Laser device and leakage inspection method for laser device

Abstract

A leakage inspection method for a laser device includes the following steps: exposing a closed space containing a laser medium gas to the atmosphere; isolating the closed space from the atmosphere after exposing the closed space to the atmosphere; introducing a neon-containing gas containing neon gas into the closed space; and determining whether the neon gas has leaked to the outside of the closed space.

Description

Technical Field

[0001] The present disclosure relates to a laser device and a leakage inspection method for a laser device. Background Art

[0002] In recent years, in semiconductor exposure devices, as semiconductor integrated circuits become smaller and more highly integrated, there is a demand for improved resolution. Therefore, the wavelength of light emitted from an exposure light source has been shortened. For example, as a gas laser device for exposure, a KrF excimer laser device that outputs a laser with a wavelength of about 248nm and an ArF excimer laser device that outputs a laser with a wavelength of about 193nm are used.

[0003] The spectral line width of the natural oscillation light of the KrF excimer laser device and the ArF excimer laser device is relatively wide, at 350 to 400 pm. Therefore, when a projection lens is constructed using a material that transmits ultraviolet light such as KrF and ArF lasers, chromatic aberration sometimes occurs. As a result, the resolution may be reduced. Therefore, it is necessary to narrow the spectral line width of the laser output from the gas laser device to a level where chromatic aberration can be ignored. Therefore, sometimes a narrowing module (Line Narrowing Module: LNM) containing narrowing elements (etalon, grating, etc.) is included in the laser resonator of the gas laser device to narrow the spectral line width. Below, a gas laser device with a narrowed spectral line width is referred to as a narrowed gas laser device.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Utility Model Application Laid-Open No. 01-146565

[0007] Patent Document 2: U.S. Patent No. 6819699

[0008] Patent Document 3: Japanese Patent Application Publication No. 2008-270279

[0009] Patent Document 4: Japanese Utility Model Application Laid-Open No. 02-142558 Summary of the invention

[0010] A leakage inspection method for a laser device according to one aspect of the present disclosure includes the following steps: exposing a closed space containing a laser medium gas to the atmosphere; isolating the closed space from the atmosphere after exposing the closed space to the atmosphere; introducing a neon-containing gas containing neon gas into the closed space; and determining whether the neon gas has leaked to the outside of the closed space.

[0011] In a leakage inspection method for a laser device according to another aspect of the present disclosure, the laser device includes: a laser cavity; a first piping for introducing a first gas including neon gas and fluorine gas into the laser cavity; and a second piping for introducing a second gas including neon gas and having a fluorine gas concentration lower than that of the first gas into the laser cavity, wherein the leakage inspection method includes the following steps: introducing a third gas including neon gas and having a fluorine gas concentration lower than that of the first gas into a closed space including the space inside the laser cavity; and determining whether the neon gas has leaked to the outside of the closed space.

[0012] A laser device according to one aspect of the present disclosure includes: a laser cavity; a first pipe for introducing a first gas comprising neon and fluorine into the laser cavity; a second pipe for introducing a second gas comprising neon and having a fluorine concentration lower than that of the first gas into the laser cavity; and a third pipe for introducing a third gas comprising neon and having a fluorine concentration lower than that of the first gas into the laser cavity and the first pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Hereinafter, several embodiments of the present disclosure will be described as simple examples with reference to the accompanying drawings.

[0014] Figure 1 The structure of a laser device according to a comparative example is schematically shown.

[0015] Figure 2 : is a flowchart showing the procedure of the leakage inspection method in the comparative example.

[0016] Figure 3 It is a diagram illustrating the range of a closed space.

[0017] Figure 4 : is a flowchart showing the procedure of maintenance work in the comparative example.

[0018] Figure 5 : is a flowchart showing the procedure of leakage inspection in the comparative example.

[0019] Figure 6 The structure of the laser device according to the first embodiment is schematically shown.

[0020] Figure 7 This is a flowchart showing the procedure of the maintenance work in the first embodiment.

[0021] Figure 8 This is a flowchart showing the leakage inspection procedure in the first embodiment.

[0022] Fig. 9 This is a flowchart showing the leakage inspection procedure in the second embodiment.

[0023] Fig.10 The structure of the replacement laser cavity is schematically shown.

[0024] Fig.11 This is a flowchart showing the leakage inspection procedure in the third embodiment. DETAILED DESCRIPTION

[0025] content

[0026] 1. Laser device of comparative example

[0027] 1.1 Structure

[0028] 1.1.1 Laser oscillator and various control units

[0029] 1.1.2 Various gas supply devices and exhaust devices

[0030] 1.1.2.1 Laser gas supply device

[0031] 1.1.2.2 Cavity purge gas supply device

[0032] 1.1.2.3 Exhaust device

[0033] 1.1.2.4 Optical module purge gas supply device

[0034] 1.2 Action

[0035] 1.2.1 Operation of the laser oscillator

[0036] 1.2.2 Operation of the optical module purge gas supply device

[0037] 1.2.3 Leakage inspection method

[0038] 1.2.3.1 Maintenance work

[0039] 1.2.3.2 Leakage Check

[0040] 1.3 Issues of Comparative Example

[0041] 2. Laser device for leak detection using neon gas

[0042] 2.1 Structure

[0043] 2.2 Action

[0044] 2.2.1 Maintenance work

[0045] 2.2.2 Leakage Check

[0046] 2.3 Function

[0047] 3. Laser device for leak detection based on changes in air pressure

[0048] 4. Laser device for leak inspection of replacement laser cavity

[0049] 4.1 Replacement of laser cavity

[0050] 4.2 Leakage Inspection Process

[0051] 4.3 Function

[0052] 5. Others

[0053] Below, the embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The embodiments described below show several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and actions described in each embodiment are not necessarily all necessary for the structures and actions of the present disclosure. In addition, the same reference numerals are marked on the same structural elements and repeated descriptions are omitted.

