Laser cavity, gas laser device and method for manufacturing electronic device

Abstract

Provided are a laser cavity, a gas laser device, and a method for manufacturing an electronic device. A laser cavity of one aspect of the present disclosure has: a container filled with a laser gas; a first electrode; a second electrode disposed at a position closer to an inner wall of the container than the first electrode in an opposed state to the first electrode; a fan that causes the laser gas to flow through a discharge space between the first electrode and the second electrode; and an insulating guide disposed at a position that is at least one of an upstream side and a downstream side of the laser gas with respect to the second electrode, a plurality of grooves extending in a direction parallel to a direction in which the laser gas flows being formed on a surface of the insulating guide, the plurality of grooves including a combination of two adjacent grooves having different cross-sectional shapes obtained by cutting the plurality of grooves in a plane orthogonal to the direction in which the laser gas flows.

Description

Technical Field

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

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

[0003] The naturally oscillating light from KrF and ArF excimer lasers has a wide spectral linewidth, reaching 350–400 pm. Therefore, if the projection lens is made of a material that allows ultraviolet light, such as that of KrF and ArF lasers, to pass through, chromatic aberration may sometimes occur. As a result, resolution may be reduced. Therefore, it is necessary to narrow the spectral linewidth of the laser output from the gas laser device to a level that negligible chromatic aberration. Thus, to achieve spectral linewidth narrowing, a line-narrowing module (LNM) including narrowing elements (etalon, grating, etc.) is sometimes incorporated into the laser resonator of the gas laser device. Hereinafter, gas laser devices that achieve spectral linewidth narrowing will be referred to as narrow-band gas laser devices.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 1999 / 045614

[0007] Patent Document 2: U.S. Patent Publication No. 2016 / 0308324

[0008] Patent Document 3: Japanese Patent Application Publication No. 6-85350 Summary of the Invention

[0009] One aspect of the laser cavity disclosed herein includes: a container filled with laser gas; a first electrode; a second electrode disposed opposite to the first electrode at a position closer to the inner wall of the container than the first electrode; a fan that directs the laser gas through a discharge space between the first and second electrodes; and an insulating guide disposed at at least one upstream or downstream of the laser gas relative to the second electrode, wherein a plurality of grooves extending in a direction parallel to the direction of laser gas flow are formed on the surface of the insulating guide, the plurality of grooves comprising a combination of two adjacent grooves with different cross-sectional shapes obtained by cutting the plurality of grooves along a plane orthogonal to the direction of laser gas flow.

[0010] One aspect of the gas laser device disclosed herein includes: an optical resonator; and a laser cavity configured to allow the optical path of the optical resonator to pass through. The laser cavity includes: a container filled with laser gas; a first electrode disposed within the container; a second electrode disposed opposite to the first electrode at a position closer to the inner wall of the container than the first electrode; a fan that directs the laser gas through a discharge space between the first and second electrodes; and an insulating guide disposed relative to the second electrode on at least one of an upstream side and a downstream side of the laser gas. A plurality of grooves extending in a direction parallel to the direction of laser gas flow are formed on the surface of the insulating guide. The plurality of grooves includes combinations of two adjacent grooves with different cross-sectional shapes obtained by cutting the plurality of grooves along a plane orthogonal to the direction of laser gas flow.

[0011] One aspect of this disclosure relates to a method for manufacturing an electronic device, comprising the steps of: generating a laser using a gas laser device; outputting the laser to an exposure apparatus; and exposing the laser on a photosensitive substrate within the exposure apparatus to manufacture the electronic device. The gas laser device includes: an optical resonator; and a laser cavity configured to allow the optical path of the optical resonator to pass through. The laser cavity includes: a container filled with laser gas; a first electrode disposed within the container; a second electrode disposed opposite to the first electrode at a position closer to the inner wall of the container than the first electrode; a fan that directs the laser gas through a discharge space between the first and second electrodes; and an insulating guide disposed relative to the second electrode on at least one of an upstream side and a downstream side of the laser gas. A plurality of grooves extending in a direction parallel to the direction of laser gas flow are formed on the surface of the insulating guide. The plurality of grooves include combinations of two adjacent grooves with different cross-sectional shapes obtained by cutting the plurality of grooves along a plane orthogonal to the direction of laser gas flow. Attached Figure Description

[0012] Hereinafter, with reference to the accompanying drawings, several embodiments of the present disclosure will be described as examples only.

[0013] Figure 1 This is a side view that schematically shows the structure of the comparative example gas laser device.

[0014] Figure 2 This is a cross-sectional view that schematically shows the structure of the comparative example gas laser device.

[0015] Figure 3 It is a schematic cross-sectional view of the portion of the laser cavity containing the main electrode.

[0016] Figure 4 This is a schematic cross-sectional view showing the portion of the laser cavity containing the main electrode in an embodiment.

