A double-sided imprint forming method and double-sided micro-nano structure element

Abstract

The present application belongs to the field of micro-nano forming technology, and particularly relates to a double-sided imprint forming method and a double-sided micro-nano structure element. The double-sided imprint forming method comprises the following steps: mold making, preparing a patterned substrate, the patterned substrate having a pattern surface, processing an alignment structure on the pattern surface, and processing a micro-nano structure on the pattern surface according to the alignment structure; edge cutting, cutting off an edge of the patterned substrate along a first direction according to the alignment structure and forming a first positioning surface; cutting off another edge of the patterned substrate along a second direction and forming a second positioning surface, so that the patterned substrate is processed into a forming mold; and forming, preparing a positioning sleeve having a positioning cavity, spacing and stacking two forming molds in the positioning cavity, and pressing the two forming molds, so as to form a double-sided micro-nano structure element from a blank. The present application can align two pattern areas formed on the upper and lower surfaces of the double-sided micro-nano structure element with high precision, and effectively improves the forming precision of the blank in the double-sided micro-nano structure processing process.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano forming technology, and particularly relates to a double-sided imprinting forming method and a double-sided micro-nano structure element. Background Technology

[0002] Double-sided micro / nanostructures, such as double-sided microlens arrays, have been widely used in beam homogenization systems, optical communication systems, and sensors. Anti-reflection beam-splitting gratings (which have a beam-splitting grating structure on one side and an anti-reflection nanostructure on the other) can be applied in laser processing systems, optical measurement systems, and spectrometers. In recent years, with social development and technological advancements, the demand for double-sided micro / nanostructures has increased significantly, not only in terms of shape accuracy but also in quantity.

[0003] Special applications such as lightweight aerospace optical components and short-wavelength refractive optical components demand ultra-thin double-sided micro / nanostructures, with thicknesses sometimes as thin as 20 micrometers. In the fabrication of these ultra-thin double-sided micro / nanostructures, double-sided micromilling removes material using shearing forces, which can easily lead to component deformation and breakage; double-sided ultrafast laser ablation offers poor depth control and creates heat-affected zones, resulting in perforation or thermal deformation; double-sided ion beam milling has extremely low efficiency; and double-sided photolithography-etching requires self-support for ultra-thin components and introduces significant differences in mechanical stress, potentially leading to component warping and structural deformation.

[0004] Double-sided micro / nano imprinting utilizes axial pressure to plastically shape ultra-thin components, effectively solving the warping and bending problems in the manufacturing process. Furthermore, it allows for controllable thickness control and an environmentally friendly manufacturing process. However, the alignment accuracy of the upper and lower templates directly affects the processing quality of the double-sided micro / nano structure components during double-sided imprinting. Therefore, the critical issue of high-precision double-sided alignment urgently needs to be addressed. Summary of the Invention

[0005] The purpose of this application is to provide a double-sided embossing forming method, which aims to solve the problem of how to improve alignment accuracy and forming quality of blanks.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, a double-sided embossing method is provided, which includes the following steps:

[0008] The process involves molding a patterned substrate with a patterned surface, fabricating an alignment structure on the patterned surface, and fabricating micro / nano structures on the patterned surface based on the alignment structure.

[0009] Edge trimming: According to the alignment structure, one edge of the patterned substrate is trimmed along a first direction to form a first positioning surface; another edge of the patterned substrate is trimmed along a second direction to form a second positioning surface, so that the patterned substrate is processed into a forming template, wherein the first direction and the second direction are arranged alternately.

[0010] Forming: Prepare a positioning sleeve with a positioning cavity; place two forming templates at intervals in the positioning cavity, with the two patterned surfaces facing each other; make both first positioning surfaces abut against one inner wall of the positioning cavity, and make both second positioning surfaces abut against the other inner wall of the positioning cavity; place the blank between the two forming templates and in a plastic state; press the two forming templates together to form the blank into a double-sided micro / nano structure element.

[0011] In some embodiments, the trimming includes the following steps:

[0012] The first coarse cut is performed by removing the edge of the patterned substrate along a first direction to form a first cut surface. The distance from the first cut surface to the alignment structure along the second direction is a first predetermined value.

[0013] The first fine-cut edge is cut off along the first direction to form the first positioning surface, which intersects the patterned surface and has a first intersection line, which intersects the alignment structure.

[0014] In some embodiments, the cutting edge further includes the following steps:

[0015] The second coarse cut is performed by removing another edge of the patterned substrate along the second direction to form a second cut surface. The distance from the second cut surface to the alignment structure along the first direction is a second predetermined value.

[0016] A second fine-cut edge is made by cutting off another edge of the patterned substrate along a second direction to form a second positioning surface. The second positioning surface intersects the patterned surface and has a second intersection line, which intersects the alignment structure.

[0017] In some embodiments, the alignment structure includes a plurality of alignment marks, the plurality of alignment marks being spaced apart and collinearly arranged along a first direction, and the plurality of alignment marks being spaced apart and collinearly arranged along a second direction; the first intersecting line intersects each corresponding alignment mark in sequence; the second intersecting line intersects each corresponding alignment mark in sequence.

[0018] In some embodiments, the first intersecting lines intersect at the same position of each of the alignment marks, and the second intersecting lines intersect at the same position of each of the alignment marks.

