Gas laser chamber, gas laser apparatus, and method for manufacturing electronic devices

Abstract

This chamber for gas laser apparatus in which a laser gas is enclosed in an inner space is provided with: an anode which is disposed in the inner space and the longitudinal direction of which is along a predetermined direction; a cathode which is disposed in the inner space and includes a base and an electric discharge portion protruding from the base toward the anode, the longitudinal direction of which is along the predetermined direction, and which faces the anode, there being a gap between the cathode and the anode; a cathode-side cover which is disposed in the inner space, is separated from a portion of the base and the electric discharge portion, and covers the base; and a cathode-side sound absorption member which is provided in a gap between the portion of the base and the cathode-side cover.

Description

Technical Field

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

Background Art

[0002] In recent years, in semiconductor exposure apparatuses, with the miniaturization and high integration of semiconductor integrated circuits, an improvement in resolution has been demanded. For this reason, 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 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 light 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 to such an extent that chromatic aberration can be ignored. For this reason, a narrowbanding module (Line Narrowing Module: LNM) including a narrowbanding element (such as an etalon or a grating) may be provided in the laser resonator of the gas laser device to narrow the spectral linewidth. Hereinafter, a gas laser device whose spectral linewidth is narrowed is referred to as a narrowbanded gas laser device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] A chamber for a gas laser apparatus according to one aspect of the present disclosure is a chamber for a gas laser apparatus that seals a laser gas in an internal space, and may include an anode disposed in the internal space with its longitudinal direction aligned with a predetermined direction, a base and a discharge portion protruding from the base toward the anode, a cathode disposed in the internal space with its longitudinal direction aligned with a predetermined direction and spaced apart from the anode, a cathode-side cover disposed in the internal space, spaced apart from a part of the base and the discharge portion, and covering the base, and a cathode-side sound-absorbing member provided in the gap between a part of the base and the cathode-side cover.

[0006] A gas laser apparatus according to one aspect of the present disclosure is a gas laser apparatus comprising a chamber for sealing a laser gas in an internal space, wherein the chamber comprises an anode disposed in the internal space and having its longitudinal direction along a predetermined direction, a cathode disposed in the internal space and including a discharge portion protruding from the base toward the base and toward the anode, having its longitudinal direction along a predetermined direction and being spaced apart from the anode and facing it, a cathode-side cover disposed in the internal space, spaced apart from a part of the base and the discharge portion and covering the base, and a cathode-side sound-absorbing member provided in the gap between a part of the base and the cathode-side cover.

[0007] A method for manufacturing an electronic device according to one aspect of the present disclosure is a gas laser device chamber for sealing a laser gas in an internal space, comprising: an anode disposed in the internal space and having its longitudinal direction along a predetermined direction; a cathode disposed in the internal space and including a discharge portion protruding from the base toward the base and toward the anode, having its longitudinal direction along a predetermined direction and spaced apart from the anode and facing it; a cathode-side cover disposed in the internal space and spaced apart from a part of the base and the discharge portion and covering the base; and a cathode-side sound-absorbing member provided in the gap between a part of the base and the cathode-side cover. Laser light may be generated by the gas laser device, the laser light may be output to an exposure device, and the laser light may be exposed onto a photosensitive substrate in the exposure device in order to manufacture an electronic device. [Brief explanation of the drawing]

[0008] 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 VH cross-sectional view of the chamber of the comparative example. [Figure 4] Figure 4 is a VH cross-sectional view of the area around the cathode shown in Figure 3. [Figure 5] Figure 5 is a VH cross-sectional view of the area around the cathode shown in Figure 3. [Figure 6] Figure 6 is a VH cross-sectional view of the area around the cathode shown in Figure 3. [Figure 7] Figure 7 is a VH cross-sectional view of the area around the cathode in Embodiment 1. [Figure 8] Figure 8 is a VH cross-sectional view of the area around the cathode in Modification 1 of Embodiment 1. [Figure 9] Figure 9 is a VH cross-sectional view of the area around the cathode in a modified example 2 of Embodiment 1. [Figure 10] Figure 10 is a VH cross-sectional view of the area around the cathode in Modification 3 of Embodiment 1. [Figure 11] Figure 11 is a VH cross-sectional view of the periphery of the cathode in Modification 4 of Embodiment 1. [Figure 12] Figure 12 is a side view of the cathode and the cathode-side sound-absorbing member in Embodiment 2 as viewed from the upstream side along the H direction. [Figure 13] Figure 13 is a cross-sectional view of the periphery of the cathode at the A-A line shown in Figure 12. [Figure 14] Figure 14 is a cross-sectional view of the periphery of the cathode at the B-B line shown in Figure 12. [Figure 15] Figure 15 is a cross-sectional view of the periphery of the cathode at the C-C line shown in Figure 12. [Figure 16] Figure 16 is a VH cross-sectional view of the periphery of the anode in Embodiment 3. [Figure 17] Figure 17 is a VH cross-sectional view of the periphery of the anode in Embodiment 4. [Figure 18] Figure 18 is a perspective view of the outer electrode of the pre-ionization electrode in Embodiment 4. [Figure 19] Figure 19 is a VZ cross-sectional view of the groove in Modification 1 of Embodiment 4. [Figure 20] Figure 20 is a cross-sectional view of the periphery of the groove at the E-E line shown in Figure 19. [Figure 21] Figure 21 is a cross-sectional view of the periphery of the groove at the F-F line shown in Figure 19. [Figure 22] Figure 22 is a VZ cross-sectional view of the groove in Modification 2 of Embodiment 4. [Figure 23] Figure 23 is a top view of the periphery of the anode in Embodiment 5. [Figure 24] Figure 24 is a top view of the periphery of the anode in the modification of Embodiment 5. [Figure 25] Figure 25 is a cross-sectional view of the periphery of the groove at the G-G line shown in Figure 24. [Figure 26] Figure 26 is a cross-sectional view of the periphery of the groove at the H-H line shown in Figure 24. <​​ Embodiment

[0009] 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 Challenges 3. Description of the Chamber of Embodiment 1 3.1 Configuration 3.2 Action and Effects 4. Description of the Chamber in Embodiment 2 4.1 Configuration 4.2 Action and Effects 5. Description of the Chamber of Embodiment 3 5.1 Configuration 5.2 Action and Effects 6. Description of the Chamber of Embodiment 4 6.1 Configuration 6.2 Action and Effects 7. Description of the Chamber in Embodiment 5 7.1 Configuration 7.2 Action and Effects

[0010] 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. Furthermore, not all configurations and operations described in each embodiment are necessarily essential to the configurations and operations of this disclosure. The same reference numerals are used for identical components, and redundant descriptions are omitted.

[0011] 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 a reticle (not shown) placed on 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 has passed 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 a 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 a device pattern onto a semiconductor wafer through the exposure process described above, a semiconductor device, which is an electronic device, can be manufactured.

[0012] 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 publicly known examples acknowledged by the applicant.

[0013] Figure 2 is a schematic diagram showing an example of the overall configuration of a comparative example gas laser apparatus 100. The gas laser apparatus 100 is, for example, an ArF excimer laser apparatus that uses a mixed gas containing argon (Ar), fluorine (F2), and neon (Ne). This gas laser apparatus 100 outputs laser light with a central wavelength of approximately 193 nm. Note that the gas laser apparatus 100 may be a gas laser apparatus other than an ArF excimer laser apparatus, for example, a KrF excimer laser apparatus that uses a mixed gas containing krypton (Kr), F2, and Ne. In this case, the gas laser apparatus 100 emits laser light with a central wavelength of approximately 248 nm. Mixed gases containing Ar, F2, and Ne as laser media, or mixed gases containing Kr, F2, and Ne as laser media, are sometimes called laser gases.

[0014] The gas laser apparatus 100 mainly comprises a housing 110, a laser oscillator 130, a monitor module 160, a shutter 170, and a laser processor 190, all of which are arranged in the internal space of the housing 110.

