Electrically-driven imprinting method for generating inclined nanostructure

Abstract

According to the electrically-driven imprinting method for generating the inclined nanostructure, a flexible conductive mold is adopted as an imprinting template, voltage is applied between the flexible conductive mold and a substrate, the moving end of the flexible conductive mold starts to move and starts to make contact with the substrate under the action of an electric field, and under the condition that the included angle between the flexible conductive mold and the substrate is controlled, the inclined nanostructure is generated. The template structure at the contact line deflects under the action of the electric field force to generate an inclined nanostructure, and the inclined nanostructure behind the contact line keeps an inclined state under the action of the electric field force; the contact area of the flexible conductive mold and the substrate is gradually increased until the flexible conductive mold completely covers the substrate; in the contact process of the flexible conductive mold and the substrate, the imprint glue is completely filled in a micro-cavity of the flexible conductive mold under the driving action of electric field force, and a complete inclined nano-structure is formed; the large-area inclined nanostructure is directly and controllably generated by using the easily obtained flexible conductive mold with the vertical structure, the method can be compatible with a semiconductor process, and the preparation mode is simple.

Description

Technical Field

[0001] The present invention belongs to the field of micro-nano manufacturing technology, and in particular relates to an electrically driven imprinting method for generating inclined nanostructures. Background Art

[0002] Tilted nanostructures, with their unique asymmetric geometry, transcend the limitations of traditional structures, demonstrating exceptional performance in optics, electricity, magnetism, and mechanics. From enhancing light-matter interactions to improving energy conversion efficiency, and from regulating surface functionality to optimizing structural mechanics, they lay the foundation for the development of high-performance devices. Tilted nanostructures, with their combined functionality and integration, are driving technological advancements in photonics, sensing, biomedicine, and other fields, becoming a critical bridge connecting nanoscale innovation with macroscale device requirements. They hold broad application prospects in future scenarios such as smart devices, precision medicine, and green energy. In particular, in the field of augmented reality (AR) displays, tilted nanogratings enable efficient light coupling and polarization manipulation, becoming a core technology for AR displays. Traditional AR devices rely on heavy optical components, but tilted gratings, with their high coupling efficiency and thinness and wide field of view, address the conflict between device miniaturization and display quality. They are recognized as the optimal optical solution for the next generation of smart devices, propelling AR technology from industrial applications to consumer products.

[0003] The huge application potential shown by tilted nanostructures is continuously promoting the advancement of related manufacturing technologies and in-depth research. At present, photolithography technology (extreme ultraviolet lithography and electron beam lithography) and tilted etching (tilted deposition) processes are the most commonly used methods for manufacturing tilted structures. However, this type of method has fundamental limitations: its process characteristics can usually only be used for the preparation of small-sized samples with a fixed, single tilt angle, and its flexibility and designability are insufficient. In addition, the entire process involves multiple steps (exposure, development, etching / deposition, etc.), which not only makes the process complex and the cycle long, but also leads to high manufacturing costs, limiting its competitiveness in large-scale applications.

