KR102349966B1 - Composition for hard mask - Google Patents

Abstract

The present invention provides a composition for a hard mask, comprising a solvent and a polymer of a compound having a specific structure including an ether group. A hard mask having improved etch resistance, solubility, and flatness can be formed from the composition for a hard mask.

Description

Composition for hard mask {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, wirings, and insulating patterns is continuously improved. Accordingly, a photolithography process for fine patterning of the structures is being developed together.

In general, a photoresist layer is formed by coating a photoresist on an etch target layer, and a photoresist pattern is formed through exposure and development processes. Then, a predetermined pattern may be formed by partially removing the etch target layer using the photoresist pattern as an etch mask. After image transfer to the etch target layer is performed, the photoresist pattern may be removed through an ashing and/or strip process.

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

Accordingly, a resist lower layer may be added between the target layer to be etched and the photoresist layer in order to secure the etch resistance and etch selectivity of the photoresist for forming a desired pattern.

The resist underlayer has, for example, sufficient etch resistance (or etch resistance) and heat resistance to a high-temperature etching process, and also satisfies the characteristics for being formed to a uniform thickness by, for example, a spin-on coating process. desirable.

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

Korean Patent Publication No. 10-2010-0082844

One 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 composition for a hard mask comprising a solvent:

[Formula 1]

(In Formula 1, Ar ₃ is an arylene group having 6 to 35 carbon atoms, and may be further substituted with a hydroxyl group (-OH),

Ar ₁ , Ar ₂ are each independently an aryl group having 6 to 20 carbon atoms,

Wherein R ₁ and R ₂ are each independently an aryl group having 6 to 20 carbon atoms when both _{Ar 1} and Ar _{2 are phenylene, and when Ar 1} or Ar ₂ is not phenylene, each independently hydrogen , or an aryl group having 6 to 20 carbon atoms, and n is an integer of 1 to 200).

2. The composition for a hard mask according to the above 1, wherein the polymer is a polymer of an aromatic compound having 6 to 35 carbon atoms and a compound of Formula 1 below:

[Formula 2]

(In Formula 2, Ar ₁ , Ar ₂ are each independently an aryl group having 6 to 20 carbon atoms,

R ₁ , R ₂ are each independently an aryl group having 6 to 20 carbon atoms when both _{Ar 1} and Ar _{2 are phenylene, and when Ar 1} or Ar ₂ is not phenylene, each independently hydrogen or a C 6 to C 20 aryl group aryl group).

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

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

4. The composition for a hard mask according to 1 above, wherein Ar ₃ is derived from an aromatic compound composed of at least one compound selected from the group consisting of the following Chemical Formulas 3-1 to 3-6:

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

[Formula 3-4]

[Formula 3-5]

[Formula 3-6]

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

5. The composition for a hard mask according to 1 above, comprising 5 to 30% by weight of the polymer and 70 to 95% by weight of the solvent based on the total weight of the composition

6. The composition for a 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, a hard mask having excellent etch resistance and improved film-forming properties such as solubility and coating property may be formed.

The composition for a hard mask according to embodiments of the present invention may include the polymer of Formula 1. By _{improving the etch resistance from Ar 3} , the mechanical properties of the hard mask may be remarkably improved.

In addition, since the flexibility of the polymer is increased by the rotational properties of the ether group, it is possible to improve film formation properties such as coatability and uniformity of the hard mask.

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

Embodiments of the present invention include a polymer of a compound having a specific structure including an ether group, and thus provide a composition for a hard mask having excellent solubility and flatness while also having etch resistance.

Using the hardmask composition, for example, a hardmask film used as a resist lower film may be formed by being applied between the photoresist layer and the etch target film. The hard mask layer 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 hardmask layer or hardmask may be used as, for example, a spin-on hardmask (SOH).

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

As used herein, the term "aromatic" or "aromatic compound" is used to encompass not only a compound in which the entire compound satisfies the aromaticity, but also a compound in which some structures or groups of the compound satisfy the aromaticity.

As used herein, the term “carbon content” may mean a ratio of the number of carbon masses to the total number of masses per molecule of a compound.

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

polymer

According to embodiments of the present invention, the polymer may include a repeating unit represented by the following formula (1).

[Formula 1]

In Formula 1, Ar ₃ may be an arylene group having 6 to 35 carbon atoms, and may be further substituted with a hydroxyl group (-OH).

The Ar ₁ , Ar ₂ may each independently be an aryl group having 6 to 20 carbon atoms.

