Maskless micro-nano structure processing device and processing method

Abstract

The invention belongs to the technical field of combination of optics, microscopy and micro-nano structures, and particularly relates to a maskless micro-nano structure processing device and method, and the device comprises a near ultraviolet light source, a first collimating lens, a digital micromirror array, a secondary zooming assembly and an objective lens; the first collimating lens is arranged in front of a light emitting point of the near ultraviolet light source, the digital micromirror array is arranged on an emergent light path of the first collimating lens, and the digital micromirror array regulates and controls incident light according to micro-nano structure digital mask information preset in the digital micromirror array to form emergent light with a target pattern. The secondary zooming assembly is arranged on an emergent light path of the digital micromirror array, the objective lens is arranged on an emergent light path of the secondary zooming assembly, and emergent light of the objective lens irradiates a substrate of the micro-nano structure to be processed. According to the processing method disclosed by the invention, the specific photocurable prepolymer is used, so that the traditional DMPL maskless photoetching technical process is simplified, the cost is reduced, and the processing precision and stability are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of the combination of optics, microscopy technology and micro-nano structures, and specifically relates to a maskless micro-nano structure processing device and processing method. The present invention uses a specific photocurable prepolymer to simplify the traditional DMPL maskless lithography technology process, reduce costs, and improve processing accuracy and stability. Background Art

[0002] The traditional field of micro-nanostructure manufacturing mainly relies on core technologies such as mask lithography, nanoimprinting and self-assembly. Among them, mask lithography technology uses a precise mask plate to accurately copy the preset pattern onto a photosensitive recording material (i.e., photoresist), and then accurately transfers the pattern to a wafer or substrate material through an etching process to produce complex micro-nanostructures such as electronic circuits, microfluidic devices, and optical diffraction elements. Nanoimprinting technology uses mechanical methods to directly transfer the fine structure on the template to the surface of the material to be processed. Its processing accuracy has reached the nanometer level, surpassing the resolution limit of traditional lithography technology. However, both technologies rely on electron beam etching to prepare expensive custom templates, and their high costs limit their widespread application. Self-assembly technology relies on the interaction between nanoparticles such as molecules and atoms to spontaneously form specific structures. Although it has unique advantages, there are still challenges in precise control.

[0003] As the demand for micro-nanostructure manufacturing continues to grow, researchers have begun to seek low-cost and easy-to-change design manufacturing methods, and maskless lithography has gradually attracted attention. Maskless lithography technology is mainly divided into charged particle maskless lithography (such as scanning electron beam lithography, focused ion beam lithography) and optical maskless technology (such as DMD maskless lithography, femtosecond laser direct writing, and interference lithography). Although optical maskless technologies such as interference lithography provide a simple and inexpensive method for manufacturing periodic micro-nanostructures, the manufacturing of complex structures is still limited. Although technologies such as femtosecond laser direct writing have high line width resolution, their equipment costs are high, and their point-to-point working mode limits processing efficiency. Digital micromirror device (DMD), as a spatial light modulator, plays a key role in digital light processing (DLP). As a new technology derived from traditional optical lithography, DMD maskless lithography (DMPL) replaces traditional masks with DMD, significantly reducing production costs, shortening production cycles, and providing flexible digital mask design capabilities. Compared with laser direct writing equipment, each micromirror of DMD can be regarded as an independent sub-wave source. By modulating millions of pixels, multi-beam and multi-point simultaneous exposure can be achieved, which significantly improves the exposure efficiency and shows a competitive advantage, especially when manufacturing large-area complex graphics.

[0004] However, DMPL technology also faces many challenges, including the Airy disk problem caused by the diffraction limit, the uneven exposure caused by the gap between DMD pixels, and the trade-off between the exposure area and the line width. To overcome these challenges, researchers have designed more complex optical components, adopted more sophisticated mechanical structures, and replaced higher magnification objective lenses. Although these methods have improved the lithography quality and line width resolution to a certain extent, they have also introduced new problems, such as increased equipment cost, increased operation difficulty, and difficulties in equipment integration and miniaturization. In addition, traditional DMPL-based maskless lithography includes: substrate pretreatment (cleaning and drying); photoresist coating; soft baking (pre-baking); alignment and exposure; post-exposure baking (post-baking); development; hard film baking (hard baking); etching or ion implantation; stripping and other steps, and the process is complicated. Therefore, the development of a simple, flexible, efficient, low-cost maskless lithography technology with high line width resolution to achieve the preparation of micro-nano structures with specific requirements has become an urgent need in the current micro-nano manufacturing field. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a maskless micro-nano structure processing device and processing method, which uses specific photocurable prepolymers to construct various micro-nano structures. Compared with traditional maskless lithography methods, the present invention has the advantages of simplicity, flexibility, high efficiency, low cost and excellent resolution.

