KR101560029B1 - Direct transfer methods of graphene - Google Patents

Abstract

The present invention relates to a method of transferring graphene onto a substrate, and more particularly, to a method of transferring graphene synthesized on a catalyst metal directly onto a substrate.
This method includes preparing graphene synthesized on the catalyst metal (step S10) as shown in FIG. 1; Spin coating the polymer on the substrate to which the graphen is to be transferred (step S20); Curing the polymer-coated substrate (S30); Attaching graphene formed on the catalyst metal to the polymer-coated surface of the substrate (S40); Etching the catalyst metal used for graphene formation (S50 step); And cleaning and drying the substrate to which graphen is attached (S60).

Description

Direct transfer methods of graphene [

The present invention relates to a method of transferring graphene onto a substrate, and more particularly, to a method of transferring graphene synthesized on a catalyst metal directly onto a substrate.

Graphene is the basic structure of all graphite materials, graphite, diamond, buckyball, fullerenes and carbon nanotubes. It transports electrons 100 times faster than silicon and 100 times larger than copper It is known that a lot of current can flow. Therefore, recently, researches for utilization as a next-generation transparent electrode material have been actively conducted. As a method of synthesizing graphene, a method of epitaxial growth on a substrate by a CVD (chemical vapor deposition) method [Science 306, 666 (2004)] [Surf. Sci. 264, 261 (1992)], a method of producing silicon carbide by pyrolysis [Science 312, 1191 (2006)], a method of oxidizing graphite, dispersing it in a solvent and reducing the dispersed graphene oxide [J Am . Chem. Soc. 128, 7720 (2006)]. Among them, a method of growing graphene by the CVD method is most widely used.

In order to utilize graphene grown on a catalytic metal (Cu, Ni, Co, Ir, Ru, etc.) by a CVD method as a transparent electrode material, a process of transferring onto a substrate is required.

A typical conventional transfer process proceeds to the same step as in Fig.

Preparing graphene synthesized on the catalytic metal; Attaching the PEN film using a tape; Adhering to a glass; Applying PMMA and spin coating; Curing the applied PMMA; Removing the attached film, glass and tape; Etching the catalytic metal; Washing with deionized water; Transferring graphene to a substrate; Drying; Removing the PMMA; And the grains are transferred to the substrate through a re-drying step.

Since the transfer step according to the related art is performed over a total of 12 steps, it takes a lot of time because of a lot of process steps, and the cost is also increased. In particular, the price of PMMA used for transcription is very expensive.

In addition, typical conventional transfer processes cause some defects in the transferring process. Typically, wrinkles generated in the transferring process and PMMA remaining without being completely removed are factors that degrade the characteristics of graphene .

In addition, a semiconductor wafer process is essentially used to form a flexible device using graphene. The problem of transferring to a flexible device after transferring to a wafer for a photolithography process have.

The present invention simplifies the existing transfer process, thereby improving the problems of the conventional transfer process and minimizing the process time and material consumption.

In the case of transferring graphene onto a substrate according to the method of the present invention, there is no PMMA remaining after the transferring process because there is no use of PMMA, wrinkles are not generated, the characteristics of the graphene are excellent and the process is simplified, (Substrate formed of organic polymer such as PI, PET, PEN, PES, FR4, BT, TPU, inorganic substrate such as Si, SiO ₂ , SiN _x , Quartz, Glass, Soda lime, Al ₂ O _3, and the like).

According to an embodiment of the present invention, there is provided a method of directly transferring graphene synthesized on a catalyst metal, comprising: preparing graphene synthesized on a catalyst metal; Spin coating the polymer on a substrate to be graphened; Curing the polymer-coated substrate; Adhering graphene formed on the catalyst metal to a polymer-coated surface of the substrate by inverting graphene formed on the catalyst metal; Etching the catalyst metal used to form the graphene; And cleaning and drying the graphene-attached substrate.

In this case, the polymer coated on the substrate is preferably a sticky material such as PDMS.

1 is a flowchart of a method of directly transferring graphene synthesized on a catalyst metal according to an embodiment of the present invention.
2 is a schematic diagram of a method of directly transferring graphene synthesized on a catalyst metal according to an embodiment of the present invention.
FIG. 3 shows a state in which the PDMS is coated on the substrate by sequentially applying PDMS and spin-coating the PDMS.
4 is a view showing the laminating step in order.
Figure 5 shows a view of the etching step.
Figure 6 shows a view of the step of cleaning with deionized water.
FIG. 7 shows a state in which graphene is finally transferred onto the substrate.
Various embodiments are now described with reference to the drawings, wherein like reference numerals are used throughout the drawings to refer to like elements. For purposes of explanation, various descriptions are set forth herein to provide an understanding of the present invention. It is evident, however, that such embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the embodiments.

The following description provides a simplified description of one or more embodiments in order to provide a basic understanding of embodiments of the invention. This section is not a comprehensive overview of all possible embodiments and is not intended to identify key elements or to cover the scope of all embodiments of all elements. Its sole purpose is to present the concept of one or more embodiments in a simplified form as a prelude to the more detailed description that is presented later.

1 is a flowchart of a method of directly transferring graphene synthesized on a catalyst metal according to an embodiment of the present invention.

