Laser device, optical path adjustment method, and electronic device manufacturing method

Abstract

A laser device according to one aspect of the present disclosure comprises: an oscillator that emits laser light; an amplifier that amplifies the laser light inside a chamber containing a pair of discharge electrodes; a front-side optical system and a rear-side optical system arranged at opposing positions across the chamber to form a ring resonator including a first light path and a second light path that intersect each other between the pair of discharge electrodes; a front-side observation device for observing the first light path and the second light path between the front-side optical system and the chamber; and a rear-side observation device for observing the first light path and the second light path between the rear-side optical system and the chamber. The first light path is a light path on which the front-side optical system emits the laser light incident from the oscillator toward the rear-side optical system. The second light path is a light path on which the rear-side optical system emits the laser light incident via the first light path toward the front-side optical system.

Description

[Technical Field]

[0001] The present disclosure relates to a laser device, an optical path adjusting method, and a method for manufacturing an electronic device. [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 from KrF excimer laser devices and ArF excimer laser devices is as wide as 350 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 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] Summary of Japanese Patent Application Laid-open No. 63-054791

[0005] A laser device according to one aspect of the present disclosure includes an oscillator that emits laser light, an amplifier that amplifies the laser light in a chamber including a pair of discharge electrodes, a front-side optical system and a rear-side optical system that are arranged at opposing positions across the chamber and form a ring resonator including a first optical path and a second optical path that intersect between the pair of discharge electrodes, a front-side observation device for observing the first optical path and the second optical path between the front-side optical system and the chamber, and a rear-side observation device for observing the first optical path and the second optical path between the rear-side optical system and the chamber, wherein the first optical path is an optical path along which the front-side optical system emits laser light incident from the oscillator toward the rear-side optical system, and the second optical path is an optical path along which the rear-side optical system emits laser light incident via the first optical path toward the front-side optical system.

[0006] An optical path adjustment method according to one aspect of the present disclosure includes: an oscillator that emits laser light; an amplifier that amplifies the laser light in a chamber including a pair of discharge electrodes; a front-side optical system and a rear-side optical system that are arranged at opposite positions across the chamber and that form a ring resonator including a first optical path and a second optical path that intersect between the pair of discharge electrodes; a front-side observation device that observes the first optical path and the second optical path between the front-side optical system and the chamber; and a rear-side observation device that observes the first optical path and the second optical path between the rear-side optical system and the chamber, wherein the first optical path is is an optical path through which the laser light incident from the oscillator is output toward the rear-side optical system, and the second optical path is an optical path through which the rear-side optical system outputs the laser light incident via the first optical path toward the front-side optical system, the method for adjusting the optical path of a laser device including: adjusting the rear-side optical system by observing the first optical path and the second optical path using a rear-side observation device; adjusting the rear-side optical system by observing the first optical path and the second optical path using a front-side observation device; and adjusting the front-side optical system by observing the optical path of the laser light output from the amplifier.

[0007] A method for manufacturing an electronic device according to one aspect of the present disclosure includes: an oscillator that emits laser light; an amplifier that amplifies the laser light in a chamber including a pair of discharge electrodes; a front-side optical system and a rear-side optical system that are arranged at opposing positions across the chamber and form a ring resonator including a first optical path and a second optical path that intersect between the pair of discharge electrodes; a front-side observation device for observing the first optical path and the second optical path between the front-side optical system and the chamber; and a rear-side observation device for observing the first optical path and the second optical path between the rear-side optical system and the chamber, wherein the first optical path is an optical path along which the front-side optical system emits laser light incident from the oscillator toward the rear-side optical system, and the second optical path is an optical path along which the rear-side optical system emits laser light incident via the first optical path toward the front-side optical system; the method includes generating laser light using a laser apparatus, outputting the laser light to an exposure apparatus, and exposing a photosensitive substrate with the laser light in the exposure apparatus to manufacture an electronic device. [Brief explanation of the drawings]

[0008] 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 top view schematically showing an example of the configuration of a laser device according to a comparative example. [Figure 2] FIG. 2 is a side view schematically illustrating an example of the configuration of a master oscillator according to a comparative example. [Figure 3] FIG. 3 is a top view schematically showing the initial state of the optical path adjustment according to the comparative example. [Figure 4] FIG. 4 is a diagram schematically showing a beam profile observed by a beam profiler. [Figure 5] FIG. 5 is a top view schematically showing an example of the configuration of the laser device according to the first embodiment. [Figure 6] FIG. 6 is a side view schematically illustrating an example of the configuration of the power oscillator according to the first embodiment. [Figure 7] FIG. 7 is a perspective view schematically showing an example of the configuration of a front-side observation device. [Figure 8] FIG. 8 is a perspective view schematically showing an example of the configuration of a rear-side observation device. [Figure 9] FIG. 9 is a diagram for explaining the function of the position adjusting stage provided in the rear optical system. [Figure 10] FIG. 10 is a diagram for explaining the action of the actuator provided in the rear optical system. [Figure 11] FIG. 11 is a flowchart showing an example of a procedure for adjusting the optical path in the first embodiment. [Figure 12] FIG. 12 is a top view schematically illustrating an example of the configuration of a laser device according to the second embodiment. [Figure 13] FIG. 13 is a perspective view schematically showing the configuration of an MO beam steering unit according to a modified example. [Figure 14] FIG. 14 is a diagram schematically illustrating a configuration of a master oscillator according to a modified example. [Figure 15] FIG. 15 is a diagram schematically showing an example of the configuration of an exposure apparatus. Embodiment

[0009] <Contents> 1. Comparative Example 1.1 Configuration 1.2 Operation 1.3 Optical path adjustment 1.4 Challenges 2. First embodiment 2.1 Configuration 2.2 Operation 2.3 Optical path adjustment 2.4 Effects 3. Second embodiment 3.1 Configuration 3.2 Operation 3.3 Optical path adjustment 3.4 Effects 4. MO beam steering unit variants 5. Master Oscillator Variations 5.1 Configuration 5.2 Operation 5.3 Other 6. Modifications of the front-side observation device and the rear-side observation device 7. Electronic Device Manufacturing Method

[0010] 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.

[0011] 1. Comparative Example The comparative examples of the present disclosure are forms that the applicant recognizes as being known only by the applicant, and are not publicly known examples that the applicant acknowledges.

[0012] 1.1 Configuration FIG. 1 shows a schematic configuration example of a laser device 2 according to a comparative example. In FIG. 1, the height direction of the laser device 2 is defined as the V-axis direction, the length direction as the Z-axis direction, and the depth direction as the H-axis direction. The V-axis direction may be parallel to the direction of gravity, and the direction opposite to the direction of gravity is defined as the "+V-axis direction." The emission direction of the laser light Lp emitted from the laser device 2 is defined as the "+Z-axis direction." The direction toward the front of the paper surface of FIG. 1 is defined as the "+V-axis direction."

[0013] The laser device 2 includes a master oscillator (MO) 10, an MO beam steering unit 20, and a power oscillator (PO) 30. The master oscillator 10 is an example of an "oscillator" according to the technology of the present disclosure. The MO beam steering unit 20 is an example of a "beam steering device" according to the technology of the present disclosure. The power oscillator 30 is an example of an "amplifier" according to the technology of the present disclosure.

