KR20190083753A - Composition for hard mask - Google Patents

Abstract

The present invention relates to a composition for a hard mask, comprising a polymer of a compound having a specific structure, and a solvent. A hard mask having improved etching resistance, solubility, and surface smothness is formed from the composition from the hard mask.

Description

COMPOSITION FOR HARD MASK [0001]

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

For example, in the fields of semiconductor fabrication, microelectronics and the like, as the degree of integration of structures such as circuits, wirings, insulating patterns and the like is continuously improved, photolithography process technology for fine patterning of the structures is also developing.

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, since the etching for the ARC layer is added, the consumption amount or the etching amount of the photoresist layer or the photoresist pattern can be increased. Further, when the thickness of the film to be etched increases or the etching amount necessary for forming a desired pattern increases, sufficient etching resistance of the photoresist layer or the photoresist pattern may not be ensured.

Therefore, a resist under film, that is, a hard mask, may be added between the etch target film and the photoresist layer in order to secure the etching resistance and etching selectivity of the photoresist for forming a desired pattern.

The resist undercoat film has sufficient etch resistance (or etching resistance) and heat resistance for a high-temperature etching process, and also has properties for forming a uniform thickness by, for example, a spin-on coating process, Solubility, flatness, and the like.

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

Korean Patent Publication No. 10-2010-0082844

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 polymer comprising a repeating unit represented by the following formula (1); And a solvent.

[Chemical Formula 1]

(Wherein Ar ₁ and Ar ₃ are each independently an aryl group having 6 to 40 carbon atoms, Ar ₂ and Ar ₄ are each independently an arylene group having 6 to 40 carbon atoms, and n is an integer of 1 to 200).

2. The hard mask composition according to 1 above, wherein the repeating unit comprises a linker unit derived from a linker compound bonded to -Ar ₄ - and represented by the following formula (2):

(2)

(Wherein Ar ₁ and Ar ₃ are each independently an aryl group having 6 to 40 carbon atoms and Ar ₂ is an arylene group having 6 to 40 carbon atoms).

3. The hard mask composition according to 2 above, wherein the linker compound comprises at least one selected from the group consisting of compounds represented by the following formulas (2-1) to (2-4):

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

4. The composition for hard mask according to item 1 above, wherein Ar ₄ is an arylene group containing at least one hydroxyl group (-OH).

5. The hard mask composition according to item ₄ above, wherein Ar ₄ is derived from a hydroxyl group-containing aromatic compound.

6. The composition for a hard mask according to 5 above, wherein the hydroxyl group-containing aromatic compound comprises at least one selected from the group consisting of compounds represented by the following formulas (3-1), (3-2) and (3-3)

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

7. 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.

8. 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 embodiments of the present invention may comprise a polymer that is condensed with a linker compound containing an aromatic compound and an arylene group. The etching resistance from the linker compound is improved in addition to the etching resistance basically ensured from the aromatic compound, whereby the mechanical properties of the hard mask can be remarkably improved.

In addition, by using a compound selected in consideration of solubility and flatness as the linker compound, it is possible to improve film forming properties at the same time.

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 that includes a polymer containing a linker unit containing an arylene group having a specific structure, thereby significantly improving solubility and flatness.

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.

polymer

According to the embodiments of the present invention, the composition for a hard mask includes a polymer comprising a repeating unit represented by the following formula (1).

[Chemical Formula 1]

Ar ₁ and Ar ₃ may each independently be an aryl group having 6 to 40 carbon atoms, Ar ₂ and Ar ₄ may each independently be an arylene group having 6 to 40 carbon atoms, different. n is an integer from 1 to 200;

The composition for a hard mask according to the embodiments of the present invention includes a polymer containing a repeating unit represented by the above formula (1), thereby exhibiting excellent etching resistance and excellent film-forming properties such as solubility and flatness .

The repeating unit may include a linker unit derived from a linker compound represented by the following formula (2). That is, the moiety (excluding -Ar ₄ -) linked to -Ar ₄ - in the repeating unit is a linker unit.

