Gas purification device and gas purification method

Abstract

To provide a gas purification device capable of purifying laser gas used in a laser light generating device with good controllability.SOLUTION: A gas purification device purifies gas recovered from a laser light generating device that uses laser gas and supplies it to the laser light generating device, and is equipped with a flow control device that controls the flow rate of the recovered gas, a constant volume supply device that is provided downstream of the flow control device and supplies an additive gas, and a purifier that is provided downstream of the constant volume supply device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas purification device and a gas purification method for a laser device. [Background technology]

[0002] Laser light generating devices such as excimer laser devices are used in lithography processes in the manufacture of semiconductor devices. When an excimer laser device is used repeatedly, impurities (e.g., fluorocarbides) are generated in the laser gas in the laser chamber, making it impossible to obtain the desired laser light output. In such cases, the laser gas needs to be replaced, but since the laser gas contains expensive gases, devices that purify and reuse the laser gas are known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-54851 [Patent Document 2] WO2015 / 076415 Summary of the Invention [Problem to be solved by the invention]

[0004] Laser gas contains a component (e.g. xenon) in a very small concentration of a few ppm in order to stabilize the discharge. The concentration of this component may fall below a prescribed concentration range and need to be added (replenished), but it is difficult to control such a small concentration.

[0005] In view of the above problems, an object of the present invention is to provide a gas purification device capable of purifying laser gas used in a laser light generating device with good controllability. [Means for solving the problem]

[0006] The gas purification device according to the present invention comprises: A gas purification device that purifies a gas recovered from a laser light generating device that uses a laser gas, and supplies the gas to the laser light generating device, a flow rate control device for controlling the flow rate of the collected gas; a constant volume supply device provided downstream of the flow rate control device and supplying an additive gas; and a refiner provided downstream of the constant volume supply device.

[0007] By configuring the gas purification apparatus in this way, it is possible to provide a gas purification apparatus that performs purification with good controllability.

[0008] In the gas purification apparatus according to the present invention having the above-mentioned configuration, the constant volume supply device may supply the additive gas discretely.

[0009] By using a gas purification device having such a configuration, the amount of additive gas to be added can be controlled by the number of times the additive gas is ejected.

[0010] Further, the gas purification apparatus according to the present invention has the above-mentioned configuration, The constant volume supply device has a constant volume section, a first valve, and a second valve, The first valve and the second valve may be located at opposite ends of the constant volume portion.

[0011] By using a constant volume supply device having such a configuration, the amount of additive gas can be accurately determined by the volume of the constant volume portion which is geometrically determined.

[0012] Further, the gas purification apparatus according to the present invention has the above-mentioned configuration, a first storage tank provided upstream of the flow control device; a second storage tank disposed downstream of the purifier; The first storage tank and the second storage tank may be connected in a communicable or disconnectable manner.

[0013] By using a gas purification apparatus having such a configuration, it becomes possible to purify the recovered gas again, and it is possible to further improve the quality assurance of the recovered gas.

[0014] Further, the gas purification apparatus according to the present invention has the above-mentioned configuration, Equipped with a gas analyzer, The gas analyzer may perform a compositional analysis of the gas in the first storage tank.

[0015] By using a gas purification device having such a configuration, it is possible to control the quality of the recovered gas.

[0016] Further, the method for purifying laser gas according to the present invention comprises the steps of: A recovery step of recovering laser gas from the laser light generating device; a recovered gas analysis step of analyzing the recovered gas and determining whether or not an additive gas needs to be added; an addition step of adding the additive gas by a constant volume supply device when it is determined in the collected gas analysis step that the addition of the additive gas is necessary; a purification step of purifying the recovered gas; a purified gas analysis step of performing a component analysis of the recovered gas purified by the purification step to determine whether or not repurification is required; a re-purification step of performing the purification step when it is determined in the purified gas analysis step that re-purification is necessary; The present invention is characterized by comprising:

[0017] By using a gas purification method having such a configuration, it is possible to accurately control the components of the recovered gas and improve quality control and assurance. Effect of the Invention