[0014] The MO beam steering unit 20 is arranged on the optical path of the laser light Lp between the master oscillator 10 and the power oscillator 30, and enables adjustment of the position and angle of the optical path of the laser light Lp incident on the power oscillator 30.

[0015] The MO beam steering unit 20 includes two high-reflection mirrors 21a and 21b. The high-reflection mirrors 21a and 21b are arranged so that the laser light Lp emitted from the master oscillator 10 is incident on the power oscillator 30. The laser light Lp emitted from the master oscillator 10 is a pulsed laser light. An actuator (not shown) is attached to each of the high-reflection mirrors 21a and 21b to change their position. For example, the actuator allows tilt adjustment in the left-right and up-down directions.

[0016] The high-reflection mirror in this disclosure is a flat mirror in which a high-reflection film is formed on the surface of a substrate made of, for example, synthetic quartz or calcium fluoride (CaF2). The high-reflection film is a dielectric multilayer film, for example, a film containing fluoride.

[0017] The power oscillator 30 includes a chamber 32, a front-side optical system 35, and a rear-side optical system 36. The front-side optical system 35 is disposed on the light incident side where the laser light Lp enters the power oscillator 30 from the MO beam steering unit 20. The rear-side optical system 36 is disposed at a position opposite the front-side optical system 35 with the chamber 32 in between.

[0018] Chamber 32 is disposed on the optical path of the ring resonator. Chamber 32 is filled with laser gas. The laser gas may contain, for example, Ar gas or Kr gas as a rare gas, F gas as a halogen gas, and Ne gas as a buffer gas.

[0019] The chamber 32 includes a pair of discharge electrodes 33a, 33b and two windows 34a, 34b through which the laser light Lp passes. The pair of discharge electrodes 33a, 33b are arranged to face each other in the V-axis direction.

[0020] The windows 34a and 34b are arranged so that the incident angle of the laser light Lp is close to the Brewster angle, and the windows 34a and 34b are arranged so that the polarization state of the laser light Lp is P-polarized.

[0021] A slit member 37 having a slit 37a and a slit member 38 having a slit 38a are provided inside the chamber 32. The slit member 37 is disposed between the pair of discharge electrodes 33a, 33b and the window 34a so that the laser light Lp passes through the slit 37a. The slit member 38 is disposed between the pair of discharge electrodes 33a, 33b and the window 34b so that the laser light Lp passes through the slit 38a. The slit members 37, 38 suppress stray light and prevent dust generated in the discharge space from adhering to the windows 34a, 34b.

[0022] The front-side optical system 35 includes an output coupling mirror 40 and a high-reflection mirror 41. The output coupling mirror 40 is disposed on the optical path of the laser light Lp incident from the MO beam steering unit 20 so that the laser light Lp is incident at a predetermined angle of incidence.

[0023] The output coupling mirror 40 is a partial reflection mirror with a reflectance in the range of 10% to 30%, for example. The output coupling mirror 40 has a first surface 40a and a second surface 40b that face each other. The first surface 40a and the second surface 40b are parallel to the V-axis direction, which is the discharge direction of the pair of discharge electrodes 33a, 33b.

[0024] The output coupling mirror 40 transmits and partially reflects the laser light Lp incident on the first surface 40a from the MO beam steering unit 20. The output coupling mirror 40 also transmits and partially reflects the laser light Lp incident on the second surface 40b from the high-reflection mirror 41. The portion of the laser light Lp that has transmitted through the output coupling mirror 40 is emitted from the front-side optical system 35 to the outside of the power oscillator 30. The portion of the laser light Lp that has been reflected by the second surface 40b of the output coupling mirror 40 enters the chamber 32.

[0025] The high-reflection mirror 41 has a high-reflection surface 41a on which a high-reflection film is formed. The output coupling mirror 40 and the high-reflection mirror 41 are arranged so that the second surface 40b and the high-reflection surface 41a face each other at a predetermined angle. The high-reflection mirror 41 reflects the laser light Lp, which is incident from the rear-side optical system 36 via the chamber 32, toward the second surface 40b of the output coupling mirror 40 by the high-reflection surface 41a.

[0026] Actuators 42 and 43 for changing the attitude are attached to the high-reflection mirror 41 and the output coupling mirror 40. For example, the actuators 42 and 43 enable tilt adjustment in the left-right and up-down directions.

[0027] The rear optical system 36 includes a first high-reflection mirror 50 and a second high-reflection mirror 51. The first high-reflection mirror 50 has a high-reflection surface 50a on which a high-reflection film is formed. The second high-reflection mirror 51 has a high-reflection surface 51a on which a high-reflection film is formed. The high-reflection surfaces 50a and 51a are parallel to the V-axis direction. The first high-reflection mirror 50 and the second high-reflection mirror 51 are arranged so that the high-reflection surfaces 50a and 51a face each other at a predetermined angle.

[0028] The first high-reflection mirror 50 reflects the laser light Lp incident thereon from the front-side optical system 35 via the chamber 32 at its high-reflection surface 50a toward the second high-reflection mirror 51. The second high-reflection mirror 51 reflects the laser light Lp incident thereon from the first high-reflection mirror 50 toward the chamber 32 at its high-reflection surface 51a.

[0029] The front-side optical system 35 and the rear-side optical system 36 form a ring resonator including a first optical path P1 and a second optical path P2 that intersect between the pair of discharge electrodes 33 a, 33 b. The first optical path P1 and the second optical path P2 are close to each other in the discharge space between the pair of discharge electrodes 33 a, 33 b.

[0030] The first optical path P1 is composed of an output coupling mirror 40 and a first high-reflection mirror 50. The second optical path P2 is composed of a second high-reflection mirror 51 and a high-reflection mirror 41. The first optical path P1 is an optical path along which the front-side optical system 35 emits the laser light Lp incident from the master oscillator 10 toward the rear-side optical system 36. The second optical path P2 is an optical path along which the rear-side optical system 36 emits the laser light Lp incident via the first optical path P1 toward the front-side optical system 35.

[0031] That is, the first optical path P1 is an outgoing path from the front-side optical system 35 to the rear-side optical system 36 via the chamber 32. The second optical path P2 is a returning path from the rear-side optical system 36 to the front-side optical system 35 via the chamber 32. The first optical path P1 and the second optical path P2 are included in a plane perpendicular to the V-axis direction, which is the discharge direction caused by the pair of discharge electrodes 33a, 33b.

[0032] A beam profiler 60 for observing the beam profile of the laser light Lp is provided in the optical path of the laser light Lp emitted from the power oscillator 30. For example, the beam profiler 60 is configured by an ultraviolet camera that captures an image of the beam profile of the laser light Lp. The beam profiler 60 is configured to be retractable from the optical path of the laser light Lp. The beam profiler 60 may be detachable from the power oscillator 30. Instead of the ultraviolet camera, the beam profiler 60 may include a fluorescent screen that converts the laser light Lp into visible light and a visible light camera that captures an image of the fluorescent screen.

