KR20240104252A - A composition of anti-reflective hardmask - Google Patents

Abstract

The present invention relates to (a) an aromatic copolymer composed of an aldehyde compound and an aryl compound substituted with a pyrolytic functional group represented by the following formula (1), or a copolymer blend including the same, and (b) an anti-reflective hard disk comprising an organic solvent. A mask composition is 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 anti-reflective properties useful in lithographic processes, and to an aromatic copolymer having strong absorption in an ultraviolet wavelength range and a hard mask composition comprising the same.

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 etch 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 is simultaneously resistant to etching.

However, the two properties required for such an organic hard mask layer, solubility and etching resistance, are in a conflicting relationship 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: Korean Patent Publication 10-2009-0120827 Patent Document 2: Korean Patent Publication 10-2008-0107210 Patent Document 3: International Patent Publication WO 2013100365 A1

The purpose of the present invention is to provide a hardmask polymer that has excellent polymer solubility, high etching selectivity, and sufficient resistance to multi-etching, and a composition containing the same.

The present invention aims to provide a novel hardmask polymer and a composition containing the same that can be used to perform lithographic techniques by minimizing the reflectivity between the resist and the back layer.

The hardmask composition according to the present invention,

(a) a binary aromatic copolymer or a mixture of these copolymers having a pyrolytic functional group when treated at a high temperature of 100 degrees or higher; and

(b) an organic solvent; an anti-reflective hard mask composition comprising:

[Formula 1]

The hard mask composition based on a binary copolymer composed of a binary compound of an aldehyde compound and an aryl compound and having a substituent that undergoes thermal decomposition during high-temperature heat treatment according to the present invention has a structure that is very advantageous for etch resistance and at the same time has a high carbon content in the polymer. It is excellent in 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 binary compound having a thermal decomposition functional group when treated at a high temperature of 100 degrees or more, represented by the following formula (1) Aromatic copolymers or mixtures of these copolymers; and (b) an organic solvent. An antireflective hardmask composition is provided.

[Formula 1]

In the above formula, the Ar group is a C6~C30 aryl group and a heteroaryl group, and the Ar group is a C6~C30 aryl or heteroaryl group that may be substituted with a hydroxyl group or a halogen group, and the C6~C30 aryl group. Groups and heteroaryl groups may have ether linkages.

The Preferably, it may have a t-BOC (t-butoxycarbonyl) structure.

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

The synthesis of the binary aromatic copolymer involves reacting aryl compounds capable of condensation polymerization under an acid catalyst with an aldehyde compound (t-BOC-BzA) having a thermal decomposition substituent (t-BOC) to synthesize a polymer compound with the structure shown below. I do it.

The acid catalyst used during polymerization can be hydrochloric acid, nitric acid, sulfuric acid, methane sulfonic acid, or paratoluene sulfonic acid (PTSA), and organic solvents such as PGMEA, GBL, toluene, etc. can be used at a temperature of 90 degrees. A copolymer can be synthesized by reacting at ~130 degrees for about 20 hours.

For example, the binary aromatic copolymer having the structure of Formula 1 may have the following forms (Formula 2-1) to (Formula 2-18).

The above polymers may be mixed with novolak resin or aromatic C6-C20 novolak polymerization 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) the aromatic copolymer composed of an aldehyde compound substituted with a high-temperature pyrolysis functional group and an aryl compound is used in an amount of 1 to 30% by weight based on 100 parts by weight of the organic solvent (b) used. It is desirable. If less than 1 part by weight or more than 30 parts by weight of the polymer prepared in (a) is used, it becomes less than 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 above aromatic ring-containing polymer. For example, propylene glycol monomethyl ether acetate (PGMEA), cyclohexanone, ethyl lactate, and gamma-butyrate. Lactone, 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 benzoguanamine, butoxymethylated benzoguanamine, These are compounds such as methoxymethylated urea, 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 may have 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 that releases acid upon heat treatment, such as pyridinium P-toluene sulfonate, 2,4,4,6-tetrabromocyclohexadienone, It is preferable to use benzoin tosylate, 2-nitrobenzyl tosylate, and alkyl esters of organic sulfonic acids.

