Preparation method of submicron semi-ellipsoidal unit structure for optical metasurface
By using evaporation coating, plasma-enhanced chemical vapor deposition, and etching processes on quartz substrates to prepare submicron semi-ellipsoidal unit structures, the problem of insufficient versatility in existing preparation methods has been solved, enabling high-precision, large-scale production of dielectric functional materials and improving optical performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-04-03
AI Technical Summary
Existing methods for preparing optical metasurface unit structures lack versatility, making it difficult to achieve high-precision, large-scale production on dielectric functional materials. Furthermore, traditional nanoimprinting and electrochemical nanoimprinting processes have limitations in terms of material adaptability and versatility.
Submicron semi-ellipsoidal unit structures are fabricated on quartz substrates using evaporation coating, plasma-enhanced chemical vapor deposition, electron beam lithography, reactive ion etching, and inductively coupled plasma etching processes. A cylindrical colloid is formed by electron beam lithography as a mask, and the semi-ellipsoids are directly formed on the medium using anisotropic etching and inductively coupled plasma etching.
This method enables the direct fabrication of submicron semi-ellipsoidal unit structures on dielectric functional materials, improving the versatility and large-scale production capability of the fabrication method, reducing dependence on current channels, and enhancing optical performance, particularly in beam divergence control, focusing imaging, and dispersion compensation.
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Figure CN121784869A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of metasurface technology, and in particular to a method for preparing a submicron semi-ellipsoidal unit structure for optical metasurfaces. Background Technology
[0002] The unit structures of optical metasurface devices typically employ geometric designs such as cylinders, prisms, and gratings, resulting in nanostructures with abrupt spatial variations. At the microscopic level, higher-order Mie resonances in these unit structures generate secondary reflection peaks, leading to wider full width at half maximum (FWHM) peaks or peak shape asymmetry and distortion. While these structures have driven the development of micro / nano optics, they suffer from high sensitivity to optical field manipulation and low spectral response resolution. In contrast, continuous surface structures in micro / nano optics, through the design of continuously varying surfaces at the submicron scale, can effectively reduce multi-level modes (especially higher-order modes) at non-resonant wavelengths, exhibiting superior optical performance and potential advantages in beam divergence control, focusing imaging, and dispersion compensation.
[0003] However, the fabrication of continuous curved surfaces is a challenge in micro / nano fabrication due to their complex geometry. The main methods for fabricating such continuous curved surface structures include traditional nanoimprinting (NIL) and electrochemical nanoimprinting (ECNL). Traditional nanoimprinting (NIL), with its extremely high replication fidelity and large-scale production capabilities, can achieve high-precision structure transfer at the tens to hundreds of nanometer scale. However, limited by its mechanical molding mechanism, it is suitable for polymer materials and difficult to apply directly to dielectric functional materials. The ECNL process requires simultaneous control of mechanical imprinting and electrochemical reactions, involving multiple sensitive parameters (such as voltage, current, time, and solution environment), making it difficult to control and limiting its applicable material range. Although it can be applied to metals and semiconductors to some extent, its versatility is still insufficient due to the significant differences in electrochemical reaction conditions among various materials. Therefore, different processes exhibit significant differences in material adaptability, making it difficult to simultaneously meet the needs of versatility and large-scale production. Summary of the Invention
[0004] This invention provides a method for fabricating submicron semi-ellipsoidal unit structures for optical metasurfaces, which can solve the problem of insufficient versatility of existing fabrication methods.
[0005] To address the aforementioned technical problems, embodiments of the present invention provide a method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces, comprising: A uniform first predetermined thickness is deposited on a quartz substrate using an evaporation deposition process. film; Deposited on a quartz substrate After thinning, plasma-enhanced chemical vapor deposition (PECVD) is used in the... A second preset thickness is deposited uniformly on the thin film. film; Deposited on a quartz substrate film and After the film, in the A positive electron beam resist layer of a third preset thickness is uniformly spin-coated onto a thin film, and the positive electron beam resist layer is exposed by electron beam lithography to prepare the positive electron beam resist layer into several cylindrical colloids of preset diameter; wherein, the height of the cylindrical colloids is the same as the height of the positive electron beam resist layer. Using the cylindrical colloid as a mask, reactive ion etching is employed to etch the area beneath the cylindrical colloid. The thin film is anisotropically etched to... The thin film was etched into a slightly conical shape with several trapezoidal cross sections; After anisotropic etching Using the thin film and the remaining positive electron beam resist layer as a mask, inductively coupled plasma etching was employed to etch the material. The thin film is etched to make the thin film... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure.
[0006] As a preferred embodiment, the method involves depositing a uniform first predetermined thickness on a quartz substrate using an evaporation deposition process. Thin film, including: Will The granular material was placed in a water-cooled copper crucible, and the material placed in the water-cooled copper crucible... The granular material was subjected to electron beam scanning, and the... The granular material is heated to a stable evaporation state, so that the... The particulate material evaporates and deposits onto a quartz substrate, forming a uniform deposition of a first predetermined thickness. film.
