KR102723279B1 - Photoresist polymer resins for ultraviolet lithography using continuous flow reaction process, and preparation method thereof - Google Patents

Abstract

The present invention relates to a method for manufacturing a photoresist polymer for ultraviolet lithography using a continuous flow reaction process, and to a photoresist polymer for lithography manufactured thereby. The method for manufacturing a photoresist polymer for lithography manufactures a photoresist polymer through a continuous flow reaction process using a continuous reactor, thereby improving batch-by-batch uniformity and productivity, optimizing the composition ratio during the manufacture of the photoresist polymer to exhibit excellent polymer conversion rate, and increasing the precision of production to minimize the defect rate, thereby exhibiting high reliability.

Description

Photoresist polymer resins for ultraviolet lithography using continuous flow reaction process, and preparation method thereof

The present invention relates to a method for producing a photoresist polymer for ultraviolet lithography using a continuous flow reaction process and to a photoresist polymer for lithography produced thereby.

Most deep UV and extreme UV photoresist polymers are generally synthesized by free radical polymerization using a batch reactor. Batch reaction is a traditional synthesis method using a general reactor, and is mainly used for synthesis from milligrams to kilograms. This method requires many optimization experiments when applying it to the production process by increasing the scale because heat transfer does not occur uniformly within the entire reaction solution, making it difficult to precisely control the reaction as the scale increases. In addition, since the reaction environment of all batches cannot be the same, there is also a limitation that the structure and quality of the product are not uniform. A flow reactor is a process that can improve these heat transfer problems and batch-to-batch non-uniformity, thereby improving productivity and precision, as well as simplifying the process. Continuous flow reaction, which has many advantages compared to traditional batch reactors, has been widely used to synthesize various polymer materials recently.

Traditional batch polymerization has been performed using free radical polymerization. Free radical polymerization has very fast chain growth and it is difficult to control the side reactions of radicals, making it difficult to control the molecular weight and molecular weight dispersion. As the size of the pattern using lithography becomes smaller than that of the polymer chain, the effects of the molecular weight and molecular weight dispersion of the polymer resin cannot be ignored. Therefore, synthesis using controlled radical polymerization based on radical polymerization has attracted attention. In this controlled radical polymerization, atom transfer radical polymerization (ATRP), nitroxide-mediated radical polymerization (NMP), and reversible addition-fragmentation chain transfer (RAFT) polymerization are being developed as useful tools for precisely controlling the structural parameters of the polymer chain. In particular, RAFT polymerization proceeds relatively smoothly even in the presence of small amounts of moisture and oxygen in the reaction solution compared to ATRP and NMP, and is widely used in the synthesis of various functional polymers because it smoothly polymerizes a wide range of vinyl monomers, including methacrylate and styrene series monomers.

Chemically amplified resist (CAR) is a material used to fabricate microcircuit structures on a substrate through photolithography. The patterning process using CAR involves a complex reaction in which the acid activated by exposure diffuses during post-exposure baking (PEB) and acts as a catalyst for the reaction to deprotect the resist resin. Controlling the diffusion-reaction process accompanied by the chemical reaction is very challenging. This is because the reaction progress and reaction rate in the thin film space are affected not only by the concentration and diffusion of the acid, but also by the composition and sequence of the polymer resin. As the size of the pattern to be fabricated decreases, the influence of complex chemical phenomena in the thin film inevitably increases, so it is very important to precisely and uniformly control the structural parameters such as the composition, structure, molecular weight, and molecular weight distribution of the resist resin. Furthermore, understanding the microstructure of the polymer chain is very important to effectively control the chemical reaction in the thin film. The microstructure of a polymer is determined by the three-dimensional structure and reactivity of individual monomers during polymerization, and in order to understand this quantitatively, it is essential to measure the reaction ratio between monomers through copolymerization reaction kinetics studies.

Republic of Korea Patent No. 10-1238580 (registered on February 22, 2013)

The purpose of the present invention is to provide a method for manufacturing a photoresist polymer for lithography and a photoresist polymer for lithography manufactured thereby.

In order to achieve the above purpose, the present invention includes a step of preparing a reaction solution by mixing two or more types of polymer monomers, an initiator, a chain transfer agent, and a solvent, and a step of injecting the reaction solution into a flow reactor and polymerizing it through a continuous flow reaction while passing the reaction solution through the flow reactor.

The above polymer monomers include two or more of γ-butyrolactonyl methacrylate (GBLMA), hydroxyadamantyl methacrylate (HAMA), 2-methyladamantan-2-yl methacrylate (MAMA), acetoxystyrene (ACOST), and highly fluorinated maleimide (), and a method for producing a photoresist polymer for lithography is provided, but is not limited thereto.

In addition, the present invention provides a photoresist polymer for lithography manufactured by the method for manufacturing a photoresist polymer for lithography described above.

The method for manufacturing a photoresist polymer for lithography according to the present invention can improve batch-by-batch uniformity and productivity by manufacturing the photoresist polymer through a continuous flow reaction process using a continuous reactor, and can exhibit excellent polymer conversion rate by optimizing the composition ratio during the manufacturing of the photoresist polymer, and can exhibit high reliability by minimizing the defect rate by increasing the precision of production.

