Wafer cleaning water supply device

Abstract

To provide a wafer cleaning water supply device which can stably supply a washing water obtained by dissolving each type of gas composition.SOLUTION: A wafer cleaning water supply device 1 include: a storage tank 2; a water supply pipe 3 for supplying an ultra pure water W to the storage tank 2; and a circular type wafer washing water supply pipe 4 connected to the storage tank 2. To a supply side 4A side of the wafer washing water supply pipe 4, a supply pipe 7 provided with a supply source 7A and a transmission liquid pump 7B of a medical liquid, and a gas dissolve film module 8 is provided on a downstream side from this supply pipe 7. To a gas phase side of the gas dissolve film module 8, a gas supply pipe 9 for a functional gas is connected. Further, to the storage tank 2, a gas supply pipe 11 connected to a supply source 11A for the same functional gas as the functional gas dissolved in the gas dissolve film module 8. The inside of the storage tank 2 can be purged by the functional gas dissolved in the gas dissolve film module 8.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 in which various gas components are dissolved, 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 solute effective for controlling pH and oxidation-reduction potential is dissolved at a very low concentration in ultrapure water (hereinafter referred to as functional water) may be used. This functional water is based on ultrapure water and has a liquid property such as pH and oxidation-reduction potential that matches the purpose of each process such as the cleaning and rinsing processes. To achieve this, trace amounts of acid and alkali such as HCl, H 2 SO 4 and NaOH, oxidizing agents such as H 2 O 2 and gas components such as CO 2 H 2 and O 3 are added in trace amounts. For pH adjustment and imparting oxidizing properties, a method of adding a trace amount of a liquid chemical (chemical injection) is generally put into practical use by a method of pumping a chemical solution or pressing out a chemical filled in a sealed container with an inert gas.

[0003] In this case, if the flow rate of ultrapure water is constant, it is easy to inject chemicals so as to obtain a desired solute concentration. However, since the cleaning machines that actually use wafer cleaning water are composed of multiple units, the supply and stop of the cleaning water poured onto the wafer are controlled by opening and closing a plurality of valves, and the flow rate fluctuates irregularly. In response to this fluctuation, various methods of dissolution control are carried out, such as proportional control of the solute supplied with respect to the ultrapure water flow rate so that the solute concentration of the wafer cleaning water falls within a desired range, and PID control in response to the signal of the concentration monitor. However, a chemical injection control that can sufficiently follow the irregular flow rate fluctuations, particularly in a single-wafer cleaning machine having a plurality of cleaning chambers, has not been realized. As a countermeasure, it is conceivable to manufacture wafer cleaning water assuming the maximum usage amount and supply it to the cleaning machine. However, this would result in supplying a significantly excessive amount of wafer cleaning water, wasting expensive wafer cleaning water. Therefore, a wafer cleaning water supply device of a system that provides a storage tank for the purpose of saving wafer cleaning water and returns the wafer cleaning water not used in the cleaning machine to the storage tank for circulation has been proposed in Patent Document 1.

[0004] An example of a wafer cleaning water supply device of a system that provides this storage tank and returns the wafer cleaning water to the storage tank for circulation is shown in FIG. 4. In FIG. 4, the wafer cleaning water supply device 21 includes a storage tank 22, a supply pipe 23 for supplying ultrapure water W to the storage tank 22, and a circulating wafer cleaning water supply pipe 24 connected to the storage tank 22. The circulating wafer cleaning water supply pipe 24 is capable of sending the cleaning water W1 to the use point 26 via a liquid feed pump 25. A supply pipe 27 to which a chemical supply source 27A such as ammonia or hydrochloric acid and a liquid feed pump 27B are attached is connected to a liquid feed section (supply side 24A) between the wafer cleaning water supply pipe 24 on the liquid feed pump 25 side and the use point 26. Further downstream of this supply pipe 27, a membrane degassing device 28 and a gas dissolution membrane module 29 are sequentially provided. On the gas phase side of this gas dissolution membrane module 29, H 2 , CO 2 , O 3A gas supply pipe 30 is connected to a functional gas supply source 30A such as this. On the other hand, a separation membrane 31 is provided on the downstream side (return side 24B) from the use point 26 of the wafer cleaning water supply pipe 24. And in the storage tank 22, N 2 A gas supply pipe 32 connected to a gas source 32A is connected, and the inside of the storage tank 22 is purged with N 2 gas.

