Method for manufacturing a chamber for a gas laser apparatus and an electronic device.

Abstract

In this gas laser apparatus chamber, the distance to a first end from a virtual axis, which extends between a first main electrode and a second main electrode along a predetermined direction, increases from the one side to the other side in the predetermined direction, and the distance from the virtual axis to a second end decreases from the one side to the other side in the predetermined direction.

Description

Technical Field

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

Background Art

[0002] In recent years, in semiconductor exposure apparatuses, as semiconductor integrated circuits have been miniaturized and highly integrated, improvement in resolution has been demanded. For this reason, the wavelength of light emitted from an exposure light source has been shortened. For example, as a gas laser device for exposure, a KrF excimer laser device that outputs laser light having a wavelength of about 248 nm and an ArF excimer laser device that outputs laser light having a wavelength of about 193 nm are used.

[0003] The spectral linewidth of spontaneous emission light of a KrF excimer laser device and an ArF excimer laser device is as wide as 350 pm to 400 pm. Therefore, when a projection lens is composed of a material that transmits ultraviolet rays such as KrF and ArF laser light, chromatic aberration may occur. As a result, the resolution may decrease. Therefore, it is necessary to narrow the spectral linewidth of the laser light output from the gas laser device to such an extent that chromatic aberration can be ignored. For this reason, a narrowbanding module (Line Narrowing Module: LNM) including a narrowbanding element (etalon, grating, etc.) may be provided in the laser resonator of the gas laser device to narrow the spectral linewidth. Hereinafter, a gas laser device in which the spectral linewidth is narrowed is referred to as a narrowbanded gas laser device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] A chamber for a gas laser apparatus according to one aspect of the present disclosure is a chamber for a gas laser apparatus that seals a laser gas in an internal space, comprising: a first main electrode and a second main electrode provided in the internal space, with their longitudinal directions aligned in a predetermined direction and spaced apart from each other, which generate light from the laser gas by an applied voltage; a window provided on the wall surface of the chamber through which light is transmitted; a first pre-ionization electrode provided on one side of the first main electrode; and a second pre-ionization electrode provided on one side of the second main electrode, facing the first pre-ionization electrode, wherein the first pre-ionization electrode comprises a first dielectric pipe, a first pre-ionization internal electrode disposed inside the first dielectric pipe and extending along the longitudinal direction of the first dielectric pipe. The first dielectric pipe is provided with a first pre-ionization outer electrode that extends along the longitudinal direction of the first dielectric pipe and includes a first end facing the first dielectric pipe, and the second pre-ionization electrode includes a second dielectric pipe, a second pre-ionization inner electrode disposed inside the second dielectric pipe and extending along the longitudinal direction of the second dielectric pipe, and a second pre-ionization outer electrode that extends along the longitudinal direction of the second dielectric pipe and includes a second end facing the second dielectric pipe, and the distance from a virtual axis extending in a predetermined direction between the first and second main electrodes to the first end may increase from one side to the other in the predetermined direction, and the distance from the virtual axis to the second end may decrease from one side to the other in the predetermined direction.

[0006] A method for manufacturing an electronic device according to one aspect of the present disclosure is a chamber for a gas laser apparatus that seals a laser gas in an internal space, comprising: a first main electrode and a second main electrode provided in the internal space, with their longitudinal directions aligned in a predetermined direction and spaced apart from each other, which generate light from the laser gas by an applied voltage; a window provided on the wall surface of the chamber through which light is transmitted; a first pre-ionization electrode provided on one side of the first main electrode; and a second pre-ionization electrode provided on one side of the second main electrode, facing the first pre-ionization electrode, wherein the first pre-ionization electrode comprises a first dielectric pipe, a first pre-ionization internal electrode disposed inside the first dielectric pipe and extending along the longitudinal direction of the first dielectric pipe, and a second electrode extending along the longitudinal direction of the first dielectric pipe and facing the first dielectric pipe. A gas laser apparatus may generate laser light, output the laser light to an exposure apparatus, and expose a photosensitive substrate in the exposure apparatus in order to manufacture an electronic device. The apparatus comprises a first pre-ionization outer electrode including a first end, the second pre-ionization inner electrode comprising a second dielectric pipe, a second pre-ionization inner electrode disposed inside the second dielectric pipe and extending along the longitudinal direction of the second dielectric pipe, and a second pre-ionization outer electrode extending along the longitudinal direction of the second dielectric pipe and including a second end facing the second dielectric pipe, the distance from a virtual axis extending in a predetermined direction between the first main electrode and the second main electrode to the first end increases from one side to the other in the predetermined direction, and the distance from the virtual axis to the second end decreases from one side to the other in the predetermined direction. [Brief explanation of the drawing]

