Gas laser device and method for manufacturing electronic device

Abstract

To provide a gas laser device capable of suppressing a decrease in the amount of laser light.SOLUTION: A gas laser device includes a chamber device including a pair of electrodes in an internal space filled with laser gas and emitting pulsed laser light, and a pulse stretcher including a loop optical path consisting of a beam splitter and multiple mirrors, and a light-guiding optical system including multiple light-guiding mirrors. The light-guiding optical system is configured such that the pulsed laser light incident on the pulse stretcher is output from the pulse stretcher via the beam splitter. The loop optical path is configured such that a portion of the pulsed laser light incident on the beam splitter is returned to the beam splitter via the multiple mirrors to be superimposed on another portion of the pulsed laser light incident on the beam splitter, and is disposed so as to be sandwiched between a first straight line along an input optical path which is the optical path of the pulsed laser light incident on the pulse stretcher, and a second straight line along an output optical path which is the optical path of the pulsed laser light output from the pulse stretcher.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] In recent years, semiconductor exposure devices have been required to improve their resolution in response to the miniaturization and high integration of semiconductor integrated circuits. To this end, the wavelength of light emitted from exposure light sources has been shortened. For example, KrF excimer laser devices, which output laser light with a wavelength of approximately 248 nm, and ArF excimer laser devices, which output laser light with a wavelength of approximately 193 nm, are used as gas laser devices for exposure.

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

[0004] [Patent Document 1] US Patent Application Publication No. 2022 / 0393420 [Patent Document 2] U.S. Patent No. 6,238,063 Summary of the Invention

[0005] A gas laser device according to one aspect of the present disclosure includes: a chamber device including a pair of electrodes in an internal space in which a laser gas is sealed and which emits pulsed laser light; and a pulse stretcher including a loop optical path consisting of a beam splitter and a plurality of mirrors, and a light-guiding optical system including a plurality of light-guiding mirrors, wherein the light-guiding optical system is configured so that the pulsed laser light incident on the pulse stretcher is output from the pulse stretcher via the beam splitter, and the loop optical path is configured so that a portion of the pulsed laser light incident on the beam splitter is returned to the beam splitter via the plurality of mirrors to be superimposed on another portion of the pulsed laser light incident on the beam splitter, and the loop optical path may be arranged so as to be sandwiched between a first straight line along an input optical path which is the optical path of the pulsed laser light incident on the pulse stretcher, and a straight line along an output optical path which is the optical path of the pulsed laser light output from the pulse stretcher.

[0006] A method for manufacturing an electronic device according to one aspect of the present disclosure may include: a chamber apparatus including a pair of electrodes in an internal space filled with laser gas and emitting pulsed laser light; and a pulse stretcher including a loop optical path consisting of a beam splitter and a plurality of mirrors and a light-guiding optical system including a plurality of light-guiding mirrors, wherein the light-guiding optical system is configured so that the pulsed laser light incident on the pulse stretcher is output from the pulse stretcher via the beam splitter; the loop optical path is configured so that a portion of the pulsed laser light incident on the beam splitter is returned to the beam splitter via the plurality of mirrors to be superimposed on another portion of the pulsed laser light incident on the beam splitter; the gas laser apparatus is disposed so as to be sandwiched between a first straight line along an input optical path that is the optical path of the pulsed laser light incident on the pulse stretcher and a second straight line along an output optical path that is the optical path of the pulsed laser light output from the pulse stretcher; and exposing the pulsed laser light output to the exposure apparatus onto a photosensitive substrate in the exposure apparatus to manufacture an electronic device. [Brief explanation of the drawings]

[0007] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram showing an example of the overall configuration of an electronic device manufacturing apparatus used in an exposure process for an electronic device. [Figure 2] FIG. 2 is a schematic diagram showing an example of the overall configuration of a gas laser device of a comparative example. [Figure 3] FIG. 3 is a schematic diagram showing an example of the schematic configuration of a first light guiding unit, a second light guiding unit, and a pulse stretcher of a comparative example, viewed obliquely from above. [Figure 4] FIG. 4 is a schematic diagram showing an example of the general configuration of the case of the pulse stretcher of the comparative example, viewed obliquely from below. [Figure 5] FIG. 5 is a schematic diagram showing an example of the schematic configuration of a sub-pulse expander of a comparative example. [Figure 6] FIG. 6 is a schematic diagram showing an example of the schematic configuration of a housing of a comparative example. [Figure 7] FIG. 7 is a diagram illustrating a schematic configuration example of the first light guiding unit, the second light guiding unit, and the pulse stretcher according to the first embodiment, similar to FIG. [Figure 8] FIG. 8 is a schematic diagram showing an example of the schematic configuration of the housing of the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating a schematic configuration example of the first light guiding unit, the second light guiding unit, and the pulse stretcher according to the second embodiment, similar to FIG. [Figure 10] FIG. 10 is a diagram illustrating a schematic configuration example of the first light guiding unit, the second light guiding unit, and the pulse stretcher according to the third embodiment, similar to FIG. Embodiment

[0008] 1. Explanation of the electronic device manufacturing equipment used in the exposure process of electronic devices 2. Description of the gas laser device of the comparative example 2.1 Configuration 2.2 Operation 2.3 Challenges 3. Description of the gas laser device of embodiment 1 3.1 Configuration 3.2 Operation 3.3 Actions and Effects 4. Description of the gas laser device of the second embodiment 4.1 Configuration 4.2 Actions and Effects 5. Description of the gas laser device of the third embodiment 5.1 Configuration 5.2 Actions and Effects

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

[0010] 1. Explanation of the electronic device manufacturing equipment used in the exposure process of electronic devices FIG. 1 is a schematic diagram showing an example of the overall configuration of an electronic device manufacturing apparatus used in an exposure process for electronic devices. As shown in FIG. 1, the manufacturing apparatus used in the exposure process includes a gas laser apparatus 100 and an exposure apparatus 200. The exposure apparatus 200 includes an illumination optical system 210, which includes multiple mirrors 211, 212, and 213, and a projection optical system 220. The illumination optical system 210 illuminates a reticle pattern on a reticle stage RT with laser light incident from the gas laser apparatus 100. The projection optical system 220 reduces and projects the laser light transmitted through the reticle onto a workpiece (not shown) placed on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure apparatus 200 synchronously translates the reticle stage RT and the workpiece table WT to expose the workpiece with laser light reflecting the reticle pattern. Semiconductor devices, which are electronic devices, can be manufactured by transferring a device pattern onto a semiconductor wafer using the exposure process described above.

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

[0012] FIG. 2 is a schematic diagram showing an example of the overall configuration of a gas laser apparatus 100 of a comparative example. The gas laser apparatus 100 is, for example, an ArF excimer laser apparatus that uses a mixed gas containing argon (Ar), fluorine (F), and neon (Ne). This gas laser apparatus 100 outputs laser light with a center wavelength of approximately 193 nm. Note that the gas laser apparatus 100 may be a gas laser apparatus other than an ArF excimer laser apparatus, such as a KrF excimer laser apparatus that uses a mixed gas containing krypton (Kr), F, and Ne. In this case, the gas laser apparatus 100 emits laser light with a center wavelength of approximately 248 nm. A mixed gas containing Ar, F, and Ne as a laser medium, or a mixed gas containing Kr, F, and Ne as a laser medium, is sometimes called a laser gas. Note that the mixed gas used in the ArF excimer laser apparatus and the KrF excimer laser apparatus may use helium (He) instead of Ne.

[0013] The gas laser device 100 of this example mainly comprises a housing 110, a laser oscillator 130 which is a master oscillator arranged in the internal space of the housing 110, an optical transmission unit 141, an amplifier 160 which is a power oscillator, a first light-guiding unit 150, a second light-guiding 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.

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

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

[0016] The laser gas is supplied to the internal space of the housing 30 from the laser gas supply device 703 of the gas module 700 via piping, and the laser gas is sealed in the internal space. The internal space is where light is generated by excitation of the laser medium in the laser gas. This light travels to the windows 31a and 31b.

