JPWO2020175320A1 - Manufacturing method of optical filter, carrier support for optical filter, and optical filter - Google Patents

Abstract

A first optical multilayer film obtained by laminating a substrate and dielectric thin films having different refractive indexes provided on one main surface of the substrate, and a magnesium fluoride film provided on the surface of the first optical multilayer film. The magnesium fluoride film comprises an optical filter having an oxide layer containing a magnesium component on at least a part of the outermost surface on the air side.

Description

The present invention relates to an optical filter and a method for manufacturing the optical filter. Further, the present invention relates to a transport support for an optical filter.

Solid-state image sensors such as CCD (Chemical Coupled Device) image sensors and CMOS (Complementary Metal Oxide Semiconductor) image sensors have stronger sensitivity to infrared light than human visual sensitivity characteristics.

Therefore, for example, in a digital camera, a digital video, or the like, spectroscopic correction is performed by using an optical filter such as a near-infrared cut filter.

In recent years, with the thinning of image pickup devices mounted on mobile phones and smartphones, the distance between the optical filter used in the image pickup device and the image pickup element tends to be shortened. Further, with the progress of high definition of cameras, the size of one pixel of the image sensor tends to be reduced.

As a result, the demand for foreign matter existing on the surface of the optical filter becomes very strict. Specifically, a small-sized foreign substance, which has not been questioned in the past, becomes a problem.

Conventionally, as a technique for suppressing the adsorption of dust on the surface of an optical filter, indium tin oxide (ITO: Indium Tin Oxide) is vapor-deposited on the final layer of the optical multilayer film to form a conductive film on the surface of the optical multilayer filter. A method for removing charge is known (Patent Document 1).

Japanese Patent Application Laid-Open No. 2007-298951

Forming ITO on the surface is an effective means for removing the charge of the optical filter. However, it is very troublesome because it is necessary to ground the ITO to remove the charge of the filter during the manufacturing process where there is a concern about the adhesion of dust or immediately before the manufacturing process. Furthermore, the present inventors have confirmed that dust once adhering to the surface of ITO has a strong adhesive force with ITO and cannot be easily removed regardless of the state of charge.

For example, in the manufacturing process of an optical filter, a cleaning step is performed to remove dust on the surface of the filter, but dust adhering to ITO may not be sufficiently removed. In particular, since the mass of minute foreign matter is small, vibration such as ultrasonic cleaning is difficult to act on, and if it adheres to the filter surface, it is considered difficult to remove it.

The present invention has been made in view of such a background, and an object of the present invention is to provide a clean optical filter in which minute foreign matters and the like are less likely to adhere to the surface of the optical filter.

The optical filter of the embodiment of the present invention has a substrate, a first optical multilayer film in which dielectric thin films having different refractive indexes are laminated on one main surface of the substrate, and a surface of the first optical multilayer film. The magnesium fluoride film is provided in the above, and the magnesium fluoride film has an oxide layer containing a magnesium component on at least a part of the outermost surface on the air side.

In the optical filter of another embodiment of the present invention, the surface roughness (Ra) of the main surface of the optical filter on the side provided with the magnesium fluoride film is 0.3 nm to 2.4 nm.

In the optical filter of another embodiment of the present invention, the main surface of the optical filter on the side provided with the magnesium fluoride film has a contact angle of 5 ° to 80 ° with respect to pure water.

In the optical filter of another embodiment of the present invention, the substrate includes a near-infrared absorbing layer containing a transparent resin and an infrared absorbing dye on the other main surface.

In the optical filter of another embodiment of the present invention, a second optical multilayer film is provided on the surface of the near-infrared absorbing layer.

In the optical filter of another embodiment of the present invention, the substrate is glass or resin.

The optical filter of another embodiment of the present invention is a near-infrared cut filter that cuts light having a wavelength in the near-infrared region.

Further, the transport support of the optical filter according to the embodiment of the present invention includes a plurality of the optical filters, and both main surfaces of the optical filters are sandwiched by protective sheets.

Further, the method for manufacturing an optical filter according to the embodiment of the present invention includes a step of preparing a substrate, a step of forming a first optical multilayer film on one main surface of the substrate, and a first optical formed. It includes at least a step of forming a magnesium fluoride film on the surface of the multilayer film and a step of cutting the substrate on which the magnesium fluoride film is formed into individual pieces.

In the method for manufacturing an optical filter according to another embodiment of the present invention, the step of cutting the substrate on which the magnesium fluoride film is formed into individual pieces is performed inside the substrate by using a laser along the planned cutting line of the substrate. It includes a step of forming a modified layer and a step of extending cracks from the modified layer by applying stress to the substrate and cutting the substrate.

In the method for manufacturing an optical filter according to another embodiment of the present invention, the step of cutting the substrate on which the magnesium fluoride film is formed into individual pieces is performed by using a rotary blade along the planned cutting line of the substrate. Including the step of cutting.

In the method for manufacturing an optical filter according to another embodiment of the present invention, a transparent resin and infrared rays are absorbed on the other main surface of the substrate before the step of cutting the substrate on which the magnesium fluoride film is formed into individual pieces. It includes a step of forming a near-infrared absorbing layer containing a dye and a step of forming a second optical multilayer film on the surface of the near-infrared absorbing layer.

