Laser chamber, discharging electrode, and manufacturing method for electronic device

Abstract

To improve the useful life of a laser chamber by suppressing the wear of a main electrode.SOLUTION: A laser chamber used for a gas laser device in which a laser gas including fluorine is excited by discharging includes a cathode electrode including a cathode discharging surface extending in a first direction, an anode electrode including an anode discharging surface extending in the first direction and disposed in a posture with the anode discharging surface facing the cathode discharging surface in a second direction that is orthogonal to the first direction, a fan that circulates the laser gas so that the laser gas passes a discharging space between the cathode electrode and the anode electrode in a third direction that is orthogonal to the first direction and the second direction, and a preliminary ionization electrode disposed on an upstream side of the laser gas relative to the cathode electrode and the anode electrode. In the initial state, a cross-sectional shape of the cathode discharging surface cut along a plane orthogonal to the first direction is asymmetric about an axis parallel to the second direction, and a cross-sectional shape of the anode discharging surface cut along the plane is symmetric about the axis.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a laser chamber, a discharge electrode, and a method for manufacturing an electronic device. [Background technology]

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

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

[0004] [Patent Document 1] Japanese Patent Application Publication No. 03-102884 [Patent Document 2] Chinese Patent No. 102768926 Specification Summary

[0005] A laser chamber according to one aspect of the present disclosure is a laser chamber used in a gas laser device that excites a laser gas containing fluorine by electric discharge, and includes: a cathode electrode having a cathode discharge surface extending in a first direction; an anode electrode having an anode discharge surface extending in the first direction and arranged so that the anode discharge surface faces the cathode discharge surface in a second direction perpendicular to the first direction; a fan that circulates the laser gas through a discharge space between the cathode electrode and the anode electrode in a third direction perpendicular to the first and second directions; and a preionization electrode that is arranged upstream of the laser gas from the cathode electrode and the anode electrode, and in an initial state, the cross-sectional shape of the cathode discharge surface cut by a plane perpendicular to the first direction is asymmetric with respect to an axis parallel to the second direction, and the cross-sectional shape of the anode discharge surface cut by the plane is symmetric with respect to the axis.

[0006] A discharge electrode according to one aspect of the present disclosure is a discharge electrode used in a gas laser device that excites a laser gas containing fluorine by discharge, and comprises: a cathode electrode having a cathode discharge surface extending in a first direction; and an anode electrode having an anode discharge surface extending in the first direction and arranged so that the anode discharge surface faces the cathode discharge surface in a second direction that is perpendicular to the first direction; and in an initial state, the cross-sectional shape of the cathode discharge surface cut by a plane perpendicular to the first direction is asymmetric with respect to an axis parallel to the second direction, and the cross-sectional shape of the anode discharge surface cut by the plane is symmetric with respect to the axis.

[0007] a fan for circulating the laser gas so that the laser gas passes through a discharge space between the cathode electrode and the anode electrode in a third direction orthogonal to the first and second directions; and a preionization electrode arranged upstream of the cathode electrode and the anode electrode in the direction of the laser gas, wherein, in an initial state, the cross-sectional shape of the cathode discharge surface taken along a plane orthogonal to the first direction is asymmetric with respect to an axis parallel to the second direction, and the cross-sectional shape of the anode discharge surface taken along the plane is symmetric with respect to the axis; [Brief explanation of the drawings]

[0008] Some embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a side view schematically showing the configuration of a gas laser device according to a comparative example. [Figure 2] FIG. 2 is a cross-sectional view schematically showing the configuration of a gas laser device according to a comparative example. [Figure 3] FIG. 3 is a cross-sectional view showing the shape of a main electrode according to a comparative example. [Figure 4] FIG. 4 is a graph showing the relationship between the amount of fluorine consumed during operation and the operating time of a gas laser device according to a comparative example. [Figure 5] FIG. 5 is a cross-sectional view showing the configuration of the main electrode according to the first embodiment. [Figure 6] FIG. 6 is a diagram illustrating the cross-sectional shape of the first discharge surface. [Figure 7] FIG. 7 is a diagram illustrating the cross-sectional shape of the second discharge surface. [Figure 8] FIG. 8 is a cross-sectional view showing the configuration of a main electrode according to the second embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing the configuration of a main electrode according to the third embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing the configuration of a main electrode according to a modified example of the third embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing the configuration of a main electrode according to the fourth embodiment. [Figure 12] FIG. 12 is a cross-sectional view showing the configuration of a main electrode according to a modification of the fourth embodiment. [Figure 13] FIG. 13 is a cross-sectional view showing a method for manufacturing a cathode electrode. [Figure 14] FIG. 14 is a cross-sectional view showing a method for manufacturing an anode electrode. [Figure 15] FIG. 15 is a diagram schematically showing an example of the configuration of an exposure apparatus. Embodiment

[0009] <Contents> 1. Comparative Example 1.1 Gas laser device 1.1.1 Configuration 1.1.2 Operation 1.2 Electrode shape 1.3 Challenges 2. First embodiment 2.1 Configuration 2.1.1 Cathode electrode shape 2.1.2 Anode electrode shape 2.2 Actions and Effects 3. Second embodiment 3.1 Configuration 3.1.1 Cathode electrode shape 3.1.2 Anode electrode shape 3.2 Actions and Effects 4. Third embodiment 4.1 Configuration 4.1.1 Cathode electrode shape 4.1.2 Anode electrode shape 4.2 Actions and Effects 5. Fourth embodiment 5.1 Configuration 5.1.1 Cathode electrode shape 5.1.2 Anode electrode shape 5.2 Actions and Effects 6.Main electrode manufacturing method 7. Manufacturing method of electronic devices

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Furthermore, not all of the configurations and operations described in the embodiments are necessarily essential as the configurations and operations of the present disclosure. Note that the same components are given the same reference symbols, and redundant explanations will be omitted.

