Multilayer film, optical member, and multilayer film production method

Abstract

The present invention addresses the problem of providing a multilayer film that exhibits a sufficient self-cleaning function via a photocatalytic reaction at a surface thereof even when the film thickness of a low-refractive-index layer at the surface is set to specific thickness or greater in order to reduce light reflectance, and that can maintain hydrophilicity in darkness over a long period. In order to solve this problem, the present invention is a multilayer film characterized in that: a layer containing cerium oxide contains cerium oxide that includes a cubic polycrystalline structure and a columnar structure; the film thickness of the layer containing cerium oxide is 85-800 nm; when a region (A) is defined as the entirety of the layer containing cerium oxide and an oxygen deficiency rate (VA) is defined as the oxygen deficiency rate of cerium oxide in the region (A), the oxygen deficiency rate (VA) is 0.05-10%; the film thickness of a layer containing silicon oxide or a layer containing magnesium fluoride is 50-240 nm; and the refractive index of a layer containing a low-refractive-index layer with respect to light of a wavelength of 500 nm is not more than 1.65.

Description

Multilayer film, optical member, and method for manufacturing multilayer film

[0001] The present disclosure relates to a multilayer film having excellent self-cleaning properties and hydrophilicity, an optical element having the multilayer film, and a method for manufacturing the multilayer film.

[0002] Optical components such as optical lenses, mirrors, and optical filters have films formed from inorganic materials to increase or decrease light transmittance or reflectance. Films formed from inorganic materials generally have high surface free energy immediately after deposition, resulting in high hydrophilicity. However, due to self-reactions and the adhesion of human or environmental contaminants, the surface free energy decreases in a relatively short time, resulting in a decrease in hydrophilicity.

[0003] For example, if water droplets adhere to optical products used in automobiles, security cameras, optical products used outdoors such as eyeglass lenses, or the surfaces of these protective covers when their hydrophilicity is reduced, visibility may be impaired, and the optical products or protective covers may not be able to fully function.

[0004] To solve the above-mentioned problems, a hydrophilic film in which a thin film of silicon dioxide is formed on a thin film of crystalline titanium dioxide is used (Patent Document 1, Patent Document 2, Non-Patent Document 1). When the surface of crystalline titanium dioxide is irradiated with near-ultraviolet light, active oxygen is generated by the photocatalytic function, and the generated active oxygen decomposes organic matter on the surface of the hydrophilic film. As a result, the hydrophilicity of the hydrophilic film is restored, and dirt is washed away by rain, resulting in self-purification. Furthermore, by placing silicon dioxide on top of titanium dioxide, even when light irradiation is stopped, the film does not become hydrophobic in a short period of time as occurs with a thin film of titanium dioxide alone, and it is known that the hydrophilicity continues for about 1 to 2 weeks even in a dark place.

[0005] However, as shown in Table 2 of Patent Document 1, when the silicon dioxide thin film formed on the crystalline titanium dioxide thin film is less than 50 nm, the high refractive index of titanium dioxide results in an increased reflectance and a decreased transmittance, which is a problem. Therefore, while this film may be applicable to vehicle door mirrors and other applications where a high reflectance is not a problem, it is not suitable for optical components such as lenses equipped with anti-reflection coatings. Furthermore, when the silicon dioxide thin film formed on the surface of the crystalline titanium dioxide thin film is 50 nm or thicker, the self-cleaning function via photocatalytic reaction is not fully realized. Additionally, although the hydrophilicity retention performance in dark places is improved compared to the case of crystalline titanium dioxide alone, it is still not sufficient.

[0006] Furthermore, as described in the examples of Patent Document 2 and Non-Patent Document 1, when a crystalline titanium dioxide layer is used as a photocatalyst, the thin film or the substrate on which the thin film is provided may need to be heated to high temperatures to crystallize the thin film made of titanium dioxide, which poses a problem that resin substrates with low heat resistance cannot be used. Some wet processes for forming titanium dioxide films do not require high-temperature heating. However, when using wet processes, it is difficult to precisely control the film thickness in 1-nm increments, form a thin film with a uniform film thickness, and form a film on a substrate other than a substrate with a simple shape such as a flat plate. Furthermore, there are inherent problems, such as a short shelf life of the coating liquid.

[0007] JP 2000-053449 JP 09-057912

[0008] K. Miyashita, et al, Journal of the Ceramic Society of Japan 110 [5] 450-454 (2002)

[0009] Considering application to optical components, a multilayer film is desired that can fully exhibit the self-cleaning function through photocatalytic reaction even when the low refractive index layer is thick so that the low refractive index layer on the surface of the optical component can be designed as an anti-reflection film. Also, a multilayer film that can maintain its hydrophilicity for a longer period in a dark place is desired.

[0010] The present disclosure has been made in view of the above-mentioned problems, and aims to provide a multilayer film that can fully exhibit a self-cleaning function through a photocatalytic reaction on the surface and maintain hydrophilicity in a dark place for a long period of time, even when the film thickness of the low refractive index layer on the surface is set to a specific thickness or more to reduce light reflectance. The present disclosure also aims to provide an optical element having the multilayer film. Another aim of the present disclosure is to provide a method for manufacturing the multilayer film.

[0011] In order to solve the above problems, the present disclosure provides a cerium oxide-containing film having a layer containing cerium oxide and a low refractive index layer formed on the cerium oxide-containing layer directly or via another layer, the low refractive index layer having a layer containing silicon oxide or a layer containing magnesium fluoride, the cerium oxide-containing layer containing cerium oxide having a cubic polycrystalline structure and a columnar structure, the cerium oxide-containing layer having a film thickness of 85 nm or more and 800 nm or less, the entire cerium oxide-containing layer being defined as region (A), and the oxygen deficiency rate of the cerium oxide in region (A) being defined as oxygen deficiency rate (V Ａ ), the oxygen deficiency rate (V Ａ ) is 0.05% or more and 10% or less, the film thickness of the low refractive index layer is 50 nm or more and 240 nm or less, and the refractive index of the low refractive index layer for light with a wavelength of 500 nm is 1.65 or less.

[0012] The present disclosure also provides an optical member having the above multilayer film.

[0013] The present disclosure also provides a method for manufacturing a cerium oxide-containing film, comprising: a step (A) of forming a cerium oxide-containing layer on a substrate by vacuum deposition, either directly or via another layer; and a step (B) of forming a low refractive index layer on the cerium oxide-containing layer by vacuum deposition, either directly or via another layer; wherein the low refractive index layer has a layer containing silicon oxide or a layer containing magnesium fluoride; the cerium oxide-containing layer contains cerium oxide having a cubic polycrystalline structure and a columnar structure; the cerium oxide-containing layer has a film thickness of 85 nm or more and 800 nm or less; the entire cerium oxide-containing layer is defined as region (A), and the oxygen deficiency rate of the cerium oxide in region (A) is defined as oxygen deficiency rate (V Ａ ), the oxygen deficiency rate (V Ａ ) is 0.5% or more and 10% or less, and the film thickness of the low refractive index layer is 50 nm or more and 240 nm or less.

[0014] According to one aspect of the present disclosure, even when the film thickness of the low refractive index layer on the surface is made to be equal to or greater than a specific thickness in order to reduce the reflectance of light, a multilayer film that exhibits sufficient self-cleaning function through a photocatalytic reaction on the surface and can maintain hydrophilicity for a long period of time even in a dark place, an optical element having the multilayer film, and a method for manufacturing the multilayer film can be obtained.

[0015] Fig. 1 is a schematic cross-sectional view showing a configuration in a first embodiment according to the present disclosure. Fig. 2 is a schematic cross-sectional view for explaining the first embodiment according to the present disclosure. Fig. 3 is a schematic cross-sectional view showing a configuration in a second embodiment according to the present disclosure. Fig. 4 is a schematic view showing an example of an application example according to the present disclosure. Fig. 5 is a schematic view showing another example of an application example according to the present disclosure.

[0016] Hereinafter, preferred embodiments of the multilayer film, optical member having the multilayer film, and method for forming the multilayer film according to the present disclosure will be described. The present disclosure is not limited to the following embodiments. Furthermore, in the present disclosure, the expressions [XX or more and YY or less] and [XX to YY] representing a numerical range mean a numerical range including a lower limit and an upper limit, which are endpoints, unless otherwise specified. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way.

[0017] In the present disclosure, the term "multilayer film" refers to a structure including two or more layers formed on the surface of a substrate. The multilayer film according to the present disclosure can be provided on the substrate directly or via another layer. Hereinafter, the layers constituting the multilayer film may also be referred to as a film or a thin film.

[0018] In the present disclosure, the "substrate" is a solid article.

[0019] In the present disclosure, the term "optical member" refers to an optical member having the above-described multilayer film, and examples of such optical members include optical filters, optical lenses, light-collecting lenses, optical films, optical prisms, eyeglass lenses, photographic lenses, surveillance camera covers, in-vehicle camera covers, in-vehicle sensor covers, vehicle door mirrors, platform door sensors, light-collecting lens covers, plate glass, condenser lenses, display cover glass, touch panels, and various films.

[0020] Before specifically describing the multilayer film according to the present disclosure, a hypothetical mechanism for achieving the effects thereof will be described below to facilitate understanding of the present disclosure. However, the following explanation is merely a hypothesis, and the present disclosure is not limited by the hypothesis.

[0021] The present inventors have discovered that when a layer containing cerium oxide, which has a cubic polycrystalline structure with specific oxygen vacancies, is disposed on a substrate directly or via another layer, and a layer containing magnesium fluoride or silicon oxide with a specific thickness is disposed on the cerium oxide layer directly or via another layer, the hydrophilicity recovery function due to the photocatalytic self-purification property is exhibited and the ability to maintain hydrophilicity in a dark place is dramatically improved. The following is thought to be the mechanism behind this.

[0022] When a near-ultraviolet light-responsive photocatalytic film is irradiated with near-ultraviolet light, electrons and holes are generated by photoexcitation. If the generated electrons and holes reach the surface of the film, a chemical reaction occurs, and hydrophilicity recovery function due to self-cleaning properties is realized. The cerium oxide in the cerium oxide-containing layer of the present disclosure has an appropriate amount of oxygen vacancies. The absence of an excess of oxygen vacancies suppresses recombination of holes and electrons generated by photoexcitation. As a result, photocatalytic activity is enhanced. Furthermore, a lack of oxygen vacancies suppresses a decrease in the mobility of electrons and holes generated by photoexcitation. As a result, a decrease in the self-cleaning function of the photocatalyst is suppressed.

[0023] Furthermore, the presence of oxygen vacancies allows the thin film and the environment to absorb water molecules (H ２ O) and oxygen molecules (O ２ ) are captured by oxygen vacancies, generating active species even in an environment without ultraviolet light, contributing to maintaining the hydrophilicity of the surface in the dark. In addition, in the layer containing cerium oxide of the present disclosure, oxygen vacancies are present, particularly at the polycrystalline interface. This improves electrical conductivity, promoting the separation of electrons and holes generated by photoexcitation, allowing the electrons and holes to move smoothly along the interface and easily reach the surface. As a result, it is believed that the hydrophilicity recovery function due to the self-cleaning properties of the photocatalyst is realized, and the ability to maintain hydrophilicity in the dark is dramatically improved.