[0018] According to the present invention, it is possible to provide a gas purification device capable of purifying laser gas used in a laser light generating device with good controllability. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 shows a schematic of the main components of a gas purification apparatus 100 . [Diagram 2] Figure 2 shows the purification flow of gas recovered from the laser chamber. [Diagram 3] FIG. 3 is a cross-sectional view showing the main configuration of the gas supply control device 15, where FIG. 3(A) shows the connection relationship of the gas supply control device 15 in the gas purification device 100, and FIGS. 3(B), (C), and (D) are cross-sectional views showing the operation of the gas supply control device 15. [Figure 4] 4A and 4B show non-limiting examples of configurations of the purifier 16, where FIG. 4(A) shows an example of a configuration having a first purifier 16a, a second purifier 16b, and a third purifier 16c, and FIG. 4(B) shows an example of a configuration having a first purifier 16a, a second purifier 16b, a third purifier 16c, and a fourth purifier 16d. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the embodiments of the present invention will be described with reference to the drawings. However, the following embodiments are not intended to limit the scope of the present invention. In addition, the same reference numerals are used for the same or similar components, and the description thereof may be omitted.

[0021] Furthermore, terms used in this specification that specify shapes and geometric conditions as well as their degrees, such as "parallel," "orthogonal," "same," "vertical," and "horizontal," as well as values ​​of length and angle (direction), are to be interpreted without being bound by their strict meanings, but including the range within which similar functions can be expected.

[0022] (Embodiment 1) Hereinafter, an embodiment of the gas purification device 100 will be described with reference to the drawings. Fig. 1 shows a schematic diagram of the main components of a gas purification apparatus 100. As shown in Fig. 1, the gas purification apparatus 100 is connected to a laser chamber of an excimer laser light generator 1 by a pipe 10 (recovery pipe) and a pipe 20 (supply pipe). The pipes 10 and 20 are connected by a pipe 30 (main pipe). The number of excimer laser light generators 1 connected to one gas refinement apparatus 100 is not necessarily limited to one, and a plurality of excimer laser light generators 1 may be connected to one gas refinement apparatus.

[0023] The gas purification device 100 includes, in order from the piping 10 side, a first tank 2, a first pump 3, a second tank 4, a second pump 5, a third tank 6, a fourth tank 7, a third pump 8, and a fifth tank 9. A purifier 16 (impurity removal device) is provided between the third tank 6 and the fourth tank 7. The purifier 16 removes impurities (e.g., CF4, oxygen, water, etc.) contained in the laser gas. These components are connected by piping 30.

[0024] The first tank 2 is in communication with the laser chamber via a pipe 10 , and the fifth tank 9 is in communication with the laser chamber via a pipe 20 . The laser gas used to generate the laser beam is collected from the laser chamber of the laser beam generator 1 to the gas refinement device 100 via the pipe 10, and after purification processing, is returned from the gas refinement device 100 to the laser chamber via the pipe 20. Hereinafter, the pipe 10 side may be referred to as the upstream side, and the pipe 20 side as the downstream side.

[0025] The laser light generating device 1 can be a known device, and is equipped with a laser chamber filled with laser gas. As the laser gas, a known laser gas is used, and as a non-limiting example, a mixed gas of neon (Ne), halogen gas (F2, etc.), and other rare gases (xenon (Xe), krypton (Kr), argon (Ar), etc.) is used, and the filling pressure is usually about 200 to 600 kPa. A known ratio can be used as the component ratio (mixing ratio) of the laser gas.

[0026] The gas purification apparatus 100 includes a control device 12, which controls the opening and closing of each valve provided in the piping, and can also control the operation and stopping of the first pump 3, the second pump 5, and the third pump 8 based on a predetermined pressure. Note that the first, second, and third pumps may be configured to operate autonomously while detecting the pressure, without relying on the control device 12, or may be configured to operate autonomously and be controlled by the control device 12 at the same time. Each tank may have a pressure gauge, and each pressure gauge may measure the pressure of the gas in the tank. The control device 12 inputs the values ​​of each pressure gauge and can monitor the pressure of the gas in each tank. Moreover, the measurement results of the gas analyzer 11 provided in the gas purification device 100 are input to the control device 12 .

[0027] The following is a detailed explanation of the laser gas purification operation by the gas purification device 100. Figure 2 shows the purification flow of the gas recovered from the laser chamber.

