Erasable graphene and its photolithography method and application

Abstract

The present invention belongs to the field of novel carbon-based photolithography technology, and specifically discloses an erasable graphene and its photolithography method and application. The photolithography method at least comprises the following steps: using laser direct writing to process graphene oxide, preparing graphene while photolithography patterns, and then subjecting the laser-treated graphene oxide to oxygen plasma treatment, so as to erase the laser-directed graphene. The present invention adopts a photolithography method of laser direct writing and oxygen plasma treatment, which can not only realize the photolithography of graphene patterns, but also reversely erase the graphene patterns, so as to facilitate repeated photolithography for multiple times and prepare graphene devices with complex structures. On the other hand, other material systems can be filled and grown after partially or completely erasing the surface graphene, so as to promote the compatibility of graphene devices with multiple material systems, thereby improving the performance of graphene devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel carbon-based photolithography, and in particular relates to erasable graphene and a photolithography method and application thereof. Background Art

[0002] Graphene materials have aroused great research interest due to their excellent optical, electrical and mechanical properties. They are widely used in the preparation of various devices including diodes, field effect transistors, photoelectric sensors, solar cells, super batteries, etc., and have become a new popular material that is very likely to replace traditional silicon materials.

[0003] However, effective preparation of graphene materials and photolithography of their devices have become an important bottleneck for their widespread industrial application. Compared with traditional graphene preparation methods, the method of laser direct writing of graphene can prepare graphene simply and quickly, and at the same time photolithography of graphene structure patterns. By laser irradiation of graphene oxide precursors, the photothermal effect and photochemical effect of the laser can be used to reduce graphene oxide to prepare graphene. The area irradiated by the laser is reduced to conductive graphene, while other areas are still insulating graphene oxide, so various graphene device structures can be photolithographically processed. However, such a laser direct writing graphene process is single, and graphene can only be prepared by one-way photolithography. It is impossible to erase the existing graphene structure and further process the graphene area multiple times, which greatly limits its process and material system, and is not conducive to the preparation of complex graphene three-dimensional multilayer structure devices.

[0004] Therefore, it is of great significance to develop a lithography method that can erasable graphene, so as to achieve the purpose of both etching graphene patterns and erasing graphene patterns in reverse. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present application provides an erasable graphene and a photolithography method thereof, which not only facilitates repeated photolithography of graphene, but also can partially or completely erase the surface graphene, which is conducive to the preparation of graphene devices with complex structures.

[0006] In order to achieve the above-mentioned purpose, the present invention provides, on one hand, a method for erasable graphene lithography, which comprises at least the following steps: performing photolithography on graphene oxide using laser treatment to prepare graphene, and then performing oxygen plasma treatment on the laser-treated graphene oxide to erase the graphene.

[0007] Preferably, the step of laser treating graphene oxide adopts one of the following conditions: (1) the laser wavelength for single-photon absorption is ≤390nm; (2) the laser wavelength for two-photon absorption is ≤780nm; (3) the temperature caused by the action of the laser on the graphene oxide is ≥60°C.

[0008] In the present application, the laser processing of graphene oxide needs to meet one of the above-mentioned conditions so that the photothermal effect and photochemical effect generated by the laser can reduce the graphene oxide irradiated by the laser into graphene, thereby realizing the photolithography of graphene.

[0009] The present application does not impose any particular restriction on the source of graphene oxide, which can be purchased from the market or prepared by itself.

[0010] Preferably, the laser processing method includes laser direct writing.

[0011] The present invention does not impose any special limitation on the laser direct writing equipment, including but not limited to the laser direct writing system produced by Nanoscribe.

[0012] The present application can effectively control the depth of laser reduction of graphene oxide by controlling the parameters of laser processing, and then achieve the erasing depth of different graphenes through oxygen plasma treatment, thereby realizing various three-dimensional graphene device structures.

[0013] Laser parameters include laser wavelength, pulse width, frequency, laser power, and scanning speed.

[0014] The present application does not impose any particular limitation on the equipment for the oxygen plasma treatment, and for example, it may be HarrickPlasma PDC-002.

[0015] Preferably, the depth of the photolithography is 0-10 μm.

[0016] The present application can realize erasable graphene with different lithography depths according to different requirements.

[0017] Preferably, the Raman spectrum of the graphene oxide after the laser treatment is D / I G Less than the I of graphene oxide before laser treatment D / I G .

[0018] Preferably, the Raman spectrum after oxygen plasma treatment is D / I G Greater than laser-treated graphene oxide I D / I G .

[0019] Preferably, the C / O value of the graphene oxide after the laser treatment is greater than the C / O value of the graphene oxide before the laser treatment.

[0020] Preferably, the C / O value after oxygen plasma treatment is less than the C / O value of graphene oxide after laser treatment.

[0021] This application modulates the Raman spectrum of graphene oxide after laser treatment. D / I G Less than I of graphene oxide D / I G , and the C / O value of the graphene oxide after laser treatment is greater than the C / O value of graphene oxide, so that the graphene oxide can be reduced to graphene after laser treatment.

