JP2020142952A - Near-infrared absorbing glass plate - Google Patents

Abstract

To provide a near-infrared absorbing glass plate which enables size reduction of a solid-state imaging element device.SOLUTION: A near-infrared absorbing glass plate which is characterized in that: the aspect ratio Str of the surface properties is 0.1 or more; and 1-40 mass% of CuO is contained in the composition.SELECTED DRAWING: Figure 1

Description

The present invention relates to a near-infrared absorbing glass plate.

Solid-state image sensors such as CCD and CMOS are used in digital cameras, smartphone cameras, and the like. Since these solid-state image sensor devices have a wide range of light-receiving sensitivities, it is necessary to remove light in the infrared region in order to match the human visual sensation. Patent Document 1 below discloses a near-infrared absorbing glass plate as a near-infrared cut filter for removing light in the infrared region. Further, in Patent Document 1, the thickness of the glass plate is reduced by physical polishing.

JP-A-2007-99604

In recent years, the solid-state image sensor device is required to be further miniaturized. Therefore, the near-infrared absorbing glass plate constituting the solid-state image sensor device is also required to be further thinned. However, in the glass plate described in Patent Document 1, if the thickness is too thin, the glass plate may be cracked. Therefore, the glass plate cannot be made sufficiently thin, and the solid-state image sensor device may not be sufficiently miniaturized.

An object of the present invention is to provide a near-infrared absorbing glass plate that enables miniaturization of a solid-state image sensor device.

The near-infrared absorbing glass plate of the present invention is characterized in that the surface texture aspect ratio Str is 0.1 or more, and CuO is contained in the composition in an amount of 1 to 40% by mass. As a result of various experiments, the present inventors have found that if the aspect ratio Str of the surface texture is 0.1 or more, the strength of the glass plate is sufficiently increased and it is difficult to crack even if the thickness is thin. .. The "surface texture aspect ratio Str" is a parameter that can be obtained from an atomic force microscope (AFM), and is an index showing the anisotropy and isotropic strength of the surface texture. More specifically, Str takes a value of 0 to 1, and when it is close to 0, there are scratches such as polishing marks on the surface and the anisotropy of the surface texture becomes strong, and when it is close to 1, the surface is smooth. It shows that there are few scratches such as polishing marks and the surface texture is strongly isotropic.

The near-infrared absorbing glass plate of the present invention contains P ₂ O ₅ 10 to 70% and R ₂ O (where R is at least one selected from Li, Na and K) of more than 0 to 50% by mass. It is preferable to contain it.

The near-infrared absorbing glass plate of the present invention preferably has a thickness of 0.2 mm or less.

The near-infrared absorbing glass plate of the present invention preferably has a three-point bending strength of 200 N / mm ² or more. Here, the three-point bending strength means that 20 glass plates (20 sheets) having a size of 6 mm square and a thickness of 0.1 mm are placed on two fulcrums arranged at a distance of 2.5 mm and crossed at one point in the center between the fulcrums. This is the average value of the load at which the glass is broken when a load is applied at a head speed of 0.5 mm / min.

The near-infrared absorbing glass plate of the present invention preferably has a thickness of 0.05 mm and a light transmittance of 80% or more at a wavelength of 400 nm.

The near-infrared absorbing glass plate of the present invention preferably has a thickness of 0.05 mm and a light transmittance of 50% or less at a wavelength of 800 nm.

According to the present invention, it is possible to provide a near-infrared absorbing glass plate that enables miniaturization of a solid-state image sensor device.

It is a photograph which shows the AFM observation result of the glass surface of Example 1. It is a photograph which shows the AFM observation result of the glass surface of the comparative example.

The near-infrared absorbing glass plate of the present invention has a surface texture aspect ratio Str of 0.1 or more, and contains CuO 1 to 40% in mass%.

First, the glass composition of the near-infrared absorbing glass plate of the present invention will be described.

The near-infrared absorbing glass plate of the present invention contains 1 to 40% by mass of CuO in the composition, preferably further in mass%, P ₂ O ₅ 10 to 70%, R ₂ O (where R is Li). , Na and at least one selected from K) Containing more than 0 to 50%. The reason why the glass composition is regulated in this way will be described below.

