KR20180109296A - Composition for hard mask - Google Patents

Abstract

A composition for a hard mask of the present invention comprises a carbazole unit, a biphenyl unit, and a polycondensate comprising a linker unit derived from at least one of formaldehyde or a synthetic equivalent thereof, or a compound represented by chemical formula 3, and a solvent. The hard mask having improved etching resistance, solubility and flatness at the same time can be formed from the composition for the hard mask.

Description

COMPOSITION FOR HARD MASK [0001]

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.

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 and having a uniform profile.

1. carbazole units; Biphenyl units; And a linker unit derived from at least one of formaldehyde or a synthetic equivalent thereof, or a compound represented by the following formula (3); And a solvent.

(3)

(Wherein R ₂ is an aromatic hydrocarbon having 6 to 20 carbon atoms, and R ₃ and R ₄ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms).

2. The hardmask composition according to 1 above, wherein the carbazole unit is represented by the following formula (1):

[Chemical Formula 1]

Wherein R ₁ is hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms (Aryl).

3. The composition for a hard mask according to 2 above, wherein R < _{1 >} is an ethyl group, a vinyl group or a phenyl group.

4. The composition of claim 1, wherein the biphenyl unit is derived from biphenylol or biphenyldiol.

5. The hard mask composition according to 4 above, wherein said biphenyl unit comprises at least one of structures represented by the following formulas (2-1) to (2-3):

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

6. The composition for a hard mask according to 1 above, wherein the compound represented by the general formula (3) comprises dibenzyl alcohol.

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

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 the embodiments of the present invention, it is possible to form a hard mask having excellent flatness, solubility, etch resistance and heat resistance at the same time.

The composition for a hard mask according to embodiments of the present invention may include a polycondensate formed by using carbazole-based compounds and biphenylol-based compounds. It is possible to improve the mechanical strength such as the etching resistance of the hard mask from the carbazole-based compound having a high carbon content and to ensure the solubility of the polycondensate and the coating property of the composition from the biphenylol-based compound.

Further, by further using a dibenzyl-based compound and / or a formaldehyde-based compound as the linker compound for the formation of the polycondensate, coating properties such as flatness and gap-fill characteristics of the hard mask are further improved .

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

Using the composition for a hard mask according to the embodiments of the present invention, for example, a hard mask film which is applied between a photoresist layer and a film to be etched and utilized as a resist under film can be formed. 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. The embodiments described below are preferred examples, and the spirit and scope of the present invention are not necessarily limited thereto.

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

Polycondensation

According to embodiments of the present invention, the composition for a hard mask may include a polycondensate in which a carbazole unit and a biphenyl unit are directly or indirectly bonded to each other.

The carbazole unit may be represented by the following formula (1).

[Chemical Formula 1]

In the formula (1), R ₁ may be a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms (Aryl).

The carbazole unit may be included as a functional unit imparting mechanical strength and chemical resistance of the polycondensate. Since the carbazole compound has a high carbon content (C%), the etch resistance and heat resistance of the polycondensate can be improved.

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

R ₁ can be selected in consideration of the mechanical properties (for example, etching resistance, heat resistance, etc.) and solubility of the polycondensate. In some preferred embodiments, R < ₁ > may be selected from an ethyl group, a vinyl group or a phenyl group.

For example, when R < ₁ > is a vinyl group, the hardness and etching resistance of the polycondensate can be further improved owing to the polymerization functionality of the vinyl group without impairing solubility. When R _{1 in the general} formula (1) includes an aryl group, the etch resistance and heat resistance of the polycondensate can be further improved by increasing the carbon content, and solubility and coating properties are complemented by the biphenyl unit and linker unit described later .

The biphenyl unit may be derived from a biphenyl-based compound. For example, the biphenol-based compound may include biphenylol or biphenyldiol.

 Thus, the condensation reaction by the nucleophilic substitution reaction with the carbazole compound or the linker compound described later can be promoted.

In exemplary embodiments, the biphenyl unit may include at least one of the structures represented by the following formulas (2-1), (2-2), and (2-3).

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

As the hydroxyl group is included in the biphenyl unit, the adhesion between the hard mask and the object and the wettability can be improved.

Further, in the case of the biphenylol-based compound, flexibility of the polycondensation can be improved since two benzene rings can rotate around a carbon-carbon (-C-C-) single bond. Therefore, the flatness and leveling characteristics of the composition for a hard mask can be further improved.

The biphenyl unit may be included as a functional unit for improving the solubility and coating properties of the polycondensate. For example, the biphenyl unit contains two benzene rings, and therefore may be advantageous in terms of etchability compared to, for example, phenol. Further, since the two benzene rings are connected by a single bond rather than a fused structure, flexibility and coating properties of the polycondensate can be improved.