[0028] When the control device 12 receives a request to purify the gas discharged from the laser light generating device 1, it executes the purification flow described below. The control device 12 is capable of communicating with each valve and each pump via wireless or wired communication means, and in each step, the opening / closing control of each valve and the driving / stopping control of each pump are executed by the control device 12. In the following description, valves that are not specifically mentioned are in a closed state.

[0029] Step 1 (Gas recovery step) Valves V1 and V2 located upstream and downstream of the first tank 2, and valve V3 located downstream of the first pump 3 are opened, and gas (hereinafter referred to as recovered gas) recovered from the laser light generating device 1 (laser chamber) is introduced into the first tank 2 (recovery tank) via piping 10 (recovery piping), and is pumped by the first pump 3 to the second tank 4 (first storage tank). When the recovered gas stored in the second tank 4 reaches a predetermined pressure (storage pressure), for example, but not limited to, 100 kPa or more and 400 kPa or less, the valve V3 is closed, the first pump 3 is stopped, and the process proceeds to step 2.

[0030] Step 2 (Gas pressure increase step) With valve V3 closed and valves V4 and V5 upstream and downstream of the second pump 5 open, the recovered gas in the second tank 4 is pumped by the second pump 5 to a third tank 6 (pressurization tank) and pressurized in the third tank 6. The third tank 6 is provided with a pressure gauge G6, which measures the gas pressure inside the third tank 6. The control device 12 acquires a measurement value P6 of the pressure gauge G6, and when it determines that the pressure P6 reaches a predetermined threshold value Pt1 (for example, 600 kPa to 900 kPa) (P6≧Pt1), it closes the valve V5, stops the second pump 5, and proceeds to step 3. If the increase in pressure of the third tank 6 is saturated and does not reach the predetermined threshold, the process returns to step 1. The control device 12 repeats steps 1 and 2 until the pressure of the third tank 6 reaches the predetermined threshold. In addition, a pump capable of being driven in a wide range (wide pressure range) may be used as the second pump 5, making the first tank 2, the first pump 3, the valves V1 and V2 unnecessary. In this case, a step (gas recovery and pressure increase step) in which step 1 and step 2 are combined is executed. Specifically, the valves V3, V4, and V5 may be opened and the valve V6 may be closed, and the recovered gas may be pumped to the third tank 6 by the second pump 5. When the control device 12 determines that the measured gas pressure P6 in the third tank 6 has reached the threshold value Pt1 (P6 or more Pt), it closes the valves V3 and V4, stops the second pump 5, and proceeds to step 3.

[0031] Step 3 (recovered gas analysis step) The valve V5 and the valve V6 downstream of the third tank 6 are closed, and the valve VA1 provided in the pipe A1 connecting the third tank 6 and the gas analyzer 11 is opened, and the gas analyzer 11 measures the concentration of the components of the recovered gas in the third tank 6. The output of the gas analyzer 11 is output to the control device 12. For example, a mass spectrometer can be used as the gas analyzer 11. For each measured component, the control device 12 determines whether the concentration of the component that makes up the laser gas (e.g., neon, krypton, xenon, argon, etc.) is within a predetermined concentration range and determines whether or not an additive gas needs to be added. The control device 12 determines that addition (replenishment) is necessary for components whose concentrations are lower than a predetermined concentration range, calculates the amount of additive gas to be added (doping amount) so that the component falls within the predetermined concentration range, and proceeds to step 4. For example, the gas analyzer 11 measures the xenon concentration in the collected gas, and if it is determined that the xenon concentration is lower than a predetermined concentration, the control device 12 determines that it is necessary to add (replenish) xenon and calculates the amount of xenon to be added (doped) to the collected gas so that the xenon concentration falls within a predetermined concentration range. Then, the process proceeds to step 4. If it is determined that the addition of all of the components is unnecessary, proceed to step 5.

[0032] Step 4 (additive process) With the valve V5 and the valve V8 downstream of the fourth tank 7 (second storage tank) in a closed state, and the valve V6 and the valve V7 upstream of the fourth tank 7 in an open state to communicate between the third tank 6 and the fourth tank 7, the recovered gas stored in the third tank 6 is allowed to flow into the downstream pipe 30. The recovered gas is adjusted to a predetermined pressure (PG1) by the pressure regulator RG1, and the flow rate is controlled by a flow control device (mass flow controller) MFC provided downstream of the pressure regulator RG1.

