Gas laser device and method for manufacturing electronic device

Abstract

A gas laser apparatus and a method of manufacturing an electronic device are provided. A gas laser device according to one aspect of the present disclosure performs discharge excitation of a laser gas passing through a discharge space between a first discharge electrode and a second discharge electrode, the gas laser device comprising: a plate that supports the first discharge electrode; a guide member that is disposed on the plate and guides the laser gas to the discharge space; a dielectric tube disposed between the guide member and the first discharge electrode so as to be separated from each of the plate and the first discharge electrode; a first path which is configured so as to include the guide member and into which a portion of the laser gas flows as a split flow; a second path configured so as to include a dielectric tube and a plate, the second path being configured so as to allow the shunt flowing out from the first path to flow; and a third path configured so as to include the dielectric tube and the first discharge electrode, and to guide the shunt flowing out from the second path to the upstream side of the discharge space with respect to the laser gas.

Description

Technical Field

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

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

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

[0004] Patent Document 1: Japanese Patent No. 2714357

[0005] Patent Document 2: U.S. Patent No. 6,529,538 Summary of the Invention

[0006] A gas laser device according to one aspect of the present disclosure excites laser gas passing through a discharge space between a first discharge electrode and a second discharge electrode. The gas laser device comprises: a plate supporting the first discharge electrode; a guide member disposed on the plate for guiding the laser gas into the discharge space; a dielectric tube disposed between the guide member and the first discharge electrode, spaced from the plate and the first discharge electrode; a first path including the guide member, into which a portion of the laser gas flows as a branch flow; a second path including the dielectric tube and the plate, into which the branch flow flowing out of the first path flows; and a third path including the dielectric tube and the first discharge electrode, which guides the branch flow flowing out of the second path toward the upstream side of the laser gas relative to the discharge space.

[0007] According to one aspect of the present disclosure, a method for manufacturing an electronic device includes the following steps: generating laser light using a gas laser device, outputting the laser light to an exposure device, and exposing the laser light on a photosensitive substrate within the exposure device to manufacture the electronic device. The gas laser device excites laser gas passing through a discharge space between a first discharge electrode and a second discharge electrode to discharge. The gas laser device includes: a plate supporting the first discharge electrode; a guide member disposed on the plate for guiding the laser gas into the discharge space; a dielectric tube disposed between the guide member and the first discharge electrode, spaced apart from the plate and the first discharge electrode; a first path including the guide member, into which a portion of the laser gas flows as a branch flow; a second path including the dielectric tube and the plate, into which the branch flow exiting the first path flows; and a third path including the dielectric tube and the first discharge electrode, which guides the branch flow exiting the second path toward the upstream side of the laser gas relative to the discharge space. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Several embodiments of the present disclosure are described below by way of example only with reference to the accompanying drawings.

[0009] Figure 1 It is a side view schematically showing the structure of a gas laser device according to a comparative example.

[0010] Figure 2 It is a cross-sectional view schematically showing the structure of a gas laser device according to a comparative example.

[0011] Figure 3 It is a cross-sectional view showing in detail the structure near the main electrode in the laser cavity.

[0012] Figure 4 This is a diagram showing an example of an ideal flow velocity distribution of the laser gas passing through the discharge space.

[0013] Figure 5 This is a timing chart showing the operation of the gas laser device.

[0014] Figure 6 This is a diagram showing an example of simulation results of the flow of laser gas.

[0015] Figure 7 This is a diagram showing an example of the flow velocity distribution of the laser gas passing through the discharge space when a void is generated.

[0016] Figure 8 This is a cross-sectional view showing in detail the structure near the main electrode in the laser cavity of the first embodiment.

[0017] Figure 9 This is an enlarged view of the area near the dielectric tube.

[0018] Figure 10 This is a plan view of a portion including an anode electrode and a dielectric tube as viewed from the discharge space.

[0019] Figure 11 This is a diagram showing an example of simulation results of the flow of laser gas in the first embodiment.

[0020] Figure 12 This is a diagram showing an example of the flow velocity distribution of the laser gas passing through the discharge space in the first embodiment.

[0021] Figure 13 This is a timing chart showing the operation of the gas laser device according to the first embodiment.

[0022] Figure 14 This is a diagram showing in detail the structure near the main electrode in the laser cavity of the second embodiment.

[0023] Figure 15 This is a plan view of a portion including an anode electrode and a dielectric tube as viewed from the discharge space.

[0024] Figure 16 This is a diagram showing an example of simulation results of the flow of laser gas in the second embodiment.

[0025] Figure 17 It is a diagram schematically showing a configuration example of an exposure apparatus. DETAILED DESCRIPTION

[0026] <Content>

[0027] 1. Comparative Example

[0028] 1.1 Structure

[0029] 1.2 Action

[0030] 1.3 Topics

[0031] 2. First Implementation

[0032] 2.1 Structure

[0033] 2.2 Action

[0034] 2.3 Effect

[0035] 3. Second embodiment

[0036] 3.1 Structure

[0037] 3.2 Action

[0038] 3.3 Effect

[0039] 4. Manufacturing methods of electronic devices

[0040] Below, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The embodiments described below illustrate several examples of the present disclosure and do not limit the content of the present disclosure. In addition, the structures and actions described in the embodiments are not necessarily all required structures and actions of the present disclosure. In addition, the same reference numerals are given to the same structural elements and repeated descriptions are omitted.