[0019] In some embodiments, the forming process includes the following steps:

[0020] Heating: The billet is heated to a predetermined temperature using a heating module;

[0021] Hot pressing applies downward pressure to the forming template located above, causing the two surfaces of the blank to replicate the micro-nano structures of the two forming templates respectively;

[0022] Cooling is achieved by blowing cooling gas onto the positioning sleeve to cool the positioning sleeve, the two forming templates, and the double-sided micro / nano structure element.

[0023] Demolding separates the positioning sleeve and the two forming templates.

[0024] In some embodiments, an elastic component is prepared, which connects to the positioning sleeve and abuts against the two forming templates. The elastic component is used to press the two first positioning surfaces against one inner wall of the positioning sleeve and press the two second positioning surfaces against the other inner wall of the positioning sleeve.

[0025] In some embodiments, the elastic component includes a plurality of ball-head locking plungers, the positioning sleeve has a first threaded hole arranged along the first direction and a second threaded hole arranged along the second direction, and each of the forming templates has at least one first threaded hole and one second threaded hole; one end of one ball-head locking plunger is screwed into the first threaded hole, and the other end abuts against the corresponding forming template; one end of another ball-head locking plunger is screwed into the second threaded hole, and the other end abuts against the corresponding forming template.

[0026] In some embodiments, the forming template is a rectangular plate, the forming template has a first side surface disposed opposite to the first positioning surface and a second side surface disposed opposite to the second positioning surface; the second side surface is machined with the first positioning surface as a reference surface to form a third positioning surface; the first side surface is machined with the second positioning surface as a reference surface to form a fourth positioning surface, and the cross-sectional shape of the positioning cavity is adapted to the shape of the forming template.

[0027] Secondly, a double-sided micro / nano structure element is provided, which is prepared using the double-sided imprinting method.

[0028] The beneficial effects of this application are as follows: By processing alignment structures and micro / nano structures on the patterned surface of a patterned substrate, and cutting the two side surfaces of the patterned substrate along the first and second directions respectively, the cut edges form the first and second positioning surfaces. Since the two first positioning surfaces are positioned based on the same inner wall of the positioning sleeve, and the two second positioning surfaces are positioned based on the same inner wall of the positioning sleeve, it is ensured that the patterned area of ​​the upper forming template and the patterned area of ​​the lower forming template are aligned with high precision in the vertical direction. During the hot pressing process, the upper first positioning surface is guided to move by one inner wall of the positioning sleeve, and the upper second positioning surface is also guided to move by the other inner wall of the positioning sleeve. This ensures that the upper hot pressing mold remains aligned with the lower hot pressing mold as it moves downwards, ultimately enabling the two patterned areas formed on the upper and lower surfaces of the double-sided micro / nano structure element to be aligned with high precision, effectively improving the forming accuracy of the blank during the processing of the double-sided micro / nano structure. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or exemplary technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of the double-sided embossing method provided in the embodiments of this application;

[0031] Figure 2 This is a schematic diagram illustrating the principle of the first and second coarse cutting edges of a patterned substrate provided in another embodiment of this application;

[0032] Figure 3 yes Figure 2 A schematic diagram illustrating the principle of the first and second precision cutting edges of the patterned substrate;

[0033] Figure 4 This is a schematic diagram illustrating the principle of the first and second coarse cutting edges of the patterned substrate provided in another embodiment of this application;

[0034] Figure 5 yes Figure 4 A schematic diagram illustrating the principle of the first and second precision cutting edges of the patterned substrate;

[0035] Figure 6 This is an assembly diagram of the positioning sleeve and forming template provided in another embodiment of this application;

[0036] Figure 7 This is an assembly diagram of the positioning sleeve and forming template provided in another embodiment of this application;

[0037] Figure 8 This is an assembly diagram of the positioning sleeve and forming template provided in another embodiment of this application;

[0038] Figure 9 yes Figure 8 A cross-sectional view along the AA direction;

[0039] Figure 10 These are scanning electron microscope images of the micro-nano structures on the upper and lower surfaces of the glass anti-reflection beam splitter element.

[0040] Figure 11 This is a graph showing the diffraction efficiency measurement results of a glass anti-reflection beam splitter element;

[0041] Figure 12 These are scanning electron microscope images of the first and second positioning edges of the silicon carbide forming template.

[0042] Figure 13 This is an optical micrograph of the front of a beryllium-based double concave parabolic microlens array;

[0043] Figure 14 yes Figure 13 A partial view of the microlens array at point A, wherein, Figure 14 The image at the top center is a three-dimensional topographic map. Figure 14 The image at the bottom center is a shape outline diagram;

[0044] Figure 15 yes Figure 13 Optical micrograph of the back side of a double concave parabolic microlens array;

[0045] Figure 16 yes Figure 15 A partial view of the microlens array at point B, wherein, Figure 16 The image at the top center is a three-dimensional topographic map. Figure 16 The image at the bottom center is a shape outline.

[0046] The following are the labeling elements in the figure:

[0047] 10. Patterned substrate; 20. Alignment structure; 21. Alignment mark; 211. Microgroove; 33. Patterned surface; 31. Patterned area; 32. Micro / nano structure; 101. First positioning surface; 102. Second positioning surface; 103. First side surface; 104. Second side surface; 11. First intersection line; 12. Second intersection line; 110. Forming template; 120. Press head; 130. Heating module; 140. Base plate; 150. Positioning sleeve; 200. Blank; 40. Elastic component; 41. Push plate; 42. Tube spring; 43. Ball head retaining plunger. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the scope of this application.

