JPH0630792B2 - Treatment method of water supply treatment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is an ultrapure semiconductor for cleaning an intermediate product such as a semiconductor wafer or a chip (hereinafter referred to as a semiconductor wafer) in the electronic industry that produces an LSI or a VLSI. The present invention relates to a treatment method of a water supply treatment apparatus for producing water, and particularly to a primary treatment apparatus that combines raw water with coagulation sedimentation, filtration, activated carbon treatment, ion exchange treatment, reverse osmosis membrane treatment, microfiltration, ultraviolet irradiation treatment, etc. The present invention relates to a method for treating a water supply treatment device including a reverse osmosis membrane device for producing so-called ultrapure water by further treating the pure water obtained by the treatment at the end.

<Prior Art> In the electronic industry that produces LSIs and VLSIs, in cleaning semiconductor wafers, which are intermediate products, in order to improve the yield, the amount of ions and the amount of fine particles are changed.
Not only reduces to ppb order, but also the viable cell count is 10
-Requires so-called ultrapure water reduced to ^-1 piece / m1.

Therefore, conventionally, in producing such ultrapure water, raw water is coagulating and settling device, sand filter, activated carbon filter, 2-bed 3-tower pure water production device, reverse osmosis membrane device, ultraviolet irradiation device, mixed-bed polisher, etc. Of the ultrafiltration membrane (UF) immediately before the semiconductor wafer is washed.
Membrane) equipment is used to obtain so-called ultrapure water, which is used as washing water.

<Problems of conventional technology> However, recently, one of the factors that determines the yield of products is T.I. O. The amount of C (total organic carbon) is also pointed out, and T.C.
O. It is said that the smaller the amount of C is, the higher the yield of the product is. Therefore, in addition to the amount of ions, the amount of fine particles and the number of viable bacteria, T.C. O. C is also the target of the management. T. cerevisiae contained in water. O. Although C can be removed by a reverse osmosis membrane device, when various devices are installed in the latter stage of the reverse osmosis membrane device, the T.C. O. C was eluted, and the eluted T.
O. C is caused by a relatively low molecular weight organic substance, and most of it cannot be removed by the ultrafiltration membrane device described above.

Therefore, it is conceivable that the semiconductor wafer is treated again by the reverse osmosis membrane apparatus immediately before cleaning, but the use of the reverse osmosis membrane apparatus causes the following problems.

That is, due to the structure of the reverse osmosis membrane device, bacteria are likely to be generated, and therefore it is necessary to periodically perform sterilization treatment with hot water or hydrogen peroxide solution.

For example, when sterilizing with a hydrogen peroxide solution, the reverse osmosis membrane device is usually washed once a week with a 0.5 to 1% hydrogen peroxide solution, but such sterilizing treatment is not carried out. As a result, a large amount of viable bacteria leaks from the reverse osmosis membrane device. Therefore, as long as the reverse osmosis membrane device is used immediately before cleaning the semiconductor wafer, the sterilization treatment cannot be omitted.

However, when such sterilization is performed, there is a risk of impurities such as hydrogen peroxide leaking into the cleaning water of the semiconductor wafer, and therefore it is necessary to secure sufficient safety against the leakage of impurities such as hydrogen peroxide. Therefore, it is necessary to wash with a large amount of pure water after the sterilization treatment, but the pure water is the pure water produced at high cost by various devices as described above, and this is used for cleaning the reverse osmosis membrane device. It is very uneconomical to use a large amount.

<Purpose of the Invention> The present invention is based on the T.O. O. The purpose is to remove C with a reverse osmosis membrane device, to prevent impurities such as hydrogen peroxide from leaking to the treated water even if sterilization is performed, and to use pure water for cleaning as little as possible. It is what

<Means for Solving Problems> The present invention treats pure water treated in a primary treatment system with a reverse osmosis membrane device in the preceding stage, and the permeated water is then irradiated with an ultraviolet irradiation device,
Treated with a mixed bed type polisher using a cation exchange resin and an anion exchange resin, and then again treated with a reverse osmosis membrane device in the subsequent stage to obtain ultrapure water as a basic flow,
Regarding the sterilization treatment of the reverse osmosis membrane device, only the reverse osmosis membrane device in the subsequent stage is sterilized, and when the reverse osmosis membrane device that has finished the sterilization treatment is returned to the basic flow, the reverse osmosis membrane device in the previous stage is used. It is characterized by being used.

