Composite all-dielectric reflector film and method of making same

Abstract

The application discloses a composite full-dielectric reflection film and a preparation method thereof. The preparation method comprises the following steps: providing a substrate, one side of the substrate being attached with a cover layer; mixing an acid adjusting solution and a powder mixture solution, and then performing ultrasonic aging to obtain a sol, wherein the pH value of the acid adjusting solution is a preset pH threshold value; the powder mixture solution is prepared by mixing an alkoxide precursor solution, SiO2 powder and high-refractive oxide powder; vertically immersing the substrate into the sol to continuously coat the substrate at a first pulling speed to reach a first quantity value, so that a dense thick film with a thickness reaching a preset thickness is formed on the side of the substrate away from the cover layer, and a coated substrate is obtained; and performing drying treatment and heat preservation treatment on the coated substrate to obtain the composite full-dielectric reflection film. Through the synergistic regulation of the pH threshold value and the heat preservation sintering, the hydrolysis and polycondensation rates of the high-refractive oxide powder and the SiO2 powder are perfectly matched and chemical bonding is promoted, and the performance of the composite full-dielectric reflection film is improved.

Description

Technical Field

[0001] This application relates to the field of reflective film technology, and in particular to a composite all-dielectric reflective film and its preparation method. Background Technology

[0002] Excimer lamps are core components in the current field of ultraviolet light sources, capable of outputting various characteristic wavelengths such as 172nm, 222nm, 248nm, and 308nm. They are widely used in semiconductor wafer cleaning, public health disinfection, dermatological treatment, and VOCs degradation. Because the ultraviolet radiation from excimer lamps is spatially isotropic, approximately half of the photons dissipate towards the inside or sidewalls of the lamp tube. Therefore, a high-reflectivity film needs to be deposited on key surfaces of the lamp tube to reflect and recover ultraviolet light from non-emitting directions. This is the core method for improving the energy utilization rate of excimer lamps. Therefore, the reflectivity, UV aging resistance, and ozone resistance of the reflective film directly determine the brightness, energy consumption, and lifespan of the excimer lamp.

[0003] Currently, the mainstream solution for excimer lamp reflective films is an all-dielectric multilayer reflective film, which uses alternating stacks of high-refractive-index materials such as Al2O3 and ZrO2 with low-refractive-index materials such as SiO2 to achieve high reflectivity using the Bragg reflection principle. Existing industrial fabrication of all-dielectric reflective films mainly relies on physical vapor deposition (PVD) technology, which suffers from expensive equipment, complex processes, and difficulty in achieving large-area uniform coating on the inner walls of irregularly shaped substrates such as coaxial cylinders. Summary of the Invention

[0004] This application provides a composite all-dielectric reflective film and its preparation method, which effectively solves the problems of easy cracking, easy agglomeration, and low reflectivity of reflective films, and improves the optical performance and production yield of composite all-dielectric reflective films.

[0005] In a first aspect, embodiments of this application provide a method for preparing a composite all-dielectric reflective film, comprising: A substrate is provided, one side of which is adhered with a cover layer; After mixing the acidic conditioning solution and the powder mixture, ultrasonic curing is performed to obtain a sol. The pH value of the acidic conditioning solution is a preset pH threshold. The powder mixture is prepared by mixing an alkoxide precursor solution, SiO2 powder, and high refractive index oxide powder. The mass ratio of the high refractive index oxide powder to the SiO2 powder is between 0.9:1 and 1.1:1. The pH threshold is determined by the high refractive index oxide. The substrate is vertically immersed in the sol, and a first number of films are continuously deposited at a first lifting speed to form a dense thick film with a preset thickness on the side of the substrate away from the masking layer, thereby obtaining a coated substrate. After drying and heat preservation treatment of the coating substrate, a composite all-dielectric reflective film is obtained.

[0006] In some embodiments, the ultrasonic curing of the mixed acid conditioning solution and powder mixture includes: 1.31 g of deionized water and 0.33 g of hydrochloric acid solution were mixed to obtain a hydrochloric acid mixture, wherein the concentration of the hydrochloric acid solution was 1 mol / L. Add 2.48g of deionized water to the first reagent bottle, then add the hydrochloric acid mixture, mix well, and obtain the acidic adjusting solution with a pH of 2.5.

[0007] In some embodiments, the powder mixture is prepared by mixing an alkoxide precursor solution, SiO2 powder, and a high refractive index oxide powder, comprising: Add 9.9g of anhydrous ethanol and 1.65g of tetraethyl orthosilicate to the second reagent bottle in sequence, and mix by ultrasonication for a preset first time to obtain the alkoxide precursor solution. SiO2 powder was added to the alkoxide precursor solution in batches. After each addition, the mixture was ultrasonically mixed for a preset second time before the next batch was added, until the weight of the SiO2 powder reached 4.13g, thus obtaining the first mixture. Al2O3 powder is added to the first mixture in batches and ultrasonically mixed for a preset third time to obtain a second mixture, wherein the weight of the Al2O3 powder is between 3.72g and 4.54g.

[0008] In some embodiments, the ultrasonic curing of the mixed acid conditioning solution and powder mixture further includes: Slowly pour the acidic adjusting solution from the first reagent bottle into the second reagent bottle and stir until homogeneous to obtain the third mixture; The third mixture is ultrasonically mixed for a preset fourth time to obtain the sol.

[0009] In some embodiments, the step of vertically immersing the substrate in the sol and continuously depositing a film at a first lifting speed to reach a first quantity value includes: The substrate is vertically immersed in the sol, and the first lifting speed is controlled at 30 cm / min to perform a coating operation on the substrate. The coating operation was performed four times consecutively, and after each coating operation, the mixture was allowed to stand and dry at room temperature for 30 minutes.

