Gas laser device and method for manufacturing electronic devices

Abstract

A gas laser device includes: a chamber device that emits pulsed laser light; a pulse stretcher that has a plurality of ring-shaped optical paths that stretch a pulse width of the pulsed laser light; and a housing that includes a main body portion that houses the pulse stretcher and is formed with an opening through which the pulse stretcher is able to enter and exit, the ring-shaped optical paths include: a beam splitter into which the pulsed laser light is incident; and a plurality of wrap-around mirrors that sequentially reflect a portion of the pulsed laser light that is incident on the beam splitter and return it to the beam splitter to overlap with another portion of the pulsed laser light, the pulse stretcher includes a plurality of modules that have two or more optical elements including at least one of the beam splitter and the wrap-around mirrors and are able to individually enter and exit from the opening, the plurality of modules include a first module and a second module that is located at a position opposite to the first module on a side closer to the opening than the first module, and a deterioration speed of at least one optical element of the first module is faster than a deterioration speed of an optical element of the second module.

Description

Technical Field

[0001] This disclosure relates to a gas laser device and a method for manufacturing 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, efforts are underway to shorten the wavelength of light emitted from the exposure light source. For example, as gas laser devices for exposure, KrF excimer lasers using lasers with an output wavelength of approximately 248 nm and ArF excimer lasers using lasers with an output wavelength of approximately 193 nm are being developed.

[0003] Furthermore, excimer lasers have pulse widths of approximately tens of nanoseconds and wavelengths as short as 248 nm and 193 nm, respectively, making them sometimes used for the direct processing of polymer materials, glass materials, and the like. The chemical bonds in polymer materials can be broken using 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, producing aesthetically pleasing shapes. Additionally, glass and ceramics are known to have high absorption rates for excimer lasers, allowing even materials that are difficult to process using visible and infrared lasers to be processed using excimer lasers.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-148550

[0007] Patent Document 2: International Publication No. 2024 / 047867

[0008] Patent Document 3: US Patent No. 9093817 Summary of the Invention

[0009] One aspect of the gas laser device disclosed herein may include: a cavity device that emits a pulsed laser; a pulse stretcher having a plurality of annular optical paths that stretch the pulse width of the pulsed laser; and a housing including a main body that houses the pulse stretcher and has an opening for the pulse stretcher to enter and exit. The annular optical paths include: 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 to overlap with another portion of the pulsed laser. The pulse stretcher includes a plurality of modules having two or more optical elements including at least one of the beam splitter and the surrounding mirrors, and can enter and exit individually from the opening. The plurality of modules includes a first module and a second module located on the opposite side of the opening, closer to the first module. The degradation rate of at least one optical element of the first module is faster than that of the optical element of the second module.

[0010] A method for manufacturing an electronic device according to one aspect of this disclosure may include the following steps: outputting a pulsed laser generated by a gas laser device to an exposure device, and exposing the pulsed laser output to the exposure device on a photosensitive substrate within the exposure device to manufacture the electronic device. The gas laser device comprises: a chamber device that emits the pulsed laser; a pulse stretcher having multiple annular optical paths for stretching the pulse width of the pulsed laser; and a housing including a main body that houses the pulse stretcher and has an opening for the pulse stretcher to enter and exit. The annular optical paths include: a beam splitter, a pulsed laser inlet... The pulse beam stretcher includes a beam splitter 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 to overlap with another portion of the pulsed laser. The pulse stretcher includes a plurality of modules having two or more optical elements including at least one of the beam splitter and the surrounding mirrors, and being able to enter and exit independently from an opening. The plurality of modules includes a first module and a second module located on the opposite side of the opening, closer to the first module. At least one optical element of the first module degrades faster than the optical element of the second module. Attached Figure Description

[0011] The following description, by way of example only, refers to the accompanying drawings to illustrate several embodiments of this disclosure.

[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 electronic devices.

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

[0014] Figure 3This 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 position.

[0017] Figure 6 This is a schematic diagram showing multiple modules and a housing according to Embodiment 1.

[0018] Figure 7 This is a schematic diagram illustrating a general structural example of the module in Embodiment 1.

[0019] Figure 8 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.

[0020] Figure 9 Is with Figure 6 Similarly, schematic diagrams of multiple modules and housings of Embodiment 2 are shown.

[0021] Figure 10 Is with Figure 6 Similarly, schematic diagrams of multiple modules and housings of a variation of Embodiment 2, Example 1, are shown.

[0022] Figure 11 This is a schematic diagram showing multiple modules and a housing of a variation of embodiment 2. Detailed Implementation

[0023] 1. Description of the electronic device manufacturing apparatus used in the exposure process of electronic devices.

[0024] 2. Description of the comparative gas laser device

[0025] 2.1 Structure

[0026] 2.2 Actions

[0027] 2.3 Research Topic

[0028] 3. Description of the gas laser device in Embodiment 1

[0029] 3.1 Structure

[0030] 3.2 Maintenance methods for pulse stretchers

[0031] 3.3 Functions and Effects

[0032] 4. Description of the gas laser device in Embodiment 2

[0033] 4.1 Structure

[0034] 4.2 Maintenance methods for pulse stretchers

[0035] 4.3 Functions and Effects

[0036] 4.4 Explanation of Variation Example 1

[0037] 4.5 Explanation of Variation Example 2

[0038] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below illustrate several examples of the present disclosure and do not limit the content of the present disclosure. In addition, not all the structures and operations described in each embodiment are necessary. Furthermore, the same reference numerals are used to refer to the same constituent elements, and repeated descriptions are omitted.

[0039] 1. Description of the electronic device manufacturing apparatus used in the exposure process of electronic devices.

[0040] 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 apparatus 200. The exposure apparatus 200 includes an illumination optics system 210 and a projection optics system 220. The illumination optics system 210 has 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 apparatus 200 exposes the workpiece with laser light reflecting the mask pattern by synchronously and parallelly moving the mask stage RT and the workpiece stage WT. By using the exposure process described above to transfer device patterns onto a semiconductor wafer, semiconductor devices as electronic devices can be manufactured.

[0041] 2. Description of the comparative gas laser device

[0042] 2.1 Structure

[0043] The gas laser apparatus of the comparative example will be described. Furthermore, the comparative examples disclosed herein are those known only to the applicant, and not those that the applicant considers to be publicly known.

[0044] 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 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 ArF and KrF excimer laser devices, helium (He) can be used instead of Ne.

[0045] The gas laser device 100 in this example includes a housing 110, a laser oscillator 130 as a main oscillator disposed in the internal space of the housing 110, an optical transmission unit 141, an amplifier 160 as a 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 as its main structures.

[0046] The laser oscillator 130 includes a chamber device CH1, a charger 41, a pulse power module 43, a narrowband module 60, and an output coupling mirror 70 as its main structures.

[0047] exist Figure 2 The diagram shows the internal structure of the chamber device CH1 as viewed from a direction approximately perpendicular to the direction of laser travel. The chamber 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 holding part 36 as its main structures.

[0048] The housing 30 receives the laser gas from the laser gas supply device 703 of the gas module 700 via piping into its internal space, thus sealing the laser gas within the internal space. The internal space is the space where light is generated by the excitation of the laser medium within the laser gas. This light travels to windows 31a and 31b.

[0049] Window 31a is disposed on the front wall of housing 30 in the direction of laser travel from gas laser device 100 to exposure device 200, and window 31b is disposed on the rear wall of housing 30 in the same direction of travel. Windows 31a and 31b are calcium fluoride substrates, and the surfaces of windows 31a and 31b located on the inner and outer sides of housing 30 are planar. Furthermore, windows 31a and 31b are not limited to calcium fluoride substrates, as long as they allow laser light to pass through.

[0050] Electrodes 32a and 32b are arranged opposite each other within the internal space of the housing 30, with their length direction aligned with the direction of light propagation generated by the high voltage applied between electrodes 32a and 32b. The space between electrodes 32a and 32b in the housing 30 is enclosed by 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.

[0051] Electrode 32a is supported by insulating portion 33. Insulating portion 33 closes the opening formed in housing 30. Insulating portion 33 includes an insulator. In addition, a feedthrough portion 34 made of conductive member is disposed in insulating portion 33. Feedthrough portion 34 applies voltage supplied from pulse power module 43 to electrode 32a. Electrode 32b is supported by electrode holding portion 36 and is electrically connected to electrode holding portion 36.

