Dry graphene transfer method

Abstract

The technical idea of the present invention provides a dry graphene transfer method comprising the steps of: arranging graphene on a first surface of a first polymer layer and arranging a second polymer layer on a second surface of the first polymer layer opposite to the first surface; aligning the first polymer layer with an insulating layer arranged on a substrate; placing the graphene, which is thermally expanded, on the insulating layer by a heat supply to the first polymer layer; completely separating the second polymer layer from the first polymer layer after stopping the heat supply to the first polymer layer; and removing the first polymer layer from the insulating layer, wherein the graphene comprises: a body in which groove and ridge portions having a height difference are repeatedly arranged in a zigzag shape along the longitudinal direction; and a probe which is arranged on one surface of the groove portions and one surface of the ridge portions and can chemically bind to a target material.

Description

Dry graphene transfer method

[0001] The technical idea of ​​the present invention relates to a dry graphene transfer method.

[0002] The recent COVID-19 pandemic has dramatically increased the need for rapid and accurate sensors for detecting biological substances such as DNA and RNA. While various optical, mechanical, and electrical methods have been developed to detect biological substances, most sensors require extensive preprocessing to increase the concentration of the target substance in the solution. In particular, for patient samples such as cancer cells, viruses, and antibodies, the number of extractions from patients is limited, resulting in significantly smaller sample volumes. Furthermore, detection of the target substance requires lengthy and complex preprocessing. Among these, electrical sensors offer high sensitivity without the need for preprocessing to increase the concentration of the target substance in the solution, and thus, significant research is currently underway.

[0003] Graphene, a two-dimensional hexagonal carbon structure, has recently been actively researched worldwide as a new material that can replace semiconductors. Furthermore, graphene possesses electrically semi-metallic properties, yet because its internal charge acts as a zero-effective mass particle, it is known to possess extremely high electrical conductivity (an intrinsic electron mobility of 20,000 cm2 / Vs). In particular, since the discovery of field-effect characteristics when graphene, a two-dimensional hexagonal carbon atom structure formed by mechanically exfoliating graphite, was used in transistors, graphene has been attracting attention as a material that can replace conventional semiconductors such as silicon. Accordingly, extensive research is being conducted on technologies that enhance the selectivity and sensitivity of biosensors containing graphene while maintaining the inherently excellent electrical conductivity of graphene. Furthermore, techniques for rapidly modifying the graphene surface and stably immobilizing bioreceptors without additional chemical reaction steps are being developed.

[0004] Graphene transfer process technologies can be roughly categorized into two types, depending on how the transition metal film on which graphene is grown is peeled off. A representative technique uses a liquid metal etching solution to remove the underlying transition metal film, known as a wet transfer technique. Another technique, without the use of a liquid metal etching solution, mechanically and physically peels graphene from the transition metal film, known as a dry transfer technique (e.g., roll-to-roll, stamp).

[0005] However, current wet transfer and dry transfer technologies have a high probability of causing damage to the graphene, such as tearing or folding, during the process of transferring the graphene to the surface of the target substrate, which leads to a deterioration in the properties of the fabricated graphene device. In particular, in dry transfer technology, there is a high probability of physical damage to the graphene due to the application of a pressure of approximately 0.2 MPa to the graphene during the process of transferring the graphene to the polymer support and the process of transferring the graphene to the target substrate. In addition, in wet transfer technology, there is a high probability of tearing or folding of the graphene during the process of removing the graphene suspended in the etching solution or cleaning solution.

[0006] The technical idea of ​​the present invention aims to solve a problem by providing a method for transferring graphene onto a substrate without damage caused by physical impact.

[0007] In order to solve the above problem, the technical idea of ​​the present invention provides a dry graphene transfer method, comprising the steps of: arranging graphene on a first surface of a first polymer layer in a solid state, and arranging a second polymer layer on a second surface of the first polymer layer opposite to the first surface; aligning the first polymer layer on an insulating layer arranged on a substrate; supplying heat to the first polymer layer to settle the graphene arranged on the first surface of the thermally expanded first polymer layer on the insulating layer; completely separating the second polymer layer from the first polymer layer after stopping the heat supply to the first polymer layer; and removing the first polymer layer from the insulating layer, wherein the graphene comprises a body in which valleys and peaks having a height difference are repeatedly arranged in a zigzag shape along the longitudinal direction; and a probe arranged on one surface of the valleys and peaks and capable of chemically bonding with a target substance to be detected.

