JP2013105846A - Optical component having antifogging film and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical component, easy to adjust refractive index, easy to design optics, and having an antifogging film.SOLUTION: The optical component comprises a transparent base material and an optical thin film, laminated on the transparent base material and at least a part of which is composed of hydrophilic metal oxide. The optical thin film has a porous structure in which a metal oxide fine particles having voids inside its matrix are combined.

Description

  The present invention relates to an optical component having an antifogging film and a semiconductor device using the optical component.

  A semiconductor device package (hereinafter, also referred to as a semiconductor package) having a solid-state imaging device such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) is often a hollow structure. For example, a light receiving unit is installed near the bottom of a package made of resin, ceramics, etc., and a cover that is an optically light-transmissive and flat optical component such as glass or resin is installed on the top. However, the structure is integrated with a frame portion (hereinafter also referred to as a frame) of the semiconductor package with an adhesive or the like to be closed.

  In order for such a semiconductor package to operate stably over a long period of time, it is important that moisture is not present in the semiconductor package as much as possible. However, in the process of manufacturing a semiconductor package, moisture in the air is adsorbed to some extent by each member such as the frame of the semiconductor package and an adhesive that bonds the semiconductor package and the cover. In order to prevent this, there is, for example, a method in which a solid-state imaging device is accommodated in a package and hermetically sealed by filling with nitrogen or dry air, but this is extremely expensive for a solid-state imaging device.

  As described above, the semiconductor package often contains moisture. For this reason, in the manufacturing process of the semiconductor device, in the process that becomes particularly high temperature such as the reflow process and the repair process, the moisture adsorbed in the semiconductor package before it evaporates, and then on the part that first returns to near normal temperature after that. Condensation may occur. When the part that first returns to the vicinity of room temperature is a cover, light is not sufficiently transmitted in quality inspection, and thus there may be a case where the transmittance is poor even if there is no problem.

  On the other hand, for example, there is a method of disposing a moisture hygroscopic agent under the solid-state imaging device (Patent Document 1). In this way, in addition to the method of providing a moisture adsorbent or dehumidifier inside the package in a place where light from the outside is not blocked, a method for adsorbing moisture on the components of the package, and providing a small opening in the package Many methods have been proposed, such as a method for escaping moisture therefrom. In addition, in a semiconductor device having a solid-state imaging element, there is a method for obtaining an antifogging effect by forming a titanium oxide film on a cover (Patent Document 2).

  Furthermore, transparent substrate surfaces such as window glass, glass for show windows, instrument cover glass, watch cover glass, eyeglass lenses, camera lenses, automobile mirrors, bathroom mirrors, etc. are hydrophilic surfaces. Most have. However, this hydrophilicity can be exhibited when the surface of the transparent substrate is not contaminated. Usually, contaminants such as dirt, dust, oil, etc. coming from the installation environment are attached to the surface of the transparent substrate. As a result, the hydrophilicity is impaired and the surface becomes hydrophobic. In this way, on the surface of the transparent base material that has become hydrophobic due to the loss of hydrophilicity of the surface, the water in the air adheres in the form of fine water droplets, causing a clouding phenomenon that irregularly reflects light, resulting in transparency. May decrease. On the other hand, there are a method for obtaining an antifogging effect by forming a titanium oxide film, a method for obtaining an antifogging effect by preventing the generation of water droplets by an uneven film containing fine silicon dioxide powder (Patent Documents) 3).

JP 2007-305811 A JP 2009-182008 A JP-A-11-217560

  However, none of the methods for arranging the hygroscopic agent has been used to solve the complete problem, and the desired anti-fogging effect is obtained by properly using the methods depending on the application or by appropriately combining a plurality of methods. . In addition, the application of titanium oxide is expensive, and ultraviolet light is necessary to obtain a high antifogging effect. Further, a high refractive index film such as titanium oxide is used on the outermost surface of the optical multilayer film for optical parts. Arrangement has problems such as difficulty in optical design. With a film made of fine silicon dioxide powder, it has been difficult to achieve a low refractive index, for example, to achieve a reduction in reflectance in the visible light region, which is one of the required characteristics of the cover.

  In view of such a problem, the present invention provides an optical component having an anti-fogging film as well as easy refractive index adjustment and easy optical design. Further, the present invention provides a method and a manufacturing method for preventing the cover from being fogged at low cost and in a simple and particularly high temperature step during the manufacturing process of the semiconductor device.

  The optical component of the present invention is characterized in that a light-transmitting optical thin film is laminated on a transparent base material, which is substantially made of a metal oxide having hydrophilicity.

  According to the optical component of the present invention, excellent anti-fogging performance and low refractive index performance with almost no light absorption that facilitates optical design can be provided at the same time at low cost.

1 is a schematic diagram illustrating an example of a semiconductor device of the present invention. Sectional drawing which shows an example of the optical component of this invention. Explanatory drawing for demonstrating the measuring method of a contact angle. The figure which shows the measurement process of a contact angle. The figure which shows the measurement process of a contact angle. Sectional drawing which shows the modification of the optical component of this invention. The comparison figure of the reflection characteristic of the visible light range by the optical component of this invention. The comparison figure of the reflection characteristic of the visible light range by the optical component of this invention. Schematic which shows refractive index adjustment by outer shell thickness.

  Hereinafter, embodiments of an optical component and a semiconductor device having an antifogging film according to the present invention will be described.

