Laser apparatus, laser system, and method for manufacturing electronic device

Abstract

The laser apparatus includes: a laser chamber connected to a gas circulation system including a merging pipe in which exhaust gases discharged from a plurality of laser apparatuses including the laser apparatus are merged; the gas circulation system selects one of a fresh gas containing xenon and a circulation gas flowing through the merging pipe and supplies the selected gas to the plurality of laser devices. A discharge pipe which is connected between the laser chamber and the merging pipe and through which exhaust gas discharged from the laser chamber flows toward the merging pipe; a fluorine trap which is connected to the midway of the discharge pipe and which removes at least fluorine from the exhaust gas discharged from the laser chamber; and a xenon adding device which is connected to the midway of the discharge pipe, and which adds an additive gas having a higher xenon concentration than the fresh gas to the discharge gas discharged from the laser chamber.

Description

Technical Field

[0001] The present disclosure relates to a laser device, a laser system, and a method for manufacturing an electronic 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 allows ultraviolet light such as KrF and ArF lasers to pass through, 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 is invisible. Therefore, in order to narrow the spectral line width, a narrowing module (Line Narrowing Module: LNM) containing narrowing elements (etalon, grating, etc.) is sometimes provided in the laser resonator of the gas laser device. A gas laser device with a narrowed spectral line width is called a narrowed laser device.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent Application Publication No. 2020 / 0403371

[0007] Patent Document 2: U.S. Patent Application Publication No. 2016 / 0248215 Summary of the invention

[0008] A laser device according to one aspect of the present disclosure includes: a laser cavity connected to a gas circulation system, the gas circulation system including a converging pipe, exhaust gases discharged from a plurality of laser devices including a laser device converge in the converging pipe, the gas circulation system selects one of a new gas containing xenon and a circulating gas flowing in the converging pipe and supplies it to the plurality of laser devices; an exhaust pipe connected between the laser cavity and the converging pipe, for the exhaust gas discharged from the laser cavity to flow toward the converging pipe; a fluorine collector connected to the middle of the exhaust pipe, for removing at least fluorine from the exhaust gas discharged from the laser cavity; and a xenon adding device connected to the middle of the exhaust pipe, for adding an added gas having a higher xenon concentration than the new gas to the exhaust gas discharged from the laser cavity.

[0009] A laser system according to one aspect of the present disclosure comprises: a plurality of laser devices; and a gas circulation system including a converging pipe, wherein exhaust gases discharged from the plurality of laser devices converge in the converging pipe, and the gas circulation system selects one of a new gas containing xenon and a circulating gas flowing in the converging pipe and supplies it to the plurality of laser devices.

[0010] The plurality of laser devices respectively include: a laser cavity connected to a gas circulation system; an exhaust pipe connected between the laser cavity and a converging pipe for allowing exhaust gas exhausted from the laser cavity to flow toward the converging pipe; a fluorine collector connected to the middle of the exhaust pipe for removing at least fluorine from the exhaust gas exhausted from the laser cavity; and a xenon adding device connected to the middle of the exhaust pipe for adding an added gas having a higher xenon concentration than the new gas to the exhaust gas exhausted from the laser cavity.

[0011] A method for manufacturing an electronic device according to one aspect of the present disclosure includes the step of generating laser light by one of a plurality of laser devices, the laser device having: a laser cavity connected to a gas circulation system, the gas circulation system including a confluence pipe, exhaust gases discharged from a plurality of laser devices confluence in the confluence pipe, the gas circulation system selecting one of a new gas containing xenon and a circulating gas flowing in the confluence pipe and supplying it to the plurality of laser devices; an exhaust pipe connected between the laser cavity and the confluence pipe, for the exhaust gas discharged from the laser cavity to flow toward the confluence pipe; a fluorine trap connected to the middle of the exhaust pipe, for removing at least fluorine from the exhaust gas discharged from the laser cavity; and a xenon adding device connected to the middle of the exhaust pipe, for adding an added gas having a higher xenon concentration than the new gas to the exhaust gas discharged from the laser cavity. The method for manufacturing an electronic device includes the steps of outputting laser light to an exposure device, exposing the laser light on a photosensitive substrate in the exposure device, and manufacturing the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Hereinafter, several embodiments of the present disclosure will be described as simple examples with reference to the accompanying drawings.

[0013] Figure 1 The structure of a laser system of a comparative example is schematically shown.

[0014] Figure 2 Examples of fluorine concentration and xenon concentration of various gases in comparative examples are shown.

[0015] Figure 3 Examples of fluorine concentration and xenon concentration of various gases in a case where a gas circulation system is connected to a plurality of laser cavities in a comparative example are shown.

[0016] Figure 4 The configuration of the laser system according to the first embodiment is schematically shown.

[0017] Figure 5 This is a flowchart schematically showing gas control in a laser device.

[0018] Figure 6 The operation of the initial gas supply is schematically shown.

[0019] Figure 7 Results for the initial gas supply are shown.

[0020] Figure 8 The operation of the nth gas flushing is schematically shown.

[0021] Fig. 9 The results of gas discharge in the first gas flushing are shown.

[0022] Fig.10 The results of gas supply in the first gas flushing are shown.

[0023] Fig.11 The results of gas discharge in the nth gas flushing are shown.

[0024] Fig.12 The results of gas supply in the n-th gas flushing are shown.

[0025] Fig.13 : is a flowchart showing the xenon addition process in the first embodiment.

[0026] Fig.14 It is a flowchart showing the details of the control of the xenon adding device.

[0027] Fig.15 yes Fig.14 The timing chart of xenon addition in the control of the xenon addition device is shown.

[0028] Fig.16 The graph shows the change over time of the pulse energy of the laser light output from the laser device when the xenon concentration inside the laser cavity is within the optimal range.

[0029] Fig.17 The graph shows the change over time of the pulse energy of the laser light output from the laser device when the xenon concentration inside the laser cavity deviates from the optimal range.

[0030] Fig.18 The graph shows the change over time of the pulse energy of the laser light output from the laser device when the xenon concentration inside the laser cavity further deviates from the optimal range.

[0031] Fig.19 is an example of a graph showing the relationship between the ratio Er and the estimated xenon concentration.

[0032] Fig. 20The figure shows the change over time of the voltage of the high voltage pulse applied to the discharge electrode in the laser device when the xenon concentration in the laser cavity is within the optimal range.

[0033] Fig.21 The figure shows the change over time of the voltage of the high voltage pulse applied to the discharge electrode in the laser device when the xenon concentration inside the laser cavity deviates from the optimal range.

[0034] Fig. 22 The figure shows the change over time of the voltage of the high voltage pulse applied to the discharge electrode in the laser device when the xenon concentration inside the laser cavity further deviates from the optimal range.

[0035] Fig.23 is an example of a graph showing the relationship between the ratio HVr and the estimated xenon concentration.

[0036] Fig.24 The structure of the first modified example of the first embodiment is schematically shown.

[0037] Fig.25 The structure of the second modified example of the first embodiment is schematically shown.

[0038] Fig.26 : is a flowchart showing the xenon addition process in the second embodiment.

[0039] Fig. 27 An example of a correction coefficient is shown.

[0040] Fig.28 The configuration of a laser system according to a third embodiment is schematically shown.

[0041] Fig.29 : is a flowchart showing the xenon addition process in the third embodiment.

[0042] Fig.30 : is a flowchart showing the details of updating the correction coefficient.

[0043] Fig.31 An example of the correction coefficients before and after updating is shown.

[0044] Fig.32 The configuration of a laser system according to a fourth embodiment is schematically shown.

[0045] Fig.33 This is a timing chart for explaining a method of measuring the xenon concentration of the inert regeneration gas using a xenon concentration meter.

[0046] Fig.34 This is a flowchart showing the updating process of the correction coefficient in the fourth embodiment.

[0047] Fig.35 The structure of an exposure device connected to a laser device is schematically shown. DETAILED DESCRIPTION

[0048] <Content>

[0049] 1. Comparative Example Laser System

[0050] 1.1 Structure

[0051] 1.1.1 Laser devices 30a and 30b

[0052] 1.1.2 Gas circulation system 50

[0053] 1.2 Action

[0054] 1.2.1 Operation of Laser Devices 30a and 30b

[0055] 1.2.2 Operation of the gas circulation system 50

[0056] 1.3 Issues of Comparative Example

[0057] 2. Laser device 30a having xenon adding device 60 in discharge pipe 24a

[0058] 2.1 Structure

[0059] 2.2 Calculation of exhaust gas Xe concentration C (Xe_vent_n)

[0060] 2.3 Xenon Addition Treatment

[0061] 2.4 Calculation of exhaust gas Xe concentration C(Xe)

[0062] 2.5 Laser device 30a including OSC laser cavity 101 and AMP laser cavity 102

[0063] 2.6 Laser device 30a including xenon addition device 60 arranged outside the housing

[0064] 2.7 Function

[0065] 3. Laser device 30a that calculates xenon addition amount V (Xe_add_cy) by correcting xenon concentration

[0066] 3.1 Xenon Addition Treatment

[0067] 3.2 Function

[0068] 4. Laser device 30a that updates correction coefficient α

[0069] 4.1 Structure

[0070] 4.2 Xenon Addition Treatment

[0071] 4.3 Update of correction coefficient α

[0072] 4.4 Function

[0073] 5. Laser system that updates the correction factor α using the measured xenon concentration C (Xe_mes) of the inert regeneration gas

[0074] 5.1 Structure

[0075] 5.2 Update of correction coefficient α

[0076] 5.3 Function

[0077] 6. Others

[0078] 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.

[0079] 1. Comparative Example Laser System

[0080] 1.1 Structure

[0081] Figure 1 The structure of the laser system of the comparative example is schematically shown. The comparative example disclosed in the present invention is a method that the applicant recognizes that only the applicant knows, and is not a known example acknowledged by the applicant himself. The laser system includes a plurality of laser devices 30a and 30b, and a gas circulation system 50. The gas circulation system 50 is connected to the laser devices 30a and 30b, respectively.

[0082] 1.1.1 Laser devices 30a and 30b

[0083] Reference Figure 1 The structure of the laser device 30a is described below. The structure of the laser device 30b is the same as that of the laser device 30a, except that the suffix of the reference numeral is sometimes replaced from "a" to "b".

