JP2017066012A - Etching system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching system capable of performing high quality filtration to an etchant for a long period.SOLUTION: An etching system 10 comprises at least, an etching device 12, a MF (micro filter) filtration device 16, a filter press 18 and a liquid feeding control device 22. The etching device 12 is configured to perform etching processing by bringing an etchant stored in an etchant tank 14 into contact with a glass substrate 100. The MF filtration device 16 and the filter press 18 are configured to filter the etchant stored in the etchant tank 14. The liquid feeding control device 22 is configured to control liquid feeding on the etchant tank 14, the MF filtration device 16 and the filter press 18, and control so that SS density of the etchant stored in a feeding liquid storage part 32 which is provided to the MF filtration device 16 is in a range of 3,000-45,000 mg/L.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an etching system configured to perform an etching process on a glass substrate, and more particularly to an etching system capable of effectively filtering sludge in an etching solution.

  A glass substrate used for a flat panel display such as a liquid crystal display is required to be thin. As a process for thinning a glass substrate for a flat panel display, an etching process in which an etching solution containing hydrofluoric acid is generally brought into contact with the glass substrate has been widely used. As such an etching process, there are a method of immersing a glass substrate to be processed in a tank in which an etching solution is put, or spraying an etching solution on a glass substrate to be processed.

  When performing the etching process with respect to the above-mentioned glass substrate, the process of the etching liquid in use or after use becomes important. Conventionally, by draining the drainage fluid through a filter medium such as a filter, the slurry or sludge mixed in the etchant is captured and the etchant has been filtered (see, for example, Patent Document 1). By doing so, not only the slurry or sludge can be separated from the etching solution, but also the slurry or sludge captured by applying pressure to the filter by bubbling from the bottom can be removed from the filter, and etching is performed for a long time. It is said that the liquid can be filtered.

Japanese Patent No. 5747046

  However, in the technique according to Patent Document 1 described above, there has been a problem in that the performance of the filtration device decreases with time. For example, fine slurry or sludge contained in the etching solution can pass through the filter and accumulate in the subsequent stage of the filter, or huge slurry or sludge can adhere to the filter seam and be removed by bubbling. Sometimes it disappeared. As a result, inconveniences such as a reduction in filtration performance due to clogging of the filter or a necessity to perform maintenance such as filter replacement may occur.

  An object of the present invention is to provide an etching system capable of performing high-quality filtration on an etching solution over a long period of time.

  The etching system according to the present invention is configured to perform an etching process on a glass substrate. The etching system includes an etching device, a membrane filtration device, a post-processing unit, and a liquid feeding control unit. The etching apparatus includes at least an etching solution tank and is configured to perform an etching process by bringing the etching solution into contact with a glass substrate. Examples of etching apparatuses include a single wafer etching apparatus that injects an etching solution onto the upper and lower surfaces of a glass substrate from a spray nozzle onto a glass substrate that is conveyed by a conveyance roller or the like, or an etching solution tank that contains an etching solution. An immersion type etching apparatus that immerses the substrate may be used.

  The membrane filtration apparatus includes a membrane module, a supply liquid storage unit, a filtrate supply unit, and clogging prevention means. The membrane module is configured to filter the etchant. An example of this membrane module is MF (microfilter). The supply liquid storage unit is configured to store the etching liquid used in the etching apparatus and to be supplied to the membrane module. The filtrate sending unit is configured to receive the etching solution obtained by filtering the etching solution supplied to the supply solution storage unit by the membrane module. The clogging prevention means is configured to detach slurry collected by the membrane module (meaning all sludge-like materials, including solid so-called sludge) from the membrane module. . As an example of the clogging prevention means, there is an apparatus that applies pressure such as bubbling to the membrane module.

  The post-processing unit includes a trapping object storage tank that can receive the sludge and slurry collected by the membrane filtration device. This post-processing section preferably includes a solid-liquid separation mechanism that can dewater sludge and slurry. An example of the post-processing unit is a filter press.