[0054] 1. Laser device of comparative example

[0055] 1.1 Structure

[0056] Figure 1 The structure of the laser device 1 of the comparative example is schematically shown. The laser device 1 is used together with the exposure device 100 .

[0057] The laser device 1 includes a laser cavity 10, a narrowband module 14, an output coupling mirror 15, a laser control unit 30, and a gas control unit 32. The narrowband module 14 and the output coupling mirror 15 constitute a laser resonator. The laser device 1 also includes a laser gas supply device 33, a cavity purge gas supply device 35, an exhaust device 37, and an optical module purge gas supply device 39.

[0058] 1.1.1 Laser oscillator and various control units

[0059] The laser cavity 10 is disposed on the optical path of the laser resonator. The laser cavity 10, the laser resonator, and a high voltage power supply (not shown) constitute a laser oscillator. The laser cavity 10 is provided with windows 10a and 10b.

[0060] The laser cavity 10 contains a pair of electrodes 11a and 11b and a laser medium gas. The laser medium gas includes a halogen gas, a rare gas, and a buffer gas. For example, the halogen gas is fluorine gas, the rare gas is argon gas or krypton gas, and the buffer gas is neon gas. In addition, the laser medium gas may also include xenon gas as an additive gas. The laser cavity 10 is connected to a pressure gauge P.

[0061] The narrowband module 14 includes wavelength selection elements such as a prism 14a and a grating 14b. The narrowband module 14 is housed in a housing 18. The output coupling mirror 15 is composed of a partial reflection mirror. The output coupling mirror 15 is housed in a housing 19. A window 10c is provided in the housing 19. An energy monitor (not shown) for measuring the pulse energy of the pulsed laser may also be housed in the housing 19.

[0062] The laser control unit 30 is composed of a computer device including a CPU (central processing unit) 30a and a memory 30b. The memory 30b stores programs and data required for information processing. The CPU 30a is configured to read various data and perform information processing according to the program stored in the memory 30b. The laser control unit 30 is connected to an exposure device control unit (not shown) of the exposure device 100, an FDC system (fault detection and classification system) 120, and a user interface 140.

[0063] The gas control unit 32 is composed of a computer device including a CPU 32a and a memory 32b. The memory 32b stores programs and data required for information processing. The CPU 32a is configured to read various data and perform information processing according to the program stored in the memory 32b.

[0064] 1.1.2 Various gas supply devices and exhaust devices

[0065] Next, the laser gas supply device 33, the cavity purge gas supply device 35, the exhaust device 37, and the optical module purge gas supply device 39 are described. In the following description, the first end of the various pipes for gas flow is the end on the upstream side of the gas flow, and the second end is the end on the side opposite to the first end.

[0066] 1.1.2.1 Laser gas supply device

[0067] The laser gas supply device 33 includes a valve F2-V1 provided near the first end of the pipe 331 and a valve B-V1 provided near the first end of the pipe 332. The pipe 331 corresponds to the first pipe in the present disclosure, and the pipe 332 corresponds to the second pipe in the present disclosure.

[0068] The first end of the pipe 331 is connected to the fluorine-containing gas bottle 23 via the pipe 231. The fluorine-containing gas bottle 23 is equivalent to the first gas supply source in the present disclosure. The fluorine-containing gas bottle 23 contains fluorine-containing gas containing neon gas and fluorine gas. The fluorine-containing gas is equivalent to the first gas in the present disclosure. The fluorine-containing gas is, for example, a mixed gas of fluorine gas, argon gas, and neon gas.

[0069] The first end of the pipe 332 is connected to the neon-containing gas bottle 24 via the pipe 241. The neon-containing gas bottle 24 is equivalent to the second gas supply source in the present disclosure. The neon-containing gas bottle 24 contains a neon-containing gas containing neon gas and having a fluorine gas concentration lower than that of the fluorine-containing gas. The neon-containing gas is equivalent to the second gas in the present disclosure. The neon-containing gas may not contain fluorine gas. The neon-containing gas is, for example, a mixed gas of argon gas, neon gas, and xenon gas.

[0070] Alternatively, the fluorine-containing gas may be a mixed gas of fluorine gas, krypton gas and neon gas, and the neon-containing gas may be a mixed gas of krypton gas and neon gas.

[0071] The second end of the pipe 331 and the second end of the pipe 332 are connected to each other and further connected to the pipe 333. The pipe 333 is connected to the pipe 334, and the pipe 334 is connected to the laser cavity 10. A check valve 332a is provided near the second end of the pipe 332 to suppress the backflow of the fluorine-containing gas from the pipes 331 and 333. The pipes 331 and 332 may be provided with mass flow controllers (not shown).

