WO2019143121A1

WO2019143121A1 - Composition for hard mask

Info

Publication number: WO2019143121A1
Application number: PCT/KR2019/000637
Authority: WO
Inventors: 최한영; 양돈식; 이은상
Original assignee: 동우화인켐 주식회사
Priority date: 2018-01-17
Filing date: 2019-01-16
Publication date: 2019-07-25
Also published as: KR20190087749A; KR102349952B1

Abstract

The present invention provides a composition, for a hard mask, comprising a solvent and polymer represented by a particular chemical formula. A hard mask having enhanced etch resistance, solubility and smoothness can be formed from the composition for a hard mask.

Description

Composition for hard mask

The present invention relates to a composition for a hard mask. More particularly, the present invention relates to a composition for a hard mask comprising a polycondensate of at least one aromatic compound.

For example, in the fields of semiconductor manufacturing, microelectronics, etc., the degree of integration of structures such as circuits, wiring lines, insulation patterns and the like is continuously improving. Accordingly, a photolithography process for fine patterning of the structures has been developed at the same time.

Generally, a photoresist is applied on a film to be etched to form a photoresist layer, and a photoresist pattern is formed through exposure and development. Then, a predetermined pattern can be formed by partially removing the film to be etched by using the photoresist pattern as an etching mask. After the image transfer to the etch target film is performed, the photoresist pattern may be removed through an ashing and / or strip process.

An anti-reflection coating (ARC) layer may be formed between the etch target film and the photoresist layer to suppress the resolution degradation due to light reflection during the exposure process. In this case, the etching for the ARC layer is added, so that the consumption amount or the etching amount of the photoresist layer or the photoresist pattern can be increased. Further, when the thickness of the etching target film increases or the etching amount required for forming a desired pattern increases, sufficient etching resistance of the photoresist layer or the photoresist pattern may not be ensured.

Thus, a resist undercoat may be added between the etch target film and the photoresist layer to ensure etch resistance and etch selectivity of the photoresist for desired pattern formation.

The resist undercoat film has sufficient etchability (or etching resistance), heat resistance, for example, for a high-temperature etching process, and also satisfies properties required to be formed into a uniform thickness by, for example, a spin- desirable.

Korean Patent Laid-Open No. 10-2010-0082844 discloses an example of a composition for forming a resist lower film.

An object of the present invention is to provide a composition for a hard mask capable of forming a hard mask having excellent mechanical and chemical properties.

1. A composition for a hard mask comprising a polymer represented by the following formula (1) and a solvent:

[Chemical Formula 1]

(Wherein Ar ₁ is an arylene group having 6 to 35 carbon atoms, which may be further substituted with a hydroxyl group (-OH)

R ₁ and R ₄ are each independently hydrogen or a linear or branched alkyl group having 1 to 8 carbon atoms,

R ₂ and R ₃ are each independently hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms, Silyl group, and the alkyl group may be further substituted with a hydroxyl group or a halogen,

n ₁ is an integer of 1 to 200, n ₃ is 0 or 1, and n ₂ and n ₄ are each independently an integer of 0 to 5).

2. The composition for a hard mask as in 1 above, wherein said polymer comprises an aromatic compound having 6 to 35 carbon atoms and a polymer of the following formula:

(2)

(Wherein R ₁ is hydrogen or a linear or branched alkyl group having 1 to 8 carbon atoms,

R ₂ is hydrogen, a straight or branched alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms, or a silyl group having 1 to 8 carbon atoms, and the alkyl group may be substituted with a hydroxy group or halogen And n is an integer of 0 to 5).