[0005] In the wafer cleaning water supply device 21 as described above, when a predetermined amount of ultrapure water W is stored in the storage tank 22, the liquid feed pump 25 is driven to supply it to the wafer cleaning water supply pipe 24, and a pH adjuster is added from the supply pipe 27 of the pH adjuster to adjust it to a desired pH. After removing excess dissolved gas components with the membrane degassing device 28, a desired functional gas component is dissolved by the gas dissolution membrane module 29 to adjust the cleaning water W1, and this cleaning water W1 is supplied to the use point 26 to perform cleaning. On the other hand, the unused cleaning water W1 is returned from the return side 24B to the storage tank 22 after removing fine particles by the separation membrane 31, thereby efficiently using the cleaning water W1. At this time, by purging the storage tank 22 with N 2 gas, oxygen does not dissolve in the stored ultrapure water W (ultrapure water W + cleaning water W1), and the dissolved oxygen (DO) does not increase. And when the amount of water stored in the storage tank 22 falls below a predetermined amount, ultrapure water W is replenished, so that the cleaning water W1 can be stably supplied to the use point 26.

[0006] In the functional water as described above, when dissolving a desired gas component, if a gas other than the desired dissolved gas dissolves, the saturation concentration of the desired dissolved gas decreases, and not only the concentration of the necessary gas component cannot be obtained, but also the pH and oxidation-reduction potential may be affected. As such a countermeasure, in Patent Document 1, a membrane degassing device 28 is installed in front of the gas dissolution membrane module 29. Also, in Patent Documents 2 and 3, it is described that a degassing membrane module is installed in front of the gas dissolution membrane module in order to remove the DO of the dissolved gas.

Prior Art Documents

Patent Documents

[0007] Patent Document 1 Japanese Patent Application Laid-Open No. 2018-182099 Patent Document 2 Japanese Patent Application Laid-Open No. 2014-225570 Patent Document 3 Japanese Patent No. 6020626 Summary of the Invention Problems to be Solved by the Invention

[0008] However, in the method of storing and circulating ultrapure water W in the storage tank 22, not only does oxygen dissolve in the washing water W1 during the circulation process, but also the oxygen present in the remaining space of the storage tank 22 dissolves, resulting in an increase in the dissolved oxygen (DO) of the functional water. Therefore, in order to suppress the DO of the circulating functional water, N 2 gas is purged into the storage tank 22. However, in this method, if the gas component dissolved in the washing water W1 is different from N 2 gas, N 2 dissolves in the supply water in the storage tank. Therefore, there is a concern that gas dissolution may not proceed sufficiently in the gas dissolution membrane module. As a countermeasure, it is conceivable to install a degassing membrane module in front of the gas dissolution membrane module as in Patent Documents 2 and 3. However, in this case, since the desired dissolved gas components contained in the functional water are also removed at the same time, there is a problem that the dissolution loss of the desired dissolved gas components increases. In addition, a membrane degassing device 28 must be installed in front of the gas dissolution membrane module 29, resulting in an increase in the components of the device and a larger installation space.

[0009] The present invention has been made in view of the above problems, and an object thereof is to provide a wafer washing water supply device capable of stably supplying washing water in which various gas components are dissolved. Means for Solving the Problems

[0010] In view of the above object, the present invention provides a wafer cleaning water supply device that supplies wafer cleaning water in which a functional gas is dissolved to a use point for ultrapure water or a chemical solution, comprising: a storage tank for ultrapure water, a chemical solution, or wafer cleaning water; a circulating wafer cleaning water supply pipe that returns from the storage tank to the storage tank via the use point; a liquid feeding means disposed between the storage tank and the use point of the wafer cleaning water supply pipe; and a supply pipe for replenishing the storage tank with ultrapure water, a chemical solution, or functional gas-dissolved water. A supply pipe for the same functional gas as the functional gas dissolved in the ultrapure water or the chemical solution is connected to the storage tank, and the space in the storage tank can be purged with the functional gas (Invention 1).

[0011] According to such an invention (Invention 1), by purging the same gas as the functional gas dissolved in the ultrapure water in the storage tank, it is possible to suppress the dissolution of other gas components in the ultrapure water and the wafer cleaning water stored in the storage tank. Therefore, the saturation concentration of the dissolved functional gas does not decrease, and wafer cleaning water with a stable functional gas concentration can be supplied to the use point.