[0041] 1. Comparative Example

[0042] First, comparative examples of the present disclosure will be described. The comparative examples of the present disclosure are methods that the applicant has recognized as being known only to the applicant, and are not publicly known examples that the applicant has acknowledged.

[0043] 1.1 Structure

[0044] use Figure 1 and Figure 2 The structure of a gas laser device 2 according to a comparative example will be described. Figure 1 The structure of the gas laser device 2 is schematically shown. Figure 2 Observed from the Z direction Figure 1 1 is a cross-sectional view of a gas laser device 2. The gas laser device 2 is a discharge-excitation type gas laser device that excites laser gas by discharge, and is, for example, an excimer laser device.

[0045] exist Figure 1 In the figure, the direction of travel of the pulsed laser light PL output from the gas laser device 2 is the Z direction. The discharge direction described later is the Y direction. Furthermore, the direction perpendicular to the Z and Y directions is the X direction. The pulsed laser light PL is an example of "laser" in the technology disclosed herein.

[0046] exist Figure 1 In FIG, the gas laser device 2 includes a laser cavity 10, a charger 11, a pulse power module (PPM) 12, a pulse energy measurement unit 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.

[0047] The laser cavity 10 is, for example, a metal container formed of aluminum metal with nickel plating on the surface. Figure 1 and Figure 2 As shown, a main electrode 20, a ground plate 21, wiring 22, a fan 23, a heat exchanger 24, an insulating guide 28, a conductive guide 29, and a preionization electrode 30 are provided inside the laser cavity 10. The preionization electrode 30 includes a preionization outer electrode 31, a dielectric tube 32, and a preionization inner electrode 33.

[0048] A laser gas containing fluorine as a laser medium is enclosed in the laser cavity 10. The laser gas contains, for example, rare gases such as argon, krypton, and xenon, buffer gases such as neon and helium, and halogen gases such as fluorine and chlorine.

[0049] An opening is formed in the laser cavity 10. An electrical insulating plate 26 having a feedthrough 25 embedded therein is attached to the laser cavity 10 via an O-ring (not shown) to block the opening. The PPM 12 is placed on the electrical insulating plate 26. The laser cavity 10 is grounded.

[0050] PPM 12 includes a charging capacitor (not shown) connected to main electrode 20 via feedthrough 25. PPM 12 includes switch SW for discharging main electrode 20. Charger 11 is connected to the charging capacitor of PPM 12. Hereinafter, discharge generated by main electrode 20 is referred to as main discharge.

[0051] The main electrode 20 is composed of a cathode electrode 20a and an anode electrode 20b. The cathode electrode 20a and the anode electrode 20b are arranged so that their discharge surfaces face each other within the laser cavity 10. The space between the discharge surface of the cathode electrode 20a and the discharge surface of the anode electrode 20b is referred to as a discharge space 27. The surface of the cathode electrode 20a opposite to the discharge surface is supported by an electrically insulating plate 26 and connected to the feedthrough 25. The surface of the anode electrode 20b opposite to the discharge surface is supported by a ground plate 21. The anode electrode 20b is an example of a "first discharge electrode" in the technology disclosed herein. The cathode electrode 20a is an example of a "second discharge electrode" in the technology disclosed herein. The ground plate 21 is an example of a "plate" in the technology disclosed herein.

[0052] The ground plate 21 is connected to the laser cavity 10 via the wiring 22. The laser cavity 10 is grounded. Therefore, the ground plate 21 is grounded via the wiring 22. The end portion of the ground plate 21 in the Z direction is fixed to the laser cavity 10.

[0053] The fan 23 is a cross-flow fan for circulating the laser gas in the laser cavity 10 and is disposed on the side of the ground plate 21 opposite to the discharge space 27. The laser cavity 10 is connected to a motor 23a for rotating the fan 23.

[0054] Laser gas blown from 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 the laser gas by exchanging heat between the refrigerant supplied to the heat exchanger 24 and the laser gas.

[0055] Insulating guide 28 is disposed on the surface of electrical insulating plate 26 on the discharge space 27 side, sandwiching cathode electrode 20a. Insulating guide 28 is formed into a shape that guides the flow of laser gas, allowing the laser gas from fan 23 to flow efficiently between cathode electrode 20a and anode electrode 20b. Insulating guide 28 and electrical insulating plate 26 are formed, for example, from a ceramic such as alumina (Al2O3) that has low reactivity with fluorine gas.

[0056] Conductive guide 29 is disposed on the surface of ground plate 21 on the discharge space 27 side, sandwiching anode electrode 20b. Like insulating guide 28, conductive guide 29 is formed into a shape that guides the flow of laser gas, allowing the laser gas from fan 23 to flow efficiently between cathode electrode 20a and anode electrode 20b. Conductive guide 29 is formed, for example, from porous nickel metal, which has low reactivity with fluorine gas.

[0057] Laser gas supply device 18a and laser gas exhaust device 18b are connected to laser cavity 10. Laser gas supply device 18a includes a valve and a flow control valve and is connected to a gas cylinder containing laser gas. Laser gas exhaust device 18b includes a valve and an exhaust pump.

[0058] Windows 10a and 10b are provided at the ends of the laser cavity 10 for emitting light generated in the laser cavity 10 to the outside. The laser cavity 10 is configured so that the optical path of the optical resonator passes through the discharge space 27 and the windows 10a and 10b.