[0008] According to one embodiment, a dry graphene transfer method is provided, characterized in that the first polymer layer includes polymethylmethacrylate (PMMA) and the second polymer layer includes polydimethylsiloxane (PDMS).

[0009] According to one embodiment, a dry graphene transfer method is provided, characterized in that the height difference between the valley and the peak of the graphene is in the range of 0.2 nanometers to 20 nanometers.

[0010] According to one embodiment, a dry graphene transfer method is provided, characterized in that the grooves of the graphene are regularly arranged along the longitudinal direction according to a wavelength in the range of 1 nanometer to 10 nanometers.

[0011] According to one embodiment, a dry graphene transfer method is provided, characterized in that, in the step of settling the graphene on the substrate, the first polymer layer is liquefied at a temperature in the range of 200 degrees Celsius to 400 degrees Celsius or less.

[0012] According to one embodiment, a dry graphene transfer method is provided, characterized in that, after stopping the heat supply to the first polymer layer, in the step of completely separating the second polymer layer from the first polymer layer, the first polymer layer is solidified at a temperature in the range of 0 degrees Celsius to 160 degrees Celsius.

[0013] According to one embodiment, a dry graphene transfer method is provided, characterized in that, in the step of settling the graphene on the substrate, the thermally expanded first polymer layer surrounds both the upper surface and both side surfaces of the graphene.

[0014] According to one embodiment, a dry graphene transfer method is provided, characterized in that, in the step of settling the graphene on the insulating layer, a source electrode and a drain electrode are exposed on an upper surface of the insulating layer, and the graphene is in contact with the insulating layer, the source electrode, and the drain electrode.

[0015] According to one embodiment, a dry graphene transfer method is provided, characterized in that, in the step of completely separating the second polymer layer from the first polymer layer, the graphene remains in a state of being settled on the insulating layer.

[0016] According to one embodiment, the step of removing the first polymer layer on the insulating layer provides a dry graphene transfer method, characterized in that the first polymer layer is removed with a solution containing acetone.

[0017] A dry graphene transfer method according to the technical idea of ​​the present invention may include a step of phase-changing a polymer layer having graphene on one side from a solid to a liquid, and then from the liquid to a solid. During the phase-changing process of the polymer layer from a solid to a liquid, and then from the liquid to a solid, the graphene can be transferred onto a substrate without defects caused by physical impact.

[0018] The effects of the present invention are not limited to the effects described above, and effects not mentioned can be clearly understood by a person skilled in the art to which the present invention pertains from this specification and the attached drawings.

[0019] Figure 1 is a cross-sectional view illustrating the structure of a biosensor including graphene.

[0020] Figure 2 is a drawing for explaining the graphene illustrated in Figure 1.

[0021] Figure 3 is an enlarged view of the Q region of the graphene illustrated in Figure 2.

[0022] Figure 4 is a flowchart of a dry graphene transfer method according to one embodiment of the present invention.

[0023] FIGS. 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, and 9b are perspective views and cross-sectional views for explaining a dry graphene transfer method according to one embodiment of the present invention.

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below and may be embodied in various other forms. The following embodiments are provided not to fully complete the present invention, but rather to fully convey the scope of the present invention to those skilled in the art.

[0025] A biosensor comprising graphene having a three-dimensional wrinkled geometry according to embodiments of the present invention is used for gene expression profiling, genotyping, detection of mutations and polymorphisms such as SNPs (Single Nucleotide Polymorphisms), protein and peptide analysis, screening of potential drugs, development and manufacturing of new drugs, etc. by analyzing target substances contained in a sample.