3. The composition for a hard mask according to 2 above, wherein the compound of Formula 2 comprises at least one selected from the group consisting of the following Formulas 2-1 to 2-11:

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

[Chemical Formula 2-5]

[Chemical Formula 2-6]

[Chemical Formula 2-7]

[Chemical Formula 2-8]

[Chemical Formula 2-9]

[Chemical Formula 2-10]

[Chemical Formula 2-11]

4. The hard mask composition according to ₁ above, wherein Ar ₁ in the formula (1) is derived from at least one aromatic compound selected from the group consisting of compounds represented by the following formulas (3-1) to (3-6)

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

[Chemical Formula 3-4]

[Formula 3-5]

[Chemical Formula 3-6]

(In the formulas (3-1) to (3-6), R < ₅ > may be one or plural in the aromatic compound and independently of each other, hydrogen or a hydroxyl group).

5. The composition of claim 1, wherein the composition comprises from 5 to 30% by weight of the polymer and from 70 to 95% by weight of the solvent in the total weight of the composition.

6. The composition for hard mask according to 1 above, further comprising at least one of a crosslinking agent, a catalyst or a surfactant.

By using the composition for a hard mask according to embodiments of the present invention, it is possible to form a hard mask having excellent etching resistance and improved film-forming properties such as solubility, coating property and the like.

The composition for a hard mask according to the embodiments of the present invention can form a hard mask having etch resistance and improved film-forming properties such as solubility, coatability, etc. by including the polymer of formula (1).

The polymer according to the embodiments of the present invention is derived from an aromatic compound having a high carbon content, so that the etching resistance is improved and the mechanical properties of the hard mask can be remarkably improved.

The polymer according to the embodiments of the present invention may be derived from a vinyl ether linker compound so that the side reaction during the polymerization reaction may be reduced.

Polymers according to embodiments of the present invention may include an alkoxy group, a silyloxy group, or an acyloxy group so that the solubility of the composition is improved, thereby improving film forming properties such as coatability and uniformity of the hard mask.

A high resolution photolithography process can be implemented using the hard mask formed from the composition for hard mask, and a target pattern having a desired fine line width can be formed.

Embodiments of the present invention provide a composition for a hard mask having a specific structure of a polymer and thus having excellent solubility and flatness as well as resistance to etching.

A hard mask film may be formed using the composition for a hard mask, for example, applied between a photoresist layer and a film to be etched to be utilized as a resist under film. The hard mask film may be partially removed through a photoresist pattern to form a hard mask, and the hard mask may be used as an additional etching mask.

The hard mask film or the hard mask may be utilized, for example, as a spin-on hard mask (SOH).

Hereinafter, the composition for a hard mask according to embodiments of the present invention will be described in detail. When a compound or an isomer of a resin represented by the formula used in the present application is present, the compound or the resin represented by the formula means a representative formula including the isomer thereof.

As used herein, the term " aromatic "or" aromatic compound "is used to encompass not only compounds in which the entire compound satisfies the directionality, but also those in which some structure or group of the compound satisfies the directivity.

As used herein, the term "carbon content" may refer to the ratio of carbon mass to total mass per molecule of a compound.

The composition for a hard mask according to embodiments of the present invention includes a polymer (or a condensate) and a solvent, and may further include an additional agent such as a cross-linking agent, a catalyst, and the like.

중합체polymer

According to embodiments of the present invention, the polymer may be represented by the following formula (1).

[Chemical Formula 1]

In formula (1), Ar ₁ may be an arylene group having 6 to 35 carbon atoms and may be further substituted with a hydroxyl group (-OH).

R ₁ and R ₄ are each independently hydrogen or a linear or branched alkyl group having 1 to 8 carbon atoms.

R ₂ and R ₃ are each independently hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cycloalky group having 3 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms, Silyl group, and the alkyl group may be further substituted with a hydroxy group (-OH) or a halogen. For example, n ₁ may be an integer of 1 to 200, n ₃ may be 0 or 1, and n ₂ and n ₄ may each independently be an integer of 0 to 5.

In the present application, when the alkyl group is a branched chain, the carbon number may be 3 or more.

The composition for a hard mask according to the embodiments of the present invention can form a hard mask having enhanced film-forming properties such as solubility, coating properties and the like while maintaining the etching resistance by including the polymer of formula (1).