[0006] The present invention is implemented in this way, providing a maskless micro-nano structure processing device, including a near-ultraviolet light source, a first collimating lens, a digital micromirror array, a secondary zoom component and an objective lens; the first collimating lens is arranged in front of the light emitting point of the near-ultraviolet light source, the digital micromirror array is arranged on the optical path of the outgoing light of the first collimating lens, the digital micromirror array regulates the incident light according to the internal preset micro-nano structure digital mask information to form an outgoing light with a target pattern, the secondary zoom component is arranged on the optical path of the outgoing light of the digital micromirror array, the objective lens is arranged on the optical path of the outgoing light of the secondary zoom component, and the outgoing light of the objective lens is irradiated on the substrate of the micro-nano structure to be processed.

[0007] Preferably, a feedback component is also included, which includes a visible light source, a second collimating lens, a dichroic mirror, a non-polarizing beam splitter cube, a first lens and a CCD. The second collimating lens is arranged in front of the light emission point of the visible light source, and the light passing through the second collimating lens and the first collimating lens is perpendicular to each other. A dichroic mirror is arranged at the intersection point, and the light coming out of the dichroic mirror is the incident light of the digital micromirror array. The non-polarizing beam splitter cube is arranged on the optical path between the secondary zoom component and the objective lens. The two beams of outgoing light emitted by the non-polarizing beam splitter cube enter the objective lens one way, and the other way passes through the first lens and is projected onto the CCD.

[0008] Further preferably, the visible light source and the near-ultraviolet light source are both provided with hexagonal light homogenizing rods.

[0009] Further preferably, the secondary zoom component (ie, the 4f zoom system) includes a second lens and a third lens, the second lens is arranged on the optical path of the outgoing light of the digital micromirror array, and the third lens is arranged on the optical path of the outgoing light of the second lens.

[0010] Further preferably, a small hole structure is provided between the second lens and the third lens.

[0011] Further preferably, it also includes a first reflector and a second reflector, the first reflector is arranged on the outgoing light path of the first collimating lens, and the light reflected by the first reflector enters the digital micromirror array, and the second reflector is arranged on the outgoing light path of the secondary zoom component, and the light reflected by the second reflector enters the objective lens.

[0012] Further preferably, the +12° reflected light of the digital micromirror array enters the secondary zoom component.

[0013] The present invention also provides a maskless micro-nano structure processing method. Based on the above-mentioned maskless micro-nano structure processing device, the method comprises the following steps: Step 1: Spin coating the photocurable prepolymer evenly on the substrate to ensure the consistency of the thickness of the liquid layer; Step 2: Design digital mask information according to the required micro-nano structure, and load the digital mask information onto the digital micromirror array; Step 3: Turn on the near-ultraviolet light source and the visible light source, collimate the homogenized light beam through the first collimating lens and the second collimating lens respectively, and irradiate the light beam onto the digital micromirror array; Step 4: The digital micromirror array controls the incident light field according to the loaded digital mask information to form an outgoing light field with a specific pattern; Step 5: Projecting the regulated patterned output light onto the surface of the photocurable prepolymer to be exposed through the secondary zoom component, the non-polarizing beam splitter cube, and the objective lens for selective exposure; Step 6: Projecting the optical focus position and the image spot onto the CCD through the non-polarizing beam splitter cube and the first lens, and monitoring the optical focus position and the image spot quality in real time; Step 7: Complete the processing of the micro-nano structure on the substrate according to the preset processing parameters to obtain the desired micro-nano structure.

[0014] Preferably, the photocurable prepolymer comprises the following components: 10-80 parts of monomer, 0.3-2.5 parts of photoinitiator, 0.001-0.85 parts of light absorber, 0.01-1 parts of leveling agent, and the monomer is at least one of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxyethyl acrylate.

[0015] Further preferably, the photoinitiator is at least one of benzophenone, 2,4-dimethylthioxanthone, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethylphosphonate, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and isopropylthioxanthone; and the light absorber is at least one of ultraviolet light absorber UV-327, Sudan Red I, ultraviolet light absorber UV-P, and rhodamine B.