[0024] First Embodiment The first embodiment relates to a multilayer film. The multilayer film of the present disclosure includes a layer containing cerium oxide and a low refractive index layer disposed directly on the cerium oxide layer or via another layer, the low refractive index layer having a layer containing silicon oxide or a layer containing magnesium fluoride, the cerium oxide layer containing cerium oxide having a cubic polycrystalline structure and a columnar structure, the cerium oxide layer having a thickness of 85 nm to 800 nm, the entire cerium oxide layer being defined as a region (A), and the oxygen deficiency rate of the cerium oxide in the region (A) being defined as an oxygen deficiency rate (V Ａ ), the oxygen deficiency rate (V Ａ ) is 0.05% or more and 10% or less, the film thickness of the low refractive index layer is 50 nm or more and 240 nm or less, and the refractive index of the low refractive index layer for light with a wavelength of 500 nm is 1.65 or less.

[0025] The multilayer film of the present disclosure includes a cerium oxide-containing layer and a low refractive index layer, either directly on the cerium oxide-containing layer or via another layer, and the low refractive index layer includes a silicon oxide-containing layer or a magnesium fluoride-containing layer. FIG. 1A is a schematic cross-sectional view showing a first embodiment of the multilayer film of the present disclosure provided on a substrate. FIG. 1A shows a configuration example in which a cerium oxide-containing layer 13 of the present disclosure is formed on a substrate 11, and a magnesium fluoride-containing layer 14 is further formed as a low refractive index layer on the cerium oxide-containing layer 13. In FIG. 1A (and FIG. 1B described below), a silicon oxide-containing layer 15 may be formed on the cerium oxide-containing layer 13 instead of the magnesium fluoride-containing layer 14. Note that FIGS. 1A, 1B, and 2 are schematic representations of the configuration of the multilayer film of the present disclosure. Therefore, the areas and film thicknesses of each layer are not expressed to exact proportions.

[0026] The substrate 11 will now be described. The substrate 11 may be any material that can be laminated with the other layer 12 and the cerium oxide-containing layer 13 of the present disclosure, and glass, ceramics, resin, metal, and the like can be used. The shape of the substrate is not limited, and may be, for example, flat, curved, concave, convex, or film-like. The substrate 11 may also have a hard coat layer or a barrier layer. In addition, the size and thickness of the substrate 11 are not particularly limited, and can be appropriately set depending on the application, etc.

[0027] The cerium oxide-containing layer 13 according to the present disclosure will be described. In the multilayer film according to the present disclosure, the entire layer containing cerium oxide is designated as region (A), and the oxygen deficiency rate of cerium oxide in region (A) is defined as the oxygen deficiency rate (V Ａ ) when the oxygen deficiency rate (V Ａ ) is 0.05% or more and 10% or less. If the oxygen deficiency rate is less than 0.05%, the mobility of electrons and holes excited by light decreases, and the self-cleaning function of the photocatalyst decreases. If it exceeds 10%, the electrons and holes excited by light tend to recombine, and the self-cleaning function of the photocatalyst decreases.

[0028] In the present disclosure, the oxygen deficiency rate is defined as the oxygen content of cerium oxide, A, and CeO ２ When the theoretical oxygen content is B, the oxygen deficiency rate can be expressed as (B-A) / B x 100 (%). For example, ２ The oxygen deficiency rate is 0%, CeO ２ When it is assumed that all oxygen atoms are absent (when it is Ce), the oxygen deficiency rate is 100%.

[0029] The multilayer film of the present disclosure has an oxygen deficiency rate (V Ａ When the oxygen deficiency rate is 0.05% or more, the self-purifying function and the ability to maintain hydrophilicity are further improved.

[0030] The multilayer film of the present disclosure has an oxygen deficiency rate (V ＡIt is more preferable that the oxygen deficiency rate is 0.1% or more and 0.3% or less. When the oxygen deficiency rate is in this range, the self-purifying function and the ability to maintain hydrophilicity are further improved.

[0031] In the multilayer film of the present disclosure, the cerium oxide-containing layer 13 is made of cerium oxide (CeO ｘ ) is contained. A layer made of cerium oxide with a single crystal structure is prone to cracking. A layer made of cerium oxide with an amorphous structure significantly reduces the photocatalytic self-cleaning function and the ability to maintain hydrophilicity in the dark.

[0032] In addition, the definition of "polycrystalline structure" in the present disclosure means that a peak specific to cerium oxide appears in X-ray diffraction (XRD) measurement of the film after deposition.

[0033] In the multilayer film of the present disclosure, the thickness of the cerium oxide-containing layer 13 is 85 nm or more and 800 nm or less. If the thickness of the cerium oxide-containing layer 13 is less than 85 nm, the photocatalytic self-cleaning function and the ability to maintain hydrophilicity in dark places are significantly reduced. On the other hand, if the thickness of the cerium oxide-containing layer 13 exceeds 800 nm, cracks are likely to occur, and light scattering due to heterogeneity, surface roughness, and polycrystalline crystal interfaces may become too large, which may adversely affect the optical properties.

[0034] In the multilayer film of the present disclosure, the cerium oxide-containing layer 13 contains cerium oxide having a columnar structure. The columnar structure promotes the separation of electrons and holes excited by light and makes it easier for the electrons and holes to reach the surface. This enhances the self-purification function of the photocatalyst.

[0035] Here, the term "columnar structure" in the present disclosure is defined. The columnar structure refers to the inclusion of polycrystals such as cylindrical, prismatic, frustum-shaped, rod-shaped, and fibrous columns in the film. The columnar structure may be solid or hollow. The longitudinal direction of the columnar structure generally grows from the substrate side of the film toward the outside air side of the film, and includes those that extend straight vertically, those that extend at an angle, those that extend while curving, those that extend branched like branches, and those in which multiple columnar crystals fuse during growth.

[0036] The cerium oxide-containing layer 13 of the present disclosure may be disposed directly on the substrate 11, or may be disposed via another layer 12 described below.

[0037] In the multilayer film of the present disclosure, the low refractive index layer has a thickness of 50 nm or more and 240 nm or less. In the multilayer film of the present disclosure, the refractive index of the low refractive index layer with respect to light having a wavelength of 500 nm is 1.65 or less, preferably 1.60 or less, more preferably 1.55 or less, and even more preferably 1.52 or less. In the multilayer film of the present disclosure, the refractive index of the low refractive index layer with respect to light having a wavelength of 500 nm is preferably 1.35 or more, and preferably 1.38 or more.

[0038] The magnesium fluoride-containing layer 14 according to the present disclosure will now be described. In the multilayer film according to the present disclosure, the thickness of the magnesium fluoride-containing layer 14 is 50 nm or more and 240 nm or less. If the thickness of the magnesium fluoride-containing layer 14 is less than 50 nm, the reflectance of the multilayer film may be too high. On the other hand, if the thickness of the magnesium fluoride-containing layer 14 exceeds 240 nm, the photocatalytic self-cleaning function may not be exhibited on the surface of the multilayer film. Furthermore, in the multilayer film according to the present disclosure, the refractive index of the magnesium fluoride-containing layer 14 for light with a wavelength of 500 nm is 1.65 or less, preferably 1.60 or less, more preferably 1.55 or less, and even more preferably 1.52 or less. In the multilayer film according to the present disclosure, the refractive index of the magnesium fluoride-containing layer 14 for light with a wavelength of 500 nm is preferably 1.35 or more, and preferably 1.38 or more. If the refractive index of the magnesium fluoride-containing layer 14 exceeds 1.65, the reflectance of the multilayer film may be too high.

[0039] As shown in FIG. 1B , in the multilayer film of the present disclosure, a region of the cerium oxide-containing layer 13 located at a position 8 nm or less from the interface between the cerium oxide-containing layer 13 and the magnesium fluoride-containing layer 14 is defined as region (B), and the oxygen deficiency rate of the cerium oxide in region (B) is defined as the oxygen deficiency rate (V Ｂ ), the oxygen deficiency rate (V ＢIn the multilayer film of the present disclosure, the region (A) excluding the region (B) is defined as a region (C), and the oxygen deficiency rate of cerium oxide in the region (C) is defined as the oxygen deficiency rate (V Ｃ ), the oxygen deficiency rate (V Ｃ ) is preferably 0% or more and 10% or less. Ｂ ) is the oxygen deficiency rate (V Ｃ ) is preferably greater than .

[0040] The content of magnesium fluoride in the total amount of materials constituting the magnesium fluoride-containing layer 14 is preferably 65 mass % or more. If it is within the above range, the ability to maintain hydrophilicity in a dark place is further improved.

[0041] 1A and 1B, the layer 15 containing silicon oxide may be disposed in place of the layer 14 containing magnesium fluoride. The layer 15 containing silicon oxide according to the present disclosure will be described below.

[0042] In the multilayer film of the present disclosure, the refractive index of the silicon oxide-containing layer 15 for light with a wavelength of 500 nm is 1.65 or less, preferably 1.60 or less, more preferably 1.55 or less, and even more preferably 1.52 or less. In the multilayer film of the present disclosure, the refractive index of the silicon oxide-containing layer 14 for light with a wavelength of 500 nm is preferably 1.35 or more, and more preferably 1.38 or more. If the refractive index of the silicon oxide-containing layer 15 exceeds 1.65, the reflectance of the multilayer film may become too high. In the multilayer film of the present disclosure, the silicon oxide-containing layer 15 has a thickness of 50 nm or more and 240 nm or less. If the thickness of the silicon oxide-containing layer 15 is less than 50 nm, the reflectance of the multilayer film may become too high. On the other hand, if the thickness of the silicon oxide-containing layer 15 exceeds 240 nm, the photocatalytic self-purification function may not be exhibited on the surface of the multilayer film.

[0043] As shown in FIG. 1B , in the multilayer film of the present disclosure, a region of the cerium oxide-containing layer 13 located at a position 8 nm or less from the interface between the cerium oxide-containing layer 13 and the silicon oxide-containing layer 15 is designated as region (B), and the oxygen deficiency rate of the cerium oxide in region (B) is designated as oxygen deficiency rate (V Ｂ ), the oxygen deficiency rate (V Ｂ In the multilayer film of the present disclosure, the region (A) excluding the region (B) is defined as a region (C), and the oxygen deficiency rate of cerium oxide in the region (C) is defined as the oxygen deficiency rate (V Ｃ ), the oxygen deficiency rate (V Ｃ ) is preferably 0% or more and 10% or less. Ｂ ) is the oxygen deficiency rate (V Ｃ ) is preferably greater than .

[0044] The silicon oxide-containing layer 15 is made of silicon oxide (SiO ｘ The silicon oxide content in the silicon oxide-containing layer 15 is preferably 65 mass % or more based on the entire silicon oxide-containing layer 15. When the silicon oxide content in the silicon oxide-containing layer 15 is within the above range, the ability to maintain hydrophilicity in a dark place is further improved.