[0084] The laser device 30a includes a laser cavity 10, a laser control unit 31, a gas supply device 42, and an exhaust device 43. The laser device 30a is an ArF excimer laser device using a laser gas containing fluorine gas and argon gas.

[0085] The laser device 30a is used together with an exposure device (not shown), for example. The laser light outputted from the laser device 30a enters the exposure device. The exposure device is configured to send a setting signal of a target pulse energy and a light emission trigger signal to a laser control unit 31 included in the laser device 30a.

[0086] The laser control unit 31 is configured to control the gas supply device 42 and the exhaust device 43. The laser control unit 31 is a processing device including a memory (not shown) storing a control program and a CPU (central processing unit) (not shown) executing the control program, and is equivalent to a processor in the present disclosure. The laser control unit 31 is specially configured or programmed to execute various processes included in the present disclosure.

[0087] The laser cavity 10 contains laser gas and is arranged on the optical path of an optical resonator (not shown). The laser cavity 10 contains a pair of discharge electrodes (not shown) inside. The discharge electrodes are connected to a high voltage pulse power supply (not shown).

[0088] The gas supply device 42 includes a portion of the pipe 28a connected to the fluorine-containing gas supply pipe 28 and a portion of the pipe 29a connected to the laser cavity 10. The pipe 28a is connected to the pipe 29a, whereby the fluorine-containing gas supply source F2 can supply the fluorine-containing gas to the laser cavity 10.

[0089] The fluorine-containing gas supply source F2 is a gas cylinder containing fluorine-containing gas. The fluorine-containing gas is, for example, a laser gas mixed with fluorine, argon, and neon. Here, the fluorine concentration of the fluorine-containing gas is adjusted to be higher than the fluorine concentration inside the laser cavity 10. The gas composition ratio of the fluorine-containing gas can be, for example, 1% fluorine, 3.5% argon, and the rest neon. The supply pressure of the laser gas from the fluorine-containing gas supply source F2 to the fluorine-containing gas supply pipe 28 is set to a value of, for example, 5000 hPa or more and 6000 hPa or less by the regulator 44.

[0090] The gas supply device 42 includes a valve F2 - V1 provided in the pipe 28 a . The supply of the fluorine-containing gas from the fluorine-containing gas supply source F2 to the laser cavity 10 via the pipe 29 a is controlled by opening and closing the valve F2 - V1 .

[0091] The gas supply device 42 further includes a portion of the pipe 27a connected to the inert gas pipe 27. The pipe 27a is connected to the pipe 29a, whereby the gas circulation system 50 can supply the inert gas to the laser cavity 10. The inert gas may be an inert new gas supplied from an inert gas supply source B described later, or an inert regeneration gas in which impurities have been reduced in the gas circulation system 50. The inert new gas is equivalent to the new gas in the present disclosure, and the inert regeneration gas is equivalent to the circulation gas in the present disclosure.

[0092] The gas supply device 42 includes a valve B-V1 provided in the pipe 27a. The supply of the inert gas from the gas circulation system 50 to the laser cavity 10 via the pipe 29a is controlled by opening and closing the valve B-V1.

[0093] The gas supply device 42 further includes a xenon-containing gas bottle 72 for adding xenon to the laser cavity 10. The xenon-containing gas bottle 72 is connected to the pipe 29a via a pipe having a valve.

[0094] The xenon-containing gas cylinder 72 is a gas cylinder containing an additional gas having a higher xenon concentration than the xenon concentration in the inert new gas supplied from the inert gas supply source B. The additional gas is a laser gas mixed with xenon in addition to argon and neon. The gas composition ratio of the additional gas may be, for example, 10,000 ppm of xenon, 3.5% of argon, and the remainder of neon.

[0095] The exhaust device 43 includes a portion of the piping 21a connected to the laser cavity 10 and a portion of the piping 22a connected to an exhaust treatment device (not shown) outside the device. The piping 21a is connected to the piping 22a, whereby the exhaust gas discharged from the laser cavity 10 can be discharged to the outside of the device. In the present disclosure, the outside of the device or the outside refers to an area or unit that does not include the laser devices 30a, 30b nor the gas circulation system 50. The unit may be, for example, an exhaust duct (not shown) that can discharge the laser gas from which the fluorine gas has been removed. The exhaust duct may also be connected to a scrubber (not shown).

[0096] The exhaust device 43 includes a valve EX-V1 provided in the pipe 21a. The exhaust gas from the laser cavity 10 to the pipe 22a or 24a is controlled by opening and closing the valve EX-V1.

[0097] The exhaust device 43 includes a valve EX-V2, a fluorine trap 45, and an exhaust pump 46, all of which are provided in the pipe 22a. The valve EX-V2, the fluorine trap 45, and the exhaust pump 46 are arranged in order from the laser cavity 10 side. The exhaust gas after passing through the valve EX-V1 toward the outside of the device is controlled by opening and closing the valve EX-V2.

[0098] The fluorine trap 45 may have the same structure as the fluorine trap 61 described later. Alternatively, since it is not assumed that the exhaust gas after passing through the fluorine trap 45 is reused as laser gas, the fluorine trap 45 may have a structure that generates other derivatives as fluorine is removed.

[0099] The exhaust pump 46 is configured to forcibly exhaust the laser gas in the laser cavity 10 to a pressure lower than the atmospheric pressure when the valves EX-V1 and EX-V2 are opened.

[0100] The exhaust device 43 also includes a part of the exhaust pipe 24a. The exhaust pipe 24a is connected between the confluence pipe 24 of the gas circulation system 50 and the connection part of the pipe 21a and the pipe 22a. The exhaust pipe 24a is connected to the connection part of the pipe 21a and the pipe 22a, thereby being able to supply the exhaust gas exhausted from the laser cavity 10 to the gas circulation system 50. The exhaust device 43 includes a valve C-V1 provided on the exhaust pipe 24a. The supply of the exhaust gas after passing through the valve EX-V1 to the gas circulation system 50 is controlled by the opening and closing of the valve C-V1. The opening and closing of the valves F2-V1, B-V1, EX-V1, EX-V2 and C-V1 and the operation of the exhaust pump 46 are controlled by the laser control unit 31.

[0101] 1.1.2 Gas circulation system 50

[0102] The gas circulation system 50 includes a gas circulation system control unit 51, the junction pipe 24, and a part of the inert gas pipe 27. The junction pipe 24 is connected to the exhaust pipes 24a and 24b. The inert gas pipe 27 is connected to the pipes 27a and 27b.

[0103] In the gas circulation system 50 , a fluorine trap 61 , a filter 63 , a booster pump 65 , and a booster tank 66 are arranged in this order on the junction pipe 24 from the exhaust device 43 side.

[0104] The gas circulation system 50 also includes a portion of an inert new gas piping 26 connected to an inert gas supply source B. The inert new gas piping 26 is connected to the connecting portion of the confluence piping 24 and the inert gas piping 27. The inert gas supply source B is, for example, a gas cylinder containing an inert gas, which contains a small amount of xenon gas in addition to argon and neon. Here, the xenon concentration of the inert gas supply source B is adjusted to a value slightly higher than the target xenon concentration in the laser cavity 10. The gas composition ratio of the inert gas supply source B can be, for example, 10 ppm of xenon, 3.5% of argon, and the rest of neon. In the present disclosure, the inert gas supplied from the inert gas supply source B and not yet reaching the laser cavity 10 is sometimes referred to as an inert new gas to distinguish it from the inert regeneration gas supplied from the confluence piping 24. The supply pressure of the inert new gas from the inert gas supply source B to the inert new gas pipe 26 is set to a value of, for example, 5000 hPa to 6000 hPa by the regulator 64 . The gas circulation system 50 includes a valve B-V2 provided in the inert new gas pipe 26 .

[0105] The fluorine trap 61 has a treatment agent for capturing fluorine gas and fluorine compounds contained in the exhaust gas discharged from the laser cavity 10. The treatment agent for capturing fluorine gas and fluorine compounds includes, for example, calcium hydroxide and zeolite. In this case, fluorine gas and calcium hydroxide react to generate calcium fluoride, water vapor and oxygen. Calcium fluoride and water vapor are adsorbed by zeolite. Oxygen is captured by an oxygen trap not shown in the figure on the downstream side of the fluorine trap 61.

[0106] The structure of the fluorine trap 61 is not limited thereto, and it is sufficient to remove at least fluorine gas and fluorine compounds.

[0107] The filter 63 includes a mechanical filter that captures particles contained in the exhaust gas that has passed through the fluorine trap 61 , an impurity gas trap that reduces impurity gases contained in the exhaust gas, and the like.

[0108] The booster pump 65 is a pump that boosts the exhaust gas that has passed through the filter 63 and supplies it to the booster tank 66. The booster pump 65 is composed of, for example, a diaphragm type or bellows type pump in which oil is less likely to be mixed into the exhaust gas.

[0109] The boost tank 66 is a container for storing the inert regeneration gas that has passed through the boost pump 65. The boost tank 66 is provided with a boost pressure sensor P3.

[0110] The gas circulation system control unit 51 is configured to send and receive signals with the laser control unit 31 and control the various components of the gas circulation system 50. The gas circulation system control unit 51 is a processing device including a memory (not shown) storing a control program and a CPU (not shown) executing the control program, and corresponds to the processor in the present disclosure. The gas circulation system control unit 51 is specially configured or programmed to execute various processes included in the present disclosure.

[0111] 1.2 Action

[0112] 1.2.1 Operation of Laser Devices 30a and 30b

[0113] In each of the laser devices 30a and 30b, the laser control unit 31 receives a setting signal of a target pulse energy and a light emission trigger signal from the exposure device. The laser control unit 31 sends a control signal and a trigger signal to the high voltage pulse power supply according to the setting signal of the target pulse energy and the light emission trigger signal received from the exposure device.

[0114] The high voltage pulse power supply generates a pulsed high voltage according to the control signal and trigger signal received from the laser control unit 31. The high voltage is applied to a pair of discharge electrodes. Thus, a discharge is generated between the discharge electrodes. The laser gas in the laser cavity 10 is excited by the energy of the discharge and transitions to a high energy level. Then, when the excited laser gas transitions to a low energy level, light of a wavelength corresponding to the energy level difference is emitted.