[0072] 1.1.2.2 Cavity purge gas supply device

[0073] The chamber purge gas supply device 35 includes a valve L-V1 provided near the first end of the pipe 351. The first end of the pipe 351 is connected to the helium gas cylinder 25 via the pipe 251. The second end of the pipe 351 is connected to the connection portion of the pipe 333 and the pipe 334. A check valve 351a is provided near the second end of the pipe 351 to suppress the backflow of the fluorine-containing gas or the neon-containing gas from the pipe 333 and the pipe 334.

[0074] A first end of the pipe 352 is connected between the valve L-V1 and the check valve 351a of the pipe 351. A second end of the pipe 352 is connected to the pipe 331. A check valve 352a is provided near the second end of the pipe 352 to suppress the backflow of the fluorine-containing gas from the pipe 331.

[0075] A first end of the pipe 353 is connected between the valve L-V1 and the check valve 351a of the pipe 351. A second end of the pipe 353 is connected to the pipe 332. A check valve 353a is provided near the second end of the pipe 353 to suppress the backflow of the neon-containing gas from the pipe 332.

[0076] 1.1.2.3 Exhaust device

[0077] The exhaust device 37 includes a fluorine trap 37a and an exhaust pump 37b which are arranged in the pipe 373. The fluorine trap 37a contains a treatment agent for capturing fluorine gas and fluorine compounds. The exhaust pump 37b is configured to forcibly exhaust the gas after passing through the fluorine trap 37a. The pipe 373 may also include a bypass flow path (not shown) for bypassing the exhaust pump 37b, so that when the gas pressure in the laser cavity 10 is higher than the atmospheric pressure, the gas after passing through the fluorine trap 37a is released.

[0078] The first end of the pipe 373 is connected to the second end of the pipe 371 and the second end of the pipe 372. The first end of the pipe 371 is connected to the laser cavity 10. The pipe 371 is provided with a valve EX-V1. The first end of the pipe 372 is connected to the vicinity of the connection between the pipes 331 and 332. The pipe 372 is provided with a valve EX-V2.

[0079] 1.1.2.4 Optical module purge gas supply device

[0080] The optical module purge gas supply device 39 includes a valve N2-V1 provided near the first end of the piping 391. The first end of the piping 391 is connected to the nitrogen gas bottle 29 via the piping 291. The second end of the piping 391 branches into a piping 392 and a piping 393. The piping 392 is connected to the housing 18 containing the narrowband module 14. The piping 393 is connected to the housing 19 containing the output coupling mirror 15. Mass flow controllers (not shown) may be provided in the piping 392 and 393, respectively.

[0081] 1.2 Action

[0082] 1.2.1 Operation of the laser oscillator

[0083] The laser control unit 30 sends a trigger signal to a high voltage power supply (not shown) based on a control signal from the exposure device control unit. The high voltage power supply generates a pulsed high voltage based on the trigger signal and applies the high voltage to the electrodes 11a and 11b.

[0084] When a high voltage is applied to electrodes 11a and 11b, a discharge is induced between electrodes 11a and 11b. The laser medium gas in laser cavity 10 is excited by the energy of the discharge and transitions to a high energy level. Then, when the excited laser medium gas transitions to a low energy level, light of a wavelength corresponding to the energy level difference is emitted.

[0085] Light generated in the laser cavity 10 is emitted to the outside of the laser cavity 10 through windows 10a and 10b. The light emitted from the window 10a is narrowbanded by the narrowbanding module 14, and light near a desired wavelength returns to the laser cavity 10 through the window 10a.

[0086] The output coupling mirror 15 transmits a part of the light emitted from the window 10 b and outputs the light, and reflects the other part and returns the light to the laser cavity 10 through the window 10 b.

[0087] In this way, the light emitted from the laser cavity 10 reciprocates between the narrowband module 14 and the output coupling mirror 15. The light is amplified each time it passes through the discharge space between the electrodes 11a and 11b. In addition, the light is narrowbanded each time it returns at the narrowband module 14. The light oscillated and narrowbanded in this way is output from the laser resonator as a pulsed laser via the output coupling mirror 15, and is output from the laser device 1 via the window 10c.

[0088] The pulse laser light outputted from the laser device 1 is incident on the exposure device 100 .

[0089] 1.2.2 Operation of the optical module purge gas supply device

[0090] When the laser device 1 is operating, the optical module purge gas supply device 39 introduces nitrogen gas into the housings 18 and 19. At this time, the valve N2-V1 is opened, and the valves F2-V1, B-V1, L-V1, EX-V1, and EX-V2 are closed.

[0091] The amount of nitrogen introduced can also be controlled by a mass flow controller (not shown) provided in the pipes 392 and 393. The nitrogen is retained in the respective interiors of the housings 18 and 19 and then discharged from the exhaust ports 18a and 19a. By introducing nitrogen into the housings 18 and 19, contamination of the optical elements in the respective interiors of the housings 18 and 19 is suppressed.

[0092] 1.2.3 Leakage inspection method

[0093] Figure 2 1 is a flowchart showing the process of the leakage inspection method in the comparative example. The leakage inspection method is performed in the order of maintenance work (S10) and leakage inspection (S30).

[0094] The maintenance work ( S10 ) includes the following steps: exposing the closed space containing the laser medium gas to the atmosphere, then performing component replacement of the laser cavity 10 , and then isolating the closed space from the atmosphere.

[0095] The leakage check (S30) includes the following steps: introducing helium gas into a closed space isolated from the atmosphere, and then determining whether the helium gas leaks to the outside of the closed space.