FIG. 1 is a schematic diagram and image of a flow reactor for manufacturing a photoresist polymer for lithography according to the present invention.
FIG. 2 is a graph showing the reaction solution for GBLMA, MAMA, and HAMA copolymerization that passed through the reaction section in the method for manufacturing a photoresist polymer for lithography according to the present invention, and ^{the 1} H NMR spectrum results thereof.
FIG. 3 is a graph showing the conversion rate (a), ln([M] ₀ /[M]) (b), Mw molecular weight (c), and SEC chromatogram (d) of a photoresist polymer according to the residence time in a continuous reactor in a method for manufacturing a photoresist polymer for lithography according to the present invention.
Figure 4 shows the results of NLS regression analysis for measuring the monomer reaction ratio in the method for manufacturing a photoresist polymer for lithography according to the present invention.
FIG. 5 is a graph showing the results of a ¹ H-NMR spectrum of (a) an ACOST-MAMA copolymer in a method for manufacturing a photoresist polymer for lithography according to the present invention (top: a copolymer obtained by continuous polymerization using a flow reaction RAFT polymerization; bottom: a copolymer obtained by using free radical polymerization), (b) a graph showing the results of ^{a 1} H-NMR spectrum of an ACOST-MAMA copolymer before (top) and after (bottom) removal of terminal groups.
FIG. 6 is a graph showing a calibration curve using (a) a UV/vis spectrum according to the concentration of a RAFT chain transfer agent solution and (b) absorbance for 306 nm light according to the concentration in a method for manufacturing a photoresist polymer for lithography according to the present invention.
FIG. 7 is a graph showing the results of a method for manufacturing a photoresist polymer for lithography according to the present invention, (a) ¹ H-NMR spectra before and after a deacetylation reaction for comparison of acetyl group peaks (top: before deacetylation; ¹ H-NMR solvent CDCl ₃ , bottom: after deacetylation; ¹ H-NMR solvent THF-d ₈ ), (b) ¹ H NMR spectrum after the deacetylation reaction (c)(d) infrared spectroscopy spectra (c, d; top: before deacetylation, bottom: after deacetylation).

Hereinafter, in order to explain the present invention more specifically, preferred embodiments according to the present invention will be described in more detail with reference to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms.

The present invention provides a method for producing a photoresist polymer for lithography, comprising the steps of: preparing a reaction solution by mixing two or more types of polymer monomers, an initiator, a chain transfer agent, and a solvent; and injecting the reaction solution into a flow reactor and polymerizing it through a continuous flow reaction while passing through the flow reactor.

The above photoresist polymer for lithography may be a photoresist polymer for ultraviolet lithography, and specifically, may be a photoresist polymer for deep UV and extreme UV lithography.

The above polymer monomer may include two or more of γ-butyrolactonyl methacrylate (GBLMA), hydroxyadamantyl methacrylate (HAMA), 2-methyladamantan-2-yl methacrylate (MAMA), acetoxystyrene (ACOST), and polyfluorinated maleimide (PFM).

Specifically, the step of preparing the reaction solution includes mixing γ-butyrolactonyl methacrylate (GBLMA), hydroxyadamantyl methacrylate (HAMA), and 2-methyladamantan-2-yl methacrylate (MAMA) as high molecular weight monomers, and the GBLMA:MAMA:HAMA can be mixed at a molar ratio of 1.3 to 3:0.6 to 1.5:1 or 1.5 to 2.5:0.7 to 1.5:1 based on the entire reaction solution.

In addition, the step of preparing the reaction solution mixes acetoxystyrene (ACOST) and 2-methyladamantan-2-yl methacrylate (MAMA) as high molecular weight monomers, and the acetoxystyrene (ACOST) and 2-methyladamantan-2-yl methacrylate (MAMA) can be mixed at a molar ratio of 0.5 to 6.0:1, 0.5 to 3.0:1, 0.5 to 1.5:1, or 1.0 to 1.5:1 based on the entire reaction solution.

The step of preparing the above reaction solution includes mixing acetoxystyrene (ACOST) and a highly fluorinated maleimide (PFM) as high molecular weight monomers, and the acetoxystyrene (ACOST) and the highly fluorinated maleimide (PFM) can be mixed at a molar ratio of 0.5 to 1.5:1 or 1.0 to 1.5:1 based on the entire reaction solution.

As described above, by controlling the composition ratio of the polymer monomers in the reaction solution, an excellent polymer conversion rate can be achieved and the precision of polymer production can be increased.

The step of preparing the above reaction solution further includes a step of removing oxygen within the reaction solution, and the step of removing oxygen can be performed through a free-pump-thaw process of the prepared reaction solution.

The initiator comprises at least one of 2,2'-azobisisobutyronitrile (AIBN) and 4,4'-azobis(4-cyanovaleric acid) (ACVA).

In the polymerizing step, the flow reactor includes an injection unit, a reaction unit, and a discharge unit, and the reaction solution can be polymerized through a continuous flow reaction by sequentially passing through the injection unit, the reaction unit, and the discharge unit to manufacture a polymer.