[0010] In some embodiments, the process of drying and heat-insulating the coating substrate to obtain a composite all-dielectric reflective film includes: The coated substrate is placed in an oven and kept at 150°C for 1 hour to complete the initial drying; The pre-dried coating substrate is placed in a muffle furnace and held at 300°C, 400°C and 500°C for 60 minutes respectively. After natural cooling in the furnace, the composite all-dielectric reflective film is obtained.

[0011] In some embodiments, the powder mixture is prepared by mixing an alkoxide precursor solution, SiO2 powder, and a high refractive index oxide powder, comprising: Add 9.9g of anhydrous ethanol and 1.65g of tetraethyl orthosilicate to the second reagent bottle in sequence, and mix by ultrasonication for a preset first time to obtain the alkoxide precursor solution. SiO2 powder was added to the alkoxide precursor solution in batches. After each addition, the mixture was ultrasonically mixed for a preset second time before the next batch was added, until the weight of the SiO2 powder reached 4.13g, thus obtaining the first mixture. ZrO2 powder is added to the first mixture in batches and ultrasonically mixed for a preset third time to obtain a second mixture, wherein the weight of the ZrO2 powder is between 3.72g and 4.54g.

[0012] In some embodiments, the ultrasonic curing of the mixed acid conditioning solution and powder mixture further includes: The acidic adjusting solution is slowly poured into the second reagent bottle and stirred until homogeneous to obtain a third mixture. The pH value of the acidic adjusting solution is 9. The third mixture is ultrasonically mixed for a preset fourth time to obtain the sol.

[0013] In some embodiments, the process of drying and heat-insulating the coating substrate to obtain a composite all-dielectric reflective film includes: The coated substrate is placed in an oven and kept at 150°C for 1 hour to complete the initial drying; The pre-dried coating substrate is placed in a muffle furnace and held at 300°C and 400°C for 60 minutes each. After natural cooling in the furnace, the composite all-dielectric reflective film is obtained.

[0014] Secondly, embodiments of this application also provide a composite all-dielectric reflective film, prepared by the preparation method described in the first aspect.

[0015] The composite all-dielectric reflective film and its preparation method according to the embodiments of this application have at least the following beneficial effects: a substrate is provided, one side of which is attached with a masking layer; an acidic conditioning solution and a powder mixture are mixed and then ultrasonically cured to obtain a sol, wherein the pH value of the acidic conditioning solution is a preset pH threshold; the powder mixture is made by mixing an alkoxide precursor solution, SiO2 powder and high refractive index oxide powder, wherein the mass ratio of high refractive index oxide powder to SiO2 powder is between 0.9:1 and 1.1:1; the substrate is vertically immersed in the sol, and a first lifting speed is continuously applied to achieve a first quantity value, forming a dense thick film with a preset thickness on the side of the substrate away from the masking layer, thereby obtaining a coated substrate; after drying and heat preservation treatment of the coated substrate, a composite all-dielectric reflective film is obtained. By synergistically controlling the pH threshold and heat-preserving sintering, the hydrolysis and polycondensation rates of high-refractive-index oxide powder and SiO2 powder are perfectly matched, promoting chemical bonding. This effectively avoids through-cracks in the composite all-dielectric reflective film, reduces its microporosity, and improves its adhesion. It also enhances the ultraviolet light intensity and photon recovery efficiency of the composite all-dielectric reflective film. The fabrication process of the composite all-dielectric reflective film is simple and inexpensive, suitable for coating the inner walls of irregularly shaped tubes, thus reducing the overall manufacturing cost.

[0016] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description and the accompanying drawings. Attached Figure Description

[0017] Figure 1 A flowchart illustrating a method for preparing a composite all-dielectric reflective film according to one embodiment of this application; Figure 2 When the high refractive index oxide is Al2O3 Figure 1 Flowchart for the preparation of neutral to acidic conditioning solution; Figure 3 When the high refractive index oxide is Al2O3 Figure 1 Flowchart for the preparation of medium-strength powder mixture; Figure 4 When the high refractive index oxide is Al2O3 Figure 1 Flowchart of the preparation process of sol; Figure 5 When the high refractive index oxide is Al2O3 Figure 1 Flowchart of step S3000; Figure 6 When the high refractive index oxide is Al2O3 Figure 1 Flowchart of step S4000; Figure 7 When the high refractive index oxide is ZrO2 Figure 1 Flowchart for the preparation of medium-strength powder mixture; Figure 8 When the high refractive index oxide is ZrO2 Figure 1 Flowchart of the preparation process of sol; Figure 9 When the high refractive index oxide is ZrO2 Figure 1 Flowchart of step S4000; Figure 10 The surface morphology of the films coated with Al2O3 as the high refractive index oxide is shown at different pH values ​​at 10kx magnification. Figure 11 The surface morphology of the coatings with Al2O3 as the high refractive index oxide is shown at different pH values ​​at 1kx magnification. Figure 12 The surface morphology of the films coated with ZrO2 at different pH values ​​is shown at 10kx magnification. Figure 13 The surface morphology of the films coated with ZrO2 at different pH values ​​is shown at 1kx magnification. Figure 14 The infrared spectrum of the composite all-dielectric reflective film when the high refractive index oxide is Al2O3; Figure 15 The infrared spectrum of the composite all-dielectric reflective film with high refractive index oxide ZrO2 is shown. Figure 16 The reflectance curves of the coatings with Al2O3 as the high refractive index oxide at different pH values ​​are shown. Figure 17 The reflectance curves of the coatings with ZrO2 as the high refractive index oxide are shown at different pH values. Figure 18 The reflectance curves of composite all-dielectric reflective films with different mass ratios are shown. Figure 19 The graph shows the reflectance curves of the coatings with Al2O3 as the high refractive index oxide at different annealing temperatures. Detailed Implementation

