A broadband ultra-low reflection film and a preparation method thereof

Abstract

The application provides a broadband ultra-low anti-reflection film and a preparation method thereof, and relates to the technical field of optical thin films, and comprises the following steps: S1, placing a substrate into a vacuum chamber, vacuumizing the vacuum chamber, baking the substrate when the vacuum degree is 1*10 ‑1 ~5*10 ‑2 Pa, the baking temperature is 220~300 DEG C, and the baking time is not less than 1 hour; S2, pre-cleaning the substrate by using an ion source when the vacuum degree reaches 6*10 ‑4 ~9*10 ‑4 Pa; S3, pre-melting SiO2 film material and Ti3O5 film material to an evaporation state before opening a baffle, and alternately coating the substrate pre-cleaned by using the SiO2 film material and the Ti3O5 film material after opening the baffle; S4, pre-melting MgF2 film material and the last layer of SiO2 film material to an evaporation state before opening the baffle, coating the MgF2 film material on the previous layer of material after opening the baffle, and then coating the SiO2 film material, so that the broadband ultra-low anti-reflection film is obtained.

Description

Technical Field

[0001] This application relates to the field of optical thin film technology, specifically to a broadband ultra-low anti-reflection film and its preparation method. Background Technology

[0002] With the rapid development of modern science and technology, the requirements for antireflective films are becoming increasingly stringent, and their application range is expanding. However, this also places increasingly higher demands on the bandwidth, spectral performance, and mechanical properties of antireflective films. Therefore, it is of great significance to improve the fabrication process of antireflective films in order to provide optical films with superior performance. Summary of the Invention

[0003] In view of this, the embodiments of this specification provide a broadband ultra-low antireflection film and its preparation method, which improves the bandwidth range and mechanical properties of the ultra-low antireflection film, makes the film more resistant to friction and increases its hardness, and overcomes the problems of film peeling and spectral changes caused by boiling in water.

[0004] The embodiments in this specification provide the following technical solutions:

[0005] One embodiment of this specification provides a method for preparing a broadband ultra-low anti-reflection film, comprising:

[0006] S1. Place the substrate in the vacuum chamber and evacuate the chamber until the vacuum level is 1×10⁻⁶. -1 ~5×10 -2 When Pa is applied, the substrate is baked at a temperature of 220-300°C for a time of not less than 1 hour.

[0007] S2, When the vacuum degree reaches 6×10 -4 ~9×10 -4 At Pa, the substrate is pre-cleaned using an ion source;

[0008] S3. Before opening the baffle, pre-melt the SiO2 film material and Ti3O5 film material to the evaporation state. After opening the baffle, alternately deposit SiO2 film material and Ti3O5 film material on the pre-cleaned substrate.

[0009] S4. Before opening the baffle, pre-melt the MgF2 film and the last layer of SiO2 film to the evaporation state. After opening the baffle, deposit the MgF2 film on the front layer material, and then deposit the SiO2 film to prepare a broadband ultra-low anti-reflection film.

[0010] In some embodiments, in step S2, the pre-cleaning conditions are as follows: Beam voltage 600-800V, current 500-800mA, ACC voltage 400-800V, neutralization current 7.5-12A, argon charge 5-20Sccm, oxygen charge 30-70Sccm, and cleaning time 300-600S.

[0011] In some embodiments, the process of pre-melting the SiO2 film material in step S3 includes:

[0012] The electron gun beam current was gradually increased from 0 to 200-260 mA, with a rise time of 10-20 seconds and a hold time of 10-20 seconds;

[0013] The electron gun beam current is gradually reduced from 200-260 mA to 130-150 mA over a period of 10-20 seconds, and held for 5-10 seconds to form vapor molecules. The vapor evaporation rate is set to 2-2.5 A / s.

[0014] In some embodiments, step S3, the process of depositing a film using SiO2 film material after opening the baffle, includes:

[0015] After pre-melting, open the baffle to allow vapor molecules to adhere to the front material. The evaporation rate of the vapor molecules is set to 4-6 A / S.

[0016] The pre-layer material with attached vapor molecules is baked at a temperature of 220–300°C, and a radio frequency source is used to assist in the coating process. The beam voltage is set to 900–1150V, the beam current to 750–950mA, the ACC voltage to 400–600V, the neutralizing electrode current to 8–16A, the argon charge to 5–15Sccm, and the oxygen charge to 40–70Sccm.

