System and method for fabricating micro-nanostructures in one step using positively and negatively tunable photoresist properties

Abstract

The present invention discloses a system and method for fabricating micro-nanostructures in one step using the properties of positively and negatively tunable photoresist. The system includes a continuous laser, a beam expansion system, an attenuation plate, a half-wave plate, an optical shutter, a spectrometer, an oil-immersion objective lens, and a positively and negatively tunable photoresist sample arranged along an optical path. The system also includes a three-dimensional, high-precision nanopositioning translation stage, a lens, a CCD camera, and a computer. The spectrometer reflects a portion of the laser light incident on the surface of the positively and negatively tunable photoresist sample back to the spectrometer, where it is then irradiated onto a third lens. The oil-immersion objective lens focuses the laser beam onto the sample, fabricating micro-nanostructures of various shapes in one step. The system is then developed using a developer or debonded using a debonding solution. The present invention utilizes a simple continuous laser direct writing method to create a novel polymer structure with both positive and negative properties. This system can fabricate a variety of polymer micro-nanostructures in one step, facilitating the low-cost design of complex submicron patterns and exhibiting promising development prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of laser direct writing, and in particular to a system and method for preparing micro-nano structures in one step by utilizing positive and negative adjustable photoresist properties. Background Art

[0002] With the rapid development of nano / micro technologies, there is a huge demand for multi-purpose submicron photonic structures, such as diffraction gratings, resonant cavities, photonic crystals, and plasmonic structures. Compared with other lithography techniques, laser direct writing (DLW) technology has been widely used in the field of nano / micro manufacturing to prepare 1D, 2D, and 3D photonic structures due to its ease of integration, submicron resolution, and maskless operation. Unfortunately, the limitations of organic photoresists (only positive or negative photoresists can be selected in a single process) and the associated operating environment have hindered traditional DLW methods.

[0003] The recently developed low single-photon absorption (LSP) DLW method offers the ability to combine single-photon (SP) and two-photon (or) multi-photon (TP) methods. This method relies on the wavelength of the excitation laser being close to the absorption band edge of the photoresist. One can create the desired submicron structure by changing the wavelength, numerical aperture, and photoresist. However, this method cannot solve the multi-step and complex sample fabrication process. Recently, Tong et al. used positive organic photoresist S1805 / 1818 to prepare 2D and 3D polymer structures by DLW through photoinduced local heating effect and various post-lithography processes to convert the material to negative. However, the problem is that it is difficult to remove the cross-linked polymer, which leads to the instability of the prepared 3D patterns. They claimed that the polymer curing is caused by cross-linking at the polymer / glass transition temperature. This phenomenon has been described for a long time, but the exact mechanism remains unknown. Therefore, the application of this technology is questionable. In addition, Xi et al. reported an inorganic photoresist Ge2Sb 1.5 Bi 0.5 Research on laser-induced phase transitions in Te5 shows that this photoresist exhibits both positive and negative modulation depending on laser intensity. However, its use as a template or host material in DLW techniques is not ideal. Each system has its own limitations and mechanisms that must be addressed.

[0004] Furthermore, Lim et al. utilized a combined UV lithography and DLW method, using both positive and negative organic photoresists to fabricate the desired patterns with good resolution and fabrication efficiency. However, the complex instrumentation and mask-assisted processes make this technique impractical. Typically, only one type of photoresist, either positive or negative, is available, requiring a very complex processing / experimental procedure if we want to combine both properties while fabricating versatile photonic structures. Because organic photoresists easily combine with guest materials and flexible templates, they are ideal for fabricating diverse polymer structures. Therefore, developing suitable techniques is essential, rather than searching for new photoresists. This problem persists due to a lack of knowledge about the interaction between LSP-DLW and available organic photoresists. Moreover, most studies described to date, including details of the multi-step preparation of one-dimensional, two-dimensional, and three-dimensional polymer structures, have not acknowledged their practicality and flexibility. Summary of the Invention

[0005] In view of this, in order to solve the problem in the prior art that micro-nano structures need to be obtained through two or more processing steps or the preparation method is too costly, the present invention proposes a system and method for preparing micro-nano structures in one step using positive and negative tunable photoresist properties.