[0018] 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 and not intended to limit the scope of this application. Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various implementations. Simultaneously, the steps or actions described in the method description can be rearranged or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0019] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0020] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0021] The composite all-dielectric reflective film and its preparation method provided in this application are applied to excimer lamps. Excimer lamps are core devices in the current field of ultraviolet light sources, capable of emitting characteristic wavelengths and widely used in semiconductor wafer cleaning, public health disinfection, dermatological disease treatment, and VOCs degradation. Since the ultraviolet radiation from excimer lamps is spatially isotropic, approximately half of the photons dissipate towards the inside or sidewalls of the lamp tube. Therefore, a high-reflectivity film needs to be deposited on key surfaces of the lamp tube to reflect and recover ultraviolet light from non-emitting directions. This is a core means of improving the energy utilization rate of excimer lamps. Therefore, the reflectivity, UV aging resistance, and ozone resistance of the composite all-dielectric reflective film directly determine the brightness, energy consumption, and lifespan of the excimer lamp.

[0022] Existing methods for preparing reflective films suffer from high internal stress during drying and a tendency to crack. Specifically, during the drying and heat treatment aging stages of sol-gel films, severe volume shrinkage and residual internal stress occur due to the intense evaporation of solvents and deep condensation of the gel network. This leads to the formation of numerous penetrating network shrinkage cracks on the surface, causing strong ultraviolet light scattering and transmission loss, resulting in a precipitous drop in reflectivity. Secondly, the acidity and alkalinity of the solution lack scientific quantitative control, and the pH value is not precisely controlled according to the isoelectric point and charge activity of the doped oxide particles. If the ambient pH value is close to the isoelectric point of the nanoparticles, the electrostatic repulsion disappears, leading to irreversible hard agglomeration and a loose structure. Furthermore, the heat treatment parameters are incompatible. Different metal-oxygen bonds (Al-O and Zr-O) have different sintering and crystallization characteristics. The traditional one-size-fits-all annealing temperature cannot simultaneously ensure density and crack resistance. Specifically, too low a temperature results in residual hydroxyl groups and organic matter; too high a temperature leads to excessive grain coarsening and stress cracking. Finally, it is difficult to balance film thickness and uniformity. The parameters of the dip coating lack a quantitative window. If the film is too thin, the reflection efficiency is low. If the film is too thick, it is very easy to delaminate due to stress superposition, which affects the performance stability and production cost of the composite all-dielectric reflective film.

[0023] Based on this, this application provides a composite all-dielectric reflective film and its preparation method. The method involves providing a substrate with a masking layer adhered to one side; mixing an acidic conditioning solution and a powder mixture, followed by ultrasonic curing to obtain a sol, wherein the pH value of the acidic conditioning solution is a preset pH threshold; the powder mixture is prepared by mixing an alkoxide precursor solution, SiO2 powder, and high-refractive-index oxide powder, with the mass ratio of high-refractive-index oxide powder to SiO2 powder between 0.9:1 and 1.1:1; vertically immersing the substrate into the sol, and continuously depositing a film at a first lifting speed to a first quantity value, forming a dense thick film with a preset thickness on the side of the substrate away from the masking layer, thus obtaining a coated substrate; and drying and heat-insulating the coated substrate to obtain the composite all-dielectric reflective film. By synergistically controlling the pH threshold and heat-preserving sintering, the hydrolysis and polycondensation rates of high-refractive-index oxide powder and SiO2 powder are perfectly matched, promoting chemical bonding. This effectively avoids through-cracks in the composite all-dielectric reflective film, reduces its microporosity, and improves its adhesion. It also enhances the ultraviolet light intensity and photon recovery efficiency of the composite all-dielectric reflective film. The fabrication process of the composite all-dielectric reflective film is simple and inexpensive, suitable for coating the inner walls of irregularly shaped tubes, thus reducing the overall manufacturing cost.

[0024] The preparation method of the composite all-dielectric reflective film is described below with reference to the accompanying drawings.

[0025] Reference Figure 1 , Figure 1 A flowchart illustrating the preparation method of the composite all-dielectric reflective film provided in this application embodiment. Figure 1As shown, the preparation method of the composite all-dielectric reflective film includes: S1000 provides a substrate with a cover layer adhered to one side.

[0026] It is understandable that a cleaned glass substrate is used as the base, and a masking layer is adhered to one side of the substrate to avoid double-sided coating. In this embodiment, the masking layer is made of transparent adhesive. By adhering transparent adhesive to one side of the substrate, the side of the substrate with the transparent adhesive is prevented from contacting the sol and being exposed to the film particle flow, thus achieving single-sided coating. In other embodiments, a masking layer such as pressure-sensitive adhesive tape can also be used to fully cover and firmly adhere the back of the substrate, and roll forming can be used to achieve a bubble-free gap, thereby saving production costs and improving the production efficiency of composite all-dielectric reflective films.

[0027] It is understandable that, in order to ensure the cleanliness of the substrate, ultrasonic, isopropanol, and plasma cleaning processes can be used to ensure that the surface of the substrate is completely hydrophilic. Otherwise, the subsequent sol-gel process may result in pinholes and edge shrinkage.

[0028] S2000, after mixing the acidic conditioning solution and the powder mixture, is ultrasonically cured to obtain a sol. The pH value of the acidic conditioning solution is a preset pH threshold. The powder mixture is made by mixing alkoxide precursor solution, SiO2 powder and high refractive index oxide powder. The mass ratio of high refractive index oxide powder to SiO2 powder is between 0.9:1 and 1.1:1. The pH threshold is determined by the high refractive index oxide.