  FIG. 1 is a schematic view showing an example of a semiconductor device of the present invention.

  FIG. 2 shows a cross-sectional view of the optical component 20 of FIG. 1 as an example of the optical component of the present invention.

  The semiconductor device 10 is, for example, a solid-state imaging device, and includes an optical component 20, a light receiving unit (light receiving chip) 1, a package 2, an external terminal 3, a bonding wire 4, an adhesive 7, and the like.

  In the semiconductor device 10, the light receiving unit 1 is accommodated in the package 2, and the optical component 20 is provided so as to cover the opening of the package 2, and is closely attached to the package 2 by the adhesive 7.

  The light incident on the semiconductor device 10 enters the light receiving unit 1 through the optical component 20. The optical component 20 includes at least a transparent substrate 6 and an optical thin film 5 laminated on the transparent substrate 6. The optical thin film 5 is provided on the inner surface of the optical component 20 that faces at least the light receiving portion 1 of the optical component 20.

  Although not shown in the figure, on the incident light side outside the semiconductor device 10, a lens group, a visibility correction component, a moire eliminating component, and the like may be further arranged to constitute the imaging device as a whole. The lens group includes various lenses, the visibility correction component includes an infrared absorption filter, and the moire elimination component includes a birefringent plate. In such a case, the light that has passed through these components enters the light receiving unit 1 through the optical component 20. Furthermore, the optical component of the present invention is not limited to the optical component of such an imaging apparatus, and can be used as an optical component such as a lens group or a mirror in a projection device such as a projector or an optical pickup, for example.

  The transparent substrate 6 is not particularly limited as long as it has transparency with respect to light in a specific wavelength region in the sensitivity range of the light receiving unit 1 including visible light, and is made of glass, inorganic crystal, organic resin, or the like. Things. Specific examples include a lens, an infrared absorption filter as a visibility correction component, a blank glass having no infrared absorption function as a cover glass, or a birefringent plate as a moire eliminating component.

  The optical thin film 5 needs to have a good transmittance with respect to light in a specific wavelength region such as visible light like the transparent substrate. For this purpose, it is preferable to suppress reflection at the interface with the air layer and the transparent substrate and absorption within the optical thin film as much as possible. Examples of such an optical thin film include an antireflection film that suppresses the reflectance of visible light. Moreover, the optical thin film 5 may be laminated | stacked directly on the transparent base material 6, and may be laminated | stacked indirectly via another functional film. Examples of other functional films include an optical multilayer film and a transparent conductive film. Such an optical thin film easily adjusts the refractive index, and the optical component 20 as a whole can be easily optically designed. The refractive index of such an optical thin film is preferably between the refractive index of the transparent substrate of the optical component 20 and the refractive index of the air layer at least in the specific wavelength region. For example, if the transparent substrate 6 is glass, 1.15 to 1.43 (refractive index at a wavelength of 550 nm, hereinafter the same unless otherwise specified) is preferable, and 1.2 to 1.4 is more preferable. When the refractive index of the optical thin film is lower on the interface side with the air layer than on the interface side with the transparent substrate, it is preferable because reflection can be further suppressed.

  The optical thin film of the present invention is not limited to a semiconductor device, and may be provided on an optical component inside a projection device such as a projector, an optical component such as a lens group or a mirror in an optical pickup, a window glass, an in-vehicle It may be provided on the surface of a transparent substrate other than a closed structure such as glass for use.

  The optical thin film 5 is made of a metal oxide having at least a part of hydrophilicity. According to the metal oxide having hydrophilicity, the contact angle can be reduced by adsorption of moisture in the atmosphere. Thereby, moisture in the air is adsorbed to the optical thin film, and even if the adsorption amount reaches a certain amount, it does not form water droplets but spreads on the surface of the optical thin film, and clouding due to water droplets is suppressed. As the metal oxide having hydrophilicity, for example, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, tantalum oxide, tin oxide and the like are preferable, and these may be used alone. Two or more kinds may be used in combination.

  The optical thin film 5 is preferably disposed at a position where it can come into contact with moisture in the gas, and is usually disposed on the outermost surface of the optical component 20 because it suppresses fogging caused by adsorption of moisture in the atmosphere. It is preferable. In particular, from the viewpoint of directly obtaining the effect of the anti-fogging function, it is preferable that the optical component 20 is disposed on the outermost surface that is on the inner side of the device when the optical component 20 is mounted on an optical device such as the semiconductor device 10.

  More preferably, the optical thin film 5 has a porous structure. According to the porous structure, the area where moisture in the atmosphere can contact is greatly increased due to the presence of surface irregularities and internal voids, and strong hydrophilicity is exhibited. Therefore, the antifogging performance of the entire film can be improved. That is, on the surface having strong hydrophilicity, the adsorbed moisture does not become a minute polka dot but gets wet uniformly, thereby smoothing the interface between the air and the adhering moisture and suppressing fogging. Further, according to the porous structure, since the air layer is stored in the voids inside, the effective refractive index can be lowered as compared with a dense structure without voids. The refractive index can be adjusted by the ratio between the gap portion and the metal oxide portion, and optical design that satisfies the required characteristics as an optical component is facilitated.

