KR20120140536A - Photoacid generator bound positive polymer resist and the method of preparing the same - Google Patents

Abstract

PURPOSE: A positive type polymer resist including a photoacid generator and a manufacturing method of the same are provided to ensure the ultrafine line-width of high resolution and to develop the polymer resist under a commercialized solution such as tetramethyl ammonium hydroxide. CONSTITUTION: A positive type polymer resist includes repeating units represented by a chemical formula 1 or 2. In chemical formulas 1 and 2, R1 and R2 are selected from a group including hydrogen atom, C1-20 alkyl group or C1-20 cycloalkyl group, ditetrabutyl dicarbonate styrene carbonate, and lactone group; the sum of a, b, and c is 1; and the sum of l, m, and n is 1. The weight average molecular weight of a repeating unit represented by chemical formula 1 is in a range between 3,000 and 100,000, inclusively. The weight average molecular weight of a repeating unit represented by chemical formula 2 is in a range between 10,000 and 100,000, inclusively.

Description

Positive polymer resist containing photoacid generator and manufacturing method thereof {Photoacid generator bound positive polymer resist and the method of preparing the same}

The present invention relates to the synthesis and application of positive type polymer resists including photoacid generators, and more particularly, to photoresists such as KrF, ArF, Atomic Force Microscope (AFM) lithography or E-beam resists. It relates to a positive polymer resist containing a photoacid generator.

High integration of semiconductors is based on ultra miniaturization of circuits. Lithography is a key technology for semiconductor manufacturing that achieves high integration by finely processing a desired circuit of a semiconductor integrated circuit (IC) and is developing at a very high speed. Resist is a key material in microfabrication technology. Solubility characteristics change due to high sensitivity chemical reaction caused by irradiation of ultraviolet rays (wavelengths 180-450 nm), X-rays (0.4-1.4 nm), and electron beams. It refers to a photosensitive or radiation-sensitive polymer material. That is, a chemical change occurs in a portion irradiated with radiation energy through a photomask on which a microcircuit is drawn, so that a difference in solubility occurs in comparison with an unirradiated portion. The change in these properties is sometimes carried out by the polymer alone or by combining a crosslinking agent such as dichromate, such as gelatin. In practical use, photoresist (PR) is used as a functional material called PR by mixing a photocrosslinking agent, a photopolymerization initiator, a sensitizer, etc. so that the function of a polymer is suitable for each use.

Another function of PR is that the PR image serves as an etch barrier during the etching process of the silicon wafer substrate after patterning, thereby processing a pattern of a desired microcircuit on the substrate. Therefore, the resist material is a primary technical material for determining the ultrafine circuit line width of a highly integrated semiconductor, and may be regarded as a core technical material for determining the achievement of semiconductor high integration.

As the degree of integration of semiconductor circuits increases, solutions for physical and chemical aspects have been studied for far-infrared micromachining. In other words, the development of highly sensitive resists using the concept of ultralithography using high power excimer lasers such as KrF (248 nm) or ArF (193 nm) and chemical amplification to dramatically increase sensitivity, At present, the ultra-ultraviolet ultra-fine processing technology using KrF and ArF excimer laser light sources and using a highly sensitive chemical amplification resist (CAR) material has been mass-produced. In addition, an immersion technique in which a high refractive index medium is combined with an ArF light source for a semiconductor circuit pattern of 50 nm or less is being actively researched.

KrF excimer laser lithography is a chemically amplified lithography method using deep UV as a light source, which means a photoresist having a quantum yield of more than 100%, also referred to as a protecting-deprotecing reaction. The mechanism of action of the chemically amplified photoresist is that the acid generated from the PAG is diffused by excimer laser exposure, and then the protecting group is replaced with a hydroxyl group through the reaction of deprotecting the proecting group in the subsequent post exposure bake (PEB) process. Since the substituted hydroxyl group has a high relative solubility in a developer which is a weak alkaline solution, a pattern shape is formed in a shape exposed through a mask after developing.

