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WO2019208366A1 - Film mince optique, élément optique, système optique et procédé de production de film mince optique - Google Patents

Film mince optique, élément optique, système optique et procédé de production de film mince optique Download PDF

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Publication number
WO2019208366A1
WO2019208366A1 PCT/JP2019/016524 JP2019016524W WO2019208366A1 WO 2019208366 A1 WO2019208366 A1 WO 2019208366A1 JP 2019016524 W JP2019016524 W JP 2019016524W WO 2019208366 A1 WO2019208366 A1 WO 2019208366A1
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Prior art keywords
silver
thin film
layer
film
optical thin
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English (en)
Japanese (ja)
Inventor
梅田　賢一
達矢 吉弘
圭佑 青島
誠吾 中村
雄一郎 板井
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Fujifilm Corp
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Fujifilm Corp
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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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B15/00—Optical objectives with means for varying the magnification
    • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
    • G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
    • G02B15/20—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having an additional movable lens or lens group for varying the objective focal length

Definitions

  • the present disclosure relates to an optical thin film such as an antireflection film and a transparent conductive film, an optical element including the optical thin film, an optical system including the optical element, and a method of manufacturing the optical thin film.
  • an antireflection film may be provided on the light incident surface in order to reduce the loss of transmitted light due to surface reflection.
  • an antireflection film comprising a silver-containing metal layer containing silver (Ag) in a laminate of dielectric films is disclosed in JP 2013-238709 (hereinafter, Patent Document 1), International Proposed in Japanese Unexamined Patent Publication No. 2016-189848 (hereinafter referred to as Patent Document 2), Japanese Patent Application Laid-Open No. 2004-334012 (hereinafter referred to as Patent Document 3), and Japanese Patent Application Laid-Open No. 10-96801 (hereinafter referred to as Patent Document 4). Yes.
  • Patent Documents 1 and 2 in order to realize a lower reflectance, a laminated body in which a low refractive index layer and a high refractive index layer are alternately laminated, and a dielectric layer having a surface exposed to air, A structure including a silver-containing metal layer is proposed.
  • a particularly preferred example of the dielectric layer provided on the silver-containing metal layer is silicon dioxide (SiO 2 ).
  • the silver-containing metal layer is directly provided with a SiO 2 layer, silver is oxidized, the silver-containing metal layer is colored and the transparency is lowered, and the refractive index is changed. There may be a problem that the antireflection effect is reduced. In particular, the thinner the silver-containing metal layer, the more pronounced this problem.
  • Patent Document 3 proposes a structure in which a nitride film is provided on the silver film to prevent silver oxidation.
  • Patent Document 4 discloses that a nitride film is provided between SiO 2 provided on the upper layer of the metal layer and the metal layer in order to prevent oxidation of the metal layer.
  • Patent Documents 3 and 4 when a structure including a nitride film for preventing oxidation of the silver film is used, since the nitride film has a higher refractive index than that of the oxide film, the deterioration of silver is suppressed. When it is provided with a thickness as much as possible, the antireflection performance may be reduced. Further, when a nitride film is used, there is a problem that the light transparency is lowered.
  • the optical thin film having a silver-containing metal layer that has been thinned to improve transparency is not limited to the use as an antireflection film as described above, and it can be applied to a transparent conductive film and the like. There is.
  • a problem to be solved by the technology of the present disclosure is to provide an optical thin film having high light transmittance and high durability, an optical element and an optical system including the optical thin film, and a method for manufacturing the optical thin film. .
  • the optical thin film of the present disclosure includes a silver-containing metal layer containing silver provided on one surface of a substrate, A dielectric layer laminated in contact with the silver-containing metal layer, The first oxygen concentration in the first region including the first surface in which the dielectric layer contains a metal oxide and the silver-containing metal layer of the dielectric layer is in contact with the first oxide concentration of the metal oxide.
  • the optical thin film is smaller than the oxygen concentration.
  • the silver-containing metal layer means a layer containing 50 atomic% or more of silver.
  • the first oxygen concentration is preferably 0.95 times or less the oxygen concentration of the stoichiometric composition.
  • the first region of the dielectric layer is provided over 5 nm or more in the film thickness direction.
  • the first oxygen concentration is lower than the second oxygen concentration in the second region including the second surface facing the first surface of the dielectric layer.
  • the metal oxide is preferably silicon oxide.
  • the ratio of the first oxygen concentration of the first region in the dielectric layer to the oxygen concentration of the stoichiometric composition is X
  • the thickness of the first region is dnm (nanometer)
  • an intermediate including a high refractive index layer having a relatively high refractive index and a low refractive index layer having a relatively low refractive index between the substrate and the silver-containing metal layer.
  • a layer may be provided.
  • “having a relatively high refractive index” and “having a relatively low refractive index” refer to the relative relationship between the high refractive index layer and the low refractive index layer. It means that the refractive index layer has a higher refractive index than the low refractive index layer, and the low refractive index layer has a lower refractive index than the high refractive index layer.
  • the optical thin film of the present disclosure may further include a fine concavo-convex layer mainly composed of alumina hydrate on the surface of the dielectric layer.
  • the film thickness of the silver-containing metal layer is preferably less than 3.5 nm.
  • the optical element of the present disclosure is an optical element including an antireflection film made of the optical thin film of the present disclosure.
  • the optical system of the present disclosure is an optical system including a combination lens in which the surface provided with the antireflection film of the optical element of the present disclosure is disposed on the outermost surface.