[0007] Some embodiments of this disclosure are described below, merely as examples, with reference to the accompanying drawings. [Figure 1] Figure 1 is a schematic diagram showing an example of the overall configuration of an electronic device manufacturing apparatus. [Figure 2] Figure 2 is a schematic diagram showing an example of the overall configuration of a comparative gas laser apparatus. [Figure 3] Figure 3 is a cross-sectional view of the comparative example chamber perpendicular to the direction of laser beam propagation. [Figure 4]Figure 4 is an electrical circuit diagram of the chamber in the comparative example. [Figure 5] Figure 5 shows the area around the preliminary ionization electrode shown in Figure 3, viewed along the Z direction. [Figure 6] Figure 6 is a top view of the area around the electrode shown in Figure 5. [Figure 7] Figure 7 is a view of the area around the pre-ionization electrode in Embodiment 1, along the Z direction. [Figure 8] Figure 8 is a top view of the area surrounding the preliminary ionization electrode shown in Figure 7. [Figure 9] Figure 9 is an electrical circuit diagram of the chamber in Embodiment 1. [Figure 10] Figure 10 is a view of the area around the pre-ionization electrode in a modified example of Embodiment 1, along the Z direction. [Figure 11] Figure 11 is a view of the area around the preliminary ionization electrode shown in Figure 10, along the X direction. [Figure 12] Figure 12 is a view of the area around the pre-ionization electrode in Embodiment 2, along the Z direction. [Figure 13] Figure 13 is a top view of the area surrounding the preliminary ionization electrode shown in Figure 12. [Figure 14] Figure 14 is an electrical circuit diagram of the chamber in Embodiment 2. [Figure 15] Figure 15 is a view of the area around the pre-ionization electrode in a modified example of Embodiment 2, viewed along the Z direction. [Figure 16] Figure 16 is a view of the area around the preliminary ionization electrode shown in Figure 15, along the X direction. Embodiment

[0008] 1. Description of the manufacturing equipment for electronic devices used in the exposure process for electronic devices. 2. Description of the comparative gas laser apparatus 2.1 Configuration 2.2 Operation 2.3 Challenges 3. Description of the Chamber of Embodiment 1 3.1 Configuration 3.2 Action and Effects 4. Description of the Chamber in Embodiment 2 4.1 Configuration 4.2 Function and Effect

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The embodiments described below show some examples of the present disclosure and do not limit the content of the present disclosure. Also, not all of the configurations and operations described in each embodiment are essential as the configurations and operations of the present disclosure. Note that the same reference numerals are assigned to the same components, and duplicate descriptions are omitted.

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

[0011] 2. Description of the Gas Laser Device in the Comparative Example 2.1 Configuration The gas laser device 100 in the comparative example will be described. Note that the comparative example of the present disclosure is a form recognized by the applicant as being known only to the applicant and is not a known example recognized by the applicant.

[0012] Figure 2 is a schematic diagram showing an overall schematic configuration example of a gas laser device 100 of a comparative example. The gas laser device 100 is, for example, an ArF excimer laser device that uses a mixed gas containing argon (Ar), fluorine (F2), and neon (Ne). This gas laser device 100 outputs laser light having a central wavelength of about 193 nm. Note that the gas laser device 100 may be a gas laser device other than an ArF excimer laser device. For example, it may be a KrF excimer laser device that uses a mixed gas containing krypton (Kr), F2, and Ne. In this case, the gas laser device 100 emits laser light having a central wavelength of about 248 nm. A mixed gas containing Ar, F2, and Ne, which is a laser medium, or a mixed gas containing Kr, F2, and Ne, which is a laser medium, may be called a laser gas.

[0013] The gas laser device 100 mainly includes a housing 110, a laser oscillator 130, a monitor module 160, a shutter 170, and a laser processor 190 disposed in the internal space of the housing 110.

[0014] The laser oscillator 130 includes a chamber device CH, a charger 141, a pulse power module 143, a narrowband module 145, and an output coupling mirror 147. In FIG. 2, the internal configuration of the chamber device CH is shown as viewed from a direction substantially perpendicular to the traveling direction of the laser light.

[0015] Examples of materials for the chamber 131 of the chamber apparatus CH include nickel-plated aluminum or nickel-plated stainless steel. The chamber 131 includes an internal space where light is generated by the excitation of the laser medium in the laser gas. This light travels to windows 139a and 139b, which will be described later. The laser gas is supplied to the internal space of the chamber 131 from a laser gas supply source (not shown) through piping (not shown). The laser gas in the chamber 131 is then subjected to processing such as removing F2 gas by a halogen filter, and exhausted to the housing 110 through piping (not shown) by an exhaust pump (not shown).

[0016] In the internal space of chamber 131, the first main electrode, electrode 133a, and the second main electrode, electrode 133b, are spaced apart from each other and facing each other, with their respective longitudinal directions aligned with the direction of laser beam propagation. In the following explanation, the longitudinal direction of electrodes 133a and 133b may be described as the Z direction, the direction perpendicular to the Z direction in which electrodes 133a and 133b are aligned and spaced apart may be described as the Y direction, and the direction perpendicular to both the Y and Z directions may be described as the X direction. Electrodes 133a and 133b are discharge electrodes for exciting the laser medium by glow discharge. In this example, electrode 133a is the anode and electrode 133b is the cathode.

[0017] Electrode 133a is supported and electrically connected to the electrode holder portion 137. Electrode 133b is fixed to the inner space side of the chamber 131 of the plate-shaped electrical insulation portion 135 by a conductive member 157, for example, a bolt. The conductive member 157 is electrically connected to the pulse power module 143 and applies a high voltage from the pulse power module 143 to electrode 133b.

[0018] The electrical insulating section 135 includes an insulator. Examples of materials for the electrical insulating section 135 include alumina ceramics, which have low reactivity with F2 gas. The electrical insulating section 135 only needs to have electrical insulating properties; examples of such materials include resins such as phenolic resin and fluororesin, or materials such as quartz and glass. The electrical insulating section 135 closes an opening provided in the chamber 131 and is fixed to the chamber 131.