When the hard mask composition is coated, the ether group of the end improves the coating property. When the baking process is performed at 400 to 450 ° C, the terminal ether group is decomposed and removed to form the aromatic structure (Ar ₁ ) remains in most of the polymer, the carbon content is increased, and the etching resistance of the hard mask can be further improved.

In some embodiments, the polymer may comprise an aromatic compound having 6 to 35 carbon atoms and a polymer of a compound of formula (2).

(2)

In the formula (2), R ₁ may be hydrogen or a linear or branched alkyl group having 1 to 8 carbon atoms.

R ₂ may be hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms, or a silyl group having 1 to 8 carbon atoms, and the alkyl group may be substituted with a hydroxy group or halogen Can be further substituted.

For example, n may be an integer of 0 to 5.

When the above-mentioned polymer is prepared by the vinyl ether compound of formula (2), the reaction rate is faster than that of the aldehyde generally used, and it can have a higher yield and can improve the solubility of the polymer.

In one preferred embodiment, the compound of Formula 2 may include at least one compound selected from the group consisting of the following Formulas 2-1 to 2-11.

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

[Chemical Formula 2-5]

[Chemical Formula 2-6]

[Chemical Formula 2-7]

[Chemical Formula 2-8]

[Chemical Formula 2-9]

[Chemical Formula 2-10]

[Chemical Formula 2-11]

In some embodiments, Ar ₁ of formula ( ₁₎ may include one derived from at least one aromatic compound selected from the group consisting of compounds represented by the following formulas (3-1) to (3-6).

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

[Chemical Formula 3-4]

[Formula 3-5]

[Chemical Formula 3-6]

In formulas (3-1) to (3-6), R ₅ may be one or more in the aromatic compound, and may independently represent a hydrogen or a hydroxyl group.

Since the polymer is derived from an aromatic compound having a high carbon content, the etching resistance of the hard mask can be improved.

In some embodiments, the polymer may polymerize an aromatic compound having 6 to 35 carbon atoms and a compound of Formula 2 in the presence of an acid (acid condition). When the polymerization is carried out in the presence of an acid, the polymer having the repeating unit of the above-mentioned formula (1) can be obtained in a more easy and high yield.

In some embodiments, the polymer may be prepared using only an aromatic compound having 6 to 35 carbon atoms and the compound of Formula 2, and other aromatic compounds or linker compounds may not be used in the production of the polymer. Therefore, it is possible to prevent deterioration of etching resistance, solubility, and flatness due to addition of other compounds, and to secure desired physical properties.

However, in one embodiment, other linkers or linkages in the main chain unit may be included within the scope of not interfering with the effect of the combination of the aromatic compound having 6 to 35 carbon atoms and the compound of formula 2, Examples do not necessarily exclude it.

In the preparation of the polymer, the aromatic compound having 6 to 35 carbon atoms and the compound of formula (1) may be used in a molar ratio of, for example, from about 1: 0.5 to 1: 1.5, but are not limited thereto.

The formula (1) indicates that the above units are included together, and does not necessarily define the bonding order and position.

In one embodiment, the polydispersity index (PDI) (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the polymer can be from about 1.5 to 6.0, preferably from about 1.5 to 3.0 . Within this range, film formation properties such as favorable solubility, etch resistance, coating property and flatness can be improved together.

The content of the polymer is not particularly limited, but may be, for example, about 5 to 30% by weight of the total weight of the hard mask composition, and in one embodiment about 10 to 20% by weight.

용매menstruum

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

The content of the solvent is not particularly limited and may be included in the balance excluding the polycondensate and the additional agents described below. For example, the solvent may comprise from about 70% to about 95% by weight of the total weight of the composition for a hard mask.

추가 제제Additional formulations

Optionally, the composition for a hard mask according to embodiments of the present invention may further comprise additional agents such as crosslinking agents, catalysts, and surfactants.

