KR102191919B1 - A composition of anti-reflective hardmask containing benzocarbazole derivatives - Google Patents

Abstract

The present invention provides an anti-reflective hardmask composition comprising: (a) a polymer consisting of a benzocarbazole derivative represented by chemical formula 1 or a polymer blend comprising the same; and (b) an organic solvent.

Description

Anti-reflection hard mask composition containing benzocarbazole derivatives {A COMPOSITION OF ANTI-REFLECTIVE HARDMASK CONTAINING BENZOCARBAZOLE DERIVATIVES}

The present invention relates to a hardmask composition having antireflection properties useful in a lithographic process, and to a benzocarbazole-based aromatic ring-containing polymer having strong absorption in an ultraviolet wavelength range, and a hardmask composition comprising the same. .

In recent years, as the semiconductor industry increasingly requires microscopic processes, an effective lithographic process is essential to realize such ultra-fine technology. In particular, there is an increasing demand for a new material for a hardmask process that is very essential in the etching process.

In general, the hardmask film quality serves as an interlayer that transfers a fine pattern of a photoresist to a lower substrate layer through a selective etching process. Therefore, the hard mask layer is required to have properties such as chemical resistance, heat resistance, and etching resistance to withstand multiple etching processes. The existing hard mask film quality was made of an amorphous carbon layer (ACL) film made by chemical vapor deposition (CVD). The disadvantages of this are high cost equipment investment and particle and film quality opaque. There were many very inconvenient points to use due to photo alignment problems, etc.

Recently, instead of the chemical vapor deposition method, a spin-on hardmask method formed by a spin-on coating method has been introduced. In the spin-on coating method, a hardmask composition is formed using an organic polymer material having solubility in a solvent, and the most important characteristic is that an organic polymer coating film having both etching resistance must be formed.

However, the characteristics of solubility and etching resistance, which are two properties required for the organic hardmask layer, are in conflict with each other, so a hardmask composition capable of satisfying all of them was required. While satisfying the characteristics of these organic hardmask materials, materials introduced into the semiconductor lithographic process have been recently introduced (Publication Patent 10-2009-0120827, Publication 10-2008-0107210, Patent WO 2013100365 A1), which is These were hard mask materials using a copolymer having an appropriate high molecular weight synthesized by the conventional phenol resin manufacturing method using ren (hydroxypyrene).

However, as the recent semiconductor lithographic process goes through a further refinement process, in the case of such an organic hardmask material, it is difficult to sufficiently perform the role of a mask due to the lack of etching selectivity in the etching process compared to the conventional inorganic hardmask material. Came. Therefore, there is an urgent need to introduce an organic hardmask material 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 containing the same.

An object of the present invention is to provide a novel hardmask polymer that can be used to perform a lithographic technique, and a composition comprising the same, since reflectivity between a resist and a back layer can be minimized.

The hardmask composition according to the present invention comprises: (a) a copolymer including a benzocarbazole derivative unit represented by the following formula (1) or a mixture of these copolymers; And

(b) an organic solvent;

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

[Formula 1]

The benzocarbazole aromatic moiety of the benzocarbazole derivative unit of Formula 1 may preferably be in any of the following forms.

The hardmask composition based on the benzocarbazole-based copolymer according to the present invention has a very high carbon content in the polymer and a structure that does not contain oxygen, so the value of the Ohnishi parameter predicting etch resistance is very low, so it is very low in etch resistance. It is an advantageous structure. In terms of the polymer structure, the packing density is very high, so when a thin film is formed, the film density increases and the etching resistance is very excellent. Accordingly, since the etching selectivity is high compared to the existing organic hard mask, the resistance to multiple etching is sufficient, and a lithographic structure having excellent pattern evaluation results can be provided.

The hard mask composition based on the benzocarbazole-based polymer according to the embodiments of the present invention is an antireflection film in the Deep UV region such as ArF (193 nm) and KrF (248 nm) when forming a film, and has a useful range of refractive index and absorption, Reflectivity between the and the back layer can be minimized.

According to the present invention, a copolymer including a benzocarbazole derivative unit represented by the following formula (1) or a mixture of these copolymers; And

(b) an organic solvent; There is provided an anti-reflection hardmask composition comprising a.

