A method for forming a micro-nano cavity structure

Abstract

The present invention provides a method for forming a micro-nano cavity structure, belonging to the field of micro-nano structure manufacturing. A cavity structure is formed on a surface to be formed by laser direct writing technology. A plurality of through holes are formed on the surface of the cavity structure, and the through holes communicate between the cavity and the external environment. A closed structure is formed on the outer surface of the cavity structure by laser direct writing technology, and the closed structure is attached to the outer surface of the cavity structure, and the closed structure simultaneously closes the plurality of through holes. By first forming a cavity structure with holes and then forming a closed structure on the surface of the cavity structure to cover the through holes, high-precision three-dimensional structure forming of the micro-nano cavity can be realized. This forming method enables the structural design of the cavity to have extremely high freedom and greatly reduces the difficulty of cavity forming.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano structure manufacturing, and particularly relates to a method for forming a micro-nano cavity structure. Background Art

[0002] A cavity is a micro-nano structure widely used in the sensing field. The enclosed environment formed by the air layer can significantly improve the detection sensitivity and working stability of the sensor. For example, in the field of fiber optic sensing, a cavity is provided at the end of the optical fiber to form optical interference; when light waves enter the cavity and are reflected at both ends thereof, the phase difference between the reflected light waves changes with the change of the cavity length, thereby forming interference fringes that can be used for signal detection. In the field of ultrasonic detection, the cavity has a reflection and resonance effect on sound waves; after ultrasonic waves enter the cavity and are reflected inside it, the phase and amplitude changes of the reflected waves can be used to measure the characteristics of the sound waves. By reducing the volume of the cavity structure, higher integration can be achieved, making the sensor device more miniaturized and facilitating integration into complex systems. Therefore, improving the processing accuracy and forming freedom of the cavity structure and developing a new micro-nano cavity encapsulation process are of great significance for the research in related fields.

[0003] Currently, the processing of cavity structures is mainly achieved through sacrificial layers. Lithography and selective etching are used to remove the sacrificial materials, thereby forming a cavity inside the enclosed structure. This method is widely used in microelectromechanical systems, but this method is mainly based on two-dimensional planar processes such as lithography and anisotropic etching, and it is difficult to directly achieve complex three-dimensional structures. Although certain three-dimensional structures can be achieved through multiple deposition and etching steps, these steps increase the complexity and difficulty of the process. In addition, there are also methods for preparing micro-nano cavities on optical fibers through methods such as bubble blowing, fusion welding, and stretch discharge. These processing methods can only achieve the processing of a single structure and do not have the ability to three-dimensionally control the shape of the cavity structure.

[0004] It can be seen that the current limitations in realizing the three-dimensional forming and preparation of micro-nano cavity structures mainly include the following problems:

[0005] (1) Limitations in forming methods. The size of micro-nano cavity structures is usually in the micron or even nanometer level, and the requirement for processing accuracy is extremely high. It is difficult to prepare high-precision cavity structures through mechanical alignment or bubble blowing.

[0006] (2) Limitations in processing freedom. Micro-nano processing technologies based on semiconductors, such as electron beam lithography, focused ion beam, and deep reactive ion etching, are usually planar processing methods and are difficult to process structures in three-dimensional space, which limits the forming freedom of the structures.

[0007] In summary, there is currently no effective method that can realize the preparation and encapsulation of three-dimensional micro-nano cavity structures. Summary of the Invention

[0008] In view of this, the present invention provides a method for forming a micro-nano cavity structure, which solves the problems of the existing forming method limitations and processing freedom limitations in realizing the three-dimensional forming and preparation technology of the micro-nano cavity structure.

[0009] The technical solution of the present invention is realized as follows: The present invention provides a method for forming a micro-nano cavity structure, including the following steps. Step 1, a cavity structure is formed on a surface to be formed by laser direct writing technology. A cavity is provided inside the cavity structure, and a plurality of through holes are provided on the surface of the cavity structure, and the through holes communicate between the cavity and the external environment. Step 2, a closed structure is formed on the outer surface of the cavity structure by laser direct writing technology. The closed structure is attached to the outer surface of the cavity structure, and the closed structure simultaneously closes a plurality of through holes.