ArF excimer laser lithography uses ArF excimer laser (193 nm) as a lithography method that emerged after using KrF (248 nm) excimer laser. Therefore, there is a need for a photoresist material with low absorbance for 193 nm wavelength. In general, the conditions for the ArF photoresist polymer should be developed in terms of transparency, dry etching resistance, good adhesion properties and typical developer (TMAH 2.38 wt%). In addition, generally required properties include a defect-free thin film formation, storage stability, adhesion to the substrate and high sensitivity.

On the other hand, ArF immersion lithography refers to a technique in which lithography is performed by filling a gap between a lens and a photoresist-coated wafer with water or a medium having high refractive index during exposure. ArF immersion technology has recently been in the spotlight for 32 nm half pitch implementations, and currently 40-50 nm half pitch patterns are available.

In addition, electron beam lithography is a technique for forming a photoresist pattern on a sample surface by combining or cutting a polymer constituting the photoresist material by irradiating an electron beam to a sample surface coated with an electron beam photosensitive agent. In recent years, it is a key technology in the manufacture of reticle (enlargement mask) for reduction projection exposure apparatus (stepper), which is used as a manufacturing line of semiconductor devices, especially ultra LSI.

The characteristic of electron beam lithography technology is that the self-calibration of the beam deflection meter is possible by electron optics with high stability and laser measurement in vacuum, and micropattern lithography is possible with precision close to the laser measurement resolution, and directly lithography on the wafer substrate As a result, high-precision fine patterns can be formed in association with patterns formed by other process treatments. However, the shape and dimensions of the minimum pattern depend on the secondary electron generation and the photosensitizer properties.

An atomic force microscope (AFM) is a type of scanning probe microscope (SPM) that uses atomic force, such as the attractive force or repulsive force, between the pointed probe and the sample surface to provide an atomic resolution. It is a precise measuring instrument that can be analyzed. Recently, AFM has been spotlighted as a useful method for forming an ultra fine pattern, and is generally used to shape the surface of a sample without damaging the sample. However, applying a force that damages the surface of the sample can manipulate the arrangement of atoms or molecules on the surface of the sample, a technique called nanolithography. By making artificial nanostructures using nanolithography, physical quantities with the same electron density and energy level can be controlled at the nanoscale.

In the field of nanolithography research using AFM, a method of forming an ultrafine pattern using a resist material, a method of obtaining an oxide film formation pattern by an electric field of an AFM tip on a surface of hydrogen passivation Si-wafer, or poly-Si, etc. Methods are in progress, and combined with electrostatic force microscopy (EMF) and scanning capacitance microscopy (SCM), they can be applied to next-generation data accumulation.

Although a number of studies on polymers for use in the aforementioned micromachining techniques, namely KrF, ArF, AFM, electron beam resist or photoresist, have developed polymer resists having photoacid generators, but mainly negative polymer resists have been reported. Therefore, there is a need for developing a positive polymer resist.

The problem to be solved by the present invention can be developed in a commercialized solution such as tetramethylammonium hydroxide (TMAH), high-resolution, fine pattern can be used for AFM, KrF, ArF, electron beam polymer side chains It is to provide a positive polymer resist in which a photoacid generator is introduced.

The present invention provides a positive polymer resist containing a repeating unit represented by the following formula (1) or (2).

...(1)

...(One)

...(2)

...(2)

In the above formula (1) or (2),

R ₁ and R ₂ are selected from the group comprising hydrogen, an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group having 1 to 20 carbon atoms, ditetrabutyl dicarbonate styrene carbonate and a lactone group,

a + b + c = 1 and l + m + n = 1.

According to one embodiment of the invention, the average molecular weight of the polymer comprising a repeating unit of formula (1) is in the range of 3,000 ≤ M _w ≤ 100,000, the average molecular weight of the polymer comprising a repeating unit of the formula (2) is 10,000 ≦ M _w ≦ 100,000.

According to another embodiment of the present invention, it is preferable that a, b, and c in Formula (1) have a range of 0 <a ≤ 0.02, 0 <b ≤ 0.8, 0 <c ≤ 0.1, and ), M, n preferably have a range of 0 <l ≦ 0.1, 0 <m ≦ 0.7, 0 <n ≦ 0.6.

