WO2020066428A1 - Film antireflet, élément optique, procédé de production de film antireflet et procédé de production d'une structure en relief fine - Google Patents

Film antireflet, élément optique, procédé de production de film antireflet et procédé de production d'une structure en relief fine Download PDF

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WO2020066428A1
WO2020066428A1 PCT/JP2019/033564 JP2019033564W WO2020066428A1 WO 2020066428 A1 WO2020066428 A1 WO 2020066428A1 JP 2019033564 W JP2019033564 W JP 2019033564W WO 2020066428 A1 WO2020066428 A1 WO 2020066428A1
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refractive index
layer
antireflection film
fine
substrate
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PCT/JP2019/033564
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English (en)
Japanese (ja)
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達矢 吉弘
雄一郎 板井
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富士フイルム株式会社
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Priority to CN201980061244.1A priority Critical patent/CN112740081B/zh
Priority to JP2020548215A priority patent/JP7065995B2/ja
Publication of WO2020066428A1 publication Critical patent/WO2020066428A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G02B1/113—Anti-reflection coatings using inorganic layer materials only
    • G02B1/115—Multilayers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G02B1/118—Anti-reflection coatings having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures

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  • the present disclosure relates to an antireflection film, an optical element having the antireflection film, a method for manufacturing the antireflection film, and a method for forming a fine uneven structure.
  • An antireflection film for suppressing reflection of incident light is provided on the optical surface of the optical element body such as a lens.
  • an antireflection film having a fine uneven structure with a pitch smaller than the wavelength of incident light is known.
  • a fine structure having a structure pitch equal to or less than the wavelength of light can be regarded as a medium having an effective refractive index according to the volume fraction of the material and air, so that a refractive index of 1.3 or less can be obtained. . Therefore, if a structure such as a fine unevenness structure in which the volume fraction continuously changes in the optical axis direction is used, remarkable antireflection performance can be obtained.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2010-156844 (hereinafter referred to as Patent Document 1), International Publication No. WO 2016/006651 (hereinafter referred to as Patent Document 2) and Japanese Patent Application Laid-Open No. 2014-21146 (hereinafter referred to as Patent Document 3),
  • Patent Documents 1 and 2 propose that a concave or convex portion having a cone shape or a truncated cone shape is provided.
  • An imprint method is known as a method for forming a fine uneven structure. This is a method in which a fine uneven structure is formed in a metal or resin mold and transferred to an optical element to be subjected to antireflection.
  • the imprint method has been put to practical use, for example, as a method for forming an antireflection structure of a flat display film. Further, according to the imprint method, the shapes of the convex portions and the concave portions can be controlled relatively easily, and the shapes proposed in Patent Documents 1 and 2 and the like can be realized.
  • Patent Literature 3 Patent No. 4182236 (hereinafter, Patent Literature 4), and Patent No. 4,520,418 (hereinafter, Patent Literature 5) disclose such alumina hydrate plate crystals as a main component. There has been proposed an antireflection film having a fine uneven structure.
  • Patent Documents 3 to 5 propose a configuration in which a thin film layer for reducing a refractive index step is provided between a substrate and a fine uneven structure mainly composed of plate crystals of alumina hydrate. Have been.
  • Patent Literature 4 describes that “the height of the fine unevenness is 0.005 ⁇ m to 5.0 ⁇ m”. However, the example of Patent Document 4 describes only an example up to a height of 0.3 ⁇ m.
  • Patent Document 5 describes that “the thickness of the plate-shaped crystal layer is 20 nm or more and 1000 nm or less”, but the maximum thickness of the plate-shaped crystal layer described in the examples is 500 nm.
  • the refractive index profile for realizing more preferable antireflection property has not been sufficiently studied due to the difficulty in controlling the structure.
  • the antireflection film is designed so that the reflectance with respect to the incident surface of the optical element at an incident angle of 0 ° (normal direction) is minimized. Therefore, a low reflectance at an incident angle of 0 ° is a required performance.
  • the reflectance for oblique incidence such as an incident angle of 45 ° or 60 ° greatly increase with respect to the reflectance for an incident angle of 0 °. Therefore, as the antireflection property, it is required that the reflectance at the time of oblique incidence and the reflectance at the time of incidence in the normal direction are small as well as the low reflectance.
  • the present disclosure can be easily manufactured, and has a low reflectance and a reduced reflectance increase at oblique incidence, an antireflection film, an optical element, a method for manufacturing an antireflection film, and formation of a fine uneven structure.
  • the aim is to provide a method.
  • An antireflection film provided on one surface of a base material including a fine uneven layer mainly composed of plate crystals of hydrated alumina
  • the fine concavo-convex layer has a refractive index profile that becomes the maximum value at the interface on the base material side that gradually changes in the thickness direction from the tip of the convex portion that is the surface toward the base material side,
  • the refractive index is 1.01 or less
  • the maximum refractive index gradient in the first inclined refractive index region from the surface to 100 nm in the thickness direction is the longest wavelength in the wavelength region of light to be antireflection target.