[0016] Compared with the prior art, the advantages of the present invention are: 1. Aiming at the disadvantage that the existing DMPL-based maskless lithography technology needs to use a high-power objective lens and thus introduces large aberrations, the present invention proposes a maskless micro-nano structure processing device, which uses secondary zoom imaging instead of directly using a high-power objective lens for imaging, reduces the field of view of off-axis points, corrects aberrations and improves line width resolution at the same time.

[0017] 2. Aiming at the shortcomings of the traditional DMPL maskless lithography technology, such as complicated process and high cost of micro-nano structure processing, the present invention proposes a maskless micro-nano structure processing method based on secondary scaling, which effectively simplifies the DMPL-based maskless lithography process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A structural diagram of a maskless micro-nanostructure processing device provided by the present invention; Figure 2 It is the digital mask information of the grating micro-nano structure to be processed in Example 1, the grating micro-nano structure prepared by the device and method of the present invention, and the far-field diffraction image of the grating micro-nano structure. DETAILED DESCRIPTION

[0019] The above scheme is further described below in conjunction with specific embodiments. It should be understood that the embodiments are used to illustrate the present invention but are not limited to the application scope of the present invention.

[0020] refer to Figure 1The present invention provides a maskless micro-nano structure processing device, comprising a near-ultraviolet light source 15, a first collimating lens 14, a digital micromirror array 9, a secondary zoom component and an objective lens 2; the first collimating lens 14 is arranged in front of the light emission point of the near-ultraviolet light source 15, the near-ultraviolet light source 15 is used to provide the energy required for photocuring, the digital micromirror array 9 is arranged on the light path of the outgoing light of the first collimating lens 14, the digital micromirror array 9 regulates the incident light according to the internal preset micro-nano structure digital mask information to form an outgoing light with a target pattern, the secondary zoom component is arranged on the light path of the outgoing light of the digital micromirror array 9, the objective lens 2 is arranged on the light path of the outgoing light of the secondary zoom component, and the outgoing light of the objective lens 2 is irradiated on the substrate 1 of the micro-nano structure to be processed. The objective lens 2 can use a 4x to 100x objective lens to achieve further zooming of the digital mask pattern on the digital micromirror array 9.

[0021] For real-time monitoring, the device also includes a feedback component, which includes a visible light source 13, a second collimating lens 12, a dichroic mirror 11, a non-polarizing beam splitter cube 4, a first lens 5 and a CCD6. The second collimating lens 12 is arranged in front of the light emission point of the visible light source 13. The light passing through the second collimating lens 12 and the first collimating lens 14 is perpendicular to each other. The dichroic mirror 11 is arranged at the intersection point. The light coming out of the dichroic mirror 11 is the incident light of the digital micromirror array 9. The non-polarizing beam splitter cube 4 is arranged on the optical path between the secondary zoom component and the objective lens 2. The two beams of outgoing light emitted by the non-polarizing beam splitter cube 4 enter the objective lens 2 in one way, and the other way passes through the first lens 5 and is projected onto the CCD6.

[0022] The substrate 1 is arranged on a three-axis precision translation stage, and the three-axis precision translation stage, the digital micromirror array 9, the near-ultraviolet light source 15, the visible light source 13, and the CCD 6 are all connected to a control system for realizing automatic adjustment of the above components. The visible light source 13 emits visible light which is combined with the near-ultraviolet light source through a dichroic mirror 11 to provide illumination light to assist in the observation and adjustment of the processing process.

[0023] In order to reduce the influence of the irrelevant light of the visible light source 13 on the fabrication of the micro-nano structure, a bandpass filter may be added to the visible light source 13 to ensure its coherence.

[0024] The method for performing maskless micro-nano structure processing using the maskless micro-nano structure processing device comprises the following steps: Step 1: Spin coating the photocurable prepolymer evenly on the substrate 1 to ensure the consistency of the thickness of the liquid layer; Step 2: Design digital mask information according to the required micro-nano structure, and load the digital mask information onto the digital micromirror array 9; Step 3: Turn on the near-ultraviolet light source 15 and the visible light source 13, collimate the homogenized light beam through the first collimating lens 14 and the second collimating lens 12 respectively, and irradiate the homogenized light beam onto the digital micromirror array 9; Step 4: the digital micromirror array 9 controls the incident light field according to the loaded digital mask information to form an outgoing light field with a specific pattern; Step 5: Projecting the regulated patterned output light onto the surface of the photocurable prepolymer to be exposed through the secondary zoom component, the non-polarizing beam splitter cube 4 and the objective lens 2, performing selective exposure to induce free radical polymerization reaction; Step 6: Project the optical focus position and the image spot onto the CCD 6 through the non-polarization beam splitter cube 4 and the first lens 5, and monitor the optical focus position and the image spot quality in real time; Step 7: Complete the processing of the micro-nano structure on the substrate 1 according to preset processing parameters, clean the unpolymerized photocurable prepolymer and impurities on the substrate 1 to obtain the desired micro-nano structure.

