A graphene structure beyond the diffraction limit and a dual-beam lithography method and application
Through dual-beam laser lithography technology, graphene oxide is lithographed using annular reducing beam and spherical oxidation beam, LSG pattern manufacturing exceeding the diffraction limit is achieved, and the problem of limited size parameters of graphene pattern lithography in the prior art is solved, and the production of high-specific capacity supercapacitor electrodes is realized.
Patent Information
- Application Number
- CN202210992808.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-08-18
- Publication Date
- 2025-04-25
- Estimated Expiration
- 2042-08-18
AI Technical Summary
The prior art is difficult to achieve graphene pattern lithography beyond the diffraction limit, especially in the manufacturing of high-performance supercapacitor electrodes.
Using dual-beam laser lithography technology, graphene oxide is reduced by the first beam of writing beam, and the second beam of femtosecond laser oxidizes high-reducing graphene oxide to achieve an LSG pattern with a minimum line width of 90nm.
The LSG pattern that exceeds the diffraction limit was successfully manufactured to make high-specific capacity supercapacitor electrodes with a specific capacity of up to 308F/g.
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Figure CN115390366B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of ultra-fine graphene lithography, and in particular to a graphene structure beyond the diffraction limit and a double-beam lithography method and application thereof. Background Art
[0002] Graphene is a layered structure of carbon atoms tightly packed in a two-dimensional honeycomb lattice with extraordinary electrical, optical and mechanical properties. Patterned graphene structures have been shown to significantly improve the performance of devices, including energy storage, holography, sensors and tribo-nanoelectric generation. Among the various graphene-based materials, graphene oxide (GO) is a graphene skeleton decorated with epoxide, carbonyl, hydroxyl and phenol functional groups. Its patterning has aroused great interest among researchers in this field.
[0003] The traditional manufacturing method for patterned GO devices is to generate a GO aqueous suspension through the interaction of graphite with strong oxidants and acids, and then obtain a GO film through spin coating, drop casting, freezing, drying and other steps, and then use a single-beam laser scribing program to photolithography the GO film. The surface functional groups of GO are eliminated by laser, and the GO film is reduced to a laser-scribed graphene (LSG) pattern, where the accuracy of photolithography determines the size parameters of the pattern, and then determines the surface area and performance of the device. However, the line width of the LSG pattern manufactured by a single-beam path that has been reported in research is in the micron level. It is a huge challenge to achieve size parameters of LSG patterns that exceed the diffraction limit, which is the key to achieving breakthroughs in device performance.
[0004] In recent years, related studies have reported a dual-beam laser scribing technology, which introduces a second annular beam into the lithography system to suppress the photopolymerization reaction triggered by the first writing beam, and produces a resin pattern with a line width far exceeding the diffraction limit. However, for graphene lithography, there is currently no suppression method for GO laser reduction, nor has the lithography technology for LSG patterns with size features beyond the diffraction limit been developed. Summary of the invention
[0005] In response to the above-mentioned technical problems, the present invention provides a graphene structure that exceeds the diffraction limit and a dual-beam lithography method thereof. The first writing beam is used to reduce GO to highly reduced graphene oxide, and the second femtosecond laser is used to oxidize the highly reduced graphene oxide, thereby achieving an LSG pattern with a minimum line width of 90nm. This LSG pattern that exceeds the diffraction limit can be used to make electrodes for supercapacitors with a specific capacity of up to 308F / g.
[0006] To achieve the above object, the present invention provides a dual-beam lithography method for graphene structures beyond the diffraction limit, comprising:
[0007] Preparation of graphene oxide film: using graphite powder to obtain a graphene oxide suspension by Hummers method, and then spin coating the graphene oxide suspension on a PET film to prepare a graphene oxide film;
[0008] Double-beam laser lithography: A double-beam laser lithography system including an annular reduction beam and a spherical oxidation beam is used to perform photolithography on the graphene oxide film.
[0009] In the above scheme, the spin coating thickness of the graphene oxide suspension is 100 to 1000 nm.
[0010] In the above scheme, the spin coating speed of the graphene oxide suspension is 100 to 300 rpm.
[0011] In the above scheme, the annular reduction light beam and the spherical oxidation light beam are concentric and controlled simultaneously.
[0012] In the above solution, the outer diameter of the annular reduction light beam is larger than the diameter of the spherical light beam.
[0013] In the above scheme, the annular reduction light beam is emitted by a continuous wave mode laser with a wavelength of 300 to 400 nm, and the spherical oxidation light beam is emitted by a femtosecond laser with a wavelength of 300 to 550 nm.