[0033] The gas cylinder 14 filled with the additive gas is connected to a pipe 31 (additive pipe), and the pipe 31 is connected to a pipe 30 downstream of the flow control device MFC. The piping 31 is provided with a pressure regulator RG2 (RG2a, RG2b) and a gas supply control device 15 (constant-volume supply device) described later, and the additive gas in the gas cylinder 14 is adjusted to a predetermined pressure (PG2) by the pressure regulator RG2 and flows into the gas supply control device 15. Based on the calculated amount of addition, the control device 12 controls the gas supply control device 15 to cause the additive gas (e.g., xenon, argon, etc.) to flow from the gas cylinder 14 to the pipe 31. At the connection point between the pipe 31 and the pipe 30, the collected gas and the additive gas join together. In addition, in order to add a component with a minute concentration, for example, xenon, xenon gas diluted with neon (mixed gas of neon and xenon) may be used.

[0034] In addition, when supplying a plurality of types of additive gases, for example, two types of additive gases, the gas cylinder 14 may have a first gas cylinder 14a and a second gas cylinder 14b, and pipes 31a and 31b may be connected to the first gas cylinder 14a and the second gas cylinder 14b, respectively, and pressure regulators RG2a and RG2b and gas supply control devices 15a and 15b may be provided on the pipes 31a and 31b, respectively, to control the amount of each additive gas added. FIG. 1 shows an example having a first gas cylinder 14a and a second gas cylinder 14b.

[0035] As described later, the gas supply control device 15 is a constant volume supply device that causes a predetermined volume of additive gas to flow through the pipe 31 to the pipe 30 by one jetting operation, and controls the volume of the required amount of additive gas by performing the jetting operation a predetermined number of times. That is, the gas supply control device 15 discretely supplies a predetermined volume of gas.

[0036] Since the volume of the collected gas flowing through the pipe 30 per unit time is determined by the flow rate control device MFC, the control device 12 can calculate the amount of added gas (replenishment amount) per unit time and calculate the number of jets per unit time. Therefore, the necessary amount of added gas can be added to the collected gas.

[0037] The pipe 30 may have a mixer 13 downstream of the communicating portion with the pipe 31. In the mixer 13, the uniformity of the mixture of the additive gas and the recovered gas is improved.

[0038] The mixed gas to which the additive gas has been added is subjected to a purification process in step 5. Since the flowing recovered gas is successively subjected to the processes of steps 4 and 5, the gas purification apparatus 100 proceeds with steps 4 and 5 simultaneously.

[0039] Also, preferably, the temperature may be kept constant by covering the entire system with a housing 40. In particular, by maintaining the same temperature for the flow rate control device MFC and the gas supply control device 15, more stable control of the addition amount becomes possible.

[0040] Step 5 (purification step) Valves V6 and V7 are opened, and the mixed gas of the recovered gas and the added gas is introduced to the purifier 16 through the pipe 30, where it is purified. If it is determined in step 3 that the additive gas is not necessary, the recovered gas is purified by the purifier 16 instead of the mixed gas. Hereinafter, the term "mixed gas" refers to "recovered gas" when it is determined in step 3 that no additional gas is required.

[0041] It should be noted that the purifier 16 may include multiple purifiers, as shown in, but not limited to, FIG. 4A and 4B show non-limiting examples of configurations of the purifier 16, where FIG. 4(A) shows an example of a configuration having a first purifier 16a, a second purifier 16b, and a third purifier 16c, and FIG. 4(B) shows an example of a configuration having a first purifier 16a, a second purifier 16b, a third purifier 16c, and a fourth purifier 16d. For example, in the example shown in Fig. 4(A), the first purifier 16a is a purifier that removes fluorocarbons (CF4, etc.), the second purifier 16b is a purifier that removes water, and the third purifier 16c is a purifier that removes oxygen, and in the example shown in Fig. 4(B), a fourth purifier 16d is further provided as a purifier (getter) that removes impurities that could not be completely removed. Depending on the application of the laser gas used, for example, for KrF laser or ArF laser, the configuration of Fig. 4(A) or Fig. 4(B) can be selected. Each purifier is a known purifier and can be operated under known conditions. The configuration of the purifier 16 is not limited to that described above, and any purifier necessary for maintaining the quality of the laser gas can be used.