[0010] On the basis of the above technical solution, preferably, in Step 1, after the cavity structure is formed, surface treatment is performed on the surface of the cavity structure where the through holes are provided, and a modified layer is formed. The modified layer improves the adhesion of the outer surface of the cavity structure.

[0011] More preferably, the thickness of the modified layer is 5-50 nm.

[0012] On the basis of the above technical solution, preferably, in Step 2, after the closed structure is formed, surface treatment is performed on the outer surfaces of the cavity structure and the closed structure, and a reinforcing layer is formed. The reinforcing layer improves the sealing performance of the cavity structure.

[0013] On the basis of the above technical solution, preferably, the shapes and inner diameters of the plurality of through holes are different from each other.

[0014] More preferably, the through holes are polygons or ellipses.

[0015] More preferably, the inner diameter of the through hole is not greater than 10 μm.

[0016] On the basis of the above technical solution, preferably, the outer contour of the cavity structure is columnar or spherical.

[0017] More preferably, when the cavity structure is columnar, one end of the cavity structure along the vertical direction of the surface to be formed is an end face, the wall surface of the cavity structure surrounding the vertical direction of the surface to be formed is an outer peripheral wall, and a plurality of through holes are provided on the end face or the outer peripheral wall.

[0018] On the basis of the above technical solution, preferably, the surface to be formed is the end face of the optical fiber of the optical fiber sensor.

[0019] The method for forming a micro-nano cavity structure of the present invention has the following beneficial effects compared with the prior art:

[0020] (1) The present invention first forms a cavity structure with holes, and then forms a closed structure on the surface of the cavity structure to cover the through holes, which can achieve the high-precision three-dimensional structure forming of micro-nano cavities. This forming method enables the structural design of the cavity to have extremely high degrees of freedom and greatly reduces the difficulty of cavity forming.

[0021] (2) A modified layer is provided on the surface of the cavity structure of the present invention, which can greatly improve the bonding strength between the surface of the cavity structure and the closed structure. Then, by providing a reinforcing layer on the outer surface of the cavity mechanism, the reinforcing layer fills the gap between the closed structure and the outer surface of the cavity structure in contact, greatly improving the sealing performance of the cavity structure after forming, realizing the anti-liquid intrusion design and encapsulation method of the cavity structure, and through the structural design of different through hole inner diameters and shapes and surface tension control, effectively sealing the air layer and reducing the encapsulation difficulty of the micro-nano cavity structure.

[0022] (3) The micro-nano cavity structure forming method proposed by the present invention can be flexibly adapted to devices such as optical fibers, thereby reducing the integration difficulty of sensor devices and increasing the degree of freedom of sensor function design. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0024] Figure 1 It is a schematic cross-sectional view of the micro-nano cavity structure of the forming method of the present invention;

[0025] Figure 2 It is a schematic cross-sectional view of the micro-nano cavity structure of another embodiment of the forming method of the present invention;

[0026] Figure 3 It is a schematic three-dimensional view of the micro-nano cavity structure of the forming method of the present invention;

[0027] Figure 4 It is a schematic three-dimensional view of the micro-nano cavity structure of another embodiment of the forming method of the present invention;

[0028] Figure 5 It is a diagram of the optical and scanning electron microscopy characterization results of the micro-nano cavity structure of the forming method of the present invention;

[0029] Figure 6 It is a schematic cross-sectional view of the optical microscopy characterization results of the micro-nano cavity structure of the forming method of the present invention after magnetron sputtering coating surface treatment;

[0030] Figure 7 Schematic cross-sectional view of the optical and scanning electron microscopy characterization results after the micro-nano cavity structure of the forming method of the present invention is blocked by a closed structure;

[0031] Figure 8 Schematic diagram of the working principle of an optical fiber sensor based on a micro-nano cavity structure of the present invention;

[0032] Figure 9 Graph showing the comparison results of the sensing signal stability of an optical fiber sensor based on a micro-nano cavity structure of the present invention when using an unblocked and a blocked structure;

[0033] In the figure: 1, cavity structure; 101, cavity; 102, through hole; 2, closed structure; 3, modified layer; 4, reinforcing layer. Detailed implementation manners

[0034] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than 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 efforts shall fall within the protection scope of the present invention.