The solvent includes at least one of tetrahydrofuran (THF), cyclohexane, methyl ethyl ketone, benzene, toluene, dioxane, and dimethylformamide, and the solvent can be mixed in a ratio of 30 wt% to 65 wt% or 40 wt% to 60 wt% of the total solution. By adding the solvent in the ratio as described above, the fluidity of the reaction solution in the continuous reactor can be improved, thereby minimizing the defect rate.

The chain transfer agent comprises at least one of 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (CDSTSP), cyanomethyldodecyltrithiocarbonate, 2-cyano-2-propylbenzodithioate, 2-(dodecylthiocarbonylthionylthio)-2-methylpropionic acid, 4-cyano-4-(phenylcarbonothionylthio)pentanoic acid, 4-((((2-carboxyethyl)thio)carbonothionyl)thio)-4-cyanopentanoic acid, and 2-cyano-2-propyldodecyl tricarbonate.

The above flow reactor may include an injection portion, a reaction portion, and a discharge portion as shown in FIG. 1.

Specifically, the polymerizing step may include injecting the reaction solution into the injection unit, and the injected reaction solution may be polymerized in the reaction unit and discharged through the discharge unit. More specifically, the polymerizing step may include allowing the reaction solution to remain in the flow reactor for 60 to 180 minutes, 90 to 160 minutes, or 100 to 140 minutes to be polymerized. The residence time of the reaction solution may be affected by the flow rate and the volume of the tube of the reactor.

The above injection unit includes a syringe and a syringe pump, the syringe can contain a reaction solution, and the syringe pump can apply pressure to move the reaction solution at a constant flow rate. For example, the syringe pump can pass the reaction solution at a flow rate of 0.1 to 2 mL/hr or 0.5 to 1.5 mL/hr.

The syringe of the above injection part is connected to a tube (reaction part) of about 2 to 4 ml using a connector, and the tube may be a PTFE tube.

The above reaction section includes a tube and a double boiler, and the tube is a space where the reaction solution can move and react, and is a section where a polymer polymerization reaction proceeds. The tube can be placed in the double boiler to be maintained at a constant temperature. The double boiler can be an oil double boiler, and can be maintained at a temperature of 95° C. to 110° C. to facilitate the polymerization reaction.

The above discharge unit is a place where a polymer (polymer) whose polymerization reaction has been completed is discharged from the tube of the reaction unit, and may include a container for containing the discharged polymer.

The conversion rate of the photoresist polymer manufactured through the above polymerization step may be 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more.

After the polymerization step, a step of modifying the polymer may be additionally included, and the functional group of the chain transfer agent present at the polymer terminal may be removed through the step of modifying the polymer.

The step of modifying the above high molecular weight polymer can be performed by stirring the high molecular weight polymer, a certain ratio of 2,2'-azobisisobutyronitrile, and a solvent at a temperature of 70 to 100°C while refluxing for 10 to 25 hours, removing the solvent using a vacuum concentrator, adding an excess amount of methanol, filtering the resulting solid, and then drying it in a vacuum oven at a temperature of 20 to 50°C.

The step of modifying the above polymer may include mixing a polymer modifier in an amount of 10 to 50 times, 15 to 30 times, or 20 to 25 times the mole number of the polymer. Specifically, the polymer modifier is 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethyl valeronitrile), 2,2'-azobis(2,4-dimethyl)valeronitrile, Dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-Azobis(2-methylbutyronitrile), 1,1'-Azobis-(cyclohexane-1-carbonitrile), Benzoyl peroxide, 2,2-Bis(tert-butylperoxy)butane, 1,1-Di(tert-butylperoxy)cyclohexane, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane-3, It may include at least one of 1,3-Bis[(t-butylperoxy)isopropyl]benzene, tert-Butyl hydroperoxide, tert-Butyl peracetate, tert-Butyl peroxide, tert-Butyl peroxybenzoate, Cumene hydroperoxide, Cyclohexanone peroxide, Dicumyl peroxide, and Lauroyl peroxide.

The step of modifying the above high molecular weight polymer can mix a solvent in an amount of 20 to 100 times, 20 to 60 times, or 25 to 55 times the weight of the high molecular weight polymer, and the solvent includes at least one of tetrahydrofuran (THF), cyclohexane, methyl ethyl ketone, benzene, toluene, dioxane, and dimethylformamide, and specifically, the solvent can be tetrahydrofuran (THF).

The step of modifying the above high molecular weight polymer can remove 90% or more or 95% or more of the functional groups of the chain transfer agent present at the polymer terminal.

In addition, the step of modifying the high molecular weight polymer may additionally perform a deacetylation reaction. The deacetylation reaction may be performed by refluxing the high molecular weight polymer from which the functional group of the chain transfer agent has been removed, a certain ratio of ammonium hydroxide, and a solvent under a nitrogen atmosphere at a temperature of 20 to 25° C. for 10 to 25 hours while stirring, then removing the solvent using a vacuum concentrator, adding an excessive amount of tetrahydrofuran, filtering the resulting solid, and then drying in a vacuum oven at a temperature of 70 to 90° C. At this time, the high molecular weight polymer may be a copolymer containing acetoxystyrene.

The step of modifying the above high molecular weight polymer can be performed by mixing an ammonium hydroxide aqueous solution in an amount of 50 to 100 times or 70 to 95 times the number of moles of acetyl groups in the polymer.

