JP3285233B2 - Gas exchange device and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas exchanging apparatus and method, and more particularly to a gas exchanging method for exchanging inner and outer partitions of a container by exchanging gas in a container filled with toxic gas. An exchange device and method.

[0002]

2. Description of the Related Art In a gas laser device such as an excimer laser device, discharge is performed by a pair of discharge electrodes inside a pressure vessel called a laser chamber, and a laser medium gas in the laser chamber is excited to perform laser oscillation. Will be The laser chamber is provided with a window for extracting a laser beam, that is, a laser window. The laser window is contaminated by, for example, metal powder generated by electric discharge in the laser chamber, and the transmittance gradually decreases with the progress of the laser operation. For this reason, the output of the laser decreases as the operation time increases. Therefore, in order to obtain a stable laser output,
It is necessary to periodically remove the laser window from the laser chamber and clean and replace it. Incidentally, the laser medium gas used in the excimer laser device contains a toxic gas such as fluorine. For this reason, when performing the work of removing the laser window, measures must be taken to prevent the toxic gas from directly touching the worker.

Further, if outside air or the like enters the laser chamber when the laser window is removed,
Thereafter, when the laser is oscillated, for a while, the laser output is reduced due to air mixing, and the inconvenience of shortening the life of the laser medium gas is caused. Therefore, such a situation must be avoided.

Therefore, conventionally, when performing the work of attaching and detaching the laser window, the gas inside the laser window is replaced by an inert gas (generally helium gas) harmless to the human body before this work. In addition, in order to prevent outside air from entering the inside of the laser chamber, the pressure of the helium gas inside the laser chamber is set slightly higher than the surrounding atmospheric pressure. That is, a series of operations are performed in the following procedure.

[0005] 1) The gas inside the laser chamber, whose initial pressure is higher than the atmospheric pressure, is forcibly evacuated until it becomes 10 Torr or less.

[0006] 2) Helium gas is supplied into the laser chamber until the pressure reaches about 1.1 atm.

3) Detach the laser window from the laser chamber.

This operation will be described with reference to FIGS.

FIG. 7 shows a part of an excimer laser device.
1 shows a gas exchange device that supplies or exhausts gas to a laser chamber.

As shown in FIG. 1, the laser chamber 10 is provided with laser windows 11a and 11b from which laser light discharged and excited inside the chamber 10 is emitted. A pressure sensor 12 for detecting the pressure P of the gas is provided.

The gas supply passage 6 is provided in the laser chamber 10.
The passage 6 communicates the gas supply source with the inside of the laser chamber 10. The helium gas, which is a non-toxic gas, is supplied into the chamber 10 by opening the valve 1 disposed on the passage 6. When the valve 2 disposed on the branch passage of the passage 6 is opened, the laser medium gas is supplied into the chamber 10.

On the other hand, a gas exhaust passage 7 is connected to the laser chamber 10, and this passage 7 communicates the inside of the laser chamber 10 with a predetermined exhaust gas processing section. When the valve 3 provided on the passage 7 is opened, the gas in the chamber 10 is forcibly exhausted from the chamber 10 via the halogen filter 8 with the driving of the vacuum pump 9.

In such an apparatus, as shown in FIG. 8, first, the vacuum pump 9 is started (step 101), and the valve 3 is opened (step 102).
The laser medium gas in the laser chamber 10 is forcibly exhausted. During the evacuation, it is determined based on the output of the pressure sensor 12 whether the pressure P of the laser medium gas in the chamber 10 has become equal to or lower than the target pressure P0 (10 Torr) (step 103). As a result, the laser chamber 1
When it is determined that the pressure P inside the pressure 0 becomes lower than the target pressure P0 (determination YES in step 103), the valve 3 is closed (step 104), and the valve 1 is opened to supply helium which is a non-toxic gas. (Step 105).

While the valve 1 is open, it is determined based on the output of the pressure sensor 12 whether or not the gas pressure P inside the laser chamber 10 is higher than a target pressure P1 (1.1 atm). (Step 106). As a result, if it is determined that the pressure P inside the laser chamber 10 has become equal to or higher than the target pressure P1 (YES in step 106),
The valve 1 is closed (step 107) and the vacuum pump 9
Is stopped (step 108).