[0017] In some embodiments, the pre-melting process of the Ti3O5 film material in step S3 includes:

[0018] The electron gun beam current was gradually increased from 0 to 200-300 mA, with a rise time of 10-20 seconds and a hold time of 10-20 seconds;

[0019] The electron gun beam current was gradually increased from 200-300 mA to 350-500 mA, with a rise time of 10-20 seconds and a hold time of 10-20 seconds.

[0020] The electron gun beam current is gradually reduced from 350-500 mA to 320-450 mA over a period of 10-20 seconds, and held for 5-10 seconds to form vapor molecules. The evaporation rate of the vapor molecules is set to 1.5-2 A / s.

[0021] In some embodiments, step S3, the process of depositing a film using Ti3O5 film material after opening the baffle, includes:

[0022] After pre-melting, open the baffle to allow vapor molecules to adhere to the front material. The evaporation rate of the vapor molecules is set to 3-4 A / S.

[0023] The substrate material with attached vapor molecules is baked at a temperature of 220–300°C, and a radio frequency source is used to assist in the coating process. The beam voltage is set to 1000–1200V, the beam current to 900–1100mA, the ACC voltage to 600–800V, the neutralizing electrode current to 12–18A, the argon charge to 5–20 Sccm, and the oxygen charge to 40–70 Sccm.

[0024] In some embodiments, the pre-melting and coating process of the MgF2 film material in step S4 includes:

[0025] The electron gun beam current was gradually increased from 0 to 20-40 mA, with a rise time of 20 seconds and a hold time of 20 seconds.

[0026] The electron gun beam was gradually reduced from 20-40 mA to 10-20 mA over a period of 5 seconds, and held for 20 seconds to form vapor molecules.

[0027] After pre-melting, open the baffle to allow vapor molecules to adhere to the front layer material. The vapor evaporation rate is set to 4-5 A / S. After coating, maintain the vacuum for 15-25 minutes, then release the vacuum chamber and remove the coated lens for testing.

[0028] In some embodiments, the SiO2 film deposition process in step S4 includes:

[0029] An ultra-thin layer is formed by depositing SiO2 film on top of MgF2 film material, with the thickness controlled between 3nm and 5nm.

[0030] In some embodiments, the thickness of different coating layers is monitored by different crystal oscillators during coating.

[0031] On the other hand, a broadband ultra-low anti-reflection film is provided, which is prepared by the method for preparing a broadband ultra-low anti-reflection film according to any of the above embodiments.

[0032] Compared with the prior art, the beneficial effects that can be achieved by the above-mentioned at least one technical solution adopted in the embodiments of this specification include at least the following: by optimizing the film structure design of the ultra-low anti-reflection film, analyzing the errors introduced by various factors in the coating process, the preparation method of combining thin and thick film layers is made controllable, and an extremely thin layer of SiO2 is added to the outermost layer on the basis of MgF2 material, which greatly improves the bandwidth range and mechanical properties of the ultra-low anti-reflection film, makes the film more resistant to friction and improves hardness, and overcomes the problems of film peeling and spectral changes caused by boiling in water. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is an exemplary film system structure diagram of the broadband ultra-low anti-reflection film provided in the embodiments of this application;

[0035] Figure 2 This is an exemplary design spectral curve of the broadband ultra-low antireflection film provided in the embodiments of this application;

[0036] Figure 3 Here is an exemplary actual spectral curve of the broadband ultra-low antireflection film provided in the embodiments of this application;

[0037] Figure 4 This is an exemplary comparison of the spectral curves of the broadband ultra-low anti-reflection film provided in this application embodiment before and after boiling. Detailed Implementation

[0038] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0039] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0041] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The drawings only show the components related to this application and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0042] Through in-depth research and improvement, the inventors discovered:

[0043] The design and fabrication of ultra-low reflectivity anti-reflective coatings using all-dielectric methods can be achieved using three materials: Ti3O5, SiO2, and an outermost layer of MgF2. However, due to differences in materials and coating processes, the reflectivity of ultra-low reflectivity anti-reflective coatings prepared by traditional methods is still relatively high. Furthermore, anti-reflective coatings using MgF2 as the outermost layer are more prone to delamination after boiling in water compared to anti-reflective coatings prepared without MgF2. They also exhibit poor hardness and abrasion resistance, and perform poorly in environmental tests under high temperature and humidity, alternating hot and cold, and acidic and alkaline conditions.

