KR20150135592A - Graphene and method of surface treatment thereof - Google Patents

Abstract

The present invention provides a method for surface treatment of graphene, which comprises spraying a gas cluster on graphene, has the effect of reducing surface roughness, reducing surface resistance and increasing adhesion to a substrate.

Description

TECHNICAL FIELD [0001] The present invention relates to graphene,

The present invention relates to graphene and a surface treatment method thereof. More particularly, the present invention relates to a graphene having reduced roughness and surface resistance and increased adhesion, and a method for surface treatment thereof.

In addition to the miniaturization of electronic devices, the importance of surface treatment such as cleaning and planarization is becoming more and more important, and the demand for development of surface treatment technology is increasing. Conventional surface treatment technology is a chemical-based wet method and has various difficulties such as surface damage, chemical reaction, by-products and cleaning efficiency.

Therefore, a dry type is actively being introduced, and a representative example is aerosol. An aerosol forms an aerosol using a gaseous working gas and performs surface treatments such as cleaning and planarization by direct physical collision with surface contaminants.

However, pattern damage occurs due to particles generated in the aerosol generated. Also, surface treatment such as cleaning and planarization using a gas cluster device is being studied to overcome such problems.

On the other hand, graphene is transparent and absorbs only 2.3% of light, but it has higher thermal conductivity than silver at room temperature, and electrons can move as if there is no mass, so electricity flow faster than existing semiconductors. .

Graphene is also the thinnest material in the world. It has a higher current density than copper and a quantum Hall effect observed only at a very low temperature. It has various characteristics such as strength, thermal conductivity and electron mobility. It is recognized as a strategic core material that will lead the growth of related industries by applying to various fields such as display, rechargeable battery, solar cell, automobile and lighting.

Although graphene has a need to improve the resistance, roughness and adhesive force by removing residual substances on the surface and planarizing the surface thereof, there is a great difficulty in surface treatment because it is a very thin structure. there was.

That is, in the past, there was no technique for cleaning and planarizing graphene, and in particular, there was no physical method that excluded chemical methods. However, it is disclosed in PCT-KR2010-007140 that a cleaning process can be performed using isopropyl alcohol (IPA), deionized water, and the like during the transferring process of graphene, and in the PCT-US2010-024723, Plasma etching, low-energy ion collision etching and so on.

In addition, the cleaning and planarization method using the gas cluster device which is being studied recently uses gas clusters. Gas clusters are a collection of tens or hundreds of molecules of the working gas, and the clusters formed form a size of several nanometers. And grow to tens of nm in size by short time condensation. Unlike aerosols, the clusters do not form the environment and time to grow, forming a small cluster, which minimizes pattern damage and removes and smoothens the polluted particles with relatively high efficiency. Surface treatment by gas clusters has been applied variously to semiconductor devices, sample surfaces, and silicon substrates, but it has not been applied to monomolecular layers such as graphene.

It is an object of the present invention to provide graphene and a method of surface treatment thereof.

Another object of the present invention is to provide a graphene having improved adhesion as well as reduction of surface roughness and surface resistance and a method of treating the surface thereof.

The above and other objects of the present invention can be achieved by the present invention described below.

One aspect of the present invention relates to a method for surface treatment of graphene.

According to one embodiment, the method includes injecting a gas cluster into the graphene.

According to another embodiment, the gas may comprise at least one of carbon dioxide, argon and nitrogen.

According to another embodiment, the average particle size of the gas clusters may be between 30 and 600 nm.

According to another embodiment, the firing angle of the gas clusters may be between 5 and 45 degrees.

According to another embodiment, the jet velocity of the gas clusters can be 150 to 850 m / s.

According to another embodiment, the firing distance of the gas clusters may be between 35 and 85 mm.

According to another embodiment, the gas clusters are ejected from the nozzles, and the cooling temperature of the nozzles may be from -85 to -20 占 폚.

According to another embodiment, the graphene may be formed by forming a graphene layer on a transition metal and forming a support layer on the graphene layer to form a laminate in which a transition metal layer-graphene layer-support layer is laminated, Removing the transition metal layer, laminating the graphene layer from which the transition metal layer has been removed on the substrate, and removing the support layer.

According to another embodiment, the gas clusters may be injected from one or more nozzles.

Another aspect of the present invention is to provide surface-treated graphene.

