JP5780487B2 - Manufacturing method of glass substrate - Google Patents

Description

  The present invention is a glass substrate manufacturing method that does not easily cause electrostatic charging even when contact peeling is performed, or a glass substrate that is difficult to stick even if contact is made between members of a glass substrate or a plate (surface plate, stage). It relates to the manufacturing method.

  Glass substrates are widely used as substrates for flat panel displays such as liquid crystal displays (LCDs). In addition, an alkali-free glass substrate that does not substantially contain an alkali metal oxide is used for flat panel displays, particularly LCDs and organic EL displays (OLEDs).

In the above applications, the alkali-free glass substrate is required to have the following characteristics.
(1) Excellent chemical resistance, specifically, excellent resistance to chemicals such as various acids and alkalis used in the photolithography-etching step,
(2) The strain point is high so that the glass substrate is not thermally contracted, specifically, the strain point is 600 ° C. or higher.

  The glass substrate is heated to several hundred degrees Celsius in processes such as film formation of flat panel display and annealing. The current polycrystalline silicon TFT-LCD has a process temperature of about 400 to 600 ° C. In this case, the glass substrate is required to have a high strain point, specifically, a strain point of 600 ° C. or higher.

In order to efficiently produce a non-alkali glass substrate having a large area and a small plate thickness, the following characteristics are also required.
(3) Excellent meltability so that melting defects such as bubbles, bumps, striae, etc. are less likely to occur in the glass.
(4) Excellent devitrification resistance so that foreign matter generated during melting or molding does not enter the glass substrate.

JP 2001-343632 A Japanese Patent Laid-Open No. 2002-72922

  By the way, in the alkali-free glass substrate, electrostatic charging often becomes a problem. Glass that is originally an insulator is very easily charged. However, alkali-free glass that does not substantially contain an alkali metal oxide is particularly easy to be charged, and there is a tendency that once charged static electricity is maintained without escaping. In the manufacturing process of LCDs and OLEDs, the glass substrate is charged in various processes. In particular, so-called peeling charging that occurs due to contact peeling between a metal or an insulator plate in a film forming process or the like is a serious problem. Charging due to contact and peeling between the glass substrate and the plate occurs in a vacuum process such as a step of etching a thin film on the surface of the glass substrate or a film forming step as well as a step in atmospheric pressure. When a conductive substance approaches the charged glass substrate during these steps, discharge occurs. Since the charged electrostatic voltage reaches several tens of kV, the discharge causes the destruction of elements and electrode wires on the surface of the glass substrate, or in some cases the glass itself (insulation breakdown or electrostatic breakdown), resulting in poor display. Cause. Among LCDs, active matrix type LCDs represented by TFT-LCDs have fine semiconductor elements such as thin film transistors and electronic circuits formed on the surface of glass substrates, but these elements and circuits are very vulnerable to electrostatic breakdown. This is particularly problematic. In addition, the charged glass substrate attracts dust present in the environment, which causes surface contamination of the glass substrate.

  Further, as a secondary problem, a glass substrate with a smooth surface tends to stick to a metal or ceramic plate, and when the plate is peeled off, a problem such as breakage of the glass substrate may occur. The charging of the glass substrate and the plate also affects the sticking.

  As an antistatic measure for the glass substrate, a method of neutralizing the charge using an ionizer or increasing the humidity in the environment and discharging the stored charge into the air is often used. However, these antistatic measures not only cause an increase in cost, but also have a problem that it is difficult to take effective measures because there are various places that cause charging during the process. Furthermore, these antistatic measures cannot be applied in a vacuum process such as a plasma etching process or a film forming process. Therefore, for flat panel display applications such as LCD and OLED, a glass substrate that is difficult to be charged even in a vacuum process is strongly demanded (see Patent Documents 1 and 2).

  On the other hand, high surface accuracy is desired for the surface of the glass substrate on the side not in contact with the various plates. This surface is generally referred to as the priority guarantee surface of the glass substrate, or simply the “front surface”. For example, in a manufacturing process of a thin film transistor type LCD, devices for driving various wiring films and pixels are formed as thin films on a priority guarantee surface of a glass substrate. If the priority guarantee surface of the glass substrate is scratched or soiled, or if the unevenness of the priority guarantee surface is large, the wiring film is disconnected or the TFT is poorly formed, causing a display defect. For this reason, in the IPS system and the ultra-high-definition LCD, which are attracting attention as a wide viewing angle technology for TV, requirements for scratches and dirt on the priority guarantee surface of the glass substrate are very strict. In addition, in OLEDs that are attracting attention as next-generation displays, a high-definition driving circuit using low-temperature p-Si (LTPS) is formed on the priority guarantee surface of the glass substrate. Smoothness has become very important.

  Accordingly, the technical problem of the present invention is to provide a method for producing a glass substrate that is difficult to cause charging in the manufacturing process of various displays, and that is difficult to stick to a plate, and that does not easily cause a disconnection of a wiring film or formation failure of a TFT. Is to provide.

As a result of intensive studies, the inventors have regulated the average surface roughness Ra of both surfaces of the glass substrate excluding the end face to a predetermined range, and chemically treating one surface of the glass substrate with a predetermined chemical solution. The present inventors have found that the above technical problem can be solved and propose as the present invention. That is, the method for producing a glass substrate of the present invention is a method for producing a glass substrate having a first surface and a second surface, wherein the average surface roughness Ra of the first surface is 0.2 nm or less, and before chemical treatment. of the second surface of the glass substrate and fire-polished surface, so that the average surface roughness Ra of the second surface is 0.3～1.5Nm, a chemical solution containing HF 0.1 to 5 wt% The second surface is chemically treated using an impregnated roller or pad . The “first surface” refers to one surface (usually the priority guarantee surface) of the glass substrate excluding the end surface, and the “second surface” refers to the other surface of the glass substrate excluding the end surface. .

  As a method for reducing charging of the glass substrate, particularly peeling charging and sticking between the plate, a method of microscopically reducing the contact area between the glass substrate and the plate is the most effective. When the glass substrate and the plate come into contact with each other with a strong force, electrons are exchanged at the interface between the two. Then, when both are peeled off, charging occurs. Therefore, by regulating the average surface roughness Ra of the second surface of the glass substrate within an appropriate range, the contact area between the glass substrate and the plate can be reduced, and as a result, the charge amount can be reduced. Further, a glass substrate that is easily charged and has a very high surface smoothness has a feature that it is very likely to stick to the plate when adsorbed on the plate. Therefore, by regulating the average surface roughness Ra of the second surface of the glass substrate to an appropriate range, the contact area between the glass substrate and the plate can be reduced, and as a result, the glass substrate can be prevented from sticking. Can do.

  The larger the average surface roughness Ra of the second surface of the glass substrate, the easier it is to prevent charging due to contact peeling and sticking to the plate. However, if the average surface roughness Ra of the second surface of the glass substrate is too large, the surface strength of the glass substrate may be impaired, and the surface of the glass substrate may be further increased in the chemical treatment process in the manufacturing process of various displays. As a result, erosion may occur and defects may occur in the display of various displays. On the other hand, if the average surface roughness Ra of the second surface of the glass substrate is too large, the process cost of the chemical treatment increases, and secondary defects such as contamination of the glass substrate tend to occur. Therefore, if the second average surface roughness Ra of the glass substrate is regulated to 0.3 to 1.5 nm, the process cost is unreasonably increased while effectively preventing peeling charging and sticking of the glass substrate. Without lowering the strength or the like of the glass substrate. Here, the “average surface roughness Ra” is sufficient if 70% or more of the second surface of the glass substrate has a predetermined average surface roughness Ra, and in particular, a plurality of locations within the surface of the glass substrate. The average value is desirable. In other words, even if a specific location on the surface of the glass substrate (for example, a peripheral portion or corner portion of the glass substrate) is larger than 1.5 nm, or conversely smaller than 0.3 nm, the second (or first) of the glass substrate. If the average surface roughness Ra is 70% or more, preferably 80% or more of the surface, the effect of the present invention can be obtained in accordance with the gist of the present invention.

Process for producing a glass substrate of the present invention, by a chemical solution containing H F 0.1 to 5 wt%, characterized by chemically treating the second surface of the glass substrate. If it does in this way, it will become easy to make average surface roughness Ra of the 2nd surface of a glass substrate 0.3-1.5 nm . The concentration of H F is from 0.1 to 3 wt%, preferably from 0.1 to 1.5 wt%. The processing temperature is 50 ° C. or lower, 5 ° C. to 40 ° C., particularly 10 ° C. to 30 ° C. The treatment time is 0.5 seconds to 3 minutes, 1 second to 2 minutes, particularly 5 seconds to 1 minute. If the processing temperature is lower than 5 ° C. and the processing time is shorter than 0.5 seconds, the average surface roughness Ra of the second surface of the glass substrate is difficult to increase. On the other hand, when the processing temperature is higher than 40 ° C., the vaporization of hydrogen fluoride vapor becomes a problem, and when the processing time is longer than 3 minutes, the process cost of the glass substrate increases. Further, in order to prevent reaction products generated by chemical treatment, mineral acids such as H ₂ SO ₄ , HNO ₃ , and HCl can be added to the chemical solution up to 20% by mass.

When the surface of the glass substrate is roughened by chemical treatment using a chemical solution, it may be a problem that the preferential guarantee surface of the glass substrate is eroded. In order to prevent this problem, it is necessary to devise the configuration of the apparatus and the like to chemically treat only one surface (second surface) of the glass substrate. In the present invention, a method is used in which a chemical solution is contained in a roller or pad made of a material that can be impregnated with the chemical solution, and the chemical solution is applied to the surface of the glass substrate .

  The glass substrate of the present invention regulates the average surface roughness Ra of the first surface to 0.2 nm or less. In this way, devices for driving various wiring films and pixels can be formed on the surface of the glass substrate with high precision, and as a result, disconnection of the thin film wiring film, TFT formation failure, etc. can be prevented accurately. can do.

Process for producing a glass substrate of the present invention, it is preferred processing time of chemical treatment is 3 minutes 0.5 seconds. If it does in this way, it will become easy to make average surface roughness Ra of the 2nd surface of a glass substrate 0.3-1.5 nm. Here, the “treatment time” means a time during which the surface of the glass substrate is actually in contact with the chemical (including a state where the transport process is carried in a state wet with the chemical). In addition, in the process of chemically treating and cleaning a very large glass substrate continuously, the processing time per glass substrate may exceed this range.

In the method for producing a glass substrate of the present invention, it is preferable to use a chemical solution containing 0.1 to 5% by mass of HF and perform chemical treatment while keeping the temperature of the chemical solution at 50 ° C. or lower.

It is preferable that the manufacturing method of the glass substrate of this invention does not chemically process the 1st surface. In this way, the average surface roughness Ra of the first surface of the glass substrate does not increase, and it becomes easy to form devices for driving various wiring films and pixels on the surface of the glass substrate with high accuracy.

In the method for producing a glass substrate of the present invention, the average surface roughness Ra of the second surface before chemical treatment is preferably 0.2 nm or less. In this way, the second surface of the glass substrate can be chemically treated uniformly.

Process for producing a glass substrate of the present invention, by forming a glass substrate with a down draw method, it is preferable that the first front surface of the glass substrate to the fire-polished surface.

Process for producing a glass substrate of the present invention is preferably a substrate size of the glass substrate is 0.2 m ² or more.

Process for producing a glass substrate of the present invention, it is preferable thickness of the glass substrate is 0.6mm or less.

Process for producing a glass substrate of the present invention, the glass substrate is a glass composition including, by mass% terms of _{oxide, SiO 2 50~70%, Al 2} O 3 10~20%, B 2 O 3 0~15 %, MgO + CaO + SrO + BaO 1~30%, 0~10% MgO, CaO 0~20%, SrO 0~20%, containing BaO 0 to 20%, and preferably does not substantially contain an alkali metal oxide. Here, “substantially no alkali metal oxide” refers to a case where the content of the alkali metal oxide in the glass composition is 1000 ppm or less.

The method of manufacturing a glass substrate of the present invention is a surface the first surface electrode lines and various devices are formed, it is preferable and a second surface which is a surface electrode lines and various devices are not formed. In this way, it is possible to accurately form devices for driving various wiring films and pixels on the surface of the glass substrate while preventing charging during the process or sticking to the plate.

  In the method for producing a glass substrate of the present invention, since the average surface roughness Ra of both surfaces of the glass substrate excluding the end face is regulated within a predetermined range, charging during the process or sticking to the plate is prevented. On the other hand, devices for driving various wiring films and pixels can be formed with high accuracy on the surface of the glass substrate. Moreover, since the manufacturing method of the glass substrate of this invention uses a predetermined | prescribed chemical | medical solution, it is easy to optimize average surface roughness Ra of the 2nd surface of a glass substrate in a short time. Therefore, the glass substrate manufactured by this method has a low peel charge amount, and can suppress static charge generated in the manufacturing process of LCDs, OLEDs, etc., thus preventing destruction of elements and wiring on the glass substrate. As a result, the manufacturing efficiency of LCDs and OLEDs can be increased. Moreover, the glass substrate produced by this method is difficult to stick to the plate in the manufacturing process of LCDs, OLEDs, etc., and can avoid the problem that the glass substrate is damaged.

It is explanatory drawing which shows the apparatus used for measurement of peeling charge amount, (a) is explanatory drawing which shows the state which mounted the glass substrate, (b) is explanatory drawing which shows the state which contact | adhered the glass substrate and plate. .

  In the method for producing a glass substrate of the present invention, the average surface roughness Ra of the second surface of the glass substrate is 0.3 to 1.5 nm, preferably 0.4 to 1.2 nm, more preferably 0.5 to 1. 0.0 nm. The larger the average surface roughness Ra of the second surface of the glass substrate, the smaller the charge amount, but if the average surface roughness Ra is too large, a large defect is likely to occur on the surface of the glass substrate, The strength of the glass substrate tends to decrease. Moreover, the larger the average surface roughness Ra, the higher the cost and time for chemical treatment, and the higher the manufacturing cost of the glass substrate. Therefore, the average surface roughness Ra of the second surface of the glass substrate is regulated within an appropriate range, and the strength of the glass substrate is prevented from lowering, and the glass substrate is prevented from being charged without lowering the productivity. There is a need.

  In the method for producing a glass substrate of the present invention, the initial surface state of the glass substrate is very important in order to improve the accuracy of chemical treatment, particularly uniformity. From such a viewpoint, in the method for producing a glass substrate of the present invention, the average surface roughness Ra of the second surface of the glass substrate before chemical treatment is preferably 2 nm or less.

  In the method for producing a glass substrate of the present invention, the glass substrate is preferably formed by a down draw method, particularly an overflow down draw method. In this way, a glass substrate having a large area and good surface accuracy can be efficiently formed. In the glass substrate of the present invention, the first surface and the second surface of the glass substrate before chemical treatment are preferably as-formed surfaces (fire-making surfaces). In this way, the accuracy of the chemical treatment, in particular the uniformity, is increased, and the glass substrate manufacturing process can be simplified, and in particular, the polishing process can be omitted, thereby reducing the manufacturing cost of the glass substrate. Can do. Currently, among the downdraw methods, the most suitable method from the above viewpoint is the overflow downdraw method. In other molding methods, such as the float process, the surface of the glass substrate is contaminated by molten tin, and the minute surface irregularities called undulations degrade the display performance of the TFT-LCD, so the priority guarantee surface must be polished. It will not be a product. On the other hand, since the overflow downdraw method is less likely to cause the above-described problem, the polishing step can be omitted, and as a result, the manufacturing cost of the glass substrate can be reduced.

In the method for producing a glass substrate of the present invention, the substrate size of the glass substrate is preferably 0.2 m ² or more, 0.5 m ² or more, 0.6 m ² or more, particularly 1.0 m ² or more. A glass substrate having a large area easily stores static electricity, easily causes charging, and, when adhering to a plate by adsorption, the glass substrate is easily damaged in a subsequent lift-up process or the like. The method for producing a glass substrate of the present invention can be applied to a glass substrate having a large area, and in that case, the obtained effect is great.

  In the method for producing a glass substrate of the present invention, the thickness of the glass substrate is preferably 0.6 mm or less, particularly preferably 0.5 mm or less. A glass substrate having a small plate thickness is likely to be damaged in a subsequent lift-up process when the glass substrate adheres to the plate by adsorption. The method for producing a glass substrate of the present invention can be applied to a glass substrate having a small plate thickness, and in that case, the obtained effect is great.

The method of manufacturing a glass substrate of the present invention, the glass substrate is a glass composition including, by mass% terms of _{oxide, SiO 2 50~70%, Al 2} O 3 10~20%, B 2 O 3 0~15 %, MgO + CaO + SrO + BaO 1 to 25%, MgO 0 to 10%, CaO 0 to 20%, SrO 0 to 20%, BaO 0 to 20%, and substantially no alkali metal oxide. The reason for limiting the content of each component in the glass composition as described above will be described below.

The content of SiO ₂ is 50 to 70%, preferably 55 to 65%. When the content of SiO ₂ is small, heat resistance, acid resistance and the like is reduced. On the other hand, when the content of SiO ₂ is large, the high-temperature viscosity is increased and the meltability is lowered. In addition, defects such as devitrified crystals (cristobalite) are likely to occur in the glass.

The content of Al ₂ O ₃ is 10 to 25%, preferably 12 to 23%, more preferably 13 to 20%. When the content of Al ₂ O ₃ is less than 10%, it is difficult to improve heat resistance. Further, Al ₂ O ₃ has a function of increasing the Young's modulus and the specific Young's modulus, but if the Al ₂ O ₃ content is less than 10%, the Young's modulus and the specific Young's modulus are likely to decrease. Note that when the specific Young's modulus decreases, the amount of bending of the glass substrate increases, and in particular, the amount of bending of a large-area glass substrate increases significantly. On the other hand, if the content of Al ₂ O ₃ is more than 25%, the chemical durability against hydrofluoric acid chemicals decreases, and as a result, after the chemical treatment according to the present invention, the roughness of the glass substrate surface varies. Is likely to occur.

B ₂ O ₃ is a component that acts as a flux, lowers the high temperature viscosity, and increases the meltability, and its content is 0 to 15%, preferably 1 to 13%. When the content of B ₂ O ₃ is small, the function as a flux becomes insufficient, the high-temperature viscosity becomes high, and the bubble quality of the glass substrate tends to be lowered. On the other hand, when the content of B ₂ O ₃ is large, the average surface roughness Ra of the surface of the glass substrate is not so large due to the chemical treatment according to the present invention, and the heat resistance and Young's modulus are easily lowered.

  MgO + CaO + SrO + BaO is a component that lowers the liquidus temperature and makes it difficult to produce crystalline foreign matter in the glass, and is a component that improves meltability and moldability, and its content is 1 to 25%, Preferably it is 5 to 20%, more preferably 10 to 20%. When there is little content of MgO + CaO + SrO + BaO, the function as a flux cannot fully be exhibited and meltability falls. On the other hand, when the content of MgO + CaO + SrO + BaO is too large, the density increases and the specific Young's modulus decreases.

  MgO is a component that lowers the viscosity at high temperature and improves the meltability without lowering the strain point, and is the component that has the effect of reducing the density most among the alkaline earth metal oxides, and its content is 0 -10%, preferably 0-8%, more preferably 0-6%, still more preferably 0-5%, most preferably 0-3%. However, when there is much content of MgO, liquidus temperature will rise and devitrification resistance will fall easily.

  CaO is a component that lowers the viscosity at high temperature and significantly increases the meltability without reducing the strain point, and has a high effect of suppressing devitrification in the glass composition system according to the present invention, and is an alkaline earth metal. If the content of the oxide is relatively increased, the density can be easily reduced. When there is much content of CaO, a thermal expansion coefficient and a density will rise too much, the balance of a glass composition will be impaired, and devitrification resistance will fall easily conversely. Therefore, the content of CaO is 0 to 20%, preferably 0 to 15%, more preferably 1 to 10%.

  SrO and BaO are components that lower the high-temperature viscosity and increase the meltability without lowering the strain point. However, when the content of SrO and BaO is large, the density and the thermal expansion coefficient tend to increase. The SrO content is 0 to 20%, preferably 0 to 15%, more preferably 0 to 10%. Further, the content of BaO is 0 to 20%, preferably 0 to 15%.

  In addition to the above components, other components can be added to the glass composition in a total amount of 10%, preferably up to 5%.

ZrO ₂ is a component that increases the Young's modulus, and its content is preferably 0 to 5%, 0 to 3%, 0 to 0.5%, particularly preferably 0 to 0.2%. When the content of ZrO ₂ is large, the liquidus temperature rises and zircon devitrification crystals are likely to precipitate.

TiO ₂ is a component that lowers the high-temperature viscosity and increases the meltability, and is a component that suppresses solarization. However, when it is contained in the glass composition in a large amount, the glass is colored and the transmittance is lowered. Therefore, the content of TiO ₂ is preferably 0 to 5%, 0 to 3%, 0 to 1%, particularly preferably 0 to 0.02%.

P ₂ O ₅ is a component that enhances devitrification resistance. However, when a large amount of P ₂ O ₅ is contained in the glass composition, the water resistance is significantly lowered in addition to the occurrence of phase separation and milk white in the glass. Therefore, the content of P ₂ O ₅ is preferably 0 to 5%, 0 to 1%, particularly preferably 0 to 0.5%.

Y ₂ O ₃ , Nb ₂ O ₅ and La ₂ O ₃ have a function of increasing the strain point, Young's modulus, and the like. However, if the content of these components is more than 5%, the density tends to increase.

As a fining agent, SnO ₂ , F, Cl, SO ₃ , C, or metal powder such as Al or Si can be added up to about 2%. Further, as a fining agent, CeO ₂ or the like may also be added up to about 2%.

  Halogens such as F and Cl have the effect of accelerating the melting of the alkali-free glass. If these components are added, the melting temperature can be lowered and the action of the fining agent is promoted. The lifetime of the glass production kiln can be extended while reducing the melting cost.

[Preparation of sample]
Table 1 shows preferred glass compositions and their characteristics as alkali-free glass substrates. Each sample in the table was prepared as follows. First, glass raw materials were prepared so as to have the glass composition in the table, and were melted using a platinum pot at 1600 ° C. for 24 hours. Next, the obtained molten glass was poured onto a carbon plate and formed into a flat plate shape. About the obtained glass, the characteristic in a table | surface was evaluated.

  The density is a value measured by a well-known Archimedes method.

  The thermal expansion coefficient is a value measured with a dilatometer, and is an average value in a temperature range of 30 to 380 ° C.

  The strain point is a value measured based on the method of ASTM C336.

  The softening point is a value measured based on the method of ASTM C338.

The temperature corresponding to the high temperature viscosity of 10 ^2.5 dPa · s is a value measured by a platinum ball pulling method.

  The Young's modulus is a value measured by a resonance method.

  The liquid phase temperature is obtained by crushing glass, passing through a standard sieve 30 mesh (a sieve opening of 500 μm), putting the glass powder remaining at 50 mesh (a sieve opening of 300 μm) in a platinum boat, and keeping it in a temperature gradient furnace for 24 hours. Then, the temperature at which the crystal is deposited is measured.

  The liquid phase viscosity is a value obtained by measuring the viscosity of glass at the liquid phase temperature TL by a platinum ball pulling method.

  Next, sample Nos. 3 was melted in a production facility of actual production, formed into a 0.5 mm thick flat plate shape by the overflow down draw method, and the obtained glass was cut into 400-500 mm size, washed, and used as a glass substrate for LCD An appropriate quality glass substrate was obtained. This glass substrate was subjected to various chemical treatments and used for peel charge evaluation and stickiness evaluation.

  Table 2 shows the results of peel charge evaluation and stickiness evaluation. In addition, the surface of the glass substrate (sample Nos. 3-1 to 3-7) before the chemical treatment is a fire-making surface on both sides (first surface and second surface), and the average surface roughness Ra is 0.00. It was 15 nm.

Next, sample No. About 3-2 to 3-6, the glass substrate was chemically processed with the chemical | medical solution as described in a table | surface. Conditions for chemical treatment are as described in the table. That is, sample no. 3-2 to 3-4 were chemically treated by immersing the glass substrate in a 1% by mass HF aqueous solution (hydrofluoric acid). The immersion conditions were 25 ° C., 15 seconds (Sample No. 3-2), 30 seconds (Sample No. 3-3), and 60 seconds (Sample No. 3-4). After the chemical treatment, the glass substrate was washed with pure water and dried, and used for the following evaluation. Sample No. For 3-5 and 3-6, it was chemically treated by immersing the glass substrate in an aqueous solution containing 1 wt% of HF and 10 wt% _H 2 SO _4. The immersion conditions were 25 ° C., 15 seconds (Sample No. 3-5), and 30 seconds (Sample No. 3-6). After the chemical treatment, the glass substrate was washed with pure water and dried, and used for the following evaluation. Furthermore, sample no. Next, the glass substrate was chemically treated by immersing the glass substrate in a 40 mass% NH ₄ F aqueous solution (ammonium fluoride aqueous solution). Immersion conditions are 40 ° C. and 3 minutes. After the chemical treatment, the glass substrate was washed with pure water and dried, and used for the following evaluation.

[Measurement of average surface roughness Ra]
A range of 10 μm square was measured using AFM (D3000, manufactured by Veeco, cantilever: Si), and the average surface roughness Ra in the plane was calculated. Specifically, the surface roughness Ra was measured at nine locations in the central portion and the peripheral portion (inside the end of the substrate 50 mm) in the glass substrate, and the average value was calculated.

[Peeling charge evaluation]
For the peeling electrification evaluation, an apparatus as shown in FIG. 1 was used. This apparatus has the following configuration.

  The support 1 for the glass substrate G includes a pad 2 made of Teflon (registered trademark) that supports the corners of the glass substrate 4. Further, the support base 1 is provided with a plate 3 made of metal aluminum that can be raised and lowered. By moving the plate 3 up and down, the glass substrate G and the plate 3 are brought into contact with and separated from each other, and the glass substrate G is charged. Can do. The plate 3 is grounded. Further, a hole (not shown) is formed in the plate 3, and this hole is connected to a diaphragm type vacuum pump (not shown). When the vacuum pump is driven, air is sucked from the holes of the plate 3, whereby the glass substrate G can be vacuum-adsorbed to the plate 3. Further, a surface potential meter 4 is installed at a position 10 mm above the glass substrate G, whereby the amount of charge generated at the center of the glass substrate G can be continuously measured. Further, an air gun 5 with an ionizer is installed above the glass substrate G, whereby the charge on the glass substrate G can be neutralized. The plate size of this device is 350-450 mm.

A method of measuring the peel charge amount using this apparatus will be described. The experiment is performed in an environment of 20 ° C. ± 1 ° C. and humidity 40% ± 1%. Since this amount of charge changes greatly under the influence of humidity in the atmosphere, particularly in the atmosphere, it is necessary to pay particular attention to the management of humidity.
(1) Place the glass substrate on the support table 1 with the chemically treated surface (second surface) facing down.
(2) The glass substrate is neutralized to 10 V or less by the air gun 5 with an ionizer.
(3) The plate is raised and brought into contact with the glass substrate and vacuum-adsorbed to bring the plate and the glass substrate into close contact for 30 seconds.
(4) The glass substrate is peeled by lowering the plate, and the charge amount generated at the center of the glass substrate is continuously measured with a surface potentiometer.
(5) Repeat (3) and (4), and continuously perform peeling electrification evaluation 5 times in total.
(6) The maximum charge amount in each measurement is obtained, and these are integrated to obtain the peel charge amount.

[Evaluation of stickiness]
For an unchemically treated glass substrate (equivalent to sample No. 3-1) and a chemically treated glass substrate (sample Nos. 3-2 to 3-7), the unchemically treated surface and the chemically treated surface face each other. After being superposed, they were placed on a flat plate and evenly applied with a weight of 10 kg and left for 30 minutes. For comparison, Sample No. Evaluation for 3-1 was performed in the same manner. Next, both glass substrates were peeled off, and “◯” indicates that the glass substrate was peeled off immediately, “Δ” indicates that it was difficult to peel off, and “X” indicates that the glass substrate could not be peeled without breakage.

[Evaluation results]
As apparent from Table 2, the sample No. In 3-2 to 3-7, since the average surface roughness Ra of the glass substrate was 0.4 to 1.0 nm, the peel charge amount was low, and the glass substrate was not damaged in the evaluation of stickiness. On the other hand, sample No. No. 3-1, the peel charge amount was high, and the glass substrate was damaged in the evaluation of stickiness. In addition, this time, No. Although various evaluations were performed using the sample No. 3, it is considered that the same evaluation results can be obtained with other samples (Nos. 1, 2, 4 to 8).

Claims (11)

In the method for producing a glass substrate having a first surface and a second surface,
The average surface roughness Ra of the first surface is 0.2 nm or less,
The second surface of the glass substrate before chemical treatment is a fire-making surface,
The average surface roughness Ra of the second surface is 0.3 to 1.5 nm.
A method for producing a glass substrate, wherein the second surface is chemically treated using a roller or pad impregnated with a chemical solution containing 0.1 to 5% by mass of HF.   The method for producing a glass substrate according to claim 1, wherein the chemical treatment time is 0.5 seconds to 3 minutes.   The method for producing a glass substrate according to claim 1 or 2, wherein the chemical treatment is performed after the temperature of the chemical solution is maintained at 50 ° C or lower.   The method for producing a glass substrate according to any one of claims 1 to 3, wherein the chemical treatment is performed after the temperature of the chemical solution is maintained at 5 to 40 ° C.   The method for producing a glass substrate according to any one of claims 1 to 4, wherein the first surface is not chemically treated.   The method for producing a glass substrate according to any one of claims 1 to 5, wherein the average surface roughness Ra of the second surface before chemical treatment is 0.2 nm or less.   The method for producing a glass substrate according to any one of claims 1 to 6, wherein the glass substrate is formed by a downdraw method, and the first surface of the glass substrate is used as a fired surface. The substrate size of a glass substrate is 0.2 m < ² > or more, The manufacturing method of the glass substrate in any one of Claims 1-7 characterized by the above-mentioned.   The thickness of the glass substrate is 0.6 mm or less, The method for producing a glass substrate according to claim 1. Glass substrate, as a glass composition, in weight percent terms of _{oxide, SiO 2 50~70%, Al 2} O 3 10~20%, B 2 O 3 0~15%, MgO + CaO + SrO + BaO 1~30%, MgO 0 10 to 10%, CaO 0 to 20%, SrO 0 to 20%, BaO 0 to 20%, and substantially no alkali metal oxide. Glass substrate manufacturing method.   The first surface is a surface on which electrode wires and various devices are formed, and the second surface is a surface on which electrode wires and various devices are not formed. Glass substrate manufacturing method.