Method for fabricating flexible radio frequency devices based on carbon nanotube arrays by dry transfer

Abstract

This invention discloses a method for fabricating flexible radio frequency (RF) devices based on dry transfer of carbon nanotube arrays, specifically comprising: 1) fabrication of a rigid support layer; 2) fabrication of a carbon nanotube array protective layer; 3) fabrication of an auxiliary layer; 4) full peeling and unwrapping; 5) attachment to the target substrate; 6) thermal release transfer of the array film; 7) residual adhesive cleaning; 8) low-temperature annealing; 9) top-down patterning; 10) defining the gate region; and 11) gate fabrication. This invention utilizes a rigid material to mechanically support the thermal release adhesive peeling process, uses a metal protective layer to prevent organic adhesive from contaminating the carbon nanotube film material, and constructs an auxiliary layer to solve the stress matching problem between the two during the transfer process. This achieves complete peeling of the carbon nanotube array to the flexible substrate with high-quality, non-destructive transfer. The RF transistor device fabricated by this invention can meet the needs of future high-speed communications.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor process technology. Background Technology

[0002] Carbon nanotubes (CNTs), as quasi-one-dimensional semiconductor materials, possess characteristics such as ballistic transport of current carriers, high mobility, high thermal conductivity, and good mechanical properties, making them promising candidates for applications in radio frequency devices, sensors, and flexible electronics. In recent years, breakthroughs have been made in the self-assembly synthesis technology of carbon nanotubes. A team at Peking University successfully fabricated a high-density carbon nanotube monolayer array film on a 4-inch silicon wafer substrate, meeting the requirements for integrated circuit applications. However, carbon nanotube arrays cannot be deposited on substrates other than silicon wafers, which greatly limits the types and application scenarios of carbon nanotube-based electronic devices, making the development of carbon nanotube array transfer technology urgently needed.

[0003] Driven by the development of next-generation IoT communication technologies, radio frequency (RF) devices are moving towards higher frequencies and greater flexibility, placing higher demands on channel materials and device fabrication processes. Carbon nanotubes are considered ideal materials for RF field-effect transistors (FETs), theoretically possessing the physical advantages of high-frequency operation, an intrinsic cutoff frequency close to the terahertz (THz) range, and flexibility. However, limited by the physical characteristics of carbon nanotube arrays, key technologies such as the development of effective non-destructive transfer techniques for carbon nanotube array thin films and low-temperature fabrication processes for RF transistors are needed to fabricate flexible carbon nanotube RF devices and realize their performance advantages.

[0004] Existing methods for transferring nanomaterials, such as two-dimensional thin films, are mainly based on wet transfer or traditional dry transfer. It is well known that due to the high mechanical strength of individual carbon nanotubes, their highly oriented arrays exhibit anisotropic mechanical characteristics, inevitably leading to significant stress issues during the transfer of carbon nanotube array films. In wet transfer, the array arrangement is difficult to maintain after being placed in a liquid, while in traditional dry transfer, films attached to polydimethylsiloxane (PDMS) and other materials are difficult to form and maintain their shape. Therefore, existing methods cannot be used for transferring carbon nanotube arrays. Furthermore, transfer with a silicon substrate that is not fully peeled off cannot meet the performance requirements of flexible bending devices due to differences in Young's modulus. Summary of the Invention

[0005] Purpose of the invention: In order to solve the problems existing in the prior art, the present invention provides a method for fabricating flexible radio frequency devices based on dry transfer of carbon nanotube arrays.

[0006] Technical solution: This invention provides a method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array, specifically including the following steps:

[0007] Step 1: Rigid support layer preparation: Coat the support layer with photoresist, roll out the heat release tape with the non-adhesive side flat on the photoresist, and apply the heat release tape to the support layer by heating and curing.

[0008] Step 2: Fabrication of protective layer for carbon nanotube array: A metal thin film is deposited on the upper surface of the carbon nanotube array, which is deposited on a silicon wafer substrate;

[0009] Step 3: Auxiliary layer preparation: Spin-coating photoresist onto the metal thin film from step 2;

[0010] Step 4: Attach the adhesive side of the heat release tape from Step 1 to the photoresist from Step 3;

[0011] Step 5: For the structure obtained in Step 4, fix the silicon substrate and apply external force to the rigid support layer to completely peel the carbon nanotube array from the silicon substrate.