[0017] Figure 5 This is a top view showing the surface of the insulating guide.

[0018] Figure 6 It shows along Figure 5 A cross-sectional view of the section obtained by cutting along line AA.

[0019] Figure 7 This is a side view showing the structure of the groove when viewed from the side.

[0020] Figure 8 This is a cross-sectional view showing the cross-section of the insulating guide in the first modified example.

[0021] Figure 9 This is a side view showing the construction of the groove of the insulating guide in the second modified example when viewed from the side.

[0022] Figure 10 This is a top view showing the surface of the insulating guide in the third modified example.

[0023] Figure 11 It shows along Figure 10 A cross-sectional view of the section obtained by cutting along the BB line.

[0024] Figure 12 This is a cross-sectional view showing the cross-section of the insulating guide in the fourth modified example.

[0025] Figure 13 This is a diagram that roughly illustrates an example of the structure of an exposure apparatus. Detailed Implementation

[0026] <Content>

[0027] 1. Comparative Example

[0028] 1.1 Structure

[0029] 1.2 Actions

[0030] 1.3 Research Topic

[0031] 2. Implementation Method

[0032] 2.1 Structure

[0033] 2.2 Actions

[0034] 2.3 Effects

[0035] 3. Variations

[0036] 3.1 First Variation

[0037] 3.2 Second variation

[0038] 3.3 Third variation

[0039] 3.4 Fourth Variation Example

[0040] 4. Manufacturing methods for electronic devices

[0041] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below represent several examples of the present disclosure and do not limit the content of the present disclosure. In addition, not all structures and operations described in the embodiments are necessary for the structures and operations of the present disclosure. Furthermore, the same structural elements are labeled with the same reference numerals, and repeated descriptions are omitted.

[0042] 1. Comparative Example

[0043] First, the comparative examples in this disclosure should be explained. The comparative examples in this disclosure are methods that the applicant recognizes as being known only to the applicant, and are not publicly known examples that the applicant himself endorses.

[0044] 1.1 Structure

[0045] use Figure 1 and Figure 2 The structure of the comparative example gas laser device 2 will be described. Figure 1 The structure of the gas laser device 2 is shown in outline. Figure 2 Observing from the Z direction Figure 1 The diagram shows a cross-sectional view of the gas laser device 2. The gas laser device 2 is a discharge-excited gas laser device, such as an excimer laser device, that uses a laser gas to generate a discharge excitation.

[0046] exist Figure 1 In this embodiment, the travel direction of the pulsed laser PL output from the gas laser device 2 is defined as the Z direction. The discharge direction, described later, is defined as the Y direction. Furthermore, the direction orthogonal to both the Z and Y directions is defined as the X direction. Additionally, the pulsed laser PL is an example of the "laser" involved in the technology disclosed herein.

[0047] The gas laser device 2 is a narrowband gas laser device comprising a laser cavity 10, a charger 11, a pulse power module (PPM) 12, a pulse energy meter 13, a processor 14, a pressure sensor 17, and a laser resonator. The laser resonator is composed of a narrowband module 15 and an output coupling mirror 16.

[0048] The laser cavity 10 includes, for example, a container 10a formed of aluminum metal with a surface plated with nickel. Figure 1 and Figure 2 As shown, the container 10a contains a main electrode 20, a ground plane 21, a return plate 22, a fan 23, a heat exchanger 24, insulating guides 28a and 28b, sound-absorbing components 29a and 29b, and a pre-ionization electrode 30. The pre-ionization electrode 30 includes a pre-ionization outer electrode 31, a dielectric tube 32, and a pre-ionization inner electrode 33.

[0049] A fluorine-containing laser gas is sealed inside container 10a as a laser medium. The laser gas may include, for example, inert gases such as argon, krypton, and xenon, buffer gases such as neon and helium, or halogen gases such as fluorine and chlorine.

[0050] Additionally, an opening is formed in container 10a. An electrical insulating plate 26, with a feedthrough portion 25 embedded within it, is mounted on container 10a via an O-ring (not shown) to block this opening. A PPM 12 is disposed on the electrical insulating plate 26. Container 10a is grounded.

[0051] PPM12 includes a charging capacitor (not shown) connected to the main electrode 20 via a feedthrough 25. PPM12 includes a switch SW for discharging the main electrode 20. Charger 11 is connected to the charging capacitor of PPM12. Hereinafter, the discharge generated on the main electrode 20 will be referred to as main discharge.

[0052] The main electrode 20 consists of a cathode electrode 20a and an anode electrode 20b. The cathode electrode 20a and anode electrode 20b are arranged within the container 10a with their discharge surfaces facing each other. The space between the discharge surfaces of the cathode electrode 20a and the anode electrode 20b is called the discharge space 27. The cathode electrode 20a and the anode electrode 20b extend along the Z-direction.