[0017] Window 31a is arranged on the front wall of housing 30 in the traveling direction of laser light from gas laser device 100 to exposure device 200, and window 31b is arranged on the rear wall of housing 30 in the traveling direction. Windows 31a and 31b are calcium fluoride substrates, and the surfaces of windows 31a and 31b facing the inside and outside of housing 30 are flat. Note that windows 31a and 31b are not limited to calcium fluoride substrates as long as they are capable of transmitting laser light.

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

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

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

[0021] The windows 31a and 31b may be tilted at a Brewster angle with respect to the propagation direction of the laser beam so as to suppress reflection of P-polarized light of the laser beam. In this example, the windows 31a and 31b are tilted with respect to a direction perpendicular to the propagation direction of the laser beam and the direction in which the electrodes 32a and 32b face each other. Therefore, the laser beam emitted from the chamber apparatus CH1 contains first linearly polarized light whose polarization direction is perpendicular to the direction in which the electrodes 32a and 32b face each other, and linearly polarized light whose polarization direction is different from that of the first linearly polarized light is reduced from the laser beam. In other words, the windows 31a and 31b are tilted with respect to the polarization direction of the first linearly polarized light, and thus also function as polarizers that reduce linearly polarized light whose polarization direction is different from that of the first linearly polarized light from the laser beam.

[0022] The line narrowing module 60 includes a housing 65, a prism 61, a grating 63, and a rotation stage (not shown) that are arranged in the internal space of the housing 65. An opening is formed in the housing 65, and the housing 65 is connected to the rear side of the housing 30 via the opening.

[0023] Prism 61 expands the beam width of light emitted from window 31b and makes the light incident on grating 63. Prism 61 also reduces the beam width of light reflected from grating 63 and returns the light to the internal space of housing 30 via window 31b. Prism 61 is supported by a rotation stage and rotates by the rotation stage. Rotation of prism 61 changes the angle of incidence of light with respect to grating 63. Therefore, by rotating prism 61, it is possible to select the wavelength of light returning from grating 63 to housing 30 via prism 61. Although FIG. 2 shows an example in which one prism 61 is arranged, two or more prisms may be arranged.

[0024] The surface of the grating 63 is made of a highly reflective material, and numerous grooves are provided at regular intervals on the surface. The grating 63 is a dispersive optical element. The cross-sectional shape of each groove is, for example, a right-angled triangle. Light incident on the grating 63 from the prism 61 is reflected by these grooves and diffracted in a direction according to the wavelength of the light. The grating 63 is Littrow-oriented so that the angle of incidence of the light incident on the grating 63 from the prism 61 matches the angle of diffraction of the diffracted light of the desired wavelength. This allows the light of the desired wavelength to be returned to the housing 30 via the prism 61.

[0025] The output coupling mirror 70 faces the window 31a, transmits a portion of the laser light emitted from the window 31a, and reflects the other portion back into the internal space of the housing 30 via the window 31a. The output coupling mirror 70 is fixed to a holder (not shown), and is disposed in the internal space of the housing 110.

[0026] A Fabry-Perot resonator is formed by the grating 63 and the output coupling mirror 70, which are provided on either side of the housing 30, and the housing 30 is disposed on the optical path of the resonator, so that the resonator resonates light between both sides of the chamber device CH1.

[0027] The optical transmission unit 141 mainly includes high-reflection mirrors 141b and 141c. The high-reflection mirrors 141b and 141c are fixed to holders (not shown) with their respective tilt angles adjusted, and are arranged in the internal space of the housing 110. The high-reflection mirrors 141b and 141c highly reflect the laser light. The high-reflection mirrors 141b and 141c are arranged on the optical path of the laser light from the output coupling mirror 70. The laser light is reflected by the high-reflection mirrors 141b and 141c and travels to the rear mirror 371 of the amplifier 160. At least a portion of this laser light is transmitted through the rear mirror 371.

[0028] The amplifier 160 amplifies the energy of the laser light output from the laser oscillator 130. The basic configuration of the amplifier 160 is generally the same as that of the laser oscillator 130. To distinguish the components of the amplifier 160 from the components of the laser oscillator 130, the chamber device, housing, pair of windows, pair of electrodes, insulating portion, feedthrough, electrode holder portion, charger, pulse power module, and output coupling mirror of the amplifier 160 will be described as a chamber device CH3, housing 330, pair of windows 331a and 331b, pair of electrodes 332a and 332b, insulating portion 333, feedthrough 334, electrode holder portion 336, charger 341, pulse power module 343, and output coupling mirror 370. The electrodes 332a and 332b generate a discharge for amplifying the laser light from the laser oscillator 130. The direction in which the electrodes 332a and 332b face each other is perpendicular to the polarization direction of the first linearly polarized light in the laser light from the laser oscillator .

[0029] The windows 331a and 331b may be tilted with respect to the polarization direction of the first linearly polarized light so that the first linearly polarized light of the laser beam enters as P-polarized light and the incident angle θ of the laser beam is the Brewster angle. By tilting the windows 331a and 331b in this manner, the laser beam emitted from the chamber apparatus CH3 contains the first linearly polarized light and reduces linearly polarized light having a polarization direction different from that of the first linearly polarized light from the laser beam. In other words, like the windows 31a and 31b, the windows 331a and 331b are tilted with respect to the polarization direction of the first linearly polarized light and serve as polarizers that reduce linearly polarized light having a polarization direction different from that of the first linearly polarized light from the laser beam. The outer shape of the laser beam emitted from the windows 331a and 331b may be a rectangle elongated in the direction in which the pair of electrodes 332a and 332b face each other. The pulsed power module 343 is a voltage application circuit, similar to the pulsed power module 43.

[0030] The amplifier 160 differs from the laser oscillator 130 mainly in that it does not include the line narrowing module 60 but includes a rear mirror 371 .

[0031] The rear mirror 371 is provided between the high-reflection mirror 141c and the window 331b and faces 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.

[0032] Output coupling mirror 370 is provided between window 331a and high-reflection mirror 151 and faces them. Output coupling mirror 370 reflects a portion of the laser light amplified and emitted by electrodes 332a, 332b toward the space between electrodes 332a, 332b, and transmits another portion of the laser light toward high-reflection mirror 151. For this reason, the surface of output coupling mirror 370 facing window 331a is coated with a partially reflective film having a predetermined reflectance.

[0033] The output coupling mirror 370 may be circular. The surface of the output coupling mirror 370 facing the window 331a and the surface opposite to that surface are flat. The rear mirror 371 has a similar configuration to the output coupling mirror 70.

[0034] The rear mirror 371 and the output coupling mirror 370, which are disposed on either side of the housing 330, form a resonator that resonates the laser light amplified by the electrodes 332a and 332b. The housing 330 is disposed 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 the laser light is reflected by the output coupling mirror 370. The laser light reflected by the output coupling mirror 370 returns to the internal space of the housing 330 via the 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 internal space of the housing 330 via the window 331b. In this way, the laser light emitted from the housing 330 travels back and forth between the rear mirror 371 and the output coupling mirror 370. The traveling 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 both sides of the chamber device CH3, and the output coupling mirror 370 is disposed on one side of the chamber device CH3. A portion of the amplified laser light is transmitted through the output coupling mirror 370. The laser light that is transmitted through the output coupling mirror 370 proceeds to the high-reflection mirror 151. In this way, the laser light that proceeds from the output coupling mirror 370 to the high-reflection mirror 151 is pulsed laser light.

[0035] 3 is a schematic diagram showing an example of the schematic configuration of the first light-guiding unit 150, the second light-guiding unit 155, and the pulse stretcher 400 of the comparative example, viewed obliquely from above. The first light-guiding unit 150 mainly includes high-reflection mirrors 151 and 152. In the following description, the Z direction is the direction in which the laser light propagates, parallel to the optical axis direction of the laser light exiting the window 331a of the chamber device CH3 and passing through the output-coupling mirror 370, the V direction is the height direction of the gas laser device 100, and the H direction is the direction perpendicular to the V and Z directions. The V direction is perpendicular to the Z direction, generally parallel to the vertical direction, and points upward. Therefore, in this example, the optical axis direction of the laser light exiting the window 331a and passing through the output-coupling mirror 370 is generally parallel to the horizontal direction.