[0029] It is understood that a sol is a stable colloidal solution composed of metal alkoxides or inorganic salts. The sol is coated onto a glass substrate, and through solvent evaporation or hydrolysis-condensation, it transforms into a gel film, which is then sintered by heat treatment to obtain a solid film of oxide. In this process, the sol is formed by mixing an acidic conditioning solution and a powder mixture, followed by ultrasonic cavitation to accelerate the reaction and break up agglomerates, significantly shortening the mixing time of the acidic conditioning solution and the powder mixture. In this application, to ensure the low activity of metal ions in the high-refractive-index oxide and the acidic inhibition of condensation, thereby improving the adhesion of the sol, the pH value of the acidic conditioning solution needs to be strictly controlled to reach a preset pH threshold.

[0030] Reference Figure 2 , Figure 2 This is a flowchart illustrating the preparation of an acidic conditioning solution when the high-refractive-index oxide is Al₂O₃. Figure 2 As shown, the above step S2000 includes at least: S2100, mix 1.31g of deionized water with 0.33g of hydrochloric acid solution to obtain hydrochloric acid mixture, wherein the concentration of hydrochloric acid solution is 1mol / L.

[0031] It is understandable that during the preparation of the coating sol, in order to avoid the presence of Ca in tap water or mineral water...2+ Mg 2 + Na + Metallic impurities can directly interfere with hydrolysis and polymerization, causing problems such as sol turbidity, particle agglomeration, film pinholes, haze, refractive index drift, and poor batch repeatability. Deionized water is water in which anions and cations such as calcium, magnesium, sodium, potassium, chloride, and sulfate ions are removed through ion exchange resins; that is, deionized water removes most of the dissolved salt ions. Therefore, it is necessary to use deionized water mixed with hydrochloric acid solution. Specifically, to avoid direct addition of concentrated hydrochloric acid to the powder mixture, a dilute hydrochloric acid solution must be prepared in advance, i.e., a hydrochloric acid mixture. The concentration of the hydrochloric acid solution is 1 mol / L, that is, 1 liter of hydrochloric acid solution contains 1 mol of HCl solute.

[0032] S2200, add 2.48g of deionized water to the first reagent bottle, then add hydrochloric acid mixture, mix well to obtain an acidic adjusting solution with a pH value of 2.5.

[0033] Understandably, to precisely control the pH value of the precursor and ensure that the pH value of the acidic adjusting solution equals the preset pH threshold, it is necessary to accurately control the mixing ratio of hydrochloric acid mixture and deionized water. The precursor refers to the initial substance used to generate the target product during a chemical reaction or material preparation process, and its properties directly affect the performance of the final product. The pH threshold is determined by the properties of the high-refractive-index oxide. (Refer to...) Figure 10 and Figure 11 , Figure 10 The images show the surface morphology of the films coated with Al2O3 at different pH values ​​at 10kx magnification. Figure 11 The images show the 1kx surface morphology of films coated with Al2O3 as the high refractive index oxide at different pH values. Figure 10 and 11 As shown, when the high refractive index oxide is Al2O3, under strong acidity (pH=2.0), the hydrolysis of ethyl silicate is too rapid while the condensation polymerization is delayed, resulting in uneven particle size and loose packing in the dense thick film. When pH=2.5, the hydrolysis and condensation reaction rates reach a perfect balance, the cross-linking degree of the gel network is moderate, and the internal stress during drying can be evenly dispersed, completely eliminating through-drying network cracks, resulting in a continuous, smooth, and dense film. When pH=3.0, the condensation rate is too fast, the rigidity of the gel increases dramatically, and the shrinkage stress cannot be dispersed, resulting in dense through-drying network or triangular shrinkage cracks on the film surface. Therefore, in this embodiment, the pH threshold is 2.5. Specifically, 2.48g of deionized water is mixed with the hydrochloric acid mixture obtained in step S2100 to obtain an acidic adjusting solution with a pH of 2.5.

[0034] Reference Figure 14 , Figure 14The image shows the infrared spectrum of the composite all-dielectric reflective film with Al2O3 as the high refractive index oxide. It can be seen that when the pH threshold is 2.5, the absorbance is relatively large at the positions of each absorption peak, indicating better optical performance.

[0035] Reference Figure 16 , Figure 16 The graphs show the reflectance curves of the coatings with Al2O3 as the high refractive index oxide at different pH values. It can be seen that the composite all-dielectric reflective film prepared at a pH threshold of 2.5 has the best optical uniformity across the entire wavelength band and reaches its peak reflectance. However, the sample at pH=3.0 suffers from severe light scattering and transmission loss due to dense cracks, and its ultraviolet reflectance drops sharply to 65%-68%.

[0036] Reference Figure 3 , Figure 3 This is a flowchart illustrating the preparation process of a powder mixture when the high-refractive-index oxide is Al2O3. Figure 3 As shown, the above step S2000 also includes at least: S2300, add 9.9g of anhydrous ethanol and 1.65g of tetraethyl orthosilicate to the second reagent bottle in sequence, and mix by ultrasonication for the preset first time to obtain the alkoxide precursor solution.

[0037] Understandably, tetraethyl orthosilicate (TEOS) is used as a reagent in organic synthesis, acting as a catalyst or reaction intermediate in various organic reactions. TEOS, as a precursor, provides silicon (Si) and, after annealing, forms a SiO2 film. Anhydrous ethanol, as the precursor solvent, does not directly participate in the hydrolysis reaction; its role is to dissolve TEOS, ensuring its miscibility with water and preventing stratification and precipitation. Hydrolysis only occurs with the addition of water. When only TEOS and anhydrous ethanol are mixed, without adding additional water, they react almost entirely, and the alkoxide precursor solution remains a transparent liquid for a long time.

