JPH0812852B2 - Sterilization cleaning method of pure water circulation path for cleaning in semiconductor manufacturing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is intended to circulate pure water for cleaning a wafer or the like between a pure water tank and a cleaning portion for the wafer or the like when manufacturing a semiconductor. The present invention relates to a method for sterilizing and cleaning bacteria that propagate in the circulation path of pure water for cleaning in the circulation path of pure water for cleaning.

[Conventional technology]

Generally, in the manufacture of semiconductors, the wafers and the like are washed with pure water. This pure water for cleaning is circulated between a pure water tank storing pure water and a cleaning place. Is composed of.

That is, the pure water produced by the pure water producing device is stored in a pure water tank, and the pure water in the pure water tank is sent to an ultraviolet sterilizer, an ion exchange device, and a final filter by a circulation pump. It is made into pure water, and this ultrapure water is sent to a cleaning portion in a clean room, and then, from this cleaning portion to a pure water tank via a return pipe, the circulation path is constituted.

In this case, since bacteria propagate in the circulation path of the pure water for cleaning, the circulation path of the pure water for cleaning needs to be regularly sterilized and washed.

Therefore, conventionally, when sterilizing and cleaning the circulation path of the pure water for cleaning, hydrogen peroxide is injected into the pure water tank so that the concentration of hydrogen peroxide in the pure water is 2 to 3%. The pure water containing hydrogen peroxide is circulated in the circulation path for an appropriate period of time, then left for a suitable period of time with the circulation stopped, and then the circulation is restarted to newly store in the pure water tank. While supplying the pure water of, from the drain pipe branching from the return pipe to the pure water tank,
By sterilizing the inside of the circulation path of the pure water for cleaning by continuing to discharge the cleaned waste water containing hydrogen peroxide until the cleaned waste water in the circulation path completely replaces the new pure water. I am trying.

[Problems to be Solved by the Invention]

However, in this sterilization cleaning with hydrogen peroxide, in order to almost completely sterilize the circulation path of the pure water for cleaning, in addition to circulating pure water containing hydrogen peroxide for about 2 hours, It is necessary to stop the circulation thereafter and leave it for about 1 hour.

Moreover, after that, the circulation is restarted and new pure water is supplied to the pure water tank, while the drainage pipe branching from the return pipe to the pure water tank is used to wash the wastewater containing hydrogen peroxide. When discharging, in the pure water tank,
It takes as long as 15 to 18 hours for all of the cleaned wastewater containing hydrogen peroxide in the ultraviolet sterilizer, the final filter and the return line to be completely replaced with new pure water.

Therefore, in the conventional sterilization cleaning method using hydrogen peroxide, the sterilization cleaning takes an extremely long time.
Not only is it extremely inefficient, but since a large amount of washed wastewater containing hydrogen peroxide is discharged during this sterilization cleaning, a large amount of equipment is required to purify this washed wastewater containing hydrogen peroxide. There was the problem of needing expense.

It is an object of the present invention to provide a sterilization cleaning method capable of significantly reducing the time required for sterilization cleaning of a circulation path and significantly reducing the amount of cleaned drainage.

[Means for solving the problem]

The present inventor completes the present invention by paying attention to the fact that ozone is extremely effective for sterilizing bacteria and that ozone has a property of decomposing and disappearing into the atmosphere very easily. Came to.

That is, in order to achieve the above-mentioned object, the present invention is to provide the pure water tank between the pure water tank containing pure water for cleaning the wafer and the cleaning portion for cleaning the wafer. In the pure water circulation path for cleaning, which forms a circulation path in which pure water inside returns to the pure water tank through the ion exchange device and the cleaning location, ozone is injected into the pure water tank and the ozone is removed. The pure water contained is circulated for an appropriate time so as to bypass the ion exchange device in the circulation path, and is then discharged from the circulation path. ”

[Action]

The present invention uses ozone for sterilization cleaning in a circulation path of pure water for cleaning, and this ozone has a sterilizing power 10 times or more as compared with hydrogen peroxide which has been conventionally used. Therefore, by circulating this pure water containing ozone for an appropriate time (about 1 to 2 hours), the circulation path can be almost completely sterilized and washed.

Further, since ozone is naturally decomposed into oxygen, it is circulated for the appropriate time and then discharged from the circulation path so that the ozone remaining in the circulation path is pure water as in the conventional case. While supplying new pure water into the tank, the washed waste water is promptly eliminated without being discharged from the drain pipe branching from the return pipe to the pure water tank.

At the time of sterilizing and cleaning the circulation path with pure water containing ozone, the pure water containing ozone is circulated by bypassing the ion exchange apparatus in the circulation path, so that the ion exchange resin in the ion exchange apparatus can be used. ,
It is possible to avoid adverse effects such as deterioration due to ozone.

〔The invention's effect〕

Therefore, according to the present invention, when sterilizing and cleaning the circulation path, it is possible to avoid adversely affecting the ion exchange device in the circulation path, while comparing the time required for the sterilization cleaning in the circulation path with the conventional one. Therefore, the workability of sterilization cleaning can be greatly improved, and the amount of washed drainage discharged during the sterilization cleaning is sufficient to circulate in the circulation path. Since the amount of waste water becomes so small that it is not comparable to the conventional case, it has the effect of significantly reducing the equipment and cost for purification treatment of washed waste water.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings (FIG. 1).