[0004] In order to overcome the multi-step limitation, researchers have explored methods such as femtosecond laser direct writing and focused ion beam (FIB) cutting / milling to directly manufacture tilted nanostructures. These technologies can theoretically achieve "one-step molding", which greatly simplifies the process ([1]Chen Z,Yu Q,Shimada K,et al.High-precision and high-efficiencyfabrication ofblazed grating by ultrasonic-assisted ultraprecision planing.J.Mater.Process.Technol.[J],2023,311(117802.[2]Roeder M,Thiele S,Hera D,etal.Fabrication of curved diffractive optical elements by means of laserdirect writing,electroplating,and injection compression molding.J.Manuf.Process.[J],2019,47(402-409.[3]Shen C,Tan X,Jiao Q,etal.Convex blazed grating of high diffraction efficiency fabricated by swingion-beam etching method.Optics Express[J],2018,26(19):25381-25398); however, they are essentially serial processing modes (point-by-point or line-by-line scanning), resulting in extremely slow manufacturing speed and low efficiency, which is completely unsuitable for mass production needs, and their resolution is also limited.Utilizing the self-organizing properties of molecules or nanoparticles (such as block copolymer microphase separation and tilted deposition self-shadowing effect) to form tilted structures ([4]Li F, Wang K, Deng N, et al. Self-assembly of polymer end-tethered gold nanorods into two-dimensional arrays with tunable tilt structures. ACS Appl. Mater. Interfaces[J], 2021, 13(5): 6566-6574.) theoretically has the advantages of low cost and potential high throughput; however, the inherent randomness of the self-assembly process makes it difficult to avoid structural defects (such as dislocations, grain boundaries, and size / angle inhomogeneities), and the controllability and repeatability are poor, making it difficult to meet the application standards of optical imaging, which require extremely high structural accuracy and consistency. Nanoimprint lithography is a high-throughput, low-cost, high-resolution graphic replication technology. In theory, it is very suitable for large-scale replication of tilted nanostructures ([5] Wang C, Fan Y, Shao J, et al. Discretely-supported nanoimprint lithography for patterning the high-spatial-frequency stepped surface. Nano Research [J], 2021, 14 (2606-2612. [6] Fan Y, Wang C, Sun J, et al. Electric-driven flexible-roller nanoimprint lithography on the stress-sensitive warped wafer. Int. J. Extrem. Manuf. [J], 2023, 5(3): 035101.); However, traditional nanoimprint technology is essentially a replication process that is highly dependent on the quality and availability of the original template. The production of large-area, high-precision nanoimprint templates with complex tilt angles itself returns to the inherent difficulties of the aforementioned photolithography / etching process—that is, how to efficiently, cost-effectively, and with high fidelity produce large-area original tilted nanostructure templates. Therefore, how to achieve "source-generated manufacturing" of large-area, controllable tilted nanostructures remains a major challenge. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an electrically driven imprinting method for generating inclined nanostructures, which uses a flexible conductive mold with an easily available vertical structure to directly and controllably generate large-area inclined nanostructures, is compatible with semiconductor processes, and has a simple preparation method.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An electrically driven imprinting method for generating tilted nanostructures comprises the following steps:

[0008] 1) Installation and control of the flexible conductive mold 1: The movable end 1-a of the flexible conductive mold 1 is fixed to a fixture at a certain height above the substrate plane and moves with the fixture; the fixed end 1-b of the flexible conductive mold 1 is fixed on the same plane as the substrate 2 and is in close contact with the substrate 2. The angle between the flexible mold 1 and the substrate 2 is controlled by controlling the position and relative motion of the movable end 1-a;

[0009] 2) Mounting of the sample to be processed: The substrate 2 coated with the embossing adhesive 3 is fixed on the wafer stage;

[0010] 3) External electric field loading: applying a voltage 4 between the flexible conductive mold 1 and the substrate 2 to form an electrode pair;

[0011] 4) Continuous generative imprinting of flexible conductive molds: The mobile end 1-a of the flexible conductive mold 1 begins to move, gradually releasing the flexible conductive mold 1 and beginning to contact the substrate 2 under the action of the electric field. While controlling the angle between the flexible conductive mold 1 and the substrate 2, the template structure 1-A at the contact line deflects to the intermediate form 1-B under the action of the electric field force, ultimately generating an inclined nanostructure 1-C. The inclined nanostructure 1-C behind the contact line remains inclined under the action of the electric field force. As the contact area between the flexible conductive mold 1 and the substrate 2 gradually increases, it completely covers the substrate 2. During the contact process between the flexible conductive mold 1 and the substrate 2, the driving effect of the electric field force causes the imprinted glue 3 to completely fill the microcavity of the flexible conductive mold 1, forming a complete inclined nanostructure.

[0012] 5) Curing: The liquid imprint adhesive is completely cured and voltage 4 is turned off;

[0013] 6) Peel-off demoulding: The moving end 1 - a of the flexible conductive mold 1 moves in the opposite direction to the imprinting direction, so that the flexible conductive mold 1 is gradually peeled off from the substrate 2 , and the imprinting process is completed.

[0014] The flexible conductive mold 1 is composed of a backing layer 1-1, a transparent conductive layer 1-2 and a structural layer 1-3.

[0015] The size of the fixing fixture of the moving end 1-a of the flexible conductive mold 1, the height from the substrate plane, and the relative position should be determined according to the actual size of the sample to be processed; the speed of each moving mechanism should be determined according to the design of the efficiency of the stamping and the prevention of defects.

[0016] The structural deflection on the flexible conductive mold 1 to generate an inclined nanostructure is the result of the combined action of the electric field force and the angle between the flexible conductive mold 1 and the substrate 2. The angle between the flexible conductive mold 1 and the substrate 2 determines the initial contact state between the structure on the flexible conductive mold 1 and the substrate 2, which is the basis for the generation of the inclined structure; and the electric field force provides the power for the generation of the inclined structure.