CuO is an essential component for absorbing near infrared rays. The content of CuO is 1 to 40%, preferably 2 to 35%, 3 to 30%, 4 to 25%, 5 to 20%, and particularly preferably 6 to 15%. If the CuO content is too low, the glass needs to be thickened to obtain the desired near-infrared absorption characteristics, and as a result, it becomes difficult to thin the optical device. On the other hand, if the CuO content is too large, the liquidus temperature rises and the devitrification resistance tends to decrease.

The near-infrared absorbing glass plate of the present invention may contain the following components in addition to the above components.

P ₂ O ₅ is a component for forming a glass skeleton. The content of P ₂ O ₅ is 10-70%, 15-65%, 16-64%, 17-63%, 18-62%, 19-61%, 20-60%, 31-56%, 41- It is preferably 55%, 45-54%, particularly 47-53%. If the content of P ₂ O ₅ is too large, the weather resistance tends to decrease.

R ₂ O (where R is at least one selected from Li, Na and K) is a component that lowers the melting temperature. The content of R ₂ O 0 to 50%, greater than 0 to 40%, 3% to 30%, 5-25%, 7-23%, 8-22%, 9-21%, 10-20%, 11 It is preferably 19%, 12-18%, 13-17%, particularly 14-16%. If the content of R ₂ O is too large, the melting temperature tends to rise. When the melting temperature rises, Cu ²⁺ ions that show absorption in the near infrared region are reduced, Cu ⁺ ions that show absorption in the ultraviolet region are generated, and the light transmittance in the ultraviolet to visible region decreases, and the near infrared region Since the light transmittance of the infrared ray is likely to increase, it becomes difficult to obtain desired spectral characteristics.

A preferable range of each component of R 2 _O is as follows. Li ₂ O is a component that increases the light transmittance in the ultraviolet to visible region. By containing Li ₂ O, it is possible to reduce the absorption due to the charge transfer transition between oxygen and copper ions, which reduce the light transmittance in the ultraviolet to visible region. The content of Li ₂ O is 0 to 50%, more than 0 to 40%, 0.2 to 30%, 0.3 to 20%, 0.4 to 6%, 0.5 to 5%, 0.6 to 4%, 0.65-3%, 0.66-2%, 0.67-1.5%, 0.68-1.2%, 0.69-1.0%, especially 0.7-0 It is preferably 9.9%. If the content of Li ₂ O is too large, the liquidus temperature rises and the devitrification resistance tends to decrease. The content of Na ₂ O is preferably 0 to 50%, more than 0 to 40%, 0.5 to 30%, 0.8 to 20%, and particularly preferably 1 to 10%. The content of K ₂ O 0-50%, greater than 0 to 40%, 3% to 30%, from 3.3 to 28%, 4-25%, 5-20%, 6-19%, 6.2 to 18 It is preferably 5.5%, 10-18%, particularly 14-17%.

Al ₂ O ₃ is a component that greatly improves weather resistance. It is also a component that improves devitrification resistance. The content of Al ₂ O ₃ is preferably 0 to 19%, 1 to 14%, 2 to 10%, 3 to 8%, and particularly preferably 4 to 6%. If the content of Al ₂ O ₃ is too large, the meltability is lowered and the melting temperature is raised, and as a result, it becomes difficult to obtain desired spectral characteristics.

R'O (where R'is at least one selected from Mg, Ca, Sr and Ba) is a component that improves weather resistance and meltability. It is also a component that improves devitrification resistance. The content of R'O is 0 to 50%, 3 to 30%, 3.3 to 29%, 3.4 to 28%, 3.5 to 27%, 3.6 to 26%, 3.7 to 25. %, 3.8 to 24%, 3.9 to 23%, 4 to 22%, particularly preferably 5 to 20%. If the content of R'O is too large, crystals due to the R'O component are likely to precipitate during molding.

The preferable range of the content of each component of R'O is as follows.

MgO is a component that improves weather resistance. The content of MgO is 0 to 15%, 0.2 to 7%, 0.3 to 5%, 0.4 to 3.7%, 0.5 to 3.6%, 0.6 to 3.5%. , 0.7 to 3.4%, 0.8 to 3.3%, 0.9 to 3.2%, 0.8 to 3.1%, particularly preferably 0.9 to 3%. If the content of MgO is too large, it becomes difficult to vitrify.

CaO is a component that improves weather resistance like MgO. The CaO content is preferably 0 to 15%, 0.4 to 10%, and particularly preferably 1 to 7%. If the CaO content is too high, it becomes difficult to vitrify.