  • the outermost surface is one surface of the lens disposed at the end of the combined lens composed of a plurality of lenses, and is the surface that is the end surface of the combined lens.
  • the method for producing an optical thin film of the present disclosure is a method for producing an optical thin film for producing an optical thin film comprising a silver-containing metal layer containing silver and a dielectric layer containing a metal oxide on a substrate. And A film forming step of forming a dielectric layer in contact with a silver-containing metal layer provided on a substrate by using a film forming method performed in the presence of plasma; In the film formation step, the first region including the surface in contact with the silver-containing metal layer in the dielectric layer is formed more than the conditions for forming a film having a stoichiometric composition of a metal oxide. This is a method for producing an optical thin film, which is carried out under the first condition in which the oxygen concentration in the film becomes small.
  • the oxygen concentration in the film becomes higher than the first condition. It is preferable to form a film using the condition of 2.
  • the film forming method is a sputtering method.
  • a first condition when forming a film having a stoichiometric composition of a metal oxide, a smaller amount of oxygen than that introduced into the chamber may be introduced.
  • the optical thin film of the present disclosure includes a silver-containing metal layer containing silver provided on one surface of a base material and a dielectric layer laminated in contact with the silver-containing metal layer.
  • the dielectric layer contains a metal oxide
  • the first oxygen concentration in the first region including the first surface in contact with the silver-containing metal layer of the dielectric layer is such that the first oxide concentration of the metal oxide It is smaller than the oxygen concentration of the ikiometry composition.
  • FIG. 10 is a diagram showing the relationship between the Hamaker constant of the anchor metal diffusion control layer and the electrical resistivity of the silver film for Samples 11 to 17. It is a figure which shows the analysis result by the X-ray photoelectron spectroscopy about the sample 11 and the sample 17.
  • a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
  • an upper limit value or a lower limit value described in a numerical range may be replaced with an upper limit value or a lower limit value in another numerical range.
  • the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.
  • FIG. 1 is a schematic cross-sectional view of an optical element 11 including an optical thin film 1 according to the first embodiment of the present invention.
  • the optical thin film 1 of this embodiment includes a silver-containing metal layer 20 containing silver provided on one surface of a substrate 10 and a dielectric layer laminated in contact with the silver-containing metal layer 20.
  • the dielectric layer 30 contains a metal oxide, and the first oxygen concentration of the first region including the first surface 30a in contact with the silver-containing metal layer 20 of the dielectric layer 30 has a metal concentration of It is smaller than the oxygen concentration of the stoichiometric composition of the oxide.
  • silicon oxide, aluminum oxide, magnesium oxide, and the like having a sufficiently high light transmittance in the stoichiometric composition are suitable.
  • a metal oxide having an oxygen concentration smaller than the oxygen concentration of the stoichiometric composition means that the ratio of oxygen to metal contained is smaller than the ratio of oxygen to metal in the stoichiometric composition of the metal oxide. means.
  • the stoichiometric composition of silicon oxide is SiO 2 , but when silicon oxide is expressed as SiO n , if n is smaller than 2, the oxygen concentration is smaller than the stoichiometric composition.
  • the first oxygen concentration in the first region 31 is preferably 0.95 times or less of the oxygen concentration of the stoichiometric composition.
  • the first oxygen concentration is preferably 0.7 times or more, more preferably 0.8 times or more, and particularly preferably 0.9 times or more the oxygen concentration of the stoichiometric composition.
  • the dielectric layer 30 is a single layer, and the composition of the metal oxide constituting the dielectric layer 30 is uniform over the entire area. That is, the entire dielectric layer 30 is the first region and is a layer having the first oxygen concentration. In the region in direct contact with the silver-containing metal layer 20, it is preferable that the first region having the first oxygen concentration is provided over 5 nm or more in the film thickness direction. Therefore, when the dielectric layer 30 is a single layer as in this embodiment, the dielectric layer 30 preferably has a thickness of 5 nm or more. Further, when the dielectric layer 30 is a single layer, it is preferably less than 150 nm, more preferably 100 nm or less, and further preferably 50 nm or less.
  • the metal oxide used as the dielectric layer 30 has the maximum light transmittance in the stoichiometric composition, and the light transmittance decreases as the oxygen concentration decreases. Therefore, in order to ensure sufficient transparency, the following examination was performed. Here, the case where the metal oxide is silicon oxide was examined.
  • k is the extinction coefficient of the substance
  • d is the film thickness.
  • silicon oxide represented by SiOn
  • the extinction coefficient k 0 with respect to the wavelength of 400 nm, and in the case of SiO where the oxygen concentration is half of the oxygen concentration of the stoichiometric composition, with respect to the wavelength of 400 nm
  • the extinction coefficient k 0.132.
  • the extinction coefficient was quoted from “RefractiveIndex.INFO website, https://refractiveindex.info/” (reference date 2018-04-12).
  • composition and film thickness range satisfy ( ⁇ 0.264X + 0.264) ⁇ d ⁇ 1.64, the transparency can be sufficiently secured, which is preferable.
  • the silver in the silver-containing metal layer is oxidized and colored black and the refractive index may change.
  • the present inventors have found that this is a problem that particularly occurs when an oxide layer is formed by a vapor phase method, and particularly when a film is formed by a sputtering method.
  • a stoichiometric composition is preferred.
  • excess oxygen is introduce
  • silver is oxidized by this excessive oxygen.
