Method for baking the chamber of a gas laser apparatus and method for manufacturing an electronic device

Abstract

This baking method for a chamber of a gas laser apparatus is applied to a gas laser apparatus having a chamber that has an interior space in which a beam is generated, the gas laser apparatus being provided with, on the outside of a sidewall in contact with the interior space of the chamber, a cooling passage configured so as to allow a flow of a cooling medium for cooling the chamber, the baking method comprising: a heating step of, prior to generating the beam in the interior space, letting a heating medium flow in the cooling passage so as to heat the interior space through the sidewall; and a discharge step of discharging gas in the heated interior space to an exterior space of the chamber.

Description

Technical Field

[0001] The present disclosure relates to a baking method for a chamber of a gas laser device and a manufacturing method for an electronic device.

Background Art

[0002] In recent years, in semiconductor exposure apparatuses, as semiconductor integrated circuits are miniaturized and highly integrated, improvement in resolution has been demanded. For this reason, shortening of the wavelength of light emitted from an exposure light source has been promoted. For example, as a gas laser device for exposure, a KrF excimer laser device that outputs laser light with a wavelength of about 248 nm and an ArF excimer laser device that outputs laser light with a wavelength of about 193 nm are used.

[0003] The spectral linewidth of the spontaneous emission light of a KrF excimer laser device and an ArF excimer laser device is as wide as 350 pm to 400 pm. Therefore, when a projection lens is configured with a material that transmits ultraviolet rays such as KrF and ArF laser light, chromatic aberration may occur. As a result, the resolution may decrease. Therefore, it is necessary to narrow the spectral linewidth of the laser light output from the gas laser device until chromatic aberration can be ignored. For this reason, in the laser resonator of the gas laser device, a line narrowing module (LNM) including a line narrowing element (etalon, grating, etc.) may be provided to narrow the spectral linewidth. Hereinafter, a gas laser device in which the spectral linewidth is narrowed is referred to as a line-narrowed gas laser device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] A method for baking a chamber of a gas laser apparatus according to one aspect of the present disclosure is a method for baking a chamber of a gas laser apparatus, wherein a cooling passage is provided on the outside of a wall surface in contact with the internal space of the chamber in which light is generated in the internal space, and the cooling passage is configured to flow a cooling medium for cooling the chamber, and the method may include a heating step of flowing a heating medium through the cooling passage to heat the internal space via the wall surface before light is generated in the internal space, and an exhaust step of exhausting the gas in the heated internal space to the external space of the chamber.

[0006] A method for manufacturing an electronic device according to one aspect of the present disclosure is a method for baking a chamber of a gas laser apparatus, the chamber of which generates light in the internal space, and the chamber is provided with a cooling passage configured to flow a cooling medium for cooling the chamber on the outside of a wall surface in contact with the internal space of the chamber, the baking method comprising: a heating step of flowing a heating medium through the cooling passage to heat the internal space via the wall surface before generating light in the internal space; and an exhaust step of exhausting the gas in the heated internal space to the external space of the chamber, the gas laser apparatus having a chamber baked by this baking method may generate laser light, output the laser light to an exposure apparatus, and expose a photosensitive substrate with the laser light in the exposure apparatus in order to manufacture an electronic device. [Brief explanation of the drawing]

[0007] Some embodiments of this disclosure are described below, merely as examples, with reference to the accompanying drawings. [Figure 1] Figure 1 is a schematic diagram showing an example of the overall configuration of an electronic device manufacturing apparatus. [Figure 2] Figure 2 is a schematic diagram showing an example of the overall configuration of a comparative gas laser apparatus. [Figure 3] Figure 3 is a cross-sectional view of the comparative example chamber perpendicular to the direction of laser beam propagation. [Figure 4] Figure 4 shows an example of a flowchart for the baking method of the comparative chamber. [Figure 5] Figure 5 shows the arrangement of the chambers during baking in the comparative example. [Figure 6] Figure 6 is a perspective view of the chamber of the embodiment. [Figure 7] Figure 7 is a cross-sectional view of the chamber of the embodiment, perpendicular to the direction of laser beam propagation. [Figure 8] Figure 8 is a perspective view of the outer main body of the outer housing that surrounds the inner housing and the partition wall. [Figure 9] Figure 9 shows the positional relationship between the fins and the bulkhead. [Figure 10] Figure 10 shows the arrangement of the chambers during baking in the embodiment. [Figure 11] Figure 11 shows an example of a flowchart of the baking method in the embodiment. [Figure 12] Figure 12 is a cross-sectional view of the chamber in a modified example. Embodiment

[0008] 1. Description of the manufacturing equipment for electronic devices used in the exposure process for electronic devices. 2. Description of the comparative gas laser apparatus 2.1 Configuration 2.2 Operation 2.3 Chamber Baking Method 2.4 Challenges 3. Description of the Chamber of the Embodiment 3.1 Configuration 3.2 Baking method for the chamber 3.3 Action and Effects

[0009] The embodiments of this disclosure will be described in detail below with reference to the drawings. The embodiments described below are examples of the disclosure and are not intended to limit the scope of this disclosure. Not all configurations and operations described in each embodiment are necessarily essential to the configurations and operations of the disclosure. The same reference numerals are used for identical components, and redundant descriptions are omitted.

[0010] 1. Description of the manufacturing equipment for electronic devices used in the exposure process for electronic devices. Figure 1 is a schematic diagram showing an example of the overall configuration of an electronic device manufacturing apparatus used in the exposure process for electronic devices. As shown in Figure 1, the manufacturing apparatus used in the exposure process includes a gas laser apparatus 100 and an exposure apparatus 200. The exposure apparatus 200 includes an illumination optical system 210 including a plurality of mirrors 211, 212, 213 and a projection optical system 220. The illumination optical system 210 illuminates the reticle pattern of the reticle stage RT with laser light incident from the gas laser apparatus 100. The projection optical system 220 reduces and projects the laser light that passes through the reticle onto a workpiece (not shown) placed on the workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer on which photoresist is coated. The exposure apparatus 200 exposes the workpiece with laser light that reflects the reticle pattern by synchronously moving the reticle stage RT and the workpiece table WT in parallel. By transferring the device pattern onto the semiconductor wafer through the exposure process described above, a semiconductor device, which is an electronic device, can be manufactured.

[0011] 2. Description of the comparative gas laser apparatus 2.1 Configuration A comparative example gas laser apparatus 100 will be described. Note that the comparative examples in this disclosure are forms that the applicant recognizes as being known only to the applicant, and are not prior art acknowledged by the applicant.

[0012] FIG. 2 is a schematic diagram showing an overall schematic configuration example of a gas laser device 100 of a comparative example. The gas laser device 100 is, for example, an ArF excimer laser device that uses a mixed gas containing argon (Ar), fluorine (F2), and neon (Ne). This gas laser device 100 outputs laser light having a central wavelength of about 193 nm. Note that the gas laser device 100 may be a gas laser device other than an ArF excimer laser device, and for example, may be a KrF excimer laser device that uses a mixed gas containing krypton (Kr), F2, and Ne. In this case, the gas laser device 100 emits laser light having a central wavelength of about 248 nm. A mixed gas containing Ar, F2, and Ne as a laser medium or a mixed gas containing Kr, F2, and Ne as a laser medium may be called a laser gas.

[0013] The gas laser device 100 mainly includes a housing 110, a laser oscillator 130, a monitor module 160, a shutter 170, and a laser processor 190 disposed in the internal space of the housing 110.

[0014] The laser oscillator 130 includes a chamber 131, a charger 141, a pulse power module 143, a narrowband module 145, and an output coupling mirror 147. In FIG. 2, the internal configuration of the chamber 131 is shown as viewed from a direction substantially perpendicular to the traveling direction of the laser light.

[0015] Examples of the material of the chamber 131 include metals such as nickel-plated aluminum or nickel-plated stainless steel. The chamber 131 includes an internal space where light is generated by excitation of the laser medium in the laser gas. The light travels to windows 139a and 139b, which will be described later. The laser gas is supplied from a laser gas supply source (not shown) to the internal space of the chamber 131 through a pipe (not shown). Further, the laser gas in the chamber 131 is subjected to a process of removing F2 gas by a halogen filter or the like, and is exhausted to the housing 110 through a pipe (not shown) by an exhaust pump (not shown).