[0035] As Figure 1 shown, in combination with Figure 2 and Figure 3 , a forming method of a micro-nano cavity structure of the present invention includes the following steps:

[0036] Step 1: A cavity structure 1 is formed on a surface to be formed by laser direct writing technology. The cavity structure 1 can be prepared from different types of materials, and the material is determined by the photoresist used in the laser direct writing process. The material used can be acrylate photoresist, epoxy resin photoresist, hydrogel precursor, metal particle solution precursor, etc. A cavity 101 is provided inside the cavity structure 1. For example, in this embodiment, the surface to be formed is the end face of an optical fiber. The preset axis is the axis of the optical fiber extension direction. The outer contour of the cavity structure 1 in this embodiment is centrally symmetrical around a preset axis. The preset axis is perpendicular to the surface to be formed. A plurality of through holes 102 are provided on the surface of the cavity structure 1 around the axial direction of the cavity structure 1. The through holes 102 are connected between the cavity 101 and the external environment. The function of the through holes 102 is to allow the photoresist to flow out of the cavity structure 1 in the development step after laser direct writing. Laser direct writing refers to a micro-nano processing method based on the principle of two-photon polymerization. The laser used is an ultrafast laser, such as picosecond laser, femtosecond laser, etc. Laser direct writing is achieved through the linkage of a scanner and a displacement stage. The scanner can be a galvanometer, a rotating mirror, and an acousto-optic scanner, etc. The displacement stage can achieve high-precision movement based on piezoelectric, ball screw, double cross ball, etc. When forming the cavity mechanism 1, the cavity structure 1 needs to meet the forming conditions of the microporous structure and the mechanical properties of the structure at the same time. The structure will not collapse due to mechanical instability before and after processing; the size and structure of the through hole 102 are determined according to the material forming process, and the minimum formable parameters and structural dimensions are determined by parameter scanning.

[0037] In addition, if Figure 4 As shown, the through holes 102 on the surface of the cavity structure 1 may also be opened on the end face and the outer peripheral wall of the cavity structure 1 at the same time. In this case, the closed structure 2 needs to be formed on the end face and the outer peripheral wall of the cavity structure 1 at the same time to form an irregular shaped structure, which can be a ring or a broken ring. It is only required to close all the through holes 102 at the same time.

[0038] Specifically, laser direct writing uses polydimethylsiloxane (PDMS)-based photoresist as the material to make the cavity structure 1. The light source used for laser direct writing is a femtosecond laser with a wavelength of 780nm, a pulse width of 80fs, and a laser power of 25mW. A galvanometer is used as a laser scanner, and a piezoelectric displacement stage is used for high-precision motion control during the processing process. The scanning speed of the femtosecond laser focus is 10mm / s.

[0039] During processing, the PDMS photoresist is dropped onto the glass substrate, and the objective lens is adjusted to obtain the best focus to ensure that the focus of the femtosecond laser system is precisely aligned with the substrate surface. According to the processing path file, the femtosecond laser is used to scan the photoresist layer by layer along the predetermined path, and a chain polymerization reaction is induced at the tightly focused laser through two-photon absorption, thereby realizing the processing of three-dimensional structures. After the processing is completed, the sample processed by the laser is immersed in the developing solvent to remove the photosensitive resin that has not undergone polymerization reaction, leaving the cured three-dimensional structure. Secondary curing with UV light is carried out according to experimental requirements to improve the mechanical strength and surface stability of the structure. The structure is characterized using an optical microscope and an electron microscope to confirm whether the processed structure meets the design requirements; the morphological characteristics of the cavity structure 1, such as Figure 5 as shown. The cavity structure 1 obtained after processing has the structural characteristics of a central cavity 101 and several through holes 102.

[0040] Step two, a closed structure 2 is formed on the outer surface of the cavity structure 1 around the axis of the cavity structure 1 by laser direct writing technology. The closed structure 2 adheres to the outer surface of the cavity structure 1, and the closed structure 2 simultaneously closes several through holes 102. The width dimension of the closed structure 2 needs to be slightly larger than that of the through hole 102 to achieve the plugging of the through hole 102.

