Wafer cleaning water supply system

Abstract

To provide a wafer cleaning water supply device which can accurately adjust the concentration of solute in dilute cleaning water to a desired value and prevents excess cleaning water from being discharged as much as possible.SOLUTION: A wafer cleaning water supply device 1 comprises a dilute cleaning water production portion 2 that produces dilute cleaning water W1, a diluted cleaning water storage tank 3, supply piping 4 having a liquid pump 4A for supplying the dilute cleaning water W1 stored in the storage tank 3 to a cleaning portion 5, and return piping 6 that returns surplus cleaning water W2 from the cleaning portion 5 to the storage tank 3. A cleaning water supply piping 21, overflow piping 12, and return piping 6A are each connected to the upper side of the storage tank 3. The overflow piping 12 is provided with a level sensor 13 and a flow meter 14, and the dilute cleaning water production portion 2 can be controlled on the basis of the measured values of the level sensor 13 and the flow meter 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wafer cleaning water supply device capable of stably supplying cleaning water containing solutes such as acids, alkalis, oxidizing agents, reducing agents, and gases at very low concentrations, which is effective in the cleaning and rinsing processes of wafers for semiconductors.

Background Art

[0002] In the cleaning process of semiconductor silicon wafers and the like, water in which a very low concentration of solutes effective for controlling pH and redox potential (hereinafter referred to as dilute cleaning water) may be used. This dilute cleaning water is based on ultrapure water, and in order to give it a liquid property such as pH and redox potential that matches the purpose of the cleaning and rinsing processes, the minimum necessary acids, alkalis, oxidizing agents, reducing agents, and other chemicals are added. For example, when adjusting the pH, generally a method of adding a small amount (chemical injection) of HCl and NH4OH is adopted. Also, when adjusting the redox potential, it is produced by adding an oxidizing agent or a reducing agent. Further, CO2 gas or N2 gas is dissolved in ultrapure water to impart pH or inactivation. In addition, when it is desired to impart reducibility, H2 gas is also dissolved.

[0003] As such a chemical injection method, there are a method using a pump such as a plunger pump, a method of pressurizing and extruding a chemical solution filled in a sealed container with an inert gas such as N2 gas, etc., and each has been put into practical use. Also, when dissolving a gas, a gas dissolution membrane is used.

[0004] When adding such chemicals, if the flow rate of ultrapure water is constant, it is easy to obtain a desired solute concentration. However, in an actual cleaning machine using dilute cleaning water, the supply and stop of the water poured onto the wafer are controlled by the opening and closing of a plurality of valves, and the flow rate fluctuates irregularly. In response to this fluctuation, various methods of dissolution control are performed, such as proportional control with respect to the ultrapure water flow rate and PID control in response to the signal of the concentration monitor, so that the solute concentration of the dilute cleaning water falls within the desired range.

Summary of the Invention

[0005] However, in semiconductor wafer cleaning machines, particularly single-wafer cleaning machines with multiple cleaning chambers, despite the irregular fluctuations in flow rate, chemical injection control that can adequately follow these irregular fluctuations has not been achieved. As a result, the quality of the cleaning and rinsing water poured onto the wafers must be controlled over a wide range that deviates from the ideal range.

[0006] Therefore, one might consider prioritizing the stabilization of the dilute cleaning water concentration and continuously producing and supplying an excess amount of dilute cleaning water under certain conditions. However, in this case, a large amount of excess dilute cleaning water would be discharged. In recent single-wafer washing machines with multiple washing chambers, the difference between the maximum and minimum flow rates of dilute cleaning water required instantaneously becomes large. Therefore, continuously supplying more dilute cleaning water than the maximum flow rate results in the discharge of a considerable amount of excess water (excess dilute cleaning water), which poses problems in terms of burden on water supply and drainage facilities, excessive use and discharge of chemicals, and excessive waste of ultrapure water as a basic material.