The step of modifying the above high molecular weight polymer may include mixing a solvent in an amount of 5 to 50 times or 5 to 20 times the weight of the high molecular weight polymer, and the solvent may include at least one of methanol and ethanol, and specifically, the solvent may be methanol.

In addition, the present invention provides a photoresist polymer for lithography manufactured by a method for manufacturing a photoresist polymer for lithography using the continuous reactor described above.

The photoresist polymer for lithography of the present invention may have a weight average molecular weight of 4000 to 11000 g/mol or 4000 to 8500 g/mol, and may have a number average molecular weight of 3200 to 8400 g/mol or 3200 to 6500 g/mol.

Additionally, the photoresist polymer for lithography can have a polydispersity index (PDI) of 1.0 to 1.5, or 1.2 to 1.35.

Specifically, the photoresist polymer for lithography contains γ-butyrolactonyl methacrylate (GBLMA), hydroxyadamantyl methacrylate (HAMA), and 2-methyladamantan-2-yl methacrylate (MAMA) as monomers, and the GBLMA:MAMA:HAMA can be contained in a molar ratio of 1.3 to 3:0.6 to 1.5:1 or 1.5 to 2.5:0.7 to 1.5:1 based on the entire polymer.

In addition, the photoresist polymer for lithography contains acetoxystyrene (ACOST) and 2-methyladamantan-2-yl methacrylate (MAMA) as monomers, and the acetoxystyrene (ACOST) and 2-methyladamantan-2-yl methacrylate (MAMA) can be contained in a molar ratio of 0.5 to 1.5:1 or 1.0 to 1.5:1 based on the entire polymer.

The above photoresist polymer for lithography contains acetoxystyrene (ACOST) and a highly fluorinated maleimide (PFM) as monomers, and the acetoxystyrene (ACOST) and the highly fluorinated maleimide (PFM) can be contained in a molar ratio of 0.5 to 1.5:1 or 1.0 to 1.5:1 based on the entire polymer.

Hereinafter, in order to help understand the present invention, examples will be given and described in detail. However, the following examples are only intended to illustrate the content of the present invention, and the scope of the present invention is not limited to the following examples. The examples of the present invention are provided to more completely explain the present invention to a person having average knowledge in the art.

<Example 1>

1. Prepare the materials

4-Acetoxystyrene (ACOST), 2-oxotetrahydrofuran-3-yl methacrylate (GBLMA), 3-hydroxy-1-methacryloyloxyadamantane (HAMA), and 2-methyl-2-adamantyl methacrylate (MAMA) were provided by Kyung-In Yanghaeng Co., Ltd. 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (CDSTSP; 97%; Sigma Aldrich), 4,4'-Azobis(4-cyanovaleric acid)(ACVA; 98%; Sigma Aldrich), Ammonia Solution (28% in water; TCI), Tetrahydrofuran (THF; 99.9%; Sigma Aldrich), Propylene glycol monomethyl ether (PGME; 98%; Daejung Chemical & Metals), Methanol (99.5%; Samchun Chemical), Toluene (99.5%; Samchun Chemical), and Anisole (99%; ACROS ORGANICS) were purchased and used without purification. 2,2'-Azobis(2-methylpropionitrile) (AIBN; JUNSEI) was recrystallized from methanol before use.

2. Structure and Characteristics Analysis

Proton nuclear magnetic resonance (1H NMR) spectra were measured in CDCl ₃ using a Bruker Avance III 400 MHz (Bruker, USA) or JEOL JNM-ECZ400S 400 MHz spectrometer. Molecular weight measurements using size exclusion chromatography (SEC) were performed using a Thermo Scientific Ultimate 3000 system. Chromatograms were acquired with THF eluent flowing at a flow rate of 1 mL/min at 35 °C. The molecular weight information was obtained using a calibration curve obtained using ten narrow polystyrene (PS) standard samples with number-average molecular weights ranging from 1.2 kg/mol to 1390 kg/mol. The chemical structure and composition of the resins were studied using Fourier transform infrared (FT-IR) spectroscopy (IR Prestige-21, Shimadzu, Japan) and UV/vis spectrophotometer (Cytation3, Biotek).

3. Preparation of reaction solution for RAFT polymerization

Acetoxystyrene (ACOST), three types of methacrylates (GBLMA, HAMA, MAMA), and highly fluorinated maleimide monomers were used as monomers for the synthesis of resist copolymers applicable to deep UV and extreme UV lithography. CDSTSP, which is applicable to the polymerization of all monomers, was used as a chain transfer agent for RAFT polymerization, and AIBN or ACVA was used as an initiator. In order to remove oxygen that may affect the polymerization, a freeze-pump-thaw process was performed three times after preparing the solution.

4. Continuous flow reaction process

The flow reactor was designed as shown in Fig. 1, dividing it into three parts: the injection part, the reaction part, and the emission part. A syringe containing the reaction solution from which the gas had been removed in advance was installed in a syringe pump, and then the syringe and the PTFE tube were connected using a connector. The reaction part was set up by immersing a PTFE tube of a certain length in an oil bath whose temperature was controlled. The reaction solution was injected at a flow rate of 1 mL/hr (= 0.016 mL/min). Polymerization occurred as it passed through the reaction part, and the solution that passed through the entire reaction part and came out through the emission part was used to measure the conversion rate and composition through NMR analysis, or mixed with a precipitation solvent to obtain it as a solid and used to calculate the molecular weight uniformity and composition uniformity through NMR and SEC analysis.

