KR102276554B1 - Composition for hard mask - Google Patents

Abstract

The present invention relates to a composition for a hard mask, and more particularly, by including a compound and a solvent including a repeating unit represented by a specific chemical formula, having excellent etching resistance to halogen gas without deterioration of optical and mechanical properties A polymer for a resist underlayer film can be formed.

Description

Composition for hard mask {COMPOSITION FOR HARD MASK}

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

In the microelectronics industry and industries such as microscopic structures (eg, micromachines, magnetoresist heads, etc.), there is a continuing need to reduce the size of structural features. Also, in the microelectronics industry, there is a desire to reduce the size of microelectronic devices, thereby providing a greater amount of circuitry for a given chip size.

Effective lithographic techniques are essential to reduce feature size.

A typical lithographic process first applies a resist to the underlying material and then exposes it to radiation to form a layer of resist. The resist layer is then developed with a developer to form a patterned resist layer, and the material in the openings of the patterned resist layer is etched to transfer the pattern to the underlying material. After the transfer is complete, it involves the formation of a patterned resist layer by patternwise exposing the photosensitive resist. The image is then developed by contacting the exposed resist layer with an optional substance (typically an aqueous alkaline developer). The pattern is then transferred to the underlying material by etching that material within the openings of the patterned resist layer. After the transfer is complete, the remaining resist layer is removed.

In most of the lithographic processes, in order to minimize the reflectivity between the resist layer and the underlying material, an anti-reflective coating (ARC) is used to increase the resolution. However, in the process of etching the anti-reflective coating after patterning, the resist layer is also consumed a lot, which may require additional patterning during the subsequent etching step.

In other words, for some lithographic imaging processes, the resist used may not be sufficiently resistant to the etching step to be able to effectively transfer the desired pattern to the underlying material. Therefore, when an ultra-thin resist layer using an extremely thin resist material is required, when the substrate to be etched is thick, when a deep etching depth is required, or when it is necessary to use a specific etchant for a given underlying material etc., a resist underlayer film has been used.

The resist underlayer acts as an intermediate layer between the resist layer and an underlayer material that can be patterned by transfer from the patterned resist, the resist underlayer receiving the pattern from the patterned resist layer and transferring the pattern to the underlayer material. It must be able to withstand the etching process required to

Although many materials have been studied to form such an underlayer film, there is still a demand for an improved underlayer film composition.

Conventional materials for forming an underlayer film are difficult to apply to a substrate, so for example, chemical or physical vapor deposition, special solvents, or high-temperature firing are used, but these are expensive. Accordingly, recently, research on an underlayer film composition that can be applied by a spin-on coating technique without the need for high-temperature sintering has been conducted.

In addition, it can be selectively and easily etched by using the resist layer formed thereon as a mask, and at the same time, especially when the lower layer is a metal layer, it is resistant to the etching process required for patterning the lower layer using the underlayer film as a mask. Research is ongoing.

Korean Patent Application Laid-Open No. 10-2010-0082844 discloses a technology related to a composition for forming a resist underlayer 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 polymer for a resist underlayer film having excellent etching resistance to halogen gas without deterioration of optical and mechanical properties.

1. A composition for a hard mask comprising a compound and a solvent comprising a repeating unit represented by the following formula (1)

[Formula 1]

(Wherein, Ar is a C6 to C18 arenetriyl group (Arenetriyl),

R ₁ to R ₃ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 18 carbon atoms,

R ₄ is a single bond, an alkylene group having 1 to 6 carbon atoms, or an arylene group having 6 to 18 carbon atoms,

n is an integer from 1 to 190).

2. The composition for a hard mask according to the above 1, wherein Ar in Formula 1 is at least one selected from the group consisting of Formula 2 and Formula 3 below:

[Formula 2]

[Formula 3]

.

.

3. The composition for a hard mask according to the above 1, wherein in Formula 1, _{at least one of R 1} to R ₃ is a phenyl group and R _{4 is a phenylene group.}

4. The composition for a hard mask according to the above 1, wherein the compound of Formula 1 is prepared by a condensation reaction of an arene compound having 6 to 18 carbon atoms containing a hydroxyl group and a vinylaldehyde compound of Formula 4 below:

[Formula 4]

(Wherein, R ₁ to R ₃ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 18 carbon atoms,

R ₄ is a single bond, an alkylene group having 1 to 6 carbon atoms, or an arylene group having 6 to 18 carbon atoms).

5. The composition for a hard mask according to 1 above, comprising 5 to 15% by weight of the compound including the repeating unit represented by Formula 1, and 85 to 95% by weight of the solvent, based on the total weight of the composition.