[0022] Furthermore, by adjusting the Raman spectrum of I D / I G Greater than laser-treated graphene oxide I D / I G , and the C / O value after oxygen plasma treatment is less than the C / O value of graphene oxide after laser treatment, which can make the oxygen plasma treatment produce an oxidation effect on the graphene after laser treatment, thereby achieving etching of graphene.

[0023] A second aspect of the present invention provides erasable graphene obtained by the above-mentioned photolithography method.

[0024] A third aspect of the present invention provides an application of erasable graphene for preparing complex device structures.

[0025] Beneficial effects of the present invention:

[0026] (1) The present invention adopts a photolithography method of laser direct writing and oxygen plasma treatment, which can not only realize the photolithography of graphene patterns, but also reversely erase the graphene patterns, so as to facilitate repeated photolithography, which is conducive to the preparation of graphene devices with complex structures;

[0027] (2) By adjusting the parameters of laser direct writing, erasable graphene with different lithography depths can be obtained to meet the needs of preparing graphene devices with various complex structures;

[0028] (3) The photolithography method of the present invention is simple and efficient, has low maskless photolithography cost, does not require additional chemical photoresist, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 (a) is the Raman spectra of graphene oxide and graphene oxide after laser direct writing at different powers in Example 1;

[0030] Figure 1 (b) is the Raman spectrum of the sample after direct writing with a laser of 36 mW power and oxygen plasma treatment in Example 1;

[0031] Figure 1(c) is the X-ray energy spectrum of the graphene oxide in Example 1, the sample after direct writing with 36mW laser and the sample after oxygen plasma treatment;

[0032] Figure 1 (d) is a refined X-ray energy spectrum of graphene oxide in Example 1;

[0033] Figure 1 (e) is a refined X-ray energy spectrum of graphene oxide directly written by a 36 mW laser in Example 1;

[0034] Figure 1 (f) is a refined X-ray energy spectrum of graphene oxide after oxygen plasma treatment with a laser power of 36 mW in Example 1;

[0035] Figure 2 (a) is a microscope photo of laser direct-written graphene oxide in Example 1;

[0036] Figure 2 (b) is a microscope photo of graphene after oxygen plasma treatment in Example 1;

[0037] Figure 2 (c) to (f) are microscope photos during the oxygen plasma treatment process in Example 1;

[0038] Figure 3 (a) is a SEM image of laser-written graphene oxide in Example 1;

[0039] Figure 3 (b) Figure 2 (a) A partial enlarged view;

[0040] Figure 3 (c) is a SEM image of graphene after oxygen plasma treatment in Example 1;

[0041] Figure 3 (d) Figure 2 (c) A partial enlarged view;

[0042] Figure 4 (a) is a microscope photo of the sample after direct writing with a laser of 36 mW in Example 1. The atomic force microscope photo is as follows: Figure 4 (b) shows that the height variation of the cross-sectional view is as follows: Figure 4 (c) shows that its 3D height distribution is Figure 4 (d)

[0043] Figure 4 (e) is a microscope photo of the sample after oxygen plasma treatment in Example 1, and its atomic force microscope photo is as follows Figure 4 As shown in (f), the height variation of the cross-sectional view is as follows: Figure 4 (g) shows that its 3D height distribution is Figure 4 (h) shown. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments and drawings. It should be understood that the 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.

[0045] Example 1

[0046] This embodiment provides a photolithography method for erasable graphene, comprising the following steps: performing photolithography on graphene oxide using laser treatment, and then performing oxygen plasma treatment on the graphene oxide after the laser treatment, so as to obtain erasable graphene.

[0047] In this embodiment, the laser processing adopts the laser direct writing system produced by Nanoscribe, and the laser parameters are set as follows: the laser wavelength is 780nm, the pulse width is 100fs, the frequency is 80MHz, and the scanning speed is 10 4 μm / s, laser power 9~36mW.

[0048] The oxygen plasma treatment uses Harrick Plasma PDC-002, with an operating power of 30W and an oxygen pressure of 500Torr.

[0049] Raman spectrum of graphene oxide after laser treatment D / I G Less than the I of graphene oxide before laser treatment D / I G ,Depend on Figure 1 The Raman spectrum results of (a) show that the I D / I G are greater than those of samples treated with different laser powers, and with the increase of laser power, the I D / I G It gradually decreases, which means that with the increase of laser power, the degree of reduction of graphene oxide gradually increases. It can be seen that the reduction effect of graphene oxide treated with a laser power of 36mW is the best.

[0050] Furthermore, the Raman spectrum after oxygen plasma treatment is D / I G Greater than the I of laser-treated graphene oxideD / I G ,Depend on Figure 1 The Raman spectrum of (b) shows that the graphene oxide treated with a laser power of 36 mW and then treated with oxygen plasma has D / I G Compared with the I of laser treated graphene oxide D / I G This indicates that after the sample is treated with oxygen plasma, it can produce oxidative etching on the laser-reduced graphene oxide.