[0007] Reusing excess water (excess dilute wash water), especially excess water after it has passed through a heating device, is sometimes unsuitable from the standpoint of strict concentration control because oxidizing agents such as H2O2 and O3 tend to decompose due to their natural decomposition and reactions with other chemicals, causing their concentrations to fluctuate. Similarly, excess water from gas-dissolved water containing H2 gas, CO2 gas, etc., has the problem of decreasing gas concentration as it passes through gas-permeable tubes or tanks before being returned to the storage tank.

[0008] The present invention has been made in view of the above problems, and aims to provide a wafer cleaning water supply device that can accurately adjust the solute concentration of dilute cleaning water to a desired value and minimize the discharge of excess water. [Means for solving the problem]

[0009] To achieve the above-mentioned objectives, the present invention provides a wafer cleaning water supply device comprising: a cleaning water production unit that produces cleaning water of a predetermined chemical concentration by adding a predetermined amount of chemical to the flow rate of ultrapure water; a storage tank for storing the cleaning water having an overflow pipe; a supply pipe connecting the storage tank and a cleaning unit equipped with a cleaning machine; a cleaning water supply mechanism provided in the supply pipe for supplying the cleaning water stored in the storage tank to the cleaning unit; and a return pipe for returning excess cleaning water from the cleaning unit to the storage tank, wherein the return pipe is provided with a discharge pipe branched from the return pipe and a means for measuring the water quality of the excess cleaning water, and has a switching means that can switch the return pipe between the storage tank side and the discharge pipe side based on the measured value of the water quality measuring means (Invention 1).

[0010] According to this invention (Invention 1), a predetermined amount of chemical is added to ultrapure water to produce dilute washing water of a predetermined concentration, which is then stored in a storage tank and supplied from this storage tank to the point of use. At this time, the storage tank is always kept full, and an overflow pipe is provided to allow overflow, thereby preventing the mixing of gas components in the storage tank, and thus eliminating the need for an inert gas supply unit. Furthermore, the excess washing water at the washing section, which is the point of use, fluctuates due to the self-decomposition of chemical components such as oxidizing agents and the permeation of gas from piping materials. However, based on the measured values ​​of the water quality measuring means, it is possible to decide whether to return it to the storage tank or remove it from the system and switch the return pipe, thereby enabling the reuse of excess washing water while maintaining a constant water quality in the storage tank.

[0011] In the above invention (Invention 1), it is preferable to have a control means capable of controlling the switching means based on the measured value of the water quality measuring means (Invention 2).

[0012] According to this invention (Invention 2), the switching of piping to return the excess washing water to the storage tank or to remove it from the system can be automatically controlled based on the measured value of the water quality measuring means, so that the wafer washing water supply device can be operated efficiently.

[0013] In the above invention (Invention 1), it is preferable to have a detection means for measuring the water level of the storage tank, and a control means capable of controlling the washing water production unit based on the measured value of the detection means (Invention 3).

[0014] According to this invention (Invention 3), by controlling the operation and stopping of the washing water production unit, or the amount of washing water produced, based on the water level in the storage tank and the amount of excess washing water returned, the amount of washing water produced can be optimized, and the amount of chemicals and ultrapure water used can be optimized.

[0015] In the above invention (Invention 1), it is preferable that the agent is a liquid and that the supply mechanism includes a pump or a sealed tank and a pressurizing means using an inert gas to add this liquid to the ultrapure water supply pipe (Invention 4).

[0016] According to this invention (Invention 4), by supplying a predetermined amount of chemical by pushing the chemical solution out with a pump or inert gas relative to the flow rate of ultrapure water, washing water of a predetermined concentration can be stably produced.

[0017] In the above invention (Invention 1), a discharge pipe is provided in the storage tank, and the washing water production unit or the storage tank has a means for calculating the chemical concentration of the washing water, and based on the measured value of the chemical concentration calculation means, the washing water It is preferable to have a control means for discharging the contents from the discharge pipe of the storage tank (Invention 5).