[0026] Biosensors are equipped with appropriate probes depending on the target biological sample to be analyzed. Examples of probes that can be equipped in a biosensor include DNA probes, enzymes or antibodies / antigens, protein probes such as bacteriorhodopsin, microbial probes, and neuronal probes. Biosensors manufactured in the form of chips are also referred to as biochips. For example, depending on the type of probe equipped, the biochip may be referred to as a DNA chip, protein chip, cell chip, neuron chip, etc. Biosensors according to some embodiments of the present invention may include an oligomer probe as a probe. The oligomer probe implies that the number of monomers of the probe employed is at the oligomer level. Here, the term "oligomer" may be used to mean a polymer composed of two or more covalently bonded monomers and having a molecular weight of about 1000 or less. Specifically, it may include 200 to 500 monomers, and preferably 5 to 30 monomers. However, the meaning of the oligomer probe is not limited to the above number. The monomers constituting the oligomeric probe can be modified depending on the type of biological sample to be analyzed, and can be, for example, nucleosides, nucleotides, amino acids, peptides, etc. Nucleosides and nucleotides can include not only the known purine and pyrimidine bases, but also methylated purines, methylated pyrimidines, acylated purines, or acylated pyrimidines. Furthermore, nucleosides and nucleotides can include not only the conventional ribose and deoxyribose sugars, but also modified sugars in which one or more hydroxyl groups are substituted with halogen atoms or aliphatics, or functional groups such as ethers and amines are bonded. Amino acids can be L-, D-, and nonchiral amino acids found in nature, as well as modified amino acids, or amino acid analogs.A peptide refers to a compound formed by an amide bond between the carboxyl group of an amino acid and the amino group of another amino acid. Unless otherwise specified, the probes exemplified in the examples below are DNA probes, which are oligomeric probes covalently bonded with monomers of 5 to 30 nucleotides. However, the present invention is not limited thereto, and it is apparent that various probes described above can be applied.

[0027] Figure 1 is a cross-sectional view illustrating the structure of a biosensor including graphene.

[0028] Referring to FIG. 1, a biosensor (10) according to one embodiment may include a substrate (100), an insulating layer (110), a wiring structure (112), a gate electrode (114), a source electrode (116), a drain electrode (118), and graphene (210).

[0029] The substrate (100) may include a base structure made of a material such as silicon. In some embodiments, the base structure may include a complementary metal-oxide semiconductor (CMOS). The substrate (100) may include a semiconductor material, for example, a group IV semiconductor, a group III-V compound semiconductor, or a group II-VI oxide semiconductor. For example, the group IV semiconductor may include silicon (Si), germanium (Ge), or silicon-germanium. The substrate (100) may be provided as a bulk wafer or an epitaxial layer. In other embodiments, the substrate (100) may include glass or a polymer. In yet other embodiments, the substrate (100) may include a silicon-on-insulator (SOI) substrate or a germanium-on-insulator (GeOI) substrate.

[0030] According to one embodiment, an insulating layer (110) may be disposed on the substrate (100). The insulating layer (110) may be formed to have a constant thickness along the upper surface of the substrate (100). The insulating layer (110) may include, for example, an inorganic insulating material, an organic insulating material, or a combination thereof. The inorganic insulating material may include, for example, silicon oxide, silicon nitride, or a combination thereof. The organic insulating material may include, for example, polyimide, epoxy resin, or a combination thereof.

[0031] In one embodiment, the gate electrode (114) can be connected to a power source via a wiring structure (112) to supply a gate voltage to the graphene (210). By observing the electrical parameters of the biosensor according to the gate voltage, the presence of a target substance in the sample can be determined. At this time, a change in the electrical parameters can correspond to the presence of the target substance. For example, the electrical parameters can include capacitance, voltage, average current, etc. The gate electrode (114) can include a conductive metal material. In one embodiment, the gate electrode (114) can be composed of silver (Ag).

[0032] According to one embodiment, a source electrode (116) and a drain electrode (118) may be disposed within the insulating layer (110). The drain electrode (118) may be disposed horizontally spaced apart from the source electrode (116). The source electrode (116) and the drain electrode (118) may be formed of various materials and may include a metal or a metal alloy. For example, the source electrode (116) and the drain electrode (118) may include copper (Cu), ruthenium (Ru), aluminum (Al), cobalt (Co), molybdenum (Mo), titanium (Ti), tantalum (Ta), nickel (Ni), platinum (Pt), chromium (Cr), or an alloy thereof.

