Gas laser apparatus and method for manufacturing electronic device

Abstract

In the present invention, a gas laser device comprises: a chamber device that emits light generated from a laser gas; a resonator that causes light emitted from the chamber device to resonate between both sides flanking the chamber device; and a beam expander. The resonator includes an output coupling mirror that is disposed on one side flanking the chamber device, transmits a portion of light emitted from the chamber device, and reflects the other portion of the light emitted from the chamber device so that the reflected light returns to the chamber device. The beam expander is disposed between the chamber device and the output coupling mirror, and includes: a holding unit; a convex mirror including a reflecting surface that reflects light emitted from the chamber device so as to increase the width of the light beam, and a plurality of side surfaces, where only one side surface is fixed to the holding unit by an adhesive agent; and a concave mirror including a reflecting surface that reflects the light reflected by the convex mirror toward the output coupling mirror so as to collimate the light so that the increased width of the light beam will be constant, and a plurality of side surfaces, where only one side surface is fixed to the holding unit by an adhesive agent.

Description

Gas laser device and method for manufacturing electronic device

[0001] The present disclosure relates to gas laser apparatus and methods for manufacturing electronic devices.

[0002] In recent years, semiconductor exposure apparatuses have been required to improve their resolution in response to the miniaturization and high integration of semiconductor integrated circuits. To this end, the wavelength of light emitted from exposure light sources has been shortened. For example, KrF excimer laser devices that output laser light with a wavelength of approximately 248.0 nm and ArF excimer laser devices that output laser light with a wavelength of approximately 193.4 nm are used as gas laser devices for exposure.

[0003] The spectral linewidth of the spontaneously oscillating light of KrF excimer laser devices and ArF excimer laser devices is wide, ranging from 350 pm to 400 pm. Therefore, constructing a projection lens using a material that transmits ultraviolet light, such as KrF and ArF laser light, can result in chromatic aberration. This can result in a decrease in resolution. Therefore, it is necessary to narrow the spectral linewidth of the laser light output from the gas laser device to a level where chromatic aberration is negligible. Therefore, a line-narrowing module (LNM) including a line-narrowing element (e.g., an etalon or grating) may be installed within the laser resonator of the gas laser device to narrow the spectral linewidth. Hereinafter, a gas laser device with a narrowed spectral linewidth is referred to as a line-narrowed gas laser device.

[0004] JP 2016-018076 A U.S. Patent Application Publication No. 2021 / 0336407 overview

[0005] A gas laser device according to one aspect of the present disclosure includes: a chamber device including a pair of discharge electrodes facing each other in an internal space in which laser gas is sealed, and which emits light generated from the laser gas when a voltage is applied between the pair of discharge electrodes; a resonator that causes the light emitted from the chamber device to resonate between both sides of the chamber device; and a beam expander, wherein the resonator is located on one side of the chamber device and includes an output coupling mirror that transmits a portion of the light emitted from the chamber device and reflects another portion of the light emitted from the chamber device back to the chamber device; and the beam expander is located between the chamber device and the output coupling mirror and includes a holder, a reflective surface that reflects light emitted from the chamber device so as to expand the beam width of the light, and a plurality of side surfaces, only one of the plurality of side surfaces being fixed to the holder with an adhesive; and a concave mirror that includes a reflective surface that reflects the light reflected by the convex mirror toward the output coupling mirror so as to collimate the expanded beam width of the light so as to be constant, and a plurality of side surfaces, only one of the plurality of side surfaces being fixed to the holder with an adhesive.

[0006] A method for manufacturing an electronic device according to one aspect of the present disclosure includes a chamber apparatus including a pair of discharge electrodes facing each other in an internal space in which a laser gas is sealed, and emitting light generated from the laser gas when a voltage is applied between the pair of discharge electrodes, a resonator that causes the light emitted from the chamber apparatus to resonate between both sides of the chamber apparatus, and a beam expander, wherein the resonator is disposed on one side of the chamber apparatus and includes an output coupling mirror that transmits a portion of the light emitted from the chamber apparatus and reflects another portion of the light emitted from the chamber apparatus back to the chamber apparatus, and the beam expander is disposed between the chamber apparatus and the output coupling mirror and includes a holder and The pulsed laser light may be generated by a gas laser apparatus including a convex mirror including a reflective surface and a plurality of side surfaces that reflect light emitted from the chamber apparatus so as to expand the beam width of the light, and a concave mirror including a reflective surface and a plurality of side surfaces that reflect the light reflected by the convex mirror toward an output coupling mirror so as to collimate the light so that the expanded beam width of the light becomes constant, and the pulsed laser light may be output to an exposure apparatus, and the pulsed laser light may be exposed onto a photosensitive substrate in the exposure apparatus to manufacture an electronic device.

[0007] Some embodiments of the present disclosure are described below, by way of example only, with reference to the accompanying drawings. FIG. 1 is a schematic diagram illustrating an example of the overall configuration of an electronic device manufacturing apparatus. FIG. 2 is a schematic diagram illustrating an example of the overall configuration of a gas laser apparatus according to a comparative example. FIG. 3 is a schematic diagram illustrating an example of the overall configuration of a beam expander according to a comparative example. FIG. 4 is a perspective view illustrating a convex mirror and a concave mirror according to a comparative example. FIG. 5 is a cross-sectional view of the convex mirror. FIG. 6 is a cross-sectional view of the concave mirror. FIG. 7 is a diagram illustrating how the convex mirror is fixed to the convex mirror holder with an adhesive. FIG. 8 is a diagram illustrating how the concave mirror is fixed to the concave mirror holder with an adhesive. FIG. 9 is a schematic diagram illustrating an example of the overall configuration of a beam expander according to a first embodiment, similar to FIG. 3. FIG. 10 is a cross-sectional view of the beam expander taken along line X-X in FIG. 9. FIG. 11 is a cross-sectional view of the beam expander taken along line XI-XI in FIG. 9. FIG. 12 is a schematic diagram illustrating an example of the overall configuration of a beam expander according to a second embodiment, similar to FIG. 3. Fig. 13 is a perspective view showing the convex mirror, plane mirror, and concave mirror of the second embodiment, similar to Fig. 4. Fig. 14 is a cross-sectional view of the beam expander taken along line XIV-XIV shown in Fig. 12. Fig. 15 is a schematic view showing an example of the general configuration of the beam expander of the third embodiment, similar to Fig. 3. Fig. 16 is a perspective view showing the convex mirror, first plane mirror, second plane mirror, and concave mirror of the third embodiment, similar to Fig. 4. Fig. 17 is a cross-sectional view of the beam expander taken along line XVII-XVII shown in Fig. 15. Embodiment

[0008] 1. Description of an electronic device manufacturing apparatus used in an exposure process for electronic devices 2. Description of a gas laser apparatus as a comparative example 2.1 Configuration 2.2 Operation 2.3 Issues 3. Description of a gas laser apparatus according to a first embodiment 3.1 Configuration 3.2 Operation 3.3 Actions and effects 4. Description of a gas laser apparatus according to a second embodiment 4.1 Configuration 4.2 Operation 4.3 Actions and effects 5. Description of a gas laser apparatus according to a third embodiment 5.1 Configuration 5.2 Operation 5.3 Actions and effects

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Furthermore, not all of the configurations and operations described in each embodiment are necessarily essential as the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and redundant explanations will be omitted.

[0010] 1. Description of an Electronic Device Manufacturing Apparatus Used in an Electronic Device Exposure Process FIG. 1 is a schematic diagram showing an example of the overall configuration of an electronic device manufacturing apparatus used in an electronic device exposure process. As shown in FIG. 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 multiple mirrors 211, 212, and 213, and a projection optical system 220. The illumination optical system 210 illuminates a reticle pattern on a reticle stage RT with laser light incident from the gas laser apparatus 100. The projection optical system 220 reduces and projects the laser light transmitted through the reticle to form an image on a workpiece (not shown) placed on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure apparatus 200 exposes the workpiece with laser light reflecting the reticle pattern by synchronously translating the reticle stage RT and the workpiece table WT. 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.

[0011] 2. Description of a gas laser device as a comparative example 2.1 Configuration A gas laser device as a comparative example will be described. Note that the comparative example in this disclosure refers to a configuration that the applicant recognizes as being known only by the applicant, and is not a publicly known example that the applicant acknowledges.

[0012] 2 is a schematic diagram showing an example of the overall configuration of the gas laser device 100 of this embodiment. The gas laser device 100 uses, for example, argon (Ar), fluorine (F ２The gas laser device 100 is an ArF excimer laser device that uses a mixed gas containing krypton (Kr) and neon (Ne). This gas laser device 100 outputs laser light with a center wavelength of approximately 193.4 nm. Note that the gas laser device 100 may be a gas laser device other than an ArF excimer laser device, such as krypton (Kr), F ２ Alternatively, the gas laser device 100 may be a KrF excimer laser device that uses a mixed gas containing Ar and Ne. In this case, the gas laser device 100 emits laser light with a center wavelength of approximately 248.0 nm. ２ and mixed gases containing Ne and laser media such as Kr and F ２ A mixed gas containing ArF and Ne may be called a laser gas. Note that helium (He) may be used instead of Ne in the mixed gas used in each of the ArF excimer laser device and the KrF excimer laser device.

[0013] The gas laser device 100 of this example mainly comprises a housing 110, a laser oscillator 130 which is a master oscillator arranged in the internal space of the housing 110, an optical transmission unit 141, an amplifier 160 which is a power oscillator, a detection unit 153, a display unit 180, a processor 190, a laser gas exhaust device 701, and a laser gas supply device 703.

[0014] The laser oscillator 130 includes a chamber device CH1, a charger 41, a pulse power module 43, a line narrowing module 60, and an output coupling mirror 70 as its main components.

[0015] 2 shows the internal configuration of the chamber apparatus CH1 as viewed from a direction substantially perpendicular to the direction of travel of the laser light. The chamber apparatus CH1 mainly comprises a housing 30, a pair of windows 31 a, 31 b, a pair of electrodes 32 a, 32 b, an insulating portion 33, a feedthrough 34, and an electrode holder portion 36.

[0016] The laser gas is supplied to the interior space of the housing 30 from the laser gas supply device 703 via piping, and the laser gas is sealed in the interior space. The interior space is where light is generated by excitation of the laser medium in the laser gas. This light travels to the windows 31 a and 31 b.

[0017] Window 31a is disposed on the front wall of housing 30 in the direction of travel of laser light from gas laser device 100 to exposure device 200, and window 31b is disposed on the rear wall of housing 30 in the same direction of travel. Windows 31a and 31b are calcium fluoride substrates, and the surfaces of windows 31a and 31b facing the interior and exterior of housing 30 are flat. Note that windows 31a and 31b are not limited to calcium fluoride substrates as long as they are capable of transmitting laser light. Windows 31a and 31b are inclined at a Brewster's angle with respect to the direction of travel of the laser light so as to suppress reflection of P-polarized light of the laser light.