[0053] The side of the cathode electrode 20a opposite to the discharge surface is supported by the electrically insulating plate 26, thereby connecting the cathode electrode 20a to the feedthrough portion 25. That is, the cathode electrode 20a is positioned opposite the anode electrode 20b, closer to the inner wall of the container 10a than the anode electrode 20b. The side of the anode electrode 20b opposite to the discharge surface is supported by the grounding plate 21. The anode electrode 20b is an example of the "first electrode" of the present disclosure. The cathode electrode 20a is an example of the "second electrode" of the present disclosure.

[0054] Grounding plate 21 is connected to container 10a via return plate 22. Container 10a is grounded. Therefore, grounding plate 21 is grounded via return plate 22. The Z-direction end of grounding plate 21 is fixed to container 10a.

[0055] Fan 23 is a crossflow fan used to circulate laser gas within container 10a, and is configured on the side opposite to the ground plane 21 and the discharge space 27. A motor 23a is connected to container 10a to drive the rotation of fan 23.

[0056] The laser gas blown out by fan 23 flows into discharge space 27. The flow direction of the laser gas flowing into discharge space 27 is approximately parallel to the X-direction. The laser gas flowing out of discharge space 27 is drawn into fan 23 via heat exchanger 24. Heat exchanger 24 changes the temperature of laser gas by exchanging heat between the refrigerant supplied inside heat exchanger 24 and the laser gas.

[0057] Insulating guides 28a and 28b are disposed on the surface of the electrically insulating plate 26 near the discharge space 27, with the cathode electrode 20a as a secondary component. Insulating guide 28a is positioned upstream of the cathode electrode 20a in the laser gas. Insulating guide 28b is positioned downstream of the cathode electrode 20a in the laser gas.

[0058] The insulating guides 28a and 28b are shaped to guide the flow of laser gas, allowing the laser gas from the fan 23 to flow efficiently between the cathode electrode 20a and the anode electrode 20b. The insulating guides 28a and 28b and the electrical insulating plate 26 are formed, for example, from alumina (Al2O3) or other ceramics that have low reactivity with fluorine gas.

[0059] Sound-absorbing components 29a and 29b are disposed on the surface of the ground plane 21 on the side closest to the discharge space 27, with the anode electrode 20b separated from it. Sound-absorbing component 29a is disposed upstream of the anode electrode 20b in the laser gas. Sound-absorbing component 29b is disposed downstream of the anode electrode 20b in the laser gas.

[0060] The sound-absorbing components 29a and 29b are formed, for example, of a porous material. The porous material constituting the sound-absorbing components 29a and 29b is at least one of porous metal, foamed metal, and mesh metal. These are metallic materials with low reactivity with the laser gas, such as at least one of nickel, aluminum, and copper. The sound-absorbing components 29a and 29b guide the laser gas from the fan 23 to flow efficiently between the cathode electrode 20a and the anode electrode 20b, and absorb the sound waves generated by the main discharge.

[0061] A laser gas supply device 18a and a laser gas exhaust device 18b are connected to the laser cavity 10. The laser gas supply device 18a includes a valve and a flow control valve and is connected to a gas cylinder containing laser gas. The laser gas exhaust device 18b includes a valve and an exhaust pump.

[0062] Windows 19a and 19b are provided at the end of the container 10a to allow light generated inside the container 10a to exit to the outside. The laser cavity 10 is configured such that the optical path of the optical resonator passes through the discharge space 27 and the windows 19a and 19b.

[0063] The narrowband module 15 includes a prism 15a and a grating 15b. The prism 15a widens the beam width of light emitted from the laser cavity 10 through the window 19a and transmits it toward the grating 15b side.

[0064] The grating 15b is configured in a Litterrow configuration where the incident angle and diffraction angle are the same. The grating 15b is a wavelength selection element that selectively extracts light near a specific wavelength based on the diffraction angle. The spectral linewidth of the light returning from the grating 15b to the laser cavity 10 via the prism 15a is narrowed.

[0065] The output coupling mirror 16 allows a portion of the light emitted from the laser cavity 10 through the window 19b to pass through, while reflecting the other portion back into the laser cavity 10. The surface of the output coupling mirror 16 is coated with a partially reflective film.

[0066] The light emitted from the laser cavity 10 travels back and forth between the narrowband module 15 and the output coupling mirror 16, and is amplified each time it passes through the discharge space 27. A portion of the amplified light is output as a pulsed laser PL via the output coupling mirror 16. The wavelength of the pulsed laser PL is in the ultraviolet region from 150 nm to 380 nm, such as the oscillation wavelength of an excimer laser device.

[0067] The pulse energy measurement unit 13 is disposed in the optical path of the pulsed laser PL output via the output coupling mirror 16. The pulse energy measurement unit 13 includes a beam splitter 13a, a focusing optical system 13b, and a light sensor 13c.