The polymers synthesized according to the present invention are well soluble in THF, DMF, cyclohexanone, PEGMEA and TMAH, depending on the composition distribution of the monomers.

Each polymer molecule according to the invention can be used as KrF, ArF, AFM or electron beam resist.

In another aspect, the present invention provides a method for producing a positive polymer resist comprising a repeating unit of the following formula (1) or (2) according to the following scheme (1) or (2).

[Reaction Scheme 1]

…(1)

... (One)

Scheme 2

…(2)

... (2)

In Scheme (1) or (2) above,

R ₁ and R ₂ are selected from the group comprising hydrogen, an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group having 1 to 20 carbon atoms, ditetrabutyl dicarbonate styrene carbonate and a lactone group,

AIBN is azobisisobutylonitrile, THF is tetrahydrofuran,

a + b + c = 1 and l + m + n = 1.

The polymer resist according to the present invention is very useful in that it is a positive polymer resist that can be applied to AFM, KrF, ArF lithography resist or electron beam resist. Specifically, in order to achieve high integration of devices in semiconductor-related manufacturing processes such as semiconductor integrated circuit devices and TFT-LCDs, a fine line width is required in an exposure process, and the polymer resist according to the present invention may realize high resolution ultra fine line width. In particular, the positive polymer resist according to the present invention has an advantage in that it can be applied to the current process because of its excellent developability in a commercial developer such as tetramethylammonium hydroxide (TMAH).

The resist currently commercialized and used in the field uses a positive type, and since the process line is aligned with the positive resist, if the resist of the present invention is commercialized, the existing process may be applied as it is.

Figure 1 shows the ¹ H-NMR analysis of the terpolymer compound synthesized in Example 1.
2 is a TGA graph of the terpolymer compound synthesized in Example 1. FIG.
3 is a DSC analysis graph of the terpolymer compound synthesized in Example 1. FIG.
Figure 4 shows the ¹ H-NMR analysis of the terpolymer compound synthesized in Example 2.
5 is a TGA graph of the terpolymer compound synthesized in Example 2. FIG.
6 is a DSC analysis graph of the terpolymer compound synthesized in Example 2. FIG.
Figure 7 shows the ¹ H-NMR analysis of the terpolymer compound synthesized in Example 3.
8 is a TGA graph of the terpolymer compound synthesized in Example 3. FIG.
9 is a DSC analysis graph of the terpolymer compound synthesized in Example 3. FIG.
Figure 10 shows the ¹ H-NMR analysis of the terpolymer compound synthesized in Example 4.
11 is a TGA graph of the terpolymer compound synthesized in Example 4. FIG.
12 is a DSC analysis graph of the terpolymer compound synthesized in Example 4. FIG.
13 is an image showing a KrF measurement result using a polymer resist according to the present invention.

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

The polymer according to the present invention provides a positive polymer resist having excellent characteristics in that it is highly applicable to the actual mass production process because it is possible to realize high resolution ultra fine wire width and develop in a commercial developer.

In general, sulfonium salts are used as photoinitiators or radical photoinitiators in polymer polymerization, or as acid catalyst generators for deprotection of organic compounds. Sulfonium salts, which generate cationic photoinitiators in response to ultraviolet light in a specific region, have been developed for various kinds of applications that cannot be obtained from conventional radical curing.

The present inventors have excellent solubility in organic solvents in which the compound in which the photoacid generator of the fluoroalkylsulfonium salt is substituted and the copolymer in which the photoacid generator in which the fluoroalkylsulfonium salt of the copolymer is polymerized is introduced into the side chain thereof, After discovering the excellent photopolymerization ability of the phosphium salt, the inventors have developed and published a polymer resist having a photoacid generator substituted with a fluoroalkylsulfonium salt introduced into the side chain. (Patent Registration No. 10-0637450) After further research, the monomer was further introduced, and thus development was possible in the 2.38% tetramethylammonium hydroxide (TMAH) solution, which is the most used developer.

In the positive polymer resist according to the present invention, the following three monomers are polymerized.