[0015] 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. Figure 2 shows the internal configuration of the chamber 131 as viewed from a direction approximately perpendicular to the direction of laser beam propagation.

[0016] Examples of materials for the chamber 131 include nickel-plated aluminum or nickel-plated stainless steel. The chamber 131 contains the laser gas and includes an internal space where light is generated by the excitation of the laser medium in the laser gas. This light travels to windows 139a and 139b, which will be described later. The laser gas is supplied to the internal space of the chamber 131 from a laser gas supply source (not shown) through piping (not shown). The laser gas in the chamber 131 is then subjected to treatment such as removing F2 gas by a halogen filter, and exhausted outside the housing 110 through piping (not shown) by an exhaust pump (not shown).

[0017] In the internal space of chamber 131, the first main electrode, cathode 400, and the second main electrode, anode 500, are spaced apart from each other and face each other, with their respective longitudinal directions aligned with the direction of laser beam propagation. In the following, the longitudinal direction of cathode 400 and anode 500 may be described as the Z direction, the direction perpendicular to the Z direction in which cathode 400 and anode 500 are spaced apart as the V direction, and the direction perpendicular to both the V and Z directions as the H direction. Cathode 400 and anode 500 are discharge electrodes for exciting the laser medium by glow discharge.

[0018] The cathode 400 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 the cathode 400. The anode 500 is supported and electrically connected to the ground plate 137.

[0019] The electrical insulating section 135 includes an insulator. Examples of materials for the electrical insulating section 135 include alumina ceramics, which have low reactivity with F2 gas. The electrical insulating section 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 section 135 closes an opening provided in the chamber 131 and is fixed to the chamber 131.

[0020] 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 the 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 stored in the charging capacitor and applies this high voltage between the cathode 400 and the anode 500.

[0021] When a high voltage is applied between the cathode 400 and the anode 500, a discharge occurs. The energy of this discharge excites the laser medium in the chamber 131, and the excited laser medium emits light when it transitions to the ground state.

[0022] A pair of windows 139a and 139b are provided on the wall of the chamber 131. Window 139a is located on one side in the direction of laser beam propagation within the chamber 131, and window 139b is located on the other side in the same direction of propagation. Windows 139a and 139b sandwich the discharge space between the cathode 400 and the anode 500. 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 the cathode 400 and the anode 500 by the pulse power module 143, so this laser beam is pulsed laser beam.

[0023] 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.

[0024] 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.

[0025] 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. When light incident on the grating 145c from the prism 145b is reflected by these grooves, it is diffracted in a direction corresponding to the wavelength of the light. The grating 145c is Littrow-positioned so 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 ensures that light near the desired wavelength is returned to the chamber 131 via the prism 145b.

[0026] The output coupling mirror 147 is positioned in the internal space of the optical path tube 147a connected to the front side of the chamber 131, facing 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. Light from the chamber 131 travels to the monitor module 160.

[0027] 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.

[0028] 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 photosensor 165. The photosensor 165 measures the energy E of the laser light incident on the light-receiving surface and outputs a signal indicating the measured energy E to the laser processor 190.

[0029] 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.

[0030] 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 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.

[0031] 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.

[0032] The shutter 170 is positioned in the optical path of the laser beam in the internal space of the optical path tube 171, which communicates with 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 internal spaces of the optical path tubes 171 and 147a, and the internal spaces of the housings 161 and 145a are supplied and filled with purge gas. 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 also communicates with the exposure apparatus 200 through an opening in the housing 110 and an optical path tube 300 connecting the housing 110 and the exposure apparatus 200. The laser beam that passes through the shutter 170 is incident on the exposure apparatus 200.

[0033] 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.

[0034] Figure 3 is a VH cross-sectional view of the chamber 131 of the comparative example. A cross-flow fan 149 and a heat exchanger 151 are further arranged in the internal space of the chamber 131.

[0035] The cross-flow fan 149 and heat exchanger 151 are positioned on the opposite side of the anode 500 from the ground plate 137. Within the internal space of the chamber 131, the space in which the cross-flow fan 149 and heat exchanger 151 are located communicates with the discharge space between the cathode 400 and the anode 500. The heat exchanger 151 is a radiator positioned next to the cross-flow fan 149 and connected to piping (not shown) through which a cooling medium, whether liquid or gas, flows. 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, discharge space between the cathode 400 and the anode 500, heat exchanger 151, and then 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 circulation of the laser gas moves impurities generated by the main discharge between the cathode 400 and the anode 500 downstream, supplying fresh laser gas to the discharge space between the cathode 400 and the anode 500 for the next discharge. Furthermore, as the laser gas passes through the heat exchanger 151, heat associated with the main discharge is removed, suppressing the temperature rise of the laser gas. The ON / OFF state and rotational speed of the 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 chamber 131 by controlling the motor 149a.

[0036] The ground plate 137 is electrically connected to the chamber 131 via wiring 137a. The anode 500, supported by the ground plate 137, is connected to ground potential via the ground plate 137, wiring 137a, and chamber 131.

[0037] An anode-side cover 550 is positioned on the ground plate 137, covering the sides of the anode 500. The anode-side cover 550 includes cover members 551, 553, and 555, which are arranged in this order from upstream to downstream of the laser gas flow. Cover member 551 is fixed to the ground plate 137 with bolts (not shown), and a pre-ionization electrode 10 is provided between cover member 551 and cover member 553, with cover members 553 and 555 sandwiching the anode 500. The anode 500 is fixed to the ground plate 137 with bolts (not shown), and cover members 553 and 555 are fixed to the anode 500 with bolts (not shown). Examples of materials for cover members 551, 553, and 555 include porous nickel metal with low reactivity with F2 gas. The cover members 551, 553, and 555 guide the laser gas so that it flows from the cross-flow fan 149 through the discharge space between the cathode 400 and the anode 500 to the heat exchanger 151 by the airflow from the cross-flow fan 149.

[0038] The pre-ionization electrode 10 is provided on the ground plate 137, to the side of the anode 500 in the H direction. In this example, the pre-ionization electrode 10 is shown to be provided upstream of the anode 500. The pre-ionization electrode 10 comprises a dielectric pipe 11, a pre-ionization inner electrode, and a pre-ionization outer electrode. Hereinafter, the pre-ionization inner electrode and the pre-ionization outer electrode may be referred to as the inner electrode 13 and the outer electrode 15, respectively.

[0039] The dielectric pipe 11 is, for example, a cylindrical member that extends along the Z direction. Examples of materials for the dielectric pipe 11 include alumina ceramics and sapphire.

[0040] The internal electrode 13 is rod-shaped, positioned inside the dielectric pipe 11, and extends along the longitudinal direction of the dielectric pipe 11. Examples of materials for the internal electrode 13 include copper and brass.

[0041] The external electrode 15 is positioned between the dielectric pipe 11 and the cover member 553 and extends along the longitudinal direction of the dielectric pipe 11. The external electrode 15 includes an end portion 15a that faces a portion of the outer circumferential surface of the dielectric pipe 11. This end portion 15a extends from one end to the other of the external electrode 15 in the longitudinal direction of the external electrode 15. The external electrode 15 is bent in an in-plane direction perpendicular to the longitudinal direction of the dielectric pipe 11, and due to the bending, the end portion 15a contacts the outer circumferential surface of the dielectric pipe 11 by pressing against it. The portion of the outer circumferential surface of the dielectric pipe 11 that is approximately opposite to the contact portion where the end portion 15a of the external electrode 15 makes contact is in contact with the cover member 551. Therefore, even when the external electrode 15 presses against the dielectric pipe 11, the dielectric pipe 11 is supported by the cover member 551. A screw hole (not shown) is provided at the end of the outer electrode 15 opposite to the end 15a, and the outer electrode 15 is fixed to the cover member 553 by a screw (not shown) that is screwed into the screw hole. Therefore, it can be understood that the outer electrode 15 is fixed to the anode 500 via the cover member 553. Examples of materials for the outer electrode 15 include copper and brass.

