Vertically aligned carbon nanotube transfer process using thin ice layer

Abstract

Disclosed are a VACNT transfer method, a VACNT transfer system for the entire substrate, and a VACNT device. The VACNT transfer method comprises: a first step of cooling a substrate to be transferred, to condense and cool water vapor on the surface of the substrate to be transferred, thereby forming an ice layer; and a second step of liquefying the ice layer and then cooling same again, while VACNTs are disposed on the ice layer.

Description

Vertically aligned carbon nanotube transfer process using a thin ice layer

[0001] The present invention relates to a VACNT transfer method, a substrate-wide VACNT transfer system, and a VACNT device.

[0002] This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science and ICT (MSIT) in 2023 (No. 2021R1A2B5B03002850).

[0003] This research was supported by the National Research Foundation of Korea (NRF) grant by the Korea government (MSIT) (No. 2021R1A2B5B03002850).

[0004]

[0005] Vertically aligned carbon nanotubes (VACNTs) have potential for diverse applications due to their superior electrical and mechanical properties and their structural characteristics, which are aligned vertically on the substrate. However, because the synthesis of VACNTs requires high temperatures (over 600°C), their use in modern manufacturing technologies such as CMOS processes and flexible device-based processes is limited. To address this issue, various VACNT transfer methods have been developed. For example, transfer processes utilizing metal solder layers are performed under high temperatures and pressures, which can damage the substrate and leave solder residues. Furthermore, laser-assisted bonding of VACNTs to polymer substrates has limited applicability and substrate deformation due to the process temperature. Another approach, chemical etching, can damage the VACNT material itself and is incompatible with microfabrication. However, the VACNT transfer method utilizing a thin ice layer according to the present invention can overcome these limitations. This method enables transfer at room temperature and pressure without damaging or deforming the substrate while maintaining the material's own properties, which can significantly increase the usability of VACNT in various application fields.

[0006] Vertically Aligned Carbon Nanotubes (VACNTs), which possess high surface area, excellent thermal and electrical conductivity, high strength, and flexibility, are a new material being studied in many fields, including energy storage devices such as batteries and supercapacitors, MEM switches, transistors, and flexible substrate-based biosensors and actuators. Currently, the technology for integrating VACNTs into existing device manufacturing processes is limited. However, if technology for integrating VACNTs into existing device manufacturing processes at room temperature and pressure is developed, it is expected that device performance enhancements can be achieved in the various application fields mentioned above.

[0007]

[0008] The challenge of the present invention is to overcome several key limitations of existing VACNT transfer methods. One of these limitations is the difficulty in preventing substrate damage due to the high temperature and high pressure required for VACNT synthesis. The high temperature and high pressure processes, typically above 600°C, increase the risk of substrate damage, which is particularly problematic when transferring VACNTs to heat-sensitive or flexible substrates. This has limited the applicability of VACNTs in various fields.

[0009]

[0010] To address these issues, the present invention provides a novel VACNT transfer method utilizing a thin ice layer. This method can form an ice layer even at room temperature, enabling effective transfer of VACNTs without damaging the substrate. Furthermore, the thin ice layer plays a crucial role in maintaining the vertical alignment of VACNTs, thereby optimizing the performance of VACNT devices. By simplifying the VACNT transfer process and enabling its application to a variety of substrates, the present invention can significantly expand the application range of VACNT-based technologies.

[0011] In one aspect, the present invention provides a VACNT transfer method, comprising: a first step of cooling a transfer target substrate to condense and cool water vapor on the surface of the transfer target substrate to form an ice layer; and a second step of liquefying the ice layer while VACNT is placed on the ice layer and then cooling it again.

[0012] In one embodiment, the ice layer can be formed to a thickness of 10 to 20 μm.

[0013] In one embodiment, in the first step, the ice layer can be formed by cooling for 2 to 4 minutes under conditions of a temperature of 15 to 25°C, a relative humidity of 40 to 60%, and a cooling temperature of -30 to -5°C.

[0014] In one embodiment, the cooling can be performed using a thermoelectric element formed on the lower surface of the transfer target substrate.