[0018] The electrodes 32a and 32b are disposed opposite each other in the internal space of the housing 30, with the longitudinal direction of the electrodes 32a and 32b aligned along the direction of light generated by a high voltage applied between the electrodes 32a and 32b. The space between the electrodes 32a and 32b in the housing 30 is sandwiched between the windows 31a and 31b. The electrodes 32a and 32b are discharge electrodes for exciting the laser medium by glow discharge. In this example, the electrode 32a is the cathode, and the electrode 32b is the anode.

[0019] The electrode 32a is supported by an insulating part 33. The insulating part 33 closes an opening formed in the housing 30. The insulating part 33 includes an insulator. A feedthrough 34 made of a conductive material is also disposed in the insulating part 33. The feedthrough 34 applies a voltage supplied from a pulse power module 43 to the electrode 32a. The electrode 32b is supported by an electrode holder part 36 and is electrically connected to the electrode holder part 36.

[0020] The charger 41 is a DC power supply device that charges a capacitor (not shown) provided inside the pulse power module 43 with a predetermined voltage. The charger 41 is disposed outside the housing 30 and connected to the pulse power module 43. The pulse power module 43 includes a switch (not shown) controlled by the processor 190. When the switch is turned from OFF to ON by this control, the pulse power module 43 is a voltage application circuit that boosts the voltage applied from the charger 41 to generate a pulsed high voltage and applies this high voltage to the electrodes 32 a and 32 b. When the high voltage is applied, a discharge occurs between the electrodes 32 a and 32 b. The energy of this discharge excites the laser medium inside the housing 30. When the excited laser gas transitions to the ground state, light is emitted, and the emitted light passes through the windows 31 a and 31 b and is emitted to the outside of the housing 30.

[0021] The line narrowing module 60 includes a housing 65, a prism 61, a grating 63, and a rotation stage (not shown) that are arranged in the internal space of the housing 65. An opening is formed in the housing 65, and the housing 65 is connected to the rear side of the housing 30 via the opening.

[0022] The prism 61 expands the beam width of light emitted from the window 31b and makes the light incident on the grating 63. The prism 61 also reduces the beam width of light reflected from the grating 63 and returns the light to the internal space of the housing 30 via the window 31b. The prism 61 is supported by a rotation stage and rotates by the rotation stage. The rotation of the prism 61 changes the angle of incidence of the light with respect to the grating 63. Therefore, by rotating the prism 61, it is possible to select the wavelength of the light that returns from the grating 63 via the prism 61 to the housing 30. Although FIG. 2 shows an example in which one prism 61 is arranged, two or more prisms may be arranged.

[0023] The surface of the grating 63 is made of a highly reflective material, and has numerous grooves formed at predetermined intervals on the surface. The grating 63 is a dispersive optical element. The cross-sectional shape of each groove is, for example, a right-angled triangle. Light incident on the grating 63 from the prism 61 is reflected by these grooves and diffracted in a direction according to the wavelength of the light. The grating 63 is Littrow-oriented so that the angle of incidence of the light incident on the grating 63 from the prism 61 matches the angle of diffraction of the diffracted light of the desired wavelength. This allows the light of the desired wavelength to be returned to the housing 30 via the prism 61.

[0024] The output coupling mirror 70 faces the window 31 a, transmits a portion of the laser light emitted from the window 31 a, and reflects the other portion back through the window 31 a into the internal space of the housing 30. The output coupling mirror 70 is fixed to a holder (not shown), and is disposed in the internal space of the housing 110.

[0025] A Fabry-Perot resonator is formed by the grating 63 and the output coupling mirror 70, which are provided on either side of the housing 30, and the housing 30 is disposed on the optical path of the resonator, so that the resonator resonates light between both sides of the chamber device CH1.

[0026] The optical transmission unit 141 mainly includes high-reflection mirrors 141b and 141c. The high-reflection mirrors 141b and 141c are fixed to holders (not shown) with their respective tilt angles adjusted, and are disposed in the internal space of the housing 110. The high-reflection mirrors 141b and 141c highly reflect the laser light. The high-reflection mirrors 141b and 141c are disposed on the optical path of the laser light from the output coupling mirror 70. The laser light is reflected by the high-reflection mirrors 141b and 141c and travels to the rear mirror 371 of the amplifier 160. At least a portion of this laser light is transmitted through the rear mirror 371.

[0027] The amplifier 160 amplifies the energy of the laser beam output from the laser oscillator 130. The basic configuration of the amplifier 160 is generally the same as that of the laser oscillator 130. To distinguish the components of the amplifier 160 from the components of the laser oscillator 130, the components will be described as a chamber device CH3, a housing 330, a pair of windows 331a and 331b, a pair of electrodes 332a and 332b, an insulating section 333, a feedthrough 334, an electrode holder section 336, a charger 341, a pulse power module 343, and an output coupling mirror 370. The electrodes 332a and 332b generate a discharge for amplifying the laser beam from the laser oscillator 130. The pulse power module 343 is a voltage application circuit, similar to the pulse power module 43.

[0028] The amplifier 160 also differs from the laser oscillator 130 mainly in that it does not include the line narrowing module 60 but includes a rear mirror 371 and a beam expander 400 .

[0029] The rear mirror 371 is provided between the high-reflection mirror 141c and the window 331b and faces them. The rear mirror 371 transmits part of the laser light from the laser oscillator 130 toward the space between the electrodes 332a and 332b, and reflects part of the laser light amplified by the electrodes 332a and 332b toward the space between the electrodes 332a and 332b.

[0030] The output coupling mirror 370 is disposed on the opposite side of the chamber device CH3 from the rear mirror 371 side, and the beam expander 400 is disposed between the chamber device CH3 and the output coupling mirror 370.

[0031] 3 is a schematic diagram showing an example of the outline configuration of the beam expander 400 of this example, and is a schematic diagram of the beam expander 400 as viewed along a direction perpendicular to the optical axis LA1 of the laser light emitted from the window 331 a and the direction in which the electrodes 332 a and 332 b face each other. As shown in FIG. 3, in this example, the beam expander 400 includes a convex mirror 410, a concave mirror 420, and a holder 450.

[0032] 4 is a perspective view showing the convex mirror 410 and the concave mirror 420 of this example. The convex mirror 410 is a plate-shaped member and includes a reflective surface 411 that reflects light, multiple side surfaces 412, and a back surface 413 located on the back side of the reflective surface 411 and facing the reflective surface 411. The concave mirror 420 is a plate-shaped member and includes a reflective surface 421 that reflects light, multiple side surfaces 422, and a back surface 423 located on the back side of the reflective surface 421 and facing the reflective surface 421. The reflective surface 411 of the convex mirror 410 reflects the laser light from the chamber device CH3 toward the concave mirror 420 so as to expand the beam width of the laser light. The reflective surface 421 of the concave mirror 420 reflects the laser light toward the output coupling mirror 370 so as to collimate the expanded beam width of the laser light reflected by the convex mirror 410 to a constant value. Furthermore, the concave mirror 420 reflects the laser light from the output coupling mirror 370 toward the convex mirror 410 so that the beam width of the laser light is reduced. The convex mirror 410 reflects the laser light toward the chamber device CH3 so as to collimate the laser light reflected by the concave mirror 420 so that the reduced beam width of the laser light becomes constant, and the laser light returns to the internal space of the housing 330 through the window 331 a.

[0033] In this example, the convex mirror 410 is a convex cylindrical mirror, and the shape of the convex mirror 410 when the reflecting surface 411 is viewed from the front is a rectangle whose long sides are long in a direction parallel to the focal line 410L of the convex mirror 410. The concave mirror 420 is a concave cylindrical mirror, and the shape of the concave mirror 420 when the reflecting surface 421 is viewed from the front is a rectangle whose long sides are long in a direction parallel to the focal line 420L of the concave mirror 420. Therefore, the convex mirror 410 includes four planar side surfaces 412, and the concave mirror 420 includes four planar side surfaces 422. The focal line 410L is a line connecting the focal points of the convex mirror 410, and the focal line 420L is a line connecting the focal points of the concave mirror 420. The shapes of the convex mirror 410 and the concave mirror 420, and the number of side surfaces 412, 422 are not limited. For example, the shape of the convex mirror 410 may be a rectangle whose longer side is in the direction perpendicular to the focal line 410L, and the shape of the concave mirror 420 may be a rectangle whose longer side is in the direction perpendicular to the focal line 420L.

[0034] 5 is a cross-sectional view of convex mirror 410, and the cross-section is parallel to the normal to reflecting surface 411 of convex mirror 410 and perpendicular to the plane of incidence of laser light emitted from window 331a onto reflecting surface 411. As shown in FIG. 5, the shape of reflecting surface 411 in the cross-section is an arc, but the shape is not limited to this and may be a parabola, for example.

[0035] 6 is a cross-sectional view of concave mirror 420, and the cross-section is parallel to the normal to reflecting surface 421 of concave mirror 420 and perpendicular to the plane of incidence of laser light reflected by convex mirror 410 toward concave mirror 420 relative to reflecting surface 421. As shown in FIG. 6, the shape of reflecting surface 421 in the cross-section is an arc, but the shape is not limited to this and may be a parabola, for example.

[0036] Returning to FIG. 3 , the focal line 410L of the convex mirror 410 is contained in a plane that includes the optical axis LA1 of the laser beam and extends in the direction in which the electrodes 332a and 332b face each other, and tilts toward the electrode 332a as it moves away from the chamber apparatus CH3. The focal line 420L of the concave mirror 420 is contained in a plane that includes the optical axis LA1 of the laser beam and the focal line 410L, and tilts toward the electrode 332a as it moves away from the chamber apparatus CH3. The focal lines 410L and 420L are located on the same line. That is, the positions of the convex mirror 410 and the concave mirror 420 are adjusted so that they are located on the same line. The focal lines 410L and 420L do not necessarily have to be located on the same line.

[0037] The holding unit 450 holds the convex mirror 410 and the concave mirror 420. In this example, the holding unit 450 includes a base member 451, a convex mirror holder 460, and a concave mirror holder 470.

[0038] The convex mirror holder 460 in this example is a plate-shaped member extending along the back surface 413 of the convex mirror 410, and the back surface 413 of the convex mirror 410 is fixed to the main surface 461 on the convex mirror 410 side with an adhesive. FIG. 7 is a diagram showing how the convex mirror 410 is fixed to the convex mirror holder 460 with an adhesive. As shown in FIG. 7 , the adhesive 462 is separated into multiple adhesive portions. By disposing the adhesive 462 between the main surface 461 of the convex mirror holder 460 and the back surface 413 of the convex mirror 410, the main surface 461 and the back surface 413 are separated, and a space is formed in the area between the main surface 461 and the back surface 413 where the adhesive 462 is not disposed. Examples of the adhesive 462 include an ultraviolet-curing adhesive, and examples of the ultraviolet-curing adhesive include a urethane acrylate adhesive. Note that the adhesive 462 does not have to be separated into multiple adhesive portions.

