KR102270378B1 - A composition of anti-reflective hardmask containing indole derivatives - Google Patents

Abstract

The present invention provides an antireflection hardmask composition comprising (a) a polymer comprising an indole derivative represented by the following formula (1) or a copolymer mixture (blend) comprising the same and (b) an organic solvent.
[Formula 1]

Description

Antireflection hard mask composition containing indole derivatives {A COMPOSITION OF ANTI-REFLECTIVE HARDMASK CONTAINING INDOLE DERIVATIVES}

The present invention relates to a hardmask composition having antireflection film properties useful in a lithographic process, an aromatic polymer containing an indole derivative having strong absorption in the ultraviolet wavelength region, and a hardmask composition comprising the same is about

Recently, as the semiconductor industry increasingly requires a miniaturization process, an effective lithographic process is essential to realize such ultra-fine technology. 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 hardmask film quality serves as an interlayer that transfers a micropattern of a photoresist to a lower substrate layer through a selective etching process. Therefore, properties such as chemical resistance, heat resistance, and etching resistance are required for the hard mask layer to withstand multiple etching processes. The existing hardmask film quality used was an amorphous carbon layer (ACL) film made by chemical vapor deposition (CVD). There were many inconveniences to use due to photo align problems.

Recently, a spin-on hardmask method of forming a spin-on coating method instead of the chemical vapor deposition method has been introduced. The spin-on coating method forms a hard mask composition using an organic polymer material having solubility in a solvent, and the most important characteristic at this time is to form an organic polymer coating film having etching resistance at the same time.

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

However, as the semiconductor lithography process has recently been further refined, in the case of such an organic hard mask material, it is difficult to sufficiently perform a mask role due to the lack of etching selectivity in the etching process compared to the conventional inorganic hard mask material. has been reached Accordingly, there is an urgent need to introduce an organic hardmask material that is more optimized for the etching process.

An object of the present invention is to provide a hardmask polymer having excellent polymer solubility, high etching selectivity, and sufficient resistance to multi-etching, and a composition comprising the same.

It is an object of the present invention to provide a novel hardmask polymer capable of minimizing the reflectivity between the resist and the backing layer, which can be used to perform lithographic techniques, and a composition comprising the same.

The hard mask composition according to the present invention comprises: (a) a polymer represented by the following formula (1) or a mixture of these copolymers comprising an indole derivative; and

(b) an organic solvent;

It is an anti-reflective hard mask composition comprising a.

[Formula 1]

The hardmask composition based on a polymer made of an indole derivative according to the present invention has a very high carbon content in the polymer and a very low Ohnishi Parameter value for predicting etch resistance due to a structure that does not contain oxygen. advantageous structure. Since the packing density is very high in the structure of the polymer, when the thin film is formed, the film density is increased and the etching resistance is very excellent. Accordingly, it is possible to provide a lithographic structure having an excellent pattern evaluation result because the etch selectivity ratio is high compared to the conventional organic hardmask, and the resistance to multiple etching is sufficient.

The hard mask composition based on the pyrrole-based polymer according to the 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), KrF (248 nm), etc. when forming a film. The reflectivity between the backside layers can be minimized.

According to the present invention, a polymer or a mixture of these copolymers comprising an indole derivative represented by the following formula (1); and

(b) an organic solvent; There is provided an anti-reflective hard mask composition comprising a.

[Formula 1]

In the above formula, R1 is a hydrogen atom, a halogen group, an amino group, a nitro group, a hydroxyl group, or a C1-C10 alkyl group, a C2-C10 alkenyl group, a C6-C20 aryl group and a heterocyclic group. R3 and R4 are hydrogen, a C1-C10 alkyl group, a C2-C10 alkenyl group, a C6-C20 aryl group and a heterocyclic group, and a C6-C20 aryl group which may be substituted with a hydroxyl group, a fluorine group, or a nitrile group. Here, R2 and R3 may form a ring together with the carbon atom to which they are attached.

Here, the weight average molecular weight (Mw) of the entire copolymer is 500 to 50,000, preferably 1,000 to 30,000.

The polymer having the structure of Chemical Formula 1 may have, for example, the form of Chemical Formula 2 of Chemical Formulas 2-1 to 2-10 as follows.

[Formula 2]

The polymers may be mixed with a novolac resin or aromatic C6 to C20 novolak polymers having a hydroxyl group to improve dissolution properties, coating properties, or curing properties of the entire hardmask composition.

On the other hand, in order to make a hard mask composition, the polymer containing the indole derivative (a) is preferably used in an amount of 1 to 30% by weight based on 100 parts by weight of the organic solvent (b) used. When the polymer prepared from the indole-based (a) is used in less than 1 part by weight or in excess of 30 parts by weight, it becomes less than or exceeds the desired coating thickness, and thus it is difficult to accurately match the coating thickness.

And the organic solvent is not particularly limited as long as it has sufficient solubility for the above aromatic ring-containing polymer, and for example, propylene glycol monomethyl ether acetate (PGMEA), cyclohexanone, ethyl lactate, etc. have.