[0033] Graphene (210) may be arranged on the upper surface of the source electrode (116) and the drain electrode (118). The graphene (210) may have a three-dimensional wrinkled geometry. A specific description of the structure of the graphene (210) will be described later in the description of FIG. 2. The graphene (210) may be arranged on the upper surface of the insulating layer (110) and may extend horizontally along the upper surface of the insulating layer (110).

[0034] A sample (not shown) in contact with graphene (210) may include a target substance. The sample (not shown) may include a biological solution such as protein, DNA, RNA, fragments having an arbitrary base sequence, blood, or saliva. The sample (not shown) may be placed in a sample storage container (142). The sample storage container (142) may be a container for containing the sample (not shown) and may be made of a polymer or non-polymer material. In the reaction region (130) inside the sample storage container (142), the sample (not shown) including the target substance may react with a probe included in the graphene (210). In one embodiment, the sample storage container (142) may include silicone rubber.

[0035] In one embodiment, the biosensor (10) may further include a well structure (122) disposed on the outer surface of the insulating layer (110) on the upper surface of the insulating layer (110). The well structure (122) may include first and second boundary members (122a, 122b). The first and second boundary members (122a, 122b) may be disposed to be horizontally spaced apart from each other on the upper surface of the insulating layer (110). At least a portion of the upper surface of the graphene (210) may be exposed in a region surrounded by the well structure (122), and a reaction region (130) surrounded by the well structure (122) on the upper surface of the graphene (210) may be defined as a region in which a probe of the graphene (210) can react with a target material. In one embodiment, the well structure (122) may include an insulating material such as silicon oxide or silicon nitride.

[0036] Fig. 2 is a drawing for explaining the graphene illustrated in Fig. 1. Fig. 3 is an enlarged view of the Q region of the graphene illustrated in Fig. 2.

[0037] Referring to FIGS. 2 and 3, the graphene (210) may include a body (212) in which peaks (P) and valleys (V) having height differences are continuously arranged in a zigzag shape along the length direction, and a probe (214) that is arranged on one surface of the peaks (P) and valleys (V) and is capable of chemically bonding with a target material to be detected. The probe (214) may be arranged not only on the peaks (P) and valleys (V) of the body (212), but also between the peaks (P) and valleys (V).

[0038] In this specification, the longitudinal direction in which the peaks (P) and valleys (V) of the body (212) are repeatedly arranged in a zigzag shape may be defined as the first direction (X direction). The direction that is perpendicular to the first direction (X direction) and in which the peaks (P) or valleys (V) are elongated may be defined as the second direction (Y direction). In addition, the direction that is orthogonal to the first direction (X direction) and the second direction (Y direction) may be defined as the third direction (Z direction). The adjacent peaks (P) and the adjacent valleys (V) of the graphene (210) may be arranged to be spaced apart from each other in the first direction (X direction), and may extend in the second direction (Y direction), respectively. The valleys (V) may be arranged between the adjacent peaks (P) of the graphene (210), and the peaks (P) may be arranged between the adjacent valleys (V). However, the wrinkled shape of the body (212) of the graphene (210) is not limited to that shown in FIGS. 2 and 3, and can be wrinkled into various shapes.

[0039] In one embodiment, the point having the highest level of the body (212) of the graphene (210) that is repeatedly crumpled in a zigzag shape is defined as a peak (P), and the point having the lowest level is defined as a valley (V). In one embodiment, the adjacent peaks (P) and the adjacent valleys (V) of the graphene (210) may be spaced apart from each other by a constant amplitude (W). The amplitude (W) may be in the range of 1 nanometer to 10 nanometers. When the amplitude (W) of the peaks (P) is less than 1 nanometer, the graphene (210) may be crumpled too tightly, so that sufficient reaction space may not be formed for the probes (214) arranged on one surface of the graphene (210) to chemically bond with the target material (144). When the amplitude (W) of the peak is greater than 100 nanometers, it can be seen that the body (212) of the graphene (210) has a flat geometry rather than a three-dimensionally wrinkled geometry.

