Inorganic plate with film and method of manufacturing the same, and package

Abstract

To provide an inorganic plate with a film that has superior ultraviolet transmission properties and can enhance airtightness in a package when used for a package mounted with an optical element.SOLUTION: There is provided an inorganic plate 1 with a film that comprises an inorganic plate 2 which has ultraviolet transmission properties and an antireflection film 3 which is provided on a principal surface 2a on one side of the inorganic plate 2, wherein the antireflection film 3 is formed by stacking a silicon oxide layer 4 and an aluminum oxide layer 5 alternately, an outermost layer 3a of the antireflection film 3 is provided with the silicon oxide layer 4, and 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 larger.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an inorganic plate with a film having ultraviolet transmissivity, a method for manufacturing the inorganic plate with a film, and a package using the inorganic plate with a film.

Background Art

[0002] Conventionally, ultraviolet rays such as deep ultraviolet rays are known to have a bactericidal action and a decomposition action of organic substances, and light-emitting elements such as LEDs that emit ultraviolet rays are widely used in medical sites and food factories. In recent years, UV cameras have attracted attention, and the demand for imaging elements such as image sensors corresponding to the ultraviolet wavelength range including the deep ultraviolet region is also increasing.

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the film material described in Patent Document 1 includes a material that absorbs in the deep ultraviolet region. An inorganic plate with a film using such a material has a problem that the ultraviolet transmittance in the ultraviolet region, particularly in the deep ultraviolet region, cannot be sufficiently increased. On the other hand, a film material that does not have an absorption effect in the deep ultraviolet region may not have sufficient wettability with the bonding material used when bonding the inorganic plate with a film and the case body in the manufacturing process of the package as described above, and the airtightness may not be sufficiently increased when sealing the inside of the package.

[0006] An object of the present invention is to provide an inorganic plate with a film, a method for manufacturing the inorganic plate with a film, and a package using the inorganic plate with a film, which are excellent in ultraviolet transmittance and can enhance the airtightness inside the package when used in a package for mounting elements such as an imaging element and a light-emitting element (hereinafter referred to as an optical element).

Means for Solving the Problems

[0007] Each aspect of the inorganic plate with a film for solving the above problems, the method for manufacturing the inorganic plate with a film, and the package using the inorganic plate with a film will be described.

[0008] The inorganic plate with a film according to Aspect 1 of the present invention includes an inorganic plate having ultraviolet transmittance and an antireflection film provided on the main surface on one side of the inorganic plate. The antireflection film is configured by alternately laminating a silicon oxide layer and an aluminum oxide layer, and the outermost layer of the antireflection film is provided with the silicon oxide layer. The thickness ratio of the silicon oxide layer to the aluminum oxide layer (silicon oxide layer / aluminum oxide layer) of the silicon oxide layer is 5 or more.

[0009] In the inorganic plate with a film according to Embodiment 1, since 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, an antireflection function can be imparted by alternately laminating them. Further, in the inorganic plate with a film according to Embodiment 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 since the thickness of the aluminum oxide layer is small, the ultraviolet transmittance in the ultraviolet region, particularly in the deep ultraviolet region, can be increased. Further, in the inorganic plate with a film according to Embodiment 1, since the silicon oxide layer is provided on the outermost layer of the antireflection film, when the inorganic plate with a film and another member are bonded together via a bonding material such as a resin adhesive, the wettability with respect to the bonding material can be increased, and the adhesion when the inorganic plate with a film is bonded to another member can be increased. Therefore, when such an inorganic plate with a film is used as a cover member of a package on which an optical element is mounted, the adhesion between the inorganic plate with a film and the case body can be increased in the manufacturing process, and the airtightness inside the package can be increased. 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 the ultraviolet transmittance, it is assumed that it is confirmed by measuring the light transmittance at a wavelength of 190 nm or more and 380 nm or less, and when determining the ultraviolet transmittance in the deep ultraviolet region, it is assumed that it is confirmed by measuring the light transmittance at a wavelength of 200 nm.

