KR20160071639A - New polymers of bottom anti-reflective coating, and composition using same - Google Patents

Abstract

The present invention relates to a novel polymer for bottom anti-reflective coating, and a composition using the same. A monomer is synthesized by using an aromatic chromophore having a nitro group as a novel anti-reflective coating; a new-type anti-reflection coating composition can be obtained by synthesizing a polymer compound having a copolymer shape with a maleic anhydride using the monomer; and highly excellent etching properties are shown.

Description

TECHNICAL FIELD [0001] The present invention relates to a polymer for a bottom anti-reflective coating and a composition using the same,

Bottom Anti-Reflective Coating for Semiconductor and Display

As demand for micropatterning and process simplification increases in semiconductor lithography processes, there is a growing demand for new bottom anti-reflective coatings.

Generally, the antireflection film prevents the standing wave or notching (lateral fringing) phenomenon due to irregular reflection of light in the underlying film quality when the photoresist patterning is performed, thereby realizing a clear pattern profile and simultaneously increasing the pattern resolution. It consists mainly of a catalyst that causes a curing reaction to prevent intermixing of photoresist solutions with chromophore substituents that can absorb light.

In the case of conventional antireflection film polymers, the antireflection film functions by introducing naphthalene (see US Pat. No. 6,999,269) or anthracene (see US Pat. No. US6486283) into the polymer chain, Is that the etch selectivity in the subsequent etching process with the photoresist by the high density carbon component of the chromophore substituent is seriously bad. In general, the naphthalene-based antireflection film has an etch rate of about 1 to 1.5 times that of the photoresist. In order to remove the antireflection film in the etching process, the photoresist film is etched together with the inorganic film to be etched. it becomes difficult to perform a sufficient mask function for the polygon (e.g., poly, etc.).

In the present invention, an antireflection film composition having an etch selectivity that is superior to that of a conventional antireflection film is developed by overcoming the drawbacks of the etch selectivity of existing antireflection film materials and synthesizing materials having new functions.

The present invention relates to a polymer for a bottom anti-reflective coating in a semiconductor lithography process and an antireflection film composition using the same. The antireflection film composition described herein can be widely used in various wavelength regions. In particular, it can be used together in the regions of 193 nm and 248 nm. It has etch selectivity to photoresist film compared to conventional antireflection films, It is an advantage to exhibit very excellent characteristics in characteristics.

Another feature of the antireflection film composition of the present invention is that a hardening agent is used for the curing reaction of the polymer film or a curing reaction occurs without using a strong acid, so that the intermixing phenomenon does not occur in the photoresist solution.

In order to realize such antireflection film characteristics, the following polymer structure has been developed and basically has a polymer structure composed of a copolymer of an aromatic vinyl monomer having a nitro substituent and maleic anhydride.

More specifically, the polymer structure of the present invention is in the form of a polymer comprising a copolymer of a vinyl monomer (X) having at least one nitro group in a chromophore aromatic compound and maleic anhydride.

Herein, m is mainly 0 or 1, and X is a monomer having vinyl form and can form a copolymer with maleic anhydride. Vinyl ether, acrylate, methacrylate, acrylamide and methacrylamide can be used. Preferably, the monomer is in the form of acrylate or methacrylate. The proportion of the monomer used is between 10 and 70%, more preferably between 20 and 50% of the total molar ratio of the polymer.

On the other hand, the molecular weight range mainly has a mass average molecular weight (Mw) of between 2,000 and 50,000, and more preferably between 3,000 and 15,000.

In the above-mentioned polymer structure, Z is a linkage between a vinyl monomer X and an aromatic chromophore, and is mainly linked to an ether, an ester, and an amino group. Here, R1 and R2 may be the same or different and are substituents having hydrogen, alcohol, halogen, nitro, and alkyl group, and preferably have a substituent mainly in the form of nitro or alcohol.

In the present invention, these aromatic nitro monomers have a very advantageous advantage in the patterning process using a photoresist, and exhibit a high light absorption rate (absorption coefficient, k> 0.2) in two wavelength regions (193 nm and 248 nm) Can be used in both ArF (193 nm) and KrF (248 nm) regions, and has an effect of raising the refractive index (n). Thus, it has excellent characteristics as an antireflection film in the patterning process.