[0052] Charger 41 is a DC power supply device that charges a capacitor (not shown) disposed inside the pulse power module 43 with a specified voltage. Charger 41 is disposed outside the housing 30 and connected to the pulse power module 43. The pulse power module 43 includes a switch (not shown) controlled by processor 190. The pulse power module 43 is a voltage application circuit that, when the switch changes from open to closed by the control, boosts the voltage applied from the charger 41 to generate a pulsed high voltage, which is applied 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 the housing 30. As the excited laser gas transitions to the ground state, light is emitted, and the emitted light passes through windows 31a and 31b and exits to the outside of the housing 30. As described above, the pulsed high voltage is applied between electrodes 32a and 32b by the pulse power module 43, therefore the laser is a pulsed laser.

[0053] Windows 31a and 31b can also be tilted at a Brewster angle relative to the laser's direction of travel to suppress 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 the chamber device CH1 contains first linearly polarized light with a polarization direction perpendicular to the direction opposite to electrodes 32a and 32b, and reduces the amount of linearly polarized light with a polarization direction different from that of the first linearly polarized light from the laser. That is, windows 31a and 31b, tilted relative to the polarization direction of the first linearly polarized light, also act as polarizers, which reduce the amount of linearly polarized light with a polarization direction different from that of the first linearly polarized light from the laser.

[0054] The narrowband module 60 includes a housing 65, a prism 61 disposed within the interior space of the housing 65, a grating 63, and a rotating stage (not shown). 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.

[0055] Prism 61 widens the beam width of light emitted from window 31b, allowing the light to enter the grating 63. Additionally, prism 61 narrows the beam width of reflected light from the grating 63, causing the light to return through window 31b to the interior space of housing 30. Prism 61 is supported by a rotating stage and rotates via the stage. Rotation of prism 61 changes the angle of incidence of light onto 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 has one prism 61, but more than two prisms can also be configured.

[0056] 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 by Littrow such 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.

[0057] 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 other portion is reflected and returns to the interior space of the housing 30 via the window 31a. The output coupling mirror 70 is fixed to a holding part (not shown) and disposed within the interior space of the housing 110.

[0058] A Fabry-Perot type resonator is formed by a grating 63 and an output coupling mirror 70 separated by a housing 30, which is positioned in the optical path of the resonator. Therefore, the resonator causes optical resonance between the two sides of the cavity device CH1.

[0059] The optical transmission unit 141 includes high-reflectivity mirrors 141b and 141c as its main structure. High-reflectivity mirrors 141b and 141c are fixed to brackets (not shown) with their respective tilt angles adjusted, and are disposed within the internal space of the housing 110. High-reflectivity mirrors 141b and 141c highly reflect the laser light. High-reflectivity 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 high-reflectivity mirrors 141b and 141c and travels to the rear mirror 371 of the amplifier 160. At least a portion of the laser light passes through the rear mirror 371.

[0060] 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 components of amplifier 160 from those of laser oscillator 130, the following components of amplifier 160 will be described as: chamber device CH3, housing 330, pair of windows 331a, 331b, pair of electrodes 332a, 332b, insulation 333, feedthrough 334, electrode holding part 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.

[0061] 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. By tilting windows 331a and 331b in this way, the laser emitted from the cavity device CH3 contains the first linearly polarized light, and reduces the amount of linearly polarized light whose polarization direction differs from that of the first linearly polarized light from the laser. That is, windows 331a and 331b, like windows 31a and 31b, are tilted relative to the polarization direction of the first linearly polarized light, and also act as polarizers, which reduce the amount of linearly polarized light whose polarization direction differs 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 rectangular shape in the direction in which a pair of electrodes 332a and 332b face each other. Pulse power module 343 is also a voltage application circuit, just like pulse power module 43.

[0062] In addition, 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.

[0063] 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 and be directed toward the space between the electrodes 332a and 332b, and reflects a portion of the laser light amplified by the electrodes 332a and 332b toward the space between the electrodes 332a and 332b.

[0064] An output coupling mirror 370 is disposed between the window 331a and the high-reflectivity mirror 151, respectively, and faces them. The output coupling mirror 370 causes a portion of the laser light emitted and amplified by the electrodes 332a and 332b to be reflected toward the space between the electrodes 332a and 332b, while allowing another portion of the laser light to pass through toward 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 the window 331a.

[0065] The output coupling mirror 370 can be circular. The surface of the output coupling mirror 370 facing the window 331a and the surface opposite to that surface are planar. The output coupling mirror 370 has a similar structure to the output coupling mirror 70.

[0066] A resonator is formed by a rear mirror 371 and an output coupling mirror 370 sandwiched between housing 330, which resonate the laser beam amplified by electrodes 332a and 332b. Housing 330 is positioned in the optical path of the resonator. Laser light emitted from window 331a of housing 330 is incident on output coupling mirror 370, and a portion is reflected by output coupling mirror 370. The laser light reflected by output coupling mirror 370 returns to the interior space of housing 330 via window 331a and exits from window 331b. Laser light emitted from window 331b is reflected by rear mirror 371 and returns to the interior space of housing 330 via window 331b. Thus, the laser light emitted from housing 330 oscillates between rear mirror 371 and output coupling mirror 370. The oscillating laser light is amplified each time it passes through the discharge space between electrodes 332a and 332b. That is, the resonator causes optical resonance between the two sides of the cavity device CH3, and the output coupling mirror 370 is disposed on one side of the cavity device CH3. A portion of the amplified laser light passes through the output coupling mirror 370. The laser light passing through the output coupling mirror 370 travels to the high-reflectivity mirror 151. Thus, the laser light traveling from the output coupling mirror 370 to the high-reflectivity mirror 151 is a pulsed laser.

[0067] Figure 3 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, viewed from an obliquely upward view. The first light guide unit 150 includes high-reflectivity mirrors 151 and 152 as its main structure. Hereinafter, the direction of the laser beam that is parallel to the optical axis of the laser emitted from the window 331a of the chamber device CH3 and passes through the output coupling mirror 370, and the direction in which the laser beam propagates, will be defined as the Z direction. The height direction of the gas laser device 100 will be defined as the V direction, and the direction orthogonal to the V and Z directions will be defined as the H direction. In this example, the optical axis of the laser beam emitted from the window 331a and passes through the output coupling mirror 370 is approximately parallel to the horizontal direction. In addition, the V direction in this example is parallel to the direction of gravity.

[0068] High-reflectivity mirrors 151 and 152, with their respective tilt angles adjusted, are fixed to a bracket (not shown) to highly reflect the laser light. Figure 3 In the diagram, the outline of the laser is represented by 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, reflecting the laser in the H direction. High-reflectivity mirror 152 is positioned in the optical path of the laser reflected by high-reflectivity mirror 151, reflecting the laser in the V direction. The laser reflected by high-reflectivity mirror 152 is incident on pulse stretcher 400.

[0069] The pulse stretcher 400 includes multiple optical elements that stretch the pulse width of the laser pulse incident from the first light guide unit 150 to the pulse stretcher 400, and then the laser pulse-width stretched is emitted toward the second light guide unit 155.

[0070] The pulse stretcher 400 in this example includes a light-guiding optical system 401 and four ring optical paths 410L, 420L, 430L and 440L as the main structure, which are arranged on the V-direction side of the optical axis of the laser that passes through the output coupling mirror 370.

[0071] 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 bracket (not shown) with their respective tilt angles adjusted, and provide high reflection of the laser. The light-guiding mirrors 402 and 403 are, for example, plane mirrors. The light-guiding mirror 402 is positioned further towards the H-direction than 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 further towards the -H-direction than 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.

[0072] 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 other optical elements. The beam splitter 410B is positioned on the optical path of the laser in the light guiding optical system 401. The laser beam that is reflected by the high-reflectivity mirror 152 and incident on the pulse stretcher 400 and towards the light guiding mirror 402 is fixed to a bracket (not shown). The beam splitter 410B splits the incident laser into two beams, allowing one of the split beams to pass through and propagate towards the light guiding mirror 402, thus propagating in the optical path of the light guiding optical system 401, while reflecting the other split beam towards the surrounding mirror 411.