Therefore, as the solubility is supplemented by the biphenyl unit, while maintaining increased etchability by the above-described carbazole unit, it is possible to form a hard mask having improved mechanical properties and film forming properties together.

The polycondensate may further include a linker unit together with the above-described carbazole unit and biphenyl unit. According to exemplary embodiments, the linker unit may be derived from at least one linker compound of formaldehyde (or a synthetic equivalent thereof) or a compound represented by the following formula (3).

(3)

In the general formula (3), R ₂ may be an aromatic hydrocarbon having 6 to 20 carbon atoms. R ₃ and R ₄ may each independently be hydrogen or an alkyl group having 1 to 4 carbon atoms.

In one embodiment, R ₂ may be a benzene ring having 6 carbon atoms so as not to lower the solubility of the polycondensate. In this case, the linker compound may include a dibenzyl-based compound. Also, in one embodiment, R ₃ and R ₄ may be hydrogen to facilitate the condensation reaction through nucleophilic substitution of the linker compound.

In this case, the linker compound may include dibenzyl alcohol.

The linker unit may be included together with the biphenyl unit as an auxiliary unit for supplementing the solubility of the polycondensate.

For example, in the case of formaldehyde or its synthetic equivalent, it can be included as an extension unit to add a methylene chain between the units of the polycondensate. Therefore, the present invention can be utilized as a unit for improving flexibility and coating properties without significantly lowering the etch resistance of the polycondensate. An example of the formaldehyde synthetic equivalent is paraformaldehyde.

For example, when formaldehyde is used as the linker compound, the polycondensate may include a repeating structure represented by the following formula (4).

[Chemical Formula 4]

For example, when the compound of formula (3) is used as the linker compound, the polycondensate may include a repeating structure represented by the following formula (5) or (6).

[Chemical Formula 5]

[Chemical Formula 6]

In the general formulas 4 to 6, Ar ₁ and Ar ₂ represent the carbazole unit and the biphenyl unit, respectively.

p, q, and s each independently may be an integer of 1 to 200.

The structures represented by the formulas (4) to (6) are merely illustrative, and the arrangement order of the carbazole unit, the biphenyl unit and the linker unit may be variously changed, and the structures represented by the formulas (4) to It is possible.

In some embodiments, the polycondensate may be prepared using only the carbazole compounds, biphenyl-based compounds, and linker compounds described above, and other aromatic compounds or linker compounds may not be used in the preparation of the polycondensate have. Therefore, it is possible to prevent the flatness, the etch resistance, and the solubility degradation due to the addition of other compounds and ensure desired properties.

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 composition for a hard mask.

In one embodiment, the weight average molecular weight of the polymer may be in the range of, for example, about 1,000 to 10,000, and desirable heat resistance, etch resistance, solubility, and flatness can be secured within the above range.

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 4.0 . Within the above range, desirable heat resistance, etching resistance, solubility and flatness can be secured at the same time.

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 polycondensate with each other, and can react with, for example, a hydroxyl group contained in the polycondensation product. 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 (meth) acrylate represented by the following general formula (8), 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 (9) and the melamine-based compound represented by the general formula (10) can also be used as the crosslinking agent.

(7)

[Chemical Formula 8]

[Chemical Formula 9]

[Chemical formula 10]

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.

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 polycondensate monomer compound) was used as an acid catalyst in the formation of the polycondensate (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-3 10 B-1 88 C-1 One D-1 One - - Example 8 A-4 10 B-1 89 - - - - E-1 One Comparative Example 1 A'-1 10 B-1 90 - - - - - - Comparative Example 2 A'-2 10 B-1 90 - - - - - - Comparative Example 3 A'-3 10 B-1 90 - - - - - -

,

,

(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3150)A-1:

,

,

(Weight-average molecular weight: 3150) produced by the condensation reaction of ethylene (1: 1: 2 molar ratio)

,

, 포름알데히드(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2750)A-2:

,

, A formaldehyde (1: 1: 2 molar ratio) condensation reaction (weight average molecular weight: 2750)

,

,

(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3050)A-3:

,

,

(Weight-average molecular weight: 3050) produced by the condensation reaction of ethylene (1: 1: 2 molar ratio)

,

,

(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3250)A-4:

,

,

(Weight average molecular weight: 3250) produced by the condensation reaction of propylene glycol (1: 1: 2 molar ratio)

,

,

(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3165)A-5:

,

,

(Weight-average molecular weight: 3165) produced by the condensation reaction of ethylene glycol (1: 1: 2 molar ratio)