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

The composition for a hard mask of the present invention forms a polymer for a resist underlayer film having excellent etching resistance to halogen gas without deterioration of optical and mechanical properties.

The composition for a hard mask according to an embodiment of the present invention may obtain appropriate crosslinking properties without changing the optical properties of the formed underlayer.

The composition for a hard mask according to an embodiment of the present invention can properly maintain acidity that affects storage stability.

One embodiment of the present invention comprises a compound and a solvent including a repeating unit represented by the following formula (1) to form a polymer for a resist underlayer film having excellent etching resistance to halogen gas without deterioration of optical and mechanical properties. It relates to a composition for a hard mask that can be used.

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

<Composition for hard mask>

The composition for a hard mask of the present invention includes a compound (A) including a repeating unit represented by the following formula (1) and a solvent (B).

Compound (A) comprising a repeating unit represented by Formula 1

[Formula 1]

(Wherein, Ar is a C6 to C18 arenetriyl group (Arenetriyl),

R ₁ to R ₃ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 18 carbon atoms,

R ₄ is a single bond, an alkylene group having 1 to 6 carbon atoms, or an arylene group having 6 to 18 carbon atoms,

n is an integer from 1 to 190).

In the present invention, when R ₄ is a single bond, R ₄ is not composed of a separate element and the carbon of the double bond and the carbon of the polymer main chain (the carbon of the aldehyde (-CHO) of the following formula 4) are directly connected. it means.

In the present invention, by including the compound including the repeating unit represented by Chemical Formula 1, the polymer layer formed of the composition for a hard mask of the present invention can exhibit excellent etching resistance. Specifically, the polymer for a resist underlayer formed from the composition for a hard mask of the present invention has excellent etching resistance to halogen gas without deterioration of optical and mechanical properties.

In this aspect, preferably, in Formula 1 according to an embodiment of the present invention, Ar may be at least one selected from the group consisting of Formula 2 and Formula 3 below:

[Formula 2]

[Formula 3]

.

.

Also, more preferably, at least one _{of R 1} to R ₃ in Formula 1 according to an embodiment of the present invention _{may be a phenyl group, and R 4} may be a phenylene group.

The compound including the repeating unit represented by Formula 1 according to an embodiment of the present invention may be prepared by a condensation reaction of an arene compound having 6 to 18 carbon atoms containing a hydroxyl group and a vinylaldehyde compound of Formula 4 below:

[Formula 4]

(Wherein, R ₁ to R ₃ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 18 carbon atoms,

R ₄ is a single bond, an alkylene group having 1 to 6 carbon atoms, or an arylene group having 6 to 18 carbon atoms).

In the present invention, when R ₄ is a single bond, R ₄ is not composed of a separate element and the carbon of the double bond and the carbon of the polymer main chain (the carbon of the aldehyde (-CHO) of the following formula 4) are directly connected. it means.

The arene compound having 6 to 18 carbon atoms containing a hydroxyl group may be, for example, of the following formula (11) or (12):

[Formula 11]

[Formula 12]

The vinylaldehyde compound of Formula 4 may be, for example, of Formulas 13 to 16 below:

[Formula 13]

[Formula 14]

[Formula 15]

[Formula 16]

[Formula 17]

Compound (A) including the repeating unit represented by Formula 1 according to an embodiment of the present invention may have a weight average molecular weight according to the n value. As a specific example, the weight average molecular weight of compound (A) may be from 1000 to 5000, preferably from 2000 to 5000.

Polydispersity index (PDI, Polydispersity index) [weight average molecular weight (Mw) / number average molecular weight (Mn)] of compound (A) comprising the repeating unit represented by Formula 1 is preferably 1.3 to 6.0, and 1.5 to It is more preferable that it is 4.0.

If the polydispersity index [weight average molecular weight (Mw) / number average molecular weight (Mn)] is included within the above range, the effect due to the compound (A) including the repeating unit represented by the above formula (1) becomes more excellent. It is preferable because

The content of the compound (A) including the repeating unit represented by Formula 1 according to an embodiment of the present invention is not particularly limited as long as the object of the present invention can be achieved, for example, 5 to 15 weight of the total weight of the composition %, and when the above range is satisfied, the effect of the present invention described above may be effectively exhibited. If the content of the compound (A) including the repeating unit represented by Formula 1 is less than 5% by weight of the total weight of the composition, it is difficult to obtain a coating layer with a desired coating thickness, and if it exceeds 15% by weight, the liquid coating uniformity may be reduced. have.