  The liquid feeding control means controls the liquid feeding in the etching liquid tank, the membrane filtration device, and the post-processing unit. By providing a valve such as an automatic valve between the liquid supply passages, the amount of liquid supply can be adjusted. Further, the liquid feeding control means controls the liquid feeding so that the SS concentration (Suspended Solids) in the supply liquid container is in the range of 3000 to 45000 mg / L.

  In the above-described configuration, when the SS concentration of the etching liquid tank is less than 3000 mg / L, the liquid feeding control unit stops the liquid feeding from the etching liquid tank to the supply liquid storage part, and sends the etching liquid tank from the filtrate sending part. It is preferable that the liquid is stopped and liquid feeding from the membrane filtration device to the post-processing unit is stopped, and the filtered etching liquid is circulated from the filtrate sending part to the supply liquid storage part. The SS concentration in the supply liquid storage part can be maintained in the range of 3000 to 45000 mg / L by stopping the supply of the etching liquid having an SS concentration of less than 3000 mg / L to the supply liquid storage part.

  Further, it is preferable that the liquid feeding control means discharges the slurry or sludge captured by the membrane filtration device to the post-processing section when the SS concentration in the supply liquid storage section exceeds 40000 mg / L. . In this case, the slurry and the sludge are preferably discharged when the SS concentration in the supply liquid container is less than 5000 mg / L. The SS concentration in the supply liquid storage unit can be reduced by discharging the slurry and sludge captured when the SS concentration in the supply liquid storage unit exceeds 40000 mg / L, and the SS concentration in the supply liquid storage unit is By stopping when it is less than 5000, the SS concentration in the supply liquid storage unit can be maintained in the range of 3000 to 45000 mg / L.

  According to the present invention, it is possible to perform high-quality filtration on an etching solution over a long period of time.

It is a figure showing the outline of the etching system concerning one embodiment of the present invention. It is a figure showing the outline of the etching system concerning one embodiment of the present invention. It is a perspective view showing the inside of the supply liquid storage part of MF filtration apparatus. It is a side view showing MF during suction filtration of an MF filtration device. It is a block diagram showing the control part of the liquid feeding control means. It is a figure showing the liquid feeding path | route of the etching system controlled by a liquid feeding control means.

  The etching system 10 which concerns on one Embodiment of the etching system of this invention is demonstrated using FIGS. 1-3. The etching system 10 is configured to perform an etching process on a glass substrate for a flat panel such as a liquid crystal display or an organic EL display. The etching system 10 includes an etching device 12, an MF (microfilter) filtration device 16, a filter press 18, a sludge container 20, and a liquid feed control device 22 (see FIG. 5). The etching apparatus 12 includes an etching solution tank 14. The MF filtration device 16 includes an MF 30, a supply liquid storage unit 32, a filtrate supply unit 34, and an air diffuser 36. The filter press 18 includes a captured object storage tank. In this embodiment, the MF filtration device 16 and the filter press 18 correspond to the membrane filtration device and the post-processing unit of the present invention, respectively. The air diffuser 36 corresponds to the clogging preventing means of the present invention.

  The etching apparatus 12 is configured to spray the etching solution stored in the etching solution tank 14 onto the glass substrate 100 conveyed by the conveyance roller from the spray nozzle toward the upper surface and the lower surface of the glass substrate 100. It is a type etching apparatus. The etching solution sprayed from the spray nozzle comes into contact with the glass substrate 100 and is then returned to the etching solution tank 14. In this embodiment, a single-wafer etching apparatus is employed, but an immersion etching apparatus that immerses the glass substrate 100 in an etching solution tank may be employed.

  The MF filtering device 16 is configured to filter the used etching solution obtained by treating the glass substrate 100 with the etching device 12. The supply liquid storage unit 32 is configured to receive a used etching solution from the etching solution tank 14. The MF 30 is arranged in the supply liquid storage part 32 and can suck and filter the etching liquid stored in the supply liquid storage part 32. The filtrate delivery unit 34 is configured to receive the etching solution filtered by the MF 30. The detailed configuration of the MF filter device 16 will be described later.

  The filter press 18 receives the sludge and slurry collected by the MF filtration device 16 into the trapping object storage tank, and filters the received sludge and slurry. The filtrate obtained by filtration is sent to the filtrate delivery part 34. The filtered sludge is stored in the sludge storage unit 20. Since the filter press 18 can apply a high filtration pressure, sludge having a low water content can be obtained, and waste can be easily treated.

