Gas laser device and method for manufacturing electronic device

Abstract

A gas laser apparatus and a method of manufacturing an electronic device are provided. This gas laser device is provided with: a cavity device that includes a pair of electrodes in an internal space in which a laser gas is sealed, and that emits pulsed laser light; and a pulse stretcher including a ring-shaped optical path configured from a beam splitter and a plurality of reflectors, and a light guide optical system including a plurality of light guide reflectors, the light guide optical system being configured so that the pulse laser light incident on the pulse stretcher is emitted from the pulse stretcher via the beam splitter, the ring-shaped optical path being configured so that the ring-shaped optical path is configured so that the ring-shaped optical path is configured so that the ring-shaped optical path is configured so that the ring-shaped optical path is configured so that the ring-shaped optical path is configured so that the ring-shaped optical path is configured so that the ring-shaped optical path is separated from the ring-shaped optical path. And a ring-shaped optical path disposed between a first straight line along the input optical path and a second straight line along the output optical path, the ring-shaped optical path being disposed between the first straight line along the input optical path and the second straight line along the output optical path, and the ring-shaped optical path being disposed between the first straight line along the input optical path and the second straight line along the output optical path. The input light path is a light path of pulse laser emitted to the pulse stretcher, and the output light path is a light path of pulse laser emitted from the pulse stretcher.

Description

Technical Field

[0001] The present disclosure relates to a gas laser device and a method for manufacturing an electronic device. Background Art

[0002] In recent years, semiconductor exposure equipment has been required to achieve higher resolution as semiconductor integrated circuits become increasingly miniaturized and highly integrated. Consequently, there has been a trend toward shorter wavelengths of light emitted from exposure light sources. For example, gas lasers used for exposure include KrF excimer lasers, which output laser light with a wavelength of approximately 248 nm, and ArF excimer lasers, which output laser light with a wavelength of approximately 193 nm.

[0003] The spectral line width of the natural oscillation light of KrF excimer laser devices and ArF excimer laser devices is relatively wide, ranging from 350pm to 400pm. Therefore, when a projection lens is constructed using a material that transmits ultraviolet light such as KrF and ArF laser light, chromatic aberration may sometimes occur. As a result, the resolution may be reduced. Therefore, it is necessary to narrow the spectral line width of the laser light output from the gas laser device to a level that can eliminate chromatic aberration. Therefore, in order to narrow the spectral line width, a narrowing module (Line Narrowing Module: LNM) containing narrowing elements (etalon, grating, etc.) is sometimes included in the laser resonator of the gas laser device. Hereinafter, a gas laser device with a narrowed spectral line width is referred to as a narrowed gas laser device.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent Application Publication No. 2022 / 0393420

[0007] Patent Document 2: U.S. Patent No. 6,238,063 Summary of the Invention

[0008] A gas laser device according to one embodiment of the present invention may also include: a cavity device, which includes a pair of electrodes in an internal space sealed with laser gas and emits pulsed laser light; and a pulse stretcher, which includes a ring light path and a light-guiding optical system, the ring light path being composed of a beam splitter and a plurality of reflection mirrors, the light-guiding optical system including a plurality of light-guiding reflection mirrors, the light-guiding optical system being configured so that the pulsed laser light incident on the pulse stretcher is emitted from the pulse stretcher via the beam splitter, the ring light path being configured so that a portion of the pulsed laser light incident on the beam splitter is returned to the beam splitter via a plurality of reflection mirrors, thereby overlapping with another portion of the pulsed laser light incident on the beam splitter, the ring light path being configured so as to be between a first straight line along an input light path and a straight line along an output light path, the input light path being the light path of the pulsed laser light incident on the pulse stretcher, and the output light path being the light path of the pulsed laser light emitted from the pulse stretcher.

[0009] The manufacturing method of an electronic device according to one embodiment of the present invention may also include the following steps: outputting a pulse laser generated by a gas laser device to an exposure device, exposing the pulse laser output to the exposure device on a photosensitive substrate in the exposure device to manufacture the electronic device, wherein the gas laser device comprises: a cavity device, which includes a pair of electrodes in an internal space sealed with laser gas and emits pulse laser; and a pulse stretcher, which includes an annular light path and a light-guiding optical system, wherein the annular light path is composed of a beam splitter and a plurality of reflectors, and the light-guiding optical system includes a plurality of reflectors for guiding light. The light-guiding optical system is constructed so that the pulse laser incident on the pulse stretcher is emitted from the pulse stretcher via the beam splitter, and the annular optical path is constructed so that a part of the pulse laser incident on the beam splitter is returned to the beam splitter via a plurality of reflection mirrors, thereby overlapping with another part of the pulse laser incident on the beam splitter. The annular optical path is configured to be between a first straight line along an input optical path, which is the optical path of the pulse laser incident on the pulse stretcher, and a second straight line along an output optical path, wherein the input optical path is the optical path of the pulse laser incident on the pulse stretcher, and the output optical path is the optical path of the pulse laser emitted from the pulse stretcher. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Several embodiments of the present disclosure are described below by way of example only with reference to the accompanying drawings.

[0011] Figure 1 This is a schematic diagram showing an overall schematic configuration example of an electronic device manufacturing apparatus used in an exposure process of the electronic device.

[0012] Figure 2 It is a schematic diagram showing an overall schematic configuration example of a gas laser device according to a comparative example.

[0013] Figure 3 It is a schematic diagram showing a schematic configuration example of a first light guiding unit, a second light guiding unit, and a pulse stretcher according to a comparative example, as viewed obliquely from above.

[0014] Figure 4 This is a schematic diagram showing a schematic structural example of a housing of a pulse stretcher according to a comparative example, viewed obliquely from below.

[0015] Figure 5 Schematic diagram showing a schematic configuration example of a sub-pulse stretcher according to a comparative example.

[0016] Figure 6 It is a schematic diagram showing a schematic structural example of a casing of a comparative example.

[0017] Figure 7 is with Figure 3 Similarly, a diagram showing a schematic configuration example of the first light guiding unit, the second light guiding unit, and the pulse stretcher according to the first embodiment is shown.

[0018] Figure 8 This is a schematic diagram showing a schematic configuration example of a housing according to the first embodiment.

[0019] Figure 9 is with Figure 3 Similarly, a diagram showing a schematic configuration example of a first light guiding unit, a second light guiding unit, and a pulse stretcher according to a second embodiment is shown.

[0020] Figure 10 is with Figure 3 Similarly, a diagram showing a schematic configuration example of a first light guiding unit, a second light guiding unit, and a pulse stretcher according to a third embodiment is shown. DETAILED DESCRIPTION

[0021] 1. Description of the electronic device manufacturing apparatus used in the exposure process of the electronic device

[0022] 2. Description of the Gas Laser Device of the Comparative Example

[0023] 2.1 Structure

[0024] 2.2 Action

[0025] 2.3 Topics

[0026] 3. Description of the Gas Laser Device of Embodiment 1

[0027] 3.1 Structure

[0028] 3.2 Action

[0029] 3.3 Function / Effect

[0030] 4. Description of the Gas Laser Device of Embodiment 2

[0031] 4.1 Structure

[0032] 4.2 Action / Effect

[0033] 5. Description of the Gas Laser Device of Embodiment 3

[0034] 5.1 Structure

[0035] 5.2 Action / Effect

[0036] Below, embodiments of the present disclosure are 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, the structures and actions described in each embodiment are not necessarily all required structures and actions of the present disclosure. In addition, the same reference numerals are given to the same structural elements, and repeated descriptions are omitted.

[0037] 1. Description of the electronic device manufacturing apparatus used in the exposure process of the electronic device

[0038] Figure 1 Schematic diagram showing an overall schematic configuration example of an electronic device manufacturing apparatus used in an exposure process of an electronic device. Figure 1 As shown, the manufacturing apparatus used in the exposure process includes a gas laser device 100 and an exposure device 200. The exposure device 200 includes an illumination optical system 210 and a projection optical system 220. The illumination optical system 210 includes a plurality of reflectors 211, 212, and 213. The illumination optical system 210 illuminates the mask pattern on the mask stage RT using the laser light incident from the gas laser device 100. The projection optical system 220 reduces and projects the laser light that has passed through the mask, forming an image on a workpiece (not shown) arranged on the workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with a photoresist. The exposure device 200 moves the mask stage RT and the workpiece stage WT in parallel in synchronization, thereby exposing the workpiece to the laser light reflecting the mask pattern. By transferring the device pattern onto the semiconductor wafer through this exposure process, semiconductor devices, which are electronic devices, can be manufactured.

[0039] 2. Description of the Gas Laser Device of the Comparative Example

[0040] 2.1 Structure

[0041] The gas laser device of the comparative example will be described. Note that the comparative examples disclosed herein are methods that the applicant recognizes as being known only to the applicant and are not publicly known examples acknowledged by the applicant himself.