[0115] The light generated in the laser cavity 10 reciprocates in the optical resonator, and is amplified each time it passes through the discharge space between the discharge electrodes, thereby performing laser oscillation. The light amplified in this way is output as laser light from one mirror of the optical resonator.

[0116] 1.2.2 Operation of the gas circulation system 50

[0117] The gas circulation system 50 reduces impurities in the exhaust gas exhausted from the laser devices 30a and 30b. The gas circulation system 50 supplies the inactive regeneration gas with reduced impurities to the laser devices 30a and 30b.

[0118] The supply of the inert regeneration gas from the junction pipe 24 to the inert gas pipe 27 is controlled by opening and closing the valve C-V2.

[0119] The supply of the inert new gas from the inert gas supply source B to the inert gas pipe 27 is controlled by the opening and closing of the valve B-V2. The opening and closing of the valves C-V2 and B-V2 are controlled by the gas circulation system control unit 51.

[0120] The gas circulation system control unit 51 selects whether to close the valve C-V2 and open the valve B-V2, or to close the valve B-V2 and open the valve C-V2, and controls these valves.

[0121] Figure 2 Examples of fluorine concentration C (F2) and xenon concentration C (Xe) of various gases in comparative examples are shown. Figure 2 In the embodiment, as the fluorine-containing gas supplied from the fluorine-containing gas supply source F2, a mixed gas of fluorine, argon, and neon with a fluorine concentration C (F2) of 1% and a xenon concentration C (Xe) of 0 ppm is used. As the inert new gas supplied from the inert gas supply source B, a mixed gas of argon, neon, and xenon with a fluorine concentration C (F2) of 0% and a xenon concentration C (Xe) of 10 ppm is used. The reason for setting the xenon concentration C (Xe) of the fluorine-containing gas to 0 ppm and the fluorine concentration C (F2) of the inert new gas to 0% is to suppress the reaction between fluorine and xenon in the fluorine-containing gas supply source F2 and the inert gas supply source B.

[0122] When the fluorine concentration C (F2) of the gas inside the laser cavity 10 is set to 0.1% and the xenon concentration C (Xe) is set to 9 ppm, the mixing ratio of the fluorine-containing gas and the inert new gas can be set to 1:9. When the exhaust gas discharged from the laser cavity 10 is introduced into the gas circulation system 50 for regeneration, the exhaust gas passes through the fluorine trap 61, thereby the fluorine concentration C (F2) thereof becomes 0%. The xenon concentration C (Xe) is still 9 ppm.

[0123] The inactive regeneration gas after passing through the gas circulation system 50 does not contain fluorine, so when the inactive regeneration gas is returned to the laser cavity 10, new fluorine-containing gas is also supplied to the laser cavity 10 together with the inactive regeneration gas. Here, if xenon is not added to the inactive regeneration gas and it is returned to the laser cavity 10, the xenon concentration C (Xe) of the gas inside the laser cavity 10 becomes a value lower than 9 ppm due to mixing with the fluorine-containing gas. The more repeatedly the regeneration of the exhaust gas is performed, the lower the xenon concentration C (Xe) of the gas inside the laser cavity 10. Therefore, xenon is added to the inactive regeneration gas. The amount of xenon added is adjusted so that the xenon concentration C (Xe) of the inactive regeneration gas returns to 10 ppm, thereby making it possible to make the gas composition of the inactive regeneration gas approximately the same as the gas composition of the inactive new gas.

[0124] 1.3 Issues of Comparative Example

[0125] Figure 3 The following is an example of the fluorine concentration C (F2) and xenon concentration C (Xe) of various gases in a case where the gas circulation system 50 is connected to a plurality of laser cavities 10 in a comparative example. Figure 2 , the case where the fluorine concentration C (F2) of the gas inside the laser cavity 10 is set to 0.1% and the xenon concentration C (Xe) is set to 9 ppm is described, but these concentrations are controlled to different values ​​according to the states of the laser devices 30a and 30b and the required characteristics. For example, when it is necessary to increase the fluorine concentration C (F2) of the gas inside one laser cavity 10, more fluorine-containing gas can be supplied to the laser cavity 10. As a result, the mixing ratio of the inactive new gas or the inactive regeneration gas to the fluorine-containing gas is reduced, and therefore, the xenon concentration C (Xe) inside the laser cavity 10 becomes lower.

[0126] In this way, regarding the exhaust gas discharged from the plurality of laser cavities 10, not only the fluorine concentration C (F2) is different from each other, but also the xenon concentration C (Xe) is sometimes different from each other. When the exhaust gas is introduced into the gas circulation system 50, the exhaust gas passes through the fluorine trap 61, whereby the fluorine concentration C (F2) becomes 0%. However, the xenon concentration C (Xe) is different depending on which laser cavity 10 the exhaust gas is discharged from. When the xenon concentration C (Xe) of the exhaust gas cannot be determined, the amount of xenon added cannot be determined, and it is difficult to return the xenon concentration C (Xe) of the inactive regeneration gas to 10 ppm.

[0127] 2. Laser device 30a having xenon adding device 60 in discharge pipe 24a

[0128] 2.1 Structure

[0129] Figure 4The structure of the laser system of the first embodiment is schematically shown. In the first embodiment, the gas supply device 42 may not include the xenon gas bottle 72. Instead, the exhaust pipes 24a and 24b are provided with a xenon addition device 60. The xenon addition device 60 provided in the exhaust pipe 24b is the same as the xenon addition device 60 provided in the exhaust pipe 24a.

[0130] The xenon adding device 60 includes a xenon-containing gas bottle 62 for adding xenon to the exhaust gas. The xenon-containing gas bottle 62 is connected to the exhaust pipe 24a via a pipe having a valve Xe-V1. The xenon-containing gas bottle 62 is the same as the xenon-containing gas bottle 72 described in the comparative example.

[0131] A regulator (not shown) for making the secondary pressure near the valve Xe-V1 constant is preferably arranged between the xenon gas cylinder 62 and the valve Xe-V1. A throttle orifice for limiting the flow rate of the added gas is preferably arranged between the regulator and the valve Xe-V1.

[0132] The xenon adding device 60 is arranged between the valve EX-V1 and the junction point leading to the junction pipe 24 .

[0133] By arranging the xenon adding device 60 at the downstream side of the exhaust gas from the valve EX-V1, the gas pressure of the exhaust gas to which xenon is added becomes lower than the gas pressure of the laser cavity 10. Therefore, even when the remaining amount of the xenon gas bottle 62 decreases and the bottle pressure decreases, the added gas can be supplied.

[0134] By arranging the xenon adding device 60 upstream of the exhaust gas from the merging point toward the merging pipe 24, a desired amount of xenon can be added to the exhaust gas from the laser device 30a before merging with the exhaust gas from the other laser device 30b.

[0135] The addition of xenon from the xenon-containing gas bottle 62 to the exhaust gas is controlled by the opening and closing of the valve Xe-V1. The opening and closing of the valve Xe-V1 is controlled by the laser control unit 31.

[0136] It is preferable to arrange the fluorine trap 61 in the exhaust pipe 24a between the laser cavity 10 and the xenon adding device 60. The fluorine trap 61 may not be arranged in the gas circulation system 50.

[0137] In the fluorine trap 61, a part of the xenon contained in the exhaust gas is sometimes removed. When xenon is added to the exhaust gas before passing through the fluorine trap 61, it is necessary to add additional xenon in consideration of the amount of xenon removed in the fluorine trap 61. In contrast, by arranging the xenon adding device 60 at a position downstream of the fluorine trap 61 and adding xenon to the exhaust gas after passing through the fluorine trap 61, the amount of xenon added can be suppressed.

[0138] The filter 63 may be arranged at the exhaust pipe 24a of the laser device 30a, or may be arranged at the confluence pipe 24 of the gas circulation system 50 as in the comparative example. The filter 63 is preferably arranged at a position downstream of the xenon addition device 60. The filter 63 is made of a porous material, and a plurality of pores contained in the porous material constitute a plurality of gas flow path branch points and confluence points. The exhaust gas and the added gas pass through the filter 63, thereby repeatedly branching and confluence, thereby promoting the mixing of the exhaust gas and the added gas.

[0139] 2.2 Calculation of exhaust gas Xe concentration C (Xe_vent_n)

[0140] In order to add an appropriate amount of xenon to the exhaust gas discharged from the laser cavity 10, it is preferable to determine the xenon concentration of the exhaust gas. Figure 5 to Figure 12 The calculation of the exhaust gas Xe concentration C (Xe_vent_n) will be described. The exhaust gas Xe concentration C (Xe_vent_n) is an example of calculating the xenon concentration in the present disclosure.

[0141] Figure 5 1 is a flowchart schematically showing gas control in the laser device 30 a .

[0142] In the initial gas supply of S11, fluorine-containing gas and inert gas are supplied to the laser cavity 10 exhausted to below atmospheric pressure. Thus, the gas composition inside the laser cavity 10 is initially adjusted, and the laser device 30a can output laser light.

[0143] When laser light is output, impurities are generated inside the laser cavity 10. As the impurities increase over time, laser performance may deteriorate. Therefore, part of the gas inside the laser cavity 10 is replaced with a clean gas. This is called gas flushing.

[0144] In S12 , the value of a counter n indicating the number of gas flushing times is set to 1.

[0145] In S13, the nth gas flushing is performed.

[0146] In S14, the value of counter n is updated by adding 1. After S14, the process returns to S13, and the value of counter n is updated in S14 every time the n-th gas flushing is performed.

[0147] The exhaust gas Xe concentration C (Xe_vent_n) is a xenon concentration calculated based on the entire history of the supply and exhaust amounts of the initial gas supply and the first to nth gas purges as described above.

[0148] Figure 6The operation of the initial gas supply is schematically shown. In the initial gas supply, the supply amount V(F_ini) of the fluorine-containing gas, the supply amount V(Ar_ini) of the inert gas, and the xenon concentration C(Xe_cy) of the inert gas are all provided based on the control data of the gas control in the laser device 30a. Assuming that the xenon concentration of the inert regeneration gas is adjusted to be the same as the xenon concentration of the inert new gas, Figure 6 to Figure 12 In the process, no distinction is made between inactive regeneration gas and inactive new gas.