5. Post-polymerization modification process

In order to remove the trithiocarbonate functional group that acts as a RAFT chain transfer agent, which is the terminal group of the polymer chain, the copolymer obtained by RAFT polymerization and AIBN (20 times the mole number of the polymer) were dissolved in tetrahydrofuran (50 times the polymer weight), and refluxed at 80°C with stirring for 19 hours. After removing an appropriate amount of the solvent using a vacuum concentrator, it was added to an excess of methanol, and the resulting solid was filtered and dried in a vacuum oven at 30°C. In the case of the copolymer containing acetoxystyrene, a deacetylation reaction was performed to obtain a resist resin. The copolymer from which the RAFT chain transfer agent was removed, an ammonium hydroxide aqueous solution (90 times the mole number of acetyl groups in the polymer), and methanol (approximately 10 times the polymer weight) were added to the reaction vessel, and then the mixture was stirred under a nitrogen atmosphere at room temperature for 18 hours. After removing the solvent using a vacuum concentrator, tetrahydrofuran was added to dilute the solution, and then added to distilled water to form a solid. The solid obtained by filtering was dried in a vacuum at 80°C.

<Experimental Example 1> Kinetics Experiment of Continuous Polymerization Process Using a Flow Reactor

It has been reported that the continuous polymerization process using a flow reactor determines the polymerization conversion rate according to changes in factors such as the residence time of the solution in the reaction section, reaction temperature, concentration of the reaction solution, and type of solvent. Therefore, it is necessary to confirm how each factor affects the composition and structure of the final product. In addition, it is necessary to analyze whether the reactor is maintained in a steady state that can produce a product with high compositional uniformity. GBLMA, a copolymer of HAMA and MAMA, a copolymer of ACOST and MAMA, and a copolymer of ACOST and maleimide were set as model copolymers as resist copolymers usable in deep ultraviolet and extreme ultraviolet lithography, and the RAFT copolymerization process of the corresponding monomers was performed using a flow reactor.

(1) Conversion rate measurement through NMR analysis

The conversion of GBLMA, HAMA, and MAMA copolymerization reactions was measured using ¹ H NMR analysis. As shown in Fig. 2, since the peaks attributed to the copolymerized polymers are indistinguishable in the low ppm range (1 ppm-3 ppm), anisole, of which an exact amount is known, was added as an internal standard. The integrals of the peaks attributed to the protons of the vinyl groups of the monomers observed in the 6-6.5 ppm range and the peaks attributed to anisole were compared, the amount of monomer remaining unreacted ([M]) was calculated, and the ratio to the amount of monomer before reaction ([M] ₀ ) was calculated to measure the conversion (([M] ₀ - [M])/[M] ₀ ). Since the vinyl groups of the unreacted monomers in the 6-6.5 ppm range are clearly distinguished depending on the type of monomer, quantitative analysis is possible.

(2) Effect of initiator type and solvent amount on GBLMA, MAMA, and HAMA copolymerization reaction

After fixing the input composition of GBLMA, MAMA, and HAMA as f _GBMLA : f _MAMA : f _HAMA = 0.40 : 0.30 : 0.30, a continuous polymerization process was performed by changing the concentration of the solution and the type of initiator (AIBN, ACVA). The polymerization conditions are summarized in Table 1 below. It was observed that when the amount of solvent in the solution decreased, the molecular weight of the copolymer increased, the viscosity of the solution increased, and the flow stopped inside the tube. As the type of initiator changed, an initiator with rapid radical formation showed a relatively high conversion rate because the flow reaction polymerization started quickly. Therefore, a higher conversion rate was observed when ACVA, which initiates faster than AIBN, was used.

Initiator [M]/[CDSTSP] M _n
(g/mol) M _w
(g/mol) PDI
(M _w /M _n ) Time of stay
(minute) Fraction of solvent in solution AIBN 57.5 3,290 4,234 1.33 90 min 30% 45 5,294 6,953 1.32 120 min 50% ACVA 57.5 Flow stopped by high viscosity 30% 45 6,207 7,759 1.25 120 min 50%

(3) Optimization of the residence time of GBLMA, MAMA, and HAMA (f _GBMLA : f _MAMA : f _HAMA = 0.40 : 0.30 : 0.30) copolymerization using a flow reactor

The flow reactor can easily set the residence time of the reactants in the reaction section according to the volume and flow rate of the tube. In particular, when the residence time exceeds a certain value, the structural parameters of the products must be maintained uniformly to be commercially useful. Therefore, the structural parameters of the products formed after the initial initiation reaction of the flow reaction were obtained as a function of time through NMR and SEC analysis, and compared to derive the optimal residence time at which a uniform product could be synthesized, thereby confirming that a uniform product was synthesized. The residence time is determined by the volume and flow rate of the tube. The flow rate was fixed to 1 mL/h to limit the variables, and the residence time of the reaction section was controlled by adjusting the volume of the tube. By setting the tube volume to 3 mL, the maximum reaction time was set to 3 hours, and the conversion trend according to the residence time of the reactants was observed at 5-minute intervals to determine the optimal residence time to reach a steady state, and the experimental conditions are summarized in Table 2.