[Formula 1]

In the above formula, n represents 0 and 1, and A represents a benzene ring.

R1 is hydrogen or a C6-C20 aryl group which may be substituted with a halogen group, a nitro group, an amino group, a phenyl group, or a hydroxyl group, and R2 is hydrogen or a C1-C10 alkyl group, a C2-C10 alkenyl group, C6 It is a combination of these which may contain an aryl group of ~ C20, or an ether bond, a ketone bond, or an ester bond.

R3 is hydrogen, a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C6 to C20 aryl group, or a C6 to C20 aryl group which may be substituted with a hydroxyl group, fluorine or nitrile group, and R4 is hydrogen, C1 to C10 Alkyl group of, C2 to C10 alkenyl group, C6 to C20 aryl group or C6 to C20 aryl group which may be substituted with a hydroxyl group, fluorine or nitrile group, and R3 and R4 form a ring with the carbon atom to which they are bonded. You may be doing it.

Here, the aromatic benzocarbazole portion of the benzocarbazole derivative unit may preferably be in any one of the following forms.

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

The copolymer having the structure of Formula 1 may have the form of Formula 2 of Formulas 2-1 to 2-9 and Formula 3 of Formulas 3-1 to 3-9, for example.

[Formula 2]

[Formula 3]

The polymers may be used in combination with a novolac resin or aromatic C6 to C20 novolac polymers having a hydroxyl group in order to improve the solubility and coating properties or curing properties of the entire hardmask composition.

On the other hand, in order to make a hardmask composition, the (a) copolymer containing a benzocarbazole-based unit is preferably used in an amount of 1 to 30% by weight based on 100 parts by weight of the (b) organic solvent used. When the benzocarbazole-based copolymer (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, making it difficult to match the exact coating thickness.

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

In addition, the antireflection 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 hardmask 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 thermally activated. It is preferably an acid catalyst to be used.

The (c) crosslinking agent component used in the hardmask composition of the present invention is not particularly limited as long as it is a crosslinking agent capable of reacting with the aromatic ring-containing polymer in a manner that can be catalytically functionalized by the produced acid. Examples of the crosslinking agent include melamine-based, substituted urea-based, or polymers thereof. Preferably, it is a crosslinking agent having at least two crosslinking substituents, methoxymethylated glycoluril, butoxymethylglycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, These are compounds such as methoxymethylated urea, butoxymethylated urea, and methoxymethylated thiourea.

Further, a crosslinking agent having high heat resistance can be used as the crosslinking agent, but a compound containing a crosslinking substituent having an aromatic ring in the molecule can be preferably used. These compounds may exemplify compounds in the form of the following structural formula.

As the (d) acid catalyst used in the hardmask composition of the present invention, an organic acid such as p-toluenesulfonic acid monohydrate may be used, and TAG (Thermal Acid Generator) having storage stability A system compound can also be used as a catalyst. TAG is an acid generator compound designed to release an acid during 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.

When the final hardmask composition further comprises (c) a crosslinking agent component and (d) an acid catalyst, the hardmask composition of the present invention comprises (a) a benzocarbazole-based copolymer having strong absorption properties in the ultraviolet region or A mixture of these copolymers (blend) 1 to 30% by weight, 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) an acid catalyst 0.001 to 0.05% 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 components, preferably containing 75 to 98% by weight of an organic solvent It is desirable.

Here, when the benzocarbazole-based aromatic ring-containing polymer is less than 1% by weight or more than 30% by weight, it becomes less than or exceeds the desired coating thickness, making it difficult to match the exact coating thickness.

In addition, 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 excessive injection.

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

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

Example-1)

In a 100 mL round flask, 5 g (23 mmol) of benzocarbazole, 2.5 g (23 mmol) of benzaldehyde, and 0.6 g of paratoluenesulfonic acid monohydrate (PTSA) were dissolved in 19 g of 1,4-dioxane, and then at a temperature of 110°C. It was polymerized for 10 hours.

After the polymerization was completed, the reaction product was precipitated in an excess of methanol/water (9:1) 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.

High molecular weight average molecular weight (Mw) 2,500, polydispersity (Mw/Mn) 1.56 results were obtained.