[0096] Figure 3 It is a diagram illustrating the range of a closed space. Figure 3 Selectively show Figure 1 The laser cavity 10 and various pipes in the laser device 1 shown in the figure are enclosed in the laser cavity 10 and the pipes by the dotted line. The enclosed space includes the space inside each part of the pipes 331, 332, 351, 371, 372, the space inside each of the pipes 333, 334, 352 and 353, and the space inside the laser cavity 10.

[0097] 1.2.3.1 Maintenance work

[0098] Figure 4 : is a flowchart showing the procedure of maintenance work in the comparative example. Figure 4 The flowchart is equivalent to Figure 2 The S10 subroutine. Figure 4 In the illustrated process, steps surrounded by a solid line frame represent operations of the gas control unit 32 , and steps surrounded by a dotted line frame represent operations of an operator.

[0099] In the maintenance of the laser cavity 10 , the fluorine gas inside the closed space is removed by the following process before the closed space is exposed to the atmosphere.

[0100] In S11 , the gas control unit 32 sets the value of a counter N for counting the number of repetitions of gas exhaust to an initial value of 1.

[0101] In S12, the gas control unit 32 exhausts the gas inside the closed space via the fluorine trap 37a. Specifically, valves F2-V1, B-V1 and L-V1 are still closed, and valves EX-V1 and EX-V2 are opened. As a result, the gas inside the laser cavity 10 flows to the exhaust device 37 via valve EX-V1, and the gas inside the pipes 331, 332, 333, 334, 351, 352 and 353 flows to the exhaust device 37 via valve EX-V2. In the exhaust device 37, the fluorine trap 37a captures fluorine gas and fluorine compounds. The gas after passing through the fluorine trap 37a is discharged to the outside of the laser device 1 via the exhaust pump 37b or the bypass flow path not shown. When the exhaust pump 37b is driven, exhaust can be performed so that the gas pressure inside the closed space is less than the atmospheric pressure.

[0102] In S13, the gas control unit 32 introduces helium into the closed space. Specifically, valves F2-V1 and B-V1 are still closed, the driving of the exhaust pump 37b is stopped, valves EX-V1 and EX-V2 are closed, and valve L-V1 is opened. Thus, helium is introduced into the laser cavity 10 from the pipe 351 via the pipes 352, 353, 331, 332, 333 and 334. Helium is also introduced into each part of the pipes 371 and 372. In this way, the gas purge of the closed space is performed using helium. After the helium is introduced, the gas control unit 32 closes the valve L-V1.

[0103] In S14, the gas control unit 32 determines whether the value of the counter N has reached a predetermined value Nmax. The predetermined value Nmax is an integer greater than or equal to 2.

[0104] When the value of the counter N does not reach the predetermined value Nmax (S14: No), the gas control unit 32 causes the process to proceed to S15. In S15, the gas control unit 32 adds 1 to the value of the counter N and updates the value of N. After S15, the gas control unit 32 returns the process to S12. By repeatedly exhausting the gas and introducing the helium gas multiple times, the fluorine gas in the closed space including the space inside the laser cavity 10 is removed to a concentration that can be exposed to the atmosphere.

[0105] When the value of the counter N reaches the predetermined value Nmax ( S14 : YES), the gas control unit 32 advances the process to S16 .

[0106] In S16, the gas control unit 32 notifies the outside that the removal of the fluorine gas is completed. For example, the gas control unit 32 sends a signal indicating that the removal of the fluorine gas is completed to the laser control unit 30. With this signal as an opportunity, the laser control unit 30 sends a notification indicating that the removal of the fluorine gas is completed to the FDC system 120. On the basis of the notification to the FDC system 120, or instead of the notification to the FDC system 120, the laser control unit 30 causes the user interface 140 to display that the removal of the fluorine gas is completed.

[0107] In S17, the operator exposes the closed space to the atmosphere to replace the components of the laser cavity 10. For example, when the window 10a or 10b is replaced, at least a portion of the space inside the laser cavity 10 is exposed to the atmosphere. In addition, for example, when the laser cavity 10 itself is replaced, a portion of the piping 334, 371 connected to the laser cavity 10 is also exposed to the atmosphere. In S18, the operator replaces the components of the laser cavity 10.

[0108] In S19, the operator isolates the closed space from the atmosphere, and further inputs completion of the maintenance work through the user interface 140. The laser control unit 30 receives the signal input to the user interface 140, and transmits a signal indicating completion of the maintenance work to the gas control unit 32.

[0109] In S20, the gas control unit 32 determines whether a signal indicating the completion of the maintenance work is received. If a signal indicating the completion of the maintenance work is not received (S20: No), the gas control unit 32 waits until a signal indicating the completion of the maintenance work is received. If a signal indicating the completion of the maintenance work is received (S20: Yes), the gas control unit 32 ends the processing of this flowchart and returns to Figure 2 Processing shown.

[0110] 1.2.3.2 Leakage Check

[0111] Figure 5: is a flowchart showing the procedure of leakage inspection in the comparative example. Figure 5 The flowchart is equivalent to Figure 2 The S30 subroutine. Figure 5 In the illustrated process, steps surrounded by a solid line frame represent operations of the gas control unit 32 , and steps surrounded by a dotted line frame represent operations of an operator.

[0112] In S32, the gas control unit 32 opens the valve L-V1 to introduce helium gas into the closed space. At this time, the valves F2-V1, B-V1, EX-V1, and EX-V2 are closed.