When the final hardmask composition further includes (c) a crosslinker component and (d) an acid catalyst, the hardmask composition of the present invention includes (a) a copolymer with strong absorption properties in the ultraviolet region or a mixture of these copolymers. (blend) 1 to 30% by weight, more preferably 5 to 20% by weight, (c) 0.1 to 5% by weight of crosslinker component, more preferably 0.1 to 3% by weight, (d) 0.001 to 0.05% by weight of acid catalyst , more preferably 0.001 to 0.03% by weight, and (b) a total of 100% by weight using an organic solvent as the remaining component, preferably containing 75 to 98% by weight of an organic solvent.

Here, if the copolymer 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 properties 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, crosslinking characteristics may not appear well, and if it exceeds 0.05% by weight, storage stability may be affected due to increased 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

In a round flask, 1-pyrenol (100 mmol) and t-BOC-BzA (t-BOC-benzylaldehyde) monomer (110 mmol) were dissolved in gammabutyrolactone (GBL) (2.5 times the total monomers), then paratoluene sulfate. After adding 5 mol% of phonic acid (PTSA), polymerization was performed 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 degrees for 24 hours to obtain a polymer of Chemical Formula 2-2.

At this time, the polymer weight average molecular weight (Mw) was 3,800 and polydispersity (Mw/Mn) was 1.97.

Example-2) Synthesis of copolymer

9,9'-bis(4-hydroxynaphthyl)fluorene (60mmol) and t-BOC-BzA (t-BOC-benzylaldehyde) monomer (70mmol) were synthesized in the same manner as Example-1 to obtain Chemical Formula 2 A polymer of -4 was obtained. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 3,500 and a polydispersity (Mw/Mn) of 1.93.

Example-3) Synthesis of copolymer

1,1'-bi-2-naphthol (100 mmol) and t-BOC-BzA (t-BOC-benzylaldehyde) (110 mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-5. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 3,900 and a polydispersity (Mw/Mn) of 1.89.

Example-4) Synthesis of copolymer

9-phenylcarbazole (100 mmol) and t-BOC-BzA (t-BOC-benzylaldehyde) (110 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 4,900 and a polydispersity (Mw/Mn) of 1.89.

Example-5) Synthesis of copolymer

9-Naphthylcarbazole (60 mmol) and t-BOC-BzA (t-BOC-benzylaldehyde) (70 mmol) were synthesized in the same manner as Example-1 to obtain a polymer of Chemical Formula 2-10. 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

Indole (100 mmol) and t-BOC-BzA (t-BOC-benzylaldehyde) (110 mmol) were synthesized in the same manner as Example-1 to obtain a polymer of Chemical Formula 2-13. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 5,500 and a polydispersity (Mw/Mn) of 1.88.

Example-7) Synthesis of copolymer

Dibenzofuran (100 mmol) and t-BOC-BzA (t-BOC-benzylaldehyde) (110 mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-15. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 5,800 and a polydispersity (Mw/Mn) of 1.98.

Example-8) Synthesis of copolymer

1-Pyrenol (100 mmol) and ethoxyethyl-BzA (110 mmol) were synthesized in the same manner as Example-1 to obtain the polymer of Chemical Formula 2-17. At this time, the synthesized polymer had a weight average molecular weight (Mw) of 4,800 and a polydispersity (Mw/Mn) of 1.98.

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 in 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 8 and Comparative Examples was completely dissolved in 7 g of propylene glycol monomethyl ether acetate (PGMEA) and 3 g of cyclohexanone, and then filtered using a 0.2 um Melbrane filter to obtain the respective Examples. Sample solutions 1 to 8 and Comparative Examples were prepared.