[0036] High-reflection mirrors 151 and 152 are fixed to holders (not shown) with their respective tilt angles adjusted, and highly reflect the laser light. In FIG. 3, the outline of the laser light is indicated by a dotted line, and the polarization direction of the first linearly polarized light in the laser light is indicated by a solid arrow. High-reflection mirror 151 is disposed on the optical path of the laser light from output coupling mirror 370. High-reflection mirror 151 reflects the laser light from output coupling mirror 370 in the -H direction. High-reflection mirror 152 is disposed on the optical path of the laser light reflected by high-reflection mirror 151, and is located on the -H direction side of the optical axis of the laser light passing through output coupling mirror 370. High-reflection mirror 152 reflects the laser light reflected by high-reflection mirror 151 in the V direction, and the laser light enters pulse stretcher 400.

[0037] 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 with the stretched pulse width toward the second light guiding unit 155 .

[0038] The pulse stretcher 400 of this example mainly comprises a light-guiding optical system 410, two loop optical paths 420L and 430L, and a case (not shown), and is disposed on the V-direction side of the optical axis of the laser light transmitted through the output coupling mirror 370. The light-guiding optical system 410 and the loop optical paths 420L and 430L are housed in the case.

[0039] The light-guiding optical system 410 of this example mainly comprises four light-guiding mirrors 411, 412, 413, and 414. The light-guiding mirrors 411, 412, 413, and 414 are each supported on the case of the pulse expander 400 with their respective tilt angles adjusted, and highly reflect the laser light. The light-guiding mirror 411 is located on the −H direction side of the optical axis of the laser light that passes through the output coupling mirror 370, and is arranged on the optical path of the laser light that is reflected by the high-reflection mirror 152 and enters the pulse expander 400. The light-guiding mirror 411 reflects the laser light that enters the pulse expander 400 in the H direction. The light-guiding mirror 412 is located on the optical path of the laser light reflected by the light-guiding mirror 411, and is arranged on the opposite side of the optical axis of the laser light that passes through the output coupling mirror 370 from the light-guiding mirror 411 side. The light-guiding mirror 412 reflects the laser light reflected by the light-guiding mirror 411 in the Z direction. The light-guiding mirror 413 is disposed on the optical path of the laser light reflected by the light-guiding mirror 412. The light-guiding mirror 413 reflects the laser light reflected by the light-guiding mirror 412 in the -H direction. The light-guiding mirror 414 is disposed on the optical path of the laser light reflected by the light-guiding mirror 413, on the -H direction side of the optical axis of the laser light that passes through the output coupling mirror 370. The light-guiding mirror 414 and the light-guiding mirror 411 are aligned in the Z direction. The light-guiding mirror 414 reflects the laser light reflected by the light-guiding mirror 413 in the -V direction, and the laser light is emitted from the pulse expander 400. In the light guiding optical system 410 configured as above, the laser light incident on the pulse stretcher 400 is reflected successively by the plurality of light guiding mirrors 411, 412, 413, and 414, and the laser light is output from the side of the pulse stretcher 400 where the laser light is incident.

[0040] The loop optical path 420L in this example is composed of a beam splitter 421 and six 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-guiding optical system 410, which is reflected by the high-reflection mirror 152, enters the pulse stretcher 400, and proceeds toward the light-guiding mirror 411, and is supported by the case of the pulse stretcher 400. The beam splitter 421 splits the incident laser light into two beams, transmits one of the beams toward the light-guiding mirror 411 so that the beam propagates along the optical path of the light-guiding optical system 410, and reflects the other beam toward the mirror 422.

[0041] Mirrors 422 to 427 are concave mirrors and are supported by the case of pulse expander 400. Mirrors 422, 424, and 426 are arranged on the Z direction side of light-guiding mirrors 411 to 414, and are lined up in the H direction in the order of mirrors 422, 426, and 424. Mirrors 423, 425, and 427 are arranged on the −Z direction side of light-guiding mirrors 411 to 414, and are lined up in the H direction in the order of mirrors 427, 423, and 425. Mirror 422 and mirror 427 face each other in a direction parallel to the Z direction, and beam splitter 421 is located between mirror 422 and mirror 427. Mirror 424 and mirror 425 face each other in a direction parallel to the Z direction, and mirror 426 and mirror 423 face each other in a direction parallel to the Z direction.

[0042] Mirrors 422 to 427 sequentially reflect the laser light reflected by beam splitter 421 back 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 the laser light to enter beam splitter 421 from the surface opposite to the surface onto which the laser light reflected by high-reflection mirror 152 enters. In this way, a loop optical path 420L is formed, which is an optical path of the laser light returning from the beam splitter 421 via the mirrors 422 to 427 to the beam splitter 421, and the loop optical path 420L spreads in the H and Z directions.

[0043] The beam splitter 421 reflects a portion of the laser light that is reflected by the mirror 427 and returns to the beam splitter 421 toward the light guiding mirror 411, and transmits the other portion toward the mirror 422. The transmitted laser light propagates through the loop optical path 420L. In this way, the laser light is reflected six times in the loop optical path 420L to make one circuit, and travels around the loop optical path 420L one or more times.

[0044] The laser light that makes one circuit around the loop optical path 420L, returns to the beam splitter 421, and is split by the beam splitter 421 and heads toward the light-guiding mirror 411 heads from the beam splitter 421 to the light-guiding mirror 411 with a predetermined time delay compared to the laser light that passes through the beam splitter 421 and heads toward the light-guiding mirror 411 without traveling to the mirror 422. The laser light that passes from the beam splitter 421 and heads toward the light-guiding mirror 411 with this predetermined time delay overlaps with a part of the laser light that passes through the beam splitter 421 and heads toward the light-guiding mirror 411 without traveling to the mirror 422. In other words, the laser light that returns to the beam splitter 421 is split into a laser light that overlaps with a part of one of the laser lights split by the beam splitter 421, and laser lights that are reflected sequentially by the mirrors 422 to 427. The laser light is superimposed each time the laser light makes one circuit around the loop optical path 420L, and due to this superposition of the laser light, the laser light with an expanded pulse width travels toward the light-guiding mirror 411 and propagates through the light-guiding optical system 410. In other words, the loop optical path 420L is configured to return a portion of the laser light incident on the beam splitter 421 to the beam splitter 421 via mirrors 422 to 427, and to superimpose this portion on another portion of the laser light incident on the beam splitter 421.

[0045] The loop optical path 430L in this example is composed of a beam splitter 431 and four mirrors 432, 433, 434, and 435. The beam splitter 431 is arranged on the optical path of the laser light in the light-guiding optical system 410, that is reflected by the light-guiding mirror 413 and directed toward the light-guiding mirror 414, and is supported by the case of the pulse expander 400. The beam splitter 431 splits the incident laser light into two beams, transmits one of the beams toward the light-guiding mirror 414 so that the beam propagates along the optical path of the light-guiding optical system 410, and reflects the other beam toward the mirror 432.

[0046] The mirrors 432 to 435 are concave mirrors and are supported by the case of the pulse expander 400. The mirrors 432 and 434 are arranged on the Z direction side of the light-guiding mirrors 411 to 414, and are lined up in the H direction in the order of mirrors 432 and 434. The mirrors 433 and 435 are arranged on the -Z direction side of the light-guiding mirrors 411 to 414, and are lined up in the H direction in the order of mirrors 435 and 433. The mirrors 432 and 435 face each other in a direction parallel to the Z direction, and the beam splitter 431 is located between the mirrors 432 and 435. The mirrors 433 and 434 face each other in a direction parallel to the Z direction. The mirrors 433 and 434 are located on the H direction side of mirrors 422 and 427 of the loop optical path 420L.

[0047] The mirrors 432 to 435 sequentially reflect the laser light reflected by the beam splitter 431 in this order. The mirror 435 reflects the laser light reflected by the mirror 434 toward the beam splitter 431, causing the laser light to enter the beam splitter 431 from a surface opposite to the surface onto which the laser light reflected by the light guiding mirror 413 enters. In this way, a loop optical path 430L is formed, which is an optical path for the laser light that returns to the beam splitter 431 from the beam splitter 431 via the mirrors 432 to 435. The loop optical path 430L extends in the H and Z directions. The optical path length of the loop optical path 430L is shorter than that of the loop optical path 420L. Furthermore, the loop optical path 430L is located above the loop optical path 420L, and the loop optical path 430L and the loop optical path 420L overlap each other in the vertical direction.