[0044] This application uses film system design software to design the film system structure of an ultra-low antireflection film (exemplarily shown in Figure 1). Based on the three materials Ti3O5, SiO2, and MgF2, the coating process and film system structure are optimized. For example, using 550nm as the reference wavelength, the film system structure that can be used is: G|1.8L0.2H0.3L1.1H0.15L0.5H1.1L0.1H0.6L1.1H0.1L0.6H0.9M|A, where G is the substrate (the substrate material can be glass substrates such as K9, JGS1, B270, BF33, or optical crystals and various optical plastic substrates), H is Ti3O5 material, L is SiO2 material, M is MgF2 material, and A is air medium. After optimization, an ideal spectral curve can be obtained (exemplarily shown in Figure 1). Figure 2 , 3(As shown in Figure 4). More preferably, the thickness of the outermost MgF2 layer can be finely adjusted, and an ultra-thin layer of SiO2 can be added as a protective layer to further improve the wear resistance, hardness and other mechanical properties of the ultra-low antireflection film.

[0045] Considering the uneven thickness distribution of the film layers during the preparation process, it is necessary to perform error analysis on each designed film layer separately to control the film thickness more efficiently and achieve mass production of ultra-low anti-reflection films. This application adopts a crystal control method using crystal control wafers (such as quartz crystal control), with different crystal control wafers monitoring the thickness of different materials, improving the accuracy of the crystal oscillator in monitoring the film thickness. In addition, through actual coating results, the remaining evaporation amount after the baffle is closed, as well as the evaporation amount from the initial coating when the baffle is open to the stable rate, can be calculated, deriving the material tooling values ​​for different substrates and thicknesses, thereby reducing the film thickness error, stabilizing the film thickness control, and making the mass production of ultra-low anti-reflection films possible. Finally, by adjusting the process of the outer MgF2 layer, the mechanical properties of the film are improved, enabling it to complete water boiling verification, hardness, abrasion resistance tests, and solving the film removal problem. Taking the K9 substrate as an example, the spectrum of the test sample for preparing the ultra-low antireflection film showed an average reflectance of 0.0496% in the 400–700 nm wavelength range; the maximum reflectance in the 400–700 nm wavelength range was 0.14%; the hardness test was 4H strength; the film surface was continuously torn 10 times with 3M tape without any film peeling; and the film did not peel off after being boiled in 90°C water for 2 hours.

[0046] In a preferred embodiment, physical vapor deposition and electron beam evaporation are used to monitor the coating thickness of ultra-low antireflection films, which are extremely thin and have a small number of layers. The relationship between the quartz crystal frequency change Δf and the deposited film thickness Δdm is as follows:

[0047]

[0048] Where N = 1670 Hz·mm, is called the frequency constant of the crystal, ρ m ρ is the density of the film layer. Q The density of quartz crystals (2.65 × 10³ kg / m³) 3 Because the ultra-low antireflection coating is relatively thin, its natural frequency does not change significantly, thus allowing us to approximate... If we consider it as a constant, the frequency change Δf of the quartz crystal and the thickness Δdm of the deposited film can be approximately considered to have a linear relationship.

