JP6870617B2 - Display glass substrate and its manufacturing method - Google Patents

Description

The present invention relates to a glass substrate for a display and a method for manufacturing the same.

In flat panel displays such as plasma display panels (PDPs), liquid crystal displays (LCDs), electroluminescence displays (ELDs), and field emission displays (FEDs), transparent electrodes, semiconductor elements, etc. are formed on a glass substrate. It is used as a substrate. For example, in an LCD, a glass substrate on which a transparent electrode, a TFT (Thin Film Transistor), or the like is formed is used as the substrate.

The transparent electrode, the semiconductor element, and the like are formed on the glass substrate in a state where the glass substrate is fixed on the adsorption stage by adsorption.
However, since the surface of the glass substrate is smooth, the glass substrate strongly adheres to the suction stage, making it difficult for the glass substrate to peel off from the suction stage, and if the glass substrate is forcibly peeled off, the glass substrate will be damaged.
Further, when the glass substrate on which the transparent electrode, the semiconductor element, etc. are formed is peeled off from the adsorption stage, the glass substrate becomes charged. When peeling charge of the glass substrate occurs, electrostatic destruction of a semiconductor element such as a TFT occurs.

Therefore, the surface of the glass substrate on the side in contact with the suction stage is roughened to reduce the contact area between the glass substrate and the suction stage. If the contact area is reduced, the glass substrate can be easily peeled off from the adsorption stage. In addition, the occurrence of peeling charge can be suppressed, and the amount of peeling charge can be reduced. As a method of roughening treatment, for example, a method of spraying a slurry containing a liquid and abrasive grains onto one surface of a glass substrate and polishing the surface of the glass substrate with a brush is known (for example, Patent Documents). 1).

However, in the glass substrate that has been roughened by the conventional method, the generation of peeling charge cannot be sufficiently suppressed, and electrostatic destruction of the semiconductor element may occur. Further, the peeling charge causes the glass substrate to reattach to the suction stage or the like, making it difficult for the glass substrate to peel off from the suction stage or the like, and if the glass substrate is forcibly peeled off, the glass substrate may be damaged.

Japanese Patent Application Laid-Open No. 2001-343632

The present invention provides a glass substrate for a display in which peeling charge is unlikely to occur when peeling from the adsorption stage, and a method for manufacturing the same.

The glass substrate for a display of the present invention is a glass substrate for a display having a first surface and a second surface opposite to the first surface, and the first surface has a plurality of holes to be opened. having an average opening area of the holes is at 1.70 × ¹⁰ 4 nm ² or less, the total opening area of the hole, characterized in that it is ^{6.00 × 10 6 nm 2 / 25μm} 2 or more ..

The display glass substrate of the present invention has a glass composition _{of 50 to 70% by mass based on an oxide, a SiO 2} content of 50 to 70% by mass, an Al ₂ O ₃ content of 10 to 20% by mass, and B ₂ O. _{The content of 3} is 0 to 15% by mass, the content of MgO is 0 to 10% by mass, the content of CaO is 0 to 20% by mass, the content of SrO is 0 to 20% by mass, and the content of BaO is 0. It is preferable that the total content of ~ 20% by mass, MgO, CaO, SrO, and BaO is 1 to 30% by mass, and substantially no alkali metal oxide is contained.
In the glass substrate for a display of the present invention, it is preferable that the second surface is a surface on which an electronic member is formed and the first surface is a surface on which an electronic member is not formed.
In the glass substrate for display of the present invention, the arithmetic average roughness Sa of the first surface is preferably 0.30 nm or more.
In the glass substrate for a display of the present invention, it is preferable that the first surface and the second surface are rectangular and the length of one side is 1 m or more.

The method for manufacturing a glass substrate for a display of the present invention is a step of performing glass etching treatment on the first surface of a glass plate having a first surface and a second surface opposite to the first surface. In the step of performing the glass etching process, a plurality of holes to be opened on the first surface have an average opening area of 1.70 × 10 ⁴ nm ² or less and a total opening area of 6.00 × 10 ^6. and forming so that nm ^2/25 [mu] m ² or more.

The method for producing a glass substrate for a display of the present invention preferably includes a step of washing the glass plate with a slurry containing calcium carbonate before the step of performing the glass etching process.
In the method for manufacturing a glass substrate for a display of the present invention, it is preferable that the glass etching process is etching with a gas containing hydrogen fluoride.
In the method for producing a glass substrate for a display of the present invention, in the etching with the gas containing hydrogen fluoride, the gas containing the hydrogen fluoride reaction component is discharged from the reaction gas discharge port into the etching tank at 0.07 m / sec. The gas contained in the mixed gas when discharged from the reaction gas discharge port at 0.07 m / sec and the gas discharged from the reaction gas discharge port is sucked together with the air around the reaction gas discharge port at 0.5 m / sec. The hydrogen fluoride concentration is preferably 500 ppm to 1500 ppm.

The glass substrate for a display of the present invention is unlikely to generate peeling charge when peeled from the adsorption stage.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a glass substrate for a display of the present invention. FIG. 2 is an image in which holes are detected in the glass substrate of Example 1. FIG. 3 is an image in which holes are detected in the glass substrate of Example 2. FIG. 4 is an image in which holes are detected in the glass substrate of Example 3. FIG. 5 is an image in which holes are detected in the glass substrate of Comparative Example 1. FIG. 6 is an image in which holes are detected in the glass substrate of Comparative Example 2. FIG. 7 is an image in which holes are detected in the glass substrate of Comparative Example 3. FIG. 8 is a graph showing the relationship between the total opening area of the holes in the glass substrate and the peeling charge amount of the glass substrate.

[Glass substrate for display]
FIG. 1 is a schematic cross-sectional view showing an embodiment of a glass substrate for a display of the present invention.
The display glass substrate 10 of the present embodiment has a first surface 10a and a second surface 10b opposite to the first surface 10a. The display glass substrate 10 has a plurality of holes 12 formed on the first surface 10a. The holes 12 are formed so as to open on the first surface 10a of the display glass substrate 10.
The holes 12 in FIG. 1 are shown larger than they actually are for convenience of explanation.

The hole 12 is opened on the first surface 10a of the display glass substrate 10. In other words, the hole 12 is a minute space recessed in the thickness direction of the display glass substrate 10 on the first surface 10a.
On the first surface 10a of the display glass substrate 10, the holes 12 are irregularly dispersed in an island shape. Further, the plurality of holes 12 have a non-uniform shape (unevenness), and the opening area (the size when viewed in a plane perpendicular to the plate thickness direction of the display glass substrate 10) is also non-uniform (the size when viewed in a plane perpendicular to the plate thickness direction). (Unmatched).

The average opening area of the holes 12 is 1.70 × 10 ⁴ nm ² or less, preferably ^{3.00 × 10 3} nm ^{2 to} 1.65 × 10 ⁴ nm ^2.
The average opening area is the average area of a plurality of openings existing in a predetermined region when the first surface 10a of the display glass substrate 10 is viewed from a bird's-eye view (average opening area = (S1 + S2 + ... + Sn) / n). Here, S1, S2, ..., Sn indicates the area of each opening existing in the predetermined region, and n indicates the number of openings existing in the predetermined region). By setting the average opening area within the above numerical range, when the display glass substrate 10 is placed on a suction stage or the like, the contact probability between the inside of the hole 12 and the suction stage is reduced. That is, the contact area between the display glass substrate 10 and the suction stage becomes smaller.
The average opening area of the hole 12 is a value measured by a method described later.

The total open area of the holes 12 is ^{6.00 × 10 6 nm 2 / 25μm} 2 or more, is ^{6.00 × 10 6 nm 2 / 25μm} 2 ~1.80 × 10 7 nm 2 / 25μm 2 it is preferable, more preferably ^{8.00 × 10 6 nm 2 / 25μm} 2 ~1.80 × 10 7 nm 2 / 25μm 2.
The total opening area is the total area of a plurality of openings existing in a predetermined region when the first surface 10a of the display glass substrate 10 is viewed from a bird's-eye view (total opening area = S1 + S2 + ... + Sn. Here. , S1, S2, ..., Sn indicates the area of each opening existing in the predetermined area, and n indicates the number of openings existing in the predetermined area). By setting the total opening area to the above numerical range, when the display glass substrate 10 is placed on a suction stage or the like, the contact area between the display glass substrate 10 and the suction stage becomes small.
The total opening area of the holes 12 is a value measured by a method described later.

Average open area of the holes 12 is at 1.70 × ¹⁰ 4 nm ² or less, as long as the total opening area of the holes 12 is ^{6.00 × 10 6 nm 2 / 25μm} 2 or more, a glass substrate 10 for display from the adsorption stage The amount of peeling charge generated when peeling the glass substrate 10 is small, and the glass substrate 10 for display can be easily peeled off from the adsorption stage.
The amount of peeling charge is preferably −7200 V or higher, more preferably −7150 V or higher, still more preferably −7000 V or higher, still more preferably 6800 V or higher, still more preferably −6500 V or higher. If the amount of charge for peeling is small, the glass substrate 10 for display is easily peeled off and is less likely to be damaged. In addition, electrostatic breakdown of the semiconductor element is less likely to occur.

The average opening area and the total opening area of the holes 12 are obtained by the following methods.
First, the first surface 10a of the display glass substrate 10 is observed with an atomic force microscope to obtain a shape image of the hole 12.
In the present embodiment, the shape image of the hole 12 is acquired by using the following atomic force microscope under the following measurement conditions.
Atomic Force Microscope: Bruker's Dimension ICON
Measurement mode: Tapping mode Probe: RTESPA (spring constant: 40 N / m)
Samples / Line: 512
Scan Rate: 0.5Hz
Measurement field of view: 5 μm × 5 μm
Measurement point: One point at the center of the first surface 10a

Next, using nanoscale three-dimensional image processing software (SPIP 6.4.1 manufactured by Image Metrology), leveling processing, filtering processing, and analysis processing of the shape image acquired by the atomic force microscope were performed, and the hole 12 was formed. Calculate the average opening area and the total opening area. Details will be described later.

The display glass substrate 10 of the present embodiment preferably has an arithmetic average roughness Sa of the first surface 10a of 0.30 nm to 0.90 nm. When the arithmetic mean roughness Sa is 0.3 nm or more, the amount of charge can be effectively reduced. The larger the arithmetic mean roughness Sa, the smaller the amount of charge. However, if the arithmetic average roughness Sa is too large, the visible light transmittance decreases, so that the arithmetic average roughness Sa is preferably 0.9 nm or less.
The arithmetic mean roughness Sa is a parameter defined by DIN 4768, which is an extension of the arithmetic mean roughness Ra (defined in JIS B0601 (2001)) to a surface. The average of the absolute values of the height differences of the points with respect to the average surface of the first surface 10a is represented.

The shape of the display glass substrate 10 is not particularly limited, and it is preferable that the first surface 10a and the second surface 10b are rectangular. The size of the display glass substrate 10 is not particularly limited, but when the first surface 10a and the second surface 10b are rectangular, the length of one side thereof is preferably 1 m or more, more preferably 1.5 m or more. 2 m or more is more preferable.
The longer the length of one side, the larger the area of the first surface 10a and the larger the amount of charge. However, by setting the first surface 10a to the average opening area and the total opening area, the amount of charge can be reduced even if the size has a large side length of 1 m or more.

The glass composition of the display glass substrate 10 is not particularly limited, but when a thin film is formed on the second surface 10b, the content of _{SiO 2 is expressed in mass% based on oxides from the viewpoint of adhesion and reduction of defective rate.} 50-70% by mass, Al ₂ O ₃ content 10 to 20% by mass, B ₂ O ₃ content 0 to 15% by mass, MgO content 0 to 10% by mass, CaO content The content of SrO is 0 to 20% by mass, the content of BaO is 0 to 20% by mass, and the total content of MgO, CaO, SrO, and BaO is 1 to 30% by mass. Moreover, it is preferable that the alkali metal oxide is substantially not contained.

The non-alkali glass is a glass that does not substantially contain _{alkali metal oxides (Na 2} O, K ₂ O, Li _{2 O). The total content of alkali metal oxides such as Na 2} O, K ₂ O, and Li ₂ O in the non-alkali glass may be, for example, 0.1% by mass or less.

The non-alkali glass has a high strain point and is preferably expressed in mass% based on the oxide, and has a SiO ₂ content of 58 to 66% by mass and an Al ₂ O ₃ content of 15 to. 22 _wt%, B 2 content of _{O 3} is 5 to 12 mass%, 0-8 mass% content of MgO, content of 0-9 wt% of CaO, the content of SrO 3-12.5 The content of mass% and BaO is 0 to 2% by mass, and the total content of MgO, CaO, SrO and BaO is 9 to 18% by mass.

When considering a high strain point, the non-alkali glass is preferably expressed in mass% based on oxide, and has a SiO ₂ content of 54 to 73 mass% and an Al ₂ O ₃ content of 10.5 to 22. 5.5% by mass, B ₂ O ₃ content 0 to 5.5% by mass, MgO content 0 to 10% by mass, CaO content 0 to 9% by mass, SrO content 0 to 0 The content of 16% by mass, the content of BaO is 0% to 2.5%, and the total content of MgO, CaO, SrO, and BaO is 8 to 26% by mass.

According to the display glass substrate 10 of the present embodiment, the first surface 10a has a plurality of holes 12 to be opened, and the average opening area of the holes 12 is 1.70 × 10 ⁴ nm ² or less, and the holes. the total open area of 12, because it is ^{6.00 × 10 6 nm 2 / 25μm} 2 or more, when placing the glass substrate 10 for display on such adsorption stage, the contact area therebetween is small, rubbing each other The amount of charge (charge amount) is small, and as a result, the display glass substrate 10 can be easily peeled off from the adsorption stage or the like.

[Manufacturing method of glass substrate for display]
The method for manufacturing a glass substrate for a display according to the present embodiment is a step of cleaning a glass plate 11 having a first surface 11a and a second surface 11b opposite to the first surface 11a with a slurry containing calcium carbonate. And a step of performing glass etching treatment on the first surface 11a of the glass plate 11.
Hereinafter, the surface of the glass plate 11 on the side of the display glass substrate 10 that becomes the first surface 10a is referred to as 11a, and the surface of the display glass substrate 10 that becomes the second surface 10b is referred to as 11b.

In the method for manufacturing a glass substrate for a display of the present embodiment, it is preferable to mold the glass plate 11 by the float method.
Specifically, the glass plate 11 is formed into a ribbon shape by a float method, the ribbon-shaped glass plate 11 is cut to a desired size, and the end face is chamfered.

Next, it is preferable to polish the second surface 11b of the glass plate 11 with a slurry containing cerium oxide.
The average particle size of cerium oxide used in this polishing step is preferably 0.3 μm to 10 μm, and more preferably 0.5 μm to 3 μm.
The content of cerium oxide in the slurry containing cerium oxide is preferably 0.5% by mass to 10% by mass, and more preferably 0.5% by mass to 7% by mass.

Next, after polishing with the slurry containing cerium oxide was completed, the glass plate 11 was washed with a shower and wrapped around the slurry on the second surface 11b of the glass plate 11 and the first surface 11a of the glass plate 11 with water. Rinse the slurry.

Next, the first surface 11a of the glass plate 11, preferably the first surface 11a and the second surface 11b, are washed with a slurry containing calcium carbonate.
In this washing step, in order to remove the slurry containing cerium oxide that could not be removed by shower washing, the slurry containing calcium carbonate is washed with a brush while being discharged to the glass plate 11.
This cleaning with a slurry containing calcium carbonate is mainly mechanical polishing as opposed to polishing with a slurry containing cerium oxide, which is chemical mechanical polishing. Physical to the slurry containing cerium oxide remaining on the second surface 11b and / or wrapping around from the second surface 11b to the first surface 11a, dirt existing on the first surface 11a, and the like. By collision or the like, the slurry and dirt containing cerium oxide are removed from the first surface 11a and / or the second surface 11b of the glass plate 11 and washed.
As the form of the brush, the form of a disc brush is preferable, but a form such as a roll brush can also be used.
The slurry containing calcium carbonate is a dispersion liquid in which calcium carbonate is dispersed in a solvent such as water or an organic solvent.

The average particle size of calcium carbonate used in the slurry containing calcium carbonate is preferably 0.3 μm to 10 μm, and more preferably 0.5 μm to 3 μm.
The content of calcium carbonate in the slurry containing calcium carbonate is preferably 1% by mass to 15% by mass, and more preferably 1% by mass to 10% by mass.

Since the slurry containing calcium carbonate has a low polishing ability with respect to the glass plate 11, the surface state of the second surface 11b of the glass plate 11 is maintained from the second surface 11b and the first surface 11a of the glass plate 11. The slurry containing cerium oxide can be removed.

Next, after the step of washing with a slurry containing calcium carbonate is completed, the step of washing the glass plate 11 with a high-pressure shower, the step of washing with a detergent, the step of washing with a high-pressure shower, the step of washing with pure water, the high-pressure shower It is preferable to carry out the treatment in the drying step after the step of washing with pure water and the step of shower washing with pure water.

Next, the first surface 11a of the glass plate 11 is subjected to glass etching treatment.
In this glass etching process, a plurality of holes 12 opened on the first surface 11a of the glass plate 11 have an average opening area of 1.70 × 10 ⁴ nm ² or less and a total opening area of 6.00 × 10. a ⁶ nm ² / ^{25μm 2} or more is formed as described above.

As the etching tank, one provided with a reaction gas discharge port for introducing the reaction gas into the etching tank and a reaction gas discharge port for discharging the reaction gas from the etching tank is used. The reaction gas discharge port is a slit having a width of 2 mm and a length of a size that allows the reaction gas to be discharged into the etching tank. The reaction gas discharge port is formed by forming a plurality of slits having the same length as the reaction gas discharge port in parallel at intervals. The width of the entire reaction gas outlet is 17 mm. The reaction gas discharge port faces the first surface 11a of the glass plate 11.
In the method for manufacturing a glass substrate for a display of the present embodiment, a gas containing a hydrogen fluoride reaction component is discharged from a reaction gas discharge port into an etching tank at 0.07 m / sec, and a reaction gas discharge port is discharged at 0.07 m / sec. Discharge from. The gas discharged from the reaction gas discharge port is sucked together with the air around the reaction gas discharge port at 0.5 m / sec to become a mixed gas. The concentration of hydrogen fluoride contained in the mixed gas is preferably 500 ppm to 1500 ppm, more preferably 600 ppm to 1000 ppm. By setting the concentration of the mixed gas in the above range, the average opening area and the total opening area of the plurality of holes 12 opened in the first surface 11a of the glass plate 11 tend to be in the above range.
In other words, in the glass etching process, the concentration of hydrogen fluoride contained in the mixed gas is within the above range regardless of the discharge amount, discharge amount, and suction amount of the reaction gas. It is preferably a concentration.
The glass etching process is preferably performed at normal temperature and pressure.

The reaction gas is preferably generated by atmospheric pressure plasma treatment in a plasma treatment tank different from the tank in which the glass etching treatment is performed (hereinafter referred to as “etching tank”). For example, carbon tetrafluoride as a raw material gas can be treated with atmospheric pressure plasma in the presence of water vapor to generate hydrogen fluoride as a reaction gas. As the carrier gas, an inert gas such as nitrogen gas can be used. Glass etching can be performed by blowing the generated reaction gas from a nozzle provided in the etching tank toward the first surface 11a of the glass plate 11 via a pipe.
The concentration and pressure of the reaction gas in the etching tank can be adjusted by adjusting the supply amount of the raw material gas to the plasma treatment tank, the supply amount of water, the discharge power of the plasma treatment, and the like.

It is preferable that the etching tank is provided with a substrate carry-in inlet and a substrate discharge port in order to carry out the treatment continuously. Further, it is preferable to provide a transport means for transporting the glass plate 11 from the substrate carry-in port to the substrate discharge port. In that case, the nozzle for blowing the reaction gas is installed on the path for transporting the glass plate 11 from the substrate carry-in port to the substrate discharge port.

Then, the glass plate 11 is washed with pure water and dried to obtain a display glass substrate 10, and the obtained display glass substrate 10 is inspected.

In this embodiment, prior to the step of performing the glass etching process, the steps of manufacturing the glass plate 11 by the float method, polishing with a slurry containing cerium oxide, and cleaning with a slurry containing calcium carbonate are all performed. However, in the method for manufacturing a glass substrate for a display of the present invention, any step other than the step of performing the glass etching process is optional.
For example, the glass plate 11 that has been processed up to the step of polishing with the slurry containing cerium oxide may be purchased from a third party, and only the step of cleaning with the slurry containing calcium carbonate and the step of performing the glass etching process may be performed. .. Further, the glass plate 11 which has been processed up to the step of cleaning with calcium carbonate may be purchased from a third party and only the step of performing the glass etching process may be performed. Further, the glass plate 11 to be etched may be a glass plate that has not undergone the step of polishing with a slurry containing cerium oxide.

According to the method for manufacturing a glass substrate for a display of the present embodiment, the first surface 11a of the glass plate 11 is subjected to a glass etching process, and in the glass etching process, the first surface 11a is used. a plurality of holes 12 which open, the average opening area 1.70 × ¹⁰ 4 nm ² or less, the total opening area is formed to be ^{6.00 × 10 6 nm 2 / 25μm} 2 or more, such as adsorption stage When placed on top, the contact area with the adsorption stage or the like is small, the amount of charging by rubbing against the adsorption stage (charge amount) is small, and as a result, the glass substrate 10 for display that can be easily peeled off from the adsorption stage or the like can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
A glass plate (trade name: AN100, manufactured by Asahi Glass Co., Ltd.) obtained by a float method having a length of 520 mm, a width of 410 mm, and a thickness of 0.50 mm and having been polished with cerium oxide on the second surface is transported. A slurry for cleaning the slurry prepared by dispersing calcium carbonate in water was discharged onto the first surface and the second surface, and the surface was washed with a disc brush.
The concentration of calcium carbonate was 3.0% by mass in the slurry (100% by mass).
As the calcium carbonate, one having an average particle size of 1 μm was used.
The transport speed of the glass plate was set to 10 m / min.
Next, the first surface of the glass plate that had been washed with the calcium carbonate slurry was washed with detergent and pure water, and the glass plate was dried with an air knife.
Next, the first surface of the glass plate that had been cleaned with pure water was glass-etched with hydrogen fluoride.
As the etching tank, one provided with a reaction gas discharge port for introducing the reaction gas into the etching tank and a reaction gas discharge port for discharging the reaction gas from the etching tank was used. The reaction gas discharge port was a slit having a width of 2 mm and a length of a size capable of discharging the reaction gas into the etching tank. The reaction gas discharge port is formed by forming a plurality of slits having the same length as the reaction gas discharge port in parallel at intervals. The width of the entire reaction gas discharge port was 17 mm.
In this example, the gas containing the hydrogen fluoride reaction component was discharged from the reaction gas discharge port into the etching tank at 0.07 m / sec, and discharged from the reaction gas discharge port at 0.07 m / sec. The gas discharged from the reaction gas discharge port was sucked together with the air around the reaction gas discharge port at 0.5 m / sec to become a mixed gas. The concentration of hydrogen fluoride contained in the mixed gas was adjusted to 500 ppm, and the pressure and temperature of hydrogen fluoride in the etching tank were set to normal temperature and normal pressure.
Hydrogen fluoride was generated by plasma treatment using carbon tetrafluoride as a raw material gas in the presence of water vapor. Nitrogen gas was used as the carrier gas.
Next, the glass plate for which the glass etching treatment was completed was washed with pure water and dried to obtain the glass substrate of Example 1.
As shown in FIG. 2, a plurality of holes were formed on the first surface of the obtained glass substrate. In FIG. 2, the dark part indicates the hole. In addition, the scratches seen in a straight line are scratches formed by cerium oxide that wraps around during polishing with cerium oxide. This scratch is included in the average opening area and the total opening area described later.

[Example 2]
A glass substrate of Example 2 was obtained in the same manner as in Example 1 except that the concentration of hydrogen fluoride contained in the mixed gas was adjusted to 850 ppm in the glass etching treatment.
As shown in FIG. 3, a plurality of holes were formed on the first surface of the obtained glass substrate.

[Example 3]
A glass substrate of Example 3 was obtained in the same manner as in Example 1 except that the concentration of hydrogen fluoride contained in the mixed gas was adjusted to 700 ppm in the glass etching treatment.
As shown in FIG. 4, a plurality of holes were formed on the first surface of the obtained glass substrate.

[Comparative Example 1]
A slurry for cleaning a slurry prepared by dispersing cerium oxide in water on the first surface of the glass plate while transporting the same glass plate (trade name: AN100, manufactured by Asahi Glass Co., Ltd.) as that used in Example 1. The first surface of the glass substrate was washed with a disc brush while discharging.
The concentration of cerium oxide was 7.0% by mass in the slurry (100% by mass).
As the cerium oxide, one having an average particle size of 1 μm was used.
The transport speed of the glass plate was set to 10 m / min.
Next, the first surface of the glass plate that had been washed with the cerium oxide slurry was washed with detergent and pure water, and the glass plate was dried with an air knife to obtain the glass substrate of Comparative Example 1.
As shown in FIG. 5, a plurality of holes formed by cleaning with a slurry of cerium oxide were formed on the first surface of the obtained glass substrate.

[Comparative Example 2]
A slurry for cleaning a slurry prepared by dispersing cerium oxide in water on the first surface of a glass substrate while transporting the same glass plate (trade name: AN100, manufactured by Asahi Glass Co., Ltd.) as that used in Example 1. The first surface of the glass plate was washed with a disc brush while discharging.
The concentration of cerium oxide was 7.0% by mass in the slurry (100% by mass).
As the cerium oxide, one having an average particle size of 1 μm was used.
The transport speed of the glass plate was set to 10 m / min.
Next, the first surface of the glass plate that had been washed with the cerium oxide slurry was washed with detergent and pure water, and the glass plate was dried with an air knife.
Next, the first surface of the glass plate that had been cleaned with pure water was glass-etched with hydrogen fluoride. A glass substrate of Comparative Example 2 was obtained in the same manner as in Example 1 except that the concentration of hydrogen fluoride contained in the mixed gas was adjusted to 700 ppm in the glass etching treatment.
As shown in FIG. 6, a plurality of holes were formed on the first surface of the obtained glass plate.

[Comparative Example 3]
A slurry for cleaning a slurry prepared by dispersing calcium carbonate in water on the first surface of the glass plate while transporting the same glass plate (trade name: AN100, manufactured by Asahi Glass Co., Ltd.) as that used in Example 1. Was discharged and washed with a disc brush.
The concentration of calcium carbonate was 3.0% by mass in the slurry (100% by mass).
As the calcium carbonate, one having an average particle size of 1 μm was used.
The transport speed of the glass substrate was set to 10 m / min.
Next, the first surface of the glass plate that had been washed with the calcium carbonate slurry was washed with detergent and pure water, and the glass plate was dried with an air knife to obtain the glass substrate of Comparative Example 3.
As shown in FIG. 7, the first surface of the obtained glass substrate is slightly poor in flatness as compared with Examples and other Comparative Examples, and a plurality of holes generated by cleaning with a calcium carbonate slurry are formed. Was there.

[Measurement of average opening area and total opening area of holes in glass substrate]
With respect to the glass substrates obtained in Examples 1 to 3 and Comparative Examples 1 to 3, the first surface of the glass substrate is observed with an atomic force microscope (AFM), a shape image of a hole is obtained, and then image analysis is performed. The average opening area and the total opening area of the holes were calculated using software (SPIP 6.4.1 manufactured by Image Metrology).
The atomic force microscope and measurement conditions were as follows.
Atomic Force Microscope: Bruker's Dimension ICON
Measurement mode: Tapping mode Probe: RTESPA (spring constant: 40 N / m)
Samples / Line: 512
Scan Rate: 0.5Hz
Measurement field of view: 5 μm × 5 μm
Measurement point: One point at the center of the first surface (10a)

The procedure for calculating the average opening area and the total opening area of the holes using the image analysis software is as follows.
Step 1: Perform the leveling process (“leveling per line” and “leveling the entire surface”. After that, rotate the image by 90 ° and perform “leveling per line” and “overall surface leveling” again. Execute.)
Step 2: Select or enter omnidirectional noise, high / low value, replacement rate: 2, window size: 5 from the median window, enable "include border", and apply. )
Step 3: Filter 2 (Select or enter smoothing, Gaussian distribution, standard deviation: 1 from the convolution window, enable and apply "X = Y" and "auto size")
Step 4: Particle / hole analysis (First, select or enter branch line-dispersed shape, hole detection, classification plateau range: ± 0.50, filter size smoothing: 2.00 pixels from the detection window. Next, from the post-processing window, enable "Save Shaped Holes", "Suppress Pixel Noise", and "Include Image Edge Shapes". Finally, click Detect to see the average hole area and Find the total area.)
The results are shown in Table 1.

[Arithmetic mean roughness Sa measurement of glass substrate]
The arithmetic average roughness Sa (nm) on the first surface of the glass substrates obtained in Examples 1 to 3 and Comparative Examples 1 to 3 was measured.
The arithmetic mean roughness Sa was defined in DIN 4768 and was determined by measuring a measuring region of 5 μm × 5 μm at each point with an atomic force microscope (AFM). The results are shown in Table 1.

[Charging amount of glass substrate]
The peeling charge amount of the glass substrate obtained in Examples 1 to 3 and Comparative Examples 1 to 3 is measured. In the measuring method, the edge of the glass substrate is first held, and the first surface is made to face a vacuum suction stage made of stainless steel (SUS304). Next, 1 of suction / opening of the glass substrate to the vacuum suction stage is repeated 110 times. Finally, the peeling charge amount (V) was measured by measuring the charge amount when the glass substrate was lifted up from the stage with a surface electrometer (MODEL 320C, manufactured by Trek Japan Co., Ltd.). The distance between the first surface of the glass substrate and the probe of the surface electrometer is 30 mm. The results are shown in Table 1.
Also, the total opening area of the holes of the glass substrate ^{(nm 2} / ^25μm 2), shows separation charge of the glass substrate a relationship between the (V) in FIG. 8.

From the results of Table 1 and FIG. 8, it was found that the amount of peeling charge can be reduced by satisfying both the conditions of both the average opening area and the total opening area of the holes in the glass substrate. It is considered that this is because cleaning with calcium carbonate is more effective than cleaning with cerium oxide while maintaining the surface condition of the glass substrate. That is, in the case of cleaning with cerium oxide, the easily etched portion of the first surface surface layer of the glass substrate is scraped off due to the high polishing ability, while in the case of cleaning with calcium carbonate, the first surface surface layer of the glass substrate is scraped off. Only the dirt is removed, leaving the easily etched parts of the glass. Therefore, it can be considered that holes were easily formed by etching. Also, in the case of cleaning with calcium carbonate, it is easy to remove chemical by-products (gel silica, etc.) in polishing with a slurry containing cerium oxide that wraps around from the second surface to the first surface. Conceivable.

Although the present invention has been described in detail and with reference to specific embodiments, it is clear to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on October 15, 2015 (Japanese Patent Application No. 2015-203881), the contents of which are incorporated herein by reference.

The glass substrate for a display of the present invention is useful as a display substrate for a plasma display panel (PDP), a liquid crystal display device (LCD), an electroluminescence display (ELD), a field emission display (FED), or the like.

10 ... Glass substrate for display, 11 ... Glass plate, 12 ... Hole

Claims (9)

In a display glass substrate having a first surface and a second surface opposite to the first surface.
The first surface has a plurality of holes to be opened.
The average opening area of the holes is 1.70 × 10 ⁴ nm ² or less.
The total opening area of the hole state, and are ^{6.00 × 10 6 nm 2 / 25μm} 2 or more,
A glass substrate for a display, which is substantially free of alkali metal oxides. The glass composition is displayed in mass% based on oxides.
The content of SiO ₂ is 50 to 70% by mass,
Al ₂ O ₃ content is 10 to 20% by mass,
B ₂ O ₃ content is 0 to 15% by mass,
MgO content 0-10% by mass,
CaO content is 0 to 20% by mass,
SrO content is 0 to 20% by mass,
BaO content is 0 to 20% by mass,
MgO, CaO, SrO, is Ru 1-30% by mass and the total content of BaO,
A glass substrate for a display according to請Motomeko 1. The glass substrate for a display according to claim 1 or 2, wherein the second surface is a surface on which an electronic member is formed, and the first surface is a surface on which an electronic member is not formed. The display glass substrate according to any one of claims 1 to 3, wherein the arithmetic average roughness Sa of the first surface is 0.30 nm or more. The glass substrate for a display according to any one of claims 1 to 4, wherein the first surface and the second surface are rectangular and the length of one side is 1 m or more. It is a method for manufacturing a glass substrate for a display that does not substantially contain an alkali metal oxide.
It has a step of performing a glass etching process on the first surface of a glass plate having a first surface and a second surface opposite to the first surface.
In the step of said glass etching, said plurality of holes which open in the first surface, the average opening area 1.70 × ¹⁰ 4 nm ² or less, the total open area of 6.00 × ¹⁰ 6 ^nm 2 / 25μm ^A method for manufacturing a glass substrate for a display, which comprises forming the glass substrate so as to have two or more. The method for manufacturing a glass substrate for a display according to claim 6, further comprising a step of cleaning the glass plate with a slurry containing calcium carbonate before the step of performing the glass etching process. The method for manufacturing a glass substrate for a display according to claim 6 or 7, wherein the glass etching process is etching with a gas containing hydrogen fluoride. In the etching with the gas containing hydrogen fluoride, the gas containing the hydrogen fluoride reaction component is discharged from the reaction gas discharge port into the etching tank at 0.07 m / sec, and discharged from the reaction gas discharge port at 0.07 m / sec. 8. The concentration of hydrogen fluoride contained in the mixed gas when the gas discharged from the reaction gas discharge port is sucked together with the air around the reaction gas discharge port at 0.5 m / sec is 500 ppm to 1500 ppm. The method for manufacturing a glass substrate for a display according to.

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