[0042] Figure 2: This is a schematic diagram showing an example of the overall schematic structure of a gas laser device 100 of a comparative example. The gas laser device 100 is, for example, an ArF excimer laser device using a mixed gas containing argon (Ar), fluorine (F2), and neon (Ne). The gas laser device 100 outputs laser light having a central wavelength of approximately 193 nm. Alternatively, the gas laser device 100 may be a gas laser device other than the ArF excimer laser device, for example, a KrF excimer laser device using a mixed gas containing krypton (Kr), F2, and Ne. In this case, the gas laser device 100 emits laser light having a central wavelength of approximately 248 nm. A mixed gas containing Ar, F2, and Ne as a laser medium, or a mixed gas containing Kr, F2, and Ne as a laser medium is sometimes referred to as a laser gas. Furthermore, helium (He) may be used in place of Ne in the mixed gas used in the ArF excimer laser device and the KrF excimer laser device, respectively.

[0043] The gas laser device 100 of this example includes a housing 110, and a main structure including a laser oscillator 130 as a master oscillator arranged 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 sub-pulse stretcher 500, a detection unit 170, a display unit 180, a processor 190, and a gas module 700.

[0044] The laser oscillator 130 includes a cavity device CH1 , a charger 41 , a pulse power module 43 , a band-narrowing module 60 , and an output coupling mirror 70 as main structures.

[0045] exist Figure 2 , the internal structure of cavity device CH1 as viewed from a direction substantially perpendicular to the direction of laser light propagation is shown. Cavity device CH1 mainly includes a housing 30, a pair of windows 31a, 31b, a pair of electrodes 32a, 32b, an insulating portion 33, a feedthrough portion 34, and an electrode holder portion 36.

[0046] The laser gas is supplied from the laser gas supply device 703 of the gas module 700 via piping into the interior space of the housing 30, enclosing the laser gas therein. The laser medium in the laser gas excites the laser gas, generating light within the interior space. This light travels toward the windows 31a and 31b.

[0047] Window 31a is located on the front wall of housing 30 in the direction of laser light traveling from gas laser device 100 to exposure device 200, while window 31b is located on the rear wall of housing 30 in the same direction. Windows 31a and 31b are made of calcium fluoride substrates, and the surfaces of windows 31a and 31b on the inside and outside of housing 30 are flat. Windows 31a and 31b are not limited to calcium fluoride substrates, as long as they can transmit laser light.

[0048] Electrodes 32a and 32b are positioned opposite each other within the interior of housing 30, with their lengths oriented along the direction of light travel generated by the high voltage applied between electrodes 32a and 32b. The space between electrodes 32a and 32b in housing 30 is located between windows 31a and 31b. Electrodes 32a and 32b serve as discharge electrodes for exciting the laser medium through glow discharge. In this example, electrode 32a serves as the cathode, and electrode 32b serves as the anode.

[0049] Electrode 32a is supported by an insulating portion 33. The insulating portion 33 blocks an opening formed in the housing 30. The insulating portion 33 comprises an insulator. Furthermore, a feedthrough 34 formed of a conductive member is disposed within the insulating portion 33. The feedthrough 34 applies the voltage supplied from the pulse power module 43 to the electrode 32a. The electrode 32b is supported by and electrically connected to the electrode holder 36.

[0050] The charger 41 is a DC power supply device that charges a capacitor (not shown) located inside the pulse power module 43 at a specified voltage. The charger 41 is located outside the housing 30 and is connected to the pulse power module 43. The pulse power module 43 includes a switch (not shown) controlled by the processor 190. The pulse power module 43 is a voltage application circuit that, when the switch is switched from off to on, boosts the voltage applied from the charger 41 to generate a pulsed high voltage, which is then applied to the electrodes 32a and 32b. The application of the high voltage generates a discharge between the electrodes 32a and 32b. The energy from this discharge excites the laser medium within the housing 30. When the excited laser gas transitions to its ground state, it emits light, which is then emitted outside the housing 30 through the windows 31a and 31b. As described above, the pulsed high voltage applied between the electrodes 32a and 32b by the pulse power module 43 produces pulsed laser light.

[0051] Windows 31a and 31b can also be tilted at a Brewster's angle relative to the direction of laser light propagation to suppress reflection of the P-polarized laser light. In this example, windows 31a and 31b are tilted perpendicular to the direction of laser light propagation and the direction in which electrodes 32a and 32b face each other. Consequently, the laser light emitted from cavity device CH1 contains first linearly polarized light with a polarization direction perpendicular to the direction in which electrodes 32a and 32b face each other, and linearly polarized light with a polarization direction different from that of the first linearly polarized light is reduced from the laser light. In other words, windows 31a and 31b also function as polarizers, tilted relative to the polarization direction of the first linearly polarized light, and reducing linearly polarized light with a polarization direction different from that of the first linearly polarized light from the laser light.

[0052] The narrowband module 60 includes a housing 65, and a prism 61, a grating 63, and a rotating stage (not shown) disposed in the interior of the housing 65. The housing 65 has an opening, and the housing 65 is connected to the rear side of the housing 30 via the opening.

[0053] The prism 61 expands the beam width of the light emitted from the window 31b and causes the light to be incident on the grating 63. In addition, the prism 61 reduces the beam width of the reflected light from the grating 63 and causes the light to return to the internal space of the housing 30 via the window 31b. The prism 61 is supported by a rotating table and rotates via the rotating table. The rotation of the prism 61 changes the incident angle of the light relative to the grating 63. Therefore, by rotating the prism 61, the wavelength of the light returned from the grating 63 via the prism 61 to the housing 30 can be selected. Figure 2 , an example in which one prism 61 is arranged is shown, but two or more prisms may be arranged.

[0054] The surface of the grating 63 is made of a high-reflectivity material and has multiple grooves spaced at regular intervals. The grating 63 is a dispersive optical element. The cross-sectional shape of each groove is, for example, a right triangle. Light incident on the grating 63 from the prism 61 is reflected by these grooves and diffracted in a direction corresponding to the wavelength of the light. The grating 63 is configured in a Littrow configuration so that the angle of incidence of the light incident on the grating 63 from the prism 61 matches the diffraction angle of the diffracted light of the desired wavelength. As a result, light of the desired wavelength is returned to the housing 30 via the prism 61.

[0055] The output coupling mirror 70 faces the window 31a, transmits part of the laser light emitted from the window 31a, and reflects the other part to return to the interior of the housing 30 through the window 31a. The output coupling mirror 70 is fixed to a holder (not shown) and is arranged in the interior of the housing 110.

[0056] A Fabry-Perot resonator is formed by the grating 63 and the output coupling mirror 70 provided across the housing 30. The housing 30 is disposed on the optical path of the resonator. Therefore, the resonator resonates light between both sides across the cavity device CH1.

[0057] The optical transmission unit 141 includes high-reflection mirrors 141b and 141c as its main components. The high-reflection mirrors 141b and 141c are fixed to a holder (not shown) with their respective tilt angles adjusted, and are located within the interior space of the housing 110. The high-reflection mirrors 141b and 141c provide high reflection for the laser beam. The high-reflection mirrors 141b and 141c are located on the optical path of the laser beam from the output coupling mirror 70. The laser beam is reflected by the high-reflection mirrors 141b and 141c and travels toward the rear mirror 371 of the amplifier 160. At least a portion of the laser beam passes through the rear mirror 371.

[0058] Amplifier 160 amplifies the energy of the laser light 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 cavity device, housing, pair of windows, pair of electrodes, insulating portion, feedthrough, electrode holder, charger, pulse power module, and output coupling mirror of amplifier 160 are described as cavity device CH3, housing 330, pair of windows 331a and 331b, pair of electrodes 332a and 332b, insulating portion 333, feedthrough 334, electrode holder 336, charger 341, pulse power module 343, and output coupling mirror 370. Electrodes 332a and 332b generate discharges to amplify the laser light 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 light from laser oscillator 130.

[0059] 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 light enters as P-polarized light, and the laser light's incident angle θ is Brewster's angle. This tilting of windows 331a and 331b allows the laser light emitted from cavity device CH3 to contain the first linearly polarized light and reduces linearly polarized light with a polarization direction different from that of the first linearly polarized light. In other words, windows 331a and 331b, like windows 31a and 31b, also function as polarizers that are tilted relative to the polarization direction of the first linearly polarized light and reduce linearly polarized light with a polarization direction different from that of the first linearly polarized light from the laser light. The laser light emitted from windows 331a and 331b can also have a rectangular shape that is elongated in the direction in which the pair of electrodes 332a and 332b face each other. Like pulse power module 43, pulse power module 343 is a voltage application circuit.

[0060] The amplifier 160 differs from the laser oscillator 130 mainly in that the amplifier 160 does not include the bandwidth narrowing module 60 but includes a rear mirror 371 .