[0040] The number of bodies (212) included in the graphene (210) is not limited to that shown in FIG. 2. In another embodiment, the graphene (210) may include a first body and a second body disposed on the first body. From a planar perspective, carbon atoms constituting the first body and carbon atoms constituting the second body may be disposed to overlap each other. In another embodiment, carbon atoms constituting the first body and carbon atoms constituting the second body may be disposed to be misaligned. Since the graphene (210) illustrated in FIGS. 2 and 3 includes one body (212), the expression that the graphene (210) has a three-dimensional wrinkled geometry may have substantially the same meaning as the expression that the body (212) of the graphene (210) has a three-dimensional wrinkled geometry.

[0041] In one embodiment, graphene (210) may have a three-dimensional wrinkled geometry. In the case of flat graphene, a special treatment process, such as a foreign substance doping process, must be performed on the surface of the graphene to open a finite band gap, thereby enabling the graphene to function as a semiconductor. In contrast, graphene having a three-dimensional wrinkled geometry according to the present invention can open a band gap without a foreign substance doping process, thereby enabling the graphene to function as a semiconductor.

[0042]

[0043]

[0044] Table 1 shows the measured data for the bond lengths between carbon atoms in graphene with a flat geometry and those in graphene with a three-dimensional wrinkled geometry. Referring to Table 1, the bond lengths between specific carbon atoms in graphene with a three-dimensional wrinkled geometry are approximately 1 angstrom longer than the bond lengths between carbon atoms in graphene with a flat geometry. This imbalance in bond lengths between carbon atoms can lead to differences in the electrical behavior of graphene. When graphene with a flat geometry is crumpled into a three-dimensional shape, the symmetry and planarity of the graphene are destroyed, and the peaks and valleys with different heights are arranged continuously in a zigzag pattern along the length direction. This deformation brings about a quantum confinement effect due to the unique electronic structure of graphene, which can be one of the major contributing factors to the opening of the band gap of graphene. In general, in the case of graphene with a flat geometry, the band gap is not opened, so the difference in the amount of current between the state where current flows and the state where current does not flow is only about 20 to 30 times, which makes it difficult to function as a semiconductor device. However, in the graphene with a three-dimensional wrinkled geometry according to the present invention, the band gap can be opened due to the imbalance in the bond lengths between carbons. Therefore, since the difference in the amount of current between the state where current flows and the state where current does not flow in graphene can be at least 100,000 times or more, its usability as a semiconductor device can increase.

[0045]

[0046] Table 2 shows the equilibrium state energy of graphene with a flat geometry and the equilibrium state energy of graphene with a three-dimensional wrinkled geometry. Referring to Table 2, the equilibrium state energy of graphene with a three-dimensional wrinkled geometry may be much lower than the equilibrium state energy of graphene with a flat geometry. Therefore, the carbon atoms constituting the graphene with a three-dimensional wrinkled geometry according to the present invention may have higher stability than the carbon atoms constituting the graphene with a flat geometry. Since more probes (214) may be arranged in the region between the peaks (P) and valleys (V) of the graphene (210) compared to the peaks (P) and valleys (V), it may include many target materials. However, the present invention is not limited thereto, and more probes (214) may be arranged in the valleys (V) and peaks (P) than in the region between the peaks (P) and valleys (V).

