KR20240037095A - A composition of anti-reflective hardmask - Google Patents

Abstract

The present invention provides an antireflective hardmask composition comprising (a) a copolymer consisting of an aryl compound having a glycidyl ether functional group represented by the following formula or a copolymer blend containing the same, and (b) an organic solvent. provided.
[Formula 1]

Description

Anti-reflective hard mask composition {A COMPOSITION OF ANTI-REFLECTIVE HARDMASK}

The present invention relates to a hard mask composition having antireflection properties useful in lithographic processes, and includes an aromatic copolymer comprising a structural unit made of an aryl compound having a glycidyl ether functional group with strong absorption in the ultraviolet wavelength range, and the same. It relates to a hardmask composition characterized in that:

Recently, as the semiconductor industry has increasingly required miniaturization processes, an effective lithographic process is essential to realize such ultra-fine technologies. In particular, the demand for new materials for the hard mask process, which is very essential in the etching process, is increasing.

In general, the hard mask film serves as an intermediate film that transfers the fine pattern of the photoresist to the lower substrate layer through a selective etching process. Therefore, the hardmask layer requires properties such as chemical resistance, heat resistance, and etching resistance to withstand multiple etching processes. The existing hard mask film used was an ACL (amorphous carbon layer) film made by chemical vapor deposition (CVD). The disadvantages of this were high equipment investment, particles generated during the process, and opacity of the film. There were many inconveniences in using it due to problems with photo alignment.

Recently, a spin-on hardmask method formed by a spin-on coating method was introduced instead of this chemical vapor deposition method. The spin-on coating method forms a hard mask composition using an organic polymer material that is soluble in a solvent, and the most important characteristic at this time is the formation of an organic polymer coating film that simultaneously has etching resistance.

However, the two properties required for such an organic hard mask layer, solubility and etching resistance, are in conflict with each other, so a hard mask composition that can satisfy both was needed. Materials that satisfy the characteristics of these organic hard mask materials and have been introduced into the semiconductor lithographic process have recently been introduced (Patent Publication No. 10-2009-0120827, Patent Publication No. 10-2008-0107210, Patent WO 2013100365 A1), which is hydroxyphi. These were hard mask materials using a copolymer with an appropriate high molecular weight synthesized using a conventional phenol resin manufacturing method using hydroxypyrene.

However, as the semiconductor lithographic process has recently gone through a process of further miniaturization, it has become difficult for these organic hard mask materials to sufficiently perform the role of a mask due to the lack of etching selectivity in the etching process compared to existing inorganic hard mask materials. It has arrived. Therefore, there is an urgent need to introduce organic hardmask materials that are more optimized for the etching process.

Patent Document 1: WO 2013100365 A1

The purpose of the present invention is to provide a new type of anti-reflective hardmask composition in order to develop an organic hardmask material more optimized for the etching process.

The hardmask composition according to the present invention is (a) a copolymer containing a structural unit represented by the following formula (1), which includes an aryl compound having a glycidyl ether functional group, or a blend of these copolymers; and

(b) organic solvent;

It is an anti-reflective hard mask composition comprising:

[Formula 1]

In Formula 1, the Ar group is an aryl group of C6~C30; Heteroaryl group of C6~C30; It is a C6 to C30 aryl group that may be substituted with a hydroxyl group or a halogen group; or a C6 to C30 heteroaryl group that may be substituted with a hydroxyl group or a halogen group.

R1 and R2 are each independently hydrogen; Alkyl group of C1~C20; Alkenyl group of C2~C20; or an aryl group of C6 to C30; and R1 and R2 may include one or more selected from the group consisting of an ether bond, a ketone bond and an ester bond, and R1 and R2 may be the same or different from each other and may have a ring structure. there is.

In Formula 1, n is 3 to 50, and m is 1 to 5.

A hardmask composition based on a copolymer or a blend of these copolymers containing an aryl compound having a glycidyl ether functional group and a structural unit represented by the following formula (1) according to the present invention has a carbon content in the polymer. It has a structure that is very advantageous for etch resistance and at the same time has excellent polymer solubility, making it very advantageous for forming a uniform thin film. Therefore, it is possible to provide a lithographic structure with excellent pattern evaluation results due to its high etching selectivity compared to existing organic hard masks and sufficient resistance to multiple etchings.