[0049] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly or indirectly attached to that other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to that other component. The terms "upper," "lower," "left," "right," etc., indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, and are for ease of description only, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. "A plurality" means two or more, unless otherwise explicitly defined.

[0050] Please see Figures 1 to 3 This application provides a method for double-sided imprinting and for fabricating a double-sided micro / nano structure element from a blank 200 using this method. The blank 200 can be made of metal (such as lithium, beryllium, aluminum, nickel, copper, silver, gold), oxide glass, infrared glass, plastic, etc., and the oxide glass can be BK7. The thickness of the blank 200 ranges from 10 to 2000 micrometers.

[0051] Please see Figures 4 to 6 The double-sided embossing method includes the following steps:

[0052] S1: Molding. A patterned substrate 10 is prepared, which has a patterned surface 33. An alignment structure 20 is fabricated on the patterned surface 33, and a micro / nano structure 32 is fabricated on the patterned surface 33 based on the alignment structure 20. It can be understood that the patterned surface 33 has a patterned area 31, which is rectangular, circular, or elliptical in shape. In this embodiment, it is rectangular, and the micro / nano structure 32 is located in the patterned area 31. Alternatively, the micro / nano structure 32 can be fabricated on the patterned area 31 first, and then the alignment structure 20 can be fabricated based on the patterned area 31.

[0053] In other words, the alignment structure 20 and the micro / nano structure 32 are processed according to the same reference. For example, high-resolution machine vision can be used to locate the patterned area 31 of the micro / nano structure 32 on the patterned substrate 10, and then the alignment structure 20 can be processed on the patterned substrate 10 using a femtosecond laser based on the patterned area 31.

[0054] The micro / nano structure 32 is an array structure, for example, it may include multiple trenches or micropores with a size of micrometer, and / or multiple trenches or micropores with a size of nanometer.

[0055] S2: Edge trimming. According to the alignment structure 20, one edge of the patterned substrate 10 is trimmed along the first direction to form a first positioning surface 101, and the other edge of the patterned substrate 10 is trimmed along the second direction to form a second positioning surface 102, so that the patterned substrate 10 is processed into a forming template 110. The first and second directions are arranged alternately. It can be understood that the first positioning surface 101 and the second positioning surface 102 are respectively located on two side surfaces of the forming template 110. In this embodiment, the first and second directions are orthogonal, and the included angle between the first positioning surface 101 and the second positioning surface 102 is 90 degrees. The first direction can be represented as X, the second direction can be represented as Y, and the vertical direction can be represented as Z.

[0056] S3: Forming. A positioning sleeve 150 with a positioning cavity is prepared. Two forming templates 110 are placed alternately and stacked in the positioning cavity, with the two patterned surfaces 33 facing each other. Both first positioning surfaces 101 abut against one inner wall of the positioning cavity, and both second positioning surfaces 102 abut against the other inner wall of the positioning cavity. The blank 200 is placed between the two forming templates 110 and is in a plastic state. The two forming templates 110 are pressed together to form the blank 200 into a double-sided micro / nano structure element. It can be understood that the blank 200 in a plastic state can have its surface material flow under external force, thereby replicating the micro / nano structure 32 on the forming template 110 to process grooves or protrusions on the blank 200.

[0057] It is understandable that the lower forming template 110 is fixedly set, and the upper forming template 110 moves downward and simultaneously imprints the blank 200. For example, the blank 200 is made of soft plastic. Through the material flow on the upper and lower surfaces of the plastic, the upper and lower surfaces of the blank 200 respectively replicate the micro-nano structures 32 on the two forming templates 110.

[0058] Please see Figures 1 to 6 For ease of description, the positioning cavity has a first inner wall and a second inner wall. The first inner wall positions two first positioning surfaces 101, and the second inner wall positions two second positioning surfaces 102. The planes defined by the first and second inner walls are perpendicular. The first and second inner walls are mirror-polished to reduce the interfacial friction between the upper and lower forming templates 110 and the positioning sleeve 150 during the imprinting process. This ensures that after forming, the micro-nano structures 32 on the upper surface of the double-sided micro-nano structure element are aligned with the micro-nano structures 32 on the lower surface of the double-sided micro-nano structure element, i.e., the optical axis of the pattern area 31 on the upper surface of the double-sided micro-nano structure element coincides with the optical axis of the pattern area 31 on the lower surface of the double-sided micro-nano structure element.

[0059] Please see Figures 1 to 6 In this embodiment, an alignment structure 20 and a micro / nano structure 32 are fabricated on the patterned surface 33 of the patterned substrate 10. The two side surfaces of the patterned substrate 10 are cut along the first and second directions respectively, and the cut edges form a first positioning surface 101 and a second positioning surface 102. Since the two first positioning surfaces 101 are positioned based on the first inner wall of the positioning sleeve 150 and the two second positioning surfaces 102 are positioned based on the second inner wall of the positioning sleeve 150, it is ensured that the patterned area 31 of the upper forming template 110 and the patterned area 31 of the lower forming template 110 are aligned with high precision in the vertical direction. During the hot pressing process, the first positioning surface 101 located above is guided to move by the first inner wall of the positioning sleeve 150, and the second positioning surface 102 located above is guided to move by the second inner wall of the positioning sleeve 150. This ensures that the upper forming template 110 remains aligned with the lower forming template 110 as it moves downwards. Ultimately, this allows the two pattern areas 31 formed on the upper and lower surfaces of the double-sided micro-nano structure element to be aligned with high precision, effectively improving the forming quality and accuracy of the double-sided micro-nano structure 32 during processing.