[0012] In the above invention (Invention 1), it is preferable that a supply source of the ultrapure water or the chemical solution is connected to the supply pipe, the ultrapure water or the chemical solution is supplied from the supply pipe to the storage tank, and a gas dissolution membrane module for dissolving the functional gas is provided upstream of the use point of the circulating wafer cleaning water supply pipe (Invention 2).

[0013] According to such an invention (Invention 2), when adjusting the wafer cleaning water by dissolving a desired gas component in the ultrapure water or the chemical solution using the gas dissolution membrane module, the dissolution of gases other than the desired gas component in the ultrapure water or the chemical solution is suppressed. Therefore, it is not necessary to degas the dissolved gas with a membrane degassing device before the gas dissolution membrane module, and wafer cleaning water with a stable functional gas concentration can be supplied.

[0014] In the above invention (Invention 1), it is preferable that a supply source of functional gas-dissolved water in which a functional gas is dissolved in ultrapure water is connected to the supply pipe, and the functional gas-dissolved water is supplied from the supply pipe to the storage tank (Invention 3).

[0015] According to such an invention (Invention 3), in the functional gas-dissolved water of a desired gas component, since the dissolution of components other than the desired gas component is suppressed, it is possible to supply wafer washing water having a stable concentration of the functional gas.

[0016] In the above inventions (Inventions 1 to 3), it is preferable to provide a chemical solution injection mechanism upstream of the use point of the circulating wafer washing water supply pipe (Invention 4).

[0017] According to such an invention (Invention 4), it is possible to stably supply wafer washing water of gas-dissolved water in which a functional gas is dissolved and a pH adjuster or a redox potential adjuster is added.

[0018] In the above inventions (Inventions 1 to 4), a drainage mechanism is provided downstream of the use point of the circulating wafer washing water supply pipe, and a measuring means for the dissolved gas concentration in the wafer washing water returned from the use point to the storage tank is provided downstream of the drainage mechanism. When the numerical value of the dissolved gas concentration exceeds a predetermined value, it is preferable that the circulating wafer washing water supply pipe can be switched to the drainage mechanism side (Invention 5).

[0019] According to such an invention (Invention 5), the dissolved gas concentration in the wafer washing water returned to the storage tank is measured. When the numerical value of the dissolved gas concentration exceeds a predetermined value, it is regarded that a gas component other than the desired functional gas is dissolved, and the circulating wafer washing water supply pipe is switched to the drainage mechanism side and discharged, thereby suppressing the concentration of other gas components in the wafer washing water flowing through the circulation flow path including the storage tank, and continuously supplying wafer washing water having a stable dissolved concentration of the desired functional gas to the use point.

Advantages of the Invention

[0020] According to the wafer cleaning water supply device of the present invention, by purging the same gas as the functional gas dissolved in ultrapure water into the storage tank, it is possible to suppress the dissolution of other gas components into the ultrapure water or wafer cleaning water stored in the storage tank. Therefore, it is possible to supply wafer cleaning water with a stable concentration of the functional gas to the use point. As a result, there is no need to provide a degassing membrane device for removing other gas components, so the number of components of the device can be reduced and the installation space can also be made smaller. Furthermore, since the consumption of the functional gas can be reduced, it is also possible to reduce the environmental load.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0022] <First Embodiment> Hereinafter, a first embodiment of the wafer cleaning water supply device of the present invention will be described in detail with reference to the accompanying drawings.

[0023] 〔Wafer Cleaning Water Supply Device〕 Figure 1 shows a wafer cleaning water supply device according to a first embodiment of the present invention. In Figure 1, the wafer cleaning water supply device 1 includes a storage tank 2, a supply pipe 3 for supplying ultrapure water W from an ultrapure water supply source 3A to the storage tank 2, and a circulating wafer cleaning water supply pipe 4 connected to the storage tank 2. The circulating wafer cleaning water supply pipe 4 can supply cleaning water W1 to a use point 6 via a liquid delivery pump 5 as a liquid delivery means. And, on the liquid delivery pump 5 side (supply side 4A) between the wafer cleaning water supply pipe 4 and the use point 6, a supply pipe 7 to which a chemical liquid supply source 7A such as ammonia or hydrochloric acid and a liquid delivery pump 7B for this chemical liquid are attached is connected, and a gas dissolution membrane module 8 is provided on the downstream side of this supply pipe 7. On the gas phase side of this gas dissolution membrane module 8, a gas supply pipe 9 communicating with a functional gas supply source 9A such as H 2 , CO 2 , O 3 etc. is connected. In this embodiment, it is desirable not to use N 2 as a functional gas. On the other hand, a separation membrane 10 is provided on the downstream side (return side 4B) of the use point 6 of the wafer cleaning water supply pipe 4. In this embodiment, it is desirable not to use N 2 as a functional gas.