[0038] It is understandable that ultrasonic mixing utilizes the cavitation effect and acoustic flow of ultrasound to achieve efficient dispersion, mixing, and reaction of substances in liquid or solid-liquid systems. Therefore, ultrasonic mixing of anhydrous ethanol and tetraethyl orthosilicate can improve the mixing effect and shorten the mixing time. It should be noted that to ensure thorough mixing of 9.9g of anhydrous ethanol and 1.65g of tetraethyl orthosilicate, ultrasonic mixing is required to achieve full mixing within 1 minute to obtain the alkoxide precursor solution; that is, the initial mixing time is 1 minute.

[0039] S2400, SiO2 powder is added to the alkoxide precursor solution in batches. After each addition, the mixture is ultrasonically mixed for a preset second time before the next batch is added, until the weight of SiO2 powder reaches 4.13g, and the first mixture is obtained.

[0040] Understandably, after obtaining the alkoxide precursor solution, in order to fully mix it with the SiO2 powder, it is necessary to add the SiO2 powder in small batches and perform ultrasonic mixing for a second time before proceeding to the next mixing step. This ensures that the alkoxide precursor solution and the 4.13g of SiO2 powder are fully mixed to obtain the first mixture. In practical applications, the 4.13g of SiO2 powder is added in small batches, and after each batch, it is ultrasonically mixed for 1 minute until completely dispersed, i.e., the second time is 1 minute.

[0041] S2500, Al2O3 powder is added to the first mixture in batches, and ultrasonic mixing is carried out for a preset third time to obtain the second mixture, wherein the weight of Al2O3 powder is between 3.72g and 4.54g.

[0042] Understandably, after the SiO2 powder is dispersed, 300 nm Al2O3 powder is added in batches. Since the weight of the SiO2 powder is 4.13 g, the mass ratio of Al2O3 to SiO2 is controlled to be 0.9:1-1.1:1 (i.e., 0.9 times the mass corresponds to 3.72 g, 1.0 times corresponds to 4.13 g, and 1.1 times corresponds to 4.54 g). Within this mass ratio range, the microporosity of the film can be precisely controlled within the range of 5.910%-17.967%, ensuring the optical performance of the composite all-dielectric reflective film. After the addition is complete, the film is placed in an ultrasonic cleaner and continuously ultrasonicated for 33 minutes to ensure that the second mixture is completely free of agglomeration; the third time is 33 minutes.

[0043] Reference Figure 18 , Figure 18 This shows the reflectivity curves of composite all-dielectric reflective films with different mass ratios. Figure 18 As shown, since the pore size inside the membrane is close to the ultraviolet wavelength, a significant Mie scattering effect will be generated. The increased porosity leads to enhanced interface scattering, which, combined with the increased proportion of high-refractive-index Al2O3, increases the refractive index difference. The synergistic effect of these two factors increases the overall reflectivity with the increase of the feed mass ratio. The overall reflectivity is optimal when the mass ratio is 1.0-1.1 times.

[0044] Reference Figure 4 , Figure 4 This is a flowchart illustrating the preparation of sol when the high-refractive-index oxide is Al2O3. Figure 4 As shown, the above step S2000 also includes at least: S2600, slowly pour the acidic conditioning solution from the first reagent bottle into the second reagent bottle, and stir until homogeneous to obtain the third mixture.

[0045] Understandably, an acidic conditioning solution is used to regulate the slightly acidic environment of the second mixture, with its pH value precisely controlled at 2.5, so as to achieve the best match between hydrolysis and polycondensation rates and eliminate through-drying network cracks in the coating.

[0046] S2700, the third mixture is ultrasonically mixed for a preset fourth time to obtain a sol.

[0047] Understandably, after uniformly stirring to obtain the third mixture, it needs to be continuously ultrasonically cured for 6 hours to obtain a stable and uniform Al2O3-SiO2 composite precursor sol, i.e., the fourth time is 6 hours. Specifically, ultrasonic curing utilizes the ultrasonic cavitation effect to replace long-term static standing, accelerating the internal hydrolysis and condensation of the third mixture, breaking up colloidal agglomerates, and removing microbubbles, allowing the sol to quickly reach a state suitable for coating. Ordinary static curing relies on molecular thermal motion and often takes several days for the sol to reach a suitable coating state. Ultrasonic curing greatly shortens the curing time.

[0048] S3000: The substrate is vertically immersed in the sol, and a first amount of film is continuously deposited at a first lifting speed to reach a first quantity value. A dense thick film with a preset thickness is formed on the side of the substrate away from the masking layer, thus obtaining a coated substrate.

[0049] Understandably, after preparing the sol through the above steps, coating is performed using the dip-coating method, which is a classic film-forming process. Specifically, the substrate is vertically immersed in the sol, left to stand, and then pulled vertically upwards at a uniform speed. Relying on the balance of sol viscosity, surface tension, and gravity, a wet gel film forms on the substrate surface. This film is then dried, pre-baked, and annealed at high temperature to obtain an inorganic oxide film.

[0050] Reference Figure 5 , Figure 5 This is a flowchart of step S3000 when the high refractive index oxide is Al2O3. (Example) Figure 5 As shown, the above step S3000 also includes at least: S3100: The substrate is vertically immersed in the sol, and the first lifting speed is controlled at 30 cm / min to perform the coating operation on the substrate.

