Inorganic plate having film, method for producing same, and package

Abstract

The present invention provides an inorganic plate that has a film, that has excellent ultraviolet transparency, and that, when used for a package on which an optical element is mounted, makes it possible to improve airtightness of the inside of the package.　Provided is an inorganic plate 1 that has a film, that has ultraviolet transparency, and that comprises an inorganic plate 2 and an antireflective film 3 which is provided on a main surface 2a on one side of the inorganic plate 2, wherein: the antireflective film 3 is configured by alternately laminating a silicon oxide layer 4 and an aluminum oxide layer 5; a silicon oxide layer 4 is provided as the outermost layer 3a of the antireflective film 3; and the thickness ratio (silicon oxide layer 4 / aluminum oxide layer 5) of the silicon oxide layer 4 with respect to the aluminum oxide layer 5 is greater than or equal to 5.

Description

Film-coated inorganic board, its manufacturing method, and package

[0001] The present invention relates to a film-coated inorganic board having ultraviolet light transmittance, a method for producing the film-coated inorganic board, and a package using the film-coated inorganic board.

[0002] It has been known that ultraviolet light, such as deep ultraviolet light, has a bactericidal effect and an organic matter decomposition effect, and light-emitting elements, such as LEDs, that emit ultraviolet light are widely used in medical settings and food factories. In addition, UV cameras have been attracting attention in recent years, and there is also an increasing demand for imaging elements, such as image sensors, that are compatible with ultraviolet wavelength ranges, including the deep ultraviolet range.

[0003] Optical elements such as light-emitting elements and imaging elements are mounted in a package and sealed before use (see, for example, Patent Document 1). The package is composed of a case body in which the optical element is mounted and a cover member that seals the inside of the housing. The cover member is a film-coated inorganic plate in which an anti-reflection film is provided on the surface of an inorganic plate. By providing such a film-coated inorganic plate on the front surface of the optical element, the optical element is protected.

[0004] Japanese Patent Application Laid-Open No. 2022-000188

[0005] However, the film material described in Patent Document 1 contains a material that absorbs in the deep ultraviolet region, and a film-coated inorganic plate using such a material for an anti-reflection film has the problem that it cannot sufficiently increase ultraviolet transmittance in the ultraviolet region, particularly in the deep ultraviolet region. On the other hand, a film material that does not absorb in the deep ultraviolet region may not have sufficient wettability with the bonding material used to bond the film-coated inorganic plate to the case body in the package manufacturing process as described above, and therefore, when sealing the inside of the package, the airtightness may not be sufficiently increased.

[0006] The object of the present invention is to provide a film-coated inorganic plate that has excellent ultraviolet transmittance and that, when used in a package that mounts an element such as an imaging element or a light-emitting element (hereinafter referred to as an optical element), can increase the airtightness within the package, a method for manufacturing the film-coated inorganic plate, and a package using the film-coated inorganic plate.

[0007] The following describes various aspects of a film-coated inorganic board that can solve the above problems, a method for producing the film-coated inorganic board, and a package that uses the film-coated inorganic board.

[0008] A film-coated inorganic plate according to a first aspect of the present invention comprises an inorganic plate having ultraviolet transparency and an anti-reflection film provided on one main surface of the inorganic plate, the anti-reflection film being constructed by alternately laminating silicon oxide layers and aluminum oxide layers, the silicon oxide layer being provided as the outermost layer of the anti-reflection film, and the thickness ratio of the silicon oxide layer to the aluminum oxide layer (silicon oxide layer / aluminum oxide layer) being 5 or more.

[0009] In the film-coated inorganic plate according to Aspect 1, the silicon oxide layer is a film with a relatively low refractive index, and the aluminum oxide layer is a film with a relatively high refractive index, so that by alternately stacking these layers, anti-reflection function can be imparted. Furthermore, in the film-coated inorganic plate according to Aspect 1, the thickness ratio of the silicon oxide layer to the aluminum oxide layer (silicon oxide layer / aluminum oxide layer) is 5 or more, and the small thickness of the aluminum oxide layer allows for increased ultraviolet transmittance in the ultraviolet range, particularly in the deep ultraviolet range. Furthermore, in the film-coated inorganic plate according to Aspect 1, the silicon oxide layer is provided as the outermost layer of the anti-reflection film. Therefore, when the film-coated inorganic plate is bonded to another component via a bonding material such as a resin adhesive, wettability with the bonding material can be improved, thereby improving adhesion when bonding the film-coated inorganic plate to another component. Therefore, when such a film-coated inorganic plate is used as a cover member for a package containing an optical element, adhesion between the film-coated inorganic plate and the case body can be improved during the manufacturing process, thereby improving airtightness within the package. In this specification, the ultraviolet region refers to a wavelength of 100 nm or more and 380 nm or less, and the deep ultraviolet region refers to a wavelength of 100 nm or more and 280 nm or less. However, when determining ultraviolet transmittance, the light transmittance is confirmed by measuring the light transmittance at a wavelength of 190 nm or more and 380 nm or less, and when determining ultraviolet transmittance in the deep ultraviolet region, the light transmittance is confirmed by measuring the light transmittance at a wavelength of 200 nm.