  The porous structure may be one in which many minute voids are dispersed, or one in which voids are partially connected. Examples of the porous structure include a structure in which metal oxide fine particles are bound by a matrix (hereinafter also referred to as a binder). Such a porous structure can be formed by a wet method, and can be formed at a lower cost than a dry method, for example, a physical vapor deposition method such as a vacuum vapor deposition method or a chemical vapor deposition method such as thermal CVD.

  The ratio of the metal oxide fine particles in the optical thin film 5 is not particularly limited, but is preferably 50 to 95% by mass with respect to the entire optical thin film 5, that is, the total amount of the matrix and the metal oxide fine particles. If it is less than 50%, the refractive index of the optical thin film 5 increases, and optical design that satisfies the required characteristics as an optical component becomes difficult. If it exceeds 95%, the wear resistance strength of the optical thin film 5 deteriorates. 60-95 mass% is more preferable, and 70-90 mass% is further more preferable. By setting it as such a range, the space | gap for adsorb | sucking the water | moisture content in air | atmosphere can be effectively formed in a porous structure, and adhesiveness with the transparent base material 6, other functional films not shown, etc. is also favorable. Can be.

  The matrix is preferably a metal oxide, and the metal oxide of the matrix and the metal oxide of the metal oxide fine particles may be the same or different. The metal oxide constituting the matrix is not particularly limited as long as it is a hydrophilic metal oxide, but preferred examples include silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, tantalum oxide, and tin oxide. . The matrix is preferably composed only of a metal oxide, but may contain, for example, a component such as an organic resin of 30% by mass or less, preferably 10% by mass or less, and more preferably 2% by mass or less.

  The average primary particle size (hereinafter also referred to as the average particle size) of the metal oxide fine particles is preferably 0.1 to 1000 nm, more preferably 2 to 500 nm, and still more preferably 10 to 100 nm. According to such an average particle diameter, voids for adsorbing moisture in the atmosphere can be effectively formed in the porous structure, and the transparency of the optical thin film 5 can be improved.

  The shape of the metal oxide fine particles is not particularly limited, and examples thereof include a spherical shape, a cylindrical shape, and a rectangular parallelepiped shape. The metal oxide is not particularly limited as long as it has hydrophilicity, and examples thereof include silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, tantalum oxide, and tin oxide. The metal oxide fine particles are not necessarily limited to those having a single shape or metal oxide, and those having two or more shapes or metal oxides can be used in combination.

  The metal oxide fine particles preferably have a structure having voids inside. A structure in which the size of the voids exceeds 1/3 of the average particle diameter is preferable. Such a structure is also called inorganic hollow fine particles. The metal oxide fine particles preferably have a structure having voids inside the outer shell. The outer shell does not necessarily need to be formed so as to cover the entire gap, and a part of the gap may be exposed from the outer shell. Examples of the inorganic hollow fine particles include silica, carbon, silicon carbide, titania, iron oxide and the like, and composites thereof. For example, inorganic hollow fine particles made of silica (hereinafter also referred to as hollow silica particles) have an outer shell mainly composed of silicon oxide, and have voids inside the outer shell. The hollow shape is preferable because the effective refractive index can be adjusted by adjusting the thickness of the outer shell, unlike the case where the inside is completely filled. Those having hollow silica particles are preferable because they themselves are porous. For example, the refractive index of the optical thin film 5 can be 1.2 to 1.4.

  When either the average particle diameter of the metal oxide fine particles or the size of the internal voids of the metal oxide fine particles (hereinafter also referred to as the inner diameter) is fixed and the outer shell is thickened, the refractive index increases and the outer shell is thinned. Then, the refractive index decreases. As an example, FIG. 9 shows an estimation of refractive index fluctuation (refractive index fluctuation ratio) when the average particle diameter of hollow silica particles is fixed at 40 nm and the thickness of the outer shell is changed. The vertical axis represents a relative value with respect to the refractive index of the silica fine particles having no voids in the outer shell, and the inside and the surroundings of the voids inside the metal oxide fine particles are estimated as an air layer.

  The average particle diameter of the hollow silica particles is preferably 0.1 to 1000 nm, more preferably 2 to 500 nm, and still more preferably 10 to 100 nm. According to such an average particle diameter, the optical thin film 5, that is, a void for adsorbing moisture in the atmosphere can be effectively formed in the porous structure, and the transparency of the optical thin film 5 can be improved.

  The thickness of the outer shell of the hollow silica particles is not particularly limited, and varies depending on the average particle diameter, but is preferably 0.01 to 100 nm, more preferably 0.5 to 50 nm, and further preferably 1 to 20 nm. The thickness of the outer shell is preferably about 1/50 to 1/3 of the average particle diameter, and more preferably about 1/5 to 1/3. If it does in this way, the refractive index of the optical thin film 5 can be adjusted to said range.

  Further, the hollow silica particles may be aggregated in the hydrophilic metal oxide film 22. For example, about 2 to 10 pieces may be aggregated. In this case, the strength and wear resistance of the hydrophilic metal oxide film 22 tend to increase. Further, the particle size (hereinafter also referred to as average aggregate particle size) as an aggregate is preferably 10 to 1000 nm, more preferably 30 to 700 nm, still more preferably 60 to 400 nm, and 70 to Particularly preferred is 200 nm. Moreover, it is preferable that an average aggregated particle diameter is 1.5 times or more of the average particle diameter (average primary particle diameter) in the state which is not aggregated.