[0061] The rear mirror 371 is disposed between the high-reflection mirror 141c and the window 331b, facing each of them. The rear mirror 371 transmits a portion of the laser light from the laser oscillator 130 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.

[0062] The output coupling mirror 370 is disposed between the window 331a and the high-reflection mirror 151, facing each of them. The output coupling mirror 370 reflects a portion of the laser light emitted after being amplified by the electrodes 332a and 332b toward the space between the electrodes 332a and 332b, while allowing another portion of the laser light to pass through the high-reflection mirror 151. Therefore, the surface of the output coupling mirror 370 facing the window 331a is coated with a partially reflective film having a predetermined reflectivity.

[0063] The output coupling mirror 370 may also be circular. The surface of the output coupling mirror 370 facing the window 331 a and the surface opposite thereto are flat surfaces. The rear mirror 371 has a similar structure to the output coupling mirror 70 .

[0064] A resonator is formed by a rear mirror 371 and an output coupling mirror 370, which are arranged across the housing 330, to resonate the laser light amplified by the electrodes 332a and 332b. The housing 330 is arranged on the optical path of the resonator. The laser light emitted from the window 331a of the housing 330 is incident on the output coupling mirror 370, and a portion of it is reflected by the output coupling mirror 370. The laser light reflected by the output coupling mirror 370 returns to the interior space of the housing 330 via the window 331a and is emitted from the window 331b. The laser light emitted from the window 331b is reflected by the rear mirror 371 and returns to the interior space of the housing 330 via the window 331b. In this way, the laser light emitted from the housing 330 reciprocates between the rear mirror 371 and the output coupling mirror 370. The reciprocating laser light is amplified each time it passes through the discharge space between the electrodes 332a and 332b. That is, the resonator resonates light between two sides of the cavity device CH3, and the output coupling mirror 370 is arranged 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 that passes through the output coupling mirror 370 travels toward the high-reflection mirror 151. Thus, the laser light that travels from the output coupling mirror 370 to the high-reflection mirror 151 is pulsed laser light.

[0065] Figure 3This is a schematic diagram showing an example of the schematic structure of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 of the comparative example, viewed from obliquely above. The first light guide unit 150 includes high-reflection mirrors 151 and 152 as its main components. Below, the description will be made with the direction parallel to the optical axis of the laser light emitted from the window 331a of the cavity device CH3 and transmitted through the output coupling mirror 370 and propagating in the Z direction, the height direction of the gas laser device 100 being the V direction, and the direction perpendicular to the V and Z directions being the H direction. The V direction is perpendicular to the Z direction, approximately parallel to the vertical direction, and pointing upward. Therefore, in this example, the optical axis of the laser light emitted from the window 331a and transmitted through the output coupling mirror 370 is approximately parallel to the horizontal direction.

[0066] The high reflective mirrors 151 and 152 are fixed to a holder (not shown) with their respective tilt angles adjusted, so as to highly reflect the laser light. Figure 3 In FIG, the outer shape of the laser light is shown by a dashed line, and the polarization direction of the first linearly polarized light in the laser light is shown by a solid arrow. High reflector 151 is arranged on the optical path of the laser light from output coupling mirror 370. High reflector 151 reflects the laser light from output coupling mirror 370 in the -H direction. High reflector 152 is arranged on the optical path of the laser light after reflection from high reflector 151, and is located closer to the -H direction than the optical axis of the laser light transmitted through output coupling mirror 370. High reflector 152 reflects the laser light reflected from high reflector 151 in the V direction, and this laser light enters pulse stretcher 400.

[0067] The pulse stretcher 400 stretches the pulse width of the laser light incident on the pulse stretcher 400 from the first light guiding unit 150 , and emits the laser light having the stretched pulse width toward the second light guiding unit 155 .

[0068] The pulse stretcher 400 of this example mainly comprises a light guide system 410, two ring optical paths 420L and 430L, and a housing (not shown). The pulse stretcher 400 is positioned on the V-direction side relative to the optical axis of the laser beam transmitted through the output coupling mirror 370. The light guide system 410 and the ring optical paths 420L and 430L are housed in the housing.

[0069] The light-guiding optical system 410 of this example has four light-guiding mirrors 411, 412, 413, and 414 as its main components. The light-guiding mirrors 411, 412, 413, and 414 are supported by the housing of the pulse stretcher 400 at adjusted tilt angles, thereby providing high laser reflection. The light-guiding mirror 411 is located closer to the -H direction than the optical axis of the laser beam transmitted through the output coupling mirror 370 and is positioned on the optical path of the laser beam that is reflected by the high-reflection mirror 152 and enters the pulse stretcher 400. The light-guiding mirror 411 reflects the laser beam entering the pulse stretcher 400 in the H direction. The light-guiding mirror 412 is positioned on the optical path of the laser beam reflected by the light-guiding mirror 411 and is positioned on the side opposite to the light-guiding mirror 411 side of the optical axis of the laser beam transmitted through the output coupling mirror 370. The light-guiding reflector 412 reflects the laser light reflected by the light-guiding reflector 411 in the Z direction. The light-guiding reflector 413 is arranged on the optical path of the laser light reflected by the light-guiding reflector 412. The light-guiding reflector 413 reflects the laser light reflected by the light-guiding reflector 412 in the -H direction. The light-guiding reflector 414 is arranged on the optical path of the laser light reflected by the light-guiding reflector 413, and is arranged at a position closer to the -H direction side than the optical axis of the laser light passing through the output coupling mirror 370. The light-guiding reflector 414 and the light-guiding reflector 411 are arranged in the Z direction. The light-guiding reflector 414 reflects the laser light reflected by the light-guiding reflector 413 in the -V direction, and the laser light is emitted from the pulse stretcher 400. The light guide optical system 410 having such a structure reflects the laser light incident on the pulse stretcher 400 sequentially on a plurality of light guide mirrors 411 , 412 , 413 , and 414 , and emits the laser light from the side of the pulse stretcher 400 where the laser light was incident.

[0070] In this example, the annular optical path 420L is composed of a beam splitter 421 and six reflective mirrors 422, 423, 424, 425, 426, and 427. The beam splitter 421 is arranged on the optical path of the laser light in the light guide optical system 410, in the optical path of the laser light that is reflected by the high reflective mirror 152, enters the pulse stretcher 400, and then travels toward the light guide reflective mirror 411. The beam splitter 421 is supported by the housing of the pulse stretcher 400. The beam splitter 421 splits the incident laser light into two, allowing one of the split laser beams to pass through the light guide reflective mirror 411, propagating along the optical path of the light guide optical system 410, and reflects the other split laser beam toward the reflective mirror 422.

[0071] Mirrors 422-427 are concave mirrors supported by the housing of the pulse stretcher 400. Mirrors 422, 424, and 426 are positioned on the Z-direction side relative to the light-guiding mirrors 411-414 and are arranged in the H-direction in the order of mirrors 422, 426, and 424. Mirrors 423, 425, and 427 are positioned on the -Z-direction side relative to the light-guiding mirrors 411-414 and are arranged in the H-direction in the order of mirrors 427, 423, and 425. Mirrors 422 and 427 face each other parallel to the Z-direction, with the beam splitter 421 located between them. Mirrors 424 and 425 face each other parallel to the Z-direction, while mirrors 426 and 423 face each other parallel to the Z-direction.

[0072] Mirrors 422 to 427 sequentially reflect the laser light reflected by beam splitter 421 and return it to beam splitter 421. Specifically, mirror 422 reflects the laser light reflected by beam splitter 421 toward mirror 423. Mirror 423 reflects the laser light reflected by mirror 422 toward mirror 424. Mirror 424 reflects the laser light reflected by mirror 423 toward mirror 425. Mirror 425 reflects the laser light reflected by mirror 424 toward mirror 426. Mirror 426 reflects the laser light reflected by mirror 425 toward mirror 427. Mirror 427 reflects the laser light reflected by mirror 426 toward beam splitter 421, causing it to enter beam splitter 421 from a surface opposite to the surface on which the laser light reflected by high-reflection mirror 152 enters. In this way, a ring optical path 420L, which is an optical path of the laser light returning from the beam splitter 421 via the reflection mirrors 422 to 427 to the beam splitter 421 , is formed. The ring optical path 420L expands in the H direction and the Z direction.

[0073] Beam splitter 421 reflects a portion of the laser light, which has been reflected by reflector 427 and returned to beam splitter 421, toward light guide reflector 411, and transmits the remaining portion toward reflector 422. The transmitted laser light propagates along annular optical path 420L. In this manner, the laser light is reflected six times in annular optical path 420L, making one complete circuit, and thus making at least one complete circuit within annular optical path 420L.