[0039] The concave mirror holder 470 in this example is a plate-shaped member extending along the back surface 423 of the concave mirror 420, and the back surface 423 of the concave mirror 420 is fixed to a main surface 471 on the concave mirror 420 side with an adhesive. FIG. 8 is a diagram showing how the concave mirror 420 is fixed to the concave mirror holder 470 with an adhesive. As shown in FIG. 8 , the adhesive 472 that fixes the back surface 423 to the main surface 471 is separated into multiple adhesive portions, similar to the adhesive 462. Therefore, by disposing the adhesive 472 between the main surface 471 and the back surface 423, the main surface 471 and the back surface 423 are separated from each other, and a space is formed in the area between the main surface 471 and the back surface 423 where the adhesive 472 is not disposed. For example, an adhesive similar to the adhesive 462 can be used as the adhesive 472. Note that the adhesive 472 does not have to be separated into multiple adhesive portions.

[0040] In this example, the base member 451 is a plate-shaped member extending in a direction parallel to the optical axis LA1 of the laser light emitted from the window 331a of the chamber device CH3. In this example, the base member 451 extends in a direction in which the electrodes 332a and 332b face each other, and a convex mirror holder 460 and a concave mirror holder 470 are fixed to one main surface 452 of the base member 451. In this manner, the convex mirror 410 is fixed to the base member 451 via the convex mirror holder 460, and the concave mirror 420 is fixed to the base member 451 via the concave mirror holder 470. Therefore, the convex mirror 410 is fixed to the holder 450 by the adhesive 462, and the concave mirror 420 is fixed to the holder 450 by the adhesive 472, and the convex mirror 410 and the concave mirror 420 are held by the holder 450.

[0041] 2, a partially reflective film having a predetermined reflectance is coated on the surface of the output coupling mirror 370 facing the beam expander 400. The output coupling mirror 370 reflects a portion of the laser light from the chamber device CH3, the beam width of which has been expanded by the beam expander 400, toward the beam expander 400, and transmits the other portion of the laser light.

[0042] The output coupling mirror 370 may be circular. The surface of the output coupling mirror 370 facing the beam expander 400 and the surface opposite to that surface may be flat. The rear mirror 371 and the output coupling mirror 370 have a configuration similar to that of the output coupling mirror 70.

[0043] The rear mirror 371 and output coupling mirror 370, which are disposed on either side of the housing 330, form a resonator that resonates the laser light amplified by the electrodes 332a and 332b. The housing 330 and the beam expander 400 are disposed on the optical path of the resonator. The laser light emitted from the window 331a of the housing 330 passes through the beam expander 400 and enters the output coupling mirror 370, where it is reflected by the output coupling mirror 370. The laser light reflected by the output coupling mirror 370 returns to the internal space of the housing 330 via the beam expander 400 and the window 331b, and is emitted from the window 331a. The laser light emitted from the window 331a is reflected by the rear mirror 371 and returns to the internal space of the housing 330 via the window 331b. In this way, the laser light emitted from the housing 330 travels back and forth between the rear mirror 371 and the output coupling mirror 370. The reciprocating laser light is amplified each time it passes through the laser gain space between the electrodes 332a and 332b. In other words, the resonator resonates light between both sides of the chamber device CH3, and the output coupling mirror 370 is disposed on one side of the chamber device CH3. A portion of the amplified laser light passes through the output coupling mirror 370. The laser light that passes through the output coupling mirror 370 proceeds to the detection unit 153.

[0044] The detection unit 153 mainly includes a beam splitter 153b and an optical sensor 153c.

[0045] The beam splitter 153b is disposed on the optical path of the laser light passing through the output coupling mirror 370. The beam splitter 153b transmits the laser light passing through the output coupling mirror 370 toward the exit window 173 with high transmittance, and also reflects a portion of the laser light toward the light receiving surface of the optical sensor 153c.

[0046] The optical sensor 153c measures the pulse energy of the laser light incident on the light receiving surface of the optical sensor 153c. The optical sensor 153c is electrically connected to the processor 190 and outputs a signal indicating the measured pulse energy to the processor 190. The processor 190 controls the voltage applied to the electrodes 332a and 332b of the amplifier 160 based on the signal.

[0047] An exit window 173 is provided on the opposite side of the output coupling mirror 370 with respect to the beam splitter 153b of the detection unit 153. The exit window 173 is provided on the wall of the housing 110. The light that passes through the beam splitter 153b is emitted from the exit window 173 to the exposure device 200 outside the housing 110. This laser light is, for example, pulsed laser light with a center wavelength of 193.4 nm.

[0048] The display unit 180 is a monitor that displays the state of control by the processor 190 based on a signal from the processor 190. The display unit 180 may be disposed outside the housing 110.

[0049] The processor 190 of the present disclosure is a processing device including a storage device in which a control program is stored and a CPU (Central Processing Unit) that executes the control program. The processor 190 is specially configured or programmed to execute the various processes included in the present disclosure. The processor 190 also controls the entire gas laser apparatus 100. The processor 190 is also electrically connected to an exposure processor (not shown) of the exposure apparatus 200, and transmits and receives various signals to and from the exposure processor.

[0050] Laser gas exhaust device 701 and laser gas supply device 703 are electrically connected to processor 190. Laser gas exhaust device 701 includes an exhaust pump (not shown), and exhausts laser gas from the internal space of housing 30, 330 via piping by suction of the exhaust pump in response to a control signal from processor 190. Laser gas supply device 703 supplies laser gas from a laser gas supply source (not shown) located outside housing 110 to the internal space of housing 30, 330 via piping in response to a control signal from processor 190.

[0051] 2.2 Operation Next, the operation of the gas laser device 100 of the comparative example will be described.

[0052] Before gas laser device 100 emits laser light, laser gas is supplied from laser gas supply device 703 to the internal space of housings 30 and 330 .

[0053] When the gas laser apparatus 100 emits laser light, the processor 190 receives a signal indicating the target energy Et and a light emission trigger signal from an exposure processor (not shown) of the exposure apparatus 200. The target energy Et is a target value for the laser light energy used in the exposure process. The processor 190 sets a predetermined charging voltage in the charger 41 so that the energy E becomes the target energy Et, and turns on the pulse power module 43 in synchronization with the light emission trigger signal. This causes the pulse power module 43 to generate a pulsed high voltage from the electrical energy stored in the charger 41, and the high voltage is applied between the electrodes 32a and 32b. When the high voltage is applied, a discharge occurs between the electrodes 32a and 32b, exciting the laser medium contained in the laser gas between the electrodes 32a and 32b. The laser medium emits light when it returns to its ground state. The emitted light resonates between the grating 63 and the output coupling mirror 70 and is amplified each time it passes through a discharge space in the internal space of the housing 30, resulting in laser oscillation. The laser light contains a first linearly polarized light, and when passing through windows 31 a and 31 b, linearly polarized light having a polarization direction different from the polarization direction of the first linearly polarized light is reduced from the laser light. A portion of the laser light passes through output coupling mirror 70, is reflected by high-reflection mirrors 141 b and 141 c, passes through rear mirror 371 and window 331 b, and proceeds into housing 330.

[0054] The processor 190 turns on the switch of the pulse power module 343 so that a discharge occurs when the laser light from the laser oscillator 130 travels into the discharge space in the housing 330. That is, the processor 190 controls the pulse power module 343 so that a high voltage is applied to the electrodes 332 a, 332 b after a predetermined delay time has elapsed since the switch of the pulse power module 343 was turned on.

[0055] As a result, the laser light incident on amplifier 160 is amplified in amplifier 160. Furthermore, the laser light that has traveled into the internal space of housing 330 exits window 331a and travels to beam expander 400 as described above. The laser light that has traveled to beam expander 400 is reflected by convex mirror 410 toward concave mirror 420. The cross-sectional shape of the reflecting surface 411 of convex mirror 410 is an arc, and a focal line 410L of convex mirror 410 is included in a plane that includes the optical axis LA1 of the laser light and extends in the direction in which electrodes 332a, 332b face each other. Therefore, the laser light that exits window 331a is reflected by convex mirror 410 toward concave mirror 420 so that the beam width of the laser light expands in a direction perpendicular to the direction in which electrodes 332a, 332b face each other.

[0056] The laser light with its expanded beam width is reflected by the concave mirror 420 toward the output coupling mirror 370. The cross-sectional shape of the reflecting surface 421 of the concave mirror 420 is an arc, and the focal line 410L of the convex mirror 410 and the focal line 420L of the concave mirror 420 are included in the same plane that contains the optical axis LA1 of the laser light, and the focal line 410L and the focal line 420L are located on the same straight line. Therefore, the laser light with its expanded beam width is reflected by the concave mirror 420 so as to be collimated so that the expanded beam width remains constant. The collimated laser light then enters the output coupling mirror 370.

[0057] A portion of the laser light incident on output coupling mirror 370 is reflected by output coupling mirror 370 and then reflected by concave mirror 420 toward convex mirror 410. The beam width of this laser light is reduced in a direction perpendicular to the direction in which electrodes 332a and 332b face each other. The laser light with its reduced beam width is reflected by convex mirror 410 toward window 331a. This laser light is collimated so that the reduced beam width remains constant, travels through window 331a into the internal space of housing 330, and exits through window 331b. The light exiting window 331b is reflected by rear mirror 371 and travels through window 331b into the internal space of housing 330. In this way, laser light of a predetermined wavelength travels back and forth between rear mirror 371 and output coupling mirror 370. The laser light is amplified each time it passes through the discharge space inside housing 330, and part of the laser light becomes amplified laser light.

[0058] Furthermore, the amplified laser light from the amplifier 160 passes through the output coupling mirror 370 and travels to the beam splitter 153b.

[0059] A portion of the amplified laser light that has reached the beam splitter 153b passes through the beam splitter 153b and the exit window 173 and travels to the exposure device 200, while the other portion is reflected by the beam splitter 153b and travels to the optical sensor 153c.

[0060] The optical sensor 153c measures the energy E of the received amplified laser beam. The optical sensor 153c outputs a signal indicating the measured energy E to the processor 190. The processor 190 feedback-controls the charging voltage of the chargers 41, 341 so that the difference ΔE between the energy E and the target energy Et falls within an allowable range. The laser beam whose difference ΔE falls within the allowable range passes through the beam splitter 153b and the exit window 173 and enters the exposure device 200.