[0068] Beam splitter 13a allows the pulsed laser PL to pass through with high transmittance and reflects a portion of the pulsed laser PL toward the focusing optical system 13b. The focusing optical system 13b focuses the light reflected by the beam splitter 13a onto the light-receiving surface of the light sensor 13c. The light sensor 13c measures the pulse energy of the light focused onto the light-receiving surface and outputs the measured value to the processor 14.

[0069] Pressure sensor 17 detects the gas pressure inside container 10a and outputs the detected value to processor 14. Processor 14 determines the gas pressure of laser gas inside container 10a based on the detected gas pressure value and the charging voltage of charger 11.

[0070] Charger 11 is a high-voltage power supply that provides charging voltage to the charging capacitor contained in PPM12. The PPM12 switch SW is controlled by processor 14. When switch SW changes from open to closed, PPM12 generates a high-voltage pulse from the electrical energy stored in the charging capacitor and applies it to the main electrode 20.

[0071] The processor 14 is a processing device such as a CPU (Central Processing Unit) that sends and receives various signals to and from the exposure apparatus controller 110 provided in the exposure apparatus 100. For example, the exposure apparatus controller 110 sends the target pulse energy of the pulsed laser PL output to the exposure apparatus 100, the oscillation trigger signal, etc., from the exposure apparatus controller 110 to the processor 14.

[0072] The processor 14 controls the operation of each structural element of the gas laser device 2 in a unified manner based on various signals sent from the exposure device controller 110, the measured value of pulse energy, the detected value of gas pressure, etc.

[0073] Furthermore, the gas laser device 2 is not necessarily limited to a narrowband laser device; it can also be a laser device that outputs naturally oscillating light. For example, a high-reflectivity mirror can be configured instead of the narrowband module 15.

[0074] 1.2 Actions

[0075] Next, the operation of the comparative example gas laser device 2 will be explained. First, the processor 14 controls the laser gas supply device 18a to supply laser gas into the container 10a of the laser cavity 10, thereby driving the motor 23a to rotate the fan 23. Thus, as... Figure 2 As shown by the middle arrow, the laser gas filled into container 10a is circulated.

[0076] The processor 14 receives the target pulse energy and the oscillation trigger signal from the exposure device controller 110. Furthermore, the oscillation trigger signal is a signal that instructs the gas laser device 2 to output a pulse of pulsed laser PL.

[0077] The processor 14 sets the charging voltage of the charger 11 to correspond to the target pulse energy. The processor 14 synchronously activates the switch SW of the PPM 12 with the oscillation trigger signal.

[0078] When the switch SW of PPM12 changes from open to closed, a voltage is applied between the pre-ionization inner electrode 33 and the pre-ionization outer electrode 31 of the pre-ionization electrode 30, and between the cathode electrode 20a and the anode electrode 20b. This generates a corona discharge in the pre-ionization electrode 30, producing UV (ultraviolet) light. By irradiating the laser gas in the discharge space 27 with UV light, the laser gas is pre-ionized.

[0079] Subsequently, when the voltage between the cathode electrode 20a and the anode electrode 20b reaches the insulation breakdown voltage, a main discharge is generated in the discharge space 27. If the discharge direction of the main discharge is set to the direction of electron flow, then the discharge direction is from the cathode electrode 20a toward the anode electrode 20b. When the main discharge occurs, the laser gas in the discharge space 27 is excited and emits light.

[0080] The light emitted from the laser gas is reflected by the narrowing module 15 and the output coupling mirror 16, and travels back and forth within the laser resonator, thereby generating laser oscillation. The light narrowed by the narrowing module 15 is output as a pulsed laser PL from the output coupling mirror 16.

[0081] A portion of the pulsed laser PL output from the output coupling mirror 16 is incident on the pulse energy measuring unit 13. The pulse energy measuring unit 13 measures the pulse energy of the incident pulsed laser PL and outputs the measured value to the processor 14.

[0082] Processor 14 calculates the difference ΔE between the measured pulse energy and the target pulse energy. Processor 14 performs feedback control on the charging voltage in a manner that keeps the difference ΔE close to 0.

[0083] When the charging voltage exceeds the maximum allowable range, the processor 14 controls the laser gas supply device 18a to supply laser gas into the container 10a until a predetermined pressure is reached. Conversely, when the charging voltage falls below the minimum allowable range, the processor 14 controls the laser gas exhaust device 18b to exhaust laser gas from the container 10a until a predetermined pressure is reached.

[0084] The pulsed laser PL is incident on the exposure device 100 through the pulse energy meter 13.

[0085] Furthermore, within container 10a, discharge products are generated due to the main discharge in discharge space 27. These discharge products are driven away from discharge space 27 by airflow generated by fan 23. This stabilizes the discharge. Additionally, the temperature of the laser gas rises due to the main discharge. The heated laser gas is cooled by cooling water flowing within heat exchanger 24 as it passes through heat exchanger 24.