  The average primary particle diameter is a value observed with a transmission electron microscope (manufactured by Hitachi, Ltd., trade name: H-9000), and the average aggregate particle diameter is a dynamic light scattering method (trade name, manufactured by Nikkiso Co., Ltd.). : Value measured by Microtrack UPA).

  The optical thin film 5 is not necessarily limited to a single layer structure, and may be a multilayer structure of two or more layers. The multilayer structure may be the same metal oxide fine particles in which two types of layers having different ratios in the matrix are alternately laminated, or a layer in which different types of metal oxide fine particles are dispersed. A layer in which metal oxide fine particles having different average particle diameters or different outer shell thicknesses are dispersed may be appropriately laminated, and is not particularly limited. When there is a refractive index distribution in the thickness direction of the optical thin film itself, it is preferable that the optical thin film closer to the interface with the air layer has a refractive index closer to air.

  Although the thickness of the optical thin film 5 varies depending on functions and applications that can be included in addition to the antifogging function, for example, the total thickness of the single layer structure or the multilayer structure is preferably 50 to 2000 nm. By setting the thickness to 50 nm or more, a sufficient film thickness can be obtained and generation of reflected light can be suppressed. The film thickness of 2000 nm or less is preferable because the film formability can be improved and the change in optical characteristics can be suppressed over a long period of time. For example, when the spectral characteristics are measured again under the same conditions as the initial stage after being left for 1,000 hours in a high-temperature and high-humidity environment with a temperature of 85 ° C. and a humidity of 85%, the optical characteristics hardly change. The thickness of the optical thin film 5 is more preferably 1000 nm or less, and further preferably 500 nm or less.

  The optical thin film 5 preferably has a contact angle of 15 degrees or less when a droplet made of 2 microliters of pure water is dropped. Here, it is assumed that the optical thin film 5 (optical component 20) to be measured is left for 3 weeks in an environment of normal temperature and normal humidity (20 ° C., relative humidity 35%). The contact angle is measured immediately after dropping. According to such an optical thin film 5, hydrophilicity can be maintained over a long period of time due to the presence of a surface having strong hydrophilicity. That is, according to such an optical thin film 5, not only the initial state but also, for example, good hydrophilicity can be maintained for 3 weeks or more, and the antifogging performance can be effectively maintained.

  Here, in general, when the liquid layer is in contact with the surface of the solid layer, the contact angle is the angle between the tangent to the liquid layer surface and the solid-liquid contact surface at the three-layer contact point of the solid-liquid gas. It means that the larger the size, the lower the hydrophilicity because the liquid layer becomes substantially spherical.

  The contact angle can be measured as follows. That is, as shown in FIG. 3, the contact angle θ of the droplet 32 made of pure water with respect to the member to be measured 31 is tangent to the surface curve of the droplet 32 at the point 33 where the member to be measured 31 and the droplet 32 contact each other. And the angle formed by the surface 31s of the member 31 to be measured.

  As the measuring device, for example, a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., trade name: FACE CA-X type) is used. First, as shown in FIG. 4, pure water droplets 32 are formed using a microsyringe 34. The amount of droplet 32 is 2 microliters.

  Next, as shown in FIG. 5, the bottom of the droplet 32 is brought into contact with the surface 31 s of the member 31 to be measured which is a measurement target. When the microsyringe 34 is separated from the member 31 to be measured, a droplet 32 as shown in FIG. 6 adheres to the surface 31 s of the member 31 to be measured. In this state, the height h of the droplet 32 and the radius r of the droplet 32 (or the distance between both ends of the droplet 32 shown in FIG. 3 or the diameter 2r of the droplet 32) are measured.

  Since the contact angle θ is equal to twice θ1 (= arctan (r / h)) shown in FIG. 3, the following equation (1) is used from the measured height h and radius r of the droplet 32. Thus, the value of the contact angle θ is calculated. The larger the value of the contact angle θ, the lower the hydrophilicity of the measurement object, and the smaller the contact angle θ, the higher the hydrophilicity of the measurement object.

θ = 2 arctan (r / h) (1)
Next, a method for forming the optical thin film 5 will be described.

  As an example, a method for forming the optical thin film 5 having hollow silica particles as metal oxide fine particles will be described.

  The core-shell type fine particles are produced, for example, by dispersing core fine particles serving as a core in a dispersion medium, and then reacting a precursor of the outer shell. The core fine particles include those that are dissolved, decomposed, or sublimated by heat, acid, or light, depending on the production method of the hollow silica particles. For example, thermally decomposable organic polymer fine particles such as surfactant micelles, water-soluble organic polymers, styrene resins and acrylic resins; acid-soluble inorganic fine particles such as sodium aluminate, calcium carbonate, basic zinc carbonate and zinc oxide; One or a mixture of two or more selected from metal chalcogenide semiconductors such as zinc sulfide and cadmium sulfide, and light-soluble inorganic fine particles such as zinc oxide can be used. Among these, workability and productivity when removing the core are good, and rapid agglomeration of the hollow silica particles can be suppressed during the core removal, and a highly transparent hydrophilic metal oxide film 22 is obtained. Therefore, zinc oxide is preferable.

  The core fine particles may be synthesized by either a dry method such as a gas phase method or a wet method such as a liquid phase method, and may be a monodisperse or an aggregate. The size and shape of the core fine particles are not particularly limited, and are appropriately selected in consideration of the dissolution rate of the core fine particles, the size of the voids in the hollow silica particles, and the like.