[0049] Analyzing the experimental data using the above formula, after the coating process was completed and the baffle was closed, the average residual evaporation amounts of Ti3O5 and SiO2 materials corresponding to the change in crystal control frequency were 4.4 nm and 6.1 nm, respectively. Furthermore, due to the effect of the ion source and positional differences, the actual average residual deposition thicknesses were approximately 2.5 nm and 4.1 nm, respectively. For films with uniform thickness distribution, residual evaporation introduces a fixed percentage error. However, for ultra-low reflective coatings, which have significant thickness variations, the error introduced by residual evaporation must be considered in relation to the specific thickness value. Moreover, after the baffle was opened and coating began, the material deposition rate on the substrate surface gradually stabilized with increasing thickness. During this stabilization process, the deposition amount of the film thickness can be approximated as a fixed value. This fixed value is not a constant relative to the ratio of different thicknesses; calculating based on a fixed ratio introduces an error. Finally, for ultra-low antireflection coating systems, using multiple crystal oscillators to monitor the film thickness is more accurate than using only one. As the fundamental frequency decreases, the stability of the quartz oscillator deteriorates, leading to frequency hopping. Since the surface environment of the crystal oscillator is not entirely consistent with the substrate surface environment, the adhesion of different materials deposited on the crystal oscillator surface also varies. In this invention, different crystal oscillators are set for different film layers (e.g., three crystal oscillators for Ti3O5, SiO2, and MgF2 material layers). Each crystal oscillator monitors only the film thickness of one material, avoiding tooling errors introduced by different substrates, and more accurately calculating the actual deposition thickness, ensuring a more precise film thickness. In actual coating, the tooling value can be set accordingly by considering multiple factors such as differences in thickness (residual amount, initial amount), differences in processes, and differences in substrates to obtain a more accurate film thickness tooling and reduce debugging difficulty.

[0050] In a preferred embodiment, the structure of the broadband ultra-low antireflection film system prepared in this application and the thickness controlled thereto are as follows:

[0051] The first layer is SiO2, with a thickness of 172.65 nm;

[0052] The second layer is a thin layer of Ti3O5 with a thickness of 14.95 nm;

[0053] The third layer is SiO2, with a thickness of 30.41 nm;

[0054] The fourth layer is Ti3O5, with a thickness of 68.96 nm;

[0055] The fifth layer is a thin layer of SiO2 with a thickness of 13.19 nm;

[0056] The sixth layer is Ti3O5 with a thickness of 29.85 nm;

[0057] The seventh layer is SiO2, with a thickness of 102.72 nm;

[0058] The eighth layer is a thin Ti3O5 layer with a thickness of 8.69 nm;

[0059] The ninth layer is SiO2, with a thickness of 56.06 nm;

[0060] The tenth layer is Ti3O5 with a thickness of 67.26 nm;

[0061] The eleventh layer is a thin layer of SiO2 with a thickness of 8 nm;

[0062] The twelfth layer is Ti3O5 with a thickness of 39.33 nm;

[0063] The thirteenth layer is MgF2, with a thickness of 86.77 nm;

[0064] The fourteenth layer is a protective layer of SiO2, with a thickness of 4nm.

[0065] In summary, this application utilizes electron beam evaporation to prepare ultra-low antireflection films, increasing the bandwidth to 400-700 nm within the conventional 420-680 nm spectral range while maintaining a Rave < 0.1%. By analyzing the errors introduced by various factors during the coating process, the preparation method of combining thin and thick film layers is made controllable. The outermost layer is an additional layer of extremely thin SiO2 on top of the MgF2 material, which greatly improves the bandwidth range and the mechanical properties of the ultra-low antireflection film, making the film more resistant to friction and increasing its hardness. At the same time, it overcomes the problems of film detachment and spectral changes caused by boiling in water.

[0066] The following examples further illustrate the broadband ultra-low anti-reflection film and its preparation method provided in this application.

[0067] Example 1

[0068] S1. Place the substrate in the vacuum chamber and evacuate the chamber until the vacuum level is 1×10⁻⁶. -1 When Pa is applied, the substrate is baked at a temperature of 220°C for 1 hour.

[0069] S2, When the vacuum degree reaches 6×10 -4 At Pa, the substrate is pre-cleaned using an ion source; including:

[0070] Set the Beam voltage to 600V, current to 500mA, ACC voltage to 400V, neutralization current to 7.5A, argon gas filling volume to 5Sccm, and oxygen gas filling volume to 30Sccm for pre-cleaning of the substrate for 300 seconds.

[0071] S3. The dielectric material is pre-melted to form vapor molecules, and the vapor molecules are used to alternately coat the cleaned substrate to prepare an ultra-low anti-reflection film.

[0072] The pre-melting process for the high-refractive-index material Ti3O5 is as follows:

[0073] ① The electron gun beam current is gradually increased from 0 to 200 mA, with a rise time of 10 seconds and a hold time of 10 seconds; ② The electron gun beam current is gradually increased from 200 mA to 350 mA, with a rise time of 10 seconds and a hold time of 10 seconds; ③ The electron gun beam current is gradually decreased from 350 mA to 320 mA, with a decrease time of 10 seconds and a hold time of 5 seconds to form vapor molecules.

