JP2920864B2 - Ultrapure water production equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing ultrapure water, and more particularly, to an apparatus for producing ultrapure water installed in a semiconductor factory or the like, for producing ultrapure water requiring a nitrogen gas purge. Related to the device.

[0002]

2. Description of the Related Art Generally, a semiconductor factory is provided with an apparatus for producing ultrapure water, and a water tank provided in the apparatus is purged with nitrogen gas to prevent external contamination. .

That is, as shown in FIG. 2, a conventional ultrapure water producing apparatus of this type stores primary pure water obtained by various deaerators 1a such as vacuum deaerator and membrane deaerator. 1 to do
A secondary pure water tank 2a, a nitrogen gas purge device 3a for injecting nitrogen gas into the primary pure water tank 2a, and a UV device 4a for sterilization,
Ultrapure water tank for storing pure water supplied from primary pure water
5a, a nitrogen gas purging device 6a for injecting nitrogen gas into the ultrapure water tank 5a, and a secondary pure water device 7a for purifying when the pure water in the ultrapure water tank 5a is recycled. is there.

In such an apparatus for producing ultrapure water, the pure water in the primary pure water tank 2a is circulated and recycled to be purified by the circulation flow path 8a, and the circulation flow path 9a and the circulation flow path 10a Thus, the ultrapure water in the ultrapure water tank 5a is circulated and recycled for purification.

[0005]

However, in such a conventional apparatus for producing ultrapure water, the circulation channels 8a, 9a, 10a
In order to make the pure water circulated and recycled into the primary pure water tank 2a and ultrapure water tank 5a while sprinkling water from above,
The sprinkling disturbs the liquid surface and dissolves the purged nitrogen gas in the ultrapure water, and the nitrogen gas becomes bubbles, causing impurities to adhere to the bubble particles, which may adversely affect the wafer cleaning. There was a point.

[0006] In particular, when ultrapure water is heated, the generation of bubbles becomes remarkable as the temperature rises, and thus the above-mentioned problems have become more remarkable.

[0007] The present invention has been made to solve such problems, and an object of the present invention is to prevent the generation of bubbles in ultrapure water as described above, particularly, the generation of bubbles during heating. Is what you do.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a means for solving the problems is to store primary pure water obtained by various deaeration means. And a super pure water tank 5 for storing pure water supplied from the primary pure water tank 2 as ultra pure water.
Nitrogen gas purging devices 3 and 6 for injecting nitrogen gas into the primary pure water tank 2 and the ultrapure water tank 5, respectively;
In order to circulate the pure water and the ultrapure water of the secondary pure water tank 2 and the ultrapure water tank 5, respectively, a circulation flow path connected to the primary pure water tank 2 and the ultrapure water tank 5 via a supply unit and a discharge unit is provided. In the apparatus for producing ultrapure water provided, the supply units of the circulation channels of the primary pure water tank 2 and the ultrapure water tank 5 are connected below the liquid levels of the primary pure water tank 2 and the ultrapure water tank 5. It is to be done.

[0009]

That is, as described above, the supply portions of the respective circulation flow paths of the primary pure water tank 2 and the ultrapure water tank 5 are connected to the lower part of the liquid level of the primary pure water tank 2 and the ultrapure water tank 5. Therefore, the nitrogen gas is not entrained in the ultrapure water during the circulation, and the purged nitrogen gas is not dissolved in the ultrapure water.

[0010]

Embodiments of the present invention will be described below. In FIG. 1, reference numeral 1 denotes a deaerator for performing various types of deaeration such as vacuum deaeration and film deaeration, and 2 denotes a primary pure water tank 2 for storing the primary pure water obtained by the deaerator 1. A level gauge section 11 and a pure water sampling section 12 are connected to the primary pure water tank 2, and a valve 13 is provided between the level gauge section 11 and the pure water sampling section 12.

Reference numeral 3 denotes a nitrogen gas purging device for purging nitrogen gas into the primary pure water tank 2, which is provided above the primary pure water tank 2.

8 circulates pure water in the primary pure water tank 2;
A circulation channel connected to the primary deionized water tank 2 via a supply part 14 and a discharge part 15 in order to recycle the supply part 14 from the side below the liquid level of the primary deionized water tank 2 It is arranged to be.

Reference numeral 4 denotes a sterilizing ultraviolet device, which is provided in the middle of the circulation channel 8.

Reference numeral 5 denotes an ultrapure water tank for storing pure water supplied from the primary pure water tank 2 as ultrapure water. The ultrapure water tank 5 is connected to an intermediate portion of the circulation channel 8 via a channel 16. I have.

Reference numeral 6 denotes a nitrogen gas purging device for purging nitrogen gas into the ultrapure water tank 5, which is provided above the ultrapure water tank 2.