[0041] Specifically, the acrylate-based photoresist IP-S is used as the material to make the closed structure 2. The closed structure 2 covers and closes the through hole 102, thereby forming a closed and sealed cavity structure 1. The thickness of the closed structure for plugging the PDMS thin film cavity structure is 2 μm. When processing with a 20× objective lens (NA 0.8), the laser power is 32.5 mW, the scanning speed is 100 mm / s, the slice filling line spacing is 300 nm, and the scanning layer spacing is 500 nm, as Figure 5 . By comparing the microscopic optical and electron microscope images before and after processing, it is confirmed whether the through hole 102 is indeed filled and plugged by the formed closed structure 1 to form an overall composite material structure; at this time, the air layer in the internal cavity 101 will show a bright color under the optical microscope for judgment. The closed structure 2 reduces the time and alignment difficulty for individually processing and plugging each through hole 102, thereby improving the processing efficiency and plugging success rate of the overall structure.

[0042] In Figure 1In a preferred embodiment shown, in step one, after forming the cavity structure 1, surface treatment is carried out on the surface of the cavity structure 1 where the through hole 102 is opened, and a modified layer 3 is formed. The function of the modified layer 3 is to enhance the adhesion of the outer surface of the cavity structure 1, thereby enhancing the connection strength between the closed structure 2 and the cavity structure 1. The modified layer 3 is a physical deposition coating, so physical vapor deposition technology can be used for processing; physical vapor deposition technology is to convert materials from solid state to vapor state by physical methods and then condense on the substrate to form a thin film. The modified layer 3 can use deposition films of materials such as indium tin oxide (ITO), titanium dioxide (TiO2), silicon dioxide (SiO2), or gold. Chemical surface modification uses the solution immersion method to control the surface hydrophilicity and hydrophobicity of the formed structure, and uses silane coupling agents to improve the surface adhesion of polymers. Silane coupling agents are silane reagents such as trimethoxysilane, triethoxysilane, triisopropoxysilane, such as methyl acrylate trimethoxysilane, vinyl triethoxysilane, or isopropyl acrylate triisopropoxysilane.

[0043] In Figure 1 In a preferred embodiment shown, the thickness of the modified layer 3 is 5 - 50 nm. Specifically, in the present invention, an ITO thin film is deposited on the surface of the cavity structure 1 using a physical vapor deposition method based on magnetron sputtering to form the modified layer 3. Since PDMS is a hydrophobic material, it is difficult to perform secondary laser direct writing processing of other structures on the surface of the formed cavity structure 1 made of PDMS. ITO films usually have a relatively high surface energy and hydrophilicity. After plating it on the PDMS surface, the surface of the PDMS structure can exhibit strong hydrophilicity. At the same time, the ITO film can serve as a reflection interface to improve the spectral resolution. During the magnetron sputtering process, high-purity argon gas is used as the working gas, and a voltage difference is formed between the target and the substrate by a DC power supply. Argon ions are accelerated by the electric field and hit the surface of the target, sputtering indium tin oxide from the surface of the target and depositing it on the surface of the opposite optical fiber to form a thin film. The process parameters used in this article are: the DC power supply power is set to 80 W, the working voltage is 335 V, the working current is 233 mA, the argon gas flow rate is 10 SCCM, and the coating time is 5 min. A layer of ITO metal film with a thickness of about 5 nm is deposited on the surface of the target PDMS microcavity structure. As Figure 5 shown, the thickness of the modified layer 3 is adjusted according to the design requirements of different types and different preparation materials of the cavity structure 1. After the modified layer 3 is formed, the color characteristic changes of the cavity structure 1 can be observed through an optical microscope. The surface of the PDMS cavity structure 1 after coating shows thin film interference colors, as Figure 5 shown in (b).

[0044] In Figure 1In a preferred embodiment shown, in step two, after forming the closed structure 2, surface treatment is performed on the outer surfaces of the cavity structure 1 and the closed structure 2, and a reinforcing layer 4 is formed. The reinforcing layer 4 improves the sealing performance of the cavity structure 1. The formation of the reinforcing layer 4 can be achieved by depositing a coating layer or attaching a thin film layer. The deposition coating method uses physical or chemical deposition to deposit the reinforcing layer 4 on the surface of the micro-nano cavity structure 1; metals or metal oxide layers are used to achieve good chemical stability and sealing performance. The attachment method of the reinforcing layer 4 uses thermal spraying or coating encapsulation methods to form a uniform polymer layer on the surface of the cavity structure 1, and the polymer is used to fill the tiny gaps between the contact surfaces of the closed structure 2 and the cavity structure 1, thereby providing good sealing performance. By modifying or coating the surface of the micro-nano cavity structure 1, the adhesion of the cavity structure 1 to different interfaces can be improved, thereby providing an effective anti-liquid intrusion design for the micro-nano cavity structure 1.