[0011] 1. Comparative Example First, a comparative example of the present disclosure will be described. The comparative example of the present disclosure is a form that the applicant recognizes as being known only by the applicant, and is not a publicly known example that the applicant acknowledges.

[0012] 1.1 Gas laser device 1.1.1 Configuration The configuration of a gas laser device 2 according to a comparative example will be described using Figures 1 and 2. Figure 1 shows a schematic configuration of the gas laser device 2. Figure 2 is a cross-sectional view of the gas laser device 2 shown in Figure 1 as viewed from the Z direction. The gas laser device 2 is a discharge excitation type gas laser device that excites laser gas by electric discharge, such as an excimer laser device.

[0013] In FIG. 1, the traveling direction of pulsed laser light PL output from gas laser device 2 is defined as the Z direction. The discharge direction, which is perpendicular to the Z direction and will be described later, is defined as the Y direction. The direction perpendicular to the Z direction and the Y direction is defined as the X direction. The pulsed laser light PL is an example of a "laser light" according to the technology of the present disclosure. The Z direction corresponds to the "first direction" according to the technology of the present disclosure. The Y direction corresponds to the "second direction" according to the technology of the present disclosure. The X direction corresponds to the "third direction" according to the technology of the present disclosure.

[0014] 1, the gas laser device 2 includes a laser chamber 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 line narrowing module 15 and an output coupling mirror 16.

[0015] The laser chamber 10 is a metal container made of, for example, aluminum metal with a nickel-plated surface. As shown in Figures 1 and 2, the interior of the laser chamber 10 is provided with a main electrode 20, a ground plate 21, wiring 22, a fan 23, a heat exchanger 24, a preionization electrode 19, an electrical insulating guide 28, and a metal damper 29. The main electrode 20 is an example of a "discharge electrode" according to the technology of the present disclosure.

[0016] A laser gas containing fluorine (F2) is sealed as a laser medium inside the laser chamber 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.

[0017] An opening is formed in the laser chamber 10. An electrical insulating plate 26 with a feedthrough 25 embedded therein is attached to the laser chamber 10 via an O-ring (not shown) so as to close the opening. The PPM 12 is placed on the electrical insulating plate 26. The laser chamber 10 is grounded.

[0018] The PPM 12 includes a charging capacitor, which will be described later, and is connected to the main electrode 20 via a feedthrough 25. The PPM 12 includes a switch SW for discharging the main electrode 20. The charger 11 is connected to the charging capacitor of the PPM 12. Hereinafter, the discharge occurring at the main electrode 20 will be referred to as the main discharge.

[0019] The main electrode 20 consists of a cathode electrode 20a and an anode electrode 20b that extend in the Z direction. The cathode electrode 20a and the anode electrode 20b are arranged in the laser chamber 10 with their discharge surfaces facing each other in the Y direction. The space between the cathode electrode 20a and the anode electrode 20b is called 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 a feedthrough 25. The surface of the anode electrode 20b opposite to the discharge surface is supported by a ground plate 21.

[0020] The cathode electrode 20a and the anode electrode 20b are each formed of a material containing copper (Cu). For example, the cathode electrode 20a and the anode electrode 20b are formed of copper or brass, which is an alloy of copper and zinc (Zn).

[0021] The ground plate 21 is connected to the laser chamber 10 via wiring 22. The laser chamber 10 is connected to the ground. Therefore, the ground plate 21 is connected to the ground via wiring 22. An end of the ground plate 21 in the Z direction is fixed to the laser chamber 10.

[0022] Fan 23 is a cross-flow fan for circulating laser gas within laser chamber 10, and is disposed on the opposite side of ground plate 21 from discharge space 27. A motor 23a that rotates fan 23 is connected to laser chamber 10.

[0023] The laser gas blown out 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 from discharge space 27 can be sucked into fan 23 via heat exchanger 24. Heat exchanger 24 exchanges heat between the laser gas and a refrigerant supplied inside heat exchanger 24.

[0024] The preionization electrode 19 includes an outer preionization electrode 19a, a dielectric pipe 19b, and an inner preionization electrode 19c, and is disposed upstream of the main electrode 20 in the direction of the laser gas.

[0025] Electrical insulating guide 28 is disposed on the surface of electrical insulating plate 26 facing discharge space 27, sandwiching cathode electrode 20a therebetween. Electrical insulating guide 28 is formed in a shape that guides the flow of laser gas so that the laser gas from fan 23 flows efficiently between cathode electrode 20a and anode electrode 20b. Electrical insulating guide 28 and electrical insulating plate 26 are formed of ceramic such as alumina (Al2O3), which has low reactivity with fluorine.

[0026] The metal damper 29 is disposed on the surface of the ground plate 21 facing the discharge space 27, so as to sandwich the anode electrode 20b therebetween. The metal damper 29 is made of, for example, porous nickel metal that has low reactivity with fluorine.