[0042] A pair of cathode-side covers 450 are positioned on the internal space side of the chamber 131 within the electrical insulation section 135. The cathode-side covers 450 are positioned on the upstream and downstream sides of the cathode 400, extending in the Z direction along the cathode 400, and are separate from each other. Each cathode-side cover 450 is fixed to the electrical insulation section 135 with bolts (not shown). The cross-sectional shape of the cathode-side covers 450 is generally a right triangle, and the cathode-side covers 450 gradually increase in height in the V direction as they approach the cathode 400 in the H direction. Such cathode-side covers 450, like the anode-side cover 550, guide the laser gas.

[0043] Figure 4 is a VH cross-sectional view of the area around the cathode 400 shown in Figure 3. In Figure 4, the laser gas flowing through the discharge space between the cathode 400 and the anode 500 is indicated by a thick arrow. The cathode 400 includes a base 401 fixed to the electrical insulation portion 135 and a discharge portion 403 protruding from the base 401 toward the anode 500. The cross-sectional shape of the base 401 is a rectangle elongated in the H direction, and the cross-sectional shape of the discharge portion 403 is a rectangle elongated in the V direction. The base 401 and the discharge portion 403 extend along the Z direction and are approximately the same length as the cathode 400 in the Z direction. The discharge portion 403 is provided on the side of the base 401 opposite to the electrical insulation portion 135. The base 401 is wider in the H direction than the discharge portion 403, and each of the left and right sides of the discharge portion 403 in the H direction is provided with a surface 401a included in the opposite side. In Figures 3 and 4, for ease of viewing, only the left side surface 401a is labeled with a reference numeral. The side surface of the base 401, which is provided in the VZ plane, abuts against a portion of the side surface 451 of the cathode-side cover 450, while the side surface of the discharge section 403 does not abut against the side surface 451. Furthermore, the discharge section 403 extends toward the anode 500 beyond the projection 453 of the cathode-side cover 450, which will be described later. Note that the illustration of the cathode 400 in Figure 2 is simplified.

[0044] The projection 453 of the cathode-side cover 450 protrudes in the H direction from the side surface 451 of the cathode-side cover 450 toward the side surface of the discharge section 403. The projection 453 is spaced apart from the discharge section 403 in the H direction and spaced apart from the surface 401a, which is part of the base 401, in the V direction. When viewed from the V direction, the projection 453 overlaps with the surface 401a. The projection 453 also extends in the Z direction and is approximately the same length as the cathode 400 in the Z direction. Such a projection 453 covers the base 401, and a gap 40 is provided between the projection 453 and the base 401. The gap 40 is a roughly L-shaped space enclosed by the entrance 41 of the gap 40 provided between the side surface of the discharge section 403 and the projection 453, the projection 453, the side surface 451, the surface 401a, and the side surface of the discharge section 403. Such a gap 40 is provided to prevent the cathode 400 and the cathode-side cover 450 from being assembled due to interference caused by manufacturing dimensional errors between the cathode 400 and the cathode-side cover 450. The cathode-side cover 450 that forms the gap 40 covers the cathode 400 from the side. The gap 40 is provided separately on the upstream and downstream sides of the cathode 400, since the cathode-side cover 450 is provided on both the upstream and downstream sides of the cathode 400. The gap 40 and the cathode-side cover 450 are provided symmetrically on the left and right sides of Figure 3, which is in the H direction with respect to the discharge section 403. In Figures 3 and 4, for ease of viewing, only the left gap 40 and inlet 41 are labeled. The acoustic wave 61a shown in Figure 4 will be described later.

[0045] 2.2 Operation Next, the operation of the comparative example gas laser apparatus 100 will be described.

[0046] Before the gas laser device 100 emits laser light, the internal spaces of the optical path tubes 147a, 171, and 300, and the internal spaces of the housings 145a and 161 are filled with purge gas from a purge gas supply source (not shown). Laser gas is also 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 circulates the laser gas through the internal space of the chamber 131. At this time, the laser gas is guided from the cross-flow fan 149 towards the discharge space between the cathode 400 and the anode 500 by the upstream cathode-side cover 450 and cover members 551 and 553. Furthermore, the laser gas is guided from the discharge space between the cathode 400 and the anode 500 towards the heat exchanger 151 by the downstream cathode-side cover 450 and cover member 555.

[0047] 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. 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 the cathode 400 and the anode 500 and between the inner electrode 13 and the outer electrode 15 from the electrical energy stored in a charging capacitor (not shown). When a high voltage is applied between the inner electrode 13 and the outer electrode 15, a corona discharge occurs near the dielectric pipe 11 and its end 15a, and ultraviolet light is emitted. When the ultraviolet light irradiates the laser gas between the cathode 400 and the anode 500, the laser gas between the cathode 400 and the anode 500 is pre-ionized. After pre-ionization, when the voltage between the cathode 400 and the anode 500 reaches the dielectric breakdown voltage, a main discharge occurs between the cathode 400 and the anode 500. This generates an excimer from the laser medium contained in the laser gas between the cathode 400 and the anode 500, which emits light upon dissociation. This light travels back and forth between the grating 145c and the output coupling mirror 147, and is amplified each time it passes through the discharge space in the internal space of the chamber 131, causing laser oscillation. A portion of the laser light then passes through the output coupling mirror 147 as pulsed laser light and proceeds to the beam splitter 163.

[0048] A portion of the laser light that travels through 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. Another portion of the laser light that travels through the beam splitter 163 passes through the beam splitter 163 and the shutter 170 and travels to the exposure apparatus 200.

[0049] 2.3 Challenges In the comparative example gas laser apparatus 100, the main discharge between the cathode 400 and the anode 500 generates a high-temperature, high-pressure state in the discharge space between the cathode 400 and the anode 500 in a very short time. This generates an acoustic wave 61a in the discharge space, which is simulated by the solid curve in Figure 4. The acoustic wave 61a is a compression wave of the laser gas in the chamber 131, and propagates within the chamber 131 while spreading out from the discharge space. The propagation speed is approximately 500 m / s.

[0050] Figures 5 and 6 are VH cross-sectional views of the area around the cathode 400, similar to Figure 4. The acoustic wave 61a may propagate from the entrance 41 of the gap 40 away from the discharge space, as shown in Figure 5. In addition, the acoustic wave 61a that has propagated into the gap 40 may be reflected by the cathode 400 and the cathode-side cover 450 around the gap 40, as shown in Figure 6, and return to the discharge space as a reflected wave 61b, shown by the solid curve. In Figures 5 and 6, the directions of propagation of the acoustic wave 61a and the reflected wave 61b are indicated by thin arrows.

[0051] If the reflected wave 61b returns to the discharge space at the same time as the main discharge occurs, the reflected wave 61b alters the density distribution of the laser gas in the discharge space, causing the main discharge to become unstable and potentially reducing the energy stability of the laser light emitted from the gas laser device 100. Thus, the reflected wave 61b can affect the performance of the laser light. This effect tends to be greater when the repetition frequency of the laser light is 2 kHz or higher. This raises concerns that the exposure device 200 may not emit laser light that meets the required performance, thus reducing the reliability of the gas laser device 100.

[0052] Therefore, in the following embodiment, a chamber 131 of the gas laser apparatus 100 in which a decrease in reliability can be suppressed is exemplified.

[0053] 3. Description of the Chamber of Embodiment 1 Next, the chamber 131 of Embodiment 1 will be described. Components similar to those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified. Furthermore, in some drawings, for clarity, some components may be omitted or simplified, and similar components may have reference numerals only in some cases, or some may be omitted entirely.

[0054] 3.1 Configuration Figure 7 is a VH cross-sectional view of the area around the cathode 400 in this embodiment. In the chamber 131 of this embodiment, the configuration of the base 401 differs from the configuration of the base 401 of the comparative example. Furthermore, the chamber 131 differs from the chamber 131 of the comparative example in that it further includes cathode-side sound-absorbing members 470 provided in the gaps 40 on the upstream and downstream sides of the cathode 400.