[0019] The charger 141 is a DC power supply that charges a charging capacitor (not shown) in the pulse power module 143 with a predetermined voltage. The pulse power module 143 includes a switch 143a controlled by a laser processor 190. When the switch 143a is turned from OFF to ON, the pulse power module 143 generates a pulsed high voltage from the electrical energy stored in the charging capacitor and applies this high voltage between electrodes 133a and 133b.

[0020] When a high voltage is applied between electrodes 133a and 133b, a discharge occurs between them. The energy of this discharge excites the laser medium in chamber 131, and the excited laser medium emits light when it transitions to the ground state.

[0021] A pair of windows 139a and 139b are provided on the wall of the chamber 131. Window 139a is located at one end of the chamber 131 in the direction of laser beam propagation, and window 139b is located at the other end in the same direction of propagation. Windows 139a and 139b sandwich the space between electrodes 133a and 133b. Windows 139a and 139b are inclined to form a Brewster angle with respect to the direction of laser beam propagation so as to suppress the reflection of P-polarized laser beam. The oscillating laser beam, as described later, exits the chamber 131 through windows 139a and 139b. As described above, a pulsed high voltage is applied between electrodes 133a and 133b by the pulse power module 143, so this laser beam is pulsed laser beam.

[0022] The narrowband module 145 includes a housing 145a, a prism 145b, a grating 145c, and a rotating stage (not shown) arranged in the internal space of the housing 145a. The housing 145a has an opening, which connects to the rear side of the chamber 131.

[0023] The prism 145b widens the beam width of the light emitted from the window 139a and directs this light onto the grating 145c. The prism 145b also reduces the beam width of the reflected light from the grating 145c and returns this light to the interior space of the chamber 131 via the window 139a. The prism 145b is supported by a rotating stage and rotates by the rotating stage. The rotation of the prism 145b changes the angle of incidence of the light on the grating 145c. Therefore, the rotation of the prism 145b allows for the selection of the wavelength of light returning from the grating 145c through the prism 145b to the chamber 131. Figure 2 shows an example with one prism 145b, but at least one prism is required.

[0024] The surface of the grating 145c is made of a highly reflective material and has numerous grooves at predetermined intervals. The cross-sectional shape of each groove is, for example, a right triangle. When light incident on the grating 145c from the prism 145b is reflected by these grooves, it is diffracted in a direction corresponding to the wavelength of the light. The grating 145c is Littrow-positioned so that the angle of incidence of the light incident on the grating 145c from the prism 145b matches the diffraction angle of the diffracted light of the desired wavelength. This ensures that light near the desired wavelength is returned to the chamber 131 via the prism 145b.

[0025] The output coupling mirror 147 is positioned in the internal space of the optical path tube 147a, which is connected to the front side of the chamber 131, and faces the window 139b. The output coupling mirror 147 transmits a portion of the laser light emitted from the window 139b toward the monitor module 160, and reflects the other portion back through the window 139b to the internal space of the chamber 131. In this way, the grating 145c and the output coupling mirror 147 form a Fabry-Perot type laser resonator, and the chamber 131 is positioned on the optical path of the laser resonator.

[0026] The monitor module 160 is positioned on the optical path of the laser beam emitted from the output coupling mirror 147. The monitor module 160 includes a housing 161 and a beam splitter 163 and an optical sensor 165, which are located in the internal space of the housing 161. An opening is formed in the housing 161, and through this opening, the internal space of the housing 161 communicates with the internal space of the optical path tube 147a.

[0027] The beam splitter 163 transmits a portion of the laser light emitted from the output coupling mirror 147 towards the shutter 170, and reflects the other portion of the laser light towards the light-receiving surface of the photosensor 165. The photosensor 165 measures the energy E of the laser light incident on the light-receiving surface and outputs a signal indicating the measured energy E to the laser processor 190.

[0028] The laser processor 190 of this disclosure is a processing unit that includes a storage device 190a in which a control program is stored, and a CPU (Central Processing Unit) 190b that executes the control program. The laser processor 190 is specially configured or programmed to perform various processes included in this disclosure. The laser processor 190 also controls the entire gas laser apparatus 100.

[0029] The laser processor 190 transmits and receives various signals to and from the exposure processor 230 of the exposure apparatus 200. For example, the laser processor 190 receives signals from the exposure processor 230 indicating the light emission trigger Tr and the target energy Et, which will be described later. The target energy Et is the target value of the energy of the laser light used in the exposure process. The laser processor 190 controls the charging voltage of the charger 141 based on the energy E and target energy Et received from the optical sensor 165 and the exposure processor 230. By controlling this charging voltage, the energy of the laser light is controlled. The laser processor 190 also transmits an ON or OFF command signal for the switch 143a to the pulse power module 143. The laser processor 190 is also electrically connected to the shutter 170 and controls the opening and closing of the shutter 170.

[0030] The laser processor 190 closes the shutter 170 until the difference ΔE between the energy E received from the monitor module 160 and the target energy Et received from the exposure processor 230 falls within an acceptable range. Once the difference ΔE is within an acceptable range, the laser processor 190 sends a ready-to-receive signal to the exposure processor 230 indicating that it is ready to receive the light emission trigger Tr. Upon receiving the ready-to-receive signal, the exposure processor 230 sends a signal indicating the light emission trigger Tr to the laser processor 190, and upon receiving the signal indicating the light emission trigger Tr, the laser processor 190 opens the shutter 170. The light emission trigger Tr is defined by a predetermined repetition frequency f of the laser light and a predetermined number of pulses P, and is an external trigger that causes the exposure processor 230 to cause the laser oscillator 130 to oscillate. The repetition frequency f of the laser light is, for example, 100 Hz or more and 10 kHz or less.