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

[0011] In the inorganic plate with a film according to Embodiment 3, in Embodiment 1 or Embodiment 2, the number of layers of the silicon oxide layer in the antireflection film is preferably 2 or more and 5 or less, and the number of layers of the aluminum oxide layer in the antireflection film is preferably 1 or more and 4 or less. In this case, the antireflection function of the antireflection film can be further enhanced, and the ultraviolet transmittance in the deep ultraviolet region of the inorganic plate with a film can be further enhanced.

[0012] In the inorganic plate with a film according to Embodiment 4, in any one of Embodiments 1 to 3, it is preferable that the inorganic plate is made of quartz glass. In this case, the ultraviolet transmittance in the deep ultraviolet region of the inorganic plate with a film can be further enhanced.

[0013] In the inorganic plate with a film according to Embodiment 5, in any one of Embodiments 1 to 4, it is preferable that the silicon oxide layer is provided on the main surface on one side of the inorganic plate. In this case, the adhesion between the inorganic plate and the antireflection film can be further enhanced.

[0014] In the inorganic plate with a film according to Embodiment 6, in any one of Embodiments 1 to 5, the contact angle of pure water with respect to the surface of the inorganic plate with a film on the antireflection film side is preferably 7° or less. In this case, when the inorganic plate with a film is bonded to another member with an adhesive, the adhesiveness can be further enhanced, and the airtightness in the package on which the optical element is mounted can be further enhanced.

[0015] In the inorganic plate with a film according to Embodiment 7, in any one of Embodiments 1 to 6, the light transmittance at a thickness of 0.5 mm and a wavelength of 200 nm of the inorganic plate with a film is preferably 80% or more. In this case, for example, when the inorganic plate with a film is used as a cover member of a package on which an imaging element is mounted, ultraviolet light in the deep ultraviolet region can be surely incident on the imaging element. Further, in this case, for example, when the inorganic plate with a film is used as a cover member of a package on which a light-emitting element is mounted, ultraviolet light in the deep ultraviolet region emitted from the light-emitting element can be more surely transmitted.

[0016] The manufacturing method of the inorganic plate with a film according to Aspect 8 of the present invention is the manufacturing method of the inorganic plate with a film according to any one of Aspects 1 to 7, and includes a step of preparing an inorganic plate, and on the main surface on one side of the inorganic plate, a silicon oxide layer and an aluminum oxide layer are alternately laminated by an ion assist evaporation method to form an antireflection film. By forming each layer by the ion assist evaporation method, the adhesiveness when bonding the inorganic plate with a film to another member with an adhesive can be further enhanced, and the airtightness inside the package on which an optical element is mounted can be further enhanced.

[0017] In the manufacturing method of the inorganic plate with a film according to Aspect 9, in Aspect 8, when forming the silicon oxide layer that becomes the outermost layer of the antireflection film, it is preferable to increase the ion irradiation amount compared to the case of forming the other layers constituting the antireflection film to form the silicon oxide layer. In this case, the outermost silicon oxide layer can be made smoother, and as a result, the adhesiveness when bonding the inorganic plate with a film to another member with an adhesive can be further enhanced, and the airtightness inside the package on which an optical element is mounted can be further enhanced.

[0018] The package according to Aspect 10 of the present invention is a package including a case body having a bottom portion and side wall portions, an optical element provided on the bottom portion of the case body, and a cover member provided on the side wall portions of the case body, wherein the cover member is an inorganic plate with a film according to any one of Aspects 1 to 7, the antireflection film in the inorganic plate with a film and the upper surface of the side wall portion in the case body are joined via an adhesive, and the inside of the package in which the optical element is housed is sealed.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide an inorganic plate with a film, a manufacturing method of the inorganic plate with a film, and a package using the inorganic plate with a film, which are excellent in ultraviolet transmittance and can enhance the airtightness inside the package when used in a package on which elements such as an imaging element and a light emitting element (hereinafter, referred to as an optical element) are mounted.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0021] Hereinafter, preferred embodiments will be described. However, the following embodiments are merely illustrative, and the present invention is not limited to the following embodiments. Also, in each drawing, members having substantially the same function may be referred to by the same reference numerals.