In addition, the greatest advantage of the antireflection film composition of the present invention is that the high oxygen content of the nitro compound has a high etch selectivity with the photoresist film in the subsequent etching process. In general, the most important function of the antireflective film is to easily remove the photoresist film from the etch process after patterning, and the remaining photoresist acts as a mask sufficient for etching the underlying film (silicon oxide, silicon nitride, poly, etc.) It should be possible. For this purpose, the polymeric materials used as the antireflection film are mainly composed of polymeric materials having a high oxygen content including a chromophore substituent. In the case of methacrylate, polyester, and polyether, materials having a high oxygen content relative to the photoresist film are used.

In order to show such a high etch selectivity in the antireflection film, the higher the content of oxygen atoms relative to carbon atoms in the unit polymer, the higher the etch selectivity. This is mainly due to the Ohnishi parameter (O / P), and the higher the oxygen content per unit molecule is, the higher the O / P value is, and the higher the etch selectivity in the photoresist etching.

In the present invention, a new type of polymer material has been developed in order to realize a high etch selectivity in such an antireflection film. This is a polymer having a vinyl monomer having an aromatic chromophore having at least one nitro group and a copolymer of maleic anhydride These polymers have a very high oxygen content relative to the oxygen content of conventional antireflection film polymers in the unit polymer chain.

In addition, the antireflection film composition of the present invention is a polymer capable of causing a curing reaction itself in comparison with the use of a crosslinker in the presence of a strong acid in the curing reaction in order to prevent intermixing with a photoresist solution Structure, it is possible to avoid the side effects of storage stability due to the addition of strong acid in the antireflection film composition, so that it can be stored at room temperature for a long time.

Accordingly, the effect of the present invention will be described in more detail through a specific embodiment of the present invention.

A polymer resin was synthesized using an aromatic compound having a nitro group as a chromophore. In order to cause a curing reaction at high temperature treatment, a polymer resin in the form of a copolymer with a maleic anhydride monomer was synthesized, A barrier film composition could be produced.

The most significant effect of the present invention is that it has a high etch selectivity with a photoresist film in a subsequent etching process due to the high oxygen content of the nitro compound and also has a high light absorption rate in two wavelength regions (193 nm, 248 nm) (Absorption coefficient, k> 0.2) and can be used in both ArF (193 nm) and KrF (248 nm) regions.

In addition, the antireflection film composition of the present invention is a polymer capable of causing a curing reaction itself in comparison with the use of a crosslinker in the presence of a strong acid in the curing reaction in order to prevent intermixing with a photoresist solution Structure, it is possible to avoid the side effects of storage stability due to addition of strong acid in the antireflection film composition, so that it can be stored at room temperature for a longer time.

Figure 1. Polymer FT-IR spectra (red: before reaction, black: after reaction) in Examples 3-8.

III. Example of Monomer and Polymer Synthesis

3-1. Methacrylate monomer (MI) synthesis

- Dibutyltin methacrylate (HEMA) (41.6 g) was dissolved in 600 g of THF together with 30 g of triethylamine (30 g), and the dinitrobenzoyl chloride (67 g) was slowly dropped in an ice-bath. For about 30 minutes and react at 60 ° C for about 4 hours.

- After the reaction was completed, the resulting salt was filtered and excess THF was transferred to a rotary evaporator, and the product was obtained by column chromatography (n-hexane: ethyl acetate = 2: 1). (Yield: 90%)

3-2. Acrylate monomer (M-II) synthesis

- Dissolve HEA (2-hydroxyethyl acrylate) (33.7 g) in TEA (triethylamine) (26.5 g) in a 1000 ml flask in 600 g of THF and slowly drop the dinitrobenzoyl chloride (60 g) in an ice bath After reacting at room temperature for about 30 minutes, react at 60 ℃ for 4 hours.

- After the reaction was completed, the resulting salt was filtered and excess THF was transferred to a rotary evaporator, and the product was obtained by column chromatography (n-hexane: ethyl acetate = 2: 1). (Yield: 91%)

3-3. Polymer synthesis

- In a round flask, methacrylate monomer MI (12 mmol, 3.9 g), HEA (6 mmol, 0.7 g) and MAA (6 mmol, 0.52 g) synthesized above were dissolved in propylene glycol monomethyl ether acetate ) And 10 g of cyclohexanone CH (cyclohexanone) 10 g. Then, AIBN (azoisobutyronitrile) (4 mol%) is added thereto and sufficiently degassed in a nitrogen atmosphere, followed by reaction at 80 ° C. for 5 hours.

After the reaction was completed, a polymer having a mass average molecular weight (Mw) of 21,700 was obtained.