[0031] The shutter 170 is positioned in the optical path of the laser beam in the internal space of the optical path tube 171, which communicates with an opening formed on the opposite side of the housing 161 of the monitor module 160 from the side to which the optical path tube 147a is connected. The internal spaces of the optical path tubes 171 and 147a, and the internal spaces of the housings 161 and 145a are supplied and filled with purge gas. The purge gas contains an inert gas such as nitrogen (N2). The purge gas is supplied from a purge gas supply source (not shown) through piping (not shown). The optical path tube 171 also communicates with the exposure apparatus 200 through an opening in the housing 110 and an optical path tube 500 connecting the housing 110 and the exposure apparatus 200. The laser beam that passes through the shutter 170 is incident on the exposure apparatus 200.

[0032] The exposure processor 230 of this disclosure is a processing unit that includes a storage device 230a in which a control program is stored and a CPU 230b that executes the control program. The exposure processor 230 is specially configured or programmed to perform various processes included in this disclosure. The exposure processor 230 also controls the entire exposure apparatus 200.

[0033] Figure 3 is a cross-sectional view of the comparative example chamber 131 perpendicular to the direction of laser beam propagation. A cross-flow fan 149 and a heat exchanger 151 are further arranged in the internal space of the chamber 131.

[0034] The cross-flow fan 149 and heat exchanger 151 are positioned on the opposite side of the electrode 133a with respect to the electrode holder portion 137. Within the internal space of the chamber 131, the space in which the cross-flow fan 149 and heat exchanger 151 are located communicates with the space between electrodes 133a and 133b. The heat exchanger 151 is a radiator positioned next to the cross-flow fan 149 and connected to piping (not shown) through which a cooling medium, whether liquid or gas, flows. As shown in Figure 2, the cross-flow fan 149 is connected to a motor 149a located outside the chamber 131 and rotates due to the rotation of the motor 149a. As the cross-flow fan 149 rotates, the laser gas sealed in the internal space of the chamber 131 circulates as shown by the thick arrows in Figure 3. In other words, the laser gas circulates in the following order: cross-flow fan 149, between electrodes 133a and 133b, heat exchanger 151, and then cross-flow fan 149. At least a portion of the circulating laser gas passes through the heat exchanger 151, which regulates the temperature of the laser gas. The circulation of the laser gas allows impurities generated by the main discharge between electrodes 133a and 133b to move downstream, ensuring that fresh laser gas is supplied between electrodes 133a and 133b for the next discharge. Furthermore, as the laser gas passes through the heat exchanger 151, heat associated with the main discharge is removed, suppressing the temperature rise of the laser gas. The ON / OFF state and rotational speed of the motor 149a are controlled by the laser processor 190. Therefore, the laser processor 190 can adjust the circulation speed of the laser gas circulating within the chamber 131 by controlling the motor 149a.

[0035] The electrode holder portion 137 is electrically connected to the chamber 131 via the wiring 137a. The electrode 133a supported by the electrode holder portion 137 is connected to ground potential via the electrode holder portion 137, the wiring 137a, and the chamber 131.

[0036] On the electrode holder portion 137, a pre-ionization electrode 10 is provided to the side of the electrode 133a. The pre-ionization electrode 10 comprises a dielectric pipe 11, a pre-ionization inner electrode, and a pre-ionization outer electrode. Hereinafter, the pre-ionization inner electrode and the pre-ionization outer electrode may be referred to as the inner electrode 13 and the outer electrode 15, respectively.

[0037] The dielectric pipe 11 is, for example, cylindrical. Examples of materials for the dielectric pipe 11 include alumina ceramics and sapphire.

[0038] The internal electrode 13 is rod-shaped, positioned inside the dielectric pipe 11, and extends along the longitudinal direction of the dielectric pipe 11. Examples of materials for the internal electrode 13 include copper and brass.

[0039] The external electrode 15 is positioned between the dielectric pipe 11 and the electrode 133a and extends along the longitudinal direction of the dielectric pipe 11. The external electrode 15 includes an end 15a that faces a portion of the outer circumferential surface of the dielectric pipe 11. This end 15a extends from one end to the other of the external electrode 15 in the longitudinal direction. The external electrode 15 is bent in an in-plane direction perpendicular to the longitudinal direction of the dielectric pipe 11, and due to the bending, the end 15a contacts the outer circumferential surface of the dielectric pipe 11 by pressing against it. A screw hole (not shown) is provided at the end of the external electrode 15 opposite to the end 15a, and the external electrode 15 is fixed to a spacer 17 by a screw (not shown) that is screwed into the screw hole. The spacer 17 is fixed to the electrode 133a. Therefore, it can be understood that the external electrode 15 is fixed to the electrode 133a via the spacer 17. Examples of materials for the external electrode 15 include copper and brass.