[0012] Step 6: Attach the carbon nanotube array that was peeled off from the silicon wafer in Step 5 onto the flexible target substrate;

[0013] Step 7: Place the structure obtained in Step 6 on a hot plate and heat it so that the heat release tape loses its adhesiveness, thereby completely peeling the rigid support layer from the carbon nanotube array with metal film; to obtain the metal film-carbon nanotube array-flexible target substrate structure.

[0014] Step 8: Clean the residual adhesive on the structure obtained in Step 7 using an organic solvent;

[0015] Step 9: Place the cleaned metal thin film-carbon nanotube array-flexible target substrate structure into an oven for annealing;

[0016] Step 10: Define and fabricate the source and drain electrode regions and the channel region of the carbon nanotube array on the metal thin film;

[0017] Step 11: Define the gate region in the channel region of the carbon nanotube array and remove the metal film of the gate region by etching;

[0018] Step 12: Deposit the gate dielectric in the channel region of the carbon nanotube array and cover the gate dielectric with gate metal to form a gate structure.

[0019] Furthermore, the support layer is a flat, rigid material, including silicon wafers, glass sheets, quartz sheets, or plastic plates.

[0020] Furthermore, the metal film used is a metal that can be chemically corroded, and the thickness of the metal film ranges from 10 to 500 nm.

[0021] Furthermore, the photoresist in step 3 is polymethyl methacrylate photoresist; the spin coating speed of polymethyl methacrylate photoresist is 5000 rpm, the curing time is greater than 4 minutes, and the thickness is less than 1 μm.

[0022] Furthermore, the flexible substrate is a flexible plastic substrate, and the plastic used is polyethylene phthalate, polyethylene naphthalate, or polyimide.

[0023] Furthermore, in steps 10 and 11, ultraviolet exposure, deep ultraviolet exposure, electron beam direct writing, nano-transfer, or printed electronics technology are used to divide the source region, drain region, channel region, and gate region.

[0024] Furthermore, in step 11, a metal etching solution is used to remove the metal film in the gate region. The metal etching solution is a cyanide-based metal etching solution, a potassium iodide and iodine-based metal etching solution, aqua regia, hydrofluoric acid, boric acid solution, hydrochloric acid solution, nitric acid solution, or any combination of two of the above liquids.

[0025] Furthermore, in step 8, the organic solvent is one or a combination of solvents selected from acetone, acetic acid, chloroform, dichloromethane, or N-methyl-2-pyrrolidone acetonitrile.

[0026] Beneficial Effects: This invention achieves non-destructive transfer of carbon nanotube array films to various substrates through a dry transfer process suitable for carbon nanotube arrays. This allows for the complete peeling of the wafer-level carbon nanotube array film from the original silicon substrate while maintaining its good morphology, resulting in a seamless transfer to the target substrate. This invention eliminates the need for solution-based wet stripping processes, reducing contamination caused by contact between carbon nanotubes and various solutions, and avoiding damage to the carbon nanotube array structure caused by solution surface tension. The transfer process defined in this invention preserves the material and electrical properties of the carbon nanotube array, thereby comprehensively improving the performance, morphology, and applications of carbon nanotube-based transistors. Furthermore, this invention enables flexible carbon nanotube array radio frequency devices, constructing high-quality flexible carbon nanotube transistor circuits for wearable devices, brain-computer interfaces, and other applications. This expands the functional design and integration of heterogeneous carbon nanotube devices while ensuring the performance of carbon nanotube transistors. Attached Figure Description

[0027] Figure 1 This is a flowchart of the present invention;

[0028] Figure 2 This is a structural diagram of the heat-release tape of the present invention after it has been attached to photoresist;

[0029] Figure 3 This is a schematic diagram showing the complete separation of the carbon nanotube array from the silicon wafer.

[0030] Figure 4 This is a structural diagram showing the carbon nanotube array attached to the target flexible substrate.

[0031] Figure 5 This is a schematic diagram of a metal thin film-carbon nanotube array-flexible target substrate structure.

[0032] Figure 6 This is a schematic diagram of the final radio frequency transistor device structure obtained in this invention.

[0033] Figure reference numerals: 1, silicon wafer; 2, carbon nanotube array; 3, metal thin film; 4, auxiliary layer; 5, heat release tape; 6, support layer; 7, target flexible substrate; 8, source and drain electrodes; 9, gate dielectric; 10, gate metal. Detailed Implementation

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0035] like Figure 1 As shown, this embodiment provides a method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array, specifically including the following steps:

[0036] Step 1: Rigid support layer preparation - Photoresist is coated on the support layer 6. The heat release tape 5 with the non-adhesive side facing the support layer is laid flat and fixed on the silicon wafer by a roller. The heat release tape is then attached to the support layer by heating and curing.