[0074] The laser light that has traveled once around the annular optical path 420L and returned to the beam splitter 421, where it was split and directed toward the light guide mirror 411, is delayed by a predetermined time compared to the laser light that has not traveled toward the reflector 422 but has passed through the beam splitter 421 and is directed toward the light guide mirror 411. The laser light that has traveled from the beam splitter 421 toward the light guide mirror 411 with a predetermined delay overlaps with a portion of the laser light that has not traveled toward the reflector 422 but has passed through the beam splitter 421 and is directed toward the light guide mirror 411. In other words, the laser light that has returned to the beam splitter 421 is split into laser light that partially overlaps with one of the laser lights split by the beam splitter 421 and into laser light that is sequentially reflected by the reflectors 422 to 427. Each time the laser light makes one complete circuit of the annular optical path 420L, laser light overlaps. Due to this laser light overlap, the laser light, after its pulse width has been expanded, travels toward the light guide mirror 411 and propagates through the light guide optical system 410. Specifically, the annular optical path 420L is configured such that a portion of the laser light entering the beam splitter 421 returns to the beam splitter 421 via the mirrors 422 to 427 and overlaps with another portion of the laser light entering the beam splitter 421.

[0075] In this example, the annular optical path 430L is composed of a beam splitter 431 and four mirrors 432, 433, 434, and 435. Beam splitter 431 is disposed on the optical path of the laser light in the light guiding optical system 410, and is supported by the housing of the pulse stretcher 400. Beam splitter 431 splits the incident laser light into two, allowing one of the split beams to pass through light guiding mirror 414, propagating along the optical path of the light guiding optical system 410, and reflects the other split beam toward mirror 432.

[0076] Mirrors 432-435 are concave mirrors supported by the housing of the pulse stretcher 400. Mirrors 432 and 434 are positioned on the Z-direction side relative to the light-guiding mirrors 411-414, and are arranged in the H-direction in the order of mirrors 432 and 434. Mirrors 433 and 435 are positioned on the -Z-direction side relative to the light-guiding mirrors 411-414, and are arranged in the H-direction in the order of mirrors 435 and 433. Mirrors 432 and 435 face each other parallel to the Z-direction, with the beam splitter 431 located between them. Mirrors 433 and 434 face each other parallel to the Z-direction. Mirrors 433 and 434 are positioned on the H-direction side relative to mirrors 422 and 427 of the annular optical path 420L.

[0077] Mirrors 432 to 435 reflect the laser light reflected by beam splitter 431 sequentially in the order of mirrors 432 to 435. Mirror 435 reflects the laser light reflected by mirror 434 toward beam splitter 431, causing it to enter beam splitter 431 from the surface opposite to the surface on which the laser light reflected by light guide mirror 413 entered. This forms an annular optical path 430L, the optical path of the laser light that returns from beam splitter 431 via mirrors 432 to 435 to beam splitter 431. Annular optical path 430L expands in the H and Z directions. The optical path length of annular optical path 430L is shorter than that of annular optical path 420L. Furthermore, annular optical path 430L is located above annular optical path 420L and vertically overlaps annular optical path 430L and 420L.

[0078] Beam splitter 431 reflects a portion of the laser light that has been reflected by reflector 435 and returned to beam splitter 431 toward light guide reflector 414, and transmits the remaining portion toward reflector 432. The transmitted laser light propagates along annular optical path 430L. In this manner, the laser light is reflected four times in annular optical path 430L, making one complete circuit, and thus making at least one complete circuit within annular optical path 430L.

[0079] In this annular optical path 430L, similar to annular optical path 420L, a portion of the laser light traveling from beam splitter 431 toward light guide mirror 414 overlaps with a portion of the laser light traveling from beam splitter 431 toward light guide mirror 414, delayed by a predetermined time. This overlap occurs each time the laser light travels through annular optical path 430L. This overlap causes the laser light, after its pulse width has been expanded, to travel toward light guide mirror 414 and propagate through light guide optical system 410. Specifically, annular optical path 430L is configured such that a portion of the laser light entering beam splitter 431 returns to beam splitter 431 via mirrors 432 to 435, where it overlaps with another portion of the laser light entering beam splitter 431.

[0080] In this manner, the laser light whose pulse width is extended by the ring optical paths 420L and 430L is emitted from the pulse stretcher 400 toward the second light guiding unit 155 .

[0081] The second light guide unit 155 of this example includes high-reflection mirrors 156 and 157 as main components. The high-reflection mirrors 156 and 157 are fixed to a holder (not shown) with their respective tilt angles adjusted, thereby providing high reflection of the laser light. The high-reflection mirror 156 is arranged on the optical path of the laser light emitted from the pulse stretcher 400, and is located on the -H direction side of the optical axis of the laser light that passes through the output coupling mirror 370. The high-reflection mirror 156 and the high-reflection mirror 152 are arranged in the Z direction. The high-reflection mirror 156 reflects the laser light emitted from the pulse stretcher 400 in the H direction. The high-reflection mirror 157 is arranged on the optical path of the laser light after being reflected by the high-reflection mirror 156, and the high-reflection mirror 157 and the high-reflection mirror 151 are arranged in the Z direction. The high-reflection mirror 157 reflects the laser light after being reflected by the high-reflection mirror 156 in the Z direction, and the laser light travels toward the sub-pulse stretcher 500. The optical axis of the laser light traveling from the high reflection mirror 157 to the sub-pulse stretcher 500 can be roughly consistent with the optical axis of the laser light passing through the output coupling mirror 370, or the optical axis of the laser light passing through the output coupling mirror 370 can be parallel to the optical axis of the laser light traveling to the sub-pulse stretcher 500 and shifted in the ±V direction or the ±Z direction.

[0082] Figure 4 This is a schematic diagram showing an example of the schematic structure of a housing 440 of a pulse stretcher 400 according to a comparative example, as viewed obliquely from below.

[0083] like Figure 4 As shown, the housing 440 is a box-shaped component with a space inside, supported by the main body portion of the casing 110 (described later). In this example, the housing 440 is a rectangular parallelepiped elongated in the Z direction. An input hole 442 and an output hole 443 are provided on the lower wall 441 of the housing 440, and the input hole 442 and the output hole 443 are aligned in the Z direction. Laser light directed from the high reflector 152 toward the light guide mirror 411 enters the interior of the housing 440 through the input hole 442. Furthermore, laser light directed from the light guide mirror 414 toward the high reflector 156 exits the interior of the housing 440 through the output hole 443. The section of the optical path of the laser light from the high reflector 152 toward the light guide mirror 411 that is closer to the high reflector 152 than the input hole 442 is the optical path of the laser light incident on the pulse stretcher 400, namely, the input optical path 400Li. The input optical path 400Li is approximately parallel to the V direction. The section of the optical path of the laser light from the light guide mirror 414 toward the high reflector 156 that is closer to the high reflector 156 than the output hole 443 is the optical path of the laser light emitted from the pulse stretcher 400, that is, the output optical path 400Lo. The output optical path 400Lo is substantially parallel to the V direction. Figure 3 In FIG. 4 , a first straight line Li along the input optical path 400Li and a second straight line Lo along the output optical path 400Lo are shown by dotted lines.

[0084] Figure 5 FIG. 5 is a schematic diagram showing a schematic configuration example of a sub-pulse stretcher 500 according to a comparative example. Figure 5 As shown, the sub-pulse stretcher 500 of this embodiment includes a beam splitter 501, four reflective mirrors 511, 512, 513, and 514, and a housing (not shown). The beam splitter 501 is arranged in the optical path of the laser light reflected by the high-reflection mirror 157 and is supported by the housing of the sub-pulse stretcher 500. The beam splitter 501 splits the laser light reflected by the high-reflection mirror 157 into two, reflecting one of the split laser beams toward the reflective mirror 511 and transmitting the other split laser beam toward the beam splitter 171.

[0085] Reflection mirrors 511-514 are concave mirrors supported by the housing of the sub-pulse stretcher 500. Reflection mirrors 511 and 513 are positioned on the -V side of the optical axis of the laser beam after reflection by the high reflection mirror 157, and are arranged in the Z direction in the order of reflection mirrors 511 and 513. Reflection mirrors 512 and 514 are positioned on the V side of the optical axis of the laser beam after reflection by the high reflection mirror 157, and are arranged in the Z direction in the order of reflection mirrors 514 and 512. Reflection mirrors 511 and 514 face each other in a direction parallel to the V direction, with the beam splitter 501 located between them. Reflection mirrors 512 and 513 face each other in a direction parallel to the V direction.

[0086] The mirrors 511 to 514 reflect the laser light reflected from the beam splitter 501 sequentially in the order of the mirrors 511 to 514 and return it to the beam splitter 501. The beam splitter 501 is located between the mirrors 511 and 514. Therefore, the laser light reflected from the mirror 514 enters the beam splitter 501 from the surface opposite to the surface on which the laser light reflected from the high-reflection mirror 157 enters. In the sub-pulse stretcher 500 with this configuration, a ring optical path 500L, which is the optical path of the laser light returning from the beam splitter 501 via the mirrors 511 to 514 to the beam splitter 501, is formed.