[0055] The base 401 of this embodiment includes a first base 405 and a second base 407. The second base 407 is provided on the side of the first base 405 opposite to the electrical insulation portion 135. The second base 407 protrudes from the first base 405 toward the anode 500. The first base 405 is wider in the H direction than the second base 407, and each of the left and right sides of the second base 407 in the H direction is provided with a surface 405a that is included in the opposite side of the first base 405. A discharge portion 403 is provided on the side of the second base 407 opposite to the first base 405. The discharge portion 403 protrudes from the second base 407 toward the anode 500. The second base 407 is wider in the H direction than the discharge portion 403, and each of the left and right sides of the discharge portion 403 in the H direction is provided with a surface 407a that is included in the opposite side of the second base 407. Surface 407a faces the inlet 41. In Figure 7, for ease of viewing, only the left surfaces 405a and 407a are labeled. The first base 405 abuts against a portion of the side surface 451 of the cathode-side cover 450, while the second base 407 does not abut against the side surface 451. In other words, the cathode-side cover 450 is spaced apart from the second base 407, which is part of the base 401. The first base 405 and the second base 407 are positioned on the electrical insulation side 135 of the inlet 41.

[0056] In this embodiment, the cathode-side sound-absorbing member 470 is positioned on the base 401, specifically on the surface 405a of the first base 405, and is screwed to the first base 405. This cathode-side sound-absorbing member 470 is provided in the gap 40 between the second base 407, which is part of the base 401, and the side surface 451 of the cathode-side cover 450, and abuts against the side surface of the second base 407, facing the projection 453 and a part of the entrance 41 of the gap 40. Furthermore, since the cathode-side sound-absorbing member 470 also abuts against the side surface 451 of the cathode-side cover 450, it can be understood that it is also positioned at the location furthest from the discharge space within the gap 40. In this embodiment, the region within the gap 40 from which the acoustic wave 61a propagates is the space enclosed by the entrance 41, the projection 453, the side surface 451, the surface 405a, the side surface of the second base 407, the surface 407a, and the side surface of the discharge section 403. Such a gap 40 consists of an entrance 41, a first rectangular space connected to the entrance 41 and longer in the H direction than in the V direction, and a second rectangular space connected to the first space, located further back than the first space, and longer in the H direction than in the V direction and narrower in the H direction than the first space. The cathode-side sound-absorbing member 470 extends along the Z direction and is approximately the same length as the cathode 400, but may be shorter than the cathode 400.

[0057] The cathode-side sound-absorbing member 470 is made of, for example, a porous material. Examples of materials for the cathode-side sound-absorbing member 470 include metals such as nickel, copper, iron, stainless steel, and brass. The cathode-side sound-absorbing member 470 may also be an electrical insulator as long as it is made of a porous material, and an example of such a material for the cathode-side sound-absorbing member 470 is alumina ceramics.

[0058] 3.2 Action and Effects When a voltage is applied to the cathode 400 and anode 500, and a main discharge occurs between the cathode 400 and anode 500, light is emitted from the laser gas, and this light passes through the window 139b and exits from the chamber 131. In the chamber 131 of this embodiment, the main discharge generates an acoustic wave 61a in the discharge space between the cathode 400 and anode 500, and this acoustic wave 61a may propagate into the gap 40 between the base 401 and the cathode-side cover 450. The acoustic wave 61a that has propagated into the gap 40 is absorbed by the cathode-side sound-absorbing member 470 provided in the gap 40. The absorbed acoustic wave 61a propagates through the inside of the cathode-side sound-absorbing member 470, repeatedly reflecting, and is converted into energy such as heat, gradually attenuating. Furthermore, the acoustic wave 61a that passes through the cathode-side sound-absorbing member 470 is reflected by the base 401 and cathode-side cover 450 surrounding the cathode-side sound-absorbing member 470 and absorbed again by the cathode-side sound-absorbing member 470. The absorbed acoustic wave 61a is further attenuated by repeated reflections inside the cathode-side sound-absorbing member 470 as described above. As a result, the magnitude of the reflected wave 61b, which is the acoustic wave 61a reflected inside the cathode-side sound-absorbing member 470 and returning to the discharge space, is reduced, which can suppress changes in the density distribution of the laser gas in the discharge space due to the reflected wave 61b, and can suppress unstable main discharge. In Figure 7, the illustration of the reflected wave 61b is omitted for clarity. In addition, by covering the base 401 with the cathode-side cover 450, unwanted discharge from the base 401 during main discharge can be suppressed. As a result, a decrease in the energy stability of the laser light emitted from the gas laser device 100 can be suppressed. Therefore, laser light that meets the required performance can be emitted from the exposure apparatus 200, and a decrease in the reliability of the gas laser apparatus 100 can be suppressed.

[0059] Furthermore, in the chamber 131 of this embodiment, the cathode-side sound-absorbing member 470 is also positioned at the location furthest from the discharge space between the cathode 400 and the anode 500 within the gap 40.

[0060] The acoustic wave 61a tends to attenuate as it propagates to the position furthest from the discharge space while being absorbed by the cathode-side sound-absorbing member 470. Therefore, with this configuration, the acoustic wave 61a propagating to the position furthest from the discharge space and the reflected wave 61b returning to the discharge space from the cathode-side sound-absorbing member 470 can be attenuated. As a result, changes in the density distribution of the laser gas in the discharge space due to the reflected wave 61b can be suppressed, and an unstable main discharge can be suppressed.

[0061] In this embodiment, the cathode-side sound-absorbing member 470 is positioned on the surface 405a of the first base 405, but it may also be positioned on at least one of the surfaces 405a and 407a of the second base 407, or it may be positioned to fill the entire gap 40. Furthermore, the cathode-side sound-absorbing member 470 is positioned in the gaps 40 on the upstream and downstream sides of the cathode 400, but it may also be positioned in at least one of the gaps 40. Alternatively, it may be positioned to surround the entire circumference of the cathode 400, such as the first base 405 and the second base 407.

[0062] Furthermore, the placement of the cathode-side sound-absorbing member 470 is not limited to the above, and other examples will be explained using modified examples.

[0063] Figure 8 is a VH cross-sectional view of the area around the cathode 400 in Modification 1 of this embodiment. In this modification, the chamber 131 differs from this embodiment in that the cathode-side sound-absorbing member 470 is spaced apart from the side surface 451 of the cathode-side cover 450. In this modification, the region of the gap 40 through which the acoustic wave 61a propagates is the space enclosed by the inlet 41, the projection 453, the side surface 451, the surface 455 and surface 405a of the cathode-side cover 450 facing the projection 453, the side surface and surface 407a of the second base 407, and the side surface of the discharge section 403. Such a gap 40 consists of an inlet 41, a first rectangular space connected to the inlet 41 that is longer in the H direction than in the V direction, and a second rectangular space connected to the first space, located further back than the first space, which is longer in the V direction than in the H direction and narrower in the H direction than the first space, and has a crank shape.

[0064] Figure 9 is a VH cross-sectional view of the area around the cathode 400 in Modification 2 of this embodiment. The base 401 of this modification has the same configuration as the base 401 of the comparative example. The chamber 131 of this modification differs from this embodiment in that the cathode-side sound-absorbing member 470 is located on the cathode-side cover 450. Specifically, the cathode-side sound-absorbing member 470 is located on the surface of the projection 453 that faces the surface 401a of the base 401. In other words, the cathode-side sound-absorbing member 470 is provided in the gap between the surface 401a, which is part of the base 401, and the projection 453 of the cathode-side cover 450. The cathode-side sound-absorbing member 470 is screwed to the projection 453, abuts against the side surface 451 of the cathode-side cover 450, and faces the surface 401a at a distance from it.