[0007] As a preferred embodiment, the plasma-enhanced chemical vapor deposition process is described in... A second preset thickness is deposited uniformly on the thin film. Thin film, including: A predetermined ratio of plasma-activated silicon and oxygen sources is introduced into the reaction chamber of a pre-defined plasma-enhanced chemical vapor deposition (PECVD) system. The radio frequency (RF) power and deposition time of the PECVD system are then set so that the PECVD system applies RF power to the plasma-activated silicon and oxygen sources according to the RF power and deposition time, thereby affecting the quartz substrate. A second preset thickness is deposited uniformly on the thin film. film.
[0008] As a preferred embodiment, the above-mentioned A uniform positive electron beam resist layer of a third predetermined thickness is spin-coated onto a thin film, and the positive electron beam resist layer is exposed by electron beam lithography to prepare the positive electron beam resist layer into cylindrical colloids of several predetermined diameters, including: In the A uniform positive electron beam resist layer of a third predetermined thickness is spin-coated onto the thin film, and a uniform conductive layer of a fourth predetermined thickness is deposited on the surface of the positive electron beam resist layer using a vacuum deposition process; The positive electron beam resist layer was exposed to electron beam using electron beam lithography to obtain the corresponding sample. After electron beam exposure, the sample is subjected to wet etching to remove the conductive layer on the sample, and the wet-etched sample is then developed to prepare the positive electron beam resist layer into several cylindrical colloids of a predetermined diameter.
[0009] As a preferred embodiment, the method of depositing a uniform conductive layer of a fourth predetermined thickness on the surface of the positive electron beam resist adhesive layer using a vacuum deposition process includes: Aluminum particles are placed in a crucible basket, and an electric current is applied to the aluminum particles in the crucible basket under high vacuum conditions to release aluminum atoms from the aluminum particles and deposit them onto the surface of the positive electron beam resist layer, forming a uniformly deposited fourth predetermined thickness conductive layer.
[0010] As a preferred embodiment, the step of using electron beam lithography to expose the positive electron beam resist layer with an electron beam to obtain a corresponding sample includes: According to the preset inverted pattern, electron beam lithography is used to expose the positions on the positive electron beam resist layer that correspond to the non-cylindrical regions of the inverted pattern to obtain the corresponding sample; wherein, the cylindrical regions to be prepared in the inverted pattern are blank, and the non-cylindrical regions are solid.
[0011] As a preferred embodiment, the wet etching process performed on the sample to remove the conductive layer on the sample includes: The sample is placed in a preset phosphoric acid solution and wet etched to remove the conductive layer. The wet-etched sample is then placed in a preset isopropanol solution to remove the phosphoric acid solution from the sample.
[0012] As a preferred embodiment, the step of developing the sample after wet etching to prepare the positive electron beam resist layer into cylindrical colloids of several predetermined diameters includes: After removing the phosphoric acid solution, the sample is placed in a preset xylene developer and stirred for a preset time. Then, the sample is transferred to a preset IPA solution for rinsing and drying to obtain several cylindrical colloids of a preset diameter.
[0013] As a preferred embodiment, the cylindrical colloid is used as a mask, and reactive ion etching is employed to etch the area beneath the cylindrical colloid. The thin film is anisotropically etched to... The thin film is etched into slightly conical bodies with several trapezoidal cross-sections, including: The developed sample is placed in a pre-defined reactive ion etching system, and a pre-defined first mixed gas is introduced into the reaction chamber of the system. The ion source discharge power and etching selectivity of the system are set so that the system uses the cylindrical colloid in the sample as a mask to etch the material beneath the colloid. The thin film is anisotropically etched to... The thin film was etched into a slightly conical shape with several trapezoidal cross sections.
[0014] As a preferred embodiment, the anisotropic etching... Using the thin film and the remaining positive electron beam resist layer as a mask, inductively coupled plasma etching was employed to etch the material. The thin film is etched to make the thin film... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure, including: A predetermined second mixed gas is introduced into the reaction chamber of a predetermined inductively coupled plasma etching system, and the source power and bias power of the inductively coupled plasma etching system are set so that the inductively coupled plasma etching system etches the etched material anisotropically. The thin film and the remaining positive electron beam resist layer serve as a mask to... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure.