[0037] Step 2: Preparation of protective layer for carbon nanotube array - A metal thin film 3 is deposited on the upper surface of the carbon nanotube array 2 deposited on silicon substrate 1.

[0038] Step 3: Auxiliary layer preparation - spin coating photoresist 4 on the metal thin film.

[0039] Step 4: Full peeling and film removal – as follows Figure 2 The heat-release tape obtained in step 1 is attached to the photoresist obtained in step 3; as shown. Figure 3 As shown, the silicon substrate is fixed in place, and an external force is applied to the rigid support layer, so that the entire carbon nanotube array is completely separated from the silicon substrate as a whole.

[0040] Step 5: Target Substrate Attachment – ​​Attach the carbon nanotube array obtained in Step 4 onto the surface of the target substrate, such as... Figure 4 As shown.

[0041] Step 6: Thermal Release Transfer – The structure obtained in Step 5 is placed on a hot plate and heated, causing the thermal release adhesive to lose its adhesiveness and peel off from the metal film on the carbon nanotube array, resulting in a metal film-carbon nanotube array-flexible target substrate structure. This structure is as follows: Figure 5 As shown.

[0042] Step 7: Residual adhesive cleaning – Use organic solvents to clean the residual adhesive on the surface of the metal thin film with the structure obtained in Step 6.

[0043] Step 8: Low-temperature annealing – Place the structure obtained in step 7 into an oven for annealing.

[0044] Step 9: Top-down patterning - Define and fabricate the source and drain electrode regions 8 and the channel region of the carbon nanotube array on the metal thin film; in this embodiment, UV exposure, deep UV exposure, electron beam writing, nano-transfer or printed electronics technology is used to divide the source region, drain region, channel region and gate region.

[0045] Step 10: Define the gate region—The gate region is defined on the channel region obtained in step 9 by photolithography or electron beam direct writing, and the metal film of the gate region is removed by etching. The metal etching solution used in this embodiment is a cyanide-based metal etching solution, a potassium iodide and iodine metal etching solution, aqua regia, hydrofluoric acid, boric acid solution, hydrochloric acid solution, nitric acid solution, or any combination of two of the above liquids.

[0046] Step 11: As Figure 6 As shown, the gate is fabricated by depositing the gate dielectric 9 on a carbon nanotube array in the gap between the source and drain electrodes using atomic layer deposition (ALD), and then covering the gate dielectric with gate metal 10 to form a gate structure.

[0047] The support layer mentioned in step 1 can be a flat, rigid material such as a glass sheet, quartz sheet, or plastic plate, which can play a supporting role and avoid problems such as film cracking and damage, poor continuity caused by the bending of the tape during mechanical peeling, as well as incomplete release caused by uneven application of the heat release adhesive.

[0048] The metal film used in step 2 is made of one or more metals that can be chemically etched, such as gold or palladium; the thickness of the metal film is 10-500 nm, preferably 50-100 nm, and after spin coating, it is baked at 180°C for 5 min; the metal film is in direct contact with the carbon nanotubes, thereby avoiding contamination of the surface-active carbon nanotube film material by organic adhesive, which is then removed by etching, thereby improving the cleanliness of the carbon nanotube array film surface.

[0049] The photoresist used in step 3 is polymethyl methacrylate (PMMA) photoresist. When spin-coating PMMA, the rotation speed is 5000 rpm, the curing time is >4 minutes, and the thickness needs to be less than 1 μm. In this embodiment, the thickness is 500 nm. PMMA serves as an auxiliary layer to separate the heat release adhesive and the metal protective layer, solving the stress mismatch problem between the two and preventing the metal from cracking and the heat release adhesive from penetrating during the heat release process.

[0050] The flexible substrate mentioned in step 5 is a flexible plastic substrate, wherein the plastic is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyimide (PI).

[0051] Because of the rigid support layer, the structure carried by the heat-release adhesive before this step cannot be stretched or bent. Therefore, the flexible substrate can be attached to the heat-release adhesive by roller to achieve the best transfer bonding effect.