Hereinafter, the case where a hydrogen peroxide solution is used as the sterilization treatment of the present invention will be described in detail with reference to the drawings.

The drawings are explanatory views of a flow showing an example of an embodiment of the present invention, in which 1 is a first reverse osmosis membrane device, 2 is a second reverse osmosis membrane device,
Reference numeral 3 is a retention tank, 4 is an ultraviolet irradiation device, and 5 is a mixed bed polisher.

First, the process for producing ultrapure water in the present invention will be described. Pure water 6 supplied from the primary treatment system is pressurized by a high-pressure pump 7 and supplied to the first reverse osmosis membrane device 1 after sterilization treatment via a valve 8. Then, the T. O. C, fine particles, bacteria, etc. are removed, and the permeated water is sent to the retention tank 3 through the valve 9 and the pipe 10. On the other hand, the non-permeate water 11 is circulated and collected in the primary treatment system.

Next, the permeated water in the retention tank 3 is supplied to the ultraviolet irradiation device 4 by the low-pressure pump 12 and is sterilized again here. When the retention tank 3 is not installed, the permeated water of the first reverse osmosis membrane device 1 is directly supplied to the ultraviolet irradiation device 4.

Since the first reverse osmosis membrane device 1 is immediately after being sterilized with a hydrogen peroxide solution as described in the sterilization step described later, the permeated water may contain a small amount of hydrogen peroxide. The remaining hydrogen peroxide can be decomposed and removed by subjecting the residual hydrogen peroxide to ultraviolet treatment by the ultraviolet irradiation device 4.

The treated water after such ultraviolet treatment is then treated with the mixed bed polisher 5.

Even if high-purity pure water is irradiated with ultraviolet rays, its specific resistance value is generally lowered, but in the present invention, since the mixed bed polisher 5 is used after the irradiation with ultraviolet rays, the specific resistance value can be increased to the limit value. it can.

The mixed bed type polisher 5 used in the present invention uses a so-called mixed bed type cartridge having no regeneration mechanism filled with a sufficiently regenerated mixed resin of an H type cation exchange resin and an OH type anion exchange resin. An ordinary mixed bed polisher having a regeneration mechanism may be used.

Then, the treated water of the mixed bed polisher 5 is supplied to the high pressure pump 1
3 and pressurized via valve 14 into the second reverse osmosis membrane device 2 where it is finally transferred to T.M. O. Ultrapure water, which is permeated water from which C has been removed, is obtained, and the ultrapure water is fed to the semiconductor wafer cleaning step via the valve 15. The generated non-permeated water 11 is circulated and collected in the primary treatment system.

Since the reverse osmosis membrane device is installed in the final stage of the treatment as described above, even a small amount of T.O. O. Even if C leaks, the T.C. O. C can be reduced as much as possible.

Next, the sterilization step in the present invention will be described.

After performing the above-described ultrapure water production process for a certain period of time, the second reverse osmosis membrane device 2 is separated from the water flow for sterilization treatment as described below.

That is, the valve 22 is opened in front of the high-pressure pump 7 to inject hydrogen peroxide solution, and the hydrogen peroxide solution diluted with pure water 6 is supplied to the second reverse osmosis membrane device 2 via the valve 17 to effect the peroxidation. The permeated water containing hydrogen is discharged through the valve 21, and the non-permeated water containing hydrogen peroxide is also discharged. The sterilization process is 0.5-1%
Is washed with the hydrogen peroxide solution of about 2 hours,
In particular, the treatment is not limited to the hydrogen peroxide solution treatment, and any treatment can be used as long as it can sterilize sterilizers attached to the membrane surface of the reverse osmosis membrane.