[0059] 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 10a and transmits the light toward the grating 15b.

[0060] Grating 15b is arranged in a Littrow configuration, where the incident angle and diffraction angle are equal. Grating 15b is a wavelength-selective element that selectively extracts light near a specific wavelength based on the diffraction angle. The spectral width of the light returning from grating 15b to laser cavity 10 via prism 15a is narrowed.

[0061] The output coupling mirror 16 transmits a portion of the light emitted from the laser cavity 10 through the window 10b and reflects the other portion to return it to the laser cavity 10. The surface of the output coupling mirror 16 is coated with a partial reflection film.

[0062] The light emitted from the laser cavity 10 travels back and forth between the bandwidth narrowing 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 pulsed laser light PL via the output coupling mirror 16.

[0063] The pulse energy measurement unit 13 is arranged on the optical path of the pulse laser light PL outputted via the output coupling mirror 16. The pulse energy measurement unit 13 includes a beam splitter 13a, a focusing optical system 13b, and a photosensor 13c.

[0064] Beam splitter 13a transmits pulsed laser light PL with high transmittance and reflects a portion of the pulsed laser light PL toward focusing optical system 13b. Focusing optical system 13b focuses the light reflected by beam splitter 13a onto the light-receiving surface of optical sensor 13c. Optical sensor 13c measures the pulse energy of the light focused on the light-receiving surface and outputs the measured value to processor 14.

[0065] Pressure sensor 17 detects the gas pressure in laser cavity 10 and outputs the detected value to processor 14. Processor 14 determines the gas pressure of the laser gas in laser cavity 10 based on the detected gas pressure value and the charging voltage of charger 11.

[0066] The charger 11 is a high-voltage power source that supplies a charging voltage to the charging capacitor included in the PPM 12. The switch SW of the PPM 12 is controlled by the processor 14. When the switch SW changes from off to on, the PPM 12 generates a high-voltage pulse from the electric energy held by the charging capacitor and applies it to the main electrode 20.

[0067] The processor 14 is a processing device that transmits and receives various signals to and from the exposure device controller 110 provided in the exposure device 100. For example, the target pulse energy of the pulsed laser light PL output to the exposure device 100, an oscillation trigger signal, etc. are transmitted from the exposure device controller 110 to the processor 14.

[0068] The processor 14 comprehensively controls the operation of each component of the gas laser device 2 based on various signals sent from the exposure device controller 110 , the measured value of pulse energy, the detected value of gas pressure, and the like.

[0069] The processor 14 functions as a controller for the gas laser device 2. For example, the processor 14 is a processing device that includes a storage device storing a control program and a CPU (Central Processing Unit) that executes the control program. The processor 14 is specifically configured or programmed to perform the various processes included in the present disclosure. The storage device is a non-temporary computer-readable storage medium, and includes, for example, a main memory device and a secondary memory device. Alternatively, the storage device may be a semiconductor memory, a hard disk drive (HDD), a solid-state drive (SSD), or a combination thereof.

[0070] Figure 3The structure near main electrode 20 in laser cavity 10 is shown in detail. In the following description, the upstream side refers to the side where laser gas flows into discharge space 27 with respect to discharge space 27. The downstream side refers to the side where laser gas flows out of discharge space 27 with respect to discharge space 27.

[0071] The preionization outer electrode 31 is positioned between the anode electrode 20b and the dielectric tube 32, and is held in contact with the side surface of a metal holding member 34. The holding member 34 is fixed to the upstream side surface of the anode electrode 20b. The preionization inner electrode 33 is positioned within the dielectric tube 32, and the preionization outer electrode 31 is in contact with the exterior of the dielectric tube 32.

[0072] The insulating guide 28 is arranged to cover the upstream and downstream side surfaces of the cathode electrode 20a. The surface of the insulating guide 28 is inclined so as to get closer to the electrical insulating plate 26 as it moves away from the cathode electrode 20a.

[0073] The conductive guide 29 includes a first guide member 29a, a second guide member 29b, and a third guide member 29c. The first guide member 29a and the third guide member 29c are positioned upstream of the anode electrode 20b. The second guide member 29b is positioned downstream of the anode electrode 20b. The first guide member 29a is an example of a "guide member" in the disclosed technology.

[0074] First guide member 29a is disposed on ground plate 21 to guide laser gas toward discharge space 27. Dielectric tube 32 is disposed between first guide member 29a and anode electrode 20b, spaced from each of ground plate 21 and anode electrode 20b. Second guide member 29b is disposed on ground plate 21 to cover the downstream side of anode electrode 20b.

[0075] Third guide member 29c is disposed between dielectric tube 32 and anode electrode 20b so as to cover the upstream side surface of anode electrode 20b and to guide laser gas toward discharge space 27. Third guide member 29c is close to dielectric tube 32.

[0076] The entire surface of the conductive guide 29 is inclined so as to get closer to the ground plate 21 as it becomes farther away from the anode electrode 20 b .

[0077] The upstream and downstream side surfaces near the discharge surface of cathode electrode 20a are not covered by insulating guide 28, so cathode electrode 20a protrudes from the surface of insulating guide 28 toward anode electrode 20b.

[0078] The upstream and downstream side surfaces near the discharge surface of the anode electrode 20b are not covered by the conductive guide 29, so the anode electrode 20b protrudes from the surface of the conductive guide 29 toward the cathode electrode 20a.

