Method for preparing sub-10nm gap on flexible substrate and flexible substrate

Abstract

The invention discloses a method for preparing a sub-10-nanometer gap on a flexible substrate and the flexible substrate, and belongs to the technical field of nanostructure preparation. According to the method, the photoresist film subjected to photoetching development is transferred to the pre-stretched flexible substrate by using the heat release seal to serve as a nano mask to realize in-situ deposition of a functional material, and a sub-10nm gap with strong adhesion is finally obtained on the flexible substrate, so that displacement and loss of a nano structure on the flexible substrate are avoided, and the yield of the flexible substrate is improved. And an organic solvent is prevented from being used on the flexible substrate, so that the precision of the sub-10 nanometer structure on the flexible substrate can be ensured.

Description

Technical Field

[0001] This invention relates to the field of nanostructure fabrication technology, and more particularly to a method for fabricating sub-10 nanometer gaps on a flexible substrate and the flexible substrate itself. Background Technology

[0002] Compared to traditional rigid devices, flexible substrates integrating functional elements offer numerous advantages such as flexibility, dynamic tunability, and biocompatibility, leading to their wide application in fields like flexible Raman detection and flexible biosensing. However, reliably fabricating sub-10 nanometer structures on flexible substrates remains challenging. Traditional transfer methods offer a feasible solution for fabricating micro / nano structures on flexible substrates; however, the weak adhesion between the transferred nanostructure and the flexible substrate hinders stable integration. Post-processing, such as high-temperature annealing and modification, can enhance adhesion, but these processes are time-consuming, and the high temperatures can introduce irreversible stress damage to both the substrate and the nanostructure. These challenges limit the reliable and stable fabrication of sub-10 nanometer structures on flexible substrates and their application in micro / nano optoelectronic devices. Summary of the Invention

[0003] The main objective of this invention is to provide a method for fabricating sub-10 nanometer gaps on a flexible substrate and a flexible substrate, thereby solving the technical problem of the difficulty in fabricating sub-10 nanometer structures on the surface of a flexible substrate.

[0004] To achieve the above objectives, the present invention provides a method for fabricating sub-10 nanometer gaps on a flexible substrate, comprising the following steps: Substrate preparation: A rigid substrate and a flexible substrate are provided, and the flexible substrate is pre-stretched to obtain a pre-stretched flexible substrate; Photoresist coating: Spin-coating photoresist onto the surface of the hard substrate and removing residual solvent; Photolithography and development: The resist is patterned and developed to obtain a photoresist film; Transfer: A heat release stamp is applied to the surface of the photoresist film away from the rigid substrate. After the heat release stamp and the photoresist film make conformal contact, the photoresist film is peeled off from the surface of the rigid substrate and transferred to the surface of the pre-stretched substrate using the heat release stamp. The heat release stamp is then released to obtain a pre-stretched flexible substrate with a photoresist film. Thin film deposition: A functional material layer is obtained by depositing a functional material on the surface of the photoresist film on the pre-stretched flexible substrate; Peeling: An adhesive layer is covered on the surface of the pre-stretched flexible substrate where the functional material layer is located. After the functional material on the surface of the photoresist film and the adhesive layer make conformal contact, the adhesive layer is peeled off. Releasing the substrate: Releasing the pre-stretching force restores the pre-stretched flexible substrate to its initial state.

[0005] In some embodiments of the present invention, the hard substrate includes at least one of silicon, silicon carbide, silicon oxide, silicon nitride, quartz, diamond, and ITO.

[0006] In some embodiments of the present invention, the photoresist includes a positive photoresist, which includes at least one of polydimethylsiloxane, ZEP photoresist, and AR-P photoresist. And / or, the thickness of the photoresist film is 50nm~300nm; And / or, the heat-release stamp includes a heat-responsive adhesive performance switching material, which includes at least one of polydimethylsiloxane and heat-release tape.

[0007] In some embodiments of the present invention, the functional material includes metallic or non-metallic materials. The metal includes pure metals or alloys, the pure metals include gold, silver, aluminum, titanium, chromium, nickel or copper, and the alloys include at least one of aluminum alloys, copper alloys and nickel-chromium alloys; The non-metallic material includes at least one of oxides and semiconductor materials, wherein the oxide includes at least one of aluminum oxide, silicon oxide, and titanium oxide, and the semiconductor material includes at least one of silicon and germanium.

