KR102539872B1 - Composition for hard mask - Google Patents

Abstract

The present invention relates to a composition for a hard mask, and more particularly, by including a polymer including a repeating unit represented by a specific chemical formula and a solvent, to form a hard mask layer having excellent etching resistance, coatability, and chemical resistance. can

Description

Composition for hard mask {COMPOSITION FOR HARD MASK}

The present invention relates to a composition for a hard mask.

Recently, high-integration design due to miniaturization and complexity of electronic devices is accelerating the development of more advanced materials and related processes, and accordingly, lithography using existing photoresists also requires new patterning materials and techniques. It became.

In general, a photoresist layer is formed by applying a photoresist on an etch-target layer, a photoresist pattern is formed through an exposure and development process, and the etch-target layer is partially removed using the photoresist pattern as an etching mask. By doing so, a predetermined pattern can be formed.

An anti-refractive coating (ARC) layer may be formed between the etch target layer and the photoresist layer to suppress deterioration of resolution due to light reflection during the exposure process. In this case, etching is added to the ARC layer, and accordingly, the consumption or etching amount of the photoresist layer or photoresist pattern may be increased. In addition, when the thickness of the etch target layer increases or the etching amount required to form a desired pattern increases, sufficient etching resistance of the photoresist layer or photoresist pattern may not be secured.

Therefore, in the patterning process, an organic layer called a hard mask layer, which is a hard intermediate layer, may be formed in order to transfer the photoresist fine pattern to a substrate to a sufficient depth without collapse. Such a hard mask layer requires properties such as heat resistance and etch resistance to withstand multiple etching processes, and needs to be formed with a uniform thickness by a spin-on coating process.

Korean Patent Publication No. 10-2015-0031163 discloses an organic film composition used for forming a hard mask layer. However, it seems to be insufficient in terms of improvement of the etching resistance property.

Republic of Korea Patent Publication No. 10-2015-0031163

An object of the present invention is to provide a hard mask composition for forming a hard mask layer having excellent etching resistance, coating properties and chemical resistance.

The present invention provides a composition for a hard mask comprising a polymer represented by Formula 1 below and a solvent.

[Formula 1]

(In Formula 1, R ₁ is a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms, or a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms,

R ₂ is hydrogen, a hydroxyl group, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, or a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms;

R ₃ is a substituted or unsubstituted aryl group having 6 to 40 carbon atoms or a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms;

n is an integer from 1 to 100.)

The polymer included in the composition for a hard mask according to the present invention may include a structural unit including an indole derivative and a structural unit including a flexible aryl derivative. Accordingly, intermolecular interactions may be promoted through an oxidative coupling reaction based on a high carbon content, thereby improving packing characteristics, and as a result, etching resistance and heat resistance may be improved. In addition, since solubility is increased by including a flexible aryl group, coating properties such as flatness and gap-fill characteristics may also be improved. Accordingly, when the composition for a hard mask according to the present invention is used, a hard mask layer having improved etching resistance, heat resistance, and coating characteristics can be formed at the same time.

One embodiment of the present invention relates to a composition for a hard mask capable of forming a hard mask layer having improved etching resistance, heat resistance and coating characteristics by including a polymer including a repeating unit having a specific structure and a solvent,

When using a polymer prepared through a condensation reaction of a first unit including an indole derivative and a second unit including a flexible aryl derivative, etching resistance and heat resistance can be improved by including an indole derivative having a high carbon content. At the same time, the present invention was completed by experimentally confirming that the solubility was increased by including a flexible aryl group, so that the coating properties could also be improved despite the high carbon content.

Hereinafter, compositions for hard masks according to embodiments of the present invention will be described in detail. However, this is only an example, and the present invention is not limited thereto.

In the present invention, when there is an isomer of a compound, repeating unit or resin represented by a chemical formula, the compound, repeating unit or resin represented by the chemical formula means a representative chemical formula including the isomer.

In addition, in the present invention, the term "carbon content" means the ratio of the total mass number of carbon to the total mass number per molecule of the compound.

<Composition for hard mask>

A composition for a hard mask according to exemplary embodiments of the present invention includes a polymer and a solvent.

polymer

The polymer includes a repeating unit represented by Formula 1 below:

[Formula 1]

(In Formula 1, R ₁ is a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms, or a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms,

R ₂ is hydrogen, a hydroxyl group, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, or a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms;

R ₃ is a substituted or unsubstituted aryl group having 6 to 40 carbon atoms or a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms;

n is an integer from 1 to 100).

