Gas laser device and method of manufacturing an electronic device

Abstract

This invention provides a method for manufacturing a gas laser device and electronic components. The gas laser device includes: a cavity device that emits pulsed laser light; and a pulse stretcher comprising multiple annular optical paths for extending the pulse width of the pulsed laser light, the annular optical paths comprising: a beam splitter to which the pulsed laser light is incident; and multiple surrounding mirrors that sequentially reflect portions of the pulsed laser light incident on the beam splitter and return it to the beam splitter in a manner that overlaps with another portion of the pulsed laser light. The pulse stretcher includes a unit that can separate and detach two or more beam splitters from one or more surrounding mirrors.

Description

Technical Field

[0001] This disclosure relates to methods for manufacturing gas laser devices and electronic components. Background Technology

[0002] In recent years, with the miniaturization and high integration of semiconductor integrated circuits, there has been a demand for higher resolution in semiconductor exposure equipment. Therefore, the use of shorter wavelengths of light emitted from exposure light sources has been developed. For example, as gas laser devices for exposure, there are KrF excimer lasers that use lasers with an output wavelength of approximately 248 nm, and ArF excimer lasers that use lasers with an output wavelength of approximately 193 nm.

[0003] Furthermore, excimer lasers have pulse widths of approximately tens of ns and relatively short wavelengths of 248 nm and 193 nm, respectively. Therefore, they are sometimes used for the direct processing of polymer materials, glass materials, and the like. The chemical bonds in polymer materials can be broken by excimer lasers, which have photon energies higher than bond energies. Therefore, it is known that excimer lasers can be used for non-thermal processing of polymer materials, resulting in well-defined shapes. Moreover, it is known that glass, ceramics, and other materials have high absorption rates for excimer lasers; therefore, even materials that are difficult to process using visible light and infrared lasers can be processed using excimer lasers.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2024 / 047867

[0007] Patent Document 2: Japanese Patent Application Publication No. 2000-088705

[0008] Patent Document 3: Japanese Patent Application Publication No. 2004-354408 Summary of the Invention

[0009] One aspect of the gas laser device disclosed herein may also include: a cavity device that emits pulsed laser light; and a pulse stretcher comprising multiple annular optical paths for extending the pulse width of the pulsed laser light, the annular optical paths comprising: a beam splitter to which the pulsed laser light is incident; and multiple surrounding mirrors that sequentially reflect portions of the pulsed laser light incident on the beam splitter and return it to the beam splitter in a manner that overlaps with another portion of the pulsed laser light, the pulse stretcher comprising a unit that can separate and detach two or more beam splitters from one or more surrounding mirrors.

[0010] One method of manufacturing an electronic device according to this disclosure may also include the following steps: outputting a pulsed laser generated by a gas laser device to an exposure apparatus, and exposing the pulsed laser output to the exposure apparatus on a photosensitive substrate within the exposure apparatus to manufacture the electronic device. The gas laser device has: a cavity device that outputs the pulsed laser; and a pulse stretcher that includes multiple annular optical paths for extending the pulse width of the pulsed laser. The annular optical paths include: a beam splitter to which the pulsed laser is incident; and multiple surrounding mirrors that sequentially reflect a portion of the pulsed laser incident on the beam splitter and return it to the beam splitter in a manner that overlaps with another portion of the pulsed laser. The pulse stretcher includes a unit that can separate and detach two or more beam splitters from one or more surrounding mirrors. Attached Figure Description

[0011] Hereinafter, several embodiments of the present disclosure will be described by way of example only, with reference to the accompanying drawings.

[0012] Figure 1 This is a schematic diagram illustrating an example of the overall general structure of an electronic device manufacturing apparatus used in the exposure process of an electronic device.

[0013] Figure 2 This is a schematic diagram showing the overall general structure of a comparative example gas laser device.

[0014] Figure 3 This is a schematic diagram of the general structure of the first light guide unit, the second light guide unit, and the pulse stretcher of the comparative example, viewed from an obliquely upward angle.

[0015] Figure 4 This is a schematic diagram showing a schematic structural example of the shell of the comparative example.

[0016] Figure 5 This is a schematic diagram of a general structural example of the first light guide unit, the second light guide unit, and the pulse stretcher in Embodiment 1, viewed from an obliquely upward perspective.

[0017] Figure 6 This is a schematic diagram showing a schematic structural example of the unit in Embodiment 1.

[0018] Figure 7 This is a schematic diagram showing the unit and housing of Embodiment 1.

[0019] Figure 8 This is a schematic diagram of the general structure of the first light guide unit, the second light guide unit, and the pulse stretcher in a modified example of Embodiment 1, viewed from an obliquely upward perspective.

[0020] Figure 9 Is with Figure 7 Similarly, schematic diagrams of the unit and housing of a variation of Embodiment 1 are shown.

[0021] Figure 10 This is a schematic diagram of a general structural example of the first light guide unit, the second light guide unit, and the pulse stretcher in Embodiment 2, viewed from an obliquely upward perspective.

[0022] Figure 11 This is a schematic diagram of a general structural example of the first light guide unit, the second light guide unit, and the pulse stretcher in Embodiment 3, viewed from an obliquely upward perspective.

[0023] Figure 12 This is a magnified schematic diagram showing the portion of the ring optical path that includes the substrate and the beam splitter.

[0024] Figure 13 This is a schematic diagram of a general structural example of the first light guide unit, the second light guide unit, and the pulse stretcher in Embodiment 4, viewed from an obliquely upward perspective. Detailed Implementation

[0025] 1. Description of the electronic device manufacturing apparatus used in the exposure process of electronic devices

[0026] 2. Description of the comparative gas laser device

[0027] 2.1 Structure

[0028] 2.2 Actions

[0029] 2.3 Research Topic

[0030] 3. Description of the gas laser device in Embodiment 1

[0031] 3.1 Structure

[0032] 3.2 Maintenance methods for pulse stretchers

[0033] 3.3 Functions / Effects

[0034] 3.4 Explanation of Variations

[0035] 4. Description of the gas laser device in Embodiment 2

[0036] 4.1 Structure

[0037] 4.2 Function / Effect

[0038] 5. Description of the gas laser device in Embodiment 3

[0039] 5.1 Structure

[0040] 5.2 Function / Effect

[0041] 6. Description of the gas laser device in Embodiment 4

[0042] 6.1 Structure

[0043] 6.2 Function / Effect

[0044] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. The embodiments described below illustrate several examples of this disclosure and do not limit its scope. Furthermore, the structures and operations described in each embodiment are not necessarily all necessary for the structures and operations of this disclosure. Additionally, the same reference numerals are used to denote the same structural elements, and repeated descriptions are omitted.

[0045] 1. Description of the electronic device manufacturing apparatus used in the exposure process of electronic devices

[0046] Figure 1 This is a schematic diagram illustrating a general structural example of an electronic device manufacturing apparatus used in the exposure process of an electronic device. For example... Figure 1 As shown, the manufacturing apparatus used in the exposure process includes a gas laser device 100 and an exposure device 200. The exposure device 200 includes an illumination optics system 210 and a projection optics system 220. The illumination optics system 210 includes multiple mirrors 211, 212, and 213. The illumination optics system 210 illuminates the mask pattern on the mask stage RT using laser light incident from the gas laser device 100. The projection optics system 220 projects the laser light transmitted through the mask onto a workpiece (not shown) disposed on a workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure device 200 moves the mask stage RT and the workpiece stage WT synchronously and parallel, thereby exposing the workpiece to the laser light reflecting the mask pattern. Through this exposure process, a device pattern is transferred onto a semiconductor wafer, thereby enabling the manufacture of semiconductor devices as electronic devices.

[0047] 2. Description of the comparative gas laser device

[0048] 2.1 Structure

[0049] The gas laser apparatus of the comparative example will be described. Furthermore, the comparative examples disclosed herein are methods known only to the applicant and are not publicly known examples acknowledged by the applicant.

[0050] Figure 2This is a schematic diagram illustrating the overall general structure of a comparative example gas laser device 100. The gas laser device 100 is, for example, an ArF excimer laser device using a mixture of argon (Ar), fluorine (F2), and neon (Ne). This gas laser device 100 outputs laser light with a center wavelength of approximately 193 nm. Alternatively, the gas laser device 100 can also be a gas laser device other than an ArF excimer laser device, for example, a KrF excimer laser device using a mixture of krypton (Kr), F2, and Ne. In this case, the gas laser device 100 emits laser light with a center wavelength of approximately 248 nm. The mixture of Ar, F2, and Ne as the laser medium, and the mixture of Kr, F2, and Ne as the laser medium, are sometimes referred to as laser gases. Furthermore, in the mixtures used in the ArF excimer laser device and the KrF excimer laser device, helium (He) can be used instead of Ne.

[0051] The gas laser device 100 in this example includes a housing 110, and a laser oscillator 130 as the main oscillator, an optical transmission unit 141, an amplifier 160 as the power oscillator, a first light guide unit 150, a second light guide unit 155, a pulse stretcher 400, a detection unit 170, a display unit 180, a processor 190, and a gas module 700 disposed in the internal space of the housing 110 as the main structure.

[0052] The laser oscillator 130 includes a cavity device CH1, a charger 41, a pulse power module 43, a narrowband module 60, and an output coupling mirror 70 as its main structures.

[0053] exist Figure 2 The image shows the internal structure of the cavity device CH1 as viewed from a direction approximately perpendicular to the direction of laser travel. The cavity device CH1 has a housing 30, a pair of windows 31a and 31b, a pair of electrodes 32a and 32b, an insulating part 33, a feed passage part 34, and an electrode holder part 36 as its main structures.