[0051] Understandably, during the coating process, vertically immersing the substrate in the sol and pulling it upwards at a uniform speed—the rate at which the substrate is pulled out—is the most crucial parameter for controlling film thickness. Specifically, the faster the pull speed, the thicker the entrained liquid film, and the thicker the solid film after annealing. However, if the pull speed is too fast, for example, >150 mm / min, it will result in a very thick wet film; the total film thickness after annealing will be too large, easily causing cracks, and surface disturbance will lead to ripples and runs, resulting in poor coating uniformity. If the speed is too slow, for example, <20 mm / min, most of the sol will flow back into the bath due to gravity, resulting in a very thin film; the evaporation effect will also dominate, leading to an unstable meniscus and poor film thickness reproducibility. Therefore, it is necessary to select an appropriate initial pull speed for the coating operation on the substrate.

[0052] It should be noted that after the substrate is completely submerged, it needs to stand for 60-120 seconds to ensure that the side of the substrate away from the masking layer is completely wetted and to eliminate surface air bubbles. Then, start lifting upwards at the first lifting speed to complete one coating operation.

[0053] The S3200 was used to perform four consecutive coating operations, and after each coating operation, the coating was allowed to stand and dry at room temperature for 30 minutes.

[0054] Understandably, to obtain the desired coating thickness, it's not advisable to simply increase the pull-up speed. A multi-layer dip-coating method is preferred, involving dip-coating → drying → re-dip-coating, stacking multiple layers to increase the coating thickness. Simultaneously, each layer should be kept below 200nm to reduce the risk of annealing cracking. Therefore, to increase the thickness of the composite all-dielectric reflective film, four consecutive coating operations are required. After each pull-up coating, the film is allowed to dry at room temperature for 30 minutes. Under these controlled parameters, due to the low activity of aluminum ions and the acid-inhibited polymerization effect, the sol adhesion is extremely strong, forming a dense film with a cumulative thickness of up to 24.378μm on the substrate. It should be noted that performing the coating operation three times at a speed of 36cm / min yields a coating with optimal thickness uniformity, ranging from 18.218 to 20.087μm.

[0055] S4000, after drying and heat preservation treatment of the coating substrate, yields a composite all-dielectric reflective film.

[0056] Understandably, after obtaining the coating substrate, it is hung vertically at room temperature for 15-30 minutes to allow the solvent to evaporate naturally. Afterward, the coating substrate needs to undergo drying and heat preservation treatment to complete pre-baking annealing, resulting in a stable and durable composite all-dielectric reflective film.

[0057] Reference Figure 6 , Figure 6 This is a flowchart of step S4000 when the high refractive index oxide is Al2O3. Figure 6 As shown, the above step S4000 includes at least: S4100: Place the coated substrate in an oven and keep it at 150°C for 1 hour to complete the initial drying.

[0058] Understandably, the substrate is placed in an oven and kept at 150°C for 1 hour to complete the initial drying. Initial drying, or pre-baking, is a low-temperature heat treatment after the film is stretched into a wet gel and before high-temperature annealing. First, initial drying removes most of the solvent. The wet film contains a large amount of precursor solvent; if directly thrown into a high-temperature furnace, the solvent will instantly and rapidly vaporize, causing pinholes, blistering, film cracking, and peeling. Pre-baking slowly evaporates the solvent at low temperatures. Second, initial drying completes most of the physical drying, allowing the gel network to initially solidify. The wet film is a soft gel; after pre-baking, it becomes a dry gel, and the film no longer flows or drips. During multi-layer stretching, pre-baking and cooling are necessary before applying the next layer; otherwise, the subsequent sol-gel layer will re-dissolve and destroy the previous wet film. Third, initial drying slowly completes residual hydrolysis and continues polycondensation. Small amounts of water and alcohol remain in the film, and hydrolysis and polycondensation continue at low temperatures, forming a preliminary metal element network, improving the mechanical strength of the film and preventing it from cracking during annealing. Finally, preliminary drying can avoid thermal shock and buffer the transition to high-temperature annealing. If the wet film is directly heated to 500°C, the huge thermal stress can easily lead to cracks. Preliminary drying provides a temperature step and reduces the stress of subsequent heating.

[0059] S4200 involves placing the pre-dried coating substrate into a muffle furnace and holding it at 300℃, 400℃, and 500℃ for 60 minutes each. After natural cooling in the furnace, a composite all-dielectric reflective film is obtained.

[0060] Understandably, the substrate obtained after initial drying is a porous dry gel film, containing a large number of hydroxyl groups (-OH), unhydrolyzed alkoxy groups (-OR), and residual carbon. It also suffers from numerous pores, poor mechanical strength, and low refractive index. High-temperature annealing is a crucial step in transforming the dry gel into a dense inorganic oxide film. Placing the initially dried substrate in a muffle furnace and holding it at 300℃, 400℃, and 500℃ for 60 minutes respectively removes residual organic matter and carbon. At high temperatures, the organic components oxidize and decompose, escaping as gases such as CO2 and H2O. Secondly, high-temperature annealing sinters and densifies the film, eliminating pores. Because the sol film is inherently porous, atomic diffusion at high temperatures causes pores to shrink and close, increasing the film density and simultaneously improving refractive index, hardness, and adhesion. Furthermore, high-temperature annealing releases internal stress within the film, improving coating stability. Internal stress is generated during film formation; annealing at appropriate heating and cooling rates can release some of this stress, improving film adhesion and reducing the risk of cracking and peeling.

[0061] It should be noted that during annealing at 300℃, the organic matter in the precursor does not decompose completely, leaving residues. The high OH content results in a loose structure. During high-temperature annealing at 500℃, Al2O3 maintains a highly crystalline corundum phase, the precursor undergoes complete thermal decomposition, the dehydration condensation reaction is most thorough, the Si-O-Si and Al-O-Si networks are most fully cross-linked, hydroxyl residue is lowest, the film density reaches the optimal level for this system, and no crack initiation occurs.