  • the metal oxide formed as the dielectric layer 30 has a lower oxygen concentration than the stoichiometric composition. That is, at the time of film formation, without introducing excessive oxygen into the film formation atmosphere, an amount of oxygen smaller than that required at the stoichiometric composition is introduced, or metal is oxidized in an atmosphere without introducing oxygen. A physical layer is formed. By forming such a film, the oxidation of silver in the silver-containing metal layer during the formation of the dielectric layer can be suppressed, and an optical thin film that maintains the original low refractive index and transparency when thin is obtained. Obtainable.
  • the dielectric layer is mainly made of silicon oxide
  • the same effect can be obtained even when the dielectric layer is an oxide of another metal such as aluminum oxide or magnesium oxide.
  • the shape of the substrate 10 is not particularly limited, and is a transparent optical member (transparent substrate) mainly used in an optical device such as a flat plate, a concave lens, or a convex lens, and is configured by a combination of a curved surface and a flat surface having a positive or negative curvature. Substrates may also be used. A flexible film may be used as the substrate 10. As a material of the base material 10, glass or plastic can be used. In the present specification, “transparent” means that the internal transmittance is 10% or more with respect to light in the wavelength range of 400 nm to 800 nm, that is, visible light.
  • the refractive index of the substrate 10 is not particularly limited, but is preferably 1.45 or more.
  • the refractive index of the substrate 10 may be 1.61 or more, 1.74 or more, or even 1.84 or more.
  • a high power lens such as a first lens of a combined lens of a camera may be used.
  • the refractive index is shown as the refractive index for light having a wavelength of 550 nm.
  • the silver-containing metal layer 20 is a metal layer in which 50 atomic% or more of the constituent elements is silver.
  • silver is preferably 85 atomic% or more, and more preferably 90 atomic% or more.
  • the silver-containing metal layer 20 includes palladium (Pd), copper (Cu), gold (Au), neodymium (Nd), samarium (Sm), bismuth (Bi), platinum (Pt), and tin (Sn).
  • Aluminum (Al), zinc (Zn), magnesium (Mg), indium (In), gallium (Ga) and lead (Pb) may be contained.
  • the silver-containing metal layer 20 preferably contains a metal having a standard electrode potential higher than that of silver.
  • the silver-containing metal layer 20 has higher durability than a layer formed of only silver.
  • Noble metals such as gold, platinum, and palladium are examples of metals having a higher standard electrode potential than silver.
  • the real part of the refractive index of the silver containing metal layer 20 is 0.4 or less.
  • an Ag—Nd—Cu alloy, an Ag—Pd—Cu alloy, an Ag—Bi—Nd alloy, or the like is preferable as a material for forming the silver-containing metal layer 20.
  • the thickness of the silver-containing metal layer 20 is not limited, but is 20 nm or less, more preferably 10 nm or less, and more preferably 8 nm or less. The thinner, the greater the impact of silver being oxidized, and the higher the effect obtained by the technology of the present disclosure.
  • FIG. 2 is a schematic cross-sectional view of an optical element 12 including an optical thin film 2 according to the second embodiment of the present invention.
  • the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
  • the optical thin film 2 of this embodiment is similar to the optical thin film 1 of the said 1st Embodiment,
  • the silver containing metal layer 20 containing the silver provided on one surface of the base material 10 is shown.
  • the dielectric layer 30 contains a metal oxide, in addition to the first region 31 including the first surface 30a in contact with the silver-containing metal layer 20 of the dielectric layer 30.
  • the first region 31 and the second region 32 are made of the same type of metal oxide, but have different oxygen concentrations.
  • the first oxygen concentration in the first region 31 is smaller than the second oxygen concentration in the second region.
  • the first oxygen concentration is smaller than the stoichiometric composition of the metal oxide.
  • the second oxygen concentration in the second region 32 may be larger than the oxygen concentration in the first region 31 and not more than the stoichiometric composition of the metal oxide, but from the viewpoint of transparency, the second region
  • the second oxygen concentration of 32 is preferably a stoichiometric composition of a metal oxide.
  • the first region 31 is provided over 5 nm or more in the film thickness direction from the first surface 30 a. If the first region 31 is 2 nm or more, there is an effect of suppressing the oxidation of silver. However, if the first region 31 is provided over 5 nm or more, it is excessive in the film formation environment when forming the second region 32. Even when oxygen is introduced, the oxidation of silver can be sufficiently suppressed.
  • the refractive index of the dielectric layer 30 is preferably 1.35 or more and 1.51 or less.
  • the film thickness of the dielectric layer 30 is preferably about ⁇ / 4n where ⁇ is the target wavelength and n is the refractive index of the dielectric layer. Specifically, it is about 70 nm to 100 nm.
  • the dielectric layer 30 is made of the same kind of metal oxide and is composed of a first region 31 and a second region 32 having different oxygen concentrations.
  • regions having different oxygen concentrations may be included, and the oxygen concentration in the film thickness direction changes. You may do it.
  • the oxygen concentration is present at the boundary between the first region 31 and the second region 32. There is a case where there is a region where the value gradually changes.
  • the dielectric layer 30 may have a composition distribution in which the oxygen concentration gradually increases from the first surface 30a toward the second surface 30b and approaches the oxygen concentration of the stoichiometric composition. Good. Further, the oxygen concentration may change in a plurality of steps. Furthermore, a film region having a stoichiometric composition may be provided between the first region and the second region.
  • the film formation of the first region 31 directly formed on the silver-containing metal layer 20 in the dielectric layer 30 is made more than the case where a film having a stoichiometric composition is formed. Since it can be performed in an atmosphere with a small amount of oxygen, the same effect as the optical thin film 1 of the first embodiment that suppresses oxidation of silver can be obtained.