[0065] Figure 10 is a VH cross-sectional view of the area around the cathode 400 in Modification 3 of this embodiment. The chamber 131 of this modification differs from Modification 2 in that the cathode-side sound-absorbing member 470 is positioned on the side surface 451 of the cathode-side cover 450. The cathode-side sound-absorbing member 470 is screwed to the side surface 451. The cathode-side sound-absorbing member 470 is spaced apart from the side surface of the base 401 and is in contact with a part of the surface 455 and a part of the projection 453 of the cathode-side cover 450. Since the cathode-side sound-absorbing member 470 also contacts the angle between the side surface 451 and the surface 455, it can be understood that it is positioned at the position furthest from the discharge space within the gap 40. In this modified example, the region of the gap 40 through which the acoustic wave 61a propagates is the space enclosed by the entrance 41 of the gap 40, the projection 453, the side surface 451, the surface 455, the side surface of the base 401, the surface 401a of the base 401, and the side surface of the discharge section 403. This gap 40, like the first modified example, consists of an entrance 41, a first space, and a second space, and has a crank shape. The side surface 451 of the cathode-side cover 450 is spaced apart from a part of the side surface of the base 401 and is in contact with another part of the side surface of the base 401.

[0066] In all of the modified examples 1, 2, and 3, the acoustic wave 61a propagating through the gap 40 is absorbed by the cathode-side sound-absorbing member 470. Therefore, the magnitude of the reflected wave 61b is reduced, and the decrease in the stability of the energy of the laser light emitted from the gas laser device 100 can be suppressed.

[0067] Figure 11 is a VH cross-sectional view of the area around the cathode 400 in Modification 4 of this embodiment. In the chamber 131 of this modification, the base 401 includes a first base 405 and a second base 407, similar to the base 401 of this embodiment, and Modifications 1 to 3 are combined, with a cathode-side sound-absorbing member 470 also positioned on the surface 407a of the second base 407. In other words, in the chamber 131 of this modification, the cathode-side sound-absorbing member 470 is positioned on the surface 405a, the surface 407a, the projection 453, and the side surface 451, respectively. The cathode-side sound-absorbing member 470 positioned on surface 407a extends in the H direction and is also positioned on the cathode-side sound-absorbing member 470 positioned on surface 405a. The cathode-side sound-absorbing member 470 positioned on projection 453 faces and is spaced apart from the cathode-side sound-absorbing member 470 positioned on surface 407a of the second base 407. The cathode-side sound-absorbing members 470 positioned on the side surface 451 of the cathode-side cover 450 face and are spaced apart from the cathode-side sound-absorbing members 470 positioned on the surface 405a of the first base 405 and the surface 407a of the second base 407, respectively.

[0068] With this configuration, compared to the case where the cathode-side sound-absorbing member 470 is placed only on either the base 401 or the cathode-side cover 450, the acoustic wave 61a can be absorbed and attenuated more by the cathode-side sound-absorbing member 470. Consequently, the magnitude of the reflected wave 61b can be further reduced, and the decrease in the stability of the energy of the laser light emitted from the gas laser device 100 can be further suppressed.

[0069] 4. Description of the Chamber in Embodiment 2 Next, the chamber 131 of Embodiment 2 will be described. Components similar to those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified. Furthermore, in some drawings, for clarity, some components may be omitted or simplified, and similar components may have reference numerals only for some parts, or some may be omitted entirely.

[0070] 4.1 Configuration Figure 12 is a side view of the cathode 400 and the cathode-side sound-absorbing member 470 in this embodiment, viewed from the upstream side along the H direction. Figure 13 is a cross-sectional view of the area around the cathode 400 along line AA shown in Figure 12, Figure 14 is a cross-sectional view of the area around the cathode 400 along line BB shown in Figure 12, and Figure 15 is a cross-sectional view of the area around the cathode 400 along line CC shown in Figure 12.

[0071] In this embodiment, the cathode-side sound-absorbing member 470 is positioned on the surface 405a of the first base 405 and spaced apart from the side surface 451 of the cathode-side cover 450, as in the modification 1 of Embodiment 1. However, in the chamber 131 of this embodiment, the configuration of the surface 405a, the surface 455 of the cathode-side cover 450 that is in contact with the gap 40, and the cathode-side sound-absorbing member 470 differs from the modification 1 of Embodiment 1.

[0072] The surface 405a of the first base 405 and the surface 455 of the cathode-side cover 450 are gradually inclined in the Z direction from one side to the other, away from the anode 500 and the projection 453. One side in the Z direction is on the monitor module 160 side, and the other side is on the narrowband module 145 side. Therefore, the region of the gap 40 between the side surface of the second base 407 and the side surface 451 of the cathode-side cover 450 gradually deepens in the V direction from one side to the other in the Z direction.

[0073] The cathode-side sound-absorbing member 470 is positioned on the inclined surface 405a as described above. In this embodiment, the height of the cathode-side sound-absorbing member 470 in the V direction gradually increases from one side to the other in the Z direction. Furthermore, the surface of the cathode-side sound-absorbing member 470 facing the projection 453 is at the same height from one side to the other in the Z direction, and is at the same height as the surface 407a of the second base 407. Therefore, the side surface of the second base 407 is covered by the cathode-side sound-absorbing member 470.

[0074] 4.2 Action and Effects In the chamber 131 of this embodiment, the surface 455 of the cathode-side cover 450 that contacts the gap 40 is perpendicular to the V direction from the anode 500 toward the cathode 400, extends in a predetermined Z direction, and is inclined to move away from the anode 500 from one side to the other in the Z direction.

[0075] In this configuration, the distance from the other side of the surface 455 in the Z direction to the discharge space is longer than the distance from the one side of the surface 455 in the Z direction to the discharge space. As a result, when the acoustic wave 61a propagating in the gap 40 is reflected by the surface 455, the reflected wave 61b returning to the discharge space from the other side of the surface 455 in the Z direction and the reflected wave 61b returning to the discharge space from the one side of the surface 455 in the Z direction are out of phase. When the phases are out of phase, the simultaneous return of the reflected waves 61b to the discharge space can be suppressed compared to when there is no phase difference. Therefore, changes in the density distribution of the laser gas in the discharge space due to the reflected waves 61b can be suppressed, and unstable main discharges can be suppressed.

[0076] Furthermore, the cathode-side sound-absorbing member 470 in this embodiment extends in the Z direction and is positioned on the base 401. The height of the cathode-side sound-absorbing member 470 in the V direction from the anode 500 to the cathode 400 increases from one side to the other in the Z direction.

[0077] In this configuration, the acoustic wave 61a absorbed by the cathode-side sound-absorbing member 470 is attenuated by repeated reflections within the cathode-side sound-absorbing member 470 on the other side in the Z direction compared to the one side. Therefore, the reflected wave 61b returning to the discharge space from the other side in the Z direction is reduced compared to the reflected wave 61b returning to the discharge space from one side in the Z direction. Compared to the case where there is no reduction, the change in the density distribution of the laser gas in the discharge space due to the reflected wave 61b can be suppressed, and an unstable main discharge can be suppressed.

[0078] In this embodiment, the chamber 131 was described using Modification 1 of Embodiment 1, but it is not limited to this and may be used in Embodiment 1 or other modifications of Embodiment 1. That is, the cathode-side sound-absorbing member 470 should be positioned on a surface perpendicular to the V direction from the anode 500 toward the cathode 400. Examples of this surface include the surface 405a in Embodiment 1, the surface on the base 401a side of the projection 453 in Modification 2, and the surface 455 of the cathode-side cover 450 in Modification 3. These surfaces should be inclined so as to move away from the anode 500 from one side to the other in the Z direction.

[0079] In this embodiment, the chamber 131 is described with one side in the Z direction facing the monitor module 160 and the other side facing the narrowband module 145, but the reverse is also possible. That is, one side in the Z direction may face the narrowband module 145 and the other side may face the monitor module 160.

[0080] Furthermore, the cathode-side sound-absorbing member 470 does not need to gradually increase in the V direction from one side to the other in the Z direction. The cathode-side sound-absorbing member 470 may increase in a stepped manner from one side to the other in the Z direction.