[0086] In addition, the main discharge generates sound waves. The generated sound waves are attenuated by being absorbed by the sound-absorbing components 29a and 29b.

[0087] 1.3 Research Topic

[0088] Figure 3 The portion of the laser cavity 10 in the comparative example containing the main electrode 20 is shown in a schematic diagram. Figure 3The dashed lines shown schematically represent the sound waves generated by the main discharge. For example... Figure 3 As shown, the acoustic wave generated by the main discharge is a compression wave of the laser gas, which propagates while spreading from the discharge space 27. This acoustic wave may sometimes remain in the discharge space 27 at the next occurrence of the main discharge, or it may be reflected back and remain in the discharge space 27 by insulating guides 28a, 28b, and other structures within the container 10a. If the main discharge occurs with acoustic waves remaining in the discharge space 27, it may adversely affect the laser performance, such as the spectral linewidth of the pulsed laser PL.

[0089] Therefore, in the comparative example gas laser device 2, sound-absorbing elements 29a and 29b are arranged near the discharge space 27 in order to achieve sound wave attenuation.

[0090] However, if the repetition frequency of the pulsed laser PL increases, the time interval between main discharges becomes shorter. Therefore, sometimes the next main discharge begins before the acoustic waves generated by the previous main discharge have been sufficiently attenuated by the sound-absorbing elements 29a and 29b. As a result, the phenomenon of acoustic waves remaining in the discharge space 27 becomes significant, and the aforementioned adverse effects on laser performance may increase. Therefore, it is desirable to attenuate the acoustic waves returning to the discharge space 27 more effectively.

[0091] In view of the above-mentioned problems, the present invention aims to effectively attenuate the sound waves returning to the discharge space 27.

[0092] 2. Implementation Method

[0093] 2.1 Structure

[0094] The gas laser device 2 of the embodiment of the present invention has the same structure as the gas laser device 2 of the comparative example, except that the structure inside the laser cavity 10 is different.

[0095] Figure 4 The portion of the laser cavity 10 containing the main electrode 20 in the embodiment is shown schematically. In this embodiment, an insulating guide 40 with a plurality of grooves 41 is provided instead of the insulating guide 28a. The insulating guide 40 has the same structure as the insulating guide 28a, except that a plurality of grooves 41 are formed on the surface 40a.

[0096] Figure 5 and Figure 6 The structure of the insulating guide 40 is shown. Figure 5 The surface 40a of the insulating guide 40 is shown. Figure 6 Show along Figure 5 The cross section is obtained by cutting along line AA.

[0097] like Figure 5As shown, multiple slots 41 extend along the X direction, which is parallel to the direction of laser gas flow. In this embodiment, as... Figure 6 As shown, the cross-section of each of the multiple grooves 41 is a quadrilateral with depth d and width t as its sides. In this embodiment, the depth d of each of the multiple grooves 41 is equal. Here, the cross-section refers to the plane orthogonal to the direction of laser gas flow, that is, the cutting surface obtained when the groove 41 is cut along the YZ plane.

[0098] Furthermore, the plurality of grooves 41 includes combinations of two adjacent grooves 41 with mutually different cross-sectional shapes. Preferably, more than 80% of all grooves 41 have a cross-sectional shape different from that of adjacent grooves 41, and more preferably, all grooves 41 have a cross-sectional shape different from that of adjacent grooves 41. Here, different cross-sectional shape means that at least one of depth d and width t is different. Depth d is the dimension of groove 41 in the direction orthogonal to surface 40a. Width t is the dimension of groove 41 in the direction orthogonal to the extension direction and the direction of depth d.

[0099] In this embodiment, the depth d of all grooves 41 is set to be equal, so different cross-sectional shapes refer to different widths t.

[0100] Furthermore, regarding the arrangement of the plurality of slots 41, it is preferable to include a combination where the arrangement spacing p in the direction orthogonal to the extension direction and depth d of the slot 41 differs from that between adjacent slots 41. That is, preferably, among all the arrangement spacings p, at least one spacing is different from the others. Here, the arrangement spacing p refers to the distance between the center positions of two adjacent slots 41.

[0101] When the wavelength of the acoustic wave generated by the main discharge is set to λ, the width t preferably satisfies the following equation (1). Here, the wavelength λ is determined by the pressure, type, temperature, etc. of the laser gas in container 10a.

[0102] λ / 4≤t≤λ…(1)

[0103] The wavelength λ is, for example, 7 mm or more and 10 mm or less, so more specifically, the width t preferably satisfies the following equation (2).

[0104] 1.75mm≤t≤10mm…(2)

[0105] Furthermore, the depth d should also preferably satisfy the following equation (3).