  • FIG. 3 is a schematic cross-sectional view of an optical element 13 including an optical thin film 3 according to the third embodiment of the present invention.
  • the optical thin film 3 of the present embodiment has a relatively high refractive index between the silver-containing metal layer 20 and the substrate 10 in the optical thin film 2 of the second embodiment.
  • An intermediate layer 40 including a high refractive index layer 41 and a low refractive index layer 42 having a relatively low refractive index is provided.
  • the antireflection performance can be further improved by providing such an intermediate layer 40.
  • the high refractive index layer 41 and the low refractive index layer 42 are each preferably provided with two or more layers, more preferably alternately stacked.
  • the base 10 side may be the low-refractive index layer or the high-refractive index layer.
  • the intermediate layer 40 is preferably composed of five or more layers.
  • middle layer 40 is 20 layers or less from a viewpoint of film-forming cost and film-forming time.
  • the refractive indexes of the high refractive index layer 41 and the low refractive index layer 42 are relatively determined and are not particularly limited.
  • the refractive index of the high refractive index layer 41 is about 1.6 to 2.4.
  • the refractive index of the low refractive index layer 42 is preferably about 1.3 to 1.8.
  • the refractive index of the high refractive index layer 41 is more preferably 1.8 or more, and the refractive index of the low refractive index layer 42 is more preferably less than 1.7.
  • the difference in refractive index between the adjacent high refractive index layer and low refractive index layer is preferably 0.4 or more, and more preferably 0.6 or more.
  • the refractive index of the intermediate layer is a value measured by ellipsometry at a wavelength of 550 nm.
  • the high refractive index layers 41 may not be the same material, and may not have the same refractive index. However, if the same refractive index is used as the same material, the material cost and the film forming cost are suppressed. From the viewpoint of Similarly, the low refractive index layers 42 do not have to be the same material and may not have the same refractive index. However, if the same refractive index is used as the same material, the material cost and the film forming cost are reduced. From the viewpoint of suppressing the above.
  • the material constituting the high refractive index layer 41 and the low refractive index layer 42 is not particularly limited as long as it satisfies the refractive index condition. These are not limited to the stoichiometric composition as long as they are transparent to the wavelength of the light to be prevented from being reflected, and a non-stoichiometric composition can also be used. Introduction of impurities is also allowed for adjustment of optical properties such as refractive index, mechanical properties, and productivity.
  • Examples of the material of the low refractive index layer 42 include silicon oxide, silicon oxynitride, gallium oxide, aluminum oxide, lanthanum oxide, lanthanum fluoride, magnesium fluoride, and mixtures thereof.
  • silicon oxynitride is preferable.
  • Examples of the material of the high refractive index layer 41 include niobium oxide, silicon niobium oxide, zirconium oxide, tantalum oxide, silicon nitride, titanium oxide, hafnium oxide, lanthanum titanate, and mixtures thereof.
  • the compound constituting the low refractive index layer and the high refractive index layer is controlled to have a constituent element ratio deviating from the composition ratio of the stoichiometric ratio, or the refractive index is controlled by controlling the film formation density. It can be changed to some extent.
  • the material constituting the low refractive index layer and the high refractive index layer is not limited to the above compound as long as the above refractive index condition is satisfied. Inevitable impurities may be included.
  • each layer of the intermediate layer 40 it is preferable to use a physical vapor deposition method such as vacuum vapor deposition (particularly EB vapor deposition) or sputtering, or various chemical vapor deposition methods (CVD).
  • a physical vapor deposition method such as vacuum vapor deposition (particularly EB vapor deposition) or sputtering, or various chemical vapor deposition methods (CVD).
  • CVD chemical vapor deposition methods
  • an ultra-thin silver film having a film thickness of 10 nm or less and further 6 nm or less as a smooth film. This is because when silver is formed by a vapor deposition method, silver is likely to aggregate and become granular.
  • a metal other than silver can be added and alloyed to suppress aggregation, but an anchor metal layer that suppresses aggregation of silver is formed on the formation surface. It is also effective to prevent silver aggregation.
  • the anchor metal layer bismuth (Bi), lead (Pb), tin (Sn), indium (In), magnesium (Mg), neodymium (Nd), zinc (Zn), Ga (gallium), germanium ( Ge) and silicon (Si), aluminum (Al), manganese (Mn), copper (Cu) and gold (Au).
  • Ge, Au and Al are preferable.
  • the anchor metal layer is preferably formed with a thickness of about 0.2 nm to 2 nm.
  • the anchor metal diffuses in the silver film and its interface region in the manufacturing process, so that it is optically handled integrally, and the silver-containing metal layer
  • the film thickness includes a region where the anchor metal is diffused.
  • the film thickness of the silver-containing metal layer 20 can be determined by X-ray reflectivity measurement. Specifically, for example, a signal near the critical angle can be measured using RIGAKU RINTULTIMA III (CuK ⁇ line 40 kV 40 mA), and the obtained vibration component can be extracted and fitted.
  • the metal which comprises an anchor metal layer is oxidized after film-forming of a silver film, and it makes it a metal oxide. Therefore, in the silver-containing metal layer, it is desirable that the content ratio of the anchor metal oxide is larger than the content ratio of the unoxidized anchor metal.
  • the magnitude relationship between the content of the anchor metal oxide and the content of the non-oxidized anchor metal can be confirmed by the signal intensity ratio in the measurement by X-ray photoelectron spectroscopy (XPS).
  • FIG. 4 shows the manufacturing process.
  • the intermediate layer 40 is formed on the substrate 10 (Step 1).