In the method for manufacturing an optical filter according to another embodiment of the present invention, before or after the step of cutting the substrate on which the magnesium fluoride film is formed into individual pieces, the outermost surface of the magnesium fluoride film on the air side. A step of forming an oxide layer containing a magnesium component at least in part thereof is provided.

INDUSTRIAL APPLICABILITY According to the present invention, a clean optical filter with less adhesion of minute foreign matter or the like to the surface of the optical filter is provided.

It is sectional drawing which shows typically the structure of the optical filter which concerns on 1st Embodiment of this invention. It is sectional drawing which shows typically the structure of the optical filter which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows typically the structure of the optical filter which concerns on 3rd Embodiment of this invention. It is a top view schematically showing the structure of the transport support of the optical filter of the embodiment of this invention. It is a partial cross-sectional view schematically showing the structure of the transport support of the optical filter of the embodiment of this invention. It is explanatory drawing which shows that the foreign matter is removed by peeling off the protective sheet in the transport support of the optical filter of embodiment of this invention.

Hereinafter, the optical filter of the embodiment of the present invention will be described in detail with reference to the embodiment. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and carried out without departing from the gist of the present invention. Further, "~" indicating a numerical range is used in the sense that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.

[First Embodiment]
The optical filter 10 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view schematically showing the configuration of the optical filter 10. The optical filter 10 is a flat plate and is used in any shape such as a rectangle, a circle, and a polygon in a plan view.

The optical filter 10 is provided on the surfaces of the substrate 1, the first optical multilayer film 2 provided on one main surface of the substrate 1 and laminated with dielectric thin films having different refractive indexes, and the first optical multilayer film 2. The magnesium fluoride film 3 provided is provided, and the magnesium fluoride film 3 has an oxide layer 4 containing a magnesium component on at least a part of the outermost surface on the air side.

The substrate 1 is a substrate that supports the first optical multilayer film 2 and the magnesium fluoride film 3. Therefore, in order to suppress warping and breakage of the optical filter due to the internal stress of these films, it is preferable to have a rigidity of a certain level or higher. As the material of the substrate 1, glass or resin can be preferably used.

From the viewpoint of reducing the thickness of the optical filter 10, the thickness of the substrate 1 is preferably 3 mm or less, more preferably 2 mm or less, further preferably 1 mm or less, and most preferably 0.5 mm or less. Further, the thickness of the substrate is preferably 0.05 mm or more, more preferably 0.1 mm or more, still more preferably 0.12 mm or more, from the viewpoint of suppressing the processing cost and suppressing the decrease in strength.

When glass is used as the substrate 1, known glass can be selected depending on the use of the optical filter.

For example, in applications where a large amount of visible light is required to be transmitted, white plate glass containing a small amount of impurities such as iron that absorbs visible light is preferably used. Further, in applications where it is required to block near-infrared light as a visual sensitivity correction filter of an image pickup apparatus, near-infrared absorbing glass containing copper or iron that absorbs near-infrared light is preferably used.

Examples of the glass composition include known glasses such as borosilicate glass, soda lime glass, non-alkali glass, aluminosilicate glass, phosphoric acid glass, and futhuric acid glass.

When a resin is used as the substrate 1, a known resin can be selected depending on the use of the optical filter.

For example, in applications where it is required to transmit visible light, the transparent resin includes acrylic resin, epoxy resin, en-thiol resin, polycarbonate resin, polyether resin, polyarylate resin, polysulfone resin, polyethersulfone resin, and poly. Examples thereof include paraphenylene resin, polyester resin, polyimide resin, polyamideimide resin, polyolefin resin, and cyclic olefin resin.

In particular, as the resin having a high glass transition temperature (Tg), one or more selected from polyester resin, polycarbonate resin, polyether sulfone resin, polyarylate resin, polyimide resin, and epoxy resin is preferable.

Further, as the resin to be a transparent substrate, one or more selected from polyester resin and polyimide resin is more preferable, and polyimide resin is particularly preferable. As the polyester resin, polyethylene terephthalate resin, polyethylene naphthalate resin and the like are preferable.

In applications where it is required to shield near-infrared light as a visual sensitivity correction filter of an image pickup apparatus, the transparent resin may contain an infrared light absorbing dye. Infrared absorbing dyes include known compounds such as cyanine-based, pyrylium-based, squarylium-based, croconium-based, azulenium-based, phthalocyanine-based, dithiol metal complex, nahitoquinone-based, anto-aquinone-based, indophenol-based, and azi-based, and copper ions. And metal ions such as neodymium ion, praseodymium ion, erbium ion, and holmium ion.

Further, the transparent resin may contain a known ultraviolet absorbing dye together with the infrared absorbing dye.

The first optical multilayer film 2 is a layer in which dielectric thin films having different refractive indexes provided on one main surface of the substrate 1 are laminated, and has predetermined optical characteristics depending on the application of the optical filter. ..

The first optical multilayer film 2 is configured as a dielectric thin film having a different refractive index, for example, a high refractive index film and a low refractive index film having a lower refractive index than the high refractive index film are alternately laminated. Will be done.

As the high refractive index film, for example, at least one metal oxide film selected from _{ZrO 2} , Nb ₂ O ₅ , Al ₂ O ₃ , TIO ₂ , and Ta ₂ O _{5 is used.}

As the low refractive index film, for example, SiO ₂ or the like is used. The film thickness and the number of layers of the high-refractive index film and the low-refractive index film are appropriately set according to the optical characteristics required for the first optical multilayer film 2.

