JPH10330132A - Production of glass product and filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To polish the glass surface with a high accuracy by polishing the glass surface with a polishing liquid at a pH previously approximated to that of glass. SOLUTION: A polishing agent such as red iron oxide, cerium oxide, titanium oxide or colloidal silica having 0.2-30 μm, preferably 0.2-20 μm, especially preferably 0.2-12 μm particle size distribution in an amount of 1-20 wt.% is dispersed in water or a mixed solvent of water with a water-soluble organic solvent to provide a polishing liquid. A glass composed of a phosphate glass or fluorophosphate glass of the same kind as that of a glass to be polished is then dipped in the polishing liquid to elute the glass component into the polishing liquid and regulate the pH thereof within ±1.0, preferably within ±0.7, especially preferably within ±0.5 based on the pH of the glass. The resultant polishing liquid is used to polish the phosphate glass or fluorophosphate glass and afford a glass product having <=7 μm width of linear flaws on the surface. Thereby, the occurrence of latent flaws, etc., can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a glass product, a filter, and a solid-state imaging device using the same. The present invention relates to a method for efficiently producing a phosphate glass product, a filter made of the glass product obtained by the method, and a solid-state imaging device using the filter.

[0002]

2. Description of the Related Art In general, a glass using a phosphate as a glass network former is excellent in transmittance in the ultraviolet region, and is therefore used for applications in which transmittance in the ultraviolet region is regarded as important. In color filter glass,
SiO ₂ and B ₂ O ₃ as glass network formers
Colored glass using phosphate as a glass network former (color filter glass) can be more stably colored by transition metal ions such as Fe ²⁺ , Cu ^2+, etc. Used.

By the way, in order to improve the stability, optical constant, transmission characteristics, chemical durability and the like of glass, Li _{2 is used.}
Alkali metal oxides such as O, Na ₂ O, K ₂ O, and Cs ₂ O; alkaline earth metal oxides such as CaO, MgO, SrO, and BaO; other divalent metal oxides such as ZnO and PbO; Etc. are often added. By appropriately adding these, the glass can have moldable stability and can be mass-produced without devitrification.

As an application of these glasses, for example, a CCD (Charge Couple) used for a color VTR camera or the like is used.
For a near-infrared absorption filter which is a visibility correction filter of Pled Device). The glass used for this filter has a property of adding CuO as a coloring component and absorbing the longer wavelength side than 700 nm by utilizing the absorption by Cu ²⁺ ions. In this case,
If phosphate is not used as the main component of the glass network former, good absorption by Cu ²⁺ will not be exhibited. Therefore, a glass obtained by adding CuO to phosphate glass or fluorophosphate glass is used for this filter, and the thickness of the glass is 1.0 to 2.0 mm.
Polished to a certain extent, it is used as a filter for solid-state imaging devices such as CCDs. In this solid-state imaging device, the density has been increasing at present, and accordingly, one cell of the photodiode constituting the CCD has become extremely small. For this reason, even if the scratches are on the order of a few μm, which has not been a problem until now, an adverse effect on the image has come to occur. For example, if a flaw having a size exceeding about 7 μm is present, the size of the photodiode will be almost crushed, and the image of the solid-state imaging device will be disturbed. Therefore, if a near-infrared absorption filter is installed near the CCD and the number of pixels per unit area is large, a highly accurate polished surface (polishing scratch width ≦ 7)
μm) is required.

[0005] Phosphate glass using the above-mentioned phosphate as a glass network former is liable to be scratched by polishing and chemically reactive because of its inherently weak glass structure. However, there is a limit to the composition for increasing the hardness of glass, and it is not easy to obtain a hardness that is easy to polish, such as borosilicate glass. In order to maintain the desired transmission properties, chemical durability, stability of mass-producible glass, and other optical properties, there is a limit in improving the composition, and phosphate glass and fluorophosphate glass are limited. Cannot obtain a hardness like borosilicate glass, and many glasses of this system are so-called hard-to-polish glasses having low hardness.
Therefore, in order to stably obtain a high-precision polished surface (polishing scratch width ≦ 7 μm) in this type of glass, there is a limit in either improving the glass composition or improving the polishing technique. .

As a method of polishing such phosphate glass or fluorophosphate glass, a method of polishing a glass using a polishing liquid obtained by adding an abrasive such as CeO _{2 to} water has conventionally been used. In general, low-hardness glass improves the accuracy of the polished surface of the glass by lowering the load during polishing or lowering the rotation speed, but phosphate glass and fluorophosphate glass have a considerable hardness. In addition, the polishing accuracy is limited due to low chemical reaction, and the polishing accuracy is limited. Latent scratches are likely to develop, and the polishing time is unavoidably long.