  The dispersion medium is not particularly limited, and examples thereof include water, alcohols, ketones, esters, ethers, glycol ethers, nitrogen-containing compounds, and sulfur-containing compounds. The dispersion medium does not necessarily contain water, but considering that it can be used as it is when hydrolysis and polycondensation of the precursor of the outer shell, the dispersion medium is water alone or a mixed solvent of water and an organic solvent. preferable.

  The dispersion of the core fine particles in the dispersion medium is preferably performed by adding a dispersant and peptizing with a dispersing machine such as a ball mill, a bead mill, a sand mill, a homomixer, or a paint shaker. A hydrolysis catalyst such as acid or alkali is added to the core fine particle dispersion, and the precursor of the outer shell is reacted at a pH of 8 or higher, for example. Thereby, an outer shell is formed on the surface of the core fine particles, and core-shell type fine particles are obtained. Examples of the outer shell precursor include one or a mixture of two or more selected from silicic acid, silicate, and alkoxide silicate, and may be a hydrolyzate or polymer thereof.

  The thickness of the outer shell can be controlled by adjusting the formation time of the outer shell. If the formation time is increased, the outer shell becomes thicker and the refractive index increases. On the other hand, when the formation time is shortened, the outer shell becomes thinner and the refractive index decreases.

  As another method of adjusting the refractive index, there is a method of adjusting the size of the internal voids of the metal oxide fine particles having a predetermined primary particle diameter, that is, the inner diameter. The inner diameter of the metal oxide fine particles can be controlled by adjusting the particle diameter of the core fine particles. When the outer shell is formed using core fine particles having a large particle diameter, the inner diameter of the outer shell is increased, the thickness of the outer shell of the metal oxide fine particles having a predetermined size is relatively reduced, and the refractive index is lowered.

  Even when the thickness of the outer shell is predetermined, in order to shorten the time for forming the outer shell, the pH at the time of mixing the core fine particle dispersion is preferably 9 to 11, and the temperature is preferably 20 to 100 ° C. In order to increase the ionic strength and facilitate the formation of the outer shell, the core fine particle dispersion may be added with an electrolyte such as magnesium hydroxide, and the pH may be adjusted with these electrolytes.

Thereafter, for example, the core fine particles in the core-shell type fine particles are dissolved to form hollow silica particles. The core fine particles dissolve as ions, for example, at pH 8 or lower. When the core fine particles are ZnO fine particles, they are dissolved as Zn ²⁺ ions. The core fine particles can be dissolved by adding an acid or using an acidic cation exchange resin. According to the acidic cation exchange resin, since the dissolution of the core fine particles proceeds slowly, it is possible to suppress a rapid increase in ion concentration and to suppress rapid aggregation of the hollow silica particles. If the agglomeration is abrupt, the aggregated particle diameter becomes too large, and the transparency of the optical thin film 5 may be reduced.

The acidic cation exchange resin preferably dissolves at least the core fine particles, and the dispersion has a pH of 8 or less, preferably 6 or less. Here, the acidity of the acidic cation exchange resin is determined by the functional group, and includes —SO ₃ H group for strong acidity and —COOH group for weak acidity. The addition amount of the acidic cation exchange resin is preferably in a range where the total exchange capacity is larger than at least the amount of ions such as Zn ²⁺ generated. The resin amount is preferably in the range of 1.1 to 5 times the required amount. There is a tendency that the dissolution rate of the core fine particles increases as the amount of the acidic cation exchange resin added increases.

  The dissolution temperature is not particularly limited, and the dissolution reaction basically proceeds even at room temperature. The higher the temperature, the higher the dissolution rate and the diffusion rate of dissolved ions and the like, and the higher the temperature, for example, preferably 10 to 100 ° C, more preferably 20 to 80 ° C. After dissolution of the core fine particles, the dispersion of the hollow silica particles can be obtained by separating the cation exchange resin by solid-liquid separation operation such as filtration.

  The method for producing inorganic hollow fine particles is not limited to the above. For example, a known method can be used as necessary, such as a method of generating voids by vaporizing the core by high-temperature firing.

  Next, the hollow silica particles and the matrix precursor are mixed to prepare a coating liquid to be the optical thin film 5. The amount of solid content of the matrix precursor is preferably 0.05 to 15 times the mass of the hollow silica particles. By setting it as such a ratio, while having a favorable porous structure, the optical thin film 5 which has high hardness and was excellent in abrasion resistance can be formed.

  Examples of the matrix precursor include metal alkoxides of metals contained in the matrix and / or hydrolyzed polycondensates thereof. As the metal alkoxide, silicate silicate is preferable, and is selected from, for example, silicate alkoxide having a fluorine-containing functional group such as perfluoropolyether group and / or perfluoroalkyl group, vinyl group and epoxy group in addition to ethyl silicate. Silicate alkoxides containing one or more functional groups may be used.

  Examples of the silicate alkoxide containing a perfluoropolyether group include perfluoropolyether triethoxysilane; and examples of the silicate alkoxide containing a perfluoroalkyl group include perfluoroethyltriethoxysilane; silicic acid containing a vinyl group. As alkoxide, vinyltrimethoxysilane, vinyltriethoxysilane; As silicate alkoxide containing epoxy group, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Examples include 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropyltriethoxysilane.