Wherein R ₁ and R ₂ may be each independently an aryl group having 6 to 20 carbon atoms when _{Ar 1} and Ar _{2 are phenylene.} When Ar ₁ or Ar ₂ is not phenylene, R ₁ and R ₂ may each independently be hydrogen or an aryl group having 6 to 20 carbon atoms.

For example, n may be an integer from 1 to 200.

The composition for a hard mask according to embodiments of the present invention may include the polymer including the repeating unit, thereby improving solubility and flatness of the hard mask and at the same time having etch resistance.

For example, R ₁ and R ₂ may each independently be an aryl group having 6 to 20 carbon atoms when _{Ar 1} and Ar _{2 are phenylene, and when Ar 1} or Ar ₂ is not phenylene, R ₁ and R ₂ may each independently be hydrogen or an aryl group having 6 to 20 carbon atoms.

In addition, since the polymer includes an ether group in the main chain, flexibility may be improved due to the rotational characteristics of the ether group, and thus film forming properties such as coatability and uniformity of the hard mask may be improved.

According to some embodiments, the polymer may include a polymer of an aromatic compound having 6 to 35 carbon atoms and a compound of Formula 1 below.

[Formula 2]

In Formula 2, Ar ₁ and Ar ₂ may each independently be an aryl group having 6 to 20 carbon atoms.

Wherein R ₁ , R ₂ may be each independently an aryl group having 6 to 20 carbon atoms when _{Ar 1} and Ar _{2 are phenylene, and when Ar 1} or Ar ₂ is not phenylene, each independently hydrogen or 6 carbon atoms to 20 aryl groups.

The compound of Formula 2 may improve the yield and reaction rate of a polymerization reaction using an acid catalyst by including a hydroxyl group at the terminal thereof.

In a preferred embodiment, the compound of Formula 2 may include at least one selected from the group consisting of compounds of Formulas 2-1 to 2-3 below.

[Formula 2-1]

[Formula 2-2]

[Formula 2-3]

In one embodiment, Ar ₃ in Formula 1 may be derived from an aromatic compound composed of at least one compound selected from the group consisting of Formulas 3-1 to 3-6 below.

[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

[Formula 3-4]

[Formula 3-5]

[Formula 3-6]

In Formulas 3-1 to 3-6, R ₃ may be one or plural in the aromatic compound, and may each independently be hydrogen or a hydroxyl group.

_{As Ar 3} derived from the aromatic compound having a high carbon content is included in the polymer, the etch resistance of the hard mask may be improved.

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 preparing the polymer. Accordingly, it is possible to prevent deterioration of etch resistance, solubility, and flatness due to the addition of other compounds, and to secure desired physical properties.

However, in one embodiment, the bonding of other linkers or main chain units may be included within a range that does not impair the effect through the combination of the aromatic compound having 6 to 35 carbon atoms and the compound of Formula 2, and the practice of the present invention Examples do not necessarily rule out this.

In preparing the polymer, the aromatic compound having 6 to 35 carbon atoms and the compound of Formula 1 may be used, for example, in a molar ratio of about 1:0.5 to 1:1.5, but is not necessarily limited thereto.

In one embodiment, the polydispersity index (PDI, Polydispersity index) [weight average molecular weight (Mw) / number average molecular weight (Mn)] of the polymer may be about 1.5 to 6.0, preferably about 1.5 to 3.0 days can In the above range, film forming properties such as coatability and flatness may be improved together with desirable solubility and etch resistance.

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, and in one embodiment, about 10 to 20% by weight.

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 polycondensate described above. 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 the remaining amount excluding the polycondensate and additional agents to be described later. For example, the solvent may be included in an amount of about 70 to 95% by weight of the total weight of the composition for a hard mask.

additional formulation

Optionally, the composition for a hard mask according to embodiments of the present invention may further include an additional agent such as a crosslinking agent, a catalyst, and a surfactant.

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

Examples of the crosslinking agent include melamine, an amino resin, a glycoluryl compound, or a bisepoxy compound.

The crosslinking agent is, for example, an etherified amino resin, such as a methylated or butylated melamine (specifically N-methoxymethyl-melamine or N-butoxymethyl-melamine) and a methylated or butylated melamine urea resin (specific example, Cymel U-65 Resin or UFR 80 Resin), glycoluryl derivative (see Formula 6, specific example, Powderlink 1174), bis (hydroxymethyl)-p represented by Formula 7 -cresol compounds and the like may be included. In addition, a bisepoxy-based compound represented by the following Chemical Formula 8 and a melamine-based compound represented by the following Chemical Formula 9 may also be used as a crosslinking agent.

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

An acid catalyst or a basic catalyst may be used as the catalyst.