[0014] In the above solution, the laser power of the continuous wave mode laser is not greater than 12 mW, and the laser power of the femtosecond laser is not greater than 18 mW.
[0015] In the above solution, the scanning speed of the continuous wave mode laser is 1 to 30 μm / s, and the scanning speed of the femtosecond laser is 1 to 30 μm / s.
[0016] In the above scheme, the photolithography system includes a confocal detector photomultiplier tube, which is used for alignment and beam overlap of the annular reduction beam and the spherical oxidation beam.
[0017] In the above solution, the numerical aperture of the objective lens used in the photolithography system is 1.4.
[0018] The second aspect of the present invention provides a graphene structure prepared by the dual-beam lithography method of the graphene structure beyond the diffraction limit.
[0019] A third aspect of the present invention provides an application of a graphene structure prepared by a dual-beam lithography method for a graphene structure beyond the diffraction limit, which is used for assembling a supercapacitor.
[0020] Beneficial effects of the present invention: The present invention uses an annular reduction beam and a spherical oxidation beam to simultaneously perform photolithography on a graphene oxide film, thereby being able to produce a refined parallel linear pattern that exceeds the diffraction limit and achieve an LSG pattern with a minimum line width of 90 nm. By controlling the laser power and scanning speed of the dual beams, LSG parallel patterns with different average line widths and average spacings can be produced. The pattern can be used to make electrodes for supercapacitors, and the specific capacity thereof can reach up to 308 F / g. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 1 is a graph showing the relationship between the intensity ratio and the laser power during the laser-driven reduction of graphene oxide and the LSG oxidation in Example 1: (a) is the first reduction; (b) is the oxidation; and (c) is the second reduction.
[0022] Figure 2 The graphene with a lithography beyond the diffraction limit of Example 1 is:
[0023] (a) is the relationship between the LSG line width and the laser power of the reduction beam, and the inset in (a) is the SEM image of the LSG line corresponding to position ①, and the scale bar in the SEM image is 1μm;
[0024] (b) is the relationship between LSG and OLSG and the laser power of the oxidation beam, and the SEM images corresponding to positions ② and ③ in the figure, respectively. The scale bar in the SEM image is 1 μm;
[0025] (c) and (d) are the gray value distribution diagrams across the cross section in the SEM images corresponding to positions ② and ③ in Figure (b);
[0026] (e) and (f) are the AFM height distributions corresponding to positions ② and ③ in Figure (b), respectively.
[0027] Figure 3 The graphene with a lithography beyond the diffraction limit of Example 2 is:
[0028] (a) is the relationship between the LSG line width and the laser power of the reduction beam, and the inset in (a) is the SEM image of the LSG line corresponding to position ①, and the scale bar in the SEM image is 1μm;
[0029] (b) is the relationship between LSG and OLSG and the laser power of the oxidation beam, and the SEM images corresponding to positions ② and ③ in the figure, respectively. The scale bar in the SEM image is 1 μm;
[0030] Figure 4 SEM images of LSG patterns obtained by lithography at different laser powers, with a scale of 500 nm.
[0031] Figure 5 is based on Figure 4 Capacitance performance test results of electrodes manufactured with different LSG patterns. DETAILED DESCRIPTION
[0032] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0033] To achieve the above purpose, the technical solution adopted by the present invention is as follows:
[0034] The present invention provides a dual-beam lithography method for graphene structures beyond the diffraction limit, comprising:
[0035] Preparation of graphene oxide film: using graphite powder to obtain a graphene oxide suspension by Hummers method, and then spin coating the graphene oxide suspension on a PET film to prepare a graphene oxide film;
[0036] Double-beam laser lithography: A double-beam laser lithography system including an annular reduction beam and a spherical oxidation beam is used to perform photolithography on the graphene oxide film.
[0037] The present invention does not impose any special restrictions on the source of the graphite powder, which can be purchased commercially.
[0038] In some embodiments, the Hummers method is specifically as follows: graphite, sodium nitrate and concentrated nitric acid are mixed in a weight ratio of 2:1:100 under stirring, and then 0.2 to 5 parts of potassium permanganate are added, and then 5 to 10 parts of hydrogen peroxide are added at 98°C, and a graphene oxide suspension is obtained after centrifugation.
[0039] In some embodiments, the spin coating thickness of the graphene oxide suspension is 100-1000 nm.