[0074] After pre-melting, the baffle is opened to allow vapor molecules to adhere to the substrate material. The vapor evaporation rate is set to 3A / S. The substrate material with attached vapor molecules is baked at 220℃, and an RF source is used to assist in coating. The Beam voltage is set to 1000V, the Beam current to 900mA, the ACC voltage to 600V, the neutralizing current to 12A, the argon charge to 5Sccm, and the oxygen charge to 40Sccm.

[0075] The pre-melting and ion source parameters of the thin-layer Ti3O5 are the same as those mentioned above, but the evaporation rate of vapor molecules is set to 1.5 A / S.

[0076] The process of pre-melting low-refractive-index SiO2 is as follows:

[0077] ① The electron gun beam current gradually increases from 0 to 200 mA, with a rise time of 10 seconds and a hold time of 10 seconds; ② The electron gun beam current gradually decreases from 200 mA to 130 mA, with a decrease time of 10 seconds and a hold time of 5 seconds to form vapor molecules.

[0078] After pre-melting, the baffle is opened to allow vapor molecules to adhere to the substrate material. The vapor evaporation rate is set to 4A / S. The substrate material with attached vapor molecules is baked at 220℃. Radio frequency source is used to assist in coating. The beam voltage is set to 900V, the beam current to 750mA, the ACC voltage to 400V, the neutral electrode current to 8A, the argon charge to 5Sccm, and the oxygen charge to 40Sccm.

[0079] The parameters for pre-melting thin-layer SiO2 and the ion source are the same as those mentioned above, but the evaporation rate of vapor molecules is set to 2A / S.

[0080] Example 2

[0081] S1. Place the substrate in the vacuum chamber and evacuate the chamber until the vacuum level is 3×10⁻⁶. -2When Pa is applied, the substrate is baked at a temperature of 260°C for 1.6 hours.

[0082] S2, When the vacuum degree reaches 8×10 -4 At Pa, the substrate is pre-cleaned using an ion source; including:

[0083] Set the Beam voltage to 700V, current to 640mA, ACC voltage to 600V, neutralization current to 9.8A, argon charge to 12Sccm, and oxygen charge to 50Sccm for pre-cleaning the substrate. The cleaning time is 450S.

[0084] S3. The dielectric material is pre-melted to form vapor molecules, and the vapor molecules are used to alternately coat the cleaned substrate.

[0085] The pre-melting process for the high-refractive-index material Ti3O5 is as follows:

[0086] ① The electron gun beam current gradually increases from 0 to 260 mA, with a rise time of 15 seconds and a hold time of 15 seconds; ② The electron gun beam current gradually increases from 150 mA to 420 mA, with a rise time of 15 seconds and a hold time of 15 seconds; ③ The electron gun beam current gradually decreases from 410 mA to 380 mA, with a decrease time of 16 seconds and a hold time of 8 seconds to form vapor molecules.

[0087] After pre-melting, the baffle is opened to allow vapor molecules to adhere to the substrate material. The vapor evaporation rate is set to 4A / S. The substrate material with attached vapor molecules is baked at 260℃, and an RF source is used to assist in coating. The Beam voltage is set to 1100V, the Beam current to 1000mA, the ACC voltage to 700V, the neutralizing current to 15A, the argon charge to 13Sccm, and the oxygen charge to 55Sccm.

[0088] The pre-melting and ion source parameters of the thin-layer Ti3O5 are the same as those mentioned above, but the evaporation rate of vapor molecules is set to 1.8 A / S.

[0089] The process of pre-melting low-refractive-index SiO2 is as follows:

[0090] ① The electron gun beam current gradually increases from 0 to 240 mA, with a rise time of 15 seconds and a hold time of 15 seconds; ② The electron gun beam current gradually decreases from 230 mA to 140 mA, with a decrease time of 15 seconds and a hold time of 7 seconds to form vapor molecules.