[0015]

During the maintenance work described above, the operation of the laser is stopped. However, in the case of industrial equipment, it is desirable from the viewpoint of work efficiency that such an operation stop time be as short as possible. Considering the time-consuming factor of the conventional method, it is found that the evacuation time until the pressure inside the laser chamber 10 is reduced to the low pressure of 10 Torr is extremely long. That is, as shown in FIG. 9, it takes a great amount of time ta to change the pressure P of the laser medium gas from the initial pressure to the target pressure P0 of 10 Torr.

Even if the toxic laser medium gas is diluted by supplying a non-toxic helium gas, the laser windows 11a and 11b are desorbed since the pressure P is finally 1.1 atm, which is slightly higher than the outside air. At this time, the toxic gas remaining in the chamber 10 is leaked to the outside though a small amount, which is not preferable for the safety of the worker.

Therefore, if the laser chamber 10 is further evacuated to a higher vacuum so that even such a small amount of toxic gas does not remain, the gas exchange operation becomes difficult.
a It takes more time and further impairs the work efficiency. Conversely, if the evacuation time is shortened, the concentration of the remaining toxic gas will increase, and the safety will be lacking.

Further, if the laser chamber is evacuated to a high vacuum, the problem of the gap between the members constituting the laser chamber, for example, the release of gas from the sealing material cannot be ignored, and the capacity of the vacuum pump 9 is insufficient. However, the use of a higher capacity vacuum pump may lead to a costly situation.

As described above, conventionally, it takes time and cost to increase the vacuum in the laser chamber, and there is a conflicting problem that the residual toxic gas comes into contact with the human body when replacing the laser window. Was.

The present invention has been made in view of such circumstances, and it is a first object of the present invention to perform a gas exchange in a short time so that the inner and outer partition walls can be exchanged in a short time, thereby improving the operation efficiency. It is a second object of the present invention to further improve safety by preventing toxic gas from touching the human body when replacing the inner and outer partition walls.

[0021]

Therefore, according to a first aspect of the present invention, a gas containing a toxic gas is forcibly evacuated from a container in which the gas is sealed, and the gas is forcibly evacuated from a container in which the gas is forcibly evacuated. After the concentration of the toxic gas in the container is reduced to a predetermined concentration or less by supplying a non-toxic gas to the container, the pressure in the container is greater than 10 Torr in a gas exchange device for exchanging the inner and outer partition walls of the container. Exhaust means for forcibly exhausting the gas in the container until the pressure reaches a pressure, supply means for supplying a non-toxic gas into the container until the pressure in the container becomes substantially equal to the outside pressure, and forcing the gas by the exhaust means Exhaust / supply control means for reducing the concentration of the toxic gas in the container to the predetermined concentration or less by repeating the exhaust and the supply of the non-toxic gas by the supply means a plurality of times. There.

Further, in the second invention of the present invention, in addition to an exhaust passage for forcibly exhausting the gas from the container, an outside air release exhaust passage opened to the outside air is provided in the container, and After supplying a non-toxic gas into the container until the pressure in the container becomes a predetermined pressure greater than the outside air pressure, open the outside air opening passage, and when the pressure in the container becomes the same pressure as the outside air pressure, The replacement work is being performed.

[0023]

According to the first aspect of the present invention, the gas in the container is forcibly exhausted until the pressure in the container reaches a predetermined pressure greater than 10 Torr, and the pressure in the container becomes substantially the same as the external pressure. The supply of the non-toxic gas into the container is repeated a plurality of times until the concentration of the toxic gas in the container becomes equal to or lower than the predetermined concentration.

In this regard, the conventional method described above requires one container.
By evacuating to a high vacuum each time, the concentration of the toxic gas remaining inside the container is reduced. However, in the present invention, the exhaust and the non-toxic gas supply are alternately repeated by a plurality of times even if the exhaust is set to a pressure higher than the conventional target pressure, instead of exhausting to a high vacuum all at once. As a result, the concentration of the toxic gas remaining inside the container is reduced in a short time.