[0027] Laser gas supply device 18a and laser gas exhaust device 18b are connected to laser chamber 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.

[0028] Windows 10a and 10b are provided at the ends of the laser chamber 10 to emit light generated within the laser chamber 10 to the outside. The laser chamber 10 is arranged so that the optical path of the optical resonator passes through the discharge space 27 and the windows 10a and 10b.

[0029] The line narrowing module 15 includes a prism 15a and a grating 15b. The prism 15a expands the beam width of the light emitted from the laser chamber 10 through the window 10a and transmits the expanded beam toward the grating 15b.

[0030] Grating 15b is arranged in a Littrow configuration, where the angle of incidence and the angle of diffraction are the same. Grating 15b is a wavelength selection element that selectively extracts light near a specific wavelength depending on the diffraction angle. The spectral width of the light returning from grating 15b to laser chamber 10 via prism 15a is narrowed.

[0031] The output coupling mirror 16 transmits a portion of the light emitted from the laser chamber 10 via the window 10b and reflects the other portion back into the laser chamber 10. The surface of the output coupling mirror 16 is coated with a partially reflective film.

[0032] The light emitted from the laser chamber 10 travels back and forth between the line 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.

[0033] The pulse energy measuring unit 13 is disposed in the optical path of the pulsed laser light PL output via the output coupling mirror 16. The pulse energy measuring unit 13 includes a beam splitter 13a, a focusing optical system 13b, and an optical sensor 13c.

[0034] The beam splitter 13a transmits the pulsed laser light PL with high transmittance and reflects a portion of the pulsed laser light PL toward the focusing optical system 13b. The focusing optical system 13b focuses the light reflected by the beam splitter 13a on the light-receiving surface of the optical sensor 13c. The optical sensor 13c measures the pulse energy of the light focused on the light-receiving surface and outputs the measurement value to the processor 14.

[0035] The pressure sensor 17 detects the gas pressure inside the laser chamber 10 and outputs the detected value to the processor 14. The processor 14 determines the gas pressure of the laser gas inside the laser chamber 10 based on the detected gas pressure value and the charging voltage Vhv of the charger 11.

[0036] The charger 11 is a high-voltage power supply that supplies a charging voltage Vhv to a 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 electrical energy stored in the charging capacitor and applies it to the main electrode 20.

[0037] The processor 14 is a processing device that transmits and receives various signals to and from an exposure apparatus controller 110 provided in the exposure apparatus 100. For example, the processor 14 receives from the exposure apparatus controller 110 the target pulse energy Et of the pulsed laser light PL output to the exposure apparatus 100, an oscillation trigger signal, and the like.

[0038] The processor 14 comprehensively controls the operation of each component of the gas laser device 2 based on various signals sent from the exposure apparatus controller 110, measured values ​​of pulse energy, detected values ​​of gas pressure, and the like.

[0039] 1.1.2 Operation Next, the operation of gas laser apparatus 2 according to the comparative example will be described. First, processor 14 controls laser gas supply device 18a to supply laser gas into laser chamber 10, and drives motor 23a to rotate fan 23. This causes the laser gas to circulate within laser chamber 10.

[0040] The processor 14 receives the target pulse energy Et and the oscillation trigger signal transmitted from the exposure apparatus controller 110. The oscillation trigger signal is a signal that instructs the gas laser apparatus 2 to output one pulse of pulsed laser light PL.

[0041] The processor 14 sets a charging voltage Vhv corresponding to the target pulse energy Et in the charger 11. The processor 14 operates the switch SW of the PPM 12 in synchronization with the oscillation trigger signal.

[0042] When the switch SW of the PPM 12 is turned from off to on, a voltage is applied between the preionization inner electrode 19c and the preionization outer electrode 19a of the preionization electrode 19, and between the cathode electrode 20a and the anode electrode 20b. This causes a corona discharge at the preionization electrode 19, generating UV (Ultraviolet) light. The laser gas in the discharge space 27 is irradiated with the UV light, thereby preionizing the laser gas.

[0043] Thereafter, when the voltage between the cathode electrode 20a and the anode electrode 20b reaches the breakdown voltage, a main discharge occurs in the discharge space 27. If the discharge direction of the main discharge is the direction in which electrons flow, then the discharge direction is from the cathode electrode 20a to the anode electrode 20b. When the main discharge occurs, the laser gas in the discharge space 27 is excited and emits light.

[0044] Metal damper 29 prevents acoustic waves generated by the main discharge from being reflected and returning to discharge space 27. In addition, as laser gas circulates within laser chamber 10, discharge products generated in discharge space 27 move downstream.

[0045] Light emitted from the laser gas is reflected by the line narrowing module 15 and the output coupling mirror 16 and travels back and forth within the laser resonator, resulting in laser oscillation. The light narrowed in line by the line narrowing module 15 is output from the output coupling mirror 16 as pulsed laser light PL.

[0046] The pulsed laser light 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 E of a portion of the incident pulsed laser light PL and outputs the measurement value to the processor 14.

[0047] The processor 14 calculates the difference ΔE between the measured value of the pulse energy E and the target pulse energy Et. Based on the difference ΔE, the processor 14 feedback-controls the charging voltage Vhv so that the measured value of the pulse energy E becomes the target pulse energy Et.