[0015] In one embodiment, the transfer target substrate may include one or more of a wafer, a semiconductor, an insulator, a conductor, and a polymer substrate.

[0016] In one embodiment, the transfer target substrate may comprise one or more materials selected from the group consisting of silicon oxide, silicon, gold, and PET.

[0017] In one embodiment, the cooling of the transfer target substrate may cool only a portion of the transfer target substrate corresponding to the desired transfer pattern.

[0018] In another aspect, the present invention provides a full-substrate VACNT transfer system, comprising: a VACNT synthesis unit capable of synthesizing VACNT; and a cooling device capable of placing a transfer target substrate thereon and cooling the transfer target substrate.

[0019] In one embodiment, the system may further include a thickness measuring unit capable of measuring the thickness of the ice layer when the cooling device cools the transfer target substrate and an ice layer is formed on the transfer target substrate.

[0020] In one embodiment, the thickness measuring unit can turn off the cooling device when the ice layer reaches a predetermined thickness.

[0021] In one embodiment, the predetermined thickness may be 10 to 20 μm.

[0022] In one embodiment, the system may further include a cooling time control unit that controls the cooling temperature and cooling time of the cooling device.

[0023] In one embodiment, the system may further include an environmental information acquisition unit that acquires environmental information including the ambient temperature and ambient humidity of a location where the system is located.

[0024] In an embodiment, the system may further include a cooling control unit that controls the cooling temperature and cooling time of the cooling device based on the ambient temperature and ambient humidity obtained by the environmental information obtaining unit, so that the ice layer reaches a predetermined thickness.

[0025] In one embodiment, the cooling control unit can control the thickness of the ice layer to be 10 to 20 μm.

[0026] In another aspect, the present invention provides a VACNT device comprising a substrate; and a VACNT formed on the substrate; wherein the VACNT is transferred onto the substrate by the VACNT transfer method.

[0027] In one embodiment, the substrate may be a substrate whose structure is destroyed at a temperature of 600° C. or higher.

[0028]

[0029] The advantage of the present invention is that it prevents damage to the substrate that can occur in existing methods because it does not require high-temperature or high-pressure processes. Since the present invention utilizes a thin ice layer, it can effectively transfer VACNTs even at room temperature, thereby reducing the risks associated with high-temperature or high-pressure processes while enabling stable transfer. Furthermore, the present invention provides the ability to transfer VACNTs to heat-sensitive or flexible substrates. This overcomes the limitations of existing high-temperature or high-pressure processes and can significantly expand the range of applications for VACNTs in various fields.

[0030]

[0031] Figure 1 illustrates a VACNT transfer process method utilizing a thin ice layer of the present invention.

[0032] Figure 2 shows optical photographs and scanning electron microscopy (SEM) photographs of the VACNT transcription results through the above process.

[0033] Figure 3 illustrates the principle by which VACNT can maintain a vertically aligned structure after transcription in the present invention.

[0034] Figure 4 illustrates a VACNT transfer process method that omits the process of melting an ice layer in the transfer process of the present invention.

[0035] Figure 5 is a substrate image of the VACNT transcription result through the above process.

[0036] Figure 6 illustrates a VACNT transfer process method that omits the process of recooling melted water in the transfer process of the present invention.

[0037] Figure 7 is a substrate image of the VACNT transcription result through the above process.

[0038] Figure 8 illustrates a VACNT transfer process method in which a recooled ice layer is removed through sublimation in the transfer process of the present invention.

[0039] Figure 9 shows a photograph after the transfer process of VACNT through the above process.

[0040]

[0041] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The present invention may be modified in various ways and may take various forms. Therefore, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, but should be understood to include all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention. In describing each drawing, similar reference numerals are used to indicate similar components. In the attached drawings, the dimensions of structures are shown larger than actual size to ensure clarity of the present invention.

[0042] The terminology used in this application is only used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, or combinations thereof. In the context of this specification, the term "about" or the like can mean about ± 1%, about ± 2%, about ± 3%, about ± 4%, about ± 5%, about ± 6%, about ± 7%, about ± 8%, about ± 9%, or about ± 10% of a numerical value described in the specification.