  • 0.4 / lambda max or less is an antireflection film when the lambda max.
  • the maximum refractive index gradient in the second inclined refractive index region from the position of 100 nm in the thickness direction to the interface on the substrate side is 0.8 / ⁇ max or less.
  • ⁇ 4> The antireflection film according to any one of ⁇ 1> to ⁇ 3>, wherein the maximum value in the refractive index profile is 1.5 or more.
  • ⁇ 5> The antireflection film according to any one of ⁇ 1> to ⁇ 4>, wherein the thickness of the fine uneven layer is 550 nm or more.
  • ⁇ 6> The antireflection film according to any one of ⁇ 1> to ⁇ 5>, wherein the substrate has a refractive index at ⁇ max of more than 1.5.
  • An inclined refractive index layer is provided between the fine uneven layer and the substrate,
  • the inclined refractive index layer has a refractive index profile in which the refractive index gradually changes in the thickness direction from the interface with the fine uneven layer to the substrate, and the refractive index at the interface with the fine uneven layer.
  • the difference between the refractive index of the fine unevenness layer at the interface is 0.01 or less, and the difference between the refractive index at the interface with the base material and the refractive index of the base material is 0.01 or less ⁇ 1>.
  • ⁇ 11> An optical element including a base material and the antireflection film according to any one of ⁇ 1> to ⁇ 10> provided on one surface of the base material.
  • ⁇ 12> a thin film forming step of forming a thin film containing aluminum on a film forming surface on the base material; By performing a warm water treatment on the thin film, a warm water treatment step of forming a fine uneven structure composed of a plate-like crystal mainly composed of alumina hydrate,
  • a method for producing an antireflection film comprising: a step of repeating the thin film forming step and the hot water treatment step with the surface of the fine uneven structure as the film forming surface.
  • a thin film forming step of forming a thin film containing aluminum on a film forming surface on the base material A hot water treatment step of subjecting the thin film to a warm water treatment to form a fine uneven structure composed of plate crystals mainly composed of alumina hydrate;
  • a method for forming a fine uneven structure comprising: a step of repeating the thin film forming step and the warm water treatment step with the surface of the fine uneven structure as the film forming surface.
  • an antireflection film that can be easily manufactured, has low reflectance, and suppresses an increase in reflectance at oblique incidence.
  • FIG. 2 is a schematic diagram illustrating a schematic configuration of an antireflection film and an optical element according to a first embodiment, and a refractive index distribution. It is a figure which shows the manufacturing process of an antireflection film.
  • FIG. 5 is a schematic diagram illustrating a schematic configuration of an antireflection film and an optical element according to a second embodiment, and a refractive index distribution.
  • FIG. 9 is a schematic diagram illustrating a schematic configuration of an antireflection film and an optical element according to a third embodiment, and a refractive index distribution.
  • FIG. 3 is a view showing a refractive index profile of a fine unevenness layer of Example 1.
  • FIG. 3 is a diagram illustrating the wavelength dependence of the reflectance of the antireflection film of Example 1.
  • FIG. 9 is a diagram showing the wavelength dependence of the reflectance of the antireflection film of Example 2.
  • FIG. 9 is a diagram showing the wavelength dependence of the reflectance of the antireflection film of Example 2.
  • FIG. 9 is a diagram illustrating the wavelength dependence of the reflectance of the antireflection film of Example 4.
  • FIG. 14 is a diagram showing the wavelength dependence of the reflectance of the antireflection film of Example 5.
  • FIG. 14 is a diagram illustrating the wavelength dependence of the reflectance of the antireflection film of Example 6.
  • FIG. 14 is a diagram illustrating the wavelength dependence of the reflectance of the antireflection film of Example 7.
  • FIG. 3 is a view showing a refractive index profile of a fine unevenness layer of Example 1.
  • FIG. 9 is a diagram showing the wavelength dependence of the reflectance of the antireflection film of Comparative Example 1.
  • FIG. 9 is a diagram illustrating the wavelength dependence of the reflectance of the antireflection film of Comparative Example 2.
  • 4 is a scanning electron microscope image of a cross section of the fine concavo-convex layer of Example 1.
  • 4 is a scanning electron microscope image of a cross section of the fine unevenness layer of Comparative Example 1.
  • FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an optical element 1 including an antireflection film 11 according to the first embodiment of the present invention, and a view showing a refractive index profile in a thickness direction.
  • the antireflection film 11 of the present embodiment includes a fine uneven layer 20 which is provided on one surface of the base material 10 and has a plate crystal of alumina hydrate as a main component.
  • the optical element 1 includes a base material 10 and an antireflection film 11 provided on one surface thereof.
  • the substrate 10 is a transparent optical member mainly used in an optical device, such as a flat plate, a concave lens, a convex lens, or a flexible transparent film.
  • an optical device such as a flat plate, a concave lens, a convex lens, or a flexible transparent film.