[Reaction Scheme 1]

…(1)

... (One)

Scheme 2

…(2)

... (2)

In Scheme (1) or (2) above,

R ₁ and R ₂ are selected from the group comprising hydrogen, an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group having 1 to 20 carbon atoms, ditetrabutyl dicarbonate styrene carbonate and a lactone group,

AIBN is azobisisobutylonitrile, THF is tetrahydrofuran,

a + b + c = 1 and l + m + n = 1.

In the case of the polymer according to the present invention, the average molecular weight of the polymer including the repeating unit of formula (1) is in the range of 3,000 ≦ M _w ≦ 100,000, and the average molecular weight of the polymer comprising the repeating unit of the formula (2) is 10,000 A range of ≦ M _w ≦ 100,000 is preferred because polymers having molecular weights in this range have good solubility in solvents in the lithographic process.

In the present invention, it is preferable that a, b, and c of Formula (1) have a range of 0 <a ≦ 0.02, 0 <b ≦ 0.8, 0 <c ≦ 0.1, and l, m, of Formula (2) n preferably has a range of 0 <l ≦ 0.1, 0 <m ≦ 0.7, 0 <n ≦ 0.6. In the present invention, the solubility characteristics are adjusted according to the ratio of a and l, and the positive characteristics are adjusted according to the ratio of c and n. In addition, the ratio of adhesion with the substrate is controlled by the ratio of b and m. Therefore, the solubility characteristic change and the positive characteristic are shown by the composition ratio of each structure.

In the polymer according to the invention each monomer plays a different role. Specifically, the monomer (x) functions to be dissolved in the TMAH developer, the monomer (y) improves adhesion to the surface, and the monomer (z) acts as a photoacid generator. Therefore, only an appropriate combination of these can be a polymer resist that can be developed in a commercial developer while enabling high resolution fine line width.

The present invention will be described in more detail with reference to the following examples, which are intended to aid the understanding of the present invention and should not be construed as being limited thereto.

Monomer methacrylic acid (MAA), glycidyl methacrylate (GMA), ethyl adamantyl methacrylate (ethyladamantyl methacrylate, EAMA) and methyl methacrylate (methyl methacrylate, used in the present invention) MAA) was purchased from Aldrich, and triphenylsulfonium salt methacrylate (TPSMA) was synthesized and used. Azobisisobutylonitrile (a, a'-azobisisobutylronitrile, AIBN) and tetrahydrofuran (THF) were purchased from Aldrich. AIBN was recrystallized and THF and cyclohexanone were used after purification.

Example  One: Triphenylsulfolium salt Of methacrylate (TPSMA)  synthesis

Triphenylsulfolium salt methacrylate (TPSMA), which is one of the constituent monomers of the present invention, is represented by the following Chemical Formula (2), and acrylophenyl, diphenyl sulfoxide and triple anhydride are represented by the following <Reaction Scheme 3>. The reaction was carried out at a temperature lower than room temperature using methylene chloride as a solvent.

<Reaction Scheme 3>

Synthesis of the TPSMA monomer is described in Korean Patent Registration No. 10-0637450, which is the prior patent of the present inventors.

Example  2-1: polymer poly ( MAA - MMA - TPSMA Synthesis of 1

Polymer (1) according to the present invention was synthesized according to the following procedure. A two-neck round bottom 100 mL flask was equipped with a cooler, filled with argon gas and dissolved in methacrylic acid (0.51 g, 5.88 mmol) and methyl methacrylate (4.71 g, 47.08 mmol) in 10 mL tetrahydrofuran. Triphenylsulfonium salt methacrylate (3.0 g, 5.88 mmol) dissolved in tetrahydrofuran is added to the reaction vessel. 2 mol% (0.2 g) of the reaction initiator AIBN (0.2 g) was added dropwise to 5 mL of tetrahydrofuran and reacted at 65 ° C. for 24 hours. The reaction mixture is cooled to room temperature and the reaction precipitate is filtered off. The filtered precipitate is dissolved with tetrahydrofuran and precipitated in a mixed solvent of isopropyl alcohol and nucleic acid (6: 1). The resulting compound was vacuum dried for 48 hours to synthesize poly (MAA-MMA-TPSMA) (1) in a yield of 80% or more.