[0033] 2 is a schematic diagram illustrating a configuration example of a master oscillator 10 according to a comparative example. The master oscillator 10 includes a line narrowing module 11, a chamber 14, and an output coupling mirror (OC) 17.

[0034] The line narrowing module 11 includes a prism beam expander 12 for narrowing the spectral linewidth, and a grating 13. The prism beam expander 12 and the grating 13 are arranged in a Littrow configuration so that the angle of incidence and the angle of diffraction match.

[0035] The output coupling mirror 17 is, for example, a reflecting mirror having a reflectance in the range of 40% to 60%. The output coupling mirror 17 and the line narrowing module 11 form an optical resonator.

[0036] The chamber 14 is disposed on the optical path of the optical resonator. The chamber 14 includes a pair of discharge electrodes 15a, 15b and two windows 16a, 16b through which the laser light Lp passes. The chamber 14 is filled with a laser gas.

[0037] The windows 16a and 16b are arranged so that the incident angle of the laser light Lp is close to the Brewster angle, and the windows 16a and 16b are arranged so that the polarization state of the laser light Lp is P-polarized.

[0038] 1.2 Operation When a discharge occurs in the chamber 14 of the master oscillator 10, the laser gas is excited, and laser light Lp, which has been narrowed in line by an optical resonator formed by the output coupling mirror 17 and the line narrowing module 11, is emitted from the output coupling mirror 17. This laser light Lp passes through the MO beam steering unit 20 and enters the front optical system 35 of the power oscillator 30 as seed light.

[0039] The laser light Lp that enters the front-side optical system 35 passes through the output coupling mirror 40 and enters the inside of the ring resonator. The laser light Lp that has passed through the output coupling mirror 40 travels along the first optical path P1 and enters the chamber 32. A discharge occurs in the discharge space in synchronization with the timing at which the laser light Lp enters the chamber 32. As a result, the laser gas is excited and the laser light Lp is amplified. The amplified laser light Lp is emitted from the chamber 32 and travels along the first optical path P1, and then enters the rear-side optical system 36.

[0040] The laser light Lp that entered the rear-side optical system 36 is reflected by the first high-reflection mirror 50 and the second high-reflection mirror 51, causing its traveling direction to be folded back, and is then emitted from the rear-side optical system 36. The laser light Lp that has been emitted from the rear-side optical system 36 travels along the second optical path P2 and enters the chamber 32. The laser light Lp that has entered the chamber 32 is amplified again in the discharge space and emitted from the chamber 32. The laser light Lp that has been emitted from the chamber 32 travels along the second optical path P2, and then enters the front-side optical system 35.

[0041] The laser light Lp incident on the front-side optical system 35 is reflected by the high-reflection mirror 41 toward the output-coupling mirror 40. A portion of the laser light Lp incident on the output-coupling mirror 40 passes through the output-coupling mirror 40 and is emitted from the front-side optical system 35 to the outside of the power oscillator 30.

[0042] Furthermore, the remaining portion of the laser light Lp that is incident on the output coupling mirror 40 is reflected by the output coupling mirror 40 and is emitted from the front-side optical system 35 toward the chamber 32. That is, the traveling direction of the remaining portion of the laser light Lp is turned back by the front-side optical system 35. The laser light Lp whose traveling direction has been turned back travels again along the first optical path P1 and enters the chamber 32. In this way, the portion of the laser light Lp repeatedly circulates around the ring resonator including the first optical path P1 and the second optical path P2. The laser light Lp is amplified and oscillated by passing through the discharge space multiple times within one discharge time.

[0043] The laser light Lp emitted from the power oscillator 30 travels along an optical path in which the beam profiler 60 is disposed, and is output from the laser device 2. When the laser device 2 is in operation, the beam profiler 60 is retracted from the optical path of the laser light Lp emitted from the power oscillator 30a.

[0044] 1.3 Optical path adjustment Next, the optical path adjustment performed in the preparation stage before operating the laser device 2 according to the comparative example will be described.

[0045] 3 shows a schematic diagram of the initial state of optical path adjustment according to the comparative example. First, in preparation, an operator removes the power oscillator 30 from the laser device 2. Next, the operator places a pair of slit members 71 and 72 for adjustment, spaced apart by a certain distance, on the optical path of the laser light Lp expected to be emitted from the MO beam steering unit 20. Slit members 71 and 72 have slits 71a and 72a formed therein, respectively.

[0046] Next, the operator operates master oscillator 10 to emit laser beam Lp. The operator adjusts the attitudes of high-reflection mirrors 21a and 21b of MO beam steering unit 20 so that laser beam Lp emitted from MO beam steering unit 20 passes through slits 71a and 72a, respectively. This completes the adjustment of the optical path of laser beam Lp emitted from MO beam steering unit 20.

[0047] With the operation of the master oscillator 10 stopped, the worker removes the slits 71a and 72a from the laser device 2 and attaches the power oscillator 30 to the laser device 2. Then, with the master oscillator 10 and the power oscillator 30 operating, the worker adjusts the attitudes of the output coupling mirror 40 and the high-reflection mirrors 41, 50, and 51 by operating the actuators 42, 43, 52, and 53 while observing the beam profile with the beam profiler 60. Note that the actuator in the present disclosure is, for example, a mirror holder with a two-axis actuator.

[0048] Fig. 4 schematically shows a beam profile observed by the beam profiler 60. In Fig. 4, Lp0 represents the laser light Lp that enters the output coupling mirror 40 from the MO beam steering unit 20 and is partially reflected by the first surface 40a, and is then emitted from the power oscillator 30. Lp1 represents the laser light Lp that circulates once around the ring resonator and is then emitted from the power oscillator 30. Lp2 represents the laser light Lp that circulates twice around the ring resonator and is then emitted from the power oscillator 30. Lp3 represents the laser light Lp that circulates three times around the ring resonator and is then emitted from the power oscillator 30.

[0049] In the present disclosure, for the sake of simplicity, it is assumed that four laser beams Lp0 to Lp3 with different numbers of revolutions are emitted from the power oscillator 30 in response to one pulse of laser beam Lp being incident on the power oscillator 30. Furthermore, when it is not necessary to distinguish between the four laser beams Lp0 to Lp3, they are simply referred to as laser beams Lp.

[0050] Beam profiles BP0 to BP3 of the laser beams Lp0 to Lp3 are observed by the beam profiler 60. While observing the degree of overlap of the beam profiles BP0 to BP3, the operator adjusts the attitudes of the output coupling mirror 40 and the high-reflection mirrors 41, 50, and 51 so that the beam profiles BP0 to BP3 completely overlap. This completes the adjustment of the first optical path P1 and the second optical path P2 included in the ring resonator.

[0051] 1.4 Challenges In the power oscillator 30, the amplification efficiency of the laser light Lp changes depending on the relative positional relationship between the intersecting first optical path P1 and second optical path P2 and the discharge space. For this reason, it is desirable that the first optical path P1 and the second optical path P2 are as close as possible to each other.