As the first optical multilayer film 2, three or more kinds of dielectric thin films having different refractive indexes may be used.

The first optical multilayer film 2 can reflect and transmit light having a specific wavelength due to the interference action of light. For example, an antireflection film that suppresses the reflection of visible light, an infrared shielding film that reflects near-infrared light, an ultraviolet shielding film that reflects ultraviolet light, an ultraviolet and infrared shielding film that reflects ultraviolet light and near-infrared light, and the like. be.

The first optical multilayer film 2 is formed on the main surface of the substrate 1 by using, for example, a sputtering method or an ion-assisted vapor deposition method.

The film formed by the sputtering method or the ion-assisted vapor deposition method has a very small change in the spectral characteristics under high temperature and high humidity as compared with the film formed by the vapor deposition method without ion assist, and is substantially spectroscopic. There is an advantage that it is possible to realize a non-shift film without change. Further, since the films formed by these methods are dense and have high hardness, they are not easily scratched and are excellent in handleability in the component assembly process and the like.

Further, the first optical multilayer film 2 may be formed by a vacuum vapor deposition method that does not use ion assist. When this vapor deposition method is used, the equipment cost is low and the manufacturing cost can be suppressed. Further, when forming the first optical multilayer film 2, it is possible to obtain a film to which foreign matter and the like are less likely to adhere. That is, the method for forming the first optical multilayer film 2 is not limited to the sputtering method, the ion-assisted vapor deposition method, or the like, and may be arbitrary.

The magnesium fluoride film 3 is provided on the surface of the first optical multilayer film 2. The magnesium fluoride film 3 is an inorganic fluorine compound, and is a configuration that serves as a base for an oxide layer containing a magnesium component, which will be described later. Further, the magnesium fluoride film 3 has high antifouling property and dustproof property, and has an effect of making it difficult for foreign matter such as dust to adhere to the surface of the optical filter.

The magnesium fluoride film 3 is formed, for example, by a vacuum heating vapor deposition method that does not use ion assist. When this vapor deposition method is used, the equipment cost is low and the manufacturing cost of the optical filter can be suppressed. Further, the method for forming the magnesium fluoride film 3 is not limited to the vacuum heating vapor deposition method, and may be arbitrary, such as a sputtering method or an ion-assisted vapor deposition method.

From the viewpoint of dust resistance of the optical filter, the film thickness of the magnesium fluoride film 3 is preferably 1.0 μm or less, more preferably 0.5 μm or less. Further, from the viewpoint of suppressing the processing cost, the film thickness of the magnesium fluoride film 3 is preferably 10 nm or more, more preferably 30 nm or more.

The oxide layer 4 containing a magnesium component (hereinafter, also referred to as an oxide layer) is present on at least a part of the outermost surface of the magnesium fluoride film 3 described above on the air side. The oxide layer 4 is formed by reacting the magnesium component of the magnesium fluoride film 3 with oxygen in the atmosphere.

Examples of the substance include magnesium oxide (MgO), magnesium hydroxide (Mg (OH) ₂ ), magnesium carbonate (MgCO ₃ ), magnesium hydrogencarbonate (Mg (HCO ₃ ) ₂ ), and a film material for the optical multilayer film 2. It is a concept including a composite oxide film (MO—Mg) of M and a magnesium fluoride film 3.

These oxide layers 4 are highly deliquescent. Further, the oxide layer 4 exists on the surface as a substance different from the magnesium fluoride film 3. Therefore, when foreign matter adheres to the oxide layer 4 on the surface of the optical filter, it is considered that the oxide layer 4 is easily separated from the magnesium fluoride film 3 together with the foreign matter due to external force such as vibration during cleaning and peeling of the adhesive sheet. Be done. Therefore, foreign matter on the surface of the optical filter can be reliably removed by cleaning or the like.

The oxide layer 4 may be present on at least a part of the outermost surface of the magnesium fluoride film 3 on the air side, and may be present on the entire surface of the outermost surface. The oxide layer 4 should not be present at the interface between the magnesium fluoride film 3 and the first optical multilayer film 2. As described above, since the oxide layer 4 has high deliquescent property, there is a possibility that the adhesion between the magnesium fluoride film 3 and the first optical multilayer film 2 may be lowered.

The method for forming the oxide layer 4 is, for example, to promote the reaction between the magnesium component of the magnesium fluoride film 3 and oxygen in the atmosphere by holding the substrate in a high temperature state after forming the magnesium fluoride film 3. do. If the oxide layer 4 is formed, not only this forming method but also an appropriate method such as a method of simultaneous treatment with other manufacturing steps or a cleaning step can be used.

The main surface of the optical filter 10 on the side provided with the magnesium fluoride film 3 preferably has a surface roughness (Ra) of 0.3 nm to 2.4 nm. The surface roughness in the present invention refers to the center line average roughness Ra defined by JIS B0601: 2001. Further, the main surface of the optical filter 10 on the side provided with the magnesium fluoride film 3 refers to the surface of the optical filter including the oxide layer 4.

When the surface roughness of the main surface of the optical filter 10 on the side provided with the magnesium fluoride film 3 is within the above range, foreign matter adhering to the optical filter 10 can be easily removed, which is preferable. Since the range of the surface roughness is larger than the general surface roughness of the optical filter, the contact area between the foreign matter and the optical filter 10 is small, and due to the synergistic effect of the oxide layer 4 described above, the foreign matter is removed from the surface of the optical filter. It is considered that it is easy to detach.