  • the anchor metal layer 21 and the silver film 22 are sequentially formed (Step 2).
  • a layer made of a metal having a higher standard electrode potential may be formed between the anchor metal layer 21 and the silver film 22. .
  • the film formation of the anchor metal layer 21 and the silver film 22 is performed in an atmosphere in which oxygen does not exist.
  • the film thickness of the anchor metal layer 21 is preferably about 0.2 nm to 2.0 nm.
  • middle layer 40, the anchor metal layer 21, and the silver film 22 is exposed to air
  • the annealing temperature is preferably from 100 ° C. to 400 ° C.
  • the annealing time is preferably from 1 minute to 2 hours.
  • the anchor metal layer 21 is transformed into the anchor region 24, and a cap region 26 made of a metal oxide formed by oxidizing the anchor metal is formed on the surface side of the silver-containing metal layer 20 (Step 3). ).
  • the anchor metal constituting the anchor metal layer 21 starts to move (diffuse) during the formation of the silver film 22 and moves to the surface side of the silver film 22.
  • the anchor metal layer 21 is transformed into an anchor region 24, and a cap region 26 containing a metal oxide formed by oxidizing the anchor metal that has passed through the silver film 22 and moved to the surface of the laminate is formed.
  • the silver-containing metal layer 20 includes a main body region 25, an anchor region 24, and a cap region 26.
  • a dielectric layer 30 is formed on the silver-containing metal layer 20.
  • the dielectric layer 30 may be formed by any film forming method performed in the presence of plasma.
  • the dielectric layer 30 may be formed by a sputtering method or an ion assist method.
  • a sputtering method or an ion assist method.
  • the film formation step of the dielectric layer 30 first, the first region 31 of the dielectric layer 30 is formed on the silver-containing metal layer 20 (Step 4). At this time, the film is formed under a first condition in which the oxygen concentration in the formed film is lower than the condition for forming a film having a stoichiometric composition of a metal oxide.
  • the condition for forming SiO 2 having a stoichiometric composition is that a SiO 2 target is used and oxygen at a predetermined flow rate is introduced into the chamber
  • the first condition is that the SiO 2 target is It is sufficient to use a smaller amount of oxygen than the above predetermined flow rate or not introduce oxygen.
  • oxygen defects are generated, and a film having an oxygen concentration lower than that of SiO 2 ⁇ x (x> 0) stoichiometry can be formed.
  • the second region 32 is subsequently formed.
  • the film is formed using the second condition in which the oxygen concentration in the film is higher than that of the film formed under the first condition (Step 5). For example, oxygen having a flow rate larger than that of oxygen introduced into the chamber under the first condition may be flowed.
  • a sufficient flow rate of oxygen may be introduced.
  • the optical thin film 3 of the third embodiment can be obtained.
  • the first region formed directly on the silver-containing metal layer is formed under conditions that cause oxygen vacancies in the formed film, so that the silver in the silver-containing metal layer is oxidized during the film formation. This phenomenon can be effectively suppressed. Therefore, it is possible to produce an optical thin film having no coloration and no change in refractive index caused by the oxidation of silver in the silver-containing metal layer.
  • an optical thin film is used as an antireflection film, transparency is ensured and a decrease in antireflection performance accompanying a change in refractive index can be suppressed.
  • FIG. 5 is a schematic cross-sectional view of an optical element 14 including an optical thin film 4 according to the fourth embodiment of the present invention.
  • the optical thin film 4 of this embodiment includes an anchor metal diffusion control layer 45 between the silver-containing metal layer 20 and the intermediate layer 40 in the optical thin film 3 of the third embodiment. Yes.
  • the anchor metal diffusion control layer 45 is a layer provided for controlling the diffusion of the anchor metal.
  • an ultra-thin silver-containing metal layer of 10 nm or less can be formed.
  • the inventors have found that when the film thickness of the silver-containing metal layer 20 is 6 nm or less, the diffusion of the anchor metal constituting the anchor metal layer must be controlled when further ultrathinning is attempted. It was. Aggregation of silver can be suppressed by forming a silver film in a state where the anchor metal layer is not oxidized.
  • the anchor metal diffuses, passes through the silver-containing metal layer, and moves to the cap region on the surface of the silver-containing metal layer. At this time, if all of the anchor metal moves to the cap region, the stability of the silver-containing metal layer 20 as a film is lowered, the flatness thereof is not maintained, and partial aggregation may occur.
  • an anchor metal diffusion control layer 45 is provided as an underlayer of the anchor metal layer in order to control excessive diffusion of the anchor metal.
  • the force to attract the anchor metal is important.
  • the Hamaker constant which is an index of van der Waals force known as a force for attracting materials
  • the present inventors have determined that the Hamaker constant is 7.3 ⁇ 10 ⁇ 20 J or more. It has been found that by providing the layer 45, the diffusion of the anchor metal can be suppressed, and an ultrathin silver-containing thin film layer of the order of several nm having high uniformity can be formed.
  • the Hamaker constant can be obtained as follows based on the van Oss theory.
  • ⁇ LW Liftshitz vdW
  • ⁇ LW a Liftshitz vdW (van der Waals) term
  • ⁇ ⁇ ⁇ donor term
  • ⁇ + acceptor term
  • the contact angles of the three liquids of water, diiodomethane, and ethylene glycol are measured, and the Lifshitz vdW term ( ⁇ LW ) in the surface energy of the thin film is calculated.
  • D 0 0.165 nm by referring to the translation by
  • the Hamaker constant is preferably 30.0 ⁇ 10 ⁇ 20 J or less.
