Method for fixing organic flexible film-based micro-nano structure through electron beam scanning

Abstract

The invention discloses a method for fixing an organic flexible film-based micro-nano structure through electron beam scanning, which comprises the following steps of: firstly, preparing a soft and hard double-layer film, and then stretching or extruding the soft and hard double-layer film, so that a micro-nano structure represented by wrinkles appears on the surface of one side, close to a hard layer, of a flexible layer of the soft and hard double-layer film; then selecting an area needing to be cured on the surface of the hard layer; finally, the selected area is segmented according to the preset maximum single curing area, each segmented area is sequentially subjected to electron beam scanning curing, and when scanning curing is conducted, the electron excitation voltage is lower than a preset voltage threshold value, the single-thread scanning time is smaller than a preset time threshold value, and the scanning current is lower than a preset current threshold value; the scanning frequency is a preset frequency threshold value. According to the method, harsh low-temperature conditions are not needed, the soft film-based micro-nano structure can be effectively fixed, and the external morphology and the internal stress state of the micro-nano structure cannot be changed in the fixing process.

Description

Technical Field

[0001] The invention relates to the field of nanotechnology, and in particular to a method for fixing an organic flexible film-based micro-nano structure by electron beam scanning. Background Art

[0002] In 2008, YK Bharadwai reported the modification of PDMS surface by electron beams of different energies. They said that as the irradiation dose increased from 100 kGy to 500 kGy, the hardness and elastic modulus of the polydimethylsiloxane (PDMS) film surface gradually increased. They believed that as the irradiation dose increased, the cross-linking density between molecules increased and the molecular motion decreased, which ultimately led to a significant increase in the hardness of the PDMS film surface, while the surface became more brittle and more fragile. High-energy heavy ion irradiation can also change the properties of the PDMS film surface. For example, in 2015, Boyin Liu et al. reported the modification behavior of PDMS film surface by kiloelectronvolt (keV) heavy ion beam irradiation. They reported that by irradiation with high-energy heavy ions (Ga+), patterns of nanometer / micrometer size appeared on the PDMS surface. At the same time, the analysis results of nanoindentation showed that with the accumulation of irradiation dose, the elastic modulus of the PDMS surface is expected to be greater than 2 GPa. They believe that heavy metal ion irradiation simultaneously causes an increase in cross-linking density and the formation of a large number of metal-PDMS-based nanocomposites. These two factors together lead to an increase in the surface hardness of PDMS. At the same time, some other literature reports that the carbonized structure caused by heavy ion irradiation in the PDMS film will also cause an increase in the surface hardness of the PDMS film. The appearance of this carbonized structure is caused by the synergistic effect of the energy loss of electrons and nuclei when the incident charged particles interact with the receptor material. Specifically, the energy loss of electrons creates a carbonized structure, and the loss of nuclear energy causes these carbonized structures to link together. The appearance of carbonization will also cause a loss of hydrogen concentration, which will also cause modifications to the PDMS surface, such as surface hardening.

[0003] At present, there is no reliable solution for fixing soft film-based micro-nano structures. The closest solution to this type of solution is cryo-electron microscopy. Cryo-electron microscopy mainly relies on the ultra-low temperature freezing sample preparation and transmission technology of scanning electron microscope to achieve direct observation of liquid, semi-liquid and electron beam-sensitive samples, such as biological and polymer materials. The main application scenario of this technology is life forms containing liquid and semi-liquid. However, the effect of low-temperature freezing technology on soft organic materials is limited. The freezing sample preparation process of cryo-electron microscopy is to a certain extent very dependent on the water content in the sample. However, soft organic materials do not contain water. Even if the sample is placed in liquid nitrogen for a long time. After taking out the sample, a slight bend will cause the freezing effect of the soft film to disappear rapidly. Repeated bending can even completely eliminate the freezing effect. Therefore, cryo-electron microscopy is not suitable for the fixation of soft film-based micro-nano structures.

[0004] In actual research, the overall fixation of the micro-nano structure is very necessary in many aspects such as stress analysis and analysis of changes in the internal structure of the film.

[0005] Electron beam irradiation can harden soft materials, which can harden the soft film-based micro-nano structure as a whole and completely fix it, and low-dose electron beam irradiation will not affect the external morphology and internal stress distribution of the micro-nano structure. Based on the above advantages, this patent proposes a solution for fixing soft film-based micro-nano structures by electron beam scanning. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for fixing an organic flexible thin film-based micro-nano structure by electron beam scanning in view of the defects involved in the background technology.

[0007] The present invention adopts the following technical solutions to solve the above technical problems: A method for fixing an organic flexible thin film-based micro-nano structure by electron beam scanning, comprising the following steps: Step 1), preparation of soft and hard double-layer film: A layer of nanometer-thick flexible film A is transferred onto a flat organic flexible film B, wherein the elastic modulus of the film A is greater than the elastic modulus of the film B, to form a soft-hard double-layer film, wherein the film A is a hard layer and the film B is a flexible layer; Alternatively, the surface of the organic flexible film is treated with oxygen plasma, so that the surface of the organic flexible film is oxidized to form a silicon oxide layer, thereby forming a soft-hard double-layer film, wherein the silicon oxide layer is a hard layer, and the unoxidized portion of the organic flexible film is a flexible layer; Step 2), stretching or squeezing the soft-hard double-layer film so that a micro-nano structure represented by wrinkles appears on the surface of the flexible layer close to the hard layer; Step 3), selecting the area to be cured on the surface of the hard layer; In step 4, the selected area is divided according to the preset maximum single curing area, and each divided area is cured by electron beam scanning in turn. During the scanning curing, the electron excitation voltage is lower than the preset voltage threshold, the single-thread scanning time is less than the preset time threshold, the scanning current is lower than the preset current threshold, and the number of scans is the preset number threshold.