[0054] Regarding the housing 30, the laser gas is supplied from the laser gas supply device 703 of the gas module 700 to the internal space of the housing 30 via piping, thus sealing the internal space with laser gas. The internal space is the space in which light is generated by the excitation of the laser medium in the laser gas. This light travels toward windows 31a and 31b.

[0055] Window 31a is disposed on the front wall surface of the housing 30 in the direction of laser travel from the gas laser device 100 to the exposure device 200, and window 31b is disposed on the rear wall surface of the housing 30 in the same direction of travel. Windows 31a and 31b are calcium fluoride substrates, and the inner and outer surfaces of windows 31a and 31b in the housing 30 are planar. Furthermore, windows 31a and 31b need only be able to allow laser transmission, and are not limited to calcium fluoride substrates.

[0056] Electrodes 32a and 32b are configured to face each other within the interior space of housing 30, with their length directions aligned with the direction of light propagation. This light is generated by applying a high voltage between electrodes 32a and 32b. The space between electrodes 32a and 32b within housing 30 is located between windows 31a and 31b. Electrodes 32a and 32b are discharge electrodes used to excite the laser medium via glow discharge. In this example, electrode 32a is the cathode, and electrode 32b is the anode.

[0057] Electrode 32a is supported by insulating portion 33. Insulating portion 33 blocks the opening formed in housing 30. Insulating portion 33 includes an insulator. Furthermore, a feedthrough portion 34 composed of conductive components is disposed in insulating portion 33. Feedthrough portion 34 applies the voltage supplied from pulse power module 43 to electrode 32a. Electrode 32b is supported by electrode holder portion 36 and is electrically connected to electrode holder portion 36.

[0058] Charger 41 is a DC power supply device that charges a capacitor (not shown) disposed inside pulse power module 43 with a specified voltage. Charger 41 is disposed outside housing 30 and connected to pulse power module 43. Pulse power module 43 includes a switch (not shown) controlled by processor 190. Pulse power module 43 is a voltage application circuit that boosts the voltage applied from charger 41 to generate a pulsed high voltage when the switch is switched from open to closed by the control, and applies this high voltage to electrodes 32a and 32b. When the high voltage is applied, a discharge occurs between electrodes 32a and 32b. The energy from this discharge excites the laser medium inside housing 30. When the excited laser gas transitions to the ground state, it emits light, which exits through windows 31a and 31b to the outside of housing 30. As described above, the pulsed high voltage is applied between electrodes 32a and 32b by pulse power module 43; therefore, this laser is a pulsed laser.

[0059] Windows 31a and 31b can also be tilted at a Brewster angle relative to the laser's direction of travel to suppress the reflection of P-polarized light from the laser. In this example, windows 31a and 31b are tilted relative to a direction perpendicular to the laser's direction of travel and the direction opposite to electrodes 32a and 32b. Therefore, the laser emitted from cavity device CH1 contains first linearly polarized light with a polarization direction perpendicular to the direction opposite to electrodes 32a and 32b, and linearly polarized light with a polarization direction different from that of the first linearly polarized light is reduced from the laser. That is, windows 31a and 31b also function as polarizers, which are tilted relative to the polarization direction of the first linearly polarized light and reduce linearly polarized light with a polarization direction different from that of the first linearly polarized light from the laser.

[0060] The narrowband module 60 includes a housing 65, and a prism 61, a grating 63, and a rotary table (not shown) disposed within the interior 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.

[0061] Prism 61 widens the beam width of light emitted from window 31b, allowing the light to enter the grating 63. Furthermore, prism 61 narrows the beam width of reflected light from the grating 63, causing the light to return via window 31b to the interior space of housing 30. Prism 61 is supported by a rotating stage and rotates via the stage. The rotation of prism 61 changes the angle of incidence of light relative to the grating 63. Therefore, by rotating prism 61, the wavelength of light returning from the grating 63 to housing 30 via prism 61 can be selected. Figure 2 The example shown is configured with one prism 61, but more than two prisms can also be configured.

[0062] The surface of the grating 63 is made of a highly reflective material, and multiple grooves are arranged on the surface at predetermined intervals. The grating 63 is a dispersive optical element. The cross-sectional shape of each groove is, for example, a right-angled triangle. Light incident from the prism 61 onto the grating 63 is reflected by these grooves and diffracted in a direction corresponding to the wavelength of the light. The grating 63 is configured in a Littlero configuration so that the angle of incidence of the light incident from the prism 61 onto the grating 63 coincides with the diffraction angle of the diffracted light of the desired wavelength. Thus, light of the desired wavelength returns to the housing 30 via the prism 61.

[0063] The output coupling mirror 70 faces the window 31a, allowing a portion of the laser emitted from the window 31a to pass through, while the remaining portion is reflected and returns through the window 31a to the interior space of the housing 30. The output coupling mirror 70 is fixed to a holder (not shown) and is disposed within the interior space of the housing 110.

[0064] A Fabry-Perot type resonator is constructed using a grating 63 and an output coupling mirror 70 disposed between the housing 30 and the resonator. The housing 30 is positioned in the optical path of the resonator. Therefore, the resonator causes optical resonance between the two sides of the cavity-separated device CH1.

[0065] The optical transmission unit 141 includes highly reflective mirrors 141b and 141c as its main structure. The highly reflective mirrors 141b and 141c are fixed to holders (not shown) at their respective tilt angles and are disposed within the interior space of the housing 110. The highly reflective mirrors 141b and 141c cause high reflection of the laser light. The highly reflective mirrors 141b and 141c are positioned in the optical path of the laser light from the output coupling mirror 70. The laser light is reflected by the highly reflective mirrors 141b and 141c and travels towards the rear mirror 371 of the amplifier 160. At least a portion of the laser light passes through the rear mirror 371.

[0066] Amplifier 160 amplifies the energy of the laser output from laser oscillator 130. The basic structure of amplifier 160 is substantially the same as that of laser oscillator 130. To distinguish the structural elements of amplifier 160 from those of laser oscillator 130, the cavity device, housing, pair of windows, pair of electrodes, insulation, feedthrough, electrode holder, charger, pulse power module, and output coupling mirror of amplifier 160 will be described as cavity device CH3, housing 330, pair of windows 331a and 331b, pair of electrodes 332a and 332b, insulation 333, feedthrough 334, electrode holder 336, charger 341, pulse power module 343, and output coupling mirror 370. Electrodes 332a and 332b generate discharges for amplifying the laser from laser oscillator 130. The direction in which electrodes 332a and 332b face each other is perpendicular to the polarization direction of the first linearly polarized light in the laser from laser oscillator 130.

[0067] Windows 331a and 331b can also be tilted relative to the polarization direction of the first linearly polarized light, so that the first linearly polarized light in the laser is incident as P-polarized light, and the incident angle θ of the laser becomes the Brewster angle. With windows 331a and 331b tilted in this way, the laser emitted from the cavity device CH3 contains the first linearly polarized light, and linearly polarized light with a polarization direction different from that of the first linearly polarized light is reduced from the laser. That is, similar to windows 31a and 31b, windows 331a and 331b also function as polarizers, which are tilted relative to the polarization direction of the first linearly polarized light, and reduce linearly polarized light with a polarization direction different from that of the first linearly polarized light from the laser. The shape of the laser emitted from windows 331a and 331b can also be a longer rectangle in the direction in which the pair of electrodes 332a and 332b face each other. Similar to pulse power module 43, pulse power module 343 is a voltage application circuit.

[0068] Furthermore, the main difference between amplifier 160 and laser oscillator 130 is that amplifier 160 does not have narrowband module 60, but has rear mirror 371.

[0069] The rear mirror 371 is positioned between the high-reflectivity mirror 141c and the window 331b, facing them respectively. The rear mirror 371 allows a portion of the laser light from the laser oscillator 130 to pass through into the space between the electrodes 332a and 332b, and allows a portion of the laser light amplified by the electrodes 332a and 332b to be reflected into the space between the electrodes 332a and 332b.

[0070] An output coupling mirror 370 is positioned between window 331a and high-reflectivity mirror 151, facing them respectively. The output coupling mirror 370 causes a portion of the laser light emitted after being amplified by electrodes 332a and 332b to be reflected towards the space between electrodes 332a and 332b, while allowing another portion of the laser light to pass through the high-reflectivity mirror 151. Therefore, a partially reflective film with a specified reflectivity is coated on the surface of the output coupling mirror 370 facing window 331a.

[0071] The output coupling mirror 370 can also be circular. The face of the output coupling mirror 370 facing the window 331a and the face opposite to it are planar. The output coupling mirror 370 has a similar structure to the output coupling mirror 70.

[0072] A resonator is constructed using a rear mirror 371 and an output coupling mirror 370, which are separated by a housing 330, to resonate the laser beam amplified by electrodes 332a and 332b. The housing 330 is positioned in the optical path of the resonator. Laser light emitted from window 331a of the housing 330 is incident on the output coupling mirror 370, and a portion is reflected by this mirror. The laser light reflected by the output coupling mirror 370 returns to the interior space of the housing 330 via window 331a and exits from window 331b. The laser light exiting from window 331b is reflected by the rear mirror 371 and returns to the interior space of the housing 330 via window 331b. Thus, the laser light emitted from the housing 330 travels back and forth between the rear mirror 371 and the output coupling mirror 370. The traveling laser light is amplified each time it passes through the discharge space between electrodes 332a and 332b. In other words, the resonator causes optical resonance between the two sides of the cavity-separated device CH3, and the output coupling mirror 370 is positioned on one side of the cavity-separated device CH3. A portion of the amplified laser beam passes through the output coupling mirror 370. The laser beam passing through the output coupling mirror 370 travels towards the high-reflectivity mirror 151. Thus, the laser beam traveling from the output coupling mirror 370 to the high-reflectivity mirror 151 is a pulsed laser.