[0106] λ / 4≤d≤λ…(3)

[0107] In addition, considering that the wavelength λ is, for example, 7 mm or more and 10 mm or less, the depth d preferably satisfies the following equation (4).

[0108] 1.75mm≤d≤10mm…(4)

[0109] Figure 7 The structure of the groove 41 is shown when viewed from the side. In this embodiment, the depth d of each groove 41 is constant in the extending direction.

[0110] 2.2 Actions

[0111] Regarding the basic operation of the gas laser device 2 in this embodiment, it is the same as that in the comparative example, except that the insulating guide 40 plays a unique role in attenuating sound waves.

[0112] When sound waves are generated due to the main discharge, they may sometimes return to the discharge space 27 after being reflected by various structures arranged in the container 10a. At this time, the sound waves may sometimes be reflected by the grounding plate 21, the pre-ionization electrode 30, and other structures, and then incident on the insulating guide 40.

[0113] Specifically, the sound waves reflected in the pre-ionization electrode 30 will be incident on various positions of the plurality of grooves 41 formed on the surface 40a of the insulating guide 40 in the path of returning to the discharge space 27 via the insulating guide 40.

[0114] The plurality of grooves 41 include combinations of adjacent grooves 41 with different cross-sectional shapes, so that the sound waves reflected by the surface 40a are dispersed as components with various phases and reflection directions.

[0115] The sound waves reflected in this way attenuate each other due to the difference in phase and reflection direction, causing the compression wave components of the laser gas to weaken each other.

[0116] 2.3 Effects

[0117] In this embodiment, the acoustic waves incident on the insulating guide 40 and reflected weaken each other and attenuate, thus attenuating the acoustic waves returning to the discharge space 27. As a result, laser performance can be improved.

[0118] Furthermore, even when operating at a high repetition frequency with a shorter discharge interval, it can suppress the influence of the acoustic waves generated by the previous discharge on the next main discharge, thus achieving stable laser output even in high-throughput operating environments.

[0119] Furthermore, since the multiple grooves 41 are formed in a direction parallel to the direction of laser gas flow, the impact on the laser gas flow is minimal. Therefore, according to this embodiment, an acoustic attenuation effect can be added without adversely affecting the circulation performance of the laser gas.

[0120] In this embodiment, the insulating guide 28a of the comparative examples, which is disposed upstream of the cathode electrode 20a from the laser gas, is provided as an insulating guide 40 having multiple grooves 41. This is because, considering that a pre-ionization electrode 30 is disposed upstream of the laser gas, the acoustic wave contains a significant amount of components reflected by the pre-ionization electrode 30 and incident on the insulating guide 28a. Therefore, by providing an insulating guide 40 upstream of the laser gas, the acoustic wave returning to the discharge space 27 can be effectively attenuated.

[0121] Furthermore, the insulating guide 28b, located downstream of the cathode electrode 20a from the laser gas, can also be configured with a plurality of grooves 41, similar to the insulating guide 40. It is acceptable as long as at least one of the insulating guides 28a and 28b in the comparative example has the same structure as the insulating guide 40.

[0122] Furthermore, the pre-ionization electrode 30 is not limited to being disposed on the upstream side of the laser gas, but may also be disposed on the downstream side. In order to attenuate the acoustic waves reflected from the pre-ionization electrode 30 and incident on the insulating guide 28a, the insulating guide 40 is preferably disposed at least on the side where the pre-ionization electrode 30 is disposed.

[0123] 3. Variations

[0124] The following describes various variations of the insulating guide 40.

[0125] 3.1 First Variation

[0126] Figure 8 The cross-section of the insulating guide 40 of the first modified example is shown. The insulating guide 40 of this modified example differs structurally from the above embodiment in that the depths d of two adjacent grooves 41 are different from each other. For example, grooves 41 having a first depth and grooves 41 having a second depth different from the first depth are alternately arranged on the surface 40a.

[0127] In this modified example, it is preferable that the depth d of all grooves 41 formed on surface 40a satisfies the above equation (3).

[0128] In addition, it is also preferable that the depth d of all grooves 41 formed on surface 40a satisfies the above formula (4).

[0129] Additionally, the plurality of grooves 41 formed on surface 40a may include grooves 41 having a depth d that satisfies the above equation (3) and grooves 41 having a depth d that does not satisfy the above equation (3). For example, it is also possible that one of the first depth and the second depth described above satisfies the above equation (3), while the other does not.

[0130] Additionally, the plurality of grooves 41 formed on surface 40a may include grooves 41 having a depth d that satisfies the above equation (4) and grooves 41 having a depth d that does not satisfy the above equation (4). For example, it is also possible that one of the first depth and the second depth described above satisfies the above equation (4), while the other does not satisfy the above equation (4).