[0045] The silicon oxide-containing layer 15 has a composition of silicon oxide of SiO ｘ Preferably, x is 1.5 or more and 2.0 or less. The composition of silicon oxide is SiO ｘ When the value of x is within the above range, the refractive index of the silicon oxide-containing layer 15 can be set to 1.65 or less. Also, a film with higher transparency in the wavelength range from visible light to near-infrared light can be obtained.

[0046] The silicon oxide-containing layer 15 is made of silicon oxide (SiO ｘIn addition to silicon oxide, the silicon oxide-containing layer 15 may contain aluminum oxide. In this case, the content of aluminum oxide in the silicon oxide-containing layer 15 is preferably 0.1 mass % or more and 10 mass % or less with respect to the entire silicon oxide-containing layer 15. When the silicon oxide-containing layer 15 contains 0.1 to 10 mass % aluminum oxide, the durability of the multilayer film, such as scratch resistance and moisture resistance, can be improved while maintaining the photocatalytic self-cleaning function of the multilayer film and its ability to maintain hydrophilicity in a dark place.

[0047] The silicon oxide-containing layer 15 is made of silicon oxide (SiO ｘ In addition to the silicon oxide-containing layer 15, the silicon oxide-containing layer 15 may contain cerium oxide. In this case, the content of cerium oxide in the silicon oxide-containing layer 15 is preferably 0.1 mass % or more and 10 mass % or less with respect to the entire silicon oxide-containing layer 15. When the silicon oxide-containing layer 15 contains 0.1 to 10 mass % of cerium oxide, the self-purification function by photocatalysis can be enhanced while maintaining the hydrophilicity of the multilayer film.

[0048] Second Embodiment The second embodiment relates to a multilayer film. The multilayer film of the second embodiment differs from the multilayer film of the first embodiment in that it is provided on another layer 12 provided on a substrate 11. Since the components other than the other layer 12 are as described above, a description thereof will be omitted. FIG. 2 is a schematic cross-sectional view showing a second embodiment of a multilayer film according to the present disclosure. In FIG. 2, the multilayer film according to the present disclosure is provided on another layer 12 provided on a substrate 11. That is, the second embodiment shows a configuration example in which the other layer 12 is formed on the substrate 11, a cerium oxide-containing layer 13 according to the present disclosure is further formed on the other layer 12, and a silicon oxide-containing layer 15 is further formed as a low refractive index layer on the cerium oxide-containing layer 13.

[0049] The substrate 11 and the layer 13 containing cerium oxide of the present disclosure are as described in the first embodiment.

[0050] 2, the magnesium fluoride-containing layer 14 described in the first embodiment may be disposed instead of all or part of the silicon oxide-containing layer 15. Furthermore, the cerium oxide-containing layer 13 of the present disclosure may be disposed directly on the substrate 11 without another layer 12 therebetween.

[0051] The other layer 12 may be a layer containing a metal, a fluoride, an oxide, a carbide, a sulfide, a halide, a nitride, or a complex anion compound (such as an oxynitride, an oxysulfide, an oxyhalide, an oxyfluoride, or an oxynitride). Specific examples of the other layer 12 include a metal layer containing an element such as aluminum (Al), chromium (Cr), gold (Au), silver (Ag), copper (Cu), silicon (Si), germanium (Ge), titanium (Ti), or nickel (Ni), and a layer containing magnesium fluoride (MgF ２ ), calcium fluoride (CaF ２ fluoride-containing layers such as silicon oxide (SiO ｘ ), aluminum oxide (Al ２ O ｘ ), yttrium oxide (Y ２ O ｘ ), zirconium oxide (ZrO ｘ ), hafnium oxide (HfO ｘ ), zinc oxide (ZnO ｘ ), tantalum oxide (Ta ２ O ｘ ), niobium oxide (Nb ２ O ｘ ), indium oxide (In ２ O ｘ ), tin oxide (SnO ｘ ), tungsten oxide (WO ｘ ), cerium oxide (CeO ｘ ), titanium oxide (TiO ｘ ), lanthanum titanate (La ｘ Ti ｙ O ｚ ), aluminum titanate (La ｘ Al ｙ O ｚ ), alumina-doped silicon dioxide (SiO ２ +Al ２ O ３), a layer containing an oxide such as ZnS, a layer containing a sulfide such as silicon nitride (Si ｘ N ｙ ), nitride-containing layers such as gallium nitride (GaN), carbide-containing layers such as tungsten carbide (WC), silicon oxynitride (SiO ｘ N ｙ ), lead titanium oxyfluoride (Pb ｗ Ti ｘ O ｙ F ｚ ) or other composite anion compounds such as the above. The other layer 12 may be a single layer or may be a multi-layer of two or more layers. When the other layer 12 is a multi-layer of two or more layers, the other layer 12 may be formed by combining a plurality of types of layers from among the layers exemplified above. The other layer 12 may also be a layer containing a mixture of two or more types of compounds contained in the layers exemplified above.

[0052] There are no particular limitations on the method for forming the other layer 12. Examples of methods that can be used to form the other layer 12 include dry film formation methods such as sputtering, vacuum deposition, and ion plating, and wet film formation methods such as dipping, coating, spraying, spin coating, bar coating, printing, and flow coating.

[0053] By adjusting the composition, refractive index, film thickness, number of layers, etc. of the other layers 12 according to the purpose and function, it is possible to form a multilayer film with specific functions added, such as an anti-reflection layer, a half mirror layer, a light absorbing layer, an alkali diffusion preventing layer, an adhesion layer, an antistatic layer, a heater layer, etc.

[0054] <Application Example> An application example of the present disclosure relates to an optical element. The optical element of the present disclosure is characterized by having the multilayer film described above. FIGS. 3 and 4 are schematic diagrams each showing the configuration of an embodiment of the optical element of the present disclosure. FIG. 3 shows a lens cover for a surveillance camera, in which the multilayer film of the present disclosure is formed on the surface of a dome-shaped resin substrate 21. FIG. 4 shows eyeglasses, in which the eyeglasses are composed of an eyeglass lens 31, which is an embodiment of the optical element of the present disclosure, and an eyeglass frame 32. The multilayer film of the present disclosure is formed on both surfaces of the eyeglass lens 31.

[0055] The multilayer film of the present disclosure can be used as an optical thin film, such as an anti-reflection film, various optical filter multilayer films, or optical mirror multilayer films. It can also be used for optical components, such as optical filters, optical lenses, light collecting lenses, optical films, optical prisms, eyeglass lenses, photographic lenses, surveillance camera covers, in-vehicle camera covers, in-vehicle sensor covers, vehicle door mirrors, glass plates, condenser lenses, display cover glass, touch panels, and various films, as well as covers for protecting the optical components. Furthermore, by coating the surfaces of the substrate 11 other than the surfaces on which the above-described layers are to be formed with layers having compositions, refractive indices, film thicknesses, and number of layers according to the purpose and function, optical components with specific functions, such as mirror layers, half-mirror layers, light-absorbing layers, transparent heater layers, and anti-reflection layers, can be produced.

[0056] Third Embodiment The third embodiment relates to a method for manufacturing a multilayer film. The method for manufacturing a multilayer film of the present disclosure includes: a step (A) of forming a cerium oxide-containing layer on a substrate by vacuum deposition, either directly or via another layer; and a step (B) of forming a low refractive index layer on the cerium oxide-containing layer by vacuum deposition, either directly or via another layer; the low refractive index layer has a layer containing silicon oxide or a layer containing magnesium fluoride; the cerium oxide-containing layer contains cerium oxide having a cubic polycrystalline structure and a columnar structure; the cerium oxide-containing layer has a film thickness of 85 nm to 800 nm; the entire cerium oxide-containing layer is defined as region (A), and the oxygen deficiency rate of the cerium oxide in region (A) is defined as oxygen deficiency rate (V Ａ ), the oxygen deficiency rate (V Ａ ) is 0.05% or more and 10% or less, and the film thickness of the low refractive index layer is 50 nm or more and 240 nm or less. The following explanation will be given. The multilayer film is as described above, so the explanation will be omitted.

[0057] The cerium oxide-containing layer 13 formed in step (A) contains cerium oxide having a cubic polycrystalline structure with a specific oxygen deficiency rate, and the thickness of the cerium oxide-containing layer 13 formed in step (A) is 85 nm or more and 800 nm or less. The thickness of the silicon oxide-containing layer 14 or the magnesium fluoride-containing layer 15 formed in step (B) is 50 nm or more and 240 nm or less. The refractive index of the silicon oxide-containing layer 14 and the magnesium fluoride-containing layer 15 formed in step (B) for light with a wavelength of 500 nm is 1.65 or less.

[0058] The method for producing a multilayer film of the present disclosure includes a step (A) of forming a cerium oxide-containing layer on a substrate by vacuum deposition, either directly or via another layer, and a step (B) of forming a silicon oxide-containing layer or a magnesium fluoride-containing layer on the cerium oxide-containing layer by vacuum deposition, either directly or via another layer. The temperature of the substrate during vacuum deposition is preferably a temperature at which cerium oxide crystallizes. Although the temperature depends on the heat resistance temperature of the substrate used and other film formation conditions, it can usually be selected from a range of 0°C to 500°C.

[0059] The evaporation method used in vacuum deposition is not limited as long as it can evaporate the film-forming material. For example, evaporation means such as an electron gun, resistance heating, or laser can be used. Furthermore, ion-assisted or plasma-assisted evaporation can be used in combination with the evaporation means as needed.

[0060] In the method for producing a multilayer film according to the present disclosure, water molecules (H ２ O) partial pressure and oxygen molecules (O ２ ) and the total partial pressure is 2 × 10 －２ Pa or less, and －４ It is more preferable that the pressure is not more than 1 Pa. In addition, the water molecules (H ２ The sum of the partial pressure of oxygen species (in the present invention, oxygen species refers to oxygen atoms, oxygen molecules, and oxygen ions) is 2×10 on average. －２ Pa or less, and the average is 7.8 × 10－３ It is more preferable that the viscosity is 0.05 Pa or less.

[0061] The vacuum level in the deposition device is the same (for example, vacuum level 7×10 －４ Even if the vapor deposition apparatus is at a vacuum pressure of 100 Pa, the partial pressure ratio of gases remaining in the vacuum atmosphere can vary significantly depending on the conditions inside the vapor deposition apparatus, such as the degree of contamination, whether there is a small vacuum leak or not, and whether prior baking has been performed. As a result, the partial pressure of gases before and during deposition of the cerium oxide-containing layer can change, which can affect the characteristics of the resulting cerium oxide-containing layer 13. For example, the partial pressure of water molecules can be reduced by cleaning the area around the evaporation source and walls of the apparatus before deposition to reduce the amount of adsorbed substances (such as water molecules).