[0073] The surrounding mirrors 411-414 are, for example, concave mirrors, supported by a bracket (not shown). Surrounding mirrors 411 and 413 are positioned further along the Z-direction than 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 further along the -Z-direction than 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, as well as surrounding mirrors 412 and 413, are respectively positioned opposite each other in a direction parallel to the Z-direction. Beam splitter 410B is located between surrounding mirrors 411 and 414.

[0074] The surrounding mirrors 411-414 reflect the laser light reflected by the beam splitter 410B in the order of 411, 412, 413, and 414, causing it to return to the beam splitter 410B. The laser light reflected by the surrounding mirror 414 enters the beam splitter 410B from a surface opposite to the incident surface of the laser light reflected by 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 via the surrounding mirrors 411-414, and the annular optical path 410L is broadened in the H and Z directions.

[0075] Beam splitter 410B receives a portion of the laser light reflected by the surrounding mirror 414 and returned to beam splitter 410B, which is then reflected by the guide mirror 402, allowing another portion to pass through and towards the surrounding mirror 411. The transmitted laser light propagates in the annular optical path 410L. Thus, the laser light is reflected four times in the annular optical path 410L, completing one revolution, and thus completing more than one revolution in the annular optical path 410L.

[0076] The laser beam returning to the beam splitter 410B after one revolution around the annular optical path 410L and being separated by the beam splitter 410B and directed toward the guide mirror 402, is delayed by a predetermined time compared to the laser beam that does not proceed to the surround mirror 411 but passes through the beam splitter 410B and is directed toward the guide mirror 402. After this predetermined time delay, a portion of the laser beam returning to the guide mirror 402 from the beam splitter 410B overlaps with a portion of the laser beam that does not proceed to the surround mirror 411 but passes through the beam splitter 410B and is directed toward the guide mirror 402. That is, the laser returning to the beam splitter 410B is separated into a portion of the laser beam that overlaps with a portion of the laser beam separated by the beam splitter 410B, and a portion of the laser beam that is sequentially reflected by the surround mirrors 411-414. Laser overlap occurs every time the laser orbits the annular optical path 410L. Through this laser overlap, the pulse width of the laser is broadened and propagates in the light guide mirror 402 within the light guide optical system 401.

[0077] 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 other optical elements. Additionally, in Figure 3 For 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. The beam splitter 420B is positioned on the path of the laser beam reflected by the light guide mirror 402 towards the light guide mirror 403 in the light guide optical system 401, and is fixed to a bracket (not shown). Surrounding mirrors 421 to 428 are, for example, concave mirrors, supported by a bracket (not shown). Surrounding mirrors 421, 423, 425, and 427 are positioned further towards the Z-direction than light guide mirrors 402 and 403, while surrounding mirrors 422, 424, 426, and 428 are positioned further towards the -Z-direction than light guide mirrors 402 and 403. Similar to the surrounding mirrors 411-414 of the ring optical path 410L, surrounding mirrors 421-428 sequentially reflect a portion of the laser light incident on the beam splitter 420B, returning it to the beam splitter 420B to overlap with another portion of the laser light. Furthermore, similar to the ring optical path 410L, laser overlap occurs, and the pulse width-broadened laser light propagates from the beam splitter 420B towards the guide mirror 403 in the guide optical system 401. The ring optical path 420L is broadened 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. Additionally, the ring optical path 420L is located further towards the V direction than the ring optical path 410L, and the ring optical paths 410L and 420L overlap in a direction parallel to the V direction.

[0078] 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 other optical elements. Additionally, in Figure 3For ease of observation, only four surround mirrors 431, 432, 437, and 438 are described, while the description of four surround mirrors 433 to 436 is omitted. Beam splitter 430B is positioned on the optical path of the laser beam in the light-guiding optical system 401, guiding the laser beam from beam splitter 420B to light-guiding mirror 403, and is fixed to a bracket (not shown). Surround mirrors 431 to 438 are, for example, concave mirrors, supported by a bracket (not shown). Surround mirrors 431, 433, 435, and 437 are positioned further towards the Z-direction than light-guiding mirrors 402 and 403, while surround mirrors 432, 434, 436, and 438 are positioned further towards the -Z-direction than light-guiding mirrors 402 and 403. Similar to the surrounding mirrors 411-414 of the ring optical path 410L, surrounding mirrors 431-438 sequentially reflect a portion of the laser light incident on the beam splitter 430B, returning it to the beam splitter 430B to overlap with the remaining portion of the laser light. Furthermore, similar to the ring optical path 410L, laser overlap occurs, and the pulse width-broadened laser light propagates from the beam splitter 430B towards the guide mirror 403 in the guide optical system 401. The ring optical path 430L is broadened 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. Additionally, the ring optical path 430L is located further towards the -H direction than the ring optical path 420L, and the ring optical paths 420L and 430L overlap in a direction parallel to the H direction.

[0079] 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 other optical elements. Additionally, in Figure 3 For ease of observation, only four surround mirrors 441, 442, 451, and 452 are described, omitting the description of the eight surround mirrors 443 to 450. The beam splitter 440B is positioned on the optical path of the laser beam reflected in the -V direction by the light guide mirror 403 in the light guide optical system 401, and is fixed to a bracket (not shown). The beam splitter 440B separates the incident laser beam into two beams, allowing one beam to pass through so that it exits from the pulse stretcher 400 and faces the second light guide unit 155, while reflecting the other beam towards the surround mirror 441.

[0080] The surrounding mirrors 441-452 are, for example, concave mirrors, supported by a bracket (not shown). Surrounding mirrors 441, 443, 445, 447, 449, and 451 are positioned further along the Z-direction than the light-guiding mirrors 402 and 403, while surrounding mirrors 442, 444, 446, 448, 450, and 452 are positioned further along the -Z-direction than the light-guiding mirrors 402 and 403. Similar to the surrounding mirrors 411-414 of the ring optical path 410L, surrounding mirrors 441-452 sequentially reflect a portion of the laser light incident on the beam splitter 440B, returning it to the beam splitter 440B to overlap with another portion of the laser light. Furthermore, similar to the ring optical path 410L, laser overlap occurs, and the pulse width-broadened laser light propagates towards the second light-guiding unit 155 in the light-guiding optical system 401. The annular optical path 440L widens 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 further towards the -V direction than annular optical path 430L, and further towards 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.

[0081] In this way, 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. Furthermore, the pulse width of the laser is broadened sequentially through the annular optical paths 410L to 440L. That is, the annular optical paths 410L, 420L, 430L, and 440L are arranged sequentially from the upstream side to the downstream side in the direction of laser travel. Moreover, the laser with its pulse width broadened is emitted from the pulse broadener 400 and travels to the second light guiding unit 155.

[0082] 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 brackets (not shown) with their respective tilt angles adjusted, and perform high reflection of the laser. 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 further towards the -H direction than the optical axis of the laser passing 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 not be parallel to the optical axis of the laser passing through the output coupling mirror 370.

[0083] The detection unit 170 includes a beam splitter 171 and an optical sensor 172 as its main structures.

[0084] Beam splitter 171 is disposed 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 with high transmittance toward the emission window 173, and reflects a portion of the laser toward the light-receiving surface of the photosensor 172.

[0085] 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 uses this signal to control the voltage applied to electrodes 32a and 32b of amplifier 160.

[0086] An emission window 173 is disposed on the wall of the housing 110. Light transmitted through the beam splitter 171 is emitted from the emission window 173 to the exposure device 200 outside the housing 110. The laser is, for example, a pulsed laser with a center wavelength of 193.4 nm.

[0087] The display unit 180 is a monitor that displays the control status of the processor 190 based on signals from the processor 190. The display unit 180 can also be configured outside the housing 110.

[0088] The processor 190 of this disclosure is a processing device including a storage device for storing control programs and a CPU (Central Processing Unit) for executing the control programs. 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 apparatus 200, and transmits and receives various signals with and from the exposure processor.

[0089] 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 from a laser gas supply source (not shown) located outside the housing 110 to the internal spaces of the housings 30 and 330 through piping.

[0090] 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 plate 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 mentioned above. 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.

[0091] 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 lower wall 113 that is longer in the Z direction and rectangular in shape, 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 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 parallel to the Z and V directions. An opening 114h is formed on the H-direction sidewall 114 of the two opposing sidewalls 114 in a direction parallel to the H direction, through which the pulse stretcher 400 housed in the internal space can be accessed. The opening 114h is a rectangular shape that is longer in the Z direction, and the opening direction of the opening 114h is the H direction, which is horizontal.