When the range of the surface roughness is 0.3 nm or more, the contact area between the foreign matter and the optical filter 10 does not increase, and it is possible to prevent the foreign matter from becoming difficult to remove. Further, when the range of the surface roughness is 2.4 nm or less, the haze value of the optical filter 10 does not increase, and it is possible to prevent the optical characteristics from deteriorating.

The range of the surface roughness is preferably 0.3 nm or more, and more preferably 0.7 nm or more. Further, the range of the surface roughness is preferably 2.4 nm or less, more preferably 1.1 nm or less.

The main surface of the optical filter 10 on the side provided with the magnesium fluoride film 3 preferably has a contact angle of 5 ° to 80 ° with respect to pure water. The contact angle in the present invention means a contact angle obtained by using the measuring method specified in JIS R3257: 1999. Further, the main surface of the optical filter 10 on the side provided with the magnesium fluoride film 3 refers to the surface of the optical filter including the oxide layer 4.

When the contact angle with respect to pure water is within the above range, the main surface of the optical filter 10 on the side provided with the magnesium fluoride film 3 is preferable because foreign matter adhering to the optical filter 10 can be easily removed.

Conventionally, since the magnesium fluoride film 3 is an inorganic fluorine compound, it has been considered to have water repellency and contribute to suppressing the adhesion of foreign substances. However, as a result of measurement by the present inventor, it has been found that the main surface of the optical filter 10 having the oxide layer 4 on the magnesium fluoride film 3 does not necessarily show water repellency, but rather is hydrophilic. .. Furthermore, it has been found that the hydrophilicity of the main surface of the optical filter 10 contributes to the ease of removing foreign matter adhering to the optical filter 10.

The following can be considered as a hypothesis as the reason for this.

Although the magnesium fluoride film 3 is water-repellent as a substance, the surface free energy becomes large due to the uneven shape of the surface, and a thin water film is formed by taking in moisture in the air. As a result, it is presumed that the magnesium fluoride membrane 3 is apparently hydrophilic. When a foreign substance adheres to the water film, it is integrated by the intramolecular force between the water film and the foreign substance, so that it can be easily removed from the magnesium fluoride film 3 by an external force such as vibration.

The main surface of the optical filter 10 on the side provided with the magnesium fluoride film 3 does not become very difficult to manufacture when the contact angle with respect to pure water is 5 ° or more. Further, when the contact angle with respect to pure water is 80 ° or less, it is possible to prevent the surface of the optical filter from becoming water repellent and prevent it from becoming difficult to remove foreign matter adhering to the optical filter 10.

The contact angle with respect to the pure water is preferably 5 ° to 80 °, more preferably 5 ° to 50 °, and even more preferably 5 ° to 20 °.

The optical filter 10 according to the first embodiment of the present invention has each of the above-described configurations, and in particular, the oxide layer 4 containing a magnesium component is formed on at least a part of the outermost surface of the magnesium fluoride film 3 on the air side. By having it, it is easy to remove foreign matter adhering to the surface of the optical filter.

The situation where foreign matter adheres to the surface of the optical filter is not limited to the manufacturing process of the optical filter 10, but also various steps such as a transfer process, an assembly process to an image pickup device, and a use of the image pickup device. The optical filter of the first embodiment has a feature that foreign matter can be easily removed.

[Second Embodiment]
The optical filter 20 according to the second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view schematically showing the configuration of the optical filter 20.

The optical filter 20 is provided on the surfaces of the substrate 1, the first optical multilayer film 2 provided on one main surface of the substrate 1 and laminated with dielectric thin films having different refractive indexes, and the first optical multilayer film 2. The magnesium fluoride film 3 provided is provided, and the oxide layer 4 containing a magnesium component is provided on at least a part of the outermost surface of the magnesium fluoride film 3 on the air side.

Further, on the other main surface of the substrate 1, the first optical multilayer film 2 and the magnesium fluoride film 3 provided on the surface of the first optical multilayer film 2 are formed on the other main surface as well as on the one main surface. The oxide layer 4 containing a magnesium component is provided on at least a part of the outermost surface of the magnesium fluoride film 3 on the air side.

That is, in the optical filter 20 according to the second embodiment, substantially the same configuration is laminated on both main surfaces.

In the second embodiment, the same parts or similar parts as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.

Since the optical filter 20 is provided with an oxide layer 4 containing a magnesium component on the outermost surfaces on the air side of both main surfaces, it is easy to remove foreign substances on both main surfaces, and a clean optical filter can be provided. For example, when the optical filter 20 is used in the image pickup apparatus, it can be suitably used in a system for removing foreign substances in the optical filter by ultrasonic vibration.

In the optical filter 20, the first optical multilayer film 2 on one main surface and the first optical multilayer film 2 on the other main surface have the same optical characteristics but different optical characteristics. It is also good. When the optical characteristics are different, for example, the first optical multilayer film 2 on one main surface is a near-infrared cut filter that cuts wavelengths in the near-infrared region, and the first optical multilayer film 2 on the other main surface. The optical multilayer film 2 is an antireflection film for visible light.

In addition, near-infrared cut filters having different blocking bands in the near-infrared wavelength region may be provided as the first optical multilayer film on both main surfaces.

[Third Embodiment]
The optical filter 30 according to the third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view schematically showing the configuration of the optical filter 30.