[0087] Beam splitter 501 reflects a portion of the laser light, which has been reflected by mirror 514 and returned to beam splitter 501, toward beam splitter 171, and transmits the remaining portion toward mirror 511. The transmitted laser light propagates along ring optical path 500L. Thus, in sub-pulse stretcher 500, the laser light is reflected four times in ring optical path 500L, making one complete circuit, and thus making at least one complete circuit.

[0088] In annular optical path 500L, similar to annular optical paths 420L and 430L, a portion of the laser light traveling from beam splitter 501 toward beam splitter 171 overlaps with laser light traveling from beam splitter 501 toward beam splitter 171 with a predetermined delay relative to the laser light. This overlap occurs each time the laser light makes one full rotation around annular optical path 430L. Due to this overlap, the laser light, after its pulse width has been expanded, is emitted from sub-pulse stretcher 500 and travels toward detection unit 170.

[0089] The detection section 170 includes a beam splitter 171 and a photosensor 172 as main components.

[0090] The beam splitter 171 is arranged on the optical path of the laser light emitted from the sub-pulse stretcher 500 . The beam splitter 171 transmits the laser light emitted from the sub-pulse stretcher 500 toward the emission window 173 with high transmittance and reflects a portion of the laser light toward the light receiving surface of the optical sensor 172 .

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

[0092] The emission window 173 is provided on the wall of the housing 110. The light transmitted through the beam splitter 171 is emitted from the emission window 173 toward the exposure device 200 outside the housing 110. This laser is, for example, a pulsed laser having a central wavelength of 193.4 nm.

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

[0094] The processor 190 of the present disclosure is a processing device comprising a storage device storing a control program and a CPU (Central Processing Unit) that executes the control program. The processor 190 is specifically configured or programmed to perform the various processes described in the present disclosure. Furthermore, the processor 190 controls the entire gas laser device 100. Furthermore, the processor 190 is electrically connected to an exposure processor (not shown) of the exposure device 200, transmitting and receiving various signals to and from the exposure processor.

[0095] The gas module 700 includes a laser gas exhaust device 701 and a laser gas supply device 703. The laser gas exhaust device 701 and the laser gas supply device 703 are electrically connected to the processor 190 via signal lines (not shown). The laser gas exhaust device 701 includes an exhaust pump (not shown). In response to a control signal from the processor 190, the exhaust pump operates to discharge laser gas from the interior of the housing 30 or 330 through piping. The laser gas supply device 703 supplies laser gas from a laser gas supply source (not shown) located outside the housing 110 through piping into the interior of the housing 30 or 330 in response to a control signal from the processor 190.

[0096] Figure 6 1 is a schematic diagram showing a schematic structural example of the housing 110 of the comparative example. Figure 6 As shown, the housing 110 of this example has a main body 111 and two maintenance panels 115 and 116 as its main structures. The main body 111 is a box-shaped component with a space inside. Various devices such as the laser oscillator 130 and the amplifier 160 are housed in the internal space. In this example, the main body 111 has a rectangular parallelepiped shape. The main body 111 includes a rectangular lower wall 112 that is longer in the Z direction, four rectangular side walls 113a to 113d connected to the four sides of the lower wall 112, and a rectangular upper wall 114 that is opposite to the lower wall 112 and connected to each of the side walls 113a to 113d. The side walls 113a and 113c are opposite to each other in a direction parallel to the Z direction, with the side wall 113a located closer to the Z direction side than the side wall 113c. The side wall 113b and the side wall 113d are opposed to each other in a direction parallel to the H direction, and the side wall 113b is located closer to the H direction than the side wall 113d. Two openings 113h1 and 113h2 are formed in the side wall 113b, arranged vertically. These openings 113h1 and 113h2 allow various devices stored in the internal space to enter and exit. The outer shape of the openings 113h1 and 113h2 is a rectangular shape that is longer in the Z direction. Figure 6 , as various devices, chamber devices CH1 and CH3, a processor 190, a pulse stretcher 400, a sub-pulse stretcher 500, chargers 41 and 341, and a gas module 700 are schematically shown.

[0097] Maintenance panels 115 and 116 cover openings 113h1 and 113h2. These panels are rectangular, plate-like members that are elongated in the Z direction and are detachably attached to sidewall 113b of main body 111. The position, number, and shape of openings 113h1 and 113h2 are not limited.

[0098] As described above, the high-reflection mirror 152 and the light-guiding reflector 411, as well as the light-guiding reflector 414 and the high-reflection mirror 156, are located on the -H side relative to the optical axis of the laser beam transmitted through the output coupling mirror 370. The optical axis of the laser beam is substantially parallel to the Z direction, and maintenance panels 115 and 116 are attached to the sidewall 113b. Therefore, the input optical path 400Li and the output optical path 400Lo in the pulse stretcher 400 are located on the side opposite to the maintenance panels 115 and 116 relative to the optical axis of the laser beam transmitted through the output coupling mirror 370. When the sidewall 113d of the housing 110 is designated as the rear surface, and the side opposite to the maintenance panels 115 and 116 is designated as the rear side, the input optical path 400Li and the output optical path 400Lo are located on the rear side relative to the optical axis of the laser beam transmitted through the output coupling mirror 370.

[0099] 2.2 Action

[0100] Next, the operation of the gas laser device 100 of the comparative example will be described.

[0101] Before the gas laser device 100 emits laser light, laser gas is supplied from the laser gas supply device 703 to the internal space of the housings 30 , 330 .

[0102] When the gas laser device 100 emits laser light, the processor 190 receives a signal indicating the target energy Et and a light emission trigger signal from the exposure processor. The target energy Et is the target value of the energy of the laser light used in the exposure process. The processor 190 sets a predetermined charging voltage for the charger 41 so that the energy E reaches the target energy Et, and turns on the switch of the pulse power module 43 in synchronization with the light emission trigger signal. The pulse power module 43 then generates a pulsed high voltage using the electrical energy held by the charger 41, applying the high voltage between the electrodes 32a and 32b. When the high voltage is applied, a discharge occurs between the electrodes 32a and 32b, causing the laser medium contained in the laser gas between the electrodes 32a and 32b to enter an excited state. When the laser medium returns to a ground state, light is emitted. The emitted light resonates between the grating 63 and the output coupling mirror 70, and is amplified each time it passes through the discharge space within the interior of the housing 30, generating laser oscillation. The laser light includes the first linearly polarized light. When passing through windows 31a and 31b, linearly polarized light having a polarization direction different from that of the first linearly polarized light is reduced from the laser light. A portion of the laser light passes through output coupling mirror 70, is reflected by high-reflection mirrors 141b and 141c, and then passes through rear mirror 371 and window 331b, traveling into housing 330.

[0103] Processor 190 turns on the switch of pulse power module 343 so that a discharge is generated when the laser light from laser oscillator 130 travels into the discharge space within housing 330. Specifically, processor 190 controls pulse power module 343 so that a high voltage is applied to electrodes 332a and 332b after a predetermined delay time has elapsed from the timing of turning on the switch of pulse power module 343.

[0104] Thus, the laser light incident on amplifier 160 is amplified within amplifier 160. Furthermore, the laser light traveling into the interior of housing 330 passes through windows 331a and 331b as described above and travels toward rear mirror 371 and output coupling mirror 370. In this manner, laser light of a predetermined wavelength travels back and forth between rear mirror 371 and output coupling mirror 370. The laser light includes first linearly polarized light, and when passing through windows 331a and 331b, linearly polarized light with a polarization direction different from that of the first linearly polarized light is reduced from the laser light. Furthermore, the laser light is amplified each time it passes through the discharge space within housing 330, with a portion of the laser light becoming amplified laser light.

[0105] The amplified laser light from the amplifier 160 passes through the output coupling mirror 370 and travels toward the high reflector 151. This laser light includes first linearly polarized light whose polarization direction is parallel to the H direction. This laser light enters the high reflector 151 such that the first linearly polarized light becomes P-polarized light, and is reflected by the high reflector 151 toward the high reflector 152. After being reflected by the high reflector 151, the laser light enters the high reflector 152 such that the first linearly polarized light in the laser light becomes S-polarized light. This light is then reflected in the V direction by the high reflector 152 and enters the pulse stretcher 400.