In Formula 1, 'substituted' means substituted with a substituent, and the substituent may be different or the same, specifically, a halogen atom such as fluorine, chlorine, bromine, an amino group, a hydroxyl group, a nitro group, An alkyl group, an aryl group, a cycloalkyl group, an aryloxy group, an alkylthio group, an arylthio group, and the like, but are not limited thereto.

In Formula 1, 'heteroaryl group' refers to an aryl group in which one or more heteroatoms other than carbon atoms are included among the atoms constituting the ring, and may be a saturated or unsaturated ring, and may be a monocyclic or condensed ring. , The hetero atom may be one or more selected from oxygen, sulfur and nitrogen. The heteroaryl group is, for example, pyridine, pyrazine, pyrimidine, pyridazine, triazine, pyrrole, furan, thiophene, imidazole, pyrazole, oxazole, thiazole, isoxazole, isothiazole, triazole , thiadiazole, oxadiazole, quinoline, benzofuran, indole, morpholine, pyrrolidine, piperidine, tetrahydrofuran and the like.

In the present invention, by including the above polymer, a hard mask formed from the composition for a hard mask of the present invention can sufficiently secure solubility to exhibit excellent coating characteristics and excellent etching resistance.

The polymer according to the present invention may include a first unit represented by Formula 2 below or a synthetic equivalent thereof; And it can be prepared through a condensation reaction of a second unit represented by Formula 3 or a synthetic equivalent thereof.

[Formula 2]

(In Formula 2, R ₁ is a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms, or a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms,

R ₂ is hydrogen, a hydroxy group, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, or a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms.)

[Formula 3]

(In Formula 3, R ₃ is a substituted or unsubstituted aryl group having 6 to 40 carbon atoms or a substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms.)

The first unit represented by Chemical Formula 2 may be, for example, any one selected from the group consisting of those represented by Chemical Formulas 2-1 to 2-4 below.

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Formula 2-4]

In addition, the second unit represented by Chemical Formula 3 may be, for example, any one selected from the group consisting of those represented by Chemical Formulas 3-1 to 3-5 below.

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

[Formula 3-4]

[Formula 3-5]

(In Chemical Formulas 3-4 and 3-5, X is nitrogen (N), oxygen (O), or sulfur (S).)

As described above, the polymer according to the present invention may include a first unit including an indole derivative. Due to the high carbon content of the indole derivative, intermolecular interactions through an oxidative coupling reaction may be promoted, thereby improving packing properties, and consequently, etching resistance and heat resistance of the hardmask layer may be improved.

In addition, the polymer according to the present invention may include a second unit containing an aryl group. The flexible trivalent carbon structure containing an aryl group provides solubility to the polymer, and at the same time, depending on the type of aryl group included, the carbon content is increased to improve packing characteristics, resulting in etching resistance and coating of the hard mask layer. properties can be improved at the same time.

In addition, the polymer according to the present invention can improve the flexibility of the polymer due to the rotatable tertiary carbon structure between the indole derivative and the aryl group. Therefore, the polymer according to the present invention may have excellent solubility despite containing an indole derivative having a relatively high carbon content and an aryl group, and thus coating properties such as flatness and gap-fill characteristics of the hard mask layer may be improved. there is.

In the polymer represented by Chemical Formula 1, R ₃ may be any one selected from substituents represented by Chemical Formulas 4-1 to 4-5 in terms of etching resistance and coating properties of the hard mask layer.

[Formula 4-1]

[Formula 4-2]

[Formula 4-3]

[Formula 4-4]

[Formula 4-5]

(In Chemical Formulas 4-4 and 4-5, X is nitrogen (N), oxygen (O), or sulfur (S).)

As such, when R ₃ of the polymer represented by Formula 1 is substituted with any one selected from substituents represented by Formulas 4-1 to 4-5, appropriate solubility can be secured while increasing the carbon content of the polymer. desirable.

According to one embodiment of the present invention, when a relatively bulky aryl group or heteroaryl group having 14 to 40 carbon atoms is substituted at the R ₃ position of the polymer according to Formula 1, etching resistance is increased by increasing the carbon content. On the other hand, since solubility and coating properties can be relatively lowered, the solubility of the polymer can be properly secured by substituting an alkyl group having 1 to 4 carbon atoms with relatively little steric hindrance at the position of R ₁ , and as a result, hard mask The etching resistance and coating properties of the layer can be simultaneously improved.