[0073] Figure 3This is a schematic diagram of the general structure of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400, viewed from an obliquely upward perspective. The first light guide unit 150 includes high-reflectivity mirrors 151 and 152 as its main structure. Below, we will define the direction of propagation of the laser beam that exits from the window 331a of the cavity device CH3 and passes through the output coupling mirror 370 as the Z direction, the height direction of the gas laser device 100 as the V direction, and the direction orthogonal to both the V and Z directions as the H direction. In this example, the optical axis of the laser beam exiting from the window 331a and passing through the output coupling mirror 370 is approximately parallel to the horizontal direction. Furthermore, the V direction in this example is parallel to the direction of gravity.

[0074] High-reflectivity mirrors 151 and 152 are fixed to a holder (not shown) with their respective tilt angles adjusted to achieve high laser reflection. Figure 3 The outline of the laser is shown using dashed lines. High-reflectivity mirrors 151 and 152 are, for example, plane mirrors. High-reflectivity mirror 151 is positioned in the optical path of the laser from the output coupling mirror 370, causing the laser to reflect in the H direction. High-reflectivity mirror 152 is positioned in the optical path of the laser after reflection from high-reflectivity mirror 151, causing the laser to reflect in the V direction. The laser after reflection from high-reflectivity mirror 152 is incident on pulse stretcher 400.

[0075] The pulse stretcher 400 includes multiple optical elements to extend the pulse width of the laser incident from the first light guide unit 150 to the pulse stretcher 400, so that the laser with the extended pulse width is emitted toward the second light guide unit 155.

[0076] In this example, the pulse stretcher 400 has a light-guiding optical system 401 and four annular optical paths 410L, 420L, 430L, and 440L as its main structures, which are positioned on the V-direction side relative to the optical axis of the laser transmitted through the output coupling mirror 370.

[0077] The light-guiding optical system 401 in this example has two light-guiding mirrors 402 and 403 as optical elements as its main structure. The light-guiding mirrors 402 and 403 are fixed to a holder (not shown) with their respective tilt angles adjusted to achieve high laser reflection. The light-guiding mirrors 402 and 403 are, for example, plane mirrors. The light-guiding mirror 402 is positioned on the H-direction side of the optical axis of the laser transmitted through the output coupling mirror 370, and is arranged in the optical path of the laser reflected by the high-reflectivity mirror 152. The light-guiding mirror 402 reflects the laser reflected by the high-reflectivity mirror 152 in the -H direction. The light-guiding mirror 403 is arranged in the optical path of the laser reflected by the light-guiding mirror 402, and is positioned on the -H-direction side of the optical axis of the laser transmitted through the output coupling mirror 370. The light-guiding mirror 403 reflects the laser reflected by the light-guiding mirror 402 in the -V direction, and this laser is emitted from the pulse stretcher 400.

[0078] In this example, the annular optical path 410L consists of a beam splitter 410B as an optical element and four surrounding mirrors 411, 412, 413, and 414 as another optical element. The beam splitter 410B is positioned in the optical path of the laser in the light-guiding optical system 401, and is fixed to a holder (not shown) for the laser light that is reflected by the high-reflectivity mirror 152, incident on the pulse stretcher 400, and directed toward the light-guiding mirror 402. The beam splitter 410B splits the incident laser light into two parts, allowing one part to pass through the light-guiding mirror 402 so that it propagates in the optical path of the light-guiding optical system 401, while the other part is reflected toward the surrounding mirror 411.

[0079] The surrounding mirrors 411-414 are, for example, concave mirrors, supported by a cage (not shown). Surrounding mirrors 411 and 413 are positioned on the Z-direction side relative to light guide mirrors 402 and 403, and are arranged in the -H direction in the order of surrounding mirrors 411 and 413. Surrounding mirrors 412 and 414 are positioned on the -Z-direction side relative to light guide mirrors 402 and 403, and are arranged in the H direction in the order of surrounding mirrors 412 and 414. Surrounding mirrors 411 and 414, and surrounding mirrors 412 and 413, are respectively opposed to each other in a direction parallel to the Z-direction. Beam splitter 410B is located between surrounding mirrors 411 and 414.

[0080] The surrounding mirrors 411-414 cause the laser light reflected from the beam splitter 410B to return to the beam splitter 410B in the order of the surrounding mirrors 411, 412, 413, and 414. The laser light reflected from the surrounding mirror 414 enters the beam splitter 410B from a surface opposite to the incident surface of the laser light reflected from the high-reflectivity mirror 152. In this way, an annular optical path 410L is formed for the laser light returning to the beam splitter 410B from the beam splitter 410B via the surrounding mirrors 411-414, and the annular optical path 410L extends in the H and Z directions.

[0081] Beam splitter 410B causes a portion of the laser light reflected from the surrounding mirror 414 and returning to beam splitter 410B to be reflected towards guide mirror 402, while the other portion passes through the surrounding mirror 411. The transmitted laser light then propagates in the annular optical path 410L. In this way, the laser light is reflected four times in the annular optical path 410L and completes one revolution, thus completing more than one revolution in the annular optical path 410L.

[0082] The laser light that returns to the beam splitter 410B after completing one revolution in the annular optical path 410L, and is separated at the beam splitter 410B and directed toward the guide mirror 402, is delayed by a predetermined time compared to the laser light that did not travel toward the annular mirror 411, passes through the beam splitter 410B, and is directed toward the guide mirror 402. This delayed laser light traveling from the beam splitter 410B to the guide mirror 402 overlaps with a portion of the laser light that did not travel toward the annular mirror 411, passes through the beam splitter 410B, and is directed toward the guide mirror 402. That is, the laser light returning to the beam splitter 410B is separated into a portion that overlaps with a portion of the laser light separated at the beam splitter 410B, and a portion that is sequentially reflected by the annular mirrors 411-414. Each time the laser revolves once around the annular optical path 410L, the laser pulses overlap. Through this overlap, the laser pulse width is extended and propagates in the light guide mirror 402 in the light guide optical system 401.

[0083] In this example, the annular optical path 420L is composed of a beam splitter 420B as an optical element and eight surrounding mirrors 421-428 as another optical element. Additionally, in Figure 3For ease of observation, only four surrounding mirrors 421, 422, 427, and 428 are described, while the description of four surrounding mirrors 423 to 426 is omitted. Beam splitter 420B is positioned in the optical path of the laser in the light-guiding optical system 401, reflecting off the light-guiding mirror 402 and directed towards the light-guiding mirror 403, and is fixed to a holder (not shown). Surrounding mirrors 421 to 428 are, for example, concave mirrors, supported by holders (not shown). Surrounding mirrors 421, 423, 425, and 427 are positioned closer to the Z-direction side than light-guiding mirrors 402 and 403, while surrounding mirrors 422, 424, 426, and 428 are positioned closer to the -Z-direction side than light-guiding mirrors 402 and 403. Similar to the surrounding mirrors 411-414 of the ring optical path 410L, the surrounding mirrors 421-428 cause a portion of the laser light incident on the beam splitter 420B to be reflected sequentially by the surrounding mirrors 421-428, returning to the beam splitter 420B in a manner that overlaps with another portion of the laser light. Then, similar to the ring optical path 410L, laser overlap occurs, and the laser light with expanded pulse width propagates from the beam splitter 420B towards the guide mirror 403 in the light guiding optical system 401. The ring optical path 420L extends in both the H and Z directions. The optical path length of the ring optical path 420L is longer than that of the ring optical path 410L. Furthermore, the ring optical path 420L is located on the V-direction side more than the ring optical path 410L, and the ring optical paths 410L and 420L overlap each other in a direction parallel to the V direction.

[0084] In this example, the annular optical path 430L is composed of a beam splitter 430B as an optical element and eight surrounding mirrors 431-438 as another optical element. Additionally, in Figure 3For ease of observation, only four surrounding mirrors 431, 432, 437, and 438 are described, while the description of four surrounding mirrors 433 to 436 is omitted. Beam splitter 430B is positioned in the optical path of the laser in the light-guiding optical system 401, on the path of the laser from beam splitter 420B toward light-guiding mirror 403, and is fixed to a holder (not shown). Surrounding mirrors 431 to 438 are, for example, concave mirrors, supported by holders (not shown). Surrounding mirrors 431, 433, 435, and 437 are positioned on the Z-direction side relative to light-guiding mirrors 402 and 403, while surrounding mirrors 432, 434, 436, and 438 are positioned on the -Z-direction side relative to light-guiding mirrors 402 and 403. Similar to the surrounding mirrors 411-414 of the ring optical path 410L, the surrounding mirrors 431-438 cause a portion of the laser incident on the beam splitter 430B to be reflected sequentially by the surrounding mirrors 431-438, returning to the beam splitter 430B in a manner that overlaps with another portion of the laser. Then, similar to the ring optical path 410L, laser overlap occurs, and the laser with expanded pulse width propagates from the beam splitter 430B towards the guide mirror 403 in the light-guiding optical system 401. The ring optical path 430L extends in both the H and Z directions. The optical path length of the ring optical path 430L is longer than that of the ring optical path 410L, and approximately the same as that of the ring optical path 420L. Furthermore, the ring optical path 430L is located on the -H direction side more than the ring optical path 420L, and the ring optical paths 420L and 430L overlap each other in a direction parallel to the H direction.