  When an organic resin is used for part of the matrix, an ultraviolet curable organic resin is preferable, and examples thereof include acrylic resins, urethane acrylate resins, epoxy acrylate resins, polyester acrylates, polyether acrylates, epoxy resins, and silicone resins. .

The coating liquid can contain a surfactant for improving the wettability to the coating surface in addition to the hollow silica particles and the matrix precursor. As the surfactant, any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. As the surfactant, —CH ₂ CH ₂ O—, —SO ₂ —, —NR— (R is a hydrogen atom or an organic group), —NH ₂ —, —SO ₃ Y, —COOY (Y is a hydrogen atom, Nonionic surfactants having a structural unit of sodium atom, potassium atom or ammonium ion are preferred.

  Nonionic surfactants include, for example, alkyl polyoxyethylene ether, alkyl polyoxyethylene-polypropylene ether, fatty acid polyoxyethylene ester, fatty acid polyoxyethylene sorbitan ester, fatty acid polyoxyethylene sorbitol ester, alkyl polyoxyethylene amine , Alkyl polyoxyethylene amide, polyether-modified silicone surfactants, and the like.

  The coating liquid can contain various additives as required in addition to the surfactant. For example, one selected from coloring, conductivity, polarization, ultraviolet shielding, infrared shielding, antifouling, antifogging, photocatalyst, antibacterial, phosphorescent, battery, refractive index control, water repellency, oil repellency, fingerprint removal, slipperiness, etc. What gives 2 or more types of functions may be included.

  Application of the coating liquid is, for example, roller coating, hand coating, brush coating, dipping, spin coating, dip coating, coating by various printing methods, curtain flow, bar coating, die coating, gravure coating, micro gravure coating, reverse coating, Roll coating, flow coating, spray coating, ink jet, dip coating or the like can be used.

  After coating, the optical thin film 5 can be formed by drying the coating film. Drying is not limited as long as the solvent can be removed and the precursor can be converted into a matrix. For example, it may be maintained at room temperature to about 200 ° C., but in order to have higher hardness, it is 1 to 60 at 500 to 700 ° C. A heat treatment of about a minute is preferred. By doing in this way, it can be set as an optical thin film with higher abrasion resistance.

  Moreover, you may perform irradiation by an ultraviolet-ray, an electron beam, etc. as needed, for example, in order to raise mechanical strength. Furthermore, in order to improve adhesion, discharge treatment such as plasma treatment, corona treatment, UV treatment, ozone treatment, chemical treatment such as water, acid or alkali, or physical treatment using an abrasive can be performed.

  Next, a modification of the optical component 20 will be described with reference to FIG.

  The optical component 20 includes a first transparent substrate 6a and a second transparent substrate 6b, and the first transparent substrate 6a and the second transparent substrate 6b are bonded by the transparent adhesive layer 8. In addition, the optical multilayer film 9b and the optical thin film 5 as functional films are laminated in this order on the second transparent substrate 6b. Further, an optical multilayer film 9a as a functional film is laminated on the first transparent substrate 6a.

  The first transparent substrate 6a can be, for example, an infrared absorption filter, and the second transparent substrate 6b can be, for example, a glass substrate or an organic resin substrate that does not have an infrared absorption function. Moreover, the optical component 20 may have an optical multilayer film 9 in addition to the transparent substrate 6 and the optical thin film 5 as necessary. The optical component 20 having the optical multilayer film 9 is suitably used as a cover glass having, for example, a visibility correction function and an antifogging characteristic function.

  The infrared absorption filter is not particularly limited as long as it transmits visible light and can absorb infrared light, and examples thereof include a glass mold and an organic resin mold. Examples of the glass mold include fluorophosphate glass containing CuO or phosphate glass containing CuO.

  The glass substrate having no infrared absorption function is not particularly limited as long as it has transparency to light in a specific wavelength region such as visible light, for example, quartz glass, soda glass, borosilicate glass, etc. Is mentioned. Moreover, as an organic resin type | mold, what disperse | distributed the pigment | dye or pigment which absorbs infrared light in organic resin is mentioned, for example. Organic resin types include polyacrylate, polymethacrylate, polyester, polyvinyl ether, polyethylene terephthalate, polycarbonate, polystyrene, polyvinyl chloride, polysulfone, cellulose, polyimide, polyamide, polyurethane, epoxy resin, norbornene resin, fluorine resin, or Examples of these copolymers include dyes that absorb infrared light, such as diimonium dyes, phthalocyanine dyes, dithiol complex dyes, squarylium dyes, tungsten oxide dyes, and the like.

  The optical multilayer film is provided to cut a specific wavelength region because, for example, only the infrared absorption filter cannot make the spectral sensitivity of the light receiving unit 1 coincide with the visual sensitivity. The optical multilayer film has, for example, the following wavelength region cut effect. That is, in order to improve the blue blur of the lens group through which the light incident on the imaging device passes, the vicinity of 400 nm is cut. The infrared absorption filter sharply cuts the gentle absorption and dimming in the vicinity of 700 nm red. Cut off the gradually increasing transmittance of the infrared absorption filter in the infrared region exceeding 1000 nm. Examples of such an optical multilayer film include a dichroic multilayer film having an infrared light and ultraviolet light cutting effect.