Specifically, the container is now 10 Torr.
The concentration of the toxic gas remaining in the container when helium, which is a nontoxic gas, is supplied until the pressure becomes 1 atm.

Here, the same container is evacuated to 100 Torr, which is larger than 10 Torr, and then helium is reduced to 1 Torr.
When supplied to atmospheric pressure, the residual concentration of toxic gas is 10
become. When this operation is repeated once again, the residual concentration of the toxic gas becomes 1.316 (= 10 × 100/76).
0). When this operation is repeated once more, the residual concentration of the toxic gas becomes 0.173 (note that this is a sufficiently low theoretical degree of vacuum in the container, so that the theoretical calculation is sufficiently performed).
It can be seen that the residual concentration of the toxic gas is further reduced as compared with the case where the exhaust is performed up to 10 Torr at a time. Moreover, even if the exhaust and supply are repeated three times, the time required to exhaust the pressure to 100 Torr is sufficiently smaller than the time required to exhaust the pressure to 10 Torr.
The work is completed in a shorter time than once. Therefore, work efficiency is improved as compared with the conventional case.

According to the second aspect of the present invention, in addition to the exhaust passage for forcibly exhausting gas from the container, an outside air release exhaust passage opened to the outside air is provided in the container. And
Non-toxic gas is supplied into the container by the supply means until the pressure in the container reaches a predetermined pressure greater than the outside air pressure.
The outside air release passage is opened, and the pressure in the container is set to the same pressure as the outside air pressure. Then, when the pressure becomes the same, the work of replacing the inner and outer partitions is performed.

More specifically, a gas is put in the container at a pressure higher than the surrounding atmospheric pressure by, for example, about 0.1 atm, and is opened to the atmosphere through a filter or the like for about several seconds through an outside air opening passage. For this reason, since there is no pressure difference between the container and the surrounding atmosphere, when the inner and outer partition walls are removed, gas inside and outside of the container hardly enters and exits. If the inner and outer partitions are replaced in this state, the operation can be performed safely without the toxic gas remaining in the container coming into contact with the human body.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a gas exchange apparatus and method according to the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing the processing procedure of the embodiment. It is assumed that the same gas exchange device as that shown in FIG. 7 is used in the embodiment. Therefore, hereinafter, the same reference numerals as described above have the same configuration and will not be described.

In this embodiment, the operation of evacuating the laser medium gas in the laser chamber 10 to 100 Torr and then supplying helium until the pressure in the chamber 10 reaches 1 atm is repeated three times. I have to.

That is, first, the vacuum pump 9 is started (step 201), and i indicating the number of repetitions of gas exhaust and air supply is initialized to 0 (step 20).
2). Next, it is determined whether or not the number of repetitions i has reached a preset number of repetitions n (= 3) (step 2).
03). If it is determined that the set number n has not yet been reached (NO in step 203), the valve 3 is opened (step 204), and the laser medium gas in the laser chamber 10 is forcibly exhausted. Throughout the exhaust
Based on the output of the pressure sensor 12, it is determined whether or not the pressure P of the laser medium gas in the chamber 10 has become equal to or lower than the target pressure P2 (100 Torr) (step 20).
5). As a result, when it is determined that the pressure P inside the laser chamber 10 has become lower than the target pressure P2 (step 2).
05, YES), the valve 3 is closed (step 2).
06), Valve 1 to supply helium, a non-toxic gas
Is opened (step 207).

While the valve 1 is open, it is determined based on the output of the pressure sensor 12 whether or not the gas pressure P inside the laser chamber 10 is higher than a target pressure P3 (1.0 atm). (Step 208). As a result, when it is determined that the pressure P inside the laser chamber 10 has become equal to or higher than the target pressure P3 (determination YES in step 208),
Valve 1 is closed (step 209) and the number of repetitions i
Is incremented by +1 (step 210). If the number of repetitions i has not reached the set number n (NO in step 203), steps 204 to
Step 210 is repeatedly executed. Eventually, when such repetitive processing is executed three times (determination Y in step 203).
ES), the drive of the vacuum pump 9 is stopped (step 2)
11). Thereafter, replacement work of the laser windows 11a and 11b is performed.