Example-2)

5 g (23 mmol) of benzocarbazole and 3.6 g (23 mmol) of 2-naphthylaldehyde were synthesized 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 1.66 were obtained.

Example-3)

5 g (23 mmol) of benzocarbazole and 5.3 g (23 mmol) of 1-pyrenecarboaldehyde were synthesized in the same manner as in Example 1. After polymer purification, a weight average molecular weight (Mw) of 1,700 and a polydispersity (Mw/Mn) of 1.63 were obtained.

Example-4)

5 g (23 mmol) of benzocarbazole, 4.2 g (18 mmol) of 1-pyrenecarboaldehyde, and 0.53 g (5 mmol) of benzaldehyde were synthesized in the same manner as in Example 1. After polymer purification, a weight average molecular weight (Mw) of 2,000 and a polydispersity (Mw/Mn) of 1.55 were obtained.

Example-5)

5 g (23 mmol) of benzocarbazole and 4.1 g (23 mmol) of 9-fluorenone were synthesized 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 1.61 were obtained.

Example-6)

Dibenzocarbazole 5.3 g (20 mmol) and benzaldehyde 2.1 g (20 mmol) were synthesized in the same manner as in Example 1. After polymer purification, a weight average molecular weight (Mw) of 1,900 and a polydispersity (Mw/Mn) of 1.65 results were obtained.

Example-7)

Dibenzocarbazole 5.3g (20mmol), 9-fluorenone 3.6g (20mmol) to synthesize a polymer in the same manner as in Example 1. After polymer purification, a weight average molecular weight (Mw) of 1,400 and a polydispersity (Mw/Mn) of 1.61 were obtained.

Example-8)

Dibenzocarbazole 5.3 g (20 mmol) and 1-pyrenylaldehyde 4.6 g (20 mmol) were synthesized in the same manner as in Example 1. After polymer purification, a weight average molecular weight (Mw) of 1,400 and a polydispersity (Mw/Mn) of 1.61 were obtained.

Example-9)

Dibenzocarbazole 5.3 g (20 mmol), 1-pyrenylaldehyde 3.5 g (15 mmol), and benzaldehyde 0.53 g (5 mmol) were synthesized in the same manner as in Example 1. After polymer purification, a weight average molecular weight (Mw) of 1,400 and a polydispersity (Mw/Mn) of 1.61 were obtained.

Comparative Example) Synthesis of phenolic polymer

After dissolving 35 g (100 mmol) of 9,9-bishydroxyphenylfluorene and 11.7 g (110 mmol) of benzaldehyde in 109 g of PGMEA, 1 g 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 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 the surfactant prepared in Examples 1 to 9 and Comparative Examples were completely dissolved in 7 g of propylene glycol monomethyl ether acetate (PGMEA) and 2 g of cyclohexanone, and then filtered using a 0.1 um melbrain filter. Thus, the sample solutions of Examples 1 to 9 and Comparative Examples were prepared, respectively.

The sample solutions prepared according to Examples 1 to 9 and Comparative Examples were 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, the refractive index n and the extinction coefficient k of the formed films were obtained, respectively. The device used was Ellipsometer (J. A. Woollam), and the measurement results are shown in Table 1.

As a result of the evaluation, it was confirmed that there is a refractive index and absorbance that can be used as an antireflection film at ArF (193 nm) and KrF (248 nm) wavelengths. In general, the refractive index range of the material used as the semiconductor antireflection 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 hardmask composition according to the embodiments can be used as an antireflection film.

Sample type Optical characteristics (193nm) Optical characteristics (248nm) Refractive index (n) Extinction coefficient (k) Refractive index (n) Extinction coefficient (k) Example 1 1.48 0.58 1.73 0.53 Example 2 1.50 0.60 1.75 0.53 Example 3 1.49 0.63 1.72 0.52 Example 4 1.52 0.61 1.74 0.55 Example 5 1.54 0.65 1.73 0.57 Example 6 1.53 0.71 1.75 0.58 Example 7 1.52 0.69 1.75 0.57 Example 8 1.54 0.65 1.73 0.54 Example 9 1.55 0.67 1.75 0.56 Comparative Example 1.48 0.68 1.95 0.35

Lithographic evaluation of antireflective hardmask composition

The sample solutions prepared in Examples 1, 3, 4, 6 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.