[0017] The angle between the flexible conductive mold 1 and the substrate 2 is determined according to the tilt angle requirement for generating the tilted nanostructure. When the electric field is fixed, the greater the tilt angle of the required tilted structure, the greater the angle between the two, and vice versa.

[0018] The angle between the flexible conductive mold 1 and the substrate 2 is adjusted in real time by the position and relative motion state of the moving end 1-a of the flexible conductive mold 1, and the adjustment range is determined by the thickness of the flexible conductive mold 1 and the applied voltage 4.

[0019] The voltage 4 applied between the flexible conductive mold 1 and the substrate 2 is determined according to the dielectric constant between the two electrodes and the electric field force required to generate the inclined nanostructure, and cannot exceed the breakdown voltage.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention can directly generate inclined nanostructures by utilizing readily available vertical nanostructures by controlling the angle between the flexible conductive mold 1 and the substrate 2, and the preparation method is simple.

[0022] 2. The present invention can customize the generation of tilted nanostructures by precisely controlling the electric field intensity, the angle between the flexible conductive mold 1 and the substrate 2, and the electric field intensity, thereby achieving precise control of the tilt angle of the tilted structure.

[0023] 3. In the present invention, under the action of the electric field and the motion mechanism, the flexible conductive mold 1 is extended on the plane of the substrate 2 in the form of line contact. The uniform electric field force can ensure the overall uniformity of the sample and realize the preparation of large-area inclined nanostructures.

[0024] 4. During the imprinting process, the present invention can flexibly control the inclination angle of the generated inclined nanostructure by real-time control of the angle between the flexible conductive mold 1 and the substrate 2, thereby being able to prepare various types of inclined nanostructures such as uniform inclination, large inclination angle, and gradient inclination. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1Schematic diagram of the method flow of an embodiment of the present invention; (a) is a schematic diagram of the inclined nanostructure generation type imprinting, in which the enlarged area represents the transformation process of the vertical structure of the flexible conductive mold 1 to generate an inclined structure; (b) is a schematic diagram of the imprinting curing step; (c) is a schematic diagram of the peeling demoulding; (d) is a schematic diagram of the inclined nanostructure prepared by imprinting.

[0026] Figure 2 This is a schematic diagram of the expanded preparation of different types of inclined nanostructures using the same flexible conductive mold 1 according to an embodiment of the present invention; (a) is a schematic diagram of the vertical structure of the flexible conductive mold 1; (b) is a schematic diagram of the prepared uniformly inclined nanostructure; (c) is a schematic diagram of the prepared nanostructure with a large inclination angle; and (d) is a schematic diagram of the prepared gradient-inclined nanostructure.

[0027] Figure 3 Schematic diagram of the manufacture of the flexible conductive mold 1 according to an embodiment of the present invention; (a) is a schematic diagram of the backing layer; (b) is a schematic diagram of the preparation of a transparent conductive layer on the backing layer; (c) is a schematic diagram of the master mold after low surface energy treatment; (d) is a schematic diagram of the master mold after spin coating the liquid material of the structural layer; (e) is a schematic diagram of the bonding and curing of the backing layer and the structural layer; and (g) is a schematic diagram of the flexible conductive mold after demolding.

[0028] Figure 4 This is a physical diagram of the flexible conductive mold 1 and the generation of various inclined nanostructures according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0030] Reference Figure 1 A method for generating tilted nanostructures by electrically driven imprinting is proposed. The core of the method is the precise real-time control of the contact state and process between the flexible conductive mold and the substrate. The method includes the following steps:

[0031] 1) Installation and control of the flexible conductive mold 1: The mobile end 1-a of the flexible conductive mold 1 is fixed to a fixture at a certain height above the substrate plane and moves with the fixture; the fixed end 1-b of the flexible conductive mold 1 is fixed on the same plane as the substrate 2 and is in close contact with the substrate 2. By controlling the position and relative motion of the mobile end 1-a, the angle between the flexible mold 1 and the substrate 2 can be controlled, thereby achieving precise real-time control of the contact state between the two.

