WO2019221255A1 - Method of forming surface microstructure, and article provided with surface microstructure - Google Patents

Abstract

Provided is a method of forming a surface microstructure with which it is possible to form, under mild conditions and without using strong chemicals or hole forming substances, a microstructure on a surface of an article simply and at low cost. Also, extending the object of processing even to articles on a surface of which it has been difficult to form a microstructure from the viewpoint of heat resistance, chemical resistance or the like, there is provided an article which is provided with a surface microstructure having hydrophilicity and/or low reflectance. The method of forming a surface microstructure is characterized by comprising: an item to be processed preparing step of preparing an item to be processed; a precursor layer stacking step of stacking over the item to be processed a precursor layer including a first substance and a second substance; and a processing step of dissolving the second substance by immersing the precursor layer obtained in the precursor layer stacking step in a processing solution.

Description

Method for forming surface microstructure and article having surface microstructure

The present invention relates to a method for forming a surface microstructure and an article having the surface microstructure.

For the purpose of imparting antifouling properties, antifogging properties, hydrophilicity, low reflectivity, etc., functional materials are coated on the surface of transparent substrates such as glass and plastic, and surfaces such as displays and optical materials. Things have been done.

Normally, the surface of window glass and mirrors has hydrophilicity, but dirt such as dust, dust, and oil adheres to it, and the dirt and hydrophilicity decrease, resulting in cloudiness and loss of transparency. Sometimes. In order to prevent such a phenomenon, a technique for imparting antifouling property and antifogging property by coating a surface such as titanium oxide on a surface of a window glass, a mirror or the like with a super hydrophilic property is known. .

When super hydrophilic coating is applied, even when dirt such as dust or oil adheres to the surface, self-cleaning that removes dirt by water entering between the surface and dirt by contact with water It is known to be effective. According to the super hydrophilic coating, it is possible to prevent soil from being fixed (antifouling property) and to spread the moisture adhering to the surface. Cloudiness).

Also, from the viewpoint of antireflection, display surfaces of various display devices such as liquid crystal display devices and organic EL display devices, optical members of optical devices such as lenses, imaging devices such as windows and showcases, outdoor surveillance cameras, and protective covers for solar cells For example, a low reflection film is provided on the surface of glass or plastic which is a transparent substrate.

In the case of display devices, windows, showcases, etc., if the surface reflection of a transparent base material such as glass or plastic is not suppressed, the reflected image is reflected and the visibility deteriorates, so it is necessary to impart low reflectivity. In addition, protective glasses for outdoor surveillance cameras and in-vehicle cameras, protective cover glasses for solar cells, etc. require low reflectivity, high light transmittance, durability, weather resistance, etc. from the viewpoint of light receiving efficiency and image pickup performance. . Furthermore, when the amount of reflected light on the lens surface of a lens used in an optical device is large, not only is there a large loss of transmitted light, but flare and ghosting due to multiple reflections within or between lenses is likely to occur, and the contrast is low. Therefore, it is necessary to take measures to suppress reflection.

For the purpose of imparting antifouling properties, antifogging properties, hydrophilicity, low reflectivity, etc., as a method of forming a surface microporous structure, a method using a sol-gel method, a material dissolved using a strong acid or a strong base Various production methods such as a treatment method and a method using a pore-forming substance such as a surfactant have been proposed.

For example, Patent Document 1 discloses that a porous silica precursor solution containing an inorganic-containing material and a surfactant is applied to a substrate, and is fired in a vacuum and in an inert gas atmosphere to thereby form porous silica on the substrate. A technique for forming an ultra-low refractive index film is described.
In Patent Document 2, a diluted solution of liquid glass diluted with an alcohol having 1 to 6 carbon atoms is applied on a glass substrate by a spin coating method or a roll coating method, and the temperature is 70 to 500 ° C. in an air atmosphere. A technique for producing an antireflection film having a nanoporous structure by drying is described.

JP 2006-350025 A JP 2016-157108 A

Conventional methods for forming a microporous structure use high-temperature processes and strong chemicals such as strong acids and strong bases, so that the substances to be treated are limited to materials such as glass with high durability and heat resistance. There was a problem.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a microstructure on the surface of an article easily and at low cost under mild conditions and without using strong chemicals or pore-forming substances. It is an object of the present invention to provide a method for forming a surface microstructure capable of forming a surface.
Another object of the present invention is to extend the object of treatment to articles that have been difficult to form a fine structure on the surface from the viewpoint of heat resistance, chemical resistance, etc. The object is to provide an article with a reflective surface microstructure.

According to the method for forming a surface fine structure of the present invention, the object is to prepare an object to be processed, and a precursor containing a first substance and a second substance on the object to be processed. A precursor layer laminating step for laminating a layer, and a treatment step for dissolving the second substance by immersing the precursor layer obtained in the precursor layer laminating step in a treatment liquid. Is done.
With the above configuration, a microstructure can be formed on the surface of the article by a simple method of immersing a precursor layer containing the first substance and the second substance in the treatment liquid.

At this time, the precursor layer stacking step is preferably performed using a method selected from a sputtering method, an ion plating method, a vacuum deposition method, and a chemical vapor deposition method.
According to the above configuration, in the precursor laminating process, it is not necessary to use special substances such as chemicals or heating at high temperature, so that it is possible to reduce labor and cost and to expand the target of the object to be processed. Become.

At this time, in the precursor layer stacking step, it is preferable that the precursor layer is stacked on the object to be processed using a target material or a vapor deposition material containing the first substance and the second substance. It is.
According to the above configuration, when preparing a target material or a vapor deposition material in which a first substance that is a base material of a fine structure and a second substance that is a readily soluble material are prepared, by adjusting the ratio mixing, It is possible to control the porosity of the surface microstructure.

At this time, the precursor layer stacking step is preferably performed at 80 ° C. or lower.
According to the above configuration, since heating at a high temperature is not required, the object to be processed can be extended to an object to be processed that contains a material that is weak against heat.

At this time, the treatment liquid used in the treatment step is preferably water.
According to the above configuration, since water that is not a special solvent or a strong chemical is used, the object to be processed can be extended to an object to be processed that contains a material that is weak to the special solvent or the chemical.

At this time, it is preferable that the water used in the treatment step has a temperature of 10 ° C. or more and 100 ° C. or less and a pH of 6 or more and 8 or less.
According to the above configuration, since water having a mild temperature and pH is used, it is possible to extend the processing target to an object to be processed that contains a material that is weak against heat, strong acid, strong base, or the like.

At this time, it is preferable that the first substance is insoluble or hardly soluble in the treatment liquid used in the treatment step, and the second substance is easily soluble in the treatment liquid used in the treatment step. It is.
According to the above configuration, the second substance is selectively dissolved in the treatment step and the first substance remains, so that a surface fine structure is formed by the first substance.

At this time, the first substance is one or more selected from the group including silicon oxide (SiO ₂ ), magnesium fluoride (MgF ₂ ), titanium oxide (TiO ₂ ), and tantalum oxide (Ta ₂ O ₅ ). A substance is preferred.
According to the above configuration, the surface fine structure can be formed by a substance having high stability and excellent durability and optical characteristics.

At this time, the second substance is selected from the group including germanium oxide (GeO _x ), molybdenum oxide (MoO _x ), tungsten oxide (WO ₃ ), zinc oxide (ZnO), and sodium chloride (NaCl). It is preferable that the substance is one or more substances.
According to the above configuration, since a substance such as an inorganic oxide that dissolves in water that is not a strong acidic or strong basic aqueous solution at a temperature around room temperature is used, a special solvent or strong chemical is used as a treatment liquid. In addition, since the second substance can be dissolved with water, the object to be processed can be extended to an object to be processed that contains a material weak to heat, a special solvent, a chemical, or the like.