[0010] In the film-coated inorganic plate of Aspect 2, it is preferable that the silicon oxide layer has a thickness of 10 nm or more and 100 nm or less, and the aluminum oxide layer has a thickness of 2 nm or more and 10 nm or less, in Aspect 1. In this case, the antireflection function of the antireflection film can be further improved, and the ultraviolet transmittance of the film-coated inorganic plate in the deep ultraviolet region can be further improved.

[0011] The film-coated inorganic plate of Aspect 3 is preferably the same as Aspect 1 or Aspect 2, in which the number of silicon oxide layers in the antireflection film is 2 to 5, and the number of aluminum oxide layers in the antireflection film is 1 to 4. In this case, the antireflection function of the antireflection film can be further improved, and the ultraviolet transmittance of the film-coated inorganic plate in the deep ultraviolet region can be further improved.

[0012] The film-coated inorganic plate of Aspect 4 is preferably configured from quartz glass in any one of Aspects 1 to 3. In this case, the ultraviolet transmittance of the film-coated inorganic plate in the deep ultraviolet region can be further increased.

[0013] The film-coated inorganic plate of Aspect 5 is preferably the same as any one of Aspects 1 to 4, except that the silicon oxide layer is provided on one main surface of the inorganic plate. In this case, the adhesion between the inorganic plate and the antireflection film can be further improved.

[0014] The film-coated inorganic plate of Aspect 6 is preferably such that the contact angle of pure water with respect to the surface of the film-coated inorganic plate on the antireflection film side is 7° or less in any of Aspects 1 to 5. In this case, the adhesiveness when the film-coated inorganic plate is bonded to another member with a bonding material can be further improved, and the airtightness inside a package that mounts an optical element can be further improved.

[0015] The film-coated inorganic plate of Aspect 7, in any one of Aspects 1 to 6, preferably has a light transmittance of 80% or more at a thickness of 0.5 mm and a wavelength of 200 nm. In this case, for example, when the film-coated inorganic plate is used as a cover member for a package that mounts an imaging element, ultraviolet light in the deep ultraviolet region can be more reliably incident on the imaging element. Furthermore, in this case, for example, when the film-coated inorganic plate is used as a cover member for a package that mounts a light-emitting element, ultraviolet light in the deep ultraviolet region emitted from the light-emitting element can be more reliably transmitted.

[0016] A method for producing a film-coated inorganic plate according to Aspect 8 of the present invention is the method for producing a film-coated inorganic plate according to any one of Aspects 1 to 7, and is characterized by comprising the steps of: preparing an inorganic plate; and forming an anti-reflection film by alternately laminating silicon oxide layers and aluminum oxide layers by ion-assisted deposition on one main surface of the inorganic plate. By forming each layer by ion-assisted deposition, it is possible to further improve the adhesion when the film-coated inorganic plate is bonded to another member with a bonding material, and to further improve the airtightness inside a package that mounts an optical element.

[0017] In the method for producing a film-coated inorganic plate of Aspect 9, in Aspect 8, it is preferable that, when forming the silicon oxide layer that will be the outermost layer of the antireflection film, the silicon oxide layer is formed using a larger ion irradiation dose than when forming the other layers that make up the antireflection film. In this case, the outermost silicon oxide layer can be made smoother, and as a result, the adhesiveness when the film-coated inorganic plate is bonded to another member with a bonding material can be further improved, and the airtightness inside a package that mounts an optical element can be further improved.

[0018] A package according to aspect 10 of the present invention comprises a case body having a bottom and sidewalls, an optical element provided on the bottom of the case body, and a cover member provided on the sidewalls of the case body, wherein the cover member is a film-coated inorganic plate according to any one of aspects 1 to 7, and the anti-reflection film on the film-coated inorganic plate and the upper surface of the sidewalls of the case body are bonded via a bonding material, thereby sealing the inside of the package containing the optical element.

[0019] According to the present invention, it is possible to provide a film-coated inorganic plate that has excellent ultraviolet transmittance and that, when used in a package that mounts an element such as an imaging element or a light-emitting element (hereinafter referred to as an optical element), can increase the airtightness within the package, a method for manufacturing the film-coated inorganic plate, and a package using the film-coated inorganic plate.