[0079] 1.2 Action

[0080] Next, the operation of the gas laser device 2 of the comparative example will be described. First, the processor 14 controls the laser gas supply device 18a to supply laser gas into the laser cavity 10 and drives the motor 23a to rotate the fan 23. Figure 2 As shown by the middle arrow, the laser gas filled in the laser cavity 10 circulates.

[0081] The processor 14 receives the target pulse energy and the oscillation trigger signal from the exposure device controller 110. The oscillation trigger signal is a signal that instructs the gas laser device 2 to output the pulsed laser light PL of one pulse.

[0082] The processor 14 sets a charging voltage corresponding to the target pulse energy in the charger 11. The processor 14 operates the switch SW of the PPM 12 in synchronization with the oscillation trigger signal.

[0083] When the switch SW of PPM 12 is turned on from off, a voltage is applied between the preionization inner electrode 33 and the preionization outer electrode 31 of the preionization electrode 30, and between the cathode electrode 20a and the anode electrode 20b. This generates a corona discharge in the preionization electrode 30, generating UV (ultraviolet) light. The UV light irradiates the laser gas in discharge space 27, preionizing the laser gas.

[0084] When the voltage between cathode electrode 20a and anode electrode 20b reaches the dielectric breakdown voltage, a main discharge occurs in discharge space 27. The main discharge is defined as the direction of electron flow, which is from cathode electrode 20a toward anode electrode 20b. When the main discharge occurs, the laser gas in discharge space 27 is excited, emitting light.

[0085] The light emitted from the laser gas is reflected by the band-narrowing module 15 and the output coupling mirror 16 and travels back and forth in the laser resonator, thereby oscillating laser light. The light narrowed by the band-narrowing module 15 is output from the output coupling mirror 16 as pulsed laser light PL.

[0086] A portion of the pulse laser light PL output from the output coupling mirror 16 enters the pulse energy measuring unit 13 . The pulse energy measuring unit 13 measures the pulse energy of the incident pulse laser light PL and outputs the measured value to the processor 14 .

[0087] The processor 14 calculates the difference ΔE between the measured pulse energy and the target pulse energy. Based on the difference ΔE, the processor 14 performs feedback control on the charging voltage so that the measured pulse energy reaches the target pulse energy.

[0088] If the charging voltage is higher than the maximum value within the allowable range, processor 14 controls laser gas supply device 18a to supply laser gas into laser cavity 10 until the pressure reaches a predetermined value. Furthermore, if the charging voltage is lower than the minimum value within the allowable range, processor 14 controls laser gas exhaust device 18b to exhaust laser gas from laser cavity 10 until the pressure reaches a predetermined value.

[0089] Figure 4 An example of an ideal flow velocity distribution of the laser gas passing through the discharge space 27 is shown. Figure 4 In FIG. 1 , P1 represents the position of the discharge surface of the cathode electrode 20a in the Y direction, and P2 represents the position of the discharge surface of the anode electrode 20b in the Y direction. In addition, P3 represents the center position of the discharge space 27 in the Y direction. In addition, the solid line represents the flow velocity distribution of the laser gas, and the dotted line represents the average flow velocity calculated based on the flow velocity distribution of the laser gas. Figure 7 and Figure 12 Same here.

[0090] The main discharge generates discharge products in the discharge space 27. The discharge products are conductive, so when the discharge products are retained in the discharge space 27, arc discharge may occur due to the discharge products. However, the laser gas is rectified on the surface of the insulating guide 28 and the surface of the conductive guide 29, and ideally, it will be Figure 4 The flow velocity distribution shown passes through discharge space 27. The laser gas moves discharge products generated in discharge space 27 downstream and is removed, thereby suppressing the occurrence of arc discharge due to the discharge products.

[0091] 1.3 Topics

[0092] Figure 5 This is a timing diagram illustrating the operation of the gas laser device 2. When exposing a semiconductor wafer using the exposure apparatus 100, exposure is performed by outputting pulsed laser light PL from the gas laser device 2 at a predetermined repetition frequency, known as "burst output." However, exposure using the pulsed laser light PL may be paused during periods of time, such as when the semiconductor wafer is being moved, replaced, or when a mask is being replaced within the exposure apparatus 100. Specifically, during exposure using the gas laser device 2, a burst output period TB, during which burst output is performed, and a burst pause period TR, during which burst output is paused, are repeated.

[0093] When the above-mentioned arc discharge occurs during the burst output period TB, the laser gas is not sufficiently excited during the arc discharge, and thus a so-called "gap" occurs where the pulsed laser light PL is not output. In the gas laser device 2 of the comparative example, it is believed that the gap is suppressed when the discharge products in the discharge space 27 are removed by the flow of the laser gas as described above. However, Figure 5 As shown, the present applicant has confirmed that in the gas laser device 2 of the comparative example, a gap may still occur in the burst output period TB.

[0094] Therefore, the present applicant simulated the flow of laser gas to speculate on the cause of the vacancies. Figure 6 An example of simulation results of the flow of laser gas is shown. The flow of laser gas includes a "mainstream", which is a laminar flow that moves at high speed in the X direction along the surface of the insulating guide 28 and the conductive guide 29 without peeling off on the discharge surface of the cathode electrode 20a and the anode electrode 20b. Laminar flow refers to a state in which a fluid flows regularly in a certain direction. Figure 6 In the above, M1 to M5 represent multiple components contained in the mainstream. Figure 11 and Figure 16 Same here.