[0042] The mixed gas purified by the purifier 16 is accumulated in the fourth tank 7, and the pressure in the fourth tank 7 rises. Meanwhile, the pressure P6 of the gas in the third tank 6 decreases, and when it becomes equal to or lower than a predetermined threshold value Pt2 (e.g., a value 100 kPa to 200 kPa lower than Pt1) (P6≦Pt2), the valves V6 and V7 are closed, the purification step ends, and the process proceeds to step 6.

[0043] In addition, since the purifier 16 generally employs a catalyst or adsorbent that comes into contact with the gas in order to remove impurities from the gas, the mixed gas passes through the purifier 16, thereby further improving the uniformity of the mixture of the recovered gas and the added gas. In addition, since the mixed gas is accumulated in the fourth tank 7, the uniformity of the mixture of the recovered gas and the added gas within the fourth tank 7 is further improved. As described above, the gas supply control device 15 supplies the additive gas discretely, but the purifier 16 and the fourth tank 7 have the effect of further improving the uniformity of the mixture.

[0044] Step 6 (Purified gas analysis step) With valves V7 and V8 closed, valve VA2 of pipe A2 connecting the fourth tank 7 to the gas analyzer 11 is opened, and the recovered gas (mixed gas) accumulated in the fourth tank 7 is subjected to component analysis (impurity analysis) by the gas analyzer 11. The output from the gas analyzer 11 is input to a control device 12, which makes it possible to calculate the concentrations of each component and other impurities. When the component analysis is completed, valve VA2 is closed.

[0045] The control device 12 compares the measured impurity concentration with the judgment value, and if the impurity concentration is greater than the judgment value, determines that refining is necessary, and if the impurity concentration is equal to or less than the judgment value, determines that refining is not necessary. If the control device 12 determines that further purification is necessary, the process proceeds to step 7. If the controller 12 determines that further purification is not necessary, the process proceeds to step 8. The judgment value is determined based on the range in which the laser light generating device 1 can operate normally.

[0046] In this way, the purified mixed gas (recovered gas) is stored in the fourth tank 7 and the components are analyzed, thereby enabling quality control of the mixed gas.

[0047] It should be noted that the concentration of each component (additive gas) of the mixed gas may be analyzed (measured) in step 6. If the concentration of the additive gas does not reach a predetermined range, step 7 may be executed, and the process may proceed to step 4 for adding the additive gas again, and then to step 5.

[0048] Step 7 (re-purification step) Valves V3 and V6 are closed, and valves VB, V4, and V5 are open, and the recovered gas stored in the fourth tank 7 is guided to the second tank 4 via pipe B (bypass pipe), and is further pumped to the third tank 6 by the second pump 5. The mixed gas is stored in the third tank 6. When the pressure P6 of the third tank 6 reaches a predetermined pressure Pt3 (for example, the same value as Pt1) (P6≧Pt3), the control device 12 closes the valve VF and the valves V4 and V5. When it is determined that re-purification of the recovered gas is necessary, the fourth tank 7 and the second tank 4 are connected by piping B in step 7, enabling the movement of the recovered gas; in other steps, the movement of the recovered gas is blocked by valve VB. Then proceed to step 5.

[0049] As described above, depending on the result of the gas analysis in step 6, the fourth tank 7 and the second tank 4 are selectively connected to each other in a communicable or disconnectable manner by the pipe B and the valve VB. Here, "communication" refers to a state in which the valve VB is open and gas can move, and "shut off" refers to a state in which the valve VB is closed and gas movement is prevented.

