KR101253292B1 - Photosensitive polymer and photoresist composition including the same - Google Patents

Abstract

Disclosed are photosensitive polymers and chemically amplified photoresist compositions comprising the same which are particularly suitable for photolithography processes using short wavelength exposure sources. The photosensitive polymer includes a repeating unit represented by the following formula.

In the above formula, R ₁ and R ₃ are each independently hydrogen, methyl group or trifluoromethyl group, Q ₁ is a cyclic compound having 4 to 12 carbon atoms containing an ester group or hydroxy, R ₅ is a carbon of 6 to 18 The alkyl ester group, R ₆ is the same as hydrogen, an alkyl group having 1 to 13 carbon atoms, or R ₅ , and a and c are mole% of each repeating unit with respect to all the repeating units constituting the photosensitive polymer, each independently 1 to 99 mol%, n is an integer of 0-12.

Photosensitive Polymer, Photoresist

Description

Photosensitive polymer and photoresist composition comprising same {Photosensitive polymer and photoresist composition including the same}

The present invention relates to a photosensitive polymer and a photoresist composition comprising the same, and more particularly, to a photosensitive polymer and a chemically amplified photoresist composition including the same, which are particularly suitable for a photolithography process using a short wavelength exposure source.

Recently, with the high integration of semiconductor devices, the development of dynamic random access memory (DRAM) having a storage capacity of more than a gigabit level has been actively progressed. In order to manufacture DRAM of 1 gigabit or more, an ultrafine pattern having a line width of 100 nm or less must be formed. To this end, photolithography technology using a short wavelength exposure source such as KrF excimer laser (248 nm) and ArF excimer laser (193 nm) has been introduced, and not only has high resolution in short wavelength exposure sources, but also transparency and dry etching. Research into photoresist compositions excellent in resistance, adhesion to lower film quality, and developability is being actively conducted. In particular, as the pattern becomes finer, the photo and etching process margins must be reduced, thereby improving the transparency of the resist composition, reducing line edge roughness, and decreasing line width variations due to post exposure bake (PEB) temperature. The importance of the back is increasing.

In general, the positive chemically amplified photoresist includes a photoacid generator (PAG) that generates an acid component by exposure and a photosensitive polymer having a protecting group decomposed by the acid component. When the chemically amplified photoresist is exposed, an acid component is generated from the photoacid generator, and the generated acid component serially decomposes the protecting group bonded to the skeleton of the polymer to change the solubility of the polymer. It will form a pattern with a high contrast (contrast). In the photolithography process using the chemically amplified photoresist, a post-exposure heating (PEB) process is performed to activate and diffuse an acid component present in the exposed photoresist. At this time, the heated acid component penetrates into the photoresist of the non-exposed part, thereby increasing the solubility of the non-exposed part, thereby changing the line width of the photoresist pattern, causing the pattern to collapse, and line edge roughness. In addition, the problem of PEB sensitivity according to the post-exposure heating temperature becomes more problematic as the pattern formed is finer.

Accordingly, an object of the present invention is to provide a photoresist polymer and a photoresist composition including the same, which can form a fine photoresist pattern having a better shape on a wafer in response to an exposure source having a short wavelength in a photolithography process. It is.

Another object of the present invention is to provide a photoresist polymer and a photoresist composition comprising the same, which can reduce the line width change of the pattern with increasing temperature after exposure.

In order to achieve the above object, the present invention provides a photosensitive polymer comprising a repeating unit represented by the following formula (1).

 [Formula 1]

In Formula 1, R ₁ and R ₃ are each independently hydrogen, methyl or trifluoromethyl group, Q ₁ is a cyclic compound having 4 to 12 carbon atoms containing an ester group or hydroxy, R ₅ is 6 to 18 carbon atoms Is an alkylester group, R ₆ is the same as hydrogen, an alkyl group having 1 to 13 carbon atoms, or R ₅ , and a and c are mole% of each repeating unit with respect to the total repeating unit constituting the photosensitive polymer, each independently 1 To 99 mol%, n is an integer of 0 to 12.

The present invention also provides a photoresist composition comprising the photosensitive polymer and a method of forming a photoresist pattern using the same.

Hereinafter, the present invention will be described in more detail.

The photosensitive polymer according to the present invention is used in the preparation of a chemically amplified photoresist composition, and is a copolymer developable by an alkali solution, and includes a repeating unit represented by the following Chemical Formula 1.