  • transparent means that the internal transmittance is about 10% or more with respect to the wavelength of the light to be prevented from being reflected by the optical member (the antireflection target light).
  • the substrate on which the antireflection film is formed is not limited to a transparent substrate, and is not particularly limited as long as the substrate has a surface to be antireflective.
  • the fine concavo-convex layer 20 is a layer mainly composed of a plate-like crystal of hydrated alumina having at least a fine concavo-convex surface.
  • the alumina hydrate includes boehmite (expressed as Al 2 O 3 .H 2 O or AlOOH), which is alumina monohydrate, and Bayerlite (Al, which is alumina trihydrate (aluminum hydroxide)). 2 O 3 .3H 2 O or Al (OH) 3 ).
  • “Alumina hydrate plate crystal as a main component” means that the alumina hydrate plate crystal in the fine uneven layer 20 is 80% by mass or more of the component constituting the fine uneven layer 20. It means there is.
  • FIG. 1 shows, as the fine concavo-convex layer 20, a fine concavo-convex layer in which uniform convex portions having a large difference in height are arranged and arranged.
  • the fine uneven layer 20 mainly composed of plate crystals of the actual hydrate of alumina has a random structure formed by overlapping plate crystals, and is specifically shown in FIG. It has such a cross section.
  • the fine uneven layer 20 has a refractive index profile that gradually changes in the thickness direction from the tip of the convex portion as the surface toward the substrate 10 and has the maximum value at the interface closest to the substrate 10.
  • a gradual change in the refractive index means that there is no refractive index step greater than 0.01 in the refractive index profile.
  • a region from the surface of the fine unevenness layer 20 up to 100 nm in the thickness direction is a first inclined refractive index region 21, and a region from the position of 100 nm in the thickness direction to the interface closest to the base material is a second inclined refractive index region 22.
  • the refractive index is a refractive index at a wavelength of 540 nm unless otherwise specified.
  • the refractive index profile in the thickness direction of the fine uneven layer 20 will be described. The most important is the refractive index profile on the tip side of the projection. If the reflection occurs at the surface where the light enters, it is necessary to cause an interference action to cancel the reflection in the subsequent structure. When a structure that causes interference is provided, the antireflection performance at the time of oblique incidence of light on the antireflection film decreases. Therefore, it is most important to prevent reflection at the tip portion.
  • the refractive index on the surface of the fine uneven layer 20 is 1.01 or less, and the maximum refractive index gradient in the first inclined refractive index region 21 from the surface to 100 nm in the thickness direction is the wavelength of light to be antireflection target.
  • the longest wavelength in the range is ⁇ max , it is 0.4 / ⁇ max or less.
  • the light to be antireflection target varies depending on the application, but is generally light in a visible light region, and may be light in an infrared region as needed.
  • the visible light region refers to a wavelength of 400 nm to 800 nm. Therefore, when the visible light region is the anti-reflection target, the longest wavelength ⁇ max in the wavelength region of the light to be anti-reflection target is 800 nm, and the shortest wavelength ⁇ min is 400 nm.
  • the maximum refractive index gradient in the first inclined refractive index region 21 from the surface to the thickness direction up to 100 nm is 0.4 / ⁇ max or less, it is possible to sufficiently suppress reflection at the tip. Become. In the range of 100 nm from the surface, the refractive index gradient does not need to be constant and may be increased or decreased as long as the maximum refractive index gradient is within a range of 0.4 / ⁇ max or less.
  • the refractive index gradient is a value obtained by averaging the refractive index gradient in the range of ⁇ min / 20. That is, the refractive index gradient averaged in the range of ⁇ min / 20 around each position is defined as the refractive index gradient at each position.
  • the value of ⁇ min / 20 centered on that position is obtained. It is sufficient that the average value of the refractive index gradients in the range is positive and 0.4 / ⁇ max or less. Therefore, as a whole as shown in the lower part of FIG 1, until the refractive index n 1 at the position of 100nm from the tip, the refractive index gradually increases. Since the maximum refractive index gradient in this range is 0.4 / lambda max, if the light anti-reflection target is visible light, n 1 is 1.05 or less. In the first inclined refractive index region 21, the maximum refractive index gradient is more preferably 0.2 / ⁇ max or less.
  • the surface of the fine uneven layer 20 can be clearly defined by examining the refractive index profile in the thickness direction of the fine uneven layer 20.
  • the step is the surface of the fine uneven layer 20.
  • the portion where the refractive index decreases from the substrate side toward the thickness direction and the refractive index becomes 1.0 is the surface.
  • the maximum refractive index gradient in the second gradient refractive index region 22 from the position of 100 nm in the thickness direction of the fine uneven layer 20 to the interface closest to the substrate 10 is 0.8 / ⁇ max or less. Again, even microscopically there are places to be slope or negative slope greater than 0.8 / lambda max, were averaged refractive index gradient ranging lambda min / 20 centered on its position The value may be 0.8 / ⁇ max or less.