[0048] Beam splitter 431 reflects a portion of the laser light that is reflected by mirror 435 and returns to beam splitter 431 toward light-guiding mirror 414, and transmits the other portion toward mirror 432. The transmitted laser light propagates through loop optical path 430L. In this way, the laser light is reflected four times in loop optical path 430L to make one circuit, and travels around loop optical path 430L one or more times.

[0049] In the loop optical path 430L, similarly to the loop optical path 420L, a part of the laser light traveling from the beam splitter 431 to the light-guiding mirror 414 is superimposed with another laser light traveling from the beam splitter 431 to the light-guiding mirror 414 with a predetermined time delay relative to the laser light. This superposition of laser light occurs each time the laser light makes one circuit around the loop optical path 430L. Due to this superposition of laser light, the laser light with an expanded pulse width travels toward the light-guiding mirror 414 and propagates through the light-guiding optical system 410. In other words, the loop optical path 430L is configured to return a part of the laser light incident on the beam splitter 431 to the beam splitter 431 via the mirrors 432 to 435, and superimpose it on another part of the laser light incident on the beam splitter 431.

[0050] The laser light whose pulse width has been expanded by the loop optical paths 420L and 430L in this way is emitted from the pulse expander 400 towards the second light guiding unit 155.

[0051] In this example, the second light guiding unit 155 mainly includes high-reflection mirrors 156 and 157. The high-reflection mirrors 156 and 157 are fixed to holders (not shown) with their respective tilt angles adjusted, and highly reflect the laser light. The high-reflection mirror 156 is disposed on the optical path of the laser light output from the pulse stretcher 400 and is positioned on the −H direction side of the optical axis of the laser light passing through the output coupling mirror 370. The high-reflection mirror 156 and the high-reflection mirror 152 are aligned in the Z direction. The high-reflection mirror 156 reflects the laser light output from the pulse stretcher 400 in the H direction. The high-reflection mirror 157 is disposed on the optical path of the laser light reflected by the high-reflection mirror 156, and the high-reflection mirror 157 and the high-reflection mirror 151 are aligned in the Z direction. The high-reflection mirror 157 reflects the laser light reflected by the high-reflection mirror 156 in the Z direction, and the laser light proceeds to the sub-pulse stretcher 500. The optical axis of the laser light traveling from high-reflection mirror 157 to sub-pulse stretcher 500 may be approximately aligned with the optical axis of the laser light passing through output coupling mirror 370, or the optical axis of the laser light passing through output coupling mirror 370 may be parallel to the optical axis of the laser light traveling to sub-pulse stretcher 500 but shifted in the ±V direction or ±Z direction.

[0052] FIG. 4 is a schematic diagram showing an example of the general configuration of a case 440 of a pulse stretcher 400 of a comparative example, viewed obliquely from below.

[0053] As shown in FIG. 4, the case 440 is a box-shaped member having an internal space, and is supported by a main body portion (described later) of the housing 110. In this example, the case 440 has a rectangular parallelepiped shape that is elongated in the Z direction. An input hole 442 and an output hole 443 are provided in a bottom wall 441 of the case 440, and the input hole 442 and the output hole 443 are aligned in the Z direction. Laser light traveling from the high-reflection mirror 152 toward the light-guiding mirror 411 passes through the input hole 442 and enters the inside of the case 440. Laser light traveling from the light-guiding mirror 414 toward the high-reflection mirror 156 passes through the output hole 443 and exits from the inside of the case 440. Of the optical path of the laser light from the high-reflection mirror 152 toward the light-guiding mirror 411, the section from the input hole 442 to the high-reflection mirror 152 is an input optical path 400Li, which is the optical path of the laser light incident on the pulse stretcher 400, and the input optical path 400Li is approximately parallel to the V direction. Of the optical path of the laser light from the light-guiding mirror 414 toward the high-reflection mirror 156, the section from the output hole 443 to the high-reflection mirror 156 is an output optical path 400Lo, which is the optical path of the laser light output from the pulse stretcher 400, and the output optical path 400Lo is approximately parallel to the V direction. In Figure 3, a first straight line Li along the input optical path 400Li and a second straight line Lo along the output optical path 400Lo are indicated by dashed lines.

[0054] 5 is a schematic diagram showing an example of the schematic configuration of a sub-pulse stretcher 500 of the comparative example. As shown in FIG. 5, sub-pulse stretcher 500 of this example includes a beam splitter 501, four mirrors 511, 512, 513, and 514, and a case (not shown). Beam splitter 501 is disposed on the optical path of the laser light reflected by high-reflection mirror 157 and is supported by the case of sub-pulse stretcher 500. Beam splitter 501 splits the laser light reflected by high-reflection mirror 157 into two beams, reflects one of the split beams toward mirror 511, and transmits the other split laser beam toward beam splitter 171.

[0055] Mirrors 511 to 514 are concave mirrors and are supported on the case of sub-pulse stretcher 500. Mirrors 511 and 513 are arranged on the -V direction side of the optical axis of the laser light reflected by high-reflection mirror 157, and are lined up in the Z direction in the order of mirrors 511 and 513. Mirrors 512 and 514 are arranged on the V direction side of the optical axis of the laser light reflected by high-reflection mirror 157, and are lined up in the Z direction in the order of mirrors 514 and 512. Mirrors 511 and 514 face each other in a direction parallel to the V direction, and beam splitter 501 is located between mirrors 511 and 514. Mirrors 512 and 513 face each other in a direction parallel to the V direction.

[0056] Mirrors 511-514 sequentially reflect the laser light reflected by beam splitter 501 in this order, returning the laser light to beam splitter 501. Because beam splitter 501 is located between mirrors 511-514, the laser light reflected by mirror 514 enters beam splitter 501 from the surface opposite to the surface onto which the laser light reflected by high-reflection mirror 157 enters. In sub-pulse stretcher 500 configured as described above, loop optical path 500L is formed, which is an optical path for the laser light that returns from beam splitter 501 to beam splitter 501 via mirrors 511-514.

[0057] Beam splitter 501 reflects a portion of the laser light that is reflected by mirror 514 and returns to beam splitter 501 toward beam splitter 171, and transmits the other portion toward mirror 511. The transmitted laser light propagates through loop optical path 500L. Thus, in sub-pulse stretcher 500, the laser light is reflected four times in loop optical path 500L to make one circuit, and then travels around loop optical path 500L one or more times.

[0058] In the loop optical path 500L, similarly to the loop optical paths 420L and 430L, a part of the laser light traveling from the beam splitter 501 to the beam splitter 171 is superimposed with another laser light traveling from the beam splitter 501 to the beam splitter 171, the latter being delayed by a predetermined time from the laser light. This superposition of laser light occurs each time the laser light makes one circuit around the loop optical path 430L. Due to this superposition of laser light, the laser light whose pulse width has been expanded is emitted from the sub-pulse expander 500 and proceeds to the detection unit 170.

[0059] The detection unit 170 mainly includes a beam splitter 171 and an optical sensor 172.

[0060] Beam splitter 171 is disposed on the optical path of the laser light output from sub-pulse stretcher 500. Beam splitter 171 transmits the laser light output from sub-pulse stretcher 500 toward output window 173 with high transmittance, and also reflects a portion of the laser light toward the light-receiving surface of optical sensor 172.

[0061] Optical sensor 172 measures the pulse energy of the laser light incident on the light receiving surface of optical sensor 172. Optical sensor 172 is electrically connected to processor 190 and outputs a signal indicating the measured pulse energy to processor 190. Processor 190 controls the voltage applied to electrodes 32a and 32b of amplifier 160 based on the signal.

[0062] An exit window 173 is provided on the wall of the housing 110. The light transmitted through the beam splitter 171 is emitted from the exit window 173 to the exposure device 200 outside the housing 110. This laser light is, for example, a pulsed laser light with a center wavelength of 193.4 nm.

[0063] The display unit 180 is a monitor that displays the state of control by the processor 190 based on a signal from the processor 190. The display unit 180 may be disposed outside the housing 110.