Similar to MgO, SrO is also a component that improves weather resistance. The content of SrO is preferably 0 to 12%, 0.3 to 10%, and particularly preferably 0.5 to 5%. If the content of SrO is too large, it becomes difficult to vitrify.

BaO is a component that enhances the stability of vitrification and improves the weather resistance. Especially when P ₂ O ₅ is small, it is easy to enjoy the effect of vitrification stability by BaO. The content of BaO is preferably 0 to 30%, 5 to 30%, 7 to 25%, 10 to 23%, and particularly preferably 15 to 20%. If the BaO content is too high, crystals due to BaO are likely to precipitate during molding.

The near-infrared absorbing glass plate of the present invention contains 1% or more of CuO. As the content of CuO increases, devitrification is likely to occur, but the devitrification resistance can be improved by containing Al ₂ O ₃ or R'O.

ZnO is a component that improves the stability and weather resistance of vitrification. The ZnO content is preferably 0 to 13%, 0.1 to 12%, and particularly preferably 1 to 10%. If the ZnO content is too high, the meltability is lowered and the melting temperature is raised, and as a result, it becomes difficult to obtain desired spectral characteristics. In addition, crystals due to the ZnO component are likely to precipitate. In particular, when P ₂ O ₅ is small, it is easy to enjoy the effect of vitrification stability by ZnO.

Nb ₂ O ₅ and Ta ₂ O ₅ are components that enhance weather resistance. The content of each component of Nb ₂ O ₅ and Ta ₂ O ₅ is preferably 0 to 20%, 0.1 to 20%, 1 to 18%, and particularly preferably 2 to 15%. If the content of these components is too large, the meltability is lowered and the melting temperature is raised, and as a result, it becomes difficult to obtain desired spectral characteristics. The total amount of Nb ₂ O ₅ and Ta ₂ O ₅ is preferably 0 to 20%, 0.1 to 20%, 1 to 18%, and particularly preferably 2 to 15%.

GeO ₂ is a component that enhances weather resistance. The content of GeO ₂ is preferably 0 to 20%, 0.1 to 20%, 0.3 to 17%, and particularly preferably 0.4 to 15%. If the content of GeO ₂ is too large, the meltability is lowered and the melting temperature is raised, and as a result, it becomes difficult to obtain desired spectral characteristics.

SiO ₂ is a component that strengthens the glass skeleton. It also has the effect of improving weather resistance. The content of SiO ₂ is 0 to 10%, 0.1 to 8%, 0.6 to 7.5%, 0.7 to 7%, 0.8 to 6.5%, 0.85 to 6.4. %, 0.9 to 6.2%, particularly preferably 1 to 6%. If the content of SiO ₂ is too large, the weather resistance tends to decrease. In addition, vitrification tends to be unstable.

In addition to the above components, B ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , Sb ₂ O _{3, and the} like may be contained within a range that does not impair the effects of the present invention. Specifically, the content of each of these components is preferably 0 to 3%, particularly preferably 0 to 2%, respectively. It is possible to improve the chemical durability by containing fluorine, but since fluorine is an environmentally hazardous substance, the anion% is 15% or less, 10% or less, 5% or less, 1% or less. , Especially preferably not contained.

The near-infrared absorbing glass plate of the present invention has a surface texture aspect ratio Str of 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0. It is preferably 0.7 or more, 0.75 or more, 0.8 or more, and particularly preferably 0.85 or more. If the Str is too small, the anisotropy tends to be strong, that is, the scratches such as polishing marks tend to increase, and as a result, the strength of the near-infrared absorbing glass plate is lowered and the glass plate is easily cracked. The upper limit of Str is not particularly limited, but is practically less than 1.

The near-infrared absorbing glass plate of the present invention preferably has a thickness of 0.2 mm or less, 0.19 mm or less, and particularly preferably 0.16 mm or less. If the thickness is too thick, it becomes difficult to miniaturize the solid-state image sensor device. If the thickness is too thin, the near-infrared absorbing glass plate is easily broken. Therefore, the thickness is preferably 0.01 mm or more, particularly 0.02 mm or more.

Near infrared absorbing glass plate of the present invention, three-point bending strength 200 N / mm ² or more, 210N / mm ² or more, 220 N / mm ² or more, 230N / mm ² or more, 240 N / mm ² or more, 250 N / mm ² or more , 260 N / mm ² or more, 270N / mm ² or more, and particularly preferably 280N / mm ² or more. If the three-point bending strength is too small, the near-infrared absorbing glass plate is easily broken. The upper limit of the three-point bending strength of the near-infrared absorbing glass plate is not particularly limited, but is 450 N / mm ² or less due to the nature of the material.