[0024] In such a wafer cleaning water supply device 1, a gas supply pipe 11 connected to a supply source 11A of the same functional gas as the functional gas dissolved by the gas dissolution membrane module 8 is connected to the storage tank 2, and the inside of the storage tank 2 can be purged with the functional gas. And, a discharge pipe 12 as a drainage mechanism is connected to the downstream side of the separation membrane 10 on the return side 4B of the wafer cleaning water supply pipe 4. On the upstream side of the connection point of this discharge pipe 12, a dissolved gas monitor 13 as a measuring means for the dissolved gas concentration is provided, and this dissolved gas monitor 13 is connected to a control means such as a personal computer (not shown). This control means can switch the returned cleaning water W1 between the wafer cleaning water supply pipe 4 side and the discharge pipe 12 side based on the detection value of the dissolved gas monitor 13.

[0025] (Ultrapure water) In this embodiment, as the ultrapure water W serving as raw water, for example, those having a resistivity of 18.1 MΩ·cm or more, particulates of 1000 pieces / L or less with a particle size of 50 nm or more, viable bacteria of 1 piece / 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°C are suitable.

[0026] (Chemical solution) As the chemical agent dissolved in the ultrapure water W, for example, a pH adjuster can be used. There is no particular limitation on this pH adjuster, but when adjusting to less than pH 7, acidic solutions such as hydrochloric acid, nitric acid, sulfuric acid, and acetic acid can be used. Further, when adjusting to pH 7 or more, alkaline solutions such as ammonia, sodium hydroxide, potassium hydroxide, or TMAH can be used. This pH adjuster also functions as a conductivity-imparting substance that imparts conductivity to the ultrapure water W.

[0027] In addition, a redox potential adjuster can also be added as a chemical agent. When adjusting the redox potential to be high (positive side), for example, hydrogen peroxide solution can be used. When adjusting the redox potential to be low (negative side), solutions such as oxalic acid, hydrogen sulfide, and potassium iodide can be used.

[0028] Either one of these pH adjusters or redox potential adjusters may be added, or both may be added.

[0029] [Supply method of wafer cleaning water] Next, a method for supplying wafer cleaning water using the wafer cleaning water supply device 1 of this embodiment having the configuration as described above will be described.

[0030] (Wafer cleaning water production process) First, ultrapure water W is supplied from the supply pipe 3 to the storage tank 2. When a predetermined amount of ultrapure water W has accumulated in this storage tank 2, the liquid feed pump 5 is driven to send the ultrapure water W to the wafer cleaning water supply pipe 4. At this time, the chemical solution supplied from the chemical solution supply source 7A is injected into the ultrapure water W at the confluence point of the supply pipe 7 to adjust the chemical solution. Then, functional gases such as H 2 , CO 2 , O 3 and the like are supplied from the functional gas supply source 9A to the gas phase side of the gas dissolution membrane module 8, and this is dissolved in the chemical solution to produce wafer cleaning water W1.

[0031] (Wafer cleaning water supply and return process) When the wafer cleaning water W1 is prepared in this way, it is supplied to the use point 6 and the required amount is consumed by a single-wafer cleaning machine or the like. The unused portion is returned to the storage tank 2 after the fine particles are removed by the separation membrane 10 from the return side 4B.

[0032] At this time, in this embodiment, the dissolved gas concentration of the wafer cleaning water W1 to be returned is measured by the dissolved gas monitor 13. If a gas different from the functional gas dissolved in the wafer cleaning water W1 dissolves during this circulation process, the dissolved gas concentration of the wafer cleaning water W1 increases. Therefore, when the measured value of the dissolved gas monitor 13 exceeds a predetermined control value, the wafer cleaning water supply pipe 4 is switched from the storage tank 2 to the discharge pipe 12 side and discharged to the outside, so that the dissolved gas concentration of the wafer cleaning water W1 circulating in the wafer cleaning water supply pipe 4 can be kept constant. This control value may be, for example, controlled to discharge the wafer cleaning water W1 when the dissolved gas concentration increases by 50% or more, particularly 30% or more, and further 10% or more with respect to the dissolved gas concentration due to the dissolution of the desired functional gas.