[0113] In S33, the gas control unit 32 determines whether the gas pressure inside the laser cavity 10 measured by the pressure gauge P reaches a predetermined value. When the gas pressure inside the laser cavity 10 does not reach the predetermined value (S33: No), the gas control unit 32 waits until the gas pressure inside the laser cavity 10 reaches the predetermined value. When the gas pressure inside the laser cavity 10 reaches the predetermined value (S33: Yes), the gas control unit 32 advances the process to S34.

[0114] In S34, the gas control unit 32 closes the valve L-V1 and notifies the outside that the filling of the gas is completed. For example, the gas control unit 32 sends a signal indicating that the filling of the gas is completed to the laser control unit 30, and the laser control unit 30 sends a notification indicating that the filling of the gas is completed to the FDC system 120, and / or causes the user interface 140 to display that the filling of the gas is completed.

[0115] In S35, the operator uses a helium leak detector (not shown) to determine whether helium has leaked to the outside of the closed space. For example, when the window 10a or 10b is replaced, the operator checks whether helium has leaked around the replaced window. Then, the operator inputs the determination result via the user interface 140. The laser control unit 30 receives the signal input to the user interface 140 and sends a signal indicating the determination result to the gas control unit 32. Alternatively, a signal indicating the determination result may be sent from the helium leak detector to the laser control unit 30, and the laser control unit 30 sends the signal to the gas control unit 32.

[0116] In S36 , the gas control unit 32 identifies a determination result as to whether or not the helium gas has leaked to the outside of the closed space.

[0117] If the helium gas leaks to the outside of the closed space (S36: Yes), the gas control unit 32 ends the processing of this flowchart and returns to Figure 2At this time, the gas control unit 32 may also send a signal indicating an apparatus error to the laser control unit 30. The laser control unit 30 may also send a notification indicating an apparatus error to the FDC system 120 and / or cause the user interface 140 to display an apparatus error.

[0118] If the helium gas has not leaked to the outside of the closed space (S36: No), the gas control unit 32 causes the process to proceed to S37. In S37, the gas control unit 32 exhausts the gas inside the closed space. The exhaust process can be the same as Figure 4 The process is the same as that described in S12 of . Then, in S38, the gas control unit 32 introduces neon-containing gas and fluorine-containing gas into the closed space including the space inside the laser cavity 10. Specifically, first, valves EX-V1, EX-V2, F2-V1 and L-V1 are closed, and valve B-V1 is opened. Thus, neon-containing gas is introduced into the laser cavity 10 from the piping 332. Next, valves EX-V1, EX-V2, B-V1, L-V1 are closed, and valve F2-V1 is opened. Thus, fluorine-containing gas is introduced into the laser cavity 10 from the piping 331.

[0119] After the gas pressure and fluorine gas concentration inside the laser cavity 10 reach the desired values, the gas control unit 32 closes valves EX-V1, EX-V2, F2-V1, B-V1 and L-V1, and sends a signal indicating that the laser device 1 is ready to work to the laser control unit 30.

[0120] Alternatively, in order to stabilize the gas composition inside the laser cavity 10 , after the exhaustion in S37 and the gas introduction in S38 are repeated a plurality of times, a signal indicating that the operation preparation of the laser device 1 is completed may be sent to the laser control unit 30 .

[0121] After S38, the gas control unit 32 ends the processing of this flowchart and returns to Figure 2 Processing shown.

[0122] 1.3 Issues of Comparative Example

[0123] In the comparative example, helium is used for gas purging and leak detection in a closed space. However, the origin and output of helium are limited, so sometimes it is difficult to supply or expensive. If the supply of helium stops, it is impossible to maintain the laser device 1, and it may be impossible to operate the laser device 1.

[0124] 2. Laser device for leak detection using neon gas

[0125] 2.1 Structure

[0126] use Figure 6 to Figure 8 The first embodiment will be described.

[0127] Figure 6 The structure of the laser device 1 of the first embodiment is schematically shown. In the first embodiment, the helium gas cylinder 25 may not be provided. The pipe 351 is configured to introduce a third gas containing neon gas and having a lower fluorine gas concentration than the fluorine-containing gas into the laser cavity 10 and the pipes 331 and 332. The pipe 351 is equivalent to the third pipe in the present disclosure.

[0128] Preferably, the third gas is a gas of the same composition as the neon-containing gas. Gases of the same composition refer to gases having the same components and their mixing ratios. More preferably, the first end of the pipe 351 is connected to the neon-containing gas bottle 24. The neon-containing gas bottle 24 is connected to the pipe 242. The pipe 242 branches into the pipe 243 and the pipe 244 at the branch portion 24a. The pipe 243 is connected to the first end of the pipe 332, and the pipe 244 is connected to the first end of the pipe 351. The pipes 242, 243, and 244 are equivalent to the fourth pipe in the present disclosure.

[0129] Regarding other points, the structure of the first embodiment is the same as that of the comparative example.

[0130] 2.2 Action

[0131] The operation of the laser oscillator and the operation of the optical module purge gas supply device 39 in the first embodiment are the same as those described in the above comparative example. Figure 2 The process described is performed in the same manner as described above. However, the subroutine described below is different between the first embodiment and the comparative example.