[0048] When charging voltage Vhv becomes higher than the maximum value of the allowable range, processor 14 controls laser gas supply device 18a to supply laser gas into laser chamber 10 until a predetermined pressure is reached. When charging voltage Vhv becomes lower than the minimum value of the allowable range, processor 14 controls laser gas exhaust device 18b to exhaust laser gas from laser chamber 10 until a predetermined pressure is reached.

[0049] The gas laser device 2 is not necessarily limited to a line-narrowing laser device, but may be a laser device that outputs spontaneously oscillated light. For example, instead of the line-narrowing module 15, a high-reflection mirror may be provided.

[0050] 1 and 2, an excimer laser device is shown as an example of the gas laser device 2, but the gas laser device 2 may be an F2 laser device or the like that uses laser gas containing fluorine gas and buffer gas.

[0051] 1.2 Electrode shape FIG. 3 shows the shape of the main electrode 20 according to a comparative example. FIG. 3 shows a cross section of the cathode electrode 20a and the anode electrode 20b cut along an XY plane perpendicular to the Z direction. The discharge surface 30a of the cathode electrode 20a and the discharge surface 30b of the anode electrode 20b each have a cross-sectional shape that is symmetrical with respect to an axis A parallel to the Y direction. Hereinafter, the discharge surface 30a of the cathode electrode 20a will be referred to as the "cathode discharge surface 30a," and the discharge surface 30b of the anode electrode 20b will be referred to as the "anode discharge surface 30b." Furthermore, in the present disclosure, the "cross-sectional shape" refers to the shape of a cross section cut along the XY plane. The XY plane corresponds to the "plane perpendicular to the first direction" according to the technology of the present disclosure.

[0052] In the comparative example, the cross-sectional shape of cathode discharge surface 30a and anode discharge surface 30b is a smoothly curved shape, for example, a semi-elliptical shape.

[0053] 1.3 Challenges One of the factors that determines the service life of the laser chamber 10 is the wear of the main electrode 20. The wear of the main electrode 20 is related to the consumption of fluorine contained in the laser gas in the laser chamber 10 when the gas laser device 2 is in operation, and the greater the fluorine consumption, the greater the wear of the main electrode 20. The wear of the main electrode 20 is thought to occur when fluorine combines with copper and other components contained in the main electrode 20 and is consumed.

[0054] Fig. 4 shows the relationship between fluorine consumption and operating time during operation of the gas laser device 2 according to the comparative example. Fig. 4 shows the change in fluorine consumption over time until the pulse rate of the pulsed laser light PL reaches approximately 10 Bpls. Fig. 4 shows that the fluorine consumption is high in the initial period T immediately after the gas laser device 2 starts operating, and gradually decreases after the initial period T.

[0055] Therefore, in order to improve the service life of the laser chamber 10, it is effective to suppress the wear of the main electrode 20 immediately after the start of operation, and to do this, it is necessary to suppress the amount of fluorine consumption immediately after the start of operation.

[0056] The technique of the present disclosure aims to improve the service life of the laser chamber 10 by suppressing wear of the main electrode 20.

[0057] 2. First embodiment 2.1 Configuration The gas laser device 2 according to the first embodiment of the present disclosure has the same configuration as the gas laser device 2 according to the comparative example, except that the shape of the main electrode 20 is different.

[0058] FIG. 5 shows the configuration of main electrode 20 according to the first embodiment. FIG. 5 shows a cross section of cathode electrode 20a and anode electrode 20b cut along the XY plane. In this embodiment, the cross-sectional shape of anode discharge surface 30b is symmetrical with respect to axis A parallel to the Y direction, as in the comparative example. On the other hand, the cross-sectional shape of cathode discharge surface 30a is asymmetrical with respect to axis A. The shape of main electrode 20 according to this embodiment is a shape that imitates the shape of an electrode at the end of its life after the initial period T shown in FIG. 4 has elapsed.

[0059] 2.1.1 Cathode electrode shape In this embodiment, cathode discharge surface 30a is composed of first discharge surface 31 and second discharge surface 32, which have different cross-sectional shapes. First discharge surface 31 is located upstream of axis A in the direction of the laser gas. Second discharge surface 32 is located downstream of axis A in the direction of the laser gas. First discharge surface 31 and second discharge surface 32 are connected at point P on axis A.

[0060] In this embodiment, the cross-sectional shape of first discharge surface 31 and the cross-sectional shape of second discharge surface 32 are each part of an ellipse, but have different ellipticities. The ellipticity is the ratio of the major axis to the minor axis of an ellipse, and is the value obtained by dividing the minor axis by the major axis.

[0061] Specifically, the cross-sectional shape of first discharge surface 31 is a part of an ellipse that is centered at point C1 on axis A and flattened in the Y direction. The cross-sectional shape of second discharge surface 32 is a part of an ellipse that is centered at point C2 on axis A and flattened in the Y direction. In both cases, the minor axis is parallel to the Y direction and the major axis is parallel to the X direction. The cross-sectional shape of first discharge surface 31 and the cross-sectional shape of second discharge surface 32 are each one of the shapes obtained by dividing an ellipse into four along the minor axis and the major axis.

[0062] First discharge surface 31 is connected to upstream side surface 33a of cathode electrode 20a at point S1. Point S1 is located on the major axis passing through point C1. Hereinafter, point S1 will also be referred to as the "upstream corner S1." As shown in FIG. 6, if the length of the major axis of the ellipse that forms the cross-sectional shape of first discharge surface 31 is DX1 and the length of the minor axis is DY1, then the ellipticity DY1 / DX1 is in the range of 1 / 5 to 1 / 3.