[0061] 2.3 Issues In the comparative example, the beam expander 400 expands the beam width of the laser light emitted from the chamber device CH3 using the convex mirror 410 and the concave mirror 420 and emits the light toward the output coupling mirror 370. This reduces the energy density of the laser light incident on the output coupling mirror 370, thereby suppressing deterioration of the output coupling mirror 370 over time. Generally, the reflective surface of a reflective member reflects most of the incident light, but some of the light passes through the reflective member without being reflected by the reflective surface. Therefore, some of the laser light incident on the reflective surface 411 of the convex mirror 410 travels inside the convex mirror 410 and exits from the back surface 413 opposite the reflective surface 411. Furthermore, some of the laser light incident on the reflective surface 421 of the concave mirror 420 travels inside the concave mirror 420 and exits from the back surface 423 opposite the reflective surface 421. In the comparative example, rear surface 413 of convex mirror 410 is fixed to convex mirror holder 460 with adhesive 462, and rear surface 423 of concave mirror 420 is fixed to concave mirror holder 470 with adhesive 472. For this reason, there is a concern that laser light will be irradiated onto adhesives 462, 472, causing deterioration of adhesives 462, 472 and reducing the durability of the gas laser device.

[0062] Therefore, in the following embodiment, a gas laser device capable of suppressing a decrease in durability is exemplified.

[0063] 3. Description of the Gas Laser Apparatus of Embodiment 1 Next, a description will be given of the gas laser apparatus 100 of embodiment 1. Note that the same components as those described above are assigned the same reference numerals, and redundant description will be omitted unless otherwise specified. Also, in some drawings, some components are omitted or simplified for clarity.

[0064] 9 is a schematic diagram showing an example of the general configuration of the beam expander 400 of embodiment 1, similar to Fig. 3. As shown in Fig. 9, in the beam expander 400 of this embodiment, the main difference from the configurations of the convex mirror holder 460 and the concave mirror holder 470 of the comparative example is the configurations of the convex mirror holder 460 and the concave mirror holder 470.

[0065] 10 is a cross-sectional view of the beam expander 400 along the X-X line shown in FIG. 9 , and is a cross-sectional view of the beam expander 400 crossing the convex mirror 410 parallel to the focal line 410L. As shown in FIG. 10 , the convex mirror holder 460 of this embodiment is a plate-shaped member extending along a specific side surface 412, which is one of two side surfaces 412 extending along the longitudinal direction of the convex mirror 410. Only one specific side surface 422 of the convex mirror 410 is fixed to the main surface 461 of the convex mirror holder 460 on the convex mirror 410 side with an adhesive 462. The adhesive 462 is separated into multiple adhesive portions. By disposing the adhesive 462 between the main surface 461 of the convex mirror holder 460 and the specific side surface 412 of the convex mirror 410, the main surface 461 and the specific side surface 412 are separated from each other, and a space is formed in the area where the adhesive 462 is not disposed between the main surface 461 and the specific side surface 412. Note that the adhesive 462 does not have to be separated into multiple adhesive portions.

[0066] The convex mirror holder 460 includes a convex mirror protrusion 463 that protrudes from the main surface 461 and is positioned around the convex mirror 410. The convex mirror protrusion 463 does not contact the convex mirror 410, and the convex mirror 410 is surrounded by the convex mirror protrusion 463. The convex mirror protrusion 463 also overlaps with the convex mirror 410 in a direction along a specific side surface 412.

[0067] The convex mirror holder 460 is fixed to the base member 451 with a main surface 464 opposite the convex mirror 410 side abutting against a main surface 452 of the base member 451. In this embodiment, the convex mirror holder 460 is fixed to the base member 451 by adhesive 453 that is placed at the contact portion between a pair of opposing side surfaces 465 of the convex mirror holder 460 and the main surface 452 of the base member 451. The position of the adhesive 453 is not limited. For example, the adhesive 453 may be placed between the main surface 464 of the convex mirror holder 460 and the main surface 452 of the base member 451.

[0068] Width 410W1 of convex mirror 410 in a direction perpendicular to specific side surface 412 of convex mirror 410 is preferably 10 mm or more and 40 mm or less, but there is no limitation on width 410W1. Furthermore, width 410W2 of convex mirror 410 in a direction along edge 412e of specific side surface 412 of convex mirror 410 on the reflecting surface 411 side is preferably 15 mm or more and 50 mm or less, but there is no limitation on width 410W2.

[0069] 11 is a cross-sectional view of the beam expander 400 taken along line XI-XI in FIG. 9 , and is a cross-sectional view of the beam expander 400 crossing the concave mirror 420 parallel to the focal line 420L. As shown in FIG. 11 , the concave mirror holder 470 of this embodiment is a plate-shaped member extending along a specific side surface 422, which is one of two side surfaces 422 extending along the longitudinal direction of the concave mirror 420. Only the specific side surface 422 of the concave mirror 420 is fixed to the main surface 471 of the concave mirror holder 470 on the concave mirror 420 side with an adhesive 472. The adhesive 472 is separated into multiple adhesive portions. By disposing the adhesive 472 between the main surface 471 of the concave mirror holder 470 and the specific side surface 422 of the concave mirror 420, the main surface 471 and the specific side surface 422 are separated from each other, and a space is formed in the area where the adhesive 472 is not disposed between the main surface 471 and the specific side surface 422. Note that the adhesive 472 does not have to be separated into multiple adhesive portions.

[0070] The concave mirror holder 470 includes a concave mirror protrusion 473 that protrudes from the main surface 471 and is positioned around the concave mirror 420. The concave mirror protrusion 473 is not in contact with the concave mirror 420, and the concave mirror 420 is surrounded by the concave mirror protrusion 473. In addition, the concave mirror protrusion 473 overlaps with the concave mirror 420 in a direction along a specific side surface 422.

[0071] The concave mirror holder 470 is fixed to the base member 451 with its main surface 474 opposite the concave mirror 420 side abutting against the main surface 452 of the base member 451. In this embodiment, the concave mirror holder 470 is mechanically fixed to the main surface 452 of the base member 451 by two bolts 454 that sandwich the concave mirror 420 in a direction parallel to the focal line 420L. The number and positions of the bolts 454 are not limited. Furthermore, the mechanical fixation is not limited to fixation by the bolts 454. For example, the concave mirror holder 470 may be fixed to the main surface 452 of the base member 451 by hooks.

[0072] Width 420W1 of concave mirror 420 in a direction perpendicular to specific side surface 422 of concave mirror 420 is preferably 10 mm or more and 40 mm or less, but there is no limitation on width 420W1. Furthermore, width 420W2 of concave mirror 420 in a direction along edge 422e of specific side surface 422 of concave mirror 420 on the reflecting surface 421 side is preferably 15 mm or more and 50 mm or less, but there is no limitation on width 420W2.

[0073] 3.2 Operation In the beam expander 400 of this embodiment, as in the beam expander 400 of the comparative example, the laser light emitted from the window 331a of the chamber device CH3 is reflected by the convex mirror 410 and then the concave mirror 420, and the beam width of the laser light is expanded in a direction perpendicular to the direction in which the electrodes 332a and 332b face each other. The laser light with its expanded beam width then enters the output coupling mirror 370. A portion of the laser light incident on the output coupling mirror 370 is reflected by the output coupling mirror 370. The laser light reflected by the output coupling mirror 370 is reflected by the concave mirror 420 and then the convex mirror 410, and the beam width of the laser light is reduced in a direction perpendicular to the direction in which the electrodes 332a and 332b face each other. The laser light with its reduced beam width travels through the window 331a into the internal space of the housing 330 and is output from the window 331b. The light emitted from window 331b is reflected by rear mirror 371 and travels through window 331b into the internal space of housing 330. In this way, the laser light travels back and forth between rear mirror 371 and output coupling mirror 370, and is amplified each time it passes through the discharge space inside housing 330.

[0074] 3.3 Actions and Effects As with the beam expander 400 of the comparative example, the beam expander 400 of this embodiment can reduce the energy density of the laser light incident on the output coupling mirror 370, thereby suppressing deterioration of the output coupling mirror 370 over time. Furthermore, in the beam expander 400 of this embodiment, only one specific side surface 412 of the convex mirror 410 is fixed to the convex mirror holder 460 with adhesive 462, and only one specific side surface 422 of the concave mirror 420 is fixed to the concave mirror holder 470 with adhesive 472. Therefore, with the gas laser apparatus 100 of this embodiment, it is possible to suppress irradiation of the adhesive 462 with laser light that is incident on the reflecting surface 411 of the convex mirror 410 and passes through the convex mirror 410, compared to when the back surface 413 of the convex mirror 410 is fixed to the convex mirror holder 460 with adhesive 462. Furthermore, compared to when the back surface 423 of the concave mirror 420 is fixed to the concave mirror holder 470 with the adhesive 472, laser light incident on the reflective surface 421 of the concave mirror 420 and passing through the concave mirror 420 can be prevented from being irradiated onto the adhesive 472. Therefore, the gas laser apparatus 100 of this embodiment can prevent deterioration of the adhesives 462, 472 due to the laser light, thereby preventing a decrease in the durability of the gas laser apparatus 100. Generally, adhesives shrink when hardened. However, because the thickness of the applied adhesive tends to vary depending on the application position due to manufacturing errors and the like, the amount of shrinkage of the adhesive tends to vary depending on the application position. Therefore, when the back surface 413 of the convex mirror 410 is fixed with the adhesive 462, there is a concern that the reflective surface 411 will be distorted due to variations in the amount of shrinkage of the adhesive 462. Similarly, when the back surface 423 of the concave mirror 420 is fixed with the adhesive 472, there is a concern that the reflective surface 421 will be distorted due to variations in the amount of shrinkage of the adhesive 472. Of the distortions of the reflecting surfaces 411 and 421, the more the distortion is in a direction perpendicular to the respective reflecting surfaces 411 and 421, the greater the effect on the beam profile of the laser light tends to be. In the beam expander 400 of this embodiment, as described above, only one specific side surface 412 of the convex mirror 410 is fixed with adhesive 462, and only one specific side surface 422 of the concave mirror 420 is fixed with adhesive 472.Therefore, the direction of contraction of adhesive 462 can approach a direction parallel to reflecting surface 411 of convex mirror 410, and the direction of contraction of adhesive 472 can approach a direction parallel to reflecting surface 421 of concave mirror 420. Therefore, according to gas laser device 100 of this embodiment, distortion of reflecting surface 411 in a direction perpendicular to reflecting surface 411 and distortion of reflecting surface 421 in a direction perpendicular to reflecting surface 421 can be suppressed, and the influence on the beam profile of laser light can be suppressed.

[0075] In the beam expander 400 of this embodiment, the convex mirror holder 460 includes convex mirror protrusions 463 that protrude from the main surface 461 and are located around the convex mirror 410. Therefore, according to the gas laser device 100 of this embodiment, it is possible to prevent the adhesive 462 from being deteriorated due to scattered light being irradiated onto the adhesive 462, compared to when the convex mirror holder 460 does not include the convex mirror protrusions 463. Note that the convex mirror holder 460 does not have to include the convex mirror protrusions 463.