[0149] Figure 7 Results for the initial gas supply are shown.

[0150] As described below, the intra-chamber gas amount V(CHB_ini) can be calculated by adding the supply amount V(F_ini) of the fluorine-containing gas and the supply amount V(Ar_ini) of the inert gas.

[0151] V(CHB_ini)=V(Ar_ini)+V(F_ini)

[0152] As described below, the amount of Xe V(Xe_ini) in the chamber can be calculated by multiplying the supply amount V(Ar_ini) of the inert gas by the xenon concentration C(Xe_cy) of the inert gas.

[0153] V(Xe_ini)=V(Ar_ini)×C(Xe_cy)

[0154] As described below, the intra-chamber Xe concentration C(Xe_ini) can be calculated by dividing the intra-chamber Xe amount V(Xe_ini) by the intra-chamber gas amount V(CHB_ini).

[0155] C(Xe_ini)=V(Xe_ini) / V(CHB_ini)

[0156] Figure 8 The operation of the n-th gas flushing is schematically shown. The gas flushing includes gas exhaust and gas supply, and a part of the gas inside the laser cavity 10 is replaced. In the n-th gas flushing, the supply amount V(F_n) of the fluorine-containing gas, the supply amount V(Ar_n) of the inert gas, the xenon concentration C(Xe_cy) of the inert gas, and the exhaust gas amount V(vent_n) are all provided according to the control data of the gas control in the laser device 30a.

[0157] Fig. 9 The results of the gas discharge in the first gas flushing are shown. The amount of gas in the chamber before the gas discharge in the first gas flushing, the amount of Xe in the chamber, and the Xe concentration in the chamber are provided based on the results of the initial gas supply (refer to Figure 7 ).

[0158] The exhaust gas volume V(vent_1) in the first gas flushing is provided as the exhaust gas volume V(vent_n) when the value of the counter n is 1 (refer to Figure 8 ).

[0159] The exhaust gas xenon concentration C(Xe_vent_1) is the same as the chamber Xe concentration C(Xe_ini) before the gas is exhausted.

[0160] The exhaust gas Xe amount V(Xe_vent_1) can be calculated by multiplying the exhaust gas amount V(vent_1) by the exhaust gas xenon concentration C(Xe_vent_1) as follows.

[0161] V(Xe_vent_1)=V(vent_1)×C(Xe_vent_1)

[0162] Fig.10 The results of gas supply in the first gas flushing are shown.

[0163] The fluorine-containing gas supply amount V(F_1) and the inert gas supply amount V(Ar_1) in the first gas flushing are provided as the fluorine-containing gas supply amount V(F_n) and the inert gas supply amount V(Ar_n) when the value of the counter n is 1 (refer to Figure 8 ).

[0164] As described below, the chamber gas volume V(CHB_1) can be calculated by adding the supply volume V(F_1) of the fluorine-containing gas and the supply volume V(Ar_1) of the inert gas to the value obtained by subtracting the exhaust gas volume V(vent_1) from the chamber gas volume before gas exhaust.

[0165] V(CHB_1)=V(CHB_ini)-V(vent_1)+V(Ar_1)+V(F_1)

[0166] As described below, the amount of Xe in the chamber V(Xe_1) can be calculated by subtracting the amount of Xe in the exhausted gas V(Xe_vent_1) from the amount of Xe in the chamber before the gas exhaust and adding the value obtained by multiplying the supply amount of inert gas V(Ar_1) by the xenon concentration C(Xe_cy) of the inert gas.

[0167] V(Xe_1)=V(Xe_ini)-V(Xe_vent_1)+V(Ar_1)×C(Xe_cy)

[0168] The intra-cavity Xe concentration C(Xe_1) can be calculated by dividing the intra-cavity Xe amount V(Xe_1) by the intra-cavity gas amount V(CHB_1) as follows.

[0169] C(Xe_1)=V(Xe_1) / V(CHB_1)

[0170] Fig.11 shows the result of gas discharge in the nth gas flushing, Fig.12 The result of the gas supply in the n-th gas flushing is shown. The result of the n-th gas flushing can be obtained using the result of the n-1-th gas flushing. That is, the result of the second gas flushing can be obtained using the result of the first gas flushing, and then, if n is increased by one, the result of any n-th gas flushing can be obtained.

[0171] The specific calculation formula will be Fig. 9 and Fig.10 In the parameter indicating the initial gas supply, "_ini" is replaced by "_n-1", and "_1" indicating the parameter of the first gas flushing is replaced by "_n". Fig. 9 and Fig.10 The same, therefore the description is omitted.

[0172] Through the above calculation, the exhaust gas Xe concentration C (Xe_vent_n) in any n-th gas flushing can be calculated (refer to Fig.11 ).

[0173] 2.3 Xenon Addition Treatment

[0174] Fig.13 : is a flowchart showing the xenon addition process in the first embodiment. Fig.13 The processing shown is performed by the laser control unit 31 .

[0175] In S21, the laser control unit 31 refers to Figure 6 to Figure 12 The described method calculates the exhaust gas Xe concentration C (Xe_vent_n).

[0176] In S26 , the laser control unit 31 calculates the xenon concentration difference C (Xe_add_n) between the xenon concentration C (Xe_cy) of the inert new gas supplied from the inert gas supply source B and the exhaust gas Xe concentration C (Xe_vent_n) of the exhaust gas exhausted from the laser cavity 10 by the following equation.

[0177] C(Xe_add_n)=C(Xe_cy)-C(Xe_vent_n)

[0178] In S27 , the laser control unit 31 calculates the xenon amount V(Xe_add_n) of the added gas by the following equation so that the xenon concentration of the exhaust gas of the exhaust gas amount V(vent_n) approaches the xenon concentration C(Xe_cy) of the inert new gas.

[0179] V(Xe_add_n)=V(vent_n)×C(Xe_add_n)

[0180] In S28, the laser control unit 31 controls the xenon adding device 60 to add an additive gas containing an amount of xenon V (Xe_add_n) of the additive gas to the exhaust gas. Fig.14 and Fig.15 Provide explanation.

[0181] After S28, the laser control unit 31 ends the processing of this flowchart.

[0182] The laser control unit 31 may perform the process of S28 after converting the xenon amount V (Xe_add_n) of the additive gas into the addition amount V (Xe_add_cy) of the additive gas by the following equation.

[0183] V(Xe_add_cy)=V(Xe_add_n)×C(Xe_add_cy)

[0184] Here, C(Xe_add_cy) is the xenon gas concentration in the xenon gas bottle 62 .

[0185] Fig.14 1 is a flowchart showing the details of the control of the xenon adding device 60 . Fig.14 The processing shown is equivalent to Fig.13 In the flowchart of the present disclosure, "Y" at a branch point indicates a destination when the determination is "Yes", and "N" indicates a destination when the determination is "No".

[0186] In S281, the laser control unit 31 opens and closes the valve C-V1 of the exhaust device 43 for a predetermined time. The predetermined time is the time for the exhaust gas of less than half, preferably less than one-fifth, of the exhaust gas volume V(vent_n) to pass through the valve C-V1 by one opening and closing of the valve C-V1, and is, for example, about several seconds.

[0187] In S282, the laser control unit 31 opens and closes the valve Xe-V1 of the xenon addition device 60 for a predetermined time. The predetermined time is the time for less than half, preferably less than one-fifth, of the addition amount V (Xe_add_cy) of the addition gas to pass through the valve Xe-V1 through one opening and closing of the valve Xe-V1, and is, for example, about 1 second. Preferably, the ratio of the amount of exhaust gas passing through the valve C-V1 through one opening and closing of the valve C-V1 to the amount of addition gas passing through the valve Xe-V1 through one opening and closing of the valve Xe-V1 is equal to the mixing ratio of the exhaust gas and the addition gas.

[0188] In S283, the laser control unit 31 determines whether the exhaust gas amount V(vent_n) of the exhaust gas has been exhausted. If the exhaust gas amount V(vent_n) of the exhaust gas has been exhausted (S283: Yes), the laser control unit 31 ends the processing of this flowchart and returns to Fig.13 When the exhaust gas amount V(vent_n) of the exhaust gas has not been exhausted (S283: No), the laser control unit 31 returns the process to S281.

[0189] Fig.15 yes Fig.14 A timing chart of xenon addition in the control of the xenon addition device 60 is shown. Fig.15 The horizontal axis represents time T, and the vertical axis represents the gas flow rate V / T per unit time in the valve C-V1 or Xe-V1.

[0190] like Fig.14 and Fig.15 As shown, by alternately opening valve C-V1 and valve Xe-V1 at a predetermined time, exhaust gas and added gas can be mixed in the pipe. Valve C-V1 corresponds to the third valve in the present disclosure.

[0191] 2.4 Calculation of exhaust gas Xe concentration C(Xe)

[0192] Reference Figure 16 to Figure 19 A first method for calculating and estimating the xenon concentration C (Xe_est) based on laser performance is described below. Fig.13 S21 can also be used instead of reference Figure 6 to Figure 12 The exhaust gas Xe concentration C (Xe_vent_n) described above uses the estimated xenon concentration C (Xe_est) calculated by the first method. The estimated xenon concentration C (Xe_est) is an example of the calculated xenon concentration in the present disclosure.

[0193] Figure 16 to Figure 18 The following is an example of how the pulse energy E of the laser light outputted from the laser device 30a changes with time T. The laser device 30a outputs pulsed laser light at a predetermined repetition frequency within a predetermined time. At this time, the stability of the pulse energy E within the predetermined time may change depending on the state of the laser device 30a.

[0194] Fig.16 The figure shows the pulse energy E when the xenon concentration Ct in the laser cavity 10 is within the optimal range. The ratio Er of the minimum value Emin to the maximum value Emax of the pulse energy E within the predetermined time is close to 1, and the pulse energy E is stable.

[0195] Fig.17The pulse energy E is shown when the xenon concentration C1 inside the laser cavity 10 deviates from the optimal range. The ratio Er of the minimum value Emin to the maximum value Emax of the pulse energy E within the predetermined time becomes smaller.

[0196] Fig.18 The pulse energy E is shown when the xenon concentration C2 in the laser cavity 10 further deviates from the optimal range. The ratio Er of the minimum value Emin to the maximum value Emax of the pulse energy E within the predetermined time further decreases.