[0063] Second discharge surface 32 is connected to downstream side surface 33b of cathode electrode 20a at point S2. Point S2 is located on the major axis passing through point C2. Hereinafter, point S2 will also be referred to as the "downstream corner S2." As shown in FIG. 7, when the length of the major axis of the ellipse constituting the cross-sectional shape of second discharge surface 32 is DX2 and the length of the minor axis is DY2, the ellipticity DY2 / DX2 is in the range of 1 / 10 to 1 / 8.

[0064] The side surfaces 33a and 33b are parallel to the YZ plane and face each other in the X direction, and satisfy the relationships DX1=DX2 and DY1>DY2.

[0065] Therefore, the upstream corner S1 of the cathode discharge surface 30a is located farther from the discharge space 27 in the Y direction than the downstream corner S2. The curvature of the first discharge surface 31 is greater than that of the second discharge surface 32. In this disclosure, the discharge space 27 is defined as the space formed between the XZ plane passing through the top of the cathode electrode 20a and the XZ plane passing through the top of the anode electrode 20b. The top of the cathode electrode 20a refers to the portion of the cathode discharge surface 30a that protrudes most toward the anode electrode 20b. The top of the anode electrode 20b refers to the portion of the anode discharge surface 30b that protrudes most toward the cathode electrode 20a. In other words, the upstream corner S1 of the cathode discharge surface 30a is located farther from the top of the cathode electrode 20a in the Y direction than the downstream corner S2.

[0066] It should be noted that no coating film is formed on the first discharge surface 31 and the second discharge surface 32.

[0067] 2.1.2 Anode electrode shape Similar to the comparative example, the cross-sectional shape of anode discharge surface 30b is symmetrical with respect to axis A and is a part of an ellipse flattened in the Y direction. Specifically, the cross-sectional shape of anode discharge surface 30b is a semi-ellipse, with an ellipticity in the range of 1 / 6 to 1 / 4. Furthermore, anode electrode 20b is formed so that its width in the X direction is equal to that of cathode electrode 20a.

[0068] A coating film 34 is formed on the anode discharge surface 30b. For example, the material of the coating film 34 is a mixture of copper and ceramic.

[0069] The cross-sectional shape of the main electrode 20 according to this embodiment described above is the shape in its initial state. The initial state refers to the state of the main electrode 20 before it is attached to the laser chamber 10 during the manufacture of the gas laser device 2, or the state of the main electrode 20 after it is attached to the laser chamber 10 and before any discharge has occurred.

[0070] 2.2 Actions and Effects The applicant observed the shape of the main electrode 20 at the end of its life after starting operation of the gas laser device 2 according to the comparative example. The applicant found that the anode electrode 20b wears symmetrically on the upstream and downstream sides with respect to the axis A, whereas the cathode electrode 20a wears asymmetrically on the upstream and downstream sides with respect to the axis A. The cathode electrode 20a at the end of its life is more worn upstream than downstream. This is thought to be because the preionization electrode 19 is located upstream of the main electrode 20, and the amount of electrons generated by preionization is greater upstream than downstream.

[0071] In view of the above phenomenon observed in gas laser device 2 according to the comparative example, in this embodiment, the applicant has designed main electrode 20 in an initial state to have a shape that mimics the shape of an electrode at the end of its life. That is, the cross-sectional shape of cathode discharge surface 30a is asymmetric with respect to axis A, and the cross-sectional shape of anode discharge surface 30b is symmetric with respect to axis A.

[0072] If anode discharge surface 30b is made asymmetric with respect to axis A, it will gradually transition to a symmetric shape as the operating time passes, so in this embodiment, only cathode discharge surface 30a is made asymmetric.

[0073] 4, in the comparative example, after the initial period T has elapsed, the amount of fluorine consumed is low and wear of the main electrode 20 is suppressed, so that the main electrode 20 of this embodiment, which mimics the shape of an electrode at the end of its life, is suppressed from wear immediately after the start of operation of the gas laser device 2. This improves the service life of the laser chamber 10.

[0074] Furthermore, if the main electrode 20 is worn away and its shape changes significantly, the variation in the pulse energy of the pulsed laser light PL will increase. However, in this embodiment, the wear of the main electrode 20 is suppressed, thereby suppressing the change in shape, and therefore the variation in the pulse energy is suppressed.

[0075] Furthermore, even if a coating film is formed on cathode discharge surface 30a, the coating film will disappear at the end of its life, so in this embodiment, coating film 34 is not formed on cathode discharge surface 30a. On the other hand, coating film 34 is formed on anode discharge surface 30b because the anode discharge surface 30b becomes brittle due to fluorination caused by the fluorine contained in the laser gas. Coating film 34 can suppress deformation of anode discharge surface 30b.

[0076] 3. Second embodiment 3.1 Configuration The gas laser device 2 according to the second embodiment of the present disclosure has the same configuration as the gas laser device 2 according to the first embodiment, except that the shape of the main electrode 20 is different.

[0077] Fig. 8 shows the configuration of the main electrode 20 according to the second embodiment. Fig. 8 shows a cross section of the cathode electrode 20a and the anode electrode 20b cut along the XY plane. The shape of the main electrode 20 in this embodiment is similar to that of an electrode at the end of its life, as in the first embodiment.