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

[0023] As shown in FIG. 1, the inorganic plate 1 with a film includes an inorganic plate 2 and an antireflection film 3. The inorganic plate 2 has ultraviolet transmittance. Also, the inorganic plate 2 has a substantially rectangular plate shape. However, the inorganic plate 2 may have a substantially disc shape, and the shape of the inorganic plate 2 is not particularly limited.

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

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

[0026] The silicon oxide layer 4 is a film mainly composed of silicon oxide (SiO 2 ). Further, the aluminum oxide layer 5 is a film mainly composed of aluminum oxide (Al 2 O 3 ). In this specification, a film mainly composed of each material means a film containing 90% by mass or more of the material in the film, and it is preferable that a film mainly composed of each material is composed only of the material excluding impurities.

[0027] In the present 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 of the total thickness of the silicon oxide layer 4 to the total thickness of the aluminum oxide layer 5. When there are a plurality of silicon oxide layers 4, the total thickness of each silicon oxide layer 4 is taken as the total thickness of the silicon oxide layer 4. Similarly, when there are a plurality of aluminum oxide layers 5, the total thickness of each aluminum oxide layer 5 is taken as the total thickness of the aluminum oxide layer 5.

[0028] Since the inorganic plate 1 with a film of the present embodiment has the above configuration, it has excellent ultraviolet transmittance, and when used in a package on which elements such as an imaging element and a light-emitting element (hereinafter, optical elements) are mounted, the airtightness in the package can be improved. This point will be described in detail below.

[0029] Conventionally, since aluminum oxide has an absorption effect in the deep ultraviolet region, in an inorganic plate with an aluminum oxide film provided on the inorganic plate, it has been difficult to sufficiently enhance the ultraviolet transmittance in the ultraviolet region, particularly in the deep ultraviolet region. On the other hand, a magnesium fluoride film that does not have an absorption effect in the deep ultraviolet region has poor wettability with a bonding material such as a resin adhesive. Therefore, when the surface of the inorganic plate with the magnesium fluoride film provided thereon is bonded to another member with a bonding material, the adhesion may not be sufficiently enhanced. For example, when the inorganic plate with a film is used as a cover member of a package on which an optical element is mounted, in the manufacturing process, when the inorganic plate with a film is bonded to the case body with a bonding material, if it is bonded from the side of the magnesium fluoride film, due to the poor wettability between the magnesium fluoride film and the bonding material, the adhesion between the inorganic plate with a film and the case body may not be sufficiently enhanced. Therefore, in an inorganic plate with a magnesium fluoride film provided on the inorganic plate, there has been a problem that the airtightness in the package on which the optical element is mounted cannot be sufficiently enhanced.

[0030] In contrast, in the inorganic plate 1 with a film of the present embodiment, since 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, an antireflection function can be imparted by alternately laminating them. Further, in the inorganic plate 1 with a film, 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 since the thickness of the aluminum oxide layer 5 is small, the ultraviolet transmittance in the ultraviolet region, particularly in the deep ultraviolet region, can be enhanced.

[0031] Furthermore, in the inorganic plate 1 with a film of the present embodiment, a silicon oxide layer 4 is provided as the outermost layer 3a of the antireflection film 3. Therefore, when the inorganic plate 1 with a film and other members are bonded together via a bonding material such as a resin adhesive, the wettability with respect to the bonding material can be enhanced, and the adhesion when the inorganic plate 1 with a film is bonded to other members can be enhanced. Accordingly, when the inorganic plate 1 with a film of the present embodiment is used as a cover member of a package on which an optical element is mounted, the adhesion between the inorganic plate 1 with a film and the case body can be enhanced in the manufacturing process, and the airtightness inside the package can be enhanced.