The optical filter 30 is provided on the surfaces of the substrate 1, the first optical multilayer film 2 provided on one main surface of the substrate 1 and laminated with dielectric thin films having different refractive indexes, and the first optical multilayer film 2. The magnesium fluoride film 3 provided is provided, and the magnesium fluoride film 3 has an oxide layer 4 containing a magnesium component on at least a part of the outermost surface on the air side.

Further, a near-infrared absorbing layer 5 containing a transparent resin and an infrared absorbing dye is provided on the other main surface of the substrate 1, and a second optical multilayer film 6 is provided on the surface of the near-infrared absorbing layer 5.

In the third embodiment, the same parts or similar parts as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.

Since the optical filter 30 is provided with an oxide layer 4 containing a magnesium component on the outermost surface of one of the main surfaces on the air side, foreign matter on the surface of the optical filter can be easily removed, and a clean optical filter can be provided.

Further, since the near-infrared absorbing layer 5 is provided on the other main surface of the optical filter 30, the ability to shield the near-infrared light is high, and the change in optical characteristics is small even if the incident angle of the light changes.

A known resin can be used as the transparent resin of the optical filter 30. Specific examples thereof include various resins described when the resin is used as the substrate.

Further, as the infrared absorbing dye of the optical filter 30, a known infrared absorbing dye can be used. Specific examples thereof include various infrared absorbing dyes described when the resin is used as the substrate. In addition, a known ultraviolet absorbing dye may be contained together with the infrared absorbing dye.

The near-infrared absorbing layer 5 is formed by mixing a transparent resin and an infrared absorbing dye and using a known method (for example, coating, dipping, etc.) on the other main surface of the substrate.

A second optical multilayer film 6 may be provided on the surface of the near-infrared absorbing layer 5. The second optical multilayer film 6 is formed by laminating dielectric thin films having different refractive indexes, similarly to the first optical multilayer film 2. Further, as the second optical multilayer film 6, the film material described in the first optical multilayer film 2 can be used, and the same forming method can be used.

The second optical multilayer film 6 can reflect and transmit light having a specific wavelength due to the interference action of light. For example, an antireflection film that suppresses the reflection of visible light, an infrared shielding film that reflects near-infrared light, an ultraviolet shielding film that reflects ultraviolet light, an ultraviolet and infrared shielding film that reflects ultraviolet light and near-infrared light, and the like. be.

By providing the second optical multilayer film 6, the optical characteristics of the optical filter 30 can be further enhanced. Specifically, by using a near-infrared cut filter that cuts wavelengths in the near-infrared region as the second optical multilayer film 6, the transmittance of near-infrared light as the optical filter 30 can be reduced. Further, by using an antireflection film for visible light as the second optical multilayer film 6, the transmittance of visible light of the optical filter 30 can be increased.

The optical filter of the third embodiment of the present invention can be suitably used as a filter that selectively transmits and reflects light in an image pickup device, an infrared sensor, a lighting device, and the like. Specifically, a visible light antireflection filter, an infrared cut filter, an infrared transmission filter, an ultraviolet cut filter, an ultraviolet transmission filter, a dual band pass filter (a filter that transmits a part of visible light and near infrared light), etc. However, it is not limited to these.

[Carrying support for optical filter]
The transport support 100 of the optical filter according to the embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a plan view schematically showing the configuration of the transport support 100 of the optical filter. FIG. 5 is a partial cross-sectional view schematically showing the configuration of the transport support 100 of the optical filter.

4 and 5 use the optical filter 20 according to the second embodiment as the optical filter, but the applicable optical filter is not limited to this and does not deviate from the gist of the present invention. It is possible to use a range of optical filters.

The transport support 100 of the optical filter according to the embodiment of the present invention includes a plurality of optical filters, and both main surfaces of the optical filter are sandwiched by the protective sheet 8.
The optical filter has been described as an embodiment of the present invention, and duplicate description will be omitted.

In the transport support 100 of the optical filter, a plurality of optical filters 20 are sandwiched between the two protective sheets 8.

The protective sheet 8 is for suppressing scratches and foreign matter from being scratched on both main surfaces of the optical filter 20 when the optical filter 20 is transported to a process of assembling the optical filter 20 to an image pickup device or the like. Since the surface of the protective sheet 8 in contact with the optical filter 20 is adhesive, the optical filter 20 is fixed to the protective sheet 8 during transportation.

As shown in FIG. 6, foreign matter adhering to the surface of the optical filter is removed by sticking to the adhesive surface of the protective sheet 8 when the protective sheet 8 is peeled from the optical filter 20. As described above, the optical filter 20 is provided with an oxide layer 4 containing a magnesium component on the outermost surface on the air side of the main surface, so that foreign matter on the main surface is easily removed. Therefore, foreign matter can be reliably removed by using the protective sheet 8.

Thereby, by using the transport support 100 of the optical filter, the optical filter 20 with less adhesion of foreign matter can be transported to the next step.

The periphery of the protective sheet 8 may or may not be fixed to the frame 7. As the frame 7, for example, a disk-shaped metal plate or a resin plate can be used, but the frame 7 is not limited to this.

Further, the transport support 100 of the optical filter may be transported using a box capable of accommodating a plurality of transport supports 100.

Next, a method of manufacturing an optical filter will be described.

