Optical films, optical elements, and optical instruments

Abstract

This technology provides advantages in improving antistatic properties and optical performance. [Solution] The optical film is disposed on a substrate and comprises one or more layers. At least one layer of the optical film contains a metal oxide and a metal oxynitride. When the oxygen atom content in at least one layer is [O]at% and the nitrogen atom content is [N]at%, the following condition is satisfied: 80.0% ≤ [O] / ([O]+[N]) ≤ 99.0%.

Description

[Technical Field]

[0001] This invention relates to optical films, optical elements, and optical instruments. [Background technology]

[0002] In optical elements such as lenses and optical filters used in optical devices such as cameras, smartphones, and exposure equipment, an optical film is coated onto the substrate to improve optical performance. The optical film coated onto the substrate can be a single layer or a multilayer film.

[0003] Optical films often use dielectric materials with a large band gap to obtain high light transmittance. Because these types of optical films are prone to static electricity buildup, dust and film particles tend to adhere to the surface of optical elements when they are attached to the optical instrument body, and once the dust adheres to the optical element, it cannot be easily removed. As a result, for example, if the optical instrument is an imaging instrument, the dust may be output as an image, degrading the performance of the optical instrument, or dust may get trapped between the optical element and the optical instrument body during manufacturing, affecting the assembly accuracy.

[0004] In contrast, Patent Document 1 discloses the use of conductive materials such as ITO in the optical film. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-221142 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, when the conductive material disclosed in Patent Document 1 is used for an optical film, there is a risk that the light transmittance will decrease due to absorption derived from the material such as band gap absorption and free electron absorption, so improvement has been desired.

[0007] The present invention provides a technique advantageous for improving antistatic properties and optical performance.

Means for Solving the Problems

[0008] One aspect of the present invention is an optical film disposed on a substrate and including a single layer or a plurality of layers, wherein at least one layer of the optical film contains a metal oxide and a metal oxynitride, and when the content of oxygen atoms in the at least one layer is [O] at% and the content of nitrogen atoms is [N] at%, it satisfies 80.0% ≤ [O] / ([O] + [N]) ≤ 99.0%. The optical film is characterized by this.

Effects of the Invention

[0009] According to the present invention, a technique advantageous for improving antistatic properties and optical performance is provided.

Brief Description of the Drawings

[0010] [Figure 1] It is a schematic cross-sectional view of an optical element according to an embodiment. [Figure 2] It is a schematic diagram showing an example of a film forming apparatus according to an embodiment. [Figure 3] (a) is a schematic diagram of an exposure apparatus which is an example of an optical device including an optical element according to an embodiment. (b) is a schematic diagram of a smartphone which is an example of another optical device including an optical element according to an embodiment. [Figure 4] (a) is a schematic cross-sectional view of an optical element according to Examples 1 to 7. (b) is a schematic cross-sectional view of an optical element according to Comparative Examples 1 and 2. [Figure 5] It is a table showing the experimental results of Examples 1 to 7 and Comparative Examples 1 and 2. [Figure 6] It is a graph showing the light absorption rate with respect to the wavelength of light according to Example 1 and Comparative Example 2. [Figure 7] (a) is a graph showing the results of time-of-flight secondary ion mass spectrometry for Example 2 and Comparative Example 1. (b) is a graph showing the results of time-of-flight secondary ion mass spectrometry for Example 2 and Comparative Example 1. [Figure 8] This graph shows the average light absorption coefficient in the visible light wavelength range for [O] / ([O]+[N]) for Examples 1-7 and Comparative Example 2. [Figure 9] This graph shows the sheet resistance to [O] / ([O]+[N]) for Examples 1-7 and Comparative Example 1. [Figure 10] This graph shows the light absorption rate in the ultraviolet wavelength range for ([O]+[N]) / ([M]+[O]+[N]) for Examples 1-7 and Comparative Example 2. [Figure 11] This graph shows the light absorption rate in the ultraviolet wavelength range for ([O]+[N]) / ([M]+[O]+[N]) in Examples 1-3 and 6-7. [Figure 12] This graph shows the light absorption rate in the ultraviolet wavelength range for the bond ratio [M-ON] / [MO] related to Examples 1-3. [Figure 13] (a) is a diagram illustrating the layer structure of the optical film according to Example 8. (b) is a graph showing the light transmittance as a function of the wavelength of light in the optical element according to Example 8. [Figure 14] (a) is a diagram illustrating the layer structure of the optical film according to Example 9. (b) is a graph showing the light transmittance as a function of the wavelength of light in the optical element according to Example 9. [Modes for carrying out the invention]

[0011] The embodiments will be described below with reference to the drawings. In the following description and drawings, components common to multiple drawings are denoted by the same reference numerals. The description of components denoted by the same reference numerals will be omitted as appropriate. Also, in the following description, notations such as "1.0E+08" will be interpreted as "1.0×10 8 This means "[...]." The same applies to other numbers.

[0012] Figure 1 is a schematic cross-sectional view of an optical element 100 according to an embodiment. The optical element 100 is an optical element such as a lens, filter, mirror, prism, image sensor, or display element. Furthermore, the optical element 100 is used in optical devices such as exposure equipment, cameras, interchangeable lenses, and smartphones.

[0013] The optical element 100 comprises a substrate 101 and an optical film 102 disposed on the substrate 101. The material of the substrate 101 is, for example, glass or plastic (resin). Furthermore, the main surface of the substrate 101 can be a flat or curved shape, and various shapes can be used depending on the application of the optical element 100.

[0014] The optical film 102 consists of a single layer or multiple layers, and in this embodiment, the optical film 102 consists of multiple layers. Of the multiple layers of the optical film 102, at least one layer, in this embodiment, one layer 102c, contains a metal oxide and a metal oxynitride. If the optical film 102 consists of a single layer, that single layer is the layer 102c containing the metal oxide and the metal oxynitride.

[0015] Furthermore, the optical film 102 comprises multiple layers, including one or more low-refractive-index layers 102a and one or more high-refractive-index layers 102b. The low-refractive-index layer 102a is a layer with a lower refractive index than the high-refractive-index layer 102b. In other words, the high-refractive-index layer 102b is a layer with a higher refractive index than the low-refractive-index layer 102a. Layer 102c may be a low-refractive-index layer, a high-refractive-index layer, or a layer other than a low-refractive-index layer or a high-refractive-index layer. Layer 102c may be the surface layer of the optical film 102 that forms the surface of the optical element 100, an inner layer of the optical film 102, or a layer in contact with the substrate 101. In the example in Figure 1, layer 102c is an inner layer of the optical film 102.

[0016] Layer 102c may be at least one of a plurality of high refractive index layers 102b. That is, some or all of the plurality of high refractive index layers 102b may be layer 102c. If the optical film 102 is composed of a single layer, that layer may be layer 102c, and layer 102c may be a high refractive index layer 102b.

[0017] In an optical film 102 having a layer 102c containing metal oxides and metal oxynitrides, it is preferable that the surface resistivity (i.e., sheet resistance) of the optical film 102 having layer 102c be low in order to exhibit antistatic properties. The amount of dust generated varies depending on the environment, and in a general environment, the amount of dust generated is greater than in a cleanroom environment. Therefore, when the optical element 100 is used in a general environment, a lower resistance value is required for the sheet resistance of the optical film 102 than when the optical element 100 is used in a cleanroom environment. Therefore, when the optical element 100 is used in a cleanroom environment, the sheet resistance of the optical film 102 should be 1.0 × 10⁻⁶. 13 It is preferable that the resistance is Ω / □ or less, and when the optical element 100 is used in a general environment, the sheet resistance of the optical film 102 is 1.0 × 10 11 It is preferable that the resistance is Ω / □ or less. Furthermore, the sheet resistance of the optical film 102 is 1.0 × 10⁻⁶. 11 If the impedance is Ω / □ or less, the optical element 100 can be used in a cleanroom environment. The usage environment for the optical element 100 includes, for example, the environment in which optical equipment is manufactured.