[0025] In the present method, the photocurable prepolymer comprises the following components: 10-80 parts of monomer, 0.3-2.5 parts of photoinitiator, 0.001-0.85 parts of light absorber, 0.01-1 parts of leveling agent, the monomer is at least one of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxyethyl acrylate. The photoinitiator is at least one of benzophenone, 2,4-dimethylthioxanthone, (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, (2,4,6-trimethylbenzoyl) ethyl phosphonate, phenyl bis (2,4,6-trimethylbenzoyl) phosphine oxide, and isopropylthioxanthone; the light absorber is at least one of ultraviolet light absorber UV-327, Sudan Red I, ultraviolet light absorber UV-P, and rhodamine B. The present invention has no particular limitation on the type of leveling agent, and a known commercial material capable of reducing the surface tension of the resin may be selected, such as one or a combination of TEGO wet500, TEGO 432, TEGOKL245, TEGO 450, TEGO 410, BYK-302, BYK-361N, BYK-358N, and BYK-310.

[0026] During the processing, the relative position between the digital micromirror array 9 and the objective lens 2 is precisely calibrated by adjusting the three-axis translation stage to ensure processing accuracy and stability.

[0027] In order to make the light emitted by the light source uniform, as an improvement, the visible light source 13 and the near-ultraviolet light source 15 are both provided with hexagonal light homogenizing rods.

[0028] As a specific implementation of the secondary zoom component, the secondary zoom component includes a second lens 8 and a third lens 7 , the second lens 8 is arranged on the outgoing light path of the digital micromirror array 9 , and the third lens 7 is arranged on the outgoing light path of the second lens 8 .

[0029] The secondary zoom component is used to maintain a constant zoom factor within a certain object distance range and reduce the impact of aberrations on resolution.

[0030] Preferably, a pinhole structure is provided between the second lens 8 and the third lens 7 to perform spatial filtering, thereby eliminating the influence of multiple diffraction orders of the digital micromirror array 9.

[0031] In order to optimize the device structure setting, as an improvement of the technical solution, it also includes a first reflector 10 and a second reflector 3. The first reflector 10 is arranged on the outgoing light path of the first collimating lens 14, and the light reflected by the first reflector 10 enters the digital micromirror array 9. The second reflector 3 is arranged on the outgoing light path of the secondary zoom component, and the light reflected by the second reflector 3 enters the objective lens 2.

[0032] Preferably, the digital micromirror array 9 has two working states, respectively called "on state" and "offstate", which are described by a tilt angle of ±12°, where the reflected light at +12° enters the secondary zoom component to generate a digital mask and regulate the incident light field.

[0033] Embodiment 1: A specific example of processing grating micro-nano structure.

[0034] This embodiment takes the processing of grating micro-nano structures as an example to specifically illustrate the application of the present invention. Designing digital mask information of one-dimensional and two-dimensional gratings, such as Figure 2 (a) and Figure 2 (d) The digital mask information is loaded onto the digital micromirror array 9 and processed according to the above method. After the processing is completed, the one-dimensional and two-dimensional grating micro-nano structures are obtained, respectively as shown in Figure 2 (b) and Figure 2 The far-field diffraction test of the processed grating micro-nanostructure was carried out to obtain the far-field diffraction images of the one-dimensional and two-dimensional gratings, respectively. Figure 2 (c) and Figure 2 (f) The test results show that the processed grating micro-nano structure has good diffraction performance, which verifies the effectiveness and accuracy of the present invention.

[0035] The examples described in the present invention are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solutions of the present invention by engineers and technicians in this field should all fall within the protection scope of the present invention.

Claims

1. A maskless micro-nanostructure processing device, characterized in that: The invention comprises a near-ultraviolet light source (15), a first collimating lens (14), a digital micromirror array (9), a secondary zoom component and an objective lens (2); the first collimating lens (14) is arranged in front of a light emission point of the near-ultraviolet light source (15); the digital micromirror array (9) is arranged on an optical path of an outgoing light from the first collimating lens (14); the digital micromirror array (9) controls the incident light according to internal preset micro-nano structure digital mask information to form outgoing light with a target pattern; the secondary zoom component is arranged on an optical path of an outgoing light from the digital micromirror array (9); the objective lens (2) is arranged on an optical path of an outgoing light from the secondary zoom component; and the outgoing light from the objective lens (2) is irradiated on a substrate (1) of a micro-nano structure to be processed.