[0085] In this example, the annular optical path 440L is composed of a beam splitter 440B as an optical element and 12 surrounding mirrors 441-452 as another optical element. Additionally, in Figure 3 For ease of observation, only four surrounding mirrors 441, 442, 451, and 452 are described, omitting the description of the eight surrounding mirrors 443 to 450. Beam splitter 440B is positioned in the optical path of the laser in the light-guiding optical system 401, on the optical path of the laser reflected in the -V direction by light-guiding mirror 403, and is fixed to a holder (not shown). Beam splitter 440B splits the incident laser into two parts, allowing one part to pass through so that it exits from pulse stretcher 400 and faces the second light-guiding unit 155, while the other part is reflected towards surrounding mirror 441.

[0086] The surrounding mirrors 441-452 are, for example, concave mirrors, supported by a cage (not shown). Surrounding mirrors 441, 443, 445, 447, 449, and 451 are positioned on the Z-direction side relative to the light-guiding mirrors 402 and 403, while surrounding mirrors 442, 444, 446, 448, 450, and 452 are positioned on the -Z-direction side relative to the light-guiding mirrors 402 and 403. Similar to the surrounding mirrors 411-414 of the ring optical path 410L, the surrounding mirrors 441-452 cause a portion of the laser incident on the beam splitter 440B to be reflected sequentially in the order of the surrounding mirrors 441-452, returning to the beam splitter 440B in a manner that overlaps with another portion of the laser. Then, similar to the ring optical path 410L, laser overlap occurs, and the laser with expanded pulse width propagates in the light-guiding optical system 401 towards the second light-guiding unit 155. The annular optical path 440L extends in both the H and Z directions. The optical path length of annular optical path 440L is longer than that of annular optical paths 410L, 420L, and 430L. Annular optical path 440L is located closer to the -V direction than annular optical path 430L, and closer to the -H direction than annular optical path 410L. Annular optical paths 430L and 440L overlap in the direction parallel to the V direction, and annular optical paths 410L and 440L overlap in the direction parallel to the H direction.

[0087] Thus, the light guiding optical system 401 sequentially directs the laser beam into the beam splitters 410B to 440B of the annular optical paths 410L to 440L. The optical path formed by the light guiding optical system 401 is a non-annular optical path. Then, the pulse width of the laser is sequentially expanded through the annular optical paths 410L to 440L. That is, the annular optical paths 410L, 420L, 430L, and 440L are arranged in this order from the upstream side to the downstream side in the direction of laser travel. Then, the laser with the expanded pulse width exits from the pulse stretcher 400 and travels towards the second light guiding unit 155.

[0088] The second light guiding unit 155 in this example includes high-reflectivity mirrors 156 and 157 as its main structure. High-reflectivity mirrors 156 and 157 are fixed to a holder (not shown) with their respective tilt angles adjusted to achieve high laser reflection. High-reflectivity mirrors 156 and 157 are, for example, plane mirrors. High-reflectivity mirror 156 is positioned in the optical path of the laser emitted from the pulse stretcher 400, located on the -H direction side relative to the optical axis of the laser transmitted through the output coupling mirror 370. High-reflectivity mirror 156 reflects the laser emitted from the pulse stretcher 400 in the H direction. High-reflectivity mirror 157 is positioned in the optical path of the laser reflected by high-reflectivity mirror 156, and high-reflectivity mirrors 157 and 151 are arranged in the V direction. High-reflectivity mirror 157 reflects the laser reflected by high-reflectivity mirror 156 in the Z direction. The optical axis of the laser traveling from high-reflectivity mirror 157 to the detection unit 170 may also be non-parallel to the optical axis of the laser transmitted through the output coupling mirror 370.

[0089] The detection unit 170 includes a beam splitter 171 and an optical sensor 172 as its main structures.

[0090] Beam splitter 171 is positioned in the optical path of the laser emitted from the second light guide unit 155. Beam splitter 171 allows the laser emitted from the second light guide unit 155 to pass through the emission window 173 with high transmittance, and also causes a portion of the laser to be reflected toward the light-receiving surface of the photosensor 172.

[0091] Optical sensor 172 measures the pulse energy of laser light incident on its light-receiving surface. Optical sensor 172 is electrically connected to processor 190 and outputs a signal representing the measured pulse energy to processor 190. Processor 190 controls the voltage applied to electrodes 32a and 32b of amplifier 160 based on this signal.

[0092] An exit window 173 is disposed on the wall of the housing 110. Light transmitted through the beam splitter 171 exits from the exit window 173 toward the exposure device 200 outside the housing 110. The laser is, for example, a pulsed laser with a center wavelength of 193.4 nm.

[0093] The display unit 180 is a monitor that displays the status of the control performed by the processor 190 based on signals from the processor 190. The display unit 180 may also be disposed outside the housing 110.

[0094] The processor 190 of this disclosure is a processing device including a storage device storing a control program and a CPU (Central Processing Unit) that executes the control program. The processor 190 is specifically configured or programmed to perform the various processes included in this disclosure. Furthermore, the processor 190 controls the gas laser device 100 as a whole. Additionally, the processor 190 is electrically connected to an exposure processor (not shown) of the exposure device 200, and transmits and receives various signals with and from the exposure processor.

[0095] The gas module 700 includes a laser gas exhaust device 701 and a laser gas supply device 703. The laser gas exhaust device 701 and the laser gas supply device 703 are electrically connected to the processor 190 via signal lines (not shown). The laser gas exhaust device 701 includes an exhaust pump (not shown), which, according to a control signal from the processor 190, exhausts laser gas from the internal spaces of the housings 30 and 330 through piping. The laser gas supply device 703, according to a control signal from the processor 190, supplies laser gas through piping to the internal spaces of the housings 30 and 330; this laser gas originates from a laser gas supply source (not shown) located outside the housing 110.

[0096] Figure 4 This is a schematic diagram showing a schematic structural example of the housing 110 of the comparative example. (See attached diagram.) Figure 4 As shown, the housing 110 in this example has a first main body 111, a second main body 112, and a maintenance panel 116 as its main structures. The first main body 111 is a box-shaped component with internal space, which houses various devices such as the laser oscillator 130 and amplifier 160. In this example, the first main body 111 is a cuboid shape that is longer in the Z direction, and the first main body 111 includes four side walls, a lower wall, and a top wall.

[0097] The second main body 112 is a box-shaped component with an internal space, in which the pulse stretcher 400 is housed. In this example, the second main body 112 is a rectangular parallelepiped that is longer in the Z direction and is disposed on the upper wall of the first main body 111. The second main body 112 includes a rectangular lower wall 113 that is longer in the Z direction, four quadrilateral side walls 114 that are connected to the four sides of the lower wall 113, and a rectangular upper wall 115 that is opposite to the lower wall 113 and connected to each of the side walls 114. Two side walls 114 are opposite each other in a direction parallel to the Z direction and are parallel to the H and V directions. The other two side walls 114 are opposite each other in a direction parallel to the H direction and are parallel to the Z and V directions. An opening 114h is formed in one of the two sidewalls 114 facing each other in a direction parallel to the H direction, located on the H-direction side, through which the pulse stretcher 400 housed in the internal space can be accessed. The opening 114h is rectangular in shape, longer in the Z-direction, and its opening direction is horizontal in the H direction.

[0098] The maintenance panel 116 is a plate-shaped component that blocks the opening 114h. The maintenance panel 116 is detachably mounted to the second main body 112. Figure 4 The image shows the maintenance panel 116 removed from the second main body 112. Furthermore, the opening 114h is only required to allow the pulse stretcher 400 to enter and exit; its position, shape, etc., are not restricted.

[0099] As described above, the laser light reflected in the V direction by the high-reflectivity mirror 152 is incident on the pulse stretcher 400, and the laser light reflected in the -V direction by the light guide mirror 403 exits from the pulse stretcher 400. Therefore, a through-hole (not shown) is provided on the upper wall of the first main body 111 and the lower wall 113 of the second main body 112 for the laser light reflected in the V direction by the high-reflectivity mirror 152 to pass through, and another through-hole (not shown) for the laser light reflected in the -V direction by the light guide mirror 403 to pass through.

[0100] 2.2 Actions

[0101] Next, the operation of the comparative example gas laser device 100 will be explained.

[0102] Before the gas laser device 100 emits a laser, laser gas is supplied from the laser gas supply device 703 to the internal space of the housings 30 and 330.

[0103] When the gas laser device 100 emits laser light, the processor 190 receives a signal representing the target energy Et and a light emission trigger signal from the exposure processor. The target energy Et is the target value of the laser energy used in the exposure process. The processor 190 sets a predetermined charging voltage to the charger 41 so that the energy E becomes the target energy Et, and synchronously switches on the pulse power module 43 with the light emission trigger signal. As a result, the pulse power module 43 uses the electrical energy held by the charger 41 to generate a pulsed high voltage, which is applied between the electrodes 32a and 32b. When the high voltage is applied, a discharge occurs between the electrodes 32a and 32b, and the laser medium contained in the laser gas between the electrodes 32a and 32b becomes excited and emits light when the laser medium returns to the ground state. The emitted light resonates between the grating 63 and the output coupling mirror 70, and is amplified whenever it passes through the discharge space in the internal space of the housing 30, generating laser oscillation. The laser contains first-line polarized light. When it passes through windows 31a and 31b, the linearly polarized light with a polarization direction different from that of the first-line polarized light is reduced from the laser. A portion of the laser passes through the output coupling mirror 70, is reflected by the high-reflectivity mirrors 141b and 141c, and then passes through the rear mirror 371 and window 331b, traveling into the housing 330.

