JPH0630794B2 - Ultrapure water production system for semiconductor cleaning - Google Patents

Description

The present invention relates to a device for producing ultrapure water, and more specifically, it removes low-molecular organic compounds that cannot be removed by conventional devices,
The present invention relates to an apparatus for producing ultrapure water that is closer to theoretical pure water.

In general, ultrapure water is used in large quantities in the manufacture of LSIs, VLSIs, etc., and the demand is increasing more and more in the future. As these ultrapure water, those having a specific resistance of 17 to 18 MΩ · cm have been manufactured, but efforts have been made to bring them closer to the specific resistance of theoretical pure water (water consisting of only H ₂ O) of 18.24 MΩ · cm. The current situation is.

Conventionally, the ultrapure water production process is composed of activated carbon, ion exchange resin, UV oxidation, reverse osmosis membrane (RO), ultrafiltration membrane (UF) and the like.

For example, an ultrapure water production process including a cleaning waste liquid recovery step from a semiconductor wafer cleaning system using ultrapure water is as shown in FIG. In the device shown in FIG.
Waste water from the semiconductor washing step 1 is first subjected to activated carbon adsorption treatment in an activated carbon adsorption tower 2 of a recovery system A, treated in an ion exchange tower 3 for desalting, and then when necessary, a reverse osmosis membrane device (not shown). And is treated by the ultraviolet oxidation device 4 via. In the ultraviolet oxidation device 4, in order to almost completely oxidize and decompose organic substances, hydrogen peroxide is generally added as an oxidant, and ultraviolet rays are irradiated in the presence of hydrogen peroxide to perform the treatment.

The treated water from the recovery system A including the activated carbon adsorption tower 2, the ion exchange tower 3, and the ultraviolet oxidation device 4 is returned to the pure water production system B. This pure water production system B
Is a pretreatment system C (coagulation reaction tank 5 and two tank filter 6
Consists of. ) Primary pure water system D (reverse osmosis membrane device 7,
It consists of a deaerator 8 and an ion exchange tower 9. ) And subsystem E (UV sterilizer 10, mixed bed type ion exchanger 11)
And an ultrafiltration device 12. ). With such a device, the ions in the treated raw water are almost completely removed, and the specific resistance of the final treated water becomes high purity of 17 MΩ · cm or more.

However, in the case of the conventional apparatus as described above, the low molecular weight organic compounds contained in the treated raw water, especially the organic halogen compounds cannot be removed, and leaks into the final treated water of the subsystem, which results in total organic carbon (TOC). There was a problem that the required water quality was not met. Also,
Organohalogen compounds such as trihalomethane can be removed by activated carbon, but there is a problem that the treatment capacity is small and that bacteria grow on the activated carbon layer during long-term liquid passage.

The present invention solves the problems of the conventional device as described above,
It is an object of the present invention to provide a device for producing ultrapure water that is closer to logical pure water by removing low molecular weight organic compounds that could not be removed by conventional devices and further reducing TOC.

The present inventor has conducted various studies to remove organic halogen compounds such as chloroform, trichloroethane, trichloroethylene, bromodichloromethane, tetrachloroethylene, chlorodibromomethane and bromoform which cannot be removed by conventional devices, and these low molecular weight compounds have been removed. Organic compounds are removed by synthetic adsorbents and TO
The inventors have found that C is reduced and have completed the present invention. That is, the ultrapure water production system of the present invention produces pure water from treated water of a raw water pretreatment system including a filter and a pretreatment system including a membrane treatment device having a membrane such as a reverse osmosis membrane. From the primary pure water system to be obtained, and the subsystem for obtaining ultrapure water from pure water of the primary pure water system equipped with a mixed-bed type ion exchanger and a membrane treatment device incorporating a membrane such as an ultrafiltration membrane In the ultra pure water producing apparatus for semiconductor cleaning, the resin substrate is selected from styrene-vinylbenzene type, methacrylic acid ester type, pinylpyridine type, sulfoxide type and amide type downstream of the membrane treatment of the primary pure water system. In addition, a synthetic adsorbent column containing a synthetic adsorbent without an ion exchange group is interposed.

The synthetic adsorbent used in the present invention is a gel-type or porous-type resin having no ion-exchange group, and the substrate is styrene-divinylbenzene-based, methacrylic acid ester-based, vinylpyridine-based, sulfoxide-based resin. Alternatively, it is an amide type and is prepared by washing with an organic solvent and heated caustic soda together to remove the TOC component. The structure of the synthetic adsorbent column containing these synthetic adsorbents may be the same as that of a generally used ion exchange column. That is, instead of the cation or anion exchange resin in the ion exchange column, the above-mentioned synthetic adsorbent may be incorporated. That is, a water collecting mechanism that does not allow the synthetic adsorbent to pass but allows water to pass is provided at the lower part of the tower, and the synthetic adsorbent is laminated on this.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1 showing an embodiment of the present invention.