[0132] 2.2.1 Maintenance work

[0133] Figure 7 FIG. 1 is a flowchart showing the maintenance work process in the first embodiment. Figure 4 S13, in Figure 7 In S13a, the gas control unit 32 introduces neon-containing gas into the closed space.

[0134] Regarding other aspects, Figure 7 Processing and reference Figure 4 The processing of the comparative example described is the same.

[0135] 2.2.2 Leakage Check

[0136] Figure 8 FIG. 1 is a flowchart showing the leakage inspection process in the first embodiment. Figure 5 S32, in Figure 8 In S32a of the embodiment, the gas control unit 32 introduces neon-containing gas into the closed space. Figure 5 The S35, in Figure 8 In S35a, the operator uses a leak detector (not shown) that is sensitive to neon gas to determine whether neon gas has leaked to the outside of the enclosed space. For example, when more neon gas than a predetermined threshold is detected, it is determined that neon gas has leaked to the outside of the enclosed space. The leak detector that is sensitive to neon gas can be, for example, a device that detects neon gas by detecting the difference in thermal conductivity between a reference gas and a measurement gas. The leak detector can also be configured to output a display or an alarm based on the detected amount of neon gas.

[0137] Regarding other aspects, Figure 8 Processing and reference Figure 5 The processing of the comparative example described is the same.

[0138] 2.3 Function

[0139] (1) According to the first embodiment, a neon-containing gas ( Figure 8 S32a), determining whether neon gas has leaked to the outside of the closed space ( Figure 8 Thus, even without using helium, leakage inspection can be performed, so that even when the supply of helium is difficult, it is possible to prevent the laser device 1 from stopping due to inability to maintain.

[0140] (2) According to the first embodiment, the gas inside the closed space is exhausted through the fluorine trap 37a before the closed space is exposed to the atmosphere. Figure 7 S12), introducing neon-containing gas into the enclosed space ( Figure 7 The gas inside the closed space is discharged again through the fluorine trap 37a ( Figure 7 Thus, even without using helium, the fluorine gas concentration can be reduced by gas purging inside the closed space. In addition, the gas purging is performed using the same neon-containing gas as that used in the leak inspection, thereby suppressing the increase in piping.

[0141] (3) According to the first embodiment, a leak detector having sensitivity to neon gas is used to determine whether neon gas has leaked to the outside of the closed space. Figure 8 Thus, the neon-containing gas can be introduced into the laser cavity 10 and a leak check can be performed immediately.

[0142] (4) According to the first embodiment, when it is determined that neon gas has not leaked to the outside of the closed space, the gas inside the closed space is exhausted ( Figure 8 S37), introducing neon-containing gas and fluorine-containing gas into the closed space ( Figure 8In this way, it is determined in advance that neon gas has not leaked, so when fluorine-containing gas is introduced, the leakage of fluorine gas can be suppressed. In addition, compared with the case of using helium gas for leak inspection, when using neon-containing gas for leak inspection, the number of repetitions of exhaust in S37 and gas introduction in S38 can be reduced.

[0143] (5) According to the first embodiment, the laser device 1 includes: a pipe 331 for introducing a fluorine-containing gas including neon and fluorine into the laser cavity 10; a pipe 332 for introducing a neon-containing gas including neon and having a fluorine concentration lower than that of the fluorine-containing gas into the laser cavity 10; and a pipe 351 for introducing a third gas including neon and having a fluorine concentration lower than that of the fluorine-containing gas into the laser cavity 10 and the pipe 331. Thus, even if helium is not used, the third gas including neon can be used to perform a leak inspection, so that even when the supply of helium is difficult, it is possible to prevent the laser device 1 from stopping due to inability to maintain.

[0144] In addition, although the case where the third gas is introduced through the pipe 351 has been described, the present disclosure is not limited thereto. Even without the pipe 351 , the third gas having the same composition as the neon-containing gas may be introduced through the pipe 332 .

[0145] (6) According to the first embodiment, the piping 351 introduces the third gas having the same composition as the neon-containing gas into the laser cavity 10 and the piping 331. As a result, the neon-containing gas constituting the laser medium gas can be used as the third gas for leak detection, thereby reducing the number of gas supply types. In addition, the cost of piping construction for the third gas can be reduced.

[0146] (7) According to the first embodiment, the pipe 331 is connected to the fluorine-containing gas bottle 23 containing the fluorine-containing gas, and the pipes 332 and 351 are connected to the neon-containing gas bottle 24 containing the neon-containing gas.

[0147] Furthermore, according to the first embodiment, the pipes 242 , 243 , and 244 including the branch portion 24 a are connected between the pipes 332 and 351 and the neon-containing gas bottle 24 .

[0148] This allows the gas cylinders connected to the pipes 332 and 351 to be common. Furthermore, since the piping for helium gas is unnecessary, the cost of piping construction can be reduced.

[0149] (8) According to the first embodiment, the pipe 351 introduces the third gas into the laser cavity 10 and the pipes 331 and 332. This allows not only the laser cavity 10 but also the pipes 331 and 332 to be leak-checked simultaneously.

[0150] (9) According to the first embodiment, the laser device 1 includes the exhaust device 37 for exhausting gas from the laser cavity 10 and the pipe 331. This allows the third gas to be introduced into the exhausted laser cavity 10 and the pipe 331 to perform a leak check.

[0151] (10) According to the first embodiment, the laser device 1 includes the exhaust device 37 for exhausting gas from the laser cavity 10 and the pipes 331 and 332. This allows the third gas to be introduced into the exhausted laser cavity 10 and the pipes 331 and 332 to perform a leak check.