[0018] Thus, the low sheet resistance of the optical film 102 having a layer 102c containing a metal oxide and a metal oxynitride gives the optical film 102 antistatic properties. In an optical element 100 equipped with such an optical film 102, even if dust adheres to the surface of the optical element 100, the dust can be easily removed from the optical element 100 using a lens blower or the like.

[0019] Furthermore, in order to improve the optical performance of the optical element 100, it is preferable that the light absorption rate in the layer 102c containing the metal oxide and metal oxynitride, particularly the light absorption rate at wavelengths of visible light, is low.

[0020] Assuming that the optical element 100 is to be used in the visible light wavelength range, the average light absorption rate in layer 102c for wavelengths from 400 nm to 800 nm is preferably 3.0% or less. Furthermore, if even higher optical performance is required for the optical element 100, the average light absorption rate in layer 102c for wavelengths from 400 nm to 800 nm is preferably 1.0% or less.

[0021] Furthermore, assuming that the optical element 100 is to be used in the ultraviolet wavelength range, it is preferable that the light absorption rate at a wavelength of 365 nm in layer 102c is 1.0% or less. If even higher optical performance is required for the optical element 100, it is preferable that the light absorption rate at a wavelength of 365 nm in layer 102c is 0.3% or less. Furthermore, if even higher optical performance is required for the optical element 100, it is more preferable that the light absorption rate at a wavelength of 365 nm in layer 102c is 0.1% or less.

[0022] Furthermore, assuming that the optical element 100 is used in the infrared wavelength range, it is preferable that the light absorption rate at a wavelength of 1000 nm in layer 102c is 1.0% or less.

[0023] When layer 102c containing a metal oxide and a metal oxynitride is used as a high refractive index layer, it is preferable that the refractive index of light at a wavelength of 550 nm is 2.0 or higher. In this case, it is preferable that the metal element contained in layer 102c is at least one of Ta, Ti, Zr, V, Nb, and Cr.

[0024] Furthermore, if the optical film 102 is a multilayer film, the material of the low refractive index layer 102a may be aluminum oxide (Al2O3), silicon oxide (SiO2), magnesium fluoride (MgF2), etc., but is not limited to these. In addition, the low refractive index layer 102a may contain one of these materials as the main component, or it may contain a mixture containing at least two of these materials.

[0025] Furthermore, if the optical film 102 is a multilayer film, the material of the high refractive index layer 102b may be tantalum oxide (Ta2O5), titanium oxide (TiO2), niobium oxide (Nb2O5), etc., but is not limited to these. In addition, the high refractive index layer 102b may contain one of these materials as the main component, or it may contain a mixture containing at least two of these materials.

[0026] Furthermore, if the optical film 102 is a multilayer film, the multiple low refractive index layers 102a of the optical film 102 may all be made of the same material, but are not limited to this. Similarly, the multiple high refractive index layers 102b of the optical film 102 may all be made of the same material, but are not limited to this. For example, some of the multiple low refractive index layers 102a may be made of silicon oxide (SiO2) and the remaining layers may be made of magnesium fluoride (MgF2), so that some layers are made of a different material from the remaining layers.

[0027] Figure 2 is a schematic diagram showing an example of a film deposition apparatus 200 used to form a layer 102c containing a metal oxide and a metal oxynitride according to the embodiment. In forming the layer 102c in this embodiment, atomic layer deposition (ALD) is preferred, but the method is not limited to this method. For example, physical vapor deposition methods such as sputtering, or chemical vapor deposition methods other than ALD such as plasma CVD may also be used.

[0028] The ALD method is a film deposition technique performed in a vacuum. The ALD method consists of four steps: introducing an organometallic gas called a precursor, purging the precursor, introducing a reactive gas, and purging the reactive gas. This cycle is repeated multiple times to form a film.

[0029] The film deposition apparatus 200 includes a reaction chamber 201, an exhaust pump 202, a heating mechanism 203, introduction ports 204 for precursor and inert gas, and introduction ports 205 for reactive and inert gas. A heatable substrate holding stage 206 is located inside the reaction chamber 201. A substrate 207 is placed on the substrate holding stage 206, thereby holding the substrate 207 in place. A film (layer) is formed on the substrate 207 held in the substrate holding stage 206.

[0030] The following explanation will use the case where the metal oxide is tantalum oxide (Ta2O5) and the metal oxynitride is tantalum oxynitride (TaON) as an example.

[0031] Tris(ethylmethylamido)(tert-butylimido)tantalum(V) is used as the precursor, and H2O is used as the reactive gas (oxidizing agent).

[0032] Furthermore, nitrogen gas is introduced as a carrier gas in the diffusion processes of both the raw material gas and the reactive gas to efficiently diffuse the gases. Nitrogen gas is also introduced as a carrier gas in the purging process to efficiently discharge residual gases. The ambient temperature in reaction chamber 201 is set to a low temperature between 70°C and 150°C. The precursor supply time per cycle is 1 s, the diffusion time is 5 s, and the purging time is 10 s. For the oxidizing agent, the supply time is 0.1 s, the diffusion time is 5 s, and the purging time is 10 s. When layer 102c is deposited under these conditions, the film thickness grown per cycle is approximately 0.1 nm. The number of cycles should be determined according to the target film thickness.

[0033] In this embodiment, by including nitrogen atoms in the precursor and keeping the ambient temperature in the reaction chamber 201 low, around 100°C, layer 102c, which is a mixed layer containing metal oxide and metal oxynitride, can be formed.

[0034] Chemical vapor deposition (CVD) is often performed under high-temperature conditions of 300°C or higher in the reaction chamber 201 to stabilize the chemical composition of the product. However, in this embodiment, by setting the ambient temperature in the reaction chamber 201 to a low temperature of around 100°C, it is possible to fabricate layer 102c, which is a mixed layer containing metal oxides and metal oxynitrides.

[0035] When layer 102c is formed in a low-temperature environment using the ALD method as described above, the desired chemical composition may not be achieved. In such cases, in order to stably obtain the desired chemical composition, it is preferable to perform a post-treatment after film formation by irradiating layer 102c with light from a light source having a wavelength of 365 nm as its emission line for at least one hour.

[0036] While the post-treatment method is not limited to the method described above, when post-treatment is performed by light irradiation, halogen lamps and the like, whose emission lines are in the visible light wavelength range, have too little light energy, resulting in little change in the chemical composition of the product even after light irradiation. Therefore, in post-treatment, it is preferable to irradiate layer 102c with light from a light source that has emission lines in the ultraviolet wavelength range, which has light energy greater than the visible light wavelength range.

[0037] The reason why the desired chemical composition can be stably obtained by irradiating layer 102c with ultraviolet light is not clear, but it is speculated that when layer 102c is formed in a low-temperature environment, metal oxynitrides (e.g., TaON) and metal oxynitride carbides (e.g., TaONC) that are generated in layer 102c act as catalysts, and when light with emission lines in the ultraviolet wavelength range is irradiated onto layer 102c, unreacted components such as residual raw materials and residual water are activated, and the chemical reaction proceeds, thereby stably obtaining the desired chemical composition.

[0038] Furthermore, while the desired chemical composition can also be obtained by annealing as a post-treatment in addition to light irradiation, in the case of post-treatment by annealing, depending on the atmosphere of the annealing environment, heating time, and heating temperature, there are conditions under which oxygen and nitrogen are likely to be depleted. For this reason, it is preferable to perform post-treatment using the method described above in this embodiment.