At this time, it is preferable that the object to be processed contains one or more substances selected from the group including resin, glass, metal, alloy, and ceramics (metal oxide, metal nitride, metal oxynitride).
As described above, the method for forming a surface microstructure of the present invention can be applied to an object to be processed that includes various substances.

At this time, it is preferable that the object to be processed contains a resin.
Thus, the method for forming a surface microstructure of the present invention can be applied to an object to be processed that includes a resin.

At this time, it is preferable that the object to be processed is an article selected from a group including a lens, a half mirror, a touch panel, and a display device.
As described above, the method for forming a surface microstructure of the present invention can be applied to an object to be processed which includes various substances, and thus can be applied to various articles.

According to an article having a surface microstructure of the present invention, the object includes an article, an antireflection film formed on the article, and a microstructure formed on the antireflection film. An article with a surface microstructure characterized by:
With the above configuration, it is possible to achieve hydrophilicity and lower reflectivity in an article including an antireflection film.

At this time, the microstructure is formed of one or more substances selected from the group including silicon oxide (SiO ₂ ), magnesium fluoride (MgF ₂ ), titanium oxide (TiO ₂ ), and tantalum oxide (Ta ₂ O ₅ ). Preferably it is formed.
According to the above configuration, it is possible to provide an article having a surface microstructure having high stability and excellent durability and optical characteristics.

At this time, it is preferable that the article contains one or more substances selected from the group including resin, glass, metal, alloy, ceramics (metal oxide, metal nitride, metal oxynitride).
According to the said structure, the articles | goods provided with a surface fine structure can be provided in the articles | goods containing various substances.

At this time, the article preferably contains a resin.
According to the said structure, the articles | goods provided with a surface fine structure can be provided in the articles | goods containing resin.

At this time, the article is preferably an article selected from a group including a lens, a half mirror, a touch panel, and a display device.
According to the above configuration, an article having a surface microstructure can be provided in various articles.

At this time, it is preferable that the reflectance of the surface is 10% or less.
According to the said structure, the article | item provided with the low reflectance and the reflection of the surface was suppressed can be provided.

At this time, the water contact angle on the surface is preferably 10 ° or less.
According to the above configuration, an article having a low water contact angle and excellent in antifouling property and hydrophilicity can be provided.

According to the method for forming a surface microstructure of the present invention, it is possible to form a microstructure on the surface of an article easily and at low cost under mild conditions and without using strong chemicals or pore-forming substances. .
In addition, from the viewpoints of heat resistance, chemical resistance, etc., surface fineness that extends the object of processing to articles that have been difficult to form a fine structure on the surface and has hydrophilicity and / or low reflectivity. It is possible to provide an article comprising a structure.
Furthermore, in an article provided with an antireflection film, it is possible to achieve hydrophilicity and lower reflectivity.

It is a schematic cross section showing an article provided with a surface microstructure according to an embodiment of the present invention. It is a schematic cross section which shows the article | item provided with the surface microstructure laminated | stacked on the antireflection film which concerns on one Embodiment of this invention. It is a schematic cross section which shows the to-be-processed object which laminated | stacked the precursor layer which concerns on one Embodiment of this invention. It is a schematic cross section which shows the to-be-processed object which laminated | stacked the precursor layer which concerns on one Embodiment of this invention in multiple layers. It is a flow figure of the formation method of the surface fine structure concerning one embodiment of the present invention. 3 is a graph showing the transmittance at 400 to 700 nm of a glass substrate having the surface microstructure of Example 1 and Comparative Example 1. 4 is a graph showing the reflectance at 400 to 700 nm of a glass substrate having the surface microstructure of Example 1 and Comparative Example 1. 3 is a graph showing the absorptance at 400 to 700 nm of a glass substrate having the surface microstructure of Example 1 and Comparative Example 1. It is a figure which shows the result of the contact angle measurement of the sample of Example 2 before and behind dissolving a germanium oxide in a process process. It is a SEM photograph of the sample of Example 2 before and after dissolving germanium oxide in a processing process. 6 is a graph showing refractive indexes (n) at 300 to 800 nm of glass substrates having surface microstructures of Examples 3 to 7 and Example 2 after dissolving germanium oxide in the treatment step. 6 is a graph showing extinction coefficients (k) at 300 to 800 nm of glass substrates having surface microstructures of Examples 3 to 7 and Example 2 after germanium oxide is dissolved in the treatment step. 6 is a graph showing refractive indices (n) at 550 nm and 633 nm of glass substrates having surface microstructures of Examples 3 to 7 and Example 2 after dissolving germanium oxide in the treatment step. 7 is a graph showing extinction coefficients (k) at 550 nm and 633 nm of glass substrates having surface microstructures of Examples 3 to 7 and Example 2 after dissolving germanium oxide in the treatment process.

Hereinafter, a method for forming a surface microstructure and an article having the surface microstructure according to an embodiment of the present invention (hereinafter referred to as the present embodiment) will be described with reference to FIGS. 1A to 6D.
As shown in FIG. 1A, the article 1 having the surface microstructure of the present embodiment is formed by laminating a workpiece 10 and a surface microstructure 20 formed on the workpiece 10.

<Processing object 10>
In the method for forming a surface microstructure according to this embodiment, an object 10 (article 10) that is a target for forming a surface microstructure is an object to which functions such as antifouling properties, antifogging properties, and low reflectivity are imparted. The article is not particularly limited.

Specific examples of the object to be processed 10 include various display devices such as smartphones, tablet terminals, liquid crystal displays, organic EL displays, various computers, televisions, plasma display panels, touch panels and displays thereof, and outdoor surveillance cameras. (Security cameras) and human sensor lenses and window members (protective glass), window glass and mirrors for vehicles such as automobiles, trains and aircraft, window glass for buildings such as houses, lenses and window members for vehicle cameras ( Protective glass), antireflection sheet (antireflection film), antifouling sheet (antifouling film), antifogging sheet (antifogging film), polarizing plate used for liquid crystal display devices, eyeglass lenses made of transparent plastics, sunglasses lenses, Camera viewfinder lens, prism, fly-eye lens, toric lens Various optical lenses such as scanning optical systems used for laser beam printers, projection optical systems used for projection devices such as liquid crystal projectors, observation optical systems such as binoculars, imaging optical systems using them, liquid crystal projectors, etc. An optical member such as a cover of an instrument, a solar cell panel (solar cell protective cover glass), and the like may be mentioned, but it is not limited to these articles.

The workpiece 10 has a workpiece surface 10a, but the shape of the workpiece surface 10a is not limited to a flat surface, but is a curved shape such as a curved surface, a complicated shape, or an inner surface of a hollow member. There may be.

As will be described later, the method for forming the surface microstructure of the present embodiment does not require the use of a special solvent, strong acid, or strong base under mild conditions. Any material such as glass, metal, alloy, semiconductor, ceramics (metal oxide, metal nitride, metal oxynitride) can be selected.

In the method for forming a surface microstructure according to the present embodiment, a process for processing at a high temperature is not required, and therefore, it can be suitably applied to an object to be processed 10 containing a substance (material) that is weak against heat, such as a resin. is there.