[0045] Specifically, the hydrogel coating encapsulation method can be used to form a gel coating on the surface of the cavity structure 1 as the reinforcing layer 4, and the surface gel structure is used to fill the tiny gaps of the formed structure, thereby providing better sealing performance. The hydrogel material used is polyethylene glycol diacrylate (PEGDA), and 0.1% wt of methylene blue is doped in the gel as a photoinitiator. The PEGDA solution is formed into a thin film with a thickness of 5 μm by spin coating, and a hydrogel film is formed after UV photopolymerization. Subsequently, the formed hydrogel is covered on the surface of the blocked cavity structure 1 to form a micro-nano cavity structure 1 encapsulated with the reinforcing layer 4 of the hydrogel coating.

[0046] In Figure 3 In a preferred embodiment shown, the shapes and inner diameters of several through holes 102 are different. By optimizing the structure of the through holes 102 on the surface of the cavity structure 1, it is designed that the surface micropores of the cavity structure 1 are composed of through holes 102 with different sizes and structures, and the surface tension of the solution is controlled by the cooperation of the structures and sizes of different through holes 102, thereby realizing the anti-liquid intrusion of the cavity structure 1 by using the surface tension of the liquid.

[0047] In Figure 3 In a preferred embodiment shown, the through hole 102 is polygonal or elliptical, preferably square, circular, or triangular, and it is preferred that the minimum tension angle of the liquid surface is greater than the minimum angle for the liquid to enter the cavity 101.

[0048] In Figure 3 In a preferred embodiment shown, the inner diameter of the through hole 102 is not greater than 10 μm, otherwise it is difficult to meet the requirements of the minimum tension angle of the liquid surface.

[0049] In Figure 2In a preferred embodiment shown, the outer contour of the cavity structure 1 is a column or a sphere. The cavity 101 can also be designed to be square, circular or any geometric shape; when the cavity structure 1 is a column, it is beneficial to design the height of the air layer of the cavity 101 inside it to be adjustable according to needs.

[0050] exist Figure 2 In a preferred embodiment shown, when the cavity structure 1 is in the shape of a column, one end of the cavity structure 1 along its axial direction is an end face, the wall surface of the cavity structure 1 surrounding its axial direction is an outer peripheral wall, and a plurality of through holes 102 are evenly arranged on the end face or the outer peripheral wall. The annularly distributed through holes 102 can enhance the structural symmetry and structural strength of the cavity structure 1.

[0051] exist Figure 8 and Figure 9 In a preferred embodiment shown, the surface to be molded is the end face of the optical fiber of the optical fiber sensor, and the micro-nano cavity structure 1 is used to detect the physical signal. The optical fiber sensor is a micro-detector based on the principle of interference or resonance. By processing different types of micro-nano cavity structures 1, the detection capability of different physical signal changes, such as temperature, pressure, flow rate and sound waves, etc., can be realized; for example, the sensor based on the interference effect detects the change of the interference fringes to detect the change of the tiny physical quantity, such as pressure, temperature, flow rate and sound waves, etc.; or, the sensor based on the resonance effect detects the change of the resonant wavelength to detect the change of the environment. The sensitivity of the sensor is related to the thickness of the thin film cavity 101. In addition, a focusing lens can be integrated on the surface of the cavity structure 1 for collecting the detection signal to enhance the detection sensitivity and test stability of the detection signal; or a signal amplifier can be integrated on the surface of the cavity structure 1 to enhance the contrast of the detection signal.