[0006] The present invention solves the above problems through the following technical means:

[0007] In one aspect, the present invention provides a system for fabricating micro-nanostructures in one step using the properties of positively and negatively tunable photoresist, comprising a continuous laser, a beam expansion system, an attenuation plate, a half-wave plate, an optical shutter, a spectrometer, an oil-immersion objective lens, and a positively and negatively tunable photoresist sample arranged along an optical path; the system also comprises a three-dimensional high-precision nanopositioning translation stage, a third lens, a CCD camera, and a computer;

[0008] The positive and negative adjustable photoresist sample is mounted on a three-dimensional high-precision nanopositioning translation stage;

[0009] The continuous laser is used to emit a continuous wave laser beam;

[0010] The beam expansion system is used to expand the continuous wave laser beam;

[0011] The attenuation plate is used to control the energy of the continuous wave laser beam after beam expansion;

[0012] The half-wave plate is used to control the polarization direction of the continuous wave laser beam;

[0013] The optical shutter is used to control the light flux of the continuous wave laser beam;

[0014] The spectroscopic device is used to focus the incident continuous wave laser beam onto the surface of the positive and negative adjustable photoresist sample through the oil immersion objective lens, and a part of the laser incident on the surface of the positive and negative adjustable photoresist sample is reflected onto the spectroscopic device and then irradiated onto the third lens;

[0015] The oil immersion objective lens is used to focus the laser beam on the positive and negative adjustable photoresist sample, and under the conditions of appropriate laser flux and exposure time, micro-nano structures of various shapes are prepared in one step, and then developed with a developer or removed with a debonding solution;

[0016] The third lens is used to focus the laser beam on the CCD camera;

[0017] The CCD camera is used to monitor the processing process in real time and observe the exposure of the light beam;

[0018] The computer is used to control the three-dimensional high-precision nanopositioning translation stage and the CCD camera.

[0019] Preferably, the beam expansion system comprises a first lens and a second lens arranged along the optical path; the continuous wave laser beam is expanded by passing through the first lens and the second lens in sequence.

[0020] Preferably, the system for preparing micro-nano structures in one step using positive and negative adjustable photoresist properties further includes a first reflector and a second reflector arranged along the optical path; the expanded continuous wave laser beam is sequentially emitted to the attenuation plate through the first reflector and the second reflector.

[0021] Preferably, the positive-negative tunable photoresist sample includes a substrate and an S1813 positive photoresist coated on the substrate.

[0022] Preferably, the S1813 positive photoresist comprises cresol novolac resin, diazonaphthoquinone photosensitive compound and solvent.

[0023] Preferably, the positive and negative tunable photoresist sample preparation process is as follows:

[0024] Before the spin coating process, the substrate was ultrasonically cleaned with acetone, ethanol, and methanol, and tiny particles were removed by dry inert gas. S1813 positive photoresist was spin-coated on the substrate at 500 rpm for 9 seconds and then at 5000 rpm for 60 seconds. The coated film was then gently baked at 115°C for 60 seconds. The final sample film thickness was 1.2 μm.

[0025] Preferably, the various shapes of the micro-nano structures include an inverted ring structure, a columnar structure, a smooth donut structure, a flower-shaped donut structure, and a flower-shaped donut+ring structure.

[0026] Preferably, the inverted ring structure includes the following parts: N: the central part of the tightly focused beam, in which the positive photoresist is converted to negative, resulting in polymer solidification; P: the outside of the focused beam, where the photoresist exhibits positive characteristics, and normal polymerization occurs in this area, which is removed in the subsequent development process; U: the non-focused part, in which the polymer film is not affected; and finally, the inverted ring structure is formed after development.

[0027] The columnar structure includes the following parts: N: the central part of the tightly focused beam, in which the positive photoresist is converted to negative, resulting in polymer solidification; P: the remaining part of the center of the tightly focused beam, in which the photoresist exhibits positive characteristics, and normal polymerization occurs in this area, which is removed in the subsequent development process; finally, the columnar structure is formed after development;

[0028] The smooth donut structure comprises the following parts: A: the central part of the tightly focused beam, where the cured polymer is ablated; N: the outer part of the tightly focused beam, where the positive photoresist is converted to negative, resulting in the curing of the polymer; and finally, a smooth donut structure is formed after development.

[0029] The flower-shaped donut structure comprises the following parts: A: the central portion of the tightly focused beam, where the cured polymer is ablated; N: the outer portion of the tightly focused beam, where the positive photoresist is converted to negative, causing the polymer to solidify; ultimately, the flower-shaped donut structure is formed after the resist is removed;

[0030] The flower-shaped donut + ring structure includes the following parts: A: the central part of the tightly focused light beam, where the solidified polymer is ablated; N: the outer part of the tightly focused light beam, where the positive photoresist is converted to negative, causing the polymer to solidify; P: the extreme outer part of the focused light beam, where normal polymerization occurs and is removed during subsequent development; U: the non-focused part, where the polymer film is unaffected; and finally, a flower-shaped donut + ring structure is formed after development.