[0106] The laser light incident on the pulse stretcher 400 enters the light guide reflector 411 such that the first linear polarization in the laser light becomes S-polarized light, and is reflected by the light guide reflector 411 toward the light guide reflector 412. After being reflected by the light guide reflector 411, the laser light enters the light guide reflector 412 such that the first linear polarization in the laser light becomes P-polarized light, and is reflected by the light guide reflector 412 toward the light guide reflector 413. After being reflected by the light guide reflector 413, the laser light enters the light guide reflector 414 such that the first linear polarization in the laser light becomes P-polarized light, and is reflected by the light guide reflector 414 to be emitted from the side of the pulse stretcher 400 from which the laser light entered, i.e., the lower side. Furthermore, in the pulse stretcher 400, the pulse width of the laser light, which is sequentially reflected by the light guide mirrors 411 to 414 of the light guide optical system 410 and propagates, is expanded through the respective ring optical paths 420L and 430L. The laser light with expanded pulse width then exits the pulse stretcher 400 and travels toward the high reflector 156. The laser light enters the high reflector 156 such that the first linearly polarized light in the laser light becomes S-polarized light, and is reflected by the high reflector 156 toward the high reflector 157. After being reflected by the high reflector 156, the laser light enters the high reflector 157 such that the first linearly polarized light in the laser light becomes P-polarized light, and is reflected by the high reflector 157 in the Z direction before entering the sub-pulse stretcher 500.

[0107] The pulse width of the laser light incident on the sub-pulse stretcher 500 is expanded by the sub-pulse stretcher 500 , and the laser light with the expanded pulse width travels toward the beam splitter 171 .

[0108] Part of the laser light traveling toward the beam splitter 171 passes through the beam splitter 171 and the emission window 173 and travels toward the exposure device 200 , while the other part is reflected by the beam splitter 171 and travels toward the optical sensor 172 .

[0109] Optical sensor 172 measures energy E of the received laser beam. Optical sensor 172 outputs a signal indicating the measured energy E to processor 190. Processor 190 performs feedback control on the charging voltage of chargers 41 and 341 so that the difference ΔE between energy E and target energy Et falls within an allowable range.

[0110] 2.3 Topics

[0111] The pulse stretcher 400 is sometimes positioned relative to the input optical path 400Li and the output optical path 400Lo. In this case, if the positions of the reflectors 422-427, 432-435 constituting the ring optical paths 420L and 430L relative to the input optical path 400Li and the output optical path 400Lo deviate from their designed positions, the laser performance may deviate from the designed values. Therefore, there is a need to suppress the laser performance from deviating from the designed values.

[0112] Therefore, in the following embodiments, a gas laser device capable of suppressing the performance of laser light from deviating from the design value is exemplified.

[0113] 3. Description of the Gas Laser Device of Embodiment 1

[0114] Next, the gas laser device 100 according to Embodiment 1 will be described. Components identical to those described above are denoted by the same reference numerals, and redundant descriptions will be omitted unless otherwise specified.

[0115] 3.1 Structure

[0116] Figure 7 is with Figure 3 Similarly, a diagram showing an example of the schematic configuration of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 of this embodiment is shown. Figure 7 As shown, the pulse stretcher 400 of this embodiment differs from the pulse stretcher 400 of the comparative example mainly in that the light guiding optical system 410 does not include the light guiding mirrors 413 and 414 .

[0117] In the light guide optical system 410 of this embodiment, the light guide mirror 412 reflects the laser light reflected by the light guide mirror 411 in the −V direction, and the laser light is emitted from the pulse stretcher 400 .

[0118] In the ring optical path 420L of this embodiment, the beam splitter 421 is arranged on the optical path of the laser light in the light guiding optical system 410, in the optical path of the laser light reflected by the light guiding reflector 411 and directed toward the light guiding reflector 412. In the ring optical path 430L of this embodiment, the beam splitter 431 is arranged on the optical path of the laser light reflected by the light guiding reflector 411 and directed toward the light guiding reflector 412, on the -H direction side of the beam splitter 421. The reflectors 432 and 434 of the ring optical path 430L and the reflectors 422, 426, and 424 of the ring optical path 420L are arranged in the H direction in this order. Furthermore, the reflectors 435 and 433 of the ring optical path 430L and the reflectors 427, 423, and 425 of the ring optical path 420L are arranged in the order of reflectors 435, 433, 427, 423, and 425 in the H direction. The ring optical path 420L is located further in the H direction than the ring optical path 430L, and the ring optical paths 430L and 420L are aligned in the H direction. The input optical path 400Li is located on the side opposite to the maintenance panels 115 and 116 relative to the optical axis of the laser light transmitted through the output coupling mirror 370, while the output optical path 400Lo is located on the maintenance panels 115 and 116 relative to the optical axis of the laser light transmitted through the output coupling mirror 370. The ring optical paths 420L and 430L are located between a first straight line Li along the input optical path 400Li and a second straight line Lo along the output optical path 400Lo.

[0119] In the second light guide unit 155 of this embodiment, a high reflector 156 is arranged on the optical path of the laser light emitted from the pulse stretcher 400, located closer to the -V direction than the high reflector 151. The high reflector 156 reflects the laser light emitted from the pulse stretcher 400 in the -H direction. A high reflector 157 is arranged on the optical path of the laser light after it is reflected by the high reflector 156. The high reflector 157 is located closer to the -V direction than the high reflector 151, and the high reflector 157 and the high reflector 151 are aligned in the V direction. The high reflector 157 reflects the laser light after it is reflected by the high reflector 156 in the Z direction, and this laser light travels toward the sub-pulse stretcher 500. The optical axis of the laser light traveling from the high reflector 157 to the sub-pulse stretcher 500 is approximately parallel to the optical axis of the laser light transmitted through the output coupling mirror 370 and is located closer to the -V direction than this optical axis.

[0120] Figure 8 Schematic diagram showing an example of the schematic structure of the housing 110 of this embodiment. Figure 8In the housing 110 shown, the maintenance panel 115 is removed. The housing 110 of this embodiment further includes an optical tube 117. The optical tube 117 is a cylindrical component extending in a direction parallel to the V direction, and covers the output optical path 400Lo. The end of the optical tube 117 on the side of the housing 440 is mounted on the housing 440 in a detachable manner. The housing 440 is supported by the main body 111 of the housing 110, and therefore, the optical tube 117 is mounted on the main body 111 via the housing 440 in a detachable manner. In addition, the optical tube 117 can also be directly mounted on the main body 111 in a detachable manner. The optical tube 117 and the output optical path 400Lo covered by the optical tube 117 overlap with the opening 113h1.

[0121] 3.2 Action

[0122] The laser light incident on the pulse stretcher 400 is incident on the light guide mirror 411 so that the first linear polarization in the laser light becomes S-polarized light. The laser light is then reflected by the light guide mirror 411 toward the light guide mirror 412. After being reflected by the light guide mirror 411, the laser light is incident on the light guide mirror 412 so that the first linear polarization in the laser light becomes S-polarized light. The laser light is then reflected by the light guide mirror 412 and emitted from the lower side of the pulse stretcher 400, the side from which the laser light was incident. The pulse width of the laser light, which propagates through the light guide mirrors 411 and 412 in sequence, is expanded through the respective ring optical paths 420L and 430L. The laser light with the expanded pulse width is then emitted from the pulse stretcher 400 and travels toward the high reflector 156.

[0123] 3.3 Function / Effect

[0124] As described above, the pulse stretcher 400 is sometimes configured based on the input optical path 400Li and the output optical path 400Lo. For the reflectors 422-427 and 432-435 that constitute the annular optical paths 420L and 430L, the shorter of the distance between the reflector and the input optical path 400Li or the distance between the reflector and the output optical path 400Lo is set as the reflector's specific distance. In this case, when the specific distance of the reflector increases, it moves away from the input optical path 400Li and the output optical path 400Lo that serve as the reference, and tends to deviate from the designed position. In the pulse stretcher 400 of this embodiment, the annular optical paths 420L and 430L are configured between the first straight line Li along the input optical path 400Li and the second straight line Lo along the output optical path 400Lo. Therefore, compared to the case of pulse stretcher 400 in the comparative example, where input optical path 400Li and output optical path 400Lo are located on one side relative to ring optical paths 420L and 430L, the specific distance of the mirror having the largest specific distance among the mirrors 422 to 427 and 432 to 435 can be shortened. Therefore, according to the gas laser apparatus 100 of this embodiment, it is possible to suppress the positions of the mirrors 422 to 427 and 432 to 435 from deviating from the designed positions, and it is possible to suppress the laser performance from deviating from the designed value.

[0125] In the pulse stretcher 400 of this embodiment, the output optical path 400Lo is located closer to the maintenance panels 115 and 116 than the optical axis of the laser light emitted from the cavity device CH3 and transmitted through the output coupling mirror 370. The input optical path 400Li is located on the side opposite the maintenance panels 115 and 116. Furthermore, the output optical path 400Lo overlaps with the opening 113h1. Therefore, in this embodiment, the position of the opening 113h1 need not be considered when designing the optical path of the laser light from the cavity device CH3 to emission outside the housing 110. Therefore, the gas laser device 100 of this embodiment can suppress the complexity of the optical path of the laser light from the pulse stretcher 400 to emission outside the housing 110, reducing the number of reflective mirrors. Consequently, it is possible to reduce laser light loss in the light guiding optical system 410. Furthermore, the output optical path 400Lo does not need to overlap with the openings 113h1 and 113h2.