  The liquid feeding control device 22 sends liquid from the etching liquid tank 14 to the supply liquid storage part 32, feeds liquid from the filtrate sending part 34 to the etching liquid tank 14, and sends liquid from the filtrate sending part 34 to the supply liquid storage part 32. Liquid feeding and liquid feeding from the supply liquid storage portion 32 to the filter press 18 can be controlled. The liquid feeding control device 22 controls to feed or stop the liquid feeding according to the SS concentration value of the sludge contained in the etching liquid stored in the etching liquid tank 14 and the supply liquid storage unit 32. It has become. The detailed configuration of the liquid feeding control device 22 will be described later.

  FIG. 3 is a perspective view showing the inside of the supply liquid storage unit 32 of the MF filtration device 16. An MF 30 and an air diffuser 36 are disposed in the supply liquid storage unit 32. A pipe 42 through which the etching liquid can be fed from the etching liquid tank 14 and a pipe 44 connected to the filter press 18 are installed at the upper part of the supply liquid storage part 32. The MF 30 is provided with a filter on the main surface and the surface facing the main surface, and can be sucked from the upper suction tube 40. The MF 30 can change the area of the filter and the number of arranged filters, and can be changed depending on the processing amount of the etching liquid and the capacity of the supply liquid storage unit 32. The MF 30 is arranged upright with the filtration surface on both sides at intervals of 3 to 30 mm. An air diffuser 36 is disposed below the MF 30. Bubbling is performed from the air diffuser 36 to prevent sludge from adhering to the MF 30. The bottom of the supply liquid storage unit 32 has a structure that is inclined toward the center so that sludge collected by the MF 30 can be accumulated. A pipe 44 for sending the accumulated sludge to the filter press 18 is installed at the center. The structure of the bottom portion is not limited to the one inclined toward the center but may be inclined toward the wall side, or may have a structure other than these as long as sludge can be accumulated.

  The supply liquid storage part 32 is supplied with the etching liquid from the etching liquid tank 14 and is filtered by the MF 30, and sends the filtered etching liquid to the subsequent filtrate supply part 34. It is preferable to send the solution so that the amount of liquid sent from the etching solution tank 14 to the supply liquid storage unit 32 is the same as the amount of liquid filtered by the MF 30. When the amount of liquid in the supply liquid storage unit 32 is reduced and the MF 30 is exposed from the liquid surface, sludge adhering to the MF 30 is dried and it becomes difficult to remove even if it is immersed in the etching solution again, thereby reducing the filtration efficiency. Cause it.

  Further, it is preferable to provide a circulation path at the bottom of the supply liquid storage unit 32 for circulating the laminated sludge at the bottom. A diffuser pipe 36 is disposed at the bottom, and if sludge begins to accumulate on the bottom, a hole in the diffuser pipe 36 may be blocked and bubbling may not be performed well. If bubbling is not performed, the sludge collected by the MF 30 remains without being desorbed from the MF 30, so that the filtration efficiency is deteriorated. Providing the circulation path reduces the possibility of sludge sticking to the hole of the air diffuser 36.

  FIG. 4 is a diagram showing the MF 30 sucking and filtering the etching solution. The MF 30 sucks the filtered etching solution from the suction pipe 40 installed at the upper part, and the etching solution outside the MF 30 is permeated into the MF 30 by the pressure. Since sludge is collected by the filter of MF30, it does not enter MF30. Bubbling is performed from the lower air diffusion pipe 36, and pressure is applied to the surface of the filter, so that sludge is detached from the filter. The detached sludge floats by bubbling and is eventually stacked on the bottom of the supply liquid storage unit 32. The detached sludge is dispersed again in the etching solution by bubbling, and a part thereof is laminated on the bottom. The air diffuser 36 not only desorbs the sludge collected by the MF 30, but also disperses the sludge in the etching solution in the supply liquid storage unit 32 to make the SS concentration uniform.