[0062] Furthermore, when using pure copper hearth liners, which are the most commonly used for film-forming materials deposited with an electron gun, the high thermal and electrical conductivity results in significant energy loss, and evaporation is not possible unless the electron gun output is increased, resulting in a higher temperature around the evaporation source. This can result in a greater amount of adsorbed gas (such as water molecules) being desorbed. Using a molybdenum or tantalum hearth liner instead of pure copper allows for a lower electron gun output during film deposition. Furthermore, molybdenum and other materials have the advantage of containing less gas than regular oxygen-free copper.

[0063] If a cryochiller is installed in addition to a rotary pump and a diffusion pump in the vacuum exhaust system, the partial pressure of water molecules in the atmosphere is likely to decrease. Also, if the area near the wall of the vacuum evaporation system is heated by a heater (wall heater) that heats the wall of the vacuum evaporation system, or if baking is performed in advance, the partial pressure of water molecules in the atmosphere is likely to decrease.

[0064] Before starting the deposition process, it is important to check that the deposition equipment is leak-free to stabilize the oxygen partial pressure inside the equipment, because even a small leak can cause the surrounding air to flow into the equipment, increasing the oxygen partial pressure in the atmosphere and affecting the properties of the resulting cerium oxide-containing layer.

[0065] When heating a substrate, there is a time lag until the actual temperature of the substrate reaches the same temperature as the temperature measured by the thermocouple. Depending on the substrate heat setting temperature, the material of the substrate holder, and the thickness of the substrate, it is necessary to wait 10 to 20 minutes after the thermocouple temperature reaches the set temperature. Furthermore, since a certain amount of moisture is adsorbed to the substrate, sufficient heating of the substrate can desorb more of the moisture adsorbed to the substrate before film formation. During film formation, radiant heat energy from the evaporation source is also added, making it easier for moisture to desorb from the substrate. Therefore, when heating the substrate, the film formation process should begin at least 15 minutes after the thermocouple measuring the substrate temperature indicates a temperature within ±2°C of the set temperature.

[0066] When placing a substrate in a deposition apparatus, the substrate is set in the apparatus using a jig, usually called a holder or holder. Using a clean, washed jig, and a material with low gas adsorption and desorption, such as SUS316LN, can reduce the amount of gas released during film formation, such as moisture. On the other hand, dirty jigs, porous materials, jigs made of brass or synthetic resin, or zinc-plated jigs release a large amount of gas, making it easier for gas components such as moisture and oxygen to be released from the jig during film formation.

[0067] The reason for cleaning the inner wall surface, installing a cryochiller, checking for leaks, controlling the substrate heating time, selecting the jig material, etc. is that when forming the layer 13 containing cerium oxide, the same gas introduction conditions (for example, no gas introduction at all, or an oxygen introduction amount of 1×10 －２ Even if the temperature is lower than the specified value (when the pressure is 100 Pa), the partial pressure of oxygen molecules and water molecules in the atmosphere will be different. This may affect the oxygen deficiency rate of the resulting cerium oxide-containing layer. Therefore, if these steps are not taken, a multilayer film including the cerium oxide-containing layer 13 of the present disclosure may not be obtained even if other film formation conditions are the same as those in the examples of the present application.

[0068] In the method for producing a multilayer film according to the present disclosure, the entire layer containing cerium oxide is designated as region (A), and the oxygen deficiency rate of cerium oxide in region (A) is determined as the oxygen deficiency rate (V Ａ ), the oxygen deficiency rate (V Ａ) is 0.05% or more and 10% or less. In the method for producing a multilayer film according to the present disclosure, as shown in FIG. 1B , a region of the cerium oxide-containing layer located at a position 8 nm or less from the interface between the cerium oxide-containing layer and the low refractive index layer (the layer containing magnesium fluoride or the layer containing silicon oxide) is designated as region (B), and the oxygen deficiency rate of the cerium oxide in region (B) is defined as the oxygen deficiency rate (V Ｂ ), the oxygen deficiency rate (V Ｂ ) is 0.5% or more and 30% or less, and the region (A) excluding the region (B) is defined as a region (C), and the oxygen deficiency rate of cerium oxide in the region (C) is defined as the oxygen deficiency rate (V Ｃ ), the oxygen deficiency rate (V Ｃ ) is 0% or more and 10% or less, and the oxygen deficiency rate (V Ｂ ) is the oxygen deficiency rate (V Ｃ ) is preferably greater than .

[0069] The multilayer film of the present disclosure can be suitably produced by the above method.

[0070] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples in any way.

[0071] The materials used for producing and evaluating the multilayer films in the examples are listed below.

[0072] (Substrate) Flat plates of the materials listed below were used as substrates. When the substrate temperature during vapor deposition was 100°C or higher, substrates other than those made of resin were used. For other substrate temperatures, all of the substrates listed below were used. The silicon and sodium chloride substrates were used for analyzing the oxygen deficiency rate and measuring the film thickness using an electron microscope. Borosilicate glass: 3 mm thick Synthetic quartz: 3 mm thick Polycarbonate resin: 2 mm thick Polymethyl methacrylate resin: 2 mm thick Silicon: 1 mm thick Sodium chloride: 2 mm thick (Film-forming materials) The materials listed below were used. Ce: granular, purity 99.9% CeO ２ : Cylindrical, purity 99.9% La ２ O ３ : Cylindrical, purity 99.9% Sm ２ O３ : Cylindrical, purity 99.9% SiO: Granular, purity 99.9% SiO ２ : Granular, purity 99.9% ・Al ２ O ３ : Granular, purity 99.95% ・MgF ２ : Granular, purity 99.9% ・Ti ３ O ５ : Granular, purity 99.9% TaO: Granular, purity 99.9% Cr: Granular, purity 99.9% (Ion-assisted film deposition gas) O ２ : Gas, purity 99.999% Ar: Gas, purity 99.999% (Gas for checking vacuum leaks) He: Gas, purity 99.9999% (Etching gas used during measurement) Ar: Gas, purity 99.9999% (Reagent, etc.) Pure water: JIS K0557 A4 Stearic acid: JIS K8585 special grade, purity 99.9% Heptane: JIS K9701 special grade, purity 99.9%

[0073] (Fabrication of Multilayer Films) The film-forming method and conditions common to the examples and comparative examples for fabricating multilayer films are described below. A vacuum deposition apparatus (dome diameter Φ 1300 mm, deposition distance 1100 mm) was used as the deposition apparatus. To obtain identical multilayer films on all substrates placed in the deposition apparatus, the temperature distribution, deposition rate of the film-forming material, and ion-assisted incident ion distribution were adjusted to be identical for all substrates placed on the domes and the monitor substrate. To achieve this adjustment, measurements using Faraday cups, thermocouples, and film thickness measurement devices were repeatedly performed, and the positioning of correction plates, sheathed heaters, and heater output were optimized. Prior to film formation, the area around the evaporation source, the domes, and the walls of the apparatus were polished and wiped clean with an organic solvent (isohexane).

[0074] Next, the film-forming materials and various clean substrates were placed in a vacuum deposition apparatus. The deposition materials to be deposited using an electron gun were placed in a cleaned and degassed molybdenum hearth liner and evaporated. A cleaned and degassed SUS316LN substrate holder was used. Since analysis and analytical evaluation may be difficult if the test specimen obtained is only a multilayer film, various substrates were placed in a mechanism that allowed the substrate to be replaced for each layer, so that not only multilayer films but also single-layer films for analysis and analytical evaluation could be obtained simultaneously.

[0075] Thereafter, the chamber was evacuated until the vacuum level reached the partial pressure of water molecules and oxygen molecules required to start film formation. A cryochiller (PFC-1102HC, manufactured by Polycold) was used in addition to a rotary pump and a diffusion pump as a vacuum pumping device. Before starting the film formation process, it was confirmed that there were almost no leaks in the vacuum deposition device using He gas for leak detection and a quadrupole mass spectrometer (Qulee with YTP-H, manufactured by ULVAC) as a leak detector. The confirmation items included that the mass spectrometer did not detect He gas for leak detection and that the ratio of nitrogen molecules (mass number 28) to oxygen molecules (mass number 32) was the same as the ratio in the atmosphere (N ２ :O ２ It was confirmed that this is clearly different from the previous example (79%:21%).

[0076] Before starting deposition of the cerium oxide-containing layer 13, the partial pressures of water molecules and oxygen molecules in the atmosphere were measured and calculated using an ionization vacuum gauge and a quadrupole mass spectrometer. During deposition of the cerium oxide-containing layer 13 in region (B), the partial pressures of water molecules and oxygen species (oxygen atoms, oxygen molecules, and oxygen ions) were measured and calculated every second using an ionization vacuum gauge and a quadrupole mass spectrometer, and these partial pressures were summed and averaged to calculate the average partial pressure during deposition in region (B). The substrate temperature during deposition was −15° C. or higher and 600° C. or lower. The deposition process was started 15 minutes or more after the substrate temperature reached the set temperature ±2° C.

[0077] Thereafter, the film-forming materials were vacuum-deposited on the set substrate to form multilayer films as listed in Tables 1-1 to 1-4, to obtain test specimens. Unless otherwise specified, the cerium oxide-containing layer was deposited at a deposition rate of 0.5 nm / s. The dome rotation speed during deposition of each layer was 20 rpm. CeO ２ +Al ２ O ３ and SiO ２ +Al ２ O ３ The two-component film was formed by a binary evaporation method in which two types of film-forming materials were placed on two heating sources and evaporated simultaneously. ２ When SiO was used as the film-forming material, a tantalum boat and resistance heating were used as the heating source.

[0078] In each of Examples 1 to 66 and Comparative Examples 1 to 22, there was essentially no difference between the multilayer films obtained by changing the type of substrate, and therefore only one example is shown in Tables 1-1 to 1-4. In Tables 1-1 to 1-4, "crystalline" means that the cerium oxide-containing layer contains cerium oxide having a cubic polycrystalline structure, and "amorphous" means that the cerium oxide-containing layer does not contain cerium oxide having a cubic polycrystalline structure. In Tables 1-1 to 1-4, "columnar" means that the cerium oxide-containing layer contains cerium oxide having a columnar structure, and "non-columnar" means that the cerium oxide-containing layer does not contain cerium oxide having a columnar structure.

[0079] The individual conditions for producing the multilayer film in each example and comparative example are described below. [Example 1] The vacuum deposition apparatus was set to a substrate temperature of 400°C and a wall heater of 100°C, and then evacuated. When 15 minutes or more had elapsed after the substrate temperature reached 400±2°C and before the film formation process for the cerium oxide-containing layer was started, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.53×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF２ Using MgF ２ During the film formation in the region 8 nm from the surface of the cerium oxide-containing layer (region (B): the region of the cerium oxide-containing layer located 8 nm or less from the interface between the cerium oxide-containing layer and the silicon oxide-containing layer or the magnesium fluoride-containing layer), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 3.11 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0080] Example 2 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 105°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.50×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.06 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0081] Example 3 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 110°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.50×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using the above-mentioned method. Subsequently, SiO and Al were used as film-forming materials on the layer. ２ O ３ Using SiO ２ +Al２ During the film formation of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total partial pressure of water molecules and oxygen species was 3.05 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0082] Example 4 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 115°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.49×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.03 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0083] Example 5 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 140°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.48×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 3.00 × 10 on average. －３The other film formation conditions were as described in (Fabrication of multilayer film).