[0078] 3.1.1 Cathode electrode shape As in the first embodiment, the cathode discharge surface 30a is composed of a first discharge surface 31 and a second discharge surface 32. The first discharge surface 31 and the second discharge surface 32 are connected at point P on the axis A and are asymmetric with respect to the axis A.

[0079] In this embodiment, the cross-sectional shape of first discharge surface 31 and the cross-sectional shape of second discharge surface 32 are parts of the same ellipse that is centered at point C located downstream of axis A and flattened in the Y direction. Specifically, the cross-sectional shape of cathode discharge surface 30a in this embodiment is a semi-ellipse obtained by cutting an ellipse centered at point C along its major axis, with a downstream portion of the resulting semi-ellipse cut away. The ellipticity of this ellipse is in the range of 1 / 5 to 1 / 3.

[0080] As in the first embodiment, the upstream corner S1 is located on the major axis passing through point C. In this embodiment, the downstream corner S2 is located at an end formed by cutting a portion of the downstream side of the semi-elliptical shape. Therefore, also in this embodiment, the upstream corner S1 of the cathode discharge surface 30a is located farther from the discharge space 27 than the downstream corner S2. Furthermore, the curvature of the first discharge surface 31 is greater than that of the second discharge surface 32.

[0081] 3.1.2 Anode electrode shape The anode electrode 20b has the same configuration as that of the first embodiment. The anode electrode 20b is formed so that its width in the X direction is equal to that of the cathode electrode 20a.

[0082] 3.2 Actions and Effects The gas laser device 2 according to the second embodiment has the same functions and effects as the gas laser device 2 according to the first embodiment.

[0083] 4. Third embodiment 4.1 Configuration The gas laser device 2 according to the third embodiment of the present disclosure has the same configuration as the gas laser device 2 according to the first embodiment, except that the shape of the main electrode 20 is different.

[0084] Fig. 9 shows the configuration of a main electrode 20 according to a third embodiment. Fig. 9 shows a cross section of a cathode electrode 20a and an anode electrode 20b cut along the XY plane. The shape of the main electrode 20 in this embodiment is similar to that of an electrode at the end of its life, as in the first embodiment.

[0085] 4.1.1 Cathode electrode shape As in the first embodiment, the cathode discharge surface 30a is composed of a first discharge surface 31 and a second discharge surface 32. The first discharge surface 31 and the second discharge surface 32 are connected at point P on the axis A and are asymmetric with respect to the axis A.

[0086] The cross-sectional shape of cathode discharge surface 30a in this embodiment differs from that of cathode discharge surface 30a in the first embodiment only in the cross-sectional shape of second discharge surface 32. As in the first embodiment, the cross-sectional shape of first discharge surface 31 in this embodiment is part of an ellipse flattened in the Y direction with an ellipticity in the range of 1 / 5 to 1 / 3. The cross-sectional shape of second discharge surface 32 in this embodiment is a straight line parallel to the X direction. In other words, second discharge surface 32 is flat.

[0087] In this embodiment as well, the upstream corner S1 of the cathode discharge surface 30a is located farther in the Y direction from the discharge space 27 than the downstream corner S2. The curvature of the first discharge surface 31 is greater than the curvature of the second discharge surface 32.

[0088] 10, the cross-sectional shape of second discharge surface 32 may be linear and inclined at a predetermined angle with respect to the X direction. The inclination angle of second discharge surface 32 with respect to the X direction is preferably determined so that upstream corner S1 is located farther from discharge space 27 than downstream corner S2. In addition, the connection between first discharge surface 31 and second discharge surface 32 is preferably rounded.

[0089] 4.1.2 Anode electrode shape The anode electrode 20b has the same configuration as that of the first embodiment. The anode electrode 20b is formed so that its width in the X direction is equal to that of the cathode electrode 20a.

[0090] 4.2 Actions and Effects The gas laser device 2 according to the third embodiment has the same functions and effects as the gas laser device 2 according to the first embodiment.

[0091] 5. Fourth embodiment 5.1 Configuration The gas laser device 2 according to the fourth embodiment of the present disclosure has the same configuration as the gas laser device 2 according to the first embodiment, except that the shape of the main electrode 20 is different.

[0092] Fig. 11 shows the configuration of a main electrode 20 according to a fourth embodiment. Fig. 11 shows a cross section of a cathode electrode 20a and an anode electrode 20b cut along the XY plane. The shape of the main electrode 20 in this embodiment is similar to that of an electrode at the end of its life, as in the first embodiment.

[0093] 5.1.1 Cathode electrode shape As in the first embodiment, the cathode discharge surface 30a is composed of a first discharge surface 31 and a second discharge surface 32. The first discharge surface 31 and the second discharge surface 32 are connected at point P on the axis A and are asymmetric with respect to the axis A.

[0094] The cross-sectional shape of cathode discharge surface 30a in this embodiment differs from that of cathode discharge surface 30a in the third embodiment only in the cross-sectional shape of first discharge surface 31. The cross-sectional shape of first discharge surface 31 in this embodiment is a straight line inclined at a predetermined angle with respect to the X direction. The cross-sectional shape of second discharge surface 32 in this embodiment is a straight line parallel to the X direction, as in the third embodiment. In other words, first discharge surface 31 and second discharge surface 32 are both flat surfaces.