[0081] 5. Description of the Chamber of Embodiment 3 Next, the chamber 131 of Embodiment 3 will be described. Components similar to those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified. Furthermore, in some drawings, for clarity, some components may be omitted or simplified, and similar components may have reference numerals only for some parts, or some may be omitted entirely.

[0082] In addition, while the configuration of the anode 500 side will be mainly described for each embodiment from Embodiment 3 onward and its modified versions, the configuration of the cathode 400 side can be any of the cathode 400 side configurations of Embodiments 1, 2 and their modified versions.

[0083] 5.1 Configuration Figure 16 is a VH cross-sectional view of the area around the anode 500 in this embodiment. The chamber 131 in this embodiment differs from Embodiment 1 in that the anode 500 includes a base 501 and a discharge section 503 that extend in the Z direction, and the anode-side cover 550 covers the anode 500 from the side of the anode 500, spaced apart from the anode 500.

[0084] The base 501 is fixed to the ground plate 137, and the discharge section 503 protrudes from the base 501 toward the discharge section 403 of the cathode 400. Unlike the cathode 400, the base 501 is narrower in the H direction than the discharge section 503, and the sides of the base 501 are located inward from the sides of the discharge section 503.

[0085] In the anode-side cover 550, since the cover members 553 and 555 are spaced apart from the anode 500, gaps 50 are provided between the anode 500 and the cover member 553, and between the anode 500 and the cover member 555.

[0086] Furthermore, the chamber 131 of this embodiment differs from Embodiment 1 in that the chamber 131 further includes an anode-side sound-absorbing member 570 provided in the gap 50 between the anode-side cover 550 and the anode 500. The anode-side sound-absorbing member 570 is positioned on the side of each of the cover member 553 and cover member 555 that faces the anode 500, and is screwed to the side. In addition, the anode-side sound-absorbing member 570 is positioned on the upstream side and the downstream side of the base 501 of the anode 500, and is screwed to the respective side of the base 501. Thus, four anode-side sound-absorbing members 570 are positioned on each of the anode-side cover 550 and the anode 500. The anode-side sound-absorbing members 570 positioned on the cover member 553 and the upstream side of the base 501 face each other, and the anode-side sound-absorbing members 570 positioned on the downstream side of the base 501 and the cover member 555 face each other. The anode-side sound-absorbing member 570 extends along the Z direction and is approximately the same length as the anode 500, but may be shorter than the anode 500. The configuration and materials of the anode-side sound-absorbing member 570 are the same as those of the cathode-side sound-absorbing member 470.

[0087] 5.2 Action and Effects The acoustic wave 61a propagates from the discharge space between the cathode 400 and the anode 500 to the gap 50 between the anode 500 and the anode-side cover 550. In this configuration, since the anode-side sound-absorbing member 570 is also placed in this gap 50, the acoustic wave 61a that propagates into the gap 50 can be absorbed by the anode-side sound-absorbing member 570 provided in the gap 50 and gradually attenuated. Consequently, the magnitude of the reflected wave 61b that is reflected inside the anode-side sound-absorbing member 570 and returns to the discharge space is reduced, and changes in the density distribution of the laser gas in the discharge space due to the reflected wave 61b can be suppressed, thereby suppressing instability of the main discharge. As a result, a decrease in the stability of the energy of the laser light emitted from the gas laser device 100 can be suppressed. In Figure 16, the illustration of the reflected wave 61b is omitted for clarity.

[0088] Furthermore, in the chamber 131 of this embodiment, the anode-side sound-absorbing member 570 is arranged on the anode-side cover 550 and the anode 500, respectively.

[0089] With this configuration, compared to the case where the anode-side sound-absorbing member 570 is placed only on either the anode 500 or the anode-side cover 550, the acoustic wave 61a can be absorbed and attenuated more by the anode-side sound-absorbing member 570. Therefore, the magnitude of the reflected wave 61b can be further reduced, and the decrease in the stability of the energy of the laser light emitted from the gas laser device 100 can be further suppressed.

[0090] In the chamber 131 of this embodiment, the anode-side sound-absorbing member 570 is positioned on both the anode-side cover 550 and the anode 500, but it may also be positioned on either the anode-side cover 550 or the anode 500. Furthermore, the side surface of the base 501 is not positioned inward from the side surface of the discharge section 503, but is on the same plane, meaning the anode 500 may have the same configuration as the anode 500 of the comparative example, and the anode-side sound-absorbing member 570 may be positioned on the side surface of this anode 500.

[0091] 6. Description of the Chamber of Embodiment 4 Next, the chamber 131 of Embodiment 4 will be described. Components similar to those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless specifically stated. Furthermore, in some drawings, for clarity, some components may be omitted or simplified, and similar components may have reference numerals only for some parts, or some may be omitted entirely.

[0092] 6.1 Configuration Figure 17 is a VH cross-sectional view of the area around the anode 500 in this embodiment. The chamber 131 in this embodiment differs from Embodiment 1 in that a groove 137b is provided in the ground plate 137, and the anode-side sound-absorbing member 570 is positioned in the groove 137b.

[0093] The groove 137b is located on the upstream side of the anode 500, specifically between the cover member 551 and the cover member 553, and below the dielectric pipe 11 and the outer electrode 15. The groove 137b extends in the Z direction, and the depth of the groove 137b in the V direction is constant in the Z direction.

[0094] The height of the anode-side sound-absorbing member 570 positioned in the groove 137b is constant in the V direction in the Z direction, and the anode-side sound-absorbing member 570 faces the dielectric pipe 11 and the external electrode 15. The anode-side sound-absorbing member 570 does not protrude from the main surface of the ground plate 137, and the surface 570a of the anode-side sound-absorbing member 570 that faces the dielectric pipe 11 and the external electrode 15 is located at the same height as the main surface of the ground plate 137.

[0095] Figure 18 is a perspective view of the outer electrode 15 of the pre-ionization electrode 10 in this embodiment. The outer electrode 15 includes an end portion 15a that extends along the longitudinal direction of the dielectric pipe 11, which is the Z direction, and contacts the outer circumferential surface of the dielectric pipe 11, and a ladder portion 15c consisting of a plurality of bar members 15b, one end of which is connected to the end portion 15a and arranged in parallel along the longitudinal direction of the end portion 15a. The gap 15e between the plurality of bar members 15b means that the outer electrode 15 does not separate the discharge space from the anode-side sound-absorbing member 570, and as shown in Figure 17, the acoustic wave 61a propagates from the discharge space through the gap 15e to the anode-side sound-absorbing member 570.

[0096] 6.2 Action and Effects The acoustic wave 61a propagates from the discharge space between the cathode 400 and the anode 500 to the ground plate 137 through the gaps 15e between the multiple bar members 15b. In this configuration, since the anode-side sound-absorbing member 570 is placed in the groove 137b of the ground plate 137, the acoustic wave 61a can be absorbed by the anode-side sound-absorbing member 570. Therefore, the magnitude of the reflected wave 61b returning to the discharge space from the anode-side sound-absorbing member 570 and the groove 137b is reduced, and changes in the density distribution of the laser gas in the discharge space due to the reflected wave 61b can be suppressed, thereby suppressing instability of the main discharge. As a result, a decrease in the stability of the energy of the laser light emitted from the gas laser device 100 can be suppressed. In addition, since the anode-side sound-absorbing member 570 is placed in the groove 137b, obstruction of the laser gas flow in the chamber 131 by the anode-side sound-absorbing member 570 can be suppressed compared to the case where the anode-side sound-absorbing member 570 is placed on the main surface of the ground plate 137.

[0097] The configuration of groove 137b and anode-side sound-absorbing member 570 is not limited to the above, and other examples will be explained using modified examples.