[0126] In the pulse stretcher 400 of this embodiment, the housing 110 includes an optical tube 117 that covers the output optical path 400Lo and is detachably mounted to the main body 111. Therefore, the gas laser device 100 of this embodiment protects equipment such as the cavity device CH3 housed in the housing 110, while also preventing the equipment from being difficult to remove. Alternatively, the housing 110 may not include the optical tube 117.

[0127] In the pulse stretcher 400 of this embodiment, the annular optical paths 420L and 430L are arranged parallel to the H direction, which is a direction non-parallel to the input optical path 400Li. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress the gas laser device 100 from increasing in size in a direction parallel to the input optical path 400Li. Alternatively, the annular optical paths 420L and 430L do not need to be arranged in a direction non-parallel to the input optical path 400Li.

[0128] The pulse stretcher 400 of this embodiment includes a housing 440. The housing 440 houses the light guiding optical system 410 and the annular optical paths 420L and 430L, and supports a plurality of light guiding mirrors 411 and 412, beam splitters 421 and 431, and a plurality of mirrors 422 to 427 and 432 to 435. The housing 440 includes an input hole 442 for inputting laser light from the cavity device CH3 and an output hole 443 for outputting laser light. The annular optical paths 420L and 430L are positioned between a first straight line Li along the input optical path 400Li and a first straight line Li along the output optical path 400Lo, thereby allowing for a greater distance between the input optical path 400Li and the output optical path 400Lo. According to the gas laser device 100 of this embodiment, when the pulse stretcher 400 is positioned relative to the input hole 442 and the output hole 443, alignment of the pulse stretcher 400 is facilitated, making the placement operation easier. Furthermore, the pulse stretcher 400 may not include the housing 440. In this case, for example, the plurality of light guide mirrors 411 and 412, the beam splitters 421 and 431, and the plurality of mirrors 422 to 427 and 432 to 435 are supported by the main body 111 of the housing 110.

[0129] In the pulse stretcher 400 of this embodiment, the light guiding optical system 410 is composed of a light guiding reflector 411 serving as a first light guiding reflector and a light guiding reflector 412 serving as a second light guiding reflector. The light guiding reflector 411 reflects the laser light incident on the pulse stretcher 400, while the light guiding reflector 412 reflects the laser light after being reflected by the light guiding reflector 411, causing the laser light to be emitted from the pulse stretcher 400. According to the gas laser device 100 of this embodiment, the number of laser light reflections can be reduced, and a decrease in the laser light intensity can be suppressed, compared to a case where the light guiding optical system 410 is composed of three or more light guiding reflectors. Furthermore, the light guiding optical system 410 may further include a light guiding reflector separate from the light guiding reflectors 411 and 412.

[0130] In the pulse stretcher 400 of this embodiment, the laser light entering the pulse stretcher 400 enters the light guide reflector 411 such that the first linear polarization of the laser light becomes S-polarized light. After being reflected by the light guide reflector 411, the laser light enters the light guide reflector 412 such that the first linear polarization of the laser light becomes S-polarized light. The reflectivity of S-polarized light tends to be higher than the reflectivity of P-polarized light. Therefore, according to the gas laser device 100 of this embodiment, for example, compared to a case where the laser light enters and is reflected by the light guide reflectors 411 and 412 such that the first linear polarization of the laser light becomes P-polarized light, a decrease in the light intensity at the light guide reflectors 411 and 412 can be suppressed. Therefore, according to the gas laser device 100 of this embodiment, a decrease in the light intensity of the laser light can be suppressed. Furthermore, the laser light does not need to enter the light guide reflectors 411 and 412 such that the first linear polarization of the laser light becomes S-polarized light.

[0131] 4. Description of the Gas Laser Device of Embodiment 2

[0132] Next, the gas laser device 100 according to Embodiment 2 will be described. The same reference numerals are used for components identical to those described above, and duplicate descriptions will be omitted unless otherwise specified. Furthermore, in some drawings, some components are omitted or simplified for easier viewing.

[0133] 4.1 Structure

[0134] Figure 9 is with Figure 3 Similarly, a diagram showing an example of the schematic configuration of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 of this embodiment is shown. Figure 9 As shown, the pulse stretcher 400 of this embodiment differs from the pulse stretcher 400 of Embodiment 1 mainly in that the beam splitter 421 of the ring optical path 420L is arranged on the optical path of the laser light that enters the pulse stretcher 400 and travels toward the light guide mirror 411 .

[0135] In this embodiment, annular optical path 420L is located closer to the -V direction than annular optical path 430L. Furthermore, annular optical path 420L and annular optical path 430L overlap in a direction parallel to input optical path 400Li. As in the first embodiment, annular optical paths 420L and 430L are located between a first straight line Li along input optical path 400Li and a second straight line Lo along output optical path 400Lo.

[0136] 4.2 Action / Effect

[0137] In the pulse stretcher 400 of this embodiment, as described above, the annular optical path 420L and the annular optical path 430L overlap in a direction parallel to the input optical path 400Li. Therefore, according to the gas laser device 100 of this embodiment, it is possible to suppress the gas laser device 100 from increasing in size in a direction perpendicular to the input optical path 400Li. Alternatively, the annular optical path 420L and the annular optical path 430L do not need to overlap in a direction parallel to the input optical path 400Li.

[0138] 5. Description of the Gas Laser Device of Embodiment 3

[0139] Next, the gas laser device 100 according to Embodiment 3 will be described. The same reference numerals are used for components identical to those described above, and duplicate descriptions will be omitted unless otherwise specified. Furthermore, in some drawings, some components are omitted or simplified for easier viewing.

[0140] 5.1 Structure

[0141] Figure 10 is with Figure 3 Similarly, a diagram showing an example of the schematic configuration of the first light guide unit 150, the second light guide unit 155, and the pulse stretcher 400 of this embodiment is shown. Figure 10 As shown, the gas laser device 100 of this embodiment differs from the gas laser device 100 of Embodiment 1 mainly in that the pulse stretcher 400 is arranged below the optical axis of the laser light emitted from the cavity device CH3 and transmitted through the output coupling mirror 370, that is, at a position on the -V direction side.

[0142] In the first light guide unit 150 of this embodiment, the high reflection mirror 151 reflects the laser light from the output coupling mirror 370 in the −H direction. The high reflection mirror 152 reflects the laser light reflected by the high reflection mirror 151 in the −V direction, and the laser light enters the pulse stretcher 400 .

[0143] In the light guide optical system 410 of this embodiment, the light guide mirror 411 reflects the laser light incident on the pulse stretcher 400 in the H direction. The light guide mirror 412 reflects the laser light reflected by the light guide mirror 411 in the V direction, and the laser light is emitted from the pulse stretcher 400. In other words, the laser light enters the pulse stretcher 400 from above, and the pulse stretcher 400 emits the laser light upward. Although not illustrated, the housing 440 of this embodiment has an input hole 442 and an output hole 443 provided on its upper wall.

[0144] In the annular optical path 420L of this embodiment, the beam splitter 421 is arranged on the optical path of the laser light in the light guiding optical system 410, and on the optical path of the laser light reflected by the light guiding mirror 412 and directed toward the high reflective mirror 156. The reflective mirrors 422, 424, and 426 are arranged in the -H direction in this order, and the reflective mirrors 423, 425, and 427 are arranged in the -H direction in this order.

[0145] In the annular optical path 430L of this embodiment, the beam splitter 431 is arranged on the optical path of the laser light in the light guide optical system 410, and on the optical path of the laser light that is reflected by the light guide reflector 411 and directed toward the light guide reflector 412. The reflectors 432 and 434 are arranged in the -H direction in that order, and the reflectors 433 and 435 are arranged in the -H direction in that order.

[0146] The annular optical path 420L is located further to the V-direction side than the annular optical path 430L. Furthermore, the annular optical path 420L and the annular optical path 430L overlap each other in a direction parallel to the input optical path 400Li. As in the first embodiment, the annular optical paths 420L and 430L are located between a first straight line Li along the input optical path 400Li and a second straight line Lo along the output optical path 400Lo.

[0147] In the second light guide unit 155 of this embodiment, a high reflector 156 is arranged on the optical path of the laser light emitted from the pulse stretcher 400. High reflector 156 is located on the V-direction side of the optical axis of the laser light transmitted through the output coupling mirror 370. High reflector 156 reflects the laser light emitted from the pulse stretcher 400 in the -H direction. High reflector 157 is arranged on the optical path of the laser light after reflection from high reflector 156. High reflector 157 is located on the V-direction side of high reflector 151, with high reflector 151 and high reflector 157 aligned in the V direction. High reflector 157 reflects the laser light reflected from high reflector 156 in the Z direction, and this laser light travels toward the sub-pulse stretcher 500. The optical axis of the laser light traveling from high reflector 157 to the sub-pulse stretcher 500 is approximately parallel to the optical axis of the laser light transmitted through the output coupling mirror 370 and is located on the V-direction side of that optical axis.