[0031] As a preferred method, the principle of preparing micro-nano structures of various shapes in one step is as follows:

[0032] The S1813 positive photoresist comprises a cresol novolac resin (NR) and a photosensitive compound, naphthoquinone (DNQ). The cresol novolac polymer resin contains a large number of -OH groups in its molecular structure, exhibiting strong hydrophilicity and being easily dissolved in alkaline aqueous solutions. On the other hand, the photoactive DNQ is highly hydrophobic and exhibits resistance to dissolution in alkaline / aqueous media. When DNQ is impregnated into the NR, the NR becomes hydrophobic, and its solubility is greatly suppressed. Therefore, the film obtained by spin coating and baking is insoluble. When the polymer film is exposed to light, the water-insoluble photoactive chemical DNQ is converted into a soluble indolecarboxylic acid (ICA), which helps dissolve the polymer resin in specific areas exposed to light and can subsequently be developed with a corresponding developer.

[0033] The conversion of DNQ to ICA is relatively poor when the incident light wavelength is close to the edge of the DNQ absorption band (hν ~ Eg); in addition, the diffusion dynamics of light in the polymer medium are not even in the exposure region of low absorption wavelengths; while increasing the exposure time and light intensity, the photothermal / ablative effect plays an important role; in addition, by changing the exposure time and laser intensity, the diffusion rate of the newly converted ICA can be controlled; in the initial stage of light absorption, two different phenomena are believed to occur simultaneously: (i) a large amount of DNQ is converted to ICA, and (ii) a small amount of the converted ICA undergoes further structural changes through decarboxylation; the decarboxylated indanediones / indanedione dimers are both hydrophobic, so they again act as dissolution inhibitors; therefore, they help resist polymer resins from developers / solvents; in addition to the expected positive behavior of S1813 photoresist, negative photoresist behavior can be observed by utilizing the specific light intensity and tightly focused spot of the continuous wave laser to reach the threshold energy for the ICA / NR photochemical conversion; specifically, the threshold energy of the outer beam is just enough to convert DNQ / NR to ICA / NR, during which positive photoresist behavior can be observed; the tightly focused spot in the center of the beam reaches the threshold energy for the ICA / NR photochemical conversion, during which negative photoresist behavior can be observed; a polymer film is formed in the unexposed area; therefore, complex patterns can be displayed in a single exposure.

[0034] In another aspect, the present invention provides a method for fabricating a micro-nanostructure in one step by utilizing positively and negatively tunable photoresist properties, comprising the following steps:

[0035] The positive and negative adjustable photoresist sample is mounted on a three-dimensional high-precision nanopositioning translation stage;

[0036] A continuous wave laser is used to emit a continuous wave laser beam;

[0037] A beam expansion system is used to expand the continuous wave laser beam;

[0038] An attenuator is used to control the energy of the expanded continuous wave laser beam;

[0039] A half-wave plate is used to control the polarization direction of the continuous wave laser beam;

[0040] An optical shutter is used to control the light flux of a continuous wave laser beam;

[0041] A beam splitter or polarization beam splitter prism is used to focus the incident continuous wave laser beam onto the surface of the positive and negative adjustable photoresist sample through an oil immersion objective lens. A portion of the laser beam incident on the surface of the positive and negative adjustable photoresist sample is reflected onto the beam splitter or polarization beam splitter prism and then irradiated onto the third lens.

[0042] An oil-immersion objective lens is used to focus the laser beam on a positive-negative photoresist sample. Under appropriate laser flux and exposure time conditions, micro-nano structures of various shapes are prepared in one step. The sample is then developed with a developer or removed with a debonding solution.

[0043] A third lens is used to focus the laser beam onto the CCD camera;

[0044] Use CCD camera to monitor the processing process in real time and observe the exposure of the light beam;

[0045] Computer-controlled three-dimensional high-precision nanopositioning translation stage and CCD camera.