The crosslinking agent is capable of crosslinking the repeating units contained in the polymer with each other, and can react with, for example, a hydroxyl group contained in the polymer. By the crosslinking agent, the curing property of the composition for a hard mask can be further strengthened.

Examples of the cross-linking agent include melamine, an amino resin, a glycoluril compound, and a bis-epoxy compound.

The cross-linking agent may be, for example, an etherified amino resin such as methylated or butylated melamine (specifically N-methoxymethyl-melamine or N-butoxymethyl-melamine) and methylated or butylated (Hydroxymethyl) -p (methoxymethyl) urea resin represented by the following general formula (7), urea resin (specific examples of which are Cymel U-65 Resin or UFR 80 Resin), glycoluril derivatives - cresol compounds and the like. The bis-epoxy compound represented by the following general formula (8) and the melamine-based compound represented by the following general formula (9) can also be used as a crosslinking agent.

[Chemical Formula 6]

(7)

[Chemical Formula 8]

[Chemical Formula 9]

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

The acid catalyst may be a thermally activated acid catalyst. As an example of the acid catalyst, an organic acid such as p-toluenesulfonic acid can be used. As the acid catalyst, a thermal acid generator (TAG) system compound may be used. Examples of the thermal acid generator system catalyst include pyridinium p-toluene sulfonate, 2,4,4,6-tetrabromocyclohexadiene, benzoin tosylate, 2-nitrobenzyltosyl Alkyl esters of organic sulfonic acids, and the like.

As the basic catalyst, any one selected from among NH ₄ OH or ammonium hydroxide represented by NR ₄ OH (R is an alkyl group) can be used.

When the cross-linking agent is included, the content of the cross-linking agent may be about 1 to 30 parts by weight, preferably about 5 to 20 parts by weight, and more preferably about 5 to 10 parts by weight based on 100 parts by weight of the polycondensate.

When the catalyst is included, the content of the catalyst may be about 0.001 to 5 parts by weight, preferably about 0.1 to 2 parts by weight, more preferably about 0.1 to 1 part by weight, per 100 parts by weight of the polycondensate .

Appropriate crosslinking properties can be obtained within the range of the content of the crosslinking agent and the catalyst without deteriorating the etching resistance, heat resistance, solubility and flatness of the polycondensate.

The composition for a hard mask according to the embodiments of the present invention may further include a surfactant for improving the surface property and adhesiveness of the hard mask. As the surfactant, alkylbenzenesulfonate, alkylpyridinium salt, polyethylene glycol, quaternary ammonium salt and the like can be used, but not limited thereto. The content of the surfactant may be, for example, about 0.1 to 10 parts by weight based on 100 parts by weight of the polycondensate.

In addition, embodiments of the present invention provide a method of forming a pattern using the hard mask composition.

According to exemplary embodiments, a hard mask can be formed by forming a film to be etched on a substrate, and coating and hardening the above-mentioned hard mask composition on the film to be etched. The curing may be performed by a heat-baking process, and it may be desirable to bake in the range of 400 to 450 degrees as described above.

A photoresist film is formed on the hard mask, and the photoresist film is selectively exposed and developed to form a photoresist pattern. A hard mask pattern may be formed by selectively etching the hard mask using the photoresist pattern.

Thereafter, a predetermined target pattern can be formed by selectively removing the etching target film using the photoresist pattern and the hard mask pattern together as an etching mask.

For example, the substrate may comprise a silicon wafer or a semiconductor substrate fabricated from a germanium wafer. The etch target film may include an insulating material such as silicon oxide, silicon nitride, etc., a conductive material such as metal or metal nitride, or a semiconductor material such as polysilicon.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. It will be apparent to those skilled in the art that various changes and modifications can be made to the embodiments within the spirit and scope of the appended claims.

실시예 및 비교예Examples and Comparative Examples

A composition for a hard mask of the composition and the content (% by weight) shown in Table 1 below was prepared. In Examples and Comparative Examples, paratoluene sulfonic acid (5 mol% based on the hydroxyl group-containing aromatic compound) was used as an acid catalyst in the formation of the polymer (A).