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

It is preferable that the crosslinking agent component (c) used in the hardmask composition of the present invention can crosslink the repeating unit of the polymer by heating in a catalyzed reaction by the generated acid, and the (d) acid catalyst is thermally activated It is preferably an acid catalyst.

The crosslinking agent component (c) used in the hardmask composition of the present invention is not particularly limited as long as it is a crosslinking agent that can be reacted with the aromatic ring-containing polymer in a manner that can be catalyzed by the produced acid. Examples of the crosslinking agent include a melamine-based, substituted urea-based, or polymer-based crosslinking agent. Preferably it is a crosslinking agent having at least two crosslinking substituents, methoxymethylated glycoluril, butoxymethyl glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, A compound such as methoxymethylated urea, butoxymethylated urea, and methoxymethylated thiourea.

In addition, although a crosslinking agent with high heat resistance can be used as the crosslinking agent, a compound containing a crosslinking substituent having an aromatic ring in its molecule can be preferably used. These compounds may be exemplified by compounds having the following structural formula.

As the acid catalyst (d) used in the hard mask composition of the present invention, an organic acid such as p-toluenesulfonic acid monohydrate may be used, and a thermal acid generator (TAG) that promotes storage stability A systemic compound can also be used as a catalyst. TAG is an acid generator compound adapted to release an acid upon heat treatment, for example, 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, and the like.

When the final hardmask composition further comprises (c) a crosslinking agent component and (d) an acid catalyst, the hardmask composition of the present invention is (a) an indole-type polymer having strong absorption properties in the ultraviolet region or a copolymer thereof 1 to 30% by weight of a blend, more preferably 3 to 15% by weight, (c) 0.1 to 5% by weight of a crosslinking agent component, more preferably 0.1 to 3% by weight, (d) 0.001 to 0.05% by weight of an acid catalyst % by weight, 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 the organic solvent .

Here, when the indole-based aromatic ring-containing polymer is less than 1% by weight or exceeds 30% by weight, it becomes less than or exceeds the desired coating thickness, and thus it is difficult to accurately match the coating thickness.

And when the crosslinking agent component is less than 0.1% by weight, crosslinking properties may not appear, and when it exceeds 5% by weight, the optical properties of the coating film may be changed by over-injection.

In addition, when the amount of the acid catalyst is less than 0.001% by weight, crosslinking properties may not be well exhibited, and when it exceeds 0.05% by weight, storage stability may be affected by an increase in acidity due to excessive input.

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

Example-1)

In a 250 mL round flask, 12 g (100 mmol) of indole and 11 g (100 mmol) of benzaldehyde were dissolved in 55 g of 1,4-dioxane, and then 2 g of para-toluenesulfonic acid monohydrate (PTSA) was added, followed by polymerization at 80°C for 20 hours.

After polymerization, the reactant is precipitated in an excess of methanol solvent and then neutralized with triethylamine. The resulting precipitate was filtered and dried in a vacuum oven at 60°C for 24 hours to obtain a polymer.

A high molecular weight average molecular weight (Mw) of 2,600 and a polydispersity (Mw/Mn) of 1.67 were obtained.

Example-2)

12 g (100 mmol) of indole and 16 g (100 mmol) of 1-naphthylaldehyde were synthesized in the same manner as in Example 1 to synthesize a polymer. After polymer purification, a weight average molecular weight (Mw) of 2,300 and a polydispersity (Mw/Mn) of 1.65 were obtained.

Example-3)

12 g (100 mmol) of indole and 18 g (100 mmol) of biphenyl-4-carboxaldehyde were synthesized in the same manner as in Example 1 to synthesize a polymer. After polymer purification, a weight average molecular weight (Mw) of 2,500 and a polydispersity (Mw/Mn) of 1.58 were obtained.

Example-4)

Indole 1.2g (10mmol), triphenylenecarboxaldehyde (triphenylenecarboxaldehyde) 2.6g (10mmol) to synthesize a polymer in the same manner as in Example-1. After polymer purification, a weight average molecular weight (Mw) of 1,800 and a polydispersity (Mw/Mn) of 1.56 were obtained.

Example-5)

Indole 2.4g (20mmol) and pyrenecarboxaldehyde 4.6g (20mmol) to synthesize a polymer in the same manner as in Example-1. After polymer purification, a weight average molecular weight (Mw) of 1,500 and a polydispersity (Mw/Mn) of 1.66 were obtained.

Example-6)

Indole 12g ( 100mmol ), fluorenone (Fluorenone) 18g (100mmol) to synthesize a polymer in the same manner as in Example-1. After polymer purification, a weight average molecular weight (Mw) of 2,300 and a polydispersity (Mw/Mn) of 1.67 were obtained.

Comparative Example) Phenolic Polymer Synthesis

35 g (100 mmol) of 9,9-bishydroxyphenyl fluorene and 11.7 g (110 mmol) of benzaldehyde were dissolved in 109 g of PGMEA, and then 1 g of concentrated sulfuric acid was added thereto.