[0020] Fig. 1 is a schematic cross-sectional view showing a film-coated inorganic plate according to one embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing a modified film-coated inorganic plate. Fig. 3 is a schematic cross-sectional view showing a package including a film-coated inorganic plate according to one embodiment of the present invention. Fig. 4 shows the light transmission spectra of the film-coated inorganic plates obtained in Examples 1 and 2 in the wavelength range of 190 nm to 790 nm.

[0021] Preferred embodiments will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0022] [Film-Coated Inorganic Plate] FIG. 1 is a schematic cross-sectional view showing a film-coated inorganic plate according to one embodiment of the present invention.

[0023] As shown in Fig. 1, the film-coated inorganic plate 1 includes an inorganic plate 2 and an anti-reflection film 3. The inorganic plate 2 is ultraviolet-transmitting. The inorganic plate 2 has a substantially rectangular plate shape. However, the inorganic plate 2 may have a substantially circular plate shape, and the shape of the inorganic plate 2 is not particularly limited.

[0024] The inorganic plate 2 has a first main surface 2 a and a second main surface 2 b facing each other. An anti-reflection film 3 is provided on the first main surface 2 a of the inorganic plate 2. In this embodiment, no anti-reflection film is provided on the second main surface 2 b of the inorganic plate 2.

[0025] The antireflection coating 3 has a silicon oxide layer 4 and an aluminum oxide layer 5. The antireflection coating 3 is a dielectric multilayer film formed by alternately laminating the silicon oxide layers 4 and the aluminum oxide layers 5. In this embodiment, the antireflection coating 3 is formed by alternately laminating three silicon oxide layers 4 and two aluminum oxide layers 5 in this order starting from the silicon oxide layer 4. The silicon oxide layer 4 is disposed on the outermost layer 3a of the antireflection coating 3.

[0026] The silicon oxide layer 4 is made of silicon oxide (SiO ２ The aluminum oxide layer 5 is a film containing aluminum oxide (Al ２ O ３ In this specification, a film containing a material as a main component refers to a film containing 90 mass % or more of that material, and it is preferable that the film containing a material as a main component is a film constituted only by that material excluding impurities.

[0027] In this embodiment, the thickness ratio of the silicon oxide layer 4 to the aluminum oxide layer 5 (silicon oxide layer 4 / aluminum oxide layer 5) is 5 or more. The thickness ratio (silicon oxide layer 4 / aluminum oxide layer 5) is the ratio between the total thickness of the silicon oxide layers 4 and the total thickness of the aluminum oxide layers 5. When there are multiple silicon oxide layers 4, the total thickness of the silicon oxide layers 4 is defined as the sum of the thicknesses of the silicon oxide layers 4. Similarly, when there are multiple aluminum oxide layers 5, the total thickness of the aluminum oxide layers 5 is defined as the sum of the thicknesses of the aluminum oxide layers 5.

[0028] The film-coated inorganic plate 1 of this embodiment has the above-mentioned configuration, and therefore has excellent ultraviolet transmittance, and when used in a package that mounts an element such as an imaging element or a light-emitting element (hereinafter referred to as an optical element), it can improve the airtightness inside the package. This point will be described in detail below.

[0029] Conventionally, because aluminum oxide has an absorbing effect in the deep ultraviolet region, it has been difficult to sufficiently enhance the ultraviolet transmittance in the ultraviolet region, especially the deep ultraviolet region, of a film-coated inorganic plate formed by providing an aluminum oxide film on an inorganic plate. On the other hand, because a magnesium fluoride film does not have an absorbing effect in the deep ultraviolet region, it has poor wettability with bonding materials such as resin adhesives. Therefore, when the surface of the film-coated inorganic plate on which the magnesium fluoride film is provided is bonded to another component using a bonding material, the adhesion may not be sufficiently enhanced. For example, when a film-coated inorganic plate is used as a cover member for a package mounting an optical element, if the film-coated inorganic plate is bonded to the case body using a bonding material in the manufacturing process, the adhesion between the film-coated inorganic plate and the case body may not be sufficiently enhanced due to the poor wettability of the magnesium fluoride film and the bonding material. Therefore, a film-coated inorganic plate formed by providing a magnesium fluoride film on an inorganic plate has been problematic in that it is not possible to sufficiently enhance the airtightness of the package in which the optical element is mounted.

[0030] In contrast, in the film-coated inorganic plate 1 of the present embodiment, the silicon oxide layer 4 is a film with a relatively low refractive index, and the aluminum oxide layer 5 is a film with a relatively high refractive index, so that by alternately laminating these layers, an anti-reflection function can be imparted. Furthermore, in the film-coated inorganic plate 1, the thickness ratio of the silicon oxide layer 4 to the aluminum oxide layer 5 (silicon oxide layer 4 / aluminum oxide layer 5) is 5 or more, and the thickness of the aluminum oxide layer 5 is small, so that ultraviolet transmittance in the ultraviolet range, particularly in the deep ultraviolet range, can be increased.