Reference numerals 9 and 10 denote circulation flow paths connected to the primary pure water tank 2 via supply units 18 and 19 and a discharge unit 20 so as to circulate and recycle the ultrapure water in the ultrapure water tank 5. In the discharge section
20 is shared by the two flow paths 9 and 10.

Reference numeral 7 denotes a secondary pure water device for purifying the pure water in the ultrapure water tank 5 when circulating and recycling the pure water, and is provided in the middle of the flow passage 10. The secondary pure water device 7 is constituted by, for example, an ultraviolet irradiation device, an ion exchange device, an ultrafiltration membrane and the like.

Reference numeral 21 denotes an ultrapure water sampling unit, and a valve 22
Is connected to the flow path 10 via a.

The case where ultrapure water is produced by the ultrapure water production apparatus having the above configuration will be described.
First, a variety of deaerators 1 such as vacuum deaerator and film deaerator 1
The secondary pure water is manufactured, and the primary pure water is supplied to the primary pure water tank 2 and stored in the primary pure water tank 2.

Next, nitrogen gas is sent into the primary pure water tank 2 by the nitrogen gas purging device 3 to perform nitrogen gas purging.

The primary pure water in the primary pure water tank 2 is supplied to a discharge section.
15 from the supply unit 14
Next, it is supplied into the pure water tank 2.

In this case, the supply section 14 of the circulation flow path 8
Is disposed below the level of pure water in the primary pure water tank 2 so as to be connected from the side, so that nitrogen gas is not involved in pure water during circulation, The nitrogen gas injected into the primary pure water tank 2 from the nitrogen gas purging device 3 does not dissolve in the pure water circulating through.

Further, since the ultraviolet device 4 for sterilization is provided in the middle of the circulation channel 8, the primary pure water circulated by the ultraviolet device 4 is sterilized.

As described above, contamination from the outside is prevented by the nitrogen gas purge, and the primary pure water in the primary pure water tank 2 which has been circulated and recycled in the circulation channel 8 while being sterilized by ultraviolet irradiation is purified. Channel 16 as ultrapure water
And supplied to the ultrapure water tank 5 and stored in the ultrapure water tank 5.

Next, nitrogen gas is fed into the ultrapure water tank 5 to which the ultrapure water is supplied and stored by the nitrogen gas purging device 6, and the nitrogen gas is purged in the same manner as in the primary pure water tank 2 side.

The ultrapure water in the ultrapure water tank 5 is supplied to a discharge section.
The water is discharged from the circulation path 20, and circulates through the two circulation paths 9, 10, and is supplied into the ultrapure water tank 5 from the supply portions 18, 19 of the respective circulation paths 9, 10.

In the ultrapure water tank 5 as well, the circulation passages 9, 1
0 is disposed so as to be connected to the storage portion of the pure water in the ultrapure water tank 5 from the side, so that the circulation passages 9, 19 are provided similarly to the primary pure water tank 2 side. 10 to pure water circulating,
The nitrogen gas from the nitrogen gas purge device 6 does not dissolve.

In the middle of the circulation channel 10 of the two circulation channels 9, 10, the secondary pure water constituted by the above-described ultraviolet irradiation device, ion exchange device, ultrafiltration membrane and the like is provided. Since the device 7 is provided, the ultrapure water is further purified by the secondary pure water device 7.

As described above, the contamination from the outside is prevented by the nitrogen gas purge, and the ultrapure water tank 5 circulated and recycled in the circulation passages 9 and 10 while the purification is promoted by the secondary pure water device 7. Is supplied to a semiconductor factory or the like after processing such as heating.

As described above, in this embodiment, in both the primary pure water tank 2 and the ultrapure water tank 5,
The supply sections 14, 18, and 19 of the pure water circulation paths 8, 9, and 10 are provided below the liquid levels of the primary pure water tank 2 and the ultrapure water tank 5 so as to be connected from the side. For both pure water tanks 2,
In both cases, mixing of nitrogen gas is prevented, and as a result, generation of bubbles during the heat treatment is prevented.

Incidentally, pure water is sampled from the primary pure water tank 2 or the ultrapure water tank 5 as described above, and the water is heated using a heating device as shown in FIG. And then the dissolved gas amount was determined. In addition, the generated gas was collected and subjected to chemical analysis.

This will be described in more detail. The pure water sampling unit on the primary pure water tank 2 side in the ultrapure water production apparatus is described below.
When the pure water sampled by the sample 12 and the sampling section 21 on the side of the ultrapure water tank 5 is heated by the heater 23 shown in FIG. 3, bubbles are generated in the collection bottle 24, and the bubbles are generated by the sample for gas analysis. The collected gas is collected in the bag 25, the dissolved gas amount is determined by the collected gas, and the chemical analysis is performed.