,

,

(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 4450)A-6:

,

,

(Weight average molecular weight: 4450) produced by the condensation reaction of ethylene (1: 1: 2 molar ratio)

,

,

(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3425)A'-1:

,

,

(Weight average molecular weight: 3425) produced by a condensation reaction at a molar ratio (1: 1: 2 molar ratio)

,

,

(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3150)A'-2:

,

,

(Weight-average molecular weight: 3150) produced by the condensation reaction of ethylene (1: 1: 2 molar ratio)

,

,

(1:1:2 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3175)A'-3:

,

,

(Weight-average molecular weight: 3175) produced by the condensation reaction of ethylene glycol (1: 1: 2 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 shown in Table 1 were evaluated by the following evaluation method. 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 DEG C for 60 seconds to form a film having a thickness of 1500 ANGSTROM. Each of the formed films was coated with ArF photoresist, baked at 110 ° C for 60 seconds, exposed using ASML (XT: 1450G, NA 0.93) exposure equipment, and developed with TMAH (2.38 wt% aqueous solution) A line-and-space pattern of 60 nm was obtained.

The patterned specimens obtained, and further cured at 110 ℃ 60 seconds, and the test piece using a CHF ₃ / CF ₄ gas mixture proceeds dry etching 20 seconds, respectively, and by observing the cross section by FE-SEM, respectively to measure the etching rate The etch resistance to the halogen plasma was evaluated.

≪ 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 according to the examples and comparative examples in Table 1 were spin-coated after drying to a thickness of 5 탆, dried at 100 캜 in a hot-air drier for 3 minutes, and then visually inspected. The solubility of the polymer was evaluated through the uniformity of the coating film.

≪ Determination of solubility &

◎: Unevenness of coating surface is not confirmed when observed with a microscope.

○: Unevenness of coating surface is not visually confirmed.

?: Local irregularity was visually confirmed.

×: Unevenness on the front surface was visually confirmed.

(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

DELTA: Thickness difference 150 to 200 nm

X: Thickness difference exceeding 200 nm

division Etchability Solubility Flatness Example 1 ○ ○ ○ Example 2 ○ ○ ○ Example 3 ○ ◎ ○ Example 4 ◎ △ △ Example 5 ○ ◎ ○ Example 6 ◎ ◎ ○ Example 7 ○ ◎ ○ Example 8 ○ ◎ ○ Comparative Example 1 ◎ △ X Comparative Example 2 △ ○ ○ Comparative Example 3 ◎ △ X

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

In Example 4, excellent etchability was ensured as the substituent of the carbazole compound included a phenyl group, but the solubility and flatness were somewhat lowered. On the other hand, in Example 8, the solubility and flatness were improved as the surfactant was included in Example 4.

In Example 5, the dihydroxybiphenyl compound was included, and the solubility was improved as compared with Example 1.

In the case of Example 6, as the substituent of the carbazole compound contained a vinyl group, the etching resistance and the solubility were both improved.

In the case of Comparative Example 1, the use of naphthol was used instead of biphenyl, and the solubility and flatness were remarkably deteriorated. In the case of Comparative Example 2, the etching resistance was decreased due to the use of phenol instead of biphenyl. In the case of Comparative Example 3, solubility and flatness remarkably deteriorated as benzaldehyde was used instead of the linker compound used in the Examples.

Claims (8)

Carbazole units; Biphenyl units; And a linker unit derived from at least one of formaldehyde or a synthetic equivalent thereof, or a compound represented by the following formula (3); And
A composition for a hard mask, comprising:
(3)

(Wherein R ₂ is an aromatic hydrocarbon having 6 to 20 carbon atoms, and R ₃ and R ₄ are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms).
The hardmask composition according to claim 1, wherein the carbazole unit is represented by the following formula (1):
[Chemical Formula 1]

(Wherein R ₁ is hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 30 carbon atoms (Aryl)).
The composition for a hard mask according to claim 2, wherein R ₁ is an ethyl group, a vinyl group or a phenyl group.
The composition of claim 1, wherein the biphenyl unit is derived from biphenylol or biphenyldiol.
The composition for a hard mask according to claim 4, wherein the biphenyl unit comprises at least one of structures represented by the following formulas (2-1) to (2-3):
[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

The composition for a hard mask according to claim 1, wherein the compound represented by Formula 3 comprises dibenzyl alcohol.
The method according to claim 1,
5 to 30% by weight of the polycondensate in the total weight of the composition, and 70 to 95% by weight of the solvent.
The composition of claim 1, further comprising at least one of a crosslinking agent, a catalyst, or a surfactant.