[0148] 5.2 Action / Effect

[0149] The pulse stretcher 400 of this embodiment is positioned below, i.e., in the -V direction, the optical axis of the laser light emitted from the cavity device CH3 and transmitted through the output coupling mirror 370. The gas laser device 100 of this embodiment prevents the pulse stretcher 400 from being positioned too high, compared to a case where the pulse stretcher 400 is positioned above the optical axis. This allows for easier maintenance of the pulse stretcher 400, for example. Furthermore, the position of the pulse stretcher 400 relative to the optical axis is not restricted.

[0150] In the above, the above embodiment has been described as an example, but the present disclosure is not limited thereto and can be modified as appropriate.

[0151] In the above embodiments, the pulse stretcher 400 including two ring-shaped optical paths 420L and 430L is described as an example. However, the number of ring-shaped optical paths is not limited.

[0152] In the above embodiments, the ring optical path 420L formed by the beam splitter 421 and six reflecting mirrors 422 to 427 and the ring optical path 430L formed by the beam splitter 431 and four reflecting mirrors 432 to 435 are described as examples. However, the number of reflecting mirrors constituting the ring optical path is not limited.

[0153] Furthermore, in the above embodiments, the first light guiding unit 150 including two high-reflection mirrors 151 and 152 and the second light guiding unit 155 including two high-reflection mirrors 156 and 157 are described as examples. However, as long as the laser light emitted from the cavity device CH3 is incident on the pulse stretcher 400, the number of high-reflection mirrors included in the first light guiding unit 150 and the second light guiding unit 155 is not limited. Furthermore, the gas laser device 100 may not include at least one of the first light guiding unit 150 and the second light guiding unit 155.

[0154] In the above embodiments, the pulse stretcher 400 is described as an example in which the input optical path 400Li and the output optical path 400Lo are substantially parallel to the vertical direction. However, at least one of the input optical path 400Li and the output optical path 400Lo may not be parallel to the vertical direction.

[0155] Furthermore, in the above embodiments, the beam splitters 421 and 431 are used as an example to describe the reflected laser light propagating along the ring optical paths 420L and 430L. However, the laser light transmitted through the beam splitters 421 and 431 may also propagate along the ring optical paths 420L and 430L. In this case, the beam splitters 421 and 431 are part of the light guide optical system 410, and are shared by the light guide optical system 410 and the ring optical paths 420L and 430L.

[0156] Furthermore, in the above embodiments, the pulse stretcher 400 is used as an example. In the pulse stretcher 400, the output optical path 400Lo is located closer to the maintenance panels 115 and 116 than the optical axis of the laser light emitted from the cavity device CH3 and transmitted through the output coupling mirror 370. However, the input optical path 400Li may also be located closer to the maintenance panels 115 and 116 than the optical axis. In this case, the input optical path 400Li may overlap with the opening 113h1. When the input optical path 400Li overlaps with the opening 113h1, the position of the opening 113h1 need not be considered in the design of the optical path of the laser light from the cavity device CH3 to the pulse stretcher 400. This can thus prevent the optical path from becoming complex.

[0157] Furthermore, in the above-described embodiments, the pulse stretcher 400 is described as being housed in the main body 111 of the housing 110 . However, the pulse stretcher 400 may be disposed outside the housing 110 .

[0158] In the above embodiments, the gas laser device 100 including the laser oscillator 130 and the amplifier 160 is described as an example. However, the gas laser device 100 may not include the amplifier 160. In this case, for example, laser light emitted from the cavity device CH1 and transmitted through the output coupling mirror 70 enters the pulse stretcher 400.

[0159] The above description is not limiting, but simply illustrative. Therefore, those skilled in the art will appreciate that changes can be made to the embodiments of the present disclosure without departing from the claims. In addition, those skilled in the art will also appreciate that the embodiments of the present disclosure can be used in combination. Unless otherwise expressly stated, the terms used in this specification and the claims as a whole should be interpreted as "non-limiting" terms. For example, terms such as "include", "have", "have", "have" and "have" should be interpreted as "excluding the presence of structural elements other than the structural elements to be recorded". In addition, the modifier "one" should be interpreted as meaning "at least one" or "one or more". In addition, 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 further, should be interpreted as also including combinations of them and parts other than "A", "B", and "C".

Claims

1. A gas laser device comprising: a cavity device including a pair of electrodes in an internal space enclosed with laser gas, and emitting pulsed laser light; and A pulse stretcher comprising an annular optical path and a light guiding optical system, wherein the annular optical path is composed of a beam splitter and a plurality of reflectors, and the light guiding optical system comprises a plurality of light guiding reflectors, wherein the pulse laser emitted from the cavity device is incident on the pulse stretcher. The light guide optical system is configured to allow the pulse laser light incident on the pulse stretcher to be emitted from the pulse stretcher via the beam splitter. The annular optical path is constructed so that a portion of the pulse laser incident on the beam splitter returns to the beam splitter via the multiple mirrors, thereby overlapping with another portion of the pulse laser incident on the beam splitter. The annular optical path is configured to be between a first straight line along an input optical path and a second straight line along an output optical path. The input optical path is the optical path of the pulse laser incident on the pulse stretcher, and the output optical path is the optical path of the pulse laser emitted from the pulse stretcher.

2. The gas laser device according to claim 1, wherein The gas laser device further includes a housing including a main body and a maintenance panel. The main body accommodates the cavity device and has an opening for access to the cavity device. The maintenance panel blocks the opening and is detachably mounted on the main body.

3. The gas laser device according to claim 2, wherein: One of the input optical path and the output optical path is located closer to the maintenance panel than the optical axis of the pulse laser emitted from the cavity device, and the other of the input optical path and the output optical path is located on the side opposite to the maintenance panel than the optical axis.

4. The gas laser device according to claim 3, wherein The one of the input optical path and the output optical path overlaps with the opening.

5. The gas laser device according to claim 4, wherein The housing further includes an optical tube that covers one of the input optical path and the output optical path and is detachably mounted on the main body.

6. The gas laser device according to claim 1, wherein The pulse stretcher includes a plurality of the annular optical paths.

7. The gas laser device according to claim 6, wherein: The plurality of annular optical paths overlap with each other in a direction parallel to the input optical path.

8. The gas laser device according to claim 6, wherein The plurality of annular optical paths are arranged in a direction non-parallel to the input optical path.

9. The gas laser device according to claim 1, wherein The pulse stretcher further includes a housing, which houses the light guiding optical system and the annular optical path and supports the plurality of light guiding mirrors, the beam splitter, and the plurality of mirrors. The housing is formed with an input hole for inputting the pulse laser light from the cavity device and an output hole for outputting the pulse laser light.

10. The gas laser device according to claim 1, wherein The pulse stretcher is arranged above the optical axis of the pulse laser light emitted from the cavity device.

11. The gas laser device according to claim 1, wherein The pulse stretcher is arranged below the optical axis of the pulse laser light emitted from the cavity device.

12. The gas laser device according to claim 1, wherein The light guiding optical system comprises: a first light guiding reflector for reflecting the pulse laser light incident on the pulse stretcher; and The second light guiding reflection mirror reflects the pulse laser light reflected by the first light guiding reflection mirror and causes the pulse laser light to be emitted from the pulse stretcher.

13. The gas laser device according to claim 12, wherein: The pulse laser incident on the pulse stretcher includes a first linearly polarized light. The pulse laser light incident on the pulse stretcher is incident on the first light guiding mirror so that the first linearly polarized light of the pulse laser light becomes S polarized light. The pulse laser light reflected by the first light guiding reflection mirror enters the second light guiding reflection mirror such that the first linearly polarized light of the pulse laser light becomes S-polarized light.

14. A method for manufacturing an electronic device, comprising the following steps: The pulse laser generated by the gas laser device is output to the exposure device. exposing the pulse laser output to the exposure device on a photosensitive substrate in the exposure device to manufacture an electronic device, The gas laser device comprises: a cavity device including a pair of electrodes in an internal space enclosed with laser gas, and emitting pulsed laser light; and A pulse stretcher comprising an annular optical path and a light guiding optical system, wherein the annular optical path is composed of a beam splitter and a plurality of reflectors, and the light guiding optical system comprises a plurality of light guiding reflectors, wherein the pulse laser emitted from the cavity device is incident on the pulse stretcher. The light guide optical system is configured to allow the pulse laser light incident on the pulse stretcher to be emitted from the pulse stretcher via the beam splitter. The annular optical path is constructed so that a portion of the pulse laser incident on the beam splitter returns to the beam splitter via the multiple mirrors, thereby overlapping with another portion of the pulse laser incident on the beam splitter. The annular optical path is configured to be between a first straight line along an input optical path and a second straight line along an output optical path. The input optical path is the optical path of the pulse laser incident on the pulse stretcher, and the output optical path is the optical path of the pulse laser emitted from the pulse stretcher.

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