According to one embodiment, the graphene is surface treated by any of the above methods and the surface roughness may be from 3 to 50 nm.

INDUSTRIAL APPLICABILITY The present invention has the effect of not only reducing the roughness and surface resistance, but also providing graphene having an increased adhesive force and a method of treating the surface thereof.

FIG. 1 schematically shows a graphene surface treatment method according to one embodiment of the present invention.
FIG. 2 is a schematic view of a surface treatment method of graphene according to another embodiment of the present invention.
3 schematically shows a surface treatment method of graphene according to another embodiment of the present invention.
4 schematically illustrates a gas cluster injector according to one embodiment of the present invention.
5 schematically illustrates a method of forming graphene according to one embodiment of the present invention.
6 is an AFM (Atomic Force Microscope) photograph of graphene deposited on copper (Cu) according to Comparative Example 1. Fig.
FIG. 7 is an AFM (Atomic Force Microscope) photograph of graphene transferred onto the substrate according to Comparative Example 2. FIG.
8 is an AFM (Atomic Force Microscope) photograph of a surface-treated graphene according to Example 1. Fig.
9 is a graph showing surface roughnesses of Comparative Example 1 (e), Comparative Example 2 (f), and Example 1 (g).
10 is a graph showing the surface resistances of Example 1 (b), Example 2 (c), Example 3 (d), Example 4 (a) and Comparative Example 2 (original).

In the present invention, the 'spray angle' is the 'angle formed by the average spray direction of the substrate cluster and the gas cluster'.

In the present invention, 'injection speed' is 'initial velocity of gas injected from gas cluster injector'.

In the present invention, the 'ejection distance' is 'the shortest distance between the ejection port of the gas cluster injector and the surface of the graphene'.

In the present invention, the 'cooling temperature of the nozzle' is the 'temperature formed in the nozzle for cooling the gas cluster'.

The 'support layer' in the present invention is a layer formed to facilitate graphene treatment in the process of removing the transition metal layer and laminating the graphene on the substrate.

Embodiments of the present application will now be described in more detail with reference to the accompanying drawings. However, the techniques disclosed in the present application are not limited to the embodiments described herein but may be embodied in other forms.

It should be understood, however, that the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the width, thickness, and the like of the components are enlarged in order to clearly illustrate the components of each device. Also, while only a portion of the components is shown for convenience of explanation, those skilled in the art will readily recognize the remaining portions of the components.

It is to be understood that when an element is described above as being located above or below another element, it is to be understood that the element may be directly on or under another element, It means that it can be done. Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. In the drawings, the same reference numerals denote substantially the same elements.

It should be understood, however, that the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise, and the terms "comprise" Acts, components, parts, or combinations thereof, but does not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof It should be understood that it does not.

Hereinafter, the present invention will be described in detail.

One aspect of the present invention is to provide a surface treatment method of graphene. Specifically, the present invention provides a graphene surface treatment method characterized by spraying a gas cluster on graphene.

FIG. 1 schematically illustrates a surface treatment method of the graphene 300 according to one embodiment of the present invention.

According to one embodiment, a gas cluster formed to a predetermined size is sprayed onto the graphene 300 to physically impinge on the surface and the residue on the surface of the graphene 300, Planarize, and remove residual material from the surface.

The surface of the graphene 300 is flattened by applying physical collisions with the gas clusters to reduce the roughness of the surface of the graphene 300 and to increase the adhesion with the substrate 100.

In addition, the injected gas clusters are desorbed together with the residual material, thereby having an effect of cleaning, and at the same time, reducing the surface resistance of the graphene 300 due to the reduction of impurities on the surface of the graphene 300.

In FIG. 1, reference numeral 310 schematically shows flattened and cleaned graphene 310 after surface-treating the graphene 300 using a gas cluster.

The gas may comprise one or more of carbon dioxide, argon, and nitrogen. Carbon dioxide, argon, and nitrogen are inert gases and have the advantage of eliminating unwanted ancillary reactions during surface treatment of graphene 300.

For a local chemical reaction, the gas may further include gases other than carbon dioxide, argon, and nitrogen.

The average particle diameter of the gas clusters may be 30 to 600 nm, preferably 100 to 500 nm, more preferably 200 to 400 nm. The cleaning and planarization efficiency of the surface of the graphene 300 can be increased and the tearing of the graphene can be prevented in the above range.