  • the maximum value in the refractive index profile of the fine uneven layer 20, that is, the second inclination preferably the difference between the refractive index n S of a surface of the refractive index n 2 and the substrate 10 closest to the substrate side of the interface of refractive index region 22 is 0.01 or less, and particularly preferably they are equal.
  • the thickness h2 of the second gradient refractive index region 22 is preferably 200 nm or more, and more preferably 600 nm or less. It is particularly preferable that the thickness h2 of the second gradient refractive index region 22 is 450 nm or more. That is, the thickness h of the entire fine uneven layer 20 is preferably 300 nm or more, more preferably 700 nm or less, and particularly preferably 550 nm or more.
  • the fine uneven layer 20 having the above-mentioned refractive index profile can realize a low reflectance even for obliquely incident light, and can sufficiently suppress a change in the reflectance due to the incident angle (see Examples described later).
  • the fine uneven layer having the above-mentioned refractive index profile can be obtained by repeating the formation of a thin film containing aluminum and the treatment with hot water two or more times.
  • a method for forming the fine uneven structure that is, a method for manufacturing the antireflection film 11 will be described.
  • a thin film 25 containing an aluminum element is formed on the surface of the substrate 10 (step 1).
  • the thin film containing the aluminum element contains, for example, one or more mixtures selected from metal aluminum, aluminum oxide (alumina), aluminum nitride, and aluminum fluoride.
  • the thin film 25 containing an aluminum element can be obtained by vapor phase film formation or liquid layer film formation, it is particularly preferable to use gas layer formation because of the ease of forming a thin film into a structure including a large number of curved surfaces. .
  • the thickness of the thin film can be 1 nm to 100 nm, and more preferably, 20 nm to 80 nm.
  • the thin film 25 together with the base material 10 is immersed in warm water 50 (step 2).
  • the temperature of the hot water in this hot water treatment step be 60 ° C. or more and the boiling temperature or less, and the immersion time be 1 minute or more and 10 minutes or less. More preferably, the temperature of the hot water is 95 ° C. or more, and the immersion time is 3 minutes or more.
  • the hot water treatment liquid pure water is preferably used, and particularly, ultrapure water having an electrical resistivity of 14 M ⁇ ⁇ m or more at a water temperature of 25 ° C. is preferably used.
  • the thin film 25 becomes a fine uneven layer 26 made of plate crystals of alumina hydrate (step 3).
  • a drying process for removing warm water from the surface of the fine uneven layer 26 of the substrate taken out of the warm water 50 is performed.
  • the drying treatment use of hot air drying, infrared drying, hot plate drying, suction drying, vacuum drying, steam drying, hot pure water pull-up drying, Marangoni drying, air blow drying, and spin drying used in the drying process after industrial cleaning. Can be.
  • step 4 the above-described thin film forming step and the hot water treatment step are repeated with the fine uneven layer 26 as a film formation surface.
  • a thin film 25 containing an aluminum element is formed on the surface of the fine unevenness layer 26 (step 4), and the substrate 10 is immersed in warm water 50 (step 5).
  • a fine uneven structure having the above-described refractive index profile can be formed on the base material 10, and the antireflection film 11 having the fine uneven layer 20 can be manufactured (Step 6).
  • the thin film containing the aluminum element when the ratio of metallic aluminum, aluminum oxide (alumina), aluminum nitride, and aluminum fluoride is 99% or more, the hydrate of alumina in the obtained fine unevenness layer 20 has a purity of 95% or more. Becomes Impurities contain less than 5% magnesium or sodium.
  • the thin film forming step and the hot water treatment step may be repeated not only twice but also three times or more.
  • the thickness of the fine concavo-convex layer refers to the height (thickness) of a region where the refractive index changes. For example, even if an aluminum thin film having a thickness of 80 nm was formed and subjected to hot water treatment, a fine uneven layer made of a plate-like crystal and having a structure height exceeding 500 nm was not obtained.
  • An anti-reflection film provided with a fine uneven layer made of a plate crystal mainly composed of alumina hydrate has been proposed so far, but heretofore, a fine film formed by a single thin film formation and hot water treatment has been proposed. Only use of the uneven layer has been considered.
  • thin film formation and hot water treatment are repeated twice or more.
  • FIG. 3 is a schematic cross-sectional view showing a schematic configuration of the optical element 2 including the antireflection film 12 according to the second embodiment of the present invention and a view showing a refractive index profile in a thickness direction.
  • the antireflection film 12 of the present embodiment includes a gradient refractive index layer 30 as an intermediate layer between the fine uneven layer 20 and the base material 10.
  • the fine concavo-convex layer 20 is the same as that of the antireflection film 11 of the first embodiment.
  • the difference between the refractive index n 2 at the interface closest to the substrate in the second inclined refractive index region of the fine unevenness layer 20 and the refractive index n S of the substrate 10 exceeds 0.01, the refractive indices of both are refracted. It is preferable to provide the gradient refractive index layer 30 for filling the index difference.