[M]/[ CDSTSP ] temperature Time of stay
(min) Initiator M _n M _w PDI Molecular weight uniformity Composition uniformity Amount of solvent in solution 45 75 ℃ 180 (3 h) ACVA 8,322 10,507 1.26 1.8 % 1.1 % 50 wt%

As can be seen in Fig. 3a, the polymerization conversion reached 0.9 after a residence time of about 80 minutes, and the conversion was observed to be constant after 140 minutes. Therefore, an optimized reaction time can be set when polymerizing the polymer. The products discharged from the flow reactor after the optimized reaction time should always have the same composition ratio and uniformity. Therefore, the molecular weight and composition of the samples discharged after a residence time of 140 minutes were analyzed to measure the composition uniformity and molecular weight uniformity of the products. The measurement results showed a composition uniformity with an error level of 1.1% and a molecular weight uniformity with an error level of 1.8%, proving that a continuous production process for copolymers with very uniform quality is possible (Table 2). The molecular weight dispersity of less than 1.3 (Fig. 3c) and the kinetic behavior that can be confirmed as a pseudo-first-order reaction (Fig. 3b) mean that RAFT polymerization is operating normally in the flow reaction continuous process and controlling the polymerization. The molecular weight of the polymer can be controlled by varying various polymerization conditions, such as the amount of RAFT polymerization chain transfer agent and monomer, polymerization temperature, amount of solvent, and residence time (Table 1), thereby emphasizing the usefulness of a continuous process using a flow reactor.

(4) Measurement of reaction ratio and prediction of copolymer composition using continuous process

Each monomer in a copolymer for resist has a role, and the lithography performance characteristics such as etching resistance and sensitivity vary depending on the amount of monomer in the chain, i.e., the composition. Furthermore, when an extremely fine pattern is to be fabricated, the position of the monomer in the chain, i.e., the sequence parameter, can also be a factor affecting the lithography performance. Furthermore, if the reaction ratio that quantitatively expresses this sequence parameter is known, the composition of the composition can be predicted from the monomer dosage. In order to measure the reaction ratio between various types of deep ultraviolet/extreme ultraviolet resist monomers, a flow reactor was used, and the composition of the product generated at a conversion rate near 10% was measured using the NMR composition analysis method using the aforementioned internal standard to determine the reaction ratio. Furthermore, basic information on the affinity and reactivity between specific monomers used for synthesizing a resist resin was obtained.

By controlling the residence time, which is a characteristic of the flow reaction, the composition of the copolymer can be measured very easily and precisely at a low conversion rate. Since it is easy to obtain the material at each time during the flow reaction, the polymerization was performed for a residence time of about 5 to 10 minutes to achieve the target conversion rate. In order to measure the reaction ratio between three monomers, GBLMA, MAMA, and HAMA, used in general 193 nm deep ultraviolet resists, namely, GBLMA-MAMA, GALMA-HAMA, and HAMA-MAMA, RAFT polymerization of each system was performed by flow reaction, and the composition according to the monomer input ratio was obtained. The reaction ratio for the ACOST-MAMA copolymer, which is a copolymer that can be used in extreme ultraviolet resists, was also obtained in the same way to confirm the applicability of the continuous polymerization process to various copolymerization systems. The results of regression analysis of the monomer input ratio and the measured actual composition using the nonlinear least squares method with the Mayo-Lewis equation are summarized in Fig. 4 and Table 3. Among GBLMA, MAMA, and HAMA, irregular sequences were observed, and ACOST and MAMA can be interpreted as showing a blocky sequence in which irregular sequences and ACOST are gathered together. In order to confirm the validity of the method developed in this study, the reaction ratio was measured while copolymerizing a styrene-based monomer (ACOST), which is known to form a cross-copolymer, and a maleimide monomer in a continuous flow mode. As a result, as shown in Table 3 below, the product of the reaction ratios of the two monomers was close to 0, confirming that they form a cross-copolymer, verifying the validity of the developed method.

Monomer A Monomer B r _A r _B r _A r _B HAMA MAMA 1.36 ± 0.13 0.45 ± 0.06 0.61 ± 0.14 GBLMA MAMA 0.67 ± 0.09 0.21 ± 0.04 0.14 ± 0.04 GBLMA HAMA 0.62 ± 0.02 0.48 ± 0.02 0.30 ± 0.02 ACOST MAMA 0.57 ± 0.09 0.08 ± 0.03 0.050 ± 0.020 ACOST maleimide 0.06 ± 0.01 0.09 ± 0.01 0.005 ± 0.001

When synthesizing GBLMA-MAMA-HAMA copolymer, which is widely used as a deep ultraviolet photoresist resin, the composition of the final product can be predicted by using the reaction ratio of each monomer. To this end, RAFT polymerization was performed through flow reaction while changing the composition of the input monomers. The input composition ratio and the determined reaction ratio were substituted into Equation 1 below to predict the composition ratio, and the results of comparison with the experimental value are summarized in Table 4 below.