[0197] Fig.19 is an example of a graph showing the relationship between the ratio Er and the estimated xenon concentration C (Xe_est). Fig.19 As shown, when there is a certain relationship between the ratio Er and the xenon concentration inside the laser cavity 10, the estimated xenon concentration C (Xe_est) can be calculated based on the relationship.

[0198] Reference Figure 20 to Figure 23 A second method for calculating and estimating the xenon concentration C (Xe_est) based on laser performance is described below. Fig.13 S21 can also be used instead of reference Figure 6 to Figure 12 Instead of the exhaust gas Xe concentration C (Xe_vent_n) described above, the estimated xenon concentration C (Xe_est) calculated by the second method is used.

[0199] Figure 20 to Figure 22 An example of how the voltage HV of the high voltage pulse applied to the discharge electrode in the laser device 30a changes with time T is shown. In the laser device 30a, the voltage HV is sometimes feedback-controlled so that the laser pulse energy E is constant. At this time, the stability of the voltage HV within the above-mentioned predetermined time may change depending on the state of the laser device 30a.

[0200] Fig. 20 The voltage HV is shown when the xenon concentration Ct in the laser cavity 10 is within the optimal range. The ratio HVr of the minimum value HVmin to the maximum value HVmax of the voltage HV within the predetermined time is close to 1, and the voltage HV is stable.

[0201] Fig.21 The voltage HV is shown when the xenon concentration C1 inside the laser cavity 10 deviates from the optimal range. The ratio HVr of the minimum value HVmin to the maximum value HVmax of the voltage HV within the predetermined time becomes smaller.

[0202] Fig. 22The voltage HV is shown when the xenon concentration C2 in the laser cavity 10 further deviates from the optimal range. The ratio HVr of the minimum value HVmin to the maximum value HVmax of the voltage HV within the predetermined time further decreases.

[0203] Fig.23 ] is an example of a graph showing the relationship between the ratio HVr and the estimated xenon concentration C(Xe_est). Fig.23 As shown, when there is a certain relationship between the ratio HVr and the xenon concentration inside the laser cavity 10, the estimated xenon concentration C (Xe_est) can be calculated based on the relationship.

[0204] 2.5 Laser device 30a including OSC laser cavity 101 and AMP laser cavity 102

[0205] Fig.24 The structure of the first modified example of the first embodiment is schematically shown. Fig.24 In the figure, only one laser device 30a is shown, and the illustration of the other laser device 30b is omitted. The laser device 30a includes an OSC laser cavity 101 and an AMP laser cavity 102. The OSC laser cavity 101 is a laser cavity for outputting a first laser, and the first laser is incident on the AMP laser cavity 102. The AMP laser cavity 102 is a laser cavity for amplifying the first laser and outputting a second laser. Laser gas is supplied to the OSC laser cavity 101 and the AMP laser cavity 102, respectively, and the xenon gas concentrations inside them are sometimes different from each other.

[0206] The pipe 29a branches before the OSC laser cavity 101 and the AMP laser cavity 102 to supply laser gas to each of them.

[0207] The OSC laser cavity 101 and the AMP laser cavity 102 are respectively connected to the first exhaust path 211 and the second exhaust path 212. The first exhaust path 211 and the second exhaust path 212 are connected to the pipe 21a, and further connected to the exhaust pipe 24a.

[0208] A first valve EX-V11 and a second valve EX-V12 are respectively disposed in the first discharge path 211 and the second discharge path 212. The first valve EX-V11 and the second valve EX-V12 are controlled by the laser control unit 31 so that one is closed and the other is opened.

[0209] In the pipe 21a and the exhaust pipe 24a, exhaust gases having different xenon concentrations may flow when the first valve EX-V11 is opened and when the second valve EX-V12 is opened. Therefore, the laser control unit 31 determines whether the exhaust gas from the OSC laser cavity 101 or the exhaust gas from the AMP laser cavity 102 flows in the exhaust pipe 24a based on the control information of the first valve EX-V11 and the second valve EX-V12. Based on the result of the determination, the xenon addition device 60 is controlled so that the additive gas corresponding to the Xe concentration of each exhaust gas is added to the exhaust gas.

[0210] 2.6 Laser device 30a including xenon addition device 60 arranged outside the housing

[0211] Fig.25 The structure of the second modified example of the first embodiment is schematically shown. Fig.25 In the laser device 30a shown, the laser cavity 10, the gas supply device 42 and the exhaust device 43 are arranged inside a laser housing 3a. The fluorine trap 61, the xenon addition device 60 and the filter 63 included in the laser device 30a are all arranged outside the laser housing 3a.

[0212] According to the second modification, when the fluorine trap 61 , the xenon addition device 60 , and the filter 63 are added to the laser device 30 a which does not include the fluorine trap 61 , the xenon addition device 60 , and the filter 63 , it is not necessary to significantly modify the laser housing 3 a .

[0213] 2.7 Function

[0214] (1) According to the first embodiment, the laser device 30 a includes the laser cavity 10 , the exhaust pipe 24 a , the fluorine trap 61 , and the xenon adding device 60 .

[0215] The laser cavity 10 is connected to a gas circulation system 50, which includes a confluence pipe 24. Exhaust gases discharged from multiple laser devices 30a and 30b including the laser device 30a converge in the confluence pipe 24. The gas circulation system 50 selects one of the inactive new gas containing xenon and the inactive regeneration gas flowing in the confluence pipe 24 and supplies it to the multiple laser devices 30a and 30b.

[0216] The exhaust pipe 24 a is connected between the laser cavity 10 and the joining pipe 24 , and is configured to allow exhaust gas exhausted from the laser cavity 10 to flow toward the joining pipe 24 .

[0217] The fluorine collector 61 is connected to a middle of the exhaust pipe 24 a and removes at least fluorine in the exhaust gas exhausted from the laser cavity 10 .

[0218] The xenon adding device 60 is connected to the middle of the exhaust pipe 24 a and adds an additive gas having a higher xenon concentration than the inert new gas to the exhaust gas exhausted from the laser cavity 10 .

[0219] Thus, even if the xenon concentration of the exhaust gas differs for each laser cavity 10 , a deficient amount of xenon can be added according to the xenon concentration, so that the xenon concentration of the inert regeneration gas can be brought close to a desired xenon concentration.

[0220] (2) According to the first embodiment, the xenon adding device 60 is located on the downstream side of the exhaust gas exhausted from the laser cavity 10 relative to the fluorine trap 61 .

[0221] Although a part of xenon may be removed in the fluorine trap 61 , by adding xenon after passing through the fluorine trap 61 , the amount of xenon added can be suppressed.

[0222] (3) According to the first modification of the first embodiment, the laser device 30a includes the OSC laser cavity 101 and the AMP laser cavity 102, which are respectively connected to the exhaust pipe 24a via the first exhaust path 211 and the second exhaust path 212. The first valve EX-V11 and the second valve EX-V12 are respectively arranged in the first exhaust path 211 and the second exhaust path 212, and the first valve EX-V11 and the second valve EX-V12 are controlled so that one valve is closed and the other valve is opened.

[0223] Thus, in the laser device 30a including two laser cavities, the first valve EX-V11 and the second valve EX-V12 are controlled so that one of them performs exhaust and the exhaust pipe 24a is shared, thereby making it possible to share the xenon adding device 60.

[0224] (4) According to the first embodiment, the laser device 30a includes the laser control unit 31 that calculates the addition amount V(Xe_add_cy) of the additional gas based on the xenon concentration C(Xe_cy) of the inert new gas.

[0225] Thus, the amount of additional gas V(Xe_add_cy) is calculated based on the xenon concentration of the inert new gas, so there is no need to distinguish the calculation of the xenon concentration in the laser cavity 10 according to whether the circulating gas or the new gas is supplied to the laser cavity 10 from the gas circulation system 50.

[0226] (5) According to the first embodiment, the valve C-V1 is disposed in the exhaust pipe 24a between the laser cavity 10 and the xenon adding device 60. The laser control unit 31 controls the valve C-V1 and the xenon adding device 60 so as to alternately open and close the valve C-V1 and to cause the xenon adding device 60 to add an additive gas of less than half the additive amount V(Xe_add_cy) to the exhaust gas exhausted from the laser cavity 10.

[0227] Thereby, the exhaust gas and the added gas can be mixed in the pipe.

[0228] (6) According to the first embodiment, the laser control unit 31 calculates the estimated xenon concentration C (Xe_est) of the exhaust gas discharged from the laser cavity 10 based on the laser performance of the laser device 30a, and calculates the addition amount V (Xe_add_cy) based on the xenon concentration C (Xe_cy) of the inert new gas and the estimated xenon concentration C (Xe_est).

[0229] Thus, by using the data on laser performance, the xenon concentration can be calculated excluding xenon lost due to chemical reaction with fluorine or the like.

[0230] (7) According to the first embodiment, the laser control unit 31 calculates the exhaust gas Xe concentration C (Xe_vent_n) exhausted from the laser cavity 10, and calculates the additive amount V (Xe_add_cy) based on the xenon concentration C (Xe_cy) of the inert new gas and the exhaust gas Xe concentration C (Xe_vent_n).

[0231] Thus, by using a calculated value as the xenon concentration of the exhaust gas instead of the measurement result by the gas analyzer, the manufacturing cost of the laser device 30 a can be reduced.

[0232] (8) According to the first embodiment, the laser cavity 10 is connected to the fluorine-containing gas supply source F2. The laser control unit 31 calculates the exhaust gas Xe concentration C (Xe_vent_n) based on the supply amounts V (F_ini) and V (F_n) of the fluorine-containing gas supplied from the fluorine-containing gas supply source F2 to the laser cavity 10, and the supply amounts V (Ar_ini) and V (Ar_n) of one of the inactive new gas and the inactive regeneration gas supplied from the gas circulation system 50 to the laser cavity 10.

[0233] Thus, by using the data of the gas supply amount, the xenon concentration C (Xe_vent_n) in the laser cavity can be accurately calculated.

[0234] Regarding other aspects, the first embodiment is the same as the comparative example.