[0018] According to this invention (Invention 5), by not storing the cleaning water produced in the cleaning water production unit in the storage tank until the concentration of the chemicals in the cleaning water falls within a predetermined range, cleaning water of a predetermined concentration can be stably stored in the storage tank.

[0019] In the above invention (Invention 5), it is preferable that the discharge pipe of the storage tank has a removal means equipped with an ion exchange device and / or a catalyst device for removing chemical components in the washing water, and is in communication with the supply side of the ultrapure water (Invention 6).

[0020] According to this invention (Invention 6), washing in which the concentration of the drug falls outside a predetermined range water Although the wastewater is discharged, this discharged washing water can be treated with a removal device to remove the chemical components and reused as ultrapure water or raw water for ultrapure water, thereby reducing the consumption of ultrapure water. [Effects of the Invention]

[0021] The wafer cleaning water supply device of the present invention comprises a cleaning water production unit, a storage tank, a cleaning water supply mechanism for supplying cleaning water to the cleaning unit, and a return pipe for returning excess cleaning water from the cleaning unit to the storage tank. Since an overflow pipe is provided in the storage tank, the storage tank can be kept full at all times and allowed to overflow, which prevents the inclusion of gaseous components in the storage tank. Therefore, even without providing an inert gas supply unit, a deterioration in the quality of the cleaning water in the storage tank can be prevented. Furthermore, the excess cleaning water in the cleaning section, which is the point of use, fluctuates due to the self-decomposition of chemical components such as oxidizing agents and the permeation of gases from piping materials. However, by providing a discharge pipe branching off from the return pipe and allowing the return pipe to be switched between the storage tank side and the discharge pipe side based on the measurement values ​​of the water quality measuring device, it is possible to decide whether to return the excess cleaning water in the cleaning section to the storage tank or discharge it outside the system and switch the return pipe accordingly. This allows for the reuse of excess cleaning water while maintaining a constant water quality for the cleaning water in the storage tank. [Brief explanation of the drawing]

[0022] [Figure 1] This is a flow diagram showing a wafer cleaning water supply system according to one embodiment of the present invention. [Figure 2] A flowchart showing an example of the cleaning water production section of the wafer cleaning water supply apparatus of the above embodiment. [Figure 3] It is a flowchart showing another example of the washing water production section of the wafer washing water supply device of the above embodiment.

Embodiments of the Invention

[0023] [Wafer Washing Water Supply Device] FIG. 1 shows a wafer washing water supply device according to an embodiment of the present invention. In FIG. 1, the wafer washing water supply device 1 includes a dilute washing water production section 2 that produces dilute washing water W1, and a storage tank 3 for the produced dilute washing water W1. A supply pipe 4 for supplying the dilute washing water W1 stored in the storage tank 3 to a washing section 5 equipped with a plurality of single wafer washing machines 5A, 5B, and 5C is connected to this storage tank 3. The supply pipe 4 and a liquid feeding pump 4A such as a booster pump provided in the supply pipe 4 constitute a washing water supply mechanism. Note that 4B is a temperature regulator. Further, the washing section 5 is provided with a return pipe 6 that is connected to the single wafer washing machines 5A, 5B, and 5C respectively and returns the surplus washing water W2 not used in this washing section 5 to the storage tank 3.

[0024] (Return Mechanism) In the middle of the return pipe 6, a dissolved oxygen meter 7 and a composite water quality meter 8 as water quality measurement means connected to an on-line monitor (not shown) etc. are provided, and it branches into a return pipe 6A and a discharge pipe 6B on the downstream side. Opening and closing valves 9 and 10 are provided in these return pipe 6A and discharge pipe 6B respectively, and these opening and closing valves 9 and 10 can be opened and closed controlled by control means (not shown) based on the measured values of the dissolved oxygen meter 7 and the composite water quality meter 8. Note that 11 is a pressure regulating valve.