[0060] Understandably, the first and second inner walls serve a positioning and guiding function, thereby enabling high-precision forming of the blank 200.

[0061] Please see Figures 1 to 6 It is also understandable that multiple forming templates 110 can be produced in batches through the molding and trimming steps. This not only reduces costs, but also allows the upper and lower forming templates 110 to be interchanged during processing, as they are processed based on the same reference and equipment. This helps reduce processing errors and improve the final forming accuracy.

[0062] Optionally, the patterned substrate 10 can be made of materials such as silicon carbide, diamond, glassy carbon, tungsten carbide, sapphire, or single-crystal silicon. The processing method can be selected based on the geometric characteristics of the micro / nano structure 32 and the machinability analysis of the material of the patterned substrate 10. Processing methods include micro-milling, ultrafast laser ablation, ion beam milling, nanoimprint lithography, laser direct-write lithography, ultraviolet lithography, electron beam lithography, dry etching, micro / nano 3D printing, and other micro / nano manufacturing technologies. Alternatively, two or more of the above processing methods can be appropriately combined to form a composite manufacturing process chain, thereby completing the fabrication and processing of the micro / nano structure 32 on the patterned substrate 10.

[0063] It is understandable that the shapes of the micro-nano structures 32 on the two forming templates 110 can be the same or different.

[0064] Please see Figures 2 to 5 In some embodiments, the trimming process includes the following steps:

[0065] S21: First coarse cutting, cutting off the edge of the patterned substrate 10 along the first direction to form a first cut surface, the distance of the first cut surface along the second direction to the alignment structure 20 is a first predetermined value;

[0066] Optionally, the first predetermined value can be 2mm. Depending on the thickness and conductivity of the patterned substrate 10, the first rough cutting edge can be performed using methods such as ultrafast laser processing, water-guided laser cutting, water jet cutting, diamond wire cutting, electrical discharge cutting, or precision milling. Preliminary processing is carried out along the position marked by the alignment structure 20, leaving an appropriate processing allowance.

[0067] Please see Figures 2 to 5 For example, when the thickness of the patterned substrate 10 is less than 1 mm, ultrafast laser processing is used; when the thickness of the patterned substrate 10 is between 1 and 10 mm, water-guided laser cutting is used; when the thickness of the patterned substrate 10 is greater than 10 mm, water jet cutting, diamond wire cutting, or precision milling is used; if the patterned substrate 10 has good conductivity, electrical discharge wire cutting can be used.

[0068] S22: First fine cutting edge, cutting off the edge of the patterned base 10 along the first direction to form a first positioning surface 101. The first positioning surface 101 intersects the patterned surface 33 and has a first intersection line 11. The first intersection line 11 intersects the alignment structure 20.

[0069] Please see Figures 2 to 5 Optionally, a high-resolution optical microscope can be used to measure the relative position between the side surface of the patterned substrate 10 and the alignment mark 21 structure after the first rough cutting. Using the patterned surface 33 as the reference surface, the side surface of the patterned substrate 10 can be further refined using an ultra-precision grinding and polishing method to ensure the perpendicularity of the first positioning surface 101 formed in the final processing to the patterned surface 33, and to improve the surface finish of the first positioning surface 101. After multiple iterations of processing, the first intersection line 11 intersects with the alignment mark 21, ensuring the cutting accuracy and alignment consistency, and improving the positioning accuracy of the forming template 110.

[0070] It is understandable that both the first coarse cutting and the first fine cutting can be understood as thinning the patterned substrate 10 along the second direction, and the cutting thickness of the first coarse cutting is greater than that of the first fine cutting, thereby achieving high-efficiency cutting through the first coarse cutting and high-precision cutting through the first fine cutting.

[0071] Please see Figures 2 to 5 In some embodiments, the trimming process further includes the following steps:

[0072] S23: Second coarse cutting edge, cutting off another edge of the patterned substrate 10 along the second direction to form a second cut surface, the distance of the second cut surface along the first direction to the alignment structure 20 is a second predetermined value;

[0073] Similarly, the second predetermined value can be 2mm. Depending on the thickness and conductivity of the patterned substrate 10, the second roughing edge can be pre-processed using methods such as ultrafast laser processing, water-guided laser cutting, water jet cutting, diamond wire cutting, electrical discharge cutting, or precision milling, along the position marked by the alignment structure 20, leaving an appropriate processing allowance.

[0074] S24: Second fine cutting edge, cutting off another edge of the patterned base 10 along the second direction to form a second positioning surface 102, the second positioning surface 102 intersecting the patterned surface 33 and having a second intersection line 12, the second intersection line 12 intersecting the alignment structure 20.

[0075] Please see Figures 2 to 5 Alternatively, a high-resolution optical microscope can be used to measure the relative position between the side surface of the patterned substrate 10 and the alignment mark 21 structure after the second rough cutting. The patterned surface 33 is used as the reference surface, and an ultra-precision grinding and polishing method is used to continue to refine the side surface of the patterned substrate 10. This ensures the perpendicularity of the second positioning surface 102 formed in the final processing to the patterned surface 33, and improves the surface finish of the second positioning surface 102. After multiple iterations of processing, the second intersection line 12 intersects with the alignment mark 21, ensuring the cutting accuracy and alignment consistency, and improving the positioning accuracy of the forming template 110.