[0235] 3. Laser device 30a that calculates xenon addition amount V (Xe_add_cy) by correcting xenon concentration

[0236] 3.1 Xenon addition treatment

[0237] Fig.26: is a flowchart showing the xenon addition process in the second embodiment. In the first embodiment, an example of calculating the exhaust gas Xe concentration C (Xe_vent_n) based on the data of the entire history of the supply and exhaust of the laser gas is shown, but the concentration of xenon actually contained in the exhaust gas may be lower than the exhaust gas Xe concentration C (Xe_vent_n) due to some important reason. For example, sometimes xenon and fluorine react chemically to become xenon fluoride, which is removed in the fluorine trap 61. Therefore, a correction coefficient α is calculated to estimate a larger difference between the target gas Xe concentration C (Xe_target) and the exhaust gas Xe concentration C (Xe_vent_n), and the target gas Xe concentration C (Xe_target) is obtained by adding the additive gas. The structure of the laser system in the second embodiment is the same as that in the first embodiment.

[0238] S21 processing and Fig.13 same.

[0239] In S22a, the laser control unit 31 calculates the correction coefficient α. The calculation of the correction coefficient α refers to Fig. 27 Provide explanation.

[0240] In S25a, the laser control unit 31 calculates the target gas Xe concentration C (Xe_target) by the following equation.

[0241] C(Xe_target)=C(Xe_cy)×α

[0242] In S26a, the laser control unit 31 calculates the xenon concentration difference C (Xe_add) between the target gas and the exhaust gas by the following equation.

[0243] C(Xe_add)=C(Xe_target)-C(Xe_vent_n)

[0244] In S27a, the laser control unit 31 calculates the xenon amount V (Xe_add) of the added gas by the following equation so that the xenon concentration of the exhaust gas approaches the target gas Xe concentration C (Xe_target).

[0245] V(Xe_add)=V(vent_n)×C(Xe_add)

[0246] In S28, the laser control unit 31 controls the xenon adding device 60 to add xenon additive gas containing an amount of xenon V (Xe_add) to the exhaust gas. Fig.13 and Fig.14 same.

[0247] After S28, the laser control unit 31 ends the processing of this flowchart.

[0248] Fig. 27 An example of the correction coefficient α is shown. The correction coefficient α is set for each laser cavity 10. The correction coefficient α may also be determined based on the number of discharge pulses pls from when the laser cavity 10 is new. For example, the correction coefficient α may also be stored in a memory (not shown) of the laser control unit 31 as table data corresponding to the number of discharge pulses pls. Alternatively, the correction coefficient α may also be stored in the memory as a function of the number of discharge pulses pls.

[0249] The correction coefficient α is a value greater than 1. As a result, the target gas Xe concentration C (Xe_target) obtained by multiplying the xenon concentration C (Xe_cy) of the inert new gas by the correction coefficient α is greater than the xenon concentration C (Xe_cy) of the inert new gas. Therefore, the xenon concentration difference C (Xe_add) between the target gas Xe concentration C (Xe_target) and the xenon concentration C (Xe_vent_n) of the exhaust gas is greater than the xenon concentration difference C (Xe_add_n) between the xenon concentration C (Xe_cy) of the inert new gas and the xenon concentration C (Xe_vent_n) of the exhaust gas, and Fig.13 Compared with the case of , the xenon addition amount V(Xe_add_cy) is calculated to be larger.

[0250] 3.2 Function

[0251] (9) According to the second embodiment, the laser control unit 31 calculates the additive amount V(Xe_add_cy) based on the xenon concentration C(Xe_cy) of the inert new gas, the exhaust gas Xe concentration C(Xe_vent_n) and the correction coefficient α, wherein the correction coefficient α is used to estimate the difference C(Xe_add) between the xenon concentration C(Xe_target) of the target gas and the exhaust gas Xe concentration C(Xe_vent_n) to be larger than the difference C(Xe_add_n) between the xenon concentration C(Xe_cy) of the inert new gas and the exhaust gas Xe concentration C(Xe_vent_n), wherein the target gas is obtained by adding the additive gas to the exhaust gas exhausted from the laser cavity 10.

[0252] Thus, by using the correction coefficient α based on the xenon concentration C (Xe_cy) of the inert fresh gas and the exhaust gas Xe concentration C (Xe_vent_n), the addition amount V (Xe_add_cy) can be calculated in consideration of the insufficient amount of xenon lost due to chemical reaction with fluorine, etc.

[0253] (10) According to the second embodiment, the laser control unit 31 obtains the discharge pulse number pls of the laser cavity 10, accesses the storage device storing the relationship between the discharge pulse number pls and the correction coefficient α, and obtains the correction coefficient α.

[0254] Thus, by determining the correction coefficient α according to the number of discharge pulses pls of the laser cavity 10 , the additive amount V(Xe_add_cy) can be calculated more appropriately.

[0255] Regarding other aspects, the second embodiment is the same as the first embodiment.

[0256] 4. Laser device 30a that updates correction coefficient α

[0257] 4.1 Structure

[0258] Fig.28 The structure of the laser system of the third embodiment is schematically shown. In the third embodiment, the exhaust pipes 24a and 24b are respectively connected to sampling ports 80 that can take out a part of the exhaust gas. The sampling port 80 is, for example, arranged at a position accessible from the outside of the housing (not shown) of the laser devices 30a and 30b. A manual valve is arranged between the exhaust pipes 24a and 24b and the sampling port 80, which is closed in normal times, but is opened when taking out a part of the exhaust gas.

[0259] A xenon concentration meter (not shown) can be connected to the sampling port 80. It is not necessary to prepare xenon concentration meters for the laser devices 30a and 30b, respectively, and one xenon concentration meter can be used interchangeably for the laser devices 30a and 30b.

[0260] The sampling port 80 is preferably connected to the exhaust pipes 24a and 24b between the laser cavity 10 and the xenon adding device 60. This allows the measured xenon concentration C (Xe_mes) of the exhaust gas before xenon addition to be measured, and the xenon deficiency can be accurately estimated.

[0261] The sampling port 80 is preferably connected to the discharge pipes 24a and 24b between the fluorine trap 61 and the junction pipe 24. Thus, the concentration of the xenon gas can be measured after xenon fluoride generated by chemical reaction with fluorine is removed.

[0262] 4.2 Xenon Addition Treatment

[0263] Fig.29 1 is a flowchart showing the xenon addition process in the third embodiment. In the third embodiment, the correction coefficient α calculated in the second embodiment is updated based on the measured xenon concentration C (Xe_mes) of the exhaust gas. The correction coefficient α is updated at a lower frequency than the calculation of the xenon addition amount V (Xe_add_cy) using the correction coefficient α.

[0264] S21 and S22a treatment and Fig.26 same.

[0265] In S23b, the laser control unit 31 determines whether the update time of the correction coefficient α has arrived. The update of the correction coefficient α can be performed once a day, for example, or can be performed during the maintenance of the laser device 30a or 30b. When the update time of the correction coefficient α has arrived (S23b: Yes), the laser control unit 31 advances the process to S24b.

[0266] In S24b, the laser control unit 31 updates the correction coefficient α using the measured xenon concentration C (Xe_mes). Fig.30 and Fig.31 After S24b, the laser control unit 31 advances the process to S25a.

[0267] When the update time of the correction coefficient α has not arrived ( S23 b : NO), the laser control unit 31 advances the process to S25 a .

[0268] Processing of S25a to S28 Fig.26 same.

[0269] 4.3 Update of correction coefficient α

[0270] Fig.30 : is a flowchart showing the details of updating the correction coefficient α. Fig.30 The processing shown is equivalent to Fig.29 Subroutine of S24b in.

[0271] In S241, the laser control unit 31 receives the measured xenon concentration C (Xe_mes) of the exhaust gas. The measured xenon concentration C (Xe_mes) may be received from a xenon concentration meter or may be received as a value input by an operator who operates the xenon concentration meter.

[0272] In S242 , the laser control unit 31 calculates the difference ΔC(Xe) between the measured xenon concentration C(Xe_mes) and the exhaust gas Xe concentration C(Xe_vent_n) by the following equation.

[0273] ΔC(Xe)=C(Xe_vent_n)-C(Xe_mes)

[0274] In S243, the laser control unit 31 determines whether the absolute value of the difference ΔC (Xe) is greater than a threshold value. If the absolute value of the difference ΔC (Xe) is less than the threshold value (S243: No), the laser control unit 31 advances the process to S244. If the absolute value of the difference ΔC (Xe) is greater than the threshold value (S243: Yes), the laser control unit 31 advances the process to S245.

[0275] In S244, the laser control unit 31 sets the update parameter β of the correction coefficient α to 1. In this case, the correction coefficient α is not changed in S246 and S247 described later. When the difference ΔC(Xe) is small, the correction coefficient α is not changed, thereby preventing control from becoming unstable.

[0276] In S245, the laser control unit 31 sets the update parameter β of the correction coefficient α by the following equation. In this case, the correction coefficient α is changed in S246 and S247 described later.

[0277] β=C(Xe_vent_n) / C(Xe_mes)

[0278] After S244 or S245, the laser control unit 31 advances the process to S246. In S246, the laser control unit 31 updates the correction coefficient α according to the following equation.

[0279] α=α×β

[0280] Furthermore, in S247, the laser control unit 31 updates the table data of the correction coefficient α according to the following equation.

[0281] α(pls)=α(pls)×β

[0282] Here, α(pls) is a correction coefficient corresponding to the number of discharge pulses pls.

[0283] After S247, the laser control unit 31 ends the processing of this flowchart and returns to Fig.29 Processing shown.

[0284] Fig.31 An example of the correction coefficient α before and after the update is shown. For example, when the correction coefficient α is stored in the memory as table data corresponding to the number of discharge pulses pls, the correction coefficient α is updated for each value of the number of discharge pulses pls. When the correction coefficient α is stored in the memory as a function of the number of discharge pulses pls, the correction coefficient α is updated by transforming the function.

[0285] In the third embodiment, the case where the correction coefficient α is updated using the measured xenon concentration C (Xe_mes) is described, but the present disclosure is not limited to this. Figure 16 to Figure 23 As described above, it is also possible to calculate the estimated xenon concentration C (Xe_est) inside the laser cavity 10 based on the laser performance. The correction coefficient α may be updated using the estimated xenon concentration C (Xe_est).