Solvent (B)

The solvent according to an embodiment of the present invention is not particularly limited as long as it is an organic solvent having sufficient solubility in the compound including the repeating unit represented by Formula 1, for example, propylene glycol monomethyl ether acetate (propylene glycol monomethyl ether acetate; PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone, ethyl lactate, gamma-butyrolactone (GBL), acetyl acetone, etc. and preferably propylene glycol monomethyl ether acetate (PGMEA).

The content of the solvent (B) according to an embodiment of the present invention is not particularly limited as long as the object of the present invention can be achieved, and the remaining amount excluding the reaction component and other additives including the compound of Formula 1 in the composition according to the present invention. may be included. For example, when only the compound of Formula 1 is used in the composition, the solvent may be 85 to 95% by weight of the total weight of the composition, and when the above range is satisfied, the above-described effects of the present invention may be effectively exhibited.

Crosslinking Agents and Catalysts

In addition, if necessary, the composition for a hard mask according to an embodiment of the present invention may further include at least one of a crosslinking agent and a catalyst.

The crosslinking agent is capable of crosslinking the repeating units of the polymer by heating in a reaction catalyzed by the generated acid, and can be reacted with the hydroxyl group of the compound (A) in a way that can be catalyzed by the generated acid It will not specifically limit if it is a crosslinking agent. As a representative example of such a crosslinking agent, any one selected from the group consisting of melamine, an amino resin, a glycoluryl compound and a bisepoxy compound may be used.

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

Specific examples of the crosslinking agent include etherified amino resins such as methylated or butylated melamine (specific examples include N-methoxymethyl-melamine or N-butoxymethyl-melamine) and methylated or butylated melamine Urea (urea) resin (specific example, Cymel U-65 Resin or UFR 80 Resin), glycoluril derivative represented by the following formula 31 (specific example, Powderlink 1174), bis (hydroxymethyl) represented by formula 32 -p-cresol compound) and the like. In addition, a bisepoxy-based compound represented by the following Chemical Formula 33 and a melamine-based compound represented by the following Chemical Formula 34 may also be used as a crosslinking agent.

[Formula 31]

[Formula 32]

[Formula 33]

[Formula 34]

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 monohydrate may be used, and a compound of a thermal acid generator (TAG) system that promotes storage stability may be mentioned. The thermal acid generator is an acid generator compound adapted to release an acid upon heat treatment, for example, pyridinium p-toluene sulfonate, 2,4,4,6-tetrabromocyclohexa Dienone, benzointosylate, 2-nitrobenzyltosylate, an alkyl ester of organic sulfonic acid, etc. can be used.

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

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

When the crosslinking agent is included, the content of the crosslinking agent may be 0.001 parts by weight to 50 parts by weight, preferably 0.1 parts by weight to 20 parts by weight, and more preferably 1 part by weight based on 100 parts by weight of the compound (A). to 20 parts by weight. In addition, when the catalyst is included, the content of the catalyst may be 0.001 parts by weight to 50 parts by weight, preferably 0.1 parts by weight to 20 parts by weight, and more preferably 1 part by weight based on 100 parts by weight of the compound (A). It may be from 20 parts by weight to 20 parts by weight.

When the crosslinking agent is included in the above range, appropriate crosslinking properties can be obtained without changing the optical properties of the formed underlayer film.

In addition, when the catalyst content is included in the above range, it is possible to obtain appropriate crosslinking properties, and also to appropriately maintain acidity affecting storage stability.

additive

If necessary, the composition for a hard mask of the present invention may further include an additive such as a surfactant. Examples of the surfactant include, but are not limited to, alkylbenzenesulfonate, alkylpyridinium salt, polyethylene glycol, tetraammonium salt, and the like. In this case, the content of the surfactant may be 1 part by weight to 30 parts by weight based on 100 parts by weight of the compound (A). When the content of the surfactant is included in the above range, appropriate crosslinking properties may be obtained without changing the optical properties of the formed underlayer.

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

manufacturing example

Preparation Example 1. Synthesis of compound (A-1) containing a repeating unit represented by Formula 1

A 1L three-necked flask equipped with a thermometer, a condenser, a stirrer, and a dropping funnel was installed in an oil container, and 1 mol of a phenol derivative (compound represented by Formula 11) was added to the reactor and dissolved in 500 g of propylene glycol monomethyl ether acetate (PGMEA). . Thereafter, 0.03 mol (5.16 g) of PTSA (paratoluenesulfonic acid) was added.