[0095] In addition to the mainstream flow, the laser gas flow also includes a "stagnant flow" generated downstream of cathode electrode 20a and anode electrode 20b. This stagnant flow is caused by turbulence generated by the laser gas peeling off the discharge surfaces of cathode electrode 20a and anode electrode 20b, and by laser gas separated from the mainstream flow by this turbulence. Furthermore, this stagnant flow is laser gas that travels at low speed in the X direction along the surfaces of insulating guide 28 and conductive guide 29 and remains between the mainstream flow and these surfaces. It is speculated that the distribution of this stagnant flow is the cause of the voids.

[0096] Stagnant flow, while including flow in a direction opposite to the mainstream, is retained, causing a portion of the mainstream flow after passing through discharge space 27 to shift to stagnant flow. Therefore, it is speculated that stagnant flow is a factor in the flow path resistance imposed on the mainstream flow, reducing its flow velocity. Hereinafter, stagnant flow generated in the cathode-side space between the surface of insulating guide 28 and the mainstream flow is referred to as "cathode-side stagnant flow." Furthermore, stagnant flow generated in the anode-side space between the surface of conductive guide 29 and the mainstream flow is referred to as "anode-side stagnant flow."

[0097] It is speculated that the laser gas after passing through discharge space 27 receives a force in the -Y direction due to the suction action of the rotation of fan 23 and flows toward second guide member 29b. Therefore, it is speculated that the cathode-side stagnant flow and the anode-side stagnant flow are asymmetric.

[0098] Specifically, the cathode-side stagnant flow generated on the discharge surface of cathode electrode 20a is continuously fed into the cathode-side space. The cathode-side stagnant flow expands while absorbing a portion of the mainstream flow. As a result, the mainstream component M1 is prevented from reattaching to the insulating guide 28. The cathode-side stagnant flow encounters significant flow resistance, slowing down as it advances. Furthermore, it is speculated that the deceleration of mainstream component M1 leads to a cascading deceleration of mainstream components M2 to M4. Reattachment refers to the phenomenon in which fluid flowing along a wall separates from the wall and then flows out again along the wall as a laminar flow.

[0099] The anode-side stagnant flow generated at anode electrode 20b is also continuously fed into the anode-side space. However, the laser gas flows while being subjected to a force in the -Y direction. Therefore, the generated anode-side stagnant flow immediately reattaches, suppressing its expansion. By suppressing the expansion of the anode-side stagnant flow, the mainstream component M5 reattaches to the conductive guide 29, reducing flow resistance. This increases the flow velocity of the mainstream component M5. Therefore, it is estimated that the mainstream component M5, after passing through discharge space 27, flows with a bias toward the conductive guide 29.

[0100] Figure 7 An example of the flow velocity distribution of laser gas passing through discharge space 27 when a void is generated is shown. When a void is generated, the flow velocity near position P1 on the discharge surface of cathode electrode 20a decreases, and the average flow velocity decreases accordingly. This is presumably due to a decrease in the removal rate of discharge products, which in turn causes arc discharge and the formation of voids.

[0101] To increase the removal rate of discharge products, one approach is to increase the speed of the laser gas by increasing the rotational speed of the fan 23. However, increasing the rotational speed of the fan 23 can lead to various problems, including increased power consumption, difficulty controlling the fan 23, increased vibration of the fan 23, resulting in uneven flow rate, and possible damage to the fan 23.

[0102] Furthermore, to suppress the expansion of cathode-side stagnant flow, it is conceivable to reduce the rotation speed of the fan 23. However, reducing the rotation speed of the fan 23 will reduce the removal rate of discharge products. In this case, high-repetition-frequency burst output operation cannot be performed.

[0103] Therefore, an object of the present disclosure is to provide a gas laser device and a method for manufacturing an electronic device that can perform burst output without gaps.

[0104] 2. First Implementation

[0105] 2.1 Structure

[0106] The gas laser device 2 according to the first embodiment of the present disclosure has the same structure as the gas laser device 2 according to the comparative example, except for the difference in the structure inside the laser cavity 10 .

[0107] Figure 8 The structure of the laser cavity 10 in the first embodiment near the main electrode 20 is shown in detail. The only difference between this embodiment and the comparative example is that no Figure 6 The third guide member 29c is shown. That is, in this embodiment, the conductive guide 29 includes the first guide member 29a and the second guide member 29b. Thus, in this embodiment, a branch path 40 is formed around the dielectric tube 32 for a branch flow away from the main flow of the laser gas.

[0108] The branch flow path 40 includes a first path 41, a second path 42, and a third path 43. The first path 41 includes the first guide member 29a, into which a portion of the main flow of laser gas flows as a branch flow. The second path 42 includes the dielectric tube 32 and the ground plate 21, through which the branch flow flowing out of the first path 41 flows. The third path 43 includes the dielectric tube 32 and the anode electrode 20b, and guides the branch flow flowing out of the second path 42 toward the upstream side of the discharge space 27. In this embodiment, the first path 41 includes the first guide member 29a and the dielectric tube 32.

[0109] Specifically, the first path 41 is the gap between the dielectric tube 32 and the first guide member 29a. The second path 42 is the gap between the dielectric tube 32 and the ground plate 21. The third path 43 is the gap between the dielectric tube 32 and the anode electrode 20b. Furthermore, the holding member 34 and a portion of the preionization outer electrode 31 are located within the third path 43.