[0091] After pre-melting, the baffle is opened to allow vapor molecules to adhere to the substrate material. The vapor evaporation rate is set to 5A / S. The substrate material with attached vapor molecules is baked at 260℃, and an RF source is used to assist in coating. The beam voltage is set to 1000V, the beam current to 800mA, the ACC voltage to 500V, the neutralizing current to 12A, the argon charge to 10Sccm, and the oxygen charge to 55Sccm.

[0092] The parameters for pre-melting thin-layer SiO2 and the ion source are the same as those mentioned above, but the evaporation rate of vapor molecules is set to 2.2 A / S.

[0093] S4. Before opening the baffle, pre-melt the MgF2 film and the last layer of SiO2 film to the evaporation state. After opening the baffle, deposit the MgF2 film on the front layer material, and then deposit the SiO2 film to prepare a broadband ultra-low anti-reflection film.

[0094] Specifically, the material process was changed during the preparation of the outermost MgF2 film to make the MgF2 film denser and improve its mechanical properties. This was mainly achieved through two aspects: increasing the baking temperature and changing the ion source parameters.

[0095] The pre-melting process of MgF2 material is as follows:

[0096] ① The electron gun beam current gradually increases from 0 to 20 mA, with a rise time of 20 seconds and a hold time of 20 seconds; ② The electron gun beam current gradually decreases from 20 mA to 10 mA, with a decrease time of 5 seconds and a hold time of 20 seconds to form vapor molecules.

[0097] After pre-melting, the baffle is opened to allow vapor molecules to adhere to the substrate material. The vapor evaporation rate is set to 4 A / s. After coating, an ultra-low anti-reflection film is obtained. After maintaining the vacuum for 15 minutes, the vacuum chamber is vented, and the lens is removed for testing.

[0098] Based on the above process, an extremely thin layer of SiO2 is deposited after the outermost MgF2 layer, with the thickness controlled at 3nm. This can improve the mechanical properties of the film, and the resistance to boiling water and friction are also improved. In addition, adding SiO2 will cause spectral changes, so the thickness of the outermost MgF2 layer is finely adjusted.

[0099] Example 3

[0100] S1. Place the substrate in the vacuum chamber and evacuate the chamber until the vacuum level is 5 × 10⁻⁶. -2 When Pa is applied, the substrate is baked at 300℃ for 2 hours.

[0101] S2, When the vacuum degree reaches 9×10 -4 At Pa, the substrate is pre-cleaned using an ion source; including:

[0102] Set the Beam voltage to 800V, current to 800mA, ACC voltage to 800V, neutralization current to 12A, argon gas filling volume to 20Sccm, and oxygen gas filling volume to 70Sccm for pre-cleaning the substrate for 600 seconds.

[0103] S3. The dielectric material is pre-melted to form vapor molecules, and the vapor molecules are used to alternately coat the cleaned substrate.

[0104] The pre-melting process for the high-refractive-index material Ti3O5 is as follows:

[0105] ① The electron gun beam current is gradually increased from 0 to 300 mA, with a rise time of 20 seconds and a hold time of 20 seconds; ② The electron gun beam current is gradually increased from 300 mA to 500 mA, with a rise time of 20 seconds and a hold time of 20 seconds; ③ The electron gun beam current is gradually decreased from 500 mA to 450 mA, with a decrease time of 20 seconds and a hold time of 10 seconds to form vapor molecules.

[0106] After pre-melting, the baffle is opened to allow vapor molecules to adhere to the substrate material. The vapor evaporation rate is set to 4A / S. The substrate material with attached vapor molecules is baked at 300℃, and a radio frequency source is used to assist in the coating process. The beam voltage is set to 1200V, the beam current to 1100mA, the ACC voltage to 800V, the neutralizing current to 18A, the argon charge to 20Sccm, and the oxygen charge to 70Sccm.

[0107] The pre-melting and ion source parameters of the thin-layer Ti3O5 are the same as those mentioned above, but the evaporation rate of vapor molecules is set to 1.5–2 A / s.

[0108] The process of pre-melting low-refractive-index SiO2 is as follows:

[0109] ① The electron gun beam current gradually increases from 0 to 260 mA, with a rise time of 20 seconds and a hold time of 20 seconds; ② The electron gun beam current gradually decreases from 260 mA to 150 mA, with a decrease time of 20 seconds and a hold time of 10 seconds to form vapor molecules.