[0052] On the other hand, in order to turn back the traveling direction of the laser light Lp in the front-side optical system 35 and the rear-side optical system 36, it is necessary that the first optical path P1 and the second optical path P2 are spaced apart from each other by a certain distance at both ends. To achieve this, it is necessary to increase the resonator length corresponding to the distance between the front-side optical system 35 and the rear-side optical system 36. As described above, since the power oscillator 30 has a long resonator length, high adjustment accuracy is required to adjust the optical path without reducing the amplification efficiency.

[0053] Furthermore, in the ring resonator, the first optical path P1 and the second optical path P2 need to pass through the slits 37a and 38a with high precision so that the laser light Lp is not eclipsed by the slit members 37 and 38 arranged in the chamber 32. From this perspective as well, high adjustment precision is required for the optical path adjustment.

[0054] However, in the optical path adjustment method according to the comparative example, simply adjusting the optical paths so that the beam profiles BP0 to BP3 overlap does not allow the operator to accurately determine whether the first optical path P1 and the second optical path P2 within the chamber 32 are optimal. Therefore, when adjusting the optical paths so that the beam profiles BP0 to BP3 completely overlap, the operator has difficulty determining which of the output coupling mirror 40 and the high-reflection mirrors 41, 50, and 51 should be adjusted in attitude. Depending on the mirror being adjusted, even if the beam profiles BP0 to BP3 can be completely overlapped, vignetting of the laser light Lp by the slits 37a and 38a may occur, resulting in a decrease in the energy of the laser light Lp emitted from the power oscillator 30.

[0055] Furthermore, in the optical path adjustment method according to the comparative example, it is necessary to remove the power oscillator 30 from the laser device 2 before performing the optical path adjustment, which takes a long time.

[0056] As described above, in the laser device 2 equipped with the power oscillator 30 including the ring resonator, it is required to be able to accurately adjust the optical path without reducing the amplification efficiency, and to shorten the time required for the optical path adjustment.

[0057] 2. First embodiment 2.1 Configuration Fig. 5 schematically illustrates a configuration example of a laser device 2a according to the first embodiment of the present disclosure. Fig. 6 schematically illustrates a configuration example of a power oscillator 30a according to the first embodiment. Fig. 5 is a view of the laser device 2a as viewed from the V-axis direction. Fig. 6 is a view of the power oscillator 30a as viewed from the H-axis direction. The laser device 2a differs from the configuration of the laser device 2 according to the comparative example only in the configuration of the power oscillator 30a.

[0058] 5, the power oscillator 30a is provided with a front-side observation device 80 and a rear-side observation device 90 in addition to the chamber 32, the front-side optical system 35a, and the rear-side optical system 36a. The front-side observation device 80 enables observation of the first optical path P1 and the second optical path P2 between the front-side optical system 35a and the chamber 32. The rear-side observation device 90 enables observation of the first optical path P1 and the second optical path P2 between the rear-side optical system 36a and the chamber 32.

[0059] The front-side observation device 80 includes a front-side mirror unit 81 and a front-side beam profiler 82. The front-side mirror unit 81 includes a front-side first mirror 83 and a front-side second mirror 84. The front-side first mirror 83 is disposed on the first optical path P1 and is a partial reflection mirror that partially reflects the laser light Lp incident along the first optical path P1. The front-side second mirror 84 is disposed on the second optical path P2 and is a high-reflection mirror that highly reflects the laser light Lp incident along the second optical path P2. For example, the front-side first mirror 83 is a half mirror that reflects approximately 50% of the incident laser light Lp and transmits the remainder. The front-side mirror unit 81 is disposed on a movable stage (not shown) and is configured to be retractable from the first optical path P1 and the second optical path P2.

[0060] The rear-side observation device 90 includes a rear-side mirror unit 91 and a rear-side beam profiler 92. The rear-side mirror unit 91 includes a rear-side first mirror 93 and a rear-side second mirror 94. The rear-side first mirror 93 is disposed on the first optical path P1 and is a partial reflection mirror that partially reflects the laser light Lp incident along the first optical path P1. The rear-side second mirror 94 is disposed on the second optical path P2 and is a high-reflection mirror that highly reflects the laser light Lp incident along the second optical path P2. For example, the rear-side first mirror 93 is a half mirror that reflects approximately 50% of the incident laser light Lp and transmits the remainder. The rear-side mirror unit 91 is disposed on a movable stage (not shown) and is configured to be retractable from the first optical path P1 and the second optical path P2.

[0061] The moving stages on which the front-side mirror unit 81 and the rear-side mirror unit 91 are arranged may be linear stages or rotary stages.

[0062] 6, the front-side first mirror 83 is arranged so that the laser light Lp traveling along the first optical path P1 is incident at an incident angle of 45° and a portion of the incident laser light Lp is reflected in the V-axis direction. The front-side second mirror 84 is arranged so that the laser light Lp traveling along the second optical path P2 is incident at an incident angle of 45° and the incident laser light Lp is highly reflected in the V-axis direction.

[0063] The rear-side first mirror 93 is disposed so that the laser light Lp traveling along the first optical path P1 is incident thereon at an incident angle of 45° and so that a portion of the incident laser light Lp is reflected in the V-axis direction. The rear-side second mirror 94 is disposed so that the laser light Lp traveling along the second optical path P2 is incident thereon at an incident angle of 45° and so that the incident laser light Lp is highly reflected in the V-axis direction.

[0064] The front-side beam profiler 82 includes a front-side screen 82a and a front-side camera 82b. The front-side screen 82a is a fluorescent screen that converts light in the ultraviolet range into visible light. Functional fluorescent glass such as Lumiras can be used as the fluorescent screen. The front-side screen 82a is positioned so that reflected light from the first front-side mirror 83 and the second front-side mirror 84 is perpendicularly incident on the front-side screen 82a. The front-side camera 82b is a visible light camera having an image sensor such as a CMOS (Complementary Metal-Oxide Semiconductor) type or a CCD (Charge-Coupled Device) type, and captures a pair of bright spots that appear when reflected light hits the front-side screen 82a.

[0065] The rear-side beam profiler 92 includes a rear-side screen 92a and a rear-side camera 92b. The rear-side screen 92a is a fluorescent screen that converts light in the ultraviolet range into visible light. Functional fluorescent glass such as Lumiras can be used as the fluorescent screen. The rear-side screen 92a is positioned so that reflected light from the first rear-side mirror 93 and the second rear-side mirror 94 is perpendicularly incident on the rear-side screen 92a. The rear-side camera 92b is a visible light camera equipped with an image sensor such as a CMOS type or CCD type, and captures a pair of bright spots that appear when reflected light hits the rear-side screen 92a.

[0066] Unlike the front side mirror unit 81 and the rear side mirror unit 91, the front side beam profiler 82 and the rear side beam profiler 92 are fixed to the chamber 32.

[0067] An image processing device may be provided that processes images captured by the front-side beam profiler 82 and the rear-side beam profiler 92, and a display that displays the processed images. It is also preferable to measure the positions and intervals between pairs of bright spots on each of the front-side screen 82a and the rear-side screen 92a by image processing and display the measurement results on the display.

