Infrared antireflection film, infrared metallized antireflection film, method for preparing the same, and use thereof

Abstract

The application provides an infrared antireflection film, an infrared metallized antireflection film, a preparation method and application thereof. The infrared antireflection film is based on silicon, antireflection films are plated on two sides of the substrate, and the film system structure of the antireflection films is (HL)^S independently; wherein H represents a Si layer, L represents a SiO layer, S represents a HL basic structure period number, the value of S is an integer between 3-6, and the Si layer is adjacent to the substrate, and the SiO layer is located on the surface layer. According to the technical scheme of the application, the film layer has strong compactness, is not prone to film cracking and film peeling, and has no water absorption band in the 3-5 mu band. The SiO film layer has large surface hardness as the outermost layer, and does not need to be additionally protected. The refractive index of SiO is low, the use of SiO as the outermost layer can also reduce the surface reflectivity, and further increase the infrared light transmittance. Since Si and SiO are relatively inexpensive and easy to obtain, the production cost can be saved.

Description

Technical Field

[0001] This invention relates to the field of infrared optical thin film technology, and more specifically, to an infrared antireflection film, an infrared metallized antireflection film, its preparation method, and its application. Background Technology

[0002] With the rapid development of technologies such as atmospheric detection, military applications, spectroscopy, and industrial monitoring, the application of optical thin films in the infrared band has attracted increasing attention. The 3-5μm band is an important atmospheric window and the main operating band of infrared detectors. Infrared antireflection coatings are most widely used on optical elements in this band. Generally, an average transmittance of over 99% is required on one side in the 3-5μm band.

[0003] Silicon is a commonly used substrate in the 3-5μm wavelength range. Its refractive index is 3.4, and the transmittance of a bare substrate is approximately 56%. Due to its high surface reflectivity, it is necessary to deposit multiple layers of antireflective dielectric films to increase transmittance, reduce light energy loss, and improve light energy transmission efficiency.

[0004] The commonly used deposition method is to deposit multilayer films of thin film materials such as Ge, ZnS, and YbF3 on a silicon substrate. The general structure is Sub|HMHMLM|Air, where Sub is the silicon substrate, H represents Ge, M represents ZnS, and L represents YbF3. In the 3-5μm wavelength range, this film system design and process can achieve an average transmittance of more than 96% after silicon wafer deposition.

[0005] In commonly used coating methods, fluoride YbF3 readily absorbs moisture from the air, forming a water absorption band around 3μm, which reduces the transmittance of optical components. Furthermore, YbF3 films are generally thick, resulting in high stress and a tendency to peel off. The films are also soft with low surface hardness, necessitating the deposition of a ZnS protective layer. However, ZnS has a higher refractive index than YbF3; a thin ZnS film is insufficient for protection, while a thicker ZnS film reduces transmittance to some extent. Therefore, conventional coating methods using materials such as Ge, ZnS, and YbF3 do not offer ideal performance in terms of both transmittance and film strength.

[0006] Another patent, CN111812753A, discloses a 3-6μm infrared window on a silicon substrate. The infrared window uses monocrystalline silicon as the substrate, and both sides of the substrate are coated with a single-layer antireflection film. The antireflection film is selected from silicon monoxide film or yttrium oxide film. At a specific thickness (the thickness of the silicon monoxide antireflection film is 0.537-0.696μm, and the thickness of the yttrium oxide antireflection film is 0.502-0.689μm), the single-layer antireflection film structure on both sides can make the infrared window have an average transmittance of ≥90% and an extreme transmittance of ≥98% in the infrared band of 3-6μm. However, the transmittance of the element still cannot meet the requirements of high transmittance (above 99%) optical systems. Summary of the Invention

[0007] The main objective of this invention is to provide an infrared antireflection film, an infrared metallized antireflection film, its preparation method and application, so as to solve the problem of low transmittance of optical elements for infrared light with a wavelength of 3-5μm in the prior art.

[0008] To achieve the above objectives, according to one aspect of the present invention, an infrared antireflection film is provided. The infrared antireflection film uses silicon as a substrate, and antireflection films are deposited on both sides of the substrate. The film system structure of each antireflection film is independently (HL)^S; where H represents a Si layer, L represents a SiO layer, S represents the number of cycles of the HL basic structure, and S takes the value of an integer between 3 and 6. The layer adjacent to the substrate is the Si layer, and the layer on the surface is the SiO layer.

[0009] Furthermore, S is 5, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 280-320nm, SiO layer thickness 36-58nm, Si layer thickness 151-191nm, SiO layer thickness 255-297nm, Si layer thickness 35-57nm, SiO layer thickness 570-640nm, Si layer thickness 108-150nm, SiO layer thickness 86-108nm, Si layer thickness 276-318nm, SiO layer thickness 474-536nm;

[0010] And / or, S is 3, the thicknesses of each film layer from the substrate are as follows: Si layer thickness 112-152nm, SiO layer thickness 24-34nm, Si layer thickness 350-410nm, SiO layer thickness 44-64nm, Si layer thickness 142-182nm, SiO layer thickness 524-584nm.