[0110] First path 41 has an inlet 41a at its end for admitting a portion of the mainstream laser gas. Third path 43 has an outlet 43a at its end for allowing a branch flow to flow out toward the mainstream. The branch flow entering through inlet 41a flows through branch path 40 in the order of first path 41, second path 42, and third path 43, and then flows out through outlet 43a, where it rejoins the mainstream flow upstream of discharge space 27.

[0111] Figure 9 This is an enlarged view of the area near the dielectric tube 32. The surface of the first guide member 29a is a plane parallel to the Z direction and non-parallel to the X and Y directions. E1 is an imaginary surface extending the surface of the first guide member 29a toward the discharge space 27. E2 is an imaginary surface parallel to the imaginary surface E1 and in contact with the surface of the dielectric tube 32. F is the outer diameter of the dielectric tube 32.

[0112] In order to allow a part of the mainstream laser gas to flow into the shunt path 40, it is preferable that a part of the dielectric tube 32 protrudes from the imaginary plane E1 toward the mainstream side. The protrusion amount dtop of the dielectric tube 32 is defined by the distance between the imaginary plane E1 and the imaginary plane E2. It is preferable that the protrusion amount dtop and the outer diameter F satisfy the relationship of 0 < dtop ≤ 0.5F.

[0113] Figure 10 It is a plan view of a part including the anode electrode 20b and the dielectric tube 32 as viewed from the discharge space 27. The discharge surface of the anode electrode 20b is a rectangle extending in the Z direction. The first guide member 29a, the second guide member 29b, the dielectric tube 32, and the pre-ionization outer electrode 31 are arranged along the length direction of the discharge surface of the anode electrode 20b.

[0114] The dielectric tube 32 extends in the Z direction, and both ends are held by a pair of holding members 35. The pair of holding members 35 are arranged on the ground plate 21 and form both end faces of the shunt path 40 in the Z direction. The inlet 41a and the outlet 43a are each a rectangle extending in the Z direction.

[0115] The pre-ionization outer electrode 31 includes a contact portion 31a, a fixing portion 31b, and a plurality of connecting portions 31c. The contact portion 31a extends in the Z direction and contacts the dielectric tube 32. The fixing portion 31b extends in the Z direction and is held by the holding member 34. The plurality of connecting portions 31c each extend in the X direction and are connected between the contact portion 31a and the fixing portion 31b. The plurality of connecting portions 31c are arranged at equal intervals in the Z direction. The pre-ionization outer electrode 31 has an overall ladder shape, and spaces between two adjacent connecting portions 31c are respectively present at the outlet 43a for the shunt of the laser gas to pass through.

[0116] Preferably, when the minimum width in the direction perpendicular to the shunt flow direction of the inlet 41a is din and the minimum width in the direction perpendicular to the shunt flow direction of the outlet 43a is dout, the relationship of dout ≥ din is satisfied. Further, preferably, when the distance between the discharge surface of the cathode electrode 20a and the discharge surface of the anode electrode 20b is D, the relationship of 0.1D ≤ din ≤ 0.5D is satisfied. In the present embodiment, the minimum width din is the length of the inlet 41a in the X direction, and the minimum width dout is the length of the outlet 43a in the X direction.

[0117] 2.2 Operation

[0118] Except for the different functions played by forming the shunt path 40, the operation of the gas laser device 2 of the present embodiment is the same as that of the comparative example.

[0119] Figure 11 Shows an example of the simulation result of the flow of the laser gas in the first embodiment. As Figure 11 As shown, in this embodiment, a portion of the main flow component M5 separates and flows from the inlet 41a into the branch channel 40. The branch flow travels along the surface of the dielectric tube 32 within the branch channel 40 and reaches the outlet 43a. It is speculated that the principle by which the branch flow is generated and travels within the branch channel 40 is based on the Coanda effect.

[0120] Within the bypass channel 40, a stagnant flow with a flow component in the opposite direction of the bypass flow occurs on the side surfaces of the first guide member 29a, the surface of the ground plate 21, the side surfaces of the retaining member 34, and the side surfaces of the anode electrode 20b. Hereinafter, the stagnant flow generated within the bypass channel 40 is referred to as the "shunt flow stagnant flow."

[0121] The branch flow that reaches outlet 43a passes through the space around the ladder-shaped preionization outer electrode 31 and flows upstream toward insulating guide 28, that is, toward the +Y direction. The branch flow merges with the main stream component M5 upstream of discharge space 27. Thus, the branch flow possesses the kinetic energy necessary to overcome the stagnant branch flow and merge with the main stream component M5.

[0122] Compared with the mainstream component M5 after the split and confluence Figure 6 In the comparative example shown, the main stream enters the discharge space 27 with a state more biased toward the cathode electrode 20a. At this time, the main stream components M1 to M4 are also affected by the main stream component M5 and enter the discharge space 27 with a state biased toward the cathode electrode 20a. Therefore, the main stream as a whole enters the discharge space 27 with a state more biased toward the cathode electrode 20a than in the comparative example.

[0123] Summarizing the above, according to this embodiment, the following first to fourth effects are obtained.