[0016] Within the internal space of chamber 131, electrodes 133a and 133b are positioned opposite each other, spaced apart, with their respective longitudinal directions aligned with the direction of laser beam propagation. In the following explanation, the longitudinal direction of electrodes 133a and 133b may be referred to as the Z direction, the direction perpendicular to the Z direction in which electrodes 133a and 133b are aligned and spaced apart may be referred to as the Y direction, and the direction perpendicular to both the Y and Z directions may be referred to as the X direction. Electrodes 133a and 133b are discharge electrodes for exciting the laser medium by glow discharge. In this example, electrode 133a is the cathode and electrode 133b is the anode.

[0017] Electrode 133a is fixed to the inner space side of the chamber 131 of the plate-shaped electrical insulation portion 135 by a conductive member 157, for example, a bolt. The conductive member 157 is electrically connected to the pulse power module 143 and applies a high voltage from the pulse power module 143 to electrode 133a. Electrode 133b is supported and electrically connected to the electrode holder portion 137.

[0018] The electrical insulating part 135 includes an insulator. Examples of materials for the electrical insulating part 135 include alumina ceramics, which have low reactivity with F2 gas. The electrical insulating part 135 only needs to have electrical insulating properties; examples of such materials include resins such as phenolic resin and fluororesin, or materials such as quartz and glass. The electrical insulating part 135 closes the opening provided in the chamber 131 and is fixed to the chamber 131.

[0019] The charger 141 is a DC power supply that charges a charging capacitor (not shown) in the pulse power module 143 with a predetermined voltage. The pulse power module 143 includes a switch 143a controlled by a laser processor 190. When the switch 143a is turned from OFF to ON, the pulse power module 143 generates a pulsed high voltage from the electrical energy held in the charger 141 and applies this high voltage between electrodes 133a and 133b.

[0020] When a high voltage is applied between electrodes 133a and 133b, a discharge occurs between them. The energy of this discharge excites the laser medium in chamber 131, and the excited laser medium emits light when it transitions to the ground state.

[0021] Chamber 131 is provided with a pair of windows 139a and 139b. Window 139a is located at one end of the chamber 131 in the direction of laser beam propagation, and window 139b is located at the other end in the same direction of propagation. Windows 139a and 139b sandwich the space between electrodes 133a and 133b. Windows 139a and 139b are inclined to form a Brewster angle with respect to the direction of laser beam propagation so as to suppress the reflection of P-polarized laser beam. The oscillating laser beam, as described later, exits the chamber 131 through windows 139a and 139b. As described above, a pulsed high voltage is applied between electrodes 133a and 133b by the pulse power module 143, so this laser beam is pulsed laser beam.

[0022] The narrowband module 145 includes a housing 145a, a prism 145b, a grating 145c, and a rotating stage (not shown) arranged in the internal space of the housing 145a. The housing 145a has an opening, which connects to the rear side of the chamber 131.

[0023] The prism 145b widens the beam width of the light emitted from the window 139a and directs this light onto the grating 145c. The prism 145b also reduces the beam width of the reflected light from the grating 145c and returns this light to the interior space of the chamber 131 via the window 139a. The prism 145b is supported by a rotating stage and rotates by the rotating stage. The rotation of the prism 145b changes the angle of incidence of the light on the grating 145c. Therefore, the rotation of the prism 145b allows for the selection of the wavelength of light returning from the grating 145c through the prism 145b to the chamber 131. Figure 2 shows an example with one prism 145b, but at least one prism is required.

[0024] The surface of the grating 145c is made of a highly reflective material and has numerous grooves at predetermined intervals. The cross-sectional shape of each groove is, for example, a right triangle. Light incident on the grating 145c from the prism 145b is reflected by these grooves and diffracted in a direction corresponding to the wavelength of the light. The grating 145c is Littrow-positioned such that the angle of incidence of the light incident on the grating 145c from the prism 145b matches the diffraction angle of the diffracted light of the desired wavelength. This allows light near the desired wavelength to be returned to the chamber 131 via the prism 145b.

[0025] The output coupling mirror 147 is positioned in the internal space of the optical path tube 147a, which is connected to the front side of the chamber 131, and faces the window 139b. The output coupling mirror 147 transmits a portion of the laser light emitted from the window 139b toward the monitor module 160, and reflects the other portion back through the window 139b to the internal space of the chamber 131. In this way, the grating 145c and the output coupling mirror 147 form a Fabry-Perot type laser resonator, and the chamber 131 is positioned on the optical path of the laser resonator.

[0026] The monitor module 160 is positioned on the optical path of the laser beam emitted from the output coupling mirror 147. The monitor module 160 includes a housing 161 and a beam splitter 163 and an optical sensor 165, which are located in the internal space of the housing 161. An opening is formed in the housing 161, and through this opening, the internal space of the housing 161 communicates with the internal space of the optical path tube 147a.

[0027] The beam splitter 163 transmits a portion of the laser light emitted from the output coupling mirror 147 towards the shutter 170 and reflects the other portion of the laser light towards the light-receiving surface of the optical sensor 165. The optical sensor 165 measures the energy E of the laser light incident on the light-receiving surface. The optical sensor 165 outputs a signal indicating the measured energy E to the laser processor 190.

[0028] The laser processor 190 of this disclosure is a processing unit that includes a storage device 190a in which a control program is stored, and a CPU (Central Processing Unit) 190b that executes the control program. The laser processor 190 is specially configured or programmed to perform various processes included in this disclosure. The laser processor 190 also controls the entire gas laser apparatus 100.

[0029] The laser processor 190 transmits and receives various signals to and from the exposure processor 230 of the exposure apparatus 200. For example, the laser processor 190 receives signals from the exposure processor 230 indicating the light emission trigger Tr and the target energy Et, which will be described later. The target energy Et is the target value of the energy of the laser light used in the exposure process. The laser processor 190 controls the charging voltage of the charger 141 based on the energy E and target energy Et received from the optical sensor 165 and the exposure processor 230. By controlling this charging voltage, the energy of the laser light is controlled. The laser processor 190 also transmits an ON or OFF command signal for the switch 143a to the pulse power module 143. The laser processor 190 is also electrically connected to the shutter 170 and controls the opening and closing of the shutter 170.

[0030] The laser processor 190 closes the shutter 170 until the difference ΔE between the energy E received from the monitor module 160 and the target energy Et received from the exposure processor 230 falls within an acceptable range. Once the difference ΔE is within an acceptable range, the laser processor 190 sends a ready-to-receive signal to the exposure processor 230 indicating that it is ready to receive the light emission trigger Tr. Upon receiving the ready-to-receive signal, the exposure processor 230 sends a signal indicating the light emission trigger Tr to the laser processor 190, and upon receiving the signal indicating the light emission trigger Tr, the laser processor 190 opens the shutter 170. The light emission trigger Tr is defined by a predetermined repetition frequency f of the laser light and a predetermined number of pulses P, and is an external trigger that causes the exposure processor 230 to cause the laser oscillator 130 to oscillate. The repetition frequency f of the laser light is, for example, 100 Hz or more and 10 kHz or less.

[0031] The shutter 170 is positioned in the optical path of the laser light that passes through an opening formed on the opposite side of the housing 161 of the monitor module 160 from the side to which the optical path tube 147a is connected. The shutter 170 is also positioned in the internal space of the optical path tube 171. The optical path tube 171 is connected to the housing 161 so as to surround the opening and communicates with the housing 161. Purge gas is supplied and filled into the internal spaces of the optical path tubes 171 and 147a, and the internal spaces of the housings 161 and 145a. The purge gas contains an inert gas such as nitrogen (N2). The purge gas is supplied from a purge gas supply source (not shown) through piping (not shown). The optical path tube 171 is also in communication with the exposure apparatus 200 through an opening in the housing 110 and an optical path tube 500 connecting the housing 110 and the exposure apparatus 200. The laser light that passes through the shutter 170 is incident on the exposure apparatus 200.

[0032] The exposure processor 230 of this disclosure is a processing unit that includes a storage device 230a in which a control program is stored and a CPU 230b that executes the control program. The exposure processor 230 is specially configured or programmed to perform various processes included in this disclosure. The exposure processor 230 also controls the entire exposure apparatus 200.

[0033] Figure 3 is a cross-sectional view of the comparative example chamber 131 perpendicular to the direction of laser beam propagation. A cross-flow fan 149 and a heat exchanger 151 are further arranged in the internal space of the chamber 131.