[0084] Example 6 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 120°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.47×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO and CeO as film-forming materials. ２ Using SiO ２ + CeO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.98 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0085] Example 7 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 125°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.45×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.96 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0086] Example 8 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 130°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.45×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.94 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0087] Example 9 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 135°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.44×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using the above-mentioned method. Subsequently, SiO and Al were used as film-forming materials on the layer. ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total partial pressure of water molecules and oxygen species was 2.92 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0088] Example 10 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 140°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.39×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.84 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0089] Example 11 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 145°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.38×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.80 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0090] Example 12 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 150°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.37×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO and CeO as film-forming materials. ２ Using SiO ２ + CeO ２ During the film formation in the region (B) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 2.78 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0091] Example 13 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 155°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.34×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.73 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0092] Example 14 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.33×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 2.71 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0093] Example 15 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 165°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.26×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using the above-mentioned method. Subsequently, SiO and Al were used as film-forming materials on the layer. ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 2.57 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0094] Example 16 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 150°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.71×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed at a deposition rate of 0.7 nm / s using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 4.89 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0095] Example 17 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 175°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.78×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed thereon at a film formation rate of 1.0 nm / s using SiO as a film forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 7.23 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0096] Example 18 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 180°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.96×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed at a deposition rate of 1.5 nm / s using a cerium oxide film. ２ Using SiO ２ + CeO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 1.20 × 10 －２ The other film formation conditions were as described in (Fabrication of multilayer film).

[0097] Example 19 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 2.87×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 5.84 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0098] Example 20 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 2.83×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 5.76 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0099] Example 21 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 200°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.03×10 －４ Then, Sm was applied as a film-forming material to various substrates. ２ O ３ and CeO ２ A layer containing cerium oxide was formed at a deposition rate of 0.65 nm / s using a SiO 2 and Al 2 O 3 film-forming material. ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total partial pressure of water molecules and oxygen species was 2.71 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0100] Example 22 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 2.83×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 5.76 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0101] Example 23 A vacuum deposition apparatus was evacuated with the substrate temperature set to 250°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 250±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.51×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ The cerium oxide-containing layer was formed using an RF ion source. The ion-assisted deposition conditions were an acceleration voltage of 700 V, an acceleration current of 700 mA, and O ２ The gas flow rate was 60 sscm. When forming the surface 8 nm of the layer containing cerium oxide (region (B)), the ion gun and gas introduction were stopped. When forming the surface 8 nm of the layer containing cerium oxide (region (B)), the ion gun and gas introduction were stopped. Subsequently, MgF ２ Using MgF ２During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.08 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0102] Example 24 A vacuum deposition apparatus was evacuated with the substrate temperature set to 350°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 350±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.49 × 10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ When forming the layer containing cerium oxide, oxygen was introduced by auto pressure control (APC). The amount of oxygen gas introduced was 1.9 × 10 －２ The pressure was Pa. In addition, when forming the surface 8 nm of the layer containing cerium oxide (region (B)), the film was formed 1 minute after the introduction of oxygen gas was stopped. Then, SiO was used as a film forming material and SiO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.03 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0103] Example 25 A vacuum deposition apparatus was evacuated with the substrate temperature set to 300°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 300±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.45×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２The cerium oxide-containing layer was formed using an RF ion source. The ion-assisted deposition conditions were an acceleration voltage of 700 V, an acceleration current of 700 mA, and O ２ The gas flow rate was 35 sccm, and the Ar gas flow rate was 7 sccm. When forming the surface 8 nm of the layer containing cerium oxide (region (B)), the ion gun and gas introduction were stopped. Then, SiO ２ and Al ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm (region (B)) of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 2.95 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0104] Example 26 A vacuum deposition apparatus was evacuated with the substrate temperature set to 300°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 300±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.39×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ The cerium oxide-containing layer was formed using an RF ion source. The ion-assisted deposition conditions were an acceleration voltage of 700 V, an acceleration current of 700 mA, and O ２ The gas flow rate was 30 sccm, and the Ar gas flow rate was 10 sccm. When forming the surface 8 nm of the layer containing cerium oxide (region (B)), the ion gun and gas introduction were stopped. Then, SiO was used as a film forming material to form a SiO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.83 × 10－３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0105] Example 27 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 2.45×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed at a deposition rate of 2.0 nm / s using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 1.99 × 10 －２ The other film formation conditions were as described in (Fabrication of multilayer film).

[0106] Example 28 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 2.87×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 5.84 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0107] Example 29 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.51×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.08 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0108] Example 30 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.51×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.08 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0109] Example 31 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.50×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using the above-mentioned method. Subsequently, SiO and Al were used as film-forming materials on the layer. ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total partial pressure of water molecules and oxygen species was 3.05 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0110] Example 32 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.47×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.98 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0111] Example 33 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.45×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.95 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0112] Example 34 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.42 × 10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO and CeO as film-forming materials. ２ Using SiO ２ + CeO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.89 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0113] Example 35 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.38×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.80 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0114] Example 36 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.37×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.80 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0115] Example 37 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.31×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using the above-mentioned method. Subsequently, SiO and Al were used as film-forming materials on the layer. ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm of the layer containing cerium oxide (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 2.66 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0116] Example 38 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 200°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 9.84×10 －５ Then, La was applied to various substrates as a film-forming material. ２ O ３ and CeO ２ A layer containing cerium oxide was formed at a deposition rate of 0.7 nm / s using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.80 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0117] Example 39 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 2.87×10 －４ The film-forming materials were Ce and CeO. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 5.84 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0118] Example 40 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.27×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO and CeO as film-forming materials. ２ Using SiO ２ + CeO ２ During the film formation in the region (region (B)) 8 nm from the surface of the layer containing cerium oxide, the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 2.59 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0119] Example 41 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.51×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.08 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0120] Example 42 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.37×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO and CeO as film-forming materials. ２ Using SiO ２ + CeO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.79 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0121] Example 43 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.51×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.08 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0122] Example 44 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.45×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.94 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0123] Example 45 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.51×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using the above-mentioned method. Subsequently, SiO and Al were used as film-forming materials on the layer. ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm (region (B)) of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 3.08 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0124] Example 46 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.45×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.95 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0125] Example 47 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.51×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.07 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0126] Example 48 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.41×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO and CeO as film-forming materials. ２ Using SiO ２ + CeO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.87 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0127] Example 49 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.51×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.07 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0128] Example 50 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.37×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 2.78 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0129] Example 51 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.51×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using a film-forming material, SiO ２ and Al ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm (region (B)) of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 3.08 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0130] Example 52 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.45×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.95 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0131] Example 53 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.50×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using a film-forming material, SiO ２ Using SiO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.05 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0132] Example 54 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.44×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using a film-forming material, SiO ２ and CeO ２ Using SiO ２ + CeO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.94 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0133] Example 55 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.37×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.79 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0134] Example 56 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 1.22 × 10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (region (B)) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 2.49 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0135] Example 57 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 2.08×10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed at a deposition rate of 3.0 nm / s using a film-forming material containing SiO and Al. ２ O ３ Using SiO ２ +Al ２ During the film formation of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total partial pressure of water molecules and oxygen species was 2.54 × 10 －２ The other film formation conditions were as described in (Fabrication of multilayer film).

[0136] Example 58 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 160°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured and found to be 2.87×10 －４ The film-forming materials were Ce and CeO. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 3.51 × 10 on average. －２ The other film formation conditions were as described in (Fabrication of multilayer film).

[0137] Example 59 The vacuum deposition apparatus was evacuated with the substrate heater turned off and the wall heater set to 50°C. The substrate temperature before film formation was 28°C. Before starting the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.22 x 10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the surface 8 nm (region (B)) of the layer containing cerium oxide, the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 2.48 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0138] Example 60 The vacuum deposition apparatus was evacuated with the substrate heater turned off and the wall heater set to 50°C. The substrate temperature before film formation was 31°C. Before starting the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.45 x 10 －４ On various substrates, CeO was used as a film-forming material. ２ A layer containing cerium oxide was formed using SiO and CeO as film-forming materials. ２ Using SiO ２ + CeO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 2.95 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0139] Example 61 A vacuum deposition apparatus was evacuated with the substrate temperature set to 100°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 100±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 9.54×10 －５Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 1.94 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0140] Example 62 A vacuum deposition apparatus was evacuated with the substrate temperature set to 100°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 100±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.36×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２ During the film formation in the region (B) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 2.78 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0141] Example 63 A vacuum deposition apparatus was evacuated with the substrate temperature set to 270°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 270±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked. －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A layer containing cerium oxide was formed using the above-mentioned method. Subsequently, SiO and Al were used as film-forming materials on the layer. ２ O ３ Using SiO２ +Al ２ O ３ During the film formation in the region (B) 8 nm from the surface of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen species was 5.84 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0142] Example 64 A vacuum deposition apparatus was evacuated with the substrate temperature set to 270°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 270±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured. The total partial pressure was 1.84×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed at a deposition rate of 1.0 nm / s using a film-forming material, MgF ２ Using MgF ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 7.50 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0143] Example 65 A vacuum deposition apparatus was evacuated with the substrate temperature set to 500°C and the wall heater set to 200°C. When 15 minutes or more had elapsed since the substrate temperature reached 500±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked. －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed using SiO as a film-forming material. ２During the film formation in the region (region (B)) 8 nm from the surface of the layer containing cerium oxide, the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 2.79 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0144] Example 66 A vacuum deposition apparatus was evacuated with the substrate temperature set to 500°C and the wall heater set to 200°C. When 15 minutes or more had elapsed since the substrate temperature reached 500±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked. －４ Then, Y was applied as a film-forming material to various substrates. ２ O ３ and CeO ２ A layer containing cerium oxide was formed at a deposition rate of 0.7 nm / s using a cerium oxide film. ２ Using SiO ２ + CeO ２ During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 8.18 × 10 －３ The other film formation conditions were as described in (Fabrication of multilayer film).

[0145] Comparative Example 1 The vacuum deposition apparatus was evacuated with the substrate temperature set to 300° C. and the wall heater set to 50° C. Before starting the film formation process of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 8.20×10 －３ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed at a deposition rate of 0.2 nm / s using a SiO 2 film forming material. ２ Using SiO ２During the film formation in the region (B) of the surface 8 nm of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen species was 6.68 × 10 －２ The other film formation conditions were as described in (Fabrication of multilayer film).

[0146] Comparative Example 2 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400° C. and the wall heater set to 100° C. Before starting the film formation process of the cerium oxide-containing layer, the total value of the partial pressure of water molecules and the partial pressure of oxygen molecules was checked and found to be 6.15×10 －３ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed at a deposition rate of 0.2 nm / s using a SiO 2 film forming material. ２ and CeO ２ Using SiO ２ + CeO ２ During the film formation in the region (region (B)) 8 nm from the surface of the layer containing cerium oxide, the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 5.01 × 10 on average. －２ The other film formation conditions were as described in (Fabrication of multilayer film).