[0076] In the beam expander 400 of this embodiment, the convex mirror 410 is surrounded by the convex mirror protrusions 463. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress deterioration of the adhesive 462 caused by scattered light being irradiated onto the adhesive 462, compared to a case in which the convex mirror 410 is not surrounded by the convex mirror protrusions 463.

[0077] In the beam expander 400 of this embodiment, the convex mirror protrusion 463 overlaps with the convex mirror 410 in a direction along a specific side surface 412 of the convex mirror 410 to which the adhesive 462 is fixed. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress deterioration of the adhesive 462 due to scattered light being irradiated onto the adhesive 462, compared to a case in which the convex mirror protrusion 463 does not overlap with the convex mirror 410 in the above direction. Note that the convex mirror protrusion 463 does not have to overlap with the convex mirror 410 in the above direction.

[0078] In the beam expander 400 of this embodiment, the concave mirror holder 470 includes concave mirror protrusions 473 that protrude from the main surface 471 and are located around the concave mirror 420. Therefore, according to the gas laser device 100 of this embodiment, it is possible to prevent the adhesive 472 from being deteriorated due to scattered light being irradiated onto the adhesive 472, compared to when the concave mirror holder 470 does not include the concave mirror protrusions 473. Note that the concave mirror holder 470 does not have to include the concave mirror protrusions 473.

[0079] In the beam expander 400 of this embodiment, the concave mirror 420 is surrounded by the concave mirror protrusions 473. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress deterioration of the adhesive 472 caused by scattered light being irradiated onto the adhesive 472, compared to a case in which the concave mirror 420 is not surrounded by the concave mirror protrusions 473.

[0080] In the beam expander 400 of this embodiment, the concave mirror protrusion 473 overlaps with the concave mirror 420 in a direction along a specific side surface 422 of the concave mirror 420 to which the concave mirror 420 is fixed with the adhesive 472. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress deterioration of the adhesive 472 due to scattered light being irradiated onto the adhesive 472, compared to a case in which the concave mirror protrusion 473 does not overlap with the concave mirror 420 in the above direction. Note that the concave mirror protrusion 473 does not have to overlap with the concave mirror 420 in the above direction.

[0081] In this embodiment, the convex mirror 410 is surrounded by the convex mirror protrusion 463 without contacting the convex mirror protrusion 463, and the concave mirror 420 is surrounded by the concave mirror protrusion 473 without contacting the concave mirror protrusion 473. However, the convex mirror protrusion 463 and the convex mirror 410 may be in contact with each other, and the concave mirror protrusion 473 and the concave mirror 420 may be in contact with each other. However, at least one of the convex mirror protrusion 463 and the convex mirror 410, and the concave mirror protrusion 473 and the concave mirror 420 may be in contact with each other. Furthermore, the convex mirror 410 does not have to be surrounded by the convex mirror protrusion 463, and the concave mirror 420 does not have to be surrounded by the concave mirror protrusion 473. However, it is preferable that at least one of the convex mirror 410 and the concave mirror 420 is surrounded by a corresponding protrusion from among the convex mirror protrusion 463 and the concave mirror protrusion 473. The protrusion corresponding to the convex mirror 410 is the convex mirror protrusion 463, and the protrusion corresponding to the concave mirror 420 is the concave mirror protrusion 473.

[0082] In this embodiment, only a specific side surface 412 extending along the longitudinal direction of the convex mirror 410 is fixed with adhesive 462, and only a specific side surface 422 extending along the longitudinal direction of the concave mirror 420 is fixed with adhesive 472. However, the one side surface 412 of the convex mirror 410 fixed with adhesive 462 and the one side surface 422 of the concave mirror 420 fixed with adhesive 472 are not limited to the specific side surfaces 412, 422 described above. For example, only one side surface 412 extending along the lateral direction of the convex mirror 410 may be fixed with adhesive 462, and only one side surface 422 extending along the lateral direction of the concave mirror 420 may be fixed with adhesive 472.

[0083] In this embodiment, the holding unit 450 includes a base member 451, a convex mirror holder 460, and a concave mirror holder 470. However, the holding unit 450 is not limited to this, as long as only one side surface 412 of the convex mirror 410 is fixed with adhesive 462 and only one side surface 422 of the concave mirror 420 is fixed with adhesive 472. For example, the holding unit 450 does not need to include the convex mirror holder 460 and the concave mirror holder 470. In this case, for example, only one side surface 412 of the convex mirror 410 is fixed to the main surface 452 of the base member 451 with adhesive 462, and only one side surface 422 of the concave mirror 420 is fixed to the main surface 452 of the base member 451 with adhesive 472. In this case, the base member 451 may include at least one of a convex mirror protrusion 463 and a concave mirror protrusion 473.

[0084] In this embodiment, the convex mirror holder 460 is fixed to the main surface 452 of the base member 451 with adhesive 453, and the concave mirror holder 470 is mechanically fixed to the main surface 452 of the base member 451. However, the method of fixing the convex mirror holder 460 and the concave mirror holder 470 to the base member 451 is not limited. For example, at least one of the convex mirror holder 460 and the concave mirror holder 470 may be fixed to the base member 451 with an adhesive. Alternatively, one of the convex mirror holder 460 and the concave mirror holder 470 may be fixed to the base member 451 with an adhesive, and the other may be fixed to the base member 451 mechanically.

[0085] 4. Description of the Gas Laser Apparatus of Embodiment 2 Next, a gas laser apparatus 100 of embodiment 2 will be described. Note that components similar to those described above are assigned the same reference numerals, and redundant description will be omitted unless otherwise specified. Also, in some drawings, some components have been omitted or simplified for clarity.

[0086] 12 is a schematic diagram showing an example of the general configuration of the beam expander 400 of this embodiment, similar to Fig. 3. As shown in Fig. 12, the beam expander 400 of this embodiment differs from the beam expander 400 of Embodiment 1 mainly in that it further includes a plane mirror 430 and that the holding unit 450 further includes a plane mirror holder 480.

[0087] 13 is a perspective view similar to FIG. 4 , showing the convex mirror 410, the plane mirror 430, and the concave mirror 420 of this embodiment. As shown in FIGS. 12 and 13 , in this embodiment, the convex mirror 410 reflects the laser light from the chamber device CH3 toward the plane mirror 430. The plane mirror 430 is a plate-shaped member and includes a flat reflective surface 431 that reflects light, multiple side surfaces 432, and a back surface 433 located behind and facing the reflective surface 431. The reflective surface 431 of the plane mirror 430 reflects the laser light reflected by the convex mirror 410 toward the concave mirror 420. The concave mirror 420 reflects the laser light reflected by the plane mirror 430 toward the output coupling mirror 370. In addition, the concave mirror 420 reflects the laser light reflected by the output coupling mirror 370 toward the plane mirror 430, the plane mirror 430 reflects the laser light reflected by the concave mirror 420 toward the convex mirror 410, and the convex mirror 410 reflects the laser light reflected by the plane mirror 430 toward the chamber device CH3.

[0088] The focal line 410L of the convex mirror 410 is included in a plane that includes the optical axis LA1 of the laser beam and extends in the direction in which the electrodes 332a and 332b face each other, and tilts toward the electrode 332a as it moves away from the chamber apparatus CH3. The focal line 420L of the concave mirror 420 is included in a plane that includes the optical axis LA1 of the laser beam and the focal line 410L, and tilts toward the electrode 332b as it moves away from the chamber apparatus CH3. The focal line 410Lv in the virtual image 410v of the convex mirror 410 formed by the reflecting surface 431 of the plane mirror 430 and the focal line 420L of the concave mirror 420 are located on the same line. The optical axis LA1 of the laser beam traveling from the chamber apparatus CH3 to the convex mirror 410 and the optical axis LA2 of the laser beam traveling from the concave mirror 420 to the output coupling mirror 370 are located on the same line. That is, the positions of the convex mirror 410, the plane mirror 430, and the concave mirror 420 are adjusted in this manner. In Fig. 12, a virtual image 410v and a focal line 410Lv in the virtual image 410v are indicated by dashed lines.

[0089] In this embodiment, the shape of the plane mirror 430 when the reflecting surface 431 is viewed from the front is a rectangle that is elongated in a direction parallel to the optical axis LA1 of the laser light from the chamber apparatus CH3. Therefore, the plane mirror 430 includes four planar side surfaces 432. Note that the shape of the plane mirror 430 and the number of side surfaces 432 are not limited. For example, the shape of the plane mirror 430 may be a rectangle that is elongated in a direction perpendicular to the optical axis LA1.

[0090] FIG. 14 is a cross-sectional view of the beam expander 400 taken along line XIV-XIV in FIG. 12 , and is a cross-sectional view of the beam expander 400 crossing the plane mirror 430 parallel to the reflecting surface 431. As shown in FIG. 14 , the plane mirror holder 480 of this embodiment is a plate-shaped member extending along a specific side surface 432, which is one of two side surfaces 432 extending along the longitudinal direction of the plane mirror 430. Only the specific side surface 432 of the plane mirror 430 is fixed to the main surface 481 of the plane mirror holder 480 facing the plane mirror 430 with adhesive 482. The adhesive 482 is separated into multiple adhesive portions. By disposing the adhesive 482 between the main surface 481 of the plane mirror holder 480 and the specific side surface 432 of the plane mirror 430, the main surface 481 and the specific side surface 432 are separated from each other, and a space is formed in the area between the main surface 481 and the specific side surface 432 where the adhesive 482 is not disposed. The adhesive 482 may be, for example, the same adhesive as the adhesive 462. Note that the adhesive 482 does not have to be separated into a plurality of adhesive portions.

[0091] The plane mirror holder 480 includes a plane mirror protrusion 483 that protrudes from a main surface 481 and is positioned around the plane mirror 430. The plane mirror protrusion 483 does not contact the plane mirror 430, and the plane mirror 430 is surrounded by the plane mirror protrusion 483. The plane mirror protrusion 483 also overlaps with the plane mirror 430 in a direction along a specific side surface 432.

[0092] The plane mirror holder 480 is fixed to the base member 451 with the main surface 484 opposite the plane mirror 430 side abutting against the main surface 452 of the base member 451. In this embodiment, the concave mirror holder 470 is mechanically fixed to the main surface 452 of the base member 451 by two bolts 454, similar to the concave mirror holder 470 of embodiment 1. Note that the number and positions of the bolts 454 are not limited. Furthermore, the mechanical fixation is not limited to fixation by the bolts 454. For example, the plane mirror holder 480 may be fixed to the main surface 452 of the base member 451 by a hook.

[0093] A width 430W1 of the plane mirror 430 in a direction perpendicular to the specific side surface 432 of the plane mirror 430 is preferably 10 mm or more and 40 mm or less, but there is no limitation on the width 430W1. Furthermore, a width 430W2 of the plane mirror 430 in a direction along an edge 432e of the specific side surface 432 of the plane mirror 430 on the reflecting surface 431 side is preferably 15 mm or more and 50 mm or less, but there is no limitation on the width 430W2.

