Deep ultraviolet special-shaped quartz element antireflection film and preparation method thereof
By depositing MgF2 and interlaced Al2O3/SiO2 thin film layers on irregularly shaped quartz substrates, the problems of low hardness, high processing difficulty, and low light absorption rate of deep ultraviolet irregularly shaped quartz elements are solved, achieving efficient anti-reflection effect and cost reduction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-02
- Publication Date
- 2026-04-07
AI Technical Summary
Existing deep ultraviolet irregular quartz element antireflection coating technology suffers from low hardness, high processing difficulty, high cost, and low light absorption rate, making it difficult to meet the needs of high-precision optical systems.
Using a fused silica substrate, an antireflective film is formed by depositing first and second MgF2 thin film layers and interleaved Al2O3 and SiO2 thin film layers. The low light absorption characteristics of MgF2 and the stress characteristics of the two materials are utilized to enhance the adhesion between the film and the substrate, adapting to the complex surface of irregularly shaped substrates.
It effectively solves the problem of light absorption at 193nm wavelength in irregularly shaped quartz substrates, improves the transmittance, reduces light loss, reduces the risk of film cracking and peeling, and lowers costs.
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Figure CN121806167A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical thin film technology, and in particular to an antireflective film for deep ultraviolet irregularly shaped quartz elements and its preparation method. Background Technology
[0002] With the development of high-precision optical systems in fields such as lithography machines, deep ultraviolet lasers, and aerospace, the demand for irregularly shaped optical components is increasing. Traditional spherical optical components have limitations in correcting aberrations and cannot meet the complex design requirements of modern lithography technology. In the high-energy-density laser transmission and processing, deep ultraviolet lasers require irregularly shaped optical components to optimize the beam path and improve the accuracy and quality of laser processing.
[0003] However, existing antireflective coating technologies for irregularly shaped quartz elements in the deep ultraviolet range present numerous challenges when applied to such optical components. Traditional substrate materials, such as calcium fluoride, while exhibiting low light absorption in the deep ultraviolet band, suffer from low hardness, leading to stress concentration and chipping at high-curvature edges or sharp corners. This makes processing extremely difficult and expensive. Quartz substrates are easier to process and significantly cheaper than calcium fluoride. However, quartz itself possesses high hardness and a low coefficient of thermal expansion, resulting in intrinsic absorption near the 193nm wavelength, which reduces transmittance and limits its application in the deep ultraviolet band.
[0004] Given the current defects in antireflective coatings for irregularly shaped quartz substrates in the deep ultraviolet band, it is necessary to improve them. Summary of the Invention
[0005] Therefore, it is necessary to provide a deep ultraviolet irregular quartz element antireflection film and its preparation method to address the shortcomings of existing technologies.
[0006] To solve the above problems, this application adopts the following technical solution: One of the objectives of this application is to provide a deep ultraviolet irregularly shaped quartz element antireflection film, comprising: Base; A first fluorine-doped thin film layer is located on the surface of the substrate, and the first fluorine-doped thin film layer includes a single first MgF2 thin film layer; An antireflection membrane layer is located on the surface of the first fluorine-doped thin film layer away from the substrate; A second fluorine-doped thin film layer is located on the surface of the antireflection membrane layer away from the substrate, and the second fluorine-doped thin film layer includes a single second MgF2 thin film layer.
[0007] In some embodiments, the antireflective coating layer includes a plurality of Al2O3 thin film layers and SiO2 thin film layers arranged alternately in sequence.
[0008] In some embodiments, the substrate is an irregularly shaped quartz substrate.
[0009] In some embodiments, the thickness of the first MgF2 thin film layer is greater than 0 and less than or equal to 100 nm; the thickness of the second MgF2 thin film layer is greater than 0 and less than or equal to 100 nm; the thickness of the SiO2 thin film layer is 100~2500 nm; and the thickness of the Al2O3 thin film layer is 100~2500 nm.
[0010] In some embodiments, the SiO2 thin film layer and the Al2O3 thin film layer are interleaved 1 to 1000 times.