[0034] The cross-flow fan 149 and the heat exchanger 151 are located in the internal space of the chamber 131 on the side opposite to electrode 133b, with reference to the electrode holder portion 137. Within the internal space of the chamber 131, the space in which the cross-flow fan 149 and the heat exchanger 151 are located is in communication with the space between electrodes 133a and 133b. The heat exchanger 151 is located next to the cross-flow fan 149 and is connected to piping (not shown) through which a cooling medium, which is either liquid or gas, flows. The heat exchanger 151 is a radiator. As shown in Figure 2, the cross-flow fan 149 is connected to a motor 149a located outside the chamber 131 and rotates due to the rotation of the motor 149a. As the cross-flow fan 149 rotates, the laser gas sealed in the internal space of the chamber 131 circulates as shown by the thick arrows in Figure 3. In other words, the laser gas circulates in the following order: cross-flow fan 149, between electrodes 133a and 133b, heat exchanger 151, and then back to cross-flow fan 149. At least a portion of the circulating laser gas passes through the heat exchanger 151, which regulates the temperature of the laser gas. The ON / OFF status and rotation speed of motor 149a are controlled by the laser processor 190. Therefore, the laser processor 190 can adjust the circulation speed of the laser gas circulating within the internal space of chamber 131 by controlling motor 149a.

[0035] The electrode holder portion 137 is electrically connected to the chamber 131 via the wiring 137a. The electrode 133b supported by the electrode holder portion 137 is connected to ground potential via the electrode holder portion 137, the wiring 137a, and the chamber 131.

[0036] On the electrode holder portion 137, a pre-ionization electrode (not shown) is provided to the side of the electrode 133b. The pre-ionization electrode comprises an inner electrode, an outer electrode, and a dielectric. The inner electrode is connected to the pulse power module 143 via wiring (not shown). The outer electrode is electrically connected to the electrode 133b via the electrode holder portion 137, and is also electrically connected to the chamber 131 via the electrode holder portion 137 and the wiring 137a. Therefore, the outer electrode is connected to ground potential via the electrode holder portion 137, the wiring 137a, and the chamber 131. The dielectric is a cylindrical pipe with its longitudinal direction aligned with the direction of laser light propagation. Inside the dielectric, an inner electrode is arranged with its longitudinal direction aligned with the longitudinal direction of the dielectric. The dielectric is made of, for example, aluminum oxide, and is placed between the inner electrode and the outer electrode. When a high voltage is applied to the inner electrode and the outer electrode from the pulse power module 143, a corona discharge occurs near the dielectric and the outer electrode. This corona discharge assists in the stable generation of the glow discharge that occurs between electrodes 133a and 133b.

[0037] 2.2 Operation Next, the operation of the comparative example gas laser apparatus 100 will be described.

[0038] Before the gas laser device 100 emits laser light, the internal spaces of the optical path tubes 147a, 171, and 500, and the internal spaces of the housings 145a and 161 are filled with purge gas from a purge gas supply source (not shown). In addition, laser gas is supplied to the internal space of the chamber 131 from a laser gas supply source (not shown). Once the laser gas is supplied, the laser processor 190 controls the motor 149a to rotate the cross-flow fan 149. The rotation of the cross-flow fan 149 causes the laser gas to circulate within the internal space of the chamber 131.

[0039] When the gas laser device 100 emits laser light, the laser processor 190 receives a signal indicating the target energy Et and a signal indicating the light emission trigger Tr from the exposure processor 230. When the laser processor 190 receives the signal indicating the target energy Et, it closes the shutter 170 and drives the charger 141. The laser processor 190 also turns on the switch 143a of the pulse power module 143. As a result, the pulse power module 143 applies a pulsed high voltage between electrodes 133a and 133b and between the inner electrode and the outer electrode using the electrical energy held in the charger 141. However, the timing of the application of the high voltage between the inner electrode and the outer electrode is slightly earlier than the timing of the application of the high voltage between electrodes 133a and 133b. When a high voltage is applied between the inner electrode and the outer electrode, a corona discharge occurs near the dielectric, and ultraviolet light is emitted. When ultraviolet light is irradiated onto the laser gas between electrodes 133a and 133b, the laser gas between electrodes 133a and 133b is pre-ionized. After pre-ionization, when a high voltage is applied between electrodes 133a and 133b, a discharge occurs between electrodes 133a and 133b. As a result, the laser medium contained in the laser gas between electrodes 133a and 133b is excited, and emits light when the laser medium returns to its ground state. This light resonates between the grating 145c and the output coupling mirror 147, and the light is amplified each time it passes through the discharge space in the internal space of the chamber 131, causing laser oscillation. Then, a portion of the laser light passes through the output coupling mirror 147 as pulsed laser light and proceeds to the beam splitter 163.

[0040] A portion of the laser light that travels to the beam splitter 163 is reflected by the beam splitter 163 and received by the light sensor 165. The light sensor 165 measures the energy E of the received laser light and outputs a signal indicating the energy E to the laser processor 190. The laser processor 190 controls the charging voltage so that the difference ΔE between the energy E and the target energy Et is within an acceptable range, and after the difference ΔE is within an acceptable range, it sends a ready-to-receive signal to the exposure processor 230 indicating that the light emission trigger Tr is ready to receive.

[0041] When the exposure processor 230 receives a signal indicating it is ready to receive, it transmits a light emission trigger Tr to the laser processor 190. Synchronized with the reception of the light emission trigger Tr, the laser processor 190 opens the shutter 170, and the laser light that has passed through the shutter 170 enters the exposure apparatus 200. This laser light is, for example, a pulsed laser light with a central wavelength of 193 nm.

[0042] Furthermore, the circulation of the laser gas causes impurities in the gas generated by the discharge between electrodes 133a and 133b to move downstream, and fresh laser gas is supplied between electrodes 133a and 133b for the next discharge. In addition, as the laser gas passes through the heat exchanger 151, the heat associated with the discharge is removed, suppressing the temperature rise of the laser gas.

[0043] 2.3 Chamber Baking Method In the above operation, when light is emitted from the laser gas in the internal space of the chamber 131, we will now describe the case where moisture is adsorbed on internal components of the chamber 131, such as the electrode 133a, which is placed in the internal space of the chamber 131. This moisture is adsorbed, for example, by cleaning the chamber 131 before it is installed in the gas laser apparatus 100. When moisture reacts with the laser gas in the internal space of the chamber 131, gas impurities may be generated. These gas impurities may absorb the laser light in the chamber 131, reducing the output of the laser light, or worsen the discharge between the electrode 133a and the electrode 133b, which can hinder the emission of laser light that meets the required performance from the exposure apparatus 200. For this reason, it is necessary to bake the internal space of the chamber 131 to remove the adsorbed moisture before generating light in the internal space of the chamber 131. In other words, the baking process is part of the preparation process for the gas laser apparatus 100 and is performed before the gas laser apparatus 100 is put into operation, that is, before generating light in the internal space of the chamber 131.

[0044] Figure 4 shows an example flowchart of the baking method for the chamber 131 of the comparative example gas laser apparatus 100. Hereinafter, the baking method for the chamber 131 may be simply referred to as the baking method. The comparative example baking method includes a preparation step SP11, a heating step SP12, an exhaust step SP13, and an installation step SP14. Figure 5 shows the arrangement of the chamber 131 during baking in the comparative example. In the comparative example baking method, the chamber 131 is baked before it is installed in the housing 110 of the gas laser apparatus 100. Therefore, the chamber 131 is baked outside the housing 110.

[0045] (Preparation Step SP11) In this step, the chamber 131 is installed in a baking facility (not shown) located outside the housing 110, and the mantle heater 301 is wrapped around the outside of the chamber 131 outside the housing 110. Figure 5 shows a simplified illustration of the chamber 131. In this step, one pipe 303a to which the vacuum pump 303 is connected is attached to the chamber 131. Pipe 303a penetrates the chamber 131 and communicates with the internal space of the chamber 131. The other pipe 303b is connected to the vacuum pump 303, and pipe 303b communicates with the outside. Once these preparations are complete, the flow proceeds to the heating step SP12.

[0046] (Heating step SP12) In this step, the mantle heater 301 is heated to over 150°C, heating the internal space of the chamber 131. The heating causes any moisture adsorbed onto the internal components of the chamber 131 to detach from them. The flow then proceeds to the exhaust step SP13.

[0047] (Exhaust step SP13) In this step, the water-containing gas impurities that have been removed from the internal space of the heated chamber 131 are sucked out by the vacuum pump 303 through piping 303a, and the sucked-out gas is exhausted to the external space of the chamber 131 through piping 303b. In this way, the water-containing gas impurities that have been removed are exhausted from the internal space of the heated chamber 131 to the external space of the chamber 131 by the vacuum pump 303. Then the process proceeds to the installation step SP14.

[0048] (Installation step SP14) In this step, the chamber 131 is installed in the housing 110 of the gas laser device 100, and the flow is completed. The gas laser device 100 then goes into standby mode for full operation.