[0039] Furthermore, the precursor or reactive gas may be appropriately changed according to the target material. For example, when the metal element in the metal oxide and metal oxynitride is to be Zr instead of Ta, Tetrakis(ethylmethylamido)zirconium(IV) may be used as the precursor, and when the metal element is to be Hf, Tetrakis(ethylmethylamido)hafnium(IV) may be used as the precursor. In addition, the reactive gas used may be O3 or H2O2 in addition to H2O, and a nitriding agent such as NH3 may be used in addition to the oxidizing agent.

[0040] While an example of the conditions for forming layer 102c has been described, the process is not limited to this. For example, the film may be formed by changing the gas material, the time for introducing the gas, or the temperature from the above conditions, or by using plasma to accelerate the reaction.

[0041] Figure 3(a) is a schematic diagram of an exposure apparatus 300, which is an example of an optical device equipped with an optical element 100 according to an embodiment. The exposure apparatus 300 comprises an outer casing 310 and a main body 320. At least a part of the main body 320 is covered by the outer casing 310. The main body 320 comprises a light source 301, mirrors 302 and 303 constituting an illumination optical system, a reticle stage 305 on which a reticle 304 is mounted, a projection optical system 306 for projecting the pattern of the reticle 304, and a stage 308 for holding a substrate 307.

[0042] A photoresist is coated on the substrate 307, and the photoresist is exposed by exposure light 309. The substrate 307 may be a semiconductor wafer or a glass substrate for an FPD (flat panel display). The exposure light of the exposure apparatus 300 is typically ultraviolet light. The wavelength of the exposure light is, for example, about 365 nm, but is not limited to this.

[0043] The optical element 100 shown in Figure 1 can be used, for example, in mirrors 302 and 303. In this case, the material of the substrate 101 of the optical element 100 is preferably glass. The optical element 100 may also be used as a lens in the projection optical system 306.

[0044] Figure 3(b) is a schematic diagram of a smartphone 400, which is another example of an optical device equipped with the optical element 100 according to the embodiment. It comprises an outer casing 410 and a device body 420. At least a portion of the device body 420 is covered by the outer casing 410.

[0045] The main unit 420 includes a multi-lens camera module 450. The multi-lens camera module 450 has a plurality of lens units 401 and a plurality of image sensors (not shown) that each receive light that has passed through the plurality of lens units 401. Each of the plurality of lens units 401 is positioned on the light-receiving surface side of the corresponding image sensor among the plurality of image sensors. The optical element 100 may be used in at least one lens among the plurality of lenses included in at least one of the plurality of lens units 401. In this case, the material of the substrate 101 of the optical element 100 is preferably plastic.

[0046] Furthermore, the optical element 100 can be applied to various optical devices other than those mentioned above, such as cameras, interchangeable lens units for cameras, projectors, and light sensors.

[0047] [Examples] Examples 1 to 7 and Comparative Examples 1 and 2 are described below. Figure 4(a) is a schematic cross-sectional view of the optical element 100 according to Examples 1 to 7, and Figure 4(b) is a schematic cross-sectional view of the optical element 100X according to Comparative Examples 1 and 2. The optical element 100 of Examples 1 to 7 has a substrate 101 and an optical film 102. The optical film 102 is composed of a single layer, layer 102c. The optical element 100X of Comparative Examples 1 and 2 has a substrate 101 and an optical film 102Y. The optical film 102Y is composed of a single layer, layer 102X.

[0048] In the following explanation, the content (concentration) of metal atoms in layers 102c and 102X is denoted as [M]at%, the content (concentration) of oxygen atoms in layers 102c and 102X as [O]at%, the content (concentration) of nitrogen atoms in layers 102c and 102X as [N]at%, the content (concentration) of hydrogen atoms in layers 102c and 102X as [H]at%, the content (concentration) of carbon atoms in layers 102c and 102X as [C]at%, and the content (concentration) of argon atoms in layers 102c and 102X as [Ar]at%. Here, "at%" means "atomic percentage," which is the ratio of the number of specific atoms to the total number of atoms in the sample.

[0049] For layer 102c containing metal oxides and metal oxynitrides, the chemical composition can be evaluated by Rutherford backscattering spectrometry (RBS) by irradiating layer 102c with a high-energy ion beam on the order of MeV. However, the hydrogen atom content [H]at% can be evaluated by hydrogen forward scattering spectrometry (HFS), and while the nitrogen atom content [N]at% and carbon atom content [C]at% of the light elements can be evaluated by RBS, they can be evaluated with higher accuracy by using nuclear reaction analysis (NRA). Therefore, in this example, the chemical composition was evaluated by combining the RBS, HFS, and NRA methods.

[0050] Furthermore, for layer 102c containing metal oxides and metal oxynitrides, the bonding ratio of the metal oxides and metal oxynitrides in the molecular state can be evaluated by measuring the ionic intensity at a mass number of interest, for example, around mass number 442 for Ta2O5 or around mass number 211 for TaON, using time-of-flight secondary ion mass spectrometry (ToF-SIMS).

[0051] In this example, the primary ion was obtained using TOF-SIMS V manufactured by ION-TOF Corporation. 3+ 25kV, 0.4pA (pulse width 10ns), irradiation area 200μm 2 The bonding ratio [M-ON] / [MO] was evaluated under the specified conditions. In addition, to evaluate the bonding ratio inside the film, the required film thickness was etched by sputter ion gun irradiation before evaluation. Here, [M-ON] is the ionic intensity (signal intensity) due to the metal oxynitride, and [MO] is the ionic intensity (signal intensity) due to the metal oxide.

[0052] For layers 102c and 102X, the light transmittance and light reflectance can be measured, for example, using an ultraviolet-visible-near-infrared spectrophotometer in the wavelength range from 300 nm to 1200 nm, with a light incidence angle of 5 degrees. Furthermore, the light absorptance can be calculated from the measured light transmittance and light reflectance results using the following equation (1). A(%) = 100 - T(%) - R(%) ... (1)

[0053] However, A represents the light absorptivity, which is the ratio of light absorption to incident light intensity; T represents the light transmittance, which is the ratio of light transmission to incident light intensity; and R represents the light reflectance, which is the ratio of light reflection to incident light intensity.

[0054] In this example, the light absorptance at a wavelength of 365 nm, the average light absorptance in the range of wavelengths from 400 nm to 800 nm, and the light absorptance at a wavelength of 1000 nm were calculated.

[0055] For layers 102c and 102X, the refractive index and film thickness can be calculated based on the measured light reflectance results, for example, by analyzing them using optical thin film analysis and design software FilmWizard™ from Scientific Computing International. In this example, the refractive index was calculated at a wavelength of 550 nm.

[0056] For layers 102c and 102X, the surface resistivity, i.e., sheet resistance, of the optical films 102 and 102Y can be evaluated by, for example, using a resistivity meter, pressing a double-ring electrode against the optical films 102 and 102Y, and applying a voltage in the range of 10V to 1000V between the double-ring electrodes. However, the Hi-Resta UP (MCP-HT450, manufactured by Mitsubishi Chemical Corporation) used in the resistivity measurement in this embodiment has a capacity of 1.0 × 10⁻⁶ 14 Values ​​above Ω / □ are outside the measurement range, and 1.0 × 10 14 It was not possible to evaluate samples with high resistance of Ω / □ or higher.

[0057] [Example 1] In Example 1, the metal oxide was Ta2O5 and the metal oxynitride was TaON. In Example 1, under the conditions described in the embodiment, the ALD method cycle was repeated 1000 times to form a layer 102c of mixed Ta2O5 and TaON, approximately 100 nm thick, on a quartz substrate 101. The ambient temperature in the reaction chamber 201 was 90 degrees Celsius. After film formation, as a post-treatment, the layer 102c was irradiated with light from a light source with an emission line of 365 nm for 10 hours.