The copolymer-based hardmask composition according to embodiments of the present invention has a refractive index and absorbance in a useful range as an anti-reflection film in the deep UV region, such as ArF (193 nm) and KrF (248 nm), when forming a film, so that it can be used as a resist and back surface. Reflectivity between layers can be minimized.

According to the present invention, (a) a copolymer containing an aryl compound having a glycidyl ether functional group and a structural unit represented by the following formula (1), or a blend of these copolymers; and (b) an organic solvent. An antireflective hardmask composition is provided.

[Formula 1]

In Formula 1, the Ar group is an aryl group of C6~C30; Heteroaryl group of C6~C30; It is a C6 to C30 aryl group that may be substituted with a hydroxyl group or a halogen group; or a C6 to C30 heteroaryl group that may be substituted with a hydroxyl group or a halogen group.

R1 and R2 are each independently hydrogen; Alkyl group of C1~C20; Alkenyl group of C2~C20; or an aryl group of C6 to C30; and R1 and R2 may include one or more selected from the group consisting of an ether bond, a ketone bond and an ester bond, and R1 and R2 may be the same or different from each other and may have a ring structure. there is.

In Formula 1, n is 3 to 50, preferably n is 3 to 30, and m is 1 to 5, preferably 1 to 3.

Meanwhile, the weight average molecular weight (Mw) of the copolymer is 1,000 to 50,000, and preferably ranges from 2,000 to 20,000.

Containing the structural unit of Formula 1 above For example, the copolymer may have the following forms (Formula 2-1) to (Formula 2-17).

The polymers of the copolymer may be mixed with novolac resin or aromatic C6-C20 novolak polymers having hydroxyl groups to improve the dissolution, coating, or curing properties of the entire hard mask composition.

Meanwhile, in order to make a hard mask composition, a copolymer containing the structural unit represented by Formula 1 above (a) containing an aryl compound having a glycidyl ether functional group, or a blend of these copolymers is used. (b) It is preferably used in an amount of 1 to 30% by weight based on 100 parts by weight of the organic solvent. When the copolymer of (a) or a blend of these copolymers is used in an amount of less than 1 part by weight or more than 30 parts by weight, the desired coating thickness falls below or exceeds the desired coating thickness, making it difficult to achieve an accurate coating thickness.

The organic solvent is not particularly limited as long as it has sufficient solubility for the copolymer of (a) or a blend of these copolymers, for example, propylene glycol monomethyl ether acetate (PGMEA), cyclo Hexanone, ethyl lactate, gamma butyrolactone, etc. can be mentioned.

In addition, the anti-reflective hardmask composition of the present invention may further include (c) a crosslinking agent component and (d) an acid catalyst.

The (c) crosslinking agent component used in the hard mask composition of the present invention is preferably capable of crosslinking the repeating units of the polymer by heating in a catalytic reaction by the generated acid, and the (d) acid catalyst is heat activated. It is preferable that it is an acid catalyst.

The cross-linking agent component (c) used in the hard mask composition of the present invention is not particularly limited as long as it is a cross-linking agent that can react with the aromatic ring-containing polymer in a manner that can be catalyzed by the produced acid. Crosslinking agents include melamine-based, substituted urea-based, or polymer-based ones thereof. Preferably, it is a crosslinking agent having at least two crosslinking substituents, and is methoxymethylated glycoluril, butoxymethylglycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated urea, methoxymethylated benzoguanamine, butoxymethylated urea. These are compounds such as methylated benzoguanamine, butoxymethylated urea, and methoxymethylated thiourea.

Additionally, a crosslinking agent with high heat resistance can be used as the crosslinking agent, and a compound containing a crosslinking substituent having an aromatic ring in the molecule can be preferably used. These compounds above may exemplify compounds having the structural formula below.