[0094] The convex mirror holder 460 of this embodiment, like the concave mirror holder 470 of embodiment 1, is mechanically fixed to the main surface 452 of the base member 451 by two bolts 454. Note that the number and positions of the bolts 454 are not limited. Furthermore, the mechanical fixation is not limited to fixation by the bolts 454. For example, the convex mirror holder 460 may be fixed to the main surface 452 of the base member 451 by a hook.

[0095] The concave mirror holder 470 of this embodiment is fixed to the base member 451 by adhesive 453, similar to the convex mirror holder 460 of embodiment 1. The position of the adhesive 453 is not limited. For example, the adhesive 453 may be disposed between the main surface 474 of the concave mirror holder 470 and the main surface 452 of the base member 451.

[0096] 4.2 Operation As in the first embodiment, the laser light emitted from the window 331a is reflected by the convex mirror 410, and the beam width of the laser light is expanded in a direction perpendicular to the direction in which the electrodes 332a and 332b face each other. The laser light with this expanded beam width is reflected by the reflecting surface 431 of the plane mirror 430 toward the concave mirror 420. As described above, the focal line 410Lv of the virtual image 410v and the focal line 420L of the concave mirror 420 are located on the same straight line. Therefore, the laser light reflected by the plane mirror 430 is reflected by the concave mirror 420 so as to be collimated so that the expanded beam width is constant, and the collimated laser light enters the output coupling mirror 370.

[0097] Furthermore, the laser light reflected by output coupling mirror 370 is reflected by concave mirror 420 toward plane mirror 430. The beam width of this laser light is reduced in a direction perpendicular to the direction in which electrodes 332a and 332b face each other. The laser light with this reduced beam width is reflected by plane mirror 430 toward convex mirror 410, and the laser light reflected by plane mirror 430 is reflected by convex mirror 410 toward window 331a. This laser light is collimated so that the reduced beam width remains constant, and returns to the internal space of housing 330 via window 331a.

[0098] 4.3 Actions and Effects As with the gas laser apparatus 100 of Embodiment 1, the gas laser apparatus 100 of this embodiment can reduce the energy density of the laser light incident on the output coupling mirror 370, thereby suppressing deterioration of the output coupling mirror 370 over time. Furthermore, in the beam expander 400 of this embodiment, only one specific side surface 432 of the plane mirror 430 is fixed to the plane mirror holder 480 with the adhesive 472. Therefore, the gas laser apparatus 100 of this embodiment can prevent laser light incident on the reflecting surface 431 of the plane mirror 430 and passing through the plane mirror 430 from irradiating the adhesive 482, compared to a case in which the back surface 433 of the plane mirror 430 is fixed to the plane mirror holder 480 with the adhesive 482. Therefore, the gas laser apparatus 100 of this embodiment can prevent deterioration of the adhesive 482 due to the laser light, thereby suppressing a decrease in the durability of the gas laser apparatus 100. Furthermore, according to the gas laser device 100 of this embodiment, similar to the convex mirror 410 and concave mirror 420 of embodiment 1, distortion of the reflecting surface 431 in a direction perpendicular to the reflecting surface 431 can be suppressed, thereby suppressing the effect on the beam profile of the laser light.

[0099] In the beam expander 400 of this embodiment, the plane mirror holder 480 includes plane mirror protrusions 483 that protrude from the main surface 481 and are located around the plane mirror 430. Therefore, according to the gas laser device 100 of this embodiment, it is possible to prevent scattered light from irradiating the adhesive 482 and causing deterioration of the adhesive 482, compared to when the plane mirror holder 480 does not include the plane mirror protrusions 483. Note that the plane mirror holder 480 does not have to include the plane mirror protrusions 483.

[0100] In the beam expander 400 of this embodiment, the plane mirror 430 is surrounded by the plane mirror protrusions 483. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress deterioration of the adhesive 482 caused by scattered light being irradiated onto the adhesive 482, compared to a case in which the plane mirror 430 is not surrounded by the plane mirror protrusions 483.

[0101] In the beam expander 400 of this embodiment, the plane mirror protrusion 483 overlaps with the plane mirror 430 in a direction along a specific side surface 432 of the plane mirror 430 to which the plane mirror 430 is fixed with the adhesive 482. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress deterioration of the adhesive 482 due to scattered light being irradiated onto the adhesive 482, compared to a case in which the plane mirror protrusion 483 does not overlap with the plane mirror 430 in the above direction. Note that the plane mirror protrusion 483 does not have to overlap with the plane mirror 430 in the above direction.

[0102] In this embodiment, the plane mirror 430 is surrounded by the plane mirror protrusions 483 without contacting the plane mirror protrusions 483, but the plane mirror protrusions 483 and the plane mirror 430 may also be in contact with each other. However, at least one of the convex mirror protrusions 463 and the convex mirror 410, the concave mirror protrusions 473 and the concave mirror 420, and the plane mirror protrusions 483 and the plane mirror 430 may not be in contact with each other. Also, it is preferable that at least one of the convex mirror 410, the concave mirror 420, and the plane mirror 430 is surrounded by a corresponding protrusion from among the convex mirror protrusions 463, the concave mirror protrusions 473, and the plane mirror protrusions 483. The protrusion corresponding to the convex mirror 410 is the convex mirror protrusion 463, the protrusion corresponding to the concave mirror 420 is the concave mirror protrusion 473, and the protrusion corresponding to the plane mirror 430 is the plane mirror protrusion 483.

[0103] In this embodiment, only a specific side surface 432 extending along the longitudinal direction of the plane mirror 430 is fixed with the adhesive 482. However, the one side surface 432 of the plane mirror 430 fixed with the adhesive 482 is not limited to the specific side surface 432 described above. For example, only one side surface 432 extending along the lateral direction of the plane mirror 430 may be fixed with the adhesive 482.

[0104] In this embodiment, the holding unit 450 includes a base member 451, a convex mirror holder 460, a concave mirror holder 470, and a plane mirror holder 480. However, the holding unit 450 is not limited to this, as long as only one side surface 412 of the convex mirror 410 is fixed with adhesive 462, only one side surface 422 of the concave mirror 420 is fixed with adhesive 472, and only one side surface 432 of the plane mirror 430 is fixed with adhesive 482. For example, the holding unit 450 does not need to include the plane mirror holder 480. In this case, for example, only one side surface 432 of the plane mirror 430 is fixed to the main surface 452 of the base member 451 with adhesive 482. In this case, the base member 451 may include a plane mirror protrusion 483.

[0105] In this embodiment, the convex mirror holder 460 and the plane mirror holder 480 are mechanically fixed to the main surface 452 of the base member 451, and the concave mirror holder 470 is fixed to the main surface 452 of the base member 451 with adhesive 453. However, the method of fixing the convex mirror holder 460, the concave mirror holder 470, and the plane mirror holder 480 to the base member 451 is not limited. For example, at least one of the convex mirror holder 460 and the concave mirror holder 470 may be fixed to the base member 451 with adhesive. Alternatively, one of the convex mirror holder 460 and the concave mirror holder 470 may be fixed to the base member 451 with adhesive, and the other may be fixed to the base member 451 mechanically. Alternatively, the plane mirror holder 480 may be fixed to the base member 451 with adhesive.

[0106] In this embodiment, the focal line 410Lv and the focal line 420L in the virtual image 410v are located on the same straight line, but the focal line 410Lv and the focal line 420Lv do not have to be located on the same straight line.

[0107] In this embodiment, the optical axis LA1 of the laser light directed from the chamber device CH3 to the convex mirror 410 and the optical axis LA2 of the laser light directed from the concave mirror 420 to the output coupling mirror 370 are positioned on the same straight line. Therefore, for example, the beam expander 400 can be disposed in an existing amplifier 160 without changing the design positions of the chamber device CH3 or the output coupling mirror 370. Note that the optical axis LA1 and the optical axis LA2 do not have to be positioned on the same straight line.

[0108] 5. Description of Gas Laser Apparatus of Embodiment 3 Next, a gas laser apparatus 100 of embodiment 3 will be described. Note that components similar to those described above are assigned the same reference numerals, and redundant description will be omitted unless otherwise specified. Also, in some drawings, some components have been omitted or simplified for clarity.

[0109] 15 is a schematic diagram showing an example of the general configuration of the beam expander 400 of this embodiment, similar to Fig. 3. As shown in Fig. 15, the beam expander 400 of this embodiment differs from the beam expander 400 of embodiment 2 mainly in that it further includes a plane mirror 440 and that the holding unit 450 further includes a plane mirror holder 490.

[0110] 16 is a perspective view showing the convex mirror 410, two plane mirrors 430 and 440, and the concave mirror 420 of this embodiment, similar to Fig. 4. Hereinafter, the plane mirror 430 will be referred to as the first plane mirror, the plane mirror 440 will be referred to as the second plane mirror, the plane mirror holder 480 will be referred to as the first plane mirror holder, the plane mirror holder 490 will be referred to as the second plane mirror holder, and the plane mirror protrusion 483 will be referred to as the first plane mirror protrusion.

[0111] In this embodiment, the convex mirror 410 reflects the laser light from the chamber device CH3 toward the first plane mirror 430. The first plane mirror 430 reflects the laser light reflected by the convex mirror 410 toward the second plane mirror 440. The second plane mirror 440 is a plate-shaped member and includes a flat reflective surface 441 that reflects light, a plurality of side surfaces 442, and a back surface 443 that is located behind and faces the reflective surface 441. The reflective surface 441 of the second plane mirror 440 reflects the laser light reflected by the first plane mirror 430 toward the concave mirror 420. The concave mirror 420 reflects the laser light reflected by the second plane mirror 440 toward the output coupling mirror 370. Furthermore, the concave mirror 420 reflects the laser light reflected by the output coupling mirror 370 toward the second plane mirror 440, and the second plane mirror 440 reflects the laser light reflected by the concave mirror 420 toward the first plane mirror 430. The first plane mirror 430 reflects the laser light reflected by the second plane mirror 440 toward the convex mirror 410, and the convex mirror 410 reflects the laser light reflected by the first plane mirror 430 toward the chamber device CH3.