  The finer the pore size of the filter is, the finer the particle size, the smaller the particle size can be filtered. The pore diameter of MF30 used in this embodiment is 0.25 μm, and it is difficult to use a finer one in consideration of the filtration flow rate. Sludge generated when etching glass is finer than the MF30 pore diameter of 0.25 μm and cannot be filtered even if it passes through MF30 as it is. The sludge adhering to the inside diameter of the MF30 is difficult to be removed even when pressure such as bubbling is applied from the outside. The MF30 is clogged, and the filtration efficiency is lowered or the MF30 is damaged due to an increase in the filtration pressure. Will lead to. When the SS concentration of the sludge contained in the etching solution increases, the particle size of the sludge increases and can be filtered, and the newly generated fine sludge also adheres to the large sludge and is filtered together. Is possible.

  The particle size of sludge having an SS concentration of sludge contained in the etching solution of less than 3000 mg / L is often less than 0.25 μm, so that MF30 cannot be completely filtered and clogging occurs. Therefore, when the etching liquid accommodated in the etching liquid tank 14 is less than 3000 mg / L, the liquid supply from the etching liquid tank 14 to the supply liquid storage part 32 is stopped, and the etching liquid is not brought into the MF filter device 16. It is like that. The SS concentration of sludge contained in the etching solution may be determined by the sensor 70 provided in the etching solution tank 14 or may be determined by predicting the amount of sludge deposited from the processing amount of the glass substrate 100. good.

  Sludge filtered by the MF 30 is stacked on the bottom of the supply liquid storage section 32, and the stacked sludge is in a state of floating in the supply liquid storage section 32 by bubbling. If the SS concentration of the sludge contained in the etching solution exceeds 45000 mg / L, the sludge collected by the MF30 does not catch up with the desorption due to bubbling, and the clogging of the MF30 occurs, resulting in a decrease in filtration efficiency and an increase in filtration pressure. Will lead to damage to MF30. By sending sludge and slurry to the filter press 18 from a pipe installed at the bottom of the supply liquid storage unit 32, the SS concentration of sludge contained in the etching liquid in the supply liquid storage unit 32 can be reduced.

  If the etching apparatus 12 is continuously used, sludge that has not been fed from the etchant tank 14 to the supply liquid storage unit 32 is clogged in the spray nozzle, so that the etchant is not sprayed, or the upper surface of the glass substrate 100 to be processed is The glass substrate 100 is not evenly etched due to sludge adhering, and thus the surface of the glass substrate 100 may be uneven or undulated. Further, in order to prevent sludge remaining in the etching solution tank 14 from adhering to the wall surface of the etching solution tank 14, it is necessary to periodically remove the etching solution from the etching apparatus 12 and perform maintenance. The etching solution extracted from the etching solution tank 14 is filtered by a filter press outside the etching system 10, an MF filtering device or the like, then added with a new solution, water, etc., and returned to the etching solution tank 14.

  It is preferable to use the original old etching solution as it is without changing the etching solution stored in the MF filtration device 16. If the etching solution in the MF filtration device 16 is newly changed, the SS concentration of sludge contained in the etching solution in the supply solution storage unit 32 starts from 0 mg / L. Even if a high etching solution is fed from the etching solution tank 14, clogging occurs. When the liquid of the supply liquid storage unit 32 is changed, it is necessary to use a sludge whose SS concentration is adjusted to 3000 mg / L or more. Moreover, since MF30 will dry at the time of liquid change implementation, it is necessary to detach sludge from MF30.

  The MF filtration device 16 stops the feeding of the supply liquid storage unit 32 from the etching liquid tank 14 when the SS concentration of the etching liquid tank 14 is low immediately after the liquid change or when the etching process of the glass substrate 100 is stopped. However, the suction filtration of MF30 should not be stopped at this time. If it stops, sludge will adhere to the surface of MF30, and when it moves next, MF30 will stop functioning. If the suction filtration of the MF 30 is continued, the amount of liquid in the supply liquid storage unit 32 decreases. Therefore, the etching solution that has been filtered and sent to the filtrate supply unit 34 is returned to the supply liquid storage unit 32 again. Thus, the suction filtration of the MF 30 can be continued without reducing the liquid amount in the supply liquid storage unit. Even if the filtrate is returned to the supply liquid storage unit 32 again, there is no change in the SS concentration of the supply liquid storage unit 32, so that a constant SS concentration can be maintained.