[0007]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a glass product having a surface polished with high precision.
In particular, it is an object of the present invention to provide a method for easily producing a phosphate glass product or a fluorophosphate glass product, a filter made of the glass product obtained by this method, and a solid-state imaging device using the filter. .

[0008]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies on a method of polishing a glass surface with a polishing liquid. The reason that large scratches (> 7 μm in width) are likely to remain is probably due to a chemical reaction between the glass surface and water during polishing, that is, the solubility of alkali metals and alkaline earth metal oxides in the glass components. The components undergo an ion exchange reaction with hydronium ions (H ₃ O ⁺ ) in water to be selectively eluted, and that the eluted components erode the skeleton of the glass. Focusing on the fact that the entire surface of the glass is dissolved due to hydrolysis of the glass, the reaction rate between the glass and the polishing liquid is adjusted by bringing the pH of the polishing liquid when polishing the glass closer to the pH of the glass. Is delayed, resulting scratches is very small (≦ width 7 [mu] m), it found that ultra-smooth surface can be obtained, and have completed the present invention based on this finding.

That is, according to the present invention, (1) when polishing a glass surface using a polishing liquid, the pH of the polishing liquid is determined in advance.
Is carried out to approximate the pH of the glass, and then the glass surface is polished using the polishing liquid. (2) The glass obtained by the method (1) (3) a filter made of phosphate glass or fluorophosphate glass, wherein the width of a linear scratch on the surface is 7 μm or less, and (4) a filter made of a product. The above (3)
Solid-state imaging device characterized by using a filter of
Is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for manufacturing a glass product of the present invention, the surface of a glass is polished with a polishing liquid. In this case, the pH of the polishing liquid is made to approximate the pH of the glass to be polished in advance. It is necessary to apply. The polishing liquid is a liquid in which an abrasive is dispersed in an aqueous medium (hereinafter, referred to as an abrasive-containing aqueous dispersion), and its pH is set to ± 1.0 with respect to the pH of glass to be polished in advance. It is preferable to adjust within. As a result, the glass is polished from the beginning with a polishing solution having a pH stable for the glass, and thus it is possible to suppress a chemical reaction between the glass and the aqueous dispersion containing an abrasive. In the polishing method described above, polishing flaws, which are likely to occur, are extremely unlikely to occur, and a glass having an ultra-smooth surface can be stably obtained.
From such a point, the pH of the polishing liquid is more preferably adjusted to be within ± 0.7 with respect to the pH of the glass, and particularly preferably adjusted to be within ± 0.5.

The pH of the glass in the present invention is a value measured by the following method. That is, a particle size of 1.
30 g of glass powder to be polished of 4 mm to 850 μm
Is added to 100 ml of ion exchange water at about 50 ° C.,
Stir with a stirrer in a constant temperature bath at about 50 ° C. until the pH of the ion-exchanged water becomes constant. This constant pH
The value is the pH of the glass to be polished.

The aqueous medium used for preparing the polishing liquid (abrasive-containing aqueous dispersion) in the present invention includes, for example, water,
A mixture of water and a water-soluble organic solvent, specifically, lower alcohols, ketones, ethers, a surfactant and the like can be mentioned, but water is usually used. The abrasive is not particularly limited, and any one can be selected from those conventionally used as abrasives for glass. As this abrasive, for example,
Preferable examples include inorganic powders such as cerium oxide, titanium oxide, and colloidal silica. The particle size distribution of this abrasive is usually 0.2 to 30 μm, preferably 0.2 to 20 μm.
m, particularly preferably in the range of 0.2 to 12 μm. However, the particle size distribution here includes the particle size distribution of the secondary particle size of the abrasive. These abrasives may be used alone or in combination of two or more. The concentration of the abrasive diluted with water is preferably 1 to 20% by weight, more preferably 3 to 15% by weight.

Further, as the pH adjuster of the abrasive,
When adjusting the pH using an alkali, for example, Na
OH, Na ₂ CO ₃ , NaHCO ₃ , Na ₂ CO ₃ .NaH
CO ₃ , Na ₃ PO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ , N
_{a 4 P 2 O 7, Na} 5 P 3 O 10, Na 6 P 4 O 13, (NaP
O ₃ ) ₃ , (NaPO ₃ ) ₄ , (NaPO ₃ ) ₆ , 2Na ₂ O
_{· SiO 2 · 5H 2 O,} Na 2 O · SiO 2 · 5H 2 O and the like are used, these may be used alone or may be used in combination of two or more kinds. On the other hand, when adjusting the pH using an acid, for example, HCl, HNO ₃ , H ₂ S
O ₄ , H ₂ CO ₃ , H ₃ PO _{4 and the} like are used, and these may be used alone or in combination of two or more.