[0011] The second objective of this application is to provide a method for preparing an antireflective coating for a deep ultraviolet irregularly shaped quartz element, comprising the following steps: A first MgF2 thin film layer is deposited on the substrate surface to prepare a first fluorine-doped thin film layer; An antireflection film layer is prepared on the surface of the first fluorine-doped thin film layer; A second MgF2 thin film layer is deposited on the surface of the antireflection membrane to prepare a second fluorine-doped thin film layer.
[0012] In some embodiments, the step of depositing a first MgF2 thin film layer on the substrate surface to prepare the first fluorine-doped thin film layer specifically includes the following steps: Using MgF2 particles as the evaporation source, the first fluorine-doped thin film layer is deposited on the substrate surface by electron beam thermal evaporation; wherein: during the deposition of the first fluorine-doped thin film layer, the temperature of the substrate is controlled at 250~260℃, the deposition rate is 0.2~0.3 nm / s, and the deposition number of the first MgF2 thin film layer is 1~1000 times.
[0013] In some embodiments, the step of preparing an antireflection film layer on the surface of the first fluorine-doped thin film layer specifically includes the following steps: Using Al2O3 particles and SiO2 particles as evaporation sources, Al2O3 thin film layers and SiO2 thin film layers are sequentially and alternately deposited on the surface of the first fluorine-doped thin film layer using electron beam thermal evaporation to form the antireflection film layer; wherein: during the deposition of the Al2O3 thin film layer and the SiO2 thin film layer, the temperature of the substrate is controlled at 250~260℃, the deposition rate of the Al2O3 thin film layer is 0.2~0.4nm / s, and the deposition rate of the SiO2 thin film layer is 0.2~0.3nm / s.
[0014] In some embodiments, the step of depositing a second MgF2 thin film layer on the surface of the antireflection membrane to prepare a second fluorine-doped thin film layer specifically includes the following steps: Using MgF2 particles as the evaporation source, a second fluorine-doped thin film layer is deposited on the surface of the antireflection membrane using electron beam thermal evaporation. During the deposition of the second fluorine-doped thin film layer, the temperature of the substrate is controlled at 250~260℃, the deposition rate of the second fluorine-doped thin film layer is 0.2~0.3 nm / s, and the deposition number of the second MgF2 thin film layer is 1~1000 times.
[0015] In some embodiments, prior to the step of depositing a first MgF2 thin film layer on the substrate surface to prepare a first fluorine-doped thin film layer, a step of plasma treatment of the substrate is included, wherein: the plasma treatment gas includes oxygen and argon, the oxygen flow rate is 50-60 sccm, the argon flow rate is 8-10 sccm, the plasma treatment time is 60-120 s, the voltage is 700-710 V, and the current is 700-710 mA.
[0016] The present application adopts the above technical solution, and its beneficial effects are as follows: 1. The antireflective coating for deep ultraviolet irregularly shaped quartz elements and its preparation method provided by the present invention use fused silica substrate instead of calcium fluoride. Its price is less than 1 / 5 of that of calcium fluoride, and it has high hardness. It can be efficiently processed into irregularly shaped structures that are difficult to achieve with other calcium fluoride, such as the large-diameter, high-steep meniscus lens of fused silica used in the present invention. It is not prone to edge chipping, reduces equipment energy consumption, lowers costs, and effectively solves the problems of difficult and costly processing of irregularly shaped optical elements of calcium fluoride in lithography machines and deep ultraviolet lasers.
[0017] 2. The deep ultraviolet antireflective coating for irregularly shaped quartz elements provided by this invention, by depositing a first fluorine-doped MgF2 thin film layer on the substrate, can effectively solve the intrinsic absorption problem of irregularly shaped quartz substrates at 193nm, thereby improving the antireflection rate. Because the optical band gap of MgF2 is 10.8 eV (approximately 115 nm), which is greater than the energy corresponding to 193nm, at a wavelength of 193nm, the photon energy is insufficient to induce an electron transition, and the MgF2 thin film will not absorb light at this wavelength, effectively solving the light absorption problem of irregularly shaped quartz substrates at 193nm. Moreover, in the 193nm band, the refractive index of MgF2 is lower than that of the substrate. As the bottom layer, the first MgF2 thin film layer can cause incident light to be reflected and interfered at the film layer interface, reducing reflected light and allowing more light to enter the substrate. This relatively reduces the absorption ratio of light in the substrate, indirectly reducing the overall optical loss of the optical system and improving the antireflection rate.