The actual monomer ratio of the synthesized polymer was calculated by the integral ratio of ¹ H-NMR and the average molecular weight (M _w ) was 12,000.

The polymer obtained in the experiment was confirmed by ¹ H-NMR, and thermal stability was analyzed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the results are shown in FIGS. 1, 2, and 3.

Example  2-2: polymer poly ( MAA _x  - MMA _y  - TPSMA _z Synthesis of 2

Polymer (2) according to the present invention was synthesized according to the following procedure. A two-neck round bottom 100 mL flask was equipped with a cooler, filled with argon gas and dissolved in methacrylic acid (1.52 g, 17.64 mmol) and methyl methacrylate (3.53 g, 35.28 mmol) in 10 mL tetrahydrofuran. Triphenylsulfonium salt methacrylate (3.0 g, 5.88 mmol) dissolved in tetrahydrofuran is added to the reaction vessel.

2 mol% (0.2 g) of the reaction initiator AIBN was added dropwise to 5 mL of tetrahydrofuran and reacted at 65 ° C. for 24 hours. The reaction mixture is cooled to room temperature and the reaction precipitate is filtered off. The filtered precipitate is dissolved with tetrahydrofuran and precipitated in a mixed solvent of isopropyl alcohol and nucleic acid (9: 1). The resulting compound was vacuum dried for 48 hours to synthesize poly (MAA-MMA-TPSMA) (2) in a yield of 80% or more.

The actual monomer ratio of the synthesized polymer was calculated by the integral ratio of ¹ H-NMR and the average molecular weight (M _w ) was 12,000.

The polymer obtained in the experiment was confirmed by ¹ H-NMR, and thermal stability was analyzed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the results are shown in FIGS. 4, 5, and 6.

Example  2-3: polymer poly ( EAMA - MMA - TPSMA Synthesis of 3

Polymer (3) according to the present invention was synthesized according to the following procedure. Equipped with a cooler in a two-necked round bottom 100 mL flask, filled with argon gas, dissolve ethyladamantyl methacrylate (4.38 g, 17.64 mmol) and methyl methacrylate (3.53 g, 35.28 mmol) in 10 mL tetrahydrofuran. . Triphenylsulfonium salt methacrylate (3.0 g, 5.88 mmol) dissolved in tetrahydrofuran is added to the reaction vessel.

4 mol% (0.39 g) of the reaction initiator AIBN was added dropwise to 5 mL of tetrahydrofuran and reacted at 65 ° C. for 24 hours. The reaction mixture is cooled to room temperature and the reaction precipitate is filtered off. The filtered precipitate is dissolved in tetrahydrofuran and precipitated in a mixed solvent of isopropyl alcohol and nucleic acid (8: 2). The resulting compound was vacuum dried for 48 hours to synthesize poly (EAMA-MMA-TPSMA) (3) in a yield of 80% or more.

The actual monomer ratio of the synthesized polymer was calculated by the integral ratio of ¹ H-NMR and the average molecular weight (M _w ) was 5,500.

The polymer obtained in the experiment was confirmed by ¹ H-NMR, and thermal stability was analyzed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the results are shown in FIGS. 7, 8, and 9.

Example  2-4: polymer poly ( EAMA _x - MMA _y - TPSMA _z Synthesis of 4

The polymer (4) according to the present invention was synthesized according to the following procedure. Equipped with a cooler in a two-necked round bottom 100 mL flask, filled with argon gas, dissolve ethyladamantyl methacrylate (4.38 g, 17.64 mmol) and methyl methacrylate (3.53 g, 35.28 mmol) in 10 mL tetrahydrofuran. . Triphenylsulfonium salt methacrylate (3.0 g, 5.88 mmol) dissolved in tetrahydrofuran is added to the reaction vessel.

4 mol% (0.39 g) of the reaction initiator AIBN was added dropwise to 5 mL of tetrahydrofuran and reacted at 65 ° C. for 24 hours. The reaction mixture is cooled to room temperature and the reaction precipitate is filtered off. The filtered precipitate is dissolved in tetrahydrofuran and precipitated in a mixed solvent of isopropyl alcohol and nucleic acid (9: 1). The resulting compound was vacuum dried for 48 hours to synthesize poly (EAMA-MMA-TPSMA) (3) in a yield of 80% or more.