[0033] In this way, the wafer cleaning water W1 is returned to the storage tank 2. However, in this embodiment, since the storage tank 2 is purged with the same functional gas as the functional gas dissolved in the ultrapure water W1, no other gas components are dissolved in the storage tank 2, and the dissolved gas concentration of the functional gas in the wafer cleaning water W1 can be kept substantially constant. When the water level of the storage tank 2 drops below a predetermined value, ultrapure water W is supplied from the ultrapure water supply source 3A to the storage tank 2 through the supply pipe 3, and the production, supply, and return of the wafer cleaning water W1 as described above may be repeated.

[0034] In this way, in this embodiment, since the storage tank 2 is purged with the same gas as the functional gas dissolved in the ultrapure water W, it is possible to prevent gas components other than the functional gas from being dissolved in the ultrapure water W (or ultrapure water W + wafer cleaning water W1) in the storage tank 2. For this reason, it is not necessary to provide a degassing membrane device for removing other gas components, so the components of the wafer cleaning water supply device 1 can be reduced, and the installation space of the wafer cleaning water supply device 1 can also be reduced. Furthermore, since there is no loss associated with the degassing of the functional gas, its consumption can be reduced, contributing to the reduction of the environmental load.

[0035] <Second Embodiment> Next, a second embodiment of the present invention will be described.

[0036] [Wafer Cleaning Water Supply Device] FIG. 2 shows a wafer cleaning water supply device according to a second embodiment of the present invention. The wafer cleaning water supply device 1 of the second embodiment has the same configuration as that of the first embodiment described above, except that a supply source 3B of functional water (FW) as a chemical solution in which a chemical is dissolved in ultrapure water is connected to the storage tank 2 instead of the ultrapure water supply source 3A through the supply pipe 3, and it does not have a chemical supply source 7A, a chemical liquid feed pump 7B, and a supply pipe 7. The same components are denoted by the same reference numerals, and detailed description thereof is omitted.

[0037] [Method for Supplying Wafer Cleaning Water] Next, a method for supplying wafer cleaning water using the wafer cleaning water supply apparatus 1 of the present embodiment having the configuration as described above will be explained.

[0038] (Wafer Cleaning Water Manufacturing Process) First, functional water FW is supplied from the supply pipe 3 to the storage tank 2. When a predetermined amount of functional water FW has accumulated in this storage tank 2, the liquid feed pump 5 is driven to feed the functional water FW into the wafer cleaning water supply pipe 4. Functional gases such as H 2 , CO 2 , O 3 and the like are supplied to this functional water FW on the gas phase side of the gas dissolution membrane module 8 from the functional gas supply source 9A, and the wafer cleaning water W1 is manufactured by dissolving them.

[0039] (Wafer Cleaning Water Supply and Return Process) This prepared wafer cleaning water W1 is supplied and returned to the use point 6 in the same manner as in the first embodiment described above. At that time, when the measured value of the dissolved gas monitor 13 becomes equal to or higher than a predetermined control value, the wafer cleaning water W1 may be discharged to the outside from the discharge pipe 12.

[0040] In this way, the wafer cleaning water W1 is returned to the storage tank 2. However, in the present embodiment, since the storage tank 2 is purged with the same functionality as the functional gas dissolved in the functional water FW, it is possible to prevent gas components other than the functional gas from dissolving in the functional water FW (or functional water FW + wafer cleaning water W1) in the storage tank 2. As a result, in the storage tank 2, other gas components different from the functional gas do not dissolve, and the dissolved gas concentration of the wafer cleaning water W1 can be kept constant. When the water level of the storage tank 2 drops below a predetermined value, functional water FW is supplied from the functional water supply source 3B to the storage tank 2 via the supply pipe 3, and the production, supply, and return of the wafer cleaning water W1 as described above may be repeated.

[0041] <Third Embodiment> Hereinafter, a third embodiment of the present invention will be described.