The optical filter of the embodiment of the present invention can be manufactured, for example, by the following steps. That is, a step of preparing the substrate 1, a step of forming the first optical multilayer film 2 on one main surface of the substrate 1, and a magnesium fluoride film 3 on the surface of the formed first optical multilayer film 2. A step of forming the substrate 1 and a step of cutting the substrate 1 on which the magnesium fluoride film 3 is formed into individual pieces are provided at least.

By manufacturing an optical filter in such a process, even if glass fragments or the like are generated when the substrate 1 is cut, since the magnesium fluoride film 3 is present on the surface of the substrate 1, the glass fragments can be easily removed by cleaning or the like. It can provide a clean optical filter.

In the process of preparing the substrate 1, the substrate 1 to be processed is prepared. The substrate 1 has one main surface facing each other and the other main surface.

The step of forming the first optical multilayer film 2 on one main surface of the substrate 1 is formed by the method described above.

The step of forming the magnesium fluoride film 3 on the surface of the first optical multilayer film 2 is formed by the method described above.

A known method can be used in the step of cutting the substrate 1 on which the magnesium fluoride film 3 is formed into individual pieces. For example, it is preferable to use the following cutting method.

That is, the steps of cutting the substrate 1 into individual pieces include a step of forming a modified layer inside the substrate using a laser along the planned cutting line of the substrate and a step of applying stress to the substrate to apply the modified layer. A method including a step of extending a crack from the glass and cutting the substrate can be mentioned.

By using this cutting method, it is possible to cut without forming a crack in the ridgeline of the cut portion of the substrate 1. Therefore, it is possible to obtain an optical filter having high mechanical strength when bending stress is applied to the substrate 1 and high cleanliness of the main surface.

Further, the step of cutting the substrate 1 into individual pieces may be a step of cutting the substrate using a rotary blade along the planned cutting line of the substrate.

By using this cutting method, the substrate 1 can be cut efficiently. Further, by using a combination of a V-shaped cross-section dicing blade and a cutting dicing blade as the rotary blade, an inclined surface can be efficiently formed on the ridgeline of the substrate 1.

Further, a step of forming an oxide layer 4 containing a magnesium component on at least a part of the outermost surface of the magnesium fluoride film 3 on the air side may be provided before or after the step of cutting the substrate 1 into individual pieces.

As a step of forming the oxide layer 4 containing a magnesium component on at least a part of the outermost surface of the magnesium fluoride film 3 on the air side, for example, the substrate 1 on which the magnesium fluoride film 3 is formed is kept at a high temperature.

As a result, the reaction between the magnesium component of the magnesium fluoride film 3 and oxygen in the atmosphere is promoted to form the oxide layer 4. If the oxide layer 4 is formed, not only this forming method but also an appropriate method such as a method of simultaneous treatment with other manufacturing steps or a cleaning step can be used.

The step of forming the oxide layer 4 containing the magnesium component may be either before or after the step of cutting the substrate 1 into individual pieces.

If the step of forming the oxide layer 4 is provided before the step of cutting the substrate 1 into individual pieces, even if the cutting debris generated at the time of cutting the substrate 1 adheres to the substrate, it can be easily removed. ..

Further, if the step of forming the oxide layer 4 is provided after the step of cutting the substrate 1 into individual pieces, it is possible to easily remove foreign substances from the surface of the optical filter when the optical filter is conveyed or used.

Further, the optical filter includes a step of forming a near-infrared absorbing layer 5 containing a transparent resin and an infrared absorbing dye on the other main surface of the substrate 1, and a second optical multilayer film 6 on the surface of the near-infrared absorbing layer 5. May be provided with a step of forming. These steps are preferably performed before the step of cutting the substrate 1 into individual pieces.

By providing this step, the near-infrared absorbing layer 5 that absorbs light in a specific wavelength range can be efficiently formed in the optical filter.

A method of manufacturing a transport support for an optical filter will be described.

The transport support 100 of the optical filter of the present invention is not particularly limited, but can be manufactured, for example, by the following steps.

The optical filter is prepared by the manufacturing method described above. Then, a plurality of optical filters are placed on the protective sheet 8. Next, by covering the main surface of the optical filter with another protective sheet 8, both main surfaces of the optical filter are sandwiched between the two protective sheets 8.

Since the oxide layer 4 is present on one main surface of the optical filter, foreign matter on the surface of the optical filter can be separated together with the protective sheet 8 when the protective sheet 8 is peeled off from the optical filter.

Hereinafter, the present invention will be described in detail based on the examples of the present invention, but the present invention is not limited to these examples.

Examples 1, 2, and 3 are optical filters according to an embodiment of the present invention, and Example 4 is an optical filter according to a comparative example. The materials and manufacturing conditions of each of the optical filters of Examples 1, 2 and 3 are the same. The samples used in each example were prepared as follows.

As the optical filter according to the embodiment, copper-containing borosilicate glass (NF-50, manufactured by AGC Technoglass Co., Ltd., plate thickness: 0.2 mm) was prepared as a substrate. Next, an optical multilayer film ( _{near-infrared cut filter in which a total of 50 layers of TiO 2} and SiO ₂ are alternately laminated on one main surface of the substrate, physical film thickness: about 5 μm) is applied by an ion-assisted vapor deposition method. Formed. Next, a magnesium fluoride film (physical film thickness: 90 nm) was formed on the surface of the optical multilayer film by a heat vapor deposition method. Next, an oxide layer containing a magnesium component was formed on the outermost surface of the magnesium fluoride film on the substrate on the air side.