[0147] Comparative Example 3 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400° C. and the wall heater set to 100° C. Before starting the film formation process of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.53×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ The cerium oxide-containing layer was formed at a deposition rate of 0.2 nm / s using an auto pressure control (APC) device under a vacuum of 1.8×10 －２ O to become Pa ２ During the film formation of the surface 8 nm of the layer containing cerium oxide (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 1.80 × 10 on average. －２Subsequently, MgF was applied thereon as a film-forming material. ２ Using MgF ２ The other film forming conditions were as described in (Fabrication of Multilayer Film).

[0148] Comparative Example 4 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400° C. and the wall heater set to 100° C. Before starting the film formation process of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.53×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ A cerium oxide-containing layer was formed at a deposition rate of 0.2 nm / s using a fluorine-containing ion source. When depositing the surface 8 nm of the cerium oxide-containing layer (region (B)), ion assistance was performed using an RF ion source. The ion assistance conditions were an acceleration voltage of 700 V, an acceleration current of 700 mA, and O. ２ The gas flow rate was 50 sscm. During the deposition of the surface 8 nm of the layer containing cerium oxide (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 3.11 × 10 on average. －３ Subsequently, SiO was used as a film-forming material on the film. ２ The other film forming conditions were as described in (Fabrication of Multilayer Film).

[0149] Comparative Example 5 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400° C. and the wall heater set to 150° C. Before starting the film formation process of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 2.91×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A cerium oxide-containing layer was formed at a deposition rate of 0.9 nm / s using a cerium oxide-containing film. When depositing the surface 8 nm of the cerium oxide-containing layer (region (B)), the deposition rate was changed to 0.1 nm / s. During the deposition of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 1.07 × 10 on average. －２Subsequently, SiO and Al were deposited thereon as film-forming materials. ２ O ３ Using SiO ２ +Al ２ An O3 film (low refractive index layer) was formed on the substrate, and a multilayer film was fabricated. Other film formation conditions were as described in (Fabrication of multilayer film).

[0150] Comparative Example 6 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400° C. and the wall heater set to 150° C. Before starting the film formation process of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 2.87×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A cerium oxide-containing layer was formed at a deposition rate of 1.0 nm / s using a cerium oxide-containing film. When depositing the surface 8 nm of the cerium oxide-containing layer (region (B)), the deposition rate was changed to 0.1 nm / s. During the deposition of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 1.17 × 10 on average. －２ Subsequently, MgF was applied thereon as a film-forming material. ２ Using MgF ２ The other film forming conditions were as described in (Fabrication of Multilayer Film).

[0151] Comparative Example 7 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400° C. and the wall heater set to 150° C. Before starting the film formation process of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 2.83×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A cerium oxide-containing layer was formed at a deposition rate of 1.1 nm / s using a cerium oxide-containing film. When depositing the surface 8 nm of the cerium oxide-containing layer (region (B)), the deposition rate was changed to 0.1 nm / s. During the deposition of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 1.27 × 10 on average. －２Subsequently, SiO was used as a film-forming material on the film. ２ The other film forming conditions were as described in (Fabrication of Multilayer Film).

[0152] Comparative Example 8 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400° C. and the wall heater set to 150° C. Before starting the film formation process of the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 2.79×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A cerium oxide-containing layer was formed at a deposition rate of 1.2 nm / s using a cerium oxide-containing film. When depositing the surface 8 nm of the cerium oxide-containing layer (region (B)), the deposition rate was changed to 0.1 nm / s. During the deposition of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 1.36 × 10 on average. －２ Subsequently, SiO and CeO were deposited thereon as film-forming materials. ２ Using SiO ２ + CeO ２ The other film forming conditions were as described in (Fabrication of Multilayer Film).

[0153] Comparative Example 9 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400° C. and the wall heater set to 150° C. Before starting the film formation process of the cerium oxide-containing layer, the total value of the partial pressure of water molecules and the partial pressure of oxygen molecules was checked and found to be 2.75×10 －４ Then, Ce and CeO were applied as film-forming materials to various substrates. ２ A cerium oxide-containing layer was formed at a deposition rate of 1.4 nm / s using a cerium oxide-containing film. When forming the surface 8 nm of the cerium oxide-containing layer (region (B)), the deposition rate was changed to 0.1 nm / s. During the deposition of the surface 8 nm of the cerium oxide-containing layer (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 1.57 × 10 on average. －２ Subsequently, MgF was applied thereon as a film-forming material. ２Using MgF ２ The other film forming conditions were as described in (Fabrication of Multilayer Film).

[0154] Comparative Example 10 A vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.53×10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ When forming the layer containing cerium oxide, oxygen was introduced by APC. The amount of oxygen gas introduced was 5.0 × 10 －２ During the film formation of the surface 8 nm of the layer containing cerium oxide (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species is 5.00 × 10 on average. －２ Subsequently, SiO was used as a film-forming material on the film. ２ The other film forming conditions were as described in (Fabrication of Multilayer Film).

[0155] Comparative Example 11 A vacuum deposition apparatus was evacuated with the substrate temperature set to 250°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 250±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.52 × 10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ The cerium oxide-containing layer was formed using an RF ion source. The ion-assisted deposition was performed under the conditions of an acceleration voltage of 700 V, an acceleration current of 700 mA, and O ２ The gas flow rate was 80 sscm. During the deposition of the surface 8 nm of the layer containing cerium oxide (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 3.09 × 10 on average.－２ Subsequently, SiO and Al were deposited thereon as film-forming materials. ２ O ３ Using SiO ２ +Al ２ An O3 film (low refractive index layer) was formed on the substrate, and a multilayer film was fabricated. Other film formation conditions were as described in (Fabrication of multilayer film).

[0156] Comparative Example 12 A vacuum deposition apparatus was evacuated with the substrate temperature set to 250°C and the wall heater set to 100°C. When 15 minutes or more had elapsed since the substrate temperature reached 250±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 1.52 × 10 －４ Then, CeO was applied as a film-forming material to various substrates. ２ The cerium oxide-containing layer was formed using an RF ion source. The ion-assisted deposition was performed under the conditions of an acceleration voltage of 700 V, an acceleration current of 700 mA, and O ２ The gas flow rate was 70 sscm. During the deposition of the surface 8 nm of the layer containing cerium oxide (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 3.02 × 10 on average. －２ Then, MgF was added as a film-forming material. ２ Using MgF ２ The other film forming conditions were as described in (Fabrication of Multilayer Film).

[0157] Comparative Example 13 The substrate temperature was changed to 600° C. so that a layer containing cerium oxide with a non-columnar structure could be obtained instead of the layer containing cerium oxide with a columnar structure in Example 34. Before starting the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.51×10 －４ The deposition of the cerium oxide-containing layer was performed by ion-assisted deposition using an RF ion source. The ion-assisted deposition conditions were an acceleration voltage of 900 V, an acceleration current of 1000 mA, and O ２The gas flow rate was 6 sccm, and the Ar gas flow rate was 34 sccm. When forming the surface 8 nm of the layer containing cerium oxide (region (B)), the O ion source was ２ The gas flow rate was changed to 2 sccm, and the Ar gas flow rate was changed to 38 sccm. During the deposition of the cerium oxide-containing layer in the top 8 nm region (region (B)), the total partial pressure of water molecules and oxygen species was 3.08 × 10 on average. －３ The temperature was 0.05 Pa. Except for this, a multilayer film was prepared in the same manner as in Example 34.

[0158] Comparative Example 14 The substrate temperature was changed to 600° C. so that a layer containing cerium oxide with a non-columnar structure could be obtained instead of the layer containing cerium oxide with a columnar structure in Example 36. Before starting the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked and found to be 1.51×10 －４ The cerium oxide-containing layer was formed by ion-assisted deposition using an RF ion source. The ion-assisted deposition conditions were an acceleration voltage of 1000 V, an acceleration current of 1000 mA, and O ２ The gas flow rate was 3 sccm, and the Ar gas flow rate was 37 sccm. When forming the surface 8 nm of the layer containing cerium oxide (region (B)), the O ion source ２ The gas flow rate was changed to 0 sccm, and the Ar gas flow rate was changed to 40 sccm. During the deposition of the surface 8 nm of the layer containing cerium oxide (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 3.07 × 10 on average. －３ The temperature was 100 Pa. Other than that, a multilayer film was prepared in the same manner as in Example 36.

[0159] [Comparative Example 15] Cubic polycrystalline CeO of Example 19 ２ Instead of the layer, amorphous CeO ２ To obtain a layer containing cerium oxide, the substrate temperature was changed to −18° C., and the wall heater was turned off before evacuation and deposition. Before starting the deposition process of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen molecules was checked and found to be 2.38×10 －５During the deposition of the layer containing cerium oxide in the surface 8 nm (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 4.84 × 10 on average. －４ The temperature was 100 Pa. Other than that, a multilayer film was prepared in the same manner as in Example 19.

[0160] [Comparative Example 16] Cubic polycrystalline CeO of Example 20 ２ Instead of the layer, amorphous CeO ２ To obtain a layer containing cerium oxide, the substrate temperature was changed to −18° C., and the wall heater was turned off before evacuation and deposition. Before starting the deposition process of the layer containing cerium oxide, the total partial pressure of water molecules and oxygen molecules was checked and found to be 2.87×10 －４ During the deposition of the layer containing cerium oxide in the surface 8 nm (region (B)), the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 5.84 × 10 on average. －３ The temperature was 1000 Pa. Other than that, a multilayer film was prepared in the same manner as in Example 20.

[0161] [Comparative Example 17] SiO of Example 24 ２ Instead of forming a thin film, a SiO film was formed at a deposition rate of 1.3 nm / s using SiO. The SiO film has a high refractive index and a large amount of light loss due to light absorption, making it unsuitable as an optical thin film.

[0162] Comparative Example 18 The vacuum deposition apparatus was evacuated with the substrate temperature set to 400°C and the wall heater set to 180°C. When 15 minutes or more had elapsed since the substrate temperature reached 400±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked. －４ Then, CeO was applied as a film-forming material to various substrates. ２ A layer containing cerium oxide was formed on the film using a film-forming material Y. ２ O ３ Using Y ２ O ３During the film formation in the top 8 nm region (region (B)) of the cerium oxide-containing layer, the total value of the partial pressure of water molecules and the partial pressure of oxygen species was 5.84 × 10 on average. －３ The other film formation conditions were as described in (Fabrication of multilayer film). ２ O ３ Since the refractive index was higher than that of the film, it was not suitable for use as an optical component.

[0163] (Evaluation of oxygen deficiency rate) The obtained multilayer film test piece was introduced into an X-ray photoelectron spectrometer (ESCA-300 manufactured by Scienta) and evacuated to a high vacuum. The thin film above the cerium oxide-containing layer 13 of the multilayer film was removed by etching with argon ions. Subsequently, XPS spectrum measurement of the Ce 3d orbital and etching with argon ions were repeated. The analysis area of ​​the multilayer film was changed and a total of three locations were analyzed. From the obtained results, the oxygen deficiency rate (V Ａ ), oxygen deficiency rate (V Ｂ ), oxygen deficiency rate (V Ｃ ) was calculated.