[0058] The chemical composition of layer 102c, a mixed layer of Ta2O5 and TaON prepared in Example 1, was evaluated by RBS / NRA / HFS methods. The results showed that the tantalum atom content [M] was 19.5 at%, the oxygen atom content [O] was 60.2 at%, the nitrogen atom content [N] was 2.1 at%, the carbon atom content [C] was 2.6 at%, the hydrogen atom content [H] was 15.6 at%, and the argon atom content [Ar] was 0.0 at%. Specifically, [O] / ([O]+[N])=96.6% and ([O]+[N]) / ([M]+[O]+[N])=76.2%.

[0059] Furthermore, the binding ratio between Ta2O5 and TaON was evaluated by ToF-SIMS and found to be [M-ON] / [MO] = 3.7%.

[0060] In addition, the light absorption rate at a wavelength of 365 nm was 0.03%, the average light absorption rate in the range from a wavelength of 400 nm to a wavelength of 800 nm was 0.00%, and the light absorption rate at a wavelength of 1000 nm was 0.01%. Very good light transmittance was obtained in each of the ultraviolet wavelength region, the visible light wavelength region, and the infrared wavelength region.

[0061] In addition, the refractive index of light at a wavelength of 550 nm was 2.01. Since the refractive index of light at a wavelength of 550 nm in the layer 102c of Example 1 is 2.0 or more, it is suitable for using the layer 102c as a high refractive index layer.

[0062] Furthermore, the sheet resistance was 5.6×10 12 Ω / □. Since the sheet resistance is 1.0×10 13 Ω / □ or less, the optical element 100 has good antistatic properties. When the optical element 100 is used in a clean room environment, dust attached to the optical element 100 can be easily removed with a lens blower.

[0063] [Example 2] In Example 2, the metal oxide was Ta2O5 and the metal oxynitride was TaON. In Example 2, under the conditions described in the embodiment, the cycle of the ALD method was repeated 1000 times to form a layer 102c, which is a mixed layer of Ta2O5 and TaON, about 100 nm on the quartz substrate 101. The environmental temperature in the reaction chamber 201 was 70°C. After film formation, as a post-treatment, the layer 102c was irradiated with light for 10 hours using a light source having a spectral line at a wavelength of 365 nm.

[0064] The chemical composition of layer 102c, a mixed layer of Ta2O5 and TaON prepared in Example 2, was evaluated by RBS / NRA / HFS methods. The results showed that the tantalum atom content [M] was 19.3 at%, the oxygen atom content [O] was 55.9 at%, the nitrogen atom content [N] was 2.7 at%, the carbon atom content [C] was 4.7 at%, the hydrogen atom content [H] was 17.3 at%, and the argon atom content [Ar] was 0.0 at%. Specifically, [O] / ([O]+[N])=95.3% and ([O]+[N]) / ([M]+[O]+[N])=75.2%.

[0065] Furthermore, the bonding ratio between Ta2O5 and TaON was evaluated by ToF-SIMS and found to be [M-ON] / [MO] = 15.9%.

[0066] Furthermore, the light absorption rate at a wavelength of 365 nm was 0.16%, the average light absorption rate in the range of wavelengths from 400 nm to 800 nm was 0.03%, and the light absorption rate at a wavelength of 1000 nm was 0.01%, indicating that very good light transmittance was obtained in the ultraviolet wavelength range, the visible light wavelength range, and the infrared wavelength range.

[0067] Furthermore, the refractive index of light at a wavelength of 550 nm was 2.02. Since layer 102c of this embodiment 2 has a refractive index of 2.0 or higher at a wavelength of 550 nm, layer 102c is suitable for use as a high refractive index layer.

[0068] Furthermore, the sheet resistance is 2.9 × 10 10 The resistance was Ω / □. The sheet resistance was 1.0 × 10 11 Because the static charge is less than or equal to Ω / □, the optical element 100 has excellent antistatic properties, and dust adhering to the optical element 100 can be easily removed with a lens blower, whether the optical element 100 is used in a general environment or a cleanroom environment.

[0069] [Example 3] In Example 3, the metal oxide was Ta2O5 and the metal oxynitride was TaON. In Example 3, under the conditions described in the embodiment, the ALD method cycle was repeated 1000 times to form a layer 102c of mixed Ta2O5 and TaON, approximately 100 nm thick, on a quartz substrate 101. The ambient temperature in the reaction chamber 201 was 150°C. After film formation, as a post-treatment, the layer 102c was irradiated with light from a light source with an emission line of 365 nm for 10 hours.

[0070] The chemical composition of layer 102c, a mixed layer of Ta2O5 and TaON prepared in Example 3, was evaluated by RBS / NRA / HFS methods. The results showed that the tantalum atom content [M] was 23.4 at%, the oxygen atom content [O] was 61.7 at%, the nitrogen atom content [N] was 1.0 at%, the carbon atom content [C] was 3.5 at%, the hydrogen atom content [H] was 10.4 at%, and the argon atom content [Ar] was 0.0 at%. Specifically, [O] / ([O]+[N])=98.4% and ([O]+[N]) / ([M]+[O]+[N])=72.8%.

[0071] The binding ratio between Ta2O5 and TaON was evaluated by ToF-SIMS and found to be [M-ON] / [MO] = 5.9%.

[0072] Furthermore, the light absorption rate at a wavelength of 365 nm was 0.62%, the average light absorption rate in the range of wavelengths from 400 nm to 800 nm was 0.93%, and the light absorption rate at a wavelength of 1000 nm was 0.01%, demonstrating good light transmittance in the ultraviolet, visible light, and infrared wavelength regions.

[0073] Furthermore, the refractive index of light at a wavelength of 550 nm was 2.07. Since layer 102c of this embodiment 3 has a refractive index of 2.0 or higher at a wavelength of 550 nm, layer 102c is suitable for use as a high refractive index layer.

[0074] Furthermore, the sheet resistance is 2.5 × 10 12 The resistance was Ω / □. The sheet resistance was 1.0 × 1013 Since the static charge is less than or equal to Ω / □, the optical element 100 has good antistatic properties, and when the optical element 100 is used in a cleanroom environment, dust adhering to the optical element 100 can be easily removed with a lens blower.

[0075] [Example 4] In Example 4, the metal oxide was Ta2O5 and the metal oxynitride was TaON. In Example 4, a mixed layer of Ta2O5 and TaON, layer 102c, was formed on a quartz substrate 101 by a reactive sputtering method different from that used in the embodiment, with a thickness of approximately 100 nm. The argon gas flow rate was 150 sccm, the oxygen gas flow rate was 30 sccm, the nitrogen gas flow rate was 40 sccm, and the hydrogen gas flow rate was 20 sccm. The sputtering target material was a 9-inch metallic tantalum (purity 99.9% by weight or higher) at 10 W / cm². 2 The film was deposited by applying the specified power. The distance between the substrate 101 and the target material was set to 100 mm. After film deposition, as a post-treatment, the layer 102c was irradiated with light from a light source with a wavelength of 365 nm for 10 hours.

[0076] The chemical composition of layer 102c, a mixed layer of Ta2O5 and TaON prepared in Example 4, was evaluated by RBS / NRA / HFS methods. The results showed that the tantalum atom content [M] was 26.6 at%, the oxygen atom content [O] was 62.0 at%, the nitrogen atom content [N] was 4.3 at%, the carbon atom content [C] was 0.0 at%, the hydrogen atom content [H] was 5.8 at%, and the argon atom content [Ar] was 1.3 at%. Specifically, [O] / ([O]+[N])=93.5% and ([O]+[N]) / ([M]+[O]+[N])=71.3%.