[0049] 2.4 Challenges In the comparative example's baking method, the mantle heater 301 is wrapped around the outside of the chamber 131, but a gap may occur between the chamber 131 and the mantle heater 301. This gap makes it difficult for the heat from the mantle heater 301 to transfer to the chamber 131, causing the internal space of the chamber 131 to heat up slowly and resulting in a longer baking time for the chamber 131. Therefore, shortening the baking period is desired.

[0050] Therefore, the following embodiment illustrates a baking method for the chamber 131 of the gas laser apparatus 100 that can shorten the baking period.

[0051] 3. Description of the Chamber of the Embodiment Next, the chamber 131 of the embodiment will be described. Components similar to those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified. Also, in some drawings, some components may be omitted or simplified for clarity.

[0052] 3.1 Configuration Figure 6 is a perspective view of the chamber 131 of this embodiment. Figure 7 is a cross-sectional view of the chamber 131 of this embodiment perpendicular to the direction of laser beam propagation. In Figure 7, the laser gas flow is indicated by thick arrows, similar to the comparative example shown in Figure 2.

[0053] In the chamber 131 of this embodiment, the configuration of the chamber 131 differs from that of the chamber 131 of the comparative example. The chamber 131 of this embodiment mainly comprises a cylindrical inner housing 50, an outer housing 70 that surrounds the inner housing 50 from the outside, and a partition wall 80 that is positioned between the inner housing 50 and the outer housing 70 on the side in the direction of laser beam propagation.

[0054] The inner housing 50, like the chamber 131 of the comparative example, includes an internal space where light is generated from the laser gas, and a wall surface in contact with the internal space. Similar to the internal space of the chamber 131 of the comparative example, electrodes 133a, 133b, an electrical insulation section 135, an electrode holder section 137, a cross-flow fan 149, a heat exchanger 151, and a pre-ionization electrode are arranged within this internal space. The piping for the laser gas supply source and the exhaust pump penetrates the outer housing 70 and communicates with the internal space of the inner housing 50. The longitudinal direction of the inner housing 50 aligns with the direction of laser light propagation within its internal space, and the laser light passes through openings 50a, 50b, which are passage openings at both ends of the cylindrical inner housing 50 in the longitudinal direction. This inner housing 50 surrounds the laser light traveling within its internal space.

[0055] Figure 8 is a perspective view of the outer main body portion 71 of the outer housing 70 that surrounds the inner housing 50 and the partition wall 80. In Figure 8, the portion of the inner housing 50 and the partition wall 80 that is surrounded by the outer main body portion 71 is shown by a dashed line.

[0056] As shown in Figures 7 and 8, the inner housing 50 mainly consists of a rectangular base plate 51a that is long in the longitudinal direction of the inner housing 50, and a pair of semicircular tubular curved plates 51b and 51c. Each of the curved plates 51b and 51c is the same size. When viewing the base plate 51a and the curved plates 51b and 51c along the longitudinal direction of the inner housing 50, the curved plates 51b and 51c are arranged symmetrically with respect to the base plate 51a and are curved so as to bulge outwards from each other. In the width direction, i.e., the X direction, of the base plate 51a perpendicular to the longitudinal direction of the inner housing 50, the outer circumferential surface of one end of the curved plate 51b is fixed to the inner surface of one end of the base plate 51a by brazing, and the outer circumferential surface of one end of the curved plate 51c is fixed to the inner surface of the other end of the base plate 51a by brazing. The curved plates 51b and 51c are brazed at their entire contact points with the base plate 51a. This suppresses the leakage of laser gas from the fixed portion to the outside of the inner housing 50. In addition, a portion of the other end of the curved plates 51b and 51c is bent outward from the inner housing 50 in a direction roughly perpendicular to the bottom plate 51a. Each of the bent other ends is fixed by brazing as described above, and a frame-shaped projection 53 is provided. The frame-shaped projection 53 is a long rectangle in the longitudinal direction of the inner housing 50, and an opening 50c is provided inside the frame-shaped projection 53. The opening 50c is a long rectangle in the longitudinal direction of the inner housing 50 and is closed by the electrical insulation portion 135. Outside the projection 53 in the longitudinal direction of the inner housing 50, the remaining portion of the other end of the curved plates 51b and 51c is bent to face the bottom plate 51a and fixed to each other by brazing. The surfaces of the bottom plate 51a and curved plates 51b and 51c configured in this way that are in contact with the internal space of the inner housing 50 can be understood as the walls of the inner housing 50 that are in contact with the internal space of the inner housing 50.

[0057] The thickness of the bottom plate 51a is greater than the thickness of the curved plates 51b and 51c, which are plates in the inner housing 50 other than the bottom plate 51a. For example, the thickness of the bottom plate 51a is 5 mm to 7 mm, and the thickness of the curved plates 51b and 51c is 1 mm to 3 mm. When the flat bottom plate 51a is thicker than the curved plates 51b and 51c, the strength of the bottom plate 51a is increased compared to when the bottom plate 51a is the same thickness as the curved plates 51b and 51c. Also, when the bottom plate 51a is a flat plate, the volume of the chamber 131 is smaller than when the bottom plate 51a is a curved plate that curves so as to bulge away from the central axis of the inner housing 50. A smaller volume reduces the amount of laser gas consumed from the laser gas supply source, making the entire gas laser device 100 smaller. Examples of materials for the inner housing 50 include stainless steel and aluminum. For stainless steel, SUS316L is preferred.

[0058] As shown in Figure 7, fins 57 are fixed to a portion of the inner circumferential surface of the inner housing 50 by brazing. The fins 57 are brazed over the entire contact area with the inner circumferential surface of the inner housing 50. Figure 7 shows an example in which the fins 57 are fixed to the surface of the bottom plate 51a and the inner circumferential surface of the curved plate 51c. The fins 57 are positioned downstream of the space between electrodes 133a and 133b in the direction of travel of the laser gas circulating in the internal space of the inner housing 50 by the cross-flow fan 149. The fins 57 are positioned to the side of the laser beam's path in the internal space of the inner housing 50 and do not obstruct the laser beam's progress. Heat from the heating medium, which will be described later, is released into the internal space of the inner housing 50 via the fins 57. The fins 57 are not shown in drawings other than Figure 7 and Figure 9, which will be described later. The surface of the fins 57 that is in contact with the internal space of the inner housing 50 can be understood as the wall surface of the inner housing 50 that is in contact with the internal space of the inner housing 50.

[0059] As shown in Figures 6, 7, and 8, the outer housing 70 surrounds the inner housing 50 from the sides, front, and rear in the direction of laser beam propagation. This outer housing 70 mainly consists of an outer body 71, a cover plate 73, a front plate 75, and a rear plate 77.

[0060] The outer body portion 71 is a plate that surrounds the inner housing 50 from the side and includes an opening 70c on the side. The cross-section of such an outer body portion 71 is, for example, U-shaped, and the outer body portion 71 is positioned opposite the bottom plate 51a, curved plates 51b, 51c, and projection 53 of the inner housing 50 on the side. The outer body portion 71 is approximately the same length as the inner housing 50, and the longitudinal direction of the outer body portion 71 is aligned with the longitudinal direction of the inner housing 50.

[0061] The cover plate 73 is positioned at both ends of the outer body portion 71 and at the openings 70c at both ends, covering the openings 70c on the outer body portion 71. The cover plate 73 is provided with openings 73c into which the projections 53 of the inner housing 50 fit. A groove is also provided on the upper surface of the cover plate 73. The groove is provided around the openings 73c and is rectangular in shape, elongated in the longitudinal direction of the inner housing 50. A sealing member 79 is placed in the groove to seal the space between the cover plate 73 and the electrical insulation portion 135. The sealing member 79 is, for example, a metal seal.

[0062] Furthermore, the cover plate 73 includes a projection 73a that protrudes outward from the side surface of the outer body portion 71 in the X direction perpendicular to the longitudinal direction of the outer body portion 71. The side surface is the surface of the bottom plate 51a of the inner housing 50 that faces the curved plates 51b and 51c of the outer body portion 71 in the width direction. The projections 73a are provided on each end of the cover plate 73 in the X direction perpendicular to the longitudinal direction. Each projection 73a bends toward the side surface of the outer body portion 71 relative to the cover plate 73 so as to surround that side surface. When the projections 73a bend in this way, the projections 73a can be shorter compared to the case where the projections 73a bend toward the side surface of the outer body portion 71, in order for the cover plate 73 to have the same rigidity in each case. Therefore, the weight of the chamber 131 can be reduced. The bending angle of the projections 73a is, for example, 25° or more and 35° or less. Furthermore, the length of the protrusion 73a is, for example, 100 mm or more and 150 mm or less. This length is the length from the bent portion of the protrusion 73a to the end furthest from the bent portion, and not the length between the side surface of the outer main body portion 71 and that end. In Figure 7, an example is shown where the bent portion is located to the side of the side surface, but it may also be located at the edge of the side surface.