[0032] Also, in the inorganic plate 1 with a film of the present embodiment, since a silicon oxide layer 4 having extremely high weather resistance is provided as the outermost layer 3a of the antireflection film 3, the weather resistance of the antireflection film 3 can be enhanced.

[0033] In the present embodiment, the total light transmittance of the inorganic plate 1 with a film at a thickness of 0.5 mm and wavelengths from 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, the ultraviolet transmittance of the inorganic plate 1 with a film can be further enhanced. Note that the upper limit value of the total light transmittance of the inorganic plate 1 with a film at a thickness of 0.5 mm and wavelengths from 190 nm to 380 nm is desirably higher, but realistically, for example, it is 95%.

[0034] In the present embodiment, the light transmittance of the inorganic plate 1 with a film 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 of the inorganic plate 1 with a film in the deep ultraviolet region can be further enhanced. Note that the upper limit value of the light transmittance of the inorganic plate 1 with a film at a thickness of 0.5 mm and a wavelength of 200 nm is desirably higher, but realistically, it is 95%.

[0035] In this embodiment, the contact angle of pure water with respect to the surface 3b on the antireflection film 3 side of the inorganic plate 1 with a film is preferably 7° or less, more preferably 5° or less. In this case, when the inorganic plate 1 with a film is bonded to another member with an adhesive, the adhesiveness can be further enhanced, and the airtightness inside the package on which the optical element is mounted can be further enhanced. Also, the lower limit value of the contact angle of pure water with respect to the surface 3b on the antireflection film 3 side of the inorganic plate 1 with a film is desirably as small as possible, but realistically, for example, it is 4°.

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

[0037] In this embodiment, the antireflection film 3 is formed by alternately laminating a total of 5 layers of a silicon oxide layer 4 and an aluminum oxide layer 5 on the first main surface 2a of the inorganic plate 2. However, in the present invention, like the inorganic plate 1A with a film of the modified example shown in FIG. 2, the antireflection film 3 may be formed by alternately laminating a total of 9 layers of a silicon oxide layer 4 and an aluminum oxide layer 5 on the first main surface 2a of the inorganic plate 2, and the total number of laminated layers of the silicon oxide layer 4 and the aluminum oxide layer 5 is not particularly limited.

[0038] In this embodiment, the total number of laminated layers of the silicon oxide layer 4 and the aluminum oxide layer 5 constituting the antireflection film 3 is preferably 3 layers or more, more preferably 5 layers or more, still more preferably 7 layers or more, and preferably 15 layers or less, more preferably 13 layers or less, still more preferably 11 layers or less. In this case, the antireflection function of the antireflection film 3 can be further enhanced, and the ultraviolet transmittance of the inorganic plate 1 with a film in the deep ultraviolet region can be further enhanced.

[0039] In addition, in the present 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, the adhesion between the antireflection film 3 and the first main surface 2a of the inorganic plate 2 can be further enhanced. 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 there is no particular limitation.

[0040] In addition, in the present embodiment, the antireflection film 3 is provided only on the first main surface 2a of the inorganic plate 2. When the antireflection film 3 is provided only on one main surface of the inorganic plate 2 as in the present embodiment, when the inorganic plate 1 with the film is bonded to another member with a bonding material, it shall be bonded to the other member through the bonding material from the side of the antireflection film 3. However, in the present invention, the antireflection film 3 may be provided on the first main surface 2a and the second main surface 2b which are the main surfaces on both sides of the inorganic plate 2, respectively.

[0041] Note that when the antireflection film 3 is made into multiple layers, there will be a plurality of steep valleys and peaks in the light interference. Therefore, when the antireflection film 3 is formed on the main surfaces on both sides of the inorganic plate 2, the wavelength of the valleys in the light transmission spectrum of the inorganic plate 1 with the film will shift, and the light transmittance will tend to decrease. As a result, the yield of the inorganic plate 1 with the film will tend to decrease. Therefore, it is desirable that the antireflection film 3 be provided only on the first main surface 2a of the inorganic plate 2.