[0077] Furthermore, the light absorption rate at a wavelength of 365 nm was 9.77%, the average light absorption rate in the range of 400 nm to 800 nm was 0.93%, and the light absorption rate at a wavelength of 1000 nm was 0.01%, indicating that very good light transmittance was obtained in both the visible light wavelength range and the infrared wavelength range.

[0078] Furthermore, the refractive index of light at a wavelength of 550 nm was 2.17. Since layer 102c of this embodiment 4 has a refractive index of 2.0 or higher at a wavelength of 550 nm, layer 102c is suitable for use as a high refractive index layer.

[0079] Furthermore, the sheet resistance is 8.6 × 10 9 The resistance was Ω / □. The sheet resistance was 1.0 × 10 11 Because the static charge is less than or equal to Ω / □, the optical element 100 has excellent antistatic properties, and dust adhering to the optical element 100 can be easily removed with a lens blower, whether the optical element 100 is used in a general environment or a cleanroom environment.

[0080] [Example 5] In Example 5, the metal oxide was Ta2O5 and the metal oxynitride was TaON. In Example 5, a mixed layer of Ta2O5 and TaON, layer 102c, approximately 100 nm thick, was formed on a quartz substrate 101 by reactive sputtering, similar to the method described in Example 4. However, the nitrogen gas flow rate was set to 50 sccm. After film formation, as a post-treatment, layer 102c was irradiated with light from a light source with an emission line of 365 nm for 10 hours.

[0081] The chemical composition of layer 102c, a mixed layer of Ta2O5 and TaON prepared in Example 5, was evaluated by RBS / NRA / HFS methods. The results showed that the tantalum atom content [M] was 27.3 at%, the oxygen atom content [O] was 53.5 at%, the nitrogen atom content [N] was 12.4 at%, the carbon atom content [C] was 0.0 at%, the hydrogen atom content [H] was 5.5 at%, and the argon atom content [Ar] was 1.2 at%. Specifically, [O] / ([O]+[N])=81.1% and ([O]+[N]) / ([M]+[O]+[N])=70.7%.

[0082] Furthermore, the light absorption rate at a wavelength of 365 nm was 27.9%, the average light absorption rate in the range of 400 nm to 800 nm was 2.64%, and the light absorption rate at a wavelength of 1000 nm was 0.01%, demonstrating good light transmittance in both the visible light wavelength range and the infrared wavelength range.

[0083] Furthermore, the refractive index of light at a wavelength of 550 nm was 2.21. Since layer 102c of this embodiment 5 has a refractive index of 2.0 or higher at a wavelength of 550 nm, layer 102c is suitable for use as a high refractive index layer.

[0084] Furthermore, the sheet resistance is 6.0 × 10 9 The resistance was Ω / □. The sheet resistance was 1.0 × 10 11 Since the static charge is less than or equal to Ω / □, the optical element 100 has excellent antistatic properties, and whether the optical element 100 is used in a general environment or a cleanroom environment, dust adhering to the optical element 100 can be easily removed with a lens blower.

[0085] [Example 6] In Example 6, HfO2 was used as the metal oxide and HfON as the metal oxynitride. In Example 6, a mixed layer of HfO2 and HfON, layer 102c, approximately 100 nm thick, was formed on a quartz substrate 101 by repeating the ALD method cycle 1000 times under the conditions described in the embodiment. Tetrakis(ethylmethylamido)hafnium(IV) was used as the precursor, and the ambient temperature in the reaction chamber 201 was 150°C. After film formation, as a post-treatment, layer 102c was irradiated with light from a light source with an emission line of 365 nm for 10 hours.

[0086] The chemical composition of layer 102c, a mixed layer of HfO2 and HfON prepared in Example 6, was evaluated by RBS / NRA / HFS methods. The results showed that the hafnium atom content [M] was 22.4 at%, the oxygen atom content [O] was 65.6 at%, the nitrogen atom content [N] was 1.7 at%, the carbon atom content [C] was 2.1 at%, the hydrogen atom content [H] was 8.2 at%, and the argon atom content [Ar] was 0.0 at%. Specifically, [O] / ([O]+[N])=97.4% and ([O]+[N]) / ([M]+[O]+[N])=75.0%.

[0087] Furthermore, the light absorption rate at a wavelength of 365 nm was 0.20%, the average light absorption rate in the range of 400 nm to 800 nm was 0.08%, and the light absorption rate at a wavelength of 1000 nm was 0.14%, indicating that very good light transmittance was obtained in the ultraviolet wavelength range, the visible light wavelength range, and the infrared wavelength range.

[0088] Furthermore, the refractive index of light at a wavelength of 550 nm was 1.94.

[0089] Furthermore, the sheet resistance is 1.2 × 10 10 The resistance was Ω / □. The sheet resistance was 1.0 × 10 11 Because the static charge is less than or equal to Ω / □, the optical element 100 has excellent antistatic properties, and dust adhering to the optical element 100 can be easily removed with a lens blower, whether the optical element 100 is used in a general environment or a cleanroom environment.

[0090] [Example 7] In Example 6, ZrO2 was used as the metal oxide and ZrON as the metal oxynitride. In Example 7, under the conditions described in the embodiment, a mixed layer of ZrO2 and ZrON, layer 102c, of approximately 100 nm was formed on a quartz substrate 101 by repeating the ALD method cycle 1000 times. Tetrakis(ethylmethylamido)zirconium(IV) was used as the precursor, and the ambient temperature in the reaction chamber 201 was 150°C. After film formation, as a post-treatment, layer 102c was irradiated with light from a light source with an emission line of 365 nm for 10 hours.

[0091] The chemical composition of layer 102c, a mixed layer of ZrO2 and ZrON prepared in Example 7, was evaluated by RBS / NRA / HFS methods. The results showed that the zirconium atom content [M] was 22.7 at%, the oxygen atom content [O] was 66.9 at%, the nitrogen atom content [N] was 1.5 at%, the carbon atom content [C] was 1.4 at%, the hydrogen atom content [H] was 10.9 at%, and the argon atom content [Ar] was 0.0 at%. Specifically, [O] / ([O]+[N])=97.8% and ([O]+[N]) / ([M]+[O]+[N])=75.1%.

[0092] Furthermore, the light absorption rate at a wavelength of 365 nm was 0.30%, the average light absorption rate in the range of wavelengths from 400 nm to 800 nm was 0.02%, and the light absorption rate at a wavelength of 1000 nm was 0.02%, indicating that very good light transmittance was obtained in the ultraviolet wavelength range, the visible light wavelength range, and the infrared wavelength range.

[0093] Furthermore, the refractive index of light at a wavelength of 550 nm was 2.21. Since layer 102c of this embodiment 7 has a refractive index of 2.0 or higher at a wavelength of 550 nm, layer 102c is suitable for use as a high refractive index layer.

[0094] Furthermore, the sheet resistance is 8.7 × 10 10 The resistance was Ω / □. The sheet resistance was 1.0 × 10 11Because the static charge is less than or equal to Ω / □, the optical element 100 has excellent antistatic properties, and dust adhering to the optical element 100 can be easily removed with a lens blower, whether the optical element 100 is used in a general environment or a cleanroom environment.

[0095] [Comparative Example 1] In Comparative Example 1, a layer 102X, which is a Ta2O5 layer, was formed on a quartz substrate 101 by reactive sputtering, similar to the method described in Example 4, with a nitrogen gas flow rate of 0 sccm. After film formation, as a post-treatment, the layer 102X was irradiated with light from a light source with an emission line of 365 nm for 10 hours.