  • the refractive index of the substrate 10 can be more than 1.5, and can be 1.6 or more. In this case, it is preferable that the refractive index n 2 of the second gradient index region is 1.5 or more.
  • the inclined refractive index layer 30 has a refractive index profile in which the refractive index gradually changes in the thickness direction from the interface with the fine uneven layer 20 toward the substrate 10. in the difference between the refractive index n 2 of the fine uneven layer 20 at the interface is 0.01 or less, the difference between the refractive index n S of the refractive index and the substrate 10 at the interface with the substrate 10 is 0.01 or less is there. It is preferable that the maximum refractive index gradient in the thickness direction is 1.6 / ⁇ max or less.
  • the gradient refractive index layer 30 is a thin film layer made of at least two or more kinds of materials, and continuously changes the refractive index by continuously changing the ratio of the materials in the thickness direction of the thin film.
  • a change in the ratio of oxygen and nitrogen in a silicon oxynitride (SiON) film by reactive sputtering can be used.
  • a mixed film of SiON and Nb 2 O The change of the element ratio of the mixed film with 5 can be used.
  • a desired gradient refractive index thin film can be obtained by sequentially coating a plurality of solutions having different refractive indexes on a substrate.
  • the coating method include spin coating, dip coating, spray coating, and an ink jet method.
  • the continuous change in the refractive index means that the amount of change in the refractive index of an adjacent layer is 0.01 or less.
  • the antireflection film of the second embodiment is formed by forming the inclined refractive index layer 30 on a substrate by the above-described method, and using the surface of the inclined refractive index layer 30 as a film forming surface to form the above-described fine uneven structure.
  • the fine unevenness layer 20 By forming the fine unevenness layer 20 by using the method described above.
  • the same fine unevenness layer 20 as that of the first embodiment is provided, so that the same effect as that of the first embodiment can be obtained. Very good antireflection properties can be obtained even when the refractive index is greater than 1.5 and even as large as 1.6 or more.
  • FIG. 4 is a schematic cross-sectional view showing a schematic configuration of the optical element 3 including the antireflection film 13 according to the third embodiment of the present invention, and a view showing a refractive index profile in a thickness direction.
  • the antireflection film 12 of the present embodiment includes a refractive index matching layer 40 as an intermediate layer between the fine uneven layer 20 and the base material 10 in the antireflection film 11 of FIG. 1. .
  • the fine concavo-convex layer 20 is the same as that of the antireflection film 11 of the first embodiment.
  • this embodiment replaces the inclined refractive index layer 30 of the second embodiment.
  • the refractive index matching layer 40 may be provided.
  • the antireflection performance can be improved by causing the refractive index matching layer 40 to generate reflection that cancels out reflection caused by a refractive index step between the base material 10 and the fine unevenness layer 20.
  • the refractive index matching layer 40 has a laminated structure in which high refractive index layers 41 having a relatively high refractive index and low refractive index layers 42 having a relatively low refractive index are alternately laminated.
  • the ratio of the relatively high refractive index to the relatively low refractive index is 1.1 or more.
  • “having a relatively high refractive index” and “having a relatively low refractive index” refer to a relative relationship between a high refractive index layer and a low refractive index layer, and the high refractive index layer has a low refractive index. It has a higher refractive index than the refractive index layer, meaning that the low refractive index layer has a lower refractive index than the high refractive index layer.
  • a high refractive index layer 41 and a low refractive index layer 42 are laminated alternately in a total of eight layers, with the high refractive index layer 41 being arranged closest to the substrate side.
  • the layers may be laminated such that the substrate side is the low refractive index layer 42, and the total number of layers of the laminated structure of the high refractive index layer 41 and the low refractive index layer 42 may be at least two. , Preferably four or more layers.
  • the high refractive index layer 41 preferably has a refractive index nH of 1.7 or more, and more preferably 1.9 or more.
  • the low refractive index layer 42 preferably has a refractive index n L of 1.6 or less, more preferably 1.55 or less.
  • the refractive index n L of the low refractive index layer 42 is lower than the refractive index n S of the substrate 10, the refractive index n H of the high refractive index layer 41 is preferably higher than the refractive index n S of the base 10 .
  • the high-refractive-index layers 41 or the low-refractive-index layers 42 do not necessarily have to have the same refractive index, and may not be made of the same material. Is preferable from the viewpoint of suppressing material costs, film formation costs, and the like.
  • the high refractive index layer 41 for example, an oxide of any of aluminum, titanium, tantalum, zirconium, niobium, magnesium and lanthanum, aluminum nitride, aluminum oxynitride, silicon nitride, silicon oxynitride And mixtures thereof.
  • Examples of the material for the low refractive index layer 42 include silicon oxide, silicon oxynitride, magnesium fluoride, and mixtures thereof, and silicon oxide, silicon oxynitride, and mixtures of magnesium fluoride and alumina. Mixtures are mentioned.