[0011] And / or, S is 4, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 80-120nm, SiO layer thickness 24-34nm, Si layer thickness 45-55nm, SiO layer thickness 25-35nm, Si layer thickness 656-716nm, SiO layer thickness 80-120nm, Si layer thickness 590-650nm, SiO layer thickness 504-564nm;

[0012] And / or, S is 6, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 26-36nm, SiO layer thickness 15-25nm, Si layer thickness 353-413nm, SiO layer thickness 54-64nm, Si layer thickness 154-174nm, SiO layer thickness 309-349nm, Si layer thickness 29-39nm, SiO layer thickness 612-672nm, Si layer thickness 135-155nm, SiO layer thickness 78-88nm, Si layer thickness 280-320nm, SiO layer thickness 500-560nm.

[0013] According to another aspect of the present invention, an infrared metallized antireflection film is provided, comprising a substrate and antireflection films respectively disposed on two surfaces of the substrate, wherein the outer edge of the antireflection film on one surface has a metal film; the metal film comprises a connecting layer, a blocking layer and a welding layer disposed sequentially, wherein the connecting layer is disposed on the surface of the substrate.

[0014] Furthermore, the width of the metal film is ≥0.2mm;

[0015] Preferably, the bonding layer is either Cr or Ti, and preferably, the thickness of the bonding layer is 50-70 nm.

[0016] Preferably, the barrier layer is either Cu or Ni, and the thickness of the barrier layer is preferably 100-120 nm.

[0017] Preferably, the welding layer is any one of metal Au or metal Ni, and the thickness of the preferred welding layer is 300-500 nm.

[0018] Furthermore, the antireflective membrane is any of the above-mentioned antireflective membranes.

[0019] According to another aspect of this application, a method for preparing any of the above-mentioned infrared antireflection films is provided, comprising: step S1, cleaning a silicon substrate, placing it in a coating machine, evacuating it, and baking it for a period of time; step S2, cleaning the substrate with an ion source, and, with the assistance of the ion source, alternately depositing Si layers and SiO layers on both sides of the substrate; step S3, after the Si layers and SiO layers are deposited, directly performing annealing treatment to obtain an infrared antireflection film.

[0020] Furthermore, in step S1, the baking temperature is 150-250℃ and the time is 1-2 hours;

[0021] And / or, in step S2, the Si layer is deposited by electron beam evaporation, preferably with a deposition rate of 0.2-0.5 nm / s;

[0022] And / or, in step S2, the SiO layer is deposited by resistance thermal evaporation, preferably at a deposition rate of 1-1.5 nm / s.

[0023] Further, the annealing process includes: holding the temperature at 155-145℃, 125-115℃, 95-85℃ and 65-55℃ for 10-20 minutes in sequence; preferably, the annealing process includes: holding the temperature at 150℃, 120℃, 90℃ and 60℃ for 15 minutes in sequence.

[0024] According to another aspect of this application, a method for preparing an infrared metallized antireflection film as described above is provided. The method includes: step S1, cleaning the substrate, setting a protective layer on the outer edge of one surface of the substrate, placing it in a coating machine, evacuating the vacuum, and baking for a period of time; step S2, cleaning the substrate with an ion source, and depositing antireflection films on both sides of the substrate with the assistance of the ion source, performing annealing treatment after the coating is completed, removing the protective layer at the outer edge, and obtaining a metal film to be coated; step S3, setting a protective layer on the antireflection film in the central region of the surface where the metal film to be coated is located, and sequentially depositing a connecting layer, a blocking layer, and a welding layer on the edge of the metal film to be coated; step S4, removing the protective layer to obtain an infrared metallized antireflection film.

[0025] According to another aspect of this application, the application of any of the above-mentioned infrared antireflection films and any of the infrared metallized antireflection films in light-transmitting devices in the 3-5μm wavelength band is provided.

[0026] Applying the technical solution of this invention, the antireflective coating material is selected from Si and SiO. Si has an optical transparency region of 1.1–9 μm and a refractive index of 3.4, while SiO has a transparency region of 0.4–9 μm and a refractive index of 1.82. During research, the researchers of this application accidentally discovered that alternating Si and SiO layers can significantly improve the infrared light transmittance of the antireflective coating on a silicon substrate. Furthermore, Si and SiO possess excellent optical and mechanical properties, high aggregation density, strong film compactness, and are not prone to cracking or delamination. They also have an anhydrous absorption band in the 3–5 μm wavelength range. The SiO film layer, as the outermost layer, has high surface hardness. With prolonged contact with air, it slowly reacts with O2 to form a very thin SiO2 film, further increasing its hardness, thus eliminating the need for an additional protective layer. The lower refractive index of SiO, when used as the outermost layer, also reduces surface reflectivity, further increasing infrared light transmittance. Using Si and SiO as antireflective membranes, compared to conventionally used materials such as Ge, ZnS, and YbF3, can save on production costs due to their lower price and availability. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 A schematic diagram of an infrared metallized antireflection film structure according to an embodiment of the present invention is shown; and

[0029] Figure 2 The transmittance spectrum of the silicon window according to Embodiment 8 of the present invention is shown.