[0015] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: This invention provides a method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces, utilizing an evaporation deposition process to deposit a uniform first predetermined thickness of [structure name missing] on a quartz substrate. Thin film; deposited on a quartz substrate After thinning, plasma-enhanced chemical vapor deposition (PECVD) is used in the... A second preset thickness is deposited uniformly on the thin film. Thin film; deposited on a quartz substrate film and After the film, in the A uniform positive electron beam resist layer of a third predetermined thickness is spin-coated onto a thin film, and the positive electron beam resist layer is then exposed using electron beam lithography to prepare a plurality of cylindrical colloids with predetermined diameters; wherein the height of the cylindrical colloids is the same as the height of the positive electron beam resist layer; using the cylindrical colloids as masks, reactive ion etching is used to etch the area below the cylindrical colloids. The thin film is anisotropically etched to... The thin film is etched into slightly conical bodies with several trapezoidal cross-sections; after anisotropic etching... Using the thin film and the remaining positive electron beam resist layer as a mask, inductively coupled plasma etching was employed to etch the material. The thin film is etched to make the thin film... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure. Compared with traditional nanoimprinting methods that are not suitable for dielectric functional materials, this invention can... Submicron semi-ellipsoidal unit structures can be directly fabricated on a dielectric substrate. Furthermore, compared to electrochemical imprinting, which requires a conductive substrate to trigger deposition or dissolution at the contact area and is difficult to perform directly on non-conductive dielectric films, the etching process of this invention does not require a current path, thus bypassing conductivity limitations. Therefore, this invention improves the versatility of methods for fabricating submicron semi-ellipsoidal unit structures for optical metasurfaces. Attached Figure Description
[0016] Figure 1 This is a schematic flowchart of a method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure during the fabrication process of a submicron semi-ellipsoidal metasurface; Figure 3 It is fabricated using a micro / nano process platform. Schematic diagrams of a semi-ellipsoidal periodic structure as captured by scanning electron microscopy and atomic force microscopy; Figure 4 These are schematic diagrams of a single-medium semi-ellipsoidal periodic structure and a cylindrical periodic structure; Figure 5 This is a comparison of the reflection spectra of a semi-ellipsoidal periodic structure and a cylindrical periodic structure under the same period, unit structure spacing, and structural height. Figure 6 These are schematic diagrams of the multipole unfolding scattering cross sections of semi-ellipsoidal periodic structures and cylindrical periodic structures. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.
[0019] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.
[0020] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.
[0021] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.
[0022] In the description of the embodiments of this application, the terms "multiple" and "several" refer to two or more (including two), similarly, "multiple groups" refer to two or more (including two groups), and "multiple pieces" refer to two or more (including two pieces).
[0023] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.
[0024] Example 1 Please refer to Figure 1 To address the lack of versatility in existing fabrication methods, this invention provides a schematic flowchart of a method for fabricating submicron semi-ellipsoidal unit structures for optical metasurfaces, based on an embodiment of the present invention. Titanium dioxide (… Taking materials as an example, this invention provides a method for preparing materials on a quartz substrate. The fabrication process for a submicron semi-ellipsoidal array structure. This designed array structure effectively suppresses higher-order modes through continuously varying curved surfaces, achieving high reflectivity and a narrow half-width at half-maximum (HWHM) reflection peak without the need for multiple dielectric layers. The designed periodic structure can cover a color range from blue-green to orange-red, thus enabling applications in display and imaging.
[0025] The process preparation adopts As a hard mask, electron beam lithography and dry etching, which is primarily physical and secondarily chemical, have enabled the application of photolithography to achieve the following: Direct fabrication of semi-ellipsoidal metasurfaces on dielectric materials. Compared to mechanical imprinting, which is only applicable to polymers, dielectric materials... It is less prone to deformation and easier to preserve; unlike grayscale lithography which requires multiple exposures, it uses single-pass EBL to form a cylindrical array on AR-P6200.13 positive resist by inverting the pattern. Therefore, no photomask is needed, and the etching pattern transfer can proceed directly, significantly reducing exposure and dosage calibration steps, shortening the pattern making cycle, and lowering costs. Compared with electrochemical imprinting, which requires a conductive substrate to trigger deposition or dissolution in the contact area, non-conductive dielectric films are difficult to directly implement this process. The dry etching process in the preparation does not require a current channel, bypassing conductivity limitations, and the morphology and size are more controllable. Please refer to... Figure 2 This is a schematic diagram of the structure during the fabrication process of a submicron semi-ellipsoidal metasurface. The fabrication method includes the following specific steps: S1. A uniform first predetermined thickness is deposited on a quartz substrate using an evaporation deposition process. film; Preferably, the method of depositing a uniform first predetermined thickness on a quartz substrate using an evaporation deposition process... Thin film, comprising: The granular material was placed in a water-cooled copper crucible, and the material placed in the water-cooled copper crucible... The granular material was subjected to electron beam scanning, and the... The granular material is heated to a stable evaporation state, so that the... The particulate material evaporates and deposits onto a quartz substrate, forming a uniform deposition of a first predetermined thickness. film.
[0026] In one specific embodiment, for step S1 above, the present invention utilizes an evaporation deposition (EBE) process to deposit a uniform 200 nm layer on a quartz substrate. film. Specifically, it will The granular material was placed in a water-cooled copper crucible and heated to 120°C by electron beam scanning for stable evaporation, ultimately yielding 200nm particles. film.