When the cleaning of the hydrogen peroxide solution is completed, then the valve 22
Is closed, and pure water 6 alone is fed to the second reverse osmosis membrane device 2 for cleaning. About 1 hour is sufficient for the cleaning.

The operation of the first reverse osmosis membrane device 1 may be interrupted during the sterilization treatment, but the following operation may be performed. That is, the accumulated water in the retention tank 3 is supplied to the first reverse osmosis membrane device 1 through the low-pressure pump 12, the ultraviolet irradiation device 4, the mixed-bed polisher 5, the high-pressure pump 13, and the valve 16, and is the permeated water obtained. Pure water is fed to the semiconductor wafer cleaning process through the valve 20.

That is, while sterilizing the latter reverse osmosis membrane device,
Using only the first reverse osmosis membrane device 1 used as the former stage,
The transparent processing is continued.

By installing the retention tank 3 in the middle of the two reverse osmosis membrane devices as in the present embodiment, the permeated water is treated as the treated water while the sterilization treatment is performed on one of the reverse osmosis membrane devices. It can be supplied continuously.

When the sterilization treatment of the second reverse osmosis membrane device 2 is completed, the second reverse osmosis membrane device 2 is positioned in the front stage, and the first reverse osmosis membrane device 1 used in the front stage immediately before the sterilization treatment is moved to the rear stage. After that, the manufacturing process of ultrapure water is restarted. That is, the pure water 6 is pressurized by the high-pressure pump 7, supplied to the second reverse osmosis membrane device 2 via the valve 17, and the permeated water is supplied to the retention tank 3 via the valve 19 and the pipe 10. Permeated water obtained by supplying the accumulated water in the retention tank 3 to the first reverse osmosis membrane device 1 through the low pressure pump 12, the ultraviolet irradiation device 4, the mixed bed polisher 5, the high pressure pump 13, and the valve 16. Ultra pure water valve 2
0 to the semiconductor wafer cleaning process. Even if a slight amount of hydrogen peroxide remains in the permeated water of the second reverse osmosis membrane device 2 immediately after the sterilization treatment, as described above, the permeated water is irradiated with ultraviolet rays and can be decomposed and removed. is there. When the retention tank 3 is not installed as in the case described above, the permeated water of the second reverse osmosis membrane device 2 is directly supplied to the ultraviolet irradiation device 4.

Next, the sterilization step in the present invention will be described again.

After performing the above-described ultrapure water production process for a certain period of time, the first reverse osmosis membrane device 1 is separated from the water flow and sterilized.
That is, the valve 22 is opened before the high-pressure pump 7 to inject hydrogen peroxide, and the hydrogen peroxide solution diluted with pure water 6 is supplied to the valve 8
Is supplied to the first reverse osmosis membrane device 1 through the valve 1, the permeated water containing hydrogen peroxide is discharged through the valve 18, and the non-permeated water containing hydrogen peroxide is also discharged.

On the other hand, while the sterilization process is being performed, the operation of the second reverse osmosis membrane device 2 may be interrupted as described above, or the following operation may be performed. That is, the accumulated water in the retention tank 3 is supplied to the second reverse osmosis membrane device 2 via the low-pressure pump 12, the ultraviolet irradiation device 4, the mixed bed polisher 5, the high-pressure pump 13, and the valve 14, and is the permeated water obtained. Pure water is supplied to the semiconductor wafer cleaning process through the valve 15.

After the sterilization process of the first reverse osmosis membrane device is completed, the pure water 6 supplied from the primary treatment system is used to supply the first reverse osmosis membrane device 1, the ultraviolet irradiation device 4, the mixed-bed polisher 5, and the second reverse osmosis membrane device 2. The process of producing ultrapure water, which is processed in this order, is restarted.