As a method for preparing a polishing liquid, for example, a glass of the same kind as the glass to be polished is immersed in an aqueous medium to elute the glass components into water, and the pH of the glass is usually ± 1.0. After preparing an aqueous solution having a pH within, preferably within ± 0.7, particularly preferably within ± 0.5, an abrasive is added to this to prepare an abrasive-containing aqueous dispersion, and used as a polishing liquid. You may. In this case, when the same kind of glass as the glass to be polished is immersed in an aqueous medium to elute the glass component, the glass component can be eluted in a short time by heating.

The glass to which the method of the present invention is applied is not particularly limited. For example, even if the glass is easily damaged due to low hardness and easily reacted chemically, the glass according to the present invention can be used. In the point that the width of polishing scratches is reduced and polishing can be performed with high precision, when applied to such glass,
The effects of the present invention are best exhibited. Such glasses having a low hardness and being easily scratched by polishing and furthermore easily reacting chemically include phosphate glass and fluorophosphate glass.

Examples of the phosphate glass to which the present invention is applied include, as described in Japanese Patent Publication No. 52-5330, 75 to 88% of P ₂ O ₅ and Li ₂ O 6 by weight.
_{~15%, Al 2 O 3 3~14} %, Na 2 O 0~5
_{%, K 2 O 0~5%,} B 2 O 3 0~5%, ZrO 2 0
_{~5%, TiO 2 0~5%,} La 2 O 3 0~5%, M
Basic glass 1 consisting of gO 0-5% and ZnO 0-5%
A phosphate glass containing 0.5 to 10.0 parts by weight of CuO per 100 parts by weight is exemplified. This phosphate glass is a glass which hardly absorbs light having a wavelength of 400 to 600 nm and can sharply absorb light having a wavelength exceeding 600 nm.

Further, 75-90% of P ₂ O ₅ , Al ₂ O _{3 based on} weight described in JP-A-62-128943.
O ₃ 7.5 to 20%, total of B ₂ O ₃ and SiO ₂ 0 to 1
5%, a total of 1 to 2 of BaO, MgO, CaO and SrO
5%, Y ₂ O ₃ and La ₂ O ₃ and ZrO ₂ and Ta ₂ O ₃ and TiO ₂
0 to 15% in total and 0.4 to 15.0% CuO per 100 parts by weight of a base glass composed of 0 to 10% PbO.
Phosphate glass containing parts by weight. This phosphate glass has a high transmittance for light having a wavelength of 400 to 550 nm, sharply cuts the transmission of light having a wavelength of 600 to 700 nm, and has high chemical durability.

Further, as described in US Pat. No. 5,668,066 (Japanese Patent Application Laid-Open No. Hei 9-100136), 35 to 50% of P ₂ O ₅ , 0 to 5% of Li ₂ O,
Na ₂ O is 0~12%, K ₂ O is 0~20%, Cs ₂ O is 0~20%, R ₂ O (R is an alkali metal) is 1.5 to 2
0%, ZnO 17-48%, MgO 0-7%, Ca
0 to 7% of O, 0 to 7% of SrO, 0 to 12 of BaO
%, R'O (R 'is an alkaline earth metal) from 0 to 15%,
Glass containing 0.2 to 12% of CuO is exemplified. This glass is excellent in transmittance characteristics in ultraviolet, stability for mass production, workability and weather resistance.

On the other hand, as a fluorophosphate glass to which the method of the present invention is applied, for example, a fluorophosphate glass containing 45% by weight or less of P ₂ O _{5 and} 1% by weight or more of AlF ₃ , particularly, a base glass Has a P ₂ O 5 content of _{5 to} 45% based on weight and A described in JP-A-1-219037.
IF _{3 to} 35%, RF ₂ (metal Ba having a divalent valence,
Total content of fluorides of Sr, Ca, Mg, Zn and Pb) 10 to 75%, R ¹ F (metal Li whose valence is monovalent,
Total content of fluorides of Na and K) 0-40%, R ²
F (Trivalent to pentavalent metals La, Y, Gd, Si,
Total content of fluorides of B, Zr and Ta) 0 to 15%
And 100 parts by weight of the base glass, C
Examples include, but are not limited to, fluorophosphate glasses containing 0.2-15.0 parts by weight uO. The fluorophosphate glass having the above composition is suitable as a filter material for color correction in a solid-state imaging device using a CCD, for example, in that it has excellent weather resistance and light transmittance characteristics.