In the optical filter of the example, it can be confirmed by the following method that an oxide layer containing a magnesium component is formed on the outermost surface of the magnesium fluoride film on the substrate on the air side.
A method of analyzing the composition of the surface of an optical filter using an XPS (X-ray photoelectron spectroscopy) wide spectrum can be mentioned. This will be described in detail below.

[Confirmation of oxide layer containing magnesium component]
Regarding the optical filter of the example, it was confirmed by the following method that an oxide layer containing a magnesium component was formed on the outermost surface of the magnesium fluoride film on the substrate on the air side.

For the measurement sample, Sample A to Sample C were taken out from a part of the manufacturing process of the optical filter.
Sample A: An optical multilayer film (similar to the above) was formed on one main surface of copper-containing borosilicate glass by using an ion-assisted vapor deposition method. Next, a magnesium fluoride film (physical film thickness: 90 nm) was formed on the surface of the optical multilayer film by a heat vapor deposition method.
Sample B: Following the manufacturing process of sample A, a layer containing a transparent resin and an infrared absorbing dye is provided on the other main surface of the substrate, and these are fired to form a near infrared absorbing layer.
Sample C: The optical filter is cleaned following the manufacturing process of sample B.

For each sample, the surface composition of the optical filter was analyzed using an X-ray photoelectron spectroscopy analyzer (QuanteraSXM, manufactured by ULVAC-PHI, Inc.). The results are shown in Table 1. Two samples were analyzed for each sample.

As shown in Table 1, the oxygen content on the optical filter surfaces of Sample B and Sample C was higher than that immediately after the magnesium fluoride film was formed on the substrate (Sample A). As a result, it is presumed that the substrate on which the magnesium fluoride film was formed was fired or washed after firing to form an oxide layer containing a magnesium component on the outermost surface of the magnesium fluoride film on the air side on the air side. To.

The optical filter according to the comparative example has the same optical multilayer film formed on the same substrate as the embodiment, and does not have a magnesium fluoride film and an oxide layer. The outermost layer on the air side of the optical multilayer film is SiO ₂ .

As an evaluation of the optical filters of Examples and Comparative Examples, the difficulty of adhering foreign substances to metal powder and resin powder (dustproof property) and the ease of removing foreign substances (dust removal property) were verified using the following evaluation methods. ..

[Evaluation method for metal powder]
First, the optical filter is statically removed for 5 minutes using an ionizer. The optical filter is then placed horizontally on the surface on which the magnesium fluoride film is formed. Then, the optical filter is sprinkled with metal powder. The metal powder is a powder carved from a stainless steel member, and the particle size distribution is 98% for less than φ20 μm and 2% for φ20 μm or more. Then, grab the side of the optical filter with tweezers and pick it up so that the main surface is vertical. Next, the optical filter is set in the microscope, and any five points on the main surface are imaged. The obtained image is analyzed by image analysis software (WinROOF, manufactured by Mitani Corporation), and the amount of metal powder adhered is calculated. The difficulty of foreign matter adhering (dust resistance) was evaluated based on the amount of this metal powder adhering.

Next, after evaluating the dust resistance, the optical filter was housed in a resin case, held in a posture in which the main surface was vertical, and the case was struck to vibrate. Next, the optical filter is set in the microscope in the same manner as described above, and any five points on the main surface are imaged. The obtained image is analyzed by image analysis software (WinROOF, manufactured by Mitani Corporation), and the amount of metal powder adhered is calculated. The removal rate of foreign matter was calculated using the amount of this metal powder adhered and the amount of adhering obtained at the time of evaluation of dust resistance. The ease of removing the foreign matter (dust removal property) was evaluated based on the residual rate of the foreign matter.

[Evaluation method for resin powder]
First, the optical filter is statically removed for 5 minutes using an ionizer. Next, the optical filter is placed horizontally on the surface on which the magnesium fluoride film is formed in the resin desiccator. A container containing resin powder is placed in a desiccator, and the resin powder is blown up using a blower and deposited on an optical filter. As the resin powder, spherical plastic particles (Micropearl, manufactured by Sekisui Chemical Co., Ltd., average particle diameter: about 20 μm) were used. Then, grab the side of the optical filter with tweezers and pick it up so that the main surface is vertical. Next, the optical filter is set in the microscope, and any five points on the main surface are imaged. The obtained image is analyzed by image analysis software (WinROOF, manufactured by Mitani Corporation), and the amount of resin powder adhered is calculated. The difficulty of foreign matter adhering (dust resistance) was evaluated based on the amount of this resin powder adhering.

Next, after evaluating the dust resistance, the optical filter was housed in a resin case, held in a posture in which the main surface was vertical, and the case was struck to vibrate. Next, the optical filter is set in the microscope in the same manner as described above, and any five points on the main surface are imaged. The obtained image is analyzed by image analysis software (WinROOF, manufactured by Mitani Corporation), and the amount of resin powder adhered is calculated. The removal rate of foreign matter was calculated using the amount of this resin powder adhered and the amount of adhering obtained at the time of evaluation of dust resistance. The ease of removing the foreign matter (dust removal property) was evaluated based on the residual rate of the foreign matter.

[Surface roughness]
Product geometric characteristic specifications (GPS) -Surface texture: Contour curve method-Measurement method based on the method and procedure of surface texture evaluation (JIS B0633: 2001), surface using device (Dimension 3000 Atomic Force Microscope, manufactured by Veeco) Roughness (Ra) was measured.