[0052] Specifically, this embodiment provides a use of a micro-nano cavity structure 1 for an optical fiber sensor, and a sensor working method based on the interference principle, such as Figure 8 As shown in (a), combined with Figure 7, the light Iin emitted by the light source S301 is transmitted to the fiber end face after passing through the circulator S302, where refraction and reflection occur. The light source exits from the fiber end face, and the fiber end face forms the first reflecting surface S303 of the FP interference cavity and forms the reflected light I1; the transmitted part of the light beam reaches the second reflecting surface S304 and is reflected to form the reflected light I2. The light beam undergoes multiple reflections and transmissions within the FP cavity. I1 and I2 interfere with each other when they return to form an interference waveform, and then the circulator transmits the output light Iout formed after interference to the detector S305 for analysis. When the signal to be measured changes and causes changes in the structural parameters of the FP cavity, such as changes in the optical thickness of the cavity or the effective refractive index of the medium within the cavity, the phase difference between I1 and I2 will change, resulting in an offset Δλ of the interference spectrum. This offset is detected and analyzed by the detector S305, thereby obtaining information about the detection signal, such as Figure 8 shown in (b) of. By comparing the differences in the sensing signal stability between the unsealed structure and the sealed structure of the sensor in this embodiment, it can be found that when the cavity structure 1 is open, water will enter the cavity 101 during the liquid-phase environment measurement process, resulting in a change in the refractive index within the cavity 101; at the same time, the presence of the water interface will cause perturbations, resulting in spectral signal offsets and affecting the detection stability. After sealing the cavity structure 1, an air layer is formed within the FP interference cavity, and the internal medium of the cavity 101 does not change after being immersed in the solution, thereby improving the working stability of the detector. As Figure 9 shown in (a) of, there are significant random offsets in the reflection spectrum of the open cavity structure 1 in the water environment, and the wavelength change of the interference spectrum trough is 0.84 nm; in contrast, as Figure 9 shown in (b) of, the spectral stability of the sealed cavity structure 1 is significantly better, and the wavelength change of the interference spectrum trough is only 0.06 nm. Therefore, through the multi-step laser direct writing and surface treatment process proposed in the present invention, the stability of the fiber optic sensor during underwater operation can be effectively improved.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for forming a micro-nano cavity structure, characterized in that: The following steps are involved: Step 1: forming a cavity structure (1) on a surface to be formed by laser direct writing technology, wherein the surface to be formed is the optical fiber end face of the optical fiber sensor, wherein a cavity (101) is provided inside the cavity structure (1), and a plurality of through holes (102) are provided on the surface of the cavity structure (1), wherein the through holes (102) are connected between the cavity (101) and the external environment; after forming the cavity structure (1), performing surface treatment on the surface of the cavity structure (1) with the through holes (102) and forming a modified layer (3), wherein the modified layer (3) improves the adhesion of the outer surface of the cavity structure (1); Step 2: forming a closed structure (2) on the outer surface of the cavity structure (1) by laser direct writing technology; the closed structure (2) is attached to the outer surface of the cavity structure (1); and the closed structure (2) simultaneously closes a plurality of through holes (102).

2. The method for forming a micro-nano cavity structure according to claim 1, characterized in that: The thickness of the modified layer (3) is 5-50 nm.

3. The method for forming a micro-nano cavity structure according to claim 1, characterized in that: In the second step, after the closed structure (2) is formed, surface treatment is performed on the outer surfaces of the cavity structure (1) and the closed structure (2) to form a reinforcement layer (4), wherein the reinforcement layer (4) improves the sealing performance of the cavity structure (1).

4. The method for forming a micro-nano cavity structure according to claim 1, characterized in that: The shapes and inner diameters of the plurality of through holes (102) are different.

5. The method for forming a micro-nano cavity structure according to claim 4, characterized in that: The through hole (102) is polygonal or elliptical.

6. The method for forming a micro-nano cavity structure according to claim 4, characterized in that: The inner diameter of the through hole (102) is no greater than 10 μm.

7. The method for forming a micro-nano cavity structure according to claim 1, characterized in that: The outer contour of the cavity structure (1) is column-shaped or spherical.

8. The method for forming a micro-nano cavity structure according to claim 7, characterized in that: When the cavity structure (1) is in the shape of a column, one end of the cavity structure (1) in the vertical direction of the surface to be formed is an end face, the wall surface of the cavity structure (1) in the vertical direction surrounding the surface to be formed is an outer peripheral wall, and the plurality of through holes (102) are arranged on the end face or on the outer peripheral wall.

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