  The liquid feeding control device 22 will be described with reference to FIGS. 5 and 6. FIG. 5 is a block diagram showing the control of the liquid feeding control device 22. The liquid feeding control device 22 includes a CPU 60 and a memory 62, and is connected to valves 50, 52, 54, 56 and a sensor 70 which are automatic valves. The CPU 60 can freely open and close the valves 50, 52, 54, and 56 based on the detection of the SS concentration of the sensor 70 while reading the program stored in the memory 62. The sensor 70 is installed in the etching solution tank 14 and the supply solution storage unit 32.

  FIG. 6 is a diagram illustrating a liquid supply path of the etching system 10. The path connecting the etching liquid tank 14 to the supply liquid storage part 32, the filtrate supply part 34 to the etching liquid tank 14, the filtrate supply part 34 to the supply liquid storage part 32, and the path connecting the supply liquid storage part 32 to the filter press 18, respectively. Automatic valves 50, 52, 54 and 56 are arranged. The liquid feeding control device 22 controls the feeding of the etching liquid by opening and closing the respective automatic valves.

  When the SS concentration in the supply liquid storage unit 32 is in the range of 5000 to 40000 mg / L, the valves 50 and 52 are opened, the valves 54 and 56 are closed, and the etching solution tank 14, the supply liquid storage unit 32, and The liquid feed is controlled so as to circulate through the filtrate feed section 34. When the glass substrate 100 is processed by the etching apparatus 12, sludge is generated, so that the SS concentration of the etching solution tank 14 temporarily increases. However, since the etching solution having an increased SS concentration is sent to the supply solution storage unit 32 and the filtered etching solution is received from the filtrate sending unit 34, the SS concentration in the etching solution tank 14 is maintained constant. Instead of maintaining the SS concentration in the etching solution tank 14 constant, the SS concentration in the supply solution storage unit 32 where sludge remains is increased by the MF 30.

  The SS concentration of the supply liquid storage unit 32 increases as the MF 30 is filtered. When the SS concentration exceeds 40000 mg / L, the valve 50, the valve 52, and the valve 56 are opened, and the valve 54 is closed. While controlling the liquid feed to circulate through the etching liquid tank 14, the supply liquid storage part 32 and the filtrate supply part 34, the liquid supply is controlled from the supply liquid storage part 32 to the filter press 18. When liquid is supplied from the supply liquid storage part 32 to the filter press 18, the SS concentration in the supply liquid storage part 32 is reduced. The liquid feeding to the filter press 18 is controlled so as to stop the liquid feeding by closing the valve 56 when the SS concentration in the supply liquid storage unit 32 becomes less than 5000 mg / L. Feeding is started when the SS concentration in the supply liquid storage unit 32 exceeds 40000 mg / L, and the SS concentration in the supply liquid storage unit 32 is controlled by controlling the supply of liquid when it is less than 5000 mg / L. A range of 3000 to 45000 mg / L can be maintained.

  When the SS concentration in the etching solution tank 14 is less than 3000 mg / L, the valve 50, the valve 52 and the valve 56 are closed, and the valve 54 is opened to circulate the supply liquid storage unit 32 and the filtrate supply unit 34. The liquid feeding is controlled. By controlling in this way, the MF 30 can be operated without lowering the SS concentration in the supply liquid storage unit 32, so that the MF 30 is not clogged with a filter. The SS concentration of the etching solution tank 14 is low immediately after the liquid change in the etching solution tank 14, but the etching process may be started as it is because it is switched as described above when changing the solution. When the etching apparatus 12 stops the etching process of the glass substrate 100, when the MF filtration apparatus 16 is operated, the SS concentration in the etching solution tank 14 decreases. Anyway.