[0047] As an example, the vertical distance (d1) from the line (A-A') crossing the center of the graphene (210) to the peak (P) may be 0.1 nanometers to 10 nanometers. The vertical distance (d2) from the line (A-A') crossing the center of the graphene (210) to the valley (V) may be 0.1 nanometers to 10 nanometers. Accordingly, the height difference between the peak (P) and the valley (V) may be 0.2 nanometers to 20 nanometers. When the vertical distance (d1) from the line (A-A') crossing the center of the graphene (210) to the peak (P) or the vertical distance (d2) from the line (A-A') crossing the center of the graphene (210) to the valley (V) is less than 0.1 nanometer, the length in the third direction (Z direction) is shortened with respect to the length in the first direction (X direction) of the graphene (210), so that the graphene (210) can be viewed as having a flat geometry rather than a three-dimensionally wrinkled geometry. When the vertical distance (d1) from the line (A-A') crossing the center of the graphene (210) to the peak (P) or the vertical distance (d2) from the line (A-A') crossing the center of the graphene (210) to the valley (V) is greater than 10 nanometers, the length of the graphene (210) in the third direction (Z direction) becomes longer than the length in the first direction (X direction), so that the graphene (210) may have an excessively densely wrinkled shape. In this case, a reaction space sufficient for the probes (214) arranged on one surface of the graphene (210) to chemically bond with the target material may not be formed.

[0048] According to one embodiment, the probe (214) disposed on one surface of the graphene (210) may be one of a polynucleotide, a peptide nucleic acid (PNA) probe, an aptamer, a protein, an antibody, or a capture agent. The probe (214) may be selected for binding to the target substance (144). For example, when the target substance (144) is DNA, the probe (214) may have a nucleotide sequence complementary to the nucleotide sequence of the DNA to be detected for binding to the DNA.

[0049] When the graphene (210) according to the present invention has a three-dimensionally wrinkled geometry, the Debye length is longer than when it has a flat geometry, allowing for the capture of more DNA molecules. Therefore, despite the Debye shielding effect, the sensitivity of the probe (214) to the target substance can be increased.

[0050] FIG. 4 is a flowchart of a dry graphene transfer method according to an embodiment of the present invention, and FIGS. 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, and 9b are perspective views and cross-sectional views for explaining a dry graphene transfer method according to an embodiment of the present invention.

[0051] Referring to FIGS. 5A and 5B along with FIG. 4, a dry graphene transfer method according to an embodiment of the present invention may include a step (see S110) of disposing graphene (210) on a first surface (200a) of a solid-state first polymer layer (200), and disposing a second polymer layer (220) on a second surface (200b) of the first polymer layer (200) opposite to the first surface (200a). At this time, the graphene (210) may be in contact with the first surface (200a) of the first polymer layer (200), and the second polymer layer (220) may be in contact with the second surface (200b) of the first polymer layer (200).

[0052] According to one embodiment, the first polymer layer (200) may include polymethylmethacrylate (PMMA). The first polymer layer (200) may have a first surface (200a) and a second surface (200b) opposite to the first surface (200a), wherein the first surface (200a) may face the upper surface of an insulating layer (110) disposed on a substrate (100). On the first surface (200a) of the first polymer layer (200), a substrate (100) and an insulating layer (110) laminated on the substrate (100) may be disposed. At this time, a portion of the source electrode (116) and the drain electrode (118) embedded in the insulating layer (110) may be exposed on the upper surface of the insulating layer (110).

[0053] According to one embodiment, the graphene (210) may be graphene (210) having a three-dimensional wrinkled geometry as described with reference to FIGS. 2 and 3. However, according to the embodiment, the graphene (210) is not limited to graphene having a three-dimensional wrinkled geometry. The second polymer layer (220) may include polydimethylsiloxane (PDMS). The polydimethylsiloxane included in the second polymer layer (220) is a silicone-based rubbery material and may have high thermal stability and high optical transparency. Therefore, even if the second polymer layer (220) is disposed on the second surface (200b) of the first polymer layer (200), the first polymer layer (200) may be confirmed with the naked eye due to the high optical transparency of the second polymer layer (220). The polymethylmethacrylic acid included in the first polymer layer (200) may also have high optical transparency. Therefore, even if graphene (210) is placed on the first surface (200a) of the first polymer layer (200), the graphene (210) can be confirmed with the naked eye due to the high optical transparency of the first polymer layer (200) and the second polymer layer (220).