[0164] For oxygen vacancy rates below the lower limit of quantification by X-ray photoelectron spectroscopy, observation, projection, and oxygen vacancy measurement were performed using a scanning transmission electron microscope (HF5000, manufactured by Hitachi High-Technologies Corporation). The multilayer film to be measured was pretreated by (1) splitting the obtained multilayer film along with the substrate and cutting it to expose the cross section, (2) processing with a focused ion beam (FIB), and (3) etching in the vertical direction with an ion beam. The measurement site was then sampled and microfabricated using one or a combination of the following steps. Furthermore, to minimize changes in oxygen vacancies, processing was performed immediately after film deposition in an atmosphere combining low temperature, argon gas, and a vacuum pump.

[0165] Thereafter, under the condition of an acceleration voltage of 200 kV, HAADF-STEM images and ABF-STEM images, which show the presence or absence of oxygen atoms in the layer containing cerium oxide, were obtained stepwise in the depth direction of the film thickness. To assist in the observation of oxygen and oxygen vacancies, which are light elements, LAADF-STEM images of the same area were also obtained. A total of five images were obtained by changing the analysis area of ​​the layer film. Each of the obtained images was converted into a mapping image using software processing, and the number of oxygen sites and oxygen vacancies was counted to determine the oxygen deficiency rate (V) of the layer containing cerium oxide. Ａ ), (V Ｂ ), (V Ｃ ) was sought.

[0166] The multilayer films obtained in Examples 19 to 22, 28, 38, and 39 and Comparative Examples 5 to 9 were analyzed for oxygen deficiency rate (V Ａ ) was also measured. ２ and Ce(NO ３ ) ３ -6H ２ O was used, and the measured absorption edge was Ce-L ３ The absorption edge (5723.0 eV) was measured by the fluorescence yield method using a multi-element silicon drift detector. The oxygen deficiency rate was calculated from the fitting results of the obtained XANES spectrum. There was almost no difference between the oxygen deficiency rate values ​​measured by X-ray photoelectron spectroscopy and electron microscope, confirming that the oxygen deficiency rate measurement was valid.

[0167] (Measurement of Thickness (Film Thickness) and Refractive Index) The thickness and refractive index of each layer of the multilayer films in the Examples and Comparative Examples were determined using spectroscopic ellipsometry (JA WOOLLAM ESM300). The wavelength of the light source was set to 192 nm to 1000 nm, and the incident angle was measured in 5° increments in the range of 45° to 65°. To improve the accuracy of the analysis, transmittance was also measured. The obtained reflection and transmittance data were analyzed using a combination of models such as Cauchy, Gaussian, Tauc-Lorentz, and effective medium approximation (surface roughness), to determine the film thickness and refractive index. Because it is a multilayer film, the number of layers and film thicknesses are complex, which can make analysis difficult. In such cases, a single-layer film obtained separately from the same batch of film deposition was measured and analyzed, and the obtained data, such as the refractive index, was used for the analysis.

[0168] (Measurement of Composition) SiO in the multilayer films of Examples and Comparative Examples ２ + CeO ２ and SiO ２ +Al ２ O ３ The composition of the layer consisting of two components such as the above was determined by measurement using a wavelength dispersive X-ray fluorescence spectrometer (ZSX Primus II, manufactured by Rigaku Corporation). When quantitative analysis of each layer was difficult, the measurement was performed on a single layer film obtained separately by film formation in the same batch.

[0169] (Confirmation of Structure) A cross section of the multilayer film formed on the Si substrate was observed using an ultra-high resolution field emission scanning electron microscope (JSM-IT800, manufactured by JEOL Ltd.) to obtain backscattered electron images and secondary electron images. The obtained images were used to confirm whether the structure was columnar or other structures (non-columnar). The film thickness of each layer was also confirmed. There was almost no difference from the film thickness values ​​obtained using the ellipsometer, confirming that the film thickness measurements using the ellipsometer were valid. The composition of each layer was also measured using energy dispersive X-ray spectroscopy (EDX), and there was almost no difference from the values ​​obtained in the composition measurements described above, confirming that the composition measurements described above were valid.

[0170] (Measurement of Crystallinity) The multilayer films of the examples and comparative examples were measured by an XRD diffractometer (Smart Lab, manufactured by Rigaku Corporation) using a focusing method in the range of 2θ = 20° to 100° at a step of 0.01° and a speed of 5° / min, and the layers were identified and their crystallinity was confirmed based on the diffraction intensity, etc. Since these were multilayer films, MgF ２ and SiO ２ + CeO ２ In some cases, diffraction intensities such as these can interfere with analysis. In such cases, measurements were also taken of a single-layer film obtained separately from the same batch of film formation, and the analysis was also performed. Multilayer films that had diffraction peaks due to the cerium oxide-containing layer were judged to be crystalline, and multilayer films that did not have diffraction peaks due to the cerium oxide-containing layer were judged to be amorphous.

[0171] (Evaluation of Hydrophilicity Maintenance) The multilayer films of the Examples and Comparative Examples were left in a dark place (temperature 23±2°C, humidity 60±15% RH) for 60 days, after which the contact angle with water was measured. After the measurement, the substrate was left in a dark place for an additional 240 days, for a total of 300 days, after which the contact angle with water was measured. A contact angle meter, model CA-X150 manufactured by Kyowa Interface Science Co., Ltd., was used, and 2.5 mL of pure water was dropped onto the test piece from a microsyringe, and the contact angle 5 seconds after the drop was determined by the θ / 2 method. The hydrophilicity of a surface can be quantified by the contact angle with water. Generally, a contact angle of less than 20° is called hydrophilic, and a contact angle of less than 10° is called superhydrophilic. Following this, a contact angle of less than 10° was rated [A], a contact angle of 10° or more but less than 20° was rated [B], and a contact angle of 20° or more was rated [C].

[0172] (Self-cleaning performance evaluation) Stearic acid was applied to the multilayer films of the examples and comparative examples using a heptane solution (0.3% by mass) of stearic acid in accordance with JIS R1753-1, and the multilayer films were dried in a dryer at 70°C for 30 minutes. The contact angle of the test piece coated with stearic acid was then measured in the same manner as described in (Evaluation of Hydrophilicity Maintenance) to confirm that the contact angle was 20° or greater. If the contact angle was not 20° or greater, the application of stearic acid, drying, and contact angle measurement were repeated until the contact angle reached 20° or greater. The multilayer film coated with stearic acid was then irradiated with ultraviolet light for 2 hours and 30 hours, after which the contact angle was measured again to determine the water contact angle after ultraviolet irradiation. A black light blue fluorescent lamp (FL20SBL-B, manufactured by Hotalux Co., Ltd.) was used as the ultraviolet light source. The ultraviolet light had an illuminance of 2.0 mW / cm. ２ As in the evaluation in the above (evaluation of hydrophilicity maintenance), a contact angle of less than 10° was evaluated as [A], a contact angle of 10° or more but less than 20° was evaluated as [B], and a contact angle of 20° or more was evaluated as [C].

[0173] The results obtained in (Hydrophilicity Maintenance Evaluation) and (Self-cleaning Performance Evaluation) are shown in Tables 1-1 to 1-4. Note that in each of the Examples and Comparative Examples, the evaluation results were the same regardless of the type of substrate.

[0174] (Evaluation of Optical Properties) The transmittance and reflectance of the multilayer films of the examples and comparative examples were measured at an incident angle of 5°. A UV-visible-near-infrared spectrophotometer (Hitachi High-Tech UH4150) was used as the measuring device, and measurements were taken in 1-nm increments over the wavelength range of 450 nm to 1200 nm. The average values ​​of the transmittance (%) and reflectance (%) obtained for each wavelength were calculated to obtain the average transmittance (%) and average reflectance (%). The average light loss was calculated by subtracting the average transmittance (%) and average reflectance (%) from 100%. An average light loss of less than 1% was rated as [A], and an average light loss of 1% or greater was rated as [C].

[0175]

[0176]

[0177]

[0178]

[0179] Comparative Example 23 Instead of forming a layer containing cerium oxide as in Example 23, a TiO ２ In this case, Ti was used as the film forming material. ３ O ５ The other film formation conditions were the same as in Example 23 to form a multilayer film. ２ The crystallinity of the layer was evaluated and found to be anatase polycrystalline. The structure was evaluated and found to be columnar. The hydrophilicity retention performance was evaluated and found to have a water contact angle of 58.7° after 60 days and 63.4° after 300 days. The self-cleaning performance was evaluated and found to have a water contact angle of 77.5° after 2 hours of irradiation and 72.5° after 30 hours of irradiation.

[0180] Comparative Example 24 Instead of forming a layer containing cerium oxide as in Example 24, a TiO ２ In this case, Ti was used as the film forming material. ３ O ５ The other film formation conditions were the same as in Example 24. ２ The crystallinity of the layer was evaluated and found to be polycrystalline, with anatase crystals as the main component and traces of rutile crystals present. The structure was also evaluated and found to be columnar. The hydrophilicity retention performance was evaluated and found to have a water contact angle of 39.4° after 60 days and 61.6° after 300 days. The self-cleaning performance was evaluated and found to have a water contact angle of 72.3° after 2 hours of irradiation and 63.4° after 30 hours of irradiation.

[0181] Comparative Example 25 Various substrates were set in brass and 99.5% pure aluminum holders, and the substrate heating and wall heater of the vacuum deposition device were set to OFF. －３ The chamber was evacuated to a vacuum of 100 Pa or less. The substrate temperature before film formation was 24°C. A Cr layer (1 nm) was formed as the first layer on each substrate. A hearth liner made of oxygen-free copper and CeO were used as the film forming material. ２Before starting the process of forming the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and it was found to be 8.94×10 －４ Subsequently, SiO ２ Using SiO ２ During the film formation in the region 8 nm from the surface of the cerium oxide-containing layer (region (B): the region of the cerium oxide-containing layer located 8 nm or less from the interface between the cerium oxide-containing layer and the silicon oxide-containing layer or the magnesium fluoride-containing layer), the total partial pressure of water molecules and oxygen species was 8.03 × 10 on average. －３ The obtained multilayer film was evaluated for crystallinity, structure, optical properties, and oxygen deficiency rate in the same manner as the multilayer films of Examples 1 to 68. The evaluation results showed that the layer containing cerium oxide had a crystalline columnar structure, and the oxygen deficiency rate was V Ａ is 0.02%, V Ｂ is 0.01%, V Ｃ was 0.02%. ２ The refractive index of the layers was 1.46. The optical loss of the multilayer film was 1.4%, and the optical characteristics were evaluated as [C].

[0182] Example 67 The flat glass having the multilayer film obtained in Example 3 was processed and attached to the outside of a near-infrared sensor of a commercially available vehicle to form a protective cover for the sensor.