A-1:

,

(Weight average molecular weight: 3100) produced by a condensation reaction at a molar ratio (1: 1 molar ratio)

A-2:

.

(Weight-average molecular weight: 2800) produced by the condensation reaction of polyoxyethylene (1: 1 molar ratio)

A-3:

,

(Weight-average molecular weight: 3300) produced by the condensation reaction at a molar ratio (1: 1 molar ratio)

A-4:

,

(Weight average molecular weight: 2400) produced by a condensation reaction in the presence of a polar solvent (1: 1 molar ratio)

A-5:

.

(Weight-average molecular weight: 3600) produced by the condensation reaction at a molar ratio (1: 1 molar ratio)

A-6:

,

(Weight-average molecular weight: 3800) produced by the condensation reaction of ethylene (1: 1 molar ratio)

A-7:

,

(Weight-average molecular weight: 4200) produced by a condensation reaction of a poly (1: 1 molar ratio)

A-8:

,

(Weight-average molecular weight: 2500) produced by the condensation reaction of ethylene (1: 1 molar ratio)

A-9:

,

(Weight-average molecular weight: 2700) produced by the condensation reaction of ethylene (1: 1 molar ratio)

A-10:

,

(Weight average molecular weight: 2300) produced by a condensation reaction at a molar ratio (1: 1 molar ratio)

A'-1:

, A formaldehyde (HCHO) (1: 1 molar ratio) condensation reaction (weight average molecular weight: 1800)

A'-2:

(Weight average molecular weight: 1600) produced by the condensation reaction of acetaldehyde (CH ₃ CHO) (1: 1 molar ratio)

A'-3:

(Weight average molecular weight: 2100) produced by the condensation reaction of acetaldehyde (CH ₃ CHO) (1: 1 molar ratio)

A'-4:

(Weight average molecular weight: 2000) produced by the condensation reaction of acetaldehyde (CH ₃ CHO) (1: 1 molar ratio)

B: PGMEA

C: N-methoxymethyl-melamine resin

D: p-toluenesulfonic acid-pyridine salt

E: triethylene glycol

실험예Experimental Example

The etchability, solubility and flatness of the hard mask layer or the hard mask formed from the compositions of Table 1 were evaluated through the evaluation method described below. The evaluation results are shown in Table 2 below.

(1) 내에칭성 평가(1) Evaluation of etchability

The compositions according to Examples and Comparative Examples were respectively coated on a silicon wafer by spin coating and baked at 400 DEG C for 60 seconds to form a hard mask layer having a thickness of 1500 ANGSTROM. Each of the formed hard mask layers was coated with an ArF photoresist and baked at 110 ° C for 60 seconds. Exposure was then performed using ASML (XT: 1450G, NA 0.93) exposure equipment, and then TMAH (2.38 wt% aqueous solution) And developed to obtain a line-and-space pattern of 60 nm.

The cross-section of the photoresist pattern as a further cured at 110 ℃ 60 seconds, and the photoresist pattern and the CHF ₃ / CF _4, using a gas mixture proceeds for 20 seconds to dry etching for each of the said hard mask layer, and FE-SEM And the etching rate was measured to determine the etching resistance against the halogen plasma.

<내에칭성 판정>&Lt; Determination of etchability &

◎: Etching rate less than 10 Å / Sec

O: etching rate of 10 Å / sec or more and less than 11 Å / sec

DELTA: etching rate of 11 Å / sec or more and less than 12 Å / sec

×: etching rate of 12 Å / sec or more

(2) 용해성(2) Solubility

The compositions of the examples and comparative examples were stirred at 50 ° C for 1 hour and then 1) the dissolved state of the polymer at a heating temperature (50 ° C) was confirmed, and after cooling to room temperature, 2) , And further stirred at room temperature for 6 hours. (3) The dissolved state of the polymer was confirmed at the room temperature (25 DEG C), and the solubility was measured.

