KR20220114469A - Method for manufacturing metal nanostructures - Google Patents

Abstract

The present invention relates to a manufacturing method of a new metal nano-structure providing an enhanced Raman signal. According to the present invention, when proceeding surface-enhanced Raman scattering spectroscopy by using the manufacturing method of a new metal nano-structure, a Raman signal is significantly improved to significantly improve detection sensitivity.

Description

Method for manufacturing metal nanostructures

The present invention relates to a method for manufacturing a novel metal nanostructure that provides an enhanced Raman signal.

Raman scattering is a phenomenon in which the energy (hv) of an incident photon is scattered with energy (hv') of a different frequency while changing the vibrational state of the molecule, and the scattering at this time belongs to inelastic scattering. Since Raman scattering exhibits a unique photon energy change (Raman shift) form depending on a molecular structure that interacts with photons to induce scattering, it can be effectively used for detection, confirmation and analysis of molecules. By using Raman spectroscopy using Raman scattering, a signal can be obtained even for a non-polar molecule with an induced polarization change of the molecule, and virtually all organic molecules have an inherent Raman shift. In addition, since it is not affected by interference by water molecules, it is more suitable for the detection of biomolecules such as proteins and genes.

On the other hand, since the wavelength of the Raman emission spectrum indicates the chemical composition and structural characteristics of the light-absorbing molecules in the sample, the analysis target material can be directly analyzed by analyzing such a Raman signal.

As such, despite the advantage of being able to directly analyze the analyte material, the signal strength is very weak, making it difficult to put it into practical use. However, since surface-enhanced Raman scattering was reported by Fleishmann et al. in 1974, studies to amplify the signal intensity have been continuously increasing.

Since Raman scattering is inherently weak in signal, it requires a long exposure to a high-power laser to detect a molecule. Raman scattering (SERS) spectroscopy.

On the other hand, the significant enhancement of Raman scattering enables single-molecule detection and thus can provide one of the most sensitive optical signals. Because surface-enhanced Raman scattering (SERS) is mainly due to electromagnetic field enhancement induced by excitation of localized surface plasmons in the vicinity of metallic nanostructures, design and synthesize metallic nanostructures that generate strong electromagnetic fields. Many efforts are being made to do so.

Surface-enhanced Raman scattering (SERS) is a Raman spectroscopy signal (Raman spectroscopy) of molecules adsorbed to plasmonic nanostructures by localized surface plasmon resonance (LSPR) generated in noble metal nanostructures such as gold, silver, and copper. ) is amplified to 10 ⁶ or more, and it is a technology capable of Raman analysis of trace samples of ppb or less. When molecules exist in a nanogap formed between nanostructures, a plasmonic coupling phenomenon occurs between adjacent nanostructures on a substrate, thereby generating an enhanced Raman signal of the molecule.

1 shows the principle and advantages of surface-enhanced Raman spectroscopy.

As shown in FIG. 1, surface-enhanced Raman spectroscopy (SERS) is capable of detecting the intensity of a signal down to the level of a single molecule when molecules emitting a Raman signal are on the surface of a metal nanostructured substrate. It is a measurement method that uses a phenomenon that is augmented to a certain extent. In general, the smaller the distance between nanoparticles constituting the metal nanostructure, that is, the nanogap, the higher the intensity of the Raman signal generated by surface-enhanced Raman spectroscopy (SERS). Therefore, it is preferable to minimize the nanogap.

The nanostructure for forming the nanogap is a conventional representative technique, (1) forming a mask on a silicon substrate through an exposure process and forming silicon and metal nanorods through plasma etching, (2) nanoimprint ( nanoimprint) process to form high-aspect-ratio polymers and metal nanorods. In addition, in the prior art, there is a case in which noble metal nanostructures are manufactured by applying various nanoprocesses, such as (3) a technique for forming uniform metal nanorods by metal nanowires.

In the method of (1), the number (density) of silicon/noble metal nanorods per unit area is up to 18 pieces/μm ² , which is tens of nm away from neighboring nanorods, so that a nanogap that is a hot spot is not formed. Therefore, in order to form a nanogap, a nanogap can be formed using the high aspect ratio metal nanorod closing phenomenon by applying a capillary force of a solvent. As a document using the method of (1), there is "Large area fabrication of leaning silicon nanopillars for surface enhanced Raman spectroscopy" described in [Advanced Materials, 2012, 24, OP11-OP18]. In this technique, high aspect ratio silicon nanorods having a diameter of 50-80 nm and a height of 600-1600 nm were manufactured by etching a silicon substrate with SF6 gas in a plasma state. Thereafter, Ag and Au were deposited to form plasmonic nanorods. As a patent document, there is a US registered patent US 8767202 B2.

The method of (2) is characterized in that the density of the noble metal nanorods is at most 25/μm ² and the distance between the nanorods is separated by several tens of nm. Therefore, as in (1), it is possible to form a nanogap using the closing phenomenon of the high aspect ratio metal nanorods by applying a capillary force. As a document using the method of (2) above, there is “Hot-spot engineering in polygonal nanofinger assemblies for surface enhanced Raman spectroscopy” described in [Nano Letters, 2011, 11, 2538-2542]. Au is vacuum deposited on the polymer nanorods formed through .

As a document using the method of (3) above, there is "3D Cross-point Plasmonic Nano-architectures Containing Dense and Regular Hot Spots for Surface-Enhanced Raman Spectroscopy Analysis" described in [Advanced materials, 2016, 28, 8695-8704]. This technology is characterized by forming a plasmonic nanostructure by stacking nanowires in a 3D structure.