[0008] In some embodiments of the present invention, the adhesive layer includes at least one of polydimethylsiloxane, high-temperature tape, transparent tape, nano tape, polyvinyl alcohol, AB glue, UV-curable adhesive, ordinary tape, and heat-release tape.

[0009] In some embodiments of the present invention, before spin-coating photoresist onto the surface of the hard substrate, the hard substrate is surface-treated to obtain a monomolecular anti-adhesion layer, and the photoresist is spin-coated onto the surface of the monomolecular anti-adhesion layer.

[0010] In some embodiments of the present invention, the monomolecular anti-adhesion layer comprises a monomolecular anti-adhesion material, which includes at least one of hexamethyldisilazane, octadecyltrichlorosilane, trichloro(1H,1H,2H,2H-tridecylfluoron-octyl)silane, and n-octyltrichlorosilane.

[0011] In some embodiments of the present invention, the surface treatment includes the following steps: depositing the monomolecular anti-adhesion layer on the surface of the hard substrate by vapor deposition in a vacuum environment.

[0012] In some embodiments of the present invention, the deposition time is 1 min to 20 min, the deposition temperature is 25°C to 300°C, and the deposition amount of the monomolecular anti-adhesion layer is 100 µL to 1 ml.

[0013] The present invention also provides a flexible substrate having a sub-10 nanometer gap, wherein the sub-10 nanometer gap is prepared by the method described above for preparing a sub-10 nanometer gap on a flexible substrate. The beneficial effects that this invention can achieve are: This invention utilizes a thermal release stamp to transfer the photoresist film after photolithography and development onto a pre-stretched flexible substrate, which acts as a nanomask to achieve in-situ deposition of functional materials, ultimately obtaining a sub-10 nanometer gap with strong adhesion on the flexible substrate.

[0014] The preparation method of the present invention not only avoids the displacement and loss of nanostructures on flexible substrates, but also avoids the use of organic solvents on flexible substrates, which helps to ensure the precision of sub-10 nanometer structures on flexible substrates.

[0015] This invention provides a new solution for the fabrication of sub-10 nanometer structures in the fields of micro-nano manufacturing, optics, biology, surface science, and bionics. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart of a method for preparing sub-10 nanometer gaps on a flexible substrate according to the present invention.

[0018] Figure 2 This is a microscopic image of the sub-10 nanometer gap on the surface of the flexible substrate in Embodiment 1 of the present invention.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] In this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention.

[0023] This invention provides a method for fabricating sub-10 nanometer gaps on a flexible substrate, and the flexible substrate itself. The fabrication method includes the following steps: Substrate preparation: Provide rigid and flexible substrates, see reference. Figure 1 Group a, (i) and (ii), pre-stretch the flexible substrate to obtain a pre-stretched flexible substrate; Glue application: Reference Figure 1 (iii) of group b: spin-coating photoresist onto the surface of a hard substrate and removing residual solvent; Photolithography, development: Reference Figure 1 In group b (iv), the photoresist is patterned and developed to obtain a photoresist film. Transfer: Reference Figure 1 In group b, (v), (vi) and (vii), a heat release stamp is applied to the surface of the photoresist film away from the hard substrate. After the heat release stamp and the photoresist film make conformal contact, the photoresist film is peeled off from the surface of the hard substrate and transferred to the surface of the pre-stretched substrate using the heat release stamp. The heat release stamp is then released to obtain a pre-stretched flexible substrate with a photoresist film. Thin Film Deposition: Reference Figure 1 In group b (viii), a functional material layer is obtained by depositing a functional material on the surface of a pre-stretched flexible substrate with a photoresist film. Stripping: Reference Figure 1 In group b (ix), an adhesive layer is covered on the surface of a pre-stretched flexible substrate with a functional material layer. After the functional material and the adhesive layer on the surface of the photoresist film achieve conformal contact, the adhesive layer is peeled off. Release substrate: reference Figure 1 Group b (x) releases the pre-stretching force to restore the pre-stretched flexible substrate to its initial state.

[0024] This invention utilizes a thermal release stamp to transfer a photoresist film, after photolithography and development, onto a pre-stretched flexible substrate, acting as a nanomask to achieve in-situ deposition of functional materials. This ultimately yields sub-10 nanometer gaps with strong adhesion on the flexible substrate. The fabrication method of this invention not only avoids the displacement and loss of nanostructures on the flexible substrate but also avoids the use of organic solvents on the flexible substrate, preventing damage from organic solvents and ensuring the precision and integrity of the sub-10 nanometer structures on the flexible substrate.