[0076] Please see Figures 2 to 5 It is understandable that both the second coarse cutting edge and the second fine cutting edge can be understood as thinning the patterned substrate 10 along the first direction, and the cutting edge thickness of the second coarse cutting edge is greater than that of the second fine cutting edge, thereby achieving high-efficiency cutting edge through the second coarse cutting edge and achieving high-precision cutting edge through the second fine cutting edge.

[0077] Please see Figures 2 to 5 In some embodiments, the alignment structure 20 includes a plurality of alignment marks 21, which are spaced apart and collinearly arranged along a first direction and spaced apart and collinearly arranged along a second direction; a first intersection line 11 intersects each corresponding alignment mark 21 in sequence; and a second intersection line 12 intersects each corresponding alignment mark 21 in sequence.

[0078] Please see Figures 2 to 5Optionally, multiple alignment marks 21 are arranged at equal intervals along a first direction to provide reference points for machining the first positioning surface 101 and the first intersection line 11. Similarly, multiple alignment marks 21 arranged at equal intervals along a second direction can provide reference points for machining the second positioning surface 102 and the second intersection line 12. Alternatively, this can be understood as follows: after machining the first positioning surface 101, each alignment mark 21 is arranged at equal intervals along the first intersection line 11; after machining the second positioning surface 102, each alignment mark 21 is arranged at equal intervals along the second intersection line 12.

[0079] Please see Figures 2 to 5 In some embodiments, the first intersecting line 11 intersects the same position of each alignment mark 21, and the second intersecting line 12 intersects the same position of each alignment mark 21.

[0080] Optionally, each alignment mark 21 has the same shape. The first intersection line 11 and the second intersection line 12 intersect each alignment mark 21 at the same position, which can unify the alignment reference, improve the accuracy of the forming template 110 when stacked, and ensure the alignment accuracy and consistency of the micro-nano structure 32 on the upper and lower surfaces of the blank 200.

[0081] Please see Figures 2 to 3 In some embodiments, the alignment mark 21 is a cross groove.

[0082] It is understood that the cross groove includes two orthogonally arranged micro-grooves 211, that is, one micro-grooves 211 is arranged along a first direction and the other micro-grooves 211 is arranged along a second direction, and the centers of the two micro-grooves 211 intersect. In the plurality of alignment mark 21 cross grooves arranged along the first direction, the micro-grooves 211 arranged along the first direction have two long groove sides located on the pattern surface 33, and the first intersection line 11 is collinear and tangent to each of the outer long groove sides; similarly, in the plurality of alignment mark 21 cross grooves arranged along the second direction, the micro-grooves 211 arranged along the second direction have two long groove sides located on the pattern surface 33, and the second intersection line 12 is collinear and tangent to each of the outer long groove sides.

[0083] Please see Figures 4 to 5 In some embodiments, alignment mark 21 is a micropore, which is a small-diameter circular hole.

[0084] Optionally, multiple micropores are arranged along a first direction, and a first intersection line 11 is tangent to the opening edge of each corresponding micropore, and the first intersection line 11 is tangent to the outside of the micropore, while the inside of the micropore is close to the pattern area 31; multiple micropores are arranged along a second direction, and a second intersection line 12 is tangent to the opening edge of each corresponding micropore, and the second intersection line 12 is tangent to the outside of the micropore, while the inside of the micropore is close to the pattern area 31.

[0085] Optionally, the alignment mark 21 is hole-shaped and can be identified using a machine vision mechanism, thereby improving the processing and inspection efficiency of the alignment structure 20, ensuring precise control of the first intersection line 11 and the second intersection line 12 during edge cutting, and avoiding the problem of limited processing resolution.

[0086] Please see Figures 2 to 5 It is understood that by having the first intersection line 11 tangent to each alignment mark 21, and the second intersection line 12 also tangent to each corresponding alignment mark 21, the processing of the first positioning surface 101 and the second positioning surface 102 can be precisely controlled, thereby improving the accuracy of hot pressing alignment.

[0087] In some embodiments, the first positioning surface 101 and the second positioning surface 102 are both perpendicular to the pattern surface 33 to improve the accuracy and stability of mechanical alignment, ensure uniform pressure distribution during hot pressing, and avoid structural deviations caused by tilting.

[0088] In some embodiments, the forming step includes the following steps:

[0089] S31: Heating, using heating module 130 to heat positioning sleeve 150, two forming templates 110 and blank 200. When blank 200 is oxidized glass, such as optical glass BK7, it is heated to its glass transition point temperature, so that the glass is in a viscoelastic and plastic state.

[0090] S32: Hot pressing, applying downward pressure to the upper forming template 110, so that the two surfaces of the blank 200 respectively replicate the micro-nano structures 32 of the two forming templates 110;

[0091] S33: Cooling, blowing cooling gas toward the positioning sleeve 150 to cool the positioning sleeve 150, the two forming templates 110 and the double-sided micro-nano structure element, for example blowing nitrogen gas at -100 degrees Celsius toward the positioning sleeve 150 to cool the positioning sleeve 150, the two forming templates 110 and the double-sided micro-nano structure element.

[0092] S34, demolding, separating the positioning sleeve 150 and the two forming templates 110 to remove the double-sided micro / nano structure element.