[0027] The evaporation deposition (EBE) process deposits... The essence of thin films is "reactive evaporation deposition," and its principle is based on high-energy-density electron beam heating (overcoming the high melting point limitation of Ti), vacuum environment to prevent contamination (ensuring film purity), and reactive gas composition control (achieving...). Stoichiometry), and substrate rotation and rate monitoring (to ensure uniform film thickness).
[0028] S2, Depositing the above on a quartz substrate After thinning, plasma-enhanced chemical vapor deposition (PECVD) is used in the... A second preset thickness is deposited uniformly on the thin film. film; Preferably, the plasma-enhanced chemical vapor deposition process is used in the... A second preset thickness is deposited uniformly on the thin film. The thin film comprises: introducing a predetermined ratio of plasma-activated silicon source and oxygen source into the reaction chamber of a predetermined plasma-enhanced chemical vapor deposition system, and setting the radio frequency power and deposition time of the plasma-enhanced chemical vapor deposition system so that the plasma-enhanced chemical vapor deposition system applies radio frequency to the plasma-activated silicon source and oxygen source according to the radio frequency power and deposition time, on the quartz substrate. A second preset thickness is deposited uniformly on the thin film. film.
[0029] In a specific embodiment, for step S2 above, after completing After thin film deposition, plasma-enhanced chemical vapor deposition (PECVD) was used to... 100 nanometers deposited on top Thin film as etching Hard mask.
[0030] Specifically, the formulation of the plasma-enhanced chemical vapor deposition process is as follows: 5% premixed [acid] is introduced into the reaction chamber of the plasma-enhanced chemical vapor deposition system. / Ar and Set the RF power to 20MHz and the deposition time (the required deposition time can be obtained according to the deposition rate), and then automatically run the plasma-enhanced chemical vapor deposition system according to the set formula to complete the deposition.
[0031] Among them, the plasma-enhanced chemical vapor deposition (PECVD) is used in Deposition on thin films As a hard mask, it is essentially a "low-temperature plasma-activated reactive deposition": it activates the silicon source (such as...) through radio frequency (RF) plasma. ) and oxygen source (such as ) gas, generating active siloxy groups, these groups in Adsorption, reaction, and condensation on the surface of the quartz substrate form a uniform and dense structure. film.
[0032] S3. Deposit the above on a quartz substrate. film and After the film, in the A positive electron beam resist layer of a third preset thickness is uniformly spin-coated onto a thin film, and the positive electron beam resist layer is exposed by electron beam lithography to prepare the positive electron beam resist layer into several cylindrical colloids of preset diameter; wherein, the height of the cylindrical colloids is the same as the height of the positive electron beam resist layer. Preferably, the one in the A uniform positive electron beam resist layer of a third predetermined thickness is spin-coated onto a thin film, and the positive electron beam resist layer is exposed by electron beam lithography to prepare the positive electron beam resist layer into cylindrical colloids of several predetermined diameters, including: in the... A uniform positive electron beam resist layer of a third preset thickness is spin-coated onto a thin film, and a uniform conductive layer of a fourth preset thickness is deposited on the surface of the positive electron beam resist layer using a vacuum deposition process; the positive electron beam resist layer is exposed to electron beam using an electron beam lithography process to obtain a corresponding sample; after electron beam exposure, the sample is subjected to wet etching to remove the conductive layer on the sample, and the wet-etched sample is developed to prepare the positive electron beam resist layer into a number of cylindrical colloids with preset diameters.
[0033] Preferably, the method of depositing a uniform conductive layer of a fourth predetermined thickness on the surface of the positive electron beam resist adhesive layer using a vacuum deposition process includes: placing aluminum particles in a crucible basket and applying an electric current to the aluminum particles placed in the crucible basket under high vacuum conditions, so that aluminum atoms in the aluminum particles are released and deposited onto the surface of the positive electron beam resist adhesive layer to form a uniformly deposited conductive layer of a fourth predetermined thickness.
[0034] Preferably, the step of using electron beam lithography to expose the positive electron beam resist layer to obtain a corresponding sample includes: according to a preset inverted pattern, using electron beam lithography to expose the positions on the positive electron beam resist layer corresponding to the non-cylindrical regions of the inverted pattern to obtain the corresponding sample; wherein, the cylindrical regions to be prepared in the inverted pattern are blank, and the non-cylindrical regions are solid.
[0035] Preferably, the wet etching process for removing the conductive layer on the sample includes: placing the sample in a preset phosphoric acid solution, performing wet etching on the sample to remove the conductive layer on the sample, and placing the wet-etched sample in a preset isopropanol solution to remove the phosphoric acid solution from the sample.