[0040] Figure 4 is an electrical circuit diagram of the comparative example chamber 131. A peaking capacitor 31a and a pre-ionization capacitor 31b are further arranged in the chamber 131. The internal electrode 13 is electrically connected to one end of the pre-ionization capacitor 31b via a current introduction terminal 31c. The external electrode 15 is electrically connected to the electrode 133a via an electrode holder portion 137, and is also electrically connected to the chamber 131 via the electrode holder portion 137 and wiring 137a. The external electrode 15, electrode holder portion 137, wiring 137a, and chamber 131 are at ground potential. The pulse power module 143 is electrically connected to the peaking capacitor 31a and the pre-ionization capacitor 31b so that when the switch 143a of the pulse power module 143 is turned ON, the charge stored in the charging capacitor (not shown) of the pulse power module 143 is transferred to the peaking capacitor 31a and the pre-ionization capacitor 31b.

[0041] Figure 5 is a view of the area around the preliminary ionization electrode 10 shown in Figure 3, along the Z direction, and Figure 6 is a top view of the area around electrode 133a shown in Figure 5. The thick arrows in Figure 5 indicate the flow of laser gas.

[0042] On the electrode holder portion 137, a pair of holders 27 and 28 are fixed to the side of the electrode 133a. One end of the dielectric pipe 11 is inserted into the hole 27a of holder 27, and the other end of the dielectric pipe 11 is inserted into a hole (not shown) of holder 28. In this way, the dielectric pipe 11 is held by the holders 27 and 28.

[0043] When a high voltage is applied between electrodes 133a and 133b, and a main discharge occurs between electrodes 133a and 133b, an acoustic wave 41a, shown by the solid curve in Figure 5, is generated by the main discharge. The acoustic wave 41a is a compression wave of the laser gas in the chamber 131, and propagates within the chamber 131 while spreading from the discharge space between electrodes 133a and 133b. The propagation speed is approximately 500 m / s.

[0044] The acoustic wave 41a is reflected by internal components of the chamber 131, such as the external electrode 15, which is located in the internal space of the chamber 131, and returns to the discharge space as a reflected wave 41b, shown by the dashed curve in Figure 5. If the reflected wave 41b returns to the discharge space at the timing when the main discharge occurs, it can affect the performance of the laser light, such as causing the main discharge to become unstable or reducing the energy stability of the laser light emitted from the gas laser device 100. This effect tends to be greater when the repetition frequency of the laser light is 2 kHz or higher.

[0045] In the comparative example gas laser apparatus 100, in order to suppress the influence of acoustic waves 41a on the performance of the laser light, the longitudinal directions of the dielectric pipe 11 and the external electrode 15 are tilted with respect to a virtual axis 50, which will be described later, when viewed along the Y direction. Figure 6 illustrates the central axis 11a of the dielectric pipe 11 tilted with respect to the virtual axis 50 as an example to facilitate understanding of this tilt. The virtual axis 50 is an axis that extends in the Z direction between electrodes 133a and 133b. The virtual axis 50 is located midway between electrodes 133a and 133b and coincides with the central axis of electrode 133a when viewed along the Y direction. Due to the above tilt, the distance from the virtual axis 50 to the end 15a of the external electrode 15 increases from one end to the other in the Z direction. One end in the Z direction is located towards the narrowband module 145, and the other end is located towards the monitor module 160. Here, the explanation uses the end 15a, but the same applies to the dielectric pipe 11 and the external electrode 15. Due to the above-mentioned slope, for example, the length of the propagation path of the reflected wave 41b that is reflected by the external electrode 15 and returns to the discharge space changes depending on its position in the Z direction. As a result, the phase of the reflected wave 41b returning to the discharge space is shifted, suppressing the reflected wave 41b from returning to the discharge space at the timing when the main discharge occurs, and thus suppressing the influence of the acoustic wave 41a on the performance of the laser light. In other words, unstable main discharges are suppressed, and the decrease in the energy stability of the laser light emitted from the gas laser device 100 is suppressed.

[0046] 2.2 Operation Next, the operation of the comparative example gas laser apparatus 100 will be described.

[0047] Before the gas laser device 100 emits laser light, the internal spaces of the optical path tubes 147a, 171, and 500, and the internal spaces of the housings 145a and 161 are filled with purge gas from a purge gas supply source (not shown). In addition, laser gas is supplied to the internal space of the chamber 131 from a laser gas supply source (not shown). Once the laser gas is supplied, the laser processor 190 controls the motor 149a to rotate the cross-flow fan 149. The rotation of the cross-flow fan 149 causes the laser gas to circulate within the internal space of the chamber 131.

[0048] When the gas laser device 100 emits laser light, the laser processor 190 receives a signal indicating the target energy Et and a signal indicating the light emission trigger Tr from the exposure processor 230. The laser processor 190 then sets the charging voltage output from the charger 141 so that the difference ΔE between the laser light energy E and the target energy Et is within an acceptable range. The laser processor 190 also turns on the switch 143a of the pulse power module 143. As a result, the pulse power module 143 applies a pulsed high voltage between electrodes 133a and 133b and between the inner electrode 13 and the outer electrode 15 from the electrical energy stored in a charging capacitor (not shown). When a high voltage is applied between the inner electrode 13 and the outer electrode 15, a corona discharge occurs near the dielectric pipe 11 and its end 15a, and ultraviolet light is emitted. When the ultraviolet light irradiates the laser gas between electrodes 133a and 133b, the laser gas between electrodes 133a and 133b is pre-ionized. After pre-ionization, when the voltage between electrode 133a and electrode 133b reaches the dielectric breakdown voltage, a main discharge occurs between electrode 133a and electrode 133b. This generates an excimer from the laser medium contained in the laser gas between electrode 133a and electrode 133b, which emits light upon dissociation. This light resonates between the grating 145c and the output coupling mirror 147, and the light is amplified each time it passes through the discharge space in the internal space of chamber 131, causing laser oscillation. A portion of the laser light then passes through the output coupling mirror 147 as pulsed laser light and proceeds to the beam splitter 163.