[0040] Spin coating that is too thin may result in discontinuous film layers, while too thick may prevent the laser from performing sufficient reduction or oxidation.
[0041] Preferably, the spin coating thickness of the graphene oxide suspension is 200-850 nm.
[0042] In some embodiments, the spin coating speed of the graphene oxide suspension is 100 to 300 rpm.
[0043] Preferably, the spin coating speed of the graphene oxide suspension is 200 rpm.
[0044] In some embodiments, the PET film has a thickness of 0.1 to 0.5 mm.
[0045] Preferably, the thickness of the PET film is 0.2 mm.
[0046] Furthermore, an Au layer with a thickness of 80 to 120 nm, preferably 100 nm, is thermally deposited on the PET film to form a circuit when the electrode is subsequently made. The Au layer can be deposited along the edge of the PET film or in a certain area of the PET film, as long as it can form a stable circuit after being made into an electrode.
[0047] The pressure used in the thermal deposition of the Au layer is less than 1×10 -4 Pa.
[0048] In some embodiments, the annular reducing beam and the spherical oxidizing beam are concentric and controlled simultaneously.
[0049] In some embodiments, the outer diameter of the annular reduction beam is greater than the diameter of the spherical beam.
[0050] The annular reduction beam and the spherical oxidation beam are concentric and controlled simultaneously, and the outer diameter of the annular reduction beam is larger than the diameter of the spherical beam, so that the graphene oxide is reduced to LSG by the first half of the reduction beam, and the spherical beam converts the middle part of the LSG line into oxidized LSG (OLSG), dividing the LSG line into two lines with a width exceeding the diffraction limit. Due to the interlayer expansion of graphene oxide caused by the photothermal effect, the OLSG undergoes a slight reduction change during the reduction of the second half of the annular beam, so that an ultra-fine LSG / OLSG / LSG parallel line pattern can be produced.
[0051] In some embodiments, the annular reduction beam is emitted by a continuous wave mode laser with a wavelength of 300-400 nm, and the spherical oxidation beam is emitted by a femtosecond laser with a wavelength of 300-550 nm.
[0052] Preferably, the annular reduction light beam is emitted by a continuous wave mode laser with a wavelength of 375 nm, and the spherical oxidation light beam is emitted by a femtosecond laser with a wavelength of 532 nm.
[0053] The wavelengths of the annular reduction beam and the spherical oxidation beam used in the present application are relatively short, and can generate relatively large laser energy, thereby ensuring the reduction and oxidation effects during the dual-beam lithography process.
[0054] In some embodiments, the laser power of the continuous wave mode laser is no greater than 12 mW, and the laser power of the femtosecond laser is no greater than 18 mW.
[0055] In some embodiments, the scanning speed of the continuous wave mode laser is 1 to 30 μm / s, and the scanning speed of the femtosecond laser is 1 to 30 μm / s.
[0056] Preferably, the scanning speed of the continuous wave mode laser is 10 μm / s, and the scanning speed of the femtosecond laser is 10 μm / s.
[0057] The applicant found in the study that the laser power and scanning speed will affect the pattern of graphene oxide during the reduction and oxidation process. Using a continuous wave mode laser with a wavelength of 375nm and controlling the laser parameters under the conditions of laser power not exceeding 12mW and scanning speed of 10μm / s can ensure that the annular light beam can produce a good reduction effect and avoid ablation of the graphene oxide film. At the same time, using a femtosecond laser with a wavelength of 532nm and controlling the laser parameters under the conditions of laser power not exceeding 18mW and scanning speed of 10μm / s can ensure that graphene oxide can produce a good oxidation effect, thereby obtaining an LSG pattern with an average line width exceeding the diffraction limit and ensuring that the graphene oxide film is not ablated.
[0058] Furthermore, a continuous wave mode laser with a wavelength of 375nm is used to emit a ring-shaped light beam. Specifically, the light beam generated by the laser is expanded after passing through a half-wave plate, and is modulated by a vortex phase plate to produce a focus profile with zero intensity at the center of the focus area, further generating a laser beam with a ring-shaped cross section.
[0059] In some embodiments, the photolithography system includes a confocal detector photomultiplier tube for alignment and beam overlap of the annular reduction beam and the spherical oxidation beam.
[0060] Furthermore, the annular reduction beam and the spherical oxidation beam are concentrically arranged, and the exposure is controlled by a synchronous shutter and monitored by a charge coupled device camera.