[0112] The focal line 410L of the convex mirror 410 is included in a plane that includes the optical axis LA1 of the laser beam and extends in the direction in which the electrodes 332a and 332b face each other, and tilts toward the electrode 332a as it moves away from the chamber apparatus CH3. The focal line 420L of the concave mirror 420 is included in a plane that includes the optical axis LA1 of the laser beam and the focal line 410L, and tilts toward the electrode 332b as it moves away from the chamber apparatus CH3. The focal line 410Lv in the virtual image 410v of the convex mirror 410 formed by the reflecting surface 431 of the first plane mirror 430 and the focal line 420Lv in the virtual image 420v of the concave mirror 420 formed by the reflecting surface 441 of the second plane mirror 440 are located on the same straight line. Furthermore, the optical axis LA1 of the laser light directed from chamber apparatus CH3 to convex mirror 410 and the optical axis LA2 of the laser light directed from concave mirror 420 to output coupling mirror 370 are positioned on the same straight line. That is, the positions of convex mirror 410, first plane mirror 430, second plane mirror 440, and concave mirror 420 are adjusted so that this occurs. In Figure 15, virtual image 410v and focal line 410Lv in virtual image 410v, and virtual image 420v and focal line 420Lv in virtual image 420v are indicated by dashed lines.

[0113] In this embodiment, the shape of the second plane mirror 440 when the reflecting surface 441 is viewed from the front is a rectangle that is elongated in a direction parallel to the optical axis LA1 of the laser light from the chamber apparatus CH3. Therefore, the second plane mirror 440 includes four planar side surfaces 442. Note that the shape of the second plane mirror 440 and the number of side surfaces 442 are not limited. For example, the shape of the second plane mirror 440 may be a rectangle that is elongated in a direction perpendicular to the optical axis LA1.

[0114] 17 is a cross-sectional view of the beam expander 400 taken along line XVII-XVII shown in FIG. 15 , and is a cross-sectional view of the beam expander 400 crossing the second plane mirror 440 parallel to the reflecting surface 441. As shown in FIG. 17 , the second plane mirror holder 490 of this embodiment is a plate-like member extending along a specific side surface 442, which is one of two side surfaces 442 extending along the longitudinal direction of the second plane mirror 440. Only the specific side surface 442 of the second plane mirror 440 is fixed to the main surface 491 of the second plane mirror holder 490 on the second plane mirror 440 side with an adhesive 492. The adhesive 492 is separated into a plurality of adhesive portions. By disposing the adhesive 492 between the main surface 491 of the second plane mirror holder 490 and the specific side surface 442 of the second plane mirror 440, the main surface 491 and the specific side surface 442 are separated from each other, and a space is formed in the area where the adhesive 492 is not disposed between the main surface 491 and the specific side surface 442. An example of the adhesive 492 is an adhesive similar to the adhesive 462. Note that the adhesive 492 does not have to be separated into multiple adhesive portions.

[0115] The second plane mirror holder 490 includes a second plane mirror protrusion 493 that protrudes from the main surface 491 and is positioned around the second plane mirror 440. The second plane mirror protrusion 493 does not contact the second plane mirror 440, and the second plane mirror 440 is surrounded by the second plane mirror protrusion 493. The second plane mirror protrusion 493 also overlaps with the second plane mirror 440 in the direction along the specific side surface 442.

[0116] The second plane mirror holder 490 is fixed to the base member 451 with its main surface 494 opposite the second plane mirror 440 side abutting against the main surface 452 of the base member 451. In this embodiment, the concave mirror holder 470 is mechanically fixed to the main surface 452 of the base member 451 by two bolts 454, similar to the concave mirror holder 470 of embodiment 1. The number and positions of the bolts 454 are not limited. Furthermore, the mechanical fixation is not limited to fixation by the bolts 454. For example, the second plane mirror holder 490 may be fixed to the main surface 452 of the base member 451 by a hook.

[0117] A width 440W1 of the second plane mirror 440 in a direction perpendicular to the specific side surface 442 of the second plane mirror 440 is preferably 10 mm or more and 40 mm or less, but is not limited to this. Furthermore, a width 440W2 of the second plane mirror 440 in a direction along an edge 442e of the specific side surface 442 of the second plane mirror 440 on the reflecting surface 441 side is preferably 15 mm or more and 50 mm or less, but is not limited to this.

[0118] The convex mirror holder 460 of this embodiment is fixed to the base member 451 by adhesive 453, similar to the convex mirror holder 460 of embodiment 1. The position of the adhesive 453 is not limited. For example, the adhesive 453 may be disposed between the main surface 464 of the convex mirror holder 460 and the main surface 452 of the base member 451.

[0119] The concave mirror holder 470, first plane mirror holder 480, and second plane mirror holder 490 of this embodiment are mechanically fixed to the main surface 452 of the base member 451 by two bolts 454, similar to the concave mirror holder 470 of embodiment 1. The number and positions of the bolts 454 are not limited. Furthermore, the mechanical fixation is not limited to fixation by the bolts 454. For example, the concave mirror holder 470, first plane mirror holder 480, and second plane mirror holder 490 may be fixed to the main surface 452 of the base member 451 by hooks.

[0120] 5.2 Operation As in the second embodiment, the laser light emitted from the window 331a is reflected by the convex mirror 410, and the beam width of the laser light is expanded in a direction perpendicular to the direction in which the electrodes 332a and 332b face each other. The laser light with the expanded beam width is reflected by the first plane mirror 430 toward the second plane mirror 440, and the laser light reflected by the first plane mirror 430 is reflected by the reflecting surface 441 of the second plane mirror 440 toward the concave mirror 420. As described above, the focal line 410Lv in the virtual image 410v and the focal line 420Lv in the virtual image 420v are located on the same line. Therefore, the laser light reflected by the second plane mirror 440 is reflected by the concave mirror 420 so as to be collimated so that the expanded beam width is constant, and the collimated laser light enters the output coupling mirror 370.

[0121] Furthermore, the laser light reflected by output coupling mirror 370 is reflected by concave mirror 420 toward second plane mirror 440. The beam width of this laser light is reduced in a direction perpendicular to the direction in which electrodes 332a and 332b face each other. The laser light with this reduced beam width is reflected by second plane mirror 440 toward first plane mirror 430, and the laser light reflected by second plane mirror 440 is reflected by first plane mirror 430 toward concave mirror 420. The laser light reflected by first plane mirror 430 is reflected by convex mirror 410 toward window 331a. This laser light is collimated so that the reduced beam width remains constant, and returns to the internal space of housing 330 via window 331a.

[0122] 5.3 Actions and Effects As with the gas laser apparatus 100 of Embodiment 1, the gas laser apparatus 100 of this embodiment can reduce the energy density of the laser light incident on the output coupling mirror 370, thereby suppressing deterioration of the output coupling mirror 370 over time. Furthermore, in the beam expander 400 of this embodiment, only one specific side surface 442 of the second plane mirror 440 is fixed to the second plane mirror holder 490 with the adhesive 492. Therefore, the gas laser apparatus 100 of this embodiment can prevent laser light that enters through the reflecting surface 441 of the second plane mirror 440 and passes through the second plane mirror 440 from irradiating the adhesive 492, compared to when the back surface 443 of the second plane mirror 440 is fixed to the plane mirror holder 490 with the adhesive 492. Therefore, the gas laser apparatus 100 of this embodiment can prevent deterioration of the adhesive 492 due to the laser light, thereby suppressing a decrease in the durability of the gas laser apparatus 100. Furthermore, according to the gas laser device 100 of this embodiment, similar to the convex mirror 410 and concave mirror 420 of embodiment 1, distortion of the reflecting surface 441 in a direction perpendicular to the reflecting surface 441 can be suppressed, thereby suppressing the impact on the beam profile of the laser light.

[0123] In the beam expander 400 of this embodiment, the second plane mirror holder 490 includes second plane mirror protrusions 493 that protrude from the main surface 491 and are located around the second plane mirror 440. Therefore, according to the gas laser device 100 of this embodiment, it is possible to prevent the adhesive 492 from being deteriorated by scattered light, compared to when the second plane mirror holder 490 does not include the second plane mirror protrusions 493. Note that the second plane mirror holder 490 does not have to include the second plane mirror protrusions 493.

[0124] In the beam expander 400 of this embodiment, the second plane mirror 440 is surrounded by the second plane mirror protrusion 493. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress deterioration of the adhesive 492 caused by scattered light being irradiated onto the adhesive 492, compared to a case in which the second plane mirror 440 is not surrounded by the second plane mirror protrusion 493.

[0125] In the beam expander 400 of this embodiment, the second plane mirror protrusion 493 overlaps with the second plane mirror 440 in a direction along a specific side surface 442 of the second plane mirror 440 to which the adhesive 492 is fixed. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress deterioration of the adhesive 492 due to scattered light being irradiated onto the adhesive 492, compared to a case in which the second plane mirror protrusion 493 does not overlap with the second plane mirror 440 in the above direction. Note that the plane mirror protrusion 483 does not have to overlap with the second plane mirror 440 in the above direction.

[0126] In this embodiment, the second plane mirror 440 is surrounded by the second plane mirror protrusion 493 without contacting the second plane mirror protrusion 493, but the second plane mirror protrusion 493 and the second plane mirror 440 may be in contact with each other. However, at least one of the convex mirror protrusion 463 and the convex mirror 410, the concave mirror protrusion 473 and the concave mirror 420, the first plane mirror protrusion 483 and the first plane mirror 430, and the second plane mirror protrusion 493 and the second plane mirror 440 may be in contact with each other. Furthermore, it is preferable that at least one of the convex mirror 410, the concave mirror 420, the first plane mirror 430, and the second plane mirror 440 be surrounded by a corresponding protrusion from the convex mirror protrusion 463, the concave mirror protrusion 473, the first plane mirror protrusion 483, and the second plane mirror protrusion 493. The protrusion corresponding to the convex mirror 410 is a protrusion for a convex mirror 463, the protrusion corresponding to the concave mirror 420 is a protrusion for a concave mirror 473, the protrusion corresponding to the first plane mirror 430 is a protrusion for a first plane mirror 483, and the protrusion corresponding to the second plane mirror 440 is a protrusion for a second plane mirror 493.

[0127] In this embodiment, only a specific side surface 442 extending along the longitudinal direction of the second plane mirror 440 is fixed with the adhesive 492. However, the one side surface 442 of the second plane mirror 440 fixed with the adhesive 492 is not limited to the specific side surface 442 described above. For example, only one side surface 442 extending along the short direction of the second plane mirror 440 may be fixed with the adhesive 492.

[0128] In this embodiment, the holding unit 450 includes a base member 451, a convex mirror holder 460, a concave mirror holder 470, a first plane mirror holder 480, and a second plane mirror holder 490. However, the holding unit 450 is not limited to this, as long as only one side 412 of the convex mirror 410 is fixed with adhesive 462, only one side 422 of the concave mirror 420 is fixed with adhesive 472, only one side 432 of the first plane mirror 430 is fixed with adhesive 492, and only one side 442 of the second plane mirror 440 is fixed with adhesive 492. For example, the holding unit 450 does not need to include the second plane mirror holder 490. In this case, for example, only one side 442 of the second plane mirror 440 may be fixed to the main surface 452 of the base member 451 with adhesive 492, and the base member 451 may include a second plane mirror protrusion 493.