[0092] The maintenance plate 116 is a plate-shaped component that blocks the opening 114h. The maintenance plate 116 is detachably mounted on the second main body 112. Figure 4 The image shows the state where the maintenance plate 116 has been removed from the second main body 112. Furthermore, the opening 114h is not limited in position or shape, as long as it allows the pulse stretcher 400 to enter and exit.

[0093] 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 is emitted from the pulse stretcher 400. Therefore, the upper wall of the first main body 111 and the lower wall 113 of the second main body 112 are provided with through holes (not shown) for the laser light reflected in the V direction by the high-reflectivity mirror 152 to pass through, and other through holes (not shown) for the laser light reflected in the -V direction by the light guide mirror 403 to pass through.

[0094] 2.2 Actions

[0095] Next, the operation of the comparative example gas laser device 100 will be explained.

[0096] 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 housing 30, 330.

[0097] 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 to make the energy E the target energy Et, and synchronously turns on the switch of the pulse power module 43 with the light emission trigger signal. As a result, the pulse power module 43 generates a pulsed high voltage based on the electrical energy held in the charger 41, and applies a high voltage between electrodes 32a and 32b. When a high voltage is applied, a discharge is caused between electrodes 32a and 32b, and the laser medium contained in the laser gas between electrodes 32a and 32b becomes excited. When the laser medium returns to its ground state, it emits light. 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, causing laser oscillation. The laser contains first linearly polarized light. When it passes through windows 31a and 31b, linearly polarized light with a polarization direction different from that of the first linearly polarized light is reduced from the laser. A portion of the laser passes through the output coupling mirror 70, is reflected by high-reflectivity mirrors 141b and 141c, and passes through the rear mirror 371 and window 331b, and travels into the housing 330.

[0098] The processor 190 switches on the pulse power module 343, causing a discharge to occur between electrodes 332a and 332b when the laser from the laser oscillator 130 travels into the discharge space within the housing 330. Specifically, 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 time when the pulse power module 43 is switched on.

[0099] Therefore, the laser incident on amplifier 160 is amplified in amplifier 160. Additionally, the laser traveling into the interior space of housing 330, as described above, travels through windows 331a and 331b to the rear mirror 371 and output coupling mirror 370. Thus, the laser of a defined wavelength travels back and forth between the rear mirror 371 and the output coupling mirror 370. The laser contains first linearly polarized light, and when passing through windows 331a and 331b, linearly polarized light with a polarization direction different from 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.

[0100] The amplified laser from amplifier 160 travels through output coupling mirror 370 to high-reflectivity mirror 151. The laser is reflected by high-reflectivity mirror 151 towards high-reflectivity mirror 152. The laser reflected by high-reflectivity mirror 151 is reflected by high-reflectivity mirror 152 in the V direction and incident on pulse stretcher 400.

[0101] 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 from the pulse stretcher 400. Furthermore, in the pulse stretcher 400, during the sequential reflection by the light guide mirrors 402 and 403 of the light guide optical system 401, the pulse width of the laser is broadened through the annular optical paths 410L to 440L. Moreover, the laser with its broadened pulse width exits from the pulse stretcher 400 and travels to 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 reflected in the Z direction by the high-reflectivity mirror 157 and travels to the beam splitter 171.

[0102] A portion of the laser beam that travels to the beam splitter 171 passes through the beam splitter 171 and the emission window 173 and travels to the exposure device 200, while another portion is reflected by the beam splitter 171 and travels to the photosensor 172.

[0103] Optical sensor 172 measures the energy E of the received laser. Optical sensor 172 outputs a signal representing the measured energy E to processor 190. Processor 190 performs feedback control on the charging voltage of chargers 41 and 341 to ensure that the difference ΔE between energy E and the target energy Et is within an acceptable range.

[0104] 2.3 Research Topic

[0105] The pulse stretcher 400 includes beam splitters 410B to 440B as optical elements, surrounding mirrors 411 to 414, 421 to 428, 431 to 438, 441 to 452, and light guide mirrors 402 and 403, and has four annular optical paths 410L to 440L. These optical elements need to be replaced as they deteriorate. For example, among the various annular optical paths 410L to 440L, the beam splitters 410B to 440B deteriorate faster than the surrounding mirrors 411 to 414, 421 to 428, 431 to 438, and 441 to 452. This is because the beam splitters 410B to 440B repeatedly transmit and reflect laser light. In addition, in the direction of laser travel, optical elements located upstream tend to deteriorate more easily. This is because the pulse width of the upstream laser is narrower than that of the downstream laser, and the intensity of the upstream laser is higher than that of the downstream laser. Thus, the degradation rate varies depending on the type and configuration of the optical components; those with faster degradation rates require more frequent replacement. Therefore, it is necessary to make the replacement of frequently replaced optical components easy, and to simplify maintenance.

[0106] Therefore, in the following embodiments, a gas laser device that can be easily maintained is illustrated.

[0107] 3. Description of the gas laser device in Embodiment 1

[0108] 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.

[0109] 3.1 Structure

[0110] 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 plurality of modules having two or more optical elements, wherein the two or more optical elements include at least one of the beam splitters 410B to 440B, the surround mirrors 411 to 414, 421 to 428, 431 to 438, 441 to 452, and the beam splitters and mirrors 402 and 403.

[0111] 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 of this embodiment, viewed from an obliquely upward view. Figure 6 This is a schematic diagram illustrating multiple modules and the housing 110 of this embodiment. Figure 6 In the diagram, the first main body portion 111 and the second main body portion 112 of the housing 110 are indicated by dashed lines, and the description of the maintenance plate 116 is omitted. (See diagram below.) Figure 5 , Figure 6 As shown, in this embodiment, each annular optical path 410L to 440L is configured as a module, and the pulse stretcher 400 includes four modules 10U, 20U, 30U, and 40U. Module 10U includes an annular optical path 410L, module 20U includes an annular optical path 420L, module 30U includes an annular optical path 430L, and module 40U includes an annular optical path 440L. These modules 10U to 40U can individually enter and exit through the opening 114h of the second main body 112. Furthermore, the second main body 112 is equipped with four moving mechanisms 117a to 117d. Figure 6 In the middle, the second main body 112 is represented by a dashed line.

[0112] Figure 7 This is a schematic diagram illustrating a schematic structural example of module 10U according to this embodiment. Figure 7 As shown, module 10U has a beam splitter 410B and surround mirrors 411-414 as optical elements constituting the ring optical path 410L, and a frame 11U as its main structures. Therefore, module 10U has a total of 5 optical elements.

[0113] The frame 11U is a component that supports the beam splitter 410B and the surrounding mirrors 411-414. In this embodiment, the frame 11U is quadrilateral in shape and is a frame-like component that surrounds the beam splitter 410B and the surrounding mirrors 411-414. The beam splitter 410B is fixed to the bracket 12U fixed to the frame 11U with its tilt angle adjusted. The surrounding mirrors 411-414 are fixed to the brackets 13Ua-13Ud fixed to the frame 11U with their tilt angles adjusted, respectively. Thus, the beam splitter 410B and the surrounding mirrors 411-414 are supported by the frame 11U. Furthermore, the frame 11U is only required to support the beam splitter 410B and the surrounding mirrors 411-414; there are no limitations. For example, if the laser beam path intersects with the frame 11U, a through-hole for the laser beam to pass through can be formed in the frame 11U.

[0114] Although the illustrations are omitted, module 20U has a main structure comprising a beam splitter 420B and surrounding mirrors 421-428, which are optical elements constituting the annular optical path 420L, as well as a frame (not shown). Therefore, module 20U has a total of nine optical elements. The frame structure of module 20U is the same as that of frame 11U of module 10U. Like beam splitter 410B and surrounding mirrors 411-414, beam splitter 420B and surrounding mirrors 421-428 are supported by the frame with their respective tilt angles adjusted.

[0115] Furthermore, module 30U comprises a beam splitter 430B and surrounding mirrors 431-438, which serve as optical elements constituting the annular optical path 430L, as well as a frame (not shown) as its main structure. Therefore, module 30U has a total of nine optical elements. The frame structure of module 30U is the same as that of frame 11U of module 10U. The beam splitter 430B and surrounding mirrors 431-438 are supported by the frame with their respective tilt angles adjusted.