It is an object of the present invention to provide a method for manufacturing a novel metal nanostructure providing an enhanced Raman signal.

In addition, another technical problem to be solved by the present invention is a method of manufacturing a metal nanostructure that controls the surface energy of the substrate through surface treatment of the substrate, deposits a metal mask thereon, and provides an improved Raman signal according to the surface energy, and To provide a metal nanostructure manufactured through this.

In order to achieve the above technical object, the present invention comprises the steps of surface-treating a template substrate or a base substrate;

coating the substrate with surface energy;

depositing metal nanoparticles on the coated substrate;

manufacturing a nanostructure by etching the substrate on which the metal nanoparticles are formed; and

Depositing a metal exhibiting localized surface plasmon resonance (LSPR) on the substrate on which the nanostructure is formed to form a metal nanostructure; provides a method of manufacturing a metal nanostructure comprising a.

In addition, the present invention provides a metal nanostructure manufactured by the method for manufacturing the metal nanostructure.

In addition, the present invention provides a substrate for surface-enhanced Raman scattering spectroscopy, characterized in that it comprises a metal nanostructure manufactured according to a method for manufacturing a metal nanostructure.

The high-density nanostructured surface-enhanced Raman spectroscopy substrate structure using a low surface energy substrate and a metal mask according to the present invention consists of a nanostructured metal deposition thin film of various designs formed through an etching (etching) process on the upper portion of the substrate, and As for the nanostructure, a metal mask having nanometal particles of different shapes is generated according to the surface treatment of the substrate, and nanostructures having different shapes can be formed depending on the metal mask.

The method for manufacturing a surface-enhanced Raman spectroscopy substrate having a high-density nanostructure using a low surface energy substrate and a metal mask according to the present invention is a water-repellent coating having low surface energy using a process chamber and a resistance heating boat installed inside the process chamber. As a method of generating a metal nanoparticle mask by performing metal deposition with A surface-enhanced Raman spectroscopy substrate having a high-density nanostructure by resistance heating coating or sputtering is performed.

When surface-enhanced Raman scattering spectroscopy is performed using the metal nanostructures manufactured using the novel metal nanostructure manufacturing method of the present invention, the Raman signal is remarkably improved and the detection sensitivity is remarkably improved.

1 shows the principle and advantages of surface-enhanced Raman spectroscopy.
2 is an embodiment of the structure of a nanostructure surface-enhanced Raman spectroscopy substrate using a plurality of metal nanoparticle masks according to the present invention. 2 is a cross-sectional image of a metal nanostructure analyzed by a field emission scanning electron microscope (FE-SEM) of the metal nanostructure, and the bottom of FIG. 2 is a metal nanostructure analyzed by a field emission scanning electron microscope (FE-SEM) It is a surface image.
3 shows the shape of the metal nanoparticle mask according to the difference in surface energy of the substrate taken with a field emission scanning electron microscope (FE-SEM). 3 (a) is a shape of a metal nanoparticle mask having a triangular structure manufactured by the method of Comparative Example 1, FIG. 3 (b) is a shape of a metal nanoparticle mask having a rectangular structure manufactured by the method of Comparative Example 2; 3(c) is a shape of a metal nanoparticle mask having a mushroom structure manufactured by the method of Example 1. The left side of each figure is a cross-sectional image analyzed with a field scanning electron microscope (FE-SEM), and the contact angle between the substrate and the metal nanoparticle mask is shown, and the right side is a metal nanoparticle analyzed with a field emission scanning electron microscope (FE-SEM). This is the surface image of the particle mask.
4 shows that the etching process was performed using a metal nanoparticle mask according to the difference in surface energy of the substrate, and the nanostructures manufactured through this were taken with a field emission scanning electron microscope (FE-SEM). 4(a) is a nanostructure having a triangular structure prepared by the method of Comparative Example 1, FIG. 4(b) is a nanostructure having a rectangular structure prepared by the method of Comparative Example 2, FIG. 4(c) is an Example It is a nanostructure having a mushroom structure prepared by the method of 1.
5 is an example of measuring and comparing Raman signals with surface-enhanced Raman spectrometers of different structures fabricated through the present invention.
6 is an example of measuring and comparing the Raman signals of the mushroom-structured surface-enhanced Raman spectroscopy substrate and the flat-structured substrate manufactured through the present invention.
7 shows that the shape of metal nanoparticles is changed according to the surface treatment of the substrate, and a nanostructure having a specific structure can be prepared through etching.
8 is a result of confirming the difference in Raman signal measurement according to the difference in etching time of the substrate.

Hereinafter, the present invention will be described in detail.

The technical core of the present invention is to form a surface treatment coating film having different surface energy on the upper portion of the substrate, to create a metal nanoparticle mask through deposition, and to form nanostructures of different sizes and shapes through an etching process. will be

Using the manufacturing process of the present invention, various nanostructures are made through a plurality of metal nanoparticle masks having different sizes, heights, intervals or shapes, and metals such as gold, silver, and copper are deposited to form metal nanostructures and nanogap can be precisely controlled, and through this, optimization can be carried out according to the target material to be analyzed, thereby optimizing the detection sensitivity of the sample by improving the Raman signal.

The present invention comprises the steps of surface-treating a substrate;

coating the substrate with surface energy;

depositing metal nanoparticles on the coated substrate;

manufacturing a nanostructure by etching the substrate on which the metal nanoparticles are formed; and

Depositing a metal exhibiting localized surface plasmon resonance (LSPR) on the substrate on which the nanostructure is formed to form a metal nanostructure; provides a method of manufacturing a metal nanostructure comprising a.