[0031] Furthermore, the film-coated inorganic plate 1 of this embodiment has a silicon oxide layer 4 provided as the outermost layer 3a of the anti-reflection coating 3. Therefore, when the film-coated inorganic plate 1 is bonded to another member via a bonding material such as a resin adhesive, the wettability of the film-coated inorganic plate 1 to the bonding material can be improved, and adhesion can be improved when the film-coated inorganic plate 1 is bonded to another member. Therefore, when the film-coated inorganic plate 1 of this embodiment is used as a cover member for a package that mounts an optical element, adhesion between the film-coated inorganic plate 1 and the case body can be improved in the manufacturing process, and the airtightness inside the package can be improved.

[0032] Furthermore, in the film-coated inorganic plate 1 of this embodiment, the silicon oxide layer 4, which has extremely high weather resistance, is provided as the outermost layer 3a of the antireflection coating 3, so that the weather resistance of the antireflection coating 3 can be improved.

[0033] In this embodiment, the total light transmittance of the film-coated inorganic plate 1 at a thickness of 0.5 mm and a wavelength of 190 nm to 380 nm is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. In this case, it is possible to further increase the ultraviolet light transmittance of the film-coated inorganic plate 1. It is desirable that the upper limit of the total light transmittance of the film-coated inorganic plate 1 at a thickness of 0.5 mm and a wavelength of 190 nm to 380 nm is as high as possible, but in reality it is, for example, 95%.

[0034] In this embodiment, the light transmittance of the film-coated inorganic plate 1 at a thickness of 0.5 mm and a wavelength of 200 nm is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. In this case, the ultraviolet transmittance in the deep ultraviolet region of the film-coated inorganic plate 1 can be further increased. Note that, although the higher the upper limit of the light transmittance of the film-coated inorganic plate 1 at a thickness of 0.5 mm and a wavelength of 200 nm, the more desirable it is, but in reality, it is 95%.

[0035] In this embodiment, the contact angle of pure water with the surface 3b of the film-coated inorganic plate 1 on the side of the antireflection film 3 is preferably 7° or less, and more preferably 5° or less. In this case, the adhesiveness when the film-coated inorganic plate 1 is bonded to another member using a bonding material can be further improved, and the airtightness inside a package that mounts an optical element can be further improved. Furthermore, the lower limit of the contact angle of pure water with the surface 3b of the film-coated inorganic plate 1 on the side of the antireflection film 3 is preferably as small as possible, but in reality, it is, for example, 4°.

[0036] The contact angle (θ) of pure water with respect to the surface 3b of the film-coated inorganic plate 1 on the side of the anti-reflection film 3 can be measured based on the sessile drop method (θ / 2 approximation method) of JIS R 3257:1999.

[0037] In this embodiment, the antireflection coating 3 is formed by alternately stacking a total of five silicon oxide layers 4 and aluminum oxide layers 5 on the first main surface 2a of the inorganic plate 2. However, in the present invention, the antireflection coating 3 may be formed by alternately stacking a total of nine silicon oxide layers 4 and aluminum oxide layers 5 on the first main surface 2a of the inorganic plate 2, as in the film-coated inorganic plate 1A of a modified example shown in Figure 2, and the total number of silicon oxide layers 4 and aluminum oxide layers 5 stacked is not particularly limited.

[0038] In this embodiment, the total number of stacked silicon oxide layers 4 and aluminum oxide layers 5 constituting the antireflection coating 3 is preferably 3 or more, more preferably 5 or more, and even more preferably 7 or more, and is preferably 15 or less, more preferably 13 or less, and even more preferably 11 or less. In this case, the antireflection function of the antireflection coating 3 can be further improved, and the ultraviolet transmittance of the film-coated inorganic plate 1 in the deep ultraviolet region can be further improved.

[0039] In this embodiment, a silicon oxide layer 4 is provided on the first main surface 2a of the inorganic plate 2. When the silicon oxide layer 4 is provided on the first main surface 2a of the inorganic plate 2, it is possible to further improve the adhesion between the anti-reflection film 3 and the first main surface 2a of the inorganic plate 2. However, in the present invention, an aluminum oxide layer 5 may be provided on the first main surface 2a of the inorganic plate 2, and is not particularly limited thereto.

[0040] In this embodiment, the anti-reflection film 3 is provided only on the first main surface 2 a of the inorganic plate 2. When the anti-reflection film 3 is provided only on one main surface of the inorganic plate 2 as in this embodiment, when the film-coated inorganic plate 1 is bonded to another member with a bonding material, the inorganic plate 1 is bonded to the other member from the anti-reflection film 3 side via the bonding material. However, in the present invention, the anti-reflection film 3 may be provided on each of the first main surface 2 a and the second main surface 2 b, which are the main surfaces on both sides of the inorganic plate 2.