[0104] The processor 190 switches on the pulse power module 343 to cause a discharge between electrodes 332a and 332b as the laser from the laser oscillator 130 travels into the discharge space within the housing 330. That is, the processor 190 controls the pulse power module 343 to apply a high voltage to electrodes 332a and 332b after a predetermined delay relative to the timing of switching on the pulse power module 43.

[0105] Therefore, the laser incident on amplifier 160 is amplified within amplifier 160. Furthermore, the laser traveling into the interior space of housing 330, as described above, travels through windows 331a and 331b towards rear mirror 371 and output coupling mirror 370. Thus, the laser of a predetermined wavelength travels back and forth between rear mirror 371 and output coupling mirror 370. The laser contains first linearly polarized light; when passing through windows 331a and 331b, linearly polarized light with a polarization direction different from that of the first linearly polarized light is reduced from the laser. Furthermore, the laser is amplified each time it passes through the discharge space inside housing 330, and a portion of the laser becomes amplified laser light.

[0106] The amplified laser from amplifier 160 travels through output coupling mirror 370 toward high-reflectivity mirror 151. The laser is reflected in high-reflectivity mirror 151 toward high-reflectivity mirror 152. The laser, after being reflected in high-reflectivity mirror 151, is reflected in the V direction by high-reflectivity mirror 152 and enters pulse stretcher 400.

[0107] The laser incident on the pulse stretcher 400 is reflected in the -H direction by the light guide mirror 402 and travels to the light guide mirror 403. The laser is then reflected in the -V direction by the light guide mirror 403 and exits the pulse stretcher 400. Furthermore, in the pulse stretcher 400, the pulse width of the laser propagating through the sequential reflections of the light guide mirrors 402 and 403 in the light guide optical system 401 is expanded by the respective annular optical paths 410L to 440L. The laser with the expanded pulse width then exits the pulse stretcher 400 and travels towards the high-reflectivity mirror 156. The laser is reflected by the high-reflectivity mirror 156 towards the high-reflectivity mirror 157. The laser reflected by the high-reflectivity mirror 156 is then reflected in the Z direction by the high-reflectivity mirror 157 and travels towards the beam splitter 171.

[0108] A portion of the laser beam traveling toward the beam splitter 171 passes through the beam splitter 171 and the exit window 173 and travels toward the exposure device 200, while another portion is reflected by the beam splitter 171 and travels toward the photosensitive sensor 172.

[0109] The optical sensor 172 measures the energy E of the received laser. The optical sensor 172 outputs a signal representing the measured energy E to the processor 190. The processor 190 performs feedback control on the charging voltage of the chargers 41 and 341 to ensure that the difference ΔE between the energy E and the target energy Et is within an acceptable range.

[0110] 2.3 Research Topic

[0111] In the annular optical path 410L to 440L of the pulse stretcher 400, beam splitters 410B to 440B repeatedly transmit and reflect laser light. Therefore, beam splitters 410B to 440B are more prone to degradation and require more frequent replacement compared to the surrounding mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452. Thus, there is a requirement to facilitate the replacement of the frequently replaced beam splitters 410B to 440B, thereby simplifying maintenance.

[0112] Therefore, in the following embodiments, a gas laser device that can be easily maintained is illustrated.

[0113] 3. Description of the gas laser device in Embodiment 1

[0114] Next, the gas laser device 100 of Embodiment 1 will be described. Furthermore, structures identical to those described above will be labeled with the same reference numerals, and repeated descriptions will be omitted unless specifically stated otherwise.

[0115] 3.1 Structure

[0116] The pulse stretcher 400 of this embodiment differs from the pulse stretcher 400 of the comparative example mainly in that it is configured as a unit that can separate and detach two or more beam splitters from one or more mirrors.

[0117] Figure 5 This is a schematic diagram showing a schematic example of the structure of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 in this embodiment, viewed from an obliquely upward position. Figure 6 This is a schematic diagram illustrating a schematic structural example of unit 10U in this embodiment. Figure 5 , Figure 6 As shown, in this embodiment, the pulse stretcher 400 includes one unit 10U, which has all beam splitters 410B to 440B, all light guide mirrors 402 and 403, and a frame 11U as its main structure. Furthermore, the unit 10U does not include the surrounding mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452 that constitute the ring optical paths 410L to 440L. Additionally, in Figure 5 The description of frame 11U is omitted.

[0118] Frame 11U is a component that supports beam splitters 410B to 440B and light guide lenses 402 and 403. In this embodiment, frame 11U is composed of four support plates 12U to 15U. Support plate 12U is a plate-shaped component extending in a direction parallel to the Z-direction. Support plate 13U is a plate-shaped component extending in the V-direction from the Z-direction side end of support plate 12U. Support plate 14U is a plate-shaped component extending in the V-direction from the -Z-direction side end of support plate 12U. Support plate 15U is a plate-shaped component located closer to support plate 12U than the V-direction side end of support plates 13U and 14U, opposite to support plate 12U, and connected to support plates 13U and 14U.

[0119] Beam splitter 410B is fixed to holder 16Ua with its tilt angle adjusted. Holder 16Ua is fixed in the support plate 14U at a position between support plates 12U and 15U. Beam splitters 420B and 430B are fixed to holders 16Ub and 16Uc with their tilt angle adjusted. Holders 16Ub and 16Uc are fixed to the side of support plate 15U opposite to the side of support plate 12U. Beam splitter 440B is fixed to holder 16Ud with its tilt angle adjusted. Holder 16Ud is fixed to the support plate 13U at a position between support plates 12U and 15U. Light guide mirror 402 is fixed to holder 17Ua with its tilt angle adjusted. Holder 17Ua is fixed to the support plate 14U at a position on the V-direction side relative to support plate 15U. The light guide mirror 403 is fixed to the holder 17Ub in a tilted state, and the holder 17Ub is fixed to the support plate 13U at a position on the V-direction side relative to the support plate 15U. Through holes 11Uh are formed in the support plates 12U and 15U to allow laser light from the high-reflectivity mirror 152 toward the light guide mirror 402 and laser light from the light guide mirror 403 toward the high-reflectivity mirror 156 to pass through, respectively.

[0120] Thus, the beam splitters 410B to 440B and the light guide lenses 402 and 403 are supported by the frame 11U. Alternatively, the frame 11U can support the beam splitters 410B to 440B and the light guide lenses 402 and 403, and is not limited thereto.

[0121] Figure 7 This is a schematic diagram showing the unit 10U and the housing 110 of this embodiment. Figure 7 In the diagram, the first main body portion 111 and the second main body portion 112 of the housing 110 are shown using dashed lines, while the description of the maintenance panel 116 is omitted. Figure 7 As shown, the second main body 112 has two moving mechanisms 117a and 117b. The unit 10U is held by the moving mechanisms 117a and 117b. The moving mechanisms 117a and 117b enable the unit 10U to move in a manner that allows it to enter and exit through the opening 114h. The moving mechanisms 117a and 117b are, for example, constructed of a track extending in a direction parallel to the H direction, and the moving direction of the held unit 10U is parallel to the H direction, which is horizontal. The unit 10U held by the moving mechanisms 117a and 117b is positioned in a direction parallel to the H direction using a positioning mechanism (not shown) composed of pins, V-grooves, etc., and is fixed using a fixing mechanism (not shown) such as bolts. The opening 114h can be any size and shape that allows the unit 10U to enter and exit, or it can be larger than... Figure 4 The illustrated opening is small. Correspondingly, the maintenance panel 116 can also be smaller. Figure 4In the case of small cases. Alternatively, the maintenance panel 116 may be provided with an opening of an area and shape that allows the unit 10U to enter and exit, or a small maintenance panel that can close the opening may be configured.

[0122] 3.2 Maintenance methods for pulse stretchers

[0123] Next, the maintenance method of the pulse stretcher 400 in Embodiment 1, namely the maintenance method of the beam splitters 410B to 440B, will be described.

[0124] In this embodiment, the timing for maintaining beam splitters 410B to 440B is predetermined. This timing is determined, for example, by the number of pulsed laser pulses emitted from the gas laser device 100. The processor 190 counts the number of pulses, and when the predetermined number of pulses is reached, the display unit 180 displays a maintenance indicator. When this indicator is displayed, the operator performs maintenance on beam splitters 410B to 440B.

[0125] In addition, the timing of maintenance of beam splitters 410B to 440B can also be determined by factors other than the number of emission cycles, such as the operating time of the gas laser device 100.

[0126] The operator stops the operation of the gas laser device 100 and removes the maintenance panel 116 from the second main body 112. Next, the fixing mechanism of the fixing unit 10U is released, and the unit 10U is removed from the second main body 112 via the moving mechanisms 117a and 117b through the opening 114h. In this way, the beam splitters 410B to 440B are separated from the surrounding mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452 and removed. Then, the beam splitters 410B to 440B and the light guide mirrors 402 and 403 of the unit 10U are replaced. Alternatively, only the beam splitters 410B to 440B may be replaced, or the removed unit 10U may be replaced with a new unit 10U. Next, the unit 10U is housed in the storage space of the second main body 112 via the moving mechanisms 117a and 117b through the opening 114h, positioned by the positioning mechanism, and fixed by the fixing mechanism. Then, after the maintenance panel 116 is installed on the second main body 112 and the opening 114h is blocked, the gas laser device 100 is operated.

[0127] 3.3 Functions / Effects

[0128] As described above, beam splitters 410B to 440B are more prone to degradation than the surrounding mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452, and tend to require frequent replacement. The pulse stretcher 400 of this embodiment includes a unit 10U that allows for the separation and detachment of the four beam splitters 410B to 440B from the surrounding mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452. Therefore, compared to removing the beam splitters 410B to 440B and the surrounding mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452, the four beam splitters 410B to 440B, which tend to require frequent replacement, can be easily removed. Therefore, the gas laser device 100 according to this embodiment can easily replace the four beam splitters 410B to 440B, and can be easily maintained.

