JP2006119525A - Antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer antireflection film with single layer film properties of MgF2 capable of both side processing using only a sputtering method in the case of processing a lens which needs multilayer antireflection film properties at one side and single layer film properties of MgF2 at the other side. <P>SOLUTION: In the antireflection film composed of ≥6 alternate layers of a high-refractive-index film whose refractive index at λ0 is ≥2.1 and a low-refractive-index film whose refractive index at λ0 is ≤1.65, wherein λ0 represents a standard wavelength of the antireflection film, the air side final layer is formed of an SiO2 film, and the antireflection film satisfies the expression (1): ¾R(λ)-R single(λ)¾≤0.4% wherein R(λ) represents a reflectance of each wavelength of the visible range (405-700 nm); and R single(λ) represents a reflectance of each wavelength of a single layer MgF2 film having the same standard wavelength λ0. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a film configuration of an antireflection film provided on the surface of a camera lens or the like, and more particularly to an antireflection film for color balance adjustment formed using a sputtering method.

  Conventionally, as an antireflection film provided on the surface of a glass material such as a camera lens, a MgF2 single layer film and a multilayer antireflection film in which an MgF2 film is provided on the air-side final layer are well known. Multi-layer anti-reflection coatings have better anti-reflection performance in the visible range than single-layer coatings, and are often used for lens surfaces in camera barrels. The color balance (color) of light is biased, and therefore, an MgF 2 single layer film is used for color balance adjustment. In addition, the MgF2 single layer film has an advantage that the change in the color of the reflected light depending on the film thickness unevenness generated in the lens shape having a strong curvature is inconspicuous. Therefore, a lens having a multilayer antireflection film on one side and a MgF2 single layer film on the other side is required.

Usually, in the processing of the antireflection film on the lens, since the final layer of the multilayer antireflection film is an MgF2 film, a vapor deposition apparatus (including an assist) that can process the multilayer antireflection film is used. However, only the processing of the multilayer antireflection film is performed by a sputtering method. For example, Patent Document 1 and Patent Document 2 are listed. Both are multi-layer antireflection films composed of five or six layers composed of a high refractive index film and a low refractive index film. In the case of the sputtering method, it is difficult to obtain a good quality MgF2 film at the same cost as the vapor deposition method, and therefore the final layer of the multilayer antireflection film is composed of a SiO2 film.
Japanese Patent Publication No.7-111482 Japanese Patent No. 2656634

  However, in the conventional example, when processing the multilayer antireflection film on one side of the lens by using the sputtering method, in order to process the MgF2 single layer film on the other side, the vapor deposition method must be used. Since different devices are used for each side, there is a problem of cost disadvantage.

  If the sputtering method is used to process another single-sided MgF2 single layer film, sputtering in a fluorine gas atmosphere is required to obtain a good quality MgF2 film. There was a disadvantage.

  In addition, when a SiO2 single layer film that can be applied by sputtering instead of the other single-sided MgF2 single layer film is used, the refractive index is higher than that of the MgF2 film, which is insufficient for the antireflection effect and color balance adjustment. There was a problem.

  The object of the present invention is to process a lens that requires a multilayer antireflection film characteristic on one side and a single-layer film characteristic of MgF2 on the other side. An object of the present invention is to provide a multilayer antireflection film having single layer film characteristics.

In order to achieve the above object, according to a first invention of the present application, when the reference wavelength of the antireflection film is λ0, a high refractive index film having a refractive index at λ0 of 2.1 or more and a low refractive index of 1.65 or less. In the antireflection film of 6 layers or more composed of alternating layers of refractive index films, the air-side final layer is formed of a SiO2 film, and the reflectance of each wavelength in the visible region (405 to 700 nm) is the same as R (λ). When the reflectance of each wavelength of a single layer MgF2 film having a reference wavelength of λ0 is R single (λ),
| R (λ) −R single (λ) | ≦ 0.4% (1)
The expression (1) is satisfied.

  In the above configuration, the present invention exhibits the same effect as a single layer MgF 2 film as an antireflection film for color balance adjustment. In the case of the characteristics exceeding 0.3% in the formula (1), the color is different from that of the single layer MgF 2 film.