[0093] It is understandable that the positioning sleeve 150, the two forming templates 110, and the blank 200 can be heated synchronously through heat conduction or heat radiation. For example, by heating with resistance wire or by heat radiation heating with an infrared tube, the temperature of the blank 200 can be raised to near the glass transition point temperature, so that the blank 200 has a certain plasticity. Then, by extrusion through the two forming templates 110, the material on the surface of the blank 200 flows, thereby replicating the micro-nano structure 32 on the forming template 110.

[0094] It is understood that the double-sided embossing method provided in this application embodiment can perform cold embossing on blanks 200 such as plastics, or hot embossing on materials such as oxidized glass. There is no limitation here, and the choice can be made according to the actual situation.

[0095] Please see Figures 2 to 5 In some embodiments, the forming template 110 is a rectangular plate, and the forming template 110 has a first side surface 103 disposed opposite to the first positioning surface 101 and a second side surface 104 disposed opposite to the second positioning surface 102; the second side surface 104 is machined with the first positioning surface 101 as the reference surface to form a third positioning surface; the first side surface 103 is machined with the second positioning surface 102 as the reference surface to form a fourth positioning surface. The cross-sectional shape of the positioning cavity is adapted to the shape of the forming template 110, that is, the cross-sectional shape of the positioning sleeve 150 is rectangular, so as to enhance the stability of the circumferential positioning of the forming template 110 and improve the alignment accuracy of the two stacked forming templates 110.

[0096] Please see Figures 7 to 9 In some embodiments, an elastic component 40 is prepared, which is connected to the positioning sleeve 150 and abuts against the two forming templates 110. The elastic component 40 is used to press the two first positioning surfaces 101 against one inner wall of the positioning sleeve 150 and press the two second positioning surfaces 102 against the other inner wall of the positioning sleeve 150.

[0097] Please see Figures 7 to 9 It is understood that the first positioning surface 101 and the first inner wall are parallel to the first side surface 103, and the second positioning surface 102 and the second inner wall are parallel to the second side surface 104. The elastic component 40 includes a tube spring 42 and a push plate 41. Multiple tube springs 42 are located between the cavity wall of the positioning cavity and the push plate 41 and are arranged at intervals. There are two push plates 41. The first side surface 103 of the two forming templates 110 are respectively provided with a push plate 41. Under the action of the tube spring 42, the push plate 41 presses and positions the two first positioning surfaces 101 against the first inner wall.

[0098] Each of the two forming templates 110 has a corresponding push plate 41 on its second side 104. Under the action of the corresponding tube spring 42, the push plate 41 presses and positions the two second positioning surfaces 102 against the second inner wall. During the hot pressing process, especially during the thermal expansion of the positioning sleeve 150, when the expansion coefficient of the positioning sleeve 150 is large, the cooperation of the push plate 41 and the tube spring 42 ensures that the two first positioning surfaces 101 and the first inner wall, and the two second positioning surfaces 102 and the second inner wall remain in contact. This helps to improve the alignment accuracy of the upper and lower forming templates 110 during the hot pressing process, and ultimately improves the forming quality.

[0099] Please see Figures 7 to 9The positioning sleeve 150 and the forming template 110 are made of different materials. For example, the positioning sleeve 150 is made of stainless steel and the forming template 110 is made of tungsten carbide. After hot pressing, the shrinkage rates of the positioning sleeve 150 and the forming template 110 are different during the cooling process. When the shrinkage rate of the positioning sleeve 150 is greater than that of the forming template 110, a phenomenon similar to interference fit may occur between the positioning sleeve 150 and the forming template 110. Since the two push plates 41 are in a relatively laterally movable state, it is convenient to demold the positioning sleeve 150 and the two forming templates 110, improve the demolding efficiency, and also avoid damage to the double-sided micro-nano structure components.

[0100] Please see Figures 7 to 9 In some embodiments, the elastic component 40 includes a plurality of ball-head locking plungers 43, and the positioning sleeve 150 has a first threaded hole arranged in a first direction and a second threaded hole arranged in a second direction. Each forming template 110 is provided with at least one first threaded hole and one second threaded hole. One end of a ball-head locking plunger 43 is screwed into the first threaded hole, and the other end abuts against the corresponding forming template 110. One end of another ball-head locking plunger 43 is screwed into the second threaded hole, and the other end abuts against the corresponding forming template 110.

[0101] It is understandable that multiple ball-head locking plungers 43 can be arranged at intervals along both the horizontal and vertical directions.

[0102] Please see Figures 7 to 9 In this embodiment, each forming template 110 has two ball-head locking plungers 43 on its first side 103 and two ball-head locking plungers 43 on its second side 104. The ball-head end of the ball-head locking plunger 43 abuts against the forming template 110, forming a point-to-surface contact. This not only reduces interfacial friction, but also ensures that the force applied to the forming template 110 is always perpendicular to the first positioning surface 101 or the second positioning surface 102. By rotating the ball-head locking plunger 43, the tightness of the forming template 110 in the positioning cavity can be adjusted to adjust the pressure applied to the forming template 110 to adapt to different forming requirements.

[0103] Please see Figures 7 to 9 It is understandable that the ball head locking plunger 43 has a spring inside, which makes the ball head end elastically abut against the forming template 110. During the forming process, the first positioning surface 101 always remains in contact with the first inner wall, and the second positioning surface 102 always remains in contact with the second inner wall. Moreover, in the subsequent demolding process, the ball head locking plunger 43 can be rotated in the opposite direction to loosen the forming template 110, thereby improving the convenience of demolding.