[0098] Figure 19 is a VZ cross-sectional view of groove 137b in Modification 1 of this embodiment. In Figure 19, for ease of viewing, only the ground plate 137, groove 137b, and anode-side sound-absorbing member 570 are shown. Figure 20 is a cross-sectional view of the area around groove 137b along the EE line shown in Figure 19, and Figure 21 is a cross-sectional view of the area around groove 137b along the FF line shown in Figure 19. Note that the cross-sectional view of the area around groove 137b along the DD line shown in Figure 19 is the same as in Figure 17.

[0099] In this modified example, groove 137b differs from the embodiment in that the depth of groove 137b in the V direction, which is perpendicular to the main surface of the ground plate 137 that is orthogonal to the Z direction, gradually increases from one side to the other in the Z direction. Therefore, the bottom surface of groove 137b is inclined from one side to the other in the Z direction. One side in the Z direction is located towards the monitor module 160, and the other side is located towards the narrowband module 145.

[0100] Furthermore, in this modified example, the anode-side sound-absorbing member 570 is positioned on the bottom surface of the inclined groove 137b as described above, and the height of the anode-side sound-absorbing member 570 in the V direction is constant from one side to the other in the Z direction, similar to Embodiment 4. Therefore, at the position along the DD line, similar to Embodiment 4, the anode-side sound-absorbing member 570 does not protrude from the main surface of the ground plate 137, and the surface 570a of the anode-side sound-absorbing member 570 is located at the same height as the main surface of the ground plate 137. Also, at the position along the EE line, the surface 570a is located lower than the main surface of the ground plate 137, and at the position along the FF line, it is located even lower than the main surface of the ground plate 137.

[0101] In this modified example, the groove 137b has a depth in the V direction perpendicular to the main surface of the ground plate 137, which is perpendicular to the predetermined Z direction, increasing from one side to the other in the predetermined direction.

[0102] In this configuration, the distance from the other side of the bottom surface of the groove 137b in a predetermined direction to the discharge space is longer than the distance from the one side of the bottom surface in a predetermined direction to the discharge space. As a result, the reflected wave 61b returning to the discharge space from the other side of the bottom surface in a predetermined direction and the reflected wave 61b returning to the discharge space from the one side of the bottom surface in a predetermined direction are out of phase. When the phases are out of phase, the simultaneous return of the reflected waves 61b to the discharge space can be suppressed compared to when there is no phase difference. Therefore, changes in the density distribution of the laser gas in the discharge space due to the reflected waves 61b can be suppressed, and unstable main discharges can be suppressed.

[0103] Figure 22 is a VZ cross-sectional view of groove 137b in modified example 2 of this embodiment. In Figure 22, for ease of viewing, only the ground plate 137, groove 137b, and anode-side sound-absorbing member 570 are shown.

[0104] In this modified example, the anode-side sound-absorbing member 570 differs from Modified Example 1 in that the height of the anode-side sound-absorbing member 570 in the V direction gradually increases from one side to the other in the Z direction. The surface 570a of the anode-side sound-absorbing member 570 is located at the same height position from one side to the other in the Z direction, and is located at the same height position as the main surface of the ground plate 137.

[0105] In this configuration, the acoustic wave 61a absorbed by the anode-side sound-absorbing member 570 is attenuated by repeated reflections within the anode-side sound-absorbing member 570 on the Z-direction, more so than on the other side. Therefore, the reflected wave 61b returning to the discharge space from the other side in a predetermined direction is reduced compared to the reflected wave 61b returning to the discharge space from one side in a predetermined direction. Compared to the case where there is no reduction, the change in the density distribution of the laser gas in the discharge space due to the reflected wave 61b can be suppressed, and an unstable main discharge can be suppressed.

[0106] In each modified example of this embodiment, the chamber 131 is described with one side in the Z direction facing the monitor module 160 and the other side facing the narrowband module 145, but the reverse is also possible.

[0107] Furthermore, in the modified example 2, the anode-side sound-absorbing member 570 does not need to gradually rise in the V direction from one side to the other in the Z direction. The anode-side sound-absorbing member 570 may rise in a stepped manner from one side to the other in the Z direction. Also, the anode-side sound-absorbing member 570 in this embodiment and each modified example may not be placed in the groove 137b of the ground plate 137, but rather on the main surface of the ground plate 137.

[0108] 7. Description of the Chamber in Embodiment 5 Next, the chamber 131 of Embodiment 5 will be described. Components similar to those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified. Furthermore, in some drawings, for clarity, some components may be omitted or simplified, and similar components may have reference numerals only for some parts, or some may be omitted entirely.

[0109] 7.1 Configuration Figure 23 is a top view of the area around the anode 500 in this embodiment. In the chamber 131 of this embodiment, in order to suppress the influence of acoustic waves 61a on the performance of the laser light, the longitudinal directions of the dielectric pipe 11 and the outer electrode 15 are inclined with respect to a virtual axis 70, which will be described later, when viewed along the V direction. This is different from Embodiment 1. In Figure 23, to facilitate understanding of this inclination, the central axis 11a of the dielectric pipe 11 inclined with respect to the virtual axis 70 is shown as an example. The virtual axis 70 is an axis that extends in the Z direction between the cathode 400 and the anode 500. The virtual axis 70 is located midway between the cathode 400 and the anode 500 and coincides with the central axis of the anode 500 when viewed along the V direction. Due to the above inclination, the distance from the virtual axis 70 to the dielectric pipe 11 decreases from one side to the other in the Z direction. One side in the Z direction is located towards the monitor module 160, and the other side is located towards the narrowband module 145. Although the above explanation used the dielectric pipe 11, the same applies to the inner electrode 13, the outer electrode 15, the end portion 15a, the part of the cover member 551 that the dielectric pipe 11 contacts, and the cover member 553.

[0110] 7.2 Action and Effects As described above, the shorter distance causes the length of the propagation path of the reflected wave 61b returning from the dielectric pipe 11 to the discharge space to vary depending on the position in a given direction. As a result, the phase of the reflected wave 61b returning to the discharge space is shifted, and compared to the case where there is no phase shift, the simultaneous return of the reflected wave 61b to the discharge space can be suppressed. Consequently, changes in the density distribution of the laser gas in the discharge space due to the reflected wave 61b can be suppressed, and unstable main discharges can be suppressed.

[0111] Furthermore, the ground plate 137 of this embodiment may be provided with the groove 137b and the anode-side sound-absorbing member 570 described in Embodiment 4 and its modified form.

[0112] Next, a modified example of this embodiment will be described. Figure 24 is a top view of the area around the anode 500 in this modified example. In this modified example, the dielectric pipe 11, the outer electrode 15, the portion of the cover member 551 that the dielectric pipe 11 contacts, and the cover member 553 are all inclined with respect to the virtual axis 70, similar to Embodiment 5. The ground plate 137 of this modified example is provided with the groove 137b and the anode-side sound-absorbing member 570 described in Embodiment 4. The groove 137b and the anode-side sound-absorbing member 570 of this modified example will be described later.

[0113] Figure 25 is a cross-sectional view of the area around groove 137b along the GG line shown in Figure 24, Figure 26 is a cross-sectional view of the area around groove 137b along the HH line shown in Figure 24, and Figure 27 is a cross-sectional view of the area around groove 137b along the II line shown in Figure 24.

[0114] In this modified example, the groove 137b and the anode-side sound-absorbing member 570 differ from Embodiment 4 in that the longitudinal directions of the groove 137b and the anode-side sound-absorbing member 570 are inclined with respect to the virtual axis 70, similar to the dielectric pipe 11. Therefore, the anode-side sound-absorbing member 570 and the groove 137b are aligned with the dielectric pipe 11, and the distance from the virtual axis 70 to the anode-side sound-absorbing member 570 decreases from one side to the other in the Z direction. In Figure 24, the portion of the anode-side sound-absorbing member 570 that overlaps with the dielectric pipe 11 is shown with a dashed line. In Figure 26, for comparison with Figure 25, the dielectric pipe 11, internal electrode 13, and anode-side sound-absorbing member 570 shown in Figure 25 are shown with dashed lines. Also, in Figure 27, for comparison with Figure 26, the dielectric pipe 11, internal electrode 13, and anode-side sound-absorbing member 570 shown in Figure 26 are shown with dashed lines. Comparing Figures 25, 26, and 27, it can be seen that the dielectric pipe 11, the internal electrode 13, and the anode-side sound-absorbing member 570 each approach the virtual axis 70 from one side to the other in the Z direction.