According to a second invention of the present application, in the antireflection film according to the first invention, when the reference wavelength is λ0, a high refractive index film (nH) having a refractive index at λ0 of 2.1 or more and 1 A six-layer antireflection film composed of alternating layers of low refractive index films (nL) of .65 or less, and the optical film thickness (nH * d, nL * d) at λ0 of each layer from the substrate side,
0.11 ≧ nH * d1 / λ0 ≧ 0.01
0.26 ≧ nL * d2 / λ0 ≧ 0.05
0.23 ≧ nH * d3 / λ0 ≧ 0.03
0.21 ≧ nL * d4 / λ0 ≧ 0.04
0.22 ≧ nH * d5 / λ0 ≧ 0.03
0.38 ≧ nL * d6 / λ0 ≧ 0.26 (21)
The equation (21) is satisfied, and 0.94 ≧ total optical film thickness / λ0 ≧ 0.8 (22)
The expression (22) is satisfied.

  In the above configuration, the present invention exhibits the same effect as a single layer MgF 2 film as an antireflection film for color balance adjustment.

According to a third invention of the present application, in the antireflection film according to the first invention, when the reference wavelength of the antireflection film is λ0, a high refractive index film having a refractive index at λ0 of 2.1 or more (nH ) And a low refractive index film (nL) having a refractive index of 1.65 or less (7 layers), and the optical film thickness (nH * d, nL * d) at λ0 of each layer is from the substrate side. ,
0.13 ≧ nL * d1 / λ0 ≧ 0.03
0.13 ≧ nH * d2 / λ0 ≧ 0.01
0.18 ≧ nL * d3 / λ0 ≧ 0.09
0.2 ≧ nH * d4 / λ0 ≧ 0.03
0.2 ≧ nL * d5 / λ0 ≧ 0.07
0.21 ≧ nH * d6 / λ0 ≧ 0.03
0.37 ≧ nL * d7 / λ0 ≧ 0.28 (31)
(31) is satisfied, and 1.12 ≧ total optical film thickness / λ0 ≧ 0.81 (32)
The expression (32) is satisfied.

  In the above configuration, the present invention exhibits the same effect as a single layer MgF 2 film as an antireflection film for color balance adjustment.

According to a fourth aspect of the present application, in the antireflective film according to the first aspect, when the reference wavelength of the antireflective film is λ0, a high refractive index film having a refractive index at λ0 of 2.1 or more (nH ) And a low refractive index film (nL) of 1.65 or less, and an eight-layer antireflection film in which the optical film thickness (nH * d, nL * d) at λ0 of each layer is from the substrate side. ,
0.09 ≧ nH * d1 / λ0 ≧ 0.01
0.26 ≧ nL * d2 / λ0 ≧ 0.06
0.19 ≧ nH * d3 / λ0 ≧ 0.03
0.2 ≧ nL * d4 / λ0 ≧ 0.04
0.3 ≧ nH * d5 / λ0 ≧ 0.05
0.18 ≧ nL * d6 / λ0 ≧ 0.02
0.24 ≧ nH * d7 / λ0 ≧ 0.03
0.36 ≧ nL * d8 / λ0 ≧ 0.26 (41)
(41) is satisfied, and 1.2 ≧ total optical film thickness / λ0 ≧ 1.01 (42)
The expression (42) is satisfied.

  In the above configuration, the present invention exhibits the same effect as a single layer MgF 2 film as an antireflection film for color balance adjustment.

  According to a fifth aspect of the present application, in the antireflection film according to any one of the second, third, and fourth aspects, the entire layer is formed by a sputtering method.

  In the above configuration, the present invention shows an effect as an antireflection film for color balance adjustment, which is more durable (film strength, cloudiness, characteristic aging) than the single layer MgF2 film.

  By using the antireflection film of the present invention configured as described above, the same color balance adjustment effect as that of the single layer MgF 2 film can be obtained. Further, according to the second, third and fourth inventions, by using an Al2O3 film as the first low refractive index film from the substrate side, the durability (film strength, It is possible to obtain an antireflection film for color balance adjustment which is excellent in spider and characteristic aging. Further, by forming all the layers by sputtering, it is possible to obtain an antireflection film for color balance adjustment that is more durable (film strength, cloudiness, characteristic aging) than a single-layer MgF2 film. In addition, by forming all the layers by sputtering, it is possible to process both surfaces of the lens using only sputtering.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

  Using reactive DC sputtering, TiO2 on each glass substrate BSL7 (n = 1.52), BSM15 (n = 1.62), BaSF08 (n = 1.72), TIH6 (n = 1.81). A six-layer antireflection film composed of alternating layers of (n = 2.53) and SiO2 (n = 1.47) was formed. The target characteristic is a characteristic (magenta) obtained with an MgF2 (n = 1.38) single layer of n * d = 125 nm when λ0 = 500 nm. As the target material, metal Ti and single crystal Si were used. Table 1 shows the film configuration, and FIG. 1 shows the film characteristics when the incident angle is 0 degree. In FIG. 1, the vertical axis represents reflectance (%), and the horizontal axis represents wavelength (nm). In the configuration of Table 1, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less.