[0030] The above figures include the following reference numerals: 100, metal film; 200, antireflection film. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0032] As analyzed in the background section of this application, there is a problem in the prior art where the transmittance of optical elements for infrared light with a wavelength of 3-5μm is low. In order to solve this problem, this application provides an infrared antireflection film, an infrared metallized antireflection film, its preparation method, and its application.

[0033] According to a typical embodiment of this application, an infrared antireflection film is provided. The infrared antireflection film uses silicon as a substrate, and antireflection films are deposited on both sides of the substrate. The film system structure of each antireflection film is independent as (HL)^S; where H represents the Si layer, L represents the SiO layer, S represents the number of cycles of the HL basic structure, and the value of S is an integer between 3 and 6. The layer adjacent to the substrate is the Si layer, and the layer on the surface is the SiO layer.

[0034] The antireflective coating material selected in this application is Si and SiO. Si has an optical transparency region of 1.1–9 μm and a refractive index of 3.4, while SiO has a transparency region of 0.4–9 μm and a refractive index of 1.82. During the research process, the researchers of this application accidentally discovered that alternating Si and SiO layers can significantly improve the infrared light transmittance of the antireflective coating on a silicon substrate. Furthermore, Si and SiO possess excellent optical and mechanical properties, high aggregation density, strong film compactness, and are not prone to cracking or delamination. They also have an anhydrous absorption band in the 3–5 μm wavelength range. The outermost SiO film has high surface hardness; with long-term contact with air, it slowly reacts with O2 to form a very thin SiO2 film, further increasing its hardness, thus eliminating the need for an additional protective layer. The lower refractive index of SiO, when used as the outermost layer, also reduces surface reflectivity, further increasing infrared light transmittance. Using Si and SiO as antireflective membranes can save production costs compared to conventionally used materials such as Ge, ZnS, and YbF3, because Si and SiO are cheaper and more readily available.

[0035] The antireflection films on both sides of the aforementioned infrared antireflection film substrate can be the same or different. When the same antireflection film is used, the antireflection films on both sides are mirror-symmetrical with respect to the substrate. The number of HL basic structure cycles S of the antireflection films on both sides of the substrate can be the same or different, and each HL structure can also be the same or different. In some embodiments of this application, the antireflection films on both sides of the substrate are mirror-symmetrical, which facilitates the preparation of the antireflection film and further simplifies the production process.

[0036] In some typical embodiments of this application, in the antireflection membrane structure, S is 5, and the thicknesses of each layer from the substrate are as follows: Si layer thickness 280-320nm, SiO layer thickness 36-58nm, Si layer thickness 151-191nm, SiO layer thickness 255-297nm, Si layer thickness 35-57nm, SiO layer thickness 570-640nm, Si layer thickness 108-150nm, SiO layer thickness 86-108nm, Si layer thickness 276-318nm, and SiO layer thickness 474-536nm, exhibiting high peak transmittance and average transmittance. Preferably, when S is 5, the thicknesses of each film layer from the substrate are as follows: Si layer thickness 302-304nm, SiO layer thickness 46-48nm, Si layer thickness 171-173nm, SiO layer thickness 275-277nm, Si layer thickness 45-47nm, SiO layer thickness 606-608nm, Si layer thickness 128-130nm, SiO layer thickness 96-98nm, Si layer thickness 296-298nm, SiO layer thickness 504-506nm. The peak transmittance of 3-5µm light reaches 99.6%, and the average transmittance is 98.9%, which meets the application requirements.

[0037] In some other typical embodiments of this application, S is 3, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 112-152nm, SiO layer thickness 24-34nm, Si layer thickness 350-410nm, SiO layer thickness 44-64nm, Si layer thickness 142-182nm, SiO layer thickness 524-584nm, the average transmittance of 3-5µm light is above 98.7%, and the peak transmittance is greater than 99.3%.

[0038] In some other typical embodiments of this application, S is 4, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 80-120nm, SiO layer thickness 24-34nm, Si layer thickness 45-55nm, SiO layer thickness 25-35nm, Si layer thickness 656-716nm, SiO layer thickness 80-120nm, Si layer thickness 590-650nm, SiO layer thickness 504-564nm, the average transmittance of 3-5µm light is greater than 98.9%, and the peak transmittance is greater than 99.5%.

[0039] In some other typical embodiments of this application, S is 6, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 26-36nm, SiO layer thickness 15-25nm, Si layer thickness 353-413nm, SiO layer thickness 54-64nm, Si layer thickness 154-174nm, SiO layer thickness 309-349nm, Si layer thickness 29-39nm, SiO layer thickness 612-672nm, Si layer thickness 135-155nm, SiO layer thickness 78-88nm, Si layer thickness 280-320nm, SiO layer thickness 500-560nm, with an average light transmittance of 3-5µm greater than 99.3% and a peak transmittance greater than 99.9%.