1 shows the principle and advantages of surface-enhanced Raman spectroscopy, and FIG. 2 shows the structure of a surface-enhanced Raman spectroscopy substrate for metal nanostructures using a metal nanoparticle mask according to the present invention.

The structure of the surface-enhanced Raman spectroscopy substrate using the metal nanoparticle mask according to the present invention is characterized in that the nanostructure is formed on the upper portion of the substrate through the metal nanoparticle mask, and the metal deposition film is sequentially arranged thereon.

The substrate is made of at least one non-metal material selected from the group consisting of glass, silicon (Si), gallium arsenide (GaAs), glass, quartz, and polymer. can

The surface energy of the coating film in the surface energy coating step is 18 mN/m or less, 17 mN/m or less, 3 to 17 mN/m, 3 to 18 mN/m, 5 to 17 mN/m, 5 to 18 mN/m , 13 to 18 mN/m, may be characterized as 13 to 32 mN/m, preferably 13 to 17 mN/m.

In the surface energy coating step, a low surface energy coating having a uniform and excellent adhesion can be performed through the atmospheric pressure plasma treatment process of the glass substrate.

On the other hand, the metal nanospheres prepared by the method of the present invention include a low surface energy coating film formed on the substrate and a metal nanoparticle mask formed on the low surface energy coating film, and the surface of the low surface energy coating film formed on the substrate. It may be characterized in that the difference in surface energy of the mask on which the metal nanoparticles are deposited compared to the energy is 100 mN/m or more.

In the step of surface energy coating the substrate, a low surface energy coating film may be formed through a coating agent treatment, and the coating agent is perfluoropolyether (PFPE), fluorocarbon carboxylic acid, hydrocarbon thiol (alkanethiol) ), hydrocarbon disulfide (alkyldisulfide), fluorocarbon thiol, fluorocarbon silane, chlorocarbon silane, fluorocarbon amine, fluorocarbon carboxylic acid, carbonization It may be characterized in that at least one selected from the group consisting of fluorocarbon polymers and derivatives thereof.

The water contact angle of the substrate on which the low surface energy coating film is formed may be 80° or more, and the thickness of the low surface energy coating film may be 100 nm or less.

In addition, the low surface energy coating film may be formed by vacuum deposition or vapor deposition or a solution process.

Through the step of depositing metal nanoparticles on the coated substrate, the nanoparticle mask can be manufactured by depositing a metal on the low surface energy coating film formed in the step of surface energy coating the substrate.

In the step of depositing the metal nanoparticles on the coated substrate, the metal is any one or more nanoparticles selected from the group consisting of silver, gold, platinum, aluminum, copper, chromium, lead, nickel, iron, tungsten and cobalt. can be characterized.

In addition, in the step of depositing the metal nanoparticles on the coated substrate, the nanomask may be manufactured through a resistance heating method or a sputtering method.

In the step of depositing the metal nanoparticles on the coated substrate, the metal nanoparticles are deposited at a deposition rate of 1.0 Å/sec or less, and the thickness may be 30 nm or less.

The metal nanoparticle mask may be formed in a spherical or hemispherical shape according to a difference in surface energy with the low surface energy coating film.

In the step of depositing the metal nanoparticles on the coated substrate, the contact angle between the substrate and the metal-nanoparticles may be 50 to 150˚, preferably 115 to 150˚.

In the step of depositing the metal nanoparticles on the coated substrate, the thickness between the metal and the substrate may be 5 to 30 nm.

In the step of depositing the metal nanoparticles on the coated substrate, the metal nanoparticles may have a diameter of 30 to 170 nm.

In the step of manufacturing the nanostructure by etching the substrate on which the metal nanoparticles are formed, etching is performed using the metal nanoparticles prepared through the step of depositing the metal nanoparticles on the coated substrate as a mask. have.

In the step of etching the substrate, the etching energy is 60 j/cm ² to 360 j/cm ² It may be characterized in that.

The density of RF plasma power used for etching of 1.0 W/cm ² can be converted to 60 J/min/cm ² . If this is multiplied by the time (min), the etching energy (j/cm ² ) can be obtained.

1[W/cm ² ]= 60[J/min/cm ² ] ;

[J/min/cm ² ] x [Time(min)] = [j/cm ² ];

The RF plasma power density is 1.0 W/cm ² , and the optimum etching time under the above conditions is 2 to 5 minutes. If the RF plasma power density is multiplied by 1 to 6 minutes, etching energy of 360 j/cm ² can be obtained from 60 j/cm ² .

60[J/min/cm ² ] x 1min = 60 j/cm ² ;

60[J/min/cm ² ] x 6min = 360 j/cm ² ;

The process of processing the nanostructure using the metal nanoparticles as a mask may be performed through plasma etching (etching).

When plasma etching (etching) the nanostructure is used, it may be characterized by using any one or more gases selected from the group consisting of argon, oxygen, hydrogen, helium, nitrogen, fluorine and chlorine gas.

In the step of making a metal nanostructure or a metal thin film by depositing a metal exhibiting localized surface plasmon resonance (LSPR) on the substrate on which the nanostructure is formed, the metal is silver, gold, platinum, It may be characterized in that it is any one or more metals or metal thin films selected from the group consisting of aluminum, copper, chromium, lead, nickel, iron, tungsten, cobalt, and alloys thereof.

In the step of depositing the metal exhibiting the local surface plasmon resonance, it may be characterized in that the surface plasmon resonance is strengthened by the nano-gap between the metal nanostructures.

The metal thin film on the nanostructure is formed by vacuum deposition, and is uniformly deposited on the nanostructure, but may tend to be concentrated on the upper portion as the deposition proceeds.