[0025] In some embodiments, the hard substrate includes at least one of silicon, silicon carbide, silicon oxide, silicon nitride, quartz, diamond, and TCO. TCO is a transparent conductive oxide, including at least one of ITO and FTO.

[0026] In some embodiments, cleaning the hard substrate to remove impurities from the substrate surface is beneficial for the adhesion of the photoresist film.

[0027] In some embodiments, cleaning with oxygen plasma for 1 minute can effectively remove impurities from the surface of a hard substrate and attach hydroxyl groups (-OH) to the surface, which is beneficial for the adhesion of photoresist films.

[0028] In some embodiments, the mass concentration of the photoresist spin-coated onto the surface of the hard substrate is 3% to 5%.

[0029] In some embodiments, the photoresist includes a positive photoresist.

[0030] In some embodiments, the positive photoresist includes at least one of PMMA, ZEP photoresist, and AR-P photoresist; In some embodiments, the thickness of the photoresist film is 50 nm to 300 nm.

[0031] In some embodiments, the spin coating parameters are 500 r / 5 s for low speed and 4000 r / 60 s for high speed.

[0032] In some embodiments, the hard substrate after photoresist spin coating is heated to remove residual solvent. The heating temperature is 80°C to 180°C, and the heating time is 1 min to 5 min.

[0033] In some embodiments, the hard substrate after photoresist spin coating can be placed on a hot plate for heating and baking to remove residual solvent.

[0034] In some embodiments, the equipment used for exposure includes the Raith 150 two electron beam exposure equipment.

[0035] In some embodiments, the exposure voltage is 28KV~32KV, which can be 30KV, and the aperture is 29 μm~31 μm, which can be 30 μm.

[0036] In some embodiments, the exposed hard substrate is immersed in a developing solution for development, the developing solution comprising a mixture of water and isopropanol, wherein the volume ratio of water to isopropanol is 10:1.

[0037] In some embodiments, the development time is 0.8 min to 1.2 min, and may be 1.0 min.

[0038] In some embodiments, after development is completed, a hard substrate with a photoresist film is obtained by blowing it with nitrogen gas.

[0039] In the transfer process, refer to Figure 1 In group b (v) to (vii), a thermal release stamp is attached to the surface of the photoresist film on a rigid substrate, achieving conformal contact with the photoresist film. After achieving conformal contact, the thermal release stamp is peeled off from the surface of the rigid substrate, transferring the photoresist film to the surface of the thermal release stamp. Then, the side of the thermal release stamp with the photoresist film is attached to the surface of a pre-stretched flexible substrate. Finally, the thermal release stamp is released, thus transferring the photoresist film from the rigid substrate to the surface of the pre-stretched flexible substrate. Using a thermal release stamp to transfer the photoresist film after photolithography and development onto the pre-stretched flexible substrate can act as a nanomask for in-situ deposition of subsequent functional materials. It can ultimately obtain sub-10 nanometer gaps with strong adhesion on the flexible substrate. In addition, it avoids the displacement and loss of nanostructures on the flexible substrate, and avoids the use of organic solvents on the flexible substrate, preventing damage to the flexible substrate by organic solvents.

[0040] In some embodiments, a heat release stamp is released from the surface of a pre-stretched flexible substrate by a heat release method, which includes the steps of heating the heat release stamp until it is completely released from the surface of the pre-stretched flexible substrate.

[0041] In some embodiments, the heating temperature for heat release is 95°C to 105°C, or 100°C, and the heating time for heat release is 0.8 min to 1.1 min, or 1 min. This allows the heat release stamp to be completely released from the surface of the pre-stretched flexible substrate, and the photoresist film to be completely transferred to the surface of the pre-stretched flexible substrate.

[0042] In some embodiments, heating the heat release stamp above it using a heating element facilitates rapid release and peeling of the heat release stamp.

[0043] In some embodiments, the heat-release stamp includes a heat-responsive adhesive performance switching material, which refers to a functional material whose adhesive performance can be reversibly or irreversibly adjusted by temperature changes, wherein the adhesive performance can be characterized by adhesive force and peel strength.

[0044] In some embodiments, the heat-responsive adhesive performance switching material includes at least one of polydimethylsiloxane (PDMS) and heat-release tape.