[0129] In the pulse stretcher 400 of this embodiment, unit 10U includes all beam splitters 410B to 440B. Therefore, all beam splitters 410B to 440B can be easily replaced simultaneously.

[0130] The pulse stretcher 400 of this embodiment also includes a light-guiding optical system 401, which comprises two light-guiding mirrors 402 and 403, allowing the pulsed laser to be sequentially incident on the beam splitters 410B to 440B of the four annular optical paths 410L to 440L. Therefore, compared with the case without the light-guiding optical system 401, the degree of freedom in the configuration of the four annular optical paths 410L to 440L can be increased.

[0131] In the pulse stretcher 400 of this embodiment, unit 10U includes all the light guide mirrors 402 and 403. Therefore, maintenance of beam splitters 410B to 440B and maintenance of the light guide optical system 401 can be performed simultaneously. Alternatively, unit 10U may not include at least one of the light guide mirrors 402 and 403.

[0132] The gas laser device 100 of this embodiment also includes a housing 110, which includes: a second main body 112 that houses the pulse stretcher 400 and has an opening 114h for the unit 10U to enter and exit; and moving mechanisms 117a and 117b that allow the unit 10U to move through the opening 114h. Therefore, the gas laser device 100 according to this embodiment allows the unit 10U to enter and exit easily. Alternatively, the housing 110 may not have the moving mechanisms 117a and 117b.

[0133] In the gas laser device 100 of this embodiment, the movement direction of the unit 10U implemented by the moving mechanisms 117a and 117b is horizontal. Therefore, when the unit 10U is moved in and out, it is possible to suppress the unit 10U from moving due to its own weight rather than intentionally. In addition, the movement direction of the unit 10U implemented by the moving mechanisms 117a and 117b may also be non-parallel to the horizontal direction.

[0134] In the gas laser device 100 of this embodiment, the housing 110 further includes a maintenance panel 116, which blocks the opening 114h and is detachably mounted to the second main body 112. Therefore, dust and other contaminants can be prevented from easily entering the storage space of the second main body 112. For example, even without a housing for storing the pulse stretcher 400, the influence of dust and other contaminants on the pulsed laser can be reduced.

[0135] 3.4 Explanation of Variations

[0136] Next, a modified example of the gas laser device 100 of Embodiment 1 will be described. Figure 8 This is a schematic diagram of the general structure of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 in this modified example, viewed from an obliquely upward position. Figure 9 Is with Figure 7 Similarly, schematic diagrams of the unit and housing 110 of this modified example are shown. Figure 8 , Figure 9 As shown, the main difference between the pulse stretcher 400 of this modified example and the pulse stretcher 400 of Embodiment 1 is that the unit 10U is divided into two units 10Ua and 10Ub.

[0137] Unit 10Ua has beam splitters 410B and 420B for the annular optical paths 410L and 420L, a light guide mirror 402, and a frame (not shown) as its main structures. The beam splitters 410B and 420B and the light guide mirror 402 are located on the H-direction side of the optical axis of the laser transmitted through the output coupling mirror 370. The beam splitters 410B and 420B and the light guide mirror 402 are supported by the frame in a state where their respective tilt angles are adjusted.

[0138] Unit 10Ub has beam splitters 430B and 440B for the annular optical paths 430L and 440L, a light guide mirror 403, and a frame (not shown) as its main structures. The beam splitters 430B and 440B and the light guide mirror 403 are located on the -H direction side of the optical axis of the laser transmitted through the output coupling mirror 370. The beam splitters 430B and 440B and the light guide mirror 403 are supported by the frame in a state where their respective tilt angles are adjusted.

[0139] In this modified example, unit 10Ua is located closer to the opening 114h than unit 10Ub, and units 10Ua and 10Ub overlap in a direction parallel to the opening direction of the opening 114h. Furthermore, in the laser's travel direction, the annular optical paths 410L and 420L are positioned upstream of the annular optical paths 430L and 440L. Therefore, the beam splitters 410B and 420B of unit 10Ua are positioned upstream of the beam splitters 430B and 440B of unit 10Ub in the laser's travel direction.

[0140] Similar to unit 10U in Embodiment 1, units 10Ua and 10Ub are held by moving mechanisms 117a and 117b, which enable units 10Ua and 10Ub to move in a manner that allows them to enter and exit through opening 114h. Furthermore, units 10Ua and 10Ub are positioned in a direction parallel to the H direction using a positioning mechanism (not shown) consisting of pins, V-grooves, etc., and are fixed using a fixing mechanism (not shown) such as bolts.

[0141] Next, the maintenance method for the pulse stretcher 400 in this modified example will be described. In this modified example, the timing for maintenance of each unit 10Ua and 10Ub is predetermined, and this timing is determined by the number of pulse laser emissions. The frequency of maintenance for unit 10Ua is higher than the frequency of maintenance for unit 10Ub.

[0142] In this modified example, the number of emissions during maintenance of unit 10Ub is twice the number of emissions during maintenance of unit 10Ua. Therefore, maintenance of unit 10Ua is performed simultaneously with maintenance of unit 10Ub. The frequency of maintenance of unit 10Ua is not limited, as long as it is higher than the frequency of maintenance of unit 10Ub. The timing of maintenance of units 10Ua and 10Ub can also be set so that maintenance of unit 10Ua is not performed when maintenance of unit 10Ub is performed. Furthermore, the timing of maintenance can be determined by factors other than the number of emissions, for example, it can be determined based on the operating time of the gas laser device 100.

[0143] First, the maintenance of unit 10Ua will be explained. Similar to the maintenance of unit 10U in Embodiment 1, the operator stops the operation of the gas laser device 100 and removes the maintenance panel 116 from the second main body 112. Next, unit 10Ua is removed from the second main body 112. In this way, beam splitters 410B and 420B are separated from the surrounding mirrors 411-414, 421-428, 431-438, and 441-452 and removed. Beam splitters 410B and 420B and the light guide mirror 402 of unit 10Ua are replaced. Alternatively, only beam splitters 410B and 420B may be replaced, or the removed unit 10Ua may be replaced with a new unit 10Ua. Next, unit 10Ua is stored in the storage space of the second main body 112, positioned using a positioning mechanism, and fixed using a fixing mechanism. After blocking the opening 114h using the maintenance panel 116, the gas laser device 100 is operated.

[0144] Next, the maintenance of unit 10Ub will be explained. Similar to the maintenance of unit 10Ua, the operator stops the operation of the gas laser device 100 and removes the maintenance panel 116 from the second main body 112. Then, as described above, unit 10Ua is removed from the second main body 112. Next, the fixing mechanism securing unit 10Ub is released, and unit 10Ub is removed from the second main body 112. In this way, beam splitters 430B and 440B are separated from and removed from the surrounding mirrors 411-414, 421-428, 431-438, and 441-452. Beam splitters 430B and 440B and the light guide mirror 403 of unit 10Ub are replaced. Alternatively, only beam splitters 430B and 440B may be replaced, or the removed unit 10Ub may be replaced with a new unit 10Ub. Then, the unit 10Ub is stored in the storage space of the second main body 112, positioned using a positioning mechanism, and fixed using a fixing mechanism.

[0145] In this modified example, the beam splitters 410B and 420B and the light guide mirror 402 of unit 10Ua are also replaced, and unit 10Ua is stored in the storage space of the second main body 112 and fixed. Alternatively, when unit 10Ua is not maintained during the maintenance of unit 10Ub, the removed unit 10Ua is directly stored in the storage space of the second main body 112 and fixed.

[0146] After housing and fixing units 10Ua and 10Ub in the storage space of the second main body 112, the maintenance panel 116 is installed on the second main body 112 and the opening 114h is blocked, so that the gas laser device 100 can be operated.

[0147] The pulse stretcher 400 of this embodiment includes units 10Ua and 10Ub. Unit 10Ua includes beam splitters 410B and 420B, which are detachable and removable from the surrounding mirrors 411-414, 421-428, 431-438, and 441-452. Unit 10Ub includes beam splitters 430B and 440B, which are detachable and removable from the surrounding mirrors 411-414, 421-428, 431-438, and 441-452. Therefore, beam splitters 410B, 420B, and 430B, 440B can be easily replaced at different times.

[0148] In the laser's travel direction, optical elements positioned upstream tend to deteriorate more easily. This is because the pulse width of the upstream laser is shorter and the intensity of the upstream laser is higher than that of the downstream laser. In the gas laser device 100 of this modified example, unit 10Ua is located closer to the opening 114h than unit 10Ub. The beam splitters 410B and 420B of unit 10Ua are positioned upstream of the beam splitters 430B and 440B of unit 10Ub in the laser's travel direction. Therefore, compared to the case where unit 10Ub is located closer to the opening 114h than unit 10Ua, unit 10Ua with beam splitters 410B and 420B can be easily accessed, and these beam splitters 410B and 420B tend to be replaced more frequently. Therefore, according to the gas laser device 100 of this modified example, the beam splitters 410B and 420B, which tend to be replaced frequently, can be easily replaced, and maintenance can be easily performed. Alternatively, in this view, unit 10Ua may have beam splitters 410B to 430B, and unit 10Ub may have beam splitter 440B.

[0149] 4. Description of the gas laser device in Embodiment 2

[0150] Next, the gas laser device 100 of Embodiment 2 will be described. Furthermore, structures identical to those described above will be labeled with the same reference numerals, and repeated descriptions will be omitted unless specifically stated otherwise. Additionally, in some of the accompanying drawings, parts have been omitted or simplified for ease of observation.