[0062] Reference Figure 19 , Figure 19 This shows the reflectance curves of films coated with Al2O3 as the high refractive index oxide at different annealing temperatures. Figure 19 As shown, annealing at 500℃ combined with a film thickness of 24.378μm enables the Al2O3-SiO2 composite reflective film to achieve a peak reflectivity of up to 92% in the entire ultraviolet band of 200-400nm. At the same time, it reaches a peak at 340-350nm, with only weak dispersion towards the 400nm end, while still maintaining a stable ultra-high reflectivity of 90%.

[0063] Understandably, the above steps involve detailed process design, fabrication, and testing analysis for the Al2O3-SiO2 composite reflective film system, which offers superior performance and more stable film formation. By synergistically controlling the four-dimensional properties of the precursor solution (weakly acidic pH=2.5), the feed mass ratio, the physical parameters of film formation (speed and number of times), and the crystallization annealing temperature (500℃), the problems of easy cracking, easy aggregation, and low reflectivity of sol-gel reflective films are thoroughly solved, achieving a peak reflectivity of up to 92% and excellent mechanical continuity in the full ultraviolet band of 200~400nm.

[0064] In other embodiments, ZrO2 can also be used as a high-refractive-index oxide to prepare a ZrO2-SiO2 composite reflective film. Due to the high charge and strong activity of zirconium ions, and the isoelectric point of ZrO2 particles in the pH range of 4.0-6.0, the process parameters produce differentiated responses.

[0065] Reference Figure 7 , Figure 7 This is a flowchart illustrating the preparation of an acidic conditioning solution when the high-refractive-index oxide is ZrO2. Figure 7 As shown, the above step S2000 also includes at least: S2510, ZrO2 powder is added to the first mixture in batches, and ultrasonic mixing is performed for a preset third time to obtain a second mixture, wherein the weight of ZrO2 powder is between 3.72g and 4.54g.

[0066] It is understood that, consistent with step S2500 above, after obtaining the first mixture, ZrO2 powder needs to be added in batches and ultrasonically mixed for a preset third time to obtain the second mixture. The specific process is the same as the above steps and will not be repeated here.

[0067] Reference Figure 8 , Figure 8 This is a flowchart illustrating the preparation of sol when the high-refractive-index oxide is ZrO2. Figure 8 As shown, the above step S2000 also includes at least: S2610, slowly pour the acidic conditioning solution into the second reagent bottle, stir well to obtain the third mixture, the pH value of the acidic conditioning solution is 9.

[0068] Understandably, due to the charge characteristics of zirconium ions, the acidic conditioning solution requires weakly alkaline pH control: the precursor system must be controlled to be weakly alkaline, i.e., pH threshold = 9.0. Under this condition, the ZrO2 particles carry a high density of negative charges on their surface, generating strong electrostatic repulsion to inhibit irreversible hard agglomeration and eliminate through-cracks. It should be noted that if the pH value is strongly acidic at 2.0, zirconium ions are close to their isoelectric point, resulting in severe hard agglomeration and numerous cracks, making it difficult to guarantee the formation of the composite all-dielectric reflective film. (Refer to...) Figure 12 and Figure 13 , Figure 12 The images show the surface morphology of the films coated with ZrO2 at different pH values ​​at 10kx magnification. Figure 13 The images show the 1kx surface morphology of the films coated with ZrO2 as the high refractive index oxide at different pH values. Figure 12 and Figure 13 As shown, when pH=9, the hydrolysis and condensation reaction rates reach perfect equilibrium, the gel network cross-linking degree is moderate, and the internal stress during drying is uniformly dispersed, completely eliminating through-drying network cracks, resulting in a continuous, smooth, and dense film. (Refer to...) Figure 15 , Figure 15 The image shows the infrared spectrum of the composite all-dielectric reflective film with high refractive index oxide ZrO2. It can be seen that when the pH threshold is 9, the absorbance is relatively large at the positions of each absorption peak, indicating better optical performance.

[0069] Reference Figure 17 , Figure 17 The graphs show the reflectance curves of the coatings with high refractive index oxide ZrO2 at different pH values. It can be seen that the composite all-dielectric reflective film prepared with a pH threshold of 9 has the best optical uniformity across the entire wavelength band and reaches its peak reflectance.

[0070] Reference Figure 9 , Figure 9 This is a flowchart of step S4000 when the high refractive index oxide is ZrO2. Figure 9As shown, the above step S4000 also includes at least: S4300 involves placing the pre-dried coating substrate into a muffle furnace and holding it at 300°C and 400°C for 60 minutes each. After natural cooling in the furnace, a composite all-dielectric reflective film is obtained.

[0071] Understandably, when the high-refractive-index oxide is ZrO2, the optimal annealing temperature is 400℃. This is because the porosity is lowest at this temperature, reaching 12.906% at a 1.0 mass ratio. If the annealing temperature is increased to 500℃, the monoclinic ZrO2 grains grow excessively, generating micro-interstic gaps and microcracks, leading to a decrease in reflectivity. The pre-dried coating substrate is placed in a muffle furnace and held at 300℃ and 400℃ for 60 minutes respectively. After natural cooling in the furnace, a ZrO2-SiO2 composite all-dielectric reflective film is obtained.

[0072] It should be noted that when the high refractive index oxide is ZrO2, the first pulling speed during the dip coating process is 30 cm / min. After four coatings, a ZrO2-SiO2 reflective film with a thickness of 10.629 μm is obtained. Under the optimal process, the peak reflectivity of ZrO2-SiO2 in the 250~400nm band can reach 88%.