[0046] Compared with the prior art, the beneficial effects of the present invention include at least:

[0047] The present invention simply uses continuous laser direct writing to manufacture a new type of polymer structure with coexisting positive and negative properties, and can complete the preparation of various polymer micro-nano structures in one step, which helps to design submicron-level complex patterns at low cost and has good development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0049] Figure 1 Schematic diagram of the structure of the system for fabricating micro-nano structures in one step by utilizing positive and negative adjustable photoresist properties of the present invention;

[0050] Figure 2 (a) is a SEM image of the inverted ring structure of the present invention, Figure 2 (b) is a schematic diagram of the inverted ring structure of the present invention;

[0051] Figure 3 (a) is a SEM image of the columnar structure of the present invention, Figure 3 (b) is a schematic diagram of the columnar structure of the present invention;

[0052] Figure 4 (a) is a SEM image of the smooth donut structure of the present invention, Figure 4 (b) is a schematic diagram of the smooth donut structure of the present invention; Figure 4 (c) is a SEM image of the flower-shaped donut structure of the present invention, Figure 4 (d) is a schematic diagram of the flower-shaped donut structure of the present invention;

[0053] Figure 5 (a) is a SEM image of the flower-shaped donut + ring structure of the present invention, Figure 5 (b) is a schematic diagram of the flower-shaped donut + ring structure of the present invention;

[0054] Figure 6 The present invention is a flow chart of a method for preparing a micro-nano structure in one step by utilizing positive and negative adjustable photoresist properties.

[0055] Description of reference numerals:

[0056] 1. Continuous laser; 2. First lens; 3. Second lens; 4. First reflector; 5. Second reflector; 6. Attenuation plate; 7. Half-wave plate; 8. Optical shutter; 9. Spectral splitter; 10. Oil-immersion objective; 11. Three-dimensional high-precision nanopositioning translation stage; 12. Positive and negative adjustable photoresist sample; 13. Third lens; 14. CCD camera; 15. Computer. DETAILED DESCRIPTION

[0057] To make the above-mentioned objectives, features, and advantages of the present invention more clearly understood, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0058] Example 1

[0059] like Figure 1 As shown, the present invention provides a system for fabricating micro-nano structures in one step by utilizing the properties of positively and negatively tunable photoresist, comprising a continuous laser 1, a beam expansion system, an attenuation plate 6, a half-wave plate 7, an optical shutter 8, a beam splitter 9, an oil-immersion objective lens 10, and a positively and negatively tunable photoresist sample 12 arranged along an optical path; further comprising a three-dimensional high-precision nanopositioning translation stage 11, a third lens 13, a CCD camera 14, and a computer 15;

[0060] The positive and negative adjustable photoresist sample 12 is mounted on a three-dimensional high-precision nanopositioning translation stage 11;

[0061] The continuous laser 1 is used to emit a continuous wave laser beam;

[0062] The beam expansion system is used to expand the continuous wave laser beam;

[0063] The attenuation plate 6 is used to control the energy of the continuous wave laser beam after beam expansion;

[0064] The half-wave plate 7 is used to control the polarization direction of the continuous wave laser beam;

[0065] The optical shutter 8 is used to control the light flux of the continuous wave laser beam;

[0066] The spectroscopic device 9 is used to focus the incident continuous wave laser beam onto the surface of the positive and negative tunable photoresist sample 12 through the oil immersion objective lens 10. A portion of the laser light incident on the surface of the positive and negative tunable photoresist sample 12 is reflected onto the spectroscopic device 9 and then irradiated onto the third lens 13. In this embodiment, the spectroscopic device 9 is a beam splitter or a polarization spectroscopic prism.

[0067] The oil immersion objective lens 10 is used to focus the laser beam on the positive and negative adjustable photoresist sample 12, and under the conditions of appropriate laser flux and exposure time, micro-nano structures of various shapes are prepared in one step, and then developed with a developer or removed with a debonding solution;

[0068] The third lens 13 is used to focus the laser beam onto the CCD camera 14;

[0069] The CCD camera 14 is used to monitor the processing process in real time and observe the exposure of the light beam;

[0070] The computer 15 is used to control the three-dimensional high-precision nanopositioning translation stage 11 and the CCD camera 14 .

[0071] Specifically, the beam expansion system includes a first lens 2 and a second lens 3 arranged along the optical path; the continuous wave laser beam is expanded by passing through the first lens 2 and the second lens 3 in sequence.

[0072] Specifically, the system for preparing micro-nano structures in one step using positive and negative adjustable photoresist properties also includes a first reflector 4 and a second reflector 5 arranged along the optical path; the expanded continuous wave laser beam is emitted to the attenuation plate 6 through the first reflector 4 and the second reflector 5 in sequence.