[0152] 3. Laser device for leak detection based on changes in air pressure

[0153] use Fig. 9 The second embodiment will be described. The configuration of the second embodiment is the same as that of the first embodiment. In the leakage check subroutine described below, the operation of the second embodiment is different from that of the first embodiment.

[0154] Fig. 9 FIG. 1 is a flowchart showing the leakage inspection process in the second embodiment. Figure 8 S35a, in Fig. 9 In S35b, the gas control unit 32 detects the change in the gas pressure inside the laser cavity 10 during a certain period T, thereby determining whether the neon-containing gas has leaked to the outside of the closed space.

[0155] For example, the gas controller 32 receives the gas pressure P1 inside the laser cavity 10 measured by the pressure gauge P from the laser controller 30, and further receives the gas pressure P2 after a certain period T has passed from the laser controller 30. Then, the gas controller 32 calculates the following value ΔP or dP / dT.

[0156] ΔP=|P1-P2|

[0157] dP / dT=|P1-P2| / T

[0158] The gas control unit 32 determines that the neon-containing gas has not leaked to the outside of the closed space when ΔP is less than a predetermined threshold value or when dP / dT is less than a predetermined threshold value. The gas control unit 32 determines that the neon-containing gas has leaked to the outside of the closed space when ΔP is greater than a predetermined threshold value or when dP / dT is greater than a predetermined threshold value.

[0159] Regarding other aspects, the operation of the second embodiment is the same as that of the first embodiment.

[0160] According to the second embodiment, the change in the gas pressure inside the closed space is detected to determine whether the neon-containing gas has leaked to the outside of the closed space ( Fig. 9Thus, the leakage inspection can be automated and the number of man-hours of the operator can be reduced.

[0161] 4. Laser device for leak inspection of replacement laser cavity

[0162] use Fig.10 and Fig.11 The third embodiment will be described. The configuration of the third embodiment is the same as that of the first and second embodiments. The third embodiment is different from the first and second embodiments in that a leakage check of the replacement laser cavity 10d is performed.

[0163] 4.1 Replacement of laser cavity

[0164] Fig.10 The structure of the replacement laser cavity 10d is schematically shown. The replacement laser cavity 10d is provided with windows 10a and 10b, and contains electrodes 11a and 11b, which is the same as the laser cavity 10. When the above maintenance work includes replacement of the laser cavity 10, the laser cavity 10 is removed from the laser device 1, Fig.10 The replacement laser cavity 10 d shown is mounted on the laser device 1 .

[0165] 4.2 Leakage Inspection Process

[0166] Fig.11 1 is a flowchart showing the leakage inspection procedure in the third embodiment. The steps surrounded by a dotted frame represent the operations of the manufacturer of the laser device 1 .

[0167] In S1, the manufacturer of the laser device 1 fills the replacement laser cavity 10d with neon-containing gas in the manufacturing plant of the laser device 1, and causes a storage device (not shown) to store the gas pressure P1 and the measurement time T1 inside the replacement laser cavity 10d. The storage device may be, for example, a storage device attached to the replacement laser cavity 10d. Alternatively, the storage device may be a storage device on a network that can be accessed from the gas control unit 32 or the laser control unit 30 of the laser device 1 installed in the semiconductor manufacturing plant of the shipping destination.

[0168] The replacement laser cavity 10 d is shipped to a semiconductor manufacturing factory and is mounted in the laser device 1 through a laser cavity replacement operation of the laser device 1 .

[0169] In S2, the gas control unit 32 determines whether a signal indicating completion of the laser cavity replacement operation is received. If a signal indicating completion of the laser cavity replacement operation is not received (S2: No), the gas control unit 32 waits until a signal indicating completion of the laser cavity replacement operation is received. If a signal indicating completion of the laser cavity replacement operation is received (S2: Yes), the gas control unit 32 advances the process to S3.

[0170] In S3, the gas control unit 32 receives the gas pressure P2 and the measurement time T2 inside the laser cavity 10 measured by the pressure gauge P from the laser control unit 30. The laser cavity 10 in this case is the newly installed replacement laser cavity 10d. The gas control unit 32 reads the gas pressure P1 and the measurement time T1 stored in the storage device, and calculates the following value ΔP or dP / dT.

[0171] ΔP=|P1-P2|

[0172] dP / dT=|P1-P2| / (T2-T1)

[0173] When ΔP is less than a predetermined threshold value, or when dP / dT is less than a predetermined threshold value, the gas control unit 32 determines that the neon-containing gas has not leaked to the outside of the laser cavity 10. When ΔP is greater than a predetermined threshold value, or when dP / dT is greater than a predetermined threshold value, the gas control unit 32 determines that the neon-containing gas has leaked to the outside of the laser cavity 10.

[0174] Processing and reference of S36~S38 Figure 5 The corresponding processing described above is the same. When the neon-containing gas leaks to the outside of the closed space (S36: Yes), or after S38, the gas control unit 32 ends the processing of this flowchart.

[0175] Regarding other aspects, the third embodiment is the same as the first or second embodiment.