[Formula 1]

Conversion rate Experimental value Forecast error f _GBLMA : f _HAMA : f _MAMA F _GBLMA : F _HAMA : F _MAMA F _GBLMA : F _HAMA : F _MAMA 13.71 0.40 : 0.20 : 0.40 0.53 : 0.27 : 0.20 0.51 : 0.28 : 0.21 ± 0.01 7.01 0.20 : 0.40 : 0.40 0.35 : 0.26 : 0.39 0.33 : 0.27 : 0.40 ± 0.01 15.41 0.40 : 0.30 : 0.30 0.45 : 0.23 : 0.32 0.49 : 0.21 : 0.30 ± 0.03 l1.1 0.50 : 0.20 : 0.30 0.58 : 0.20 : 0.22 0.60 : 0.19 : 0.21 ± 0.01 12.6 0.30 : 0.30 : 0.40 0.46 : 0.27 : 0.26 0.47 : 0.27 : 0.25 ± 0.01

The error between the composition of the copolymer obtained through the experiment and the composition predicted using the reaction ratio and the composition of the monomers introduced was ±1-3%, confirming the validity of the reaction ratio measured using the continuous flow reaction process. Furthermore, it was possible to obtain information about the monomer sequence within the chain of the copolymer, and it was possible to confirm the precise polymerization control of the continuous process using the flow reactor.

<Experimental Example 2> Synthesis of polymer for resist through post-polymerization modification reaction

(1) Removal of terminal RAFT chain transfer agent functional group

At the end of the polymer chain obtained through RAFT polymerization, a trithiocarbonate functional group remains, and this functional group generally absorbs ultraviolet light and a small portion of the visible light range and exhibits a yellow color. Therefore, in order to apply the copolymer resin obtained through RAFT polymerization to a resist for ultraviolet lithography, the functional group must be removed so that the photoacid generator in the thin film can be more efficiently activated by ultraviolet light to generate acid, and furthermore, the loss of sensitivity of the photoresist can be prevented. To this end, the ACOST-MAMA copolymer (f _ACOST = 0.6 or 0.4) synthesized by a continuous polymerization process was reacted with an excess amount of AIBN. In order to find the optimal reaction conditions, (1) the amount of THF was fixed (25 times the copolymer mass) and the amounts of AIBN (20, 50, 80, and 100 times the mole number of copolymer chains) were varied, and (2) the amount of AIBN was fixed (20 times the copolymer mole number) and the amounts of THF (10, 50, and 100 times the copolymer mass) were varied. The efficiency of the end group removal reaction was quantitatively analyzed using ¹ H NMR and UV/vis spectroscopy. The results are shown in Figs. 5 and 6. At this time, Fig. 6 shows the results of measurements with different molar concentrations of CTA, and the samples with smaller molar concentrations of CTA are shown from top to bottom, and the molar concentrations from the top of the graph are 0.99 mol/L (blue), 0.66 mol/L (red), 0.44 mol/L (green), 0.33 mol/L, 0.29 mol/L, 0.20 mol/L, 0.11 mol/L, 0.036 mol/L, 0.012 mol/L, and 0.004 mol/L, respectively.

As shown in Fig. 5, it was confirmed that the peaks at 3-3.2 ppm and 1.3 ppm (these peaks did not appear during free radical polymerization) originating from the terminal groups in the ¹ H NMR spectrum disappeared after AIBN treatment. However, in order to analyze this more quantitatively, the UV absorption behavior of the trithiocarbonate functional group was utilized. As can be confirmed in Fig. 6a, the absorbance of the RAFT chain transfer agent solution (CDSTSP/THF solution) whose exact concentration is known at 306 nm was measured, and a calibration curve was obtained to determine the concentration of trithiocarbonate at the terminal of the polymer (Fig. 6b). The absorbance of the polymer for 306 nm light before and after removal of the terminal groups was measured, and the absorbance for 306 nm light was converted into concentration using the calibration curve, and the removal rate was calculated using the corresponding values. The terminal group removal rates of the products obtained under the various reaction conditions mentioned above are summarized in Table 5. As a result, it was confirmed that the removal rate was highest when the amount of AIBN was 20 times the number of moles of polymer and the amount of THF was 50 times the weight of polymer.

Amount of CTA removed (%) Amount of THF relative to polymer weight
(AIBN amount compared to polymer concentration: 20 times) 100 times 96.65 50 times 97.69 AIBN amount compared to polymer moles
(THF amount relative to polymer weight: 25 times) 20 times 98.46 50 times 96.10 80 times 97.25 100 times 96.78 Amount of CTA removed (%) AIBN 20 times, THF 50 times
₍ fACOST _: fMAMA =0.60:0.40) 98.68 AIBN 20 times, THF 50 times
₍ fACOST _: fMAMA =0.40:0.60) 98.68