  For example, the optical multilayer film is formed by laminating about 40 layers in total such that a high refractive index metal oxide and a low refractive index metal oxide are alternately about 100 nm in thickness from the transparent substrate 6 side. . The high refractive index metal oxide has a refractive index of 1.9 or more, preferably 1.9 to 2.5. For example, niobium oxide, tantalum oxide, titanium oxide, zirconium oxide, hafnium oxide and the like are preferable. On the other hand, the low refractive index metal oxide has a refractive index of 1.5 or less, preferably 1.2 to 1.5. For example, silicon oxide, magnesium fluoride and the like are preferable. The outermost surface layer of the optical multilayer film may be either a low refractive index metal oxide or a high refractive index metal oxide, but silicon oxide is particularly preferable. This is because the adhesion of the hydrophilic metal oxide film 22 can be improved by using silicon oxide as the outermost surface layer of the optical multilayer film.

  The optical multilayer film can be formed by applying a known film forming method, for example, a magnetron sputtering method, an electron beam evaporation method, a vacuum evaporation method, a chemical vapor deposition method, or the like.

(Example 1)
On the glass substrate as the transparent substrate 6, a hollow silica film in which hollow silica particles are bonded by a matrix as the optical thin film 5 was formed to produce an optical component A. The hollow silica membrane was formed as shown below.

  First, a hollow silica sol was obtained by the following procedure.

In a glass reaction vessel with a capacity of 200 ml, ethanol 60 g, ZnO fine particle water dispersion sol (product of Sakai Chemical Industry Co., Ltd., product name: NANOFINE-50, average primary particle size 20 nm, average aggregated particle size 100 nm, solid content equivalent concentration 10 mass) %) 30 g and tetraethoxysilane (SiO ₂ solid content concentration 29 mass%) 10 g were added, then an aqueous ammonia solution was added to adjust pH = 10, and the mixture was stirred at 20 ° C. for 6 hours to obtain a core-shell type fine particle dispersion. 100 g (solid content concentration 6 mass%) was obtained.

100 g of strongly acidic cation exchange resin (manufactured by Mitsubishi Chemical Co., Ltd., trade name: Diaion, total exchange capacity of 2.0 meq / ml or more) was added to the obtained core-shell type fine particle dispersion, and the mixture was stirred for 1 hour to pH = 4. Then, the strongly acidic cation exchange resin was removed by filtration to obtain 100 g of a hollow SiO ₂ fine particle dispersion (hereinafter, also referred to as hollow silica sol) having voids therein. The average primary particle diameter of the hollow SiO ₂ fine particles (hereinafter also referred to as hollow silica particles) is 40 nm (manufactured by Hitachi High-Tech, trade name: Hitachi Scanning Electron Microscope S-3700N), and the pore diameter is the average primary particle diameter of ZnO fine particles. Therefore, the thickness of the outer shell was calculated to be 10 nm. The SiO ₂ fine particles were aggregate particles, and the average aggregate particle size was 100 nm.

Hollow silica sol obtained by the above procedure (0.7 g, solid content concentration: 15% by mass), nitrate partial hydrolyzate of tetraethoxysilane which is a matrix precursor (2 g, solid content concentration: 2.25% by mass) , Isopropanol (7.3 g) was mixed at room temperature to prepare a coating solution. The ratio between the hollow silica particles and the matrix contained in the coating liquid is 7: 3 (mass ratio) in terms of SiO ₂ .

  Then, the coating liquid was apply | coated by the spin coat method on the above-mentioned glass substrate. Thereafter, a heat treatment was performed at 200 ° C. for 45 minutes to perform a dehydration reaction of the precursor, and a hollow silica film was formed as an optical thin film. The film thickness of the optical thin film was measured with a scanning electron microscope and was 102 nm (manufactured by Hitachi High-Tech, trade name: S-3700N). The reflectance of the optical thin film thus obtained was measured with a spectrophotometer (trade name: U4100, manufactured by Hitachi High-Tech), and the refractive index of the optical thin film was 1.22 by calculation.

(Example 2)
An optical component B in which a titanium oxide film having a thickness of 105 nm was formed as the optical thin film 5 on a glass substrate as the transparent base 6 was manufactured. In forming the titanium oxide film, a DC magnetron sputtering apparatus using titanium (Ti) as a target and a mixed gas of argon (Ar) and oxygen (O ₂ ) as a sputtering gas was used.

(Example 3)
On the glass substrate as the transparent substrate 6, a silica particle film in which so-called general silica particles are bonded as the optical thin film 5 without a void exceeding 1/3 of the average particle diameter is formed by a matrix. An optical component C was manufactured. The silica particle film was formed as follows.

First, silica particles having no voids exceeding 1/3 of the average particle size (product of Sakai Chemical Industry Co., Ltd., product name: spherical silica, average primary particle size 50 nm), and nitric acid of tetraethoxysilane which is a matrix precursor A partial hydrolyzate (2 g, solid content concentration: 2.25% by mass) and isopropanol (7.3 g) were mixed at room temperature to prepare a coating solution. The ratio of the silica particles and the matrix contained in the coating liquid in terms of SiO ₂ 9: is adjustable between 3, wherein in terms of SiO ₂ with 8: 1 to 7 was set to 2 (mass ratio). This coating solution was applied onto the above glass substrate by a spin coating method. Thereafter, a heat treatment was performed at 200 ° C. for 45 minutes to perform a dehydration reaction of the precursor, and a silica film was formed as an optical thin film. The film thickness was 111 nm.