The resin contained in the object to be processed may be either a thermoplastic resin or a thermosetting resin, for example, polyethylene (high density, medium density or low density), polypropylene (isotactic type or syndiotactic type). Polyolefins such as polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), ethylene-propylene-butene copolymer, cyclic polyolefin, modified polyolefin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide , Polyimide, polyamideimide, polycarbonate, poly- (4-methylbenten-1), ionomer, acrylic resin, polymethyl methacrylate, polybutyl (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, Chill (meth) acrylate-styrene copolymer, acrylic-styrene copolymer (AS resin), butadiene-styrene copolymer, polio copolymer (EVOH), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), Polyethylene such as ethylene-terephthalate-isophthalate copolymer, polyethylene naphthalate, precyclohexane terephthalate (PCT), polyether, polyetherketone (PEK), polyetheretherketone (PEEK), polyetherimide, polyacetal (POM) , Polyphenylene oxide, modified polyphenylene oxide, polyarylate, aromatic polyester (liquid crystal polymer), polytetrafluoroethylene (PTFE), polyvinylidene fluoride, other fluorine-based Various thermoplastic elastomers such as fat, styrene, polyolefin, polyvinyl chloride, polyurethane, fluororubber, chlorinated polyethylene, ethoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester, silicone resin, Cellulose resins such as polyurethane, nylon, nitrocellulose, cellulose acetate, cellulose acetate propionate, etc., or copolymers, blends, polymer alloys, etc. mainly comprising these, and one or two of these A combination of two or more species (for example, a laminate having two or more layers) may be used.

Examples of the glass contained in the object to be treated include silicate glass (quartz glass), alkali silicate glass, soda lime glass, potash lime glass, lead (alkali) glass, barium glass, and borosilicate glass.

Examples of the metal contained in the workpiece include gold, chromium, silver, copper, platinum, indium, palladium, iron, titanium, nickel, manganese, zinc, tin, tungsten, tantalum, and aluminum.
Further, stainless steels such as SUS316L, shape memory alloys such as Ti—Ni alloys or Cu—Al—Mn alloys, Cu—Zn alloys, Ni—Al alloys, titanium alloys, tantalum alloys, platinum alloys, which are alloys of the above metals. Alternatively, an alloy such as a tungsten alloy can be used.
An alloy is obtained by adding one or more metal elements or non-metal elements to the metal element. The alloy structure includes eutectic alloys in which the component elements become separate crystals, solid solutions in which the component elements are completely dissolved, and those in which the component elements form an intermetallic compound or a compound of a metal and a nonmetal. Although there is, it is not necessarily limited to this.

Examples of the ceramic contained in the object to be processed include oxides (for example, aluminum oxide, zinc oxide, titanium oxide, silicon oxide, zirconia, barium titanate), nitrides (for example, silicon nitride, boron nitride), carbides ( Examples thereof include silicon carbide) and oxynitrides. A mixture of these can also be used.

Examples of the metal oxide contained in the object to be processed include an oxide containing, for example, aluminum, copper, gold, silver, platinum, indium, palladium, iron, nickel, titanium, chromium, manganese, zinc, tin, tungsten, or the like as a metal. , Indium tin oxide (ITO), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), tin oxide (SnO ₂ , SnO), iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ), composite oxides having a perovskite structure, a spinel structure, and an ilmenite structure, but are not necessarily limited thereto.

Examples of the metal nitride contained in the workpiece include titanium nitride (TiN), zirconium nitride (ZrN), vanadium nitride (VN), niobium nitride (NbN), tantalum nitride (TaN), and chromium nitride (CrN, Cr ₂ N ) And hafnium nitride (HfN), but are not necessarily limited thereto.

<Surface microstructure 20>
The surface fine structure 20 (surface porous structure 20) is a layer having fine pores laminated on the surface 10a of the object 10 (article 10) or the antireflection film 30 of the object 10 to be processed. It is. The surface fine structure 20 is formed by dissolving the second substance contained in the precursor layer 40 with a treatment liquid in the method for forming a surface fine structure according to the present embodiment.

The surface microstructure 20 is composed of a base material (first substance), and includes silicon oxide (SiO ₂ ), magnesium fluoride (MgF ₂ ), titanium oxide (TiO ₂ ), and tantalum oxide (Ta ₂ O ₅ ). One or more substances selected from the group containing can be used, but the present invention is not limited to these substances.

Silicon oxide (SiO ₂ ) has a refractive index of n ₀ = 1.53514, and has a wide wavelength transmission region from the ultraviolet region of 0.147 μm to 4.5 μm to the infrared region.
In addition, since silicon oxide is a chemically stable and low-cost substance and has a Mohs hardness of 7, the surface microstructure is highly stable and durable when used as a base material (first substance). 20 can be constructed.

Magnesium fluoride (MgF ₂ ) has a wide wavelength transmission region from the ultraviolet light region of 0.11 μm to 7.5 μm to the infrared light region. Magnesium fluoride (MgF ₂ ) is used as an antireflection film by being deposited on glass as an optical film material having an ultra-low refractive index (n ₀ = 1.38359). Further, since magnesium fluoride has a Mohs hardness as high as 6, when used as a base material (first substance), it is possible to construct a highly durable and ultra-low reflection surface microstructure 20.

By appropriately selecting a base material (first substance) constituting the surface microstructure 20 according to this embodiment, an ultraviolet region (10 nm to 380 nm), a visible light region (380 to 800 nm), an infrared light region ( In a desired wavelength region such as 800 nm to 1000 μm, it is possible to construct a surface microstructure 20 that exhibits low reflectivity.

The thickness of the surface microstructure 20 may be appropriately selected according to the shape and application of the object to be processed 10, and is preferably several nm or more and several μm or less, more preferably several nm or more and 30 μm or less, and more The thickness is preferably several nm to 10 μm, more preferably 10 nm to 5.0 μm, and still more preferably 10 nm to 1.0 μm. If the surface microstructure 20 is too thin, it is not preferable from the viewpoint of durability. On the other hand, if the surface microstructure 20 is too thick, it may not be preferable from the viewpoints of a decrease in transmittance, a decrease in flexibility, a reduction in weight, a cost, and the like depending on the use of the workpiece 10.

The article 1 having a surface microstructure has a reduced surface reflectance due to the lamination of the surface microstructure 20, and the reflectance at a wavelength of 400 to 700 nm (for example, 550 nm) of the surface is 20% or less. Preferably, it is 15% or less, more preferably 10% or less, still more preferably 7% or less, and particularly preferably 5% or less. Since the reflectance value of the surface is in the above range, it is possible to suppress the reflection of the surface of the workpiece 10.

The article 1 having a surface microstructure has improved surface hydrophilicity by laminating the surface microstructure 20, and the water contact angle of the surface is 10 ° or less, preferably 8 ° or less, more preferably 5 ° or less. Since the water contact angle on the surface of the surface microstructure 20 is in the above range, it has high wettability with respect to water, and attached dirt and foreign matter can be easily removed by washing with water. It is possible to prevent fogging.

<Antireflection film 30>
Moreover, the article provided with the surface microstructure of the present embodiment is formed on the object to be processed 10, the antireflection film 30 formed on the article, and the antireflection film 30, as shown in FIG. 1B. An article 1A in which the surface microstructure 20 thus formed is laminated may be used.

The antireflection film 30 has a reflectance of 10% or less, preferably 8% or less, more preferably 7% or less, still more preferably 6% or less, laminated on the surface 10a of the object 10 (article 10). Particularly preferably, it is a layer having a low reflectance of 5% or less, such as silicon oxide (SiO ₂ ), magnesium fluoride (MgF ₂ ), titanium oxide (TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), etc. It is formed by the substance. The antireflection film may be a single layer or a multilayer of two or more layers. FIG. 1B shows an example in which the antireflection film 30 includes two layers of a first antireflection film 30a and a second antireflection film 30b.