[0054] Referring to FIGS. 6A and 6B along with FIG. 4, a dry graphene transfer method according to an embodiment of the present invention may include a step (see S120) of aligning a first polymer layer (200) to an insulating layer (110) disposed on a substrate (100). At this time, since the first polymer layer (200) and the second polymer layer (220) may have high optical transparency as mentioned above, the graphene (210) disposed on the first surface (200a) of the first polymer layer (200) can be aligned to more easily overlap the source electrode (116) and the drain electrode (118) exposed on the upper surface of the insulating layer (110).

[0055] Referring to FIGS. 7a and 7b together with FIG. 4, a dry graphene transfer method according to one embodiment of the present invention may include a step (see S130) of settling graphene (210) disposed on a first surface (200a) of a first polymer layer (200) that has been thermally expanded by supplying heat to the first polymer layer (200) on an insulating layer (110).

[0056] Heat can be supplied to the first polymer layer (200) in a solid state to liquefy the first polymer layer (200) in a first temperature range. According to one embodiment, the first temperature range may be in the range of 200 degrees Celsius to 400 degrees Celsius. If the first temperature range is 200 degrees Celsius or lower, sufficient heat may not be supplied to cause thermal expansion of the first polymer layer (200). In addition, if the first temperature range is 400 degrees Celsius or higher, excessive liquefaction of the first polymer layer (200) may cause the first polymer layer (200) to be completely separated from the second polymer layer (220), and the graphene (210) may be momentarily dropped onto the upper surface of the insulating layer (110). If the graphene (210) is momentarily dropped onto the upper surface of the insulating layer (110), a defect may occur in the graphene (210) due to physical impact.

[0057] Since the liquefied first polymer layer (200) increases in volume, the first surface (200a) of the liquefied first polymer layer (200) slowly stretches toward the upper surface of the insulating layer (110). The first surface (200a) of the liquefied first polymer layer (200) comes into contact with the upper surface of the insulating layer (110), and the graphene (210) disposed on the first surface (200a) of the liquefied first polymer layer (200) comes into contact with the upper surface of the insulating layer (110). In addition, the graphene (210) disposed on the first surface (200a) of the liquefied first polymer layer (200) also comes into contact with the upper surfaces of the source electrode (116) and the drain electrode (118) exposed on the upper surface of the insulating layer (110). In the step of settling the graphene (210) placed on the first surface (200a) of the liquefied first polymer layer (200) onto the insulating layer (110) on the substrate (100), the first polymer layer (200) surrounds both the upper surface and the side surface of the graphene (210).

[0058] According to one embodiment, a dry graphene transfer method can allow the graphene (210) disposed on the first surface (200a) of the first polymer layer (200) that has been extended by liquefaction to slowly settle onto the insulating layer (110), thereby allowing the graphene (210) to be transferred onto the insulating layer (110) without sustaining physical damage. In particular, when the graphene (210) has a three-dimensional wrinkled geometry, impact may be concentrated on the valley portion (V, see FIG. 3) of the body (212, see FIG. 3) during the process of settling the graphene (210) onto the insulating layer (110). Therefore, when the first polymer layer (200) is liquefied to slowly settle the graphene (210) onto the insulating layer (110), physical defects in the valley portion (V, see FIG. 3) of the body (212, see FIG. 3) can be prevented.

[0059] Referring to FIGS. 8A and 8B along with FIG. 4, a dry graphene transfer method according to an embodiment of the present invention may include a step (see S140) of completely separating the second polymer layer (220) from the first polymer layer (200) after stopping the heat supply to the first polymer layer (200). At this time, the heat supply to the liquefied first polymer layer (200) may be stopped to solidify the liquefied first polymer layer (200) in a second temperature range. According to an embodiment, the second temperature range may be a temperature range of 0 degrees Celsius or more and 160 degrees Celsius or less. If the second temperature range is 160 degrees Celsius or more, the first polymer layer (200) may not be sufficiently solidified. In addition, when the second temperature range is below 0 degrees Celsius, the adhesive force between the first polymer layer (200) and the graphene (210) becomes strong, so that it may be difficult to remove the first polymer layer (200) from the graphene (210) in a later step.