[0116] Furthermore, module 40U comprises a beam splitter 440B and surrounding mirrors 441-452, which serve as optical elements constituting the annular optical path 440L, as well as a frame (not shown) as its main structure. Therefore, module 40U has 13 optical elements. The frame structure of module 40U is the same as that of frame 11U of module 10U. The beam splitter 440B and surrounding mirrors 441-452 are supported by the frame with their respective tilt angles adjusted.

[0117] As described above, the annular optical path 440L is located further towards the -H direction than the annular optical path 410L, and the annular optical path 410L and the annular optical path 440L overlap each other in a direction parallel to the H direction. Therefore, as Figure 6As shown, module 10U is located closer to the opening 114h than module 40U, and module 10U overlaps with module 40U in a direction parallel to the opening direction of opening 114h. Furthermore, in the laser's travel direction, module 10U is positioned further upstream than module 40U. Therefore, the degradation rate of at least beam splitter 410B in the optical elements of module 10U is faster than the degradation rate of the optical elements, namely beam splitter 440B, in module 40U. Therefore, if module 10U is designated as the first module and module 40U as the second module, the degradation rate of at least one optical element in the first module is faster than the degradation rate of the optical element in the second module, which is located on the opposite side of the opening 114h from the first module.

[0118] Furthermore, as described above, the annular optical path 430L is located further towards the -H direction than the annular optical path 420L, and the annular optical paths 420L and 430L overlap in a direction parallel to the H direction. Therefore, module 20U is located further towards the opening 114h than module 30U, and module 20U overlaps with module 30U in a direction parallel to the opening direction of the opening 114h. Additionally, in the laser's travel direction, module 20U is positioned further upstream than module 30U. Therefore, the degradation rate of at least the beam splitter 420B among the optical elements in module 20U is faster than the degradation rate of the optical elements, i.e., the beam splitter 430B, in module 30U. Therefore, if module 20U is designated as the first module and module 30U as the second module, the degradation rate of at least one optical element in the first module is faster than the degradation rate of the optical element in the second module, which is located on the opposite side of the opening 114h from the first module.

[0119] These modules 10U to 40U are held by moving mechanisms 117a to 117d. Specifically, modules 10U and 40U are held by moving mechanisms 117a and 117b, and modules 20U and 30U are held by moving mechanisms 117c and 117d. Moving mechanisms 117a and 117b allow modules 10U and 40U to move in and out through opening 114h. Moving mechanisms 117a and 117b are, for example, composed of tracks extending in a direction parallel to the H direction, and the direction of movement of the held modules 10U and 40U is parallel to the H direction, which is horizontal. Modules 10U and 40U held by moving mechanisms 117a and 117b are positioned in a direction parallel to the H direction by positioning mechanisms (not shown) composed of pins, V-grooves, etc., and are fixed by fixing mechanisms (not shown) such as bolts.

[0120] The moving mechanisms 117c and 117d enable modules 20U and 30U to move through the opening 114h. Similar to moving mechanisms 117a and 117b, moving mechanisms 117c and 117d are, for example, constructed from tracks extending in a direction parallel to the H direction. The moving direction of the modules 20U and 30U held by the moving mechanisms 117c and 117d is parallel to the H direction, which is horizontal. The modules 20U and 30U held by the moving mechanisms 117c and 117d are positioned in a direction parallel to the H direction by positioning mechanisms (not shown) consisting of pins, V-grooves, etc., and are fixed by fixing mechanisms (not shown) such as bolts.

[0121] 3.2 Maintenance methods for pulse stretchers

[0122] Next, the maintenance method of the pulse stretcher 400 in Embodiment 1 will be described.

[0123] In this embodiment, the maintenance time for each module 10U to 40U is predetermined. This time is determined, for example, by the number of pulsed laser shots emitted from the gas laser device 100. The processor 190 counts the number of shots, and when a module reaches the required number of shots for maintenance, the display unit 180 displays the name of that module. The operator performs maintenance on the displayed module. The frequency of maintenance for module 10U is higher than that for module 40U, and the frequency of maintenance for module 20U is higher than that for module 30U.

[0124] In this embodiment, the number of ejections is the same when maintaining modules 10U and 20U, while the number of ejections is twice that when maintaining modules 30U and 40U. Therefore, maintenance of modules 10U and 20U is performed simultaneously, as is maintenance of modules 30U and 40U. Furthermore, maintenance of modules 10U and 20U is also performed while maintenance of modules 30U and 40U is being conducted.

[0125] Furthermore, the maintenance times for modules 10U and 20U can differ, as can the maintenance times for modules 30U and 40U. Additionally, the maintenance times can be determined by factors other than the number of emission cycles, such as the operating time of the gas laser device 100.

[0126] First, the maintenance of modules 10U and 20U will be explained. The operator stops the operation of the gas laser device 100 and removes the maintenance plate 116 from the second main body 112. Next, the fixing mechanism of module 10U is released, and module 10U is taken out from the second main body 112 through opening 114h via moving mechanisms 117a and 117b, and the optical elements of module 10U are replaced. Alternatively, some or all of the optical elements of module 10U can be replaced. Alternatively, the removed module 10U can be replaced with a new module 10U. Similarly, module 20U is removed and its optical elements or module 20U is replaced in the same manner as module 10U. Next, module 10U is stored in the storage space of the second main body 112 through opening 114h using moving mechanisms 117a and 117b, positioned using a positioning mechanism, and fixed using a fixing mechanism. Furthermore, module 20U is stored in the storage space of the second main body 112, positioned using a positioning mechanism, and fixed using a fixing mechanism. Next, after the maintenance plate 116 is installed into the second main body 112 and the opening 114h is blocked, the gas laser device 100 is operated. Here, modules 10U and 20U can be removed and stored separately, so the order in which modules 10U and 20U are removed and stored is not necessarily as described above.

[0127] Next, the maintenance of modules 30U and 40U will be explained. Similar to the maintenance of modules 10U and 20U, the operator stops the operation of the gas laser device 100 and removes the maintenance plate 116 from the second main body 112. Then, module 10U is removed from the second main body 112 through opening 114h. Next, the fixing mechanism securing module 40U is released, and module 40U is removed from the second main body 112 through opening 114h via moving mechanisms 117a and 117b. Similarly, regarding modules 20U and 30U, after removing module 20U from the second main body 112, module 30U is also removed.

[0128] Next, the optical element of the removed module 40U is replaced, or the module 40U itself is replaced. Similarly, the optical element of the removed module 30U is replaced, or the module 30U itself is replaced. Furthermore, modules 30U and 40U are stored in the storage space of the second main body 112, positioned using a positioning mechanism, and fixed using a fixing mechanism.

[0129] As described above, the number of shots fired during maintenance of modules 30U and 40U is twice the number fired during maintenance of modules 10U and 20U. Therefore, the optical components of the removed modules 10U and 20U are replaced, or modules 10U and 20U are replaced. Furthermore, modules 10U and 20U are stored in the storage space of the second main body 112, positioned using a positioning mechanism, and fixed using a fixing mechanism. In addition, if modules 10U and 20U are not maintained at the time of maintenance of modules 30U and 40U, the removed modules 10U and 20U are directly stored and fixed in the storage space of the second main body 112.

[0130] In this way, after the modules 10U, 20U, 30U, and 40U are stored and fixed in the storage space of the second main body 112, the maintenance plate 116 is installed on the second main body 112 to block the opening 114h, so that the gas laser device 100 can be operated.

[0131] 3.3 Functions and Effects

[0132] In the pulse stretcher 400 of this embodiment, modules 10U to 40U have two or more optical elements, including at least one of a beam splitter and a mirror, and can be individually accessed through the opening 114h of the second main body 112 of the housing 110. Therefore, during maintenance, two or more optical elements can be removed at once, making it easier to remove the optical elements compared to removing them one by one from the second main body 112. Furthermore, the degradation rate of at least one optical element in module 10U is faster than the degradation rate of the optical element in module 40U, which is located on the opposite side of module 40U, closer to the opening 114h than module 10U. Therefore, compared to the case where module 40U is located on the side of module 10U closer to the opening 114h than module 10U, it is easier to obtain module 10U with optical elements that tend to be replaced more frequently. Additionally, the degradation rate of at least one optical element in module 20U is faster than the degradation rate of the optical element in module 30U, which is located on the opposite side of module 30U, closer to the opening 114h than module 20U. Therefore, compared to the case where module 30U is located further from the opening 114h than module 20U, module 10U, which has optical elements that tend to be replaced frequently, can be easily obtained. Therefore, the gas laser device 100 according to this embodiment allows for easy replacement of optical elements that require frequent replacement, and facilitates easy maintenance.