[0041] Note that when the antireflection coating 3 is multi-layered, multiple sharp peaks and valleys of optical interference occur. Therefore, when the antireflection coating 3 is formed on both main surfaces of the inorganic plate 2, the wavelengths of the peaks and valleys in the light transmission spectrum of the film-coated inorganic plate 1 shift, and the light transmittance tends to decrease. As a result, the yield of the film-coated inorganic plate 1 tends to decrease. Therefore, it is desirable to provide the antireflection coating 3 only on the first main surface 2 a of the inorganic plate 2.

[0042] In this embodiment, the antireflection coating 3 is provided over the entire first main surface 2a of the inorganic plate 2. However, the antireflection coating 3 may be provided only partially in an area of ​​the first main surface 2a of the inorganic plate 2 that requires ultraviolet light transmission. Furthermore, the silicon oxide layer 4 in the outermost layer 3a of the antireflection coating 3 may be provided only partially in an area of ​​the first main surface 2a of the inorganic plate 2 that is to be bonded to another member.

[0043] In addition, the entire or part of the silicon oxide layer 4 other than the outermost layer 3a of the antireflection film 3 is made of magnesium fluoride (MgF ２ In this case, the layer may be replaced with a magnesium fluoride (MgF ２) layers and aluminum oxide layers 5 are preferably stacked alternately.

[0044] Hereinafter, each of the members constituting the film-coated inorganic plate 1 will be described in detail.

[0045] (Inorganic Plate) The total light transmittance of the inorganic plate 2 at a thickness of 0.5 mm and a wavelength of 190 nm to 380 nm is preferably 90% or more, more preferably 93% or more, and even more preferably 94% or more. In this case, the ultraviolet transmittance of the film-coated inorganic plate 1 can be further increased. Note that, although the upper limit of the total light transmittance of the inorganic plate 2 at a thickness of 0.5 mm and a wavelength of 190 nm to 380 nm is preferably as high as possible, a practical upper limit of 95% is preferable.

[0046] In this embodiment, the light transmittance of the inorganic plate 2 at a thickness of 0.5 mm and a wavelength of 200 nm is preferably 90% or more, more preferably 93% or more, and even more preferably 94% or more. In this case, the ultraviolet transmittance in the deep ultraviolet region of the film-coated inorganic plate 1 can be further increased. Note that, although the higher the upper limit of the light transmittance of the inorganic plate 2 at a thickness of 0.5 mm and a wavelength of 200 nm, the more desirable it is, but in reality, 95% is used.

[0047] Examples of materials that can be used for the inorganic plate 2 include ultraviolet-transmitting glass, sapphire, and diamond. Examples of ultraviolet-transmitting glass include quartz glass and borosilicate glass. Of these, it is preferable that the inorganic plate 2 be a quartz glass plate. In this case, the ultraviolet transmittance of the film-coated inorganic plate 1 in the deep ultraviolet region can be further increased.

[0048] The inorganic plate 2 may have a thickness of, for example, 0.1 mm to 1.5 mm.

[0049] (Anti-Reflection Film) The total thickness of the anti-reflection film 3 is preferably 80 nm or more, more preferably 150 nm or more, and even more preferably 250 nm or more, and is preferably 400 nm or less, more preferably 350 nm or less, and even more preferably 320 nm or less.

[0050] In particular, in the antireflection coating 3, the thickness ratio of the silicon oxide layer 4 to the aluminum oxide layer 5 (silicon oxide layer 4 / aluminum oxide layer 5) is 5 or more, more preferably 10 or more, even more preferably 12 or more, and is preferably 20 or less, more preferably 17 or less, even more preferably 15 or less. In this case, the antireflection function of the antireflection coating 3 can be further improved, while the ultraviolet transmittance of the film-coated inorganic plate 1 in the deep ultraviolet region can be further increased.

[0051] The thickness of each silicon oxide layer 4 is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more, and is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 50 nm or less. When the thickness of each silicon oxide layer 4 is within the above range, the anti-reflection function of the film-coated inorganic plate 1 in the deep ultraviolet region can be further improved, while a decrease in ultraviolet transmittance due to an increase in film thickness can be more reliably avoided. Furthermore, by specifying the thickness of the silicon oxide layer 4 to be equal to or greater than the above lower limit, the weather resistance of the film-coated inorganic plate 1 can be further improved.