[0018] 3. The deep ultraviolet irregularly shaped quartz element antireflective film of the present invention uses an irregularly shaped quartz substrate. The essential material of the fused silica is SiO2, which has a higher Mohs hardness than calcium fluoride, is easier to process, and has a lower difficulty in processing. Moreover, its coefficient of thermal expansion with CaF2 is 18.9~24.1×10⁻⁶.-6 / K, the coefficient of thermal expansion of quartz is 0.55×10 -6 / K, which is much lower than CaF2, can suppress problems such as film failure and peeling on irregularly shaped substrates under high-temperature coating.
[0019] 4. The deep ultraviolet antireflective coating for irregularly shaped quartz elements provided by this invention involves alternating deposition of Al2O3 and SiO2 thin film layers on a MgF2 thin film base. Utilizing the different stress characteristics of these two materials, the alternating deposition enhances the adhesion between the film and the substrate, adapting to the complex surfaces of irregularly shaped substrates. This further balances the film stress, effectively reducing the residual stress of the entire deep ultraviolet antireflective coating and minimizing the risk of cracking, deformation, and detachment. This deep ultraviolet antireflective coating exhibits excellent film-forming properties on irregularly shaped quartz substrates, uniformly covering all parts of the substrate, including edges, corners, and curved surfaces. Even on complex-shaped quartz substrates, it can form a complete and uniform film layer, ensuring consistent optical performance. Attached Figure Description
[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art 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.
[0021] Figure 1 A schematic diagram of the structure of the antireflective coating for the deep ultraviolet irregular quartz element provided in this application.
[0022] Figure 2 A flowchart illustrating the steps of the method for preparing the antireflective coating for the deep ultraviolet irregularly shaped quartz element provided in this application.
[0023] Figure 3 The membrane system design spectrum provided for the embodiments of this application. Detailed Implementation
[0024] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. In the description of this application, it should be understood that the terms "upper", "lower", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0025] In related technologies, the optical path systems in EUA lithography machines and deep ultraviolet lasers are complex and diverse. Spherical optical elements, due to their symmetrical shape, struggle to effectively correct aberrations such as spherical aberration and coma, requiring the stacking of multiple lenses, increasing reflection loss and stray light. Furthermore, the entire optical system becomes more cumbersome, resulting in less than ideal laser beam quality and stability, affecting the precision and quality of laser processing. In cutting-edge fields such as lithography, deep ultraviolet lasers, and aerospace, irregularly shaped optical elements, through breakthroughs in geometric freedom and material-co-design, are gradually replacing spherical elements, becoming the core carrier supporting technological iteration. This is because CaF2 is typically preferred as the substrate material in the fabrication of deep ultraviolet antireflection coatings. CaF2 has an optical bandgap of approximately 12 eV (absorption edge at 125 nm), far exceeding the deep ultraviolet photon energy (190 nm photon energy ≈ 6.5 eV, 210 nm ≈ 5.9 eV), and its extinction coefficient in deep ultraviolet light is almost zero, resulting in virtually no light absorption. However, CaF2 is softer and more brittle than quartz. During processing, stress concentration occurs at high curvature edges or sharp corners, making it prone to chipping. Therefore, the processing of irregular shapes from CaF2 is very difficult.
[0026] 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.
[0027] like Figure 1 As shown, the present invention provides an antireflective coating for a deep ultraviolet irregularly shaped quartz element, comprising: a substrate 110, a first fluorine-doped thin film layer 120, an antireflective coating layer 130, and a second fluorine-doped thin film layer 140. The specific implementation of each component is described in detail below.
[0028] In this embodiment, the substrate 110 is an irregularly shaped quartz substrate.