In FIG. 1, raw water is passed from a left side to a pretreatment system C including a coagulation reaction tank 5 and a two-layer filter 6 as indicated by an arrow, and pretreated. The treated water after this pretreatment is then
Water is successively passed through a primary pure water system D including a reverse osmosis device 7, a synthetic adsorbent tower 13, a deaerator 8 and an ion exchange tower 9 to obtain pure water. The pure water obtained by the primary pure water system D is then converted into ultrapure water by the subsystem E including the ultraviolet sterilizer 10, the mixed bed ion exchanger 11 and the ultrafiltration membrane device 2.

The above-described ultrapure water production system B including the systems C, D, and E of FIG. 1 is different from the conventional apparatus shown in FIG. 2 in that the synthetic adsorbent tower 13 is installed. The synthetic adsorbent tower 13 almost completely removes the low-molecular organic compounds described above. In addition, since the organic compound adsorption capacity of the synthetic adsorbent decreases as the water flow continues, it is periodically regenerated with a chemical such as caustic soda.

When the synthetic adsorbent tower 13 is installed in the flow of the primary pure water system D as shown in FIG. 1, it is provided after the reverse osmosis device 7. That is, by providing after the reverse osmosis device 7, the suspended suspension (SS) is removed by the reverse osmosis device 7, and the rise of the differential pressure of the synthetic adsorbent column 13 can be prevented.

The processing flow rate in such an ultrapure water production system is SV
= 5 to 50 hr ^-1 , preferably SV = 10 to 30 hr ^-1 .

The obtained ultrapure water can be used for various purposes, and FIG. 1 shows an example used for cleaning semiconductors. That is, the ultrapure water obtained by the apparatus of the present invention is used for the semiconductor cleaning (use point) 1 of LSI or VLSI, and the water mixed with impurities by this is activated carbon adsorption tower 2, ion exchange tower 3 and It is recovered by the recovery system A composed of the ultraviolet oxidation device 4, returned to the inlet of the primary pure water system D, and is recycled. The water recovered from the recovery system A may be returned to the inlet of the pretreatment system C.

Next, an experimental example is shown.

Example 1 Synthetic water containing an organic halogen compound was passed through 100 ml of a synthetic adsorbent (Lewatit (trademark) E400 / 83 manufactured by Bayer Co., Ltd.) which is a copolymer of styrene and divinylbenzene at SV = 10 hr ⁻¹ . However, the results shown in Table 1 were obtained. That is, the organic halogen of the treated water was significantly reduced.

Experimental Example 2 An ultrapure water production system in which city water was installed at the outlet of a reverse osmosis system 7 as shown in FIG. 1 and a synthetic adsorbent tower 13 filled with 100 of synthetic adsorbent Lewatit (trademark) E400 / 83 was installed. As shown in FIG. 2, water was passed through an apparatus in which the synthetic adsorbent 13 was not installed for 30 days, and the treated water of the subsystem (the TOC concentration of ultrapure water used at the point of use was compared.

The results are shown in Table 2.

In the ultrapure water production system of the present invention as described above, the synthetic adsorbent tower containing the special synthetic adsorbent is installed on the downstream side of the membrane treatment of the primary pure water system in the ultrapure water production system.
It has the effect that low molecular weight organic compounds, which were difficult to remove with conventional equipment, can be removed, and TOC can be further reduced to obtain ultrapure water extremely close to theoretical water.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a system flow of an ultrapure water production system showing an embodiment of the present invention. FIG. 2 is a schematic explanatory view of the system flow of the conventional device. 1 …… Semiconductor cleaning (use point) 2 …… Activated carbon adsorption tower 3 …… Ion exchange tower 4 …… UV oxidizer 5 …… Coagulation reaction tank 6 …… Two-layer filter, 7 …… Reverse osmosis equipment 8 ...... Deaerator, 9 …… Ion exchange tower 10 …… UV sterilizer, 11 …… Mixed bed ion exchanger 12 …… Ultrafiltration device, 13 …… Synthetic adsorbent tower A …… Collection system, B …… Ultrapure water production system C …… Pretreatment system, D …… Primary pure water system E …… Subsystem

Claims (1)

[Claims] 1. A primary pure water system for obtaining pure water from treated water of a raw water pretreatment system including a filter and the like, and a pretreatment system including a membrane treatment device including a membrane such as a reverse osmosis membrane. And a subsystem for obtaining ultrapure water from pure water of a primary pure water system equipped with a mixed-bed type ion exchanger and a membrane treatment device including a membrane such as an ultrafiltration membrane. In the water producing device, an ion exchange group whose resin substrate is selected from a styrene-divinylbenzene type, a methacrylic acid ester type, a vinylpyridine type, a sulfoxide type and an amide type is provided on the downstream side of the membrane treatment device of the primary pure water system. An ultrapure water production system for cleaning semiconductors, characterized in that a synthetic adsorbent tower containing a synthetic adsorbent without a gas is interposed.