The vacuum deposition may use any one of sputtering, evaporation, chemical vapor deposition, and atomic layer deposition, but is not limited thereto.

The metal thin film may use any one of Al, Au, Ag, Cu, Pt, Pd, and alloys thereof, but is not limited thereto. It may be suitable for the metal thin film to apply Au or Ag.

The metal thin film may be formed by vacuum-depositing the Au, Ag, or an alloy thereof to a thickness of 10 nm or more, and the optimized thickness may vary according to the spacing of the nanostructures.

The optimized thickness is determined by the size of the nanogap. The size of the nanogap is suitable to be formed to be 10 nm or less, and at this time, plasmonic coupling occurs between the metal-containing nanostructures to remarkably improve the sensitivity of the substrate for surface-enhanced Raman scattering.

The metal nanostructure may be characterized in that it provides an increased Raman signal in a surface-enhanced Raman scattering (SERS) analysis.

In the step of making the metal nanostructure, the metal nanostructure may be characterized in that it is for a surface-enhanced Raman scattering (SERS) substrate.

The present invention provides a metal nanostructure manufactured by the method for manufacturing the metal nanostructure.

The metal nanostructure may be characterized in that it provides an increased Raman signal.

In addition, the present invention provides a substrate for surface-enhanced Raman scattering spectroscopy, characterized in that it comprises a metal nanostructure.

In addition, the present invention comprises the steps of: i) functionalizing a biomolecule complementary to a nucleic acid to be detected on the surface of the metal nanostructure;

ii) performing hybridization by reacting the functionalized SERS nanoparticles with a sample expected to contain a nucleic acid to be detected; and

iii) performing Raman spectroscopy to confirm the presence, amount, or both of the nucleic acid to be detected to which the SERS nanoparticles are bound.

The sample expected to contain the nucleic acid to be detected may be used as the collected sample itself, or used by separating, purifying, or amplifying the nucleic acid to be detected therefrom.

The nucleic acid detection method may be characterized as a nucleic acid detection method for the diagnosis of disease, identification, confirmation of blood ties, identification of bacteria or cells, or confirmation of origin of animals and plants.

The nucleic acid detection method may be characterized as a single nucleotide polymorphism (SNP) detection method.

3 is a SEM photograph of a metal nanoparticle mask according to an embodiment of the present invention.

3 (a) is a shape of a metal nanoparticle mask having a triangular structure manufactured by the method of Comparative Example 1, FIG. 3 (b) is a shape of a metal nanoparticle mask having a rectangular structure manufactured by the method of Comparative Example 2; 3(c) is a shape of a metal nanoparticle mask having a mushroom structure manufactured by the method of Example 1. The left side of each figure is a cross-sectional image analyzed with a field scanning electron microscope (FE-SEM), and the contact angle between the substrate and the metal nanoparticle mask is shown, and the right side is a metal nanoparticle analyzed with a field emission scanning electron microscope (FE-SEM). This is the surface image of the particle mask.

4 is an SEM photograph of a substrate on which a nanostructure is formed according to an embodiment of the present invention. It has a triangular structure (Comparative Example 1), a rectangular structure (Comparative Example 2), and a mushroom structure (Example 1) according to process conditions. 4(a) is a nanostructure having a triangular structure prepared by the method of Comparative Example 1, FIG. 4(b) is a nanostructure having a rectangular structure prepared by the method of Comparative Example 2, FIG. 4(c) is an Example It is a nanostructure having a mushroom structure prepared by the method of 1.

The metal nanoparticle mask process conditions (refer to Comparative Example 1) for forming the triangular nanostructure are illustratively as follows.

/sec 이하 이며, 증착 두께는 7~10 nm 일 수 있다. Specifically, through surface treatment on a glass substrate, the water contact angle of the substrate is made 90 to 100°, and Ag is vacuum-deposited by the resistance heating method. At this time, the vacuum deposition rate is 0.5

/sec or less, and the deposition thickness may be 7 to 10 nm.

3(a) shows the shape of a metal nanoparticle mask having a triangular structure manufactured by the method of Comparative Example 1, and it can be confirmed that the metal nanoparticle mask is formed in a hemispherical shape as a metal nanoparticle mask for forming a triangular nanostructure. When these hemispherical metal nanoparticles are subjected to a reactive ion etching process using CF ₄ gas for 3 minutes, the nanostructure of FIG. 4(a) can be formed.

The metal nanoparticle mask process conditions (refer to Comparative Example 2) for forming the rectangular nanostructure are illustratively as follows.

/sec 이하 이며, 증착 두께는 12~15nm 일 수 있다. Through surface treatment on the glass substrate, the water contact angle of the substrate is made 100~110°, and Ag is vacuum-deposited by the resistance heating method. At this time, the vacuum deposition rate is 0.5

/sec or less, and the deposition thickness may be 12-15 nm.

3(b) shows the shape of the metal nanoparticle mask having a rectangular structure manufactured by the method of Comparative Example 2, and it can be confirmed that the contact angle of the metal nanoparticle mask for the formation of the rectangular structure nanostructure is formed at 107°. have. When these metal nanoparticles are subjected to a reactive ion etching process using CF ₄ gas for 3 minutes, the nanostructure of FIG. 4(b) can be formed.

The metal nanoparticle mask process conditions (refer to Example 1) for forming the mushroom-structured nanostructure are illustratively as follows.