This method includes preparing graphene synthesized on the catalyst metal (step S10) as shown in FIG. 1; Spin coating the polymer on the substrate to which the graphen is to be transferred (step S20); Curing the polymer-coated substrate (S30); Attaching graphene formed on the catalyst metal to the polymer-coated surface of the substrate (S40); Etching the catalyst metal used for graphene formation (S50 step); And cleaning and drying the substrate to which graphen is attached (S60).

2 is a schematic diagram of a method of directly transferring graphene synthesized on a catalyst metal according to an embodiment of the present invention.

Hereinafter, the method of the present invention will be described in detail for each step.

1. Catalyst On metal  Synthesized Graffin  Preparing step ( S10  step)

In this step, graphene is synthesized on the catalyst metal to prepare graphene synthesized on the catalyst metal.

The catalyst metal may be Cu, Ni, Fe, Co, and alloys thereof, and there is no particular limitation on such a catalyst metal. In the following examples, Cu was used as the catalyst metal.

2. Grapin  Spin coating the polymer on the substrate to be transferred ( S20  step)

This step is a step of precoating the polymer on the substrate to be transferred with graphene. For example, a liquid polymer material is coated on a substrate such as a Si wafer using a spin coating method.

The polymer used in this step is preferably tacky, flexible and stretched, and PDMS is available as such a polymer material.

In the present invention, since the polymer is first coated on the substrate, and organic materials such as PMMA used in the conventional graphene transfer method are not directly applied on the surface of the graphene, there is no problem of graphene surface contamination, It is advantageous to realize the original characteristics of the graphene because wrinkles inevitably generated in the process do not occur.

Fig. 3 shows a photograph of an actual experiment until PDMS is applied and spin coating is completed. I will explain this in detail below.

3. The polymer  Curing the coated substrate ( S30  step)

This step is a step of spin-coating the polymer on the substrate in step S20 and then curing the liquid polymer.

In this step, an oven or the like is used for curing and curing is performed under a constant temperature and time.

4. formed on the catalytic metal Graffin  inside out Grapin  The formed surface The polymer  Adhering to the coated surface ( S40  step)

This step is a step in which the graphene synthesized on the catalyst metal prepared in step S10 is turned on so as to be adhered to the surface on which the graphened surface is adhered to the surface of the polymer coated on the substrate in step S20, To attach the graphene-formed surface to the polymer-coated surface on the substrate.

5. Grapin  Etching the attached substrate with a catalytic metal S50  step)

In this step, etching is performed in an etchant that can etch the catalyst metal to remove the catalyst metal in a state where graphene is attached on the substrate in step S40.

When Cu is used as the catalyst metal, an aqueous solution of FeCl ₃ (NH ₄ ) ₂ S ₂ O ₈ or the like can be used as the etching solution.

6. Grapin  Cleaning and drying the attached substrate ( S60  step)

In this step, the substrate having the graphene is etched in step S50, and finally, the substrate is cleaned and dried.

Washed with deionized water, and finally dried using an oven or the like.

When all of the above steps are performed, graphene is directly transferred onto the substrate. If graphene is transferred according to the method of the present invention, it can be directly applied to a semiconductor wafer process for manufacturing a device, and then an additional transfer process to a flexible substrate It is not necessary.

Meanwhile, when the method of the present invention is followed, the thickness of the flexible and stretched substrate can be freely adjusted by controlling the number of revolutions of the spin coater after synthesis of graphene.

The applicant of the present invention has directly experimented with the method of the present invention according to the following steps, and will be described below.

First, graphene was synthesized on the catalytic metal Cu.

Then, liquid phase PDMS (Dow Corning, Inc) was spin-coated on the Si wafer substrate to be transferred with graphene. In this case, the PDMS was coated using a mixture of a hardener and a 10: 1 ratio, and spin coating was performed at 1200 rpm.

FIG. 3 shows a state in which the PDMS is coated on the substrate by sequentially applying PDMS and spin-coating the PDMS.

Then, in order to cure the PDMS, it was placed in an oven and cured, in which case the curing temperature was set at 100 ° C and the time was 30 minutes.

The graphene thus synthesized is turned upside down on the PDMS coated substrate, and the graphene is raised so as to adhere to the PDMS coated surface, followed by laminating with a protective film. The laminating temperature was 70 캜, and the speed was not particularly limited.

Fig. 4 is an actual view showing the steps of laminating in order.

Thereafter, the catalytic metal etching was performed, in which case the Cu surface was floated so as to be immersed in the etching solution (etchant), and this etching state is shown in FIG. FeCl ₃ aqueous solution (manufactured by Sigma-Aldrich) was used, and the etching time was about 3 to 4 hours.

Thereafter, it was washed with deionized water for about 2 to 3 times each for about 10 minutes, which can be confirmed in FIG. After cleaning, it was dried in an oven at 50 DEG C for 30 to 60 minutes.

The state in which graphene is finally transferred onto the substrate is shown in FIG.

The description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features presented herein.

Claims (4)

Preparing graphene synthesized on the catalytic metal;
Spin coating the adhesive polymer on the substrate onto which the graphene is to be transferred;
Curing the substrate coated with the tacky polymer;
Adhering graphene formed on the catalytic metal to a surface coated with an adhesive polymer of the substrate by inverting the graphene formed on the catalytic metal;
Etching said catalyst metal used for formation of said graphene;
And washing and drying the graphene-adhered substrate.
Direct transfer method of graphene.
delete The method according to claim 1,
Wherein the polymer is PDMS,
Direct transfer method of graphene.
delete

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