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

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.

When the crosslinking agent is included, the content of the crosslinking 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, and more preferably about 0.1 to 1 part by weight based on 100 parts by weight of the polycondensate. can

Within the content range of the crosslinking agent and the catalyst, appropriate crosslinking properties may be obtained without deteriorating etch resistance, heat resistance, solubility, and flatness of the polycondensate.

The composition for a hard mask according to embodiments of the present invention may further include a surfactant to improve surface properties and adhesion of the hard mask. The surfactant may include, but is not limited to, alkylbenzenesulfonate, alkylpyridinium salt, polyethylene glycol, quaternary ammonium salt, and the like. 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 pattern forming method using the hard mask composition.

According to exemplary embodiments, an etch target layer may be formed on a substrate, and the hard mask composition may be coated and cured on the etch target layer to form a hard mask. A photoresist layer may be formed on the hard mask, and a photoresist pattern may be formed by selectively exposing and developing the photoresist layer. A hard mask pattern may be formed by selectively etching the hard mask using the photoresist pattern.

Thereafter, by selectively removing the etch target layer using the photoresist pattern and the hard mask pattern together as an etch mask, a predetermined target pattern may be formed.

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

Hereinafter, experimental examples including specific examples and comparative examples are presented to help the understanding of the present invention, but these are merely illustrative of the present invention and do not limit the appended claims, the scope and description of the present invention It is obvious to those skilled in the art that various changes and modifications to the embodiments are possible within the scope of the spirit, and it is natural that such variations and modifications fall within the scope of the appended claims.

Examples and Comparative Examples

A composition for a hard mask of the composition and content (% by weight) described in Table 1 was prepared. In Examples and Comparative Examples, paratoluenesulfonic acid (5 mol% relative to the hydroxyl group-containing aromatic compound) was used as an acid catalyst when forming the polymer (A).

division Polycondensate (A) Solvent (B) Crosslinking agent (C) 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-2 10 B-1 88 C-1 One D-1 One - - Example 7 A-2 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 - - - - - - Comparative Example 4 A'-4 10 B-1 90 - - - - - - Comparative Example 5 A'-5 10 B-1 90 - - - - - -

,

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

,

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

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2800)A-2:

,

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

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 3100)A-3:

,

(1:1 molar ratio) of the copolymer produced by the condensation reaction (weight average molecular weight: 3100)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 4800)A-4:

,

(1:1 molar ratio) of the copolymer produced by the condensation reaction (weight average molecular weight: 4800)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2600)A-5:

,

(1:1 molar ratio) of the copolymer produced by the condensation reaction (weight average molecular weight: 2600)

,

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

,

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

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2400)A'-2:

,

(1:1 molar ratio) of the copolymer produced by the condensation reaction (weight average molecular weight: 2400)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2900)A'-3:

,

(1:1 molar ratio) of the copolymer produced by the condensation reaction (weight average molecular weight: 2900)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 4500) A'-4:

,

(1:1 molar ratio) of the copolymer produced by the condensation reaction (weight average molecular weight: 4500)

,

(1:1 몰비율)의 축합반응으로 생성된 공중합체(중량평균분자량: 2800)A'-5:

,

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

B: PGMEA

C: N-methoxymethyl-melamine resin

D: p-toluene sulfonic acid-pyridine salt

E: triethylene glycol

Experimental example

Etching resistance, solubility, and flatness of the hard mask layer or hard mask formed of the compositions of Table 1 were evaluated through an evaluation method to be described later. The evaluation results are shown in Table 2 below.

(1) Evaluation of etch resistance

The compositions according to Examples and Comparative Examples were coated on a silicon wafer by spin-coating, respectively, and baked at 200° C. for 60 seconds to form a hard mask layer having a thickness of 1500 Å. A photoresist for ArF is coated on each hard mask layer formed, and after baking at 110°C for 60 seconds, exposure is performed using ASML (XT:1450G, NA 0.93) exposure equipment, and then each is exposed with TMAH (2.38wt% aqueous solution). After development, a line-and-space pattern of 60 nm was obtained.

The photoresist pattern is further cured at 110° C. for 60 seconds, and _{dry etching is performed on the hard mask layer for 20 seconds using the photoresist pattern and CHF 3} /CF ₄ mixed gas, respectively, and the cross section is cut with FE-SEM. Each was observed to measure the etching rate to determine the etch resistance to halogen plasma.