[0029] It is understood that this embodiment uses an irregularly shaped quartz substrate, namely a large-diameter, high-steep meniscus lens made of fused silica. Generally, calcium fluoride is preferred as the substrate for preparing deep ultraviolet antireflective coatings; however, calcium fluoride is soft and brittle, and is prone to edge chipping when processed into a meniscus lens, making processing very difficult. This invention uses fused silica, whose essential material is SiO2, which has a higher Mohs hardness than calcium fluoride, making it easier to process and less difficult to manufacture. Furthermore, CaF2 has a coefficient of thermal expansion of 18.9~24.1×10⁻⁶. -6 / K, the coefficient of thermal expansion of quartz is 0.55×10 -6 The K content is significantly lower than that of CaF2, which can suppress problems such as film failure and peeling on irregularly shaped substrates under high-temperature coating. In addition, the price of fused silica is only 1 / 5 of that of calcium fluoride, effectively reducing the overall cost.
[0030] A first fluorine-doped thin film layer 120 is located on the surface of the substrate 110, and the first fluorine-doped thin film layer includes a single first MgF2 thin film layer.
[0031] In this embodiment, the thickness of the first MgF2 thin film layer is greater than 0 and less than or equal to 100 nm.
[0032] It is understood that the antireflection coating system design for deep ultraviolet irregularly shaped quartz elements of the present invention employs the first deposition of a fluorine-doped MgF2 thin film layer on an irregularly shaped quartz substrate, which can effectively solve the intrinsic absorption problem of the irregularly shaped quartz substrate at 193nm and improve the antireflection rate. Because the optical band gap of MgF2 is 10.8 eV (approximately 115 nm), which is greater than the energy corresponding to 193nm, at a wavelength of 193nm, the photon energy is insufficient to induce an electron transition, and the film itself will not absorb light at this wavelength, effectively solving the light absorption problem of the irregularly shaped quartz substrate at 193nm. Furthermore, in the 193nm band, the refractive index of MgF2 is approximately 1.376, while the refractive index of the irregularly shaped quartz substrate is approximately 1.54. Since the refractive index of MgF2 is lower than that of the irregular quartz substrate, as the bottom film, the MgF2 thin film layer can cause incident light to be reflected and interfered at the film layer interface, reducing the reflected light and allowing more light to enter the irregular quartz substrate. This relatively reduces the absorption ratio of light in the irregular quartz substrate, indirectly reducing the overall light loss of the system and improving the transmittance.
[0033] The antireflective film layer 130 is located on the surface of the first fluorine-doped thin film layer away from the substrate.
[0034] In some embodiments, the antireflective coating layer 130 includes a plurality of Al2O3 thin film layers 131 and SiO2 thin film layers 132 arranged alternately in sequence.
[0035] Furthermore, the SiO2 thin film layer and the Al2O3 thin film layer are interleaved 1 to 1000 times. Furthermore, the thickness of the SiO2 thin film layer is 100 to 2500 nm; the thickness of the Al2O3 thin film layer is 100 to 2500 nm.
[0036] It is understood that in this embodiment, Al2O3 and SiO2 thin film layers are alternately deposited on a MgF2 thin film layer. This utilizes the different stress characteristics of the two materials to enhance the adhesion between the film and the substrate, adapting to complex surfaces of irregularly shaped substrates, further balancing film stress, effectively reducing residual stress in the entire antireflective film, and minimizing the risk of cracking, deformation, and detachment. This antireflective film exhibits excellent film-forming properties on irregularly shaped quartz substrates, uniformly covering all parts of the substrate, including edges, corners, and curved surfaces. Even on complex-shaped quartz substrates, a complete and uniform film layer can be formed, ensuring consistent optical performance.
[0037] The second fluorine-doped thin film layer 140 is located on the surface of the antireflection membrane layer away from the substrate, and the second fluorine-doped thin film layer includes a single second MgF2 thin film layer.
[0038] In this embodiment, the thickness of the second MgF2 thin film layer is greater than 0 and less than or equal to 100 nm.