[0068] In the first embodiment, of the output coupling mirror 40 and the high-reflection mirror 41 included in the front-side optical system 35a, only the high-reflection mirror 41 is provided with an actuator 42. Also, of the first high-reflection mirror 50 and the second high-reflection mirror 51 included in the rear-side optical system 36a, only the second high-reflection mirror 51 is provided with an actuator 53. The actuator 53 corresponds to the "first actuator" according to the technology of the present disclosure.

[0069] In the first embodiment, the first high-reflection mirror 50 and the second high-reflection mirror 51 included in the rear-side optical system 36a are arranged on a position adjustment stage 54. The position adjustment stage 54 moves the first high-reflection mirror 50 and the second high-reflection mirror 51 in the H-axis direction, which is a direction perpendicular to the longitudinal direction and the discharge direction of the pair of discharge electrodes 33a, 33b.

[0070] 7 shows a schematic configuration example of the front-side observation device 80. The front-side screen 82a is arranged parallel to the Z-axis direction and the H-axis direction. The front-side camera 82b captures an image of a bright spot B1a generated by light reflected from the first front-side mirror 83 and a bright spot B1b generated by light reflected from the second front-side mirror 84 on the front-side screen 82a.

[0071] 8 shows a schematic configuration example of the rear-side observation device 90. The rear-side screen 92a is arranged parallel to the Z-axis direction and the H-axis direction. The rear-side camera 92b captures an image of a bright spot B2a generated by light reflected from the first rear-side mirror 93 and a bright spot B2b generated by light reflected from the second rear-side mirror 94 on the rear-side screen 92a.

[0072] 9 explains the operation of the position adjustment stage 54 provided in the rear-side optical system 36a shown in FIG. The position adjustment stage 54 moves the first high-reflection mirror 50 and the second high-reflection mirror 51 in the H-axis direction, thereby causing the second optical path P2 to move parallel to the H-axis direction. When the position adjustment stage 54 moves the first high-reflection mirror 50 and the second high-reflection mirror 51 by a distance d, the second optical path P2 moves by a distance 2d. In this way, the position of the second optical path P2 can be adjusted by the position adjustment stage 54.

[0073] 10 explains the operation of the actuator 53 provided in the rear-side optical system 36a shown in FIG. 5. When the actuator 53 changes the attitude of the second high-reflection mirror 51, the angle of the second optical path P2 changes. When the actuator 53 rotates the second high-reflection mirror 51 by an angle θ around the V axis, the second optical path P2 rotates by an angle 2θ around the V axis. In this way, the angle of the second optical path P2 can be adjusted by the actuator 53.

[0074] 2.2 Operation The operation of the laser device 2a according to the first embodiment is similar to that of the laser device 2 according to the comparative example. During operation of the laser device 2a, the front-side mirror unit 81 and the rear-side mirror unit 91 are retracted from the first optical path P1 and the second optical path P2, and the beam profiler 60 is retracted from the optical path of the laser light Lp emitted from the power oscillator 30a.

[0075] 2.3 Optical path adjustment Next, the optical path adjustment performed in the preparation stage before operating the laser device 2a according to the first embodiment will be described.

[0076] 11 shows an example of the procedure for adjusting the optical path according to the first embodiment. In the optical path adjustment according to the first embodiment, it is not necessary to perform the adjustment using the pair of slit members 71, 72 in a state where the power oscillator 30a is removed from the laser device 2a as in the comparative example.

[0077] First, with the power oscillator 30a attached to the laser device 2a, the worker operates the master oscillator 10 to emit the laser beam Lp (step S10). At this time, the front-side mirror unit 81 and the rear-side mirror unit 91 are retracted from the first optical path P1 and the second optical path P2. The beam profiler 60 is inserted into the optical path of the laser beam Lp emitted from the power oscillator 30a.

[0078] The worker inserts the front-side mirror unit 81 into the first optical path P1 and the second optical path P2 (step S11).

[0079] The operator adjusts the MO beam steering unit 20 while observing the bright spots B1a and B1b using the front-side observation device 80 (step S12). For example, the operator adjusts the positions and angles of the first optical path P1 and the second optical path P2 by changing the orientation of the high-reflection mirrors 21a and 21b so that the bright spots B1a and B1b are at specified positions. Here, the specified positions refer to the positions of the bright spots B1a and B1b observed when the first optical path P1 and the second optical path P2 are in an appropriate state, passing through the discharge space and the slits 37a and 38a. The operator adjusts the MO beam steering unit 20 so that the bright spots B1a and B1b are aligned with a pair of markers or the like that indicate specified positions on the display or front-side screen 82a.

[0080] Next, the worker inserts the rear-side mirror unit 91 into the first optical path P1 and the second optical path P2 (step S13). As a result, the front-side mirror unit 81 and the rear-side mirror unit 91 are inserted into the first optical path P1 and the second optical path P2. The laser light Lp that has passed through the front-side first mirror 83 of the front-side mirror unit 81 travels along the first optical path P1 and is incident on the rear-side first mirror 93 of the rear-side mirror unit 91.

[0081] The operator adjusts the MO beam steering unit 20 while observing the bright spots B2a and B2b using the rear-side observation device 90 (step S14). For example, the operator checks whether the bright spots B2a and B2b are in the specified positions. If they are not in the specified positions, the operator adjusts the positions and angles of the first optical path P1 and the second optical path P2 by changing the orientation of the high-reflection mirrors 21a and 21b, as in step S12. Here, the specified positions refer to the positions of the bright spots B2a and B2b observed when the first optical path P1 and the second optical path P2 are in the above-described appropriate state. The operator adjusts the MO beam steering unit 20 so that the bright spots B2a and B2b coincide with a pair of markers or the like that indicate the specified positions on the display or rear-side screen 92a.

[0082] Furthermore, in step S14, the operator checks whether the bright spots B2a and B2b are circular. If vignetting of the laser light Lp occurs due to the slit members 37 and 38, the circularity of the bright spot B2a decreases. If the bright spots B2a and B2b are not circular, the positions and angles of the first optical path P1 and the second optical path P2 are adjusted by changing the attitudes of the high-reflection mirrors 21a and 21b.

[0083] Furthermore, the operator adjusts the rear-side optical system 36a while observing the bright spots B2a and B2b using the rear-side observation device 90 (step S15). For example, the operator checks whether the distance D2 (see FIG. 8) between the bright spots B2a and B2b is a specified distance, and if it is not, the operator translates the second optical path P2 using the position adjustment stage 54 to make the distance D2 the specified distance. Here, the specified distance is the distance between the bright spots B2a and B2b observed when the first optical path P1 and the second optical path P2 are in the above-described appropriate state.

[0084] Next, the worker retracts the rear side mirror unit 91 from the first optical path P1 and the second optical path P2 (step S16).

[0085] The operator adjusts the rear-side optical system 36a while observing the bright spots B1a and B1b using the front-side observation device 80 (step S17). For example, the operator checks whether the distance D1 (see FIG. 7) between the bright spots B1a and B1b is a specified distance, and if it is not, changes the angle of the second optical path P2 with the actuator 53 to make the distance D1 the specified distance. Here, the specified distance is the distance between the bright spots B1a and B1b observed when the first optical path P1 and the second optical path P2 are in the above-described appropriate state.