In this specification, the antireflection film 30 is regarded as a part of the workpiece 10 (article 10). Specifically, the workpiece 10 (article 10) on which the antireflection film 30 is laminated is regarded as a workpiece (article), and the surface of the antireflection film 30 is regarded as the surface of the workpiece.

<Precursor layer 40>
The surface microstructure 20 of the articles 1 and 1A having the surface microstructure according to the present embodiment is formed by processing the precursor layer 40 with a processing liquid according to the method for forming the surface microstructure according to the present embodiment.

The precursor layer 40 includes a base material (first substance) and a readily soluble substance (on the object surface 10a of the object 10 (article 10) or the antireflection film 30 of the object 10 to be processed). A layer containing a second substance). In the method for forming a surface microstructure according to this embodiment, the precursor layer 40 is a layer that becomes the surface microstructure 20 by dissolving the second substance with a treatment liquid.

The precursor layer 40 may be a single layer as shown in FIG. 1C, but is not limited to this, and may have a multilayer structure in which a plurality of precursor layers are stacked. In FIG. 1D, the first precursor layer 40a, the second precursor layer 40b, and the third precursor layer 40c are sequentially laminated on the workpiece surface 10a of the workpiece 10 (article 10). The layer structure is shown.

Here, the plurality of precursor layers may contain a base material (first substance) and a readily soluble substance (second substance) in the same or different ratio.

(Base material-first substance)
The base material (first substance) that constitutes the precursor layer 40 is a substance that is insoluble or hardly soluble in the treatment liquid used in the treatment step, and is an object to be treated together with a readily soluble substance (second substance). There is no particular limitation as long as it is a substance that can be formed on the surface 10a.

As a base material (first substance), for example, a kind selected from the group including silicon oxide (SiO ₂ ), magnesium fluoride (MgF ₂ ), titanium oxide (TiO ₂ ), and tantalum oxide (Ta ₂ O ₅ ) The above substances can be used, but are not limited to these substances.

When a water-insoluble inorganic substance such as silicon oxide (SiO ₂ ) or magnesium fluoride (MgF ₂ ) is used as the base material (first substance), water can be used as a treatment liquid in the treatment step. Is preferred.
Further, the surface microstructure according to this embodiment formed using silicon oxide (SiO ₂ ) or magnesium fluoride (MgF ₂ ) as a base material is preferable because it is transparent in a specific wavelength region and has a low reflectance. It is.

(Easily soluble substance-second substance)
The easily soluble substance (second substance) constituting the precursor layer 40 is a substance that dissolves in the treatment liquid used in the treatment step, and is formed on the surface 10a to be treated together with the base material (first substance). There is no particular limitation as long as it is a possible substance.

Examples of the readily soluble substance (second substance) include germanium oxide (GeO _x ), molybdenum oxide (MoO _x ), tungsten oxide (WO ₃ ), zinc oxide (ZnO), and sodium chloride (NaCl). One or more substances selected from the group can be used, but are not limited to these substances.

When a water-soluble inorganic substance such as a water-soluble metal oxide is used as the easily soluble substance (second substance), water can be used as a treatment liquid in the treatment process, which is preferable.
Examples of the water-soluble metal oxide include molybdenum oxide (MoO _x , x = stoichiometric ratio, 2 ≦ x ≦ 3), germanium oxide (GeO _x , x = stoichiometric ratio, 1 ≦ x ≦ 2), tungsten oxide (WO ₃ ), and the like, but are not limited thereto.

The readily soluble substance (second substance) constituting the precursor layer 40 is preferably a substance that dissolves in water at 10 to 50 ° C. and pH 4.0 to 10.0 in the bulk state. Even if it is water-insoluble, it may be any substance that dissolves in water at 10 to 50 ° C. and pH 4.0 to 10.0 when it is formed to a film thickness of several tens nm to several μm.

In addition, when a metal oxide is used as the readily soluble substance, when expressed by the general formula MO _x (M = metal, x = stoichiometric ratio), the value of x indicates the charge balance between the metal ion and the oxide ion. The value that becomes zero is normal, but it may be a value of x where the electrification balance of metal ions and oxide ions slightly deviates from zero.

The solubility of the metal oxide in water is 0.14 g / 100 mL (20 ° C.) for MoO ₃ which is a molybdenum oxide, and 0.447 g / 100 mL for hexagonal GeO ₂ which is a germanium oxide. In WO ₃ which is a tungsten oxide, it is less than 0.46 g / 100 mL.

The thickness of the precursor layer 40 may be appropriately selected according to the thickness of the surface microstructure formed on the workpiece 10, and is preferably several nm or more and several μm or less, more preferably several nm or more. It is 30 μm or less, more preferably several nm to 10 μm, further preferably 10 nm to 5.0 μm, and further preferably 10 nm to 1.0 μm. If the thickness of the precursor layer 40 becomes too thin, it is not preferable from the viewpoint of the durability of the formed surface microstructure. On the other hand, if the precursor layer 40 is too thick, it is not preferable because it may take a long time until the easily soluble substance (second substance) is dissolved in the treatment liquid in the treatment step, or it may not be sufficiently dissolved. .

The method for forming the precursor layer 40 on the workpiece 10 may be a physical vapor deposition method such as a vacuum vapor deposition method, a sputtering method, or an ion plating method, or a chemical vapor deposition method, but is not limited thereto. However, a chemical method such as a sol-gel method can also be used depending on the material constituting the workpiece 10 and the material of the precursor layer.

<Method for forming surface microstructure>
Article 1 provided with the surface microstructure of the present embodiment is manufactured by the following method for forming the surface microstructure as shown in FIG.

Specifically, the surface microstructure forming method of the present embodiment includes a processing object preparation step (step S1) for preparing a processing object (article) 10, and a first substance on the processing object 10. And a precursor layer laminating step (step S2) for laminating the precursor layer 40 containing the second substance, and the precursor layer 40 obtained in the precursor layer laminating step is immersed in a treatment liquid, And a processing step (step S3) for dissolving the substance.

Through the above steps S1 to S3, the article 1 having a surface microstructure can be obtained.
Hereinafter, each step will be described in detail.

(Process preparation process)
In the processing object preparation step (step S1), a processing object 10 (article 10) to be processed is prepared. At this time, pretreatment is performed in advance to improve the film formability (stackability) of the precursor layer 40, such as cleaning the surface 10a of the object 10 to be processed or charging. May be.

(Precursor layer lamination process)
In the precursor layer laminating step (step S2), the precursor layer 40 including the first substance and the second substance is laminated on the workpiece surface 10Aa of the workpiece 10 prepared in the workpiece preparation process. To do.

The precursor layer stacking step can be performed using a method such as a sputtering method, an ion plating method, a vacuum deposition method, or a chemical vapor deposition method depending on the material of the object to be processed 10 or the precursor layer 40. However, it is not limited to these methods. Depending on the material constituting the object to be processed 10 and the material of the precursor layer, a method such as a sol-gel method may be employed.

The precursor layer 40 is preferably stacked using a target material or a vapor deposition material containing a base material (first substance) and a readily soluble substance (second substance).
Specifically, when silicon oxide is used as the base material and germanium oxide is used as the easily soluble substance, a mixed target or mixed vapor deposition material in which silicon oxide and germanium oxide are mixed may be used.
Note that it is also possible to use a reactive sputtering method in which an oxygen gas is supplied using a target material containing a base material or a readily soluble material, for example, a target containing silicon and germanium.