[0060] As the first polymer layer (200) solidifies, a gap may occur at the interface between the first polymer layer (200) and the second polymer layer (220). When solidification of the first polymer layer (200) is complete, the second polymer layer (220) can be completely separated and removed from the first polymer layer (200). In the process of completely separating the second polymer layer (220) from the first polymer layer (200), the graphene (210) can remain in a state of being settled on the upper surface of the insulating layer (110).

[0061] Hereinafter, referring to FIGS. 9A and 9B together with FIG. 4, the dry graphene transfer method according to one embodiment of the present invention may include a step (see S150) of removing the first polymer layer (200) from the insulating layer (110). At this time, the first polymer layer (200) may be dissolved and removed from the substrate (100), and a solution containing acetone may be used to dissolve the first polymer layer (200).

[0062] In one embodiment, after the first polymer layer (200) is immersed in a solution containing acetone for about 30 seconds, the solution containing acetone is removed and the first polymer layer (200) can be physically removed. Thereafter, if foreign substances decomposed from the first polymer layer (200) still remain on the insulating layer (110) or graphene (210), the insulating layer (110) and graphene (210) on which the foreign substances remain can be immersed in deionized water for about 12 hours to remove the foreign substances.

[0063] As described above, exemplary embodiments have been disclosed in the drawings and specifications. While specific terminology has been used to describe embodiments herein, it is intended solely to illustrate the technical concept of the present disclosure and is not intended to limit the scope of the present disclosure as defined in the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible. Therefore, the true technical protection scope of the present disclosure should be determined by the technical concept of the appended claims.

Claims

1. A step of placing graphene on a first surface of a first polymer layer in a solid state and placing a second polymer layer on a second surface of the first polymer layer opposite to the first surface; A step of aligning the first polymer layer to an insulating layer disposed on a substrate; A step of settling the graphene disposed on the first surface of the thermally expanded first polymer layer on the insulating layer by supplying heat to the first polymer layer; After stopping the heat supply to the first polymer layer, a step of completely separating the second polymer layer from the first polymer layer; and A step of removing the first polymer layer from the insulating layer, The above graphene is, A body in which the ribs and ridges with different heights are repeatedly arranged in a zigzag shape along the length; and A dry graphene transfer method characterized by including a probe that is arranged on one surface of the above-mentioned bone portion and the floor portion and is capable of chemically bonding with a target material to be detected.

2. In paragraph 1, The first polymer layer comprises polymethylmethacrylate (PMMA), A dry graphene transfer method, characterized in that the second polymer layer comprises polydimethylsiloxane (PDMS).

3. In paragraph 1, A dry graphene transfer method, characterized in that the height difference between the valley and the peak of the graphene is in the range of 0.2 nanometers to 20 nanometers.

4. In paragraph 1, A dry graphene transfer method, characterized in that the grooves of the graphene are regularly arranged along the longitudinal direction according to a wavelength ranging from 1 nanometer to 10 nanometers.

5. In paragraph 1, In the step of settling the graphene on the substrate, A dry graphene transfer method, characterized in that the first polymer layer is liquefied at a temperature in the range of 200 degrees Celsius to 400 degrees Celsius.

6. In paragraph 5, After stopping the heat supply to the first polymer layer, in the step of completely separating the second polymer layer from the first polymer layer, A dry graphene transfer method, characterized in that the first polymer layer is solidified at a temperature in the range of 0 degrees Celsius to 160 degrees Celsius.

7. In paragraph 1, In the step of settling the graphene on the substrate, A dry graphene transfer method, characterized in that the thermally expanded first polymer layer surrounds both the upper surface and the side surface of the graphene.

8. In paragraph 1, In the step of settling the graphene on the insulating layer, The source electrode and drain electrode are exposed on the upper surface of the above insulating layer, A dry graphene transfer method, characterized in that the graphene is in contact with the insulating layer, the source electrode, and the drain electrode.

9. In paragraph 1, In the step of completely separating the second polymer layer from the first polymer layer, A dry graphene transfer method characterized in that the graphene remains in a state of being settled on the insulating layer.

10. In paragraph 1, The step of removing the first polymer layer from the insulating layer comprises: A dry graphene transfer method characterized in that the first polymer layer is removed with a solution containing acetone.

Images