[0045] In the thin film deposition step, refer to Figure 1 In group b (Viii), the functional material is deposited on the surface of the photoresist film and also on the surface of the pre-stretched flexible substrate that is not covered by the photoresist film, thereby forming a functional material layer.

[0046] In some embodiments, the functional material includes metallic or non-metallic materials.

[0047] Metals include pure metals or alloys. Pure metals include gold, silver, aluminum, titanium, chromium, nickel, or copper. Alloys include at least one of aluminum alloys, copper alloys, and nickel-chromium alloys.

[0048] Non-metallic materials include at least one of oxides and semiconductor materials. Oxides include at least one of aluminum oxide, silicon oxide, and titanium oxide. Semiconductor materials include at least one of silicon and germanium.

[0049] In some embodiments, a pre-stretched flexible substrate is placed inside a thermal evaporation chamber for the deposition of a functional material layer.

[0050] In some embodiments, the vacuum level of the vapor deposition environment is 5 × 10⁻⁶. 4 Pa.

[0051] In some embodiments, the evaporation rate is 0.1 Å / s to 1 Å / s.

[0052] In the stripping step, refer to Figure 1 In group b (ix), an adhesive layer is applied to the surface of the pre-stretched substrate with a functional material layer. This adhesive layer conformally contacts the functional material on the photoresist film surface. When the adhesive layer is peeled off, it removes both the photoresist film on the pre-stretched flexible substrate surface and the functional material covering it, preserving the functional material formed on the pre-stretched flexible substrate surface, thus obtaining a sub-10 nm gap. This step achieves the fabrication of a sub-10 nm gap on the pre-stretched flexible substrate surface through dry peeling, avoiding solvent penetration or capillary damage to the sub-10 nm gap caused by wet processes.

[0053] In some embodiments, the adhesive layer includes at least one of polydimethylsiloxane (PDMS), high-temperature tape, transparent tape, nano tape, polyvinyl alcohol (PVA), AB glue, UV-curable adhesive, ordinary tape, and heat-release tape.

[0054] In some embodiments, refer to Figure 1 In groups b (ii) and (iii), before spin-coating photoresist onto the surface of the hard substrate, the hard substrate is surface-treated to obtain a monomolecular anti-adhesion layer, resulting in a near-zero adhesion surface. Spin-coating photoresist onto the surface of the monomolecular anti-adhesion layer with near-zero adhesion properties can ensure that the photoresist is completely peeled off during subsequent transfer, while maintaining the uniformity of spin-coating and ensuring the fidelity of the sub-10 nanometer gap pattern.

[0055] The monomolecular anti-adhesion layer includes a monomolecular anti-adhesion material, which includes at least one of hexamethyldisilazane (HMDS), octadecyltrichlorosilane (OTS), trichloro(1H,1H,2H,2H-tetrafluoron-octyl)silane, and n-octyltrichlorosilane.

[0056] In some embodiments, the surface of the hard substrate has a monomolecular anti-adhesion layer, which helps to significantly reduce the surface energy of the hard substrate, achieve near-zero adhesion without affecting the uniformity of photoresist spin coating, and ensure the non-destructive transfer of subsequent nanostructures.

[0057] In some embodiments, the surface treatment includes the following steps: depositing a monomolecular anti-adhesion layer on the surface of a hard substrate by vapor deposition in a vacuum environment.

[0058] In some embodiments, the deposition time is 1 min to 20 min and the deposition temperature is 25°C to 300°C.

[0059] In some embodiments, the deposition amount of the monomolecular anti-adhesion layer is 100 µL to 1 ml.

[0060] It is understandable that the deposition amount of the monomolecular anti-adhesion layer of 100 µL to 1 ml refers to the deposition amount of the monomolecular anti-adhesion material solution obtained by dissolving the monomolecular anti-adhesion material.

[0061] In some embodiments, the hard substrate that has undergone surface treatment is cleaned, and the cleaning steps include: ultrasonic cleaning in acetone solution for 1 min, ultrasonic cleaning in isoacetone solution for 1 min, and drying with nitrogen gas.

[0062] In some embodiments, the surface treatment specifically includes the following steps: placing the cleaned hard substrate in a vacuum oven at 120°C, placing a glass petri dish about 5 cm away from the hard substrate, adding 100 µL to 1 ml of monomolecular anti-adhesion material solution to the petri dish, evacuating for 2 min, turning off the vacuum pump, depositing on the hard substrate for 15 min, removing the hard substrate after deposition, ultrasonically cleaning it in acetone solution for 1 min, ultrasonically cleaning it in isopropanol solution for 1 min, and drying it with nitrogen gas.