When the precursor layer laminating step is performed at 80 ° C. or lower using a sputtering method, an ion plating method, a vacuum vapor deposition method, a chemical vapor deposition method or the like, an object to be processed containing a heat-sensitive substance (material) such as a resin. 10 can be suitably applied.

In the precursor layer lamination step, a plurality of precursor layers containing the base material (first substance) and the readily soluble substance (second substance) in the same or different ratios can be laminated.

(Processing process)
In the processing step (step S3), the precursor layer 40 laminated on the workpiece surface 10Aa of the workpiece 10 obtained in the precursor layer laminating step is immersed in the treatment liquid to dissolve the second substance. To do.

In the treatment step, it is preferable to use water as a treatment liquid capable of selectively dissolving the easily soluble substance (second substance) without dissolving the base material (first substance). The water used here only needs to be able to dissolve a readily soluble substance (second substance) without affecting the base material (first substance), and has a temperature of 0 to 100 ° C., preferably 10 to 100 ° C. Water, more preferably water at 10 to 60 ° C., still more preferably water at 20 to 50 ° C., particularly preferably water at 30 to 50 ° C. Water having a temperature of 20 ° C. or more and 50 ° C. or less is preferable because a long-time heat treatment is unnecessary even when a large amount of water is required, and water as a treatment liquid can be easily prepared. .

The pH of the water may be within a range in which the easily soluble substance (second substance) can be selectively dissolved without dissolving the base material (first substance), preferably pH 4 to 10, and preferably pH 5 to 9, more preferably pH 6-8. If pH is 6 or more and 8 or less, it is possible to process the water after peeling as waste water without adjusting the pH.
In the treatment step, it is more preferable to use neutral water as a treatment solution at a temperature of 20 to 50 ° C. and a pH of 6 to 8 near room temperature.

In addition, it is desirable to use water from which various metal ions and impurities are removed, such as distilled water, pure water, and ultrapure water, but is not limited thereto, and tap water, industrial water, well water It is also possible to use water such as.
Distilled water is water having an electric conductivity of about 1 to 10 μS / cm, which is heated to water vapor and then returned to a liquid by cooling.
Pure water is high-purity water having an electrical conductivity of 1 μS / cm or less from which impurities such as ions, fine particles, microorganisms, and organic substances are removed.
Ultrapure water is extremely high-purity water having a higher purity than that of pure water removed from suspended substances, dissolved substances, and high efficiency in an ultrapure water production apparatus, and has an electric conductivity of less than 0.055 μScm.

In this embodiment, when an inorganic oxide that dissolves in water at 10 to 50 ° C. and pH 4.0 to 10.0 is selected as a base material (first substance), an acidic aqueous solution such as an aqueous hydrochloric acid solution or an aqueous nitric acid solution, There is an advantage that an easily soluble substance (second substance) can be dissolved without using a basic aqueous solution such as an aqueous sodium hydroxide solution.

In the treatment step, it is preferable that the easily soluble substance (second substance) dissolves within 60 minutes, for example, by immersing the object 10 on which the precursor layer 40 is laminated in the treatment liquid. More preferably. It is particularly preferable that the readily soluble substance (second substance) dissolves immediately after being immersed in the treatment liquid. Moreover, it is also possible to perform ultrasonic irradiation or stirring with a stirrer with respect to the precursor layer 40 immersed in water in order to promote dissolution of the readily soluble substance (second substance) in water.

In the present embodiment, the surface microstructure forming method and the article provided with the surface microstructure according to the present invention have been mainly described.
However, said embodiment is only an example for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof.

Hereinafter, specific examples of the method for forming the surface microstructure and the article having the surface microstructure of the present invention will be described, but the present invention is not limited thereto.

<A. Formation of Surface Microstructure According to Example 1 and Comparative Example 1>
(A-1. Precursor layer forming step)
On the following conditions, the precursor layer which concerns on Example 1 and Comparative Example 1 was laminated | stacked on the glass base material as a to-be-processed object.
Sputtering device: Carousel type batch type sputtering device Target: φ150, thickness 6mm
Example 1: Germanium oxide (GeO ₂ ) 50 vol% / silicon oxide (SiO ₂ ) 50 vol% mixed target Comparative Example 1: Germanium oxide (GeO ₂ ) 100 vol%
Sputtering method: RF sputtering Exhaust device: Turbo molecular pump Ultimate vacuum: 5 × 10 ⁻⁴ Pa
Substrate temperature: 25 ° C. (room temperature)
Sputtering power: 1.2 kW
Film thickness of precursor layer: 100 ± 10 nm
Ar flow rate: 120 sccm
Oxygen flow rate: 0 sccm
Substrate used: Glass substrate (1.0 mm thick)

(A-2. Processing step)
The glass substrate on which the precursor layers of Example 1 and Comparative Example 1 were laminated was immersed in pure water (manufactured by Mac Ace KN type, Kurita Kogyo Co., Ltd., pH 7.0) at room temperature (25 ° C.), and the precursor The germanium oxide contained in the layer was dissolved.

(Test A1 spectroscopic measurement)
After the germanium oxide was dissolved in the treatment step, the reflectance, transmittance, and absorption rate of the glass substrate provided with the surface microstructure of Example 1 and Comparative Example 1 were measured. The measurement was performed using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies Corporation) in a wavelength region of 400 nm to 700 nm.

The results of the spectroscopic measurement are shown in FIGS. 3A to 3C.
In the sample of Comparative Example 1, the absorption rate was almost zero, and it was found that all the precursor layers were dissolved. On the other hand, the reflectance of the sample of Example 1 was lower than that of the sample of Comparative Example 1. From the test A1, it was suggested that in the sample of Example 1, germanium oxide contained in the precursor layer was dissolved, thereby forming a surface microstructure and lowering the reflectance.

<B. Formation of Surface Microstructure According to Examples 2 to 5 and Comparative Example 2>
(B-1. Precursor layer forming step)
Under the following conditions, the precursor layers according to Examples 2 to 5 and Comparative Example 2 were laminated on a glass substrate as an object to be processed.
Sputtering device: Carousel type batch type sputtering device Target: φ150, thickness 6mm
Example 2: Germanium oxide (GeO ₂ ) 20 vol% / silicon oxide (SiO ₂ ) 80 vol% mixed target Example 3: Germanium oxide (GeO ₂ ) 40 vol% / silicon oxide (SiO ₂ ) 60 vol% mixed target Example 4: Germanium oxide (GeO ₂ ) 60 vol% / silicon oxide (SiO ₂ ) 40 vol% mixed target Example 5: Germanium oxide (GeO ₂ ) 80 vol% / silicon oxide (SiO ₂ ) 20 vol% mixed target Comparative Example 2: Germanium oxide (GeO) ₂ ) 100 vol%
Sputtering method: RF sputtering Exhaust device: Turbo molecular pump Ultimate vacuum: 5 × 10 ⁻⁴ Pa
Substrate temperature: 25 ° C. (room temperature)
Sputtering power: 1.2 kW (Examples 2 to 4), 0.42 kW (Example 5)
Film thickness of precursor layer: 50 ± 5 nm
Ar flow rate: 120 sccm
Oxygen flow rate: 0 sccm
Substrate used: Glass substrate (1.0 mm thick)

(B-2. Processing step)
The glass substrate on which the precursor layers of Examples 2 to 5 were laminated was immersed in pure water (manufactured by Mac Ace KN type, Kurita Kogyo Co., Ltd., pH 7.0) at room temperature (25 ° C.) to form a precursor layer. The germanium oxide contained was dissolved.