The dropping funnel was filled with a solution of 1 mol of a vinylaldehyde derivative (compound represented by Formula 13) in PGMEA (200 g), and was added dropwise for 2 hours while maintaining the temperature inside the reactor at 120°C. After completion of the dropwise addition, after stirring at the same temperature for 12 hours, 0.03 mol (4.48 g) of triethanolamine was added to the reactor as a neutralizing agent, stirred at room temperature for an additional 1 hour, cooled to room temperature, and the obtained reaction mixture was mass ratio A 9:1 methanol:ethylene glycol mixture was added dropwise to a 5L round-bottom flask containing 3 kg while stirring. The resulting solid product was left at the bottom of the flask, and the supernatant was removed by decanting, followed by distillation under reduced pressure at 80° C. for 1 hour to remove the residual solvent.

The molecular weight and polydispersity index of the obtained copolymer were measured by GPC under tetrahydrofuran, and the weight average molecular weight and polydispersity index (PDI) were measured and summarized below.

Preparation Example 2. Synthesis of compound (A-2) containing a repeating unit represented by Formula 1

A-2 was synthesized in the same manner as in Preparation Example 1, except that 1 mol of the compound represented by Formula 11 and 1 mol of the compound represented by Formula 14 were used as the phenol derivative and the vinylaldehyde derivative, respectively.

Preparation Example 3. Synthesis of compound (A-3) containing a repeating unit represented by Formula 1

A-3 was synthesized in the same manner as in Preparation Example 1, except that 1 mol of the compound represented by Formula 12 and 1 mol of the compound represented by Formula 13 were used as the phenol derivative and the vinylaldehyde derivative, respectively.

Preparation Example 4. Synthesis of compound (A-4) containing a repeating unit represented by Formula 1

A-4 was synthesized in the same manner as in Preparation Example 1, except that 1 mol of the compound represented by Formula 12 and 1 mol of the compound represented by Formula 14 were used as the phenol derivative and the vinylaldehyde derivative, respectively.

Preparation Example 5. Synthesis of Compound (A-5) containing a repeating unit represented by Formula 1

A-5 was synthesized in the same manner as in Preparation Example 1, except that 1 mol of the compound represented by Formula 11 and 1 mol of the compound represented by Formula 15 were used as the phenol derivative and the vinylaldehyde derivative, respectively.

Preparation Example 6. Synthesis of compound (A-6) containing a repeating unit represented by Formula 1

A-6 was synthesized in the same manner as in Preparation Example 1, except that 1 mol of the compound represented by Formula 11 and 1 mol of the compound represented by Formula 16 were used as the phenol derivative and the vinylaldehyde derivative, respectively.

Preparation Example 7. Synthesis of compound (A-7) containing a repeating unit represented by Formula 1

A-7 was synthesized in the same manner as in Preparation Example 1, except that 1 mol of the compound represented by Formula 11 and 1 mol of the compound represented by Formula 17 were used as the phenol derivative and the vinylaldehyde derivative, respectively.

Preparation 8. Synthesis of compound (A'-1)

A'-1 was synthesized in the same manner as in Preparation Example 1, except that formaldehyde was used as the aldehyde derivative.

Preparation 9. Synthesis of compound (A'-2)

A'-2 was synthesized in the same manner as in Preparation Example 1, except that 1,4-phenylenedimethanol was used as the bicinaldiol derivative.

Preparation 10. Synthesis of compound (A'-3)

A'-3 was synthesized in the same manner as in Preparation Example 1, except that benzaldehyde was used as the aldehyde derivative.

Examples and Comparative Examples

A composition for a hard mask of the composition and content (% by weight) described in Table 1 was prepared.

division Compound (A) Solvent (B) Crosslinking agent (C) Catalyst (D) Additive (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-1 18 B-1 82 Example 9 A-1 10 B-1 88 C-1 One D-1 One - - Example 10 A-1 10 B-1 89 - - - - E-1 One

division Compound (A') Solvent (B) crosslinking agent catalyst additive ingredient weight ingredient weight ingredient weight ingredient weight ingredient weight 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 - - - - - -

를 축합 중합하여 생성된 화합물(중량평균분자량:2100, PDI:1.3)A-1:

A compound produced by condensation polymerization of (weight average molecular weight: 2100, PDI: 1.3)

를 축합 중합하여 생성된 화합물(중량평균분자량:2300, PDI:1.7)A-2:

A compound produced by condensation polymerization of (weight average molecular weight: 2300, PDI: 1.7)

를 축합 중합하여 생성된 화합물(중량평균분자량:1850, PDI:1.8)A-3:

A compound produced by condensation polymerization of (weight average molecular weight: 1850, PDI: 1.8)