In addition, according to one embodiment of the present invention, the content of the polymer is not particularly limited as long as it can achieve the object of the present invention, but may be, for example, 5 to 25% by weight based on the total weight of the composition, preferably It may be 5 to 15% by weight. When the above range is satisfied, the effect of the present invention described above can be most excellently displayed.

In addition, the weight average molecular weight of the polymer according to an embodiment of the present invention is not particularly limited as long as the object of the present invention can be achieved, but may be, for example, 1000 to 8000, preferably 1000 to 3000. there is. When the above range is satisfied, the effect of the present invention described above may be most excellent.

menstruum

The solvent used in the composition for a hard mask according to embodiments of the present invention is not particularly limited, and may include an organic solvent having sufficient solubility in the above-described polymer. For example, the solvent is propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone, ethyl lactate, gamma-butyrolactone (γ-butyrolactone; GBL), acetyl acetone, and the like.

The content of the solvent is not particularly limited, and may be included in a residual amount excluding the polymer and additional agents to be described later. For example, the solvent may be included in 75 to 95% by weight, preferably 85 to 95% by weight, based on the total weight of the hard mask composition. When the above range is satisfied, the effect of the present invention may be excellent.

additional formulation

If necessary, the composition for a hard mask according to an embodiment of the present invention may further include at least one of a crosslinking agent and a catalyst. The crosslinking agent is capable of crosslinking the repeating unit of the polymer by heating in a reaction catalyzed by the generated acid, and is specifically limited to a crosslinking agent capable of reacting with the polymer in such a way that it can be catalyzed by the generated acid. It doesn't work. As a representative example of such a crosslinking agent, any one selected from the group consisting of melamine, amino resins, glycoluril compounds and bis-epoxy compounds may be used.

By further including the crosslinking agent, curing characteristics of the hard mask composition may be further enhanced.

Specific examples of the crosslinking agent include etherified amino resins such as methylated or butylated melamine (specific examples include N-methoxymethyl-melamine or N-butoxymethyl-melamine) and methylated or butylated melamine. A urea resin (specific examples, Cymel U-65 Resin or UFR 80 Resin), a glycoluril derivative represented by Formula 11 (specific examples, Powderlink 1174), bis(hydroxymethyl) represented by Formula 12 -p-cresol compound) and the like. In addition, a bisepoxy-based compound represented by the following formula (13) and a melamine-based compound represented by the following formula (14) can also be used as a crosslinking agent.

[Formula 11]

[Formula 12]

[Formula 13]

[Formula 14]

As the catalyst, an acid catalyst or a basic catalyst may be used.

As the acid catalyst, a thermally activated acid catalyst may be used. As an example of the acid catalyst, an organic acid such as p-toluene sulfonic acid monohydrate may be used, and a TAG (thermal acid generator)-type compound that promotes storage stability may be mentioned. Thermal acid generators are acid generator compounds designed to release acids upon heat treatment, such as pyridinium p-toluene sulfonate, 2,4,4,6-tetrabromocyclohexadiene On, benzoin tosylate, 2-nitrobenzyl tosylate, alkyl ester of organic sulfonic acid, etc. can be used. As the basic catalyst, any one selected from ammonium hydroxide represented by NH ₄ OH or NR ₄ OH (R is an alkyl group) may be used.

In addition, other photosensitive catalysts known in the art of resist may also be used as long as they are compatible with the other components of the antireflective composition.

When the crosslinking agent is included, the content of the crosslinking agent may be 1 part by weight to 30 parts by weight, preferably 5 parts by weight to 20 parts by weight, more preferably 5 parts by weight to 10 parts by weight, based on 100 parts by weight of the polymer. may be wealth. In addition, when the catalyst is included, the content of the catalyst may be 0.001 part by weight to 5 parts by weight, preferably 0.1 part by weight to 2 parts by weight, more preferably 0.1 part by weight to 5 parts by weight, based on 100 parts by weight of the polymer. It may be 1 part by weight.

When the crosslinking agent is included within the above range, appropriate crosslinking characteristics may be obtained without changing the optical characteristics of the formed underlayer film.

In addition, when the content of the catalyst is within the above range, appropriate crosslinking properties may be obtained, and acidity, which affects storage stability, may be appropriately maintained.

additive

If necessary, the hard mask composition of the present invention may further include an additive such as a surfactant. Alkylbenzenesulfonic acid salts, alkylpyridinium salts, polyethylene glycols, quaternary ammonium salts, etc. may be used as the surfactant, but are not limited thereto. In this case, the content of the surfactant may be 0.1 part by weight to 10 parts by weight based on 100 parts by weight of the polymer.