In Formula 1, R ₁ and R ₃ are each independently hydrogen, a methyl group or a trifluoromethyl group, Q ₁ is a cyclic compound having 4 to 12 carbon atoms containing an ester group or hydroxy, preferably 4 to 12 carbon atoms Is a cycloalkyl group, more preferably a lactone group having 4 to 12 carbon atoms, R ₅ is an alkyl ester group having 6 to 18 carbon atoms, preferably R-OCOCH ₂ CH _2- (wherein R is 4 carbon atoms) Is a secondary or tertiary alkyl group of 15 to 15), R ₆ is the same as hydrogen, an alkyl group having 1 to 13 carbon atoms, or R ₅ , and a and c are all repeating units constituting the photosensitive polymer. As mole% of each repeating unit to, each independently is 1 to 99 mole%, and n is an integer of 0 to 12.

,

,

,

,

,

등의 탄소수 4 내지 12의 락톤(lactone)기,

등의 히드록시 치환된 탄소수 4 내지 12의 고리 화합물을 예시할 수 있다. 상기 R₅의 바람직한 예로는

,

,

,

,

,

,

,

,

,

등의 R-OCOCH₂CH₂-(여기서, R은 탄소수 4 내지 15의 3차(tertiary) 알킬기이다), 또는

,

등의 R-OCOCH₂CH₂-이다(여기서, R은 탄소수 4 내지 15의 2차(secondary) 알킬기이다). 상기 Q₁ 및 R₅에 있어서, 점선 표시는 결합위치를 나타낸다. 또한 R₆가 탄소수 1 내지 13의 알킬기인 경우, 직쇄상 알킬기인 것이 바람직하다.Preferred examples of Q ₁

,

,

,

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,

A lactone group having 4 to 12 carbon atoms such as

Hydroxy substituted C4-C12 ring compounds, such as these, can be illustrated. Preferred examples of R ₅

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,

,

,

,

,

,

,

,

R-OCOCH ₂ CH _2- (where R is a tertiary alkyl group having 4 to 15 carbon atoms), or

,

And R-OCOCH ₂ CH _2- (wherein R is a secondary alkyl group having 4 to 15 carbon atoms). In the above Q ₁ and R ₅ , the dotted line indicates the bonding position. Moreover, when R <_6> is a C1-C13 alkyl group, it is preferable that it is a linear alkyl group.

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The weight average molecular weight (Mw) and the degree of dispersion of the photosensitive polymer copolymer according to the present invention may vary depending on the use, use conditions, and synthetic conditions of the photosensitive polymer, but the weight average molecular weight (Mw) is 3,000 to 100,000, preferably 3,000 to 30,000 and dispersion degree is preferably 1.01 to 3.00. The photosensitive polymer according to the present invention may be prepared by copolymerizing (meth) acrylate monomer components in the presence of a suitable initiator such as azobis (isobutylonitrile) (AIBN) and an organic solvent such as tetrahydrofuran (THF). have. The polymerization reaction is preferably carried out in an inert gas atmosphere such as nitrogen and argon, the preferred reaction temperature is 30 to 70 ℃, the preferred reaction time is 4 to 23 hours. If the weight average molecular weight, the degree of dispersion, and the ratios of a, b, and c are out of the above ranges, the physical properties of the photoresist film may be reduced, the photoresist film may be difficult to form, and the contrast of the pattern may be reduced. Since the photosensitive polymer according to the present invention includes a bulky aliphatic cyclic hydrocarbon, it improves the dry etching resistance of the photoresist. In addition, since the photosensitive polymer has a low activation energy and is easily deprotected by an acid component, post-exposure heating (PEB) may be performed at a relatively low temperature. Therefore, since the diffusion of the acid component to the non-exposed portion and the line width change by the post-exposure heating (PEB) process can be reduced, it is particularly useful for the photolithography process using an exposure source of deep UV.