[0043] Additionally, the description of one aspect of the present invention may be applied identically or similarly to the same or similar configurations or terms in the description of other aspects.

[0044] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0045]

[0046] A VACNT transfer method according to an embodiment of the present invention may include a first step of cooling a substrate to be transferred, thereby condensing and cooling water vapor on the surface of the substrate to form an ice layer; and a second step of liquefying the ice layer while VACNTs are placed on the ice layer and then cooling it again. During this process, the VACNTs are transferred to the substrate through contact with the ice layer, and as the ice layer is formed again, the adhesive force between the VACNTs and the substrate is strengthened. Through this, the VACNTs are firmly attached to the substrate, and the vertical alignment structure of the VACNTs can be maintained during the transfer process.

[0047] The role of the first step is to lower the surface temperature of the substrate to be transferred, causing atmospheric water vapor to condense and form an ice layer. This ice layer plays a crucial role in the VACNT transfer process and can function as a temporary adhesive layer for transferring the VACNT to the substrate. The formation of the ice layer protects the vertical alignment structure of the VACNT and enhances the adhesive strength in subsequent steps.

[0048] The first stage is particularly notable for condensing and cooling atmospheric water vapor without actively supplying a cooling fluid. This simplifies the transfer process, forms a uniform and appropriately thick ice layer, and allows for the formation of the ice layer without additional chemicals or complex processes. The cooling of the substrate is designed to naturally condense water vapor, ensuring the uniform and efficient formation of the ice layer on the substrate surface. A description of the appropriately thick ice layer is provided below.

[0049] The role of the second step is to transfer the VACNTs placed on the ice layer to the target substrate. During this step, the ice layer is liquefied and cooled again, which strengthens the adhesion between the VACNTs and the substrate. This step ensures that the VACNTs are firmly attached to the substrate while maintaining their vertical alignment.

[0050] In one embodiment, the method can remove the substrate before transfer of the VACNT after the cooling in the second step. In one embodiment, the method can remove the ice after removing the substrate before transfer of the VACNT. For example, the ice can be removed by natural liquefaction followed by evaporation, active liquefaction followed by evaporation, and / or physical removal after liquefaction. The ice layer naturally evaporates after the surface cooler is stopped, and during this process, the VACNT can be cleanly transferred to the substrate without residue. This method does not require high temperature or high pressure processes compared to existing VACNT transfer methods, thereby preventing damage to the substrate and enabling cleaner and more efficient transfer. In addition, this method can be applied to various types of substrates, and has the advantage of being able to transfer VACNT to heat-sensitive materials or flexible substrates in particular.

[0051] In one embodiment, the ice layer may be formed to a thickness of 10 to 20 μm. If the thickness of the ice layer is too thin, a sufficient thickness for VACNT transfer is not achieved, and if the thickness of the ice layer is too thick, collapse of the VACNT due to capillary action may occur during transfer. This optimal thickness is important for stable transfer of the VACNT and maintenance of the vertically aligned structure, and by controlling the thickness of the ice layer, the capillary action is minimized and the structural integrity of the VACNT is maintained during the transfer process. Therefore, the present invention can contribute to increasing the efficiency and success rate of the VACNT transfer process by appropriately controlling the thickness of the ice layer.

[0052] In one embodiment, the ice layer in the first step can be formed by cooling for 2 to 4 minutes under conditions of a temperature of 15 to 25°C, a relative humidity of 40 to 60%, and a cooling temperature of -30 to -5°C. These conditions provide an optimal environment for the formation of the ice layer. In this environment, the ice layer is formed uniformly and with an appropriate thickness on the surface of the substrate, which can ensure efficient transfer of the VACNT.

[0053] In one embodiment, the cooling can be performed using a thermoelectric element formed on the lower surface of the transfer target substrate. In one embodiment, the cooling of the transfer target substrate can cool only a portion of the transfer target substrate corresponding to the desired transfer pattern. This contributes to effectively lowering the surface temperature of the substrate through highly precise control. The use of a thermoelectric element enables uniform and precise cooling of the substrate, which can promote the uniform formation of an ice layer during the transfer process. Furthermore, this method enables selective cooling of only a specific portion of the substrate, thereby enabling the transfer of VACNT to a specific pattern or area.