<용해성 판정>&Lt; Determination of solubility &

◎: Unhealthy polymer is not visually confirmed at room temperature.

○: Under normal temperature condition, unheated polymer is not visually confirmed, but a small amount of unheated polymer is visually confirmed at room temperature.

△: The unhydrolyzable polymer was not visually confirmed in the warmed state, but the unheated polymer was visually confirmed in the normal temperature state.

X: A small amount of unheated polymer was visually confirmed in a heated state.

(3) 평탄성 평가(3) Flatness evaluation

The compositions of Examples and Comparative Examples were coated on a SiO ₂ wafer substrate having a trench width of 10 μm and a depth of 0.50 μm and dried to form a hard mask film. The thickness difference between the trench portion and the non-trench portion was measured by a scanning electron microscope (SEM) to evaluate flatness.

<평탄성 판정>&Lt; Flatness judgment &

?: Thickness difference less than 150 nm

?: Thickness difference of 150 to 175 nm

DELTA: thickness difference of 175 to 200 nm

X: Thickness difference exceeding 200 nm

Referring to Table 2, the etchability, solubility, and flatness of the hard mask using the aromatic compound and the compound represented by the specific formula according to the embodiments of the present invention are improved in a balanced manner as a whole.

On the other hand, in Comparative Example 1 in which formaldehyde was used, the resistance to nicking was increased, but the solubility and flatness were excessively decreased.

In the case of Comparative Examples 2 to 4 in which acetaldehyde was used, the etch resistance was equivalent but the solubility and flatness were not good.

Claims

A composition for a hard mask comprising a polymer represented by the following formula (1) and a solvent:

[Chemical Formula 1]

(Wherein Ar 1 is an arylene group having 6 to 35 carbon atoms, which may be further substituted with a hydroxyl group (-OH)

R 1 and R 4 are each independently hydrogen or a linear or branched alkyl group having 1 to 8 carbon atoms,

R 2 and R 3 are each independently hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms or a silyl group having 1 to 8 carbon atoms, May be further substituted with a hydroxy group or a halogen,

n 1 is an integer of 1 to 200, n 3 is 0 or 1, and n 2 and n 4 are each independently an integer of 0 to 5).
The composition for a hard mask according to claim 1, wherein the polymer comprises an aromatic compound having 6 to 35 carbon atoms and a polymer of the following formula:

(2)

(Wherein R 1 is hydrogen or a linear or branched alkyl group having 1 to 8 carbon atoms,

R 2 is hydrogen, a straight or branched alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an acyl group having 1 to 8 carbon atoms, or a silyl group having 1 to 8 carbon atoms, and the alkyl group may be substituted with a hydroxy group or halogen And n is an integer of 0 to 5).
The composition for a hard mask according to claim 2, wherein the compound of formula (2) comprises at least one selected from the group consisting of the following formulas (2-1) to (2-11)

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

[Chemical Formula 2-5]

[Chemical Formula 2-6]

[Chemical Formula 2-7]

[Chemical Formula 2-8]

[Chemical Formula 2-9]

[Chemical Formula 2-10]

[Chemical Formula 2-11]

.
The hard mask composition according to claim 1, wherein Ar 1 in the formula (1) is derived from at least one aromatic compound selected from the group consisting of compounds represented by the following formulas (3-1) to (3-6)

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

[Chemical Formula 3-4]

[Formula 3-5]

[Chemical Formula 3-6]

(In the formulas (3-1) to (3-6), R < 5 > may be one or plural in the aromatic compound and independently of each other, hydrogen or a hydroxyl group).
4. The composition of claim 1, wherein the composition comprises from 5 to 30% by weight of the polymer and from 70 to 95% by weight of the solvent in the total weight of the composition.
The composition of claim 1, further comprising at least one of a crosslinking agent, a catalyst, or a surfactant.