  • Each layer of the refractive index matching layer 40 can be formed by a vapor deposition method such as a sputtering method, an electron beam evaporation method, and a chemical vapor deposition method.
  • the antireflection film of the third embodiment is formed by forming the refractive index matching layer 40 on the base material by the above-described method, and using the surface of the refractive index matching layer 40 as a film forming surface to form the above-described fine uneven structure. To form a fine uneven layer.
  • the same fine unevenness layer 20 as that of the first embodiment is provided, so that the same effect as that of the first embodiment can be obtained. Very good antireflection properties can be obtained even when the refractive index is greater than 1.5 and even as large as 1.6 or more.
  • ⁇ max 800 nm.
  • Example 1 A 70 nm alumina (Al 2 O 3 ) thin film was formed by a direct current (DC) sputtering method on a glass substrate and a single crystal Si substrate of Eagle XG (registered trademark) manufactured by Corning Incorporated. Next, ultrapure water having an electric resistivity of 14 M ⁇ ⁇ cm or more at a water temperature of 25 ° C. was heated to 100 ° C., and both substrates on which the alumina thin film was formed were immersed for 3 minutes. After obtaining a fine uneven structure mainly composed of a plate-like crystal made of alumina hydrate, hot water was dried by air blow drying.
  • DC direct current
  • an alumina thin film having a thickness of 70 nm was formed again by the DC sputtering method. Further, ultrapure water was heated to 100 ° C., and both substrates on which the alumina thin film was formed were immersed for 3 minutes. In this way, a fine uneven layer mainly composed of alumina hydrate thicker than the fine uneven structure formed by the first warm water treatment was obtained. That is, the formation of the alumina thin film and the hot water treatment were repeated twice to form a fine uneven structure, and the antireflection film of Example 1 including the fine uneven layer on the glass substrate was produced.
  • the purity of the alumina thin film formed by the DC sputtering method was measured by X-ray photoelectron spectroscopy, the purity was 99% or more.
  • the following refractive index profile was measured using a sample provided with a fine uneven layer on a single-crystal Si substrate produced at the same time.
  • FIG. 5 shows the obtained refractive index distribution.
  • the horizontal axis represents the thickness from the substrate surface with the substrate surface position being 0, and the vertical axis represents the refractive index.
  • the refractive index continuously changes from the substrate surface and gradually decreases to the refractive index of air of 1.
  • FIG. 5 there was no refractive index step at the interface with air. Therefore, the point where the refractive index coincided with the refractive index 1 of air was regarded as the surface of the fine uneven layer.
  • the thickness of the fine unevenness layer was 590 nm.
  • the refractive index at a position of 100 nm in the thickness direction from the surface of the fine uneven structure is 1.045. Therefore, the refractive index gradient in the first gradient refractive index region is 0.045 / 100 nm, which satisfies 0.4 / ⁇ max or less.
  • the thickness of the second gradient refractive index region is 490 nm, and the refractive index changes from 1.045 to 1.52 from the substrate surface. Therefore, the refractive index gradient in the second gradient refractive index region is 0.475 / 490 nm.
  • Silicon oxynitride was formed on a glass substrate of S-LAH55V manufactured by OHARA CORPORATION by reactive sputtering (sputtering apparatus RAS manufactured by SYNCHRON CORPORATION).
  • the refractive index of silicon oxynitride can be controlled by the gas flow rate during reactive sputtering.
  • a gradient refractive index layer was formed by continuously changing the refractive index from 1.84 to 1.52 from the substrate side to the surface side.
  • the thickness of the gradient refractive index layer was 1280 nm, and the third refractive index gradient was 0.00025 / nm.
  • a fine concavo-convex layer was formed on this gradient refractive index layer in the same manner as in Example 1, and an antireflection film of Example 2 including a gradient refractive index layer and a fine concavo-convex layer on a glass substrate was produced.
  • Example 1 About the obtained structure, about the fine uneven
  • FIG. 7 shows the reflection dependence of the refractive index at the incident angles of 0 °, 45 ° and 60 ° obtained by numerical calculation, and Table 3 shows the average reflectance. The average reflectance was 1.3% at an incident angle of 60 °, and a good value was obtained even at oblique incidence.
  • Example 3 The antireflection film of Example 3 was produced in the same manner as in Example 2, except that the thickness of the gradient refractive index layer was 640 nm and the refractive index gradient was 0.0005 / nm. In the same manner as in Example 2, the wavelength dependence of the reflectance and the average reflectance were determined.
  • FIG. 8 shows the reflection dependence of the refractive index at the incident angles of 0 °, 45 ° and 60 ° obtained by numerical calculation, and Table 3 shows the average reflectance. The average reflectance was 1.2% at an incident angle of 60 °, and a good value was obtained even at oblique incidence.