[0096] The chemical composition of layer 102X, a Ta2O5 layer prepared in Comparative Example 1, was evaluated by RBS / NRA / HFS methods. The results showed that the tantalum atom content [M] was 26.3 at%, the oxygen atom content [O] was 66.5 at%, the nitrogen atom content [N] was 0.0 at%, the carbon atom content [C] was 0.0 at%, the hydrogen atom content [H] was 5.9 at%, and the argon atom content [Ar] was 1.3 at%. Specifically, [O] / ([O]+[N])=100% and ([O]+[N]) / ([M]+[O]+[N])=71.7%. The refractive index of light at a wavelength of 550 nm was 2.16.

[0097] Furthermore, the light absorption rate at a wavelength of 365 nm was 0.03%, the average light absorption rate in the range of wavelengths from 400 nm to 800 nm was 0.00%, and the light absorption rate at a wavelength of 1000 nm was 0.00%, indicating that very good light transmittance was obtained in the ultraviolet wavelength range, the visible light wavelength range, and the infrared wavelength range.

[0098] However, the sheet resistance is 1.0 × 10 14 The value was Ω / □ or greater, and good antistatic properties could not be obtained with the optical element 100X of Comparative Example 1.

[0099] [Comparative Example 2] In Comparative Example 2, a TaON layer, layer 102X, approximately 100 nm in thickness was formed on a quartz substrate 101 by reactive sputtering, similar to the method described in Example 4. However, the oxygen gas flow rate was 20 sccm and the nitrogen gas flow rate was 80 sccm. After film formation, as a post-treatment, layer 102X was irradiated with light from a light source with an emission line of 365 nm for 10 hours.

[0100] The chemical composition of layer 102X, a TaON layer fabricated in Comparative Example 2, was evaluated by RBS / NRA / HFS methods. The results showed that the tantalum atom content [M] was 28.9 at%, the oxygen atom content [O] was 33.8 at%, the nitrogen atom content [N] was 31.3 at%, the carbon atom content [C] was 0.0 at%, the hydrogen atom content [H] was 4.9 at%, and the argon atom content [Ar] was 1.1 at%. Specifically, [O] / ([O]+[N])=51.9% and ([O]+[N]) / ([M]+[O]+[N])=69.2%. The refractive index of light at a wavelength of 550 nm was 2.29.

[0101] In Comparative Example 2, the composition ratio of oxygen atoms [O] to nitrogen atoms [N] is approximately 1:1, so it is determined that only TaON is produced in layer 102X.

[0102] Also, the sheet resistance is 3.1 × 10 2 The resistance was Ω / □. The sheet resistance was 1.0 × 10 11 Since the ratio is less than or equal to Ω / □, the optical element 100 exhibits very good antistatic properties.

[0103] However, the light absorption rate at a wavelength of 365 nm was 69.7%, the average light absorption rate in the wavelength range from 400 nm to 800 nm was 6.59%, and the light absorption rate at a wavelength of 1000 nm was 0.02%. In Comparative Example 2, optical element 100X showed good light transmittance in the infrared wavelength range, but did not show good light transmittance in the ultraviolet wavelength range or the visible light wavelength range.

[0104] Figure 5 is a table showing the experimental results for Examples 1-7 and Comparative Examples 1 and 2. In all of the layers 102c of Examples 1-7, antistatic properties were obtained, and excellent light transmittance was obtained when used in the visible light wavelength range and the infrared wavelength range. Specifically, in all of the layers 102c of Examples 1-7, the sheet resistance was 1.0 × 10⁻⁶. 13 The ratio was less than or equal to Ω / □, the average light absorption rate in the wavelength range from 400 nm to 800 nm was 3.0% or less, and the light absorption rate at 1000 nm was 1.0% or less.

[0105] Figure 6 is a graph showing the light absorption rate against the wavelength of light for Example 1 and Comparative Example 2. As shown in Figure 6, in Example 1, the absorption rate is improved compared to Comparative Example 2, particularly at a wavelength of 365 nm and in the wavelength range from 400 nm to 800 nm.

[0106] Figures 7(a) and 7(b) are graphs showing the results of time-of-flight secondary ion mass spectrometry for Example 2 and Comparative Example 1. As shown in Figure 7(a), for Example 2, a peak in ionic intensity [M-ON] due to metal oxynitride (TaON) appears around mass number 211. However, for Comparative Example 1, a peak in ionic intensity [M-ON] due to metal oxynitride (TaON) does not appear around mass number 211. On the other hand, as shown in Figure 7(b), in both Example 2 and Comparative Example 1, a peak in ionic intensity due to metal oxide (Ta2O5) appears around mass number 442.

[0107] Figure 8 is a graph showing the average light absorption coefficient in the visible light wavelength range for [O] / ([O]+[N]) for Examples 1-7 and Comparative Example 2. In Figure 8, the experimental results for Examples 1-7 and Comparative Example 2 are plotted as black circles, and multiple black circles are interpolated with straight lines (dashed lines).

[0108] Figure 9 is a graph showing the sheet resistance against [O] / ([O]+[N]) for Examples 1-7 and Comparative Example 1. In Comparative Example 1, where [O] / ([O]+[N])=100%, the sheet resistance is 1.0 × 10⁻⁶.14 The result was Ω / □ or greater, indicating low antistatic properties. In Figure 9, the experimental results for Examples 1-7 and Comparative Example 1 are plotted as black circles, and the black circle representing Example 3 and the black circle representing Comparative Example 1 are interpolated with a straight line (dashed line).

[0109] From the interpolation line that interpolates between the black circle representing Comparative Example 2 and the black circle representing Example 5 in Figure 8, it is found that when [O] / ([O]+[N]) is lower than 80.0%, the average light absorption rate in the visible light wavelength range (from 400 nm to 800 nm) is 3.0%. Therefore, as shown in Figure 8, by satisfying 80.0% ≤ [O] / ([O]+[N]), the average light absorption rate in the visible light wavelength range (from 400 nm to 800 nm) becomes 3.0% or less.

[0110] Furthermore, from the interpolation line that interpolates between the black circle representing Comparative Example 1 and the black circle representing Example 1 in Figure 9, it is found that [O] / ([O]+[N]) is 99.0% and the sheet resistance is 1.0 × 10⁻⁶. 13 The ratio becomes Ω / □. Therefore, as shown in Figure 9, by satisfying [O] / ([O]+[N])≦99.0%, the sheet resistance becomes 1.0×10 13 It will be less than or equal to Ω / □.

[0111] The sheet resistance is 1.0 × 10 in the range including Examples 1 to 7. 13 The reason why the resistance is less than Ω / □ is not clear, but it is speculated that the metal oxynitrides present in small amounts within layer 102c, which contains metal oxides and metal oxynitrides, preferentially become the current conduction path, resulting in a dramatic decrease in sheet resistance even with a low nitrogen content of 80.0% ≤ [O] / ([O] + [N]) ≤ 99.0%.

[0112] In this embodiment, by satisfying 80.0% ≤ [O] / ([O] + [N]) ≤ 99.0%, the sheet resistance is 1.0 × 10 13 The Ω / □ ratio is less than or equal to 3.0% or less, and the average light absorption rate in the visible light wavelength range (from 400 nm to 800 nm) is 3.0% or less. In other words, the antistatic properties of the optical film 102 are improved, and the optical performance of the optical film 102 is improved.

[0113] Furthermore, from the experimental results of Examples 1 to 7 shown in Figure 9, by satisfying [O] / ([O]+[N])≦98.4%, the sheet resistance is 1.0×10 13 The value becomes lower than Ω / □. In other words, the antistatic properties of the optical film 102 are further improved.