[0063] Furthermore, the in-plane direction of the planar area of ​​the cover plate 73, excluding the protruding portion 73a, is parallel to the in-plane direction of the bottom plate 51a, and the protruding portion 73a may protrude outward along the in-plane direction beyond the side surface of the outer main body portion 71. Alternatively, the protruding portion 73a may be bent to the opposite side of the outer main body portion 71. The length of the protruding portion 73a is shortest when it is bent toward the side surface of the outer main body portion 71, and increases in the order of when it is bent toward the side surface of the outer main body portion 71, when it is bent to the opposite side of the outer main body portion 71, and when it protrudes along the in-plane direction.

[0064] Compared to the case where the protrusion 73a is not provided, the rigidity of the cover plate 73 is increased when the protrusion 73a is provided. Therefore, even if the inner housing 50 tries to deform, the cover plate 73 can suppress the deformation of the inner housing 50, and the deformation of the cover plate 73 due to the deformation of the inner housing 50 can also be suppressed. In addition, because the deformation of the cover plate 73 is suppressed, the thickness of the cover plate 73 including the protrusion 73a can be reduced. Therefore, even if the protrusion 73a is provided, the weight of the chamber 131 can be reduced, and the handling of the chamber 131 can be made easier.

[0065] As shown in Figure 6, the front panel 75 is positioned along the longitudinal direction of the inner housing 50 and the outer main body 71, at the opening 50a and its peripheral edge on one end of the inner housing 50, and at the opening and its peripheral edge on one end of the outer housing 70. The front panel 75 is provided with an opening 75a. The opening 75a is approximately the same size and shape as the opening 50a of the inner housing 50, and when the front panel 75 is attached to one end of the inner housing 50 and one end of the outer main body 71, it overlaps with the opening 50a. An output-side holder (not shown) for holding the output coupling mirror 147 is attached to the front panel 75. The output-side holder is attached to the front panel 75 so that the output coupling mirror 147 faces the opening 50a. In this embodiment, a window 139b is not provided.

[0066] The rear panel 77 is positioned along the longitudinal direction of the inner housing 50 and the outer main body 71, specifically at the opening 50b and its peripheral edge on the other end of the inner housing 50, and at the opening and its peripheral edge on the other end of the outer housing 70. The rear panel 77 is provided with an opening 77a, which will be described later in Figure 9. The opening 77a will be described later.

[0067] Since the outer housing 70 is provided with a partition wall 80, the strength of the outer housing 70 may be lower than that of the inner housing 50. For this reason, the thickness of each of the outer body 71, lid plate 73, front plate 75, and rear plate 77 may be thinner than the thickness of the inner housing 50. If each of the plates is thinner, the weight of the chamber 131 will be less than if each of the plates is the same as or thicker than the thickness of the inner housing 50. The thickness of each of the outer body 71, lid plate 73, front plate 75, and rear plate 77 is, for example, 1 mm or more and 3 mm or less. The material of the outer body 71, lid plate 73, front plate 75, and rear plate 77 can be the same as that of the inner housing 50, for example, stainless steel or aluminum.

[0068] As shown in Figures 7 and 8, there are multiple partition walls 80, each of which is a support member that supports the inner housing 50, the outer main body 71, and the cover plate 73 excluding the protruding portion 73a. The partition walls 80 are fixed to the outer circumferential surface of the inner housing 50 and the inner circumferential surface of the outer housing 70 by brazing. The partition walls 80 are brazed at the entire contact portion with the outer circumferential surface of the inner housing 50 and the entire contact portion with the inner circumferential surface of the outer housing 70. The inner circumferential surface of the outer housing 70 refers to the inner circumferential surface of the outer main body 71 and the back surface of the cover plate 73 excluding the protruding portion 73a.

[0069] Each partition wall 80 is positioned parallel to the inner housing 50 at predetermined intervals along its longitudinal direction, with the in-plane direction of the partition wall 80 being approximately perpendicular to the longitudinal direction of the inner housing 50. Therefore, the surface of one partition wall 80 faces the back surface of an adjacent partition wall 80, and adjacent partition walls 80 are positioned with a gap between them. The partition walls 80 divide the gap between the inner housing 50 and the outer main body 71 in a direction perpendicular to the longitudinal direction of the inner housing 50, and also divide the gap front to back along the longitudinal direction of the inner housing 50. Gaps are also provided between the front panel 75 and the partition wall 80 adjacent to the front panel 75, and between the rear panel 77 and the partition wall 80 adjacent to the rear panel 77. Figure 8 shows an example in which 11 partition walls 80 are arranged, but at least one partition wall 80 is sufficient.

[0070] Figure 9 shows the positional relationship between the fins 57 and the partition walls 80. As shown in Figure 9, multiple fins 57 are arranged on the inner circumferential surface of the inner housing 50. Each fin 57, like the partition walls 80, is arranged in parallel with a predetermined interval in the longitudinal direction of the inner housing 50, with the in-plane direction of the fin 57 being approximately perpendicular to the longitudinal direction of the inner housing 50. The partition walls 80 and fins 57 are arranged alternately along the longitudinal direction of the inner housing 50. It is preferable that the fins 57 are positioned approximately midway between adjacent partition walls 80 in the longitudinal direction of the inner housing 50. Therefore, the length between adjacent partition walls 80 is approximately the same as the length between adjacent fins 57. Note that if the lengths between them are the same, the fins 57 do not necessarily have to be positioned approximately midway between adjacent partition walls 80. Figure 9 shows an example in which multiple fins 57 are arranged, but there may be only one fin 57, or there may be no fins at all. Furthermore, multiple fins 57 may be arranged along the circumferential direction of the inner housing 50. In this case, adjacent fins 57 may be spaced apart from each other or touching each other. An opening 77a is provided in the rear panel 77. The opening 77a is approximately the same size and shape as the opening 50b of the inner housing 50 (not shown in Figure 9), and overlaps with the opening 50b when the rear panel 77 is attached to the other end of the inner housing 50 and the other end of the outer main body 71. The housing 145a of the narrowband module 145 is attached to the rear panel 77. The housing 145a is attached to the rear panel 77 such that the prism 145b faces the opening 50b of the inner housing 50. In this embodiment, a window 139a is not provided. The laser light travels back and forth between the internal space of the inner housing 50 and the prism 145b (not shown in Figure 9) through the opening 77a.

[0071] The chamber 131 of this embodiment includes a cooling passage 91 provided on the outside of the wall surface of the chamber 131 that is in contact with the internal space of the chamber 131 that generates laser light. The cooling passage 91 is configured to carry a cooling medium, which will be described later, for cooling the chamber 131. The cooling passage 91 of this embodiment is provided between the inner housing 50 and the outer housing 70. As described above, a gap is separated between the inner housing 50 and the outer housing 70 by a partition wall 80, and the cooling passage 91 is this gap. The cooling passage 91 is provided so as to be in contact with an area of ​​50% or more of the outer surface of the inner housing 50.

[0072] In such cooling passages 91, a cooling medium flows to cool the inner housing 50 when laser light is generated from the laser gas in the internal space during the full operation of the gas laser apparatus 100 after baking. Examples of cooling mediums include liquids such as water and oil, and gases such as water vapor.

[0073] As shown in Figures 7, 8, and 9, the chamber 131 is located at the same position as the partition wall 80 in the longitudinal direction of the inner housing 50 and further includes a passage 80a through which a cooling medium flows from one of the adjacent cooling passages 91 via the partition wall 80 to the other cooling passage 91 adjacent to that cooling passage 91. In this embodiment, the passage 80a is shown as an opening provided in the partition wall 80. The passage 80a is part of the cooling passage 91. The cooling medium flows from the front panel 75 side to the rear panel 77 side, passing from the cooling passage 91 on the front panel 75 side through passage 80a to the cooling passage 91 on the rear panel 77 side that is adjacent to that cooling passage 91.