[0025] (Storage Tank) The storage tank 3 is made of a material that allows for negligible leaching from its inner wall in order to avoid impairing the purity of the dilute wash water W1. The wash water supply pipe 21, the overflow pipe 12, and the return pipe 6A are connected to the upper side of the storage tank 3, while the discharge pipe 15 of the storage tank 3 is connected to the bottom side. The overflow pipe 12 is equipped with a level sensor 13 and a flow meter 14 as means for detecting the water level, and the dilute wash water production unit 2 can be controlled by a control means (not shown) based on the measured values ​​of these level sensor 13 and flow meter 14. Furthermore, in this embodiment, the discharge pipe 15 of the storage tank 3 has an on / off valve (not shown), and a removal means 16 equipped with an ion exchange device and / or a catalyst device is provided along the pipe, and by measuring the chemical concentration of the wash water stored in the storage tank 3, the on / off valve can be controlled by a control means (not shown) based on this measured value.

[0026] (Dilute Washing Water Production Department) As shown in Figure 2, the dilute cleaning water production unit 2 includes a dilute cleaning water supply pipe 21 connecting the ultrapure water (DIW) W supply source 22 and the storage tank 3, and a first chemical solution (chemical) supply mechanism 23 and a second chemical solution (chemical) supply mechanism 24 provided in the middle of the dilute cleaning water supply pipe 21. In this embodiment, the first chemical solution supply mechanism 23 and the second chemical solution supply mechanism 24 are each composed of a first chemical solution tank 23A and a plunger pump 23B for adding the chemical solution, and a second chemical solution tank 24A and a plunger pump 24B for adding the chemical solution. Furthermore, the chemical dissolved in the dilute cleaning water W1 is not limited to a liquid (chemical solution) but may also be a gas. As the gas dissolved as the chemical, for example, hydrogen, ozone, CO2, etc., can be selected in various ways depending on the cleaning purpose. When dissolving functional gases in this manner, a membrane degasser 25 and a gas dissolution membrane 26, which is a mechanism for dissolving functional gases as gaseous agents, are provided downstream of the second chemical supply mechanism 24. A dissolution gas source 27 and a mass flow controller (MFC) 27A, which serves as a flow rate control means, are connected to this gas dissolution membrane 26. The dilute wash water supply pipe 21 is equipped with a flow rate measuring means, such as a flow meter (not shown), and a predetermined flow rate of chemical solution (agent) is supplied according to this flow rate. Furthermore, the supply amount of ultrapure water (DIW) W from the supply source 22 can be controlled by a control means (not shown).

[0027] [Method for supplying diluted washing water] Next, the method for supplying dilute cleaning water using the wafer cleaning water supply device described above will be explained below.

[0028] (Dilute washing water production process) First, in the dilute washing water production unit 2, ultrapure water (DIW) W is supplied from the ultrapure water (DIW) W supply source 22, and the first chemical solution and the second chemical solution are supplied from the first chemical solution supply mechanism 23 and the second chemical solution supply mechanism 24, respectively. At this time, based on the flow rate of the dilute washing water supply pipe 21, the control device controls the plunger pumps 23B and 24B so that the first and second chemical solutions reach predetermined concentrations, thereby adjusting the amount of the first and second chemical solutions added. In this embodiment, the dilute washing water W1 contains chemical components at a concentration of 100 ppm or less, particularly 50 ppm or less.

[0029] In this embodiment, the raw water, ultrapure water W, is preferably such that it has a resistivity of 18.1 MΩ·cm or more, fine particles with a particle size of 50 nm or more and 1000 particles / L or less, live bacteria of 1 cell / L or less, TOC (Total Organic Carbon) of 1 μg / L or less, total silicon of 0.1 μg / L or less, metals of 1 ng / L or less, ions of 10 ng / L or less, hydrogen peroxide of 30 μg / L or less, and a water temperature of 25 ± 2℃.