[0114] Furthermore, as shown in Figure 8, experimental results from Examples 1-4 and 6-7 show that satisfying 93.5% ≤ [O] / ([O] + [N]) results in an average light absorption rate of 1.0% or less in the visible light wavelength range (from 400 nm to 800 nm). The reason why the average light absorption rate in the visible light wavelength range is 1.0% or less is not clear, but it is presumed that the influence of band gap absorption originating from oxynitrides is reduced. In summary, satisfying 93.5% ≤ [O] / ([O] + [N]) further improves the optical performance of optical film 102.

[0115] Furthermore, focusing on the sheet resistance, as shown in Figure 9, if [O] / ([O]+[N])≦95.3%, the sheet resistance is 1.0×10 11 The ratio becomes Ω / □ or less. Furthermore, the average light absorption rate in the visible light wavelength range (from 400 nm to 800 nm) is 3.0% or less. This further improves the antistatic properties of the optical film 102. For example, dust adhering to the surface of the optical element 100 can be easily removed by a blower or the like in both general and cleanroom environments.

[0116] Furthermore, based on the table shown in Figure 5, the inventors conducted thorough research and found that, regarding layer 102c containing metal oxides and metal oxynitrides, by focusing not only on the content of each atom but also on the content ratios of [M], [O], and [N], as well as the bonding ratio between metal oxides and metal oxynitrides, there is a relationship between the film state and light transmittance and antistatic properties.

[0117] The following describes the conditions under which excellent light transmittance can be obtained for layer 102c, which contains metal oxides and metal oxynitrides, in the ultraviolet wavelength range (wavelength 365 nm).

[0118] Figure 10 is a graph showing the light absorption rates in the ultraviolet wavelength range (wavelength 365 nm) for ([O]+[N]) / ([M]+[O]+[N]) for Examples 1-7 and Comparative Example 2. In Figure 10, the experimental results for Examples 1-7 and Comparative Example 2 are plotted as black circles, and multiple black circles are interpolated with straight lines (dashed lines).

[0119] From Figures 5 and 10, it was found that Examples 1-3 and 6-7 were the only ones in which the light absorption rate in the ultraviolet wavelength region (wavelength 365 nm) was 1.0% or less. From the results of Examples 1-3 and 6-7, when 95.3% ≤ [O] / ([O]+[N]) ≤ 99.0% and ([O]+[N]) / ([M]+[O]+[N]) ≥ 72.8%, the average light absorption rate in the visible light wavelength region is 3.0% or less, the light absorption rate in the ultraviolet wavelength region (wavelength 365 nm) is 1.0% or less, and the sheet resistance is 1.0 × 10⁻⁶. 13 The ratio becomes Ω / □ or less. Assuming that the optical element 100 is used in the ultraviolet wavelength region, in addition to eliminating the effect of band gap absorption originating from oxynitride, setting ([O]+[N]) / ([M]+[O]+[N])≧72.8% reduces the effect of absorption due to oxygen and nitrogen bonding defects, and it is presumed that high light transmittance in the ultraviolet wavelength region can be obtained. Therefore, the antistatic properties of the optical film 102 are improved, and the optical performance of the optical film 102 (especially the light transmittance in ultraviolet light) is further improved.

[0120] Figure 11 is a graph showing the light absorption rates in the ultraviolet wavelength range (wavelength 365 nm) for ([O]+[N]) / ([M]+[O]+[N]) for Examples 1-3 and 6-7. In Figure 11, the experimental results for Examples 1-3 and 6-7 are plotted as black circles.

[0121] From Figures 5 and 11, it was found that Examples 1-2, 6-7 were the only ones in which the light absorption rate in the ultraviolet wavelength region (wavelength 365 nm) was 1% or less. From the results of Examples 1-2, 6-7, when 95.3% ≤ [O] / ([O]+[N]) ≤ 99.0% and ([O]+[N]) / ([M]+[O]+[N]) ≥ 75.0%, the average light absorption rate in the visible light wavelength region is 3.0% or less, the light absorption rate in the ultraviolet wavelength region (wavelength 365 nm) is 0.3% or less, and the sheet resistance is 1.0 × 10⁻⁶. 13 The ratio becomes Ω / □ or less. Therefore, the antistatic properties of the optical film 102 are improved, and the optical performance of the optical film 102 (especially the light transmittance of ultraviolet light) is further improved.

[0122] Figure 12 is a graph showing the light absorption rate in the ultraviolet wavelength range (wavelength 365 nm) for the bond ratio [M-ON] / [MO] for Examples 1-3. In Figure 12, the experimental results for Examples 1-3 are plotted as black circles.

[0123] From Figures 5 and 12, it was in Example 1 that the light absorption rate in the ultraviolet wavelength region (wavelength 365 nm) was 1% or less. From the results of Example 1, when 95.3% ≤ [O] / ([O] + [N]) ≤ 99.0%, ([O] + [N]) / ([M] + [O] + [N]) ≥ 75.0%, and the bond ratio [M-ON] / [MO] evaluated by ToF-SIMS is ≤ 5.0%, the average light absorption rate in the visible light wavelength region is 3.0% or less, the light absorption rate in the ultraviolet wavelength region (wavelength 365 nm) is 0.1% or less, and the sheet resistance is 1.0 × 10⁻⁶ 13 The ratio becomes Ω / □ or less. By satisfying the bond ratio [M-ON] / [MO] ≤ 5.0%, the effect of band gap absorption by the metal oxynitride can be reduced, and it is presumed that very high light transmittance of 0.1% or less at a wavelength of 365 nm was obtained. Therefore, the antistatic properties of the optical film 102 are improved, and the optical performance of the optical film 102 (especially the light transmittance of ultraviolet light) is further improved.

[0124] [Example 8] Figure 13(a) is a diagram illustrating the layer structure of the optical film 102 according to Example 8. The optical element 100 fabricated in Example 8 is a light-transmitting optical element. The optical film 102 is an anti-reflective film having an anti-reflective structure. The substrate 101 was made of quartz glass. The optical film 102 was a multilayer film having a first layer, a second layer, a third layer, and a fourth layer. The first layer, second layer, third layer, and fourth layer were arranged in this order from the substrate 101 toward the surface of the optical element 100. The first layer is a high refractive index layer 102b, the second layer is a low refractive index layer 102a, the third layer is a high refractive index layer 102b, and the fourth layer is a low refractive index layer 102a. Thus, in Example 8, the optical film 102 was formed by alternately stacking four layers of high refractive index layers 102b and low refractive index layers 102a.

[0125] In Example 8, the high refractive index layer 102b was layer 102c, which is a mixed layer containing metal oxide (Ta2O5) and metal oxynitride (TaON) using the conditions shown in Example 1. The low refractive index layer 102a was a layer containing silicon oxide (SiO2). To maximize the transmittance characteristics at a wavelength of 365 nm, the physical film thickness of each layer was optimized to determine the configuration of the optical film 102. Figure 13(a) shows the materials used in the optical element of Example 8, the physical film thickness of each layer, and the refractive index of light at a wavelength of 550 nm.

[0126] For the optical element 100 having the configuration shown in Figure 13(a), the light transmittance was measured with a light incident angle of 5 degrees. Figure 13(b) is a graph showing the light transmittance of the optical element 100 according to Example 8 against the wavelength of light. A very good result was obtained, with a light transmittance of 99.9% or more at a wavelength of 365 nm, and good results were also obtained regarding antistatic properties.