[0074] When viewed along the longitudinal direction of the inner housing 50, the passage 80a of one of the adjacent partition walls 80 is positioned so as not to overlap with the passage 80a of the other partition wall 80. Furthermore, Figures 7, 8, and 9 show an example in which, when viewed along the longitudinal direction of the inner housing 50, the passage 80a of one partition wall 80 is positioned on the opposite side from the passage 80a of the other partition wall 80, with reference to the non-flow region in the cooling passage 91 where the cooling medium does not flow. The non-flow region is the area between the protrusions 53 of the curved plates 51b and 51c in the in-plane direction of the bottom plate 51a. When viewed along the longitudinal direction of the inner housing 50, for example, the cooling medium flows clockwise in the circumferential direction of the inner housing 50 through the cooling passage 91 on the front plate 75 side, and counterclockwise in the circumferential direction through the cooling passage 91 on the rear plate 77 side that is adjacent to the said cooling passage 91. Therefore, the cooling medium flows in opposite directions in each of the adjacent cooling passages 91. The flow of the cooling medium in each cooling passage 91 is illustrated by dashed arrows in Figure 8. For ease of viewing, only one flow is shown in Figure 8. In the cooling passage 91, as described above, the partition wall 80 is brazed at the entire contact portion with the outer circumferential surface of the inner housing 50 and the entire contact portion with the inner circumferential surface of the outer housing 70. Therefore, leakage of the cooling medium from these contact portions is suppressed, and the cooling medium flows from one of the adjacent cooling passages 91 to the other via passage 80a. During the full operation of the gas laser apparatus 100 after baking, the cooling medium flows through the cooling passages 91 and passage 80a. As a result, the cooling medium comes into contact with the inner housing 50 and directly cools the inner housing 50. Cooling can suppress the temperature rise of the inner housing 50 due to laser light in the internal space of the inner housing 50, and can suppress deformation of the inner housing 50 due to the temperature rise.

[0075] Incidentally, a heating medium flows through the cooling passage 91 to heat the internal space of the chamber 131 during baking before the gas laser device 100 is put into full operation. Therefore, the cooling passage 91 is used for both the heating medium and the cooling medium. Preferably, the heating medium is made of the same material as the cooling medium, but it may be made of a different material. The heating medium flows through the cooling passage 91 and passage 80a in the same way as the flow of the cooling medium described above.

[0076] Figure 10 shows the arrangement of the chamber 131 during baking in this embodiment. Figure 10 shows a simplified illustration of the chamber 131. A pipe 93a is connected to an inlet 75d provided on the front plate 75 of the chamber 131, and a pipe 93b is connected to an outlet 77d provided on the rear plate 77. Pipes 93a and 93b are connected to a heat exchanger 95 located in the outer housing 70, i.e., the space outside the chamber 131. The heat exchanger 95 supplies a heating medium through the pipe 93a to the cooling passage 91 between the inner housing 50 and the outer main body 71 using a pump (not shown) of the heat exchanger 95, and heats the internal space of the inner housing 50 with the heating medium. The heat exchanger 95 circulates the heating medium in the following order: heat exchanger 95, pipe 93a, cooling passage 91, passage 80a, pipe 93b, and heat exchanger 95. Note that the heat exchanger 95 may circulate the heating medium in the reverse order. The cooling passage 91 is also the cooling passage 91 between the front panel 75 and the partition wall 80 adjacent to the front panel 75, the cooling passage 91 between adjacent partition walls 80, and the cooling passage 91 between the rear panel 77 and the partition wall 80 adjacent to the rear panel 77. Each cooling passage 91 between adjacent partition walls 80 is surrounded by the partition wall 80, the curved panels 51b, 51c, the projection 53, the outer main body 71, and the cover plate 73.

[0077] The temperature of the internal space of the inner housing 50 is measured by a temperature sensor (not shown). The heat exchanger 95 adjusts the temperature of the heating medium based on the measured temperature of the internal space. The set temperature of the heating medium is, for example, 150°C or higher.

[0078] One pipe 303a connected to the vacuum pump 303 penetrates the outer housing 70 and communicates with the internal space of the inner housing 50. The other pipe 303b connected to the vacuum pump 303 communicates with the outside. The vacuum pump 303 draws impurities from the gas in the internal space heated by the heating medium through pipe 303a and exhausts the gas to the outside of the chamber 131 through pipe 303b. These impurities include desorbed moisture.

[0079] Next, a configuration for flowing a cooling medium through the cooling passage 91 will be described. This configuration is used when laser light is generated from the laser gas in the internal space during the full operation of the gas laser apparatus 100 after baking. When flowing the cooling medium through the cooling passage 91, the vacuum pump 303 is removed, and a temperature controller (not shown) is installed in place of the heat exchanger 95. The temperature controller is located inside the housing 110 of the gas laser apparatus 100. The temperature controller is a chiller that supplies the cooling medium to the cooling passage 91 between the inner housing 50 and the outer main body 71 through piping 93a using a pump (not shown) of the temperature controller, and cools the inner housing 50 with the cooling medium. The cooling medium circulates in the same way as the heating medium. The temperature controller is electrically connected to the laser processor 190, and the laser processor 190 outputs a signal indicating the temperature of the cooling medium to the temperature controller based on the signal from the temperature sensor. The temperature controller adjusts the temperature of the cooling medium based on the signal from the laser processor 190. The set temperature of the cooling medium is preferably, for example, 20°C to 70°C, and the temperature range of the cooling medium flowing through the cooling passage 91 is preferably ±3°C of the set temperature.

[0080] 3.2 Baking method for the chamber Figure 11 is a diagram showing an example of a flowchart of the baking method in this embodiment. The baking method in this embodiment includes a preparation step SP21, a heating step SP22, and an exhaust step SP23.

[0081] (Preparation Step SP21) In this step, the chamber 131 is mounted on the housing 110 of the gas laser device 100, specifically installed inside the housing 110. Piping 93a, 93b, 303a, and 303b are connected to the chamber 131. In other words, the heat exchanger 95 and vacuum pump 303 are connected to the chamber 131. The heating medium is then heated to 150°C or higher by the heat exchanger 95. Once these preparations are complete, the process proceeds to the heating step SP22.

[0082] (Heating step SP22) In this step, the heating medium flows from the heat exchanger 95 through piping 93a to the cooling passage 91, transferring heat from the inner housing 50 to the internal space of the inner housing 50, and from the inner housing 50 to the internal space of the inner housing 50 via the fins 57. This raises the temperature of the internal space of the inner housing 50 to 150°C or higher, heating the internal space of the inner housing 50. Due to the heating, moisture adsorbed on the internal components of the chamber 131 is released from the internal components. The heating medium returns to the heat exchanger 95 through piping 93b from the cooling passage 91, where it is heated again to 150°C or higher, and flows back to the cooling passage 91 through piping 93a. Thus, the heating medium circulates through the heat exchanger 95, piping 93a, cooling passage 91, piping 93b, and heat exchanger 95. When the temperature of the internal space reaches 150°C or higher, the flow proceeds to the exhaust step SP23.

[0083] (Exhaust step SP23) In this step, similar to the exhaust step SP13, the desorbed moisture-containing gas impurities are exhausted from the heated internal space of the chamber 131 to the external space of the chamber 131 by the vacuum pump 303.

[0084] At least a portion of this step may overlap with the heating step SP22 and may be performed simultaneously with the heating step SP22. Furthermore, this step may be completed before the heating step SP22, simultaneously with the heating step SP22, or after the heating step SP22. The time from the start of the heating step SP22 to the completion of the later of the two steps, the heating step SP22 and the exhaust step SP23, is 8 hours or more.

[0085] In this step, once the gas is exhausted, the flow ends because the chamber 131 is already installed inside the housing 110 of the gas laser device 100, as described in preparation step SP21. The gas laser device 100 then goes into standby mode for full operation.

[0086] 3.3 Action and Effects The baking method of this embodiment includes a heating step SP22 in which a heating medium is flowed through a cooling passage 91 to heat the internal space of the chamber 131 via the wall surface, before light is generated in the internal space of the chamber 131, and an exhaust step SP23 in which the gas in the heated internal space is exhausted to the external space of the chamber 131.

[0087] In this baking method, the internal space is heated as the heating medium flows through the cooling passage 91. Due to the heating, moisture adsorbed on internal components of the chamber 131, such as the electrodes 133a placed inside the chamber 131, is released from the internal components, and the moisture is exhausted to the outside of the chamber 131 along with the gas in the internal space. In this baking method, there is no gap between the chamber 131 and the mantle heater 301, compared to the case where the mantle heater 301 is wrapped around the chamber 131 to heat the internal space of the chamber 131. Therefore, the internal space can be heated up in a short time, and the baking period can be shortened.