[0095] The inclination angle of first discharge surface 31 with respect to the X direction is preferably determined so that upstream corner S1 is located farther from discharge space 27 than downstream corner S2. In addition, the connection between first discharge surface 31 and second discharge surface 32 is preferably rounded.

[0096] 12, the cross-sectional shape of second discharge surface 32 may be a straight line inclined at a predetermined angle with respect to the X direction. In this case, too, the inclination angle of second discharge surface 32 with respect to the X direction is preferably determined so that upstream corner S1 is located farther from discharge space 27 than downstream corner S2.

[0097] 5.1.2 Anode electrode shape The anode electrode 20b has the same configuration as that of the first embodiment. The anode electrode 20b is formed so that its width in the X direction is equal to that of the cathode electrode 20a.

[0098] 5.2 Actions and Effects The gas laser device 2 according to the fourth embodiment has the same functions and effects as the gas laser device 2 according to the first embodiment.

[0099] 6.Main electrode manufacturing method Next, a method for manufacturing the main electrode 20 according to the first embodiment will be described. First, as shown in Fig. 13, a rectangular base material 41 made of a material containing copper is prepared, and the cathode electrode 20a is formed by cutting one surface of the base material 41 asymmetrically with respect to the axis A. The cathode electrode 20a is formed with a cathode discharge surface 30a having the shape described in the first embodiment.

[0100] 14, a rectangular parallelepiped substrate 42 made of a copper-containing material is prepared, and anode electrode 20b is formed by cutting one surface of substrate 42 symmetrically with respect to axis A. Anode electrode 20b is formed with anode discharge surface 30b having the shape described as the first embodiment. Thereafter, coating film 34 is formed on anode discharge surface 30b.

[0101] Then, the cathode electrode 20a and the anode electrode 20b are attached inside the laser chamber 10. The main electrode 20 thus manufactured has the shape described in the first embodiment in the initial state immediately after manufacture.

[0102] The same applies to the manufacturing methods of the main electrode 20 according to the second to fourth embodiments, and the manufactured main electrode 20 has the shape explained in the second to fourth embodiments in the initial state immediately after manufacturing.

[0103] 7. Manufacturing method of electronic devices 15 shows a schematic configuration example of exposure apparatus 100. Exposure apparatus 100 includes an illumination optical system 104 and a projection optical system 106. Illumination optical system 104 illuminates a reticle pattern of a reticle (not shown) placed on a reticle stage RT with pulsed laser light PL incident thereon, for example, from a gas laser device 2. Projection optical system 106 reduces and projects the pulsed laser light PL that has passed through the reticle, forming an image on a workpiece (not shown) placed on a workpiece table WT. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist.

[0104] Exposure apparatus 100 exposes a workpiece to pulsed laser light PL reflecting a reticle pattern by synchronously translating a reticle stage RT and a workpiece table WT. After transferring the reticle pattern to a semiconductor wafer through the exposure process described above, a semiconductor device can be manufactured through multiple processes. A semiconductor device is an example of an "electronic device" in this disclosure.

[0105] The gas laser device 2 is not limited to use in the manufacture of electronic devices, but can also be used for laser processing such as drilling.

[0106] The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to those skilled in the art that modifications may be made to the embodiments of the present disclosure without departing from the scope of the appended claims.

[0107] Terms used throughout this specification and the appended claims should be interpreted as "open ended" terms. For example, the terms "include" or "including" should be interpreted as "not limited to what is stated as including." The term "having" should be interpreted as "not limited to what is stated as having." Additionally, the modifier "a" used in this specification and the appended claims should be interpreted as "at least one" or "one or more." Additionally, the term "at least one of A, B, and C" should be interpreted as "A," "B," "C," "A+B," "A+C," "B+C," or "A+B+C," and should also be interpreted as including combinations other than "A," "B," and "C."

Claims

1. A laser chamber used in a gas laser device that excites a laser gas containing fluorine by discharge, a cathode electrode having a cathode discharge surface extending in a first direction; an anode electrode having an anode discharge surface extending in the first direction and disposed in a position where the anode discharge surface faces the cathode discharge surface in a second direction perpendicular to the first direction; a fan that circulates the laser gas through a discharge space between the cathode electrode and the anode electrode in a third direction perpendicular to the first direction and the second direction; a preionization electrode disposed upstream of the cathode electrode and the anode electrode in the direction of the laser gas; Equipped with In an initial state, a cross-sectional shape of the cathode discharge surface cut along a plane orthogonal to the first direction is asymmetric with respect to an axis parallel to the second direction, and a cross-sectional shape of the anode discharge surface cut along the plane is symmetric with respect to the axis. Laser chamber.

2. 10. The laser chamber of claim 1, The corner of the cathode discharge surface on the upstream side of the laser gas is located farther from the discharge space in the second direction than the corner of the cathode discharge surface on the downstream side of the laser gas.

3. 3. The laser chamber of claim 2, When the upstream side of the laser gas from the axis of the cathode discharge surface is defined as a first discharge surface, and the downstream side of the laser gas from the axis of the cathode discharge surface is defined as a second discharge surface, the curvature of the first discharge surface is greater than the curvature of the second discharge surface.

4. 4. The laser chamber of claim 3, a cross-sectional shape of the first discharge surface is a part of an ellipse having an ellipticity in a range of 1 / 5 to 1 / 3 and flattened in the second direction, The cross-sectional shape of the second discharge surface is a part of an ellipse that has an ellipticity in the range of 1 / 10 to 1 / 8 and is flattened in the second direction.