[0042] [Wafer Cleaning Water Supply Apparatus] Figure 3 shows a wafer cleaning water supply device according to the third embodiment of the present invention. The wafer cleaning water supply device 1 of the third embodiment is the same as that of the second embodiment described above, except that in the storage tank 2, instead of the supply source 3B of the functional water (FW) in which the chemical solution is dissolved through the supply pipe 3, a supply source 3C of the wafer cleaning water W1 in which the chemical solution is further dissolved in the functional gas dissolved water obtained by dissolving the functional gas in the ultrapure water is connected. The supply side 4A of the wafer cleaning water supply pipe 4 does not have the gas dissolution membrane module 8, the functional gas supply source 9A, and the gas supply pipe 9, but has the fine particle removal filter 14. Therefore, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

[0043] 〔Method for Supplying Wafer Cleaning Water〕 Next, a method for supplying wafer cleaning water using the wafer cleaning water supply device 1 of the present embodiment having the configuration as described above will be described.

[0044] (Wafer Cleaning Water Supply Step) First, the wafer cleaning water W1 is supplied from the supply pipe 3 to the storage tank 2. When a predetermined amount of the wafer cleaning water W1 has accumulated in the storage tank 2, the liquid feed pump 5 is driven to feed the wafer cleaning water W1 to the wafer cleaning water supply pipe 4. The wafer cleaning water W1 is supplied to the use point 6 after the fine particles are removed by the fine particle removal filter 14.

[0045] (Wafer Cleaning Water Return Step) The required amount of the wafer cleaning water W1 is consumed by a single-blade type cleaning machine or the like at the use point 6, and the unused portion is returned to the storage tank 2 after the fine particles are removed by the separation membrane 10 from the return side 4B. Thereafter, as in the first embodiment described above, when the measured value of the dissolved gas monitor 13 becomes equal to or higher than a predetermined control value, the wafer cleaning water W1 may be discharged to the outside from the discharge pipe 12.

[0046] In this way, the wafer cleaning water W1 is returned to the storage tank 2. However, in this embodiment, since the storage tank 2 is purged with the same functionality as the functional gas dissolved in the wafer cleaning water W1, other gas components other than the functional gas do not dissolve in the wafer cleaning water W1 in the storage tank 2, and the dissolved gas concentration of the wafer cleaning water W1 can be kept constant. When the water level of the storage tank 2 drops below a predetermined value, functional water FW is supplied to the storage tank 2 from the supply source 3B of the functional water through the supply pipe 3, and the production, supply, and return of the wafer cleaning water W1 as described above may be repeated.

[0047] As described above, the present invention has been described based on the embodiments with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various modifications can be made. For example, in the first embodiment, the chemical solution is supplied to the supply side 4A from the supply source 7A of the chemical solution by the liquid feed pump 7B. However, without using the liquid feed pump 7B, the chemical solution is placed in a sealed container together with an inert gas such as N 2 gas, and a pressure extrusion type pump that extrudes this chemical solution by the pressure of the inert gas can also be preferably used. When adding a pH adjuster or a redox potential adjuster as the chemical solution, it may have a pH meter or an ORP meter for measuring the pH or the redox potential of the wafer cleaning water W1. And the injection amount of the chemical solution may be controlled based on this measured value. Further, in some cases, only the measurement of the dissolved gas concentration by the dissolved gas monitor 13 may be performed without providing the discharge pipe 12, and a degassing membrane such as a membrane degassing device may be provided in front of the storage tank 2 on the return side 4B as needed. Also, the dissolved gas concentration may be estimated by measuring an individual gas other than the functional gas to be dissolved, such as the dissolved oxygen concentration.

Example

[0048] The present invention will be described in more detail with the following specific examples.

[0049] [Example 1] In the wafer cleaning water supplying apparatus 1 shown in Fig. 1, after 150 L of ultrapure water W was supplied to the storage tank 2, the liquid supply pump 5 was driven to send this ultrapure water W to the supply side 4A of the wafer cleaning water supply pipe 4. Ammonia (conductivity imparting substance) was added to this ultrapure water W from the supply pipe 7 so that the conductivity was 1 µS / cm, and further hydrogen was added from the gas supply pipe 9 to the gas phase chamber side of the gas dissolved membrane module 8 so that the hydrogen concentration was 1.4 ppm, thereby producing wafer cleaning water W1.