[0064] The processor 190 of the present disclosure is a processing device including a storage device in which a control program is stored and a CPU (Central Processing Unit) that executes the control program. The processor 190 is specially configured or programmed to execute various processes included in the present disclosure. The processor 190 also controls the entire gas laser apparatus 100. The processor 190 is also electrically connected to an exposure processor (not shown) of the exposure apparatus 200, and transmits and receives various signals to and from the exposure processor.

[0065] Gas module 700 includes laser gas exhaust device 701 and laser gas supply device 703. Laser gas exhaust device 701 and laser gas supply device 703 are electrically connected to processor 190 by signal lines (not shown). Laser gas exhaust device 701 includes an exhaust pump (not shown), and in response to a control signal from processor 190, exhausts laser gas from the internal space of housing 30, 330 via piping by suction from the exhaust pump. In response to a control signal from processor 190, laser gas supply device 703 supplies laser gas from a laser gas supply source (not shown) located outside housing 110 to the internal space of housing 30, 330 via piping.

[0066] FIG. 6 is a schematic diagram illustrating an example of the overall configuration of a housing 110 of a comparative example. As shown in FIG. 6, the housing 110 of this example mainly includes a main body 111 and two maintenance panels 115 and 116. The main body 111 is a box-shaped member having an internal space, and various devices such as the laser oscillator 130 and the amplifier 160 described above 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 bottom wall 112 that is elongated in the Z direction, four rectangular side walls 113a to 113d that connect to the four sides of the bottom wall 112, and a rectangular top wall 114 that faces the bottom wall 112 and connects to each of the side walls 113a to 113d. The side walls 113a and 113c face each other in a direction parallel to the Z direction, and the side wall 113a is located closer to the Z direction than the side wall 113c. The sidewalls 113b and 113d face each other in a direction parallel to the H direction, with the sidewall 113b being located closer to the H direction than the sidewall 113d. Two openings 113h1 and 113h2 are formed in the sidewall 113b, arranged vertically, and allow various devices housed in the internal space to be inserted and removed through the openings 113h1 and 113h2. The openings 113h1 and 113h2 have rectangular shapes elongated in the Z direction. In FIG. 6, the chamber devices CH1 and CH3, the processor 190, the pulse stretcher 400, the sub-pulse stretcher 500, the chargers 41 and 341, and the gas module 700 are schematically shown as various devices.

[0067] The maintenance panels 115 and 116 are members that close the openings 113h1 and 113h2. The maintenance panels 115 and 116 are rectangular plate-like members that are elongated in the Z direction, and are detachably attached to the side wall 113b of the main body 111. There are no limitations on the positions, number, shapes, etc. of the openings 113h1 and 113h2.

[0068] As described above, the high-reflection mirror 152 and the light-guiding mirror 411, and the light-guiding mirror 414 and the high-reflection mirror 156 are located on the -H direction side of the optical axis of the laser light that passes through the output coupling mirror 370. The optical axis of the laser light is approximately parallel to the Z direction, and the maintenance panels 115 and 116 are attached to the side wall 113b. Therefore, the input optical path 400Li and the output optical path 400Lo in the pulse stretcher 400 are located on the opposite side of the maintenance panels 115 and 116 from the optical axis of the laser light that passes through the output coupling mirror 370. If the surface of the housing 110 on which the side wall 113d is located is defined as the rear surface, and the position opposite the maintenance panels 115 and 116 is defined as the rear side, the input optical path 400Li and the output optical path 400Lo are located on the rear side of the optical axis of the laser light that passes through the output coupling mirror 370.

[0069] 2.2 Operation Next, the operation of the gas laser device 100 of the comparative example will be described.

[0070] Before gas laser device 100 emits laser light, laser gas is supplied from laser gas supply device 703 to the internal space of housings 30 and 330 .

[0071] When the gas laser apparatus 100 emits laser light, the processor 190 receives a signal indicating the target energy Et and a light emission trigger signal from the exposure processor. The target energy Et is the target value of the laser light energy used in the exposure process. The processor 190 sets a predetermined charging voltage in the charger 41 so that the energy E becomes the target energy Et and turns on the pulse power module 43 in synchronization with the light emission trigger signal. This causes the pulse power module 43 to generate a pulsed high voltage from the electrical energy stored in the charger 41, and the high voltage is applied between the electrodes 32a and 32b. When the high voltage is applied, a discharge occurs between the electrodes 32a and 32b, exciting the laser medium contained in the laser gas between the electrodes 32a and 32b. The laser medium emits light when it returns to its ground state. The emitted light resonates between the grating 63 and the output coupling mirror 70 and is amplified each time it passes through a discharge space within the interior space of the housing 30, resulting in laser oscillation. The laser light contains a first linearly polarized light, and when passing through windows 31 a and 31 b, linearly polarized light having a polarization direction different from the polarization direction of the first linearly polarized light is reduced from the laser light. A part of the laser light passes through output coupling mirror 70, is reflected by high-reflection mirrors 141 b and 141 c, passes through rear mirror 371 and window 331 b, and proceeds into housing 330.

[0072] The processor 190 turns on the switch of the pulse power module 343 so that a discharge occurs when the laser light from the laser oscillator 130 travels into the discharge space in the housing 330. That is, the processor 190 controls the pulse power module 343 so that a high voltage is applied to the electrodes 332a and 332b after a predetermined delay time has elapsed since the switch of the pulse power module 343 was turned on.

[0073] As a result, the laser light incident on amplifier 160 is amplified in amplifier 160. Furthermore, the laser light that has traveled into the internal space of housing 330 passes through windows 331a and 331b and travels to rear mirror 371 and output coupling mirror 370 as described above. In this way, laser light of a predetermined wavelength travels back and forth between rear mirror 371 and output coupling mirror 370. The laser light contains a first linearly polarized light, and when passing through windows 331a and 331b, linearly polarized light having a polarization direction different from the polarization direction 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 inside housing 330, and part of the laser light becomes amplified laser light.

[0074] The amplified laser light from amplifier 160 passes through output coupling mirror 370 and travels to high-reflection mirror 151. This laser light contains first linearly polarized light whose polarization direction is parallel to the H direction, and is incident on high-reflection mirror 151 so that the first linearly polarized light becomes P-polarized light, and is reflected by high-reflection mirror 151 toward high-reflection mirror 152. The laser light reflected by high-reflection mirror 151 is incident on high-reflection mirror 152 so that the first linearly polarized light of the laser light becomes S-polarized light, is reflected by high-reflection mirror 152 in the V direction, and enters pulse stretcher 400.

[0075] The laser beam entering pulse stretcher 400 is incident on light-guiding mirror 411 so that the first linearly polarized light of the laser beam becomes S-polarized light, and is reflected by light-guiding mirror 411 toward light-guiding mirror 412. The laser beam reflected by light-guiding mirror 411 is incident on light-guiding mirror 412 so that the first linearly polarized light of the laser beam becomes P-polarized light, and is reflected by light-guiding mirror 412 toward light-guiding mirror 413. The laser beam reflected by light-guiding mirror 413 is incident on light-guiding mirror 414 so that the first linearly polarized light of the laser beam becomes P-polarized light, is reflected by light-guiding mirror 414, and exits from the lower side of pulse stretcher 400, the side from which the laser beam enters. Furthermore, in pulse stretcher 400, the pulse width of the laser light propagating after being sequentially reflected by light-guiding mirrors 411-414 of light-guiding optical system 410 is stretched by each of loop optical paths 420L and 430L. Then, the laser light with its pulse width stretched is emitted from pulse stretcher 400 and travels to high-reflection mirror 156. This laser light is incident on high-reflection mirror 156 so that the first linearly polarized light of the laser light becomes S-polarized light, and is reflected by high-reflection mirror 156 towards high-reflection mirror 157. The laser light reflected by high-reflection mirror 156 is incident on high-reflection mirror 157 so that the first linearly polarized light of the laser light becomes P-polarized light, is reflected by high-reflection mirror 157 in the Z direction, and enters sub-pulse stretcher 500.

[0076] The pulse width of the laser light incident on the sub-pulse stretcher 500 is stretched by the sub-pulse stretcher 500 , and the laser light with the stretched pulse width proceeds to the beam splitter 171 .