[0151] 4.1 Structure

[0152] Figure 10 This is a schematic diagram showing a schematic example of the structure of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 in this embodiment, viewed from an obliquely upward position. Figure 10As shown, the main difference between the gas laser device 100 of this embodiment and the gas laser device 100 of Embodiment 1 is that the first light guide unit 150 does not include a high reflectivity mirror 152, the pulse stretcher 400 does not include a ring optical path 440L, and the second light guide unit 155 does not include a high reflectivity mirror 157.

[0153] In the first light guiding unit 150 of this embodiment, a high reflectivity mirror 151 is disposed in the optical path of the laser from the output coupling mirror 370, so that the laser is reflected in the V direction, and the laser after being reflected by the high reflectivity mirror 151 is incident on the pulse stretcher 400.

[0154] In the pulse stretcher 400 of this embodiment, the light guide mirror 402 of the light guide optical system 401 is disposed in the optical path of the laser reflected by the high-reflectivity mirror 152, causing the laser reflected by the high-reflectivity mirror 151 to be reflected in the Z direction. The light guide mirror 403 is disposed in the optical path of the laser reflected by the light guide mirror 402, causing the laser reflected by the light guide mirror 402 to be reflected in the -V direction, and the laser is emitted from the pulse stretcher 400.

[0155] In this embodiment, the beam splitters 410B to 430B of the annular optical paths 410L to 430L are arranged in the order of beam splitters 410B, 420B, and 430B on the optical path of the laser reflected by the high-reflectivity mirror 151 and directed towards the guide mirror 402. Therefore, the beam splitters 410B to 430B are arranged in the order of beam splitters 410B, 420B, and 430B in the V direction parallel to the direction of gravity, and the annular optical paths 410L to 430L are arranged in the order of annular optical paths 410L, 420L, and 430L in the V direction. These annular optical paths 410L to 430L sequentially expand the pulse width of the laser, which exits from the pulse stretcher 400 and travels towards the second guide unit 155.

[0156] In the second light guiding unit 155 of this embodiment, a high-reflectivity mirror 156 is disposed in the optical path of the laser after it is reflected by the light guiding mirror 403, so that the laser emitted from the pulse stretcher 400 is reflected in the Z direction and travels towards the beam splitter 171.

[0157] The unit 10U of this embodiment includes beam splitters 410B to 430B, light guide mirrors 402 and 403, and a frame (not shown). The frame supports the beam splitters 410B to 430B and the light guide mirrors 402 and 403. Similar to the unit 10U of Embodiment 1, the unit 10U is separable from and detachable from the surround mirrors 411 to 414, 421 to 428, and 431 to 438.

[0158] 4.2 Function / Effect

[0159] In the pulse stretcher 400 of this embodiment, the annular optical paths 410L to 430L are arranged in the direction of gravity. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress the pulse stretcher 400 from becoming too large in the horizontal direction.

[0160] In the pulse stretcher 400 of this embodiment, beam splitters 410B to 430B are arranged in the direction of gravity. Therefore, according to the gas laser device 100 of this embodiment, the design of the pulse stretcher 400 can be kept from becoming complicated. Alternatively, beam splitters 410B to 430B may not be arranged in the direction of gravity. For example, beam splitter 430B may be arranged in the optical path of the laser light reflected by the light guide mirror 403.

[0161] 5. Description of the gas laser device in Embodiment 3

[0162] Next, the gas laser device 100 of Embodiment 3 will be described. Furthermore, structures identical to those described above will be labeled with the same reference numerals, and repeated descriptions will be omitted unless specifically stated otherwise. Additionally, in some of the accompanying drawings, parts have been omitted or simplified for ease of observation.

[0163] 5.1 Structure

[0164] Figure 11 This is a schematic diagram showing a schematic example of the structure of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 in this embodiment, viewed from an obliquely upward position. Figure 11 As shown, the pulse stretcher 400 of this embodiment differs from the pulse stretcher 400 of Embodiment 1 mainly in that the annular optical paths 410L to 440L each further include a light-transmitting flat substrate 410H to 440H.

[0165] Figure 12 This is a magnified schematic diagram showing the portion of the annular optical path 410L including the substrate 410H and the beam splitter 410B. The substrate 410H is disposed obliquely in the optical path of the laser light reflected by the surrounding mirror 414 and returning to the beam splitter 410B. Specifically, the substrate 410H is configured to be symmetrical with respect to a plane perpendicular to the optical path of the laser light reflected by the surrounding mirror 414 and returning to the beam splitter 410B. The thickness and refractive index of the substrate 410H are approximately the same as those of the beam splitter 410B. The section in the annular optical path 410L from the beam splitter 410B to the substrate 410H lies in a plane perpendicular to the V direction. The substrate 410H shifts the optical path of the laser light reflected by the surrounding mirror 414 and returning to the beam splitter 410B in the V direction, causing the laser light to overlap with the laser light traveling from the beam splitter 410B toward the guide mirror 402.

[0166] Similar to substrate 410H, substrate 420H is disposed obliquely on the optical path of the laser reflected by the surrounding mirror 428 and returning to the beam splitter 420B. Moreover, substrate 420H causes the laser returning to the beam splitter 420B to overlap with the laser traveling from the beam splitter 420B toward the guide mirror 403.

[0167] Similar to substrate 410H, substrate 430H is disposed obliquely on the optical path of the laser reflected by the surrounding mirror 438 and returning to the beam splitter 430B. Moreover, substrate 430H causes the laser returning to the beam splitter 430B to overlap with the laser traveling from the beam splitter 430B toward the guide mirror 403.

[0168] Similar to substrate 410H, substrate 440H is disposed obliquely on the optical path of the laser reflected by the surrounding mirror 452 and returning to the beam splitter 440B. Moreover, substrate 440H causes the laser returning to the beam splitter 440B to overlap with the laser from the beam splitter 440B toward the high-reflectivity mirror 156.

[0169] Examples of substrates 410H to 440H include calcium fluoride substrates. Furthermore, substrates 410H to 440H are configured to be tilted relative to the optical path of the laser returning to beam splitters 410B to 440B, and are used for light guiding so that the laser overlaps with another portion of the laser incident on beam splitters 410B to 440B; this is not limited. For example, the thickness and refractive index of substrates 410H to 440H may differ from those of beam splitters 410B to 440B.

[0170] The unit 10U of this embodiment includes beam splitters 410B to 440B, substrates 410H to 440H, light guide mirrors 402 and 403, and a frame (not shown). The frame supports the beam splitters 410B to 440B, substrates 410H to 440H, and light guide mirrors 402 and 403. Similar to the unit 10U of Embodiment 1, the unit 10U is separable from and detachable from the surround mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452.

[0171] 5.2 Function / Effect

[0172] In the pulse stretcher 400 of this embodiment, the annular optical paths 410L to 440L include transparent substrates 410H to 440H. The substrates 410H to 440H are a portion of the laser incident on the beam splitters 410B to 440B, and are configured to be tilted relative to the optical path of the laser returning to the beam splitters 410B to 440B. Furthermore, the substrates 410H to 440H guide light so that the laser overlaps with another portion of the laser incident on the beam splitters 410B to 440B. Therefore, the portion of the annular optical paths 410L to 440L from the beam splitters 410B to 440B to the substrates 410H to 440H can be located on a plane. Therefore, it is possible to prevent the design of the annular optical paths 410L to 440L from becoming complex.

[0173] In the pulse stretcher 400 of this embodiment, unit 10U includes all substrates 410H to 440H. Therefore, all substrates 410H to 440H can be easily replaced simultaneously. Alternatively, unit 10U may not include at least one substrate 410H to 440H.

[0174] 6. Description of the gas laser device in Embodiment 4

[0175] Next, the gas laser device 100 of Embodiment 4 will be described. Furthermore, structures identical to those described above will be labeled with the same reference numerals, and repeated descriptions will be omitted unless specifically stated otherwise. Additionally, in some of the accompanying drawings, parts have been omitted or simplified for ease of observation.

[0176] 6.1 Structure

[0177] Figure 13 This is a schematic diagram showing a schematic example of the structure of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 in this embodiment, viewed from an obliquely upward position. Figure 13 As shown, the pulse stretcher 400 of this embodiment differs from the pulse stretcher 400 of embodiment 2 mainly in that the annular optical paths 410L to 430L each further include a light-transmitting flat substrate 410H to 430H.

[0178] Similar to the substrate 410H in Embodiment 3, the substrate 410H is disposed obliquely on the optical path of the laser reflected by the surrounding mirror 414 and returning to the beam splitter 410B. Moreover, the substrate 410H causes the laser returning to the beam splitter 410B to overlap with the laser traveling from the beam splitter 410B toward the guide mirror 402.

[0179] Similar to substrates 420H and 430H in Embodiment 3, substrates 420H and 430H are disposed obliquely on the optical path of the laser light reflected by the surrounding mirrors 428 and 438 and returning to the beam splitters 420B and 430B. Furthermore, substrates 420H and 430H cause the laser light returning to the beam splitters 420B and 430B to overlap with the laser light traveling from the beam splitters 420B and 430B toward the guide mirror 402.

[0180] The unit 10U of this embodiment includes beam splitters 410B to 430B, substrates 410H to 430H, light guide mirrors 402 and 403, and a frame (not shown). The frame supports the beam splitters 410B to 430B, substrates 410H to 430H, and light guide mirrors 402 and 403. Similar to the unit 10U of Embodiment 2, the unit 10U is separable from and detachable from the surround mirrors 411 to 414, 421 to 428, and 431 to 438.