[0127] [Example 9] Figure 14(a) is a diagram illustrating the layer structure of the optical film 102 according to Example 9. The optical element 100 fabricated in Example 9 is a light-transmitting optical element. The optical film 102 is an anti-reflective film having an anti-reflective structure. The substrate 101 is made of quartz glass. The optical film 102 is a multilayer film having a first layer, a second layer, a third layer, a fourth layer, a fifth layer, and a sixth layer. The first layer, second layer, third layer, fourth layer, fifth layer, and sixth layer are arranged in this order from the substrate 101 toward the surface of the optical element 100. The first layer is a high refractive index layer 102b, the second layer is a low refractive index layer 102a, the third layer is a high refractive index layer 102b, the fourth layer is a low refractive index layer 102a, the fifth layer is a high refractive index layer 102b, and the sixth layer is the outermost layer. Thus, in Example 9, the optical film 102 was formed by alternately stacking five layers of high refractive index layer 102b and low refractive index layer 102a, and placing a sixth layer on the outermost surface.

[0128] In Example 9, the high refractive index layer 102b was layer 102c, a mixed layer containing metal oxide (Ta2O5) and metal oxynitride (TaON) using the conditions shown in Example 1. The low refractive index layer 102a was a layer containing silicon oxide (SiO2). The outermost layer was a layer containing magnesium fluoride (MgF2). To maximize the transmittance characteristics in the wavelength range from 400 to 700 nm, the physical film thickness of each layer was optimized to determine the configuration of the optical film 102. Figure 14(a) shows the materials used in the optical element of Example 9, the physical film thickness of each layer, and the refractive index of light at a wavelength of 550 nm.

[0129] For the optical element 100 having the configuration shown in Figure 14(a), the light transmittance was measured with a light incident angle of 5 degrees. Figure 14(b) is a graph showing the light transmittance of the optical element 100 according to Example 9 against the wavelength of light. An average light transmittance of 99.6% or more was obtained in the region from wavelength 400 nm to wavelength 700 nm, which is a very good result, and good results were also obtained regarding antistatic properties.

[0130] In Example 8, a transmissive optical element 100 was fabricated to match the ultraviolet wavelength range of 365 nm, and in Example 9, a transmissive optical element 100 was fabricated to match the visible light wavelength range from 400 nm to 700 nm. However, the invention is not limited to these examples. The low refractive index material, high refractive index material, number of layers, and physical film thickness can be set to optimize the optical properties according to the wavelength range in which the optical element 100 is used.

[0131] [Other variations] This disclosure is not limited to the embodiments described above, and many modifications are possible within the technical concept of this disclosure. Furthermore, the effects described in these embodiments are merely a list of the most preferred effects and are not limited to this disclosure.

[0132] The above disclosure of embodiments includes the following sections.

[0133] (Section 1) An optical film disposed on a substrate and comprising one or more layers, At least one layer of the optical film comprises a metal oxide and a metal oxynitride. When the oxygen atom content in at least one of the layers is [O]at% and the nitrogen atom content is [N]at%, Satisfying 80.0% ≤ [O] / ([O]+[N]) ≤ 99.0%, An optical film characterized by the following features.

[0134] (Section 2) [O] / ([O]+[N])≦98.4% The optical film according to item 1, characterized in that it is a film.

[0135] (Section 3) Satisfying 93.5% ≤ [O] / ([O] + [N]), The optical film according to item 1 or 2, characterized in that

[0136] (Section 4) The condition 95.3% ≤ [O] / ([O] + [N]) is satisfied, and When the content of metal atoms in the at least one layer is [M]at%, ([O]+[N]) / ([M]+[O]+[N]) ≥ 72.8% The optical film according to any one of claims 1 to 3, characterized in that it is an optical film.

[0137] (Section 5) The condition 95.3% ≤ [O] / ([O] + [N]) is satisfied, and When the content of metal atoms in the at least one layer is [M]at%, ([O]+[N]) / ([M]+[O]+[N])≧75.0% The optical film according to any one of claims 1 to 3, characterized in that it is an optical film.

[0138] (Section 6) In the analysis of at least one layer by time-of-flight secondary ion mass spectrometry, when the ionic intensity due to the metal oxynitride is denoted as [M-ON] and the ionic intensity due to the metal oxide is denoted as [MO], [M-ON] / [MO] ≤ 5.0% The optical film according to item 4 or 5, characterized by the features described herein.

[0139] (Section 7) [O] / ([O]+[N])≦95.3% The optical film according to item 1, characterized in that it is a film.

[0140] (Section 8) The optical film comprises the plurality of layers, The plurality of layers include one or more high refractive index layers and one or more low refractive index layers. The at least one layer is at least one of the one or more high refractive index layers. The optical film according to item 1, characterized in that it is a film.

[0141] (Section 9) The aforementioned high refractive index layer is a layer whose refractive index at a wavelength of light of 550 nm is 2.0 or higher. The optical film according to item 8, characterized in that

[0142] (Section 10) The metal element contained in the high refractive index layer is at least one of Ta, Ti, Zr, V, Nb, and Cr. The optical film according to item 9, characterized by the features described herein.

[0143] (Section 11) Substrate and, A comprising an optical film according to any one of items 1 to 10, disposed on the substrate, An optical element characterized by the following features.

[0144] (Section 12) The material of the substrate is glass or plastic. The optical element according to item 11, characterized in that

[0145] (Section 13) The optical film is an anti-reflective film. The optical element according to item 11 or 12, characterized in that

[0146] (Section 14) The main unit of the device, The device comprises an outer casing that covers at least a part of the main body of the device, The device body has an optical element as described in any one of items 11 to 13. An optical instrument characterized by the following features. [Explanation of Symbols]

[0147] 100...Optical element, 101...Substrate, 102...Optical film, 102c...Layer

Claims

1. An optical film disposed on a substrate and comprising one or more layers, At least one layer of the optical film comprises a metal oxide and a metal oxynitride. When the oxygen atom content in at least one of the layers is [O] at% and the nitrogen atom content is [N] at%, The following conditions are met: 80.0% ≤ [O] / ([O] + [N]) ≤ 99.0% An optical film characterized by the following features.

2. [O] / ([O]+[N]) ≤ 98.4% The optical film according to feature 1.

3. 93.5% ≤ [O] / ([O] + [N]) The optical film according to feature 1.

4. 95.3% ≤ [O] / ([O] + [N]) and, When the content of metal atoms in the at least one layer is [M] at%, ([O] + [N]) / ([M] + [O] + [N]) ≥ 72.8% The optical film according to feature 1.

5. 95.3% ≤ [O] / ([O] + [N]) and, When the content of metal atoms in the at least one layer is [M] at%, ([O] + [N]) / ([M] + [O] + [N]) ≥ 75.0% The optical film according to feature 1.

6. In the analysis of at least one layer by time-of-flight secondary ion mass spectrometry, when the ionic intensity due to the metal oxynitride is denoted as [M-ON] and the ionic intensity due to the metal oxide is denoted as [M-O], [M-ON] / [M-O] ≤ 5.0% The optical film according to feature 5.

7. [O] / ([O]+[N]) ≤ 95.3% The optical film according to feature 1.

8. The optical film comprises the plurality of layers, The plurality of layers include one or more high refractive index layers and one or more low refractive index layers. The at least one layer is at least one of the one or more high refractive index layers. The optical film according to feature 1.

9. The aforementioned high refractive index layer is a layer whose refractive index at a wavelength of light of 550 nm is 2.0 or higher. The optical film according to feature 8.

10. The metal element contained in the high refractive index layer is at least one of Ta, Ti, Zr, V, Nb, and Cr. The optical film according to feature 9.

11. Substrate and, The optical film according to claim 1 is disposed on the substrate, An optical element characterized by the following features.

12. The material of the substrate is glass or plastic. The optical element according to feature 11.

13. The optical film is an anti-reflective film. The optical element according to feature 11.

14. The main unit of the device, The device comprises an outer casing that covers at least a part of the main body of the device, The device body has an optical element according to any one of claims 11 to 13. An optical instrument characterized by the following features.

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