[0061] In some embodiments, the numerical aperture of the objective lens used in the lithography system is 1.4. Introducing a high numerical aperture objective lens in the lithography system of the present application, especially when the numerical aperture is 1.4, can reduce the cross-sectional area of the light beam, which is conducive to obtaining an LSG pattern with a smaller line width that exceeds the diffraction limit.
[0062] The second aspect of the present invention provides a graphene structure prepared by the dual-beam lithography method of the graphene structure beyond the diffraction limit.
[0063] A third aspect of the present invention provides an application of a graphene structure prepared by a dual-beam lithography method for a graphene structure beyond the diffraction limit, which is used for assembling a supercapacitor.
[0064] Example 1
[0065] This embodiment provides a dual-beam lithography method for a graphene structure beyond the diffraction limit, comprising:
[0066] S1. Preparation of graphene oxide film: using graphite powder to obtain a graphene oxide suspension by Hummers method, and then spin coating the graphene oxide suspension on a PET film with a thickness of 0.2 mm and a thermally deposited 100 nm Au layer at a speed of 200 rpm to obtain a spin-coated graphene oxide film with a thickness of 200 nm;
[0067] S2. Dual-beam laser lithography: A dual-beam laser lithography system including an annular reduction beam and a spherical oxidation beam is used to perform photolithography on the graphene oxide film obtained in step S1.
[0068] The Hummers method is specifically as follows: graphite, sodium nitrate and concentrated nitric acid are mixed in a weight ratio of 2:1:100 under stirring, and then 3 weight parts of potassium permanganate are added, and then 8 weight parts of hydrogen peroxide are added at 98° C., and a graphene oxide suspension is obtained after centrifugation.
[0069] The outer diameter of the annular reduction beam is larger than the diameter of the spherical beam. The annular reduction beam is emitted by a continuous wave mode laser with a wavelength of 375 nm, and the spherical oxidation beam is emitted by a femtosecond laser with a wavelength of 532 nm.
[0070] A continuous wave mode laser with a wavelength of 375nm is used to emit an annular beam. Specifically, the beam generated by the laser is expanded after passing through a half-wave plate, and is modulated by a vortex phase plate to produce a focus profile with zero intensity at the center of the focus area, further generating a laser beam with a ring-shaped cross section.
[0071] The annular reduction beam and the spherical oxidation beam are concentric and controlled simultaneously. Specifically, the lithography system aligns and overlaps the annular reduction beam and the spherical oxidation beam through a confocal detector photomultiplier tube. The exposure is controlled by a synchronous shutter and monitored by a charge-coupled device camera. At the same time, an objective lens with a numerical aperture of 1.4 is introduced into the lithography system to reduce the cross-sectional area of the beam, which is conducive to obtaining LSG patterns with smaller line width that exceed the diffraction limit.
[0072] Implementation Effect
[0073] 1. Reduction and oxidation effects
[0074] (1) The graphene oxide film with a thickness of 200 nm prepared in step S1 of Example 1 was treated with a continuous wave mode laser of 375 nm at a scanning speed of 10 μm and laser powers of 0, 3 mW, 6 mW, 9 mW, and 12 mW, respectively, and then the Raman spectra of the treated graphene oxide films were measured, and the intensity ratio between the D peak and the G peak was calculated, i.e., I D / I G , which is used to characterize the reduction degree of graphene oxide, and the relationship between the intensity ratio and the laser power is obtained as follows Figure 1 As shown in a.
[0075] Conclusion: Figure 1 (a) It can be seen that when the laser power increases from 6mW to 12mW, its I D / I G It decreases with the increase of laser power, indicating that the reduction degree of graphene oxide gradually increases at this power, and during the experiment, the applicant found that when the laser power is greater than 12 mW, it will cause ablation of the graphene oxide film.
[0076] (2) The graphene oxide film treated with 6 mW, 9 mW, and 12 mW in (1) was then subjected to laser oxidation treatment using a femtosecond laser with a wavelength of 532 nm and a scanning speed of 10 μm / s at laser powers of 0 mW, 3 mW, 6 mW, 9 mW, 12 mW, 15 mW, and 18 mW, respectively. The Raman spectra of the treated reduced graphene oxide film were measured, and the intensity ratio between the D peak and the G peak, i.e., I D / I G , which is used to characterize the oxidation degree of reduced graphene oxide, and the relationship between the intensity ratio and the laser power is obtained as Figure 1 (b) as shown.