[0039] It is understood that the thickness and number of each of the first MgF2 thin film layer, the second MgF2 thin film layer, the Al2O3 thin film layer, and the SiO2 thin film layer provided in this embodiment can be precisely controlled according to their thermal expansion coefficient and the required overall performance, so as to disperse and alleviate the problem of thermal stress concentration, so that the antireflective film can maintain its optical performance stability in high temperature environment and is not prone to oxidation decomposition between film layers or film peeling.
[0040] The deep ultraviolet antireflective coating for irregularly shaped quartz elements provided in the above embodiments of the present invention, by depositing a first fluorine-doped MgF2 thin film layer on the substrate, can effectively solve the intrinsic absorption problem of irregularly shaped quartz substrates at 193nm and improve the antireflection rate. Because the optical band gap of MgF2 is 10.8 eV (approximately 115 nm), which is greater than the energy corresponding to 193nm, at a wavelength of 193nm, the photon energy is insufficient to induce an electron transition, and the film itself will not absorb light at this wavelength, effectively solving the light absorption problem of irregularly shaped quartz substrates at 193nm. Moreover, in the 193nm band, the refractive index of MgF2 is lower than that of the substrate. As the bottom layer, the first MgF2 thin film layer can cause incident light to be reflected and interfered at the film layer interface, reducing reflected light and allowing more light to enter the substrate, thereby relatively reducing the absorption ratio of light in the substrate, indirectly reducing the overall light loss of the system and improving the antireflection rate.
[0041] Please see Figure 2 The present invention also provides a method for preparing a deep ultraviolet irregular quartz element antireflection film, which includes the following steps S110 to S130. The specific implementation of each component is described in detail below.
[0042] Step S110: A first MgF2 thin film layer is deposited on the substrate surface to prepare a first fluorine-doped thin film layer.
[0043] In this embodiment, the step of depositing a first MgF2 thin film layer on the substrate surface to prepare the first fluorine-doped thin film layer specifically includes the following steps: Using MgF2 particles as the evaporation source, the first fluorine-doped thin film layer is deposited on the substrate surface by electron beam thermal evaporation; wherein: during the deposition of the first fluorine-doped thin film layer, the temperature of the substrate is controlled at 250~260℃, the deposition rate is 0.2~0.3 nm / s, and the deposition number of the first MgF2 thin film layer is 1~1000 times.
[0044] Preferably, the substrate temperature is controlled at 250°C and the deposition rate of the first MgF2 thin film layer is 0.2 nm / s.
[0045] In this embodiment, the substrate 110 is an irregularly shaped quartz substrate.
[0046] It is understood that this embodiment uses an irregularly shaped quartz substrate, namely a large-diameter, high-steep meniscus lens made of fused silica. Generally, calcium fluoride is preferred as the substrate for preparing deep ultraviolet antireflective coatings; however, calcium fluoride is soft and brittle, and is prone to edge chipping when processed into a meniscus lens, making processing very difficult. This invention uses fused silica, whose essential material is SiO2, which has a higher Mohs hardness than calcium fluoride, making it easier to process and less difficult to manufacture; moreover, its coefficient of thermal expansion with CaF2 is 18.9~24.1×10⁻⁶. -6 / K, the coefficient of thermal expansion of quartz is 0.55×10 -6 The K value is much lower than that of CaF2, which can suppress problems such as film failure and peeling on irregularly shaped substrates under high-temperature coating.
[0047] It is understood that the antireflection coating system design for deep ultraviolet irregularly shaped quartz elements of the present invention employs the first deposition of a fluorine-doped MgF2 thin film layer on an irregularly shaped quartz substrate, which can effectively solve the intrinsic absorption problem of the irregularly shaped quartz substrate at 193nm and improve the antireflection rate. Because the optical band gap of MgF2 is 10.8 eV (approximately 115 nm), which is greater than the energy corresponding to 193nm, at a wavelength of 193nm, the photon energy is insufficient to induce an electron transition, and the film itself will not absorb light at this wavelength, effectively solving the light absorption problem of the irregularly shaped quartz substrate at 193nm. Furthermore, in the 193nm band, the refractive index of MgF2 is approximately 1.376, while the refractive index of the irregularly shaped quartz substrate is approximately 1.54. Since the refractive index of MgF2 is lower than that of the irregular quartz substrate, as the bottom film, the MgF2 thin film layer can cause incident light to be reflected and interfered at the film layer interface, reducing the reflected light and allowing more light to enter the irregular quartz substrate. This relatively reduces the absorption ratio of light in the irregular quartz substrate, indirectly reducing the overall light loss of the system and improving the transmittance.