The liquidus temperature of the near-infrared absorbing glass plate of the present invention is preferably 900 ° C. or lower, 890 ° C. or lower, 880 ° C. or lower, 870 ° C. or lower, 860 ° C. or lower, particularly 850 ° C. or lower. If the liquidus temperature is too high, devitrification is likely to occur in the manufacturing process (especially during molding).

The near-infrared absorbing glass plate of the present invention has a thickness of 0.05 mm and a light transmittance at a wavelength of 400 nm of 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more. In particular, it is preferably 87% or more. On the other hand, the light transmittance at a wavelength of 800 nm is preferably 50% or less, 40% or less, 35% or less, 30% or less, 29% or less, 28% or less, 27% or less, 26% or less, and particularly preferably 25% or less. The light transmittance at a wavelength of 1200 nm is 70% or less, 65% or less, 60% or less, 59% or less, 58% or less, 57% or less, 56% or less, 55% or less, 54% or less, 53% or less, especially 52. % Or less is preferable.

Next, the method for manufacturing the near-infrared absorbing glass plate of the present invention will be described.

First, a glass base material is obtained by melting a raw material powder batch prepared to have a desired composition and molding it into a plate shape.

The melting temperature is preferably 700 to 900 ° C., particularly preferably 71 to 850 ° C. If the melting temperature is too low, it will be difficult to obtain homogeneous glass. On the other hand, if the melting temperature is too high, Cu ions are reduced and it becomes easy to shift from Cu ²⁺ to Cu ⁺ , and it becomes difficult to obtain desired optical characteristics.

The molding method is not particularly limited, but for example, a molding method such as a casting method, a rollout method, a downdraw method, or a redraw method can be used.

Subsequently, the plate-shaped glass base material prepared as described above is polished by physical polishing. In the polishing step, it is preferable that the thickness of the glass base material is more than 0.2 mm to 0.3 mm by physical polishing. If the thickness of the glass base material is made too thin by physical polishing, the glass base material may crack. Further, if the thickness of the glass base material is too thick, it becomes difficult to sufficiently reduce the thickness of the glass plate in the etching process described later.

In the polishing step, for example, the glass base material was polished to a thickness of about 0.3 mm by lap polishing, and then physically polished by optical polishing to a thickness of more than 0.2 mm to 0.3 mm. A glass base material can be obtained.

Next, the physically polished glass base material is etched by immersing it in an alkaline detergent in a vertically standing state. By etching, a near-infrared absorbing glass plate having a thickness of 0.2 mm or less can be obtained.

As the alkaline detergent, for example, an alkaline detergent containing an alkaline component such as Na or K, a surfactant such as triethanolamine, benzyl alcohol or glycol, or water or alcohol can be used.

The immersion temperature in the alkaline detergent can be, for example, 20 to 40 ° C.

The immersion time in the alkaline detergent can be, for example, 1 to 30 hours. It is preferable that the physically polished glass base material is immersed in an alkaline detergent for 1 to 30 hours in a vertically standing state, and then turned upside down and immersed for the same time. In this way, a near-infrared absorbing glass plate having a uniform thickness distribution can be obtained.

Since the surface of the glass base material is melted by etching with an alkaline detergent in this way, scratches such as polishing marks on the surface of the glass base material generated in the polishing step are removed. As a result, it is possible to obtain a near-infrared absorbing glass plate having a strong isotropic surface property (large Str) without scratches such as polishing marks. The obtained near-infrared absorbing glass plate has high strength because there are no scratches such as polishing marks that are the starting points of cracking, and it is difficult to crack even if the thickness is thin.

Hereinafter, the present invention will be described based on examples. The present invention is not limited to the following examples.

(Example 1)
By _{mass%, 6.9% CuO, P 2} O 5 46%, K 2 O 13.9%, Al 2 O 3 6.6%, 2.7% MgO, CaO 3.7%, and BaO 20. A raw material powder batch prepared to have a composition of 2% was melted at a temperature of 850 to 1300 ° C. and molded into a plate shape by a rollout method to obtain a plate-shaped glass base material.