The photoresist composition according to the present invention comprises a) a photosensitive polymer comprising a repeating unit represented by Chemical Formula 1, b) a photoacid generator (PAG) for generating an acid, and c) an organic solvent. Depending on the various additives may be further included. The content of the photosensitive polymer of Chemical Formula 1 is preferably 1 to 30% by weight based on the total photoresist composition. If the content of the photosensitive polymer is less than 1% by weight, the resist layer remaining after coating is too thin to form a pattern having a desired thickness, and if it exceeds 30% by weight, coating uniformity may be degraded. The photoacid generator generates an acid component such as H ⁺ by exposure to induce chemical amplification, and photoacid generators commonly known in the art may be widely used in the present invention (US Pat. No. 5,212,043, International patent application WO 97/33198 et al.). Specifically, as the photoacid generator, an organic sulfonic acid and / or onium salt-based compound may be used, and in particular, phthalimido trifluoro methane sulfonate and dinitrobenzyltosylate having low absorbance at 157 nm and 193 nm. (dinitrobenzyltosylate), n-decyl disulfone and naphthyl imidotrifluoromethane sulfonate may be used alone or in combination, and may also be used diphenyl iodo salt hexafluoro Phosphate, diphenyl iodo hexafluoroarsenate, diphenyl iodo hexafluoroantimonate, diphenyl paramethoxyphenylsulfonium triflate, diphenyl paratoluenylsulfonium triflate, diphenyl paraisobutyl phenyl sulphate Phosphorium Triflate, Triphenylsulfonium Hexafluoroarsenate, Triphenylsulfo Photoacid generators selected from the group consisting of hexafluoroantimonate, triphenylsulfonium triflate and dibutylnaphthylsulfonium triflate may also be used. The content of the photoacid generator is preferably 0.1 to 20% by weight based on the total photoresist composition. If the content of the photoacid generator is less than 0.1% by weight, the sensitivity of the photoresist to light is weakened, and the amount of acid components generated by exposure is low, which may make it difficult to deprotect the protecting group. The generator absorbs a lot of far ultraviolet rays, the acid is excessively generated, and the cross section of the pattern is not good. As the organic solvent constituting the remaining components of the photoresist composition according to the present invention can be used a wide variety of organic solvents commonly used in the preparation of the photoresist composition (for example, US Patent No. 5,212,043, International Patent Publication WO 97/33198 et al.). Specifically, as the organic solvent, diethyleneglycol diethylether, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol monomethyl ether acetate (PGMEA), cyclohexanone , 2-heptanone, ethyl lactate and the like can be used alone or in combination. In addition, the photoresist composition according to the present invention may further include an organic base, such as triethylamine, triisobutylamine, triisooctylamine, diethanolamine, triethanolamine, if necessary, the amount of use of the organic base The photoresist composition according to the present invention is prepared by blending the photosensitive polymer resin, a photoacid generator, an organic solvent, and various additives as necessary, and filtering with a filter. In this case, the solid content concentration in the entire photoresist composition is preferably 1 to 30% by weight.

In order to form a photoresist pattern using the chemically amplified photoresist composition according to the present invention, first, the photoresist composition is applied to a substrate such as a silicon wafer or an aluminum substrate using a spin coater to form a photoresist film. The photoresist film may be exposed in a predetermined pattern, and then a conventional photolithography process may be used in which the photoresist pattern is heated after exposure (PEB) and developed. The exposure process may be performed using ArF, KrF, Extreme Ultra Violet (EUV), Vacuum Ultra Violet (VUV), E-beam, X-ray, ion beam, or Immersion Lithography. It may also be carried out by the) process. In addition, as the developer used in the developing step, an alkaline aqueous solution in which alkaline compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate and tetramethylammonium hydroxide (TMAH) are dissolved at a concentration of 0.1 to 10% by weight may be used. If necessary, an appropriate amount of a water-soluble organic solvent such as methanol or ethanol and a surfactant may be added to the developer. In addition, after the development process, the cleaning process may be further performed to clean the substrate with ultrapure water.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples are intended to illustrate the present invention more specifically, but the scope of the present invention is not limited by the following examples.