When the content of the surfactant is within the above range, appropriate crosslinking properties may be obtained without changing the optical properties of the formed underlayer film.

Hereinafter, experimental examples including preferred examples and comparative examples are presented to aid understanding of the present invention, but these examples are only illustrative of the present invention and do not limit the scope of the appended claims, and It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope and scope of the technical idea, and it is natural that these changes and modifications fall within the scope of the appended claims.

<Example>

Synthesis Example: Synthesis of Polymers

Synthesis Example 1 (Polymer A-1)

A 1L three-necked flask equipped with a thermometer, condenser, stirrer, and dropping funnel was installed in an oil container, and 19.3 g (0.1 mol) of the compound represented by Formula 2-1 was added to the reactor, and 200 g of propylene glycol monomethyl ether acetate (PGEMA) ) Then, 0.19 g (0.002 mol) of sulfuric acid was added. The dropping funnel was filled with a solution in which 26.9 g (0.1 mol) of the compound represented by Chemical Formula 3-1 was dissolved in 100 g of PGMEA, and the mixture was added dropwise for 2 hours while maintaining the internal temperature of the reactor at 120°C. After completion of the dropwise addition, after additional stirring at the same temperature for 12 hours, 0.45 g (0.003 mol) of triethanolamine was added to the reactor as a neutralizer, stirred at room temperature for an additional 1 hour, and cooled to room temperature to obtain a reaction mixture having a mass ratio of 3 :7 was added dropwise while stirring to a round bottom flask containing a mixed solution of distilled water/methanol. A solid product produced at the bottom of the flask was obtained using a high-speed stirrer and distilled under reduced pressure at 80° C. for 1 hour to obtain a polymer represented by the following formula (A-1). The weight average molecular weight (Mw) of the polymer was 2000, and the degree of dispersion (Mw/Mn) was 1.5.

[Formula A-1]

Synthesis Example 2 (Polymer A-2)

Represented by the following formula (A-2) in the same manner as in Synthesis Example 1, except that 26.9 g (0.1 mol) of Formula 2-2 was used as an indole derivative and 15.6 g (0.1 mol) of Formula 3-2 was used as an aryl aldehyde derivative. A polymer was obtained. The weight average molecular weight (Mw) of the polymer was 1840, and the degree of dispersion (Mw/Mn) was 1.25.

[Formula A-2]

Synthesis Example 3 (Polymer A-3)

Formula 2-3 14.5 g (0.1 mol) as an indole derivative and Formula 3-3 23.0 g (0.1 mol) as an aryl aldehyde derivative. A polymer was obtained. The weight average molecular weight (Mw) of the polymer was 1650, and the degree of dispersion (Mw/Mn) was 1.21.

[Formula A-3]

Synthesis Example 4 (Polymer A'-1)

11.7 g (0.1 mol) of indole, 25.3 g (0.1 mol) of 2,6-naphthalenedicarbonyl dichloride, and 300 g of 1,2-dichloroethane were added to the flask, and 13.3 g (0.1 mol) of aluminum chloride was slowly added at room temperature. After addition, the mixture was stirred at 60° C. for 8 hours. After completion of the reaction, methanol was added dropwise and the formed solid compound was filtered and dried. To a solution of 6.0 g (0.02 mol) of the solid compound obtained in this process dissolved in 100 g of tetrahydrofuran, 7.6 g (0.2 mol) of sodium borohydride aqueous solution was slowly added dropwise and stirred at 50° C. for 11 hours. After completion of the reaction, pH 7 was neutralized using a 5% hydrogen chloride solution, and the formed solid compound was filtered and dried to obtain a polymer represented by the following formula (A'-1). The weight average molecular weight (Mw) of the polymer was 3100, and the degree of dispersion (Mw/Mn) was 1.8.

[Formula A'-1]

Synthesis Example 5 (Polymer A'-2)

In a 1L flask, 11.7 g (0.1 mol) of indole, 23.0 g (0.1 mol) of 1-pyrenecarboxaldehyde, 24.5 g (0.1 mol) of triphenylamine, and 19.0 g (0.1 mol) of p-toluenesulfonic acid monohydrate were mixed with propylene glycol. It was dissolved in 300 g of monomethyl ether acetate (PGMEA) and stirred at 120°C. After the reaction was completed, a small amount of ethyl acetate (EA) and tetrahydrofuran were added, and then the acid catalyst was removed using distilled water. Thereafter, the solid compound formed using tetrahydrofuran and hexane was filtered and dried to obtain a polymer represented by the following formula (A'-2). The weight average molecular weight (Mw) of the polymer was 1780, and the degree of dispersion (Mw/Mn) was 1.5.