를 축합 중합하여 생성된 화합물(중량평균분자량:1850, PDI:1.6)A-4:

A compound produced by condensation polymerization of (weight average molecular weight: 1850, PDI: 1.6)

를 축합 중합하여 생성된 화합물(중량평균분자량:2500, PDI:1.8)A-5:

A compound produced by condensation polymerization of (weight average molecular weight: 2500, PDI: 1.8)

를 축합 중합하여 생성된 화합물(중량평균분자량:1670, PDI:2.7)A-6:

A compound produced by condensation polymerization of (weight average molecular weight: 1670, PDI: 2.7)

를 축합 중합하여 생성된 화합물(중량평균분자량:1520, PDI:2.6)A-7:

A compound produced by condensation polymerization of (weight average molecular weight: 1520, PDI: 2.6)

를 축합 중합하여 생성된 화합물A'-1:

a compound produced by condensation polymerization of

(Weight average molecular weight: 2400, PDI: 1.7)

를 축합 중합하여 생성된 화합물A'-2:

a compound produced by condensation polymerization of

(Weight average molecular weight: 2100, PDI: 2.1)

를 축합 중합하여 생성된 화합물A'-3:

a compound produced by condensation polymerization of

(Weight average molecular weight: 2120, PDI: 2.0)

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

C-1: (N-methoxymethyl-melamine resin)

D-1: p-toluene sulfonic acid-pyridine salt

E-1: triethylene glycol

Experimental example

1. Etch resistance evaluation

The sample solutions prepared in Examples 1 to 10 and Comparative Examples 1 to 3 were coated on a silicon wafer by spin-coating, respectively, and baked at 200° C. for 60 seconds to form a film having a thickness of 1500 Å. On each formed film, a photoresist for ArF is coated, baked at 110° C. for 60 seconds, exposed using ASML (XT:1450G, NA 0.93) exposure equipment, and then each developed with TMAH (2.38 wt% aqueous solution) to achieve a 60 nm thickness. A line and space pattern was obtained. The obtained sample was further cured at 110° C. for 60 seconds, the specimen was _{dry-etched for 20 seconds using a CHF 3} /CF ₄ mixed gas, respectively, and the etching rate was measured by examining each cross section with FE-SEM, and the Etching resistance was determined.

<Determination of etching resistance to halogen gas>

○: Etching rate less than 11A/Sec

△: Etching rate 11 to 12 A/Sec

×: Exceeding etching rate 12A/Sec

<For oxygen gas Etching Judgment>

○: Etching rate >20A/Sec

△: Etching rate 15~20A/Sec

×: Etching rate <15A/Sec

division Etching to Oxygen Gas Etching resistance to halogen gases Example 1 ○ ○ Example 2 ○ ○ Example 3 ○ ○ Example 4 ○ ○ Example 5 ○ ○ Example 6 ○ ○ Example 7 ○ ○ Example 8 ○ ○ Example 9 △ ○ Example 10 ○ ○ Comparative Example 1 △ △ Comparative Example 2 ○ × Comparative Example 3 ○ △

Referring to Table 3, it was confirmed that the Examples showed excellent etching resistance to halogen gas, but Comparative Examples were not excellent in all of these properties. However, in Example 8, the liquid coating uniformity was lowered due to the increase in viscosity.

Claims (6)

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

(Wherein, Ar is a C6 to C18 arenetriyl group (Arenetriyl),
R ₁ to R ₃ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 18 carbon atoms,
R ₄ is a single bond, an alkylene group having 1 to 6 carbon atoms, or an arylene group having 6 to 18 carbon atoms,
n is an integer from 1 to 190). The composition for a hard mask according to claim 1, wherein Ar in Formula 1 is at least one selected from the group consisting of Formula 2 and Formula 3 below:
[Formula 2]

[Formula 3]

. The composition for a hard mask according to claim 1, wherein in Formula 1, _{at least one of R 1} to R ₃ is a phenyl group and R _{4 is a phenylene group.} The composition for a hard mask according to claim 1, wherein the compound of Formula 1 is prepared by a condensation reaction of an arene compound having 6 to 18 carbon atoms containing a hydroxyl group and a vinylaldehyde compound of Formula 4 below:
[Formula 4]

(Wherein, R ₁ to R ₃ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 18 carbon atoms,
R ₄ is a single bond, an alkylene group having 1 to 6 carbon atoms, or an arylene group having 6 to 18 carbon atoms). The composition for a hard mask according to claim 1, comprising 5 to 15% by weight of the compound including the repeating unit represented by Formula 1, and 85 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 and a catalyst.