[0036] Preferably, the step of developing the sample after wet etching to prepare the positive electron beam resist layer into cylindrical colloids of several preset diameters includes: placing the sample after removing the phosphoric acid solution in a preset xylene developer, stirring the sample in the xylene developer for a preset time, transferring the sample into a preset IPA solution for rinsing and drying to obtain cylindrical colloids of several preset diameters.
[0037] In a specific embodiment, for step S4 above, the present invention deposits... and On the thin film sample, a cylindrical pattern was fabricated in the positive resist AR-P6200.13 using electron beam lithography (EBL). This cylindrical pattern was derived from the inverted layout. The diameter of the cylinder needed to be approximately 40 nanometers smaller than the actual diameter, and the height of the cylinder was 380 nanometers. The specific steps are as follows: (1) Spin coating of positive electron beam resist: Fix the sample on the spin coater turntable, use a dropper to drop AR-P 6200.13 positive electron beam resist onto the sample surface and fully cover the sample area, then spin coat. After spin coating, the resist layer thickness is about 380 nm. Then place the sample on the drying table and pre-bake at 170 °C for 10 min.
[0038] (2) Conductivity treatment: On the surface of positive electron beam resist, aluminum of about 50 nanometers is deposited as a conductive top coating by vacuum coating process.
[0039] Specifically, this invention involves placing a sample coated with a positive electron beam resist into a coating chamber, and applying an electric current to aluminum particles placed in a crucible basket under high vacuum conditions, causing aluminum atoms to be released and deposited onto the sample surface. The deposition of the conductive top coating can be achieved using a vacuum ion sputtering coating instrument, which incorporates both ion sputtering and thermal evaporation deposition methods.
[0040] (3) Electron beam lithography: According to the preset inverted pattern, the electron beam lithography process is used to expose the non-cylindrical regions on the positive electron beam resist layer to obtain the corresponding sample.
[0041] Electron beam lithography (EBL) is a high-resolution, maskless micro-nano fabrication technique that uses a focused electron beam to directly irradiate photoresist coated on a substrate. Patterning is achieved through the interaction between electrons and photoresist, and nanoscale structures are finally fabricated on the substrate through development, etching, and other steps.
[0042] (4) Conductive layer removal and development: After electron beam exposure, conductive layer removal and development are performed on a wet etching stage. The sample is first wet etched in a 5% phosphoric acid solution at 50°C to remove the surface conductive aluminum layer. Then, the sample is rinsed in isopropanol (IPA) solution to remove residual phosphoric acid solution and then briefly baked at 130°C for 1 min. The sample is then immersed in xylene developer for about 90 s with slight agitation to develop, and then immediately transferred to IPA rinsing to terminate development. Finally, it is dried to obtain the target pattern. Please refer to... Figure 3 Fabricated using micro / nano process platforms A schematic diagram of the semi-ellipsoidal periodic structure obtained by scanning electron microscopy and atomic force microscopy (P=360nm, G=50nm), where, Figure 3 (1) A schematic diagram of the structure taken by scanning electron microscope (SEM). Figure 3 (2) A schematic diagram of the structure taken by atomic force microscope (AFM).
[0043] S4. Using the cylindrical colloid as a mask, employ reactive ion etching to etch the material beneath the cylindrical colloid. The thin film is anisotropically etched to... The thin film was etched into a slightly conical shape with several trapezoidal cross sections; Preferably, the step of using the cylindrical colloid as a mask and employing reactive ion etching to etch the material beneath the cylindrical colloid... The thin film is anisotropically etched to... Thin film etching into slightly conical bodies with trapezoidal cross-sections includes: placing a developed sample in a preset reactive ion etching system, introducing a preset first mixed gas into the reaction chamber of the reactive ion etching system, and setting the ion source discharge power and etching selectivity of the reactive ion etching system so that the reactive ion etching system uses the cylindrical colloid in the sample as a mask to etch the thin film into the area below the cylindrical colloid. The thin film is anisotropically etched to... The thin film was etched into a slightly conical shape with several trapezoidal cross sections.
[0044] In a specific embodiment, for step S4 above, the present invention uses the cylinder formed after electron beam lithography as a mask and uses reactive ion etching (RIE) to perform anisotropic etching on the sample.
[0045] The reactive ion etching process is formulated as follows: Ar / A 3:1 gas mixture was used, and the ion source discharge power was set to 200W to maintain the plasma within the source cavity. AR-P6200.13 positive adhesive and... The etching selectivity ratio is 1:1.5. After the etching process is completed, The hard mask has a slightly tapered shape (trapezoidal cross-section).
[0046] Reactive ion etching (RIE) is a dry etching technique that achieves directional etching of solid materials through the synergistic effect of active free radicals (chemical action) and high-energy ions (physical bombardment) in plasma. Its core characteristics are anisotropy (perpendicular sidewalls) and high selectivity (different etching rates for different materials), making it a key process for pattern transfer in micro / nano fabrication (such as transferring photoresist / EBL patterns to underlying thin films).