  Using reactive DC sputtering, a six-layer antireflection film composed of alternating layers of Ta 2 O 5 (n = 2.18) and SiO 2 was formed as in Example 1. As the target material, metal Ta and single crystal Si were used. Table 2 shows the film configuration, and FIG. 2 shows the film characteristics. In the configuration of Table 2, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less.

  Using reactive DC sputtering, a six-layer antireflection film composed of alternating layers of TiO 2 and SiO 2 was formed as in Example 1. However, the second layer was an AL2O3 film (n = 1.63). As the target material, metal Ti, metal Al, and single crystal Si were used. Table 3 shows the film configuration, and FIG. 3 shows the film characteristics. In the case of this configuration, a ripple is generated in the characteristics for BSL7, which is not suitable. In the configuration of Table 2, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less.

  Using reactive DC sputtering, a six-layer antireflection film composed of alternating layers of Ta 2 O 5 and SiO 2 was formed as in Example 1. However, the second layer was an AL2O3 film (n = 1.63). As the target material, metal Ta, metal Al, and single crystal Si were used. Table 4 shows the film structure, and FIG. 4 shows the film characteristics. In the case of this configuration, a ripple is generated in the characteristics for BSL7, which is not suitable. In the configuration of Table 4, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less.

  Using a reactive DC sputtering method, a seven-layer antireflection film composed of alternating layers of TiO 2 and SiO 2 was formed as in Example 1. However, the first layer was an AL2O3 film (n = 1.63). As the target material, metal Ti, metal Al, and single crystal Si were used. Table 5 shows the film configuration, and FIG. 5 shows the film characteristics. In the configuration of Table 5, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less. In this configuration, the durability (spider) was improved by using the AL2O3 film as the first layer. If the thickness of the AL2O3 film is 0.03λ0 or less, the effect of preventing spiders is insufficient, and if it is 0.13λ0 or more, the antireflection characteristics and productivity are poor.

  Using a reactive DC sputtering method, a seven-layer antireflection film composed of alternating layers of Ta 2 O 5 and SiO 2 was formed as in Example 5. However, the first layer was an AL2O3 film (n = 1.63). As the target material, metal Ta, metal Al, and single crystal Si were used. Table 6 shows the film structure, and FIG. 6 shows the film characteristics. In the configuration of Table 6, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less. In this configuration, the durability (spider) was improved by using the AL2O3 film as the first layer.

  Using reactive DC sputtering, an eight-layer antireflection film composed of alternating layers of TiO 2 and SiO 2 was formed in the same manner as in Example 1. As the target material, metal Ti and single crystal Si were used. Table 7 shows the film structure, and FIG. 7 shows the film characteristics. In the configuration of Table 7, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less.

  Using reactive DC sputtering, an eight-layer antireflection film composed of alternating layers of Ta 2 O 5 and SiO 2 was formed in the same manner as in Example 7. As the target material, metal Ta and single crystal Si were used. Table 8 shows the film configuration, and FIG. 8 shows the film characteristics. In the configuration of Table 8, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less.

  Using a reactive DC sputtering method, an 8-layer antireflection film composed of alternating layers of TiO 2 and SiO 2 was formed in the same manner as in Example 7. However, the second layer was an AL2O3 film. As the target material, metal Ti, metal Al, and single crystal Si were used. Table 9 shows the film configuration, and FIG. 9 shows the film characteristics. In the case of this configuration, a ripple is generated in the characteristics for BSL7, which is not suitable. In the configuration of Table 9, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less.

  Using reactive DC sputtering, an eight-layer antireflection film composed of alternating layers of Ta 2 O 5 and SiO 2 was formed in the same manner as in Example 7. However, the second layer was an AL2O3 film. As the target material, metal Ta, metal Al, and single crystal Si were used. Table 10 shows the film configuration, and FIG. 10 shows the film characteristics. In the case of this configuration, a ripple is generated in the characteristics for BSL7, which is not suitable. In the configuration of Table 10, when the same λ0, the difference in reflectance from the single layer MgF 2 film was 0.4% or less.

[Conventional example 1]
MgF2 (n = n = 1.81) on each glass substrate BSL7 (n = 1.52), BSM15 (n = 1.62), BaSF08 (n = 1.72), TIH6 (n = 1.81) by vacuum evaporation. 1.38) An antireflection film consisting of a single layer was formed. The target characteristic is a characteristic (magenta) obtained with a single layer of n * d = 125 nm when λ0 = 500 nm. Table 11 shows the film configuration, and FIG. 11 shows the film characteristics. The vapor deposition single layer film is easy to produce as a color balance adjustment film, and the film formation time is short and advantageous in terms of cost.