[0050] Step 8 (purified gas supply step) In step 6, if it is determined that re-purification is not necessary, the mixed gas accumulated in the fourth tank 7 is pumped to the fifth tank 9 by the third pump 8 with the valve V10 located downstream of the fifth tank 9 (supply tank) in a closed state and the valves V8 and V9 located upstream and downstream of the third pump 8 in an open state. The mixed gas is accumulated in the fifth tank 9. When the pressure P9 of the mixed gas in the fifth tank 9 reaches a predetermined pressure Pt4 (eg, the same as Pt1) (P9≧Pt4), the valves V8 and V9 are closed. Thereafter, the valve V10 is opened, and the mixed gas stored in the fifth tank 9 is supplied to the laser light generator 1 via the second pipe 20 (supply pipe). Incidentally, before the valve V10 is opened, the components of the mixed gas stored in the fifth tank 9 may be analyzed by the gas analyzer 11. In this case, valves V10 and V9 are closed, and valve VA3 of pipe A3 connecting the fifth tank 9 and gas analyzer 11 is opened, and the components of the mixed gas in the fifth tank 9 are analyzed by the gas analyzer 11. This contributes to quality control and quality assurance of the purified recovered gas.

[0051] By refining the collected gas and replenishing it with additive gas through the above steps, the laser gas is recycled, which can contribute to reducing the operating costs of the laser light generating device 1.

[0052] A plurality of third tanks 6 may be provided and used alternately. For example, two third tanks 6A and 6B may be provided, and steps 1 and 2 may be performed in one of the third tanks 6A, and then steps 3 and onward may be performed while steps 1 and 2 are performed in the other third tank 6B, and the recovered gas may be accumulated and pressurized in the third tank 6B. After one of the third tanks 6A has completed step 10 or while the other of the third tanks 6A is performing step 10, the other third tank 6B can perform steps 3 and thereafter. By alternately using a plurality of third tanks 6, it is possible to contribute to improving the utilization efficiency of the gas purification apparatus 100.

[0053] Note that a plurality of purifiers 16 may be provided in parallel and used alternately. For example, the second purifier 16b may be a purifier that adsorbs water, and the third purifier 16c may be a purifier that adsorbs oxygen, and two of the second purifiers 16b, 16b' and two of the third purifiers 16c, 16c' may be connected in parallel to alternately perform the purification operation and the regeneration operation of the purifiers in parallel. By purifying the recovered gas using one of the purifiers 16 (e.g., the second purifier 16b and the third purifier 16c) and regenerating the other purifier 16 (e.g., the second purifier 16b' and the third purifier 16c'), the gas purification apparatus 100 can perform purification operations continuously without having to stop operation for regenerating the purifiers 16. For example, when the second refiner 16b is a refiner that adsorbs water, and the second refiner 16b is to be regenerated, the second refiner 16b is evacuated by a vacuum pump (not shown) to discharge adsorbed substances and the like from within the second refiner 16b, and then laser gas is supplied from a gas cylinder (not shown) into the second refiner 16b to fill the second refiner 16b with laser gas. For example, in the piping 30 connected to the second purifier 16b, valves are provided on the upstream side and downstream side of the second purifier 16b, and these valves are closed. A vacuum pump is connected to the piping 30 between the second purifier 16b and the upstream valve, the second purifier 16b is evacuated, and then a purge gas (e.g., argon) is supplied to the second purifier 16b from the piping 30 between the second purifier 16b and the downstream valve. Then, the supply of the purge gas is stopped, the second purifier 16b is evacuated, and then the vacuum pump is stopped, and the laser gas may be filled into the second purifier 16b from the piping 30 between the second purifier 16b and the downstream valve. The same applies to the third purifier 16c (e.g., a purifier that adsorbs oxygen).

[0054] Hereinafter, gas supply control device 15, which is a constant-volume gas supply device, will be described in detail with reference to the drawings. The constant-volume supply device is a device that supplies a predetermined volume of gas in one operation (ejection). Fig. 3 is a cross-sectional view showing the main configuration of the gas supply control device 15. Fig. 3(A) shows the connection relationship of the gas supply control device 15 in the gas purification device 100, and Figs. 3(B), (C), and (D) are cross-sectional views showing the operation of the gas supply control device 15.