The (d) acid catalyst used in the hard mask composition of the present invention may be an organic acid such as p-toluenesulfonic acid monohydrate, and TAG (Thermal Acid Generator) for storage stability. Chemical compounds can also be used as catalysts. TAG is an acid generator compound designed to release acid upon heat treatment, such as 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, pyridinium P- It is preferable to use toluene sulfonate (Pyridinium P-toluene sulfonate) and alkyl esters of organic sulfonic acids.

In the case where the hardmask composition of the present invention further comprises (c) a crosslinking agent component and (d) an acid catalyst, the hardmask composition of the present invention contains (a) the atom of (a) having strong absorption characteristics in the ultraviolet region. 1 to 30% by weight of polymer or blend of these copolymers, preferably 5 to 20% by weight, (c) 0.1 to 5% by weight of crosslinker component, preferably 0.1 to 3% by weight, (d) acid catalyst 0.001 to 0.05 wt%, preferably 0.001 to 0.03 wt%, and (b) an organic solvent as the remaining ingredient, for a total of 100 wt%, preferably containing 75 to 98 wt% of organic solvent. desirable.

Here, if the copolymer of (a) or a blend of these copolymers is less than 1% by weight or more than 30% by weight, the desired coating thickness falls below or exceeds the desired coating thickness, making it difficult to achieve an accurate coating thickness.

In addition, if the crosslinking agent component is less than 0.1% by weight, crosslinking characteristics may not appear, and if it exceeds 5% by weight, the optical properties of the coating film may be changed due to excessive addition.

In addition, if the acid catalyst is less than 0.001% by weight, the crosslinking characteristics may not appear well, and if it is more than 0.05% by weight, storage stability may be affected due to an increase in acidity due to excessive addition.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example-1) Synthesis of copolymer

Dissolve 1-glycidyloxynaphthalene (100 mmol) and benzaldehyde (100 mmol) in gammabutyrolactone (GBL) (2.5 times the total monomers) in a 250 mL round flask, then add 5 mol% of methanesulfonic acid. Afterwards, it was polymerized at a temperature of 120 degrees for 20 hours.

After polymerization is completed, the reactant is precipitated in an excess of methanol/water (8:2) solvent and then neutralized using triethylamine. The resulting precipitate was filtered and washed twice with an excess of methanol solution, then the precipitate was filtered and dried in a vacuum oven at 65°C for 24 hours to obtain a polymer of Chemical Formula 2-2.

At this time, the polymer weight average molecular weight (Mw) was 4,500 and polydispersity (Mw/Mn) was 1.87.

Example-2) Synthesis of copolymer

Phenyl glycidyl ether (100 mmol) and 1-naphthylaldehyde (100 mmol) were synthesized in the same manner as Example-1 to obtain a polymer of Chemical Formula 2-3. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 3,800 and a polydispersity (Mw/Mn) of 1.85.

Example-3) Synthesis of copolymer

1-Glycidyloxynaphthalene (60mmol) and 1-naphthylaldehyde (60mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-4. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 4,300 and a polydispersity (Mw/Mn) of 1.89.

Example-4) Synthesis of copolymer

1-Glycidyloxynaphthalene (80 mmol) and 4-phenoxybenzaldehyde (80 mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-6. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 5,800 and a polydispersity (Mw/Mn) of 1.88.

Example-5) Synthesis of copolymer

1-Glycidyloxynaphthalene (100 mmol) and fluorenone (100 mmol) were synthesized in the same manner as Example-1 to obtain a polymer of Chemical Formula 2-7. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 3,900 and a polydispersity (Mw/Mn) of 1.87.

Example-6) Synthesis of copolymer

1-Glycidyloxypyrene (80 mmol) and benzaldehyde (80 mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-9. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 4,700 and a polydispersity (Mw/Mn) of 1.88.

Example-7) Synthesis of copolymer

1-Glycidyloxypyrene (70 mmol) and 3-hydroxybenzaldehyde (70 mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-11. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 4,500 and a polydispersity (Mw/Mn) of 1.87.