[0115] In this configuration, the length of the propagation path of the reflected wave 61b returning from the anode-side sound-absorbing member 570 to the discharge space varies depending on the position in a predetermined direction. As a result, the phase of the reflected wave 61b returning to the discharge space is shifted, and compared to the case where there is no phase shift, the simultaneous return of the reflected wave 61b to the discharge space can be suppressed. Consequently, changes in the density distribution of the laser gas in the discharge space due to the reflected wave 61b can be suppressed, and unstable main discharges can be suppressed.

[0116] In this modified chamber 131, a groove 137b with a depth in the V direction and a constant depth in the Z direction, as described in Embodiment 4, and an anode-side sound-absorbing member 570 with a height in the V direction and a constant height in the Z direction were used. However, in this modified chamber 137b, it is sufficient that the groove 137b and anode-side sound-absorbing member 570 are inclined with respect to the virtual axis 70 as described above, and the groove 137b and anode-side sound-absorbing member 570 described in Modifications 1 and 2 of Embodiment 4 may also be used. Furthermore, the anode-side sound-absorbing member 570 in this modified chamber may be placed on the main surface of the ground plate 137 instead of being placed in the groove 137b of the ground plate 137. Also, the pre-ionization electrode 10 in this modified chamber does not need to be inclined with respect to the virtual axis 70 as in this embodiment. In addition, in this embodiment and this modified chamber 131, one side in the Z direction is described as the monitor module 160 side and the other side as the narrowband module 145 side, but the reverse may also be used.

[0117] The above description is intended to be illustrative and not restrictive. It will 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 herein and throughout the claims should be construed as “non-restrictive” unless otherwise specified. For example, terms such as “includes,” “has,” “equips,” and “possesses” should be construed as “not excluding the existence of components other than those described.” Also, the modifier “one” should be construed as “at least one” or “one or more.” Furthermore, the term “at least one of A, B, and C” should be construed as “A,” “B,” “C,” “A+B,” “A+C,” “B+C,” or “A+B+C,” and should also be construed as including combinations of them with anything other than “A,” “B,” and “C.”

Claims

1. A chamber for a gas laser device that seals laser gas in its internal space, An anode is arranged in the aforementioned internal space, with its longitudinal direction aligned with a predetermined direction, Displaced in the internal space, the discharge portion includes a base and a discharge portion protruding from the base toward the anode, and the cathode is positioned in the predetermined direction, spaced apart from the anode and facing it. A cathode-side cover is provided, which is arranged in the internal space, spaced apart from a part of the base and the discharge section, and covers the base. A cathode-side sound-absorbing member is provided in the gap between a part of the base and the cathode-side cover, Equipped with Chamber of a gas laser device.

2. A chamber for a gas laser apparatus according to claim 1, The cathode-side sound-absorbing member is placed on the base.

3. A chamber for a gas laser apparatus according to claim 1, The cathode-side sound-absorbing member is positioned on the cathode-side cover.

4. A chamber for a gas laser apparatus according to claim 1, The cathode-side sound-absorbing member is positioned on the base and the cathode-side cover, respectively.

5. A chamber for a gas laser apparatus according to claim 4, The cathode-side sound-absorbing member positioned on the base faces the cathode-side sound-absorbing member positioned on the cathode-side cover.

6. A chamber for a gas laser apparatus according to claim 1, The cathode-side sound-absorbing member is also positioned at the location furthest from the discharge space between the cathode and the anode within the gap.

7. A chamber for a gas laser apparatus according to claim 1, The surface of the cathode-side cover that is in contact with the gap is perpendicular to the direction from the anode toward the cathode, extends in the predetermined direction, and is inclined to move away from the anode from one side to the other in the predetermined direction.

8. A chamber for a gas laser apparatus according to claim 7, The cathode-side sound-absorbing member extends in the predetermined direction and is positioned on the base. The height of the cathode-side sound-absorbing member in the direction from the anode to the cathode increases from one side to the other in the predetermined direction.

9. A chamber for a gas laser apparatus according to claim 1, A ground plate is arranged in the internal space on which the anode is placed, An anode-side cover is placed on the ground plate and covers the anode, spaced apart from the anode on the side of the anode, An anode-side sound-absorbing member is provided in the gap between the anode-side cover and the anode, To further prepare.

10. A chamber for a gas laser apparatus according to claim 9, The anode-side sound-absorbing member is positioned on the anode-side cover.

11. A chamber for a gas laser apparatus according to claim 9, The anode-side sound-absorbing member is positioned on the anode.

12. A chamber for a gas laser apparatus according to claim 9, The anode-side sound-absorbing member is arranged on the anode-side cover and the anode, respectively.

13. A chamber for a gas laser apparatus according to claim 1, A ground plate is arranged in the internal space on which the anode is placed, An anode-side sound-absorbing member is placed on the ground plate and positioned in a groove provided on the side of the anode, To further prepare.

14. A chamber for a gas laser apparatus according to claim 13, The groove extends in the predetermined direction, The depth of the groove in a direction perpendicular to the main surface of the ground plate, which is perpendicular to the predetermined direction, increases from one side to the other in the predetermined direction.

15. A chamber for a gas laser apparatus according to claim 14, The anode-side sound-absorbing member extends in the predetermined direction, The height of the anode-side sound-absorbing member in the aforementioned vertical direction is constant from one side to the other in the predetermined direction.

16. A chamber for a gas laser apparatus according to claim 14, The anode-side sound-absorbing member extends in the predetermined direction, The height of the anode-side sound-absorbing member in the aforementioned vertical direction increases from one side to the other in the predetermined direction.

17. A chamber for a gas laser apparatus according to claim 1, The anode is further provided with a pre-ionization electrode located to the side of the anode, The pre-ionization electrode comprises a dielectric pipe, a pre-ionization internal electrode disposed inside the dielectric pipe and extending along the longitudinal direction of the dielectric pipe, and a pre-ionization external electrode extending along the longitudinal direction of the dielectric pipe and including an end facing the dielectric pipe. The distance from the virtual axis extending along the predetermined direction between the cathode and the anode to the dielectric pipe decreases from one side to the other in the predetermined direction.

18. A chamber for a gas laser apparatus according to claim 17, A ground plate is arranged in the internal space on which the anode is placed, The anode-side sound-absorbing member is positioned to the side of the anode of the ground plate, Furthermore, The distance from the virtual axis to the anode-side sound-absorbing member decreases from one side to the other in the predetermined direction.

19. A gas laser device comprising a chamber for sealing laser gas in an internal space, The aforementioned chamber is An anode is arranged in the aforementioned internal space, with its longitudinal direction aligned with a predetermined direction, Displaced in the internal space, the discharge portion includes a base and a discharge portion protruding from the base toward the anode, and the cathode is positioned in the predetermined direction, spaced apart from the anode and facing it. A cathode-side cover is provided, which is arranged in the internal space, spaced apart from a part of the base and the discharge section, and covers the base. A cathode-side sound-absorbing member is provided in the gap between a part of the base and the cathode-side cover, Equipped with Gas laser device.

20. A chamber in which laser gas is sealed in an internal space, An anode is arranged in the aforementioned internal space, with its longitudinal direction aligned with a predetermined direction, Displaced in the internal space, the discharge portion includes a base and a discharge portion protruding from the base toward the anode, and the cathode is positioned in the predetermined direction, spaced apart from the anode and facing it. A cathode-side cover is provided, which is arranged in the internal space, spaced apart from a part of the base and the discharge section, and covers the base. A cathode-side sound-absorbing member is provided in the gap between a part of the base and the cathode-side cover, A gas laser device equipped with a chamber containing a laser beam 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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