5. 4. The laser chamber of claim 3, The cross-sectional shape of the cathode discharge surface is a part of an ellipse that is flattened in the second direction and has an ellipticity in the range of 1 / 5 to 1 / 3, with the center being located at a point downstream of the laser gas from the axis.

6. 4. The laser chamber of claim 3, a cross-sectional shape of the first discharge surface is a part of an ellipse having an ellipticity in a range of 1 / 5 to 1 / 3 and flattened in the second direction, The cross-sectional shape of the second discharge surface is a straight line parallel to the third direction or inclined with respect to the third direction.

7. 3. The laser chamber of claim 2, When the upstream side of the laser gas from the axis of the cathode discharge surface is defined as a first discharge surface, and the downstream side of the laser gas from the axis of the cathode discharge surface is defined as a second discharge surface, a cross-sectional shape of the first discharge surface is a straight line inclined with respect to the third direction, The cross-sectional shape of the second discharge surface is a straight line parallel to the third direction or inclined with respect to the third direction.

8. 10. The laser chamber of claim 1, The anode discharge surface has an ellipticity in the range of 1 / 6 to 1 / 4 and is part of an ellipse that is flattened in the second direction.

9. 10. The laser chamber of claim 1, The cathode electrode and the anode electrode are made of a material containing copper.

10. 10. The laser chamber of claim 1, A coating film is formed on the anode discharge surface.

11. 11. The laser chamber of claim 10, The material of the coating film is a mixture of copper and ceramic.

12. A discharge electrode used in a gas laser device that excites a laser gas containing fluorine by discharge, a cathode electrode having a cathode discharge surface extending in a first direction; an anode electrode having an anode discharge surface extending in the first direction and disposed in a position where the anode discharge surface faces the cathode discharge surface in a second direction perpendicular to the first direction; Equipped with In an initial state, a cross-sectional shape of the cathode discharge surface cut along a plane orthogonal to the first direction is asymmetric with respect to an axis parallel to the second direction, and a cross-sectional shape of the anode discharge surface cut along the plane is symmetric with respect to the axis. discharge electrode.

13. The discharge electrode according to claim 12, The corner of the cathode discharge surface on the upstream side of the laser gas is located farther in the second direction from the discharge space between the cathode electrode and the anode electrode than the corner of the cathode discharge surface on the downstream side of the laser gas.

14. The discharge electrode according to claim 13, When the upstream side of the laser gas from the axis of the cathode discharge surface is defined as a first discharge surface, and the downstream side of the laser gas from the axis of the cathode discharge surface is defined as a second discharge surface, the curvature of the first discharge surface is greater than the curvature of the second discharge surface.

15. The discharge electrode according to claim 14, a cross-sectional shape of the first discharge surface is a part of an ellipse having an ellipticity in a range of 1 / 5 to 1 / 3 and flattened in the second direction, The cross-sectional shape of the second discharge surface is a part of an ellipse that has an ellipticity in the range of 1 / 10 to 1 / 8 and is flattened in the second direction.

16. The discharge electrode according to claim 14, The cross-sectional shape of the cathode discharge surface is a part of an ellipse that is flattened in the second direction and has an ellipticity in the range of 1 / 5 to 1 / 3, with the center being located at a point downstream of the laser gas from the axis.

17. The discharge electrode according to claim 14, a cross-sectional shape of the first discharge surface is a part of an ellipse having an ellipticity in a range of 1 / 5 to 1 / 3 and flattened in the second direction, The cross-sectional shape of the second discharge surface is a straight line parallel to a third direction orthogonal to the first direction and the second direction, or inclined relative to the third direction.

18. The discharge electrode according to claim 13, When the upstream side of the laser gas from the axis of the cathode discharge surface is defined as a first discharge surface, and the downstream side of the laser gas from the axis of the cathode discharge surface is defined as a second discharge surface, a cross-sectional shape of the first discharge surface is a straight line parallel to a third direction orthogonal to the first direction and the second direction or inclined with respect to the third direction, The cross-sectional shape of the second discharge surface is a straight line parallel to the third direction or inclined with respect to the third direction.

19. The discharge electrode according to claim 12, The anode discharge surface has an ellipticity in the range of 1 / 6 to 1 / 4 and is part of an ellipse that is flattened in the second direction.

20. A method for manufacturing an electronic device, comprising: A laser chamber used in a gas laser device that excites a laser gas containing fluorine by discharge, a cathode electrode having a cathode discharge surface extending in a first direction; an anode electrode having an anode discharge surface extending in the first direction and disposed in a position where the anode discharge surface faces the cathode discharge surface in a second direction perpendicular to the first direction; a fan that circulates the laser gas through a discharge space between the cathode electrode and the anode electrode in a third direction perpendicular to the first direction and the second direction; a preionization electrode disposed upstream of the cathode electrode and the anode electrode in the direction of the laser gas; Equipped with In an initial state, a cross-sectional shape of the cathode discharge surface cut along a plane orthogonal to the first direction is asymmetric with respect to an axis parallel to the second direction, and a cross-sectional shape of the anode discharge surface cut along the plane is symmetric with respect to the axis. Laser Chamber generating laser light by a gas laser device comprising: outputting the laser light to an exposure device; exposing a photosensitive substrate to the laser light in the exposure apparatus to manufacture an electronic device; A method for manufacturing electronic devices.

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