[0054] In one embodiment, the transfer target substrate may include one or more of a wafer, a semiconductor, an insulator, a conductor, and a polymer substrate. In one embodiment, the transfer target substrate may include one or more materials selected from the group consisting of silicon oxide, silicon, gold, and PET. In the prior art, VACNTs are synthesized using a CVD process or the like, so a heat-resistant substrate must be used. However, the present invention allows transfer to a heat-sensitive substrate, eliminating the limitation on the transfer target substrate. This diversity broadens the scope of application of VACNT transfer technology and increases its usability in various industrial fields. The present invention provides the flexibility to efficiently transfer VACNTs to various types of substrates that were previously difficult to use, thereby enabling innovative material applications in fields such as electronic devices, sensors, and energy storage devices.

[0055] Meanwhile, a full-substrate VACNT transfer system according to an embodiment of the present invention may include a VACNT synthesis unit capable of synthesizing VACNTs; and a cooling device capable of placing a transfer target substrate thereon and cooling the transfer target substrate. The operation of the system is the same as or similar to the method described above. The sequence of synthesizing and transferring VACNTs through the system is as follows: (1) First, VACNTs are synthesized in the VACNT synthesis unit. This process can synthesize VACNTs on an existing growth substrate using a method such as chemical vapor deposition (CVD). (2) Next, the transfer target substrate is placed in the cooling device. In this step, the transfer target substrate is cooled according to the conditions of the first step, so that an ice layer is formed on the surface. The formation of the ice layer is controlled by considering air temperature, relative humidity, cooling temperature, and cooling time. (3) Thereafter, the synthesized VACNTs are placed on the ice layer. This forms a temporary adhesive layer between the transfer target substrate and the VACNTs, and helps maintain the vertical alignment structure of the VACNTs. (4) Subsequently, in the second step, the ice layer is liquefied and cooled again, strengthening the adhesion between the VACNT and the substrate. This process ensures that the VACNT is firmly attached to the substrate and maintains its vertical alignment structure. (5) Finally, the substrate is removed before the VACNT is transferred, and the ice layer is naturally evaporated or physically removed. This results in the clean transfer of the VACNT to the substrate.

[0056] In one embodiment, the system may further include a thickness measurement unit capable of measuring the thickness of the ice layer when the cooling device cools the transfer target substrate, thereby forming an ice layer on the transfer target substrate. In one embodiment, the thickness measurement unit may turn off the cooling device when the ice layer reaches a predetermined thickness. In one embodiment, the predetermined thickness may be 10 to 20 μm. This thickness measurement unit provides an important function that greatly improves the precision of the transfer process. Since an ice layer that is too thin or too thick may negatively affect transfer efficiency and the structural integrity of the VACNT, this thickness measurement unit can help maintain an optimal thickness of the ice layer. The thickness measurement unit ensures that the thickness of the ice layer is within an appropriate range, thereby improving the accuracy and consistency of the transfer process and ensuring the vertical alignment and structural stability of the VACNT.

[0057] In one embodiment, the system may further include a cooling time control unit that controls the cooling temperature and cooling time of the cooling device. In one embodiment, the system may further include an environmental information acquisition unit that obtains environmental information including the ambient temperature and ambient humidity of a location where the system is located. In one embodiment, the system may further include a cooling control unit that controls the cooling temperature and cooling time of the cooling device based on the ambient temperature and ambient humidity obtained by the environmental information acquisition unit, so that the ice layer reaches a predetermined thickness. In one embodiment, the cooling control unit may control the thickness of the ice layer to be 10 to 20 μm.

[0058] The role of the environmental information acquisition unit is to continuously monitor and collect critical environmental conditions, such as temperature and humidity, in the environment where the system is located during the transcription process. This collected information is then provided to the cooling control unit, allowing adjustments to maintain optimal cooling conditions throughout the transcription process.