[0124] As a first action, a branch flow with kinetic energy capable of shifting the position of the main flow is generated. The branch flow generated by the Coanda effect propagates within the branch flow path 40 along the surface of the dielectric tube 32, thereby flowing out of the branch flow path 40 with minimal loss of kinetic energy. This first action occurs at all locations in the Z direction of the branch flow path 40. As a result, a branch flow with minimal kinetic energy variation flows out of the outlet 43a in the Z direction.

[0125] As a second effect, a split flow traveling in the +Y direction flows out of the outflow port 43a. Because the dielectric tube 32 is located upstream of the discharge space 27, the split flow generated by the Coanda effect separates from the dielectric tube 32 and flows out of the outflow port 43a in the +Y direction. Furthermore, because the dielectric tube 32 extends in the Z direction, the split flow flows out of the outflow port 43a in the +Y direction from all locations in the Z direction.

[0126] As a third effect, the entire mainstream flow shifts toward the cathode electrode 20a. The branch flow advancing in the +Y direction merges with the main flow entering the discharge space 27 in the +X direction. Therefore, the entire mainstream flow enters the discharge space 27 while shifting toward the cathode electrode 20a.

[0127] As a fourth effect, the symmetry between the cathode-side stagnant flow and the anode-side stagnant flow is improved. The entire mainstream enters the discharge space 27 while displaced toward the cathode electrode 20a. This promotes the reattachment of the mainstream component M1 in the cathode-side space, suppressing the expansion of the cathode-side stagnant flow. Meanwhile, in the anode-side space, the reattachment of the mainstream component M5 is delayed, causing the anode-side stagnant flow to expand. This improves the symmetry between the cathode-side stagnant flow and the anode-side stagnant flow.

[0128] Figure 12 An example of the flow velocity distribution of the laser gas passing through the discharge space 27 in the first embodiment is shown. Figure 12 In addition to the flow velocity distribution and average flow velocity in this embodiment, the ideal flow velocity distribution and average flow velocity are also shown. Figure 12 In this embodiment, the flow velocity decreases near the discharge surface position P2 of the anode electrode 20b, but approaches the ideal value as it approaches the discharge surface position P1 of the cathode electrode 20a.

[0129] 2.3 Effect

[0130] According to this embodiment, the symmetry of the cathode-side stagnant flow and the anode-side stagnant flow is improved, and the flow velocity distribution of the laser gas passing through the discharge space 27 is close to the ideal flow velocity distribution, thereby improving the situation where the discharge product is insufficiently removed. As a result, arc discharge is suppressed, such as Figure 13 As shown, burst output without gaps is possible.

[0131] 3. Second embodiment

[0132] 3.1 Structure

[0133] The gas laser device 2 according to the second embodiment of the present disclosure has the same structure as the gas laser device 2 according to the first embodiment, except for the difference in the structure inside the laser cavity 10 .

[0134] Figure 14 The structure near the main electrode 20 within the laser cavity 10 of the second embodiment is shown in detail. This embodiment differs from the first embodiment only in the structure of the conductive guide 29. In this embodiment, the first guide member 29a of the conductive guide 29 is positioned close to the dielectric tube 32. Furthermore, a through hole 50 is formed in the first guide member 29a, extending from the upstream end toward the anode electrode 20b along the X direction.

[0135] In this embodiment, the first path 41 of the branch flow path 40 is formed by a through-hole 50. The inlet 41a for the branch flow is an opening on the upstream side of the through-hole 50. As in the first embodiment, the second path 42 is the gap between the dielectric tube 32 and the ground plate 21. As in the first embodiment, the third path 43 is the gap between the dielectric tube 32 and the anode electrode 20b. Furthermore, the retaining member 34 and a portion of the preionization outer electrode 31 are located within the third path 43.

[0136] Figure 15 This is a plan view of the portion including the anode electrode 20b and the dielectric tube 32 as viewed from the discharge space 27. The through hole 50 extends in the Z direction. Furthermore, in this embodiment, a pair of retaining members 35 extend from the dielectric tube 32 to the first guide member 29a. Thus, the pair of retaining members 35 form both end surfaces of the first path 41 in the Z direction.

[0137] In this embodiment, it is also preferable to satisfy the relationship of dout ≥ din and the relationship of 0.1D ≤ din ≤ 0.5D. In this embodiment, the branch flow flows into the inlet 41a in the X direction, so the minimum width din is the length in the Y direction.

[0138] 3.2 Action

[0139] The operation of the gas laser device 2 of this embodiment is the same as that of the first embodiment except for the difference due to the structure of the branch flow path 40 .

[0140] Figure 16 An example of simulation results of the flow of laser gas in the second embodiment is shown. Figure 16 As shown, even when the through hole 50 is used as the first path 41 , the same flow division as in the first embodiment occurs, and thus the same effect as in the first embodiment can be obtained.

[0141] 3.3 Effect

[0142] According to this embodiment, as in the first embodiment, the symmetry between the cathode-side stagnant flow and the anode-side stagnant flow is improved, and the flow velocity distribution of the laser gas passing through discharge space 27 approaches the ideal flow velocity distribution, thereby improving the situation where insufficient removal of discharge products is required. As a result, arc discharge is suppressed, and burst output without gaps is possible.

[0143] 4. Manufacturing methods of electronic devices

[0144] Figure 17An example configuration of an exposure apparatus 100 is schematically shown. Exposure apparatus 100 includes an illumination system 104 and a projection system 106. Illumination system 104 illuminates the reticle pattern of a mask (not shown) placed on reticle stage RT using pulsed laser light PL incident from, for example, a gas laser device 2. Projection system 106 projects the pulsed laser light PL, which has passed through the reticle, into a reduced-size image on a workpiece (not shown) placed on workpiece stage WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist.