[0048] Step S120: An antireflection membrane is prepared on the surface of the first fluorine-doped thin film layer.
[0049] In this embodiment, the step of preparing an antireflection film layer on the surface of the first fluorine-doped thin film layer specifically includes the following steps: Using Al2O3 particles and SiO2 particles as evaporation sources, Al2O3 thin film layers and SiO2 thin film layers are sequentially and alternately deposited on the surface of the first fluorine-doped thin film layer using electron beam thermal evaporation to form the antireflection film layer; wherein: during the deposition of the Al2O3 thin film layer and the SiO2 thin film layer, the temperature of the substrate is controlled at 250~260℃, the deposition rate of the Al2O3 thin film layer is 0.2~0.4nm / s, and the deposition rate of the SiO2 thin film layer is 0.2~0.3nm / s.
[0050] Preferably, the substrate temperature is controlled at 250°C, the deposition rate of the Al2O3 thin film layer is 0.2~0.4 nm / s, the deposition rate is 0.3 nm / s, and the deposition rate of the SiO2 thin film layer is 0.25 nm / s.
[0051] It is understood that in this embodiment, Al2O3 and SiO2 thin film layers are alternately deposited on a MgF2 thin film layer. This utilizes the different stress characteristics of the two materials to enhance the adhesion between the film and the substrate, adapting to complex surfaces of irregularly shaped substrates, further balancing film stress, effectively reducing residual stress in the entire antireflective film, and minimizing the risk of cracking, deformation, and detachment. This antireflective film exhibits excellent film-forming properties on irregularly shaped quartz substrates, uniformly covering all parts of the substrate, including edges, corners, and curved surfaces. Even on complex-shaped quartz substrates, a complete and uniform film layer can be formed, ensuring consistent optical performance.
[0052] Step S130: A second MgF2 thin film layer is deposited on the surface of the antireflection membrane to prepare a second fluorine-doped thin film layer.
[0053] The step of depositing a second MgF2 thin film layer on the surface of the antireflection membrane to prepare a second fluorine-doped thin film layer specifically includes the following steps: Using MgF2 particles as the evaporation source, a second fluorine-doped thin film layer is deposited on the surface of the deep ultraviolet antireflection film layer by electron beam thermal evaporation. During the deposition of the second fluorine-doped thin film layer, the temperature of the substrate is controlled at 250~260℃, the deposition rate of the second fluorine-doped thin film layer is 0.2~0.3 nm / s, and the deposition number of the second MgF2 thin film layer is 1~1000 times.
[0054] In some embodiments, before depositing the first MgF2 thin film layer on the substrate surface, the substrate is further subjected to plasma treatment, wherein the plasma treatment gas includes oxygen and argon, the oxygen flow rate is 50-60 sccm, the argon flow rate is 8-10 sccm, the plasma treatment time is 60-120 s, the voltage is 700-710 V, and the current is 700-710 mA; preferably, the oxygen flow rate is 55 sccm, the argon flow rate is 8 sccm, the plasma treatment time is 60 s, the voltage is 700 V, and the current is 700 mA.
[0055] It is understood that the thickness and number of each of the first MgF2 thin film layer, the second MgF2 thin film layer, the Al2O3 thin film layer, and the SiO2 thin film layer provided in this embodiment can be precisely controlled according to their thermal expansion coefficient and the required overall performance, so as to disperse and alleviate the problem of thermal stress concentration, so that the antireflective film can maintain its optical performance stability in high temperature environment and is not prone to oxidation decomposition between film layers or film peeling.