2 schematically shows a surface treatment method of the graphene 300 according to another embodiment of the present invention. Specifically, it is possible to perform the surface treatment of the graphene 300 by adjusting the spray angle of the gas clusters.

The firing angle of the gas clusters may be 5 to 45 degrees, preferably 5 to 35 degrees, more preferably 5 to 25 degrees. The adhesion of the graphene 300 is increased in the above-mentioned range, and the efficiency of surface cleaning and planarization of the graphene 300 is improved.

The jet velocity of the gas clusters may be 150 to 850 m / s, preferably 250 to 750 m / s, more preferably 330 to 670 m / s. In the above range, the surface roughness of the graphene 300 is reduced, and the adhesion of the graphene 300 to the substrate 100 is increased, thereby preventing the graphene 300 from being torn.

According to a specific example, when the flow rate of the gas to be injected is 5 lpm, the average particle size of the gas clusters is 200 to 500 nm, preferably 250 to 450 nm, more preferably 300 to 400 nm, and the gas cluster jetting rate is 280 to 650 m / s , Preferably 320 to 610 m / s, and more preferably 360 to 570 m / s.

According to another embodiment, when the gas flow rate to be injected is 10 lpm, the average particle size of the gas clusters is 160 to 460 nm, preferably 210 to 410 nm, more preferably 260 to 360 nm, and the gas cluster jetting velocity is 320 to 670 m / s, preferably 360 to 630 m / s, more preferably 400 to 590 m / s.

According to another embodiment, when the gas flow rate to be injected is 15 lpm, the average particle diameter of the gas clusters is 120 to 420 nm, preferably 170 to 370 nm, more preferably 220 to 320 nm, and the gas cluster jetting velocity is 350 to 710 m / s, preferably 390 to 670 m / s, and more preferably 430 to 630 m / s.

In the above-described range, the gas clusters can efficiently planarize the graphene deposited in island form on the surface of the graphene 300 and can also prevent the graphene 300 from being torn.

3 schematically illustrates a surface treatment method of the graphene 300 according to another embodiment of the present invention. Specifically, the surface of the graphene 300 can be treated by controlling the ejection distance of the gas clusters.

The ejection distance of the gas clusters may be 35 to 85 mm, preferably 40 to 75 mm, more preferably 50 to 70 mm. There is an advantage that desorption of residual material on the surface of the graphene 300 is effective in the above range.

4 schematically illustrates a gas cluster injector 500 according to one embodiment of the present invention. The gas clusters are grown into particles of a certain size, then through the nozzles 510 and through the gas cluster injector inlet 520. The nozzle 510 may include a cooling device for cooling the gas clusters.

The cooling temperature of the nozzle may be -85 to -20 占 폚, preferably -75 to -30 占 폚, and more preferably -65 to -40 占 폚. The size of the gas clusters can be easily adjusted within the above range.

5 schematically illustrates a method of forming graphene according to one embodiment of the present invention.

Specifically, the graphene is formed by forming a graphene layer 300 on the transition metal layer 700 and forming a support layer 800 on the graphene layer 300 to form a transition metal layer 700, a graphene layer 300, The transition metal layer 700 is removed from the laminate and the graphene layer 300 on which the transition metal layer 700 is removed is laminated on the substrate 100, A structure in which the graphene layer 300 is stacked on the substrate 100 by removing the support layer 800 may be formed.

The graphene layer 300 may be formed as a single layer, or may be partially or entirely two or more layers. The number of layers of the graphene layer 300 can be controlled by adjusting the type and thickness of the graphene layer 300, the reaction time, the cooling rate, and the concentration of the reaction gas.

According to a specific example, the method of forming the graphene layer 300 on the transition metal layer 700 may be a chemical vapor deposition method. The chemical vapor deposition method is a method of synthesizing graphene 300 by forming carbon or alloy well at high temperature or using a transition metal having excellent adsorption with carbon as a catalyst.

Specifically, the transition metal reacts with the catalyst layer in a mixed gas atmosphere such as methane and hydrogen at a high temperature of 1,000 占 폚, so that an appropriate amount of carbon is dissolved or adsorbed in the catalyst layer. After cooling, the carbon atoms contained in the catalyst layer are crystallized on the surface to form a graphene (300) crystal structure. The synthesized graphene 300 can be used for a desired application by removing the catalyst layer.