[0042] In addition, in the present embodiment, the antireflection film 3 is provided on the entire first main surface 2a of the inorganic plate 2. However, the antireflection film 3 may be partially provided only in the region where ultraviolet transmission is required on the first main surface 2a of the inorganic plate 2. Also, the silicon oxide layer 4 in the outermost layer 3a of the antireflection film 3 may be partially provided only in the region where it adheres to other members on the first main surface 2a of the inorganic plate 2.

[0043] In addition, all or part of the silicon oxide layer 4 other than the outermost layer 3a of the antireflection film 3 is magnesium fluoride (MgF 2) layer may be replaced. In this case, it is desirable that the magnesium fluoride (MgF 2 ) layer and the aluminum oxide layer 5 are alternately laminated.

[0044] Hereinafter, details of each member constituting the inorganic plate 1 with a film will be described.

[0045] (Inorganic plate) The thickness of the inorganic plate 2 is 0.5 mm, and the total light transmittance at 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 inorganic plate 1 with a film can be further enhanced. Note that the upper limit value 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 desirably as high as possible, but in reality, it is 95%.

[0046] In the present 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 of the inorganic plate 1 with a film in the deep ultraviolet region can be further enhanced. Note that the upper limit value of the light transmittance of the inorganic plate 2 at a thickness of 0.5 mm and a wavelength of 200 nm is desirably as high as possible, but in reality, it is 95%.

[0047] As the material of the inorganic plate 2, for example, ultraviolet-transmitting glass, sapphire, diamond, etc. can be used. Examples of the ultraviolet-transmitting glass include quartz glass and borosilicate glass. Among them, the inorganic plate 2 is preferably a quartz glass plate. In this case, the ultraviolet transmittance of the inorganic plate 1 with a film in the deep ultraviolet region can be further enhanced.

[0048] The thickness of the inorganic plate 2 can be, for example, 0.1 mm to 1.5 mm.

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

[0050] Among them, in the antireflection film 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, still more preferably 12 or more, and preferably 20 or less, more preferably 17 or less, still more preferably 15 or less. In this case, while enhancing the antireflection function of the antireflection film 3, the ultraviolet transmittance of the inorganic plate 1 with a film in the deep ultraviolet region can be further enhanced.

[0051] The thickness of each layer of the silicon oxide layer 4 is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 30 nm or more, and preferably 100 nm or less, more preferably 80 nm or less, still more preferably 50 nm or less. When the thickness of each layer of the silicon oxide layer 4 is within the above range, while enhancing the antireflection function of the inorganic plate 1 with a film in the deep ultraviolet region, it is possible to more reliably avoid a decrease in the ultraviolet transmittance due to an increase in the film thickness. Further, by defining the thickness of the silicon oxide layer 4 to be equal to or greater than the above lower limit value, the weather resistance of the inorganic plate 1 with a film can be further enhanced.

[0052] The thickness of each layer of the aluminum oxide layer 5 is preferably 2 nm or more, more preferably 4 nm or more, still more preferably 5 nm or more, and preferably 10 nm or less, more preferably 8 nm or less, still more preferably 7 nm or less. When the thickness of each layer of the aluminum oxide layer 5 is within the above range, while enhancing the antireflection function of the inorganic plate 1 with a film in the deep ultraviolet region, it is possible to more reliably avoid a decrease in the ultraviolet transmittance due to an increase in the film thickness.

[0053] Note that the number of silicon oxide layers 4 in the antireflection film 3 is preferably 2 or more, more preferably 3 or more, 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 film 3 is within the above range, while enhancing the antireflection function of the inorganic plate 1 with a film in the deep ultraviolet region, it is possible to more reliably avoid a decrease in the ultraviolet transmittance due to an increase in the film thickness.