[0088] Furthermore, in the baking method of this embodiment, the chamber 131 comprises an inner housing 50 and an outer housing 70 that surrounds the inner housing 50 from the side in the direction of light propagation. The cooling passage 91 is provided between the inner housing 50 and the outer housing 70. In this baking method, since the cooling passage 91 is provided between the inner housing 50 and the outer housing 70, it is possible to eliminate the need to install the chamber 131 in the baking equipment.

[0089] Furthermore, in the baking method of this embodiment, the chamber 131 is positioned between the inner housing 50 and the outer housing 70 and further comprises a partition wall 80 fixed to the inner housing 50 and the outer housing 70.

[0090] In the chamber 131, when the internal space of the inner housing 50 is heated by the heating medium, the temperature of the internal space may rise, causing an uneven temperature distribution within that space. Also, the exhaust of gas from the internal space of the inner housing 50 may cause a decrease in pressure within that space. The inner housing 50 will attempt to deform due to thermal expansion caused by the temperature rise, the difference in thermal expansion within the internal space of the inner housing 50 due to the uneven temperature distribution, and the decrease in pressure. However, in this configuration, this deformation of the inner housing 50 can be suppressed by the partition wall 80 fixed to the outer circumferential surface of the inner housing 50 and the outer housing 70 to which the partition wall 80 is fixed. For example, even if the inner housing 50 attempts to deform by expanding due to thermal expansion, the expansion of the inner housing 50 can be suppressed by the partition wall 80 and the outer housing 70. Similarly, even if the inner housing 50 attempts to deform by contracting due to a decrease in pressure, the contraction of the inner housing 50 can be suppressed by the partition wall 80 and the outer housing 70. By suppressing the deformation of the inner housing 50 in this way, the change in the direction of propagation of the laser light emitted from the inner housing 50 after the baking is completed from the pre-expected direction of propagation can be suppressed. By suppressing this change, the change in the direction of propagation of the light emitted from the gas laser device 100 toward the exposure device 200 from the pre-expected direction of propagation can be suppressed. Therefore, a decrease in the reliability of the gas laser device 100 can be suppressed.

[0091] Furthermore, since the partition wall 80 and outer housing 70 suppress deformation of the inner housing 50, the thickness of the inner housing 50 may be thinner compared to the state without the partition wall 80 and outer housing 70. Therefore, even with the partition wall 80 and outer housing 70 in place, the weight of the chamber 131 may be reduced, making it easier to handle. Also, in order to suppress deformation of the inner housing 50 when the partition wall 80 and outer housing 70 are not provided, it is necessary to increase the rigidity of the inner housing 50. In the baking method of this embodiment, since the partition wall 80 and outer housing 70 suppress deformation of the inner housing 50, it is possible to suppress an increase in the thickness of the inner housing 50. In addition, in the baking method of this embodiment, the rigidity of the chamber 131 may be increased by the partition wall 80 and outer housing 70.

[0092] Furthermore, in the baking method of this embodiment, there are multiple partition walls 80, and each partition wall 80 is arranged in parallel with a gap between them in the direction of light propagation. In this case, compared to the case where there is only one partition wall 80, deformation of the inner housing 50 can be suppressed and the rigidity of the chamber 131 can be increased.

[0093] Furthermore, in the baking method of this embodiment, the chamber 131 is provided at the same position as the partition wall 80 in the direction of light propagation, and further includes a passage 80a through which the heating medium flows from one of the adjacent cooling passages 91 to the other. If the passage 80a is not provided, it would be necessary to connect piping to each cooling passage 91 for the heating medium to flow through each cooling passage 91. However, by providing the passage 80a, it becomes unnecessary to connect piping to each cooling passage 91, and the weight of the chamber 131 can be reduced. In addition, by providing an inlet 75d on the front plate 75 and an outlet 77d on the rear plate 77, the heating medium can circulate through the cooling passages 91 by flowing through each cooling passage 91.

[0094] Alternatively, the passages 80a may not be provided in each partition wall 80, and piping may be connected to each cooling passage 91 so that the heating medium flows through each cooling passage 91. When the heating medium circulates as described above, the temperature of the heating medium decreases as it flows from the upstream side to the downstream side, and the internal space of the inner housing 50 may not be heated to the expected temperature. However, when the heating medium flows through each cooling passage 91, the temperature change of the heating medium can be suppressed compared to when the heating medium circulates as described above, and the internal space of the inner housing 50 can be heated.

[0095] The passages 80a do not need to be located in all partition walls 80. For example, if a passage 80a is not provided in the fifth partition wall 80 from the front panel 75 side, the first to fifth cooling passages 91 from the front panel 75 side become one flow path, and the sixth to twelfth cooling passages 91 from the front panel 75 side become separate cooling passages 91 from the above cooling passage 91. In this case, piping may be connected to each cooling passage 91 and a heating medium may flow through each cooling passage 91. Also, multiple passages 80a may be provided in a single partition wall 80.

[0096] Furthermore, in the baking method of this embodiment, when viewed along the direction of light propagation, the passage 80a of one of the adjacent partition walls 80 is positioned so as not to overlap with the passage 80a of the other partition wall 80. As a result, the heating medium can flow in opposite directions in each of the adjacent cooling passages 91.

[0097] Furthermore, in the baking method of this embodiment, the heating medium is made of the same material as the cooling medium. If the heating medium is made of a different material, for example, if the cooling medium flows into the cooling passage 91 after the heating medium, some heating medium may remain in the cooling passage 91, and even if the cooling medium flows into the cooling passage 91, the chamber 131 may not be cooled effectively by the heating medium remaining in the cooling passage 91. For this reason, the cooling passage 91 may need to be cleaned to remove the heating medium. However, in this configuration, since the heating medium is made of the same material as the cooling medium, even if some heating medium remains, there is no need to remove it, and cleaning of the cooling passage 91 can be made unnecessary.

[0098] Furthermore, in the baking method of this embodiment, the heating medium is heated by a heat exchanger 95 located in the space outside the chamber 131. This configuration allows for a reduction in the size of the chamber 131 compared to the case where the heat exchanger 95 is located inside the chamber 131. Note that the heat exchanger 95 does not necessarily have to be located in the space outside the chamber 131.

[0099] Furthermore, in the baking method of this embodiment, the heating step SP22 and the exhaust step SP23 are performed with the chamber 131 mounted on the housing 110 of the gas laser device 100. With this configuration, once baking of the chamber 131 is complete, laser light can be emitted from the gas laser device 100 without moving the chamber 131.

[0100] Furthermore, in the baking method of this embodiment, at least a portion of the exhaust step SP23 is performed simultaneously with the heating step SP22. This configuration allows for a shorter baking period compared to the case where the exhaust step SP23 is performed after the completion of the heating step SP22.

[0101] Furthermore, in the baking method of this embodiment, the fins 57 are arranged on the inner circumferential surface of the inner housing 50, and the heat from the heating medium is released into the internal space of the inner housing 50 via the fins 57. When the fins 57 are arranged, the amount of heat dissipated increases compared to when the fins 57 are not arranged, making it easier to raise the temperature of the internal space of the inner housing 50.

[0102] Furthermore, in the baking method of this embodiment, there are multiple fins 57. In this case, the amount of heat dissipated increases compared to when there is only one fin 57. When the amount of heat dissipated increases, the internal space of the chamber 131 can be heated up in an even shorter time, and the baking period can be further shortened.

[0103] Furthermore, in the baking method of this embodiment, the partition walls 80 and fins 57 are arranged alternately along the direction of light propagation. The rigidity of the inner housing 50 between adjacent partition walls 80 is lower than the rigidity of the inner housing 50 in the portion where the partition walls 80 are located. When the partition walls 80 and fins 57 are arranged alternately as described above, the rigidity of the inner housing 50 between adjacent partition walls 80 is higher than when the partition walls 80 are arranged adjacent to the fins 57 via the inner housing 50. Note that the fins 57 may also be arranged adjacent to the partition walls 80 via the inner housing 50.

[0104] Furthermore, in the baking method of this embodiment, the fins 57 are positioned between adjacent partition walls 80. In this case, compared to the case where the fins 57 are positioned biasedly toward one of the adjacent partition walls 80, changes in the strength distribution of the inner housing 50 in the longitudinal direction of the inner housing 50 can be suppressed, and deformation of the inner housing 50 can be suppressed. Note that the length between adjacent partition walls 80 may differ from the length between adjacent fins 57.