[0063] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0064] Example 1 Substrate preparation: Refer to Figure 1 In step b(i), a clean single-crystal silicon substrate is selected and cleaned with oxygen plasma for 1 min; refer to Figure 1 In step a, a pre-stretched PDMS flexible substrate is obtained by pre-stretching the PDMS flexible substrate using a fixture. (Refer to...) Figure 1 In step b(ii), the cleaned single-crystal silicon substrate was placed in a vacuum oven at 120°C. A glass culture dish was placed about 5 cm away from the substrate, and 200 µL of OTS solution was dropped into the culture dish. After vacuuming for 2 min, the vacuum pump was turned off. After modification for 15 min, the single-crystal silicon substrate was removed, and then ultrasonically cleaned in acetone solution for 1 min, ultrasonically cleaned in isopropanol solution for 1 min, and dried with nitrogen gas to obtain a near-zero adhesion surface on the single-crystal silicon substrate.

[0065] Apply adhesive: Refer to Figure 1 In b(iii), a 3% PMMA photoresist is spin-coated onto a near-zero adhesion surface of a single-crystal silicon substrate. The spin-coating parameters are 500r / 5s at low speed and 4000r / 60s at high speed. Then, the substrate is baked on a hot plate at 180°C for 5 min to remove residual solvent.

[0066] Photolithography and development: See reference Figure 1 In step b(iv), the PMMA photoresist was exposed using an electron beam exposure device Raith 150 two with a high voltage of 30 kV and a 30 μm aperture. The exposed film was then immersed in a mixed solution of H2O:IPA = 10:1 for 1 min for development, and then dried with nitrogen to obtain the PMMA photoresist film.

[0067] Transfer: Refer to Figure 1In group b, (v), (vi), and (vii), the thermal release stamp is attached to the surface of the PMMA photoresist film away from the single-crystal silicon substrate. After the thermal release stamp and the PMMA photoresist film achieve conformal contact, the PMMA photoresist film is peeled off from the surface of the single-crystal silicon substrate using the thermal release stamp. The peeled-off PMMA photoresist film is then attached to the surface of the pre-stretched PDMS flexible substrate. The thermal release stamp is heated from above using a heating plate at a temperature of 100°C for 1 minute. After the thermal release stamp is completely released, it is removed.

[0068] Thin film deposition: Reference Figure 1 In group b (viii), the pre-stretched PDMS flexible substrate, along with the fixture, is placed into a thermal evaporation chamber for functional material deposition. Specifically, a 2 nm layer of Cr and a 30 nm layer of Au are deposited sequentially to obtain the functional material layer. The vacuum level of the chamber during evaporation is 5 × 10⁻⁶. 4 Pa, with evaporation rates of 0.1 Å / s and 1 Å / s, respectively.

[0069] Stripping: Reference Figure 1 In group b (ix), after the functional material is vapor-deposited, the fixture is removed, high-temperature tape is attached to the PDMS pre-stretched substrate, and the PMMA photoresist film is peeled off to achieve dry peeling.

[0070] Release substrate: Reference Figure 1 In group b (x), the tensile force of the PDMS pre-stretched substrate is released, that is, a sub-10 nanometer gap with strong adhesion is obtained on the flexible substrate.

[0071] The sub-10 nanometer gaps formed on the surface of the flexible substrate in Example 1 were observed using a scanning electron microscope, and the results are as follows: Figure 2 As shown.

[0072] Example 2 Example 2 describes the preparation of sub-10 nanometer gaps on the surface of a flexible substrate using the same method as in Example 1. The difference is that the photoresist used in Example 2 is ZEP photoresist.

[0073] Example 3 Example 3 describes the preparation of a sub-10 nanometer gap on the surface of a flexible substrate using the same method as in Example 1. The difference is that the photoresist in Example 3 is an AR-P photoresist.

[0074] Example 4 Example 4 describes the preparation of a sub-10 nanometer gap on the surface of a flexible substrate using the same method as in Example 1. The difference is that the heat release stamp in Example 4 is a heat release tape.

[0075] Example 5 Example 5 describes the preparation of sub-10 nanometer gaps on the surface of a flexible substrate using the same method as in Example 1. The difference is that the functional material in Example 5 is gold.