FIG. 2 is a graph showing the change in the gas pressure P in the laser chamber 10 during the execution of the processing shown in FIG.
It is a graph shown according to.

Therefore, the inside of the laser chamber 10 is maintained at 10 Torr by the graph shown in FIG.
The graph is compared with the graph when exhaust is performed until. First,
As is evident from both graphs, it is understood that the exhaust time from the initial pressure to 1 atm does not change.

Also, theoretically, after the pressure reaches 1 atm, 1
The time required to evacuate to 00 Torr (P2) is one third of the time required to evacuate from 1 atm to 10 Torr (P0). The time required to supply the helium gas, which is an inert gas, is the same in both cases. Since the time required to supply the inert gas is sufficiently shorter than the time required to exhaust the gas, it can be ignored in the calculation. Therefore, in theory, the time required for gas exchange is almost the same for both.

In practice, however, as is apparent from both graphs, the conventional method required three times of repeating the operation of evacuating to 100 Torr and then supplying helium to 1 atm. It can be seen that the time is shorter than the time ta. And finally, the laser chamber 1
The concentration of the toxic gas remaining in 0 is lower when the process is repeated three times.

In this embodiment, when supplying the helium gas, the target pressure is set to the same pressure P3 (1 atm) for all three times, but the first two target pressures and the last one target pressure are set. May be different from the value.

In the above embodiment, after replacing the laser windows 11a and 11b, the laser medium gas is supplied into the laser chamber 10 via the valve 2, and the operation of the laser is newly restarted.

In this embodiment, the pressure sensor 1
When the pressure inside the laser chamber 10 becomes equal to the pressure of the outside air based on the output of the laser window 1, the laser window 1
The replacement work of 1a and 11b is performed. However, at this time, a small amount of air may enter the laser chamber 10 and cause a decrease in laser output. Therefore, an embodiment which can completely avoid such a situation will be described with reference to FIGS.

In the apparatus of this embodiment, as shown in FIG. 3, in addition to the gas exhaust passage 7, a gas exhaust passage 13 that bypasses the vacuum pump 9 is provided.
Is provided. The processing of this embodiment is basically the same as that shown in FIG. However, at the time of the third repetition processing, the processing shown in FIG. 4 is executed instead of steps 207 to 209 in FIG.

That is, the valve 1 is opened to supply helium which is a non-toxic gas (step 301). While the valve 1 is open, it is determined based on the output of the pressure sensor 12 whether or not the pressure P of the gas inside the laser chamber 10 is equal to or higher than the target pressure P4 (1.1 atm.). Step 302). As a result, the laser chamber 1
When it is determined that the internal pressure P of 0 is equal to or higher than the target pressure P4 (determination YES in step 302), the valve 1 is closed (step 303). Next, the valves 3 and 4 are opened, and the gas containing the toxic gas inside the laser chamber 10 is discharged to the outside via the filter 8 without passing through the vacuum pump 9. In this case, the vacuum pump 9
Is discharged without passing through, so that the laser chamber 1
The internal pressure of 0 becomes equal to the external atmospheric pressure through the passage 13 (step 304). Thus, the laser chamber 1
The determination that the internal pressure of 0 has become the same as the external atmospheric pressure is made based on the fact that a predetermined time t1 has been measured as a time since the valves 3 and 4 were opened by a predetermined timer (step 305).

Eventually, when the internal pressure of the laser chamber 10 becomes equal to the external atmospheric pressure, the valves 3 and 4
Are closed (step 306). Then, the number of repetitions i is incremented by +1 (step 210), and it is determined that the repetition process has been executed three times (determination YES in step 203), so that the driving of the vacuum pump 9 is stopped (step 211). After a while, the laser window 11
The replacement work of a and 11b is performed.

As described above, in this embodiment, when the inside of the laser chamber 10 is released to the atmosphere, the pressure inside the laser chamber 10 is surely equal to the outside pressure, and then the laser windows 11a and 11b are replaced. Since the work is performed, the work can be performed safely without touching the remaining toxic gas.