/sec 이하 이고, 증착 두께는 20 nm일 수 있다. 상기 물접촉각은 금속나노입자 증착 전 물을 사용해 측정한 물과 기판 사이의 접촉각을 의미할 수 있다.Through surface treatment on the glass substrate, the water contact angle of the substrate is made 110~120°, and Ag is vacuum-deposited by the resistance heating method. At this time, the vacuum deposition rate is 0.5

/sec or less, and the deposition thickness may be 20 nm. The water contact angle may mean a contact angle between water and a substrate measured using water before metal nanoparticle deposition.

Figure 3(c) shows the shape of the metal nanoparticle mask having a mushroom structure manufactured by the method of Example 1, and it can be confirmed that the metal nanoparticle mask for forming the mushroom structure nanostructure was formed in a spherical shape. When these spherical metal nanoparticles are subjected to a reactive ion etching process using CF ₄ gas for 3 minutes, the nanostructure of FIG. 4(c) can be formed.

Reactive ion etching (RIE) process conditions for forming the nanostructures are illustratively as follows.

-Initial vacuum degree: 10 mTorr

-Process gas: CF ₄ 40 sccm

-Process pressure: 150 mTorr

-RF plasma power density: 1.0 W/cm2

7 is a schematic view showing that the shape of metal nanoparticles is changed according to the surface treatment of the substrate, and a nanostructure having a specific structure can be prepared through etching.

5 is a view showing the results of evaluation by comparing the Raman spectroscopic characteristics of the multi-nanostructure surface-enhanced Raman spectrometer substrate according to an embodiment of the present invention according to the shape of each nanostructure.

After dripping 3 μL of ethanol solution containing 20 μM methylene blue solution (MB) onto each SERS substrate, drying for 1 hour and evaporating the ethanol solvent, only MB is selectively chemically adsorbed to Au nanostructures. Thereafter, the Raman signal intensity of MB measured on each SERS substrate was compared and evaluated using a portable Raman spectrometer.

6 is a Raman Shift (Raman Shift, cm ^-1 ) of a nanostructure surface-enhanced Raman spectroscopic substrate (Example 1) and a flat substrate having a mushroom structure according to an embodiment of the present invention (Comparative Example 3) The results of comparing the signal intensity according to the following are shown. By amplifying the Raman spectroscopy signal of the molecule adsorbed to the nanostructure having a mushroom structure to 10 ⁶ or more, Raman analysis of trace samples of ppb or less is possible.

On the other hand, it is known that an appropriate surface energy is an important factor for forming silver-nanoparticles and making special nanostructures using them.

Table 2 shows the contact angle of the silver-nanoparticle mask according to each surface energy. According to Table 2, when surface-treated with a surface energy of 35 N/m or higher, the silver-nanoparticle mask was not formed and deposited in the form of a film, and silver (Ag) deposition was not done at all When the film is deposited in the form of a film or silver (Ag) is not deposited, a silver-nanoparticle mask is not generated, so that a nanostructure manufacturing using the same cannot be performed.

Table 3 shows the results of measuring and analyzing Raman signals according to each etching time. As shown in Table 3, when the etching was performed in 2 minutes or less, there was a problem that the Raman signal enhancement was not smooth because the height of the nanostructure was too small. In addition, if excessive etching is performed for more than 5 minutes, first, all the silver-nanoparticle masks are etched away and the nanostructures created through etching are also etched, so that the height of the nanostructures decreases again, and accordingly, the Raman signal enhancement is also has decreased

On the other hand, when etching using silver-nano particles as a mask, the etching gas used CF4 gas, which is advantageous for Si etching and is not harmful to the human body. The pressure may be adjustable with the amount of process gas injected and the throttle valve. However, when the process pressure increases, the etching rate decreases, and when the process pressure is high, it is difficult to form a desired structure through fast etching with strong straightness. At a process pressure of 150 mTorr, 100 nm is etched at an etching rate of 33 nm/min for 3 minutes.

Hereinafter, the present invention will be described in detail by way of Examples and Experimental Examples.

However, the following Examples and Experimental Examples only illustrate the present invention, and the content of the present invention is not limited by the following Examples and Experimental Examples.

Example 1. Surface-enhanced Raman scattering nanostructure with mushroom structure

1-1. Surface treatment process

Sodalime Glass substrate (TASCO, 100 X 100 X 1.1 mmTh) was prepared and the process was carried out with atmospheric plasma (APP Co., Ltd., ILP-450S) equipment. Ar, O ₂ gas is injected at atmospheric pressure through atmospheric plasma equipment to generate plasma with RF power. When the glass substrate is exposed to plasma, the surface energy increases, so that when the substrate is coated, the adhesion between the substrate and the coating film is improved. The atmospheric plasma process conditions were 330 W RF power, Ar 4 L/min and O ₂ A linear plasma was floated at a flow rate of 30 mL/min and exposed four times at a rate of 2 m/min. Through the atmospheric pressure plasma treatment process of the glass substrate, it is possible to achieve a uniform and low surface energy coating with excellent adhesion.

*Atmospheric pressure plasma process conditions

Process power: 330 W

Gas flow rate: Ar 4 L/min & O ₂ 30 ml/min

Speed: 2 m/min 2 round trips

1-2. Low surface energy coating process

The low surface energy coating agent was prepared through the following synthesis process.