[0052] The thickness of each aluminum oxide layer 5 is preferably 2 nm or more, more preferably 4 nm or more, and even more preferably 5 nm or more, and is preferably 10 nm or less, more preferably 8 nm or less, and even more preferably 7 nm or less. When the thickness of each aluminum oxide layer 5 is within the above range, the antireflection function of the film-coated inorganic plate 1 in the deep ultraviolet region can be further improved, while a decrease in ultraviolet transmittance due to an increase in film thickness can be more reliably avoided.

[0053] The number of silicon oxide layers 4 in the antireflection coating 3 is preferably 2 or more, more preferably 3 or more, and preferably 9 or less, more preferably 7 or less, and even more preferably 5 or less. When the number of silicon oxide layers 4 in the antireflection coating 3 is within the above range, the antireflection function of the film-coated inorganic plate 1 in the deep ultraviolet region can be further improved, while a decrease in ultraviolet transmittance due to an increase in film thickness can be more reliably avoided.

[0054] The number of aluminum oxide layers 5 in the antireflection coating 3 is preferably 1 or more, more preferably 2 or more, and preferably 8 or less, more preferably 6 or less, and even more preferably 4 or less. When the number of aluminum oxide layers 5 in the antireflection coating 3 is within the above range, the antireflection function of the film-coated inorganic plate 1 in the deep ultraviolet region can be further improved, while a decrease in ultraviolet transmittance due to an increase in film thickness can be more reliably avoided.

[0055] An example of a method for producing the film-coated inorganic substrate 1 will be described below.

[0056] (Method for manufacturing a film-coated inorganic plate) In a method for manufacturing a film-coated inorganic plate 1, first, an inorganic plate 2 is prepared. Next, silicon oxide layers 4 and aluminum oxide layers 5 are alternately laminated on a first main surface 2a of the inorganic plate 2 to form an anti-reflection coating 3. In this way, a film-coated inorganic plate 1 can be obtained.

[0057] The method for forming the silicon oxide layer 4 and the aluminum oxide layer 5 is not particularly limited, and they can be formed, for example, by forming the silicon oxide layer 4 and the aluminum oxide layer 5 on the first main surface 2 a of the inorganic plate 2 using a deposition method such as sputtering or vacuum deposition.

[0058] Conventional sputtering and vacuum deposition methods can be used, but the substrate temperature during film formation is preferably 150° C. or higher, more preferably 200° C. or higher, and preferably 350° C. or lower. In particular, if the substrate temperature during film formation of the silicon oxide layer 4 that constitutes the outermost layer 3 a of the antireflection coating 3 is within the above range, the adhesiveness when the film-coated inorganic plate 1 is bonded to another member with a bonding material can be further improved, and the airtightness inside the package in which the optical element is mounted can be further improved.

[0059] The silicon oxide layer 4 and the aluminum oxide layer 5 are preferably formed by ion-assisted vapor deposition. By forming each layer by ion-assisted vapor deposition, the adhesiveness when bonding the film-coated inorganic plate 1 to another member with a bonding material can be further improved, and the airtightness inside the package in which the optical element is mounted can be further improved.

[0060] In particular, when forming the silicon oxide layer 4 constituting the outermost layer 3a of the anti-reflection coating 3, it is preferable to deposit the silicon oxide layer 4 constituting the outermost layer 3a using a higher ion irradiation dose than when forming the other layers constituting the anti-reflection coating 3. In this case, high-energy sputtered or vapor-deposited particles are implanted into the already formed film surface, thereby pressing convex portions of the film surface into the film. This makes the silicon oxide layer 4 constituting the outermost layer 3a smoother and denser, thereby further improving adhesion when the film-coated inorganic plate 1 is bonded to other components using a bonding material and further improving the airtightness of the package containing the optical element. The deposition rate is preferably 3 Å / sec or more and 8 Å / sec or less when forming the silicon oxide layer 4, and 3 Å / sec or more and 8 Å / sec or less when forming the aluminum oxide layer 5.

[0061] The ion irradiation dose when forming the silicon oxide layer 4 constituting the outermost layer 3a of the antireflection coating 3 is preferably 1 to 1.5 times the ion irradiation dose when forming the other layers constituting the antireflection coating 3. The ion irradiation dose when forming the silicon oxide layer 4 constituting the outermost layer 3a of the antireflection coating 3 is, for example, 1 mA / cm ２ Above, 1.5mA / cm ２ The ion irradiation time when forming the silicon oxide layer 4 constituting the outermost layer 3a of the antireflection coating 3 can be, for example, 60 seconds or more and 300 seconds or less.

[0062] [Package] FIG. 3 is a schematic cross-sectional view showing a package including a film-coated inorganic substrate according to one embodiment of the present invention.

[0063] As shown in FIG. 3, the package 11 includes the film-coated inorganic plate 1 as a cover member, a case body 12, and an image sensor 13 as an imaging element.