  With the configuration of the present invention, it is possible to process an antireflection film in a film formation time close to that of a vacuum evaporation method using a small-sized, small-volume processing, and low-cost sputter film forming apparatus.

Characteristic diagram of Example 1 Characteristic diagram of Example 2 Characteristic diagram of Example 3 Characteristic diagram of Example 4 Characteristic diagram of Example 5 Characteristic diagram of Example 6 Characteristic diagram of Example 7 Characteristic diagram of Example 8 Characteristic diagram of Example 9 Characteristic diagram of Example 10 Characteristics diagram of conventional example 1

Claims (5)

When the reference wavelength of the antireflective film is λ0, the antireflective film having six or more layers composed of alternating layers of a high refractive index film having a refractive index of 2.1 or more and a low refractive index film of 1.65 or less at λ0 , The air-side final layer is formed of a SiO2 film, the reflectance of each wavelength in the visible region (405 to 700 nm) is R (λ), and the reflectance of each wavelength of the single-layer MgF2 film having the same reference wavelength is λ0. When R is single (λ),
| R (λ) −R single (λ) | ≦ 0.4% (1)
An antireflection film characterized by satisfying the expression (1). When the reference wavelength of the antireflection film is λ0, it is composed of alternating layers of a high refractive index film (nH) having a refractive index of 2.1 or more and a low refractive index film (nL) of 1.65 or less at λ0. A layer antireflection film, wherein the optical film thickness (nH * d, nL * d) at λ0 of each layer is from the substrate side,
0.11 ≧ nH * d1 / λ0 ≧ 0.01
0.26 ≧ nL * d2 / λ0 ≧ 0.05
0.23 ≧ nH * d3 / λ0 ≧ 0.03
0.21 ≧ nL * d4 / λ0 ≧ 0.04
0.22 ≧ nH * d5 / λ0 ≧ 0.03
0.38 ≧ nL * d6 / λ0 ≧ 0.26 (21)
The equation (21) is satisfied, and 0.94 ≧ total optical film thickness / λ0 ≧ 0.8 (22)
The antireflection film according to claim 1, wherein the formula (22) is satisfied. When the reference wavelength of the antireflection film is λ0, it is composed of alternating layers of a high refractive index film (nH) having a refractive index of 2.1 or more and a low refractive index film (nL) having a refractive index of 1.65 or less at λ0. A layer antireflection film, wherein the optical film thickness (nH * d, nL * d) at λ0 of each layer is from the substrate side,
0.13 ≧ nL * d1 / λ0 ≧ 0.03
0.13 ≧ nH * d2 / λ0 ≧ 0.01
0.18 ≧ nL * d3 / λ0 ≧ 0.09
0.2 ≧ nH * d4 / λ0 ≧ 0.03
0.2 ≧ nL * d5 / λ0 ≧ 0.07
0.21 ≧ nH * d6 / λ0 ≧ 0.03
0.37 ≧ nL * d7 / λ0 ≧ 0.28 (31)
(31) is satisfied, and 1.12 ≧ total optical film thickness / λ0 ≧ 0.81 (32)
The antireflection film according to claim 1, wherein the formula (32) is satisfied. When the reference wavelength of the antireflection film is λ0, it is composed of alternating layers of a high refractive index film (nH) having a refractive index of 2.1 or more and a low refractive index film (nL) of 1.65 or less at λ0. A layer antireflection film, wherein the optical film thickness (nH * d, nL * d) at λ0 of each layer is from the substrate side,
0.09 ≧ nH * d1 / λ0 ≧ 0.01
0.26 ≧ nL * d2 / λ0 ≧ 0.06
0.19 ≧ nH * d3 / λ0 ≧ 0.03
0.2 ≧ nL * d4 / λ0 ≧ 0.04
0.3 ≧ nH * d5 / λ0 ≧ 0.05
0.18 ≧ nL * d6 / λ0 ≧ 0.02
0.24 ≧ nH * d7 / λ0 ≧ 0.03
0.36 ≧ nL * d8 / λ0 ≧ 0.26 (41)
(41) is satisfied, and 1.2 ≧ total optical film thickness / λ0 ≧ 1.01 (42)
The antireflection film according to claim 1, wherein the formula (42) is satisfied.   The antireflection film according to claim 2, wherein all layers are formed by sputtering.

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