[0049] A portion of the laser light that travels to the beam splitter 163 is reflected by the beam splitter 163 and received by the light sensor 165. The light sensor 165 measures the energy E of the received laser light and outputs a signal indicating the energy E to the laser processor 190. The laser processor 190 controls the charging voltage so that the difference ΔE between the energy E and the target energy Et is within an acceptable range.

[0050] Furthermore, although the acoustic wave 41a is generated by the main discharge between electrode 133a and electrode 133b, the longitudinal directions of the dielectric pipe 11 and the outer electrode 15 are tilted with respect to the virtual axis 50. As a result, as described above, the phase of the reflected wave 41b returning to the discharge space is shifted, and the decrease in the energy stability of the laser light emitted from the gas laser device 100 is suppressed.

[0051] 2.3 Challenges In the comparative example gas laser apparatus 100, in order to suppress the influence of acoustic waves 41a on the performance of the laser light, the longitudinal directions of the dielectric pipe 11 and the outer electrode 15 are tilted with respect to the virtual axis 50, and the distance from the virtual axis 50 to the end 15a is increased from one end to the other in the Z direction. However, ultraviolet light generated near the dielectric pipe 11 and the end 15a tends to attenuate as the distance increases, according to the Lambert-Beer law. For this reason, the pre-ionization intensity by the pre-ionization electrode 10 on the virtual axis 50 may be non-uniform in the axial direction of the virtual axis 50. Specifically, the pre-ionization intensity may decrease from one end located on the narrowband module 145 side to the other end located on the monitor module 160 side. If the pre-ionization intensity is non-uniform, an unstable main discharge may occur, and the energy stability of the laser light emitted from the gas laser apparatus 100 may decrease. This raises concerns that the exposure apparatus 200 may not emit laser light that meets the required performance, thus reducing the reliability of the gas laser apparatus 100.

[0052] Therefore, in the following embodiment, a chamber 131 of the gas laser apparatus 100 in which a decrease in reliability can be suppressed is exemplified.

[0053] 3. Description of the Chamber of Embodiment 1 Next, the chamber 131 of this embodiment will be described. Components similar to those described above are denoted by the same reference numerals, and redundant descriptions are omitted unless otherwise specified. Also, in some drawings, some components may be omitted or simplified for clarity.

[0054] 3.1 Configuration Figure 7 is a view of the area around the pre-ionization electrode in this embodiment, along the Z direction, and Figure 8 is a top view of the area around the pre-ionization electrode shown in Figure 7. In Figure 8, the electrode 133b and the electrical insulation portion 135 are omitted for clarity.

[0055] Chamber 131 of this embodiment differs from the comparative example in that it has one additional pre-ionization electrode. For convenience of explanation, the two pre-ionization electrodes will be described below as the first pre-ionization electrode and the second pre-ionization electrode. The first pre-ionization electrode may be referred to as pre-ionization electrode 60, and the second pre-ionization electrode as pre-ionization electrode 70. Pre-ionization electrode 60 corresponds to pre-ionization electrode 10 of the comparative example, with only the reference numeral changed. Pre-ionization electrode 70 has the same configuration as pre-ionization electrode 10.

[0056] For the sake of explanation, the dielectric pipe, pre-ionization inner electrode, pre-ionization outer electrode, and end of the pre-ionization electrode 60 will be described as the first dielectric pipe, the first pre-ionization inner electrode, the first pre-ionization outer electrode, and the first end. Hereafter, each of these components in the pre-ionization electrode 60 may be referred to as the dielectric pipe 61, the inner electrode 63, the outer electrode 65, and the first end 65a. Similarly, the dielectric pipe, pre-ionization inner electrode, pre-ionization outer electrode, and end of the pre-ionization electrode 70 will be described as the second dielectric pipe, the second pre-ionization inner electrode, the second pre-ionization outer electrode, and the second end. Hereafter, each of these components in the pre-ionization electrode 70 may be referred to as the dielectric pipe 71, the inner electrode 73, the outer electrode 75, and the second end 75a.

[0057] The pre-ionization electrode 60 is located on one side of electrode 133a in the X direction, and the pre-ionization electrode 70 is located on the same side of electrode 133b, facing the pre-ionization electrode 60. In Figure 8, the dielectric pipe 61, the first end 65a, and the portion of the outer electrode 65 that overlaps with the dielectric pipe 71, the second end 75a, and the outer electrode 75 are shown with dashed lines. The pre-ionization electrodes 60 and 70 are positioned upstream of the laser gas flowing in the X direction between electrodes 133a and 133b. In Figure 7, the flow of the laser gas is shown with thick arrows.

[0058] In the preliminary ionization electrodes 60 and 70, the longitudinal directions of the dielectric pipes 61 and 71 are tilted in opposite directions in the X direction with respect to the virtual axis 50, such that the dielectric pipes 61 and 71 intersect each other when viewed along the Y direction. Figure 8 illustrates the central axes 61a and 71a of the dielectric pipes 61 and 71 to facilitate understanding of this tilt.