[0050] This cleaning water W1 was supplied to a use point 6 equipped with a single-wafer cleaning machine, and the cleaning water W1 not used at the use point 6 was returned from the return side 4B of the wafer cleaning water supply pipe 4 to the storage tank 2 from which hydrogen gas had been purged after removing fine particles with a separation membrane 10, and the process was repeated while appropriately replenishing the storage tank 2 with ultrapure water W, thereby circulating the water. At this time, the dissolved gas concentration of the returned wafer cleaning water W1 was measured by a dissolved gas monitor 13, and when the dissolved gas concentration increased by 30% or more relative to the amount of dissolved hydrogen, the wafer cleaning water W1 was discharged from the discharge pipe 12, and when it became less than 20%, it was returned to the storage tank 2. When the dissolved gas concentration of the cleaning water W1 was measured after one hour had passed, it was possible to control the dissolved hydrogen gas concentration to within ±10% of the initial setting value.

[0051] [Comparative Example 1] In Example 1, N 2 The gas was purged and the ultrapure water W was appropriately replenished, and the water was circulated while being supplied to the point of use. At this time, the cleaning water W1 was not discharged based on the measurement result of the dissolved gas concentration, and the circulation was continued. When the dissolved gas concentration of the cleaning water W1 was measured after 1 hour, it was found that the dissolved gas concentration had increased by 100% or more compared to the amount of dissolved hydrogen, and it was presumed that gases other than hydrogen, such as oxygen, nitrogen, and carbon dioxide, had dissolved and the hydrogen concentration had decreased. The oxidation-reduction potential had changed, and the water was unsuitable as the wafer cleaning water W1 in Example 1.

[0052] [Example 2] In the wafer cleaning water supply device 1 shown in FIG. 1, after supplying 150 L of ultrapure water W to the storage tank 2, the liquid feed pump 5 was driven to feed this ultrapure water W to the supply side 4A of the wafer cleaning water supply pipe 4. To this ultrapure water W, ammonia (conductivity-imparting substance) was added from the supply pipe 7 so that the conductivity became 100 μS / cm, and further ozone (O 3 ) was added to the gas phase chamber side of the gas dissolution membrane module 8 from the gas supply pipe 9 so as to be 30 ppm to produce wafer cleaning water W1.

[0053] This cleaning water W1 was supplied to the use point 6 equipped with a single-wafer cleaning machine, and the cleaning water W1 not used at the use point 6 was separated by the separation membrane 10 from the return side 4B of the wafer cleaning water supply pipe 4 to remove fine particles, and then returned to the storage tank 2 from which ozone gas had been purged. While appropriately replenishing the storage tank 2 with ultrapure water W, this was repeated to circulate it. At this time, the dissolved gas concentration of the returned wafer cleaning water W1 was measured with the dissolved gas monitor 13. If the dissolved gas concentration increased by 30% or more with respect to the dissolved amount of ozone, the wafer cleaning water W1 was discharged from the discharge pipe 12, and if it became less than 20%, it was controlled to be returned to the storage tank 2. When the dissolved gas concentration of the cleaning water W1 after 1 hour had elapsed was measured, the dissolved ozone concentration could be controlled to be ±10% or less with respect to the initial set value.

[0054] [Comparative Example 2] In Example 2, N 2 gas was purged from the storage tank 2, and while appropriately replenishing ultrapure water W, this was repeated to circulate while supplying it to the use point. At this time, the cleaning water W1 was not discharged based on the measurement result of the dissolved gas concentration, and the circulation was continued. When the dissolved gas concentration of the cleaning water W1 after 1 hour had elapsed was measured, the dissolved gas concentration had increased by 100% or more with respect to the dissolved amount of ozone, and it was presumed that gases other than ozone, such as oxygen, nitrogen, carbon dioxide, etc., had dissolved and the ozone concentration had decreased, and it was inappropriate as the wafer cleaning water W1 in Example 2.

[0055] [Example 3] In the wafer cleaning water supply device 1 shown in Fig. 2, when functional water FW obtained by adding 100 ppm of hydrogen peroxide to ultrapure water was supplied to the 150 L storage tank 2, the liquid feed pump 5 was driven to feed this functional water FW to the supply side 4A of the wafer cleaning water supply pipe 4. To this functional water FW, carbon dioxide (CO 2 ) was added from the gas supply pipe 9 to the gas phase chamber side of the gas dissolution membrane module 8 so that the amount became 50 ppm, and wafer cleaning water W1 was produced.