[0047] S5, after anisotropic etching Using the thin film and the remaining positive electron beam resist layer as a mask, inductively coupled plasma etching was employed to etch the material. The thin film is etched to make the thin film... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure.
[0048] Preferably, the anisotropic etching after Using the thin film and the remaining positive electron beam resist layer as a mask, inductively coupled plasma etching was employed to etch the material. The thin film is etched to make the thin film... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure. This includes: introducing a predetermined second mixed gas into the reaction chamber of a predetermined inductively coupled plasma etching system, and setting the source power and bias power of the inductively coupled plasma etching system to enable the inductively coupled plasma etching system to anisotropically etch the film. The thin film and the remaining positive electron beam resist layer serve as a mask to... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure.
[0049] In a specific embodiment, for step S5 above, the present invention mixes the remaining photoresist with... The hard mask also serves as the etching mask, and etching is performed using inductively coupled plasma etching (ICP). .
[0050] The formulation of the inductively coupled plasma etching process is set as follows: [Injection / Introduction] A gas mixture with an Ar ratio of 4:3, power output 600 W. A hard mask with a certain tilt angle. The structure will be etched The tilt angle is then passed down until the photoresist and hard mask are exhausted. It will become a frustum structure, entirely exposed. The structure continues to be etched within the reaction chamber. Over a certain etching time, the overall arc-shaped contour is etched, ultimately transforming the angled frustum into a 130-nanometer-thick semi-ellipsoidal structure. Please refer to... Figure 3 Fabricated using micro / nano process platforms A schematic diagram of the semi-ellipsoidal periodic structure obtained by scanning electron microscopy and atomic force microscopy (P=360nm, G=50nm), where, Figure 3 (1) A schematic diagram of the structure taken by scanning electron microscope (SEM). Figure 3 (2) A schematic diagram of the structure taken by atomic force microscope (AFM).
[0051] Inductively Coupled Plasma Etching (ICP) is a high-density plasma dry etching technique that uses an alternating electromagnetic field generated by an induction coil to excite plasma and separates and controls the "generation" of plasma from "ion acceleration (physical bombardment)" (independent source power and bias power) to achieve high-speed, high anisotropy, and high aspect ratio etching of materials.
[0052] In another preferred embodiment, the submicron structure with a continuous curved surface morphology prepared by the present invention is described below: The described submicron semi-ellipsoidal optical metasurface structure can effectively reduce multi-level Mie resonances at non-resonant wavelengths through continuous curved surface profiles, offering potential advantages in focusing, dispersion compensation, polarization control, and integration. The principle behind this structure is to excite and modulate Mie resonances with high quality factors, achieving a smooth transition of resonant modes within a continuously varying micro / nano curved surface structure, thereby enabling highly efficient control of the wavefront amplitude, phase, and polarization of light.
[0053] According to the multipole expansion theory of Mie scattering, the submicron semi-ellipsoidal structural unit will excite electric dipoles, magnetic dipoles, and higher-order multipole modes under the action of an optical field, and its total scattering cross section can be expressed as: (1) in, and Let Mie be the coefficient, and the scattered field can be decomposed into different multipole contributions: Electric dipole moment (ED): (2) Magnetic dipole moment (MD): (3) Electric Quadrupole Tensor (EQ): (4) Magnetic quadrupole tensor (MQ): (5) Circular Dipole Moment (TD): (6) in, Polarization current density It is the optical angular frequency. At the speed of light, It is a spatial displacement vector. , It is the Kronecker delta function.
[0054] The total scattering intensity can be expanded as follows: (7) Therefore, the scattering intensity is determined by multiple pole modes, including electric dipole (ED), magnetic dipole (MD), quadrupole (EQ, MQ), and toroidal dipole (TD). Traditional dielectric geometry designs, with their abrupt spatial distribution, can induce strong higher-order quadrupole modes (EQ / MQ), leading to energy dispersion and efficiency loss. In contrast, the semi-ellipsoidal micro / nano unit of this invention features a continuously varying surface, effectively suppressing the excitation of higher-order modes and concentrating scattering energy on lower-order dipole modes, thereby improving optical efficiency and functional controllability. Its geometric parameters, including radius of curvature and major-minor axis ratio, can be precisely controlled. The optical response characteristics of this continuous surface are significantly different from those of two-dimensional structures with abrupt spatial distributions of geometric parameters.
[0055] by For example, regarding metasurface structural colors, please refer to... Figure 4 The diagram shows a semi-ellipsoidal periodic structure and a cylindrical periodic structure in a single medium. Figure 4 (1) is a schematic diagram of a single-medium semi-ellipsoidal periodic structure. Figure 4 (2) A schematic diagram of a cylindrical periodic structure. Using the same period (P=350nm), height (H=130nm), and spacing (G=120nm) parameters, a semi-ellipsoidal periodic structure in a single medium is simulated. Figure 4 (1) shown) and cylindrical periodic structure ( Figure 4 (2) shows the optical response in the visible light band.