[0059] As the dielectric pipes 61 and 71 are tilted, the extending directions of the external electrodes 65 and 75 and the ends 65a and 75a are also tilted with respect to the virtual axis 50. The first end 65a is the same length as the second end 75a, and when viewed along the Y direction, the center of the first end 65a in the longitudinal direction of the external electrode 65 coincides with the center of the second end 75a in the longitudinal direction of the external electrode 75. Furthermore, the first end 65a is tilted counterclockwise with respect to the virtual axis 50 around its center, and the second end 75a is tilted clockwise with respect to the virtual axis 50 around its center. Therefore, when viewed along the Y direction, the distance from the virtual axis 50 to the first end 65a increases from one end to the other in the Z direction. Also, when viewed along the Y direction, the distance from the virtual axis 50 to the second end 75a decreases from one end to the other in the Z direction. In the Z direction, one end is located towards the narrowband module 145, and the other end is located towards the monitor module 160. When viewed along the X direction, the first end 65a and the second end 75a are arranged in parallel.

[0060] When viewed along the Y direction, the extension direction of the first end 65a is inclined at a first angle θ1 with respect to the virtual axis 50, and the extension direction of the second end 75a is inclined at a second angle θ2, the same as the first angle θ1, but in the opposite direction to the first end 65a with respect to the virtual axis 50. Therefore, the first end 65a is positioned symmetrically with respect to the second end 75a with respect to its center. Furthermore, the extension direction of the first end 65a is inclined at the same angle as the extension direction of the second end 75a with respect to the virtual axis 50, but in the opposite direction to the extension direction of the second end 75a. The angles θ1 and θ2 are acute angles between 0.2 degrees and 3.0 degrees. Note that the first end 65a may be positioned asymmetrically with respect to the second end 75a with respect to its center, and the angles θ1 and θ2 may be different from each other.

[0061] Furthermore, it is preferable that the first distance L1 from the center of the first end 65a in the longitudinal direction of the external electrode 65 to the virtual axis 50 is the same as the second distance L2 from the center of the second end 75a in the longitudinal direction of the external electrode 75 to the virtual axis 50. If the first distance L1 and the second distance L2 are different, it is preferable that one of them is 0.9 times or more and 1.1 times or less of the other.

[0062] In the above explanation, we used the ends 65a and 75a, but the dielectric pipes 61 and 71, the internal electrodes 63 and 73, and the external electrodes 65 and 75 are also inclined in the same way as the ends 65a and 75a.

[0063] The external electrode 65 is fixed to the first spacer 67, which corresponds to the spacer 17 of the comparative example, in the same manner as in the comparative example. Therefore, the external electrode 65 is fixed to the electrode 133a via the first spacer 67. Note that the external electrode 65 may also be fixed directly to the electrode 133a. Incidentally, on the inner space side of the chamber 131 of the electrical insulation portion 135 of this embodiment, a second spacer 77 is arranged, which has the same configuration as the spacer 17 of the comparative example and is fixed to the electrode 133b. The external electrode 75 is fixed to the second spacer 77 in the same manner as the external electrode 15 is fixed to the spacer 17. Therefore, the external electrode 75 is fixed to the electrode 133b via the second spacer 77. Note that the external electrode 75 may also be fixed directly to the electrode 133b.

[0064] The holder 27 of this embodiment extends in the Y direction and includes two holes 27a and 27b that are spaced apart in the Y direction. One end of the dielectric pipe 61 is inserted into hole 27a on the electrode holder portion 137 side, and one end of the dielectric pipe 71 is inserted into hole 27b on the electrical insulation portion 135 side. As a result, one end of each dielectric pipe 61 and 71 is held by the holder 27. The holder 28 of this embodiment has the same configuration as the holder 27 of this embodiment, with the other end of the dielectric pipe 61 being inserted into a hole (not shown) on the electrode holder portion 137 side of the holder 28, and the other end of the dielectric pipe 71 being inserted into a hole (not shown) on the electrical insulation portion 135 side of the holder 28. As a result, the other ends of each dielectric pipe 61 and 71 are held by the holder 28.

[0065] One end of each of the internal electrodes 63 and 73 is electrically connected to the other by an internal electrode connector 33a. The other ends of each of the internal electrodes 63 and 73 may also be electrically connected to the other by an internal electrode connector 33a. The internal electrode connector 33a is cylindrical, but may also be wire-shaped. The internal electrode 73 is connected to the pulse power module 143 via wiring not shown. The other end of the external electrode 75 is electrically connected to electrode 133b.

[0066] Figure 9 is an electrical circuit diagram of the chamber 131 in this embodiment. The electrical circuit diagram of this embodiment differs from the electrical circuit diagram of the comparative example in that the pre-ionization capacitor 31b and the current introduction terminal 31c are not arranged. When switch 143a is turned ON, the charge stored in the charging capacitor is transferred to the peaking capacitor 31a, and at the same time the voltage between electrode 133a and electrode 133b increases. In addition, a voltage equal to half the voltage between electrode 133a and electrode 133b is induced in each of the internal electrodes 63 and 73. As a result, corona discharge occurs near the dielectric pipe 61 and the first end 65a and near the dielectric pipe 71 and the second end 75a, and ultraviolet light is emitted from each. When ultraviolet light irradiates the laser gas between electrode 133a and electrode 133b, the laser gas between electrode 133a and electrode 133b is pre-ionized. After pre-ionization, when the voltage between electrode 133a and electrode 133b reaches the dielectric breakdown voltage, a main discharge occurs between electrode 133a and electrode 133b. This generates an excimer from the laser medium contained in the laser gas between electrode 133a and electrode 133b, which emits light when it dissociates.