Specifically, Cesium fluoride (Aldrich, CsF 99.9%) and Tetraethylene glycol dimethyl ether (Aldrich, TG 99%) were added in a molar ratio of 1:1 and stirred, and then Hexafluoropropylene oxide (3M, HFPO 99.9%) was added at a reaction temperature of 35 It was injected into the reactor at ℃. At this time, hexafluoropropylene (3 M, HFP 99.9%) was used as a solvent. A silane coupling agent introduction reaction was applied to the perfluoropolyether (PFPE) obtained by the above reaction. 1 mol of the silane coupling agent 3-glycidoxypropyltrimethoxy silane (Aldrich, GOPTMS) was added to 1 mol of the PFPE compound, reacted at 35° C. for 7 hours, and then vacuum dried to obtain a final product, a low surface energy coating agent.

Since PFPE contains fluorine, the glass substrate has a very low surface energy, and the silane group helps to increase the adhesion between the glass substrate and the low surface energy coating agent. Coating was carried out on the glass substrate subjected to atmospheric pressure plasma treatment in the 1-1 surface treatment process using the low surface energy coating agent obtained through the above synthesis process and a spin coater (Rhabdos, SE-150LED). The spin coater dropped 5 mL of the low surface energy coating agent onto the glass substrate and proceeded for 10 seconds at a speed of 2000 rpm, forming a thin and uniform film with a thickness of 10 to 20 nm.

*Processing method: spin coating

Speed: 2000 rpm

Time: 10 seconds

Surface energy of substrate: 15 mN/m

1-3. nano mask process

^1-2 In the low surface energy coating process, the substrate coated with low surface energy is coated with silver (Ag) ( TASCO, EAG0LT0006) was deposited to a thickness of 20 nm at a deposition rate of 0.5 Å/sec or less. At this time, due to the difference in surface energy between the low surface energy of the glass substrate and the slowly deposited Ag at 0.5 Å/sec or less, the Ag deposition was not formed as a thin film but as nanoparticles. Surface analysis of the prepared nanoparticles using a field emission scanning microscope (FE-SEM) (JEOL, JSM-7500F) confirmed that nanoparticles having a size of 50 to 150 nm were formed, and by FE-SEM cross-sectional analysis It was confirmed that the contact angle between the substrate and the silver-nanoparticle was 120 to 135˚ (FIG. 3 (C)).

*Processing method: resistance heating deposition method

Initial vacuum: 1.0 x 10 ^-5 Torr

Deposition rate: 0.5 Å/sec

Thickness: 20 nm

1-4. Etching process

In the etching process, silver-nanoparticles having a high contact angle of 120 to 135˚ manufactured through the 1-3 nano mask process were used as a mask. This etching process was performed using reactive ion etching (Artek Systems, RIE) equipment. The silver-nano-particles on the glass substrate act as a mask, so that where silver-nano-particles are formed, etching is not performed, and where silver-nano-particles are not formed, etching proceeds to form nanostructures. At this time, a mushroom-shaped nanostructure was prepared due to the spherical silver-nanoparticle mask having a high contact angle (Fig. 4(c)).

On the other hand, when the silver-nanoparticle mask has a low contact angle, the mask is etched together to form a triangular or rectangular structure (FIG. 4(d)).

The etching process conditions using the RIE equipment are as follows. At the initial vacuum degree of 10 mtorr of the RIE equipment, CF ₄ (MS gas, CF ₄ ), a process gas suitable for glass etching, was injected 40 sccm to create a process pressure of 150 mtorr, 1-3. The substrate calculated in the nanomask process was etched for 3 minutes at an RF plasma power density of 1.0 W/cm 2 .

As a result of confirming the etching result by FE-SEM, the glass substrate was etched with an average of 100 nm at an etching rate of 33 nm/min to form a mushroom-shaped nanostructure (FIG. 4(C)).

*Process method: RIE

Initial vacuum: 10 mTorr

Process gas: CF ₄ 40 sccm

Process pressure: 150 mTorr

RF Plasma Power Density: 1.0 W/cm2

Process time: 3 minutes

1-5. deposition process

A surface-enhanced Raman spectrometer was manufactured by depositing gold (Au) (TASCO, EAU0KI0001) on the nano mushroom structure formed through the 1-4 etching process. In the gold deposition process, 120 nm deposition was performed at a deposition rate of 1.5 Å/sec through a resistance heating deposition method (Thermal Evaporator (ULTECH, EasyDEP-3)) in a high vacuum of 1.0 x 10 ^-5 Torr or less. As the thickness of gold increases and the gap between nanostructures becomes narrower, the performance as a surface-enhanced Raman spectroscopy substrate is improved. It is known that the enhancement index increases to 108 when the spacing between nanostructures is narrowed to ¹ nm. When gold is gradually deposited thickly, the enhancement factor increases, and the gap between the nanostructures disappears above a certain thickness and is deposited in the form of a film rather than a nanostructure, resulting in poor performance as a surface-enhanced Raman spectroscopy substrate. Finally, the thickness of the deposited gold was optimized to 120 nm.

Raman signal measurement was carried out using a surface-enhanced Raman spectrometer having a mushroom structure prepared in the same manner as in Example 1. Methylene blue (MB) (Samjeon pure medicine, M0796) was diluted in ethanol (Samjeon pure medicine, EtOH 99%) to make a concentration of 20 μM, and as a result of Raman analysis, a signal strength of about 69000 can be confirmed at the main peak, 1624 cm ^-1 . There was (Test Example 1 and FIG. 5).