The method for polishing the glass is not particularly limited. For example, a method commonly used in the conventional method for polishing glass is used. For example, the glass to be polished is mounted on a polishing apparatus, and the polishing liquid is used while rotating. After the polishing treatment is performed until the thickness of the glass reaches a desired value, a method of cleaning and removing the polishing liquid remaining on the glass surface by a known means can be used.

In this way, it is possible to easily manufacture a glass product having an ultra-smooth surface having a linear scratch on the surface of usually 7 μm or less. Such a method of the present invention can be applied to, for example, a polishing liquid cleaning treatment in addition to the polishing treatment. In the cleaning process after the polishing treatment, removal of the polishing liquid and other dirt are usually performed by using an ultrasonic cleaning device or the like, and the pH of the cleaning liquid and the rinse liquid used in the subsequent rinsing treatment are used. The present invention can be applied to adjustment. That is, when an aqueous cleaning liquid is used in the ultrasonic cleaning apparatus,
By adjusting H to within ± 1.0 of the pH of the glass to be cleaned, erosion on the glass is extremely small,
Latent scratches and the like are less likely to occur than in the case where no adjustment is made.

The present invention also provides a method for producing a filter using the glass product thus obtained, and a phosphate glass or a fluorophosphate glass having a linear scratch on the surface of 7 μm or less in width. It also provides a filter. As the filter, a filter for a solid-state imaging device such as a CCD, specifically, a visibility correction filter is used.

In recent years, solid-state imaging devices such as CCDs have been reduced in size and density, and accordingly, high image quality has been demanded. Due to the miniaturization of the solid-state imaging device, the device size has been reduced from the conventional 1/2 inch system to a 1/4 inch system, and as a result, the area per pixel has become extremely small. Micro defects have come to be regarded as a problem in placed filters. If the width of the linear scratch on the filter surface exceeds 7 μm, one or more pixels will be crushed, thereby disturbing the image. Therefore, a filter having an ultra-smooth surface with a scratch width of 7 μm or less is required. Therefore, the glass product obtained by the above-described method of the present invention is suitable as the filter for a solid-state imaging device.

Further, the present invention also provides a solid-state imaging device using the filter made of the phosphate glass or the fluorophosphate glass. This solid-state imaging device mainly includes, for example, a CCD, an infrared absorption filter, an optical low-pass filter, and an optical lens. However, as the filter position is closer to the CCD, polishing scratches on the filter surface tend to disturb the image. Therefore, the closer the filter is to the CCD, the smaller the width of the linear scratch on the filter surface is required.

The solid-state imaging device using the filter of the present invention is not particularly limited. For example, as shown below, in the solid-state imaging device having the structure shown in FIG. . In the apparatus of FIG. 1, two optical low-pass filters are used, but there may be one or three or more optical low-pass filters, and the number of optical low-pass filters is not limited.

FIG. 1 is a schematic diagram showing an example of a solid-state image pickup device using the filter of the present invention. Light incident from a subject passes through an optical lens 1, passes through an optical low-pass filter 2, 2 'and an infrared ray. The light passes through a unit including the absorption filter 3, is incident on a package 4 having a CCD chip 5 and a window glass 6, is converted into an electric signal, and is then electrically processed.

In a solid-state imaging device having such a configuration, that is, a device in which the infrared absorption filter 3 is located between the optical low-pass filters 2 and 2 ',
In the case where the filter of the present invention is used as the infrared absorption filter 3, although not shown, the filter is generally closer to the CCD than the infrared absorption filter is located at a position to be incorporated in the optical lens system.
The effect of the filter of the present invention is better exhibited.

[0028]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, four kinds of A to D having the composition shown in Table 1 were used as the glass. Glasses A to C are phosphate glasses, and glass D is a fluorophosphate glass.
Glasses A, B and D have added CuO and are mainly used as filters for correcting color sensitivity of CCD. On the other hand, glass C is used as a low refractive index, low dispersion optical glass for a camera lens and the like.

Production Examples Preparation of Glasses A to D After blending to obtain the glass having the composition shown in Table 1, the mixture was melted at 800 to 1200 ° C. using a platinum crucible, homogenized by stirring, and then bubbled by fining. Was performed, poured into a mold, and gradually cooled to produce a glass block. Then, after removing the strain inside the glass according to a conventional method, the glass block was placed at 20.0 × 30.
It was sliced into a flat plate of 0 × 1.40 mm. The glass side was chamfered so that broken pieces of glass were not mixed during polishing. Thus, test glass plates A to D were prepared.