[0032] like Figure 1 As shown in (a), in this embodiment, the movable end 1-a of the flexible conductive mold 1 is fixed on a roller with a height of 120 mm and a diameter of 70 mm from the plane of the substrate 2, and the fixed end of the flexible conductive mold 1 is fixed on the plane of the substrate 2;

[0033] 2) Mounting of the sample to be processed: The substrate 2 coated with the embossing adhesive 3 is fixed on the wafer stage;

[0034] In this embodiment, the substrate 2 of the 4-inch silicon wafer sample coated with 1000nm UV-curable nanoimprint adhesive 3 is sucked onto the wafer stage under the action of negative pressure;

[0035] 3) External electric field loading: applying a voltage 4 between the flexible conductive mold 1 and the substrate 2 to form an electrode pair;

[0036] 4) Continuous generative imprinting of flexible conductive molds: The mobile end 1-a of the flexible conductive mold 1 begins to move, gradually releasing the flexible conductive mold 1 and beginning to contact the substrate 2 under the action of the electric field. While controlling the angle between the flexible conductive mold 1 and the substrate 2, the template structure 1-A at the contact line deflects to the intermediate form 1-B under the action of the electric field force, ultimately generating an inclined nanostructure 1-C. The inclined nanostructure 1-C behind the contact line remains inclined under the action of the electric field force. Over time, the contact area between the flexible conductive mold 1 and the substrate 2 gradually increases until it completely covers the substrate 2. During the contact process between the flexible conductive mold 1 and the substrate 2, the driving effect of the electric field force causes the imprinted adhesive 3 to completely fill the microcavity of the flexible conductive mold 1, forming a complete inclined nanostructure.

[0037] 5) Curing: The liquid imprint adhesive is completely cured and voltage 4 is turned off;

[0038] This embodiment Figure 1 As shown in (b), after the flexible conductive mold 1 and the substrate 2 are in full contact, UV exposure is performed for 30 seconds, the imprint glue 3 is completely cured, and the electric field 4 is turned off;

[0039] 6) Peel-off demoulding: Figure 1 As shown in (c), the moving end 1-a of the flexible conductive mold 1 moves in the opposite direction to the stamping, so that the flexible conductive mold 1 is gradually peeled off from the substrate 2; Figure 1 As shown in (d), the complete peel-off demoulding is completed and the imprinted inclined nanostructured sample is completed.

[0040] Reference Figure 2 , through real-time control of the contact state and process between the flexible conductive mold 1 and the substrate 2, different types of tilted nanostructures can be generated:

[0041] (1) Figure 2 (a) is a schematic diagram of the structure of a vertical flexible conductive mold 1 with a line width of 700 nm, a period of 2 μm, an aspect ratio of 2.5, and a duty cycle of 0.5;

[0042] (2) Figure 2(b) is a schematic diagram of a uniformly inclined nanostructure 3-1 with an inclination angle of 20° prepared when the voltage intensity is 600 V and the angle between the flexible conductive mold 1 and the substrate 2 is 25°;

[0043] (c) Figure 2 (c) is a schematic diagram of a uniformly tilted nanostructure 3-2 with a tilt angle of 40° prepared by four-step generative imprinting at a voltage of 400 V and an angle of 25° between the flexible conductive mold 1 and the substrate 2;

[0044] (d) Figure 2 Middle (d) is a schematic diagram of the prepared gradient-tilted nanostructure 3-3 with an electric field strength of 600 V, an angle between the flexible conductive mold 1 and the substrate 2 of 25° at the initial moment and 10° at the subsequent moment. The initial tilt angle is 20° and then gradually changes to 0°.

[0045] Reference Figure 3 The flexible conductive mold 1 is composed of a backing layer 1-1, a transparent conductive layer 1-2 and a structural layer 1-3, and its preparation steps are as follows:

[0046] (1) Figure 3 As shown in (a), a PET material with a thickness of 30 μm is prepared as the backing layer 1-1 of the flexible conductive mold 1;

[0047] (2) Figure 3 As shown in (b), a transparent conductive layer 1-2 of silver nanowires is prepared on the backing layer 1-1 by a doctor blade coating process;

[0048] (3) Figure 3 As shown in (c), a silicon master mold 5 is prepared by electron beam lithography and etching process, and a 10 nm layer of octafluorocyclobutane (C4F8) is deposited on the structure surface of the master mold 5 for hydrophobic treatment to reduce its surface energy;

[0049] (4) Figure 3 As shown in (d), the liquid working mold material is spin-coated on the master mold 5 at a speed of 2000 rpm / 60s to form liquid structural layers 1-3;

[0050] (5) Figure 3 As shown in (e), the backing layer 1-1 and the liquid structural layer 1-3 are bonded together, and UV curing is performed for 90 seconds to completely cure the liquid structural layer 1-3 material and bind it to the backing layer 1-1;

[0051] (6) Figure 3 As shown in (f), the flexible conductive mold 1 is demoulded from the mother mold 5 and the preparation is completed.