[0176] 4.3 Function

[0177] According to the third embodiment, a leakage check is performed on the replacement laser cavity 10d ( Fig.11 Then, a fluorine-containing gas ( Fig.11 Thus, since it is determined in advance that neon gas has not leaked, it is possible to suppress leakage of fluorine gas from the replacement laser cavity 10d when fluorine-containing gas is introduced. In addition, compared with the case of using helium gas for leak inspection, when using neon-containing gas for leak inspection, the number of repetitions of exhaust in S37 and gas introduction in S38 can be reduced.

[0178] 5. Others

[0179] The above description is not intended to be limiting, but is intended to be a simple illustration. Therefore, it is clear to those skilled in the art that changes can be made to the embodiments of the present disclosure without departing from the claims. In addition, it is also clear to those skilled in the art that the embodiments of the present disclosure can be used in combination.

[0180] Unless explicitly stated, the terms used in this specification and claims as a whole should be interpreted as "non-limiting" terms. For example, terms such as "including", "having", "all", and "having" should be interpreted as "excluding the existence of structural elements other than the recorded structural elements". In addition, the modifier "one" should be interpreted as meaning "at least one" or "one or more". In addition, terms such as "at least one of A, B, and C" should be interpreted as "A", "B", "C", "A+B", "A+C", "B+C", or "A+B+C". Furthermore, it should be interpreted as also including combinations of them and parts other than "A", "B", and "C".

Claims

1. A method for leak inspection of a laser device, wherein: The laser device comprises: Laser cavity; a first pipe connected to a first gas supply source containing a first gas, and introducing the first gas into the laser cavity, wherein the first gas includes neon gas and fluorine gas; and a second pipe connected to a second gas supply source containing a second gas, and introducing the second gas into the laser cavity, wherein the second gas contains neon gas and has a fluorine gas concentration lower than that of the first gas; The leakage inspection method comprises the following steps: Exposing a closed space including the interior of the laser cavity and containing laser medium gas to the atmosphere; After exposing the enclosed space to the atmosphere, isolating the enclosed space from the atmosphere; introducing a third gas having the same composition as the second gas into the closed space from the second gas supply source; and It is determined whether neon gas has leaked to the outside of the closed space.

2. The leakage inspection method according to claim 1, wherein: The leakage inspection method further includes the following steps: before the exposure to the atmosphere, exhausting the gas inside the closed space through a fluorine trap, introducing the third gas into the closed space, and exhausting the gas inside the closed space again through the fluorine trap.

3. The leakage inspection method according to claim 1, wherein: The above determination is performed using a leak detector that is sensitive to neon gas.

4. The leakage inspection method according to claim 1, wherein: The determination is performed by detecting a change in the air pressure inside the closed space.

5. The leakage inspection method according to claim 1, wherein: The leakage inspection method further includes the following steps: when it is determined as a result of the determination that the neon gas has not leaked to the outside of the closed space, exhausting the gas inside the closed space and introducing the third gas and the first gas into the closed space.

6. A method for leak inspection of a laser device, the laser device comprising: Laser cavity; a first pipe connected to a first gas supply source containing a first gas, and introducing the first gas into the laser cavity, wherein the first gas includes neon gas and fluorine gas; and a second pipe connected to a second gas supply source containing a second gas, and introducing the second gas into the laser cavity, wherein the second gas contains neon gas and has a fluorine gas concentration lower than that of the first gas; in, The leakage inspection method comprises the following steps: introducing a third gas having the same composition as that of the second gas from the second gas supply source into a closed space including a space inside the laser cavity; and It is determined whether neon gas has leaked to the outside of the closed space.

7. The leakage inspection method according to claim 6, wherein: The laser device further includes a third pipe for introducing the third gas into the closed space.

8. A method for leak inspection of a laser device, wherein: The laser device comprises: Laser cavity; a first pipe connected to a first gas supply source containing a first gas, and introducing the first gas into the laser cavity, wherein the first gas includes neon gas and fluorine gas; a second pipe connected to a second gas supply source containing a second gas, and introducing the second gas into the laser cavity, wherein the second gas contains neon gas and has a fluorine gas concentration lower than that of the first gas; and a third pipe connected to the second gas supply source and introducing a third gas having the same composition as the second gas into the laser cavity; The leakage inspection method comprises the following steps: introducing the third gas into a closed space including a space inside the laser cavity; and It is determined whether neon gas has leaked to the outside of the closed space.

9. The leakage inspection method according to claim 8, wherein: A fourth pipe including a branch portion is connected between the second pipe, the third pipe, and the second gas supply source.

10. A laser device, comprising: Laser cavity; a first pipe connected to a first gas supply source containing a first gas, and introducing the first gas into the laser cavity, wherein the first gas includes neon gas and fluorine gas; a second pipe connected to a second gas supply source containing a second gas, and introducing the second gas into the laser cavity, wherein the second gas contains neon gas and has a fluorine gas concentration lower than that of the first gas; and A third pipe is connected to the second gas supply source and introduces a third gas having the same composition as that of the second gas into the laser cavity and the first pipe.

11. The laser device according to claim 10, wherein: A fourth pipe including a branch portion is connected between the second pipe, the third pipe, and the second gas supply source.

12. The laser device according to claim 10, wherein: The third pipe introduces the third gas into the laser cavity, the first pipe, and the second pipe.

13. The laser device according to claim 10, wherein: The laser device further includes an exhaust device that exhausts gas from the laser cavity and the first pipe.

14. The laser device according to claim 10, wherein: The laser device further includes an exhaust device that exhausts gas from the laser cavity, the first pipe, and the second pipe.

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