[0055] The gas supply control device 15 has an inlet 151, an outlet 152, an inflow path 153, a constant volume portion 154 (accommodation area), an outlet path 155, a first valve 156 (inflow valve), and a second valve 157 (outflow valve). The first valve 156 and the second valve 157 are located at both ends of the constant volume portion 154. The first valve 156 has a first valve body 156a and a first valve seat 156b, and the second valve 157 has a second valve body 157a and a second valve seat 157b. When the first valve body 156a and the first valve seat 156b are separated from each other, the first valve 156 is in an open state, and when the first valve body 156a and the first valve seat 156b are in contact with each other, the first valve 156 is in a closed state. Similarly, when the second valve body 157a and the second valve seat 157b are separated from each other, the second valve 157 is in an open state, and when the second valve body 157a and the second valve seat 157b are in contact with each other, the second valve 157 is in a closed state. It should be noted that a known structure can be used as the valve to be operated. For example, a diaphragm or the like can be used as the valve body, and the valve can be operated, for example, by an air (gas) drive system using compressed air or the like, or an electromagnetic drive system using an electromagnet or the like.

[0056] The inlet 151 is connected to the cylinder 14 via a pipe 31 (addition pipe), and the outlet 152 is connected to the pipe 31 . The additive gas in the cylinder 14 is supplied to the gas supply control device 15 via a pressure regulator RG2. The pressure regulator RG2 adjusts the additive gas to a pressure (PG2=PG1+Pd) that is higher than the pressure (PG1) of the recovered gas set by the pressure regulator RG1 of the piping 30 by a predetermined amount Pd (e.g., 100 kPa). The additive gas flowing out from outlet 152 of gas supply control device 15 flows into pipe 30 via pipe 31 .

[0057] The gas supply operation by gas supply control device 15 will be described with reference to FIGS. For the supply of gas, a shot has the following steps:

[0058] Step 1 (inflow step) 3(B), the second valve 157 is closed, and the first valve 156 is open. As indicated by the arrows in the figure, the additive gas whose pressure is adjusted by the pressure regulator RG2 flows into the constant volume section 154 via the inlet 151, the inlet path 153, and the first valve 156.

[0059] Step 2 (Containment Step) As shown in FIG. 3C, the first valve 156 is closed, and the second valve 157 is also closed. The additive gas is sealed in the constant volume section 154 by a first valve 156 and a second valve 157. The sealed additive gas has a pressure PG2 (contained pressure) adjusted by the volume of the constant volume section 154 and a pressure regulator RG2. The amount of gas to be added is determined by the gas contained in the constant volume section 154. This makes it possible to deliver a predetermined volume of gas in one ejection. The volume of the constant volume portion 154 can be determined geometrically, and for the purpose of minute amount control, can be set to, for example, non-restrictively, 0.1-1 cc, but is not limited to this. This step determines the amount of added gas.

[0060] Step 3 (Outflow step) 3(D), the first valve 156 is kept closed, and the second valve 157 is opened. Since the pressure PG2 of the additive gas contained in the constant volume section 154 is higher than the pressure PG1 of the recovered gas in the piping 30, the additive gas flows out of the gas supply control device 15 via the second valve 157, the outflow path 155, and the outflow port 152, and flows into the piping 30.

[0061] The amount of additive gas added in one jet can be controlled by the volume and pressure of the constant volume section 154. By setting the volume of the constant volume section 154 according to the amount (volume) of addition to be controlled, even minute amounts can be controlled. By controlling the number of jets, the amount of additive gas can be adjusted, and a necessary amount of additive gas can be mixed into the collected gas. The number of jets per unit time is calculated by the control device 12 from the component concentration of the collected gas and the target component concentration, and the control device 12 controls the number of jets per unit time by controlling the opening and closing of the first valve 156 and the second valve 157. The control device 12 digitally controls the opening and closing of the first valve 156 and the second valve 157, and the constant volume supply device ejects the gas discretely (in pulses).

[0062] Conventionally, the additive gas is controlled by a continuous amount of gas flow using a flow control device, specifically a mass flow controller. However, a mass flow controller requires a finite time until the flow rate stabilizes, making it difficult to accurately control a minute doping amount. In addition, a mass flow controller has a minute amount of residual gas in the space (dead space) between the flow control unit and the open / close valve provided downstream of the flow control unit. Since this residual gas exists downstream of the flow control unit, the flow rate cannot be controlled, making it difficult to accurately control the additive amount. In other words, with flow control using a conventional mass flow controller, it is difficult to accurately control the supply amount of a minute additive gas from the gas cylinder 14.