[0008] As a further optimization scheme of the method for fixing organic flexible film-based micro-nano structures by electron beam scanning of the present invention, the organic flexible film B described in step 1) is preferably a PMDS film.

[0009] As a further optimization scheme of the method for fixing organic flexible thin film-based micro-nanostructure by electron beam scanning of the present invention, in step 4), a field emission scanning electron microscope is used as an electron beam source, and a preset voltage threshold is 10 KV , the preset time threshold is 100 μs The preset current threshold is 240 μA .

[0010] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects: The present invention does not require harsh low temperature conditions and can effectively fix the soft film-based micro-nano structure; under the premise of strictly controlling the scanning electron beam dose, the fixing process will not change the external morphology and internal stress state of the micro-nano structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the state where the double-layer film surface is stretched 40% in the horizontal direction and then scanned and solidified; Figure 2 It is a schematic diagram of the state where the double-layer film surface returns to 0% stretch in the horizontal direction after scanning and solidification. DETAILED DESCRIPTION

[0012] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings: The present invention can be implemented in many different forms and should not be considered to be limited to the embodiments described herein. On the contrary, these embodiments are provided to make this disclosure thorough and complete, and will fully express the scope of the present invention to those skilled in the art. In the accompanying drawings, components are enlarged for clarity.

[0013] A method for fixing an organic flexible thin film-based micro-nano structure by electron beam scanning, comprising the following steps: Step 1), preparation of soft and hard double-layer film: A layer of nanometer-thick flexible film A is transferred onto a flat organic flexible film B, wherein the elastic modulus of the film A is greater than the elastic modulus of the film B, to form a soft-hard double-layer film, wherein the film A is a hard layer and the film B is a flexible layer; Alternatively, the surface of the organic flexible film is treated with oxygen plasma, so that the surface of the organic flexible film is oxidized to form a silicon oxide layer, thereby forming a soft-hard double-layer film, wherein the silicon oxide layer is a hard layer, and the unoxidized portion of the organic flexible film is a flexible layer; Step 2), stretching or squeezing the soft-hard double-layer film so that a micro-nano structure represented by wrinkles appears on the surface of the flexible layer close to the hard layer; Step 3), selecting the area to be cured on the surface of the hard layer; In step 4, the selected area is divided according to the preset maximum single curing area, and each divided area is cured by electron beam scanning in turn. During the scanning curing, the electron excitation voltage is lower than the preset voltage threshold, the single-thread scanning time is less than the preset time threshold, the scanning current is lower than the preset current threshold, and the number of scans is the preset number threshold.

[0014] The organic flexible film B in step 1) is preferably a PMDS film.

[0015] In step 4), a field emission scanning electron microscope is preferably used as the electron beam source, and the preset voltage threshold is 10 KV , the preset time threshold is 100 μs The preset current threshold is 240 μA .

[0016] like Figure 1 As shown in the figure, a wrinkle array parallel to the stretching direction appears on the upper surface of the soft and hard double-layer film under the stretching state; then, the wrinkle structure of the selected area is fixed by electron beam scanning, and the micro-nano structure in the selected area can be fixed. Even after the stretching is released, the morphology of the micro-nano structure in the area scanned by the electron beam will not change, as shown in the figure. Figure 2 shown.

[0017] The present invention does not require harsh low temperature conditions, can effectively realize the fixation of soft film-based micro-nano structures, and is suitable for the fixation of all soft film-based micro-nano structures; under the premise of strictly controlling the scanning electron beam dose, the fixation process will not change the external morphology and internal stress state of the micro-nano structure.

[0018] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0019] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for fixing an organic flexible thin film-based micro-nano structure by electron beam scanning, characterized in that: The following steps are involved: Step 1), preparation of soft and hard double-layer film: A layer of nanometer-thick flexible film A is transferred onto a flat organic flexible film B, wherein the elastic modulus of the film A is greater than the elastic modulus of the film B, to form a soft-hard double-layer film, wherein the film A is a hard layer and the film B is a flexible layer; Alternatively, the surface of the organic flexible film is treated with oxygen plasma, so that the surface of the organic flexible film is oxidized to form a silicon oxide layer, thereby forming a soft-hard double-layer film, wherein the silicon oxide layer is a hard layer, and the unoxidized portion of the organic flexible film is a flexible layer; Step 2), stretching or squeezing the soft-hard double-layer film so that a micro-nano structure represented by wrinkles appears on the surface of the flexible layer close to the hard layer; Step 3), selecting the area to be cured on the surface of the hard layer; In step 4, the selected area is divided according to the preset maximum single curing area, and each divided area is cured by electron beam scanning in turn. During the scanning curing, the electron excitation voltage is lower than the preset voltage threshold, the single-thread scanning time is less than the preset time threshold, the scanning current is lower than the preset current threshold, and the number of scans is the preset number threshold.

2. The method for fixing organic flexible thin film-based micro-nano structures by electron beam scanning according to claim 1, characterized in that: The organic flexible film B in step 1) is preferably a PMDS film.

3. The method for fixing organic flexible thin film-based micro-nano structures by electron beam scanning according to claim 1, characterized in that: In step 4), a field emission scanning electron microscope is used as the electron beam source, and the preset voltage threshold is 10 KV , the preset time threshold is 100 μs The preset current threshold is 240 μA .

Images