotropic) Example 14 Vertical (Anisotropic) Vertical (Anisotropic) Example 15 Vertical (Anisotropic) Vertical (Anisotropic) Example 16 Vertical (Anisotropic) Vertical (Anisotropic) Example 17 Vertical (Anisotropic) Vertical (Anisotropic) Example 18 Vertical (Anisotropic) Vertical (Anisotropic) Comparative Example 3 Bowed Tapered

[140]

Industrial Applicability

[141] As apparent from the above description, the antireflective hardmask composition of the present invention can be used to form a film having a refractive index and an ab- sorbance suitable for use as an antireflective film in the deep UV (DUV) (e.g., ArF (193 nm) and KrF (248 nm)). Therefore, the antireflective hardmask composition of the present invention exhibits high etch selectivity for lithography. In addition, since the antireflective hardmask composition of the present invention is sufficiently resistant to multiple etching, it can be used to form a hardmask having a very good etch profile. Therefore, a good image can be transferred to an underlying layer. Furthermore, since the antireflective hardmask composition of the present invention can minimize the reflectivity between a resist and an underlying layer, it can be used to provide a lithographic structure that has better results in terms of pattern profile and margins.

Claims

[1] An antireflective hardmask composition comprising

(a) an aromatic ring-containing polymer represented by any one of Formulae 1 to

3:

wherein Ri is selected from -CH₂-

-^H=^c-0^O-^CHj-

-CH-

and

— CH-

, R₂ and R₃ are independently selected from hydrogen, hydroxyl, Ci-Ci₀ alkyl, C₆ Cio ^aryl_> allyl and halogen, and 1 < n < 750;

wherein Ri is selected from -CH₂-

and

-CH-

wherein R₁ is selected from -CH₂-

-^H=^C-O-C^^CH-

— CH-

and

-CH-

, and 1 < n < 750,

(b) an initiator, and

(c) an organic solvent.

[2] The hardmask composition according to claim 1, further comprising (d) a crosslinking component and (e) an acid catalyst.

[3] The hardmask composition according to claim 2, wherein the composition comprises 1 to 20% by weight of the aromatic ring-containing polymer (a), 0.001 to 5% by weight of the initiator (b), 75 to 98.8% by weight of the organic solvent

(c), 0.1 to 5% by weight of the crosslinking component (d), and 0.001 to 0.05% by weight of the acid catalyst (e).

[4] The hardmask composition according to claim 2, wherein the crosslinking component is selected from the group consisting of etherified amino resins, al- koxyalkyl melamine resins, alkyl urea resins, glycoluril derivatives, 2,6-bis(hydroxymethyl)-/?-cresol, bisepoxy compounds, and mixtures thereof.

[5] The hardmask composition according to claim 2, wherein the acid catalyst is selected from the group consisting of /?-toluenesulfonic acid monohydrate, pyridinium /?-toluenesulfonate, 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, alkyl esters of organic sulfonic acids, and mixtures thereof.

[6] The hardmask composition according to claim 1, further comprising an imidazole compound as a base catalyst (d).

[7] The hardmask composition according to claim 6, wherein the composition comprises 1 to 20% by weight of the aromatic ring-containing polymer (a), 0.001 to 5% by weight of the initiator (b), 75 to 98.8% by weight of the organic solvent (c), and 0.001 to 5% by weight of the base catalyst (d).

[8] The hardmask composition according to claim 1, wherein the aromatic ring- containing polymer has a weight average molecular weight of 1,000 to 30,000.

[9] The hardmask composition according to claim 1, further comprising a surfactant.

[10] The hardmask composition according to claim 1, wherein the initiator is selected from the group consisting of peroxides, persulfates, azo compounds, and mixtures thereof.

[11] A method for forming a patterned material layer on a substrate, the method comprising the steps of

(a) providing a material layer on a substrate,

(b) forming an antireflective hardmask layer using the hardmask composition according to any one of claims 1 to 10 on the material layer,

(c) forming a radiation-sensitive imaging layer on the antireflective hardmask layer,

(d) patternwise exposing the radiation-sensitive imaging layer to radiation to form a pattern of radiation-exposed regions in the imaging layer,

(e) selectively removing portions of the radiation- sensitive imaging layer and the antireflective hardmask layer to expose portions of the material layer, and

(f) etching the exposed portions of the material layer to pattern the material layer. [12] The method according to claim 11, further comprising the step of forming a hardmask layer using a silicon-containing composition prior to step (c). [13] The method according to claim 12, further comprising the step of forming a bottom antireflective coating (BARC) on the silicon-containing hardmask layer prior to step (c). [14] A semiconductor integrated circuit device produced using the method according to any one of claims 11 to 13.