(Contact angle)
About the contact angle of the optical thin film 5 surface of each of the optical components A, B, and C manufactured according to Examples 1 to 3 above, the environment immediately after manufacturing (20 ° C.) and normal temperature and normal humidity (20 ° C., relative humidity 35%), respectively. It was measured after standing for 3 weeks at the bottom. The measurement was performed using a contact angle meter (manufactured by Kyowa Interface Chemical Co., Ltd., trade name: FACE CA-X type) by dropping a water droplet of 2 microliters of pure water on the target surface. The contact angles of the optical thin film surfaces of the optical component A, the optical component B, and the optical component C immediately after manufacture were all below the measurement limit (7 degrees or less). However, the contact angle between the optical thin film surfaces of the optical component A and the optical component C left for 3 weeks was less than the measurement limit, whereas the contact angle of the optical thin film surface of the optical component B was 17 degrees. That is, when there was an optical thin film surface made of hollow silica or silica particles, the hydrophilicity was very good over a long period of time compared with the case of having a titanium oxide film.

(Anti-fogging test)
Pure water is put in a beaker on the surface of each optical thin film 5 of each of the optical parts A, B, and C manufactured according to Examples 1 to 3, heated to 80 ° C. to generate water vapor, and subjected to a water vapor exposure test for 30 seconds. went. The test was performed immediately after production (20 ° C.) and after standing for 3 weeks in an environment of normal temperature and normal humidity (20 ° C., relative humidity 35%). Thereafter, the presence or absence of fogging was confirmed by visual inspection. As a result, all of the optical parts A, B, and C immediately after production were uniformly wetted on the surface, and no fogging occurred. However, in the optical parts A and C left for 3 weeks in the above environment, water was uniformly wet on the surface and no fogging occurred, whereas in the optical part B, fogging occurred. That is, when there was an optical thin film surface made of hollow silica or silica particles, the antifogging performance was very good over a long period of time compared to the case of having a titanium oxide film.

(Reflectance measurement)
About the optical components A, B, and C manufactured according to Examples 1 to 3 above, a spectrophotometer (trade name: U4100, manufactured by Hitachi High-Tech) was used in an environment of normal temperature and normal humidity (20 ° C., relative humidity 35%). The transmittance at 400 to 1200 nm was measured using this (FIG. 7). FIG. 8 is an enlarged view of a portion having a reflectance of 1% or less in FIG. As shown in FIGS. 7 and 8, while the reflectance of the optical component B is as high as at least 3%, the reflectance of the optical component A is approximately 1% or less at a wavelength of 400 to 800 nm. It was. In particular, it was confirmed that the reflectance is 0.1% or less in the vicinity of 500 to 600 nm where the visibility is high, and that an extremely good antireflection characteristic can be obtained in the visible light region. The reflectance of the optical component C is approximately 1% or less at a wavelength of 400 to 800 nm, but the reflectance is 0.1% or more in the wavelength region of 400 to 800 nm, which is sufficiently low as compared with the optical component A. The rate could not be realized.

  Thus, the optical thin film surface made of hollow silica has both good anti-fogging performance and good optical characteristics. Even if the reflectance measurement is performed again after leaving for three weeks, no significant change is observed in the reflectance in each of the optical components A, B, and C.

DESCRIPTION OF SYMBOLS 1 Solid-state image sensor 2 Semiconductor package 3 External terminal 4 Bonding wire 5 Optical thin film 6, 6a, 6b Transparent base material 7 Adhesive 8 Transparent adhesives 9, 9a, 9b Optical multilayer film 10 Semiconductor device 20 Optical component 31 Measured member 32 Droplet 34 Micro syringe

Claims (11)

A transparent substrate;
An optical component having a light-transmitting optical thin film laminated on the transparent base material and comprising at least a part of a hydrophilic metal oxide,
An optical component characterized in that the optical thin film has a porous structure in which metal oxide fine particles having voids inside are bonded by a matrix.   The optical component according to claim 1, wherein the metal oxide fine particles are hollow silica particles.   The optical component according to claim 1, wherein the metal oxide fine particles have an average primary particle diameter of 0.1 to 1000 nm observed with a transmission electron microscope.   4. The optical according to claim 1, wherein the metal oxide fine particles have voids inside an outer shell, and the thickness of the outer shell is 1/50 to 1/3 of the average primary particle diameter. parts.   The optical component according to claim 1, wherein the matrix is mainly made of a hydrophilic metal oxide.   The optical component as described in any one of Claims 1-5 whose ratio of the said metal oxide microparticles | fine-particles is 5-95 mass% with respect to the said whole optical thin film.   The optical component according to claim 1, wherein the optical thin film is formed on an outermost surface of the optical component.   The optical component according to claim 1, wherein the transparent substrate is made of at least one selected from glass, inorganic crystals, and organic resins. A transparent substrate;
An optical multilayer film laminated on the transparent substrate, wherein a high refractive index metal oxide film and a low refractive index metal oxide film are alternately laminated;
An optical thin film having a porous structure laminated on the optical multilayer film, light-transmissive, and bonded with metal oxide fine particles having voids inside by a matrix;
An optical component.   The optical component according to claim 9, wherein an outermost surface of the optical multilayer film is made of silicon oxide, and the optical thin film is laminated thereon. The optical component according to any one of claims 1 to 10 and a light receiving unit,
The optical thin film is provided on the inner surface facing the light receiving portion of the optical component,
Semiconductor device.

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