[0052] The organic solvents in step 7 include acetone, acetic acid, chloroform, dichloromethane, N-methyl-2-pyrrolidone acetonitrile, and combinations thereof. The adhesive removal time is 30 minutes to 1 hour. The optimal residual adhesive cleaning process and combination for removing the heat-release adhesive of the corresponding formulation can be selected as needed. There is no need for a complicated adhesive removal process, avoiding the impact of residual adhesive on the surface morphology and cleanliness of carbon nanotubes, which in turn affects the ohmic contact with metals and other interface state problems of transistors.

[0053] In step 8, the annealing temperature is 80~100℃ and the time is 8~12 hours. In this embodiment, the annealing temperature is 90℃.

[0054] Step 9 uses oxygen plasma etching technology to remove the carbon nanotube film.

[0055] The gate medium mentioned in step 11 is either alumina (Al2O3) or hafnium oxide (HfO2), the deposition temperature is less than 90℃ to ensure the stability of carbon nanotubes during the medium growth process, and the thickness of the deposited medium is greater than 10nm to ensure that the channel region is completely covered by the gate medium.

[0056] An embodiment of the present invention:

[0057] Prepare a support layer (in this embodiment, a silicon wafer is used as the support layer) and thermal release tape. Spin-coat AZ7908 adhesive onto the silicon wafer. Place the non-adhesive side of the thermal release tape facing the silicon wafer, and use a roller to lay it flat and fix it onto the silicon wafer. Heat and cure the thermal release tape at 110°C for 2 minutes to attach it to the silicon wafer. Peel off the release film of the thermal release tape. Attach a PI film to any one of the four edges of the adhesive side of the thermal release tape to make the area covered by the PI film lose its adhesiveness, facilitating subsequent peeling. The PI film is a release plastic film with a thickness of <10μm.

[0058] A 50nm thick metal film is first deposited on the upper surface of the carbon nanotube array deposited on a silicon wafer substrate with silicon oxide to prevent organic contamination such as photoresist or thermal release adhesive, which greatly reduces radio frequency performance and improves cleanliness. Then, PMMA A6 photoresist is coated on top of the gold protective layer. The construction of the PMMA auxiliary layer plays a role in isolating stress and preventing deformation, and better assists in maintaining the morphology of the carbon nanotube array during the complete peeling and release process.

[0059] In step (1), the adhesive side of the heat-release adhesive tape is attached to the PMMA A6 photoresist. Air is expelled by electrostatic adsorption to form an adhesive bond. After the remaining air bubbles are expelled, an external force is applied to the support layer. This external force is along the edge with the PI film in step (1). Through the competition of van der Waals forces between the desorption and adsorption forces, the carbon nanotube array is completely separated from the silicon substrate. (In this embodiment, the PI film is attached to one side of the heat-release adhesive tape, which makes the peeling of the carbon nanotube array from the silicon substrate smoother.)

[0060] Prepare a flexible target substrate. After cleaning with acetone and alcohol, attach the carbon nanotube array that has been separated from the silicon wafer substrate to the flexible target substrate.

[0061] The heat-release adhesive tape with the structure obtained above is heated on a hot plate at a temperature above 130°C. The heat-release adhesive loses its adhesiveness upon heating, and the carbon nanotube array film detaches from the heat-release adhesive tape and autonomously adheres to the target substrate, forming a metal film-carbon nanotube array-flexible target substrate structure with a metal film on the top layer, a carbon nanotube array in the middle layer, and the target substrate at the bottom layer.

[0062] To remove residual adhesive from the surface of the metal thin film-carbon nanotube array-flexible target substrate structure, organic solvents were used to reduce residual organic compounds such as PMMA and heat-release adhesives (mainly acrylic acid) on the metal thin film surface. The film was then immersed in acetone for 30 minutes, soaked in ethanol for 10 minutes, immersed in NMP at 60°C for 30 minutes, and soaked in ethanol for 10 minutes.

[0063] The metal thin film-carbon nanotube array-flexible target substrate structure was annealed in a 90℃ oven for 8 hours to release the micro-stress caused during the transfer process and optimize the electrical performance of the carbon nanotube array on the new substrate.

[0064] The source and drain electrode regions and the channel region of the carbon nanotube array are defined on the metal thin film by photolithography. Ti / Au (titanium / gold, in this embodiment the thickness of Ti is 20nm and the thickness of Au is 180nm) is deposited at the electrode pattern. Then, the metal thin film outside the active region is removed by etching and oxygen plasma etching, and the carbon nanotube thin array outside the active region is removed by oxygen plasma etching.