The actual monomer ratio of the synthesized polymer was found to be a: b: c = 0.3: 0.57: 0.13 as analyzed by the integral ratio of ¹ H-NMR, and the average molecular weight (M _w ) was 10,000.

The polymer obtained in the experiment was confirmed by ¹ H-NMR, and thermal stability was analyzed by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the results are shown in FIGS. 10, 11, and 12.

Test Example  One: Resist  Test

The following experiment was conducted using the polymer resist prepared in Example 3. As the casting solvent of the polymer resist including the photoacid generator, propylene glycol monomethyl ether acetate (PGMEA) was used. A 10 wt% resist solution was prepared and filtered using a 0.1 μm filter, and spin-coated on a silicon wafer at 500 rpm (5 sec) and 4000 rpm (40 sec). The coated wafer was exposed to KrF after removing the solvent in a state at 100 ° C. for 30 seconds. After PEB (post exposed bake) treatment for 80 seconds at 80 ℃ developed in 2.38% tetramethylammonium hydroxide (TMAH) for 60 seconds and washed with purified water.

KrF lithography results using the polymer resist of the present invention are shown in FIG. 13. The test conditions are as follows.

Coating solution: 10% PGMEA

Coating conditions: 500 rpm (5 seconds) 3000 rpm (40 seconds)

Soft baking: 100 ° C., 30 seconds

UV irradiation: 10 seconds

PEB process: 80 ° C., 60 seconds

Development: 2.38% TMAH (60 seconds), distilled water (20 seconds), N ₂ drying

Film thickness: 200 nm

As shown in the KrF measurement results of FIG. 13, it was confirmed that a lithography pattern having a fine and sharp line width was formed in the TMAH developer using the polymer resist according to the present embodiment.

Claims (8)

Positive polymer resists comprising repeating units of formula (1) or (2):

...(One)

...(2)
In the above formula (1) or (2),
R ₁ and R ₂ are selected from the group comprising hydrogen, an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group having 1 to 20 carbon atoms, ditetrabutyl dicarbonate styrene carbonate and a lactone group,
a + b + c = 1 and l + m + n = 1. The method of claim 1,
Positive polymer resist, characterized in that the average molecular weight of the formula (1) has a range of 3,000 ≤ M _w ≤ 100,000. The method of claim 1,
Positive polymer resist, characterized in that the average molecular weight of the formula (2) has a range of 10,000 ≤ M _w ≤ 100,000 The method of claim 1,
A, b, c are 0 <a ≤ 0.02, 0 <b ≤ 0.8, 0 <c ≤ 0.1, l, m, n is 0 <l ≤ 0.1, 0 <m ≤ 0.7, 0 <n ≤ 0.6 A positive polymer resist, characterized in that. The method of claim 1,
Positive type polymer resist, which is used as KrF, ArF, AFM, electron beam resist or photoresist. The method of claim 1,
Positive polymer resist, characterized in that development is possible in tetramethylammonium hydroxide (TMAH). According to Scheme (1) or (2), a method of preparing a positive polymer resist including repeating units of the following formula (1) or (2):
[Reaction Scheme 1]

... (One)
[Reaction Scheme 2]

... (2)
In Reaction Scheme (1) or (2),
R ₁ and R ₂ are selected from the group comprising hydrogen, an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group having 1 to 20 carbon atoms, ditetrabutyl dicarbonate styrene carbonate and a lactone group,
AIBN is azobisisobutylonitrile, THF is tetrahydrofuran,
a + b + c = 1 and l + m + n = 1. The method of claim 7, wherein
A, b, c are 0 <a ≤ 0.02, 0 <b ≤ 0.8, 0 <c ≤ 0.1, l, m, n is 0 <l ≤ 0.1, 0 <m ≤ 0.7, 0 <n ≤ 0.6 A method for producing a positive polymer resist, characterized in that.

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