[0086] Next, the worker retracts the front-side mirror unit 81 from the first optical path P1 and the second optical path P2 (step S18). The worker then operates the power oscillator 30a (step S19). This causes the amplified laser light Lp to be emitted from the power oscillator 30a.

[0087] Then, the operator adjusts the overlap of the beam profiles BP0 to BP3 (see FIG. 4) using the beam profiler 60 (step S20). Specifically, the operator changes the attitude of the high-reflection mirror 41 using the actuator 42 so that the degree of overlap of the beam profiles BP0 to BP3 becomes the largest. This completes the optical path adjustment.

[0088] The optical path adjustment method of the present disclosure includes adjusting the rear-side optical system 36a by observing the first optical path P1 and the second optical path P2 using a rear-side observation device 90 (step S15), adjusting the rear-side optical system 36a by observing the first optical path P1 and the second optical path P2 using a front-side observation device 80 (step S17), and adjusting the front-side optical system 35a by observing the optical path of the laser light Lp emitted from the power oscillator 30a (step S20).

[0089] The optical path adjustment method of the present disclosure also includes adjusting the MO beam steering unit 20 by observing the first optical path P1 and the second optical path P2 using the front-side observation device 80 and the rear-side observation device 90 (steps S12 and S14).

[0090] 2.4 Effects In this embodiment, the operator can accurately determine whether the first optical path P1 and the second optical path P2 are optimal using the front-side observation device 80 and the rear-side observation device 90. Therefore, the optical path adjustment can be performed accurately without reducing the amplification efficiency. Furthermore, in this embodiment, there is no need to remove the power oscillator 30a from the laser device 2a to perform the optical path adjustment, as in the comparative example, and therefore the time required for the optical path adjustment can be reduced.

[0091] 3. Second embodiment 3.1 Configuration Next, a laser device 2b according to a second embodiment of the present disclosure will be described, focusing on differences in configuration from the laser device 2a according to the first embodiment.

[0092] 12 is a schematic diagram illustrating an example of the configuration of a laser device 2b according to the second embodiment. The laser device 2b differs from the laser device 2a according to the first embodiment only in the configuration of the power oscillator 30b. The power oscillator 30b differs from the front-side optical system 35a according to the first embodiment in the configuration of the front-side optical system 35b. The other configurations of the power oscillator 30b are the same as those of the power oscillator 30a according to the first embodiment.

[0093] The front-side optical system 35b includes an output-coupling mirror 40, a third high-reflection mirror 44, and a fourth high-reflection mirror 45. The configuration of the output-coupling mirror 40 is the same as that of the first embodiment. The third high-reflection mirror 44 is disposed so as to reflect the laser light Lp, which travels along the second optical path P2 and enters the front-side optical system 35b, toward the fourth high-reflection mirror 45. The fourth high-reflection mirror 45 is disposed so as to reflect the laser light Lp, which enters from the third high-reflection mirror 44, toward the second surface 40b of the output-coupling mirror 40.

[0094] The output coupling mirror 40 transmits a portion of the laser light Lp incident on the second surface 40b from the fourth high-reflecting mirror 45, and reflects a portion of the laser light Lp to cause it to travel along the first optical path P1.

[0095] The third high-reflection mirror 44 and the fourth high-reflection mirror 45 are respectively equipped with actuators 46 and 47 for changing their attitudes. For example, the actuators 46 and 47 enable tilt adjustment in the left-right and up-down directions. By changing the attitudes of the third high-reflection mirror 44 and the fourth high-reflection mirror 45 using the actuators 46 and 47, it is possible to adjust the position and angle of the optical path of the laser light Lp emitted from the power oscillator 30b. The actuator 46 corresponds to the "second actuator" according to the technology of the present disclosure. The actuator 47 corresponds to the "third actuator" according to the technology of the present disclosure.

[0096] In the first embodiment, the ring resonator is composed of four mirrors: an output coupling mirror 40, a high-reflection mirror 41, a first high-reflection mirror 50, and a second high-reflection mirror 51. In contrast, in the second embodiment, the ring resonator is composed of five mirrors: an output coupling mirror 40, a first high-reflection mirror 50, a second high-reflection mirror 51, a third high-reflection mirror 44, and a fourth high-reflection mirror 45.

[0097] 3.2 Operation The operation of the laser device 2b according to the second embodiment is the same as that of the laser device 2a according to the first embodiment, except that the laser light Lp incident on the front optical system 35b is reflected by the third high-reflection mirror 44 and the fourth high-reflection mirror 45 and then incident on the output coupling mirror 40.

[0098] In this embodiment, the laser light Lp that enters the front-side optical system 35b from the chamber 32 is reflected by the third high-reflection mirror 44 and the fourth high-reflection mirror 45 and then enters the output coupling mirror 40. A portion of the laser light Lp that enters the output coupling mirror 40 passes through the output coupling mirror 40 and is emitted from the front-side optical system 35b to the outside of the power oscillator 30b. The remaining portion of the laser light Lp that enters the output coupling mirror 40 is reflected by the output coupling mirror 40 and is emitted from the front-side optical system 35b toward the chamber 32.

[0099] 3.3 Optical path adjustment The procedure for adjusting the optical path according to the second embodiment is basically the same as that according to the first embodiment. However, in this embodiment, in step S20 shown in Fig. 11, the operator changes the attitudes of the third high-reflection mirror 44 and the fourth high-reflection mirror 45 using the actuators 46 and 47 so that the degree of overlap of the beam profiles BP0 to BP3 becomes the largest.

[0100] 3.4 Effects In this embodiment, since the ring resonator is composed of five mirrors, the beam profile of the laser light Lp is mirror-inverted each time it makes one revolution around the ring resonator. That is, since the beam profile of the laser light Lp emitted from the power oscillator 30b is mirror-inverted each time it makes one revolution, the spatial coherence of the laser light Lp is reduced. As a result, when the laser device 2b is used as an exposure light source, speckles on the reticle are suppressed.

[0101] Furthermore, even if there is an angular misalignment among the five mirrors that make up the ring resonator, the beam profile of the laser light Lp is inverted by the mirrors for each revolution, which has the advantage of suppressing the accumulation of the angular misalignment components of each mirror.

[0102] Furthermore, in this embodiment, the position and angle of the laser light Lp emitted from the power oscillator 30b can be adjusted using two mirrors, the third high-reflection mirror 44 and the fourth high-reflection mirror 45. Therefore, in this embodiment, the overlap of the beam profiles BP0 to BP3 can be adjusted with higher precision.

[0103] 4. MO beam steering unit variants Next, we will explain modified examples of the MO beam steering unit 20. The MO beam steering unit 20 according to the first and second embodiments can be modified in various ways.

[0104] 13 shows a schematic configuration of an MO beam steering unit 20a according to a modified example. The MO beam steering unit 20a includes three high-reflection mirrors 22a, 22b, and 22c, and a position adjustment stage 23. Each of the high-reflection mirrors 22a and 22b is fitted with an actuator (not shown) for changing its position. For example, the actuator allows tilt adjustment in the left-right and up-down directions.

[0105] The high-reflection mirror 22c is disposed on a position adjustment stage 23. The position adjustment stage 23 moves the high-reflection mirror 22c in the H-axis direction.