[0129] In this embodiment, the convex mirror holder 460 is fixed to the main surface 452 of the base member 451 with adhesive 453, and the concave mirror holder 470, the first plane mirror holder 480, and the second plane mirror holder 490 are mechanically fixed to the main surface 452 of the base member 451. However, the method of fixing the convex mirror holder 460, the concave mirror holder 470, the first plane mirror holder 480, and the second plane mirror holder 490 to the base member 451 is not limited. For example, at least one of the convex mirror holder 460 and the concave mirror holder 470 may be fixed to the base member 451 with adhesive. Alternatively, one of the convex mirror holder 460 and the concave mirror holder 470 may be fixed to the base member 451 with adhesive, and the other may be fixed to the base member 451 mechanically. Alternatively, the second plane mirror holder 490 may be fixed to the base member 451 with adhesive.

[0130] In amplifier 160 of this embodiment, the only components that reflect laser light from chamber device CH3 to output coupling mirror 370 are convex mirror 410, first plane mirror 430, second plane mirror 440, and concave mirror 420, and the laser light is reflected four times. Therefore, gas laser device 100 of this embodiment can prevent inversion of the beam profile due to reflection between the laser light traveling from chamber device CH3 to convex mirror 410 and the laser light traveling from concave mirror 420 to output coupling mirror 370.

[0131] In this embodiment, the focal line 410Lv in the virtual image 410v and the focal line 420Lv in the virtual image 420v are located on the same straight line, but the focal line 410Lv and the focal line 420Lv do not have to be located on the same straight line.

[0132] In this embodiment, the optical axis LA1 of the laser light directed from the chamber device CH3 to the convex mirror 410 and the optical axis LA2 of the laser light directed from the concave mirror 420 to the output coupling mirror 370 are positioned on the same straight line. Therefore, for example, the beam expander 400 can be disposed in an existing amplifier 160 without changing the design positions of the chamber device CH3 or the output coupling mirror 370. Note that the optical axis LA1 and the optical axis LA2 do not have to be positioned on the same straight line.

[0133] Although the above embodiments have been described as examples, the present disclosure is not limited to these and can be modified as appropriate.

[0134] In the above embodiments, the convex mirror 410 is described as reflecting the laser beam so that the beam width of the laser beam emitted from the chamber apparatus CH3 is expanded in a direction perpendicular to the direction in which the electrodes 332 a and 332 b face each other. However, the direction in which the beam width is expanded by the convex mirror 410 is not limited. For example, the direction in which the beam width is expanded by the convex mirror 410 may be the direction in which the electrodes 332 a and 332 b face each other.

[0135] Furthermore, in each of the above embodiments, the gas laser apparatus 100 is described as including the laser oscillator 130 and the amplifier 160. However, the gas laser apparatus 100 does not have to include the amplifier 160. In this case, for example, the beam expander 400 is disposed between the chamber apparatus CH1 and the output coupling mirror 70, and the laser light emitted from the window 31 a of the chamber apparatus CH3 is incident on the convex mirror 410.

[0136] The above description is intended to be illustrative, not limiting. Accordingly, it will be apparent to one skilled in the art that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. It will also be apparent to one skilled in the art that the embodiments of the present disclosure can be used in combination. Terms used throughout this specification and claims should be construed as "open-ended" terms unless expressly stated. For example, terms such as "comprise," "have," "comprise," and "equip" should be interpreted as meaning "without excluding the presence of elements other than those listed." The modifier "a" or "an" should be interpreted as meaning "at least one" or "one or more." 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," including combinations other than "A," "B," and "C."

Claims

1. A chamber apparatus including a pair of discharge electrodes facing each other in an internal space in which laser gas is sealed, and emitting light generated from the laser gas when a voltage is applied between the pair of discharge electrodes; a resonator that causes the light emitted from the chamber apparatus to resonate between both sides of the chamber apparatus; and a beam expander, wherein the resonator is disposed on one side of the chamber apparatus and includes an output coupling mirror that transmits a portion of the light emitted from the chamber apparatus and reflects another portion of the light emitted from the chamber apparatus back to the chamber apparatus, and the beam expander is disposed between the chamber apparatus and the output coupling mirror and comprises: a holding section; and a convex mirror that includes a reflective surface that reflects the light emitted from the chamber apparatus so as to expand the beam width of the light, and multiple side surfaces, only one of the multiple side surfaces being fixed to the holding section with an adhesive; a reflective surface that reflects the light reflected by the convex mirror toward the output coupling mirror so as to collimate the light so that the expanded beam width of the light is constant, and a concave mirror that includes a plurality of side surfaces, only one of which is fixed to the holding portion with an adhesive.

2. A gas laser device as described in claim 1, wherein the holding portion includes a convex mirror protrusion protruding from the surface to which the one side of the convex mirror is fixed with an adhesive and positioned around the convex mirror, and a concave mirror protrusion protruding from the surface to which the one side of the concave mirror is fixed with an adhesive and positioned around the concave mirror.

3. A gas laser device as claimed in claim 2, wherein at least one of the convex mirror protrusion and the convex mirror, and the concave mirror protrusion and the concave mirror are not in contact with each other.

4. A gas laser device as claimed in claim 3, wherein at least one of the convex mirror and the concave mirror is surrounded by a corresponding one of the protrusions for the convex mirror and the protrusion for the concave mirror.

5. A gas laser device as described in claim 1, wherein the holding portion includes a plate-shaped base member extending in a direction parallel to the optical axis of the light traveling from the chamber device to the convex mirror, a convex mirror holder to which the one side of the convex mirror is fixed with an adhesive and which is fixed to one main surface of the base member, and a concave mirror holder to which the one side of the concave mirror is fixed with an adhesive and which is fixed to the one main surface of the base member.

6. A gas laser device as set forth in claim 5, wherein at least one of the convex mirror holder and the concave mirror holder is fixed to said one of the main surfaces with an adhesive.

7. A gas laser device as set forth in claim 6, wherein one of said convex mirror holder and said concave mirror holder is fixed to said one main surface with an adhesive, and the other is mechanically fixed to said one main surface.

8. A gas laser device as described in claim 1, wherein the shape of the convex mirror when the reflecting surface of the convex mirror is viewed from the front, and the shape of the concave mirror when the reflecting surface of the concave mirror is viewed from the front, are rectangular.

9. A gas laser device as claimed in claim 8, wherein the one side surface of the convex mirror extends along the longitudinal direction of the concave mirror, and the one side surface of the concave mirror extends along the longitudinal direction of the concave mirror.

10. A gas laser device as described in claim 1, wherein the width of the convex mirror in a direction perpendicular to said one side surface of the convex mirror and the width of the concave mirror in a direction perpendicular to said one side surface of the concave mirror are 10 mm or more and 40 mm or less.

11. A gas laser device as described in claim 1, wherein the width of the convex mirror in a direction along the edge of one of the edges of the convex mirror that faces the reflecting surface, and the width of the concave mirror in a direction along the edge of one of the edges of the concave mirror that faces the reflecting surface, are 15 mm or more and 50 mm or less.

12. A gas laser device as described in claim 1, wherein the beam expander further includes a plane mirror including a reflective surface that reflects the light reflected by the convex mirror toward the concave mirror, and a plurality of side surfaces, only one of which is fixed to the holding portion with an adhesive.

13. A gas laser device as described in claim 12, wherein the holding portion includes a convex mirror protrusion protruding from the surface to which the one side of the convex mirror is fixed with an adhesive and positioned around the convex mirror, a concave mirror protrusion protruding from the surface to which the one side of the concave mirror is fixed with an adhesive and positioned around the concave mirror, and a plane mirror protrusion protruding from the surface to which the one side of the plane mirror is fixed with an adhesive and positioned around the plane mirror.

14. A gas laser device as claimed in claim 13, wherein at least one of the convex mirror protrusion and the convex mirror, the concave mirror protrusion and the concave mirror, and the plane mirror protrusion and the plane mirror are not in contact with each other.

15. A gas laser apparatus as claimed in claim 13, wherein at least one of the convex mirror, the concave mirror and the plane mirror is surrounded by a corresponding one of the protrusions for the convex mirror, the protrusions for the concave mirror and the protrusions for the plane mirror.

16. A gas laser device as claimed in claim 12, wherein the optical axis of the laser light directed from the chamber device to the convex mirror and the optical axis of the laser light directed from the concave mirror to the output coupling mirror are aligned on the same straight line.

17. A gas laser apparatus as described in claim 1, wherein the beam expander further includes a first plane mirror including a reflective surface that reflects the light reflected by the convex mirror and a plurality of side surfaces, only one of which is fixed to the holding portion with an adhesive, and a second plane mirror including a reflective surface that reflects the light reflected by the first plane mirror toward the concave mirror and a plurality of side surfaces, only one of which is fixed to the holding portion with an adhesive.

18. A gas laser apparatus as described in claim 17, wherein the holding portion includes a convex mirror protrusion protruding from the surface to which the one side of the convex mirror is fixed with an adhesive and positioned around the convex mirror, a concave mirror protrusion protruding from the surface to which the one side of the concave mirror is fixed with an adhesive and positioned around the concave mirror, a first plane mirror protrusion protruding from the surface to which the one side of the first plane mirror is fixed with an adhesive and positioned around the first plane mirror, and a second plane mirror protrusion protruding from the surface to which the one side of the second plane mirror is fixed with an adhesive and positioned around the second plane mirror.

19. A gas laser device as claimed in claim 1, wherein the chamber device transmits laser light output from a laser oscillator and amplifies the laser light.

20. A chamber device including a pair of discharge electrodes facing each other in an internal space in which laser gas is sealed, and emitting light generated from the laser gas when a voltage is applied between the pair of discharge electrodes; a resonator for resonating the light emitted from the chamber device between both sides of the chamber device; and a beam expander, wherein the resonator is disposed on one side of the chamber device and includes an output coupling mirror for transmitting a portion of the light emitted from the chamber device and reflecting another portion of the light emitted from the chamber device back to the chamber device, and the beam expander is disposed between the chamber device and the output coupling mirror and includes a holding section; and a convex mirror including a reflective surface that reflects the light emitted from the chamber device so as to expand the beam width of the light, and multiple side surfaces, only one of the multiple side surfaces being fixed to the holding section with an adhesive; a gas laser apparatus including a reflective surface that reflects the light reflected by the convex mirror toward the output coupling mirror so as to collimate the light so that the expanded beam width of the light reflected by the convex mirror becomes constant, and a concave mirror that includes a plurality of side surfaces, only one of which is fixed to the holding portion with an adhesive; generating a pulsed laser light by a gas laser apparatus including: a reflective surface that reflects the light reflected by the convex mirror toward the output coupling mirror so as to collimate the light so that the expanded beam width of the light becomes constant; outputting the pulsed laser light to an exposure apparatus; and exposing the pulsed laser light onto a photosensitive substrate in the exposure apparatus to manufacture an electronic device.

Images