[0077] Conclusion: Figure 1 (b) It can be seen that the intensity ratio of graphene oxide reduced by 6 mW will further decrease as the power of the oxidation beam increases, and it will ablate when the power of the oxidation beam is greater than 6 mW; the intensity of graphene oxide reduced by 9 mW will be slightly oxidized at 3 mW and 6 mW as the power of the oxidation beam increases, and then it will be reduced as the laser power increases, and it will ablate when the laser power is greater than 15 mW; the intensity ratio of graphene oxide reduced by 12 mW will increase from 0.29 to 0.86 as the power of the oxidation beam increases, especially from 9 mW to 18 mW, the oxidation degree is more obvious, and it will ablate when the laser power is greater than 18 mW. It also further proves that the 532 nm femtosecond laser can oxidize highly reduced graphene oxide, and the laser range required for oxidation is 6-18 mW.
[0078] (3) The reduced graphene oxide film treated with laser oxidation at a power of 18 mW in (2) was then treated with a continuous wave laser of 375 nm at a scanning speed of 10 μm / s at powers of 0 mW, 3 mW, 6 mW, 9 mW, and 12 mW. The Raman spectra of the treated films were measured, and the intensity ratio between the D peak and the G peak, i.e., I D / I G , which is used to characterize the degree of its second reduction, and the relationship between the intensity ratio and the laser power is obtained as follows Figure 1 (c) as shown.
[0079] Conclusion: Figure 1 (c) It can be seen that as the laser power increases, the intensity ratio decreases slightly. Therefore, the degree of reduction is weaker during the second reduction process, so pattern lithography with a smaller line width can be achieved.
[0080] 2. Graphene structure patterns beyond the diffraction limit
[0081] The graphene oxide film with a thickness of 200 nm prepared in S1 of Example 1 was subjected to dual-beam processing at a scanning speed of 10 μm / s using a ring beam with a laser power of 6-12 mW emitted by a continuous wave laser with a wavelength of 375 nm and a spherical beam with a laser power of 6-18 mW emitted by a femtosecond laser with a wavelength of 532 nm, and the pattern changes during the photolithography process were observed. The results are as follows: Figure 2 As shown in (a) to (f).
[0082] Since the outer diameter of the annular beam is larger than the diameter of the spherical beam, only the annular beam irradiates the film in the early stage. Figure 2 (a) As can be seen, as the laser power of the annular beam increases, the average line width of the LSG pattern increases from 260nm to 420nm, corresponding to Figure 2 (a) ① position; when the oxidation beam is irradiated onto the film, an OLSG can be observed emerging from the middle of the LSG, as shown in Figure 2 As shown in (b) to (d), as the oxidation power increases from 9 mW (i.e., position ②) to 18 mW (i.e., position ③), the average width of the OLSG line increases from 140 nm to 240 nm, and the average width of the LSG increases from 140 nm to 240 nm (the SEM images are shown in Figure 2). Figure 4 structure C) is reduced to 90nm (see its SEM image Figure 4 structure D) and by Figure 2 (e) to (f) demonstrate that the double bundle leads to interlayer expansion of graphene-based films.
[0083] It can be seen that this Example 1 proves that the dual-beam lithography method can be applied to a graphene oxide film with a thickness of 200 nm to obtain a graphene lithography pattern with a size below the diffraction limit.
[0084] Example 2
[0085] This embodiment provides a dual-beam lithography method for graphene structures beyond the diffraction limit. The specific implementation method is the same as that of Embodiment 1, except that the spin coating thickness is 850 nm.
[0086] Implementation Effect
[0087] 1. Graphene structure patterns beyond the diffraction limit
[0088] The graphene oxide film with a thickness of 850 nm prepared in Example 2 was subjected to dual-beam processing at a scanning speed of 10 μm / s using a ring beam with a laser power of 6-12 mW emitted by a continuous wave laser with a wavelength of 375 nm and a spherical beam with a laser power of 9-18 mW emitted by a femtosecond laser with a wavelength of 532 nm, and the pattern changes during the photolithography process were observed. The results are as follows: Figure 3 As shown in ab.
[0089] Depend on Figure 3 (a) It can be seen that when there is no oxidation beam, as the laser power of the annular reduction beam increases from 6mW to 12mW, the average line width of the LSG pattern increases from 310nm to 550nm, corresponding to Figure 3 (a) ① position; when the oxidation beam is introduced, an OLSG can be observed to emerge from the middle of the LSG, such as Figure 3 As shown in (b), as the oxidation power increases from 9 mW (i.e., position ②) to 18 mW (i.e., position ③), the average width of the OLSG line increases from 190 nm to 290 nm, and the average width of the LSG increases from 180 nm to 290 nm (the SEM images are shown in Figure 2). Figure 4 structure A) is reduced to 130nm (see its SEM image Figure 4 structure B).