[0040] According to another typical embodiment of this application, an infrared metallized antireflection film is provided, including a substrate and antireflection films respectively disposed on two surfaces of the substrate, wherein the outer edge of one surface has a metal film; wherein the metal film includes a connecting layer, a blocking layer and a welding layer disposed sequentially, and the connecting layer is disposed on the surface of the substrate.

[0041] The bonding layer in the metal film has excellent adhesion to the silicon substrate, and the barrier layer can prevent the metal elements of the welding layer from diffusing downwards, thus preventing the metal of the welding layer from diffusing into the bonding layer or the substrate or antireflection film inside the bonding layer. The welding layer can be firmly welded to the lens barrel, chip device, etc. The metal film with this structure not only has a firm connection with the antireflection film, but also has good welding performance, which enables the infrared metallized antireflection film of this application to be welded to the lens barrel and chip, playing a sealing and pressure-maintaining role, and expanding the application range of silicon windows.

[0042] The material of the aforementioned substrate is not particularly required and can be selected from existing technologies, such as silicon substrates, ZnS substrates, Ge substrates, sapphire substrates, etc. The aforementioned infrared metallized antireflection film has no particular requirements regarding the substrate material or the film system structure of the antireflection film and can be selected from existing technologies. In some embodiments of this application, the infrared metallized antireflection film is as follows... Figure 1 As shown, the center of one of the surfaces (surface A) is an antireflective coating 100, and the edge is a metal film 200; the other surface, namely surface B, is also an antireflective coating 100.

[0043] The width of the metal film can be determined according to specific application requirements. In some embodiments of this application, the width of the metal film is ≥0.2mm, which can achieve both welding performance and allow infrared light to pass through the area.

[0044] In some preferred embodiments of this application, the bonding layer is either Cr or Ti, which provides better adhesion to the substrate or antireflection film. Preferably, the thickness of the bonding layer is 50-70 nm, which significantly improves the adhesion to the metal film.

[0045] The material of the aforementioned welding layer can be selected from existing materials that are easy to weld. In some embodiments of this application, the welding layer is either metal Au or metal Ni, which has good welding performance. Preferably, the thickness of the welding layer is 300-500 nm, which facilitates the implementation of the welding process.

[0046] In some preferred embodiments of this application, the barrier layer is either Cu or Ni, which provides a better barrier effect for the welding layer and can be firmly bonded to the connecting layer or welding layer. The thickness of the barrier layer is preferably 100-120nm, which better balances the barrier performance and manufacturing cost.

[0047] In some typical embodiments of this application, the antireflection film of the infrared metallization antireflection film is any of the above-mentioned antireflection films with (HL)^S film system structure, which has both high infrared light transmittance and good welding performance, and can simultaneously meet the requirements of silicon window coating index with high transmittance and packaging and testing devices.

[0048] According to another typical embodiment of this application, a method for preparing any of the above-mentioned infrared antireflection films is provided. The preparation method includes: step S1, cleaning the silicon substrate, placing it in a coating machine, evacuating it, and baking it for a period of time; step S2, cleaning the substrate with an ion source, and with the assistance of the ion source, alternately depositing Si layers and SiO layers on both sides of the substrate; step S3, after the Si layers and SiO layers are deposited, directly performing annealing treatment to obtain the infrared antireflection film.

[0049] The antireflection coating prepared by this method uses Si and SiO as the film material, which can significantly improve the infrared light transmittance of the antireflection coating on the silicon substrate. Furthermore, Si and SiO possess excellent optical and mechanical properties, high aggregation density, strong film compactness, and are not prone to cracking or delamination. They also have an anhydrous absorption band in the 3-5 μm wavelength range. The outermost SiO film has high surface hardness; with long-term contact with air, it slowly reacts with O2 to form a very thin SiO2 film, further increasing its hardness, thus eliminating the need for an additional protective layer. The low refractive index of SiO, used as the outermost layer, also reduces surface reflectivity, further increasing infrared light transmittance. Using Si and SiO as the antireflection coating, compared to conventionally used materials such as Ge, ZnS, and YbF3, saves production costs due to their lower cost and availability.

[0050] In some embodiments of this application, in step S1, the baking temperature is 150–250°C and the time is 1–2 hours, which is beneficial to improving the infrared light transmittance of the product. Preferably, before performing the coating process in step S2, the vacuum degree of the coating machine is evacuated to (3–9)*10. -4 Pa, more preferably 7*10 Pa -4 Pa.

[0051] In some embodiments of this application, in step S2, the substrate is cleaned with an ion source for 10 minutes, and the deposition process is ion source-assisted deposition, with parameters shown in Tables 1 and 2 below.