[0073] Specifically, the positive-negative tunable photoresist sample 12 includes a substrate and S1813 positive photoresist coated on the substrate. The S1813 positive photoresist (Micorchem, USA) is composed of cresol novolac resin (NR), diazonaphthoquinone (DNQ) photosensitive compound and solvent.

[0074] According to the results of physical and chemical analysis, it was determined that the S1813 positive photoresist is composed of cresol novolac resin (NR) and the photosensitive compound diazonaphthoquinone (DNQ). The molecular structure of cresol novolac polymer resin contains a large number of -OH groups, so it exhibits strong hydrophilic properties and is easily dissolved by alkaline aqueous solutions. On the other hand, the photoactive DNQ is very hydrophobic and exhibits anti-dissolution properties in alkaline / aqueous media. When DNQ is impregnated into NR, NR becomes hydrophobic and its solubility is greatly suppressed. Therefore, the film obtained by spin coating and baking is insoluble. When the polymer film is exposed to light, the water-insoluble photoactive chemical (DNQ) is converted into soluble indolecarboxylic acid (ICA), which helps dissolve the polymer resin in specific areas exposed to light and can subsequently be developed by the corresponding developer.

[0075] The conversion of DNQ to ICA is relatively poor when the incident light wavelength is close to the edge of the DNQ absorption band (hν to Eg). Furthermore, the diffusion kinetics of light in the polymer medium are not even in the exposure region of low absorption wavelengths. While increasing exposure time and light intensity, photothermal / ablative effects play a significant role. Furthermore, by varying exposure time and laser intensity, the diffusion rate of the newly converted ICA can be controlled. During the initial phase of light absorption, two distinct phenomena are believed to occur simultaneously: (i) a large amount of DNQ is converted to ICA, and (ii) a small amount of the converted ICA undergoes further structural changes through decarboxylation. Decarboxylated indanediones / indanedione dimers are hydrophobic, so they again act as dissolution inhibitors. Therefore, they help resist the polymer resin from the developer / solvent. In addition to the expected positive-tone behavior of S1813 photoresist, negative-tone behavior was observed by using a specific light intensity and a tightly focused spot at 473 nm to reach the threshold energy for the photochemical conversion of ICA to NR. Specifically, the (loosely focused) threshold energy of the outer beam is just enough to convert DNQ / NR to ICA / NR, during which the behavior of positive photoresist can be observed. The tightly focused spot in the center of the beam reaches the threshold energy for the photochemical conversion of ICA / NR, during which the behavior of negative photoresist can be observed. The unexposed area forms a polymer film. Therefore, in a single exposure, complex patterns can be displayed.

[0076] The system preparation process of the present invention using positive and negative adjustable photoresist properties to prepare micro-nano structures in one step is generally as follows:

[0077] Materials: S1813 positive photoresist (Micorchem, USA) consists of cresol novolac resin (NR), diazonaphthoquinone (DNQ) photosensitive compound, and solvent. MF319 developer (N-methylpyrrolidone (NMP)) was purchased from Resmi Co., Ltd. The photoresist and NMP solution were prepared by diluting with MilliQ water (18.2 MΩ·cm).

[0078] 2. Sample Preparation: Prior to the spin coating process, the substrate was ultrasonically cleaned with acetone, ethanol, and methanol, and fine particles were removed by passing through a dry inert gas atmosphere. S1813 was spin-coated onto a glass substrate at 500 rpm for 9 seconds, followed by 5000 rpm for 60 seconds. The coated film was then gently baked at 115°C for 60 seconds. The final sample film thickness was 1.2 μm.

[0079] 3. Preparation process: Figure 1 As shown, a continuous wave (CW) laser with a wavelength of 473 nm is used as the irradiation source. In order to control the energy and polarization direction of the laser beam, an attenuation plate 6 and a half-wave plate 7 are used. A 100x oil immersion objective lens 10 (NA=1.4, Zeiss) is used to focus the laser beam on the sample 12. The sample 12 is mounted on a three-dimensional high-precision nanopositioning translation stage 11 (P-563, PI) controlled by a computer 15. Under appropriate laser flux and exposure time conditions (such as the experimental conditions of the example), various micro-nano structures of various shapes as shown in the figure can be prepared. After direct writing processing, the sample 12 needs to be developed / de-bonded with MF319 / NMP for 30 seconds.