The results are shown in Table 2. The amount of adhesion of both the metal powder and the resin powder indicates the adhesion area obtained in the image by the number of pixels (pixel). The dustproof property and the dust removal property are the average values of the measurement data (5 points) of one sheet, and are the results of measuring these three sheets at a time (N = 3). The surface roughness is an average value of three sheets.

From the evaluation results, it can be seen that the optical filter of the example (Example 1) has a smaller amount of metal powder and resin powder adhered to the optical filter of the comparative example (Example 4) and has high dust resistance. Further, it can be seen that the optical filter of the example has a lower residual ratio of metal powder and resin powder and higher dust removal property than the optical filter of the comparative example.

Next, the relationship between the contact angle of the optical filter with pure water and the dustproof and dustproof properties was investigated.

[Contact angle with pure water]
The contact angle with respect to pure water was measured using a measuring method and an apparatus (automatic contact angle meter DMe-200, manufactured by Kyowa Interface Science Co., Ltd.) based on the wettability test method (JIS R3257: 1999) of the substrate glass surface. As a specific measurement method, the sessile drop method (θ / 2 method) is used, and the conditions are that the amount of droplets is 1.5 μL, the measurement time is 10 sec, the room temperature is 25 ° C ± 5 ° C, and the humidity is 50% ± 10%. gone.

The results are shown in Table 3. Dustproofness and dustproofness are average values of one measurement data (5 points). Further, it is the average value of the measurement data of the contact angle with respect to pure water and 3 points per sheet.

From the evaluation results, it can be seen that the optical filters of the examples (Examples 1 to 3) have a contact angle with respect to pure water of 50 ° or less, a small amount of metal powder adhered, and high dust resistance. In addition, it can be seen that the residual rate of metal powder is low and the dust removal property is high.

Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, which naturally belong to the technical scope of the present invention. Understood. Further, each component in the above-described embodiment may be arbitrarily combined as long as the gist of the invention is not deviated.

This application is based on a Japanese patent application filed on February 26, 2019 (Japanese Patent Application No. 2019-032249), the contents of which are incorporated herein by reference.

1 Substrate 2 First optical multilayer film 3 Magnesium fluoride film 4 Oxide layer containing magnesium component 5 Near infrared absorption layer 6 Second optical multilayer film 7 Frame 8 Protective sheet 9 Foreign matter 10, 20, 30 Optical filter 100 Optical filter carrier support

Claims (13)

With the board
A first optical multilayer film obtained by laminating dielectric thin films having different refractive indexes provided on one main surface of the substrate, and
A magnesium fluoride film provided on the surface of the first optical multilayer film is provided.
The magnesium fluoride film is an optical filter having an oxide layer containing a magnesium component on at least a part of the outermost surface on the air side. The optical filter according to claim 1, wherein the main surface of the optical filter provided with the magnesium fluoride film has a surface roughness (Ra) of 0.3 nm to 2.4 nm. The optical filter according to claim 1 or 2, wherein the main surface of the optical filter on the side provided with the magnesium fluoride film has a contact angle of 5 ° to 80 ° with respect to pure water. The optical filter according to any one of claims 1 to 3, wherein the substrate is provided with a near-infrared absorbing layer containing a transparent resin and an infrared absorbing dye on the other main surface. The optical filter according to claim 4, wherein a second optical multilayer film is provided on the surface of the near-infrared absorbing layer. The optical filter according to any one of claims 1 to 5, wherein the substrate is glass or resin. The optical filter according to any one of claims 1 to 6, wherein the optical filter is a near-infrared cut filter that cuts light having a wavelength in the near-infrared region. The optical filter according to any one of claims 1 to 7 is provided with a plurality of the optical filters.
A transport support for an optical filter, characterized in that both main surfaces of the optical filter are sandwiched between protective sheets. A step of preparing a substrate, a step of forming a first optical multilayer film on one main surface of the substrate, and a step of forming a magnesium fluoride film on the surface of the formed first optical multilayer film. A method for manufacturing an optical filter, comprising at least a step of cutting a substrate on which a magnesium fluoride film is formed into individual pieces. The steps of cutting the substrate on which the magnesium fluoride film is formed into individual pieces are the steps of forming a modified layer inside the substrate using a laser along the planned cutting line of the substrate and applying stress to the substrate. The method for manufacturing an optical filter according to claim 9, further comprising a step of extending cracks from the modified layer and cutting the substrate. The method for manufacturing an optical filter according to claim 9, wherein the step of cutting the substrate on which the magnesium fluoride film is formed into individual pieces includes a step of cutting the substrate using a rotary blade along a planned cutting line of the substrate. .. Before the step of cutting the substrate on which the magnesium fluoride film is formed into individual pieces, a step of forming a near-infrared absorbing layer containing a transparent resin and an infrared absorbing dye on the other main surface of the substrate, and a step of forming a near-infrared ray. The method for manufacturing an optical filter according to any one of claims 9 to 11, further comprising a step of forming a second optical multilayer film on the surface of the absorbent layer. Before or after the step of cutting the substrate on which the magnesium fluoride film is formed into individual pieces, a step of forming an oxide layer containing a magnesium component on at least a part of the outermost surface of the magnesium fluoride film on the air side. The method for manufacturing an optical filter according to any one of claims 9 to 12.

Images