[0131] In this modified example, the multiple slots 41 include combinations of two adjacent slots 41 that differ in both width t and depth d, thus further increasing the diversity of the phase difference and propagation direction of the sound waves reflected by the surface 40a. Consequently, the attenuation effect of the sound waves is further improved.

[0132] 3.2 Second variation

[0133] Figure 9 The diagram shows the structure of the groove 41 of the insulating guide 40 in the second modified example when viewed from the side. The structural difference between the insulating guide 40 of this modified example and the embodiment described above is that the depth d of each groove 41 is formed to be greater on the side opposite to the cathode electrode 20a than on the side opposite to the cathode electrode 20a. Specifically, the depth d of each groove 41 is formed to gradually increase with distance from the cathode electrode 20a.

[0134] Alternatively, the groove 41 may not be formed in the proximity region R of the insulating guide 40 that is close to the cathode electrode 20a. For example, the proximity region R is the region within 10 mm of the cathode electrode 20a.

[0135] The depth d of each groove 41 at the end opposite to the cathode electrode 20a preferably satisfies the above formula (3) or formula (4).

[0136] In this modified example, similar to the embodiment described above, by diversifying the phase and reflection direction of the sound waves reflected from surface 40a, an attenuation effect of the sound waves can be obtained. Furthermore, by not forming a groove 41 in the proximity region R of the cathode electrode 20a, the flow of laser gas near the cathode electrode 20a is rectified without turbulence. As a result, the circulation performance and discharge characteristics of the laser gas are improved.

[0137] 3.3 Third variation

[0138] Figure 10 and Figure 11 The structure of the insulating guide 40 in the third modified example is shown. Figure 10 The surface 40a of the insulating guide 40 is shown. Figure 11 Show along Figure 10 The cross-section is obtained by cutting the BB line. The insulating guide 40 in this modified example differs structurally from the above embodiment in that the cross-section of each groove 41 is arc-shaped. Furthermore, the arc shape includes a portion of a circle and a portion of an ellipse.

[0139] The insulating guide 40 in this modified example has the same structure as the embodiment described above, except for the cross-sectional shape of each slot 41. That is, the plurality of slots 41 includes a combination of two adjacent slots 41 with different cross-sectional shapes. In addition, the plurality of slots 41 preferably includes different combinations of the arrangement spacing p between adjacent slots 41.

[0140] In this modified example, the insulating guide 40 can also be configured in a manner similar to the first modified example, where the depths d of two adjacent grooves 41 are different. Alternatively, the insulating guide 40 can also be configured in a manner similar to the second modified example, where the depth d of each groove 41 is greater on the side opposite to the cathode electrode 20a than on the side opposite to the cathode electrode 20a.

[0141] In this modified example, the cross-section of each groove 41 is circular, thereby further diversifying the phase and reflection direction of the sound waves reflected from the surface 40a. As a result, the attenuation effect of the sound waves is further improved.

[0142] 3.4 Fourth Variation Example

[0143] Figure 12 The cross-section of the insulating guide 40 in the fourth modification is shown. The insulating guide 40 in this modification differs from the third modification only in that the cross-section of each groove 41 is triangular. The function and effect of this modification are the same as those of the third modification.

[0144] 4. Manufacturing methods for electronic devices

[0145] Figure 13 An example of the structure of the exposure apparatus 100 is shown schematically. The exposure apparatus 100 includes an illumination optics system 104 and a projection optics system 106. The illumination optics system 104 illuminates, for example, a mask pattern (not shown) disposed on a mask stage RT using a pulsed laser PL incident from a gas laser device 2. The projection optics system 106 projects and reduces the pulsed laser PL passing through the mask onto a workpiece (not shown) disposed on a workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist.

[0146] The exposure apparatus 100 exposes a pulsed laser PL, reflecting the mask pattern, onto a workpiece by synchronously and parallelly moving the mask stage RT and the workpiece stage WT. After transferring the mask pattern onto a semiconductor wafer through the above exposure process, a semiconductor device can be manufactured through multiple processes. The semiconductor device is an example of the "electronic device" in this disclosure.

[0147] In addition, the gas laser device 2 is not limited to the manufacture of electronic devices, but can also be used for laser processing such as hole drilling.

[0148] The foregoing description is not limiting, but merely illustrative. Therefore, modifications to the embodiments of this disclosure can be made without departing from the claims, as will be apparent to those skilled in the art.

[0149] Unless explicitly stated otherwise, all terms used in this specification and the claims as a whole shall be interpreted as “non-limiting” terms. For example, terms such as “comprising,” “having,” “possessing,” and “comprise” shall be interpreted as “not excluding the presence of structural elements other than those described.” Furthermore, the modifier “a” shall be interpreted as “at least one” or “one or more.” Additionally, the phrase “at least one of A, B, and C” shall be interpreted as “A,” “B,” “C,” “A+B,” “A+C,” “B+C,” or “A+B+C,” and shall be interpreted as including combinations of these and elements other than “A,” “B,” and “C.”