  The liquid feeding control device 22 must control the opening and closing of the valve 50 and the valve 52 as a set. Further, the liquid feeding of the valve 50 and the valve 52 must be controlled to be the same amount. When either one is open or the other is closed, or the amount of liquid to be fed is not the same, the balance of the amount of liquid in the etching liquid tank 14, the supply liquid storage part 32, and the filtrate sending part 34 is lost. There is a possibility that the liquid leakage exceeding the capacity of the liquid or the liquid level may decrease. The liquid feeding amount of the valve 54 may be the same as the filtration amount of the MF 30. When the liquid is fed from the valve 56 to the filter press 18, the amount of liquid in the supply liquid storage unit 32 decreases. Therefore, only when the valve 56 is opened, the liquid amount of the valve 50 is increased and the MF 30 in the supply liquid storage unit 32 It must be controlled so that it does not come out of the etching liquid surface.

  The liquid feeding control device 22 controls in the range of 5000 to 40,000 mg / L because the liquid feeding from the liquid feeding container 32 to the filter press 18 is performed when the SS concentration in the liquid feeding container 32 is cut to 5000 mg / L. When the SS concentration in the supply liquid storage unit 32 is stopped or when the liquid supply from the supply liquid storage unit 32 to the filter press 18 is started when the SS concentration in the supply liquid storage unit 32 exceeds 40000 mg / L, the SS concentration in the supply liquid storage unit 32 is 3000. It is an action line that maintains within the range of ˜45000 mg / L. If control can be performed without error, when the SS concentration in the supply liquid storage unit 32 is 3000, the supply of liquid from the supply liquid storage unit 32 to the filter press 18 is stopped, or the SS concentration in the supply liquid storage unit 32 is It is ideal to start feeding liquid from the supply liquid storage unit 32 to the filter press 18 at 45000 mg / L.

  By controlling as described above, the sludge generated by the etching device 12 can be efficiently filtered by the MF filtering device 16 without being clogged or damaged. In addition, since the size of the MF 30 filter and the number of installed MF 30 can be varied in accordance with the processing amount of the etching solution, it is possible to easily adjust the filtration device according to the device scale.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 10-Etching system 12-Etching apparatus 14-Etching liquid tank 16-MF filtration apparatus 18-Filter press 20-Sludge storage part 22-Liquid feeding control apparatus 30-MF
32-Supply liquid storage part 34-Filtrate delivery part 36-Air diffusion pipe 40-Suction pipe 42, 44-Piping 50, 52, 54, 56-Valve 60-CPU
62-memory 70-sensor

Claims (3)

An etching system for performing an etching process on a glass substrate,
An etching apparatus comprising at least an etchant tank, and configured to perform an etching process by bringing an etchant contained in the etchant tank into contact with a glass substrate;
A membrane filtration device connected to the etchant tank and configured to filter the etchant contained in the etchant tank;
A post-processing unit that is connected to the membrane filtration device and has a captured object storage tank capable of receiving the slurry captured by the membrane filtration device;
Liquid feeding control means for controlling liquid feeding in the etching liquid tank, the membrane filtration device, and the post-processing section;
Comprising at least
The membrane filtration device is:
A membrane module configured to filter the etchant;
A supply liquid storage section for storing an etching liquid to be supplied to the membrane module;
A filtrate delivery section for delivering the etching solution after passing through the membrane module;
Clogging prevention means for preventing clogging of the membrane module;
With
The liquid feeding control means is provided in the etching solution tank, the membrane filtration device, and the post-treatment unit so that the SS concentration in the supply liquid storage unit of the membrane filtration device is in a range of 3000 to 45000 mg / L. An etching system that controls liquid feeding.   The liquid feeding control means feeds liquid from the etching liquid tank to the supply liquid storage section when the SS concentration of the etching liquid tank is less than 3000 mg / L, and sends liquid from the filtrate feeding section to the etching liquid tank. 2. The liquid feeding from the membrane filtration device to the post-processing unit is stopped, and the filtered etching solution is circulated from the filtrate feeding unit to the supply liquid storage unit. Etching system.   The liquid feeding control means discharges the slurry captured by the membrane filtration device to the post-processing section when the SS concentration in the supply liquid storage section exceeds 40000 mg / L, and the inside of the supply liquid storage section The etching system according to claim 1, wherein the discharge is stopped when the SS concentration of is less than 5000 mg / L.

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