[0030] For either the first or second chemical solution, a pH adjuster is preferred. There are no particular restrictions on the pH adjuster, but when adjusting to a pH below 7, an acidic solution such as hydrochloric acid, nitric acid, sulfuric acid, or acetic acid can be used. When adjusting to a pH of 7 or higher, an alkaline solution such as ammonia, sodium hydroxide, potassium hydroxide, or TMAH can be used.

[0031] Furthermore, a redox potential adjusting agent is preferred as the second chemical solution or the other of the first chemical solution. As this redox potential adjusting agent, hydrogen peroxide solution can be used when adjusting the redox potential to a high level. When adjusting the redox potential to a low level, solutions of oxalic acid, hydrogen sulfide, potassium iodide, etc., can be used.

[0032] These first or second chemical solutions may be added together or either one may be added. If only one is added, the supply mechanism 24 for the second chemical solution may be omitted. In this way, the desired dilute washing water W1 is produced by controlling the amount of either the first or second chemical solution, or both, added by a control device based on the flow rate of ultrapure water W, so that the concentration reaches a predetermined level.

[0033] Furthermore, in this embodiment, if necessary, the dissolved gas in the ultrapure water W after adding the first and / or second chemical solution may be removed by a membrane degasser 25, and then the gas supplied from the dissolving gas source 27 may be dissolved in the gas dissolution membrane 26 to prepare the dilute wash water W1. At this time, it is preferable to control the flow rate of the gas supplied from the dissolving gas source 27 with a mass flow controller (MFC) 27A so that the dilute wash water W1 reaches a predetermined dissolving gas concentration.

[0034] (Storage process) The dilute wash water W1 produced in this manner is supplied directly to the storage tank 3. At this time, in order to prevent the dissolution of gases such as atmospheric components and the rise in dissolved oxygen in the storage tank 3, the dilute wash water W1 is filled to the full capacity of the storage tank 3 without creating a gas phase, and is allowed to enter the overflow pipe 12 of the storage tank 3, causing a slight overflow. When the values ​​of the level sensor 13 and / or flow meter 14 of the overflow pipe 12 at the top of the storage tank 3 are above a certain level, the production of dilute wash water W1 is stopped or the supply amount is switched to be reduced. On the other hand, when the values ​​of the level sensor 13 and / or flow meter 14 installed in the overflow pipe 12 fall below a certain level, the production of dilute wash water W1 by the dilute wash water production unit 2 is started or the supply amount is switched to be increased, and this state is continued until the predetermined water level or flow rate is reached again. This operation can be repeated.

[0035] Here, the maximum amount of dilute wash water W1 produced by the dilute wash water production unit 2 is set to be slightly greater than the maximum amount used in the washing unit 5, so that an overflow always occurs in the storage tank 3. At this time, the supply of dilute wash water W1 from the dilute wash water production unit 2 may be controlled by on / off, but to make it easier to maintain flow balance, it is preferable to pre-set the production flow rate in two or more stages in accordance with the amount of dilute wash water W1 used in the washing unit 5, as this allows for more precise control of the chemical concentration of the dilute wash water W1. It is also possible to use flow rate proportional control instead of stage control, but with flow rate proportional control, it becomes difficult to control the concentration of extremely small amounts of solute (chemical solution), and the water quality of the dilute wash water W1 tends to fluctuate. Furthermore, it is desirable to insert the return pipe 6A for excess wash water W2 to the storage tank 3 and the dilute wash water supply pipe 21 from the dilute wash water production unit 2 into the storage tank 3 so that fluid diffusion occurs within the storage tank 3, thereby homogenizing the solute (chemical solution) within the storage tank 3.