[0133] In the pulse stretcher 400 of this embodiment, modules 10U and 40U overlap each other in the direction parallel to the opening direction of the opening 114h, and modules 20U and 30U overlap each other. Therefore, it is possible to suppress the pulse stretcher 400 from becoming too large in the direction perpendicular to the opening direction of the opening 114h. Alternatively, modules 10U and 40U may not overlap each other in the direction parallel to the opening direction of the opening 114h, and modules 20U and 30U may also not overlap each other.

[0134] In the pulse stretcher 400 of this embodiment, each annular optical path 410L to 440L is configured as a module 10U to 40U. Therefore, maintenance of each annular optical path 410L to 440L can be easily performed.

[0135] In the pulse stretcher 400 of this embodiment, the optical elements of module 40U are positioned further downstream than the optical elements of module 10U in the direction of pulsed laser travel, and the number of optical elements in module 10U is less than the number of optical elements in module 40U. Therefore, the pulse width can be broadened before the laser travels to module 40U, which has a larger number of optical elements, thus slowing down the degradation rate of the optical elements in module 40U. This reduces the frequency of maintenance for module 40U, which has a larger number of optical elements, and suppresses the increase in maintenance costs. Alternatively, the number of optical elements in module 10U may also be greater than the number of optical elements in module 40U.

[0136] In the gas laser device 100 of this embodiment, the second main body 112 of the housing 110 includes moving mechanisms 117a to 117d that allow modules 10U to 40U to move in and out through openings 114h. Therefore, it is easy to move modules 10U to 40U in and out. Alternatively, the second main body 112 may not include moving mechanisms 117a to 117d.

[0137] In the gas laser device 100 of this embodiment, the modules 10U to 40U move in a horizontal direction via the moving mechanisms 117a to 117d. Therefore, it is possible to prevent the modules 10U to 40U from accidentally moving due to their own weight when being moved in or out. Alternatively, the moving direction of the modules 10U to 40U via the moving mechanisms 117a to 117d may not be parallel to the horizontal direction.

[0138] The pulse stretcher 400 of this embodiment includes two light guide mirrors 402 and 403, and also has a light guide optical system 401 that sequentially directs the pulsed laser beam into four annular optical paths 410L to 440L. Therefore, compared with the case without the light guide optical system 401, the degree of freedom in the configuration of the four annular optical paths 410L to 440L can be increased.

[0139] 4. Description of the gas laser device in Embodiment 2

[0140] 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 drawings, parts have been omitted or simplified for ease of observation.

[0141] 4.1 Structure

[0142] The pulse stretcher 400 of this embodiment differs from the pulse stretcher 400 of the comparative example mainly in that it consists of 6 modules.

[0143] Figure 8 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 of this embodiment, viewed from an obliquely upward view. Figure 9 Is with Figure 6 Similarly, schematic diagrams of multiple modules and housing 110 of this embodiment are shown. Figure 8 , Figure 9 As shown, the pulse stretcher 400 of this embodiment includes six modules 10U, 20U, 30U, 40U, 50U, and 60U. These modules 10U to 60U can individually enter and exit through the opening 114h of the second main body 112. In addition, the second main body 112 of this modified example has six moving mechanisms 117a to 117f.

[0144] Module 10U comprises optical elements forming part of the annular optical path 410L, namely surround mirrors 411 and 413; optical elements forming part of the annular optical path 420L, namely surround mirrors 421, 423, 425, and 427; and a frame (not shown) as its main structure. Therefore, module 10U has a total of six optical elements. The surround mirrors 411, 413, 421, 423, 425, and 427 are located further to the Z-direction side than the light guide mirrors 402 and 403. The surround mirrors 411, 413, 421, 423, 425, and 427 are supported by the frame with their respective tilt angles adjusted.

[0145] Module 20U comprises, as its main structure, surrounding mirrors 431, 433, 435, and 437, which are optical elements forming part of the annular optical path 430L; surrounding mirrors 442, 444, 446, 448, 450, and 452, which are optical elements forming part of the annular optical path 440L; and a frame (not shown). Therefore, module 20U has 10 optical elements. The surrounding mirrors 431, 433, 435, 437, 442, 444, 446, 448, 450, and 452 are located further to the Z-direction side than the light guide mirrors 402 and 403. The surrounding mirrors 431, 433, 435, 437, 442, 444, 446, 448, 450, and 452 are supported by the frame with their respective tilt angles adjusted.

[0146] Module 30U comprises beam splitters 410B to 440B in the annular optical paths 410L to 440L, light guide mirrors 402 and 403, and a frame (not shown) as its main structure. Therefore, module 30U has a total of six optical elements. The beam splitters 410B to 440B and the light guide mirrors 402 and 403 are supported by the frame with their respective tilt angles adjusted. Furthermore, if a module including all beam splitters and all light guide mirrors is designated as a third module, then module 30U is a third module.

[0147] Module 40U has optical elements constituting another part of the annular optical path 410L, namely the surrounding mirrors 412 and 414, and a frame (not shown) as its main structure. Therefore, module 40U has two optical elements. The surrounding mirrors 412 and 414 are located further towards the -Z direction than the light guide mirrors 402 and 403. The surrounding mirrors 412 and 414 are supported by the frame with their respective tilt angles adjusted.

[0148] Module 50U comprises, as its main structure, surrounding mirrors 422, 424, 426, and 428, which are optical elements constituting another part of the annular optical path 420L, and a frame (not shown). Therefore, module 50U has four optical elements. The surrounding mirrors 422, 424, 426, and 428 are located further towards the -Z direction than the light guide mirrors 402 and 403. The surrounding mirrors 422, 424, 426, and 428 are supported by the frame with their tilt angles adjusted.

[0149] Module 60U comprises the following main components: optical elements constituting another part of the annular optical path 430L, namely, surround lenses 432, 434, 436, and 438; optical elements constituting another part of the annular optical path 440L, namely, surround lenses 441, 443, 445, 447, 449, and 451; and a frame (not shown). Therefore, module 60U has 10 optical elements. Surround lenses 432, 434, 436, 438, 441, 443, 445, 447, 449, and 451 are located further towards the -Z direction than light guide lenses 402 and 403. Surround lenses 432, 434, 436, 438, 441, 443, 445, 447, 449, and 451 are supported by the frame with their respective tilt angles adjusted.

[0150] In this embodiment, module 10U is located further from the opening 114h than module 20U, and module 10U overlaps with module 20U in a direction parallel to the opening direction of opening 114h. Furthermore, in the laser's travel direction, the annular optical paths 430L and 440L are positioned further downstream than the annular optical paths 410L and 420L. Therefore, the degradation rate of the surrounding mirrors 411, 413, 421, 423, 425, and 427, which are all optical elements of module 10U, is faster than the degradation rate of the surrounding mirrors 431, 433, 435, 437, 442, 444, 446, 448, 450, and 452, which are all optical elements of module 20U. Therefore, if module 10U is designated as the first module and module 20U is designated as the second module, the degradation rate of at least one optical element of the first module is faster than the degradation rate of the optical element of the second module located on the opposite side of the opening 114h, which is closer to the first module.

[0151] Furthermore, modules 40U and 50U are located closer to the opening 114h than module 60U, and overlap with module 60U in a direction parallel to the opening direction of opening 114h. Additionally, in the laser's travel direction, the annular optical paths 430L and 440L are positioned further downstream than the annular optical paths 410L and 420L. Therefore, the degradation rate of all optical elements in module 40U (i.e., the surrounding mirrors 412 and 414) and all optical elements in module 50U (i.e., the surrounding mirrors 422, 424, 426, and 428) is faster than that of all optical elements in module 60U (i.e., the surrounding mirrors 432, 434, 436, 438, 441, 443, 445, 447, 449, and 451). Therefore, if modules 40U and 50U are designated as the first module and module 60U is designated as the second module, the degradation rate of at least one optical element of the first module is faster than the degradation rate of the optical element of the second module, which is located on the opposite side of the opening 114h, which is closer to the first module.