The transition metal may be nickel (Ni), copper (Cu), platinum (Pt), or the like, but is not limited thereto.

According to one embodiment, the catalyst layer may be a copper foil, but is not necessarily limited thereto. The copper foil may have a thickness of 10 탆 to 100 탆, preferably 10 탆 to 70 탆, more preferably 10 탆 to 50 탆. In the above range, not only the graphene deposition efficiency is enhanced but also the transition metal layer 700 can be easily removed.

When a copper foil is used as the catalyst layer, since graphene is deposited on both sides, it may further include a polishing process. The polishing may utilize an oxygen plasma, but is not necessarily limited thereto.

According to another embodiment, the transition metal layer 700 may be a transition metal layer 700 formed on a SiO ₂ / Si substrate. Specifically, the method may further include depositing at least one of nickel (Ni), copper (Cu), and platinum (Pt) on a SiO ₂ / Si substrate by a CVD method. In this case, the thickness of the transition metal layer 700 may be 30 to 1300 nm, preferably 30 to 1000 nm, more preferably 30 to 800 nm. In the above range, the efficiency of graphene deposition as a catalyst layer is improved, and the transition metal layer 700 can be easily removed.

Referring to FIG. 5, the support layer 800 may be formed on the graphene layer 300.

Polymethyl methacrylate (PMMA) or polydimethylsiloxane (PDMS) may be used as the material of the supporting layer 800 in the process of forming the supporting layer 800 on the graphene layer 300, but the present invention is not limited thereto. The support layer 800 may serve to support the graphene 300 layer in the step of removing the transition metal layer 700 and the step of laminating on the substrate 100, For example, 10 nm to 500 nm, and the present invention is not limited thereto.

Specifically, PMMA may be spin-coated or drop-coated on the graphene layer 300 to form a laminate in which a transition metal layer 700, a graphene layer 300, and a support layer 800 are formed. And is not necessarily limited thereto.

The step of removing the transition metal layer 700 may be performed using 0.1 moles of (NH ₄ ) ₂ S ₂ O ₈ aqueous solution, FeCl ₃ solution, or FeNO ₃ (0.05 g / mL). It is also possible to use a dry etching method in which the transition metal layer 700 is removed by using a mixed gas of chlorine gas and argon gas as a plasma and removing the gas by physical impact.

According to FIG. 5, after removal of the transition metal layer 700, the graphene layer 300 may be deposited on the substrate 100. At this time, the support layer 800 can facilitate the deposition of the graphene layer 300 on the substrate 100. The deposition on the substrate 100 may be performed in ionized pure water (DI water), but is not limited thereto.

The step of removing the support layer 800 may be performed using acetone or methanol, but is not limited thereto. Specifically, the support layer 800 can be removed with acetone at a temperature of 40 ° C to 60 ° C.

As another embodiment, the method of forming the graphene 300 may be provided by a chemical stripping method. The chemical stripping method is a method utilizing the oxidation-reduction characteristics of graphite. Graphite oxide is produced by oxidizing graphite with strong acid and oxidizing agent. When it comes into contact with water, water molecules penetrate between the surface and the surface due to strong hydrophilic nature of graphite. Thereafter, when the interplanar spacing of the graphite oxide is spread by the water molecule, the oxidized graphene sheet can be produced through an ultrasonic grinder or the like. Thereafter, impurities are removed through a reduction process to produce graphene.

The step of forming the graphene includes all the methods available for the transfer process, etc., in addition to the above methods.

According to another embodiment of the present invention, the step of injecting gas clusters into the graphene 300 may be performed by one or more nozzles 510. When spraying from two or more nozzles 510, it can be applied to a small-area and large-area graphene, and also it is possible to perform surface treatment for cleaning and planarizing a large-area graphene in a short time.

Another aspect of the present invention is to provide surface-treated graphene.

According to one embodiment, graphene may be graphene surface treated by any of the above methods.

According to another embodiment, the graphene may have a surface roughness of 3 to 50 nm, preferably 3 to 48 nm, more preferably 3 to 45 nm. There is an advantage that the surface resistance of the graphene 300 can be lowered within the above range.