<Determination of etch resistance>

◎: Etching rate less than 10Å/Sec

○: Etching rate 10Å/Sec or more and less than 11Å/Sec

△: Etching rate 11Å/Sec or more and less than 12Å/Sec

×: Etching rate 12Å/Sec or more

(2) solubility

After stirring the compositions of Examples and Comparative Examples at 50° C. for 1 hour, 1) confirming the dissolved state of the polymer in a warm state (50° C.), cooling to room temperature, 2) at room temperature (25° C.) The dissolved state of the polymer was confirmed, and the mixture was further stirred at room temperature for 6 hours, and 3) the dissolved state of the polymer at room temperature was reconfirmed (25° C.), and solubility was measured.

<Solubility determination>

(double-circle): Undissolved polymer was not visually confirmed in the state left at room temperature.

○: Undissolved polymer was not visually confirmed at room temperature, but a small amount of undissolved polymer was visually confirmed when left at room temperature.

△: Undissolved polymer was not visually confirmed in a warm state, but undissolved polymer was visually confirmed in a room temperature state.

x: A small amount of undissolved 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 including a trench having a width of 10 μm and a depth of 0.50 μm) and dried to form a hard mask film, and the thickness difference between the trench portion and the non-trench portion was measured using a scanning electron microscope. (SEM) was observed to evaluate the flatness.

<Flatness judgment>

◎: thickness difference less than 150 nm

○: thickness difference 150 to 175 nm

Δ: thickness difference 175 to 200 nm

×: thickness difference greater than 200 nm

division etch resistance solubility flatness Example 1 ◎ ○ ○ Example 2 ◎ ◎ ◎ Example 3 ◎ ◎ ◎ Example 4 ○ ◎ ◎ Example 5 ◎ ◎ ◎ Example 6 ◎ ◎ ◎ Example 7 ◎ ◎ ◎ Comparative Example 1 △ ○ ○ Comparative Example 2 ◎ △ △ Comparative Example 3 ◎ △ △ Comparative Example 4 △ ◎ ◎ Comparative Example 5 ○ △ △

Referring to Table 2, in the case of a hard mask using an aromatic compound and a compound represented by a specific chemical formula according to embodiments of the present invention, etch resistance, solubility, and flatness were improved in a balanced overall manner.

On the other hand, in the case of Comparative Example 1 in which A'-1 was used, solubility and flatness were increased by including an ether group, but the etch resistance was excessively decreased due to a small carbon content.

In Comparative Examples 2 and 3 in which A'-2 and A'-3 were used, etch resistance was improved due to an increase in carbon content, but solubility and flatness were rapidly deteriorated.

In the case of Comparative Example 4 in which A'-4 was used, solubility and flatness were increased, but etch resistance was greatly reduced due to a low carbon content.

In Comparative Example 5 in which A'-5 was used, etch resistance was improved due to an increase in carbon content, but solubility and flatness were excessively decreased.

Claims (6)

A polymer comprising a repeating unit represented by the following formula (1); and
A composition for a hard mask comprising a solvent:
[Formula 1]

(In Formula 1, Ar ₃ is an arylene group having 6 to 35 carbon atoms, and may be further substituted with a hydroxyl group (-OH),
Ar ₁ , Ar ₂ are each independently an aryl group having 10 to 20 carbon atoms and having at least two aromatic rings,
wherein R ₁ , R ₂ are hydrogen, and n is an integer of 1 to 200).
The composition for a hard mask according to claim 1, wherein the polymer is a polymer of an aromatic compound having 6 to 35 carbon atoms and a compound of Formula 2 below:
[Formula 2]

(In Formula 2, Ar ₁ , Ar ₂ are each independently an aryl group having 10 to 20 carbon atoms and having at least two aromatic rings;
R ₁ , R ₂ are hydrogen).
The composition for a hard mask according to claim 2, wherein the compound of Formula 2 includes at least one selected from the group consisting of compounds of Formula 2-2 and Formula 2-3:
[Formula 2-2]

[Formula 2-3]

The composition for a hard mask according to claim 1, wherein Ar ₃ is derived from an aromatic compound composed of at least one compound selected from the group consisting of the following Chemical Formulas 3-1 to 3-6:
[Formula 3-1]

[Formula 3-2]

[Formula 3-3]

[Formula 3-4]

[Formula 3-5]

[Formula 3-6]

(In Formulas 3-1 to 3-6, R ₃ may be one or plural in the aromatic compound, and each independently represent hydrogen or a hydroxyl group).
The composition for a hard mask according to claim 1, comprising 5 to 30% by weight of the polymer and 70 to 95% by weight of the solvent based on the total weight of the composition.
The composition for a hard mask according to claim 1, further comprising at least one of a crosslinking agent, a catalyst, and a surfactant.