[0090] It can be seen that this embodiment proves that the dual-beam lithography method can also obtain a graphene lithography pattern with a size below the diffraction limit when applied to a graphene oxide film with a thickness of 850 nm.
[0091] Example 3
[0092] This embodiment provides an application of a graphene structure prepared by a dual-beam lithography method for a graphene structure beyond the diffraction limit, which is used to assemble a supercapacitor, as follows:
[0093] In this embodiment, the LSG patterns corresponding to structure A, structure B, structure A structure C, and structure D in embodiment 1 and embodiment 2 are used to make energy storage electrodes for assembling supercapacitors. The supercapacitor is a sandwich structure, wherein the electrolyte is a PVA / H3PO4 solid gel, specifically, 3 ml H3PO4 and 5 g PVA are added to 40 mL deionized water and stirred for 2 hours at 85°C; the electrode is 9 mm 2 square electrode.
[0094] 1. Capacitor performance test
[0095] The capacitance performance of supercapacitors assembled with structure A, structure B, structure Astructure C and structure D as electrodes were tested respectively. The test results are shown in the figure. Figure 5 shown.
[0096] Conclusion: Figure 5 It can be seen that 850nm graphene oxide film can be made into electrodes with high supercapacitor performance, and 200nm graphene oxide film will cause the graphene flakes to be significantly peeled off from the substrate, resulting in a decrease in capacitance; and from the data, the supercapacitor performance formed by the electrode prepared by structure A is the best, and its weight capacitance corresponding to the current density of 1 and 50A / g is 308 and 210F / g respectively, which is significantly higher than the reported graphene supercapacitors.
Claims
1. A dual-beam lithography method for graphene structures beyond the diffraction limit, characterized in that: include: Preparation of graphene oxide film: using graphite powder to obtain a graphene oxide suspension by Hummers method, and then spin coating the graphene oxide suspension on a PET film to prepare a graphene oxide film; Double-beam laser lithography: A double-beam laser lithography system including an annular reduction beam and a spherical oxidation beam is used to perform photolithography on the graphene oxide film.
2. The dual-beam lithography method for graphene structures beyond the diffraction limit according to claim 1, characterized in that: The spin coating thickness of the graphene oxide suspension is 100-1000 nm.
3. The dual-beam lithography method for graphene structure beyond the diffraction limit according to claim 1, characterized in that: The spin coating speed of the graphene oxide suspension is 100-300 rpm.
4. The dual-beam lithography method for graphene structure beyond the diffraction limit according to claim 1, characterized in that: The annular reduction beam and the spherical oxidation beam are concentric and controlled simultaneously.
5. The dual-beam lithography method for graphene structure beyond the diffraction limit according to claim 4, characterized in that: The outer diameter of the annular reduction light beam is greater than the diameter of the spherical light beam.
6. The dual-beam lithography method for graphene structure beyond the diffraction limit according to claim 4, characterized in that: The annular reduction light beam is emitted by a continuous wave mode laser with a wavelength of 300 to 400 nm, and the spherical oxidation light beam is emitted by a femtosecond laser with a wavelength of 300 to 550 nm.
7. The dual-beam lithography method for graphene structure beyond the diffraction limit according to claim 6, characterized in that: The laser power of the continuous wave mode laser is not greater than 12 mW, and the laser power of the femtosecond laser is not greater than 18 mW.
8. The dual-beam lithography method for graphene structure beyond the diffraction limit according to claim 6, characterized in that: The scanning speed of the continuous wave mode laser is 1 to 30 μm / s, and the scanning speed of the femtosecond laser is 1 to 30 μm / s.
9. The dual-beam lithography method for graphene structure beyond the diffraction limit according to claim 1, characterized in that: The photolithography system includes a confocal detector photomultiplier tube for alignment and beam overlap of the annular reduction beam and the spherical oxidation beam.
10. The dual-beam lithography method for graphene structure beyond the diffraction limit according to claim 1, characterized in that: The numerical aperture of the objective lens used in the photolithography system is 1.
4.
11. A graphene structure prepared by a double-beam lithography method for a graphene structure beyond the diffraction limit according to any one of claims 1 to 10.
12. An application of a graphene structure prepared by the double-beam lithography method for a graphene structure beyond the diffraction limit according to claim 11, characterized in that: Used to assemble supercapacitors.