[0104] Another objective of this application embodiment is to provide a forming mold, which includes a positioning sleeve 150, two forming templates 110 and an elastic component 40.

[0105] The present invention also proposes a double-sided micro / nano structure element, which is prepared using the double-sided imprinting method. The specific steps of the double-sided imprinting method are as described in the above embodiments. Since this double-sided micro / nano structure element adopts all the technical solutions of all the above embodiments, it also has all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0106] In the forming process of the double-sided micro-nano structure element, the forming template 110 located below, the blank 200, the forming template 110 located above, and the pressure head 120 are sequentially placed into the positioning cavity. The first positioning surface 101 and the second positioning surface 102 are respectively attached to the first inner wall and the second inner wall, and the two forming templates 110 are automatically aligned.

[0107] Since both the first intersection line 11 and the second intersection line 12 are tangent to the alignment mark 21 at the corresponding position, it means that in the two forming templates 110, the distance between the first positioning surface 101 and the pattern area 31 is basically the same, and the distance between the second positioning surface 102 and the pattern area 31 is basically the same. That is, the distance from the first intersection line 11 to the pattern area 31 is n, and the distance from the second intersection line 12 to the pattern area 31 is m. The first intersection line 11 is also the intersection line between the pattern surface 33 and the first inner wall, and the second intersection line 12 is also the intersection line between the pattern surface 33 and the second inner wall, thereby achieving the alignment of the pattern area 31 of the upper forming template 110 and the pattern area 31 of the lower forming template 110.

[0108] By controlling the servo press, the forming template 110 located below is brought into close contact with the base plate 140; then the upper and lower heating modules 130 are powered on to heat the forming template 110 located above, the forming template 110 located below, and the blank 200 to the imprinting temperature, such as near the glass transition point temperature of BK7.

[0109] Then, by applying pressure or an ultrasonic energy field, the micro-nano structure 32 of the upper forming template 110 and the micro-nano structure 32 of the lower forming template 110 are transferred to the upper and lower surfaces of the blank 200, respectively. Moreover, by increasing the imprinting temperature, imprinting force and extending the imprinting time, the replication rate and structural uniformity of the micro-nano structure 32 can be effectively improved.

[0110] Finally, cooling and demolding yield the double-sided micro / nano structure element. The surface quality of the double-sided micro / nano structure element is measured using a white light interferometer or scanning electron microscope. Based on the test results, it is determined whether further adjustments to the mold tooling and imprinting process are needed.

[0111] Please see Figures 10 to 11 The following example uses a glass anti-reflection beam splitter element applied in the near-infrared band:

[0112] According to the optical design, one side of the glass antireflective beam splitter element is a polarization-insensitive beam splitter structure (period 11.7µm, duty cycle 0.51, height 2.38µm), and the other side is an antireflective nanograting structure (period 260nm, ridge width 130nm, height 100nm).

[0113] First, two patterned substrates 10 are created. The process of processing the two patterned substrates 10 into two forming templates 110 is as follows:

[0114] The fabrication process of the upper forming template 110 (beam splitting grating template) is as follows: photoresist is spin-coated on the surface of a single-crystal silicon wafer, followed by ultraviolet exposure and development, and then reactive ion etching to obtain the single-crystal silicon grating template.

[0115] The fabrication process of the forming template 110 (anti-reflection grating template) below is as follows: A silicon oxide thin film is deposited on the surface of a silicon carbide wafer using ion-enhanced chemical vapor deposition, and then a layer of photoresist is spin-coated. A photoresist nanograting mask is generated using electron beam lithography, and a silicon oxide nanograting mask is formed using inductively coupled plasma etching. The anti-reflection nanograting pattern on the mask is transferred to the silicon carbide substrate again using inductively coupled plasma etching, and finally processed into the forming template 110.

[0116] Next, the alignment structure 20 is machined on the forming template 110 located in the upper direction, and the first positioning surface 101 and the second positioning surface 102 are machined.

[0117] Next, the alignment structure 20 is processed on the forming template 110 located below, and the first positioning surface 101 and the second positioning surface 102 are processed.

[0118] Then, double-sided micro-nano imprinting is performed using two forming templates 110 to obtain a glass anti-reflection beam splitter element.

[0119] Please see Figures 10 to 11 Compared with beam splitters without anti-reflection structures, anti-reflection beam splitters have improved diffraction efficiency. Specifically, the diffraction efficiency of +1st order TM and TE waves is improved by 1.4% and 0.6%, respectively, while the diffraction efficiency of -1st order TM and TE waves is improved by 0.9% and 1.2%, respectively.

[0120] Please see Figures 12 to 16 The following example uses a biconcave parabolic microlens array applied in the X-ray band:

[0121] The upper and lower surfaces of the biconcave parabolic microlens array are both plano-concave parabolic microlens array structures (microlens diameter 80μm, period 90μm, sagitta ≥20μm).

[0122] First, a patterned substrate 10 is fabricated, and a micro-cylinder array photoresist mask is made on a 6-inch thickened silicon carbide wafer substrate using ultraviolet lithography. The photoresist micro-cylinders are heated by thermal reflow technology, causing them to flow under the action of surface tension and gravity to form an ideal parabolic shape. The microlens shape on the photoresist is transferred to the silicon carbide substrate using inductively coupled plasma etching technology.