[0183] Example 68 A dome-shaped transparent substrate made of polymethyl methacrylate resin (Acrylite (registered trademark) manufactured by Mitsubishi Chemical Corporation) with an acrylic hard coat was used as the substrate. The substrate temperature of a vacuum deposition apparatus was set to 50°C, and the wall heater was set to 50°C, and the apparatus was evacuated to a vacuum. When 15 minutes or more had elapsed after the substrate temperature reached 50±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was measured, and it was found to be 1.49 × 10 －４ The film was formed using SiO as a film-forming material. ２ A film (200 nm) was formed as the first layer at a deposition rate of 0.3 nm / s.

[0184] Next, TaO was used as the film-forming material, and Ta ２ O ５ The second layer was formed with a film (14 nm) at a deposition rate of 0.2 nm / s. The third layer was formed with SiO ２ Using SiO ２ A film (35 nm) was formed as the first layer at a deposition rate of 0.7 nm / s. For the fourth layer, Ce and CeO were used as film-forming materials. ２ A layer containing cerium oxide (256 nm) was formed at a deposition rate of 0.3 nm / s using a SiO 2 and CeO 3 film-forming material. ２ SiO at a deposition rate of 0.5 nm / s using ２ (95%) + CeO ２ The final sixth layer was formed using SiO as the film-forming material. ２ Using SiO ２ A film (10 nm, refractive index 1.46) was formed on the substrate to prepare a multilayer film. During the film formation, the substrate was rotated in planetary rotation.

[0185] The deposition of the first, second, and fourth layers was performed using an RF ion source with ion assistance. For the first layer, the acceleration voltage was 280 V, the acceleration current was 280 mA, and the O ２ Ion assist was performed under the condition of a gas flow rate of 40 sccm, and for the second layer, the acceleration voltage value was 500 V, the acceleration current value was 500 mA, and O ２ The ion-assisted deposition was carried out under the condition of a gas flow rate of 60 sccm. For the fifth layer, the acceleration voltage was 500 V, the acceleration current was 500 mA, and O ２ Ion-assisted deposition was performed under the condition of a gas flow rate of 40 sccm. When depositing the fifth layer with a thickness of 8 nm on the surface, the deposition rate was changed to 0.5 nm / s, and the O ２ The gas flow rate was changed to 0 sccm and the Ar gas flow rate was changed to 40 sccm for film formation.

[0186] The resulting dome-shaped resin substrate with the multilayer film and the various substrates on which the film was formed at the same time were evaluated for the composition, crystallinity, structure, oxygen deficiency rate, and optical properties of the thin film in the same manner as the multilayer films of Examples 1 to 68.２ + CeO ２ The composition of the layer is SiO ２ (95%) + CeO ２ (5%), the film thickness was 79 nm, and the refractive index was 1.52. ２ The refractive index of the layer was 1.46. The layer containing cerium oxide had a crystalline columnar structure, and the oxygen deficiency rate was V Ａ is 0.05%, V Ｂ is 0.52%, V Ｃ The optical loss was 0.03%, and the optical loss was less than 1.5%. Subsequently, the dome-shaped resin substrate with the obtained multilayer film was attached to a surveillance camera for use as a surveillance camera cover.

[0187] The surveillance camera equipped with the manufactured cover was stored in a dark place in a product presentation box for four months. It was then installed outdoors during rainy weather at night. Even when water got on the camera due to rain, the water droplets spread over the cover, maintaining good visibility. Even after the water dried, no water marks remained, maintaining good visibility. Furthermore, even during rainy weather eight months after installation outdoors, the water droplets spread over the cover, maintaining good visibility.

[0188] Example 69 The substrate used was a resin substrate (MR-8 manufactured by Mitsui Chemicals) coated with a silicon-based hard coat. The vacuum deposition apparatus was set to a substrate temperature of 80°C and a wall heater at 80°C, and then evacuated. When 15 minutes or more had elapsed after the substrate temperature reached 80±2°C and before the start of the film formation process for the cerium oxide-containing layer, the total partial pressure of water molecules and oxygen molecules was checked, and the total partial pressure was 1.52 × 10 －４ The film forming material was Al. ２ O ３ Using Al ２ O ３ A film (82 nm) was formed as the first layer of the multilayer film. The second layer was formed using Ce and CeO as film-forming materials. ２ Using CeO ２ The third layer was formed using SiO as the film-forming material. ２ and Al ２ O ３ Using SiO ２ (95%) + CeO ２The final fourth layer was a SiO film (75 nm, refractive index 1.52). ２ For use with SiO ２ A film (15 nm, refractive index 1.46) was formed on the resin substrate to prepare a multilayer film. The deposition rate during film formation was 0.5 nm / s. The resin substrate with the multilayer film was then processed and attached to an eyeglass frame to prepare eyeglasses.

[0189] The obtained eyeglass lens substrate with the multilayer film and the various substrates on which the film was formed at the same time were evaluated for crystallinity, structure, oxygen deficiency rate, and optical properties in the same manner as the multilayer films of Examples 1 to 68. As a result of the evaluation, it was found that the layer containing cerium oxide had a crystalline columnar structure, and the oxygen deficiency rate was V Ａ is 0.05%, V Ｂ is 0.53%, V Ｃ The optical loss was 0.03%, and the optical loss was less than 1.5%. The manufactured eyeglasses were then stored in an aluminum eyeglass case in a dark place for three months. When water droplets were then placed on the lenses, the droplets spread across the lenses, maintaining good visibility. The contact angle of water at this time was 4.7°. Furthermore, no water marks remained even after the water had dried, maintaining good visibility.

[0190] The multilayer film of the present disclosure can be used for optical components such as optical filters, optical lenses, light collecting lenses, optical films, optical prisms, eyeglass lenses, photographic lenses, vehicle door mirrors, plate glass, condenser lenses, display cover glass, touch panels, and various films, as well as covers for protecting optical components such as surveillance camera covers, in-vehicle camera covers, and in-vehicle sensor covers.

[0191] In addition, the optical member of the present disclosure can be used as optical devices such as digital cameras, digital video cameras, action cameras, endoscopes, lens barrels, eyeglasses, sensors, binoculars, telescopes, surveillance cameras, in-vehicle cameras, smartphones, tablet PCs, weather cameras, live cameras, protective goggles, underwater goggles, head-mounted displays, sunglasses, smart glasses, face shields, helmet shields, vehicle mirrors, and bathroom mirrors, as well as covers for protecting these devices.

[0192] This application claims priority based on Japanese Patent Application No. 2023-221408, filed on December 27, 2023, the entire contents of which are incorporated herein by reference.

[0193] REFERENCE SIGNS LIST 11 Substrate 12 Other layer 13 Layer containing cerium oxide 14 Layer containing magnesium fluoride 15 Layer containing silicon oxide 16 Layer containing silicon dioxide 21 Dome-shaped resin substrate 31 Spectacle lens 32 Spectacle frame

Claims

1. It has a layer containing cerium oxide and a low refractive index layer directly on the layer containing cerium oxide or via another layer. The low refractive index layer has a layer containing silicon oxide or a layer containing magnesium fluoride. The layer containing cerium oxide contains cerium oxide including a cubic polycrystalline structure and a columnar structure. The film thickness of the layer containing cerium oxide is 85 nm or more and 800 nm or less. Taking the entire layer containing cerium oxide as region (A) and the oxygen deficiency rate of cerium oxide in the region (A) as the oxygen deficiency rate (V Ａ ), when the oxygen deficiency rate (V Ａ ) is 0.05% or more and 10% or less, the film thickness of the low refractive index layer is 50 nm or more and 240 nm or less, and the refractive index of the low refractive index layer with respect to light having a wavelength of 500 nm is 1.65 or less. A multilayer film characterized by this.

2. The oxygen deficiency rate (V Ａ ) is 0.05% or more and 0.6% or less. The multilayer film according to claim 1.

3. The oxygen deficiency rate (V Ａ ) is 0.1% or more and 0.3% or less, and the multilayer film according to claim 1.

4. The region of the cerium oxide-containing layer within a range of 8 nm or less from the interface between the cerium oxide-containing layer and the low refractive index layer is defined as region (B). When the oxygen deficiency rate of cerium oxide in the region (B) is defined as the oxygen deficiency rate (V Ｂ ), the multilayer film according to any one of claims 1 to 3, wherein the oxygen deficiency rate (V Ｂ ) is 0.5% or more and 30% or less.

5. The oxygen deficiency rate (V Ａ ) is 0.05% or more and 10% or less, and the oxygen deficiency rate (V Ｂ ) is 0.5% or more and 30% or less. When the region excluding the region (B) from the region (A) is defined as the region (C) and the oxygen deficiency rate of cerium oxide in the region (C) is defined as the oxygen deficiency rate (V Ｃ ), the oxygen deficiency rate (V Ｃ ) is 0% or more and 10% or less, and the oxygen deficiency rate (V Ｂ ) is greater than the oxygen deficiency rate (V Ｃ ). The multilayer film according to claim 4.

6. An optical member having the multilayer film according to any one of claims 1 to 5.

7. A step (A) of forming a layer containing cerium oxide by a vacuum evaporation method directly on a substrate or via another layer, and a step (B) of forming a low refractive index layer by a vacuum evaporation method directly on the layer containing cerium oxide or via another layer, wherein the low refractive index layer has a layer containing silicon oxide or a layer containing magnesium fluoride, the layer containing cerium oxide contains cerium oxide including a cubic polycrystalline structure and a columnar structure, the film thickness of the layer containing cerium oxide is 85 nm or more and 800 nm or less, the entire layer containing cerium oxide is defined as region (A), and when the oxygen deficiency rate of cerium oxide in the region (A) is defined as oxygen deficiency rate (V Ａ ), the oxygen deficiency rate (V Ａ ) is 0.05% or more and 10% or less, and the film thickness of the low refractive index layer is 50 nm or more and 240 nm or less. A method for manufacturing a multilayer film, characterized by the above.

8. The region of the cerium oxide-containing layer within a range of 8 nm or less from the interface between the cerium oxide-containing layer and the low refractive index layer is defined as region (B). When the oxygen deficiency rate of cerium oxide in region (B) is defined as oxygen deficiency rate (V Ｂ ), the oxygen deficiency rate (V Ｂ ) is 0.5% or more and 30% or less. Of region (A), the region excluding region (B) is defined as region (C). When the oxygen deficiency rate of cerium oxide in region (C) is defined as oxygen deficiency rate (V Ｃ ), the oxygen deficiency rate (V Ｃ ) is 0% or more and 10% or less. The oxygen deficiency rate (V Ｂ ) is greater than the oxygen deficiency rate (V Ｃ ). The method for manufacturing a multilayer film according to claim 7.

9. Before the step (A), the total value of the partial pressure of water molecules and the partial pressure of oxygen molecules in the atmosphere is 2×10 －２ Pa or less, and the average total value of the partial pressure of water molecules and the partial pressure of oxygen species during film formation in the region (B) is 2×10 －２ Pa or less. The method for manufacturing a multilayer film according to claim 7 or 8.

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