(2)

In Formula 2, Ar ₁ and Ar ₃ may each independently be an aryl group having 6 to 40 carbon atoms, and Ar ₂ may be an arylene group having 6 to 40 carbon atoms.

In the case of the linker compound of Formula 2, the solubility and flatness of the hard mask can be improved through the structure including the arylene group. Further, through the structure including one aryl group at both ends, the etching resistance of the hard mask can be improved without impairing solubility and flatness of the hard mask.

In a preferred embodiment, the linker compound may include at least one of the compounds represented by the following formulas (2-1), (2-2), (2-3), and (2-4).

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

According to exemplary embodiments, Ar ₄ of Formula 1 may include at least one hydroxyl group (-OH). By including a hydroxy group, solubility in a solvent, adhesion to a substrate, and reactivity with the above-mentioned linker compound can be improved.

The Ar ₄ may be derived from a hydroxyl group-containing aromatic compound. For example, as the above aromatic compounds containing a hydroxyl group, compounds of the following formula 3-1, formula 3-2, or formula 3-3 can be mentioned. These may be used alone or in combination of two or more.

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

In some embodiments, the polymer may be prepared using only the hydroxyl group-containing aromatic compound and the linker compound of Formula 2, and other aromatic compounds or linker compounds may not be used in the preparation of the polymer have. Accordingly, the etching resistance, solubility, and flatness are not deteriorated due to the addition of other compounds, and desired physical properties can be secured.

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 through the above-mentioned combination of the hydroxyl group-containing aromatic compound and the linker compound of Formula 2, Examples do not necessarily exclude it.

In the preparation of the polymer, the hydroxyl group-containing aromatic compound and the linker compound of Formula 2 may be used in a molar ratio of, for example, about 1: 0.5 to 1: 1.5, but are not limited thereto.

As indicated by formula (1), the length of the polymer can be extended while repeating the repeating structure. However, the formula (1) indicates that the above-mentioned units are included together, and does not necessarily define the bonding sequence 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.

menstruum

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.

Additional 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, 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. 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.

Then, 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.

Examples 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).

division The polycondensation product (A) Solvent (B) The crosslinking agent (C) The catalyst (D) Surfactants
(E) ingredient content ingredient content ingredient content ingredient content ingredient content Example 1 A-1 10 B-1 90 - - - - - - Example 2 A-2 10 B-1 90 - - - - - - Example 3 A-3 10 B-1 90 - - - - - - Example 4 A-4 10 B-1 90 - - - - - - Example 5 A-5 10 B-1 90 - - - - - - Example 6 A-6 10 B-1 90 - - - - - - Example 7 A-7 10 B-1 90 - - - - - - Example 8 A-8 10 B-1 90 - - - - - - Example 9 A-9 10 B-1 90 - - - - - - Example 10 A-10 10 B-1 90 - - - - - - Example 11 A-11 10 B-1 90 - - - - - - Example 12 A-12 10 B-1 90 - - - - - - Example 13 A-1 10 B-1 88 C-1 One D-1 One - - Example 14 A-1 10 B-1 89 - - - - E-1 One Comparative Example 1 A'-1 10 B-1 90 - - - - - - Comparative Example 2 A'-2 10 B-1 88 - - - - - - Comparative Example 3 A'-3 10 B-1 89 - - - - - -

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3500)A-1:

,

(Weight-average molecular weight: 3500) produced by the condensation reaction of ethylene (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3200)A-2:

,

(Weight-average molecular weight: 3200) produced by the condensation reaction of ethylene (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3300)A-3:

,

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

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2500)A-4:

,

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

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 5300)A-5:

,

(Weight-average molecular weight: 5,300) produced by the condensation reaction of ethylene (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 4700) A-6:

,

(Weight-average molecular weight: 4,700) produced by the condensation reaction of ethylene (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 4500)A-7:

,

(Weight-average molecular weight: 4,500) produced by a condensation reaction in a molar ratio (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3600) A-8:

,

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

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3200) A-9:

,

(Weight-average molecular weight: 3200) produced by the condensation reaction of ethylene (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2600)A-10:

,

(Weight-average molecular weight: 2600) produced by a condensation reaction of ethylene (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2800)A-11:

,

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

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2100)A-12:

,

(Weight-average molecular weight: 2100) produced by the condensation reaction of ethylene (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3800)A'-1:

,

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

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 4500)A'-2:

,

(Weight-average molecular weight: 4,500) produced by a condensation reaction in a molar ratio (1: 1 molar ratio)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 1700)A'-3:

,

(Weight-average molecular weight: 1,700) produced by the condensation reaction of ethylene (1: 1 molar ratio)

B: PGMEA

C: N-methoxymethyl-melamine resin

D: p-toluenesulfonic acid-pyridine salt

E: triethylene glycol

Experimental 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 later. The evaluation results are shown in Table 2 below.

(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 200 ° C for 60 seconds to form a 1500 Å thick hard mask layer. 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.

≪ Determination of etchability &

◎: Etching rate less than 10 A / sec

○: Etching rate 10 A / sec or more and less than 11 A / sec

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

×: etching rate of 12 A / sec or more

(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.

≪ Determination of solubility &

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

○: Under normal temperature condition, unharmed 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) 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.

≪ Flatness judgment &

?: Thickness difference less than 150 nm

?: Thickness difference of 150 nm or more and less than 175 nm

DELTA: Thickness difference of 175 nm or more and less than 200 nm

X: Thickness difference of 200 nm or more

division Etchability Solubility Flatness Example 1 ◎ ○ ○ Example 2 ◎ ○ ○ Example 3 ◎ ○ ○ Example 4 ◎ ○ ○ Example 5 ○ ◎ ◎ Example 6 ○ ◎ ◎ Example 7 ○ ◎ ◎ Example 8 ◎ ○ ○ Example 9 ○ ○ ○ Example 10 ◎ ○ ○ Example 11 ◎ ○ ○ Example 12 ◎ ◎ ◎ Example 13 ◎ ○ ○ Example 14 ◎ ○ ○ Comparative Example 1 △ ○ ○ Comparative Example 2 × ◎ ◎ Comparative Example 3 ○ △ △

Referring to Table 2, in the case of the hard mask using the linker compound and the aromatic compound according to the embodiments of the present invention, etchability, solubility, and flatness were improved in a balanced manner as a whole.

On the other hand, in the case of Comparative Example 1 and Comparative Example 2 in which p-xylylenediol was used, the solubility and flatness were good, but the etching resistance was lower than in the Examples.

In the case of Comparative Example 3 in which 1,4-phenylenebis (diphenylmethanol) was used, the etch resistance was increased, but the solubility and flatness were rapidly deteriorated.

Claims (8)

A polymer comprising a repeating unit represented by the following formula (1); And a solvent.
[Chemical Formula 1]

(Wherein Ar ₁ and Ar ₃ are each independently an aryl group having 6 to 40 carbon atoms, Ar ₂ and Ar ₄ are each independently an arylene group having 6 to 40 carbon atoms and are different from each other, and n is an integer of 1 to 200 ).
The hard mask composition according to claim 1, wherein the repeating unit comprises a linker unit derived from a linker compound bonded to -Ar ₄ - and represented by the following formula:
(2)

(Wherein Ar ₁ and Ar ₃ are each independently an aryl group having 6 to 40 carbon atoms and Ar ₂ is an arylene group having 6 to 40 carbon atoms).
The hard mask composition according to claim 2, wherein the linker compound comprises at least one selected from the group consisting of compounds represented by the following formulas (2-1) to (2-4):
[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

[Chemical Formula 2-4]

The composition for a hard mask according to claim 1, wherein Ar ₄ comprises at least one hydroxyl group (-OH).
5. The hard mask composition according to claim 4, wherein Ar ₄ is derived from a hydroxyl group-containing aromatic compound.
The composition for a hard mask according to claim 5, wherein the hydroxyl group-containing aromatic compound comprises at least one selected from the group consisting of compounds represented by the following Formulas (3-1), (3-2) and (3-3)
[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

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.