  • the anchor metal diffusion control layer 45 is not limited to any constituent material as long as the Hamaker constant satisfies 7.3 ⁇ 10 ⁇ 20 J or more, but is preferably transparent to visible light and sufficiently transparent. It is preferable to contain a metal oxide, a metal nitride, a metal oxynitride or a metal carbide in order to obtain properties. Specific examples of the constituent material include Si, Nb, Hf, Zr, Ta, Mg, Al, La, Y, or Ti oxides, nitrides, oxynitrides, carbides, and mixtures thereof. In general, a metal nitride has a higher Hamaker constant than an oxide of the same metal, so that the effect of suppressing the diffusion of the anchor metal is high.
  • Hf oxide HfO 2
  • the occupation ratio of the Hf oxide in the anchor metal diffusion control layer is more preferably 50 mol% or more, and it is particularly preferably composed of only HfO 2 (occupation ratio is 100 mol%).
  • the inventors have confirmed that the homogeneity of the silver-containing metal layer is particularly high when HfO 2 is used (see Examples below).
  • the thickness of the anchor metal diffusion control layer 45 is preferably 5 nm or more and 100 nm or less in order to improve the adhesion with the silver-containing metal layer 20.
  • a material satisfying the above-described Hamaker constant may be used as the outermost layer of the intermediate layer 40.
  • one layer of the intermediate layer 40 also serves as the anchor metal diffusion control layer 45.
  • the intermediate layer 40 may be a low refractive index layer or a high refractive index layer as long as the conditions for the anchor metal diffusion control layer are satisfied.
  • FIG. 6 is a schematic cross-sectional view illustrating a schematic configuration of the optical element 15 including the optical thin film 5 according to the fifth embodiment.
  • the optical thin film 5 of the present embodiment is further provided with a fine uneven layer 50 on the surface of the dielectric layer 30 in the optical thin film 4 of the fourth embodiment.
  • the fine uneven layer 50 is mainly composed of alumina hydrate.
  • a main component means the component which occupies 80 mass% or more of the structural components of a fine uneven
  • alumina hydrate refers to boehmite (expressed as Al 2 O 3 .H 2 O or AlOOH), which is alumina monohydrate, and Bayerlite (Al 2 O, which is alumina trihydrate). 3 ⁇ 3H 2 O or Al (OH) 3 .
  • the fine concavo-convex layer 50 is transparent, and has a generally sawtooth cross section although the size of the convex portion (vertical angle size) and direction are various.
  • corrugated layer 50 is the distance of the vertexes of the nearest convex part which separated the recessed part. The distance is less than or equal to the wavelength of the light to be prevented from being reflected. It is preferably on the order of several tens of nm to several hundreds of nm, 200 nm or less, and more preferably 150 nm or less.
  • the fine uneven layer 50 is obtained by forming a thin film of a compound containing aluminum and immersing the thin film of the compound containing aluminum in hot water of 70 ° C. or higher for 1 minute or longer to perform hot water treatment.
  • hot water treatment after forming an aluminum-containing film by vapor deposition such as vacuum deposition, plasma sputtering, electron cyclotron sputtering, or ion plating.
  • the fine concavo-convex layer 50 made of hydrated alumina is provided on the outermost surface, it is necessary to perform hot water treatment as described above. Silver is oxidized by moisture. Therefore, when water enters from the fine uneven layer side to the silver-containing metal layer during the hot water treatment, there is a concern that the oxidation of silver is promoted by moisture and the silver-containing metal layer is damaged. However, since the dielectric layer functions as a protective film, moisture can be prevented from entering.
  • the optical thin film 5 of the present embodiment is particularly suitable as an antireflection film and exhibits a very low reflectance with respect to visible light.
  • the thickness of the silver-containing metal layer 20 including the anchor region and the cap region is preferably less than 3.5 nm. Further, the film thickness of the silver-containing metal layer 20 is preferably 0.5 nm or more, and more preferably 1.0 nm or more.
  • the film thickness of the silver-containing metal layer is 3.5 nm or more, a very low reflectance as an antireflection film can be realized by providing a fine uneven layer on the surface.
  • the effect of reducing the reflectance is remarkably enhanced by providing the fine uneven layer and making the film thickness of the silver-containing metal layer 20 less than 3.5 nm.
  • optical thin film 1 of the first embodiment, the optical thin film 2 of the second embodiment, or the optical thin film 3 of the third embodiment may be an optical thin film having a structure with the fine uneven layer 50 on the outermost surface.
  • Such an optical thin film is also an embodiment of the present invention.
  • the configuration including the fine uneven layer of boehmite includes the fine uneven layer such as the optical thin films 1, 2, 3, and 4 of the first to fourth embodiments. Very low reflectivity is obtained compared to a configuration without it. On the other hand, the rub resistance is much higher in the case where the fine uneven layer is not provided. Therefore, when the optical thin film of the present invention is used as an antireflection film, a configuration with a fine uneven layer or a structure without a fine uneven layer may be used as appropriate depending on the application.
  • optical thin film of the present disclosure may include other functional layers in addition to the above layers.
  • the optical thin film of each of the above embodiments can be used for a transparent conductive film or an antireflection film. It is particularly suitable as an antireflection film and can be applied to the surface of various optical members.
  • the optical thin film according to the first to fourth embodiments does not have a structure such as a concavo-convex structure or a porous structure on the surface, so that it has high mechanical strength and can be applied to a surface touched by a user's hand. It is. Since it can be applied to the surface of a lens having a high refractive index, it is suitable for the outermost surface of a known zoom lens described in, for example, Japanese Patent Application Laid-Open No. 2011-186417.