[0059] Meanwhile, a VACNT device according to an embodiment of the present invention includes a substrate; and a VACNT formed on the substrate; and the VACNT can be transferred onto the substrate by the VACNT transfer method. In one embodiment, the substrate may be a substrate whose structure is destroyed at a temperature of 600° C. or higher. In general, since a VACNT device is synthesized through a CVD process or the like, synthesis on a substrate that can withstand high temperatures has been possible, but by using the transfer method of the present invention, it has become possible to stably transfer VACNT to various types of substrates that are sensitive to heat. This is an innovative improvement on the limitations of existing VACNT synthesis methods, and solves the problem of substrate damage that may occur during the high-temperature synthesis process.

[0060] In one embodiment, the substrate may be a substrate whose structure is destroyed at a temperature of 600°C or higher. In one embodiment, the substrate may be a substrate whose structure is destroyed at a temperature of 700°C or higher. In one embodiment, the substrate may be a substrate whose structure is destroyed at a temperature of 800°C or higher. In one embodiment, the substrate may be a substrate whose structure is destroyed at a temperature of 900°C or higher. In one embodiment, the substrate may be a substrate whose structure is destroyed at a temperature of 1000°C or higher.

[0061] Hereinafter, embodiments of the present invention will be described. However, the embodiments described below are merely some embodiments of the present invention, and the scope of the present invention is not limited to the embodiments described below.

[0062] The present invention includes a method and results of a vertically aligned carbon nanotube (VACNT) transfer process utilizing a thin ice layer.

[0063] Figure 1 illustrates a VACNT transfer process utilizing a thin ice layer of the present invention. This transfer process utilizes a thin ice layer as a bonding layer for material transfer. First, a substrate to which the material is to be transferred is attached to a surface cooler capable of forming a thin ice layer. The surface cooler is then operated to cool the substrate surface to a sub-zero temperature, and atmospheric water vapor condenses on the surface to form an ice layer. VACNTs synthesized on a separate substrate via chemical vapor deposition (CVD) are then brought into contact with the ice layer, and the surface cooler is then turned off to melt the ice layer. During this process, water fills the space between the VACNT strands and the substrate after contact, and the surface cooler is then operated to cool the water. With the re-formed ice layer strengthening the adhesion between the VACNT and the substrate, the growth substrate over the VACNT is lifted and removed. The substrate attached to the surface cooler contains VACNTs and the ice layer, which evaporates after the surface cooler is turned off, resulting in the VACNTs being transferred to the substrate without residue.

[0064] Fig. 2 shows optical photographs and scanning electron microscopy (SEM) photographs of the VACNT transfer results through the above process. Fig. 2(a) shows an optical photograph of VACNTs transferred to various substrates, Fig. 2(b) shows an SEM image of VACNTs transferred to a SiO2 substrate, and Fig. 2(c) shows an SEM image of VACNTs with micro-patterns after transfer. VACNTs synthesized through a high-temperature process of 600°C or higher on a silicon substrate can be transferred to other substrates through this transfer process. It was confirmed that VACNTs synthesized over a large area (1 X 1 cm2) on the substrate maintained a vertically aligned structure while being transferred. In addition, this process can be universally applied to various substrates on which an ice layer can be formed, such as semiconductors, insulators, conductors, and polymer substrates, including wafers (Si, SiO2). Additionally, the transfer results of VACNTs with various sizes and shapes that can be formed through microprocesses confirmed their potential for use in existing application device manufacturing processes.