[0080] Figure 2 (a) is the SEM image of the inverted ring structure. Figure 2 (b) Schematic diagram of the inverted ring structure; the inverted ring structure consists of the following sections: N: the center of the tightly focused beam, where the photoresist converts from positive to negative, resulting in polymer solidification; P: the outer portion of the focused beam, where the photoresist exhibits positive properties and undergoes normal polymerization, which is removed during subsequent development; U: the unfocused portion, where the polymer film remains unaffected. Ultimately, the inverted ring structure is formed after development.

[0081] Figure 3 (a) is the SEM image of the columnar structure. Figure 3 (b) Schematic diagram of a pillar structure. The pillar structure consists of the following sections: N: the center of the tightly focused beam, where the photoresist converts from positive to negative, resulting in polymer solidification; P: the rest of the tightly focused beam center, where the photoresist exhibits positive properties. Normal polymerization occurs within this region and is removed during the subsequent development process. The pillar structure is ultimately formed after development.

[0082] Figure 4 (a) is the SEM image of the smooth donut structure. Figure 4(b) Schematic diagram of a smooth donut structure. The smooth donut structure consists of the following parts: A: the center of the tightly focused beam, where the cured polymer is ablated; N: the outer portion of the tightly focused beam, where the photoresist is converted from positive to negative, resulting in the polymer curing. The final smooth donut structure is formed after development. Figure 4 (c) is the SEM image of the flower-shaped donut structure. Figure 4 (d) Schematic diagram of a flower-shaped donut structure. The flower-shaped donut structure consists of the following components: A: the central portion of the tightly focused beam, where the cured polymer is ablated; N: the outer portion of the tightly focused beam, where the photoresist is converted from positive to negative, resulting in the polymer curing. The flower-shaped donut structure is ultimately formed after resist removal.

[0083] Figure 5 (a) is the SEM image of the flower-shaped donut + ring structure. Figure 5 (b) Schematic diagram of the flower-shaped donut + ring structure; the flower-shaped donut + ring structure consists of the following sections: A: the center of the tightly focused beam, where the cured polymer is ablated; N: the outer portion of the tightly focused beam, where the photoresist converts from positive to negative, resulting in polymer solidification; P: the extreme outer portion of the focused beam, where normal polymerization occurs and is removed during subsequent development; U: the unfocused portion, where the polymer film remains unaffected. The final structure after development is the flower-shaped donut + ring structure.

[0084] At a laser power density of 0.64 mJ / μm 2 Under the conditions of exposure time of 0.5s, the attached Figure 2 (a) shows an inverted ring structure. In this case, the applied laser beam can simultaneously generate negative and positive features in the polymer film. Specifically, in the central portion of the tightly focused beam, the positive behavior is converted to negative behavior, resulting in polymer solidification; in the outer portion of the focused beam, the DNQ is converted to ICA, resulting in positive behavior, which is removed during subsequent development.

[0085] At a laser power density of 0.64 mJ / μm 2 Under the conditions of 0.5s exposure time, based on the above anti-ring structure, the distance between the anti-rings can be properly controlled to obtain the attached Figure 3 (a) shows a columnar structure. Similar to the previous case, the applied laser beam can simultaneously generate both negative and positive features in the polymer film. Specifically, in the tightly focused central portion of the beam, the positive behavior is converted to negative, resulting in polymer solidification; in the remaining portion, the DNQ is converted to ICA, resulting in positive behavior, which is then removed during subsequent development.

[0086] At a laser power density of 70.03 mJ / μm 2 Under the conditions of exposure time of 1s, the attached Figure 4 The smooth donut structure shown in (a) can also be obtained by replacing the development with the degumming. Figure 4 (c) shows the flower-shaped donut structure. In this case, the applied laser beam can simultaneously produce ablation and negative features in the polymer film. At this time, in the central part of the tightly focused beam, the solidified polymer (formed by the negative behavior of S1813) is ablated; in the outer part of the tightly focused beam, the positive is converted to negative, resulting in polymer solidification. The flower-shaped donut structure obtained after debonding can be explained by the fact that the newly formed ICA at the edge of the ring structure is not completely converted into highly soluble compounds such as indene dimers due to the invasion of ICA molecules into the polymer resin and the uneven diffusion of energy. As a result, some specific spots that are not completely decarboxylated are washed away by the debonding solution during the debonding process, resulting in the flower-shaped donut pattern.