[0064] The case body 12 has a bottom 12 a and a frame-shaped side wall 12 b. The side wall 12 b is provided on the bottom 12 a. The case body 12 can be made of a material such as ceramics, such as aluminum nitride, or glass ceramics.

[0065] A film-coated inorganic plate 1 serving as a cover member is provided on an upper surface 12c of a side wall portion 12b of the case body 12. The upper surface 12c of the side wall portion 12b and the film-coated inorganic plate 1 are bonded together with a bonding material 14, thereby sealing the inside of the package 11 on which the image sensor 13 is mounted. In this embodiment, the anti-reflection film 3 side of the film-coated inorganic plate 1 is bonded to the upper surface 12c of the side wall portion 12b via the bonding material 14.

[0066] There are no particular limitations on the bonding material 14, and it is possible to use, for example, a resin adhesive or a solder film. As the resin adhesive, it is possible to use a resin such as an ultraviolet curing adhesive.

[0067] The image sensor 13 is disposed on the bottom 12a of the case body 12. In this embodiment, the package 11 is equipped with the image sensor 13 as an imaging element, but the package 11 may be equipped with other optical elements such as light-emitting elements such as deep ultraviolet LEDs, and is not particularly limited thereto.

[0068] In the package 11 of this embodiment, the above-described film-coated inorganic plate 1 is used as a cover member, thereby improving the airtightness inside the package 11. In addition, since the film-coated inorganic plate 1 has excellent ultraviolet transmittance, the package 11 of this embodiment allows ultraviolet light to be efficiently incident on the image sensor 13.

[0069] In this embodiment, the film-coated inorganic plate 1 is used as the cover member of the package 11, but the film-coated inorganic plate 1 may be directly bonded to the image sensor 13 via a bonding material 14. Even in this case, the film-coated inorganic plate 1 and the image sensor 13 can be reliably bonded by bonding the anti-reflection film 3 side of the film-coated inorganic plate 1 to the image sensor 13 via the bonding material 14. Furthermore, ultraviolet light can be efficiently incident on the image sensor 13 through the film-coated inorganic plate 1.

[0070] The present invention will be described in more detail below with reference to specific examples. The present invention is not limited to the following examples, and can be practiced with appropriate modifications within the scope of the present invention.

[0071] Example 1 First, a quartz glass plate (manufactured by SHANGHAI WECHANCE INDUSTRIA, product number "JGS01", thickness: 0.5 mm) was prepared as an inorganic plate. Next, silicon oxide (SiO ２ ) layer and aluminum oxide (Al ２ O ３ More specifically, the substrate temperature was set to 200° C., and O was used as a carrier gas. ２ Using gas, SiO ２ The film material was heated by irradiating it with thermoelectrons, and the film formation rate was set to 0.5 nm / sec. ２ Next, a layer was formed using O as a carrier gas. ２ Using gas, Al placed in the hearth liner ２ O ３ The film material was heated by irradiating it with thermoelectrons, and the film formation rate was set to 5 nm / sec. Al was deposited on one main surface of the inorganic plate. ２ O ３ In this way, a SiO layer was formed on one main surface of the inorganic plate. ２ layer and Al ２ O ３ The layers were alternately stacked to form a total of five layers, thereby obtaining an anti-reflection film. In this way, a film-coated inorganic plate was obtained. ２ When forming the layer, the ion irradiation dose was 1.1 mA / cm ２ The ion irradiation was carried out for 125 seconds (hours). ２ When forming the layer, the ion irradiation dose was 0.8 mA / cm ２ The ion irradiation was carried out for 125 seconds (hours) with the above conditions. The thickness of each layer constituting the antireflection film is as shown in Table 1 below. In Example 1, the thickness ratio of the silicon oxide layer to the aluminum oxide layer (total thickness of the silicon oxide layers / total thickness of the aluminum oxide layers) was 17.6.

[0072] Example 2 SiO ２ layer and Al ２ O ３ A film-coated inorganic plate was obtained in the same manner as in Example 1, except that the layers were alternately laminated to obtain a total of nine layers to obtain an antireflection coating, and the thickness of each layer constituting the antireflection coating was changed as shown in the following Table 1. In Example 2, the thickness ratio of the silicon oxide layer to the aluminum oxide layer (total thickness of the silicon oxide layers / total thickness of the aluminum oxide layers) was 13.2.

[0073]

[0074] (Example 3) Outermost layer SiO ２ When forming the layer, the ion irradiation dose was 0.8 mA / cm ２ A film-coated inorganic substrate was obtained in the same manner as in Example 1, except that the ion irradiation was carried out for 142 seconds (hours) as the temperature.