Claims

1. A laser cavity, comprising: A container filled with laser gas; A first electrode is disposed within the container; The second electrode is disposed opposite to the first electrode at a position closer to the inner wall of the container than the first electrode; A fan that directs the laser gas through the discharge space between the first and second electrodes; and An insulating guide is disposed relative to the second electrode on at least one of the upstream and downstream sides of the laser gas. Multiple grooves extending in a direction parallel to the direction of laser gas flow are formed on the surface of the insulating guide. The plurality of slots comprises a combination of two adjacent slots with different cross-sectional shapes, the cross-sectional shapes being obtained by cutting the plurality of slots along a plane orthogonal to the direction of the laser gas flow.

2. The laser cavity according to claim 1, wherein, More than 80% of the slots have a cross-sectional shape that differs from that of the adjacent slots.

3. The laser cavity according to claim 1, wherein, The cross-sectional shape of each of the plurality of slots is different from that of the adjacent slots.

4. The laser cavity according to claim 1, wherein, The combination is a combination of two adjacent slots with different widths.

5. The laser cavity according to claim 1, wherein, The combination is a combination of two adjacent slots with different depths.

6. The laser cavity according to claim 1, wherein, When the depth of each of the plurality of grooves is set to d, the following condition is met: 1.75mm≤d≤10mm.

7. The laser cavity according to claim 1, wherein, When the width of each of the plurality of slots is set to t, the following condition is met: 1.75mm≤t≤10mm.

8. The laser cavity according to claim 1, wherein, The cross-sectional shape is quadrilateral.

9. The laser cavity according to claim 1, wherein, The cross-sectional shape is an arc shape.

10. The laser cavity according to claim 1, wherein, The cross-sectional shape is triangular.

11. The laser cavity according to claim 1, wherein, The depth of each of the plurality of grooves is greater on the side opposite to the second electrode than on the side opposite to the second electrode.

12. The laser cavity according to claim 11, wherein, The plurality of grooves were not formed in the proximity region to the second electrode.

13. The laser cavity according to claim 1, wherein, The laser cavity has a pre-ionization electrode, which is disposed on at least one of the upstream side and the downstream side of the second electrode. The insulating guide is disposed on the side where the pre-ionization electrode is located, relative to the second electrode.

14. A gas laser device, comprising: Optical resonators; and The laser cavity is configured such that the optical path of the optical resonator passes through it. The laser cavity has: A container filled with laser gas; A first electrode is disposed within the container; The second electrode is disposed opposite to the first electrode at a position closer to the inner wall of the container than the first electrode; A fan that causes the laser gas to flow through the discharge space between the first electrode and the second electrode; as well as An insulating guide is disposed relative to the second electrode on at least one of the upstream and downstream sides of the laser gas. Multiple grooves extending in a direction parallel to the direction of laser gas flow are formed on the surface of the insulating guide. The plurality of slots comprises a combination of two adjacent slots with different cross-sectional shapes, the cross-sectional shapes being obtained by cutting the plurality of slots along a plane orthogonal to the direction of the laser gas flow.

15. The gas laser device according to claim 14, wherein, More than 80% of the slots have a cross-sectional shape that differs from that of the adjacent slots.

16. The gas laser device according to claim 14, wherein, The cross-sectional shape of each of the plurality of slots is different from that of the adjacent slots.

17. The gas laser device according to claim 14, wherein, The combination is a combination of two adjacent slots with different widths.

18. The gas laser device according to claim 14, wherein, The combination is a combination of two adjacent slots with different depths.

19. The gas laser device according to claim 14, wherein, When the depth of each of the plurality of grooves is set to d, the following condition is met: 1.75mm≤d≤10mm.

20. A method for manufacturing an electronic device, wherein, The manufacturing method of this electronic device includes the following steps: Laser is generated using a gas laser device; The laser is output to the exposure device; and Within the exposure apparatus, the laser is used to expose a photosensitive substrate to manufacture electronic devices. The gas laser device has the following features: Optical resonators; and The laser cavity is configured such that the optical path of the optical resonator passes through it. The laser cavity has: A container filled with laser gas; A first electrode is disposed within the container; The second electrode is disposed opposite to the first electrode at a position closer to the inner wall of the container than the first electrode; A fan that causes the laser gas to flow through the discharge space between the first electrode and the second electrode; as well as An insulating guide is disposed relative to the second electrode on at least one of the upstream and downstream sides of the laser gas. Multiple grooves extending in a direction parallel to the direction of laser gas flow are formed on the surface of the insulating guide. The plurality of slots comprises a combination of two adjacent slots with different cross-sectional shapes, the cross-sectional shapes being obtained by cutting the plurality of slots along a plane orthogonal to the direction of the laser gas flow.

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