[0286] 4.4 Function

[0287] (11) According to the third embodiment, the laser control unit 31 calculates the estimated xenon concentration C (Xe_est) of the exhaust gas from the laser cavity 10 based on the laser performance of the laser device 30a, and updates the correction coefficient α based on the estimated xenon concentration C (Xe_est).

[0288] Thus, by using the estimated xenon concentration C (Xe_est) calculated using the laser performance data, the correction coefficient α can be updated and changed to an appropriate value.

[0289] (12) According to the third embodiment, the laser control unit 31 obtains the measured xenon concentration C (Xe_mes) of either the exhaust gas or the inactive regeneration gas exhausted from the laser cavity 10, and updates the correction coefficient α based on the measured xenon concentration C (Xe_mes).

[0290] Thus, by using the actually measured xenon concentration C (Xe_mes), the correction coefficient α can be changed to an appropriate value.

[0291] (13) According to the third embodiment, the sampling port 80 included in the laser device 30a is connected to the exhaust pipe 24a, and is configured to be connectable to a xenon concentration meter.

[0292] Thus, even if a xenon concentration meter is not provided for each laser device 30 a , the xenon concentration meter can be connected to the sampling port 80 when necessary to obtain the measured xenon concentration C (Xe_mes).

[0293] (14) According to the third embodiment, the laser control unit 31 receives the measured xenon concentration C (Xe_mes) at a first frequency, updates the correction coefficient α, and calculates the addition amount V (Xe_add_cy) based on the correction coefficient α at a second frequency higher than the first frequency.

[0294] Thus, by receiving the measured xenon concentration C (Xe_mes) at a first frequency lower than the second frequency of calculating the added amount V (Xe_add_cy), the use frequency of the xenon concentration meter can be reduced, and the replacement frequency of consumables such as the column of the xenon concentration meter can be reduced.

[0295] (15) According to the third embodiment, the laser control unit 31 is configured to access a storage device that stores the relationship between the number of discharge pulses pls and the correction coefficient α of the laser cavity 10. The laser control unit 31 updates the relationship based on the measured xenon concentration C (Xe_mes), and calculates the addition amount V (Xe_add_cy) based on the correction coefficient α obtained from the updated relationship.

[0296] Thus, the correction coefficient α corresponding to the number of discharge pulses pls of the laser cavity 10 is updated based on the measured xenon concentration C (Xe_mes), so that the additive amount V (Xe_add_cy) can be calculated more appropriately.

[0297] Regarding other aspects, the third embodiment is the same as the second embodiment.

[0298] 5. Laser system that updates the correction factor α using the measured xenon concentration C (Xe_mes) of the inert regeneration gas

[0299] 5.1 Structure

[0300] Fig.32 The structure of the laser system of the fourth embodiment is schematically shown. In the fourth embodiment, a xenon concentration meter 90 is arranged at the junction of the junction pipe 24 for the flow of the inactive regeneration gas and the inactive new gas pipe 26 for the flow of the inactive new gas. The xenon concentration meter 90 includes, for example, a gas chromatograph mass spectrometer (GS-MS).

[0301] Fig.33 This is a timing diagram for explaining a method for measuring the measured xenon concentration C (Xe_mes) of the inactive regeneration gas by the xenon concentration meter 90. The valve C-V2 disposed in the junction piping 24 and the valve B-V2 disposed in the inactive new gas piping 26 are controlled to close one and open the other so that both are not in an open state. When the valve B-V2 is in an open state, the xenon concentration meter 90 measures the xenon concentration C (Xe_cy) of the inactive new gas. When the valve C-V2 is in an open state, the xenon concentration meter 90 measures the xenon concentration of the inactive regeneration gas. The xenon concentration C (Xe_cy) of the inactive new gas is always approximately constant. By using the inactive new gas as a reference gas and taking the xenon concentration C (Xe_cy) of the inactive new gas as a reference, the measured xenon concentration C (Xe_mes) of the inactive regeneration gas can be accurately measured.

[0302] The xenon concentration meter 90 may also be arranged in the inert gas piping 27 from the confluence position of the confluence piping 24 and the inert new gas piping 26 to the initial branching point toward the laser device 30a. When the distance from the confluence position of the confluence piping 24 and the inert new gas piping 26 to the xenon concentration meter 90 becomes longer, it is sometimes difficult to distinguish whether the xenon concentration measured by the xenon concentration meter 90 is the xenon concentration of the inert regeneration gas or the xenon concentration of the inert new gas. A flow meter may be arranged in the confluence piping 24 and the inert new gas piping 26, respectively, or a mass flow controller including a flow meter and a flow control valve may be arranged, so that the above distinction can be made based on the history of these flow rates. It is preferred that the distance from the confluence position of the confluence piping 24 and the inert new gas piping 26 to the xenon concentration meter 90 is greater than 0m and less than 1m.

[0303] 5.2 Update of correction coefficient α

[0304] Fig.34 is a flowchart showing the updating process of the correction coefficient α in the fourth embodiment. Fig.26 Similarly, the laser control unit 31 of each laser device 30a, 30b calculates the correction coefficient α independently, and uses the correction coefficient α to calculate the xenon addition amount V (Xe_add_cy). However, the correction coefficient α based on the measured xenon concentration C (Xe_mes) is not updated by the laser control unit 31 of each laser device 30a, 30b, but by the gas circulation system control unit 51 according to Fig.34 Carry out in a unified manner. Fig.34 The correction coefficient α shown is updated once a day, for example, which is more convenient than using Fig.26 The calculation frequency of the xenon addition amount V(Xe_add_cy) of the treatment is low.

[0305] In S241 c , the gas circulation system control unit 51 receives the measured xenon concentration C (Xe_mes) of the inert regeneration gas from the xenon concentration meter 90 .

[0306] In S242c, the gas circulation system control unit 51 calculates the difference ΔC(Xe) between the measured xenon concentration C(Xe_mes) of the inert regeneration gas and the xenon concentration C(Xe_cy) of the inert new gas by the following equation.

[0307] ΔC(Xe)=C(Xe_cy)-C(Xe_mes)

[0308] In S243c, the gas circulation system control unit 51 determines whether the absolute value of the difference ΔC (Xe) is greater than a threshold value. When the absolute value of the difference ΔC (Xe) is less than the threshold value (S243c: No), the gas circulation system control unit 51 advances the process to S244c. When the absolute value of the difference ΔC (Xe) is greater than the threshold value (S243c: Yes), the gas circulation system control unit 51 advances the process to S245c.

[0309] In S244c, the gas circulation system control unit 51 sets the update parameter β of the correction coefficient α to 1. In this case, the correction coefficient α is not changed in S246c described later. When the difference ΔC(Xe) is small, the correction coefficient α is not changed, thereby preventing the control from becoming unstable.

[0310] In S245c, the gas circulation system control unit 51 sets the update parameter β of the correction coefficient α to a value obtained by the following equation. In this case, in S246c described later, the correction coefficient α is changed.

[0311] β=C(Xe_cy) / C(Xe_mes)

[0312] After S244c or S245c, the gas circulation system control unit 51 advances the process to S246c. In S246c, the gas circulation system control unit 51 updates the correction coefficient α of each laser device according to the following equation.

[0313] α(1)=α(1)×β

[0314] α(2)=α(2)×β

[0315] …

[0316] α(m)=α(m)×β

[0317] Here, m is the number of laser devices connected to the gas circulation system 50. α(1), α(2), ..., α(m) are correction coefficients of the first to mth laser devices.

[0318] After S246c, the gas circulation system control unit 51 ends the processing of this flowchart.

[0319] 5.3 Function

[0320] (16) According to the fourth embodiment, the laser system includes the plurality of laser devices 30 a and 30 b and the gas circulation system 50 .

[0321] The gas circulation system 50 includes a converging pipe 24, and exhaust gases discharged from multiple laser devices 30a and 30b are merged in the converging pipe 24. The gas circulation system 50 selects one of the inactive new gas containing xenon and the inactive regeneration gas flowing in the converging pipe 24 and supplies it to the multiple laser devices 30a and 30b.

[0322] Each of the plurality of laser devices 30 a and 30 b includes a laser cavity 10 , an exhaust pipe 24 a or 24 b , a fluorine trap 61 , and a xenon adding device 60 .

[0323] The laser cavity 10 is connected to a gas circulation system 50 .

[0324] The exhaust pipe 24 a or 24 b is connected between the laser cavity 10 and the joining pipe 24 , and is configured to allow the exhaust gas exhausted from the laser cavity 10 to flow toward the joining pipe 24 .

[0325] The fluorine collector 61 is connected to a middle of the exhaust pipe 24 a or 24 b and removes at least fluorine from the exhaust gas exhausted from the laser cavity 10 .

[0326] The xenon adding device 60 is connected to the middle of the exhaust pipe 24 a or 24 b and adds an additive gas having a higher xenon concentration than the inert new gas to the exhaust gas exhausted from the laser cavity 10 .

[0327] Thus, even if the xenon concentration of the exhaust gas differs for each laser cavity 10 , a deficient amount of xenon can be added according to the xenon concentration, so that the xenon concentration of the inert regeneration gas can be brought close to a desired xenon concentration.

[0328] (17) According to the fourth embodiment, the laser system includes the gas circulation system control unit 51 that calculates the addition amount V(Xe_add_cy) of the additive gas, and the plurality of laser devices 30a and 30b are connected to the fluorine-containing gas supply source F2.

[0329] The gas circulation system control unit 51 calculates the Xe concentration C (Xe_vent_n) of the exhaust gas discharged from the laser cavity 10 based on the supply amounts V (F_ini) and V (F_n) of the fluorine-containing gas supplied to the laser cavity 10 from the fluorine-containing gas supply source F2 and the supply amounts V (Ar_ini) and V (Ar_n) of one of the inactive new gas and the inactive regeneration gas supplied to the laser cavity 10 from the gas circulation system 50. In addition, the gas circulation system control unit 51 calculates the additive amount V(Xe_add_cy) based on the xenon concentration C(Xe_cy) of the inert new gas, the exhaust gas Xe concentration C(Xe_vent_n) and the correction coefficient α, wherein the correction coefficient α is used to estimate the difference C(Xe_add) between the xenon concentration C(Xe_target) of the target gas and the exhaust gas Xe concentration C(Xe_vent_n) to be larger than the difference C(Xe_add_n) between the xenon concentration C(Xe_cy) of the inert new gas and the exhaust gas Xe concentration C(Xe_vent_n), and the target gas is obtained by adding additive gas to the exhaust gas discharged from the laser cavity 10.