[0056] This cleaning water W1 was supplied to the use point 6 equipped with a single wafer cleaning machine. The cleaning water W1 not used at the use point 6 was passed through the separation membrane 10 from the return side 4B of the wafer cleaning water supply pipe 4 to remove fine particles, and then returned to the storage tank 2 from which carbon dioxide had been purged. While appropriately replenishing the functional water FW to the storage tank 2, this was repeated to effect circulation. At this time, the dissolved gas concentration of the wafer cleaning water W1 to be returned was measured with the dissolved gas monitor 13. When the dissolved gas concentration increased by 30% or more with respect to the dissolved amount of carbon dioxide, the wafer cleaning water W1 was discharged from the discharge pipe 12, and when it became less than 20%, it was controlled to be returned to the storage tank 2. When the dissolved gas concentration of the cleaning water W1 after 1 hour had elapsed was measured, it was possible to control the dissolved carbon dioxide concentration to ±10% or less with respect to the initial set value.

[0057] [Comparative Example 3] In Example 3, N 2 gas was purged from the storage tank 2, and ultrapure water W was repeatedly and appropriately replenished to effect circulation while supplying it to the use point. At this time, the cleaning water W1 was not discharged based on the measurement results, and the circulation was continued. When the dissolved gas concentration of the cleaning water W1 after 1 hour had elapsed was measured, the dissolved gas concentration had increased by 100% or more with respect to the dissolved amount of carbon dioxide, and it was presumed that gases other than carbon dioxide, such as oxygen and nitrogen, had dissolved and the pH and oxidation-reduction potential had fluctuated, making it unsuitable as the wafer cleaning water W1 in Example 3.

Explanation of Reference Numerals

[0058] 1 Wafer cleaning water supply device 2 Storage tank 3 Supply pipe 3A Ultra-pure water supply source 4 Circulating wafer cleaning water supply pipe 4A Supply side 4B Return side 5 Liquid delivery pump (liquid delivery means) 6 Use point 7 Supply pipe 7A Chemical solution supply source 7B Liquid delivery pump 8 Gas dissolution membrane module 9 Gas supply pipe 9A Functional gas supply source 10 Separation membrane 11 Gas supply pipe 11A Functional gas supply source 12 Drain pipe (drainage mechanism) 13 Dissolved gas monitor (dissolved gas concentration measuring means) W Ultra-pure water W1 Cleaning water FW Functional water

Claims

1. A wafer cleaning water supply device that supplies wafer cleaning water in which a functional gas is dissolved to a use point for ultrapure water or a chemical solution, comprising: a storage tank for ultrapure water, a chemical solution, or wafer cleaning water; a circulating wafer cleaning water supply pipe that returns from the storage tank to the storage tank via the use point; a liquid feeding means disposed between the storage tank and the use point of the wafer cleaning water supply pipe; a supply pipe for replenishing the storage tank with ultrapure water, a chemical solution, or functional gas-dissolved water; a supply pipe of the same functional gas as the functional gas dissolved in ultrapure water or a chemical solution is connected to the storage tank, and the space in the storage tank can be purged with the functional gas; a supply source of ultrapure water or a chemical solution is connected to the supply pipe, ultrapure water or a chemical solution is supplied from the supply pipe to the storage tank, and a gas dissolution membrane module for dissolving the functional gas is provided upstream of the use point of the circulating wafer cleaning water supply pipe; a degassing device is not provided upstream of the gas dissolution membrane module; The wafer cleaning water supply device, wherein the functional gas is H2, CO2, or O3.

2. The wafer cleaning water supply device according to claim 1, wherein a supply source of functional gas-dissolved water in which a functional gas is dissolved in ultrapure water is connected to the supply pipe, and the functional gas-dissolved water is supplied from the supply pipe to the storage tank.

3. The wafer cleaning water supply device according to claim 1 or 2, further comprising a chemical liquid injection mechanism upstream of the use point of the circulating wafer cleaning water supply pipe.

4. A drainage mechanism is attached downstream of the use point of the circulating wafer cleaning water supply pipe, and a measuring means for the dissolved gas concentration in the wafer cleaning water returned from the use point to the storage tank is provided downstream of the drainage mechanism. When the numerical value of the dissolved gas concentration exceeds a predetermined value, the circulating wafer cleaning water supply pipe can be switched to the drainage mechanism side. The wafer cleaning water supply device according to any one of claims 1 to 3.

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