[0065] FIG. 3 illustrates the principle by which VACNTs can maintain a vertically aligned structure after transfer in the present invention. FIG. 3(a) is a graph of ice thickness according to the surface cooler operation time, FIG. 3(b) is a schematic diagram showing the deformation of VACNT strand structures according to the increase in the amount of water, FIG. 3(c) is a SEM image of the VACNT transfer results according to the change in ice formation time, and FIG. 3(d) is a schematic diagram of an ice layer formed by a water spray method and an SEM image of the VACNT transfer results using the same. VACNTs, which have a structure in which individual carbon nanotube strands are densely packed vertically, typically experience a collapse of the vertical structure due to the capillary force acting on the carbon nanotubes when the liquid evaporates after contact with the liquid. In this process, the amount of ice used for transfer is minimized to prevent the collapse of the vertical structure of the material caused by utilizing the ice layer as a bonding layer in the transfer process. FIG. 3(a) shows the results showing ice thickness according to the surface cooler operation time. Fig. 3(b) is a schematic diagram showing how the VACNT strand structure is deformed as the amount of water used in the process increases. As the ice layer becomes thicker, the area where the capillary force acts between the carbon nanotube strands increases, and if a force exceeding the support force between the VACNT strands is applied, the vertical structure of the VACNT is deformed. Therefore, in this process, we developed a process method in which the vertical structure of the VACNT is maintained by forming an ice layer for approximately 3 minutes in a specific environment (20℃, RH 50%), and confirmed that the structure of the VACNT collapsed when ice was formed for a longer time (10 minutes, 20 minutes) than 3 minutes, as shown in the SEM image in Fig. 3(c). In addition, Fig. 3(d) shows that when the ice layer was formed by spraying water and then cooling, which is different from the present process method, an excessive amount of ice was formed in a specific area, causing the vertical structure to collapse during the transfer of the VACNT.

[0066] It was confirmed through comparative experiments that when each process step is omitted in the VACNT transfer process utilizing the thin ice layer of the present invention, the material cannot be transferred to the acceptor substrate.

[0067] First, Fig. 4 illustrates a VACNT transfer process method that omits the process of melting the ice layer by stopping the surface cooler operation after the VACNT and the ice layer come into contact in the transfer process of the present invention, and Fig. 5 is an image of the experimental results when the melting process is omitted. Through Fig. 5, it can be confirmed that the VACNT synthesized on the donor substrate is not transferred to the acceptor substrate. This is because the ice layer melting process is omitted, the contact area between the VACNT strands and the ice does not increase, and thus the adhesion between the material and the ice is proven through the transfer results.

[0068] FIG. 6 illustrates a transfer process method that omits the recooling process after melting the ice layer in the VACNT transfer process of the present invention, and FIG. 7 is an image of the experimental results when the recooling process is omitted. It can be confirmed through FIG. 7 that the VACNT is not transferred to the substrate when the recooling process of the water is omitted. This is because when the ice layer is melted, the VACNT on the ice layer moves downward due to the gravity of the substrate and comes into contact with the acceptor substrate, and the melted ice exists as water and is located between the VACNT and the substrate. However, when the water is not recooled and remains in a liquid state, the adhesive force between the water and the VACNT is less than the adhesive force between the VACNT and the donor substrate, so the VACNT is not transferred.

[0069] Figure 8 illustrates a process method for removing the ice layer through sublimation, which is the final step in the VACNT transfer using a thin ice layer of the present invention. When the ice layer of the present invention is removed from the acceptor substrate through evaporation after melting, if the ice layer is thick, the VACNTs may clump together with the CNT strands during the water evaporation process, which may cause vertical structural deformation of the material. Therefore, a removal process through sublimation of the ice layer can be introduced to solve this problem. In this process, after transferring the VACNTs to the acceptor substrate, the vacuum level in a vacuum chamber is lowered to a pressure (4.6 torr) below the triple point (critical point) of water, and then the temperature of a surface cooler is increased to cause the ice layer to sublimate (transition from solid to gas). At this time, the ice layer does not pass through a liquid phase, thereby eliminating the capillary force acting on the VACNTs when the liquid changes to gas, thereby preventing the CNT strands from clumping together. Figure 9 shows the experimental results of transferring VACNTs using both the sublimation and evaporation removal processes. When the ice layer remaining on the substrate after VACNT transfer was removed by evaporation under normal pressure using the conventional process, it was confirmed that the vertical structure of the VACNT collapsed during the water evaporation process. Conversely, when the ice layer was removed by sublimation under low pressure, it was confirmed that the vertical structure of the VACNT was maintained while being transferred to the acceptor substrate by preventing the aggregation of the VACNT strands. The results of this experiment demonstrated that the vertical structure of the VACNT can be maintained regardless of the thickness of the ice when the residual ice layer is removed by sublimation. In other words, the sublimation process can be applied when the ice layer is thick.