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

Sample type Pattern characteristics EL margin
(△mJ/energy mJ) DoF margin
(㎛) Pattern shape Example 1 0.4 0.4 cubic Example 3 0.3 0.3 cubic Example 4 0.4 0.3 cubic Example 6 0.4 0.4 cubic Comparative Production Example 0.2 0.2 undercut

Etching Characteristics Evaluation of Antireflective Hard Mask Composition

In Examples 3, 4, 6, and Comparative Examples, each patterned specimen was subjected to dry etching of the lower SiON antireflection film (BARC) with 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 gas as a mask. Afterwards, dry etching the silicon nitride (SiN) film quality by using the hard mask as a mask with CHF ₃ /CF ₄ mixed gas, and then O ₂ ashing and wet stripping process for the remaining hard mask and organic matter. Proceeded.

Immediately after hardmask etching and silicon nitride etching, the cross-sections of each specimen were examined with V-SEM, and the results are listed in Table 3. As a result of the etch evaluation, the pattern shape after hard mask etching and silicon nitride etching in each case did not show any bowing phenomenon, and both had good resistance due to the etching process. Confirmed.

Sample Pattern shape (after hard mask etching) Pattern shape (after SiN etching) Example 3 Vertical shape Vertical shape Example 4 Vertical shape Vertical shape Example 6 Vertical shape Vertical shape Comparative Example A little boeing Boeing

Claims (7)

(a) a copolymer including a benzocarbazole derivative unit represented by the following Formula 1-1 or Formula 1-2, or a mixture of these copolymers; And
(b) an organic solvent;
Anti-reflection hardmask composition comprising a.
[Formula 1-1]

[Formula 1-2]

In Formula 1-1,
R1 is hydrogen or a combination of these, which may contain a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C6 to C20 aryl group, or an ether bond, a ketone bond, or an ester bond,
R2 is hydrogen, a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C6 to C20 aryl group or a C6 to C20 aryl group which may be substituted with a hydroxyl group, fluorine, or nitrile group,
R3 is hydrogen, a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C6 to C20 aryl group or a C6 to C20 aryl group which may be substituted with a hydroxyl group, fluorine, or nitrile group, and R2 and R3 are bonded to them. It may not form a ring with a carbon atom and cannot be an aryl group at the same time, and this aryl group may be a C6 to C20 aryl group or a C6 to C20 aryl group which may be substituted with a hydroxyl group, fluorine, or nitrile group. to be.

In Formula 1-2,
R1 is hydrogen or a combination of these, which may contain a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C6 to C20 aryl group, or an ether bond, a ketone bond, or an ester bond,
R2 is hydrogen, a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C6 to C20 aryl group or a C6 to C20 aryl group which may be substituted with a hydroxyl group, fluorine, or nitrile group,
R3 is hydrogen, a C1 to C10 alkyl group, a C2 to C10 alkenyl group, a C6 to C20 aryl group or a C6 to C20 aryl group which may be substituted with a hydroxyl group, fluorine or nitrile group, and R2 and R3 are bonded to A ring may be formed with the carbon atom to be formed.
The method of claim 1,
Wherein n is 0, R2 is a hydrogen atom, anti-reflection hardmask composition.
The method of claim 1,
N is 1, R2 is a hydrogen atom, antireflection hard mask composition.
The method of claim 1,
The hardmask composition is an antireflection hardmask composition further comprising a crosslinking agent and an acid catalyst component.
The method of claim 4,
The hard mask composition,
(a) 1 to 30% by weight of a polymer containing the benzocarbazole derivative or a blend of these polymers;
(b) 0.1 to 5% by weight of a crosslinking agent component;
(c) 0.001 to 0.05% by weight of an acid catalyst; And
(d) An antireflection hard mask composition comprising a total of 100% by weight using an organic solvent as the remaining component.
The method according to claim 4 or 5,
The crosslinking agent is methoxymethylated glycoluril, butoxymethylglycoluril, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, me Antireflection hard mask composition which is any one selected from the group consisting of oxymethylated thiourea compounds.
The method according to claim 4 or 5,
The acid catalyst is p-toluenesulfonic acid monohydrate, 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.