[0087] At a laser power density of 4.46 mJ / μm 2 Under the conditions of exposure time 0.1s, the attached Figure 5 (a) Flower-shaped donut + ring structure shown. In this case, the applied laser beam can simultaneously produce ablated, negative, positive, and unexposed features in the polymer film. Specifically, in the central portion of the tightly focused beam, the cured polymer (formed by the negative behavior of S1813) is ablated; in the outer portion of the tightly focused beam, the positive is converted to negative, resulting in polymer curing; in the extreme outer portion of the focused beam, DNQ is converted to ICA (leading to positive behavior); and in the unfocused portion, the polymer film is unaffected.

[0088] It can be seen that the present invention can complete the preparation of various polymer micro-nano structures in one step by simply using continuous laser direct writing to manufacture a new type of polymer structure with coexisting positive and negative properties. This helps to design submicron-level complex patterns at low cost and has good development prospects.

[0089] Example 2

[0090] like Figure 6 As shown, the present invention provides a method for preparing a micro-nano structure in one step by utilizing positive and negative tunable photoresist properties, comprising the following steps:

[0091] S1, mounting the positive and negative adjustable photoresist sample 12 on the three-dimensional high-precision nanopositioning translation stage 11;

[0092] S2, using continuous laser 1 to emit a continuous wave laser beam;

[0093] S3, using a beam expansion system to expand the continuous wave laser beam;

[0094] S4, using an attenuation plate 6 to control the energy of the continuous wave laser beam after beam expansion;

[0095] S5, using a half-wave plate 7 to control the polarization direction of the continuous wave laser beam;

[0096] S6, using the optical shutter 8 to control the light flux of the continuous wave laser beam;

[0097] S7, using a beam splitter or polarization beam splitter prism 9 to focus the incident continuous wave laser beam onto the surface of the positive and negative adjustable photoresist sample 12 through the oil immersion objective lens 10, and a portion of the laser beam incident on the surface of the positive and negative adjustable photoresist sample 12 is reflected onto the beam splitting device 9 and then irradiated onto the third lens 13;

[0098] S8, using an oil immersion objective lens 10 to focus a laser beam on the positive and negative adjustable photoresist sample 12, preparing micro-nano structures of various shapes in one step, and then developing with a developer or removing the glue with a glue remover;

[0099] S9, using the third lens 13 to focus the laser beam onto the CCD camera 14;

[0100] S10, using a CCD camera 14 to monitor the processing process in real time and observe the exposure of the light beam;

[0101] S11 , using the computer 15 to control the three-dimensional high-precision nanopositioning translation stage 11 and the CCD camera 14 .

[0102] The method for preparing micro-nano structures in one step by utilizing positively and negatively tunable photoresist properties of the present invention generally includes the following steps:

[0103] Materials: S1813 positive photoresist (Micorchem, USA) consists of cresol novolac resin (NR), diazonaphthoquinone (DNQ) photosensitive compound, and solvent. MF319 developer (N-methylpyrrolidone (NMP)) was purchased from Resmi Co., Ltd. The photoresist and NMP solution were prepared by diluting with MilliQ water (18.2 MΩ·cm).

[0104] 2. Sample Preparation: Prior to the spin coating process, the substrate was ultrasonically cleaned with acetone, ethanol, and methanol, and fine particles were removed by passing through a dry inert gas atmosphere. S1813 was spin-coated onto a glass substrate at 500 rpm for 9 seconds, followed by 5000 rpm for 60 seconds. The coated film was then gently baked at 115°C for 60 seconds. The final sample film thickness was 1.2 μm.

[0105] 3. Preparation process: Figure 1As shown, a continuous wave (CW) laser with a wavelength of 473 nm is used as the irradiation source. In order to control the energy and polarization direction of the laser beam, an attenuation plate 6 and a half-wave plate 7 are used. A 100x oil immersion objective lens 10 (NA=1.4, Zeiss) is used to focus the laser beam on the sample 12. The sample 12 is mounted on a three-dimensional high-precision nanopositioning translation stage 11 (P-563, PI) controlled by a computer 15. Under appropriate laser flux and exposure time conditions (such as the experimental conditions of the example), various micro-nano structures of various shapes as shown in the figure can be prepared. After direct writing processing, the sample 12 needs to be developed / de-bonded with MF319 / NMP for 30 seconds.

[0106] The other features of this embodiment are the same as those of embodiment 1, so they will not be repeated here.