(Test B1 spectroscopic measurement)
The reflectance, transmittance, and absorptivity of the glass substrates provided with the surface microstructures of Examples 2 to 5 before and after dissolving germanium oxide in the treatment process were measured. The measurement was performed using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies Corporation) in a wavelength region of 400 nm to 700 nm.

(Test B2 contact angle measurement)
The water contact angle of the glass substrate provided with the surface microstructures of Examples 2 to 5 after dissolving germanium oxide in the treatment step was measured (Table 2: after treatment). The measurement was performed at 25 ° C. using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model number FACE CA-X type). As a reference, the water contact angle of the sample before dissolving germanium oxide in the treatment step was measured (Table 2: before treatment).

(Test B3 electron microscope observation)
Field emission scanning electron microscope (FE-SEM, Hitachi High-Technologies Corporation) shows the state of the surface and cross section of the glass substrate having the surface microstructure of Examples 2 to 5 before and after dissolving germanium oxide in the treatment process. And S-4300).

(Result B1 spectroscopic measurement)
The results of the spectroscopic measurement are shown in Table 1. In Table 1, the values of transmittance, reflectance, and absorptance before and after treatment at a wavelength of 550 nm are shown together with the amount of change.
In the samples of Examples 3 to 5, the reflectance was lowered, suggesting that the surface microstructure was formed by the dissolution of germanium oxide contained in the precursor layer.

(Result B2 Contact angle measurement)
The results of contact angle measurement are shown in Table 2. Before the germanium oxide was dissolved, the water contact angle was 45.3 ° to 48.5 °, indicating water repellency. After the germanium oxide was dissolved in the treatment step, the water contact angle decreased from 4.7 ° to 5.3 °, indicating super hydrophilicity.

(Result B3: Observation with an electron microscope)
There was no change in the electron microscope image before and after the treatment.

<C. Formation of Surface Microstructure According to Example 6>
(C-1. Precursor layer forming step)
Under the following conditions, the precursor layer according to Example 6 was laminated on a glass substrate as an object to be processed.
The precursor layer of Example 6 is obtained by stacking four layers (layers 1 to 4) having different ratios of silicon oxide and germanium oxide.
Sputtering device: Carousel type batch type sputtering device Target: φ150, thickness 6mm
Layer 1: Silicon oxide (SiO ₂ ): Germanium oxide (GeO ₂ ) = 80 vol%: 20 vol% mixed target Layer 2: Silicon oxide (SiO ₂ ): Germanium oxide (GeO ₂ ) = 60 vol%: 40 vol%
Layer 3: Silicon oxide (SiO ₂ ): Germanium oxide (GeO ₂ ) = 40 vol%: 60 vol%
Layer 4: Silicon oxide (SiO ₂ ): Germanium oxide (GeO ₂ ) = 20 vol%: 80 vol%
Sputtering method: RF sputtering Exhaust device: Turbo molecular pump Ultimate vacuum: 5 × 10 ⁻⁴ Pa
Substrate temperature: 25 ° C. (room temperature)
Sputtering power: 1.2, 1.2, 1.2, 0.42 kW (SiO ₂ ): 0.1, 0.24, 0.5, 0.5 kW (GeO ₂ )
Film thickness of precursor layer: 400 ± 40 nm
Layer 1: 100 ± 10 nm
Layer 2: 100 ± 10 nm
Layer 3: 100 ± 10 nm
Layer 4: 100 ± 10 nm
Ar flow rate: 120 sccm
Oxygen flow rate: 0 sccm
Substrate used: Glass substrate (1.0 mm thick)

(C-2. Processing step)
The glass substrate on which the precursor layer of Example 6 was laminated was immersed in pure water (manufactured by Mac Ace KN type, Kurita Kogyo Co., Ltd., pH 7.0) at room temperature (25 ° C.) and contained in the precursor layer. Germanium oxide was dissolved.

(Test C1 contact angle measurement)
The water contact angle of the glass substrate provided with the surface microstructure of Example 2 after dissolving germanium oxide in the treatment step was measured (Table 1: after water treatment). The measurement was performed at 25 ° C. using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model number FACE CA-X type). As a reference, the water contact angle of the sample before dissolving germanium oxide in the treatment step was measured (Table 3: before water treatment).

The results of contact angle measurement are shown in FIG.

Before the germanium oxide was dissolved, the water contact angle was 47.18 ° on average, indicating water repellency. In the sample of Example 6 in which germanium oxide was dissolved in the treatment step, the water contact angle was reduced to 5.04 ° on average, indicating super hydrophilicity.

(Test C2 electron microscope observation)
Before and after dissolving germanium oxide in the treatment step, the surface and cross-sectional state of the glass substrate having the surface microstructure of Example 6 were measured with a field emission scanning electron microscope (FE-SEM, manufactured by Hitachi High-Technologies Corporation) S-4300).

The results are shown in FIG. It was found that nano-scale pores were formed after use after dissolving germanium oxide. In the sample of Example 6, it was found that the surface microstructure was formed by the remaining silicon oxide by dissolving germanium oxide contained in the precursor layer.

<D. Formation of Surface Microstructure According to Examples 7 to 11>
(D-1. Precursor layer forming step)
Under the following conditions, the precursor layers according to Examples 7 to 11 were laminated on a glass substrate as an object to be processed.
Sputtering device: Carousel type batch type sputtering device Target: φ150, thickness 6mm
Examples 7 to 9: Germanium oxide (GeO ₂ ) 40 vol% / silicon oxide (SiO ₂ ) 60 vol% mixed target Example 10: Germanium oxide (GeO ₂ ) 45 vol% / silicon oxide (SiO ₂ ) 55 vol% mixed target 11: Germanium oxide (GeO ₂ ) 50 vol% / silicon oxide (SiO ₂ ) 50 vol% mixed target Sputtering method: RF sputtering Exhaust device: Turbo molecular pump Ultimate vacuum: 5 × 10 ⁻⁴ Pa
Substrate temperature: 25 ° C. (room temperature)
Sputtering power: 0.26, 0.32 (GeO ₂ ) kW: 1.2, 1.2 (SiO ₂ )
Film thickness of precursor layer Example 7: 500 ± 50 nm
Example 8: 250 ± 25 nm
Example 9: 100 ± 10 nm
Example 10: 100 ± 10 nm
Example 11: 100 ± 10 nm
Ar flow rate: 120 sccm
Oxygen flow rate: 0 sccm
Substrate used: Glass substrate (1.0 mm thick)

(D-2. Processing step)
The glass substrate on which the precursor layers of Examples 7 to 11 were laminated was immersed in pure water (manufactured by Mac Ace KN type, Kurita Kogyo Co., Ltd., pH 7.0) at room temperature (25 ° C.) for 14 hours. The germanium oxide contained in the layer was dissolved.

(Test D1 Optical constant measurement)
The optical constants of the glass substrates having the surface microstructures of Examples 7 to 11 and Example 6 after dissolving germanium oxide in the treatment step were measured. The optical constant was measured using a spectroscopic ellipsometer (manufactured by JASCO Corporation, M-220).

Results of optical constant measurement are shown in FIGS. 6A to 6D and Table 4. 6A is a graph showing the refractive index (n) at 300 to 800 nm, FIG. 6B is a graph showing the extinction coefficient (k) at 300 to 800 nm, and FIG. 6C shows the refractive index (n) at 50 nm and 633 nm. FIG. 6D is a graph showing the extinction coefficient (k) at 550 nm and 633 nm.