[Formula A'-2]

Examples and Comparative Examples: Preparation of composition for hard mask

A composition for a hard mask having the composition and content (unit: wt%) shown in Table 1 below was prepared.

division polymer menstruum ingredient content ingredient content ingredient content Example 1 A-1 10 B-1 63 B-2 27 Example 2 A-2 10 B-1 63 B-2 27 Example 3 A-3 10 B-1 63 B-2 27 Comparative Example 1 A'-1 10 B-1 63 B-2 27 Comparative Example 2 A'-2 10 B-1 63 B-2 27

A-1: Polymer A-1 synthesized according to Synthesis Example 1

A-2: Polymer A-2 synthesized according to Synthesis Example 2

A-3: Polymer A-3 synthesized according to Synthesis Example 3

A'-1: Polymer A'-1 synthesized according to Synthesis Example 4

A'-2: Polymer A'-2 synthesized according to Synthesis Example 5

B-1: propylene glycol monomethyl ether acetate (PGMEA)

B-2: cyclohexanone

Experimental example

The etching resistance, coating property, and chemical resistance of the hard mask layer or hard mask formed of the compositions in Table 1 were evaluated through the evaluation method described below. The evaluation results are shown in Table 2 below.

(1) Evaluation of etching resistance

Compositions according to Examples and Comparative Examples were each coated on a silicon wafer by a spin-coating method, heat-treated at 400° C. for 90 seconds to form a thin film, and then the initial thin film thickness was measured. The wafer coated with each formed film was dry etched using a dielectric etcher under conditions of 30 mT / 600-600 W / 42 CF ₄ / 600 Ar / 15 O ₂ / 30 sec, and the film thickness was measured. Etch rate was calculated by dividing the difference between the initial thin film thickness (Å) and the thin film thickness after etching (Å) by the etching time (Å/min).

(2) Evaluation of coating properties

Compositions according to Examples and Comparative Examples were spin-coated and heat-treated in the same manner as the etching resistance evaluation, and then the uniformity of the coated thin film was evaluated by checking with the naked eye and using an electron microscope.

◎: Non-uniformity of the coating surface cannot be confirmed (microscope)

○: Non-uniformity of the coating surface cannot be confirmed (visual)

△: Local non-uniformity of the coating surface can be confirmed (visual)

Ⅹ: The entire coating surface unevenness can be confirmed (visual)

(3) Chemical resistance evaluation

The compositions according to Examples and Comparative Examples were spin-coated and heat-treated to form thin films in the same manner as evaluation of etching resistance. The wafer coated with the formed thin film was immersed in a petri dish containing PGMEA for 10 minutes to measure the thickness change of the thin film. The remaining film ratio represents the thin film thickness (Å) after soaking compared to the initial thin film thickness (Å).

◎ : 95% or more film remaining

○: Remaining film rate of 90% or more

△: Film remaining rate 70% or more

X: Remaining film rate less than 50% and thin film falling off

Etch rate (Å/min) coating property chemical resistance Example 1 927 ◎ ○ Example 2 917 ○ ○ Example 3 938 ◎ ○ Comparative Example 1 1197 ○ △ Comparative Example 2 1186 △ ○

Referring to Table 2, Examples 1 to 3 exhibited excellent overall properties in a well-balanced manner in terms of etching resistance, coating properties, and chemical resistance. could On the other hand, in the case of Comparative Examples 1 and 2, it was confirmed that the etching resistance was significantly lower than that of Examples 1 to 3, and furthermore, in the case of Comparative Example 1, the chemical resistance and in the case of Comparative Example 2, the coating property, respectively. Degraded results were observed.

Claims (7)

A composition for a hard mask comprising at least one selected from the group consisting of polymers represented by the following formulas A-1 to A-3 and a solvent:
[Formula A-1]

[Formula A-2]

[Formula A-3]

(In the above formulas A-1 to A-3, n is an integer from 1 to 100.) delete delete delete delete According to claim 1,
The composition for the hard mask is based on the total weight of the composition,
5 to 25% by weight of at least one selected from the group consisting of polymers represented by Formulas A-1 to A-3; and
A composition for a hard mask comprising 75 to 95% by weight of a solvent. According to claim 1,
The hard mask composition further comprises at least one selected from a crosslinking agent, a catalyst, and a surfactant.