[0052] Table 1 Ion source parameters for cleaning substrates

[0053] cathode anode screen accelerate neutralization Beam 18A 80V 300V 200V 15A 150mA

[0054] Table 2 Ion source-assisted deposition parameters

[0055] cathode anode screen accelerate neutralization Beam 18A 80V 400V 200V 15A 200mA

[0056] The deposition methods for the Si and SiO layers can refer to existing technologies and have no special requirements. In some embodiments of this application, in step S2, the Si layer is deposited using electron beam evaporation, preferably with a deposition rate of 0.2–0.5 nm / s, resulting in better Si deposition. In some embodiments of this application, the SiO layer is deposited using resistance thermal evaporation, preferably with a deposition rate of 1–1.5 nm / s, resulting in even better SiO deposition.

[0057] In some preferred embodiments of this application, the film is not cooled directly after deposition, but undergoes annealing. The annealing process includes sequentially holding the film at 155-145°C, 125-115°C, 95-85°C, and 65-55°C for 10-20 minutes. This annealing process reduces the stress generated on the film during deposition and improves its mechanical strength. More preferably, the annealing process includes sequentially holding the film at 150°C, 120°C, 90°C, and 60°C for 15 minutes.

[0058] According to another typical embodiment of this application, a method for preparing an infrared metallized antireflection film according to any of the above-mentioned methods is provided. The method includes: step S1, cleaning the substrate, setting a protective layer on the outer edge of one of the surfaces of the substrate, placing it in a coating machine, evacuating the vacuum, and baking for a period of time; step S2, cleaning the substrate with an ion source, and depositing an antireflection film on both sides of the substrate with the assistance of the ion source, performing an annealing treatment after the coating is completed, removing the protective layer on the outer edge, and obtaining a metal film to be coated; step S3, setting a protective layer on the antireflection film in the central region of the surface where the metal film to be coated is located, and sequentially depositing a connecting layer, a blocking layer, and a welding layer on the edge of the metal film to be coated; step S4, removing the protective layer to obtain an infrared metallized antireflection film.

[0059] The infrared metallized antireflective film prepared by this method has excellent adhesion between the bonding layer and the silicon substrate in its metal film. The barrier layer can prevent the metal elements of the welding layer from diffusing downwards, avoiding the metal of the welding layer from diffusing to the bonding layer or the substrate inside the bonding layer. The welding layer can be firmly welded to the lens barrel, chip device, etc. The metal film with this structure not only has a strong connection with the antireflective film, but also has good welding performance, which makes the infrared metallized antireflective film of this application welded to the lens barrel and chip, playing a sealing and pressure-maintaining role, and expanding the application range of silicon windows.

[0060] In steps S1 and S2 of this preparation method, the specific treatment methods for the substrate and the process of depositing the antireflection film can refer to existing technologies or the above-mentioned preparation method for infrared antireflection films, and will not be repeated here. The above-mentioned protective layer is used to prevent contamination of the antireflection film medium during the metal film deposition process, which would affect the transmittance. The protective layer can be selected from existing technologies, including but not limited to photoresist or protective film.

[0061] In some typical embodiments of this application, the preparation method of the above-mentioned infrared metallized antireflection film includes: 1) ultrasonically cleaning the silicon substrate for 5-15 minutes each with acetone solution, anhydrous ethanol, and pure water, and wiping the substrate clean with degreased cotton before loading it onto a fixture. 2) After placing it in a coating machine, vacuuming is performed, the baking temperature is set to 150-250℃, and the temperature is maintained for 1-2 hours until the vacuum degree reaches (3-9)*10. -4After Pa, the deposition process begins. 3) The substrate is cleaned with an ion source for 10-20 minutes, and the deposition process is ion source-assisted. 4) Si is deposited using an electron gun at a deposition rate of 0.2-0.5 nm / s; SiO is deposited using a resistance thermal evaporation method at a deposition rate of 1-1.5 nm / s. Si and SiO are deposited alternately layer by layer on the center area of ​​surface A and surface B of the substrate to form a multilayer dielectric film. Photoresist is applied to the edge area of ​​surface A for protection using photolithography. 5) After deposition, the substrate is not cooled directly but annealed sequentially at 150℃, 120℃, 90℃, and 60℃ for 15 minutes. 6) After annealing, the lens is removed, and the photoresist in the edge area is removed using acetone solution or a photoresist remover. 7) A protective sheet or photoresist is used to protect the dielectric film in the center area of ​​surface A of the silicon window. The edge area is cleaned and then attached to the workpiece tray. 8) Place the film into a thermal evaporation coating machine or a magnetron sputtering coating machine to deposit a Cr film of 50-70 nm, a Cu or Ni film of 100-120 nm, and an Au film of 300-500 nm in sequence. 9) After the deposition is completed, remove the protective film, or use acetone solution or photoresist remover to remove the photoresist.

[0062] According to another typical embodiment of this application, the application of any of the above-described infrared antireflection films and any of the above-described infrared metallized antireflection films in light-transmitting devices in the 3-5μm wavelength band is provided. These infrared antireflection films and infrared metallized antireflection films have high transmittance for 3-5μm infrared light, good mechanical strength, and are made from inexpensive and readily available raw materials, thus resulting in low cost. In particular, the infrared metallized antireflection film not only has high light transmittance and can be welded to lens barrels, chip devices, etc., but also has strong pressure resistance, further expanding its application range.