[0056] Please refer to Figure 5 This is a comparison of the reflection spectra of a semi-ellipsoidal periodic structure and a cylindrical periodic structure under the same period, unit spacing, and structural height. The horizontal axis x represents wavelength (in nm), and the vertical axis y represents reflectivity. Figure 5 (1) Comparison of reflection spectra of semi-ellipsoidal periodic structures with the same period (P=350nm), unit structure spacing (G=120nm), and structure height (H=130nm). Figure 5 (2) A comparison diagram of the reflection spectra of a cylindrical periodic structure. Figure 5 The reflection spectrum shows that the reflection peaks of the semi-ellipsoidal periodic structure are sharper, and the half-peak width is narrower. Please refer to... Figure 6 This is a schematic diagram of the multipole unfolding scattering cross-section of a semi-ellipsoidal periodic structure and a cylindrical periodic structure. Figure 6 (1) It is a semi-ellipsoidal periodic structure. Figure 6 (2) The structure is cylindrical with a periodic structure. The horizontal axis x represents the wavelength (in nm), and the vertical axis y represents the scattering cross section. The multipole decomposition results of the scattering cross section show that the electric dipole (ED) contribution is dominant. The cylindrical periodic structure has a wider reflection peak and exhibits multiple peaks. The main contribution in its scattering cross section comes from the MD (e.g., Figure 6 (2) is shown). According to Figure 6 The comparison shows that the higher-order modes (electric quadrupole, magnetic quadrupole, and toroidal dipole) of the semi-ellipsoidal periodic structure have a smaller impact on the overall scattering than the higher-order modes of the cylindrical periodic structure.
[0057] This micro / nano continuous curved surface structure can be used to realize a variety of optical functions, including but not limited to light focusing and imaging, beam deflection, dispersion compensation, polarization control, and multifunctional integration. Depending on the application requirements, the structure can be designed as an independent unit or an array to meet the optical performance requirements of different devices.
[0058] Therefore, this invention provides a method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces, utilizing an evaporation deposition process to deposit a uniform first predetermined thickness of [structure name missing] on a quartz substrate. Thin film; deposited on a quartz substrate After thinning, plasma-enhanced chemical vapor deposition (PECVD) is used in the... A second preset thickness is deposited uniformly on the thin film. Thin film; deposited on a quartz substrate film and After the film, in the A uniform positive electron beam resist layer of a third predetermined thickness is spin-coated onto a thin film, and the positive electron beam resist layer is then exposed using electron beam lithography to prepare a plurality of cylindrical colloids with predetermined diameters; wherein the height of the cylindrical colloids is the same as the height of the positive electron beam resist layer; using the cylindrical colloids as masks, reactive ion etching is used to etch the area below the cylindrical colloids. The thin film is anisotropically etched to... The thin film is etched into slightly conical bodies with several trapezoidal cross-sections; after anisotropic etching... Using the thin film and the remaining positive electron beam resist layer as a mask, inductively coupled plasma etching was employed to etch the material. The thin film is etched to make the thin film... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure. Compared with traditional nanoimprinting methods that are not suitable for dielectric functional materials, this invention can... Submicron semi-ellipsoidal unit structures can be directly fabricated on a dielectric substrate. Furthermore, compared to electrochemical imprinting, which requires a conductive substrate to trigger deposition or dissolution at the contact area and is difficult to perform directly on non-conductive dielectric films, the etching process of this invention does not require a current path, thus bypassing conductivity limitations. Therefore, this invention improves the versatility of methods for fabricating submicron semi-ellipsoidal unit structures for optical metasurfaces.
[0059] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.
Claims
1. A method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces, characterized in that, include: A uniform first predetermined thickness is deposited on a quartz substrate using an evaporation deposition process. film; Deposited on a quartz substrate After thinning, plasma-enhanced chemical vapor deposition (PECVD) is used in the... A second preset thickness is deposited uniformly on the thin film. film; Deposited on a quartz substrate film and After the film, in the A positive electron beam resist layer of a third preset thickness is uniformly spin-coated onto a thin film, and the positive electron beam resist layer is exposed by electron beam lithography to prepare the positive electron beam resist layer into several cylindrical colloids of preset diameter; wherein, the height of the cylindrical colloids is the same as the height of the positive electron beam resist layer. Using the cylindrical colloid as a mask, reactive ion etching is employed to etch the area beneath the cylindrical colloid. The thin film is anisotropically etched to... The thin film was etched into a slightly conical shape with several trapezoidal cross sections; After anisotropic etching Using the thin film and the remaining positive electron beam resist layer as a mask, inductively coupled plasma etching was employed to etch the material. The thin film is etched to make the thin film... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure.
2. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 1, characterized in that, The process involves depositing a uniform first predetermined thickness on a quartz substrate using an evaporation deposition process. Thin film, including: Will The granular material was placed in a water-cooled copper crucible, and the material placed in the water-cooled copper crucible... The granular material was subjected to electron beam scanning, and the... The granular material is heated to a stable evaporation state, so that the... The particulate material evaporates and deposits onto a quartz substrate, forming a uniform deposition of a first predetermined thickness. film.
3. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 2, characterized in that, The plasma-enhanced chemical vapor deposition process is described in A second preset thickness is deposited uniformly on the thin film. Thin film, including: A predetermined ratio of plasma-activated silicon and oxygen sources is introduced into the reaction chamber of a pre-defined plasma-enhanced chemical vapor deposition (PECVD) system. The radio frequency (RF) power and deposition time of the PECVD system are then set so that the PECVD system applies RF power to the plasma-activated silicon and oxygen sources according to the RF power and deposition time, thereby affecting the quartz substrate. A second preset thickness is deposited uniformly on the thin film. film.
4. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 3, characterized in that, The above A uniform positive electron beam resist layer of a third predetermined thickness is spin-coated onto a thin film, and the positive electron beam resist layer is exposed by electron beam lithography to prepare the positive electron beam resist layer into cylindrical colloids of several predetermined diameters, including: In the A uniform positive electron beam resist layer of a third predetermined thickness is spin-coated onto the thin film, and a uniform conductive layer of a fourth predetermined thickness is deposited on the surface of the positive electron beam resist layer using a vacuum deposition process; The positive electron beam resist layer was exposed to electron beam using electron beam lithography to obtain the corresponding sample. After electron beam exposure, the sample is subjected to wet etching to remove the conductive layer on the sample, and the wet-etched sample is then developed to prepare the positive electron beam resist layer into several cylindrical colloids of a predetermined diameter.
5. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 4, characterized in that, The process of depositing a uniform conductive layer of a fourth predetermined thickness on the surface of the positive electron beam resist adhesive layer using a vacuum deposition process includes: Aluminum particles are placed in a crucible basket, and an electric current is applied to the aluminum particles in the crucible basket under high vacuum conditions to release aluminum atoms from the aluminum particles and deposit them onto the surface of the positive electron beam resist layer, forming a uniformly deposited fourth predetermined thickness conductive layer.
6. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 5, characterized in that, The process of using electron beam lithography to expose the positive electron beam resist layer with an electron beam to obtain a corresponding sample includes: According to the preset inverted pattern, electron beam lithography is used to expose the positions on the positive electron beam resist layer that correspond to the non-cylindrical regions of the inverted pattern to obtain the corresponding sample; wherein, the cylindrical regions to be prepared in the inverted pattern are blank, and the non-cylindrical regions are solid.
7. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 6, characterized in that, The wet etching process performed on the sample to remove the conductive layer on the sample includes: The sample is placed in a preset phosphoric acid solution and wet etched to remove the conductive layer. The wet-etched sample is then placed in a preset isopropanol solution to remove the phosphoric acid solution from the sample.
8. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 7, characterized in that, The step of developing the sample after wet etching to prepare the positive electron beam resist layer into cylindrical colloids of several predetermined diameters includes: After removing the phosphoric acid solution, the sample is placed in a preset xylene developer and stirred for a preset time. Then, the sample is transferred to a preset IPA solution for rinsing and drying to obtain several cylindrical colloids of a preset diameter.
9. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 8, characterized in that, The cylindrical colloid is used as a mask, and reactive ion etching is employed to etch the material beneath the cylindrical colloid. The thin film is anisotropically etched to... The thin film is etched into slightly conical bodies with several trapezoidal cross-sections, including: The developed sample is placed in a pre-defined reactive ion etching system, and a pre-defined first mixed gas is introduced into the reaction chamber of the system. The ion source discharge power and etching selectivity of the system are set so that the system uses the cylindrical colloid in the sample as a mask to etch the material beneath the colloid. The thin film is anisotropically etched to... The thin film was etched into a slightly conical shape with several trapezoidal cross sections.
10. The method for fabricating a submicron semi-ellipsoidal unit structure for optical metasurfaces as described in claim 9, characterized in that, The anisotropic etching Using the thin film and the remaining positive electron beam resist layer as a mask, inductively coupled plasma etching was employed to etch the material. The thin film is etched to make the thin film... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure, including: A predetermined second mixed gas is introduced into the reaction chamber of a predetermined inductively coupled plasma etching system, and the source power and bias power of the inductively coupled plasma etching system are set so that the inductively coupled plasma etching system etches the etched material anisotropically. The thin film and the remaining positive electron beam resist layer serve as a mask to... The thin film is etched into several semi-ellipsoids to obtain the corresponding submicron semi-ellipsoidal unit structure.