  • Example 4 The antireflection film of Example 4 was produced in the same manner as in Example 2, except that the thickness of the gradient refractive index layer was 320 nm and the refractive index gradient was 0.001 / nm. In the same manner as in Example 2, the wavelength dependence of the reflectance and the average reflectance were determined.
  • FIG. 9 shows the reflection dependence of the refractive index at the incident angles of 0 °, 45 ° and 60 ° obtained by numerical calculation, and Table 3 shows the average reflectance. The average reflectance was 1.2% at an incident angle of 60 °, and a good value was obtained even at oblique incidence.
  • Example 5 The antireflection film of Example 5 was produced in the same manner as in Example 2, except that the thickness of the gradient refractive index layer was 160 nm and the refractive index gradient was 0.002 / nm. In the same manner as in Example 2, the wavelength dependence of the reflectance and the average reflectance were determined.
  • FIG. 10 shows the reflection dependence of the refractive index at the incident angles of 0 °, 45 ° and 60 ° obtained by numerical calculation, and Table 3 shows the average reflectance. The average reflectance was 1.1% at an incident angle of 60 °, and a good value was obtained even at oblique incidence.
  • Example 6 On an S-LAH55V glass substrate manufactured by OHARA, instead of the graded refractive index layer of Example 2, two types of silicon oxynitride (SiON) and silicon nitride (SiN) were used as a refractive index matching layer as an intermediate layer. was formed.
  • Table 1 shows the layer configuration of the antireflection film of Example 6. The thickness of each layer of the refractive index matching layer was as shown in Table 1. Then, a fine concavo-convex layer was formed on the laminated film in the same manner as in Example 1, and the antireflection film of Example 6 including the fine concavo-convex layer on the refractive index matching layer was produced.
  • Example 2 About the obtained structure, about the fine uneven
  • FIG. 11 shows the reflection dependence of the refractive index at the incident angles of 0 °, 45 ° and 60 ° obtained by numerical calculation, and Table 3 shows the average reflectance. The average reflectance was 1.1% at an incident angle of 60 °, and a good value was obtained even at oblique incidence.
  • Example 7 The antireflection film of Example 7 was produced in the same manner as in Example 2, except that the thickness of the gradient refractive index layer was 80 nm and the refractive index gradient was 0.004 / nm. In the same manner as in Example 2, the wavelength dependence of the reflectance and the average reflectance were determined.
  • FIG. 12 shows the reflection dependence of the refractive index at the incident angles of 0 °, 45 ° and 60 ° obtained by numerical calculation, and Table 3 shows the average reflectance.
  • the average reflectance at the incident angles of 0 ° and 45 ° was larger than those of the other examples, but the increase rate of the average reflectance at the incident angle of 60 ° from the incident angle of 0 ° was larger than that of the other examples.
  • Comparative Example 1 A 40 nm Al thin film was formed on a glass substrate and a single crystal Si substrate of Eagle XG (registered trademark) manufactured by Corning Inc. by a DC sputtering method. Then, the same ultrapure water as in Example 1 was heated to 100 ° C., and the two substrates on which the Al film was formed were immersed for 3 minutes to obtain fine particles mainly composed of plate crystals of alumina hydrate. An uneven layer was obtained. The anti-reflection film of Comparative Example 1 provided with the fine uneven layer formed by performing this Al thin film formation and hot water treatment only once was formed on a glass substrate.
  • the purity of the Al film formed by the DC sputtering method was measured by X-ray photoelectron spectroscopy, the purity was 99% or more.
  • the following refractive index profile was measured using a sample provided with a fine uneven layer on a single-crystal Si substrate produced at the same time.
  • the refractive index distribution (refractive index profile) in the thickness direction of the fine uneven layer was determined from the spectroscopic ellipsometry measurement.
  • FIG. 13 shows the obtained refractive index distribution.
  • the horizontal axis represents the thickness from the substrate surface with the substrate surface position being 0, and the vertical axis represents the refractive index.
  • the thickness of the fine unevenness layer was 325 nm.
  • the refractive index at a position of 100 nm in the thickness direction from the surface of the fine uneven layer is 1.09. Accordingly, the refractive index gradient in the first gradient index region is 0.09 / 100 nm, is greater than 0.4 / lambda max.
  • the thickness of the second gradient refractive index region is 225 nm, and the refractive index has a peak between 1.1 and the substrate surface, and thereafter decreases to around 1.3.
  • the range of the visible light (wavelength: 400 to 800 nm) at the incident angles of 0 °, 45 °, and 60 ° with respect to the substrate surface was determined by numerical calculation.
  • FIG. 14 shows the reflection dependence of the refractive index at the incident angles of 0 °, 45 °, and 60 ° obtained by the numerical calculation.
  • Table 3 shows the average reflectance. At an incident angle of 60 °, the average reflectance was 2.2%, which was a relatively large value.
  • Comparative Example 2 On an S-LAH55V glass substrate manufactured by OHARA, a laminated film composed of two kinds of silicon oxynitride and silicon nitride was formed as a refractive index matching layer.