In the figure, reference numeral 1 denotes a pure water tank for storing pure water manufactured by the pure water manufacturing apparatus 2, and the pure water tank 1
The pure water in the inside is pumped out by a circulation pump 4 through a pipe line 3, guided to an ultraviolet sterilization device 6 through a pipe line 5, and from this ultraviolet sterilization device 6 through a pipe line 7 an ion exchange device 8
To the final filter 10 from the ion exchange device 8 via the pipe line 9, and then from the final filter 10 via the pipe line 11 to the cleaning location 12 for the wafer having a plurality of faucets 12a. The place 12 is provided in a clean room), and then the circulating place is such that it returns from the washing place 12 to the pure water tank 1 via the return pipe 13.

The ion exchange device 8 is provided with an inlet valve 8a to the ion exchange device 8 and an outlet valve 8b from the ion exchange device 8 and is provided with a valve 8d that bypasses the ion exchange device 8. A bypass line 8c is provided.

In addition, the return line 13 to the pure water tank 1 has an open / close valve.
14 is provided and is connected to a drainage line 15 for the washed drainage, which is provided with a valve 16.

Furthermore, a gas-liquid separation chamber 17 is inserted into the highest part of the return pipe 13 to the pure water tank 1, and valves 18 and 19 are provided at the inlet and outlet of the gas-liquid separation chamber 17, respectively. On the other hand, the return conduit 13 is provided with a bypass conduit 20 with a valve 21 that bypasses the gas-liquid separation chamber 17.

Then, as shown in FIG. 2, a diffused gas 22 formed by forming a plurality of diffused nozzles 23 at the bottom of the pure water tank 1.
Is provided, and ozone generated by the ozone generator 24 is introduced into the diffused gas 22 through a pipe line 25 having a valve 26.

In this configuration, normally, the inlet valve 8a and the outlet valve 8b in the ion exchange device 8 are opened, and the bypass line
The valve 8d in 8c is closed, while the valves 18 and 19 at the inlet and outlet of the gas-liquid separation chamber 17 are closed, and the bypass line 20 thereof is closed.
The circulation pump 4 is driven with the inside valve 21 opened, the opening / closing valve 14 in the return line 13 opened, and the valve 16 in the drainage line 15 closed.

Then, the pure water in the pure water tank 1 is sent to the cleaning location 12 in the clean room through the ultraviolet sterilizer 6, the ion exchange apparatus 8 and the final filter 10 by the circulation pump 4, and then this cleaning location 12 It is circulated so as to return to the pure water tank again via the return pipe line 13.

During the sterilization cleaning, the supply of pure water from the pure water producing device 2 to the pure water tank 1 is stopped, and the pure water in the pure water tank 1 is dispersed with ozone generated by the ozone generator 24. The gas 22 is blown from a plurality of nozzles 23 so that the concentration of ozone in the pure water is 0.05 to 0.2 ppm.

Then, the inlet valve 8a and the outlet valve 8b in the ion exchange device 8 are closed, and the valve 8d in the bypass pipe line 8c thereof is opened, while the valve 1 at the inlet and the outlet of the gas-liquid separation chamber 17 is closed.
The circulation pump 4 is driven with the valves 8 and 19 opened and the valve 21 in the bypass line 20 closed.

Then, the pure water containing ozone in the pure water tank 1 passes through the ultraviolet sterilizer 6 by the circulation pump 4, then bypasses the ion exchange device 8, and then passes through the final filter 10 to the cleaning location 12 in the clean room. To the return line from this cleaning point 12.
Since it is circulated so as to return to the pure water tank 1 again via 13, the pure water containing ozone is passed through the ion exchange device 8 in the circulation path from the pure water tank 1 to the pure water tank 1 again. While it can be sterilized and washed without flowing into, the ozone in the pure water is partly separated from the pure water in the gas-liquid separation chamber 17.

When the sterilization cleaning is completed as described above, the on-off valve 14 in the return line 13 is closed and the drainage line 15 is closed.
By opening the inner valve 16, the washed wastewater is discharged from the drainage pipe 15 and the like, and ozone in the pure water is spontaneously decomposed into oxygen and disappears.

In this case, according to the experiment of the present inventor, by setting the ozone concentration in pure water to 0.05 to 0.2 ppm, it was possible to completely sterilize and wash by circulation for about 1 to 2 hours, and used for sterilizing and washing. Ozone completely disappears in about 10 minutes, and on the other hand, ozone was safe with almost no danger to the human body.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a view showing a circulation path of pure water for cleaning, and FIG. 2 is a perspective view of ozone diffused gas. 1 ... Pure water tank, 2 ... Pure water production device, 4 ... Circulation pump, 6 ... UV sterilizer, 8 ... Ion exchange device,
10 …… Final filter, 12 …… Wafer cleaning part, 13 …… Return pipeline, 14 …… Open / close valve, 15 …… Drainage pipeline, 22 …… Ozone diffuser, 24 …… Ozone generator .

Claims (1)

[Claims] 1. Pure water in the pure water tank is between the pure water tank containing pure water for cleaning wafers and the like and a cleaning place for cleaning the wafers, etc. In a pure water circulation path for cleaning, which forms a circulation path that returns to the pure water tank via a portion, ozone is injected into the pure water tank, and pure water containing this ozone is circulated for an appropriate time. A method for sterilizing and cleaning a pure water circulation path for cleaning in semiconductor manufacturing, which comprises circulating so as to bypass the ion exchange device in the path and then discharging from the circulation path.