The sample solutions prepared in Examples 1 to 8 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 below.

sample type Optical properties (193nm) Optical properties (248nm) Refractive index (n) Extinction coefficient (k) Refractive index (n) Extinction coefficient (k) Example 1 1.51 0.57 1.72 0.58 Example 2 1.54 0.53 1.73 0.58 Example 3 1.51 0.55 1.72 0.56 Example 4 1.53 0.63 1.73 0.57 Example 5 1.54 0.68 1.75 0.62 Example 6 1.55 0.61 1.72 0.56 Example 7 1.57 0.61 1.72 0.55 Example 8 1.56 0.62 1.72 0.54 Comparative Example 1.48 0.51 1.95 0.36

As shown in Table 1, the evaluation results confirmed that the composition containing the copolymer of the present invention had a refractive index and absorbance 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.

Lithographic evaluation of anti-reflective hardmask compositions

The sample solutions prepared in Examples 1, 3, 5, and 6 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.

KrF photoresist was coated on each formed coating film, baked at 110°C for 60 seconds, exposed individually using exposure equipment from ASML (XT: 1400, NA 0.93), and then exposed with a 2.38 wt% aqueous solution of TMAH (tetramethyl ammonium hydroxide). 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 3 0.4 0.3 cubic Example 5 0.4 0.3 cubic Example 6 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 8 and Comparative Examples was heat treated at 400 degrees for 90 seconds to form a thin film, and then treated 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. The change in thickness of the thin film was divided by the etching time to determine the respective etch rate ( /s) was calculated. The results are shown in Table 3 below.

Sample N2/O2 etch( /s) CFx etch( /s) Example 1 34.1 25.1 Example 2 34.3 25.3 Example 3 34.1 25.9 Example 4 34.6 25.9 Example 5 32.4 23.8 Example 6 34.3 25.8 Example 7 34.7 24.9 Example 8 34.7 25.9 Comparative Example 36.8 33.7

As shown in Table 3, the thin film formed in the 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 Example can be used as a lithography pattern. It can be predicted that it can serve as an anti-reflection hard mask that is excellent for forming.

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 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 (11)

(a) a binary aromatic copolymer or a blend of these copolymers having a pyrolytic functional group, represented by the following formula (1); and
(b) an organic solvent; an antireflective hardmask composition comprising:
[Formula 1]

In the above formula, the Ar group is a C6~C30 aryl group or heteroaryl group,
The According to paragraph 1,
An anti-reflective hard mask composition, wherein the Ar group is a C6 to C30 aryl or heteroaryl group that may be substituted with a hydroxyl group or a halogen group. According to claim 1 or 2,
An anti-reflective hard mask composition, characterized in that the aryl or heteroaryl group of C6 to C30 contains an ether bond. According to paragraph 1,
An antireflective hardmask composition, characterized in that the X group is t-BOC (t-butoxycarbonyl). According to paragraph 1,
An anti-reflective hardmask composition, characterized in that the X group is an alkoxy ethyl. According to paragraph 1,
An antireflective hardmask composition, characterized in that the weight average molecular weight (Mw) of the copolymer is 1,000 to 50,000. According to paragraph 1,
An antireflective hardmask composition, characterized in that the Ar group has a naphthalene, binaphthalene, pyrene, carbazole, or indole derivative structure. According to paragraph 1,
An antireflective hardmask composition, characterized in that the hardmask composition further includes a crosslinking agent and an acid catalyst component. According to clause 8,
The hard mask composition is,
(a) 1 to 30% by weight of a polymer made of an aromatic copolymer composed of an aldehyde compound and an aryl compound in which the thermal decomposition functional group is substituted, or a blend of these copolymers;
(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 consisting of a total of 100% by weight using an organic solvent as the remaining ingredient. According to clause 8 or 9,
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 clause 8 or 9,
The acid catalyst is p-toluenesulfonic acid monohydrate, pyridinium p-toluene sulfonate, 2,4,4,6-tetrabromocyclohexadienone, and benzoate. An anti-reflective hard mask composition, characterized in that it is at least one selected from the group consisting of phosphorus tosylate, 2-nitrobenzyl tosylate, and alkyl esters of organic sulfonic acids.