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. However, the following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples. The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

Example

Example 1

After graphene was deposited on a copper foil, graphene was transferred to the substrate. Carbon dioxide (CO ₂ ) having a purity of 99.99% and an average particle diameter of 270 nm was sprayed at a flow rate of 15 lpm at an injection angle of 15 °, a spraying distance of 60 mm, an injection speed of 600 m / s, a nozzle cooling temperature of -50 ° C, / s < / RTI >

Example 2

As shown in Table 1, surface treatment was performed in the same manner as in Example 1, except that the average particle diameter of the gas clusters was 310 nm, the gas flow rate was 10 lpm, and the spraying speed was 560 m / s.

Example 3

The same surface treatment as in Example 2 was carried out to prepare Example 3.

Example 4

As shown in Table 1, surface treatment was carried out in the same manner as in Example 1, except that the gas clusters had an average particle diameter of 350 nm, a gas flow rate of 5 lpm, and an injection speed of 520 m / s.

Gas cluster average particle diameter (nm) Gas flow rate (lpm) Injection angle (°) Distance in minutes (mm) Injection speed (m / s) Cooling temperature of nozzle (℃) Example 1 270 15 15 60 600 -50 Example 2 310 10 15 60 560 -50 Example 3 310 10 15 60 560 -50 Example 4 350 5 15 60 520 -50

Comparative Example 1

Graphene was deposited on a copper foil and was not surface treated.

Comparative Example 2

After graphene was deposited on a copper foil, the graphene was transferred to the substrate and the surface was not treated.

How to measure

1. Roughness measurement method

Surface roughnesses of Example 1, Comparative Example 1, and Comparative Example 2 were measured using Atomic Force Microscopy (AFM) to measure minute changes in roughness after cluster processing of monomolecular layer such as graphene, , Fig. 8, Fig. 9 and Table 2. In FIG. 9, e represents Comparative Example 1, f represents Comparative Example 2, and g represents Embodiment 1.

2. Surface resistance measurement method

A multilayer structure was formed for easy surface resistance measurement. A 500μm Au electrode was deposited on the surface using a thermal deposition method. The overall structure is the order in which the substrate is used as an insulator, the graphene layer is transferred thereon, and the Au electrode is deposited. The surface resistance values of Examples 1, 2, 3, 4 and Comparative Example 2 were measured and shown in FIG. 10 and Table 3. In Fig. 10, original indicates Comparative Example 2, a indicates Embodiment 4, b indicates Embodiment 1, c indicates Embodiment 2, and d indicates Embodiment 3.

Comparative Example 1 Comparative Example 2 Example 1 Average surface roughness (nm) 4.37 2.46 1.42

Comparative Example 2 Example Example 4 Example 1 Example 2 Example 3 Surface Resistance (kΩ) 500 345 330 95 115

As shown in Tables 2 and 3 and FIGS. 6 to 10, the surface roughness and surface resistance of Examples 1 to 4, which were surface treated with gas clusters, were small, while Comparative Examples 1 and 2 Surface roughness and surface resistance are large.

100: substrate 300: graphene
500: Gas Cluster Injector 510: Nozzle
520: injection nozzle 700: transition metal
800: Support layer

Claims (10)

And spraying a gas cluster onto the graphene.
The method of claim 1, wherein the gas comprises at least one of carbon dioxide, argon, and nitrogen.
The surface treatment method of graphene according to claim 1, wherein the average particle diameter of the gas clusters is 30 to 600 nm.
The surface treatment method of graphene according to claim 1, wherein the gas clusters have an injection angle of 5 to 45 degrees.
The surface treatment method of graphene according to claim 1, wherein an ejection velocity of the gas clusters is 150 to 850 m / s.
The surface treatment method of graphene according to claim 1, wherein the gas clusters have an ejection distance of 35 to 85 mm.
2. The apparatus of claim 1, wherein the gas clusters are injected from a nozzle,
Wherein the nozzle has a cooling temperature of -85 to -20 占 폚.
The method of claim 1,
Forming a graphene layer on the transition metal layer;
Forming a support layer on the graphene layer to form a laminate in which a transition metal layer-graphene layer-support layer is laminated;
Removing the transition metal layer from the laminate;
Depositing a graphene layer from which the transition metal layer has been removed on a substrate; And
Removing the support layer;
Wherein the graphene layer has a structure in which a graphene layer is laminated on a substrate.
The method of claim 1, wherein the gas clusters are injected from one or more nozzles.
A graphene which is surface-treated by the treatment method according to any one of claims 1 to 9 and has a surface roughness of 3 to 50 nm.

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