[0052] In this embodiment, the flexible conductive mold 1 with the same vertical structure is used respectively according to Figure 2 The experimental parameters were adjusted to prepare nanostructures with different inclinations, such as Figure 4 As shown, there are uniformly inclined nanostructures with an inclination angle of 20°, large-angle inclined nanostructures with an inclination angle of 40°, and gradient inclined nanostructures that gradually change from 20° to 0°, indicating that the inclined nanostructures have excellent sharpness and uniformity.

Claims

1. An electrically driven imprinting method for generating inclined nanostructures, characterized by: The following steps are involved: 1) Installation and control of the flexible conductive mold (1): The movable end (1-a) of the flexible conductive mold (1) is fixed on a fixture at a certain height from the substrate plane and moves with the fixture; the fixed end (1-b) of the flexible conductive mold (1) is fixed on the same plane as the substrate (2) and is in close contact with the substrate (2); by controlling the position and relative motion state of the movable end (1-a), the angle between the flexible mold (1) and the substrate (2) is controlled; 2) Mounting of the sample to be processed: The substrate (2) coated with the embossing adhesive (3) is fixed on the wafer stage; 3) External electric field loading: applying a voltage (4) between the flexible conductive mold (1) and the substrate (2) to form an electrode pair; 4) Continuous generation-type imprinting of a flexible conductive mold: the moving end (1-a) of the flexible conductive mold (1) starts to move, so that the flexible conductive mold (1) is gradually released and starts to contact with the substrate (2) under the action of the electric field. Under the control of the angle between the flexible conductive mold (1) and the substrate (2), the template structure (1-A) at the contact line is deflected to an intermediate form (1-B) under the action of the electric field force, and finally an inclined nanostructure (1-C) is generated. The inclined nanostructure (1-C) behind the contact line remains in an inclined state under the action of the electric field force; as the contact area between the flexible conductive mold (1) and the substrate (2) gradually increases, until the substrate (2) is completely covered; in the process of the flexible conductive mold (1) and the substrate (2) being in contact, the driving action of the electric field force causes the imprinting glue (3) to completely fill the microcavity of the flexible conductive mold (1), forming a complete inclined nanostructure; 5) Curing: The liquid imprint adhesive is completely cured and the voltage is turned off (4); 6) Peel-off demoulding: The moving end (1-a) of the flexible conductive mold (1) moves in the opposite direction to the imprinting direction, so that the flexible conductive mold (1) is gradually peeled off from the substrate (2), and the imprinting process is completed.

2. The method according to claim 1, wherein: The flexible conductive mold (1) consists of a backing layer (1-1), a transparent conductive layer (1-2) and a structural layer (1-3).

3. The method according to claim 1, wherein: The size of the fixing fixture of the moving end (1-a) of the flexible conductive mold (1), the height from the substrate plane, and the relative position are determined according to the size of the actual sample to be processed; the speed of each moving mechanism is determined according to the efficiency of the stamping and the prevention of defects.

4. The method according to claim 1, wherein: The deflection of the structure on the flexible conductive mold (1) to generate the inclined nanostructure is the result of the combined action of the electric field force and the angle between the flexible conductive mold (1) and the substrate (2), wherein the angle between the flexible conductive mold (1) and the substrate (2) determines the initial contact state between the structure on the flexible conductive mold (1) and the substrate (2), and the electric field force provides the driving force for the generation of the inclined structure.

5. The method according to claim 1, wherein: The angle between the flexible conductive mold (1) and the substrate (2) is determined according to the tilt angle requirement for generating the tilted nanostructure. When the electric field is fixed, the greater the tilt angle of the required tilted structure, the greater the angle between the two, and vice versa.

6. The method according to claim 1, wherein: The angle between the flexible conductive mold (1) and the substrate (2) is adjusted in real time by the position and relative motion state of the moving end (1-a) of the flexible conductive mold (1), and the adjustment range is determined by the thickness of the flexible conductive mold (1) and the applied voltage (4).

7. The method according to claim 1, wherein: The voltage (4) applied between the flexible conductive mold (1) and the substrate (2) is determined according to the dielectric constant between the two electrodes and the electric field force required to generate the inclined nanostructure, and cannot exceed the breakdown voltage.

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