[0077] A part of the laser light that has reached the beam splitter 171 passes through the beam splitter 171 and the exit window 173 and proceeds to the exposure device 200 , and the other part is reflected by the beam splitter 171 and proceeds to the optical sensor 172 .

[0078] The optical sensor 172 measures the energy E of the received laser light. The optical sensor 172 outputs a signal indicating the measured energy E to the processor 190. The processor 190 feedback-controls the charging voltage of the charger 41, 341 so that the difference ΔE between the energy E and the target energy Et falls within an allowable range.

[0079] 2.3 Challenges The pulse stretcher 400 may be positioned based on the input optical path 400Li and the output optical path 400Lo. In this case, if the positions of the mirrors 422-427 and 432-435 that make up the loop optical paths 420L and 430L relative to the input optical path 400Li and the output optical path 400Lo deviate from their designed positions, the performance of the laser light may deviate from the designed value. For this reason, there is a demand for suppressing deviation of the performance of the laser light from the designed value.

[0080] Therefore, in the following embodiment, a gas laser device that can suppress deviation of the performance of laser light from the design value is exemplified.

[0081] 3. Description of the gas laser device of embodiment 1 Next, a description will be given of gas laser device 100 of embodiment 1. Note that the same components as those described above are given the same reference numerals, and redundant description will be omitted unless otherwise specified.

[0082] 3.1 Configuration 7 is a diagram showing a schematic configuration example of the first light-guiding unit 150, the second light-guiding unit 155, and the pulse stretcher 400 of this embodiment, similar to Fig. 3. As shown in Fig. 7, 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 light-guiding mirrors 413 and 414.

[0083] In the light-guiding optical system 410 of this embodiment, the light-guiding mirror 412 reflects the laser light reflected by the light-guiding mirror 411 in the −V direction, and the laser light is emitted from the pulse expander 400 .

[0084] In the loop optical path 420L of this embodiment, the beam splitter 421 is arranged on the optical path of the laser light reflected by the light-guiding mirror 411 and directed toward the light-guiding mirror 412, within the optical path of the laser light in the light-guiding optical system 410. In the loop optical path 430L of this embodiment, the beam splitter 431 is arranged on the −H direction side of the beam splitter 421, within the optical path of the laser light reflected by the light-guiding mirror 411 and directed toward the light-guiding mirror 412. The mirrors 432 and 434 of the loop optical path 430L and the mirrors 422, 426, and 424 of the loop optical path 420L are arranged in the H direction in the order of the mirrors 432, 434, 422, 426, and 424. Furthermore, the mirrors 435 and 433 of the loop optical path 430L and the mirrors 427, 423, and 425 of the loop optical path 420L are arranged in the H direction in the order of mirrors 435, 433, 427, 423, and 425. The loop optical path 420L is located on the H direction side of the loop optical path 430L, and the loop optical paths 430L and 420L are arranged in the H direction. The input optical path 400Li is located on the opposite side of the maintenance panels 115 and 116 from the optical axis of the laser light transmitted through the output coupling mirror 370, and the output optical path 400Lo is located on the maintenance panels 115 and 116 side from the optical axis of the laser light transmitted through the output coupling mirror 370. The loop optical paths 420L and 430L are sandwiched between a first straight line Li along the input optical path 400Li and a second straight line Lo along the output optical path 400Lo.

[0085] In the second light guiding unit 155 of this embodiment, the high-reflection mirror 156 is disposed on the optical path of the laser light output from the pulse stretcher 400, and is located on the −V side of the high-reflection mirror 151. The high-reflection mirror 156 reflects the laser light output from the pulse stretcher 400 in the −H direction. The high-reflection mirror 157 is disposed on the optical path of the laser light reflected by the high-reflection mirror 156. The high-reflection mirror 157 is located on the −V side of the high-reflection mirror 151, and the high-reflection mirror 157 and the high-reflection mirror 151 are aligned in the V direction. The high-reflection mirror 157 reflects the laser light reflected by the high-reflection mirror 156 in the Z direction, and the laser light proceeds to the sub-pulse stretcher 500. The optical axis of the laser light proceeding from the high-reflection mirror 157 to the sub-pulse stretcher 500 is approximately parallel to the optical axis of the laser light passing through the output coupling mirror 370, and is located on the −V side of that optical axis.

[0086] FIG. 8 is a schematic diagram showing an example of a schematic configuration of the housing 110 of this embodiment. The maintenance panel 115 has been removed from the housing 110 shown in FIG. 8. The housing 110 of this embodiment further includes an optical path tube 117. The optical path tube 117 is a cylindrical member extending in a direction parallel to the V direction and covers the output optical path 400Lo. The end of the optical path tube 117 on the case 440 side is detachably attached to the case 440. Since the case 440 is supported by the main body 111 of the housing 110, the optical path tube 117 is detachably attached to the main body 111 via the case 440. Note that the optical path tube 117 may also be detachably attached directly to the main body 111. The optical path tube 117 and the output optical path 400Lo covered by the optical path tube 117 overlap with the opening 113h1.

[0087] 3.2 Operation The laser beam incident on the pulse stretcher 400 is incident on the light-guiding mirror 411 so that the first linearly polarized light of the laser beam becomes S-polarized light, and is reflected by the light-guiding mirror 411 toward the light-guiding mirror 412. The laser beam reflected by the light-guiding mirror 411 is incident on the light-guiding mirror 412 so that the first linearly polarized light of the laser beam becomes S-polarized light, and is reflected by the light-guiding mirror 412 to exit from the lower side of the pulse stretcher 400, which is the side from which the laser beam enters. The pulse width of the laser beam that is reflected successively by the light-guiding mirrors 411 and 412 and propagates is extended by each of the loop optical paths 420L and 430L, and the laser beam with the extended pulse width is emitted from the pulse stretcher 400 and proceeds to the high-reflection mirror 156.

[0088] 3.3 Actions and Effects As described above, the pulse stretcher 400 may be positioned based on the input optical path 400Li and the output optical path 400Lo. For each of the mirrors 422-427 and 432-435 constituting the loop optical paths 420L and 430L, the shorter of the distance from the input optical path 400Li and the distance from the output optical path 400Lo is defined as the specific mirror distance. In this case, as the specific mirror distance increases, the mirrors become farther from the reference input optical path 400Li and output optical path 400Lo, and tend to be more likely to deviate from their designed positions. In the pulse stretcher 400 of this embodiment, the loop optical paths 420L and 430L are positioned so as to be sandwiched between a first straight line Li along the input optical path 400Li and a second straight line Lo along the output optical path 400Lo. Therefore, compared to the pulse stretcher 400 in the comparative example in which the input optical path 400Li and the output optical path 400Lo are located on one side of the loop optical paths 420L and 430L as a reference, the specific distance of the mirror with the longest specific distance among the mirrors 422 to 427 and 432 to 435 can be made shorter. Therefore, according to the gas laser device 100 of this embodiment, it is possible to prevent the positions of the mirrors 422 to 427 and 432 to 435 from shifting from their designed positions, and to prevent the performance of the laser light from shifting from the designed value.

[0089] In the pulse stretcher 400 of this embodiment, the output optical path 400Lo is located on the maintenance panel 115 / 116 side of the optical axis of the laser light emitted from the chamber device CH3 and transmitted through the output coupling mirror 370. The input optical path 400Li is located on the opposite side of the optical axis from the maintenance panel 115 / 116 side. Furthermore, the output optical path 400Lo overlaps with the opening 113h1. Therefore, in this embodiment, the position of the opening 113h1 does not need to be considered when designing the optical path of the laser light from the chamber device CH3 to the outside of the housing 110. Therefore, the gas laser device 100 of this embodiment can prevent the optical path of the laser light from the pulse stretcher 400 to the outside of the housing 110 from becoming complicated, thereby reducing the number of mirrors. This can reduce loss of laser light in the light-guiding optical system 410. The output optical path 400Lo does not need to overlap with the openings 113h1 and 113h2.

[0090] In pulse stretcher 400 of this embodiment, housing 110 includes optical path tube 117 that covers output optical path 400Lo and is detachably attached to main body 111. Therefore, according to gas laser apparatus 100 of this embodiment, it is possible to protect devices such as chamber apparatus CH3 housed in housing 110 while preventing the devices from becoming difficult to put in and take out. Note that housing 110 does not have to include optical path tube 117.