[0110] After pre-melting, the baffle is opened to allow vapor molecules to adhere to the substrate material. The vapor evaporation rate is set to 6A / S. The substrate material with attached vapor molecules is baked at 300℃, and a radio frequency source is used to assist in coating. The beam voltage is set to 1150V, the beam current to 950mA, the ACC voltage to 600V, the neutralizing current to 16A, the argon charge to 15Sccm, and the oxygen charge to 70Sccm.

[0111] The parameters for pre-melting thin-layer SiO2 and the ion source are the same as those mentioned above, but the evaporation rate of vapor molecules is set to 2.5 A / S.

[0112] S4. Before opening the baffle, pre-melt the MgF2 film and the last layer of SiO2 film to an evaporation state. After opening the baffle, deposit the MgF2 film on the previous layer material, and then deposit the SiO2 film to prepare a broadband ultra-low anti-reflection film. Similarly, when preparing the outermost MgF2 film, change the material process to make the MgF2 film more dense and improve its mechanical properties. This is mainly done in two ways: increasing the baking temperature and changing the ion source parameters.

[0113] Specifically, the pre-melting process of MgF2 material is as follows:

[0114] ① The electron gun beam current is gradually increased from 0 to 40 mA, with a rise time of 20 seconds and a hold time of 20 seconds; ② The electron gun beam current is gradually decreased from 40 mA to 20 mA, with a decrease time of 5 seconds and a hold time of 20 seconds to form vapor molecules.

[0115] After pre-melting, the baffle is opened to allow vapor molecules to adhere to the substrate material. The vapor evaporation rate is set to 5 A / s. After coating, an ultra-low anti-reflection film is obtained. After maintaining a vacuum for 25 minutes, the vacuum chamber is vented, and the lens is removed for testing.

[0116] Based on the above process, an extremely thin layer of SiO2 is deposited after the outermost MgF2 layer, with the thickness controlled at 5nm. This can improve the mechanical properties of the film, and the resistance to boiling water and friction are also improved. In addition, adding SiO2 will cause spectral changes, so the thickness of the outermost MgF2 layer is finely adjusted.

[0117] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for the product embodiments described later, since they correspond to the methods, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions in the system embodiments.

[0118] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0119] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although various examples have been discussed in the foregoing disclosure of some embodiments of the invention that are currently considered useful, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the spirit and scope of the embodiments described herein. For example, while the system components described above can be implemented by hardware devices, they can also be implemented solely by software solutions, such as installing the described system on existing processing devices or mobile devices.

[0120] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this specification. Such modifications, improvements, and corrections are suggested in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

Claims

1. A method for producing a broadband ultra-low reflection film, characterized by, Comprise: S1, put the substrate into the vacuum chamber, vacuumize the vacuum chamber, when the vacuum degree is 1x10 -1 ~5x10 -2 Pa, bake the substrate, the baking temperature is 220~300℃, and the baking time is not less than 1 hour; S2, when the vacuum degree reaches 6x10 -4 ~9x10 -4 Pa, the substrate is pre-cleaned by using an ion source; S3, open the shutter before the SiO2 film material and Ti3O5 film material pre-melt to evaporation state, open shutter after the pre-cleaning on the substrate using SiO2 film material and Ti3O5 film material alternately plated film; S4, open the shutter before the MgF2 film material and the last layer of SiO2 film material pre-melt to evaporation state, open shutter after the front layer material MgF2 film material plating, then plated SiO2 film material, preparation obtained broadband ultra-low anti-reflective film; In S4 step, MgF2 film material pre-melt and plating process, comprising: The electron gun beam current from 0 gradually increased to 20-40 mA, the rising time is 20 seconds, the holding time is 20 seconds; The electron gun beam current from 20-40 mA gradually reduced to 10-20 mA, the reducing time is 5 seconds, the holding time is 20 seconds to form vapor molecules; Pre-melt after opening shutter, let the vapor molecules adhere to the front layer material, the evaporation rate of vapor molecules is set to 4-5 A / S, after plating film, vacuum keeping 15-25 minutes, then the vacuum chamber is discharged, take out the plating film lens for testing; In S4 step, the plating process of SiO2 film material, comprising: In addition to the MgF2 film material plated SiO2 film material to form a very thin layer, thickness control in 3-5 nm; The structure of the broadband ultra-low anti-reflective film is: The first layer is SiO2, the thickness is 172.65 nm; The second layer is thin layer Ti3O5, the thickness is 14.95 nm; The third layer is SiO2, the thickness is 30.41 nm; The fourth layer is Ti3O5, the thickness is 68.96 nm; The fifth layer is thin layer SiO2, the thickness is 13.19 nm; The sixth layer is Ti3O5, the thickness is 29.85 nm; The seventh layer is SiO2, the thickness is 102.72 nm; The eighth layer is thin layer Ti3O5, the thickness is 8.69 nm; The ninth layer is SiO2, the thickness is 56.06 nm; The tenth layer is Ti3O5, the thickness is 67.26 nm; The eleventh layer is thin layer SiO2, the thickness is 8 nm; The twelfth layer is Ti3O5, the thickness is 39.33 nm; The thirteenth layer is MgF2, the thickness is 86.77 nm; 2. The production method according to claim 1, characterized by, The fourteenth layer is protective layer SiO2, the thickness is 4 nm.