[0036] Here, immediately after starting production of dilute wash water W1 in the dilute wash water production unit 2, the solute (chemical) concentration of the dilute wash water W1 may not be stable and may not fall within the predetermined concentration range. Therefore, by pre-determining the time required and the amount of dilute wash water W1 to stabilize in the produced dilute wash water W1, and discharging the dilute wash water W1 from the discharge pipe 15 without storing it in the storage tank 3 until that point, the solute concentration of the supplied dilute wash water W1 stored in the storage tank 3 can be accurately controlled. Alternatively, the chemical concentration of the dilute wash water W1 may be measured, and if this concentration is outside the predetermined range, the discharge pipe 15 may be opened to control the system so that the dilute wash water W1 is discharged from the discharge pipe 15 without being stored in the storage tank 3. The discharged dilute wash water W1 in this case becomes wastewater, but it accounts for only a small portion of the total water volume. Furthermore, the discharge of this dilute washing water W1 is preferable because it can be returned to a wide range of applications, such as the dilute washing water production unit 2 or the ultrapure water W side, by removing the first chemical solution and / or the second chemical solution component using a removal means 16 equipped with an ion exchange device or catalyst device installed in the discharge pipe 15, thereby reducing the amount of wastewater.

[0037] (Dilute washing water preparation and supply process) Next, the dilute cleaning water W1 stored in the storage tank 3 is sent to the cleaning unit 5 by a liquid transfer pump 4A, which is located downstream of the storage tank 3. At this time, a temperature regulator 4B is provided downstream of the liquid transfer pump 4A in the supply piping 4, so that the temperature rise due to the circulation of the dilute cleaning water W1 and the resulting cleaning problems can be prevented. In this embodiment, a pressure adjustment valve 11 is installed in the return piping 6A for the excess cleaning water W2 to the storage tank 3, so that the dilute cleaning water W1 can be supplied to the cleaning unit 5 at a pressure above a predetermined level.

[0038] (Return process) The excess cleaning water W2 that was not used in the cleaning machines 5A, 5B, and 5C is returned to the storage tank 3 via the return pipe 6. In many cases, there is no problem in returning this excess cleaning water W2 directly to the storage tank 3, but the oxidizing agent component in the cleaning water W1 may self-decompose or react with the chemical solution, causing the concentration of the first and / or second chemical solution to fall below a predetermined value, or the dissolved oxygen concentration to increase due to contact with the atmosphere. Therefore, in this embodiment, a dissolved oxygen meter 7 and a combined water quality meter 8 are provided in the return pipe 6 as means of measuring water quality, and the water quality of the excess cleaning water W2 is monitored by an online monitor or the like, and the opening and closing of the on / off valves 9 and 10 are controlled according to the values ​​measured there. Specifically, if the water quality of the excess cleaning water W2 is problematic even if it is returned directly to the storage tank 3, the on / off valve 9 on the return pipe 6A side is opened and the on / off valve 10 on the discharge pipe 6B side is closed, and the water is returned to the storage tank 3. On the other hand, if the excess wash water W2 is not suitable for direct return to the storage tank 3, the on / off valve 9 on the return pipe 6A side is closed, and the on / off valve 10 on the discharge pipe 6B side is opened, thereby discharging the water outside the system instead of returning it to the storage tank 3. This discharged excess wash water W2 can be reused as raw material for ultrapure water W by removing the first chemical solution and / or the second chemical solution components using an ion exchange device or catalyst device. Furthermore, even when the excess wash water W2 is returned to the storage tank 3, the solute concentration in the excess wash water W2 can be monitored, and the solute (chemical solution) concentration in the dilute wash water production unit 2 can be controlled to reduce solute consumption and eliminate the need for a solute removal device in the excess wash water W2.