  • the optical thin film 3 according to the third embodiment described above is an antireflection film (hereinafter referred to as an antireflection film 3), and the assembled lens includes an optical element in which the antireflection film is provided on the surface of the lens.
  • FIGS. 7A, 7B, and 7C show configuration examples of a zoom lens that is an embodiment of the optical system of the present invention.
  • 7A shows the arrangement of the optical system at the wide-angle end (shortest focal length state)
  • FIG. 7B shows the arrangement of the optical system in the intermediate region (intermediate focal length state)
  • FIG. 7C shows the telephoto end (longest length). This corresponds to the arrangement of the optical system in the focal length state.
  • the zoom lens includes, in order from the object side along the optical axis Z1, a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, and a fifth lens group G5. It has.
  • the optical aperture stop S1 is preferably disposed near the object side of the third lens group G3 between the second lens group G2 and the third lens group G3.
  • Each lens group G1 to G5 includes one or more lenses Lij.
  • a symbol Lij indicates a jth lens that is assigned a symbol such that the most object side lens in the i-th lens group is the first lens and increases sequentially toward the imaging side.
  • This zoom lens can be mounted not only on video cameras and digital still cameras, but also on portable information terminals.
  • a member corresponding to the configuration of the photographing unit of the mounted camera is arranged on the image side of the zoom lens.
  • an imaging element 100 such as a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide Semiconductor) is disposed on the imaging surface (imaging surface) of the zoom lens.
  • Various optical members GC may be arranged between the final lens group (fifth lens group G5) and the image sensor 100 according to the configuration on the camera side where the lens is mounted.
  • zooming is performed by moving at least the first lens group G1, the third lens group G3, and the fourth lens group G4 along the optical axis Z1 and changing the interval between the groups. ing. Further, the fourth lens group G4 may be moved at the time of focusing.
  • the fifth lens group G5 is preferably always fixed during zooming and focusing.
  • the aperture stop S1 moves with, for example, the third lens group G3. More specifically, as the magnification is changed from the wide-angle end to the intermediate range and further to the telephoto end, each lens unit and the aperture stop S1 are further changed from the state shown in FIG. 7A to the state shown in FIG. 7B, for example. It moves to the state of 7 (C) so that the locus
  • the outermost surface of this zoom lens is provided with the antireflection film 3 on the outer surface (object side surface) of the lens L11 of the first lens group G1 and the lens L51 of the fifth lens group G5 which is the final lens group. That is, this is an embodiment of an optical element in which the lens L11 and the lens L51 are base materials and the antireflection film 3 is provided on the surface thereof. In this zoom lens, the antireflection film 3 may be similarly provided on other lens surfaces.
  • the antireflection film 3 Since the antireflection film 3 has a high mechanical strength, it can be provided on the outermost surface of the zoom lens that may be touched by the user, and a zoom lens having a very high antireflection performance can be configured.
  • a germanium film (film thickness 0.68 nm) is formed as an anchor metal layer on a SiO 2 glass substrate as a base material, and a gold film (film thickness 0.125 nm) is subsequently formed as a noble metal layer without exposure to the atmosphere.
  • a silver film (film thickness 4 nm) was further formed.
  • Each film was formed using a sputtering device (CFS-8EP) manufactured by Shibaura Mechatronics.
  • the film formation conditions for each film were as follows. Below, room temperature is 20 degreeC or more and 30 degrees C or less.
  • a dielectric layer was formed on the silver-containing metal layer.
  • Each example and comparative example differ in the structure of the dielectric layer.
  • a sputtering apparatus (CFS-8EP) manufactured by Shibaura Mechatronics was also used to form the dielectric layer.
  • the dielectric layer was formed by radio frequency (RF) sputtering.
  • -Dielectric layer deposition conditions A silicon oxide film was formed as the dielectric layer.
  • the film was formed under different film formation conditions depending on the composition of each film.
  • RF input power RF (W)
  • the flow rate introduction amount
  • Ar argon gas
  • O 2 sccm
  • Table 1 Each condition of the membrane pressure (Depo pressure (Pa)) is shown in Table 1 below.
  • the composition of the target was SiO 2.
  • the first region including the first surface in contact with the silver-containing metal layer of the dielectric layer was SiO 1.9
  • the second region subsequently provided in the first region was SiO 2
  • the second region is a region up to the second surface facing the first surface.
  • the thicknesses of the first region and the second region in each example were as shown in Table 2.
  • the stoichiometric composition of silicon oxide is SiO 2 .
  • the second region has a stoichiometric composition
  • the first region has a lower oxygen concentration than the stoichiometric composition.
  • Example 5 In Example 1, the first region was SiO 1.8 , the thickness of the first region was 50 nm, and the thickness of the second region was 50 nm.
  • the dielectric layer was made of SiO 1.9 over the entire area.
  • the dielectric layer was made of SiO 2 having a stoichiometric composition over the entire area.
  • the optical thin films of the examples and comparative examples were produced.
  • ⁇ Measurement of composition of dielectric layer> The concentration distribution of the contained elements in the depth direction (film thickness direction) was measured. The concentration distribution was measured using X-ray photoelectron spectroscopy (XPS). Quantera SXM manufactured by PHI was used as a measuring device. As a result, it was confirmed that the composition and thickness were almost as designed.
  • ⁇ Coloring evaluation> The coloration of the silver-containing metal layer after the dielectric layer was formed was evaluated visually.