[0123] Then, a 6-inch silicon carbide plano-convex parabolic microlens array template is cut using a water-guided laser to obtain multiple silicon carbide square forming templates 110 with a side length of 20mm. Then, two sides of two of the forming templates are precision machined using a side grinding machine, and the two sides are respectively formed into a first positioning surface 101 and a second positioning surface 102.

[0124] Prepare two forming templates 110, one for the upper template and one for the lower template;

[0125] A circular beryllium sheet with a diameter of 3mm and a thickness of 0.1mm is selected as the blank 200. The upper template, beryllium sheet, and lower template are placed into the positioning sleeve 150 in sequence. The first positioning surface 101 and the second positioning surface 102 ensure that the corresponding positioning edges of the upper and lower templates are aligned, and a double concave parabolic microlens array of beryllium material is manufactured.

[0126] Please see Figures 12 to 16 Since the optical axes of the plano-convex microlenses on the surfaces of the upper and lower templates are aligned, the optical axes of the front and back microlens arrays in the formed double concave parabolic microlens array are also aligned, and the front and back microlens arrays of the double-sided micro-nano structure element are set in a mirror image.

[0127] exist Figure 14 In the image, the upper 3D color image shows the 3D topography of the front-facing microlens array, while the lower curve shows the shape contour of the front-facing microlens array. Figure 16 In the image above, the three-dimensional color image is a three-dimensional topographic image of the microlens array on the back side, and the curve below is a shape contour image of the microlens array on the back side. It can be seen that both the front and back microlens arrays have good shape accuracy.

[0128] The above are merely optional embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A double-sided embossing forming method, characterized in that, Includes the following steps: The process involves molding a patterned substrate with a patterned surface, fabricating an alignment structure on the patterned surface, and fabricating micro / nano structures on the patterned surface based on the alignment structure. Edge trimming: According to the alignment structure, one edge of the patterned substrate is trimmed along a first direction to form a first positioning surface; Another edge of the patterned substrate is cut off along the second direction to form a second positioning surface, so that the patterned substrate is processed into a forming template, wherein the first direction and the second direction are arranged alternately; Forming: Prepare a positioning sleeve with a positioning cavity; place two forming templates at intervals in the positioning cavity, with the two patterned surfaces facing each other; make both first positioning surfaces abut against one inner wall of the positioning cavity, and make both second positioning surfaces abut against the other inner wall of the positioning cavity; place the blank between the two forming templates and in a plastic state; press the two forming templates together to form the blank into a double-sided micro / nano structure element; The trimming process includes the following steps: The first coarse cut is performed by removing the edge of the patterned substrate along a first direction to form a first cut surface. The distance from the first cut surface to the alignment structure along the second direction is a first predetermined value. The first fine-cut edge is cut off along the first direction to form the first positioning surface, which intersects the patterned surface and has a first intersection line, which intersects the alignment structure. The trimming process also includes the following steps: The second coarse cut is performed by removing another edge of the patterned substrate along the second direction to form a second cut surface. The distance from the second cut surface to the alignment structure along the first direction is a second predetermined value. A second fine-cut edge is made by cutting off another edge of the patterned substrate along the second direction to form the second positioning surface, which intersects the patterned surface and has a second intersection line, which intersects the alignment structure. The alignment structure includes multiple alignment marks, which are spaced apart and collinearly arranged along a first direction, and spaced apart and collinearly arranged along a second direction; the first intersecting line intersects each corresponding alignment mark in sequence; the second intersecting line intersects each corresponding alignment mark in sequence. The first intersecting lines intersect at the same position of each of the alignment marks, and the second intersecting lines intersect at the same position of each of the alignment marks.

2. The double-sided embossing method as described in claim 1, characterized in that: The forming process includes the following steps: Heating: The billet is heated to a predetermined temperature using a heating module; Hot pressing applies downward pressure to the forming template located above, causing the two surfaces of the blank to replicate the micro-nano structures of the two forming templates respectively; Cooling is achieved by blowing cooling gas onto the positioning sleeve to cool the positioning sleeve, the two forming templates, and the double-sided micro / nano structure element. Demolding separates the positioning sleeve and the two forming templates.

3. The double-sided embossing method as described in any one of claims 1-2, characterized in that: Prepare an elastic component that connects to the positioning sleeve and abuts against the two forming templates. The elastic component is used to press the two first positioning surfaces against one inner wall of the positioning sleeve and press the two second positioning surfaces against the other inner wall of the positioning sleeve.

4. The double-sided embossing method as described in claim 3, characterized in that: The elastic component includes a plurality of ball-head locking plungers. The positioning sleeve has a first threaded hole arranged along the first direction and a second threaded hole arranged along the second direction. Each of the forming templates has at least one first threaded hole and one second threaded hole. One end of one ball-head locking plunger is screwed into the first threaded hole, and the other end abuts against the corresponding forming template. One end of another ball-head locking plunger is screwed into the second threaded hole, and the other end abuts against the corresponding forming template.

5. The double-sided embossing method as described in any one of claims 1-2, characterized in that: The forming template is a rectangular plate, and the forming template has a first side surface that is disposed opposite to the first positioning surface and a second side surface that is disposed opposite to the second positioning surface; the second side surface is processed with the first positioning surface as a reference surface to form a third positioning surface; the first side surface is processed with the second positioning surface as a reference surface to form a fourth positioning surface, and the cross-sectional shape of the positioning cavity is adapted to the shape of the forming template.

6. A double-sided micro / nano structure element, characterized in that, Prepared using the double-sided embossing method as described in any one of claims 1-5.

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