From the results of optical constant measurement, a precursor layer having a film thickness of 100 to 500 nm is formed using a target having a volume ratio of germanium oxide (GeO ₂ ): silicon oxide (SiO ₂ ) of 50:50 to 60:40. Then, it was found that the refractive index is small and reflection is suppressed in the visible light region. Further, it was found that the extinction coefficient was zero in the visible light region, and good visible light transmittance was exhibited.

<E. Formation of Surface Microstructure According to Examples 12 and 13>
(E-1. Precursor layer forming step)
On the following conditions, the precursor layer which concerns on Example 12 and 13 was laminated | stacked on the glass base material as a to-be-processed object.
Sputtering device: Carousel type batch type sputtering device Target: φ150, thickness 6mm
Example 12: Aluminum oxide (Al ₂ O ₃ ) 55 vol% / germanium oxide (GeO ₂ ) 45 vol% mixed target Example 13: Aluminum oxide (Al ₂ O ₃ ) 55 vol% / Zinc oxide (ZnO) 45 vol% mixed target Sputtering Method: RF sputtering Exhaust device: Turbo molecular pump Ultimate vacuum: 5 × 10 ⁻⁴ Pa
Substrate temperature: 25 ° C. (room temperature)
Sputtering power: 1.20 kW (Al ₂ O ₃ ), 0.11 kW (GeO ₂ ), 0.27 kW (ZnO)
Film thickness of precursor layer Example 12: 100 ± 10 nm
Example 13: 100 ± 10 nm
Ar flow rate: 120 sccm
Oxygen flow rate: 0 sccm
Substrate used: Glass substrate (1.0 mm thick)

(E-2. Processing step)
The glass substrate on which the precursor layers of Examples 12 and 13 were laminated was immersed in pure water (manufactured by Mac Ace KN type, Kurita Kogyo Co., Ltd., pH 7.0) at room temperature (25 ° C.). The contained germanium oxide or zinc oxide was dissolved.

(Test E1 spectroscopic measurement)
The reflectance, transmittance, and absorptance of the glass substrate having the surface microstructure of Examples 12 and 13 before and after the treatment process were measured. The measurement was performed using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies Corporation) in a wavelength region of 400 nm to 700 nm.
The results of the spectroscopic measurement are shown in Table 5. In Table 5, the values of transmittance, reflectance, and absorptance before and after treatment at a wavelength of 550 nm are shown together with the amount of change. In both Example 12 and Example 13, the change in reflectance was small.

(Test E2 contact angle measurement)
The water contact angle of the glass substrate provided with the surface microstructure of Examples 12 and 13 before and after the treatment process was measured. The measurement was performed at 25 ° C. using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model number FACE CA-X type).
The results of contact angle measurement are shown in Table 6. It was found that the water contact angle was lowered and the hydrophilicity was improved after the treatment step.

<F. Formation of Surface Microstructure According to Example 14>
(F-1. Precursor layer forming step)
The precursor layer according to Example 14 was laminated on a glass substrate as an object to be processed under the following conditions.
The precursor layer of Example 14 is obtained by laminating a layer (layer 4) containing silicon oxide and germanium oxide on a multilayer structure (layers 1 to 3) of titanium oxide and silicon oxide.
Sputtering device: Carousel type batch type sputtering device Target: φ150, thickness 6mm
Layer 1: Titanium oxide (TiO) 100 vol%
Layer 2: Silicon oxide (SiO ₂ ) 100 vol%
Layer 3: Titanium oxide (TiO) 100 vol%
Layer 4: Silicon oxide (SiO ₂ ): Germanium oxide (GeO ₂ ) = 55 vol%: 45 vol%
Sputtering method: DC sputtering (TiO), RF sputtering (SiO ₂ , GeO ₂ )
Exhaust device: Turbo molecular pump Ultimate vacuum: 5 × 10 ⁻⁴ Pa
Substrate temperature: 25 ° C. (room temperature)
Sputtering power: 0.80 kW (TiO ₂ ), 1.20 kW (SiO ₂ ), 0.26 kW (GeO ₂ )
Film thickness of precursor layer: 250 ± 25 nm
Layer 1: 12 ± 1 nm
Layer 2: 35 ± 4 nm
Layer 3: 115 ± 12 nm
Layer 4: 88 ± 9 nm
Ar flow rate: 120 sccm
Oxygen flow rate: 5 sccm
Substrate used: Glass substrate (1.0 mm thick)

(F-2. Processing step)
The glass substrate on which the precursor layer of Example 14 was laminated was immersed in pure water (manufactured by Mac Ace KN type, Kurita Kogyo Co., Ltd., pH 7.0) at room temperature (25 ° C.) and contained in the precursor layer. Germanium oxide was dissolved.

(Test F1 spectroscopic measurement)
The reflectance, transmittance, and absorptance of the glass substrate having the surface microstructure of Example 14 before and after the treatment process were measured. The measurement was performed using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies Corporation) in a wavelength region of 400 nm to 700 nm.
Table 7 shows the results of the spectroscopic measurement. In Table 7, the values of transmittance, reflectance, and absorption before and after treatment at a wavelength of 550 nm are shown together with the amount of change.

(Test F2 contact angle measurement)
The water contact angle of the glass substrate provided with the surface microstructure of Example 14 before and after the treatment step was measured. The measurement was performed at 25 ° C. using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model number FACE CA-X type).
The results of contact angle measurement are shown in Table 8. It was found that the water contact angle was lowered and the hydrophilicity was improved after the treatment step.

<G. Formation of Surface Microstructure According to Examples 15 to 18 and Comparative Example 3>
(G-1. Precursor layer forming step)
On the following conditions, the precursor layers according to Examples 15 to 18 and Comparative Example 3 were laminated on the glass substrate as the object to be processed.
Sputtering device: Carousel type batch type sputtering device Target: φ150, thickness 6mm
Example 15: Zinc oxide (ZnO) 45 vol% / silicon oxide (SiO ₂ ) 55 vol% mixed target Examples 16 and 17: Molybdenum oxide (MoO ₃ ) 45 vol% / silicon oxide (SiO ₂ ) 55 vol% mixed target Example 18 : Germanium oxide (GeO ₂ ) 45 vol% / silicon oxide (SiO ₂ ) 55 vol% mixed target Comparative Example 3: germanium oxide (GeO ₂ ) 45 vol% / tantalum oxide (Ta ₂ O ₅ ) 55 vol%
Sputtering method: RF sputtering _{(SiO 2, ZnO, GeO 2} , Ta 2 O 5), DC sputtering _(MoO 3)
Exhaust device: Turbo molecular pump Ultimate vacuum: 5 × 10 ⁻⁴ Pa
Substrate temperature: 25 ° C. (room temperature)
Sputtering power: 1.2 kW (SiO ₂ ), 0.27 kW (ZnO), 0.21 kW (Example 16, MoO ₃ ), 0.17 kW (Example 17, MoO ₃ ), 0.11 kW (GeO ₂ ), 0.67 kw (Ta ₂ O ₅ )
Film thickness of precursor layer Examples 15 to 18: 100 ± 10 nm
Comparative Example 3: 100 ± 10 nm
Ar flow rate: 120 sccm
Oxygen flow rate: 0 sccm (Examples 15 and 18)
50 sccm (Example 16)
40 sccm (Example 17)
10 sccm (Comparative Example 3)
Substrate used: Glass substrate (1.0 mm thick)

(G-2. Treatment process)
The glass substrate on which the precursor layer of Example 15 was laminated was immersed in a weak acid (dilute hydrochloric acid) at room temperature (25 ° C.).
The glass substrate on which the precursor layers of Examples 16 to 18 and Comparative Example 3 were laminated was immersed in pure water (manufactured by Mac Ace KN type, Kurita Kogyo Co., Ltd., pH 7.0) at room temperature (25 ° C.).