[0056] The method for preparing a deep ultraviolet antireflective coating for irregularly shaped quartz elements provided in the above embodiments of the present invention effectively solves the problem of intrinsic absorption at 193 nm in irregularly shaped quartz substrates by depositing a first fluorine-doped MgF2 thin film layer on the substrate, thereby improving the antireflection rate. Because the optical band gap of MgF2 is 10.8 eV (approximately 115 nm), which is greater than the energy corresponding to 193 nm, the photon energy at 193 nm is insufficient to induce electron transitions, and the film itself will not absorb light at this wavelength, effectively solving the light absorption problem of irregularly shaped quartz substrates at 193 nm. Furthermore, in the 193 nm band, the refractive index of MgF2 is lower than that of the substrate. As the bottom layer, the first MgF2 thin film layer allows incident light to be reflected and interfered at the film interface, reducing reflected light and allowing more light to enter the substrate. This relatively reduces the absorption ratio of light in the substrate, indirectly reducing the overall light loss of the system and improving the antireflection rate.
[0057] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.
[0058] The following specific embodiments further illustrate the deep ultraviolet band irregularly shaped quartz substrate antireflection film and its preparation method of this application. This section further illustrates the content of the present invention with reference to specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.
[0059] Example 1 The method for preparing the antireflective coating for deep ultraviolet irregularly shaped quartz elements provided in Example 1 of this application includes the following steps: S1. Select high-purity MgF2, Al2O3, and SiO2 particles and add them to the evaporation crucible of the electron beam thermal evaporation coating machine; S2. Use a mechanical pump and an oil diffusion pump to evacuate the vacuum chamber of the vacuum coating machine to a value less than 2 × 10⁻⁶. -3 Pa, using heating wires to raise the temperature of the vacuum chamber to the set temperature of 250°C; S3. 55 sccm of oxygen is introduced into the radio frequency ion source body, and 8 sccm of argon is introduced into the ion source neutralizer to generate plasma to clean the fused silica large-diameter high-steep meniscus lens substrate; the plasma treatment time is 60 s, the voltage is 700 V, and the current is 700 mA. S4. After cleaning the fused silica large-diameter high-steep meniscus lens substrate, the first MgF2 thin film layer is deposited on the substrate by electron beam thermal evaporation to prepare the first fluorine-doped deep ultraviolet protective layer. S5. An antireflective membrane layer is prepared by sequentially depositing Al2O3 thin film layer and SiO2 thin film layer on the surface of the first fluorine-doped deep ultraviolet protective layer using electron beam thermal evaporation. S6. A second MgF2 thin film layer is obtained by sequentially and alternately depositing on the surface of the antireflection membrane using electron beam thermal evaporation to prepare a second fluorine-doped deep ultraviolet protective layer. S7. Thin film deposition is complete. The vacuum chamber is cooled for 60 minutes to complete the preparation of the antireflective film on the irregularly shaped quartz substrate in the deep ultraviolet band. The sample is then removed.
[0060] Please refer to the table below for the parameters of the specific components of the deep ultraviolet irregular quartz element antireflection film prepared by the above method in this embodiment.
[0061]
[0062] Please see Figure 3 The deep ultraviolet irregular quartz element antireflection film system design diagram provided in this embodiment consists of a substrate-MgF2 thin film layer-Al2O3 thin film layer-SiO2 thin film layer-MgF2 thin film layer. This film system structure can effectively solve the absorption difficulty of fused silica at 193nm and improve the transmittance of fused silica large-diameter high-steep meniscus lens at 193nm to 99.98%.
[0063] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0064] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.
Claims
1. A deep ultraviolet irregularly shaped quartz element antireflection film, characterized in that, include: Base; A first fluorine-doped thin film layer is located on the surface of the substrate, and the first fluorine-doped thin film layer includes a single first MgF2 thin film layer; An antireflection membrane layer is located on the surface of the first fluorine-doped thin film layer away from the substrate; A second fluorine-doped thin film layer is located on the surface of the antireflection membrane layer away from the substrate, and the second fluorine-doped thin film layer includes a single second MgF2 thin film layer.
2. The antireflective film for deep ultraviolet irregularly shaped quartz elements as described in claim 1, characterized in that, The antireflective coating comprises multiple Al2O3 thin film layers and SiO2 thin film layers arranged alternately in sequence.