*Process method: resistance heating deposition method

Initial vacuum: 1.0 x 10 ^-5 Torr

Deposition rate: 1.5 Å/sec

Thickness: 120 nm

Methylene blue 20 μM Raman analysis (at 1624cm ^-1 ): 69,889 intensity (au)

Comparative Example 1. Surface-enhanced Raman scattering nanostructure with triangular structure

A nanostructure was prepared in the same manner as in Example 1, but 1-2 After the low surface energy coating process, the surface energy was set to 25 mN/m through 1-1 atmospheric plasma treatment. The atmospheric pressure plasma process conditions were 330 W RF power, Ar 4 L/min and O ₂ A linear plasma was floated at a flow rate of 30 mL/min and exposed to the plasma twice at a rate of 10 m/min. When exposed to plasma, a difference in surface energy was made by using the characteristic of increasing surface energy, and in the 1-3 nano mask process of Example 1, 20 nm silver (Ag) deposition was reduced to a thickness of 10 nm and proceeded to 70~80˚ A silver-nanoparticle mask having a contact angle of was prepared (Fig. 3(a)).

As a result, as shown in Fig. 4(a), a surface-enhanced Raman scattering nanostructure having a triangular structure was prepared.

*Surface energy: 25~30 mN/m

*Methylene blue 20μM Raman analysis (at 1624cm ^-1 ): 6235 intensity (au)

Comparative Example 2. Surface-enhanced Raman scattering nanoparticles having a rectangular structure

A nanostructure was prepared in the same manner as in Example 1, but 1-2 After the low surface energy coating process, the surface energy was adjusted to 20 mN/m through 1-1 atmospheric pressure plasma treatment. The atmospheric pressure plasma process conditions were 330 W RF power, Ar 4 L/min, and O ₂ A linear plasma was floated at a flow rate of 30 mL/min and exposed to plasma once at a rate of 10 m/min. The surface energy difference was made by using the property that the surface energy increases when exposed to plasma, and in the 1-3 nano mask process of Example 1, silver (Ag) 20 nm deposition was reduced to a thickness of 15 nm and proceeded to 100~110˚ A silver-nanoparticle mask having a contact angle of was prepared (Fig. 3(b)).

As a result, a surface-enhanced Raman scattering nanostructure having a rectangular structure as shown in FIG. 4(b) was prepared.

*Surface energy: 20 mN/m

*Methylene blue 20μM Raman analysis (at 1624cm ^-1 ): 40,175 intensity (au)

Comparative Example 3. Substrate having a planar structure

Example 1-1 Surface treatment process, 1-2 low surface energy coating process, 1-3 nano mask process, and 1-4 etching process are omitted, and only 1-5 deposition process is performed to manufacture a gold substrate having a planar structure did. Gold (Au) (TASCO, EAU0KI0001) was deposited at 120 nm on a Sodalime Glass substrate (TASCO, 100 X 100 X 1.1 mmTh). As a result, a gold substrate having a planar structure was manufactured.

*Methylene blue 20μM Raman analysis (at 1624cm ^-1 ): 20 intensity (au)

Test Example 1. Raman signal measurement and analysis

Different silver nanoparticles prepared in the same manner as in Example 1 and Comparative Examples 1 to 3 were used as masks to prepare surface-enhanced Raman spectroscopic substrates having different nanostructures.

Methylene blue (MB) (Samjeon Soonyak, M0796) was analyzed using the surface-enhanced Raman spectrometer of different nanostructures prepared above. Methylene blue was diluted in ethanol (Samjeon Pure Chemical, EtOH 99%) to a concentration of 20 μM to measure the Raman signal.

The measurement conditions in this example are as follows.

- Measured molecule: 20 μM methylene blue (Methylene Blue, MB)

- excitation laser wavelength: 633 nm

- Laser power and measurement time: 5 mW and 1 second

- spot size: 20 μm

- Measuring equipment: Raman spectrometer (PRISM, NOST)

As a result, as shown in FIG. 5, the strongest Raman signal was confirmed in the mushroom-shaped nanostructure prepared in the same manner as in Example 1 (signal intensity of about 69000 at the main peak, 1624 cm ^-1 ), and a rectangular structure ( A strong Raman signal was confirmed in the order of Comparative Example 2) and the triangular structure (Comparative Example 1). At 1624cm ^-1 of the main pick, the mushroom structure exhibited Raman signals of 69889 intensity (au), the rectangular structure 40175 intensity (au), and the triangular structure 6235 intensity (au).

In addition, as shown in FIG. 6 , in the flat gold substrate (Comparative Example 3), a Raman signal of less than 100 intensity (a.u.) was measured to be very low. In order to confirm the Raman signal on the flat gold substrate, a higher concentration of methylene blue than the nanostructured substrate and a laser irradiation time of 30 seconds were applied.

The conditions for confirming the Raman signal on the flat gold substrate are as follows.

- Measured molecule: 100μM methylene blue (Methylene Blue, MB)

- excitation laser wavelength: 633 nm

- Laser power and measurement time: 5mW and 30 seconds

- spot size: 20 μm

- Measuring equipment: Raman spectrometer (PRISM, NOST)

Table 1 shows the Raman shift (Raman Shift, cm ^- The results of comparing the signal intensity according to ¹ ) according to the shape of each nanostructure are shown.

Raman Shift (cm ^-1 ) triangular structure square structure mushroom structure Triangular structure contrast
Mushroom structure signal increase rate 443 cm ^-1 2133.901 26210.58 48805.76 22.9 times 1397 cm ^-1 2818.087 29488.96 54279.44 19.3 times 1624 cm ^-1 6235.867 40175.41 69889.36 11.2 times

As can be seen in Figure 5 and Table 1, the surface-enhanced Raman spectroscopy substrate manufactured by the present invention had a signal enhancement of 11 to 22 times compared to other nanostructures regardless of the Raman shift of MB.