(2) Achieving a copolymer structure for resist through deacetylation reaction

The reaction of removing the acetyl group of ACOST-MAMA copolymer, which can be used for KrF resist and EUV resist, and converting it into a phenol group is very important for securing the adhesion of the photoresist and improving the sensitivity. It is difficult to polymerize a monomer having a phenol group because of the high reactivity of the phenol group with radicals, so ACOST in which the phenol group is protected by an acetyl group is used for RAFT polymerization. In the case of the acetyl group of the copolymer polymerized using a flow reactor, the deprotection reaction was generally performed using an aqueous ammonium hydroxide solution, which is a weak base. As can be seen in the NMR spectra before and after deprotection (Figs. 7a and 7b), the peak due to the acetyl group appearing at 2.2-2.4 ppm was removed after the weak base treatment, and it could be confirmed that the peak due to the proton of phenol appeared at 7.7 ppm. Furthermore, the OH signal at 3200–3600 cm ^-1 , which could not be observed before the reaction, could be observed after the reaction as a result of the infrared spectroscopy spectrum measurement, and the peak attributed to the C=O of the acetyl group appearing at 1750–1770 cm ^-1 was observed to disappear. Through this, it was shown that the copolymer with high precision and uniformity obtained by the continuous process using the flow reaction can be modified to have a structure applicable as a resin for photoresist for actual deep ultraviolet/extreme ultraviolet lithography.

The present invention predicts the composition of a photoresist polymer based on a kinetic experiment, and based on the results, demonstrates that a deep UV and extreme UV photoresist polymer having a desired composition can be synthesized by a RAFT copolymerization method using a flow reactor. Finally, it was confirmed that post-polymerization modification reactions, which remove the RAFT functional group at the end of the copolymer and perform deacetylation, can be successfully applied as essential tasks for applying the synthesized copolymer to an actual chemically amplified resist, thereby confirming that the continuous flow reaction process is a next-generation production method suitable for mass production of a photoresist polymer resin with high structural and compositional uniformity.

While the specific parts of the present invention have been described in detail above, it is obvious to those skilled in the art that such specific description is merely a preferred embodiment and that the scope of the present invention is not limited thereby. In other words, the actual scope of the present invention is defined by the appended claims and their equivalents.

Claims (14)

A step of preparing a reaction solution by mixing two or more types of polymer monomers, an initiator, a chain transfer agent, and a solvent; and
It comprises a step of injecting the above reaction solution into a flow reactor and polymerizing it through a continuous flow reaction while passing through the flow reactor,
The step of preparing the above reaction solution is to mix acetoxystyrene (ACOST) and polyfluorinated maleimide (PFM) as high molecular weight monomers,
The above acetoxystyrene (ACOST) and highly fluorinated maleimide (PFM) are mixed at a molar ratio of 0.5 to 1.5:1 based on the total reaction solution.
A method for manufacturing a photoresist polymer for lithography. In paragraph 1,
The above flow reactor comprises an injection section, a reaction section and a discharge section,
A method for manufacturing a photoresist polymer for lithography, characterized in that the polymerizing step comprises injecting the reaction solution into the injection unit and performing polymerization while passing through the reaction unit. delete delete delete In paragraph 1,
A method for producing a photoresist polymer for lithography, wherein the initiator comprises at least one of 2,2'-azobisisobutyronitrile (AIBN) and 4,4'-azobis(4-cyanovaleric acid) (ACVA). In paragraph 1,
The solvent comprises at least one of tetrahydrofuran (THF), cyclohexane, methyl ethyl ketone, benzene, toluene, dioxane and dimethylformamide,
A method for producing a photoresist polymer for lithography, characterized in that the solvent is mixed in a ratio of 30 to 65 wt% of the total solution. In paragraph 1,
A method for producing a photoresist polymer for lithography, characterized in that the polymerizing step comprises allowing the reaction solution to remain in the flow reactor for 60 to 180 minutes. In paragraph 1,
A method for manufacturing a photoresist polymer for lithography, characterized in that the polymerizing step comprises passing the reaction solution through the polymer at a flow rate of 0.1 to 2 mL/hr. A step of preparing a reaction solution by mixing two or more types of polymer monomers, an initiator, a chain transfer agent, and a solvent;
A step of injecting the above reaction solution into a flow reactor and polymerizing it through a continuous flow reaction while passing through the flow reactor; and
It comprises a step of modifying the polymer by removing the functional group of the chain transfer agent present at the end of the polymerized polymer through the above continuous flow reaction,
The above polymer monomer comprises two or more of γ-butyrolactonyl methacrylate (GBLMA), hydroxyadamantyl methacrylate (HAMA), 2-methyladamantan-2-yl methacrylate (MAMA), acetoxystyrene (ACOST), and highly fluorinated maleimide (PFM).
A method for producing a photoresist polymer for lithography, wherein the step of modifying the polymer comprises the step of refluxing the polymer, the polymer modifier 2,2'-azobisisobutyronitrile, and the solvent at a temperature of 70 to 100° C. for 10 to 25 hours. In Article 10,
A method for manufacturing a photoresist polymer for lithography, characterized in that the step of modifying the above polymer comprises mixing a polymer modifier in an amount of 10 to 50 times the mole number of the polymer. In Article 11,
A method for manufacturing a photoresist polymer for lithography, characterized in that the step of modifying the above polymer comprises mixing 20 to 100 times the weight of the polymer in a solvent. A photoresist polymer for lithography manufactured by any one of claims 1, 2, 6 to 12. In Article 13,
A photoresist polymer for lithography, characterized in that the polymer has a weight average molecular weight of 4000 to 11000 g/mol.