[0107] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A system for fabricating micro-nano structures in one step using positively and negatively tunable photoresist properties, characterized in that: It includes a continuous laser, a beam expansion system, an attenuation plate, a half-wave plate, an optical shutter, a spectrometer, an oil-immersion objective lens, and a positive and negative adjustable photoresist sample arranged along the optical path; it also includes a three-dimensional high-precision nanopositioning translation stage, a third lens, a CCD camera, and a computer; The positive and negative adjustable photoresist sample is mounted on a three-dimensional high-precision nanopositioning translation stage; the positive and negative adjustable photoresist sample comprises a substrate and an S1813 positive photoresist coated on the substrate; the S1813 positive photoresist comprises a cresol novolac resin, a diazonaphthoquinone photosensitive compound and a solvent; The continuous laser is used to emit a continuous wave laser beam; The beam expansion system is used to expand the continuous wave laser beam; The attenuation plate is used to control the energy of the continuous wave laser beam after beam expansion; The half-wave plate is used to control the polarization direction of the continuous wave laser beam; The optical shutter is used to control the light flux of the continuous wave laser beam; The spectroscopic device is used to focus the incident continuous wave laser beam onto the surface of the positive and negative adjustable photoresist sample through the oil immersion objective lens, and a part of the laser incident on the surface of the positive and negative adjustable photoresist sample is reflected onto the spectroscopic device and then irradiated onto the third lens; The oil-immersion objective lens is used to focus a laser beam on a positive-negative tunable photoresist sample, and under the conditions of appropriate laser flux and exposure time, micro-nano structures of various shapes are prepared in one step, and then developed with a developer or removed with a debonding solution; the various micro-nano structures include inverted ring structures, columnar structures, smooth donut structures, flower-shaped donut structures, and flower-shaped donut + ring structures; The third lens is used to focus the laser beam on the CCD camera; The CCD camera is used to monitor the processing process in real time and observe the exposure of the light beam; The computer is used to control the three-dimensional high-precision nanopositioning translation stage and the CCD camera; When the incident light wavelength is close to the edge of the DNQ absorption band, the conversion of DNQ to ICA is relatively poor. The threshold energy of the external beam is only sufficient to convert DNQ / NR to ICA / NR, during which positive photoresist behavior can be observed. When the beam center region is tightly focused to reach the threshold energy for the photochemical conversion of ICA / NR, negative photoresist behavior can be observed. The unexposed areas form a polymer film.

2. A method for preparing micro-nano structures in one step using positively and negatively tunable photoresist properties, characterized in that: The steps include: Mounting a positive and negative adjustable photoresist sample on a three-dimensional high-precision nanopositioning translation stage; the positive and negative adjustable photoresist sample comprises a substrate and an S1813 positive photoresist coated on the substrate; the S1813 positive photoresist comprises a cresol novolac resin, a diazonaphthoquinone photosensitive compound, and a solvent; A continuous wave laser is used to emit a continuous wave laser beam; A beam expansion system is used to expand the continuous wave laser beam; An attenuator is used to control the energy of the expanded continuous wave laser beam; A half-wave plate is used to control the polarization direction of the continuous wave laser beam; An optical shutter is used to control the light flux of a continuous wave laser beam; A beam splitter or polarization beam splitter prism is used to focus the incident continuous wave laser beam onto the surface of the positive and negative adjustable photoresist sample through an oil immersion objective lens. A portion of the laser beam incident on the surface of the positive and negative adjustable photoresist sample is reflected onto the beam splitter or polarization beam splitter prism and then irradiated onto the third lens. An oil-immersion objective lens is used to focus the laser beam on a positive-negative photoresist sample. Under appropriate laser flux and exposure time conditions, micro-nano structures of various shapes are prepared in one step. The sample is then developed with a developer or removed with a debonding solution. A third lens is used to focus the laser beam onto the CCD camera; Use CCD camera to monitor the processing process in real time and observe the exposure of the light beam; Computer-controlled three-dimensional high-precision nanopositioning translation stage and CCD camera; The principles for preparing micro-nano structures of various shapes in one step include: When the incident light wavelength is close to the edge of the DNQ absorption band, the conversion of DNQ to ICA is relatively poor; the threshold energy of the external beam is only sufficient to convert DNQ / NR into ICA / NR, during which the behavior of positive photoresist can be observed; the light spot in the central area of the beam is tightly focused to reach the threshold energy for the photochemical conversion of ICA / NR, during which the behavior of negative photoresist can be observed; and a polymer film is formed in the unexposed area.

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