3. The antireflective film for deep ultraviolet irregularly shaped quartz elements as described in claim 1, characterized in that, The substrate is an irregularly shaped quartz substrate, namely a large-diameter, high-steep meniscus lens made of fused quartz.
4. The antireflective film for deep ultraviolet irregularly shaped quartz elements as described in claim 1, characterized in that, The thickness of the first MgF2 thin film layer is greater than 0 and less than or equal to 100 nm; the thickness of the second MgF2 thin film layer is greater than 0 and less than or equal to 100 nm; the thickness of the SiO2 thin film layer is 100~2500 nm; and the thickness of the Al2O3 thin film layer is 100~2500 nm.
5. The antireflective film for deep ultraviolet irregularly shaped quartz elements as described in claim 2, characterized in that, The SiO2 thin film layer and the Al2O3 thin film layer are interleaved 1 to 1000 times.
6. A method for preparing a deep ultraviolet irregularly shaped quartz element antireflection film, characterized in that, Includes the following steps: A first MgF2 thin film layer is deposited on the substrate surface to prepare a first fluorine-doped thin film layer; An antireflection film layer is prepared on the surface of the first fluorine-doped thin film layer; A second MgF2 thin film layer is deposited on the surface of the antireflection membrane to prepare a second fluorine-doped thin film layer.
7. The method for preparing the antireflective film for deep ultraviolet irregularly shaped quartz elements as described in claim 6, characterized in that, The step of depositing a first MgF2 thin film layer on a substrate surface to prepare a first fluorine-doped thin film layer specifically includes the following steps: Using MgF2 particles as the evaporation source, the first fluorine-doped thin film layer is deposited on the substrate surface by electron beam thermal evaporation; wherein: during the deposition of the first fluorine-doped thin film layer, the temperature of the substrate is controlled at 250~260℃, the deposition rate is 0.2~0.3 nm / s, and the deposition number of the first MgF2 thin film layer is 1~1000 times.
8. The method for preparing the antireflective film for deep ultraviolet irregularly shaped quartz elements as described in claim 1, characterized in that, The step of preparing an antireflection film layer on the surface of the first fluorine-doped thin film layer specifically includes the following steps: Using Al2O3 particles and SiO2 particles as evaporation sources, Al2O3 thin film layers and SiO2 thin film layers are sequentially and alternately deposited on the surface of the first fluorine-doped thin film layer by electron beam thermal evaporation to prepare the antireflection film layer; wherein: during the deposition of the Al2O3 thin film layer and the SiO2 thin film layer, the temperature of the substrate is controlled at 250~260℃, the deposition rate of the Al2O3 thin film layer is 0.2~0.4nm / s, and the deposition rate of the SiO2 thin film layer is 0.2~0.3nm / s.
9. The method for preparing the antireflective coating for deep ultraviolet irregularly shaped quartz elements as described in claim 1, characterized in that, The step of depositing a second MgF2 thin film layer on the surface of the antireflection membrane to prepare a second fluorine-doped thin film layer specifically includes the following steps: Using MgF2 particles as the evaporation source, a second fluorine-doped thin film layer is deposited on the surface of the antireflection film layer of the deep ultraviolet irregular quartz element by electron beam thermal evaporation. The temperature of the substrate is controlled at 250~260℃ during the deposition of the second fluorine-doped thin film layer, the deposition rate of the second fluorine-doped thin film layer is 0.2~0.3 nm / s, and the deposition number of the second MgF2 thin film layer is 1~1000 times.
10. The method for preparing the antireflective film for deep ultraviolet irregularly shaped quartz elements as described in claim 6, characterized in that, Before the step of depositing a first MgF2 thin film layer on the substrate surface to prepare a first fluorine-doped thin film layer, the method further includes a plasma treatment step on the substrate, wherein: the plasma treatment gas includes oxygen and argon, the oxygen flow rate is 50~60 sccm, the argon flow rate is 8~10 sccm, the plasma treatment time is 60~120 s, the voltage is 700~710V, and the current is 700~710 mA.