[0091] In the pulse stretcher 400 of this embodiment, the loop optical path 420L and the loop optical path 430L are aligned in a direction parallel to the H direction, which is a direction non-parallel to the input optical path 400Li. Therefore, the gas laser device 100 of this embodiment can prevent the gas laser device 100 from becoming larger in the direction parallel to the input optical path 400Li. Note that the loop optical path 420L and the loop optical path 430L do not have to be aligned in a direction non-parallel to the input optical path 400Li.

[0092] The pulse stretcher 400 of this embodiment includes a case 440. The case 440 houses the light-guiding optical system 410 and the loop 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 case 440 is formed with an input hole 442 through which the laser light from the chamber device CH3 enters and an output hole 443 through which the laser light exits. Since the loop optical paths 420L and 430L are sandwiched between a first straight line Li along the input optical path 400Li and a first straight line Li along the output optical path 400Lo, the distance between the input optical path 400Li and the output optical path 400Lo can be increased. According to the gas laser device 100 of this embodiment, when the pulse stretcher 400 is placed based on the input hole 442 and the output hole 443, the pulse stretcher 400 can be easily aligned, facilitating the placement work. The pulse stretcher 400 does not need to include the case 440. In this case, for example, the plurality of light-guiding mirrors 411, 412, the beam splitters 421, 431, and the plurality of mirrors 422 to 427, 432 to 435 are supported by the main body 111 of the housing 110.

[0093] In the pulse stretcher 400 of this embodiment, the light-guiding optical system 410 is composed of a light-guiding mirror 411 as a first light-guiding mirror and a light-guiding mirror 412 as a second light-guiding mirror. The light-guiding mirror 411 reflects the laser light incident on the pulse stretcher 400, and the light-guiding mirror 412 reflects the laser light reflected by the light-guiding mirror 411 and causes the laser light to exit the pulse stretcher 400. According to the gas laser apparatus 100 of this embodiment, the number of reflections of the laser light can be reduced compared to when the light-guiding optical system 410 is composed of three or more light-guiding mirrors, and a decrease in the amount of the laser light can be suppressed. Note that the light-guiding optical system 410 may further include a light-guiding mirror other than the light-guiding mirrors 411 and 412.

[0094] In the pulse stretcher 400 of this embodiment, the laser beam enters the beam-guiding mirror 411 so that the first linear polarization of the laser beam becomes S-polarized. The laser beam reflected by the beam-guiding mirror 411 enters the beam-guiding mirror 412 so that the first linear polarization of the laser beam becomes S-polarized. The reflectance of S-polarized light tends to be higher than the reflectance of P-polarized light. Therefore, according to the gas laser apparatus 100 of this embodiment, a decrease in the amount of light at the beam-guiding mirrors 411 and 412 can be suppressed compared to, for example, a case where the laser beam enters the beam-guiding mirrors 411 and 412 and is reflected therefrom so that the first linear polarization of the laser beam becomes P-polarized. Therefore, according to the gas laser apparatus 100 of this embodiment, a decrease in the amount of laser light can be suppressed. Note that the laser beam does not necessarily enter the beam-guiding mirrors 411 and 412 so that the first linear polarization of the laser beam becomes S-polarized.

[0095] 4. Description of the gas laser device of the second embodiment Next, a gas laser device 100 according to a second embodiment will be described. The same components as those described above are designated by the same reference numerals, and redundant descriptions will be omitted unless otherwise specified. In addition, in some of the drawings, some components are omitted or simplified for clarity.

[0096] 4.1 Configuration 9 is a diagram illustrating a schematic configuration example of the first light guiding unit 150, the second light guiding unit 155, and the pulse stretcher 400 of this embodiment, similar to Fig. 3. As shown in Fig. 9, the pulse stretcher 400 of this embodiment differs from the pulse stretcher 400 of the first embodiment mainly in that a beam splitter 421 of a loop optical path 420L is arranged on the optical path of the laser light that enters the pulse stretcher 400 and travels toward the light guiding mirror 411.

[0097] In this embodiment, the loop optical path 420L is located on the -V direction side of the loop optical path 430L. The loop optical paths 420L and 430L overlap each other in a direction parallel to the input optical path 400Li. As in the first embodiment, the loop optical paths 420L and 430L are sandwiched between a first straight line Li along the input optical path 400Li and a second straight line Lo along the output optical path 400Lo.

[0098] 4.2 Actions and Effects In the pulse stretcher 400 of this embodiment, as described above, the loop optical path 420L and the loop optical path 430L overlap each other in the direction parallel to the input optical path 400Li. Therefore, the gas laser device 100 of this embodiment can prevent the gas laser device 100 from becoming larger in the direction perpendicular to the input optical path 400Li. Note that the loop optical path 420L and the loop optical path 430L do not have to overlap each other in the direction parallel to the input optical path 400Li.

[0099] 5. Description of the gas laser device of the third embodiment Next, a gas laser device 100 according to a third embodiment will be described. The same components as those described above are designated by the same reference numerals, and redundant descriptions will be omitted unless otherwise specified. In addition, in some of the drawings, some components are omitted or simplified for clarity.

[0100] 5.1 Configuration 10 is a diagram showing a schematic configuration example of the first light-guiding unit 150, the second light-guiding unit 155, and the pulse stretcher 400 of this embodiment, similar to Fig. 3. As shown in Fig. 10, the gas laser apparatus 100 of this embodiment differs from the gas laser apparatus 100 of the first embodiment mainly in that the pulse stretcher 400 is located on the -V direction side, which is below the optical axis of the laser light that is emitted from the chamber apparatus CH3 and transmitted through the output coupling mirror 370.

[0101] In the first light guiding 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 expander 400.

[0102] In the light-guiding optical system 410 of this embodiment, the light-guiding mirror 411 reflects the laser light incident on the pulse stretcher 400 in the H direction. The light-guiding mirror 412 reflects the laser light reflected by the light-guiding 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 case 440 of this embodiment has an input hole 442 and an output hole 443 formed in the top wall of the case 440.

[0103] In the loop optical path 420L of this embodiment, the beam splitter 421 is disposed on the optical path of the laser light in the light-guiding optical system 410, that is reflected by the light-guiding mirror 412 and directed toward the high-reflection mirror 156. The mirrors 422, 424, and 426 are arranged in the order of 422, 426, and 424 in the −H direction, and the mirrors 423, 425, and 427 are arranged in the order of 427, 423, and 425 in the −H direction.

[0104] In the loop optical path 430L of this embodiment, the beam splitter 431 is disposed on the optical path of the laser light reflected by the light-guiding mirror 411 and directed toward the light-guiding mirror 412, among the optical paths of the laser light in the light-guiding optical system 410. The mirrors 432 and 434 are arranged in the order of the mirrors 432 and 434 in the -H direction, and the mirrors 433 and 435 are arranged in the order of the mirrors 435 and 433 in the -H direction.

[0105] The loop optical path 420L is located on the V-direction side of the loop optical path 430L. The loop optical paths 420L and 430L overlap each other in a direction parallel to the input optical path 400Li. As in the first embodiment, the loop optical paths 420L and 430L are sandwiched between a first straight line Li along the input optical path 400Li and a second straight line Lo along the output optical path 400Lo.

[0106] In the second light guiding unit 155 of this embodiment, the high-reflection mirror 156 is disposed on the optical path of the laser light output from the pulse stretcher 400, and is located on the V-direction side of the optical axis of the laser light passing through the output coupling mirror 370. The high-reflection mirror 156 reflects the laser light output from the pulse stretcher 400 in the -H direction. The high-reflection mirror 157 is disposed on the optical path of the laser light reflected by the high-reflection mirror 156. The high-reflection mirror 157 is located on the V-direction side of the high-reflection mirror 151, and the high-reflection mirrors 151 and 157 are aligned in the V direction. The high-reflection mirror 157 reflects the laser light reflected by the high-reflection mirror 156 in the Z-direction, and the laser light proceeds to the sub-pulse stretcher 500. The optical axis of the laser light proceeding from the high-reflection mirror 157 to the sub-pulse stretcher 500 is approximately parallel to the optical axis of the laser light passing through the output coupling mirror 370 and is located on the V-direction side of the optical axis.