[0039] The wafer cleaning water supply apparatus of the present invention has been described above based on the above embodiments, but the present invention is not limited to the above embodiments and can be modified in various ways. For example, the first chemical supply mechanism 23 and the second chemical supply mechanism 24 are not limited to those shown in Figure 2, but as shown in Figure 3, the first chemical tank 23A and the second chemical tank 24A can be made into sealed tanks, and N2 gas as an inert gas can be supplied to the first chemical tank 23A and the second chemical tank 24A from the N2 gas supply source 28 via the supply pipe 29 to increase the pressure inside the tanks, and the first chemical and second chemicals can be pumped to dissolve the first and second chemicals to a desired solute concentration. Furthermore, the dilute cleaning water production unit 2 does not need to have all of the first chemical supply mechanism 23, the second chemical (chemical) supply mechanism 24 and the gas dissolution mechanism as in this embodiment, and can be used for the desired cleaning water Depending on the properties of W1, you may select and use 1 or more of them. [Explanation of Symbols]

[0040] 1. Wafer cleaning water supply system 2. Dilute Washing Water Production Department 3 Storage tank 4. Supply piping (washing water supply mechanism) 4A Liquid transfer pump (wash water supply mechanism) 4B Temperature controller 5. Cleaning section 5A, 5B, 5C Single-wafer cleaning machine 6. Return piping 6A Return piping 6B Discharge pipe 7. Dissolved oxygen meter (water quality measurement tool) 8. Combined water quality meter (water quality measurement means) 9. On / off valve 10. On / off valves 11 Pressure regulating valve 12 Overflow piping 13 Level Sensor 14 Flow meter 15 Discharge pipe 16 Removal means 21. Dilute wash water supply pipe 22 Ultrapure water source 23. The supply mechanism of the first drug solution (medicine) 23A First chemical tank 23B Plunger Pump 24. Second drug supply mechanism 24A Second chemical tank 24B Plunger Pump 25 Membrane-type degassing device 26 Gas-dissolved membrane 27. Dissolved gas source 27A Mass Flow Controller (MFC: Flow Control Means) 28 N2 gas supply sources 29 N2 gas supply pipe W Ultrapure water W1 Dilute washing water W2 Excess washing water

Claims

1. A washing water production unit that produces washing water with a predetermined chemical concentration by adding a predetermined amount of chemical to the flow rate of ultrapure water, A storage tank for storing the cleaning water having an overflow pipe, A supply pipe connecting the storage tank and the cleaning unit equipped with a cleaning machine, A cleaning water supply mechanism provided in the supply piping for supplying cleaning water stored in the storage tank to the cleaning unit, A return pipe for returning excess cleaning water from the cleaning unit back to the storage tank. A washing water supply device comprising: A wafer cleaning water supply device is provided, wherein the return piping is equipped with a discharge pipe branched off from the return piping and a means for measuring the water quality of the excess cleaning water, and the device has a switching means that can switch the return piping between the storage tank side and the discharge pipe side based on the measurement value of the water quality measuring means.

2. The wafer cleaning water supply apparatus according to claim 1, further comprising a control means capable of controlling the switching means based on the measured value of the water quality measuring means.

3. The wafer cleaning water supply apparatus according to claim 1, further comprising a detection means for measuring the water level in the storage tank, and a control means capable of controlling the cleaning water production unit based on the measurement value of the detection means.

4. The wafer cleaning water supply apparatus according to claim 1, wherein the agent is a liquid, and the apparatus comprises a supply mechanism using a pump or sealed tank and pressurizing means that uses an inert gas to add the liquid to the ultrapure water supply pipe.

5. A wafer cleaning water supply apparatus according to claim 1, wherein the storage tank is provided with a discharge pipe, and the cleaning water production unit or the storage tank has a means for calculating the chemical concentration of the cleaning water, and the apparatus further comprises a control means for discharging the cleaning water from the discharge pipe of the storage tank based on the measured value of the chemical concentration calculation means.

6. The wafer cleaning water supply apparatus according to claim 5, wherein the discharge pipe of the storage tank has a removal means equipped with an ion exchange device and / or a catalyst device for removing chemical components in the cleaning water, and is in communication with the supply side of the ultrapure water.

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