By the way, an apparatus using a toxic gas such as an excimer laser apparatus has a structure in which the air inside the laser apparatus is constantly exhausted to the outside, in case that the toxic gas leaks. There is something. In such an apparatus, the following implementation is also possible.

FIG. 5 shows the structure of an apparatus having such a structure. The entire laser apparatus is covered by a cover 15, and gas leaking in the apparatus is discharged through an exhaust port 15a open to the atmosphere. Discharged safely outside the room. The gas exhaust passage 1 other than the gas exhaust passage 7 is provided in the laser chamber 10.
4 is provided separately, and the valve 5 is disposed on the passage 14. When this valve 5 is opened, the passage 1
4. The gas inside the laser chamber 10 is exhausted outside through the exhaust port 15a.

FIG. 6 shows a process performed by the apparatus having such a configuration, and is basically the same as that shown in FIG. However, at the time of the third repetition processing, step 2 in FIG.
The processing shown in FIG. 6 is executed instead of 07 to 209.

That is, the valve 1 is opened to supply helium which is a non-toxic gas (step 401). While the valve 1 is open, it is determined based on the output of the pressure sensor 12 whether or not the pressure P of the gas inside the laser chamber 10 is equal to or higher than the target pressure P5 (1.1 atm). Step 402). As a result, the laser chamber 1
When it is determined that the internal pressure P of 0 is equal to or higher than the target pressure P5 (YES in step 402), the valve 1 is closed (step 403). Then, the valve 5 is opened, and the gas containing the toxic gas inside the laser chamber 10 is exhausted outside through the passage 14 and the exhaust port 15a. In this case, since the exhaust port 15a is open to the atmosphere, the internal pressure of the laser chamber 10 eventually becomes equal to the external atmospheric pressure (step 404). Thus, the fact that the internal pressure of the laser chamber 10 has become equal to the external atmospheric pressure is determined by the fact that a predetermined time t2 has been measured as the time from when the valve 5 was opened by the predetermined timer (step). 405).

Eventually, when the internal pressure of the laser chamber 10 becomes equal to the external atmospheric pressure, the valve 5 is closed (step 406). Then, the number of repetitions i is incremented by +1 (step 210), and
Since it is determined that the execution has been performed (YES in step 203), the driving of the vacuum pump 9 is stopped (step 211). Thereafter, replacement work of the laser windows 11a and 11b is performed. As described above, also in this embodiment, the laser windows 11a and 11b are replaced after the inside of the laser chamber 10 is released to the atmosphere, so that the pressure inside the laser chamber 10 becomes equal to the outside air pressure. As a result, the operation can be performed safely without touching the remaining toxic gas.

In the embodiment shown in FIGS. 4 and 6,
After the evacuation valve 5 and the like are opened, it is determined that the pressure inside the chamber 10 matches the outside air pressure when a predetermined time has elapsed. When the amount of change in pressure per unit time becomes smaller than a predetermined value, the inside of the laser chamber 10 may be regarded as being balanced with the external pressure, and the exhaust valve 5 and the like may be closed.

By the way, in each of the above-mentioned embodiments, after the pressure inside the laser chamber 10 becomes about 1 atm.
Although the replacement work of the laser windows 11a and 11b is performed, it is also possible to perform the replacement work at a pressure slightly higher than 1 atm, for example, about 1.1 atm. In this case, open the exhaust valve,
Until the pressure inside the laser chamber 10 reaches the same pressure as that outside the container, there is a concern that the gas flowing out of the laser chamber 10 may touch an operator.

However, the concentration of the toxic gas in the laser chamber 10 has been sufficiently reduced at the time of being replaced with the helium gas.

By properly setting the position of the exhaust pipe, the gas flowing out of the laser chamber 10 can be surely captured by the exhaust pipe.

Therefore, it can be said that there are few safety problems in practice.