Test Example 2. Surface Energy Numerical Range

A nanostructure was prepared in the same manner as in Example 1, but 1-2 After the low surface energy coating process, 1-1 atmospheric pressure plasma treatment was performed, and the surface energy treated at this time is shown in Table 2. Surface-enhanced Raman spectroscopy substrates having different nanostructures were prepared using different silver-nanoparticles prepared respectively as masks, and Raman signals were measured and analyzed in the same manner as in Test Example 1.

As a result, as shown in Table 2, when proceeding at a surface energy of 35 N/m or higher, the silver-nanoparticle mask was not formed and was deposited in the form of a film, and silver (Ag) was deposited at a surface energy that was too low (10 N/m or less). This was not done at all.

Surface energy (N/m) 10 15 20 25 30 35 Silver (Ag) deposition form X nanoparticles nanoparticles nanoparticles nanoparticles film Silver-nanoparticle contact angle - 135˚ 110˚ 80˚ 60˚ -

Test Example 3. Etching time range

A nanostructure was prepared in the same manner as in Example 1, but the etching times of the 1-4 etching processes were changed as shown in Table 3, respectively. Surface-enhanced Raman spectroscopy substrates having different nanostructures were prepared using different silver-nanoparticles prepared respectively as masks, and Raman signals were measured and analyzed in the same manner as in Test Example 1.

As a result, as shown in Table 3, when the etching was performed in 2 minutes or less, there was a problem in that the height of the nanostructure was too small, so that the Raman signal enhancement was not smooth. In addition, when excessive etching is performed for more than 5 minutes, first, all of the silver-nanoparticle masks are etched away and the nanostructures generated through the etching are also etched, causing a problem in that the height of the nanostructures is reduced again.

Raman Shift (cm ^-1 ) 1 min (33 nm) 2 min (66 nm) 3 min (100 nm) 4 min (133 nm) 5 min (166 nm) 1624 cm ^-1 - 23297.15 69889.36 62084.78 59187.12

Claims (19)

surface treatment on the substrate;
coating the substrate with surface energy;
depositing metal nanoparticles on the coated substrate;
manufacturing a nanostructure by etching the substrate on which the metal nanoparticles are formed; and
and depositing a metal exhibiting localized surface plasmon resonance (LSPR) on the substrate on which the nanostructure is formed to form a metal nanostructure.
The method of claim 1, wherein the surface energy in the surface energy coating step is 13 to 32 mN/m or less.
The method of claim 1, wherein the surface energy in the surface energy coating step is 13 to 18 mN/m or less.
According to claim 1, wherein the coating agent used in the surface energy coating step perfluoropolyether (Perfluoropolyether, PFPE), fluorocarbon carboxylic acid (fluorocarbon carboxylic acid), hydrocarbon thiol (alkanethiol), hydrocarbon disulfide (alkyldisulfide), fluorocarbon thiol (fluorocarbon thiol), fluorocarbon silane (fluorocarbon silane), chlorocarbon silane (chlorocarbon silane), fluorocarbon amine (fluorocarbon amine) fluorocarbon carboxylic acid (fluorocarbon carboxylic acid) and fluorocarbon polymer selected from the group consisting of (fluorocarbon polymer) Any one or more, characterized in that the manufacturing method of a metal nanostructure.
The method of claim 1, wherein in the step of depositing the metal nanoparticles, the metal is any one or more nanoparticles selected from the group consisting of silver, gold, platinum, aluminum, copper, chromium, lead, nickel, iron, tungsten and cobalt. A method of manufacturing a metal nanostructure, characterized in that.
The method of claim 1 , wherein in the step of depositing the metal nanoparticles on the coated substrate, the contact angle between the substrate and the metal-nanoparticles is 50 to 150°.
The method of claim 1, wherein in the step of depositing the metal nanoparticles on the coated substrate, the contact angle between the substrate and the metal-nanoparticles is 115 to 150°.
The method of claim 1, wherein the thickness between the metal and the substrate in the step of depositing the metal nanoparticles on the coated substrate is 5 to 30 nm.
The method of claim 1, wherein in the step of depositing the metal nanoparticles on the coated substrate, the metal nanoparticles have a diameter of 30 to 170 nm.
The method of claim 1, wherein the etching energy in the step of etching the substrate is 60 j/cm ² to 360 j/cm ² .
According to claim 1, wherein in the step of etching the substrate, any one or more gases selected from the group consisting of argon, oxygen, hydrogen, helium, nitrogen, fluorine and chlorine gas is used, the production of metal nanostructures Way.
According to claim 1, wherein in the step of depositing the metal exhibiting the localized surface plasmon resonance, the metal is any one or more of silver, gold, platinum, aluminum, copper, lead, and alloys thereof, characterized in that the metal nanostructures manufacturing method.
The method of claim 1 , wherein, in the step of depositing the metal exhibiting the local surface plasmon resonance, the surface plasmon resonance is strengthened by the nano-gap between the metal nanostructures.
The metal of claim 1, wherein the substrate is made of a non-metal material selected from the group consisting of glass, silicon (Si), gallium arsenide (GaAs), quartz and polymer. A method for manufacturing a nanostructure.
The method of claim 1 , wherein the metal nanostructure provides an increased Raman signal in Surface-Enhanced Raman Scattering (SERS) analysis.
The method of claim 1, wherein in the step of making the metal nanostructures, the metal nanostructures are for surface-enhanced Raman scattering (SERS) substrates.
A metal nanostructure manufactured by the method of claim 1 .
18. The metal nanostructure of claim 17, wherein the metal nanostructure provides an increased Raman signal.
A substrate for surface-enhanced Raman scattering spectroscopy, characterized in that it comprises a metal nanostructure prepared according to any one of claims 1 to 16.

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