[0075] [Evaluation] (Evaluation of Contact Angle) The contact angle θ of pure water with respect to the surface of the anti-reflection film side of the film-coated inorganic plate of Examples 1 to 3 was measured.

[0076] The contact angle θ was measured based on the sessile drop method (θ / 2 approximation method) of JIS R 3257: 1999. Specifically, 5 mg of pure water was dropped onto each of the film-attached inorganic plates placed horizontally, and then the water droplet was photographed from directly above using a measuring microscope (manufactured by Nikon Corporation), and the contact angle θ was determined from the outer diameter of the water droplet.

[0077] The contact angle θ of pure water with respect to the surface of the anti-reflection film side of the film-coated inorganic plate in Example 1 was 2.7°, the contact angle θ was 3.5° in Example 2, and the contact angle was 3.9° in Example 3. As a reference example, magnesium fluoride (MgF ２ ) film, the contact angle θ was 7.5°.

[0078] (Evaluation of Light Transmittance) The light transmittance of the film-coated inorganic plates of Examples 1 and 2 was measured using a spectrophotometer (Hitachi High-Tech Corporation, product number "U-4150"). Figure 4 shows the light transmission spectra of the film-coated inorganic plates obtained in Examples 1 and 2 in the wavelength range of 190 nm to 790 nm. Note that Figure 4 also shows the light transmission spectrum of a quartz glass plate as a reference example.

[0079] As shown in FIG. 4, it was confirmed that the film-attached inorganic plates of Examples 1 and 2 have high ultraviolet transmittance, particularly in the deep ultraviolet region.

[0080] From the above, the film-coated inorganic plates of Examples 1 and 2 have high ultraviolet transmittance in the deep ultraviolet region, and magnesium fluoride (MgF ２ ) film, it has been confirmed that the contact angle with pure water is smaller than that of the film, and therefore it can improve the airtightness inside the package containing the optical element.

[0081] DESCRIPTION OF SYMBOLS 1, 1A... Film-attached inorganic plate 2... Inorganic plate 2a... First main surface 2b... Second main surface 3a... Outermost layer 3b... Surface 3... Anti-reflection film 4... Silicon oxide layer 5... Aluminum oxide layer 11... Package 12... Case body 12a... Bottom 12b... Side wall 12c... Upper surface 13... Image sensor 14... Bonding material

Claims

1. A film-coated inorganic plate comprising: an inorganic plate having ultraviolet light transparency; and an anti-reflection film provided on one main surface of the inorganic plate, wherein the anti-reflection film is composed of silicon oxide layers and aluminum oxide layers alternately laminated together, the silicon oxide layer is provided as the outermost layer of the anti-reflection film, and the thickness ratio of the silicon oxide layer to the aluminum oxide layer (silicon oxide layer / aluminum oxide layer) is 5 or more.

2. The film-coated inorganic board according to claim 1, wherein the silicon oxide layer has a thickness of 10 nm or more and 100 nm or less, and the aluminum oxide layer has a thickness of 2 nm or more and 10 nm or less.

3. The film-coated inorganic plate according to claim 1 or 2, wherein the number of silicon oxide layers in the anti-reflective coating is 2 or more and 5 or less, and the number of aluminum oxide layers in the anti-reflective coating is 1 or more and 4 or less.

4. The film-coated inorganic substrate according to claim 1 or 2, wherein the inorganic substrate is made of quartz glass.

5. The film-coated inorganic board according to claim 1 or 2, wherein the silicon oxide layer is provided on one main surface of the inorganic board.

6. The film-coated inorganic plate according to claim 1 or 2, wherein the contact angle of pure water with respect to the surface of the film-coated inorganic plate on the anti-reflection film side is 7° or less.

7. The film-coated inorganic plate according to claim 1 or 2, wherein the film-coated inorganic plate has a light transmittance of 80% or more at a thickness of 0.5 mm and a wavelength of 200 nm.

8. A method for producing a film-coated inorganic plate according to claim 1 or 2, comprising the steps of: preparing an inorganic plate; and forming an anti-reflective film by alternately laminating silicon oxide layers and aluminum oxide layers on one main surface of the inorganic plate by ion-assisted deposition.

9. The method for producing a film-coated inorganic plate described in claim 8, wherein when forming the silicon oxide layer that is the outermost layer of the anti-reflective film, the amount of ion irradiation is increased to form the silicon oxide layer compared to when forming other layers that constitute the anti-reflective film.

10. A package comprising: a case body having a bottom and a side wall; an optical element provided on the bottom of the case body; and a cover member provided on the side wall of the case body, wherein the cover member is a film-coated inorganic plate as described in claim 1 or 2, and the anti-reflection film of the film-coated inorganic plate and an upper surface of the side wall of the case body are bonded via a bonding material to seal the inside of the package containing the optical element.

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