[0105] In this embodiment, the chamber 131 is located in the internal space of the inner housing 50. The heat exchanger 151 may heat the heating medium flowing through it. In the heating step SP22, the heating medium may be further passed through the heat exchanger 151, and the internal space may be further heated by heating the heating medium in the heat exchanger 151. This configuration allows the internal space to be heated in an even shorter time, further shortening the baking period. In the heating step SP22, the heating medium may not be passed through the heat exchanger 151, and the internal space may not be further heated.

[0106] Figure 12 is a cross-sectional view of the chamber 131 in a modified example. In Figure 12, the configuration of the chamber 131 is briefly described, and the internal components and electrical insulation part 135 in the internal space of the chamber 131 are not shown. The chamber 131 in this modified example includes a wall portion 131a. This wall portion 131a is provided with a wall surface that is in contact with the internal space of the chamber 131. The cooling passage 91 in this modified example may be provided inside the wall portion 131a. The inlet and outlet of the cooling passage 91, which are not shown, are provided on the front of the chamber 131. Between the inlet and outlet, the cooling passage 91 extends from the front side toward the back side in the direction of laser beam propagation, i.e., the Z direction, and then folds back toward the front side on the back side and extends toward the front side along the Z direction. The cooling passage 91 also folds back toward the back side on the front side and extends toward the back side along the Z direction. In such a cooling passage 91, the cooling medium and heating medium flow in opposite directions in each of the adjacent cooling passages 91.

[0107] In the chamber 131 of this embodiment, the passage 80a is an opening, but it is not limited to this. For example, a part of the partition wall 80 may be positioned away from at least one of the inner housing 50 and the outer housing 70, and the passage 80a may be a gap between that part and at least one of the inner housing 50 and the outer housing 70. As an example of such a passage 80a, a part of the partition wall 80 may be positioned away from the other end of the curved plate 51b and the projection 53 on the curved plate 51b side, and a gap formed between the other end of the curved plate 51b, the projection 53, the partition wall 80 and the cover plate 73. Note that this gap may be provided on the curved plate 51c side. Alternatively, the passage 80a may be formed by a notch provided in the partition wall 80 and a cover plate 73 that closes the opening in the notch.

[0108] The outer housing 70 may enclose at least a portion of the inner housing 50. The outer housing 70 may enclose the inner housing 50 at least from the side in the direction of laser beam propagation. The outer main body 71 may be longer or shorter than the inner housing 50.

[0109] The fins 57 may be fixed by welding to the inner circumferential surface of the inner housing 50, and the partition wall 80 may be fixed by welding to the outer circumferential surface of the inner housing 50 and the inner circumferential surface of the outer housing 70. The fins 57 may also be positioned on the outer circumferential surface of the outer housing 70.

[0110] The members positioned between the inner housing 50 and the outer housing 70 and fixed to each of them are not limited to partition walls 80. The members only need to support the inner housing 50, the outer main body portion 71, and the cover plate 73 excluding the protruding portion 73a. Examples of such members include rod-shaped members that support the inner housing 50 and the outer main body portion 71 of the outer housing 70. There may be multiple rod-shaped members, and they may extend radially from the outer circumferential surface of the inner housing 50 to the inner circumferential surface of the outer main body portion 71 and the back surface of the cover plate 73 excluding the protruding portion 73a, with the central axis of the inner housing 50 as the reference point, like spokes. Alternatively, multiple partition walls 80 may be arranged along the circumferential direction of the inner housing 50. In this case, adjacent partition walls 80 may be positioned far apart from each other or in contact with each other.

[0111] Temperature sensors may be provided in the cooling passage 91 and the pipes 93a and 93b. The temperature sensors measure the temperature of the heating medium flowing through them. The heat exchanger 95 may then adjust the temperature of the heating medium based on the measured temperature. Although this explanation uses a heating medium, the same applies to a cooling medium.

[0112] The above description is intended to be illustrative and not restrictive. It will therefore be apparent to those skilled in the art that modifications can be made to the embodiments of this disclosure without departing from the claims. It will also be apparent to those skilled in the art that the embodiments of this disclosure can be used in combination. Terms used in this specification and throughout the claims should be interpreted as "non-limiting" unless otherwise specified. For example, terms such as "includes," "have," "equip," and "possess" should be interpreted as "not excluding the existence of components other than those described." Also, the modifier "one" should be interpreted as "at least one" or "one or more." Furthermore, the term "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," and should also be interpreted as including combinations of these with anything other than "A," "B," and "C."

Claims

1. A method for baking a chamber of a gas laser apparatus, wherein a cooling passage is provided on the outside of the wall surface in contact with the internal space of the chamber that generates light in the internal space, and the cooling passage is configured to flow a cooling medium for cooling the chamber, A heating step in which, before generating the light in the internal space, a heating medium is flowed through the cooling passage and the internal space is heated via the wall surface, An exhaust step of exhausting the gas in the heated internal space to the external space of the chamber, Equipped with, The chamber comprises a partition wall including the wall surface, The cooling passage is provided inside the partition wall. A method for baking the chamber of a gas laser apparatus.

2. A method for baking the chamber of a gas laser apparatus according to claim 1, The aforementioned chamber is The inner housing includes the aforementioned wall surface, the aforementioned internal space, and the aforementioned internal space which includes an opening through which the light passes, An outer housing that surrounds at least a part of the inner housing from the side in the direction of light propagation, Equipped with, The cooling passage is provided between the inner housing and the outer housing.

3. A method for baking the chamber of a gas laser apparatus according to claim 2, The inner and outer casings are made of stainless steel.

4. A method for baking the chamber of a gas laser apparatus according to claim 2, The cooling passage is provided so as to be in contact with an area of ​​50% or more of the outer surface of the inner housing.

5. A method for baking the chamber of a gas laser apparatus according to claim 2, The chamber is positioned between the inner housing and the outer housing and further comprises a partition wall fixed to the inner housing and the outer housing.

6. A method for baking the chamber of a gas laser apparatus according to claim 5, The aforementioned partitions are multiple. Each of the aforementioned partitions is arranged in parallel with a gap between them in the direction of light propagation.

7. A method for baking the chamber of a gas laser apparatus according to claim 5, The gap between the inner housing and the outer housing, separated by the partition wall, is the cooling passage.

8. A method for baking the chamber of a gas laser apparatus according to claim 7, The chamber is provided at the same position as the partition wall in the direction of light propagation and further includes a passage through which the heating medium flows from one of the adjacent cooling passages to the other.

9. A method for baking the chamber of a gas laser apparatus according to claim 8, The aforementioned partition wall is multiple, Each of the aforementioned partitions is arranged in parallel with respect to the direction of light propagation, with a gap between them. When viewed along the direction of light propagation, the passage provided at the same position in the direction of light propagation as one of the adjacent partitions is provided at a position that does not overlap with the passage provided at the same position in the direction of light propagation as the other partition adjacent to the one partition.

10. A method for baking the chamber of a gas laser apparatus according to claim 1, The heating medium is made of the same material as the cooling medium.

11. A method for baking the chamber of a gas laser apparatus according to claim 1, The heating medium is oil or water.

12. A method for baking the chamber of a gas laser apparatus according to claim 1, The temperature of the heating medium is 150°C or higher.

13. A method for baking the chamber of a gas laser apparatus according to claim 1, The heating medium is heated by a heat exchanger located in the space outside the chamber.

14. A method for baking the chamber of a gas laser apparatus according to claim 1, The heating step and the exhaust step are performed with the chamber mounted in the housing of the gas laser device.

15. A method for baking the chamber of a gas laser apparatus according to claim 1, At least a portion of the exhaust step is performed simultaneously with the heating step.

16. A method for baking the chamber of a gas laser apparatus according to claim 1, The time from the start of the heating step to the end of the later of the heating and exhaust steps is 8 hours or more.

17. A method for baking the chamber of a gas laser apparatus according to claim 1, In the heating step, the heating medium is further passed through a heat exchanger provided in the internal space, thereby further heating the internal space.

18. A method for baking a chamber of a gas laser apparatus, wherein a cooling passage is provided on the outside of the wall surface in contact with the internal space of the chamber that generates light in the internal space, and the cooling passage is configured to flow a cooling medium for cooling the chamber, A heating step in which, before generating the light in the internal space, a heating medium is flowed through the cooling passage and the internal space is heated via the wall surface, An exhaust step of exhausting the gas in the heated internal space to the outside of the chamber, Equipped with, The chamber comprises a partition wall including the wall surface, The cooling passage is provided inside the partition wall. A gas laser device equipped with a chamber that is baked by a baking method generates laser light, The laser light is output to the exposure apparatus, To manufacture an electronic device, the laser light is exposed onto a photosensitive substrate within the exposure apparatus. A method for manufacturing electronic devices including

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