[0107] 5.2 Actions and Effects The pulse stretcher 400 of this embodiment is disposed on the −V direction side below the optical axis of the laser light emitted from the chamber device CH3 and transmitted through the output coupling mirror 370. The gas laser device 100 of this embodiment can prevent the pulse stretcher 400 from being positioned too high, compared to when the pulse stretcher 400 is disposed above the optical axis, which can facilitate maintenance of the pulse stretcher 400, for example. The position of the pulse stretcher 400 relative to the optical axis is not limited.

[0108] Although the above embodiments have been described as examples, the present disclosure is not limited to these and can be modified as appropriate.

[0109] In each of the above embodiments, the pulse stretcher 400 includes two loop optical paths 420L and 430L. However, the number of loop optical paths is not limited.

[0110] Furthermore, in the above embodiments, the loop optical path 420L consisting of the beam splitter 421 and six mirrors 422 to 427 and the loop optical path 430L consisting of the beam splitter 431 and four mirrors 432 to 435 have been described as examples. However, the number of mirrors constituting the loop optical path is not limited.

[0111] In addition, in each of the above embodiments, the first light-guiding unit 150 includes two high-reflection mirrors 151, 152, and the second light-guiding unit 155 includes two high-reflection mirrors 156, 157. However, the number of high-reflection mirrors included in the first light-guiding unit 150 and the second light-guiding unit 155 is not limited as long as the laser light output from the chamber device CH3 is incident on the pulse stretcher 400. Furthermore, the gas laser device 100 does not have to include at least one of the first light-guiding unit 150 and the second light-guiding unit 155.

[0112] In addition, in each of the above embodiments, the pulse stretcher 400 in which the input optical path 400Li and the output optical path 400Lo are substantially parallel to the vertical direction has been described as an example. However, at least one of the input optical path 400Li and the output optical path 400Lo may be non-parallel to the vertical direction.

[0113] Furthermore, in each of the above embodiments, the beam splitters 421 and 431 have been described as examples in which reflected laser light propagates to the loop optical paths 420L and 430L. However, laser light that passes through the beam splitters 421 and 431 may propagate to the loop optical paths 420L and 430L. In this case, the beam splitters 421 and 431 are part of the light-guiding optical system 410, and the light-guiding optical system 410 and the loop optical paths 420L and 430L share the beam splitters 421 and 431.

[0114] Furthermore, in the above-described embodiments, the pulse stretcher 400 has been described with reference to an example in which the output optical path 400Lo is located on the maintenance panel 115, 116 side of the optical axis of the laser light that is emitted from the chamber device CH3 and transmitted through the output coupling mirror 370. However, the input optical path 400Li may be located on the maintenance panel 115, 116 side of 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, it may not be necessary to consider the position of the opening 113h1 when designing the optical path of the laser light from the chamber device CH3 to the pulse stretcher 400. This can prevent this optical path from becoming complicated.

[0115] Furthermore, in each of the above embodiments, the pulse stretcher 400 is housed in the main body 111 of the housing 110. However, the pulse stretcher 400 may be disposed outside the housing 110.

[0116] Furthermore, in each of the above embodiments, the gas laser apparatus 100 is described as including the laser oscillator 130 and the amplifier 160. However, the gas laser apparatus 100 does not have to include the amplifier 160. In this case, for example, the laser light emitted from the chamber apparatus CH1 and transmitted through the output coupling mirror 70 is incident on the pulse stretcher 400.

[0117] The above description is intended to be illustrative, not limiting. Accordingly, it will be apparent to those skilled in the art that modifications can be made to the embodiments of the present disclosure without departing from the scope of the claims. It will also be apparent to those skilled in the art that the embodiments of the present disclosure can be used in combination. Terms used throughout this specification and claims should be construed as "open-ended" terms unless expressly stated. For example, terms such as "comprise," "have," "comprise," and "equip" should be interpreted as meaning "without excluding the presence of elements other than those listed." The modifier "a" or "an" should be interpreted as meaning "at least one" or "one or more." The term "at least one of A, B, and C" should be interpreted as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C," including combinations other than "A," "B," and "C."

Claims

1. a chamber device including a pair of electrodes in an internal space in which a laser gas is sealed, and which emits pulsed laser light; a pulse extender including a loop optical path including a beam splitter and a plurality of mirrors, and a light guiding optical system including a plurality of light guiding mirrors, into which the pulsed laser light emitted from the chamber device is incident; Equipped with the light-guiding optical system is configured so that the pulsed laser light incident on the pulse stretcher is output from the pulse stretcher via the beam splitter, The loop optical path is configured to return a portion of the pulsed laser beam incident on the beam splitter to the beam splitter via the plurality of mirrors, thereby superimposing the portion on another portion of the pulsed laser beam incident on the beam splitter, and is disposed so as to be sandwiched between a first straight line along an input optical path, which is an optical path of the pulsed laser beam incident on the pulse stretcher, and a second straight line along an output optical path, which is an optical path of the pulsed laser beam output from the pulse stretcher. Gas laser device.

2. 2. The gas laser device according to claim 1, The apparatus further includes a housing including a main body portion that houses the chamber device and has an opening through which the chamber device can be taken in and out, and a maintenance panel that closes the opening and is detachably attached to the main body portion.

3. 3. The gas laser device according to claim 2, One of the input optical path and the output optical path is located on the maintenance panel side of the optical axis of the pulsed laser light emitted from the chamber device, and the other of the input optical path and the output optical path is located on the opposite side of the optical axis from the maintenance panel side.

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

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

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

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

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

9. 2. The gas laser device according to claim 1, the pulse stretcher further includes a case that houses the light-guiding optical system and the loop optical path and supports the plurality of light-guiding mirrors, the beam splitter, and the plurality of mirrors; The case is formed with an input hole through which the pulsed laser light from the chamber device enters and an output hole through which the pulsed laser light exits.

10. 2. The gas laser device according to claim 1, The pulse stretcher is disposed above the optical axis of the pulsed laser beam emitted from the chamber device.

11. 2. The gas laser device according to claim 1, The pulse stretcher is disposed below the optical axis of the pulsed laser beam emitted from the chamber device.

12. 2. The gas laser device according to claim 1, The light-guiding optical system includes a first light-guiding mirror that reflects the pulsed laser light that enters the pulse stretcher, and a second light-guiding mirror that reflects the pulsed laser light reflected by the first light-guiding mirror and causes the pulsed laser light to exit the pulse stretcher.

13. 13. The gas laser device of claim 12, the pulsed laser light incident on the pulse stretcher includes a first linearly polarized light; the pulsed laser light is incident on the first light guiding mirror such that the first linearly polarized light of the pulsed laser light incident on the pulse stretcher becomes S-polarized light; The pulsed laser light reflected by the first light guiding mirror is incident on the second light guiding mirror such that the first linearly polarized light of the pulsed laser light becomes S-polarized light.

14. a chamber device including a pair of electrodes in an internal space in which a laser gas is sealed, and which emits pulsed laser light; a pulse extender including a loop optical path including a beam splitter and a plurality of mirrors, and a light guiding optical system including a plurality of light guiding mirrors, into which the pulsed laser light emitted from the chamber device is incident; Equipped with the light-guiding optical system is configured so that the pulsed laser light incident on the pulse stretcher is output from the pulse stretcher via the beam splitter, the loop optical path is configured to return a portion of the pulsed laser beam incident on the beam splitter via the plurality of mirrors to the beam splitter, thereby superimposing the portion on another portion of the pulsed laser beam incident on the beam splitter, and outputs pulsed laser beams generated by a gas laser device disposed so as to be sandwiched between a first straight line along an input optical path that is an optical path of the pulsed laser beam incident on the pulse stretcher and a second straight line along an output optical path that is an optical path of the pulsed laser beam output from the pulse stretcher, to an exposure device; exposing a photosensitive substrate in the exposure apparatus with the pulsed laser light output to the exposure apparatus in order to manufacture an electronic device. A method for manufacturing an electronic device, comprising:

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