[0076] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for fabricating sub-10 nanometer gaps on a flexible substrate, characterized in that, Includes the following steps: Substrate preparation: A rigid substrate and a flexible substrate are provided, and the flexible substrate is pre-stretched to obtain a pre-stretched flexible substrate; Photoresist coating: Spin-coating photoresist onto the surface of the hard substrate and removing residual solvent; Photolithography and development: The resist is patterned and developed to obtain a photoresist film; Transfer: A heat release stamp is applied to the surface of the photoresist film away from the rigid substrate. After the heat release stamp and the photoresist film make conformal contact, the photoresist film is peeled off from the surface of the rigid substrate and transferred to the surface of the pre-stretched substrate using the heat release stamp. The heat release stamp is then released to obtain a pre-stretched flexible substrate with a photoresist film. Thin film deposition: A functional material layer is obtained by depositing a functional material on the surface of the photoresist film on the pre-stretched flexible substrate; Peeling: An adhesive layer is covered on the surface of the pre-stretched flexible substrate where the functional material layer is located. After the functional material on the surface of the photoresist film and the adhesive layer make conformal contact, the adhesive layer is peeled off. Releasing the substrate: Releasing the pre-stretching force restores the pre-stretched flexible substrate to its initial state.

2. The method for fabricating sub-10 nanometer gaps on a flexible substrate according to claim 1, characterized in that, The hard substrate includes at least one of silicon, silicon carbide, silicon oxide, silicon nitride, quartz, diamond, and TCO.

3. The method for fabricating sub-10 nanometer gaps on a flexible substrate according to claim 1, characterized in that, The photoresist includes a positive photoresist, which includes at least one of polydimethylsiloxane, ZEP photoresist, and AR-P photoresist. And / or, the thickness of the photoresist film is 50nm~300nm; And / or, the heat-release stamp includes a heat-responsive adhesive performance switching material, which includes at least one of polydimethylsiloxane and heat-release tape.

4. The method for fabricating sub-10 nanometer gaps on a flexible substrate according to claim 1, characterized in that, The functional materials include metallic or non-metallic materials. The metal includes pure metals or alloys, the pure metals include gold, silver, aluminum, titanium, chromium, nickel or copper, and the alloys include at least one of aluminum alloys, copper alloys and nickel-chromium alloys; The non-metallic material includes at least one of oxides and semiconductor materials, wherein the oxide includes at least one of aluminum oxide, silicon oxide, and titanium oxide, and the semiconductor material includes at least one of silicon and germanium.

5. The method for fabricating sub-10 nanometer gaps on a flexible substrate according to claim 1, characterized in that, The adhesive layer includes at least one of polydimethylsiloxane, high-temperature tape, transparent tape, nano tape, polyvinyl alcohol, AB glue, UV-curable adhesive, ordinary tape, and heat-release tape.

6. The method for fabricating sub-10 nanometer gaps on a flexible substrate according to any one of claims 1 to 5, characterized in that, Before spin-coating photoresist onto the surface of the hard substrate, the hard substrate is surface-treated to obtain a monomolecular anti-adhesion layer, and then the photoresist is spin-coated onto the surface of the monomolecular anti-adhesion layer.

7. The method for fabricating sub-10 nanometer gaps on a flexible substrate according to claim 6, characterized in that, The monomolecular anti-adhesion layer comprises a monomolecular anti-adhesion material, which includes at least one of hexamethyldisilazane, octadecyltrichlorosilane, trichloro(1H,1H,2H,2H-tetrafluoron-octyl)silane, and n-octyltrichlorosilane.

8. The method for fabricating sub-10 nanometer gaps on a flexible substrate according to claim 6, characterized in that, The surface treatment includes the following steps: depositing the monomolecular anti-adhesion layer on the surface of the hard substrate by vapor deposition in a vacuum environment.

9. The method for fabricating sub-10 nanometer gaps on a flexible substrate according to claim 6, characterized in that, The deposition time is 1 min to 20 min, and the deposition temperature is 25℃ to 300℃; the deposition amount of the monomolecular anti-adhesion layer is 100 µL to 1 ml.

10. A flexible substrate, characterized in that, The flexible substrate has a sub-10 nanometer gap, which is prepared by the method described in any one of claims 1 to 9 for preparing a sub-10 nanometer gap on a flexible substrate.

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