[0070] The advantages of the VACNT transfer process utilizing a thin ice layer proposed in the present invention, which are different from existing studies and inventions, are as follows: (1) Transfer to another substrate is possible without damage to the VACNT material itself or deformation of its vertical structure. (2) Transfer is possible to all flat substrates, and is compatible with the micro process used in existing device manufacturing technology, allowing for universal use. (3) Since the process is performed in a room temperature / normal pressure environment, separate high temperature / high pressure equipment is unnecessary, and the equipment can be simplified. (4) Since the ice layer is utilized during transfer and then evaporates, no residue other than VACNT remains on the substrate.

[0071] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

[0072]

[0073] The mode for carrying out the invention has been described together with the best mode for carrying out the invention above.

[0074]

[0075] The present invention does not require high-temperature or high-pressure processes, thereby preventing substrate damage that can occur with existing methods. Utilizing a thin ice layer, the present invention can effectively transfer VACNTs even at room temperature, thereby reducing the risks associated with high-temperature or high-pressure processes while ensuring stable transfer. Furthermore, the present invention provides the ability to transfer VACNTs to heat-sensitive or flexible substrates. This overcomes the limitations of existing high-temperature or high-pressure processes and significantly expands the range of applications for VACNTs in various fields, making it highly industrially feasible.

Claims

1. A first step of cooling the substrate to be transferred, condensing and cooling water vapor on the surface of the substrate to be transferred, thereby forming an ice layer; and A second step of liquefying the ice layer and then cooling it again while VACNT is placed on the ice layer; VACNT transcription method.

2. In paragraph 1, The above ice layer is formed with a thickness of 10 to 20 μm. VACNT transcription method.

3. In paragraph 1, In the first step, the ice layer is formed by cooling for 2 to 4 minutes under conditions of a temperature of 15 to 25°C, a relative humidity of 40 to 60%, and a cooling temperature of -30 to -5°C. VACNT transcription method.

4. In paragraph 1, The above cooling is performed using a thermoelectric element formed on the lower surface of the substrate to be transferred. VACNT transcription method.

5. In paragraph 1, The above transfer target substrate includes at least one of a wafer, a semiconductor, an insulator, a conductor, and a polymer substrate. VACNT transcription method.

6. In paragraph 1, The above-mentioned transfer target substrate comprises one or more materials selected from the group consisting of silicon oxide, silicon, gold and PET. VACNT transcription method.

7. In paragraph 1, The cooling of the above transfer target substrate cools only a portion of the transfer target substrate corresponding to the desired transfer pattern. VACNT transcription method.

8. VACNT synthesis unit capable of synthesizing VACNT; and A substrate to be transferred can be placed on the upper side, and a cooling device capable of cooling the substrate to be transferred; Full board VACNT transfer system.

9. In paragraph 8, The system further includes a thickness measuring unit capable of measuring the thickness of the ice layer when the cooling device cools the transfer target substrate and an ice layer is formed on the transfer target substrate. Full board VACNT transfer system.

10. In paragraph 9, The above thickness measuring unit turns off the cooling device when the ice layer reaches a predetermined thickness, The above predetermined thickness is 10 to 20 μm, Full board VACNT transfer system.

11. In paragraph 8, The above system further includes a cooling time control unit that controls the cooling temperature and cooling time of the cooling device. Full board VACNT transfer system.

12. In paragraph 11, The above system further includes an environmental information acquisition unit that acquires environmental information including the ambient temperature and ambient humidity of the location where the system is located. Full board VACNT transfer system.

13. In paragraph 12, The above system further includes a cooling control unit that controls the cooling temperature and cooling time of the cooling device based on the ambient temperature and ambient humidity obtained by the environmental information obtaining unit, so that the ice layer reaches a predetermined thickness. Full board VACNT transfer system.

14. In paragraph 13, The above cooling control unit controls the thickness of the ice layer to be 10 to 20 μm. Full board VACNT transfer system.

15. A substrate; and a VACNT formed on the substrate; The above VACNT is transferred onto the substrate by a VACNT transfer method according to any one of claims 1 to 7, The above substrate is a substrate whose structure is destroyed at a temperature of 600℃ or higher. VACNT devices.

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