[0152] These modules 10U to 60U are held by moving mechanisms 117a to 117f. Specifically, modules 10U and 20U are held by moving mechanisms 117a and 117b. Module 30U is held by moving mechanisms 117c and 117d. Module 40U is held by moving mechanism 117e. Module 50U is held by moving mechanism 117f. Module 60U is held by moving mechanisms 117e and 117f. Moving mechanisms 117a and 117b allow modules 10U and 20U to move through opening 114h. Moving mechanisms 117c and 117d allow module 30U to move through opening 114h. Moving mechanism 117e allows module 40U to move through opening 114h, and moving mechanism 117f allows module 50U to move through opening 114h. Furthermore, the moving mechanisms 117e and 117f enable the module 60U to move in and out through the opening 114h. Similar to the moving mechanisms 117a to 117d in Embodiment 1, the moving mechanisms 117a to 117f are, for example, constructed from a track extending in a direction parallel to the H direction, and the moving direction of the modules 10U to 60U is horizontal. Furthermore, similar to the modules 10U to 40U in Embodiment 1, the modules 10U to 60U are positioned in a direction parallel to the H direction using a positioning mechanism (not shown) composed of pins, V-grooves, etc., and fixed using a fixing mechanism (not shown) such as bolts.

[0153] 4.2 Maintenance methods for pulse stretchers

[0154] Next, the maintenance method of the pulse stretcher 400 in Embodiment 2 will be described.

[0155] In this embodiment, similar to embodiment 1, the maintenance time for each module 10U to 60U is predetermined, and this time is determined by the number of pulse laser emanations. The maintenance frequency of module 10U is higher than that of module 20U, and the maintenance frequency of modules 40U and 50U is higher than that of module 60U.

[0156] In this embodiment, the number of injection attempts is the same when maintaining modules 10U, 30U, 40U, and 50U, while the number of injection attempts when maintaining modules 20U and 60U is twice that when maintaining modules 10U, 30U, 40U, and 50U. Therefore, maintenance of modules 10U, 30U, 40U, and 50U is performed simultaneously, as is maintenance of modules 20U and 60U. Furthermore, maintenance of modules 10U, 30U, 40U, and 50U is also performed during the maintenance of modules 20U and 60U.

[0157] First, the maintenance of modules 10U, 30U, 40U, and 50U will be explained. Similar to the maintenance of modules 10U and 20U in Embodiment 1, the operator stops the operation of the gas laser device 100 and removes the maintenance plate 116 from the second main body 112. Next, the fixing mechanisms securing modules 10U, 30U, 40U, and 50U are released. Modules 10U, 30U, 40U, and 50U are removed from the second main body 112 via the moving mechanisms 117a to 117f through the opening 114h, and the optical elements of modules 10U, 30U, 40U, and 50U are replaced. Alternatively, some or all of the optical elements of modules 10U, 30U, 40U, and 50U can be replaced. Alternatively, the removed modules 10U, 30U, 40U, and 50U can be replaced with new modules 10U, 30U, 40U, and 50U. Next, modules 10U, 30U, 40U, and 50U are stored in the storage space of the second main body 112 via the moving mechanisms 117a to 117f through the opening 114h, positioned using a positioning mechanism, and fixed using a fixing mechanism. After blocking the opening 114h with the maintenance plate 116, the gas laser device 100 is operated.

[0158] Next, the maintenance of modules 20U and 60U will be explained. Similar to the maintenance of modules 10U, 30U, 40U, and 50U, the operator stops the operation of the gas laser device 100 and removes the maintenance plate 116 from the second main body 112. Furthermore, as described above, modules 10U, 30U, 40U, and 50U are removed from the second main body 112. Next, the fixing mechanisms securing modules 20U and 60U are released, and modules 20U and 60U are removed from the second main body 112 through opening 114h via moving mechanisms 117a, 117b, 117e, and 117f. The optical elements of the removed modules 20U and 60U are replaced, or the modules 20U and 60U are replaced. Furthermore, modules 20U and 60U are stored in the storage space of the second main body 112, positioned using a positioning mechanism, and fixed using a fixing mechanism.

[0159] In this embodiment, the optical components of modules 10U, 30U, 40U, and 50U are replaced, or the modules 10U, 30U, 40U, and 50U are replaced, and these modules 10U, 30U, 40U, and 50U are stored and fixed in the storage space of the second main body 112. Furthermore, if modules 10U, 30U, 40U, and 50U are not maintained when maintaining modules 20U and 60U, the removed modules 10U, 30U, 40U, and 50U are directly stored and fixed in the storage space of the second main body 112.

[0160] In this way, after storing and fixing the modules 10U to 60U in the storage space of the second main body 112, the maintenance plate 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.

[0161] 4.3 Functions and Effects

[0162] In a ring optical path, the beam splitter undergoes multiple reflections and transmissions of the pulsed laser, thus its degradation rate is faster than that of the mirror. In the pulse stretcher 400 of this embodiment, module 30U includes all beam splitters 410B to 440B. Therefore, multiple beam splitters 410B to 440B with such rapid degradation rates can be replaced simultaneously. Furthermore, from the viewpoint of simultaneously replacing multiple beam splitters, module 30U only needs to include multiple beam splitters. For example, module 30U may also exclude some of the beam splitters.

[0163] In the pulse stretcher 400 of this embodiment, module 30U 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, module 30U may not include at least one of the light guide mirrors 402 and 403.

[0164] 4.4 Explanation of Variation Example 1

[0165] Next, a variation 1 of the gas laser device 100 of Embodiment 2 will be described. Figure 10 Is with Figure 6 Similarly, schematic diagrams of multiple modules and housing 110 of this modified example are shown. Figure 10 As shown, the main difference between the pulse stretcher 400 of this modified example and the pulse stretcher 400 of embodiment 2 is that the module 30U is divided into two modules 30Ua and 30Ub.

[0166] Module 30Ua mainly includes beam splitters 410B and 420B in the annular optical paths 410L and 420L, a light guide mirror 402, and a frame (not shown). Beam splitters 410B and 420B, and the light guide mirror 402 are located further H-direction than the optical axis of the laser passing through the output coupling mirror 370. Beam splitters 410B and 420B, and the light guide mirror 402 are supported by the frame with their respective tilt angles adjusted.

[0167] Module 30Ub comprises beam splitters 430B and 440B in the annular optical paths 430L and 440L, a light guide mirror 403, and a frame (not shown) as its main structure. The beam splitters 430B and 440B, and the light guide mirror 403 are located further towards the -H direction than the optical axis of the laser passing through the output coupling mirror 370. The beam splitters 430B and 440B, and the light guide mirror 403 are supported by the frame with their respective tilt angles adjusted. Furthermore, if a module including multiple beam splitters is designated as a third module, then modules 30Ua and 30Ub are third modules.

[0168] In this modified example, module 30Ua is located closer to the opening 114h than module 30Ub, and module 30Ua overlaps with module 30Ub in a direction parallel to the opening direction of opening 114h. Furthermore, in the laser's travel direction, the annular optical paths 430L and 440L are positioned further downstream than the annular optical paths 410L and 420L. Therefore, the beam splitters 410B and 420B, which are optical elements of module 30Ua, degrade faster than the beam splitters 430B and 440B, which are optical elements of module 30Ub. Therefore, if module 30Ua is designated as the first module and module 30Ub as the second module, the deterioration rate of at least one optical element of the first module is faster than the deterioration rate of the optical element of the second module, which is located on the opposite side of the opening 114h from the first module.

[0169] In this variant, module 30Ua is maintained together with modules 10U, 40U, and 50U, and modules 30Ua and 30Ub are maintained together with modules 10U, 20U, 40U, 50U, and 60U.

[0170] According to the gas laser device 100 of this modified example, compared with the case where module 30Ub is located on the side closer to the opening 114h than module 30Ua, it is easier to obtain module 30Ua which has optical elements that tend to be replaced frequently.