The obtained glass base material is cut to a size of 125.1 mm square using a dicer, and the cut glass base material is fitted into the hole of the carrier set on the lower surface plate of the double-sided polishing machine, and the cut glass base material is placed on the hole. The upper surface plate was lowered and pressure was applied, and while rotating the upper surface plate, the lower surface plate and the carrier, both sides were polished while flowing a polishing liquid containing Al ₂ O _3, and the thickness of the glass base material was set to 0.3 mm. .. Subsequently, the glass base material was further polished by CeO ₂ to make the thickness of the glass base material 0.25 mm.

Next, the polished glass base material was cut into a size of 6 mm square, and the alkaline detergent having a composition of 37% Na component, 20% triethanolamine, and 43% water in mass% was added. It was immersed and etched at a temperature of 30 ° C. for 120 minutes to obtain an infrared absorbing glass plate having a size of 6 mm square and a thickness of 0.1 mm.

When the aspect ratio Str of the surface texture of the obtained infrared absorbing glass plate was measured, the Str was 0.78, which was highly isotropic. The aspect ratio Str was measured by an atomic force microscope (AFM). The result of observing the glass surface with AFM is shown in FIG. As can be seen from FIG. 1, no scratches such as polishing marks were confirmed on the glass surface, and it was found that the glass surface was strongly isotropic. The detailed measurement conditions of AFM are as follows.

SPM unit: Division Icon (made by Bruker)
Controller unit: Nano Scope (manufactured by Bruker)
Probe: OTESPA-R3 (manufactured by Bruker)
Analysis software: Nano Scope Analysis (made by Bruker)
Scan size: 5 x 5 μm
scan rate: 1Hz
sampling points: 512 x 512

Further, for the obtained infrared absorbing glass plates (20 sheets), the bending strength at three points at a distance between fulcrums of 2.5 mm was measured and the average value was calculated. As a result, it was 280 N / mm ² , and the thickness was as thin as 0.1 mm. Nevertheless, it had high strength.

Both sides of the obtained infrared absorbing glass plate were mirror-polished so as to have a thickness of 0.05 mm. The light transmittance of the infrared absorbing glass plate polished on both sides was measured in the wavelength range of 300 to 1300 nm using a spectrophotometer (UV-3100PC manufactured by Shimadzu Corporation). It was 86% at a wavelength of 400 nm, 26% at a wavelength of 800 nm, and 52% at a wavelength of 1200 nm.

(Comparison example)
Using the polished glass base material before etching obtained in the examples as a comparative example, the characteristics were evaluated in the same manner. As a result, the isotropic property was as low as 0.07, and the average value of the three-point bending strength was 90 N. Although it was / mm ² and the thickness was as thick as 0.25 mm, the strength was low. Further, the results of observing the glass surface with AFM are shown in FIG. 2. As can be seen from FIG. 2, polishing marks were confirmed on the glass surface, and it was found that the isotropic property was low.

(Examples 2-45)
An infrared absorbing glass plate was prepared in the same manner as in Example 1 except that the composition was changed as shown in Tables 1 to 5, and the aspect ratio Str, 3-point bending strength, and light transmittance were measured. The results are shown in Tables 1-5. The three-point bending strength was set to “◯” when the strength was 200 N / mm ² or more.

As is clear from Tables 1 to 5, the aspect ratio Str of Examples ^{2 to} 45 was highly isotropic with 0.71 or more, and the three-point bending strength was also high with 200 N / mm ² or more. In addition, the light transmittance also had a desired value.

Claims (6)

A near-infrared absorbing glass plate having a surface texture aspect ratio Str of 0.1 or more and containing 1 to 40% by mass of CuO in the composition. Claim 1 is characterized by containing P ₂ O ₅ 10 to 70% and R ₂ O (where R is at least one selected from Li, Na and K) in an amount of more than 0 to 50% by mass. The near-infrared absorbing glass plate described in. The near-infrared absorbing glass plate according to claim 1 or 2, wherein the thickness is 0.2 mm or less. The near-infrared absorbing glass plate according to any one of claims 1 to 3, wherein the three-point bending strength is 200 N / mm ² or more. The near-infrared absorbing glass plate according to any one of claims 1 to 4, wherein the light transmittance at a wavelength of 400 nm is 80% or more in terms of a thickness of 0.05 mm. The near-infrared absorbing glass plate according to any one of claims 1 to 5, wherein the light transmittance at a wavelength of 800 nm is 50% or less in terms of a thickness of 0.05 mm.