[0063] The beneficial effects that this application can achieve will be further illustrated below with reference to embodiments and comparative examples.

[0064] Example 1

[0065] In this embodiment, an infrared metallized antireflection film is prepared according to the following steps:

[0066] 1. The silicon substrate was ultrasonically cleaned for 10 minutes each with acetone solution, anhydrous ethanol and pure water, and then wiped clean with degreased cotton before being loaded onto the fixture.

[0067] 2. After placing the coating machine, vacuum it, set the baking temperature to 150℃, maintain the temperature for two hours, and start coating when the vacuum degree reaches 7*10-4Pa.

[0068] 3. Clean the substrate with an ion source for 10 minutes. During the deposition process, use an ion source to assist in deposition. The parameters are shown in the table below.

[0069] Table 3 Ion source parameters for cleaning substrates

[0070] cathode anode screen accelerate neutralization Beam 18A 80V 300V 200V 15A 150mA

[0071] Table 4 Ion source-assisted deposition parameters

[0072] cathode anode screen accelerate neutralization Beam 18A 80V 400V 200V 15A 200mA

[0073] 4. Si was deposited using electron gun evaporation at a rate of 0.5 nm / s; SiO was deposited using resistance thermal evaporation at a rate of 1.2 nm / s. Multiple layers of dielectric films were formed by alternating evaporation of Si and SiO on the central region of surface A and surface B of the substrate. The optical film thicknesses, from closest to the substrate, were as follows: Si layer 303 nm, SiO layer 47 nm, Si layer 172 nm, SiO layer 276 nm, Si layer 46 nm, SiO layer 607 nm, Si layer 129 nm, SiO layer 97 nm, Si layer 297 nm, and SiO layer 505 nm.

[0074] 5. After plating, do not cool down directly. Instead, use an annealing process, and keep the temperature constant at 150℃, 120℃, 90℃, and 60℃ for 15 minutes in sequence.

[0075] The silicon window was tested using an infrared Fourier transform spectrometer, and the average transmittance of 3-5 μm light was 98.9%, with a peak transmittance of 99.6%.

[0076] Example 2

[0077] The difference from Example 1 is that in step 4, the thicknesses of the optical film layers, starting from the substrate, are as follows: Si layer thickness 300nm, SiO layer thickness 50nm, Si layer thickness 170nm, SiO layer thickness 270nm, Si layer thickness 45nm, SiO layer thickness 600nm, Si layer thickness 130nm, SiO layer thickness 100nm, Si layer thickness 295nm, and SiO layer thickness 500nm.

[0078] The silicon window was tested using an infrared Fourier transform spectrometer. The average transmittance of 3-5 μm light was 98.9%, and the peak transmittance was 99.6%.

[0079] Example 3

[0080] The difference from Example 1 is that in step 4, the thicknesses of the optical film layers, starting from the substrate, are as follows: Si layer thickness 270nm, SiO layer thickness 60nm, Si layer thickness 150nm, SiO layer thickness 300nm, Si layer thickness 60nm, SiO layer thickness 570nm, Si layer thickness 160nm, SiO layer thickness 90nm, Si layer thickness 250nm, and SiO layer thickness 550nm.

[0081] The silicon window was tested using an infrared Fourier transform spectrometer. The average transmittance of 3-5 μm light was 75.3%, and the peak transmittance was 87.9%.

[0082] Example 4

[0083] The difference from Example 1 is that in step 4, the thicknesses of the optical film layers from the closest to the substrate are as follows: Si layer thickness 132nm, SiO layer thickness 29nm, Si layer thickness 380nm, SiO layer thickness 54nm, Si layer thickness 162nm, and SiO layer thickness 554nm.

[0084] The silicon window was tested using an infrared Fourier transform spectrometer. The average transmittance of 3-5 μm light was 98.7%, and the peak transmittance was 99.3%.

[0085] Example 5

[0086] The difference from Example 1 is that in step 4, the thicknesses of the optical film layers from the closest to the substrate are as follows: Si layer thickness 105nm, SiO layer thickness 38nm, Si layer thickness 415nm, SiO layer thickness 50nm, Si layer thickness 140nm, and SiO layer thickness 590nm.

[0087] The silicon window was tested using an infrared Fourier transform spectrometer. The average transmittance of 3-5 μm light was 78.8%, and the peak transmittance was 83.8%.

[0088] Example 6

[0089] The difference from Example 1 is that in step 4, the thicknesses of the optical film layers, starting from the substrate, are as follows: Si layer thickness 100nm, SiO layer thickness 29nm, Si layer thickness 50nm, SiO layer thickness 30nm, Si layer thickness 686nm, SiO layer thickness 100nm, Si layer thickness 620nm, and SiO layer thickness 535nm.

[0090] The silicon window was tested using an infrared Fourier transform spectrometer, and the average transmittance of 3-5 μm light was 98.9%, with a peak transmittance of 99.5%.