[0106] High-reflection mirror 22a is disposed at a position where laser light Lp emitted from master oscillator 10 is incident, and highly reflects the laser light Lp in the V-axis direction. High-reflection mirror 22b is disposed at a position where laser light Lp highly reflected by high-reflection mirror 22a is incident, and highly reflects the laser light Lp in the H-axis direction. High-reflection mirror 22c is disposed at a position where laser light Lp highly reflected by high-reflection mirror 22b is incident, and highly reflects the laser light Lp in the Z-axis direction toward the power oscillator.

[0107] The angle of the first optical path P1 can be adjusted by changing the attitude of the high-reflection mirrors 22a and 22b with the actuators. In addition, the position of the first optical path P1 can be adjusted by moving the high-reflection mirror 22c with the position adjustment stage 23.

[0108] By using the MO beam steering unit 20a of this modified example instead of the MO beam steering unit 20 of the first and second embodiments, the position and angle of the first optical path P1 can be adjusted with high precision in steps S12 and S14 shown in Figure 11.

[0109] The MO beam steering unit in the present disclosure may be any device that includes at least two mirrors and that can adjust the position and angle of the optical path of the laser light Lp that enters the power oscillator.

[0110] 5. Master Oscillator Variations Next, a description will be given of modified examples of the master oscillator 10. In the first and second embodiments, the laser devices 2a and 2b each include a master oscillator 10 configured as an excimer laser device, but the master oscillator 10 can be modified in various ways.

[0111] 5.1 Configuration 14 shows a schematic configuration of a master oscillator 10a according to a modified example. The master oscillator 10a is a solid-state laser device that includes a semiconductor laser 100 that outputs seed light, a titanium sapphire amplifier 110 that amplifies the seed light, and a wavelength conversion system 120.

[0112] The semiconductor laser 100 is a distributed feedback semiconductor laser that outputs a CW (Continuous Wave) laser beam having a wavelength of 773.6 nm as seed light. By changing the temperature setting of the semiconductor laser 100, the oscillation wavelength can be changed.

[0113] The titanium sapphire amplifier 110 includes a titanium sapphire crystal 111 and a pumping pulse laser 112. The titanium sapphire crystal 111 is disposed on the optical path of the seed light. The pumping pulse laser 112 is a laser device that outputs second harmonic light of a YLF laser.

[0114] The wavelength conversion system 120 is a wavelength conversion system that generates fourth harmonic light and includes an LBO (LiB3O5) crystal and a KBBF (KBe2BO3F2) crystal. Each crystal is placed on a rotation stage (not shown) so that the angle of incidence of the seed light on each crystal can be changed.

[0115] 5.2 Operation In the titanium sapphire amplifier 110, the pumping pulse laser 112 converts the CW laser light input as seed light to the titanium sapphire crystal 111 into pulsed laser light and outputs it based on a trigger signal input from a control unit (not shown). The pulsed laser light output from the titanium sapphire amplifier 110 is input to the wavelength conversion system 120. The wavelength conversion system 120 converts the input pulsed laser light with a wavelength of 773.6 nm into pulsed laser light with a wavelength of 193.4 nm and emits it as laser light Lp toward the MO beam steering unit.

[0116] In this modification, the power oscillator is an ArF excimer amplifier, which amplifies the laser light Lp having a wavelength of 193.4 nm input from the MO beam steering unit.

[0117] 5.3 Other The master oscillator 10a may be a solid-state laser device that emits pulsed laser light with a wavelength of 248.4 nm, and the power oscillator may be a KrF excimer amplifier. In this case, the semiconductor laser 100 outputs CW laser light with a wavelength of 745.2 nm, and the titanium sapphire amplifier 110 converts the CW laser light input from the semiconductor laser 100 into pulsed laser light and outputs it. In this case, the wavelength conversion system 120 is a wavelength conversion system that generates third harmonic light, and is composed of an LBO crystal and CLBO (CsLiBO). 10 The wavelength conversion system 120 generates second harmonic light using the LBO crystal and third harmonic light using the CLBO crystal, thereby emitting pulsed laser light with a wavelength of 248.4 nm as laser light Lp.

[0118] 6. Modifications of the front-side observation device and the rear-side observation device The front-side observation device 80 is not limited to a configuration in which the front-side mirror unit 81 can be retracted from the first optical path P1 and the second optical path P2, and the front-side mirror unit 81 may be fixed to the first optical path P1 and the second optical path P2. Similarly, the rear-side observation device 90 is not limited to a configuration in which the rear-side mirror unit 91 can be retracted from the first optical path P1 and the second optical path P2, and the rear-side mirror unit 91 may be fixed to the first optical path P1 and the second optical path P2. That is, the front-side mirror unit 81 and the rear-side mirror unit 91 may be disposed on the first optical path P1 and the second optical path P2 while the laser devices 2a and 2b are operating. In this case, the front-side second mirror 84 and the rear-side second mirror 94 disposed on the second optical path P2 may each be a partially reflecting mirror so that the laser light Lp circulates through the ring resonator. In this case, it is preferable that the front-side first mirror 83, the front-side second mirror 84, the rear-side first mirror 93, and the rear-side second mirror 94 are each a partial reflection mirror with a reflectance of 1% or less.

[0119] 7. Electronic Device Manufacturing Method 15 shows a schematic configuration example of exposure apparatus 200. Exposure apparatus 200 includes an illumination optical system 204 and a projection optical system 206. Illumination optical system 204 illuminates a reticle pattern of a reticle (not shown) placed on reticle stage RT with laser light Lp incident from, for example, laser device 2a. Projection optical system 206 reduces and projects the laser light Lp that has passed through the reticle, forming an image on a workpiece (not shown) placed on workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist.

[0120] The exposure apparatus 200 exposes the workpiece with laser light Lp reflecting the reticle pattern by synchronously translating the reticle stage RT and the workpiece table WT. After the reticle pattern is transferred to the semiconductor wafer through the exposure process described above, a semiconductor device can be manufactured through multiple processes. A semiconductor device is an example of an "electronic device" in this disclosure.

[0121] The laser device that outputs the laser light Lp to the exposure device 200 may be any of the laser devices according to the above-described embodiments and modifications.

[0122] The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to those skilled in the art that modifications may be made to the embodiments of the present disclosure without departing from the scope of the appended claims.

[0123] Terms used throughout this specification and the appended claims should be interpreted as "open-ended" terms. For example, the terms "including" or "including" should be interpreted as "not limited to what is stated as including." The term "having" should be interpreted as "not limited to what is stated as having." Additionally, the modifier "a" or "an" used in this specification and the appended claims should be interpreted as meaning "at least one" or "one or more."