2. The maskless micro-nanostructure processing device according to claim 1, characterized in that: The invention also comprises a feedback component, which comprises a visible light source (13), a second collimating lens (12), a dichroic mirror (11), a non-polarizing beam splitting cube (4), a first lens (5) and a CCD (6). The second collimating lens (12) is arranged in front of the light emission point of the visible light source (13). Light passing through the second collimating lens (12) and the first collimating lens (14) is perpendicular to each other. A dichroic mirror (11) is arranged at the intersection point. Light coming out of the dichroic mirror (11) is incident light of the digital micromirror array (9). The non-polarizing beam splitting cube (4) is arranged on the optical path between the secondary zoom component and the objective lens (2). Two beams of outgoing light emitted by the non-polarizing beam splitting cube (4) enter the objective lens (2) in one way and pass through the first lens (5) to be projected onto the CCD (6) in the other way.

3. The maskless micro-nanostructure processing device according to claim 2, characterized in that: The visible light source (13) and the near-ultraviolet light source (15) are both provided with hexagonal light homogenizing rods.

4. The maskless micro-nanostructure processing device according to claim 1, characterized in that: The secondary zoom component comprises a second lens (8) and a third lens (7), the second lens (8) being arranged on the optical path of the outgoing light of the digital micromirror array (9), and the third lens (7) being arranged on the optical path of the outgoing light of the second lens (8).

5. The maskless micro-nanostructure processing device according to claim 4, characterized in that: A small hole structure is provided between the second lens (8) and the third lens (7).

6. The maskless micro-nanostructure processing device according to claim 1, characterized in that: It also comprises a first reflector (10) and a second reflector (3), wherein the first reflector (10) is arranged on the optical path of the outgoing light of the first collimating lens (14), and the light reflected by the first reflector (10) enters the digital micromirror array (9), and the second reflector (3) is arranged on the optical path of the outgoing light of the secondary zoom component, and the light reflected by the second reflector (3) enters the objective lens (2).

7. The maskless micro-nanostructure processing device according to claim 1, characterized in that: The +12° reflected light of the digital micromirror array (9) enters the secondary zoom component.

8. A maskless micro-nanostructure processing method, characterized in that: Based on the maskless micro-nanostructure processing device according to claim 2, the method comprises the following steps: Step 1: uniformly coating the photocurable prepolymer on the substrate (1) by spin coating to ensure the consistency of the thickness of the liquid layer; Step 2: Designing digital mask information according to the required micro-nano structure, and loading the digital mask information onto the digital micromirror array (9); Step 3: turning on the near-ultraviolet light source (15) and the visible light source (13), collimating the homogenized light beam through the first collimating lens (14) and the second collimating lens (12) respectively, and irradiating the collimated light beam onto the digital micromirror array (9); Step 4: the digital micromirror array (9) controls the incident light field according to the loaded digital mask information to form an outgoing light field with a specific pattern; Step 5: Projecting the regulated patterned output light onto the surface of the photocurable prepolymer to be exposed through the secondary zoom component, the non-polarizing beam splitter cube (4), and the objective lens (2) for selective exposure; Step 6: Projecting the optical focus position and the image spot onto the CCD (6) through the non-polarizing beam splitter cube (4) and the first lens (5), and monitoring the optical focus position and the image spot quality in real time; Step 7: Complete the processing of the micro-nano structure on the substrate (1) according to the preset processing parameters to obtain the desired micro-nano structure.

9. The maskless micro-nanostructure processing method according to claim 8, characterized in that: The photocurable prepolymer comprises the following components: 10-80 parts of monomer, 0.3-2.5 parts of photoinitiator, 0.001-0.85 parts of light absorber and 0.01-1 parts of leveling agent. The monomer is at least one of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate and hydroxyethyl acrylate.

10. The maskless micro-nanostructure processing method according to claim 9, characterized in that: The photoinitiator is at least one of benzophenone, 2,4-dimethylthioxanthone, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, (2,4,6-trimethylbenzoyl)ethylphosphonate, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and isopropylthioxanthone; the light absorber is at least one of ultraviolet light absorber UV-327, Sudan Red I, ultraviolet light absorber UV-P, and rhodamine B.

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