[0145] Exposure apparatus 100 synchronously moves reticle stage RT and workpiece stage WT in parallel, exposing a workpiece to pulsed laser light PL reflecting the reticle pattern. After transferring the reticle pattern onto a semiconductor wafer through this exposure process, semiconductor devices can be manufactured through multiple steps. Semiconductor devices are an example of "electronic devices" in this disclosure.

[0146] Furthermore, 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.

[0147] The above description is not limiting but merely illustrative, and therefore, it will be apparent to those skilled in the art that modifications may be made to the various embodiments of the present disclosure without departing from the scope of the appended claims.

[0148] The terms used throughout this specification and claims should be interpreted as “non-limiting” terms. For example, terms such as “including” or “comprising” should be interpreted as “not limited to the recorded included parts.” Terms such as “having” should be interpreted as “not limited to the recorded possessed parts.” In addition, the modifier “one” described in this specification and claims should be interpreted as meaning “at least one” or “one or more.” In addition, terms such as “at least one of A, B, and C” should be interpreted as “A,” “B,” “C,” “A+B,” “A+C,” “B+C,” or “A+B+C,” and further, should be interpreted as including combinations of these and parts other than “A,” “B,” and “C.”

Claims

1. A gas laser device that excites laser gas passing through a discharge space between a first discharge electrode and a second discharge electrode, wherein: The gas laser device has: a plate that supports the first discharge electrode; a guiding member that is disposed on the plate and guides the laser gas to the discharge space; a dielectric tube that is disposed between the guiding member and the first discharge electrode in a manner separated from the plate and the first discharge electrode respectively; a first path that is configured to include the guiding member, and a part of the laser gas flows into the first path as a shunt; a second path that is configured to include the dielectric tube and the plate, and the shunt flowing out from the first path flows through it; and a third path that is configured to include the dielectric tube and the first discharge electrode, and guides the shunt flowing out from the second path to a position upstream of the laser gas relative to the discharge space.

2. The gas laser device according to claim 1, wherein the guiding member is disposed in a manner separated from the dielectric tube, the first path is configured to include the guiding member and the dielectric tube.

3. The gas laser device according to claim 2, wherein a part of the dielectric tube protrudes from a virtual plane obtained by extending the surface of the guiding member toward the discharge space.

4. The gas laser device according to claim 3, wherein when the protrusion amount of the dielectric tube is dtop and the outer diameter of the dielectric tube is F, the relationship 0 < dtop ≤ 0.5F is satisfied.

5. The gas laser device according to claim 1, wherein a through hole is formed in the guiding member, the first path is constituted by the through hole.

6. The gas laser device according to claim 1, wherein when the minimum width in the direction perpendicular to the flow direction of the shunt at the inlet of the first path is din and the minimum width in the direction perpendicular to the flow direction of the shunt at the outlet of the third path is dout, the relationship dout ≥ din is satisfied.

7. The gas laser device according to claim 6, wherein when the distance between the discharge surfaces of the first discharge electrode and the second discharge electrode is D, the relationship 0.1D ≤ din ≤ 0.5D is satisfied.

8. The gas laser device according to claim 1, wherein the first discharge electrode is an anode electrode and the second discharge electrode is a cathode electrode.

9. The gas laser device according to claim 8, wherein the gas laser device has a ladder-shaped pre-ionization outer electrode disposed between the first discharge electrode and the dielectric tube.

10. The gas laser device according to claim 9, wherein the gas laser device has a pre-ionization inner electrode disposed inside the dielectric tube.

11. The gas laser device according to claim 10, wherein the plate is a ground plate, the guiding member is conductive.

12. The gas laser device according to claim 11, wherein the gas laser device has a conductive guiding member that includes the guiding member as the first guiding member, The conductive guide includes a second guide member disposed on the plate so as to cover a side surface of the first discharge electrode on a downstream side of the first discharge electrode.

13. The gas laser device according to claim 12, wherein: The first discharge electrode protrudes from a surface of the conductive guide toward the second discharge electrode.

14. The gas laser device according to claim 13, wherein The gas laser device includes an insulating guide disposed so as to cover upstream and downstream side surfaces of the second discharge electrode.

15. The gas laser device according to claim 14, wherein The second discharge electrode protrudes from a surface of the insulating guide toward the first discharge electrode.

16. A method for manufacturing an electronic device, comprising the following steps: Laser is generated by a gas laser device, Outputting the laser to an exposure device, exposing the laser light on a photosensitive substrate in the exposure device to manufacture an electronic device, The gas laser device excites the laser gas passing through the discharge space between the first discharge electrode and the second discharge electrode. The gas laser device comprises: a plate supporting the first discharge electrode; a guide component, disposed on the plate and configured to guide the laser gas toward the discharge space; a dielectric tube disposed between the guide member and the first discharge electrode so as to be separated from the plate and the first discharge electrode; a first path including the guide member, wherein a portion of the laser gas flows into the first path as a branch flow; a second path, configured to include the dielectric tube and the plate, and through which the split flow flowing out of the first path flows; as well as The third path includes the dielectric tube and the first discharge electrode and guides the branch flow flowing out of the second path to an upstream side of the laser gas relative to the discharge space.

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