Although the embodiments have been described on the assumption that the present invention is applied to an excimer laser apparatus, the gas exchange apparatus and method according to the present invention are not limited to this, and a container containing a toxic gas may be used. The present invention can be applied to any device that requires replacement of the inner and outer partitions.

[0056]

As described above, according to the present invention,
Since the gas exchange until the concentration of the toxic gas becomes equal to or lower than the predetermined concentration is completed in a short time, and the replacement operation of the inner and outer partition walls can be performed in a short time, the work efficiency is dramatically improved. In addition, when the inner and outer bulkheads are removed, the ingress and egress of gas inside and outside of the container is minimized, so that toxic gas does not touch the human body when replacing the inner and outer bulkheads, and safety is reduced. Is dramatically improved.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a gas exchange apparatus and method according to the present invention.

FIG. 2 is a graph showing a result of the embodiment shown in FIG. 1, and is a graph showing a time change of a gas pressure in a laser chamber.

FIG. 3 is a diagram showing a configuration of an apparatus used in another embodiment.

FIG. 4 is a flowchart illustrating a procedure of a process performed using the apparatus illustrated in FIG. 3;

FIG. 5 is a diagram showing a configuration of an apparatus used in still another embodiment.

FIG. 6 is a flowchart illustrating a procedure of processing performed using the apparatus illustrated in FIG. 5;

FIG. 7 is a diagram showing a configuration of a conventional apparatus or an apparatus used in the embodiment shown in FIG. 1 of the present invention.

FIG. 8 is a flowchart showing a procedure of processing performed by a conventional device.

FIG. 9 is a graph showing a result of the processing of FIG. 8;
4 is a graph showing a change over time of a gas pressure in a laser chamber.

[Explanation of symbols]

 Reference Signs List 1 valve 3 valve 6 gas supply passage 7 gas exhaust passage 10 laser chamber 11a laser window 11b laser window

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01S 3/03-3/038

Claims (4)

(57) [Claims] 1. A method according to claim 1, further comprising: forcibly exhausting the gas from a container in which the gas containing the toxic gas is sealed, and supplying a non-toxic gas into the container in which the gas is forcibly exhausted. In a gas exchange device for replacing the inner and outer partition walls of the container after the concentration is reduced to a predetermined concentration or less, exhaust means for forcibly exhausting the gas in the container until the pressure in the container reaches a predetermined pressure greater than 10 Torr. Supplying means for supplying a non-toxic gas into the container until the pressure in the container becomes substantially the same as the external pressure; and repeatedly performing the forced exhaustion of the gas by the exhaust means and the supply of the non-toxic gas by the supply means a plurality of times. A gas exchange device comprising exhaust / supply control means for controlling the concentration of the toxic gas in the container to be equal to or lower than the predetermined concentration. 2. An outside air release exhaust passage open to the outside air is provided in the container in addition to an exhaust passage for forcibly exhausting the gas from the container, and the pressure in the container is reduced by an external pressure by the supply means. After supplying a non-toxic gas into the container until the pressure becomes large, the outside air opening passage is opened,
2. The gas exchange apparatus according to claim 1, wherein the replacement operation is performed when the pressure in the container reaches the same pressure as the outside air pressure. 3. The container is a laser chamber of a gas laser device, the inner and outer partitions are laser windows, the toxic gas is a fluorine gas as a laser medium gas, and the non-toxic gas is a helium gas. The gas exchange device according to claim 1. 4. A toxic gas in the container is discharged by forcibly exhausting the gas from a container in which the gas containing the toxic gas is sealed and supplying a non-toxic gas into the container in which the gas is forcibly exhausted. After the concentration is reduced to a predetermined concentration or less, in a gas exchange method of replacing the inner and outer partition walls of the container, an exhausting process of forcibly exhausting gas in the container until the pressure in the container becomes a predetermined pressure greater than 10 Torr. A supply step of supplying a non-toxic gas into the container until the pressure in the container becomes substantially the same as the external pressure, wherein a plurality of forcible exhaustion of gas in the exhaust step and a supply of non-toxic gas in the supply step are provided. A gas exchange method in which the concentration of the toxic gas in the container is reduced to the predetermined concentration or less by repeatedly performing the method.