[0051] The C / O value of graphene oxide after laser treatment is greater than that before laser treatment, and the C / O value after oxygen plasma treatment is less than that after laser treatment. Figure 1 (c) It can be seen that the C / O values ​​of the untreated graphene oxide, the sample after direct writing with 36mW laser and the sample after oxygen plasma treatment are 0.75, 2.72 and 1.55, respectively. At the same time, the changes in the peak values ​​can also be seen from their corresponding refined X-ray energy spectra (d) to (f), that is, the C / O value after laser treatment is significantly higher than that of the untreated graphene oxide, which proves the reducing effect of laser treatment on graphene oxide. The C / O value after oxygen plasma treatment is significantly reduced, which proves the oxidizing effect of oxygen plasma treatment on the sample.

[0052] In order to characterize the effects of laser treatment and oxygen plasma on samples, this embodiment studies the microscope photos of samples treated with laser power of 36mW and oxygen plasma. Figure 2 (a) shows that the black area is the graphene oxide irradiated by the laser, and the other areas are graphene oxide. Figure 2 (b) is a sample treated with oxygen plasma after laser treatment, showing that oxygen plasma treatment completely etches the laser-reduced graphene. Figure 2 (c) to (d) show microscope photos of the oxygen plasma treatment process, showing how the oxygen plasma gradually etches graphene and further erases the photolithographic graphene pattern.

[0053] Furthermore, in order to characterize the effects of laser treatment and oxygen plasma on the sample morphology, the present application studies the SEM images of samples treated with laser power of 36 mW and oxygen plasma. Figure 3 (a) and (b) show that the thermal effect of the laser reduces the graphene oxide, and its surface morphology shows a protruding shape. Figure 3(c) and (d) show that after oxygen plasma treatment of the laser-written sample, its surface morphology becomes concave, which further proves that oxygen plasma treatment can reversely erase the photolithographic graphene pattern obtained by laser direct writing.

[0054] In addition, this embodiment also performs atomic force microscopy tests on samples treated with laser power of 36 mW and oxygen plasma. Figure 4 (a) is a microscope photo of laser-written graphene oxide. It can be seen that the black area is the area treated by laser. Figure 4 (b) is the corresponding atomic force microscope photo, and the height distribution of its cross-section is as follows Figure 4 (c) and its corresponding 3D height distribution is shown in Figure 4 As shown in (d), it can be seen that the laser-treated area is raised, which is consistent with the results presented in the above SEM image, indicating that the laser treatment has a reducing effect on the irradiated graphene oxide, that is, a photolithographic graphene pattern is obtained.

[0055] Figure 4 (e) is a microscope image of the sample after oxygen plasma treatment, and its corresponding atomic force microscope image is as follows: Figure 4 (f), the height distribution of its cross-section is shown in Figure 4 (g), and its corresponding 3D height distribution is shown in (h). It can be seen that the area of ​​the laser-treated sample after oxygen plasma treatment is etched and depressed, which is consistent with the results presented in the above SEM images, indicating that oxygen plasma treatment produces oxidative etching for the laser-treated sample and reversely erases the photolithographic graphene pattern.

[0056] Based on the above test results, it can be seen that the graphene oxide sample can be reduced by laser direct writing to form a graphene pattern, and then the graphene pattern can be reversely erased by oxygen plasma treatment, and a certain etching depth can be formed by controlling the laser parameters. Therefore, the lithography method of the present application can realize repeated lithography on the one hand to prepare graphene devices with complex structures; on the other hand, other material systems can be filled and grown after partially or completely erasing the surface graphene. By stacking multiple material systems, the graphene device is promoted to be compatible with the multiple material systems, thereby improving the performance of the graphene device.

[0057] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for erasable graphene lithography, characterized in that: The method comprises at least the following steps: performing photolithography on graphene oxide by laser treatment to prepare graphene, and then performing oxygen plasma treatment on the graphene oxide after the laser treatment to erase the graphene.

2. The method for erasable graphene lithography according to claim 1, characterized in that: The step of laser processing graphene oxide adopts one of the following conditions: (1) the laser wavelength for single-photon absorption is ≤390nm; (2) the laser wavelength for two-photon absorption is ≤780nm; (3) the temperature caused by the action of the laser on the graphene oxide is ≥60°C.

3. The method for erasable graphene lithography according to claim 1, characterized in that: The laser processing method includes laser direct writing.

4. The method for erasable graphene lithography according to claim 1, characterized in that: The depth of the photolithography is 0-10 μm.

5. The method for erasable graphene lithography according to claim 1, characterized in that: The Raman spectrum of the graphene oxide after laser treatment is D / I G Less than the I of graphene oxide before laser treatment D / I G .

6. The method for erasable graphene lithography according to claim 5, characterized in that: The Raman spectrum after oxygen plasma treatment is D / I G Greater than laser-treated graphene oxide I D / I G .

7. The method for erasable graphene lithography according to claim 1, characterized in that: The C / O value of the graphene oxide after the laser treatment is greater than the C / O value of the graphene oxide before the laser treatment.

8. The method for erasable graphene lithography according to claim 7, characterized in that: The C / O value after the oxygen plasma treatment is less than the C / O value of the graphene oxide after the laser treatment.

9. An erasable graphene prepared by the photolithography method according to any one of claims 1 to 8.

10. A use of erasable graphene according to claim 9, characterized in that: Used to prepare complex device structures.

Images