[0181] 6.2 Function / Effect

[0182] In the pulse stretcher 400 of this embodiment, the annular optical paths 410L to 430L include transparent substrates 410H to 430H. The substrates 410H to 430H are a portion of the laser incident on the beam splitters 410B to 430B, and are configured to be tilted relative to the optical path of the laser returning to the beam splitters 410B to 430B. Furthermore, the substrates 410H to 430H are used for light guiding so that the laser overlaps with another portion of the laser incident on the beam splitters 410B to 430B. Therefore, similar to the gas laser device 100 of Embodiment 3, the section in the annular optical paths 410L to 430L from the beam splitters 410B to 430B to the substrates 410H to 430H can be located on a plane. Therefore, it is possible to prevent the design of the annular optical paths 410L to 430L from becoming complex.

[0183] In the pulse stretcher 400 of this embodiment, unit 10U includes all substrates 410H to 430H. Therefore, similar to the gas laser device 100 of embodiment 3, all substrates 410H to 430H can be easily replaced simultaneously. Alternatively, unit 10U may not include at least one substrate 410H to 430H.

[0184] The above description uses the above-described embodiments as examples; however, this disclosure is not limited thereto and can be appropriately modified.

[0185] In embodiments 1 and 3 described above, a pulse stretcher 400 comprising a unit 10U having four beam splitters 410B to 440B was used as an example for explanation. In embodiments 2 and 4 described above, a pulse stretcher 400 comprising a unit 10U having three beam splitters 410B to 430B was used as an example for explanation. However, the pulse stretcher 400 may simply comprise a unit that can separate and detach two or more beam splitters from one or more surround mirrors. For example, the unit 10U may also comprise a portion of surround mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452.

[0186] Furthermore, in a variation of Embodiment 1 described above, unit 10Ua is used as an example. This unit 10Ua has beam splitters 410B and 420B positioned upstream of beam splitters 430B and 440B of unit 10Ub in the laser's travel direction, and located on the side closer to opening 114h than unit 10Ub. However, it is permissible for at least one of units 10Ua and 10Ub to have two or more beam splitters. For example, unit 10Ua may have beam splitters 410B, 420B, and 430B, and unit 10Ub may have beam splitter 440B.

[0187] Furthermore, in embodiments 1 and 3 described above, a pulse stretcher 400 having four annular optical paths 410L to 440L was used as an example for explanation, and in embodiments 2 and 4 described above, a pulse stretcher 400 having three annular optical paths 410L to 430L was used as an example for explanation. However, the number of annular optical paths can be multiple.

[0188] Furthermore, in the above embodiments, examples of a ring optical path 410L with four surrounding mirrors, a ring optical path 420L with eight surrounding mirrors, a ring optical path 430L with eight surrounding mirrors, and a ring optical path 440L with twelve surrounding mirrors have been described. However, the number of surrounding mirrors constituting the ring optical path is not limited. In addition, it is preferable that the ring optical path is positioned downstream in the direction of travel of the pulsed laser, the more surrounding mirrors it has.

[0189] Furthermore, in the above embodiments, a light-guiding optical system 401 consisting of two light-guiding mirrors 402 and 403 has been described as an example. However, the number of light-guiding mirrors constituting the light-guiding optical system 401 is not limited. In addition, the pulse stretcher 400 may also not have a light-guiding optical system 401.

[0190] Furthermore, in embodiments 1 and 3 described above, a first light guide unit 150 including high-reflectivity mirrors 151 and 152 and a second light guide unit 155 including two high-reflectivity mirrors 156 and 157 were used as examples for explanation. However, since the laser emitted from the cavity device CH3 can be incident on the pulse stretcher 400, the number of high-reflectivity mirrors included in the first light guide unit 150 and the second light guide unit 155 is not limited. In addition, the gas laser device 100 may not include at least one of the first light guide unit 150 and the second light guide unit 155.

[0191] Furthermore, in the above embodiments, a housing 110 having a first main body 111 and a second main body 112 disposed on the upper wall of the first main body 111 has been described as an example. However, the arrangement of the second main body 112 is not limited. For example, the second main body 112 may also be disposed below the first main body 111. In addition, the first main body 111 may also serve as the second main body 112. That is, the pulse stretcher 400 may also be disposed in the storage space of the first main body 111. Furthermore, the opening direction of the opening 114h is not limited. For example, the opening 114h may also be formed on the upper wall 115 of the second main body 112.

[0192] Furthermore, in the above embodiments, the beam splitters 410B to 440B, in which reflected laser light propagates to the annular optical paths 410L to 440L, have been described as examples. However, laser light passing through the beam splitters 410B to 440B can also propagate to the annular optical paths 410L to 440L. In this case, the beam splitters 410B to 440B are part of the light guiding optical system 401, and the light guiding optical system 401 and the annular optical paths 410L to 440L share the beam splitters 410B to 440B.

[0193] Furthermore, in the above embodiments, a gas laser device 100 having a laser oscillator 130 and an amplifier 160 has been described as an example. However, the gas laser device 100 may also not have an amplifier 160. In this case, for example, the laser emitted from the cavity device CH1 and passing through the output coupling mirror 70 is incident on the pulse stretcher 400.

[0194] The foregoing description is not a limitation but merely illustrative. Therefore, those skilled in the art will understand that modifications can be made to the embodiments of this disclosure without departing from the claims. Furthermore, those skilled in the art will understand that the embodiments of this disclosure can be used in combination. Unless explicitly stated otherwise, the language used throughout this specification and the claims should be interpreted as “non-limiting”. For example, terms such as “comprising,” “having,” “possessing,” and “comprise” should be interpreted as “excluding the presence of structural elements other than the described structural elements.” Furthermore, the modifier “a” should be interpreted as meaning “at least one” or “one or more.” Moreover, the phrase “at least one of A, B, and C” should be interpreted as “A,” “B,” “C,” “A+B,” “A+C,” “B+C,” or “A+B+C,” and further, should be interpreted as including combinations of these and portions other than “A,” “B,” and “C.”

Claims

1. A gas laser device, comprising: Cavity device that emits pulsed laser light; and A pulse stretcher comprising multiple annular optical paths that extend the pulse width of the pulsed laser. The annular optical path includes: a beam splitter to which the pulsed laser is incident; and a plurality of surrounding mirrors that sequentially reflect a portion of the pulsed laser incident on the beam splitter and return it to the beam splitter in a manner that overlaps with another portion of the pulsed laser. The pulse stretcher includes a unit that can separate and detach two or more of the beam splitters from one or more of the surrounding mirrors.

2. The gas laser device according to claim 1, wherein, The gas laser device also has a housing comprising: a main body that houses the pulse stretcher and has an opening for the unit to enter and exit; and a moving mechanism that allows the unit to move in a manner that enables it to enter and exit through the opening.

3. The gas laser device according to claim 2, wherein, The opening direction is horizontal. The movement direction of the unit, achieved by the moving mechanism, is horizontal.

4. The gas laser device according to claim 2, wherein, The housing also includes a maintenance panel that blocks the opening and is detachably mounted to the main body.

5. The gas laser device according to claim 1, wherein, The unit contains all of the aforementioned beam splitters.

6. The gas laser device according to claim 1, wherein, The pulse stretcher also includes a light-guiding optical system comprising multiple light-guiding mirrors, which sequentially direct the pulsed laser light onto the beam splitters of the multiple annular optical paths. The unit includes at least one of the light guide mirrors.

7. The gas laser device according to claim 6, wherein, The unit contains all of the light guide mirrors.

8. The gas laser device according to claim 1, wherein, The annular optical path further includes a light-transmitting substrate configured to be tilted relative to the portion of the pulsed laser returning to the beam splitter, so as to guide light in a manner that the portion of the pulsed laser overlaps with the other portion of the pulsed laser. The unit includes the substrate.

9. The gas laser device according to claim 8, wherein, The unit comprises all of the substrates.

10. The gas laser device according to claim 1, wherein, The surrounding mirror is a concave mirror.

11. The gas laser device according to claim 1, wherein, The plurality of said annular optical paths are configured to be arranged in the direction of gravity.

12. The gas laser device according to claim 11, wherein, The beam splitters in the plurality of said annular optical paths configured to be arranged in the direction of gravity are configured to be arranged in the direction of gravity.

13. The gas laser device according to claim 1, wherein, The ring optical path has three or more components. The pulse stretcher includes another unit containing a beamsplitter different from the beamsplitter contained in the unit, which is separable from and detachable from one or more of the surrounding mirrors.

14. The gas laser device according to claim 13, wherein, The gas laser device also includes a housing comprising a main body that houses the pulse stretcher and has openings for access to the unit and the other unit. The unit is located closer to the opening side than the other unit. The beam splitter of the unit is positioned upstream of the beam splitter of the other unit in the direction of travel of the pulsed laser.

15. A method for manufacturing an electronic device, comprising the following steps: The pulsed laser generated by the gas laser device is output to the exposure device. The pulsed laser output to the exposure apparatus exposes a photosensitive substrate within the exposure apparatus to manufacture electronic devices. The gas laser device has the following features: Cavity device that emits pulsed laser light; and A pulse stretcher comprising multiple annular optical paths that extend the pulse width of the pulsed laser. The annular optical path includes: a beam splitter to which the pulsed laser is incident; and a plurality of surrounding mirrors that sequentially reflect a portion of the pulsed laser incident on the beam splitter and return it to the beam splitter in a manner that overlaps with another portion of the pulsed laser. The pulse stretcher includes a unit that can separate and detach two or more of the beam splitters from one or more of the surrounding mirrors.

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