[0030]

[Table 1]

Example 1 1000 g of cerium oxide powder (trade name: MIRAKE S-2, manufactured by Mitsui Kinzoku Co., Ltd.) as an abrasive in 10 liters of pure water
Was added, and the pH was adjusted to the level shown in Table 2 using sodium hydroxide to prepare a polishing liquid. next,
For the glasses A, B, C and D obtained in the production examples,
Polishing was performed as follows. 80 pieces of glass were fixed on a polishing apparatus, and a polishing liquid was used. Load: 80 g / cm ² ,
Rotation speed: thickness of 1.20 mm under the condition of about 60 rpm
It was polished until it became. The polishing treatment was performed in two steps. In the first step, a relatively large particle size (0.2 to 30 μm)
In the second step, a relatively small particle size (0.2
〜12 μm) abrasive was used. The above particle size distribution includes the particle size distribution of the secondary particles in the abrasive. After the polishing was completed, the polishing liquid was completely removed from the glass surface, and the polished surface accuracy was measured in a dark room. Regarding the width of the linear scratches, those having a width exceeding 7 μm were evaluated as x, and those having a width of 7 μm or less were evaluated as ○. The results are shown in Table 2 together with the pH of the glass. The pH of glass
Was measured according to the method described in the text of the specification.

Example 2, Comparative Example 1 A polishing treatment was performed in the same manner as in Example 1 except that the pH of the polishing liquid was changed as shown in Table 2, and the polished surface accuracy was measured. Table 2 shows the results.

Example 3 In the preparation of the polishing solution in Example 1, instead of pure water, each glass was immersed in pure water, and an aqueous solution in which glass components were dissolved in pure water was used. A polishing liquid was prepared and polished in the same manner as in Example 1 except for adjustment as shown in Table 2, and the polished surface accuracy was measured. Table 2 shows the results.

Comparative Example 2 A polishing liquid was prepared and polished in the same manner as in Example 1 except that the pH was not adjusted in the preparation of the polishing liquid in Example 1, and the polishing surface accuracy was measured. did. Table 2 shows the results.

[0035]

[Table 2]

The width of the linear scratches on the polished surface of the polished glass plate obtained in Examples 1, 2 and 3 was smaller than 5 μm in all the glasses, and the depth of the scratches was 4 μm or less. And good results were obtained.

On the other hand, in Comparative Example 1, the p
H is not close to the pH of the glass, the difference from the pH of the glass is larger than 1.0, and the polished surface of the glass plate after the polishing treatment has numerous scratches with a width larger than 7 μm. I was Comparative Example 2 is a conventional polishing method without performing pH adjustment, and the polished surface of the glass plate after the polishing treatment is
In each case, countless scratches having a width larger than 30 μm were present.

[0038]

According to the method of the present invention, it is possible to easily produce a glass product, particularly a phosphate glass product or a fluorophosphate glass product, whose surface has been polished with high precision (surface scratch width ≦ 7 μm). it can. The glass product whose surface is polished with high precision is suitably used, for example, as a filter for a solid-state imaging device.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of a solid-state imaging device using a filter of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical lens 2 Optical low-pass filter 2 'Optical low-pass filter 3 Infrared absorption filter 4 Package 5 CCD chip 6 Window glass

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02B 5/20 G02B 5/22 5/22 1/10 Z H01L 27/14 H01L 27/14 D

Claims (9)

[Claims] 1. When polishing a glass surface with a polishing liquid, an operation for previously bringing the pH of the polishing liquid close to the pH of the glass is performed, and then the glass surface is polished using the polishing liquid. Characteristic glass product manufacturing method. 2. The method for producing a glass product according to claim 1, wherein an operation of approximating the pH of the polishing liquid to the pH of the glass is performed so that the difference from the pH of the glass is within 1.0. 3. The method for producing a glass product according to claim 1, wherein the glass is phosphate glass or fluorophosphate glass. 4. The method for producing a glass product according to claim 1, wherein the glass product is used for a filter. 5. The filter is a CCD (Charge Couple).
5. The method for producing a glass product according to claim 4, which is for a solid-state imaging device using ed Device). 6. A method for producing a filter, comprising using the glass product obtained by the method according to claim 4. 7. A filter made of phosphate glass or fluorophosphate glass, wherein the width of the linear scratch on the surface is 7 μm or less. 8. The filter according to claim 7, which is a filter for a solid-state imaging device using a CCD (Charge Coupled Device). 9. A solid-state imaging device using the filter according to claim 7. Description: