JP2005247687A - Chemical processing method of glass substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical processing method of a glass substrate capable of producing various glass substrates for FPD having high flatness with reduced thickness. <P>SOLUTION: The glass substrate is immersed in a chemical processing solution, which is replaced with a new chemical processing solution before its quality is degraded by the increase in the number of reaction products, and a part or the whole of the surface of the substrate is processed at a polishing velocity of 10 μm/min or less. The chemical processing solution contains hydrofluoric acid and at least one inorganic acid selected from among hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid and/or a reattachment prevention agent to prevent the reattachment of the reaction products on the surface of the glass substrates. An anionic surfactant or an amine-based surfactant is favorably selected as the reattachment prevention agent. A chemical processing equipment is exhibited in the figure as an example. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes one or a pair of various FPD (flat panel display) glass substrates, such as LCD (liquid crystal display) glass substrates, PDP (plasma display panel) glass substrates, and organic EL (electroluminescence) glass substrates. The present invention relates to a chemical processing method for performing processing to polish and thin a bonded substrate.

Conventional glass substrate processing methods include physical methods and chemical methods. The physical method includes processing using a machine and processing by blasting, and the chemical method includes processing by wet etching. Recently, there is a trend to demand quality improvement as shown below.
1) Eliminate surface scratches originally present on the glass substrate.
2) Eliminate pattern traces remaining on the substrate from which the patterned thin film has been peeled off.
3) The entire thickness of one side of the outer surface of the glass substrate is reduced to increase its flatness.
4) Thin all sides of the outer surface of the glass substrate to improve its flatness.
5) A recessed part is produced in a part of one side of the outer surface of the glass substrate, and the dimensions of each part and the flatness of each surface are improved.
6) A dent part is produced in a part of both sides of the outer surface of a glass substrate, and the dimension of each part and the flatness of each surface are improved.
7) The glass substrate of 3) to 6) is read as two bonded substrates, and the same purpose is performed.

  Among the quality improvement items, for example, in the processing using a conventional machine, for example, mechanical polishing, for example, 1) to 4), lack of flatness, generation of cracks and surface scratches, residual polishing pattern, polishing ability Inevitable issues such as limitations remain. On the other hand, with conventional wet etching processing, it is difficult to eliminate surface scratches and traces that originally exist on the glass substrate, and various problems occur as shown in the following examples even when the plate thickness is reduced. It has been difficult to ensure a quality equivalent to or better than that of raw glass. In the following, description will be made on a liquid crystal glass substrate as a representative example.

  For example, in Patent Document 1, an element assembly is assembled by bonding a pair of glass substrates having an area corresponding to a plurality of liquid crystal display elements via seal materials surrounding the liquid crystal sealing regions of the respective element sections. Although a method for etching the outer surface of a liquid crystal glass substrate by immersing the body in an etching solution based on hydrofluoric acid has been disclosed, there is a problem that defects described later occur even though the plate thickness can be reduced.

  Patent Document 2 also includes a bubble generating device at the bottom of an etching solution tank that stores an etching solution containing hydrofluoric acid, and the etching solution is stirred by bubbles generated from the bubble generating apparatus. Although an invention of an automatic etching apparatus that etches the surface of the inserted glass is disclosed, when the outer surface of the liquid crystal glass substrate is processed using 15 to 17% hydrofluoric acid, there is a problem that defects described later occur.

In this invention, the processing liquid is agitated by nitrogen gas rising bubbles to achieve uniform processing of the glass surface. However, the flow that descends after the rising bubbles and the processing liquid reach the liquid surface is the upward flow. This hinders the uniformity of the surface, and there is a problem that the surface is not processed uniformly.
Japanese Patent No. 2722798 JP, 2000-147474, A The problems at the time of processing 50-300 micrometers by the conventional wet etching shown in the above-mentioned two examples are shown below. 1) White turbidity that can be confirmed even under fluorescent lamps occurs. 2) Pits with a maximum diameter of 0.2 mm are generated. FIG. 14 is a graph showing the results of measurement by a surface roughness meter after processing. 3) The pit diameter increases with the amount of machining. FIG. 15 is a graph showing the relationship between the pit diameter and the machining amount. 4) Up to 50 pits / cm 2 are generated. FIG. 16 is a graph showing the relationship between the number of pits per unit area and the machining amount. It can be seen from FIG. 16 that the number of pits per unit area increases as the processing amount increases. 5) An undulation that can be seen under a fluorescent lamp occurs. FIG. 17 is a graph showing the state of undulation on the surface after processing. 6) The difference between the maximum value and the minimum value of the plate thickness is 20 to 100 μm, which is not uniform. 7) Surface flaws artificially applied before processing increase in width and depth due to processing (see FIGS. 18 and 19). FIG. 18 is a graph showing a cross section of the surface intentionally scratched before processing, and FIG. 19 is a graph showing a cross section of the surface after processing.

  In addition, for example, when color filter pixels are patterned after sputtering Cr on a liquid crystal glass substrate, when the substrate becomes defective, the patterned Cr is usually removed and mechanical polishing is performed to erase the pattern traces. However, when conventional wet etching is performed instead of mechanical polishing, the pattern traces do not disappear and cannot be reused as raw glass.

  This invention is made | formed in view of this situation, and it aims at providing the chemical processing method of the glass substrate which can obtain various glass substrates for FPD with high flatness, reducing plate | board thickness.

  The present invention is a chemical processing method in which a glass substrate is immersed in a chemical processing solution and a part or all of one side constituting the outer surface of the glass substrate or a part or all of both sides is polished and thinned. The chemical processing method is characterized in that the chemical processing liquid before quality deterioration due to an increase in reaction products is replaced with a new chemical processing liquid and processed at a processing speed of 10 μm / min or less. .

  The chemical working liquid preferably contains hydrofluoric acid and one or more inorganic acids selected from hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid. Moreover, it is preferable that the said chemical processing liquid contains the anti-redeposition agent which prevents that the reaction product adheres again on the glass substrate surface. Examples of the anti-redeposition agent include an anionic surfactant and an amine surfactant. An ultrasonic vibrator or an oscillating stirring blade may be operated on the chemical working fluid containing the anti-redeposition agent.

  In addition, it is preferable that the glass substrate is arranged substantially vertically in the chemical processing liquid, and the rising liquid flow is generated by the bubbles generated continuously in the chemical processing liquid. It is preferable to overflow the chemical working fluid containing the product from the chemical working fluid storage tank.

  The present invention is a glass substrate processed by the chemical processing method and a flat panel display manufactured using the glass substrate.

  As described in detail above, according to the chemical processing method of the present invention, various glass substrates for FPD with high flatness can be manufactured by reducing the thickness of the glass substrate by chemically processing the glass substrate.

  In the present invention, a glass substrate (hereinafter collectively referred to as a “glass substrate”) once manufactured as a glass substrate for glass or for various FPDs is processed. And this invention immerses such a glass substrate in a chemical processing liquid, and processes at least one part of the outer surface of a glass substrate under specific conditions, thereby reducing the plate thickness and flattening the surface. An object of the present invention is to provide various glass substrates for FPD that are excellent in properties.

  The chemical processing liquid used in the present invention preferably has a glass substrate processing speed in the range of 0.5 to 10 μm / min, and more preferably in the range of 1.0 to 5.0 μm / min. According to the study of the present inventor, when the processing speed exceeds 10 μm / min, it becomes difficult to produce a glass substrate having excellent flatness. On the other hand, if the processing speed is less than 0.5 μm / min, a glass substrate excellent in flatness can be produced, but the production speed becomes too slow, which is not preferable from the viewpoint of productivity.

  Specifically, when the processing speed exceeds 10 μm / min, pits and undulation are likely to occur on the surface of the glass substrate after processing, and the variation in plate thickness increases, so that the flatness of the glass substrate cannot be ensured sufficiently. . Furthermore, scratches that originally existed on the substrate surface before processing remain. On the other hand, when the processing speed is in the range of 0.5 to 10 μm / min, the above problem can be solved and a glass substrate having excellent flatness can be manufactured.

  If the processing speed as described above can be obtained, the components of the chemical working fluid are not particularly limited, but preferred components for the present invention include hydrofluoric acid, ammonium fluoride, potassium fluoride, fluoride fluoride. Fluoride selected from sodium, inorganic acid selected from hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, organic acid selected from acetic acid, succinic acid, anionic surfactant such as sulfonate surfactant, amine-based amphoteric Mention may be made of surfactants.

  Of the above components, hydrofluoric acid, fluoride, inorganic acid and organic acid are used to chemically process the glass substrate and prevent reaction products such as fluoride from reattaching to the surface of the glass substrate. The anionic surfactant and the amine amphoteric surfactant are added to prevent a reaction product such as fluoride from reattaching to the surface of the glass substrate.

  The chemical working fluid used in the present invention can be combined arbitrarily except that hydrofluoric acid is an essential component, and each component is appropriately selected according to the composition of the glass substrate used, the required processing speed, processing accuracy, and the like. Can be combined. According to the study of the present inventor, among the above components, a combination of hydrofluoric acid and an inorganic acid (especially hydrochloric acid and nitric acid), a combination of hydrofluoric acid and an anionic surfactant, hydrofluoric acid, an organic acid (especially hydrochloric acid) And nitric acid) and anionic surfactants have been found to be particularly suitable.

  Since the gist of the present invention is to immerse the glass substrate in the above-described chemical processing liquid, the storage tank for storing the chemical processing liquid and its peripheral devices are not particularly limited. For example, it is also possible to use a chemical processing apparatus consisting only of a storage tank that stores a chemical processing liquid. In this case, when processing the glass substrate, the reaction product such as silicofluoride gradually increases in the chemical processing solution, and as a result, many reaction products adhere to the surface of the glass substrate. It is also assumed that the solid-liquid reaction rate of the processing liquid tends to vary in each part on the glass substrate, and it becomes difficult to ensure the flatness of the surface of the glass substrate. However, before the quality of the chemical working fluid is deteriorated by prior examination, the flatness of the glass substrate surface, which is the main object of the present invention, is sufficiently secured by using the chemical working fluid by replacing it with a new one. be able to.

  Another preferred example of the chemical processing apparatus is to continuously remove the chemical processing liquid containing reaction products during chemical processing from the chemical processing liquid storage tank and continuously supply new chemical processing liquid. A chemical processing apparatus capable of When such chemical processing equipment is adopted, reaction products generated after processing are removed outside the storage tank (outside the reaction system), and fresh chemical processing liquid containing only active ingredients is always stored in the storage tank (reactions). Therefore, uniform chemical processing of the glass substrate surface is possible.

  In the present invention, it is preferable to improve the flatness of the glass substrate while the chemical processing solution generates a liquid flow substantially parallel to the processing surface of the glass substrate. This is particularly effective when a glass substrate with low flatness having many fine irregularities on the substrate surface is processed before processing.

  The above operation and effect can be explained as follows. The chemical processing method in the present invention is a solid-liquid reaction between a glass substrate (solid) and a processing liquid (liquid). (1) Diffusion of the processing liquid into the diffusion layer constituting the vicinity of the glass substrate surface; 2) Adsorption of processing components on glass substrate surface, (3) Chemical reaction between processing components and glass, (4) Desorption of reaction products from glass substrate, (5) Reaction products out of diffusion layer It consists of multistage reactions such as diffusion. Among the above reactions, the reaction rates of (2) to (4) are larger than the reaction rates of (1) and (5), so the overall reaction rate of this multistage reaction is (1) and (5). It is determined by the reaction rate of, and is considered to be diffusion-limited.

  Here, when using a glass substrate with low flatness in which fine irregularities exist on the substrate surface, and causing a chemical processing liquid flow substantially parallel to the processing surface of the glass substrate, the substrate The convex portion on the surface is more strongly affected by the liquid flow than the concave portion. That is, in the convex portion, as a result of receiving a kind of stirring action by the liquid flow, the thickness of the diffusion layer is reduced, so that the diffusion rate of the machining liquid is increased, and the overall reaction rate (ie, the processing rate) is increased. On the other hand, the concave portion is hardly affected by the liquid flow, and the liquid flow near the concave portion is in a stagnation state, so the thickness of the diffusion layer near the concave portion hardly changes, and the overall reaction rate is smaller than that of the convex portion. Become.

  Here, for example, when the entire processing liquid is stirred with a stirrer or the like and the glass substrate is immersed in a nearly vertical state, the rising liquid flow does not effectively occur, so that the chemical processing is performed on the processing surface of the glass substrate. It becomes difficult to make the liquid flows substantially parallel. In order to effectively generate the rising liquid flow, a method of continuously generating fine bubbles such as nitrogen gas from the lower part of the processing liquid in a state where the chemical processing liquid is filled up to the top of the chemical processing liquid storage tank Can be mentioned. Then, by immersing the glass substrate in such a working liquid in a substantially vertical state, the processing surface of the glass substrate can be made substantially parallel to the rising liquid flow of the chemical working liquid.

  In the present invention, the processed portion of the glass substrate is not limited to both sides of the outer surface constituting the glass substrate, but is in the form required for various FPD glass substrates, for example, the patterning shape of the substrate surface, etc. Accordingly, only necessary processing portions can be processed appropriately. Specifically, for example, an acid-resistant protective film is formed on a portion that is not processed, and a masking process is performed. After the processing, the protective film is removed so that a part or all of one side of the glass substrate or both sides of the glass substrate are removed. Some can be chemically processed.

  Below, embodiment which processes a glass substrate using the latter chemical processing apparatus among the chemical processing apparatuses mentioned above is described concretely, referring drawings. FIG. 1 is a cross-sectional view showing an example of a chemical processing apparatus of the present invention. The chemical processing apparatus 1 is provided with a chemical processing liquid storage tank 11, and bubbles are generated at the bottom of the chemical processing liquid storage tank 11 to be introduced and discharged from a porous bubble discharge portion 12 a. The apparatus 12 is arranged, and a glass substrate storage jig 18 for inserting and holding a glass substrate or a pair of glass substrates bonded in the vertical direction is arranged on the upper side of the bubble generating device 12. Yes. The glass substrate storage jig 18 is disposed in the glass substrate storage jig holder 17. The chemical working liquid storage tank 11 is charged with a chemical working liquid mainly composed of hydrofluoric acid.

  An overflow liquid receiving tank 13 for receiving the chemical working liquid overflowed from the chemical working liquid storage tank 11 is provided at the peripheral edge of the chemical working liquid storage tank 11, and the overflow liquid receiving tank 13 is generated by processing. A filter 14 for removing the reaction product, and a pump 15 for sending the chemical working fluid filtered by the filter 14 to the chemical working fluid storage tank 11 again are connected. And the chemical processing liquid discharge part 16a which is distribute | arranged under the bubble generator 12 and has many holes for discharging the chemical processing liquid sent out by the pump 15 toward the bottom part of a chemical processing liquid storage tank is provided. The chemical working fluid is again supplied to the chemical working fluid storage tank 11 by the chemical working fluid discharge device 16.

  Further, the chemical processing apparatus 1 may be provided with an ultrasonic vibrator or a rocking stirring blade (not shown). This is used for diffusing bubbles throughout the chemical working fluid storage tank 11.

  FIG. 2 is a perspective view showing an example of the bubble generator 12. The bubble generation device 12 includes a gas introduction pipe 12b for introducing a gas such as nitrogen gas, and a plurality of porous pipe-like bubble discharge sections 12a, 12a,... Connected vertically to the gas introduction pipe 12b. It has. FIG. 3 is a perspective view showing an example of a bubble discharger 12a of another bubble generator 12. The bubble discharge portion 12a is made of a porous material and has a plate shape. In both FIG. 2 and FIG. 3, it is preferable that the hole diameter of the bubble discharge section 12a is 10 to 500 μm. Then, these bubble generating devices 12 are disposed below the holder 17 for the liquid crystal glass substrate storage jig, and fine bubbles are discharged upward to raise the chemical processing liquid uniformly. With this rising liquid flow, it is possible to always supply a fresh chemical working liquid to the surface of the glass substrate and to prevent reaction products such as fluoride from reattaching to the surface of the glass substrate.

  After the ascending liquid flow of fine bubbles reaches the surface of the chemical working liquid, it overflows from the peripheral edge of the chemical working liquid storage tank 11, is received by the overflow liquid receiving tank 13, passes through the filter 14, and then is again chemical. It is supplied to the machining liquid storage tank 11. When the chemical working fluid is not overflowed, if the cross-sectional area of the portion where the rising liquid flow turns into the falling liquid flow is small, the falling liquid flow intersects with the rising liquid flow, and a uniform rising liquid flow cannot be secured. FIG. 4 is a plan view showing an example of the chemical working fluid storage tank 11 and the glass substrate storage jig holder 17. As shown in FIG. 4, the passing cross-sectional area of the descending liquid flow corresponding to the outer portion of the glass substrate storage jig holder 17 is the rising liquid flow corresponding to the inner portion of the glass substrate storage jig holder 17. It is confirmed that a uniform ascending liquid flow can be secured when it is 1 to 3 times the passage cross-sectional area.

  A reaction product such as fluoride between the components of the glass substrate and the chemical processing liquid rises due to the upward flow of fine bubbles, but this circulates in the chemical processing liquid storage tank 11 to the bottom of the chemical processing liquid storage tank 11. Since deposition adversely affects the discharge of fine bubbles, it is necessary to prevent deposition of reaction products. FIG. 5 is a perspective view showing an example of the chemical processing liquid discharge device 16. The chemical working liquid discharge device 16 is provided with a plurality of chemical working liquid discharge parts 16a having a large number of holes in parallel, and the chemical working liquid discharged by the pump 15 is directed downward from the chemical working liquid discharge part 16a. Alternatively, it is preferable to design so as to prevent the deposition of the reaction product as well as the supply of the chemical working liquid by discharging obliquely downward.

  In the present invention, as a method for controlling the processing speed of the glass substrate using the above-described chemical processing apparatus 1, there are a change in the composition of the chemical processing liquid and a change in the temperature of the chemical processing liquid. FIG. 6 is a graph showing the relationship between the chemical working fluid addition ratio and the processing speed. This chemical processing solution is an aqueous solution in which the ratio of processing components consisting of 20 parts by weight of hydrofluoric acid, 20 parts by weight of hydrochloric acid and 20 parts by weight of nitric acid to water is appropriately changed. From FIG. 6, although the addition rate is 1.1 μm / min when the addition rate is 10%, the processing speed increases as the addition rate increases, and shows the maximum value of 3.7 μm / min at 40%, and then decreases slightly. It can be seen that the addition rate is approximately constant at 3 μm / min up to 90%. When the addition ratio is 30% or less, the processing speed is slow. When the addition ratio is 70% or more, white clouding occurs on the glass surface or reaction product sludge adheres to the glass surface. The ratio is preferably 30 to 60%. In addition, it has been confirmed that this relationship is the same even when a chemical working fluid comprising a combination of other processing components described above is used.

  FIG. 7 is a graph showing the relationship between the processing speed and the temperature of a chemical processing liquid composed of 5% hydrofluoric acid and 10% hydrochloric acid using the chemical processing apparatus 1. The horizontal axis of this graph is the amount of deviation from the reference temperature (30 ° C.), and the vertical axis is the machining speed. FIG. 7 shows that the processing speed tends to increase as the temperature rises as a whole, but only 0.5 μm / min is generated in the range of ± 5 ° C. of the reference temperature (30 ° C.). Thus, in the present invention, there exists a temperature region in which the machining speed hardly changes. Therefore, in chemical processing, the relationship between the processing speed and temperature is investigated in advance, and the processing speed of the glass substrate is determined by performing chemical processing near the intermediate temperature, with the intermediate temperature in the temperature region where the processing speed hardly changes as the reference temperature. Is preferably controlled. Further, by examining in advance a temperature region in which the machining speed hardly changes, the machining time condition can be set gently according to the required machining accuracy. For example, in the case where the graph of FIG. 7 is obtained, in order to keep the variation in the processing amount within the range of 20 μm, a maximum of 40 minutes is allowed as the variation in the processing time.

The present invention will be specifically described below based on examples.
[Embodiment 1] An example of chemical processing of raw glass using the above-described chemical processing apparatus 1 is shown below. The relationship between the processing speed and the surface state of the glass substrate when the following raw glass was immersed in a chemical processing solution having a predetermined processing speed and the same processing amount was polished was studied. The results are shown in Table 1.
(1) Raw glass size and target chemical processing amount
No.1: 320mm long x 400mm wide x 1.1mm thick. Target chemical processing amount: 0.3mm.
No.2: Length 400mm x width 500mm x thickness 0.7mm. Target chemical processing amount: 0.2mm.
(2) Chemical processing fluid composition water as a solvent, hydrofluoric acid, hydrochloric acid, nitric acid as chemical processing components, the processing rate is 0.5, 1.0, 3.0, 5.0, 10.0, 13.0 by appropriately changing the blending ratio of each component A chemical working solution to 15.0 (unit: μm / min) was prepared.

  In Table 1, the presence or absence of pits, undulations, and original scratches is the result of visual observation under a fluorescent lamp in a dark room. FIG. 8 shows the measurement position of the thickness of the No. 2 glass substrate after chemical processing. Table 1 shows the results obtained by measuring the plate thickness with an ultrasonic plate thickness meter at each position shown in FIG. 8 and obtaining the difference between the maximum value and the minimum value as variations. Here, “small” means that the variation is 50 μm or less, “medium” means 100 to 200 μm, and “large” means 200 μm or more. From the results of Table 1, it was found that the processing speed is preferably 0.5 to 10 μm / min, particularly 1.0 to 5.0 μm / min in terms of quality and productivity.

[Embodiment 2] An example of chemical processing of raw glass using the above-described chemical processing apparatus 1 is shown below.
(1) Raw glass size and target chemical processing amount
No.1: 320mm long x 400mm wide x 1.1mm thick. Target chemical processing amount: 0.3mm.
No.2: Length 400mm x width 500mm x thickness 0.7mm. Target chemical processing amount: 0.2mm.
(2) Composition of chemical working solution A chemical working solution containing 5% hydrofluoric acid, 10% hydrochloric acid and 5% nitric acid was used with water as a solvent.
(3) Raw glass acceptance inspection and final inspection method <plate thickness measurement>
The plate thickness at the measurement position shown in FIG. 8 was measured using an ultrasonic plate thickness meter.
<Appearance inspection>
Fluorescent lamp (1500Lx or more) and condensing lamp (10,000Lx or more) are used as the inspection equipment, and the distance from the light source of the inspection equipment to the glass substrate and the distance from the glass substrate to the measurer are both 300 mm. Reflected light and transmitted light were visually confirmed.
(4) Experimental results <Processing speed>
It was 2.5 μm / min with respect to one side of the raw glass.
<Thickness>
Table 2 shows the thickness of the raw glass measured by an ultrasonic thickness gauge.

<Scratch presence>
FIG. 9 shows the result of inspecting the presence or absence of scratches on the raw glass before and after chemical processing. From the result of FIG. 9, it can be seen that scratches existing before chemical processing disappeared by chemical processing.
<Surface flatness>
The result of measuring the surface state after chemically processing No. 2 bare glass is shown in FIG. It can be seen from Table 2 and FIG. 10 that the target amount can be uniformly processed at each position of the raw glass, and the surface of the raw glass has been flattened.

[Example 3] An example of chemical processing of two bonded liquid crystal glass substrates using the chemical processing apparatus 1 is shown.
(1) Size of bonded liquid crystal glass substrate and target chemical processing amount
No.3; 400mm x 500mm x 1.4mm. Target chemical processing amount: 0.4mm on both sides.
(2) Composition of chemical working fluid Same as Example 2.
(3) Acceptance inspection and final inspection method <plate thickness measurement>
The measurement position on the front side of the two bonded liquid crystal glass substrates is shown in FIG. 12, and the measurement position on the back side is shown in FIG.
<Appearance inspection>
The same operation as in Example 2 was performed.
(4) Experimental results <Processing speed>
It was 2.5 μm / min with respect to one side of the bonded liquid crystal glass substrate.
<Thickness>
Table 3 shows the results measured with an ultrasonic plate thickness meter.

<Scratch presence>
The result of inspecting the presence or absence of scratches before and after chemical processing is shown in FIG. From FIG. 11, it can be seen that scratches existing before chemical processing disappeared by chemical processing.
<Surface flatness>
From Table 3, it can be seen that the target amount can be uniformly processed at each position of the bonded glass substrate, and the surface is flattened.

[Example 4] Since the liquid crystal glass substrate in which the color filter pixels were patterned with Cr became defective, after the Cr was peeled off, chemical processing was performed by the chemical processing apparatus 1 in order to eliminate the pattern trace.
(1) Size of glass substrate after Cr peeling and target chemical processing amount
No.4: Length 400mm x width 500mm x thickness 0.7mm. Target chemical processing amount: 5 μm.
(2) Composition of chemical working fluid The same composition as in Example 2 was used.
(3) Acceptance inspection and final inspection method <plate thickness measurement>
The plate thickness at the measurement position shown in FIG. 8 was measured using an ultrasonic plate thickness meter.
<Appearance inspection>
The same operation as in Example 2 was performed.
(4) Experimental results <Processing speed>
It was 2.5 μm / min with respect to one side of the glass substrate.
<Thickness>
Table 4 shows the results measured with an ultrasonic plate thickness meter.

<Presence / absence of pattern trace>
It was confirmed that all traces of the pattern disappeared by chemical processing.
<Surface flatness>
From Table 4 and the disappearance result of the pattern trace, it can be seen that the target amount of the liquid crystal glass substrate can be processed uniformly and the surface is flattened.

  As described above, it was confirmed that by performing the chemical processing method of the present invention, the surface of the liquid crystal glass substrate can be flattened while reducing the plate thickness. In addition, since scratches that have been present on the surface of the liquid crystal glass substrate can be eliminated, the glass can be reused. Furthermore, in the chemical processing method of the present invention, the glass substrate can be processed with high productivity regardless of the size of the glass substrate. The chemical processing apparatus 1 used in this example is not limited to the one described in the above embodiment, and various design changes can be made without impairing the object of the present invention.

It is sectional drawing which shows an example of a chemical processing apparatus. It is a perspective view which shows the 1st Example of a bubble generator. It is a perspective view which shows the 2nd Example of a bubble generator. It is a top view which shows an example of a chemical processing liquid storage tank and the holder for glass substrate storage jigs. It is a perspective view which shows an example of a chemical processing liquid discharge apparatus. It is a graph which shows the relationship between the addition ratio of a chemical processing liquid, and a processing speed. It is a graph which shows the relationship between a processing speed and temperature. It is a top view which shows the measurement position of the plate | board thickness of the glass substrate of No.2. It is a top view which shows the result of having investigated the presence or absence of the surface flaw before and after chemical processing. It is a top view which shows the result of having investigated the surface state of the glass substrate of No. 2 with the surface roughness meter. It is a top view which shows the result of having investigated the presence or absence of a crack before and after chemical processing. It is the top view which showed the measurement position of the plate | board thickness of the outer surface of what bonded together two glass substrates of No.2. It is the top view which showed the measurement position of the plate | board thickness of the outer back surface of what bonded together two glass substrates of No.2. It is a graph which shows the result of having measured the surface after grind | polishing by the conventional chemical processing method. It is the graph which showed the relationship between the diameter of a pit, and the amount of processing. 5 is a graph showing the relationship between the number of pits per unit area and the machining amount. It is the graph which showed the state of the undulation of the surface after a process. It is a graph which shows the section of the surface where the crack was intentionally given before processing. It is a graph which shows the cross section of the surface after a process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chemical processing apparatus 11 Chemical processing liquid storage tank 12 Bubble generator 12a Bubble discharge part 13 Overflow liquid receiving tank 14 Filter 15 Pump 16 Chemical processing liquid discharge apparatus 17 Glass substrate storage jig holder 18 Glass substrate storage jig

Claims (8)

A chemical processing method for immersing a glass substrate in a chemical processing liquid and performing a process of polishing and thinning part or all of one side or part or all of both sides constituting the outer surface of the glass substrate,
Replacing the chemical working fluid before quality degradation due to an increase in reaction products with a new chemical working fluid,
A chemical processing method characterized by processing at a processing speed of 10 μm / min or less. The chemical processing method according to claim 1, wherein the chemical processing liquid contains hydrofluoric acid and one or more inorganic acids selected from hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid. The chemical working fluid contains an anti-redeposition agent that prevents the reaction product from re-adhering to the glass substrate surface,
The chemical processing method according to claim 1, wherein the anti-redeposition agent is an anionic surfactant or an amine surfactant. The chemical processing method according to claim 3, wherein an ultrasonic vibrator or an oscillating stirring blade is operated on the chemical processing liquid. The chemical processing method according to claim 1, wherein the glass substrate is arranged substantially vertically in the chemical processing liquid, and a rising liquid flow is generated by bubbles continuously generated in the chemical processing liquid. . The chemical processing method according to claim 5, wherein the chemical processing liquid containing the reaction product is overflowed from the chemical processing liquid storage tank by the rising liquid flow. The glass substrate processed by the method in any one of Claims 1-6. The flat panel display manufactured using the glass substrate of Claim 7.

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