3-4. Polymer synthesis

- (9 g) / CH (9 g), methacrylate monomer (10 mmol, 3.2 g), MA (maleimidhydride) (10 mmol, 0.98 g) and MAA (methacrylic acid) (6 mmol, 0.52 g) synthesized above were placed in a round- After dissolving in a co-solvent, AIBN (3 mol%) is added thereto, degassed sufficiently in a nitrogen atmosphere, and reacted at 80 ° C. for 5 hours.

After the reaction was completed, a polymer having a mass average molecular weight (Mw) of 6,400 was obtained.

3-5. Polymer synthesis

- (50 mmol) of methacrylate monomer (60 mmol, 19.5 g), MA (maleic anhydride) (90 mmol, 8.8 g) synthesized above and 30 mmol (2.1 g) After dissolving in a co-solvent, AIBN (2 mol%) is added thereto and sufficiently degassed in a nitrogen atmosphere, followed by reaction at 80 ° C. for 5 hours.

After the reaction was completed, a polymer having a mass average molecular weight (Mw) of 8,500 was obtained.

3-6. Polymer synthesis

- (10 mmol, 3.1 g), MA (15 mmol, 1.47 g) and AA (5 mmol, 0.36 g) were dissolved in PGMEA (10 g) and CH (10 g) co-solvent in a round- , AIBN (2 mol%) was added thereto, and degassed sufficiently in a nitrogen atmosphere, followed by reaction at 80 ° C. for 5 hours.

- After the reaction was completed, a polymer having a mass average molecular weight (Mw) of 9,800 was obtained.

3-7. Polymer synthesis

- 10 mmol of maleic anhydride (10 mmol, 0.98 g) and 2-hydroxyethyl methacrylate (HEMA) (10 mmol, 1.3 g) were added to a round flask with 10 g of PGMEA and 10 g of CH , And then AIBN (4 mol%) was added thereto. After degassing sufficiently in a nitrogen atmosphere, the reaction was carried out at 80 ° C. for 5 hours.

After the reaction was completed, a polymer having a mass average molecular weight (Mw) of 4,600 was obtained.

3-8. Polymer synthesis

- GMA (80 mmol, 11.4 g) and MA (maleic anhydride) (80 mmol, 7.84 g) were dissolved in a PGMEA 40 g and CH 40 g co-solvent, and AIBN (6 mol%) was added thereto in a 250 ml flask. After degassing sufficiently, react at 80 ° C for 5 hours.

- After the polymerization, DNB (dinitrobenzoic acid) (16.8g) and BTEAC (benzyltriethylammonium chloride) (0.16g) were added to the polymer solution at room temperature, and 40g of PGMEA and 40g of CH were further added. Respectively.

- After the reaction was completed, the polymer synthesized by GPC and FTIR was confirmed. The final mass average molecular weight (Mw) was 6,000 and hydroxyl (OH) and nitro (NO2) peaks were observed on FTIR.

Through the above examples, polymers having nitro groups in various aromatic rings can be synthesized. They can be synthesized by reacting with a chromophore compound having carboxylic acid, sulfonic acid, hydroxy, amino functional group in an aromatic ring. More specifically, a polymer reaction can be performed using a nitro compound such as benzoic acid, salicylic acid, phenol, or aniline. In this case, a maleic anhydride may participate in a partial reaction to obtain a carboxylic acid type polymer.

In the synthesis of a copolymer of an aromatic compound having a nitro group and maleic anhydride, the weight average molecular weight is controlled by adjusting the amount of a radical initiator. The amount of the catalyst is about 1 to 10% of the molar ratio of the polymer use. In some cases, a chain-transfer agent may be used to obtain a lower molecular weight. The mass average molecular weight can be controlled mainly by using n-butyl mercaptan or n-octyl mercaptan.

In the case of the antireflection film polymer of the present invention, the weight average molecular weight ranges from about 2,000 to about 50,000, preferably from about 3,000 to about 15,000.

In addition, the content of the nitroaromatic chromophore in the polymer synthesized in the above various examples is between 10 and 70%, preferably between 20 and 50% of the total polymer molar ratio.

IV. Antireflection film composition

The antireflection film composition of the present invention can act as an antireflection film due to its own curing reaction when heated at a temperature of 150 to 200 ° C for 60 to 90 seconds using only the polymers and solvents synthesized in the above examples. If necessary, a curing reaction may be carried out by adding a catalytic amount of pyridinium p-toluenesulfonate (PPTS). In addition, a curing reaction may be performed by adding a crosslinker such as glycoluril, triglycidyl isocyanurate and the like. At this time, the content of the curing agent to be added is usually in the range of 5 to 50%, preferably 20 to 40%, of the total weight of the polymer.