[0091] Example 7

[0092] The difference from Example 1 is that in step 4, the thicknesses of the optical film layers, starting from the substrate, are as follows: Si layer thickness 31nm, SiO layer thickness 20nm, Si layer thickness 383nm, SiO layer thickness 59nm, Si layer thickness 164nm, SiO layer thickness 329nm, Si layer thickness 34nm, SiO layer thickness 642nm, Si layer thickness 145nm, SiO layer thickness 83nm, Si layer thickness 300nm, and SiO layer thickness 529nm.

[0093] The silicon window was tested using an infrared Fourier transform spectrometer, and the average transmittance of 3-5 μm light was 99.3%, with a peak transmittance of 99.9%.

[0094] Example 8

[0095] In this embodiment, an infrared metallized antireflection film is prepared according to the following steps:

[0096] 1. The silicon substrate was ultrasonically cleaned for 10 minutes each with acetone solution, anhydrous ethanol and pure water, and then wiped clean with degreased cotton before being loaded onto the fixture.

[0097] 2. After placing the coating machine, vacuum it, set the baking temperature to 150℃, maintain the temperature for two hours, and start coating when the vacuum degree reaches 7*10-4Pa.

[0098] 3. Clean the substrate with an ion source for 10 minutes. During the deposition process, use an ion source to assist in deposition. The parameters are shown in the table below.

[0099] Table 3 Ion source parameters for cleaning substrates

[0100] cathode anode screen accelerate neutralization Beam 18A 80V 300V 200V 15A 150mA

[0101] Table 4 Ion source-assisted deposition parameters

[0102] cathode anode screen accelerate neutralization Beam 18A 80V 400V 200V 15A 200mA

[0103] 4. Si was deposited using electron gun evaporation at a deposition rate of 0.5 nm / s; SiO was deposited using resistance thermal evaporation at a deposition rate of 1.2 nm / s. Multiple dielectric films were formed by alternating deposition of Si and SiO layers on the central region of surface A and surface B of the substrate, respectively. Photoresist was applied to the edge region of surface A for protection using photolithography. The optical film thicknesses, from closest to the substrate, were as follows: Si layer 303 nm, SiO layer 47 nm, Si layer 172 nm, SiO layer 276 nm, Si layer 46 nm, SiO layer 607 nm, Si layer 129 nm, SiO layer 97 nm, Si layer 297 nm, and SiO layer 505 nm.

[0104] 5. After plating, do not cool down directly. Instead, use an annealing process, and keep the temperature constant at 150℃, 120℃, 90℃, and 60℃ for 15 minutes in sequence.

[0105] 6. After annealing, remove the lens and use acetone solution or photoresist remover to remove the photoresist in the edge area.

[0106] 7. Use a protective film or photoresist to protect the dielectric film in the center area of ​​the silicon window A side, clean the edge area, and attach it to the workpiece tray.

[0107] 8. Place it into a thermal evaporation coating machine or a magnetron sputtering coating machine to sequentially deposit a Cr film of 60nm, a Cu or Ni film of 110nm, and an Au film of 350nm.

[0108] 9. After the plating is completed, remove the protective film, or use acetone solution or photoresist remover to remove the photoresist.

[0109] The transmittance spectrum of the silicon window was tested using an infrared Fourier transform spectrometer, as shown in the figure below. Figure 2 As shown, the average transmittance of 3-5µm light is 98.9%, and the peak transmittance is 99.6%. The post-weld sealing performance meets the requirement of a leakage rate of less than 1*102. -9 m 3 / s requirement.

[0110] Comparative Example 1

[0111] The difference from Example 1 is that in step 4, the thicknesses of the optical film layers, starting from the substrate, are as follows: Si layer thickness 282nm, SiO layer thickness 107nm, Si layer thickness 164nm, and SiO layer thickness 558nm.

[0112] The silicon window was tested using an infrared Fourier transform spectrometer. The average transmittance of 3-5 μm light was 97.3%, and the peak transmittance was 99%.