(Test G1 spectroscopic measurement)
The reflectance, transmittance, and absorptivity of the glass substrates having the surface microstructures of Examples 15 to 18 and Comparative Example 3 before and after the treatment process were measured. The measurement was performed using a spectrophotometer (U-4100, manufactured by Hitachi High-Technologies Corporation) in a wavelength region of 400 nm to 700 nm.
Table 9 shows the results of the spectroscopic measurement. In Table 9, the values of transmittance, reflectance, and absorption before and after treatment at a wavelength of 550 nm are shown together with the amount of change.
In Example 15, it was found that zinc oxide (ZnO) can be selectively dissolved by dipping in weak acid (dilute hydrochloric acid).
In Comparative Example 3, there was no change in reflectivity before and after immersion in pure water, and there was a possibility that a composite oxide was generated between tantalum oxide (Ta ₂ O ₅ ) and germanium oxide (GeO ₂ ).

(Test G2 contact angle measurement)
The water contact angles of the glass substrates having the surface microstructures of Examples 16 to 18 and Comparative Example 3 before and after the treatment process were measured. The measurement was performed at 25 ° C. using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., model number FACE CA-X type).
Table 10 shows the results of the contact angle measurement. It was found that the water contact angle was lowered and the hydrophilicity was improved after the treatment step.

(Test G3 electron microscope observation)
The surface and cross-sectional states of the glass substrates having the surface microstructures of Examples 15 to 18 and Comparative Example 3 before and after the treatment process were measured with a field emission scanning electron microscope (FE-SEM, manufactured by Hitachi High-Technologies Corporation, S- 4300). There was no change in the electron microscope image before and after the treatment step.

<H. Measurement of Surface Roughness of Surface Microstructures According to Examples and Comparative Examples>
(Test H1 surface roughness measurement)
The surface roughness of the glass substrate having the surface microstructure of Examples 2, 3, 5, 8 to 11, 15, 16 and Comparative Example 2 before and after the treatment step was measured. The measurement was performed under the following conditions using an atomic force microscope (AFM, manufactured by Bruker AXS KK, Innova).
Measurement mode: Tapping
Input Gain: × 20
Target Tapping Signal: 2V
Scan Range: 3μm × 3μm
Scan Rate: 0.5Hz
Line: 256
ClsedLoop: ON
Measurement temperature: 25 ° C

Table 11 shows the results of the surface roughness measurement.
In Table 11, Ra is the arithmetic average roughness, and Rz is the maximum height (JIS B 0601: 2001).
It was found that the arithmetic average roughness (Ra) and the maximum height (Rz) were lowered after the treatment step.
From this result, it was shown that the surface microstructure having very high surface smoothness and hydrophilicity and low reflectivity can be formed by the method for forming the surface microstructure according to the present invention. More specifically, according to the method for forming a surface microstructure according to the present invention, the arithmetic average roughness (Ra) is 2.0 nm or less (the thickness of the surface microstructure, 50 nm or more and 500 nm or less), 1.5 nm or less ( Since the thickness of the surface microstructure is 50 nm or more and 250 nm or less) and 1.0 nm or less (thickness of the surface microstructure, 50 nm or more and 100 nm or less), the thickness of the surface microstructure is 50 nm or more and 500 nm or less. It was shown that a surface microstructure having an average roughness (Ra) of 10 nm or less can be formed.

1,1A Article 10 with surface microstructure Structure to be processed (article)
10a Surface of workpiece 20 Surface microstructure (surface porous structure)
DESCRIPTION OF SYMBOLS 30 Antireflection film 30a 1st antireflection film 30b 2nd antireflection film 2,2A Article 40 provided with precursor layer 40 precursor layer 40a 1st precursor layer 40b 2nd precursor layer 40c 3rd precursor Body layer

Claims (19)

1. A processing object preparation step of preparing a processing object;
   A precursor layer laminating step of laminating a precursor layer containing a first substance and a second substance on the workpiece;
   A treatment step of immersing the precursor layer obtained in the precursor layer lamination step in a treatment liquid to dissolve the second substance;
   And forming a surface microstructure.
2. The method for forming a surface microstructure according to claim 1, wherein the precursor layer stacking step is performed using a method selected from a sputtering method, an ion plating method, a vacuum deposition method, and a chemical vapor deposition method.
3. In the precursor layer stacking step, the precursor layer is stacked on the object to be processed using a target material or a vapor deposition material containing the first substance and the second substance. The method for forming a surface microstructure according to claim 1 or 2.
4. The method for forming a surface microstructure according to any one of claims 1 to 3, wherein the precursor layer laminating step is performed at 80 ° C or lower.
5. The method for forming a surface microstructure according to any one of claims 1 to 4, wherein the treatment liquid used in the treatment step is water.
6. The method for forming a surface microstructure according to claim 5, wherein the water used in the treatment step has a temperature of 10 ° C to 100 ° C and a pH of 6 to 8.
7. The first substance is insoluble or hardly soluble in the treatment liquid used in the treatment step,
   The method for forming a surface microstructure according to any one of claims 1 to 6, wherein the second substance is easily soluble in a processing solution used in the processing step.
8. The first substance is one or more substances selected from the group including silicon oxide (SiO ₂ ), magnesium fluoride (MgF ₂ ), titanium oxide (TiO ₂ ), and tantalum oxide (Ta ₂ O ₅ ). The method for forming a surface microstructure according to claim 7.
9. The second substance is a kind selected from the group including germanium oxide (GeO _x ), molybdenum oxide (MoO _x ), tungsten oxide (WO ₃ ), zinc oxide (ZnO), and sodium chloride (NaCl). The method for forming a surface microstructure according to claim 7 or 8, wherein the material is the above-mentioned substance.
10. The said to-be-processed object contains 1 or more types of substances selected from the group containing resin, glass, a metal, an alloy, and ceramics (metal oxide, metal nitride, metal oxynitride), The method for forming a surface microstructure according to any one of 1 to 9.
11. The method for forming a surface microstructure according to any one of claims 1 to 10, wherein the object to be processed contains a resin.
12. The method for forming a surface microstructure according to any one of claims 1 to 11, wherein the object to be processed is an article selected from a group including a lens, a half mirror, a touch panel, and a display device.
13. Goods,
    An antireflective coating formed on the article;
    A microstructure formed on the antireflection film;
    An article comprising a surface microstructure characterized by comprising:
14. The microstructure is formed of one or more materials selected from the group including silicon oxide (SiO ₂ ), magnesium fluoride (MgF ₂ ), titanium oxide (TiO ₂ ), and tantalum oxide (Ta ₂ O ₅ ). An article comprising a surface microstructure according to claim 13.
15. The said article contains 1 or more types of substances selected from the group containing resin, glass, a metal, an alloy, and ceramics (metal oxide, metal nitride, metal oxynitride), or characterized by the above-mentioned. 14. An article comprising the surface microstructure of item 14.
16. The article comprising a surface microstructure according to any one of claims 13 to 15, wherein the article contains a resin.
17. The article having a surface microstructure according to any one of claims 13 to 16, wherein the article is an article selected from a group including a lens, a half mirror, a touch panel, and a display device.
18. The article having a surface microstructure according to any one of claims 13 to 17, wherein the reflectance of the surface is 10% or less.
19. The article having a surface microstructure according to any one of claims 13 to 18, wherein the water contact angle of the surface is 10 ° or less.

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