Claims

1. an oscillator that emits laser light; an amplifier that amplifies the laser light in a chamber including a pair of discharge electrodes; a front-side optical system and a rear-side optical system that are arranged at opposite positions across the chamber and that configure a ring resonator including a first optical path and a second optical path that intersect between the pair of discharge electrodes; a front-side observation device for observing the first optical path and the second optical path between the front-side optical system and the chamber; a rear-side observation device for observing the first optical path and the second optical path between the rear-side optical system and the chamber; Equipped with the first optical path is an optical path through which the front-side optical system emits the laser light incident from the oscillator toward the rear-side optical system, the second optical path is an optical path through which the rear-side optical system emits the laser light, which has entered through the first optical path, toward the front-side optical system; 1. A laser device, comprising: the front side observation device, a front-side first mirror disposed in the first optical path; a front-side second mirror disposed in the second optical path; a front-side screen onto which reflected light of the laser light from the first front-side mirror and the second front-side mirror is incident; a front-side camera that captures an image of the front-side screen; Including, the rear side observation device, a rear-side first mirror disposed in the first optical path; a rear-side second mirror disposed in the second optical path; a rear-side screen onto which reflected light of the laser light from the first rear-side mirror and the second rear-side mirror is incident; a rear camera that captures an image of the rear screen; Contains Laser device.

2. 2. The laser device according to claim 1, the first front-side mirror and the second front-side mirror are retractable from the first optical path and the second optical path between the front-side optical system and the chamber, The first rear-side mirror and the second rear-side mirror are retractable from the first optical path and the second optical path between the rear-side optical system and the chamber.

3. 3. The laser device according to claim 2, the front-side first mirror and the rear-side first mirror are partial reflection mirrors that partially reflect the laser light incident along the first optical path, The front-side second mirror and the rear-side second mirror are high-reflection mirrors that highly reflect the laser light incident along the second optical path.

4. 2. The laser device according to claim 1, The front screen and the rear screen are fluorescent screens.

5. 3. The laser device according to claim 2, the front-side camera captures an image of a pair of bright points that appear on the front-side screen; The rear camera captures an image of a pair of bright spots that appear on the rear screen.

6. 2. The laser device according to claim 1, The rear optical system includes a first high-reflection mirror that reflects the laser light incident via the first optical path, and a second high-reflection mirror that reflects the laser light reflected by the first high-reflection mirror and causes it to travel along the second optical path.

7. 7. The laser device according to claim 6, the first optical path and the second optical path are included in a plane perpendicular to a discharge direction of the pair of discharge electrodes, The rear optical system includes a position adjustment stage that moves the first high-reflection mirror and the second high-reflection mirror in a direction perpendicular to the longitudinal direction of the pair of discharge electrodes and the discharge direction.

8. 8. The laser device according to claim 7, The rear optical system includes a first actuator that changes the attitude of the second high-reflection mirror.

9. 2. The laser device according to claim 1, The laser beam source further includes a beam steering device that is disposed on the optical path of the laser beam between the oscillator and the amplifier and adjusts the optical path of the laser beam that enters the amplifier.

10. 10. The laser device according to claim 9, The beam steering device includes at least two mirrors, and enables adjustment of the position and angle of the optical path of the laser light incident on the amplifier.

11. 2. The laser device according to claim 1, The optical fiber further includes a beam profiler for observing the optical path of the laser light emitted from the amplifier.

12. 2. The laser device according to claim 1, the front-side optical system includes an output coupling mirror, a third high-reflection mirror, and a fourth high-reflection mirror; The output coupling mirror transmits the laser light incident from the oscillator and causes it to travel along the first optical path.

13. 13. The laser device according to claim 12, the third high-reflection mirror reflects the laser light, which travels along the second optical path and enters the front-side optical system, toward the fourth high-reflection mirror; the fourth high-reflection mirror reflects the laser light incident from the third high-reflection mirror toward the output coupling mirror; The output coupling mirror transmits a portion of the laser light incident from the fourth high-reflectivity mirror to emit the laser light from the front-side optical system, and reflects a portion of the laser light to cause the laser light to travel along the first optical path.

14. 14. The laser device according to claim 13, The front optical system includes a second actuator that changes the position of the third high-reflection mirror, and a third actuator that changes the position of the fourth high-reflection mirror.

15. 2. The laser device according to claim 1, The chamber comprises: a first window disposed between the pair of discharge electrodes and the front-side optical system, through which the first optical path and the second optical path pass; a second window disposed between the pair of discharge electrodes and the rear-side optical system, through which the first optical path and the second optical path pass; is established, Inside the chamber, slit members having slits through which the first optical path and the second optical path pass are provided between the pair of discharge electrodes and the first window and between the pair of discharge electrodes and the second window, respectively.

16. 2. The laser device according to claim 1, The oscillator is a solid-state laser device.

17. an oscillator that emits laser light; an amplifier that amplifies the laser light in a chamber including a pair of discharge electrodes; a front-side optical system and a rear-side optical system that are arranged at opposite positions across the chamber and that configure a ring resonator including a first optical path and a second optical path that intersect between the pair of discharge electrodes; a front-side observation device for observing the first optical path and the second optical path between the front-side optical system and the chamber; a rear-side observation device for observing the first optical path and the second optical path between the rear-side optical system and the chamber; Equipped with the first optical path is an optical path through which the front-side optical system emits the laser light incident from the oscillator toward the rear-side optical system, the second optical path is an optical path through which the rear-side optical system emits the laser light, which has entered through the first optical path, toward the front-side optical system; A method for adjusting an optical path of a laser device, comprising: adjusting the rear-side optical system by observing the first optical path and the second optical path using the rear-side observation device; adjusting the rear-side optical system by observing the first optical path and the second optical path using the front-side observation device; adjusting the front optical system by observing the optical path of the laser light emitted from the amplifier; An optical path adjustment method including:

18. 18. The optical path adjustment method according to claim 17, The method includes adjusting a beam steering device disposed on the optical path of the laser light between the oscillator and the amplifier by observing the first optical path and the second optical path using the front-side observation device and the rear-side observation device.

19. A method for manufacturing an electronic device, comprising: an oscillator that emits laser light; an amplifier that amplifies the laser light in a chamber including a pair of discharge electrodes; a front-side optical system and a rear-side optical system that are arranged at opposite positions across the chamber and that configure a ring resonator including a first optical path and a second optical path that intersect between the pair of discharge electrodes; a front-side observation device for observing the first optical path and the second optical path between the front-side optical system and the chamber; a rear-side observation device for observing the first optical path and the second optical path between the rear-side optical system and the chamber; Equipped with the first optical path is an optical path through which the front-side optical system emits the laser light incident from the oscillator toward the rear-side optical system, The second optical path is an optical path through which the rear-side optical system emits the laser light, which has entered through the first optical path, toward the front-side optical system.

1. A laser device, comprising: the front side observation device, a front-side first mirror disposed in the first optical path; a front-side second mirror disposed in the second optical path; a front-side screen onto which reflected light of the laser light from the first front-side mirror and the second front-side mirror is incident; a front-side camera that captures an image of the front-side screen; Including, the rear side observation device, a rear-side first mirror disposed in the first optical path; a rear-side second mirror disposed in the second optical path; a rear-side screen onto which reflected light of the laser light from the first rear-side mirror and the second rear-side mirror is incident; a rear camera that captures an image of the rear screen; Contains generating the laser light by a laser device; outputting the laser light to an exposure device; exposing a photosensitive substrate to the laser light in the exposure apparatus to manufacture an electronic device; A method for manufacturing electronic devices.

Images