Example-8) Synthesis of copolymer

Bisglycidyloxyphenyl fluorene (9,9-Bis(4-glycidyloxyphenyl) fluorene) (80 mmol) and benzaldehyde (80 mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-14. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 4,100 and a polydispersity (Mw/Mn) of 1.88.

Example-9) Synthesis of copolymer

4-Glycidylcarbazole (80mmol) and benzaldehyde (80mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-16. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 4,800 and a polydispersity (Mw/Mn) of 1.88.

Comparative Example) Synthesis of phenolic polymer

9,9-Bishydroxyphenylfluorene (100 mmol) and benzaldehyde (110 mmol) are dissolved in PGMEA, and then 5 mol% of concentrated sulfuric acid is added thereto.

After polymerization in the same manner as Example-1, the polymer was purified and dried in a vacuum oven, and a polymer with a weight average molecular weight (Mw) of 3,300 was obtained.

Hardmask composition preparation

1 g of the polymer prepared in Examples 1 to 9 and Comparative Examples was completely dissolved in 7 g of propylene glycol monomethyl ether acetate (PGMEA) and 2 g of cyclohexanone, and then filtered using a 0.2 um Melbrane filter to obtain the respective Examples. 1 to 9 and Comparative Example sample solutions were prepared.

The sample solutions prepared in Examples 1 to 9 and Comparative Example were each spin-coated on a silicon wafer and baked at 400°C for 90 seconds to form a film with a thickness of 3000Å.

At this time, the refractive index n and extinction coefficient k of the formed films were respectively calculated. The device used was an ellipsometer (J. A. Woollam), and the measurement results are shown in Table 1.

As a result of the evaluation, it was confirmed that there was a refractive index and absorption that could be used as an antireflection film at ArF (193 nm) and KrF (248 nm) wavelengths. Typically, the refractive index of the material used as a semiconductor anti-reflection film ranges from 1.4 to 1.8, and the important thing is the extinction coefficient, and the higher the absorption, the better. However, if the k value is 0.3 or more, there is no problem in using it as an anti-reflection film, so the material of the present invention It can be seen that the hard mask composition according to the examples can be used as an anti-reflection film.

sample type Optical properties (193nm) Optical properties (248nm) Refractive index (n) Extinction coefficient (k) Refractive index (n) Extinction coefficient (k) Example 1 1.51 0.58 1.71 0.55 Example 2 1.53 0.51 1.73 0.56 Example 3 1.51 0.45 1.72 0.56 Example 4 1.55 0.63 1.73 0.57 Example 5 1.55 0.68 1.74 0.62 Example 6 1.54 0.61 1.72 0.55 Example 7 1.56 0.61 1.72 0.55 Example 8 1.55 0.60 1.71 0.56 Example 9 1.54 0.61 1.72 0.55 Comparative Example 1.48 0.51 1.95 0.36

Lithographic evaluation of anti-reflective hardmask compositions

The sample solutions prepared in Examples 1, 4, 6, and 7 and Comparative Examples were spin-coated on aluminum-coated silicon wafers and baked at 400°C for 90 seconds to form a coating film with a thickness of 3000Å.

Photoresist for KrF was coated on each of the above-formed coating films, baked at 110°C for 60 seconds, exposed respectively using exposure equipment from ASML (XT: 1400, NA 0.93), and then TMAH (tetramethyl ammonium hydroxide) 2.38 wt% aqueous solution. Each was developed for 60 seconds. Then, as a result of examining each 90 nm line and space pattern using V-SEM, the results shown in Table 2 below were obtained. The EL (expose latitude) margin according to changes in exposure amount and the DoF (depth of focus) margin according to changes in distance from the light source were considered and recorded in Table 2. As a result of the pattern evaluation, good results were confirmed in terms of profile and margin, and it was found that the EL margin and DoF margin required for litho pattern evaluation were satisfied.

sample type pattern characteristics EL margin
(△mJ/energy mJ) DoF margin
(㎛) pattern shape Example 1 0.3 0.3 cubic Example 4 0.4 0.3 cubic Example 6 0.4 0.3 cubic Example 7 0.4 0.4 cubic Comparative manufacturing example 0.2 0.2 undercut