  • Table 2 shows the layer configuration of the antireflection film of Comparative Example 2. The thickness of each layer of the refractive index matching layer was as shown in Table 2. Then, a fine concavo-convex layer was formed on the laminated film in the same manner as in Comparative Example 1 to prepare an antireflection film of Comparative Example 2 including the fine concavo-convex layer on the refractive index matching layer.
  • FIG. 15 shows the reflection dependence of the refractive index at the incident angles of 0 °, 45 ° and 60 ° obtained by numerical calculation
  • Table 3 shows the average reflectance.
  • Example 1 From the results of Example 1 and Comparative Example 1 having no intermediate layer, the fine unevenness layer subjected to the twice warm water treatment has a lower average reflection at any incident angle than the fine unevenness layer subjected to the once warm water treatment. It was clarified that a good antireflection property was obtained.
  • Example 7 As shown in Table 3, in Examples 1 to 6, a good average reflectance of 0.2% or less was obtained at an incident angle of 0 °. Even when the incident angles were increased to 45 ° and 60 °, an average reflectance of 1.5% or less was obtained, and the increase in reflectance at an oblique incidence of 10 ° or less with respect to an incident angle of 0 °. And good antireflection properties were obtained.
  • the average reflectance at an incident angle of 0 ° is slightly higher than those of the other examples, but the increase in the average reflectance at an incident angle of 45 ° or 60 ° with respect to the incident angle of 0 ° is four times.
  • Comparative Example 2 having a configuration including a fine unevenness layer obtained by a single hot water treatment and a refractive index matching layer formed of a laminated film of high and low refractive index layers, a very low average reflectance was obtained at an incident angle of 0 °. Have been.
  • Comparative Example 2 the average reflectance increased 5 times or more at an incident angle of 45 ° with respect to the incident angle of 0 °, and increased 20 times at an incident angle of 60 °. Had declined.
  • FIGS. 16 and 17 are scanning electron microscope (SEM) images of the cross section of the fine concavo-convex layer formed on the Si substrate in Example 1 and Comparative Example 1, respectively. In each case, the magnification is 50,000 times.
  • the fine unevenness layer of Example 1 shown in FIG. 16 is a layer having a thickness of 590 nm and made of plate-like crystals from the surface of the base material to the surface of the fine unevenness layer, and having fine unevenness on at least the surface.
  • the fine uneven layer of Comparative Example 1 shown in FIG. 17 has a thickness of 325 nm. As shown in FIG.
  • Example 16 it can be seen that even the fine uneven layer of Example 1 having a large thickness is composed of a plate crystal from the surface of the fine uneven layer to the surface of the Si substrate. That is, by forming a thin film layer containing aluminum and warm water treatment at least twice, forming a fine uneven layer having a thickness exceeding 500 nm without leaving a thin film layer that is not hydrated on the substrate side. succeeded in. There has been no actual case of a fine uneven layer made of plate crystals of hydrated alumina having a thickness exceeding 500 nm.

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  • General Physics & Mathematics (AREA)
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  • Inorganic Chemistry (AREA)
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Abstract

La présente invention concerne un film antireflet facile à fabriquer et présentant une meilleure performance antireflet ; un élément optique pourvu d'un effet antireflet ; un procédé de production du film antireflet ; et un procédé de formation d'une structure en relief fine. La présente invention consiste à répéter, plusieurs fois, les étapes suivantes : une étape de formation de film mince consistant à former un film mince contenant de l'aluminium sur une surface de formation de film d'un substrat ; et une étape de traitement à l'eau chaude consistant à former une structure en relief fine constituée de cristal plat présentant de l'hydrate d'alumine en tant que composant principal en soumettant le film fin à un traitement à l'eau chaude. La présente invention permet d'obtenir un film antireflet comprenant une couche en relief fine : qui présente un profil d'indice de réfraction qui change progressivement dans le sens de l'épaisseur en partant de l'extrémité distale de convexité, qui est la surface, vers le côté substrat et atteint une valeur maximale à la limite située le plus vers le côté substrat ; et qui présente un indice de réfraction au niveau de la surface inférieur ou égal à 1,01 ; et qui présente un premier gradient d'indice de réfraction, de la surface à 100 nm dans le sens de l'épaisseur, de 0,4/λmax ou moins, où λmax est la longueur d'onde la plus grande dans une région de longueur d'onde de lumière ciblée par l'antireflet.
PCT/JP2019/033564 2018-09-27 2019-08-27 Film antireflet, élément optique, procédé de production de film antireflet et procédé de production d'une structure en relief fine WO2020066428A1 (fr)

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CN201980061244.1A CN112740081B (zh) 2018-09-27 2019-08-27 防反射膜、光学元件、防反射膜的制造方法及微细凹凸结构的形成方法
JP2020548215A JP7065995B2 (ja) 2018-09-27 2019-08-27 反射防止膜の製造方法、および微細凹凸構造の形成方法

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