  • the evaluation criteria are as follows. The coloring is caused by the oxidation of silver, and when it is oxidized, black or brown coloring is observed. A: There is no coloring. B: Slight coloring can be visually recognized. C: Clear coloring is visually recognized.
  • the refractive index of the silver-containing metal layer was determined by the following method. First, for each example and comparative example, the wavelength dependency of the double-sided transmittance and double-sided reflectance at wavelengths of 400 nm to 800 nm was measured with a spectrophotometer U-4000 (Hitachi High-Tech). And the refractive index of the silver containing metal layer which reproduces the measured value of the reflectance and transmittance obtained by this measurement was searched and derived with a self-made thin film calculation program.
  • the thin film calculation program was created with reference to literature (basic theory of optical thin film, Mitsunobu Kohatayama, Optronics, 2011).
  • the calculated refractive index value at a wavelength of 550 nm was evaluated according to the following criteria.
  • the uniformity of the silver-containing metal layer and the permeability of the laminated film were evaluated.
  • Comparative Example 1 since the coloring of silver was clear, the refractive index of the silver-containing metal layer was not obtained.
  • Table 2 shows the production conditions and evaluation results of each example and comparative example.
  • the composition of the dielectric layer formed in the region in contact with the silver-containing metal layer is such that the oxygen concentration is smaller than the stoichiometry, so that the silver is deposited during sputtering. It is clear that can be suppressed from being oxidized.
  • an anchor metal diffusion control layer made of the material shown in Table 3 was formed on a glass substrate.
  • a film was formed under the following conditions using a sputtering apparatus (CFS-8EP) manufactured by Shibaura Mechatronics.
  • the following anchor metal layer and silver film were also formed using the same sputtering apparatus.
  • an anchor metal layer made of Ge was successively formed without exposure to the atmosphere.
  • the anchor metal diffusion control layer was 20 nm
  • the anchor metal layer was 0.68 nm
  • the silver film was 2 nm.
  • the sample obtained as described above was evaluated for film uniformity and permeability.
  • the electrical resistivity increases due to a partial increase in resistance in a discontinuous part of the silver-containing metal layer and a part where the film thickness changes, and is an index of film uniformity.
  • the electrical resistivity decreases as the film uniformity (particularly flatness) increases, and increases as the film uniformity decreases.
  • Table 3 summarizes the film configuration and measurement (evaluation) results for Samples 11 to 17 produced and evaluated by the above method.
  • FIG. 10 is a graph showing the Ge element distribution in the depth direction from the surface in the stacking direction obtained by XPS toward the anchor metal diffusion control layer for Sample 11 and Sample 17. Drilling was performed by Ar + sputtering, and elemental analysis in the depth direction was performed.
  • the horizontal axis 0 is the laminate surface position.
  • the interface region between the silver-containing metal layer and the anchor metal diffusion control layer includes a region where the amount of Ge as an anchor metal increases, It can be seen that an anchor region is formed.
  • SiO 2 is used for the anchor metal diffusion control layer
  • Ge is reduced at the interface between the silver-containing metal layer and the anchor metal diffusion control layer, and the anchor metal layer formed on the anchor metal diffusion control layer It can be seen that most of Ge moves to the surface side of the silver-containing metal layer.
  • HfO 2 having a high Hamaker constant can effectively suppress the diffusion of Ge. Since the diffusion of Ge is suppressed, the function as an anchor region that suppresses granulation of the silver-containing metal layer by the anchor metal is maintained, and it is assumed that the planarization of the silver-containing metal layer has been realized.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Nonlinear Science (AREA)
  • Laminated Bodies (AREA)
  • Physical Vapour Deposition (AREA)
  • Surface Treatment Of Optical Elements (AREA)

Abstract

L'invention porte sur un film mince optique présentant un facteur de transmission de la lumière élevé ainsi qu'une durabilité élevée, sur un élément optique et un système optique équipés du film mince optique, et sur un procédé de production du film mince optique. Le film mince optique est pourvu d'une couche métallique contenant de l'argent disposée sur une surface d'un substrat et d'une couche diélectrique stratifiée de manière à être en contact avec la couche métallique contenant de l'argent, la couche diélectrique contenant un oxyde métallique, et une première concentration en oxygène dans une première région comprenant une première face de la couche diélectrique en contact avec la couche métallique contenant de l'argent étant inférieure à la concentration en oxygène dans une composition stœchiométrique de l'oxyde métallique.
PCT/JP2019/016524 2018-04-26 2019-04-17 Film mince optique, élément optique, système optique et procédé de production de film mince optique Ceased WO2019208366A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010224350A (ja) * 2009-03-25 2010-10-07 Sumitomo Metal Mining Co Ltd 吸収型多層膜ｎｄフィルターとその製造方法
WO2012127744A1 (fr) * 2011-03-18 2012-09-27 富士フイルム株式会社 Élément optique, et procédé de fabrication de celui-ci
WO2016189848A1 (fr) * 2015-05-28 2016-12-01 富士フイルム株式会社 Film anti-réflexion, élément optique et système optique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010224350A (ja) * 2009-03-25 2010-10-07 Sumitomo Metal Mining Co Ltd 吸収型多層膜ｎｄフィルターとその製造方法
WO2012127744A1 (fr) * 2011-03-18 2012-09-27 富士フイルム株式会社 Élément optique, et procédé de fabrication de celui-ci
WO2016189848A1 (fr) * 2015-05-28 2016-12-01 富士フイルム株式会社 Film anti-réflexion, élément optique et système optique

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