[0065] The gate region is defined on the channel region by photolithography or electron beam direct writing, and the metal film of the gate region is removed by etching, so that the carbon nanotube array is exposed and the gap between the source and drain electrodes is formed.

[0066] Al₂O₃ (alumina) was deposited onto a carbon nanotube array within the gap between the source and drain electrodes using atomic layer deposition (ALD) at a temperature of 90°C, resulting in a thickness of 10 nm. Subsequently, Ti / Au was deposited onto the gate dielectric to form the gate structure. This completed the fabrication of a flexible radio frequency device based on carbon nanotube array transfer.

[0067] Examples and analyses in contrast to the present invention:

[0068] 1. Without PMMA auxiliary layer – metal film peeling, array stress, unable to transfer; specific steps are as follows:

[0069] Prepare a silicon wafer and thermal release tape. Spin-coat AZ7908 adhesive onto the silicon wafer, then lay and fix the thermal release tape onto it. Evaporate 100nm of gold onto the upper surface of the carbon nanotube array deposited on the silicon substrate. Apply the thermal release tape to the upper surface of the carbon nanotube array with the metal film, then peel it off. Cracks are visible on the surface of the metal film. This is due to the adhesive expanding upon contact with the hot plate and the uneven stress on the carbon nanotube array during peeling. The load on the metal film surface cannot be transferred outwards, and the low toughness of the metal hinders its absorption of deformation energy before fracture. During the thermal release process, due to the destruction of the metal structure, the thermal release adhesive penetrates into the layered structure of the gold / carbon nanotubes, causing deformation of the film structure and the formation of micro-regional mechanical stress. This results in the rupture of the gold / carbon nanotube film after thermal release. Characterization analysis shows that the morphology of the carbon nanotube array is permanently damaged, and the electrical properties of the film are lost, making it unsuitable for the fabrication of radio frequency transistors.

[0070] 2. Metal-free thin films – PMMA and acrylic adhesive contamination reduce electrical properties, and filler expansion disrupts array morphology.

[0071] The specific steps are as follows:

[0072] Prepare a quartz wafer and thermal release tape. Spin-coat AZ7908 adhesive onto a silicon wafer, then lay and fix the thermal release tape onto the wafer. Spin-coat PMMA A6 photoresist with a thickness of 500 nm onto the upper surface of the carbon nanotube array deposited on the silicon substrate. Attach the thermal release tape to the upper surface of the carbon nanotube array with a PMMA auxiliary layer, then peel off the tape and attach the carbon nanotube-containing side to the PI substrate. Heat to 130°C for release, clean to remove the photoresist, and anneal to obtain a directly exposed carbon nanotube array / flexible substrate. Subsequently, deposit a 50 nm layer of gold, pattern the source, drain, and gate using photolithography, define the gate using electron beam writing, etch a metal thin film, grow a 10 nm layer of HfO2 as the gate dielectric using ALD, and deposit the gate metal to form an RF transistor device. Testing revealed that the channel current is less than 100 μA / mm, representing a two-order-of-magnitude attenuation compared to this embodiment. Characterization revealed a large amount of organic residue on the carbon nanotubes within the channels, and the array morphology was disrupted, forming numerous disordered and oriented regions. This was due to the absence of the metal film, which allowed for the infiltration of a large amount of heat-release adhesive (acrylic adhesive) and PMMA adhesive. During the heat release process, the adhesive, in a semi-liquid, semi-solid state, exhibited greatly enhanced fluidity, penetrating into the carbon nanotube array, compressing and disrupting its morphology, and seeping into the lower surface of the carbon nanotubes, making it difficult to remove during subsequent adhesive removal and cleaning. The extensive coating of organic adhesive created defects and phonon scattering, weakening the electrical properties of the carbon nanotube array.

[0073] 3. Lack of rigid support layer – wrinkles and cracks, mechanical deformation, large-area peeling and delamination, inability to maintain array morphology. Specific steps are as follows:

[0074] A 50nm layer of gold was deposited on the upper surface of a carbon nanotube array on a silicon substrate. Subsequently, a 500nm thick PMMA A6 photoresist was spin-coated onto the upper surface as an auxiliary layer. Thermally release tape was applied to the upper surface of the carbon nanotube array with the PMMA auxiliary layer and gold protective layer. The tape was then peeled off, and the carbon nanotube-containing side was attached to a PI substrate. The substrate was then heated to 130°C for release. After cleaning to remove the photoresist and annealing, large-area wrinkling and detachment of the carbon nanotubes and metal film were observed. The lack of a rigid support layer was the main cause of this phenomenon. Because the thermally release tape required a certain load to bend and peel off the carbon nanotubes during the process, the gold protective layer on the carbon nanotube array stretched and slipped in the micro-regions. After returning to its flat state, the stretched portions overlapped and transferred to the target substrate, resulting in a large number of overlapping micro-regions of the carbon nanotube array, thus losing the monolayer array morphology. During the removal of adhesive and cleaning with organic solvents, the overlapping and wrinkled metal films cause the organic solvent to penetrate and abrupt changes in regional stress. The partial contact between the carbon nanotubes and the target substrate is also reduced, resulting in van der Waals adsorption in these areas and causing partial film detachment. Due to the inherent high stress of the carbon nanotube array itself, the peeling off of micro-regions leads to large-area detachment and peeling, causing transfer failure.

[0075] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for fabricating a flexible radio frequency device based on dry transferred carbon nanotube arrays, characterized in that: Specifically, the steps include the following: Step 1: Rigid support layer preparation: Coat the support layer with photoresist, roll out the heat release tape with the non-adhesive side flat on the photoresist, and apply the heat release tape to the support layer by heating and curing. Step 2: Fabrication of protective layer for carbon nanotube array: A metal thin film is deposited on the upper surface of the carbon nanotube array, which is deposited on a silicon wafer substrate; Step 3: Auxiliary layer preparation: Spin-coating photoresist onto the metal thin film from step 2; Step 4: Attach the adhesive side of the heat release tape from Step 1 to the photoresist from Step 3; Step 5: For the structure obtained in Step 4, fix the silicon substrate and apply external force to the rigid support layer to completely peel the carbon nanotube array from the silicon substrate. Step 6: Attach the carbon nanotube array that was peeled off from the silicon wafer in Step 5 onto the flexible target substrate; Step 7: Place the structure obtained in Step 6 on a hot plate and heat it so that the heat release tape loses its adhesiveness, thereby completely peeling the rigid support layer from the carbon nanotube array with metal film; to obtain the metal film-carbon nanotube array-flexible target substrate structure. Step 8: Clean the residual adhesive on the structure obtained in Step 7 using an organic solvent; Step 9: Place the cleaned metal thin film-carbon nanotube array-flexible target substrate structure into an oven for annealing; Step 10: Define and fabricate the source and drain electrode regions and the channel region of the carbon nanotube array on the metal thin film; Step 11: Define the gate region in the channel region of the carbon nanotube array and remove the metal film of the gate region by etching; Step 12: Deposit the gate dielectric in the channel region of the carbon nanotube array and cover the gate dielectric with gate metal to form a gate structure.

2. The method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array according to claim 1, characterized in that: The support layer is a flat, rigid material, including silicon wafers, glass sheets, quartz sheets, or plastic plates.

3. The method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array according to claim 1, characterized in that: The metal film used is a metal that can be chemically corroded, and the thickness of the metal film ranges from 10 to 500 nm.

4. The method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array according to claim 1, characterized in that: The photoresist used in step 3 is polymethyl methacrylate (PMMA) photoresist; when spin-coating PMMA photoresist, the rotation speed is 5000 rpm, the curing time is greater than 4 minutes, and the thickness is less than 1 μm.

5. The method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array according to claim 1, characterized in that: The flexible target substrate is a flexible plastic substrate, and the plastic used is polyethylene phthalate, polyethylene naphthalate, or polyimide.

6. The method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array according to claim 1, characterized in that: In steps 10 and 11, ultraviolet exposure, deep ultraviolet exposure, electron beam direct writing, nano-transfer, or printed electronics techniques are used to divide the source region, drain region, channel region, and gate region.

7. The method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array according to claim 1, characterized in that: In step 11, a metal etching solution is used to remove the metal film in the gate region. The metal etching solution is a cyanide-based metal etching solution, a potassium iodide and iodine-based metal etching solution, aqua regia, hydrofluoric acid, boric acid solution, hydrochloric acid solution, nitric acid solution, or any combination of two of the above liquids.

8. The method for fabricating a flexible radio frequency device based on a dry transfer carbon nanotube array according to claim 1, characterized in that: In step 8, the organic solvent is one or a combination of multiple solvents selected from acetone, acetic acid, chloroform, dichloromethane, or N-methyl-2-pyrrolidone acetonitrile.

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