[0054] Note that the number of aluminum oxide layers 5 in the antireflection film 3 is preferably 1 or more, more preferably 2 or more, 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 film 3 is within the above range, while enhancing the antireflection function of the inorganic plate 1 with a film in the deep ultraviolet region, it is possible to more reliably avoid a decrease in the ultraviolet transmittance due to an increase in the film thickness.

[0055] Hereinafter, an example of a method for manufacturing the inorganic plate 1 with a film will be described.

[0056] (Method for manufacturing an inorganic plate with a film) In the method for manufacturing the inorganic plate 1 with a film, first, an inorganic plate 2 is prepared. Next, a silicon oxide layer 4 and an aluminum oxide layer 5 are alternately laminated on the first main surface 2a of the inorganic plate 2 to form an antireflection film 3. Thereby, the inorganic plate 1 with a film can be obtained.

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

[0058] In addition, sputtering methods and vacuum evaporation methods can use conventionally known methods. The substrate temperature during film formation is preferably 150°C or higher, more preferably 200°C or higher, and can preferably be 350°C or lower. In particular, when the substrate temperature during film formation of the silicon oxide layer 4 constituting the outermost layer 3a of the antireflection film 3 is within the above range, the adhesiveness when bonding the inorganic plate 1 with a film to another member using an adhesive can be further enhanced, and the airtightness within the package on which the optical element is mounted can be further enhanced.

[0059] In addition, the silicon oxide layer 4 and the aluminum oxide layer 5 are preferably formed by ion-assisted evaporation. By forming each layer by ion-assisted evaporation, the adhesiveness when bonding the inorganic plate 1 with a film to another member using an adhesive can be further enhanced, and the airtightness within the package on which the optical element is mounted can be further enhanced.

[0060] Among them, when forming the silicon oxide layer 4 constituting the outermost layer 3a of the antireflection film 3, it is preferable to increase the ion irradiation amount more than when forming the other layers constituting the antireflection film 3 and perform film formation of the silicon oxide layer 4 constituting the outermost layer 3a. In this case, sputtering particles or vapor deposition particles with high energy are driven into the already formed film surface, so the convex portions on the film surface are pushed into the film. Therefore, the silicon oxide layer 4 constituting the outermost layer 3a can be made smoother and denser. As a result, the adhesiveness when bonding the inorganic plate 1 with a film to another member using an adhesive can be further enhanced, and the airtightness within the package on which the optical element is mounted can be further enhanced. The film formation rate is preferably 3 Å / second or more and 8 Å / second or less when forming the silicon oxide layer 4, and preferably 3 Å / second or more and 8 Å / second or less when forming the aluminum oxide layer 5.

[0061] When forming the silicon oxide layer 4 that constitutes the outermost layer 3a of the antireflection film 3, the ion irradiation dose is preferably 1 time or more and 1.5 times or less the ion irradiation dose when forming the other layers that constitute the antireflection film 3. The ion irradiation dose when forming the silicon oxide layer 4 that constitutes the outermost layer 3a of the antireflection film 3 is, for example, 1 mA / cm 2 or more and 1.5 mA / cm 2 or less. Also, the ion irradiation time when forming the silicon oxide layer 4 that constitutes the outermost layer 3a of the antireflection film 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 an inorganic plate with a film according to an embodiment of the present invention.

[0063] As shown in FIG. 3, the package 11 includes an inorganic plate with a film 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 12a and a frame-shaped side wall portion 12b. The side wall portion 12b is provided on the bottom 12a. As the material of the case body 12, for example, ceramics such as aluminum nitride or glass ceramics can be used.

[0065] An inorganic plate with a film 1 as a cover member is provided on the upper surface 12c of the side wall portion 12b of the case body 12. The upper surface 12c of the side wall portion 12b and the inorganic plate with a film 1 are joined by a joining material 14, thereby sealing the inside of the package 11 in which the image sensor 13 is mounted. In the present embodiment, it is joined to the upper surface 12c of the side wall portion 12b via the joining material 14 from the antireflection film 3 side of the inorganic plate with a film 1.