Example 1

A. Synthesis of Monomers

Into a 500 mL four-necked flask equipped with a stirring rod, 234.33 g of ethyladamantyl acrylate was injected, 75.11 g of N-methyl-2-hydroxyethanolamine was added slowly, and the reaction was carried out under a nitrogen atmosphere for 6 hours. After the reaction was completed, the resultant was obtained to increase the viscosity, and the flask containing the resultant was diluted by adding 200 g of tetrahydrofuran (THF) as a solvent while maintaining the flask at room temperature. After adding 101.20 g of triethylamine as a reaction catalyst to the diluted reaction product, 128.20 g of acryloyl chloride was slowly added while maintaining the room temperature so that the temperature of the reactor did not increase. After the reaction was performed at room temperature for 5 hours in a nitrogen atmosphere, 100.00 g of diethyl ether was added to remove the chloride produced during the reaction through filtration, and the filtrate was stored at room temperature. To the filtrate was further added 200 g of diethyl ether and 500 g of water to separate the diethyl ether layer. The separated organic layer was extracted three times with 300 g of water, and the aqueous layer was extracted with 50 g of diethyl ether and mixed with the organic layer. After separating and drying the obtained organic layer with magnesium sulfate for 1 day, the organic solvent was removed by an evaporator to obtain a monomer of the following Chemical Formula 3 (yield: 88%, color: clear pale yellow, H-NMR (CDCl ₃ , internal standard) Tetramethylsilane): δ (ppm) 6.73 (CH, 1 H), 6.18 (CH ₂ , 1 H), 5.86 (CH ₂ , 1 H), 4.21 (CH ₂ , 2H), 2.70 (CH ₂ , 4H), 2.46 (CH ₂ , 2H), 2.35 (CH, 2H), 2.29 (CH ₃ , 3H), 2.19 (CH ₂ , 2H), 1.79 (CH, 2H), 1.62 (CH ₂ , 2H), 1.58 (CH ₂ , 4H), 1.42 (CH ₂ , 2H), 0.78 (CH ₃ , 3H)}.

B. Synthesis of Polymers

300 mL of tetrahydrofuran was added to a 500 mL four-necked flask equipped with a reflux condenser, a temperature controller, and a nitrogen injector, and nitrogen was added thereto, followed by stirring for 30 minutes. 39.04 g of gamma butyrolactone acrylate, 35.15 g of ethyladamantyl acrylate and 36.35 g of the monomer of Formula 3 were added thereto, and 3.16 g of AIBN was added thereto, followed by 30 minutes at a temperature of 40 ° C. and a nitrogen atmosphere. Stirring was carried out for 24 hours while keeping the reaction solution at reflux by raising the temperature. After the reaction was completed, the temperature was lowered to room temperature, and the reaction solution was dipped in 3 L of diethyl ether to obtain a precipitate. The obtained precipitate was filtered, washed several times with 2 L of diethyl ether and dried in vacuo to give 71.83 g of photosensitive polymer (GPC analysis: Mn = 7599, Mw = 14899, MP = 15788, PD = 1.96, low molecular weight = 4.1%). Synthesis process of the photosensitive polymer is summarized in Scheme 1 below.

[Example 2]

A. Synthesis of Monomers

Into a 500 mL four-necked flask equipped with a stirring rod, 256.34 g of t-butyl acrylate was injected, and 61.08 g of 2-hydroxyethanolamine was slowly added, followed by reaction under nitrogen atmosphere for 6 hours. After the reaction was completed, the resultant was obtained to increase the viscosity, and the flask containing the resultant was diluted by adding 250 g of tetrahydrofuran (THF) as a solvent while maintaining the flask at room temperature. After adding 101.20 g of triethylamine as a reaction catalyst to the diluted reaction product, 128.20 g of acryloyl chloride was slowly added while maintaining the room temperature so that the temperature of the reactor did not increase. After the reaction was performed at room temperature for 5 hours in a nitrogen atmosphere, 100.00 g of diethyl ether was added to remove the chloride produced during the reaction through filtration, and the filtrate was stored at room temperature. 200 g of diethyl ether and 500 g of water were further added to the filtrate to separate the diethyl ether layer. The separated organic layer was extracted three times with 300 g of water, and the aqueous layer was extracted with 50 g of diethyl ether and mixed with the organic layer. The separated organic layer was dried with magnesium sulfate for 1 day, and then the organic solvent was removed by an evaporator to obtain a monomer of the following Chemical Formula 4 (yield: 82%, appearance: transparent liquid with a slight light yellow color, H-NMR (CDCl) ₃ , internal standard: tetramethylsilane): δ (ppm) 6.38 (CH, 1H), 6.18 (CH ₂ , 1H), 5.87 (CH ₂ , 1H), 4.19 (CH ₂ , 2H), 2.80 (CH ₂ , 4H), 2.57 (CH ₂ , 2H), 2.34 (CH ₂ , 4H), 1.43 (CH ₃ , 18H)}.

B. Synthesis of Polymers

Instead of the monomer of Formula 3, 37.15 g of the monomer of Formula 4 was used, and the reaction was carried out under the same conditions as in the polymer synthesis step of Example 1, except that the amount of AIBN used was 3.28 g. Was obtained (GPC analysis: Mn = 10729, Mw = 18873, MP = 25246, PD = 1.76, low molecular weight balance = 2.7%). The synthesis process of the photosensitive polymer is summarized in Scheme 2 below.