<Effects of the Invention> As described above, according to the present invention, the reverse osmosis membrane device is installed at the final stage of the ultrapure water feed treatment device.
O. Since C can be reduced as much as possible, two reverse osmosis membrane devices are skillfully combined, and an ultraviolet irradiation device and a mixed bed polisher are installed between the two reverse osmosis membrane devices. Even if the sterilization treatment is performed, leakage of impurities such as hydrogen peroxide into the final treated water can be eliminated as much as possible.

In other words, when returning to the water treatment process after the reverse osmosis membrane device after sterilization treatment, be sure to use the first stage so that even if impurities such as hydrogen peroxide leak into the permeated water, this can be performed by the second stage UV irradiation device. Even if it can be decomposed and the specific resistance value is lowered by the ultraviolet irradiation device, the electrolyte can be removed to the limit value by the mixed bed type polisher in the subsequent stage. O. Even if C leaks, it can be reduced as much as possible by the reverse osmosis membrane device in the latter stage.

Further, the reverse osmosis membrane device used as the first stage after the sterilization treatment is sufficiently washed during the permeation treatment until the reverse osmosis membrane device of the second stage is sterilized. When used as, the impurities such as hydrogen peroxide are completely washed away, and therefore, impurities such as hydrogen peroxide never leak into the final treated water.

In this way, two reverse osmosis membrane devices are skillfully used, the reverse osmosis membrane device after sterilization is always in the previous stage, and a small amount of impurities such as hydrogen peroxide remaining after the sterilization treatment is absorbed during the permeation treatment of the reverse osmosis membrane device. Since it can be washed, the amount of washing water used after the sterilization treatment can be significantly reduced.

Examples of the present invention will be described below.

Example Raw water turbidized by a turbidity filtration device was treated with a two-bed, three-column pure water production device, the treated water was deaerated with a vacuum deaeration tower, and then treated with a mixed-bed pure water production device. Pure water was stored in the pure water tank. This pure water was sent to the low-pressure reverse osmosis membrane device in the previous stage with a high-pressure pump. The pressure at that time is 18 kg / cm ² G.

The permeated water was treated with an ultraviolet irradiation device and a mixed bed type cartridge, and then was sent to a low-pressure reverse osmosis membrane device in the subsequent stage by a high-pressure pump. The reverse osmosis membrane device in the latter stage was subjected to permeation treatment for 9 hours, then sterilized with 0.5% hydrogen peroxide solution for 2 hours, and then washed with pure water for 1 hour.

Such sterilization treatments were sequentially performed, and the reverse osmosis membrane device subjected to the sterilization treatment was always used as the first stage, and the operation was continued for 3,000 hours. The water quality of the permeate of the latter stage reverse osmosis membrane device was as shown in Table 1.

[Brief description of drawings]

Drawing is an explanatory view of a flow showing an example of an embodiment of the present invention. 1 ... First reverse osmosis membrane device, 2 ... Second reverse osmosis membrane device 3 ... Retention tank, 4 ... Ultraviolet irradiation device 5 ... Mixed bed polisher, 6 ... Pure water 7 ... High-pressure pump, 8 ... Valve 9 ... Valve, 10 ... Pipe 11 ... Impermeable water, 12 ... Low pressure pump 13 ... High pressure pump, 14-22 ... Valve

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C02F 1/44 J 8014-4D

Claims (1)

[Claims] 1. Pure water produced by a primary treatment system is treated by a reverse osmosis membrane device in the preceding stage, then an ultraviolet irradiation device and a mixed bed polisher in this order, and then by a reverse osmosis membrane device in the latter stage. A method for treating a water supply treatment device for producing ultrapure water, wherein when sterilizing a reverse osmosis membrane device, only the reverse osmosis membrane device located in a subsequent stage is sterilized, and the ultrapure water is produced after the sterilization treatment. When restarting the process, the reverse osmosis membrane device after the sterilization treatment is placed in the front stage, and the reverse osmosis membrane device that was located in the front stage just before the sterilization treatment is placed in the rear stage to produce ultrapure water. A method of treating a water supply treatment device, which is characterized in that