The solvent used is mainly propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone (CH), and methyl isobutyl ketone (MIBK). At this time, the content of the solvent to be used depends on the thickness of the antireflection film to be applied, and it is mainly between 70 and 95% of the total antireflection film solution weight ratio.

4-1. Antireflection Film Composition Example (MA47)

- 1 g of the polymer (MI / MA / MAA = 5/5/3) synthesized in Example 3-4, 0.3 g of glycoluril and 0.5 g of PPTS (pyridinium p-toluenesulfonate) were added to PGMEA (6 g) / CH ) Dissolve completely in the co-solvent and filter it with a 0.1um filter.

- The solution is spin-coated at 1500 rpm and pre-baked at 110 ° C for 60 seconds, followed by hard bake at 200 ° C for 60 seconds.

- The thickness of the coated antireflection coating was measured by using an elipsometer. The thickness was 2100 A, the refractive index (n) was 1.63, and the absorption coefficient (k) was 0.22.

4-2. Antireflection Film Composition Example (MA55)

- 1 g of the polymer (MI / MA / MAA = 2/3/1) synthesized in Example 3-4, 0.3 g of glycoluril and 0.5 wt% of PPTS were completely dissolved in PGMEA (6 g) / CH The thickness was 2230 A, the refractive index (n) was 1.74, and the absorption coefficient (k) was 0.20 as a result.

4-3. Antireflection Film Composition Example (MA62)

1 g of the polymer synthesized in Example 3-5 (MI / MA / AA = 3/4/1) was completely dissolved in a co-solvent of PGMEA (4 g) / CH (4 g) (N) = 1.84, and the absorption coefficient (k) = 0.34.

4-4. Antireflection Film Composition Example (MA63)

1 g of the polymer synthesized in Example 3-5 (MI / MA / AA = 2/3/1) was completely dissolved in a co-solvent of PGMEA (6 g) / CH (5 g) (N) = 1.73, and the absorption coefficient (k) = 0.24.

4-5. Antireflection Film Composition Example (MA68)

1 g of the polymer synthesized in Example 3-5 (MI / MA / AA = 1/2/1) was completely dissolved in a co-solvent of PGMEA (5 g) / CH (5 g) , The thickness was 1370 A, the refractive index (n) was 1.75, and the absorption coefficient (k) was 0.19.

4-6. Antireflection Film Composition Example (MA63-G)

- 1 g of the polymer synthesized in Example 3-5 (MI / MA / AA = 2/3/1), 0.35 g of glycoluril and 0.5 wt% of PPTS (pyridinium p-toluenesulfonate) (N) = 1.67, the absorption coefficient (k) = 0.23, and the thickness of the elipsometer was measured as follows: thickness = 2940 A; refractive index Value.

4-7. Antireflection Film Composition Example (GMA-G)

1 g of the polymer synthesized in Example 3-8, 0.3 g of glycoluril and 0.5 g of PPTS (pyridinium p-toluenesulfonate) were completely dissolved in a co-solvent of PGMEA (5 g) / CH (5 g) The thickness of the elipsometer was measured to be 2534A, refractive index (n) = 1.68, and absorption coefficient (k) = 0.12.

The results of the physical properties of the respective compositions are summarized as follows.

Polymer composition Hardener (%) The refractive index (n) Absorption coefficient (k) Example 4-1 M-I / MA / MAA = 5/5/3 30 1.63 0.22 Example 4-2 M-I / MA / MAA = 2/3/1 30 1.74 0.20 Example 4-3 M-I / MA / AA = 3/4/1 0 1.84 0.34 Example 4-4 M-I / MA / AA = 2/3/1 0 1.73 0.24 Example 4-5 M-I / MA / AA = 1/2/1 0 1.75 0.19 Examples 4-6 M-I / MA / AA = 2/3/1 35 1.67 0.23 Examples 4-7 GMA / MA 30 1.68 0.12

4-8. Compatibility with photoresist solution and comparison of etching characteristics

In order to confirm the intermixing of the antireflection film composition of the present invention with the photoresist solution, each composition was spin-coated on a bare Si wafer and subjected to a high-temperature bake process. Thereafter, PGMEA or CH used as a resist solution And the surface was soaked for about 3 minutes while spraying on the wafer, and the presence or absence of dissolution of the antireflection coating film was confirmed.

In order to confirm the progress of the curing reaction of the antireflection film, a 2.34 wt% solution of TMAH (tetramethylammonium hydroxide) using a high-temperature antireflection coating film as a resist developer was dipped for about 60 seconds, Respectively.

Solubility results for each composition are summarized in the table below.

Polymer composition PGMEA Solubility CH solubility TMAH solubility Example 4-1 M-I / MA / MAA = 5/5/3 Not recording Not recording Not recording Example 4-2 M-I / MA / MAA = 2/3/1 Not recording Not recording Not recording Example 4-3 M-I / MA / AA = 3/4/1 Not recording Not recording Not recording Example 4-4 M-I / MA / AA = 2/3/1 Not recording Not recording Not recording Example 4-5 M-I / MA / AA = 1/2/1 Not recording Not recording Not recording Examples 4-6 M-I / MA / AA = 2/3/1 Not recording Not recording Not recording Examples 4-7 GMA / MA Not recording Not recording Not recording Comparative Example Poly (ST / MAA = 7/3) record record record

In order to determine how fast the etch rate is in the etching process than that of the photoresist film for each antireflection film composition, each antireflection film coating film was prepared, and CF4 80sccm / CHF3 20sccm / O2 5sccm process condition (5mtorr / 400Ws / 150Wb ) For 30 seconds, and the final etch rate was confirmed by confirming the change of each thickness.

The etch results for each coating are summarized in the table below.

Polymer composition Hardener (%) Etch speed (? / Sec) Selection ratio Example 4-1 M-I / MA / MAA = 5/5/3 30 65.6 2.80 Example 4-2 M-I / MA / MAA = 2/3/1 30 63.0 2.69 Example 4-3 M-I / MA / AA = 3/4/1 0 61.4 2.62 Example 4-4 M-I / MA / AA = 2/3/1 0 66.7 2.84 Example 4-5 M-I / MA / AA = 1/2/1 0 43.1 1.84 Examples 4-6 M-I / MA / AA = 2/3/1 35 79.2 3.38 Examples 4-7 GMA / MA 30 76.1 3.25 Comparative Example 1 Poly (ST / MAA = 7/3) 0 23.4 1.0 Comparative Example 2 Poly (IBMA / tBMA / HEMA = 2/1/1) 0 38.0 1.62

As described above, it was found that the antireflective coating compositions of the present invention had no compatibility with the photoresist solution and were not soluble in the TMAH developer. It was found that the antireflection film compositions were completely cured by the high temperature bake process.

On the other hand, the comparison of the most important etch characteristics of the antireflection film on the basis of the etch rate of Comparative Example-1 (KrF PR) was about 1.6 times as high as that of Comparative Example-2 (ArF PR) The compositions showed an etch selectivity of about 2.5 to 3.4 times. As a result, it was confirmed that the antireflection film compositions of the present invention had a significantly higher etch rate than the photoresist film.

MA: maleic anhydride
MAA: methacrylic acid
AA: acrylic acid
GMA: glycidyl methacrylate

Claims (6)

 A novel polymer comprising an aromatic compound having a nitro group as a novel chromophore substituent for a planarization or antireflection film function in a microlithography process, and an antireflection film coating composition using the same. A polymer structure having a polymer structure in which at least one nitro group is substituted with an aromatic ring structure and a maleic anhydride copolymer having the following structure.

Where m is 0, 1, X is a monomer having vinyl form, and Z is a linkage between vinyl monomer X and an aromatic chromophore. And R1 and R2 may be the same or different and are substituents having hydrogen, alcohol, halogen, nitro, alkyl, alkoxy group, preferably having a substituent in the form of nitro or alcohol
On the other hand, the molecular weight range mainly has a mass average molecular weight (Mw) of between 2,000 and 50,000, and more preferably between 3,000 and 15,000.  The X mentioned in paragraph 2 can be mainly vinyl ether, acrylate, methacrylate, acrylamide, and methacrylamide. Preferably, acrylate and methacrylate type monomers are used. Here, the content of X ranges from 10 to 70% of the molar ratio of the total polymer. Preferably in the range of usually between 20 and 50%.  Z is a linkage between the chromophore and the polymer main chain. It consists mainly of ether, ester, sulfonate and amino.  The maleic anhydride copolymer referred to in paragraph 2 is composed of a ternary copolymer with other monomers, and mainly acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate and the like can be used. An acid salt catalyst such as a maleic anhydride polymer and a pyridinium p-toluenesulfonate (PPTS), and a solvent. Here, the amount of acid salt used ranges from 0.01 to 3 wt% of the total polymer weight. Preferably between 0.1 and 1 wt%.

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