[0063] On the other hand, the gas supply control device 15 determines the amount of gas added by the constant volume section 154 separated by two valves, so there is no dead space like in a mass flow controller, and no finite time is required to stabilize the flow rate. Therefore, the gas supply control device 15 is excellent at controlling minute amounts of gas added.

[0064] The gas supply control device 15 can be used not only to add gas during purification of the collected gas, but also to supply laser gas at the start-up of the laser light generating device 1. Since it can control the amount of small amounts of added gas, it can also be used to generate laser gas with an optimal component concentration and fill it into the laser chamber. By generating laser gas and removing impurities using purifier 16, it is possible to fill the laser chamber with laser gas of higher purity. [Industrial Applicability]

[0065] According to the present invention, the amount of additive gas added to the laser gas used in the laser light generating device can be accurately controlled, and by enabling re-purification, the impurity removal performance of the recovered gas is improved, making it possible to supply a high-quality recovered gas. Recycling the laser gas can contribute to reducing the operating costs of the laser light generating device, and the industrial applicability is high. [Explanation of symbols]

[0066] 100 Gas purification equipment 1. Laser light generating device 2. First tank (recovery tank) 3. First pump (recovery pump) 4. Second tank (first storage tank) 5. Second pump (booster pump) 6. Third tank (booster tank) 7 Fourth Tank (Second Storage Tank) 8. Third pump (supply pump) 9 5th tank (supply tank) 10 Piping (recovery piping) 11 Gas analyzer 12 Control device 13 Mixer 14 Gas Cylinder 14a First gas cylinder 14b Second gas cylinder 15, 15a, 15b Gas supply control device (constant volume supply device) 151 Inlet 152 Outlet 153 Inflow channel 154 Constant volume section (containment area) 155 Outflow channel 156 First valve (inlet valve) 156a First valve body 156b First valve seat 157 Second valve (outlet valve) 157a Second valve body 157b Second valve seat 16 Purifier (impurity removal device) 16a First refiner (impurity removal device) 16b Second refiner (impurity removal device) 16c Third Purifier (Impurity Removal Device) 16d Fourth Purifier (Impurity Removal Device) 20 Piping (supply piping) 30 Piping (main piping) 31, 31a, 31b piping (additional piping) 40 Case A1 Piping A2 Piping B piping (bypass piping) MFC Flow control device (Mass flow controller) G6 Pressure Gauge RG1 Pressure Regulator RG2, RG2a, RG2b Pressure Regulators V1-V10 Valves VA1, VA2 valves

Claims

1. A gas purification device that purifies a gas recovered from a laser light generating device that uses a laser gas, and supplies the gas to the laser light generating device, a flow rate control device for controlling the flow rate of the collected gas; a constant volume supply device provided downstream of the flow rate control device and supplying an additive gas; a purifier disposed downstream of the constant volume supply device.

2. 2. The gas purification system according to claim 1, wherein the constant volume supply device supplies the additive gas in a discrete manner.

3. the constant volume supply device has a constant volume section, a first valve, and a second valve; 3. The gas purification apparatus according to claim 2, wherein the first valve and the second valve are positioned on both ends of the constant volume section.

4. a first storage tank provided upstream of the flow control device; a second storage tank disposed downstream of the purifier; 4. The gas purification apparatus according to claim 1, wherein the first storage tank and the second storage tank are connected so as to be capable of communicating or being cut off from each other.

5. Equipped with a gas analyzer, 5. The gas purification system according to claim 4, wherein the gas analyzer performs a composition analysis of the gas in the first storage tank.

6. A recovery step of recovering laser gas from the laser light generating device; a recovered gas analysis step of analyzing the recovered gas and determining whether or not an additive gas needs to be added; an addition step of adding the additive gas by a constant volume supply device when it is determined in the collected gas analysis step that the addition of the additive gas is necessary; a purification step of purifying the recovered gas; a purified gas analysis step of performing a component analysis of the recovered gas purified by the purification step to determine whether or not repurification is required; a re-purification step of performing the purification step when it is determined in the purified gas analysis step that re-purification is necessary; A method for purifying a laser gas, comprising:

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