[0066] The joining material 14 is not particularly limited, and for example, a resin adhesive or a solder film can be used. As the resin adhesive, a resin such as an ultraviolet curable adhesive can be used.

[0067] The image sensor 13 is disposed on the bottom 12a of the case body 12. In the present embodiment, the image sensor 13 as an imaging element is mounted on the package 11. However, the package 11 may be mounted with other optical elements such as a light emitting element like a deep ultraviolet LED, and is not particularly limited.

[0068] In the package 11 of the present embodiment, the above-described inorganic plate 1 with a film is used as the cover member. Therefore, the airtightness inside the package 11 can be enhanced. Further, since the inorganic plate 1 with a film is excellent in ultraviolet transmittance, in the package 11 of the present embodiment, ultraviolet rays can be efficiently incident on the image sensor 13.

[0069] In the present embodiment, the inorganic plate 1 with a film is used as the cover member of the package 11. However, the inorganic plate 1 with a film may be directly bonded to the image sensor 13 via the bonding material 14. Even in that case, by bonding the inorganic plate 1 with a film to the image sensor 13 via the bonding material 14 from the antireflection film 3 side of the inorganic plate 1 with a film, the inorganic plate 1 with a film and the image sensor 13 can be reliably bonded. Further, ultraviolet rays can be efficiently incident on the image sensor 13 through the inorganic plate 1 with a film.

[0070] Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the following examples, and can be appropriately modified and implemented without changing the gist thereof.

[0071] (Example 1) First, a quartz glass plate (manufactured by SHANGHAI WECHANCE INDUSTRIA, product number "JGS01", thickness: 0.5 mm) was prepared as the inorganic plate. Next, a silicon oxide (SiO 2 ) layer and an aluminum oxide (Al 2 O 3 ) layer were formed on the first main surface of the inorganic plate by ion assist evaporation. More specifically, the substrate temperature was set to 200°C, O 2 gas was used as the carrier gas, and SiO placed in the hearth liner2 The film material was irradiated with hot electrons and heated, and the film formation rate was set to 0.5 nm / sec. A SiO 2 layer was formed on one main surface of the inorganic plate. Next, using O 2 gas as the carrier gas, Al 2 O 3 The film material was irradiated with hot electrons and heated, and the film formation rate was set to 5 nm / sec. An Al 2 O 3 layer was formed on one main surface of the inorganic plate. In this way, on one main surface of the inorganic plate, SiO 2 layers and Al 2 O 3 layers were alternately laminated to a total of 5 layers to obtain an antireflection film. Thereby, an inorganic plate with a film was obtained. When forming the outermost SiO 2 layer, ion irradiation was performed for 125 seconds (time) with an ion irradiation amount of 1.1 mA / cm 2 . When forming the SiO 2 layers other than the outermost layer, ion irradiation was performed for 125 seconds (time) with an ion irradiation amount of 0.8 mA / cm 2 . Also, 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 layer / total thickness of the aluminum oxide layer) was 17.6.

[0072] (Example 2) An antireflection film was obtained by alternately laminating SiO 2 layers and Al 2 O 3 layers to a total of 9 layers on one main surface of the inorganic plate, and an inorganic plate with a film was obtained in the same manner as in Example 1 except that the thickness of each layer constituting the antireflection film was changed as shown in Table 1 below. In Example 2, the thickness ratio of the silicon oxide layer to the aluminum oxide layer (total thickness of the silicon oxide layer / total thickness of the aluminum oxide layer) was 13.2.

[0073]

Table 1

[0074] (Example 3) When forming the outermost SiO 2 layer, except that the ion irradiation dose was 0.8 mA / cm 2 and the ion irradiation was performed for 142 seconds (hours), an inorganic plate with a film was obtained in the same manner as in Example 1.