[0113] From the above description, it can be seen that the embodiments of the present invention achieve the following technical effects: The antireflective coating material selected in this application is Si and SiO. The optical transparency region of Si is 1.1–9 μm with a refractive index of 3.4, while the transparency region of SiO is 0.4–9 μm with a refractive index of 1.82. The researchers of this application accidentally discovered during their research that alternating Si and SiO layers can significantly improve the infrared light transmittance of the antireflective coating on a silicon substrate. Furthermore, Si and SiO possess excellent optical and mechanical properties, high aggregation density, strong film compactness, and are not prone to cracking or delamination. They also lack hydrophobic bands in the 3–5 μm wavelength range. The SiO film layer, as the outermost layer, has high surface hardness. With prolonged contact with air, it slowly reacts with O2 to form a very thin SiO2 film, further increasing its hardness, thus eliminating the need for an additional protective layer. The low refractive index of SiO, when used as the outermost layer, also reduces surface reflectivity, further increasing infrared light transmittance. Using Si and SiO as antireflective membranes can save production costs compared to conventionally used materials such as Ge, ZnS, and YbF3, because Si and SiO are cheaper and more readily available.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An infrared antireflection film, wherein the infrared antireflection film is based on silicon, characterized in that, Antireflection films are deposited on both sides of the substrate. The film structure of each antireflection film is (HL)^S. Wherein, H represents the Si layer, L represents the SiO layer, S represents the number of cycles of the HL basic structure, and S is an integer between 3 and 6. The layer adjacent to the substrate is the Si layer, and the layer on the surface is the SiO layer. S is 5, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 280-320nm, SiO layer thickness 36-58nm, Si layer thickness 151-191nm, SiO layer thickness 255-297nm, Si layer thickness 35-57nm, SiO layer thickness 570-640nm, Si layer thickness 108-150nm, SiO layer thickness 86-108nm, Si layer thickness 276-318nm, SiO layer thickness 474-536nm; Alternatively, S is 3, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 112-152nm, SiO layer thickness 24-34nm, Si layer thickness 350-410nm, SiO layer thickness 44-64nm, Si layer thickness 142-182nm, SiO layer thickness 524-584nm. Alternatively, S is 4, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 80-120nm, SiO layer thickness 24-34nm, Si layer thickness 45-55nm, SiO layer thickness 25-35nm, Si layer thickness 656-716nm, SiO layer thickness 80-120nm, Si layer thickness 590-650nm, SiO layer thickness 504-564nm; Alternatively, S is 6, and the thicknesses of each film layer from the substrate are as follows: Si layer thickness 26-36nm, SiO layer thickness 15-25nm, Si layer thickness 353-413nm, SiO layer thickness 54-64nm, Si layer thickness 154-174nm, SiO layer thickness 309-349nm, Si layer thickness 29-39nm, SiO layer thickness 612-672nm, Si layer thickness 135-155nm, SiO layer thickness 78-88nm, Si layer thickness 280-320nm, and SiO layer thickness 500-560nm.

2. An infrared metallized antireflective film, comprising a substrate and antireflective films respectively disposed on two surfaces of the substrate, characterized in that, One of the antireflective coatings on one surface has a metal film at its outer edge; the antireflective coating is the antireflective coating according to claim 1; The metal film includes a connecting layer, a barrier layer and a welding layer arranged sequentially, with the connecting layer disposed on the surface of the substrate.

3. The infrared metallized antireflective film according to claim 2, characterized in that, The width of the metal film is ≥0.2mm; The connecting layer is either Cr or Ti, and the thickness of the connecting layer is 50-70 nm. The barrier layer is either metal Cu or metal Ni, and the thickness of the barrier layer is 100-120 nm. The welding layer is either Au or Ni, and the thickness of the welding layer is 300-500 nm.

4. A method for preparing an infrared antireflective film as described in claim 1, characterized in that, include: Step S1: After cleaning the silicon substrate, place it in the coating machine, apply vacuum, and bake for a period of time. Step S2: The substrate is cleaned with an ion source, and with the assistance of the ion source, Si layers and SiO layers are alternately deposited on both sides of the substrate layer by layer. Step S3: After the Si layer and SiO layer are deposited, they are directly annealed to obtain the infrared antireflection film.

5. The preparation method according to claim 4, characterized in that, In step S1, the baking temperature is 150-250℃ and the time is 1-2 hours. And / or, in step S2, the Si layer is deposited by electron beam evaporation at a deposition rate of 0.2-0.5 nm / s; And / or, in step S2, the SiO layer is deposited by resistance thermal evaporation, with a deposition rate of 1-1.5 nm / s.

6. The preparation method according to claim 4, characterized in that, The annealing process includes: maintaining a constant temperature of 155-145℃, 125-115℃, 95-85℃ and 65-55℃ for 10-20 minutes in sequence.

7. The preparation method according to claim 6, characterized in that, The annealing process includes: holding the temperature at 150℃, 120℃, 90℃, and 60℃ for 15 minutes in sequence.

8. A method for preparing an infrared metallized antireflective film as described in claim 2 or 3, characterized in that, include: Step S1: After cleaning the substrate, a protective layer is set on the outer edge of one of the surfaces of the substrate. After placing it in the coating machine, a vacuum is drawn and the substrate is baked for a period of time. Step S2: The substrate is cleaned with an ion source, and an antireflection film is deposited on both sides of the substrate with the assistance of the ion source. After the film is deposited, an annealing treatment is performed to remove the protective layer on the outer edge, and a metal film to be deposited is obtained. Step S3: A protective layer is set on the antireflective film in the central area of ​​the surface where the metal film to be deposited is located, and a connecting layer, a barrier layer and a welding layer are sequentially deposited on the edge of the metal film to be deposited. Step S4: Remove the protective layer to obtain the infrared metallized antireflection film.

9. The application of the infrared antireflection film according to claim 1 in a light-transmitting device in the 3-5μm wavelength band.

10. The application of the infrared metallized antireflective film according to claim 2 or 3 in a light-transmitting device in the 3-5μm wavelength band.

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