[0330] Thus, by using the correction coefficient α based on the xenon concentration C (Xe_cy) of the inert fresh gas and the exhaust gas Xe concentration C (Xe_vent_n), the addition amount V (Xe_add_cy) can be calculated in consideration of the insufficient amount of xenon lost due to chemical reaction with fluorine, etc.

[0331] (18) According to the fourth embodiment, the gas circulation system 50 includes: an inert gas piping 27 that merges the inert new gas and the inert regeneration gas and branches toward the plurality of laser devices 30a and 30b; and a xenon concentration meter 90 that is disposed between the merging point of the inert new gas and the inert regeneration gas and the branching point toward the plurality of laser devices 30a and 30b. The gas circulation system control unit 51 updates the correction coefficient α based on the measured xenon concentration C (Xe_mes) measured by the xenon concentration meter 90.

[0332] Thus, by using the actually measured xenon concentration C (Xe_mes), the correction coefficient α can be changed to an appropriate value.

[0333] (19) According to the fourth embodiment, the xenon concentration meter 90 measures the xenon concentration C (Xe_mes) using the inert fresh gas as the reference gas.

[0334] Thus, the xenon concentration meter 90 does not need to include a separate supply source of the reference gas, and can make the xenon concentration of the inert regeneration gas closer to the xenon concentration C (Xe_cy) of the inert fresh gas.

[0335] Regarding other aspects, the fourth embodiment is the same as the second embodiment.

[0336] 6. Others

[0337] Fig.35 The structure of the exposure device 100 connected to the laser device 30a is schematically shown. As described above, the laser device 30a generates laser light and outputs it to the exposure device 100.

[0338] exist Fig.35 In the embodiment, the exposure device 100 includes an illumination optical system 141 and a projection optical system 142. The illumination optical system 141 illuminates the mask pattern of the mask stage RT by the laser light incident from the laser device 30a. The projection optical system 142 performs reduced projection of the laser light after passing through the mask so that it is imaged on a workpiece (not shown) arranged on the workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a photoresist. The exposure device 100 causes the mask stage RT and the workpiece stage WT to move synchronously and in parallel, thereby exposing the workpiece to the laser light reflecting the mask pattern. By transferring the device pattern on the semiconductor wafer through the above exposure process, electronic devices can be manufactured.

[0339] The above description is not limiting but simply illustrative. Therefore, those skilled in the art will appreciate that changes can be made to the embodiments of the present disclosure without departing from the claims. In addition, those skilled in the art will appreciate that the embodiments of the present disclosure can be used in combination.

[0340] Unless explicitly stated otherwise, 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", "having", and "having" should be interpreted as "excluding the existence of structural elements other than the structural elements to be recorded". 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 laser device, comprising: a laser cavity connected to a gas circulation system including a converging pipe in which exhaust gases exhausted from a plurality of laser devices including the laser device converge, the gas circulation system selecting one of a new gas containing xenon and a circulating gas flowing in the converging pipe and supplying the selected gas to the plurality of laser devices; an exhaust pipe connected between the laser cavity and the merging pipe, and allowing exhaust gas exhausted from the laser cavity to flow toward the merging pipe; a fluorine collector connected to the middle of the exhaust pipe and removing at least fluorine from the exhaust gas exhausted from the laser cavity; as well as A xenon adding device is connected to the middle of the exhaust pipe and adds an added gas having a higher xenon concentration than the new gas to the exhaust gas exhausted from the laser cavity.

2. The laser device according to claim 1, wherein: The xenon adding device is located on the downstream side of the exhaust gas exhausted from the laser cavity rather than the fluorine trap.

3. The laser device according to claim 1, wherein: The laser device has two laser cavities including the laser cavity, The two laser cavities are connected to the exhaust pipe via a first exhaust path and a second exhaust path, respectively. A first valve and a second valve are disposed in the first discharge path and the second discharge path, respectively, and the first valve and the second valve are controlled so that one of the valves is closed and the other is opened.

4. The laser device according to claim 1, wherein: The laser device further includes a processor that calculates the amount of the additional gas to be added based on the xenon concentration of the new gas.

5. The laser device according to claim 4, wherein: The exhaust pipe between the laser cavity and the xenon adding device is provided with a third valve. The processor controls the third valve and the xenon adding device to alternately open and close the third valve and to cause the xenon adding device to add less than half of the amount of the added gas to exhaust gas exhausted from the laser cavity.

6. The laser device according to claim 4, wherein: the processor calculating an estimated xenon concentration of exhaust gas exhausted from the laser cavity based on laser performance of the laser device, The processor calculates the addition amount based on the xenon concentration of the new gas and the estimated xenon concentration.

7. The laser device according to claim 4, wherein: the processor calculating a calculated xenon concentration of exhaust gas exhausted from the laser cavity, The processor calculates the addition amount based on the xenon concentration of the new gas and the calculated xenon concentration.

8. The laser device according to claim 7, wherein: The laser cavity is connected to a fluorine-containing gas supply source, The processor calculates the calculated xenon concentration based on a supply amount of the fluorine-containing gas supplied from the fluorine-containing gas supply source to the laser cavity and a supply amount of one of the new gas and the circulating gas supplied from the gas circulation system to the laser cavity.

9. The laser device according to claim 8, wherein: The processor calculates the added amount based on the xenon concentration of the new gas, the calculated xenon concentration and a correction factor, wherein the correction factor is used to estimate the difference between the xenon concentration of the target gas obtained by adding the added gas to the exhaust gas discharged from the laser cavity to be greater than the difference between the xenon concentration of the new gas and the calculated xenon concentration.

10. The laser device according to claim 9, wherein: The processor obtains the number of discharge pulses of the laser cavity, The processor accesses a storage device storing a relationship between the number of discharge pulses and the correction coefficient to obtain the correction coefficient.

11. The laser device according to claim 9, wherein: the processor calculating an estimated xenon concentration of exhaust gas exhausted from the laser cavity based on laser performance of the laser device, The processor updates the correction factor based on the estimated xenon concentration.

12. The laser device according to claim 9, wherein: The processor obtains a measured xenon concentration of either exhaust gas exhausted from the laser cavity or the circulating gas, The processor updates the correction coefficient based on the measured xenon concentration.

13. The laser device according to claim 12, wherein: The laser device further includes a sampling port, which is connected to the exhaust pipe and can be connected to a xenon concentration meter.

14. The laser device according to claim 12, wherein: The processor receives the measured xenon concentration at a first frequency and updates the correction coefficient. The processor calculates the addition amount based on the correction coefficient at a second frequency higher than the first frequency.

15. The laser device according to claim 12, wherein: The processor is configured to access a storage device storing a relationship between the number of discharge pulses of the laser cavity and the correction coefficient. the processor updating the relationship based on the measured xenon concentration, The processor calculates the addition amount based on the correction coefficient obtained from the updated relationship.

16. A laser system comprising: a plurality of laser devices; and a gas circulation system including a converging pipe in which exhaust gases exhausted from the plurality of laser devices converge, the gas circulation system selecting one of a new gas containing xenon and a circulating gas flowing in the converging pipe and supplying the selected gas to the plurality of laser devices; The plurality of laser devices respectively include: A laser cavity connected to the gas circulation system; an exhaust pipe connected between the laser cavity and the merging pipe, and allowing exhaust gas exhausted from the laser cavity to flow toward the merging pipe; a fluorine collector connected to the middle of the exhaust pipe and removing at least fluorine from the exhaust gas exhausted from the laser cavity; and A xenon adding device is connected to the middle of the exhaust pipe and adds an added gas having a higher xenon concentration than the new gas to the exhaust gas exhausted from the laser cavity.

17. The laser system of claim 16, wherein: The laser system further comprises a processor, which calculates the amount of the added gas. The plurality of laser devices are connected to a fluorine-containing gas supply source, The processor calculates a calculated xenon concentration of exhaust gas exhausted from the laser cavity based on a supply amount of the fluorine-containing gas supplied from the fluorine-containing gas supply source to the laser cavity and a supply amount of one of the new gas and the circulating gas supplied from the gas circulation system to the laser cavity, The processor calculates the added amount based on the xenon concentration of the new gas, the calculated xenon concentration and a correction coefficient, wherein the correction coefficient is used to estimate the difference between the xenon concentration of the target gas and the calculated xenon concentration to be greater than the difference between the xenon concentration of the new gas and the calculated xenon concentration. The target gas is obtained by adding the added gas to the exhaust gas discharged from the laser cavity.

18. The laser system of claim 17, wherein: The gas circulation system comprises: an inert gas pipe that merges the new gas and the circulating gas and branches toward the plurality of laser devices; and a xenon concentration meter disposed between a junction of the fresh gas and the circulating gas and a branch point toward the plurality of laser devices, The processor updates the correction coefficient according to the xenon concentration measured by the xenon concentration meter.

19. The laser system of claim 18, wherein: The xenon concentration meter measures the measured xenon concentration using the new gas as a reference gas.

20. A method for manufacturing an electronic device, comprising the following steps: generating laser light by one of the plurality of laser devices, outputting the laser to an exposure device, exposing the laser light on a photosensitive substrate in the exposure device to manufacture the electronic device, The laser device has: a laser cavity connected to a gas circulation system including a converging pipe in which exhaust gases exhausted from the plurality of laser devices converge, the gas circulation system selecting one of a new gas containing xenon and a circulating gas flowing in the converging pipe and supplying the selected gas to the plurality of laser devices; an exhaust pipe connected between the laser cavity and the merging pipe, and allowing exhaust gas exhausted from the laser cavity to flow toward the merging pipe; a fluorine collector connected to the middle of the exhaust pipe and removing at least fluorine from the exhaust gas exhausted from the laser cavity; as well as A xenon adding device is connected to the middle of the exhaust pipe and adds an added gas having a higher xenon concentration than the new gas to the exhaust gas exhausted from the laser cavity.

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