[0171] 4.5 Explanation of Variation Example 2

[0172] Next, a modified example 2 of the gas laser device 100 of Embodiment 2 will be described. Figure 11 This is a schematic diagram showing multiple modules and the housing 110 of this modified example. (See attached diagram.) Figure 11 As shown, the main difference between the gas laser device 100 of this modified example and the gas laser device 100 of Embodiment 2 is that three openings 114ha, 114hb, and 114hc are formed in the second main body 112, and the housing 110 has three maintenance plates 116a, 116b, and 116c.

[0173] In this modified example, modules 10U and 20U overlap with opening 114ha in a direction parallel to the H direction, allowing entry and exit through opening 114ha. Module 30U overlaps with opening 114hb in a direction parallel to the H direction, allowing entry and exit through opening 114hb. Modules 40U, 50U, and 60U overlap with opening 114hc in a direction parallel to the H direction, allowing entry and exit through opening 114hc.

[0174] Maintenance plate 116a is a plate-shaped component that blocks opening 114ha, maintenance plate 116b is a plate-shaped component that blocks opening 114hb, and maintenance plate 116c is a plate-shaped component that blocks opening 114hc. Maintenance plates 116a, 116b, and 116c are detachably mounted on the second main body 112.

[0175] According to the gas laser device 100 of this modified example, compared with the case where the modules 10U to 60U are allowed to enter and exit through one opening during maintenance, the storage space of the second main body 112 exposed to the outside can be reduced, making it difficult for dust and other contaminants to enter the storage space.

[0176] The above description uses the above-described embodiments as examples, but this disclosure is not limited thereto and can be appropriately modified.

[0177] In the above-described embodiment 1, a pulse stretcher 400 comprising four modules 10U to 40U was used as an example. However, as long as the pulse stretcher 400 includes multiple modules, each module having at least two optical elements, including at least one of a beam splitter and a mirror, and capable of entering and exiting independently from the opening 114h, the multiple modules include a first module and a second module located on the opposite side of the opening 114h, and the degradation rate of at least one optical element in the first module is faster than the degradation rate of the optical element in the second module. For example, in the pulse stretcher 400 of embodiment 1, a first module composed of modules 10U and 20U and a second module composed of modules 30U and 40U may also be formed.

[0178] Furthermore, in the embodiments described above, a pulse stretcher 400 having four annular optical paths 410L to 440L was used as an example. However, the number of annular optical paths can be multiple.

[0179] Furthermore, in the above embodiments, the following examples were described: 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. However, the number of surrounding mirrors constituting the ring optical path is not limited. Moreover, it is preferable that the ring optical path is positioned downstream of the pulsed laser's travel direction, with a greater number of surrounding mirrors.

[0180] Furthermore, in the embodiments described above, a light-guiding optical system 401 consisting of two light-guiding mirrors 402 and 403 has been used as an example. However, the number of light-guiding mirrors constituting the light-guiding optical system 401 is not limited. Additionally, the pulse stretcher 400 may not include the light-guiding optical system 401.

[0181] Furthermore, in the above embodiments, the first light guide unit 150, which includes high-reflectivity mirrors 151 and 152, and the second light guide unit 155, which includes two high-reflectivity mirrors 156 and 157, have been described as examples. However, as long as the structure is such that the laser emitted from the chamber device CH3 is 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 also exclude at least one of the first light guide unit 150 and the second light guide unit 155.

[0182] Furthermore, in the embodiments described above, 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 configuration 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. In addition, the opening direction of the opening 114h is not limited. For example, the opening 114h may also be formed in the upper wall 115 of the second main body 112.

[0183] Furthermore, in the embodiments described above, beam splitters 410B to 440B, which propagate reflected laser light into the annular optical paths 410L to 440L, have been used as examples. However, it is also possible for laser light passing through beam splitters 410B to 440B to propagate into the annular optical paths 410L to 440L. In this case, 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 beam splitters 410B to 440B.

[0184] Furthermore, in the embodiments described above, a gas laser device 100 equipped with a laser oscillator 130 and an amplifier 160 has been used as an example. However, the gas laser device 100 may also be without the amplifier 160. In this case, for example, the laser emitted from the chamber device CH1 and passing through the output coupling mirror 70 is incident on the pulse stretcher 400.

[0185] The foregoing description is not limiting but merely illustrative. Therefore, modifications to the embodiments of this disclosure can be made without departing from the claims, as will be apparent to those skilled in the art. Furthermore, it will be apparent to those skilled in the art that embodiments of this disclosure can be used in combination. Unless otherwise expressly stated, all terms used in this specification and claims should be interpreted as “non-limiting” terms. For example, terms such as “comprising,” “having,” “possessing,” and “comprise” should be interpreted as “not excluding the presence of constituent elements other than those described.” Additionally, the modifier “a” should be interpreted as “at least one” or “one or more.” Furthermore, terms such as “at least one of A, B, and C” should be interpreted as “A,” “B,” “C,” “A+B,” “A+C,” “B+C,” or “A+B+C,” and should also be interpreted as including combinations thereof with content other than “A,” “B,” and “C.”

Claims

1. A gas laser device, wherein, The gas laser device includes: A chamber device that emits pulsed laser light; A pulse stretcher having multiple annular optical paths that stretch the pulse width of the pulsed laser; and The housing includes a main body that houses the pulse stretcher and has an opening for the pulse stretcher to enter and exit. The annular optical path includes: a beam splitter, to which the pulsed laser is incident; and a plurality of surrounding mirrors, which sequentially reflect a portion of the pulsed laser incident on the beam splitter and return it to the beam splitter to overlap with another portion of the pulsed laser. The pulse stretcher comprises multiple modules, each module having two or more optical elements including at least one of the beam splitter and the surrounding mirror, and each module can be individually accessed through the opening. The plurality of modules includes a first module and a second module located on the opposite side of the opening, which is further away from the first module. The degradation rate of at least one optical element in the first module is faster than that of the optical element in the second module.

2. The gas laser device according to claim 1, wherein, The first module and the second module overlap each other in a direction parallel to the opening direction of the opening.

3. The gas laser device according to claim 1, wherein, The optical element of the second module is positioned further downstream than the optical element of the first module in the direction of travel of the pulsed laser.

4. The gas laser device according to claim 3, wherein, The number of optical elements in the first module is less than the number of optical elements in the second module.

5. The gas laser device according to claim 1, wherein, The housing also includes a moving mechanism that allows the module to move in and out through the opening.

6. The gas laser device according to claim 5, wherein, The module moves horizontally via the moving mechanism.

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

8. The gas laser device according to claim 1, wherein, At least one of the plurality of modules includes the beam splitter and the surround mirror.

9. The gas laser device according to claim 8, wherein, Each of the aforementioned ring optical paths is configured as the module.

10. The gas laser device according to claim 1, wherein, The plurality of modules includes a third module, and the third module includes a plurality of the beam splitters.

11. The gas laser device according to claim 10, wherein, The third module includes all of the aforementioned beam splitters.

12. The gas laser device according to claim 1, wherein, The pulse stretcher also has a light-guiding optical system, which includes a plurality of light-guiding mirrors that serve as optical elements other than the beam splitter and the surrounding mirror. The light-guiding optical system allows the pulsed laser to be sequentially incident on the beam splitter of the plurality of annular optical paths.

13. The gas laser device according to claim 12, wherein, The plurality of modules includes a third module, which includes at least one of the light guide mirrors.

14. The gas laser device according to claim 13, wherein, The third module includes all of the light guide mirrors.

15. A method for manufacturing an electronic device, wherein, The method for manufacturing the electronic device includes 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 includes: A chamber device that emits pulsed laser light; A pulse stretcher having multiple annular optical paths that stretch the pulse width of the pulsed laser; and The housing includes a main body that houses the pulse stretcher and has an opening for the pulse stretcher to enter and exit. The annular optical path includes: a beam splitter, to which the pulsed laser is incident; and a plurality of surrounding mirrors, which sequentially reflect a portion of the pulsed laser incident on the beam splitter and return it to the beam splitter to overlap with another portion of the pulsed laser. The pulse stretcher comprises multiple modules, each module having two or more optical elements including at least one of the beam splitter and the surrounding mirror, and each module can be individually accessed through the opening. The plurality of modules includes a first module and a second module located on the opposite side of the opening, which is further away from the first module. The degradation rate of at least one optical element in the first module is faster than that of the optical element in the second module.

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