Examples 3 and 4 Preparation and Evaluation of Photoresist Composition

2.0 g of each photosensitive polymer and 0.02 g of triphenylsulfonium triflate (TPS-105) obtained in Examples 1 and 2 were completely dissolved in 17 g of propylene glycol monomethyl ether acetate (PGMEA), followed by a 0.2 μm disc filter. Filtration produced a photoresist composition. The resulting photoresist composition was coated on a silicon wafer treated with hexamethyldisilazane (HMDS) to a thickness of about 0.30 μm. The wafer coated with the photoresist composition is prebaked at 100 ° C. for 90 seconds, exposed in a predetermined pattern using an ArF excimer laser having a numerical aperture of 0.60, and then the exposed wafer is heated after exposure at 100 ° C. for 90 seconds. (PEB). The post-exposure heated (PEB) wafer was developed for 30 seconds using a 2.38 wt% tetramethylammonium hydroxide (TMAH) solution to obtain a 0.10 μm line and space pattern. The line width change of the obtained photoresist pattern was investigated, and the results are shown in Table 1.

PEB (℃) Line width change size (nm) Polymer of Formula 3 100 1.5 nm / ℃ Polymer of Formula 4 100 1.4 nm / ℃

From Table 1, when the photoresist pattern is formed using the photoresist composition comprising the photosensitive polymer according to the present invention, the post-exposure heating (PEB) temperature can be kept low and the magnitude of the line width change can be reduced. It can be seen that.

As described above, the photosensitive polymer and the photoresist composition including the same according to the present invention can only form a fine photoresist pattern having a better shape in a photolithography process using a short wavelength exposure source of 248 nm or 193 nm or less. In addition, after exposure, the line width change of the pattern with increasing temperature can be reduced.

Claims (9)

A photosensitive polymer comprising a repeating unit represented by the following formula (1). [Formula 1]

In Formula 1, R ₁ and R ₃ are each independently hydrogen, methyl or trifluoromethyl group, Q ₁ is a cyclic compound having 4 to 12 carbon atoms containing an ester group or hydroxy, R ₅ is 6 to 18 carbon atoms Is an alkylester group, R ₆ is the same as hydrogen, an alkyl group having 1 to 13 carbon atoms, or R ₅ , and a and c are mole% of each repeating unit with respect to the total repeating unit constituting the photosensitive polymer, each independently 1 To 99 mol%, n is an integer of 0 to 12. The method of claim 1, wherein Q ₁ is

,

,

,

,

,

And

The photosensitive polymer is selected from the group consisting of. The method of claim 1, wherein R ₅ is

,

,

,

,

,

,

,

,

,

,

And

The photosensitive polymer is selected from the group consisting of. delete delete delete The photosensitive polymer of claim 1, wherein the weight average molecular weight of the photosensitive polymer is 3,000 to 100,000, and the degree of dispersion is 1.01 to 3.00. A photosensitive polymer comprising a repeating unit represented by the following formula (1), [Formula 1]

In Formula 1, R ₁ and R ₃ are each independently hydrogen, methyl or trifluoromethyl group, Q ₁ is a cyclic compound having 4 to 12 carbon atoms containing an ester group or hydroxy, R ₅ is 6 to 18 carbon atoms Is an alkylester group, R ₆ is the same as hydrogen, an alkyl group having 1 to 13 carbon atoms, or R ₅ , and a and c are mole% of each repeating unit with respect to the total repeating unit constituting the photosensitive polymer, each independently 1 To 99 mol%, n is an integer from 0 to 12; Photoacid generators generating acid; And Photoresist composition comprising an organic solvent. A photosensitive polymer including a repeating unit represented by Formula 1 below; Photoacid generators generating acid; And applying a photoresist composition comprising an organic solvent to the substrate to form a photoresist film, [Formula 1]

In Formula 1, R ₁ and R ₃ are each independently hydrogen, methyl or trifluoromethyl group, Q ₁ is a cyclic compound having 4 to 12 carbon atoms containing an ester group or hydroxy, R ₅ is 6 to 18 carbon atoms Is an alkylester group, R ₆ is the same as hydrogen, an alkyl group having 1 to 13 carbon atoms, or R ₅ , and a and c are mole% of each repeating unit with respect to the total repeating unit constituting the photosensitive polymer, each independently 1 To 99 mol%, n is an integer from 0 to 12; Exposing the photoresist film in a predetermined pattern; And A method of forming a photoresist pattern comprising the step of heating and developing the exposed photoresist pattern after exposure.