Evaluation of etching properties of anti-reflective hardmask compositions

The hard mask composition (10% by weight) according to Examples 1 to 9 and Comparative Examples was heat-treated at 400 degrees for 90 seconds to form a thin film, and then heated with N2/O2 mixed gas (50mT/ 300W/ 10 O2/ 50 N2). After dry etching for 60 seconds using CFx gas (100mT/ 600W / 42 CF4 / 600 Ar / 15 O2 conditions), the thickness of the thin film was measured before and after etching. Each etch rate (/s) was calculated by dividing the change in thickness of the thin film by the etching time. The results are shown in Table 3 below.

Sample N2/O2 etch(/s) CFx etch(/s) Example 1 34.3 24.7 Example 2 34.0 23.3 Example 3 34.4 23.5 Example 4 34.6 23.1 Example 5 32.4 22.8 Example 6 34.3 23.1 Example 7 34.7 24.9 Example 8 32.9 24.7 Example 9 34.4 23.8 Comparative Example 36.8 30.7

As shown in Table 3, the thin film formed in the above example shows very excellent etch resistance compared to the thin film formed in the comparative example, and based on these bulk etch characteristics, the hardmask composition formed in the above example can form a lithography pattern. It is expected that it can serve as an excellent anti-reflection hard mask.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements can also be made by those skilled in the art using the basic concept of the present invention as defined in the following claims. It falls within the scope of invention rights.

Claims (8)

(a) a copolymer containing an aryl compound having a glycidyl ether functional group and a structural unit represented by the following formula (1), or a blend of these copolymers; and
(b) organic solvent;
An antireflective hardmask composition comprising:
[Formula 1]


In Formula 1, the Ar group is an aryl group of C6~C30; Heteroaryl group of C6~C30; It is a C6 to C30 aryl group that may be substituted with a hydroxyl group or a halogen group; or a C6 to C30 heteroaryl group that may be substituted with a hydroxyl group or a halogen group.
R1 and R2 are each independently hydrogen; Alkyl group of C1~C20; Alkenyl group of C2~C20; or an aryl group of C6 to C30; and R1 and R2 may include one or more selected from the group consisting of an ether bond, a ketone bond and an ester bond, and R1 and R2 may be the same or different from each other and may have a ring structure. there is.
In Formula 1, n is 1 to 50, and m is 1 to 5. According to paragraph 1,
An antireflective hardmask composition, characterized in that the weight average molecular weight (Mw) of the copolymer is in the range of 1,000 to 50,000. According to paragraph 1,
An antireflective hardmask composition, characterized in that the Ar group has a benzene, naphthalene, pyrene, or carbazole derivative structure. According to paragraph 1,
An antireflective hardmask composition, wherein the R1 group is hydrogen and the R2 group has a benzene, diphenyl, naphthalene, or hydroxybenzene derivative structure. According to paragraph 1,
The hard mask composition is an anti-reflective hard mask composition further comprising a cross-linking agent and an acid catalyst component. According to clause 5,
The hard mask composition is,
(a) 1 to 30% by weight of a copolymer or a blend of these copolymers containing an aryl compound having a glycidyl ether functional group and the structural unit represented by Formula 1;
(b) 0.1 to 5% by weight of cross-linking agent component;
(c) 0.001 to 0.05% by weight of acid catalyst; and
(d) An anti-reflective hard mask composition, characterized in that it consists of a total of 100% by weight using an organic solvent as the remaining ingredient. According to claim 5 or 6,
The crosslinking agent includes methoxymethylated glycoluril, butoxymethylglycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, and methoxymethylated urea. An anti-reflective hard mask composition, characterized in that it is any one selected from the group consisting of oxymethylated thiourea compounds. According to claim 5 or 6,
The acid catalyst is 2,4,4,6-tetrabromocyclohexadienone; p-toluenesulfonic acid monohydrate; Pyridinium p-toluene sulfonate; benzoin tosylate; 2-nitrobenzyl tosylate; and alkyl esters of organic sulfonic acids. An antireflective hardmask composition selected from the group consisting of.