[0073] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network nodes. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0074] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0075] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0076] In the several embodiments provided in this application, it should be understood that the disclosed systems, instruments, and methods can be implemented in other ways. For example, the instrument embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the shown or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between instruments or units may be electrical, mechanical, or other forms. Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, i.e., they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0077] It should also be understood that the various implementation methods provided in this application can be combined arbitrarily to achieve different technical effects.

[0078] The above is a detailed description of the preferred embodiments of this application. However, this application is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. Composite all-dielectric reflective film Preparation method, characterized in that, Includes the following steps: A substrate is provided, one side of which is adhered with a cover layer; After mixing the acidic conditioning solution and the powder mixture, ultrasonic curing is performed to obtain a sol. The pH value of the acidic conditioning solution is a preset pH threshold. The powder mixture is prepared by mixing an alkoxide precursor solution, SiO2 powder, and high refractive index oxide powder. The mass ratio of the high refractive index oxide powder to the SiO2 powder is between 0.9:1 and 1.1:

1. The pH threshold is determined by the high refractive index oxide. The substrate is vertically immersed in the sol, and a first number of films are continuously deposited at a first lifting speed to form a dense thick film with a preset thickness on the side of the substrate away from the masking layer, thereby obtaining a coated substrate. After drying and heat preservation treatment of the coating substrate, a composite all-dielectric reflective film is obtained.

2. The method for preparing the composite all-dielectric reflective film according to claim 1, characterized in that, The mixture of acidic conditioning solution and powder is then subjected to ultrasonic ripening, including: 1.31 g of deionized water and 0.33 g of hydrochloric acid solution were mixed to obtain a hydrochloric acid mixture, wherein the concentration of the hydrochloric acid solution was 1 mol / L. Add 2.48g of deionized water to the first reagent bottle, then add the hydrochloric acid mixture, mix well, and obtain the acidic adjusting solution with a pH of 2.

5.

3. The method for preparing the composite all-dielectric reflective film according to claim 2, characterized in that, The powder mixture is prepared by mixing alkoxide precursor solution, SiO2 powder, and high refractive index oxide powder, including: Add 9.9g of anhydrous ethanol and 1.65g of tetraethyl orthosilicate to the second reagent bottle in sequence, and mix by ultrasonication for a preset first time to obtain the alkoxide precursor solution. SiO2 powder was added to the alkoxide precursor solution in batches. After each addition, the mixture was ultrasonically mixed for a preset second time before the next batch was added, until the weight of the SiO2 powder reached 4.13g, thus obtaining the first mixture. Al2O3 powder is added to the first mixture in batches and ultrasonically mixed for a preset third time to obtain a second mixture, wherein the weight of the Al2O3 powder is between 3.72g and 4.54g.

4. The method for preparing the composite all-dielectric reflective film according to claim 3, characterized in that, The process of ultrasonic curing after mixing the acidic conditioning solution and the powder mixture also includes: Slowly pour the acidic adjusting solution from the first reagent bottle into the second reagent bottle and stir until homogeneous to obtain the third mixture; The third mixture is ultrasonically mixed for a preset fourth time to obtain the sol.

5. The method for preparing the composite all-dielectric reflective film according to claim 3, characterized in that, The step of vertically immersing the substrate into the sol and continuously depositing a film at a first lifting speed to reach a first quantity value includes: The substrate is vertically immersed in the sol, and the first lifting speed is controlled at 30 cm / min to perform a coating operation on the substrate. The coating operation was performed four times consecutively, and after each coating operation, the mixture was allowed to stand and dry at room temperature for 30 minutes.

6. The method for preparing the composite all-dielectric reflective film according to claim 3, characterized in that, After drying and heat preservation treatment of the coating substrate, a composite all-dielectric reflective film is obtained, comprising: The coated substrate is placed in an oven and kept at 150°C for 1 hour to complete the initial drying; The pre-dried coating substrate is placed in a muffle furnace and held at 300°C, 400°C and 500°C for 60 minutes respectively. After natural cooling in the furnace, the composite all-dielectric reflective film is obtained.

7. The method for preparing the composite all-dielectric reflective film according to claim 1, characterized in that, The powder mixture is prepared by mixing alkoxide precursor solution, SiO2 powder, and high refractive index oxide powder, including: Add 9.9g of anhydrous ethanol and 1.65g of tetraethyl orthosilicate to the second reagent bottle in sequence, and mix by ultrasonication for a preset first time to obtain the alkoxide precursor solution. SiO2 powder was added to the alkoxide precursor solution in batches. After each addition, the mixture was ultrasonically mixed for a preset second time before the next batch was added, until the weight of the SiO2 powder reached 4.13g, thus obtaining the first mixture. ZrO2 powder is added to the first mixture in batches and ultrasonically mixed for a preset third time to obtain a second mixture, wherein the weight of the ZrO2 powder is between 3.72g and 4.54g.

8. The method for preparing the composite all-dielectric reflective film according to claim 7, characterized in that, The process of ultrasonic curing after mixing the acidic conditioning solution and the powder mixture also includes: The acidic adjusting solution is slowly poured into the second reagent bottle and stirred until homogeneous to obtain a third mixture. The pH value of the acidic adjusting solution is 9. The third mixture is ultrasonically mixed for a preset fourth time to obtain the sol.

9. The method for preparing the composite all-dielectric reflective film according to claim 8, characterized in that, After drying and heat preservation treatment of the coating substrate, a composite all-dielectric reflective film is obtained, comprising: The coated substrate is placed in an oven and kept at 150°C for 1 hour to complete the initial drying; The pre-dried coating substrate is placed in a muffle furnace and held at 300°C and 400°C for 60 minutes each. After natural cooling in the furnace, the composite all-dielectric reflective film is obtained.

10. A composite all-dielectric reflective film, characterized in that, Prepared by the preparation method according to any one of claims 1-9.

Images