[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 inorganic plates with films 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, after dropping 5 mg of pure water onto each horizontally placed inorganic plate with a film, the water droplet was photographed from directly above with a measurement microscope (manufactured by Nikon Corporation), and the contact angle θ was obtained 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 inorganic plate of Example 1 was 2.7°, in Example 2, the contact angle θ was 3.5°, and in Example 3, the contact angle was 3.9°. As a reference example, in the magnesium fluoride (MgF 2 ) film, the contact angle θ was 7.5°.

[0078] (Evaluation of Light Transmittance) The light transmittance of the inorganic plates with films of Example 1 and Example 2 was measured using a spectrophotometer (manufactured by Hitachi High-Tech Corporation, product number "U-4150"). Figure 4 shows the light transmission spectra in the wavelength range of 190 nm to 790 nm of the inorganic plates with films obtained in Example 1 and Example 2. In Figure 4, the light transmission spectrum of a quartz glass plate is shown as a reference example.

[0079] As shown in Figure 4, it was confirmed that the inorganic plates with films of Example 1 and Example 2 have high ultraviolet transmittance particularly in the deep ultraviolet region.

[0080] From the above, in the inorganic plates with films of Example 1 and Example 2, while having high ultraviolet transmittance in the deep ultraviolet region, compared with the magnesium fluoride (MgF 2 ) film, it was confirmed that the contact angle with pure water is small, so that the airtightness in the package mounting the optical element can be enhanced.

Explanation of Symbols

[0081] 1, 1A... Inorganic plates with films 2... Inorganic plate 2a... First main surface 2b... Second main surface 3a... Outermost layer 3b... Surface 3... Antireflection film 4... Silicon oxide layer 5... Aluminum oxide layer 11... Package 12... Case body 12a... Bottom 12b... Side wall part 12c... Upper surface 13... Image sensor 14... Bonding material

Claims

1. An inorganic plate having ultraviolet transmittance, and an antireflection film provided on one main surface of the inorganic plate, comprising: the antireflection film is configured by alternately laminating a silicon oxide layer and an aluminum oxide layer, the outermost layer of the antireflection film is provided with the silicon oxide layer, an inorganic plate with a film, wherein the thickness ratio of the silicon oxide layer to the aluminum oxide layer (silicon oxide layer / aluminum oxide layer) in the antireflection film is 5 or more.

2. The inorganic plate with a film according to claim 1, wherein the thickness of the silicon oxide layer is 10 nm or more and 100 nm or less, and the thickness of the aluminum oxide layer is 2 nm or more and 10 nm or less.

3. The inorganic plate with a film according to claim 1 or 2, wherein the number of layers of the silicon oxide layer in the antireflection film is 2 or more and 5 or less, and the number of layers of the aluminum oxide layer in the antireflection film is 1 or more and 4 or less.

4. The inorganic plate with a film according to claim 1 or 2, wherein the inorganic plate is made of quartz glass.

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

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

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

8. A method for manufacturing an inorganic plate with a film according to claim 1 or 2, comprising: a step of preparing an inorganic plate, and a step of alternately laminating a silicon oxide layer and an aluminum oxide layer on one main surface of the inorganic plate by an ion assist deposition method to form an antireflection film. A method for manufacturing an inorganic plate with a film, comprising:

9. The method for manufacturing an inorganic plate with a film according to claim 8, wherein when forming the silicon oxide layer that becomes the outermost layer of the antireflection film, the ion irradiation amount is increased compared to the case of forming other layers constituting the antireflection film to form the silicon oxide layer.

10. A case body having a bottom portion and a side wall portion, an optical element provided on the bottom portion of the case body, a cover member provided on the side wall portion of the case body, comprising a package, wherein the cover member is the inorganic plate with a film according to claim 1 or 2. A package in which the antireflection film on the inorganic plate with a film is joined to the upper surface of the side wall portion in the case body via a bonding material, and the inside of the package in which the optical element is housed is sealed.

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