The measurement was performed at 40 ° C., 55 ° C., 70 ° C., and 80 ° C., respectively.

Further, the amount of gas generated by heating was compared with pure water and ultrapure water sampled by a conventional ultrapure water producing apparatus.

FIG. 4 shows a graph of the result.

In FIG. 4, (a) relates to the amount of gas generated by heating pure water sampled from a pure water tank, and (b) relates to gas generated by heating ultrapure water sampled from an ultrapure water tank. It is about quantity.

In the graph of FIG. 4A, A shows the measurement results of the present embodiment, and BF show the results of measurements at a plurality of factories equipped with the conventional apparatus.

Also, in the graph of FIG. 4B, a shows the measurement result of this embodiment, and b to h show the results of measurement at a plurality of factories equipped with the conventional apparatus.

As is clear from the results shown in FIG. 4, in the sample sampled by the conventional manufacturing apparatus, almost no bubbles are generated at a water temperature of about 40 ° C., but the amount of generated gas increases as the temperature increases. At a temperature of 80 ° C., considerable gas evolution was observed.

On the other hand, in the present embodiment, almost no gas was generated even when heated to 80 ° C. as well as when the temperature was low.

In the above embodiment, the ultraviolet device 4 is provided in the middle of the circulation flow path 8 on the primary pure water tank 2 side, and the secondary water purification apparatus is provided in the middle of the circulation flow path 10 on the ultrapure water tank 5 side. 7 was provided,
The preferable effect of increasing the purity of pure water and ultrapure water circulated and recycled in the primary pure water tank 2 and the ultrapure water tank 5, respectively, was obtained. Provision is not an essential condition of the present invention.

The design of each of the other components can be freely changed within the range intended by the present invention.

Further, in the above embodiment, the circulation flow path 8,
The supply units 14, 18, and 19 of 9, 10 are connected to the storage portions of the primary pure water tank 2 and the ultrapure water tank 5 from the side, but are not limited to this. For example, the primary pure water tank 2 and the ultrapure water tank It is also possible to connect to the bottom of the water tank 5.

In short, a nitrogen gas purging device 3 for injecting nitrogen gas into the primary pure water tank 2 and the ultrapure water tank 5, respectively.
6 and circulation paths 8, 9, 10 connected to the primary pure water tank 2 and the ultrapure water tank 5 through supply units 14, 18, 19 and discharge units 15, 20, respectively. Supply section 14,1 of roads 8,9,10
It suffices that 8 and 19 are connected below the liquid levels of the primary pure water tank 2 and the ultrapure water tank 5.

[0045]

As described above, according to the present invention, the supply portions of the circulation passages of the primary pure water tank and the ultrapure water tank are located above the water surface of the primary pure water tank and the ultrapure water tank as in the prior art. Since it is not separated and connected below the liquid level of the primary pure water tank and the ultrapure water tank, the purged nitrogen gas must be dissolved in the ultrapure water sprayed as before. Inadvertently dissolving the nitrogen gas in ultrapure water is prevented.

As a result, there is no possibility that bubbles are generated in the ultrapure water by the heat treatment, and therefore, the adhesion of the bubble particles to the impurities as in the prior art is prevented, which may adversely affect wafer cleaning and the like. Problems can be solved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an ultrapure water production apparatus according to one embodiment.

FIG. 2 is a schematic block diagram of a conventional ultrapure water production apparatus.

FIG. 3 is a schematic block diagram of a heating device of one test example.

FIG. 4 is a graph showing test results, in which (a) is a gas amount generated by heating pure water, and (b) is a graph of gas amount generated by heating ultrapure water.

[Explanation of symbols]

2 Primary water tank 3 Nitrogen gas purging device 5 Ultrapure water tank 6 Nitrogen gas purging device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-222769 (JP, A) JP-A-2-152589 (JP, A) JP-A-50-86162 (JP, A) JP-A-2- 222763 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C02F 1/00 C02F 1/20

Claims (1)

(57) [Claims] 1. A primary pure water tank (2) for storing primary pure water obtained by various deaeration means, and said primary pure water tank
An ultrapure water tank (5) for storing pure water supplied from (2) as ultrapure water, and a nitrogen gas for injecting nitrogen gas into the primary pure water tank (2) and the ultrapure water tank (5), respectively. Nitrogen gas purge device
(3), (6) and the primary pure water tank (2) and the primary pure water tank to circulate the pure water and ultrapure water of the ultrapure water tank (5), respectively.
(2) and the ultrapure water tank (5) in the ultrapure water production apparatus having a circulation path connected via a supply section and a discharge section,
The supply units of the circulation channels of the primary pure water tank (2) and the ultrapure water tank (5) are connected to the lower part of the liquid level of the primary pure water tank (2) and the ultrapure water tank (5). An apparatus for producing ultrapure water.