3. The preparation method according to claim 1, characterized in that, In S2 step, the pre-cleaning conditions are: set Beam voltage 600-800 V, current 500-800 mA, ACC voltage 400-800 V, neutral current 7.5-12 A, argon filling amount 5-20 Sccm, oxygen filling amount 30-70 Sccm, cleaning time 300-600 S. In S3 step, the process of pre-melting SiO2 film material, comprising: The electron gun beam current from 0 gradually increased to 200-260 mA, the rising time is 10-20 seconds, the holding time is 10-20 seconds; The electron gun beam current from 200-260 mA gradually reduced to 130-150 mA, the reducing time is 10-20 seconds, the holding time is 5-10 seconds to form vapor molecules, the evaporation rate of vapor molecules is set to 2-2.5 A / S.

4. The production method according to claim 3, characterized by, In the S3 step, the process of coating with the SiO2 film material after opening the shutter includes: After the pre-melting is completed, the shutter is opened, and the vapor molecules are attached to the previous layer of material, and the evaporation rate of the vapor molecules is set to 4-6 A / S; The previous layer of material with the attached vapor molecules is baked at a temperature of 220-300°C, and the coating is assisted by the radio frequency source, with the Beam voltage set to 900-1150 V, the Beam current set to 750-950 mA, the ACC voltage set to 400-600 V, the neutralizing electrode current set to 8-16 A, the argon gas amount set to 5-15 Sccm, and the oxygen gas amount set to 40-70 Sccm.

5. The preparation method according to claim 1, characterized in that, In the S3 step, the process of pre-melting the Ti3O5 film material includes: The electron gun beam current is gradually increased from 0 to 200-300 mA, with the rising time being 10-20 seconds and the holding time being 10-20 seconds; The electron gun beam current is gradually increased from 200-300 mA to 350-500 mA, with the rising time being 10-20 seconds and the holding time being 10-20 seconds; The electron gun beam current is gradually decreased from 350-500 mA to 320-450 mA, with the decreasing time being 10-20 seconds and the holding time being 5-10 seconds to form the vapor molecules, and the evaporation rate of the vapor molecules is set to 1.5-2 A / S.

6. The production method according to claim 5, wherein In the S3 step, the process of coating with the Ti3O5 film material after opening the shutter includes: After the pre-melting is completed, the shutter is opened, and the vapor molecules are attached to the previous layer of material, and the evaporation rate of the vapor molecules is set to 3-4 A / S; The substrate material with the attached vapor molecules is baked at a temperature of 220-300°C, and the coating is assisted by the radio frequency source, with the Beam voltage set to 1000-1200 V, the Beam current set to 900-1100 mA, the ACC voltage set to 600-800 V, the neutralizing electrode current set to 12-18 A, the argon gas amount set to 5-20 Sccm, and the oxygen gas amount set to 40-70 Sccm.

7. The production method according to any one of claims 1 to 6, characterized by, The thickness of different coating layers during the coating is monitored by different crystal oscillator chips.

8. A broadband, ultra-low reflectance film, characterized in that, Prepared by the method according to any one of claims 1 to 7. Prepared by the method according to any one of claims 1 to 7.

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