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

Preparation of hard mask composition

1 g of the polymer and 300 ppm of surfactant made in Examples 1 to 6 and Comparative Examples were put in 7 g of propylene glycol monomethyl ether acetate (PGMEA) and 2 g of cyclohexanone and completely dissolved, followed by filtration using a 0.1 um Melbrain filter Thus, Examples 1 to 6 and Comparative Example sample solutions were prepared, respectively.

Each of the sample solutions prepared in Examples 1 to 6 and Comparative Example was spin-coated on a silicon wafer and baked at 240° C. for 60 seconds to form a film having a thickness of 3000 Å.

At this time, refractive index n and extinction coefficient k for the formed 　 films were respectively obtained. The device used is 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 absorbance usable as an antireflection film at ArF (193 nm) and KrF (248 nm) wavelengths. Generally, the refractive index range of the material used as the semiconductor anti-reflection film is about 1.4 to 1.8, and the important thing is the extinction coefficient, and the higher the absorbance, the better. It can be seen that the hard mask composition according to the embodiments can be used as an anti-reflection film.

sample type Optical Characteristics (193nm) Optical Characteristics (248nm) refractive index (n) extinction coefficient (k) refractive index (n) extinction coefficient (k) Example 1 1.49 0.56 1.70 0.52 Example 2 1.53 0.58 1.71 0.54 Example 3 1.52 0.60 1.73 0.56 Example 4 1.55 0.63 1.73 0.57 Example 5 1.56 0.65 1.74 0.58 Example 6 1.54 0.61 1.72 0.53 Comparative Example 1.48 0.68 1.95 0.35

Lithographic evaluation of antireflective hardmask compositions

The sample solutions prepared in Examples 1, 3, 5 and Comparative Examples were spin-coated on a silicon wafer coated with aluminum, respectively, and baked at 240° C. for 60 seconds to form a coating film having a thickness of 3000 Å.

A photoresist for KrF is coated on each coating layer formed, baked at 110°C for 60 seconds, and exposed using ASML (XT:1400, NA 0.93) exposure equipment, followed by TMAH (tetramethyl ammonium hydroxide) 2.38wt% 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 (exposure latitude) margin according to the change of exposure amount and the DoF (depth of focus) margin according to the distance change with 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 lithographic pattern evaluation were satisfied.

sample type pattern characteristics EL margin
(ΔmJ/energy mJ) DoF margin
(μm) pattern shape Example 1 0.3 0.3 cubic Example 3 0.4 0.3 cubic Example 5 0.4 0.4 cubic Comparative Preparation Example 0.2 0.2 undercut

Evaluation of etching properties for anti-reflective hardmask compositions

In Examples 2, 3, 5 and Comparative Examples, respectively, the patterned specimens were subjected to dry etching of the lower SiON anti-reflection film (BARC) _{using CHF 3} /CF _{4 mixed gas and PR as a mask, followed by O 2} /N ₂ mixing Dry etching of this hard mask was performed again using the SiON antireflection film as a mask with gas. After dry etching of the silicon nitride (SiN) film quality using the _{CHF 3} /CF _{4 mixed gas as a mask, O 2} ashing and wet stripping process for the remaining hard mask and organic material proceeded.

After hard mask etching and silicon nitride etching, the cross-sections of each specimen were reviewed by V-SEM, and the results are listed in Table 3. As a result of etch evaluation, the pattern shape after hard mask etching and silicon nitride etching did not show bowing in each case and all were good, so the tolerance by the etching process was sufficient, so that the etching process of silicon nitride film quality was performed well. confirmed that.

Sample Pattern shape (after hard mask etch) Pattern shape (after SiN etching) Example 2 vertical shape vertical shape Example 3 vertical shape vertical shape Example 5 vertical shape vertical shape Comparative Example slightly boeing-shaped boeing shape

Claims (6)

(a) a polymer comprising any one of the following Chemical Formulas 2-3, 2-4, 2-6, and 2-7 or a copolymer mixture comprising the same; and
(b) an organic solvent;
An anti-reflective hard mask composition comprising a.

delete The method of claim 1,
The hard mask composition is an anti-reflective hard mask composition further comprising a crosslinking agent and an acid (acid) catalyst component. 4. The method of claim 3,
The hard mask composition,
(a) 1-30 wt% of a polymer or a mixture of these copolymers comprising the indole derivative;
(b) 0.1-5% by weight of a crosslinking agent component;
(c) 0.001 to 0.05% by weight of an acid catalyst; and
(d) an anti-reflective hard mask composition comprising a total of 100% by weight using an organic solvent as the remaining component. 5. The method of claim 3 or 4,
The crosslinking agent is methoxymethylated glycoluril, butoxymethyl glycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, meth An anti-reflective hard mask composition which is any one selected from the group consisting of thoxymethylated thiourea compounds. 5. The method of claim 3 or 4,
The acid catalyst is p-toluenesulfonic acid monohydrate (p-toluenesulfonic acid monohydrate), pyridinium p-toluene sulfonate (Pyridinium p-toluene sulfonate), 2,4,4,6-tetrabromocyclohexadienone, benzo An antireflective hardmask composition selected from the group consisting of phosphorus tosylate, 2-nitrobenzyl tosylate and alkyl esters of organic sulfonic acids.