[0067] 3.2 Action and Effects In the chamber 131 of this embodiment, the distance from the virtual axis 50 to the first end 65a increases from one end to the other in the Z direction. Conversely, the distance from the virtual axis 50 to the second end 75a decreases from one end to the other in the Z direction.

[0068] When a high voltage is applied between the inner electrode 63 and the outer electrode 65 and between the inner electrode 73 and the outer electrode 75 at the pre-ionization electrodes 60 and 70, corona discharge occurs near the dielectric pipe 61 and the first end 65a and near the dielectric pipe 71 and the second end 75a, and ultraviolet light is emitted. When the ultraviolet light irradiates the laser gas between electrode 133a and electrode 133b, the laser gas between electrode 133a and electrode 133b is pre-ionized. After pre-ionization, when the voltage between electrode 133a and electrode 133b reaches the dielectric breakdown voltage, a main discharge occurs between electrode 133a and electrode 133b. However, in this configuration, the distance from the virtual axis 50 to the first end 65a increases from one end to the other in the Z direction, so the pre-ionization intensity by the pre-ionization electrode 60 decreases from one end to the other in the Z direction along the virtual axis 50. Furthermore, as the distance from the virtual axis 50 to the second end 75a decreases from one end to the other in the Z direction, the pre-ionization intensity from the pre-ionization electrode 70 increases from one end to the other in the Z direction along the virtual axis 50. In the virtual axis 50, the pre-ionization intensity from the pre-ionization electrode 60, which decreases from one end to the other in the Z direction, and the pre-ionization intensity from the pre-ionization electrode 70, which increases from one end to the other in the Z direction, combine with each other, thus suppressing non-uniformity of the pre-ionization intensity. As a result, unstable main discharge can be suppressed, and the decrease in the energy stability of the laser light emitted from the gas laser device 100 can be suppressed. Therefore, laser light that meets the required performance can be emitted from the exposure device 200, and the decrease in the reliability of the gas laser device 100 can be suppressed.

[0069] Furthermore, in this chamber 131, the pre-ionization electrode 60 and the pre-ionization electrode 70 are positioned upstream of the laser gas flowing between electrode 133a and electrode 133b.

[0070] When a main discharge occurs between electrode 133a and electrode 133b, discharge products such as positive ions, negative ions, and metal fluorides are generated. These discharge products are carried away by the laser gas flowing between electrode 133a and electrode 133b. If pre-ionization electrodes 60 and 70 are positioned downstream of the laser gas flow, the discharge products carried away by the laser gas may absorb ultraviolet light emitted from pre-ionization electrodes 60 and 70, respectively. This can suppress the irradiation of the laser gas between electrode 133a and electrode 133b with ultraviolet light. However, in this configuration, pre-ionization electrodes 60 and 70 are positioned upstream of the laser gas flow, thus suppressing the absorption of ultraviolet light by the discharge products. Consequently, unstable main discharges are suppressed, and the decrease in the energy stability of the laser light emitted from the gas laser device 100 is suppressed. The pre-ionization electrodes 60 and 70 may be positioned downstream of electrodes 133a and 133b from the laser gas flowing between electrodes 133a and 133b.

[0071] Furthermore, in this chamber 131, the extension direction of the first end 65a is inclined in the opposite direction to the extension direction of the second end 75a at the same angle as the extension direction of the second end 75a with respect to the virtual axis 50, and the first distance L1 is the same as the second distance L2.

[0072] In this configuration, when viewed along the Y direction, the first end 65a and the second end 75a are arranged symmetrically with respect to their respective centers, and when viewed along the X direction, the first end 65a and the second end 75a are arranged parallel to each other. Therefore, non-uniformity of the pre-ionization intensity along the virtual axis 50 can be further suppressed, and the decrease in the energy stability of the laser light emitted from the gas laser device 100 can be further suppressed.

[0073] In addition, in this chamber 131, the first end 65a may be tilted clockwise, and the second end 75a may be tilted counterclockwise. In this case, the distance from the virtual axis 50 to the first end 65a decreases from one end to the other in the Z direction. Also, the distance from the virtual axis 50 to the second end 75a increases from one end to the other in the Z direction.

[0074] Figure 10 is a view of the area around the preliminary ionization electrodes 60 and 70 in a modified example of this embodiment, along the Z direction, and Figure 11 is a view of the area around the preliminary ionization electrodes 60 and 70 shown in Figure 10, along the X direction.

[0075] In this modified example, the orientation of the inclination of the first end 65a and the second end 75a differs from that of Embodiment 1. When viewed along the Y direction, the dielectric pipe 61, the outer electrode 65, and the first end 65a overlap with the dielectric pipe 71, the outer electrode 75, and the second end 75a, and are not misaligned with them. Furthermore, in this modified example, the extending direction of the first end 65a and the extending direction of the second end 75a are inclined in the same direction in the Y direction with respect to the virtual axis 50 when viewed along the X direction. Specifically, the first end 65a moves away from the virtual axis 50 from one end to the other in the Z direction, and the second end 75a approaches the virtual axis 50 from one end to the other in the Z direction. The extending direction of the first end 65a is parallel to the extending direction of the second end 75a. Therefore, the distance from the virtual axis 50 to the first end 65a increases from one end to the other in the Z direction. Furthermore, the distance from the virtual axis 50 to the second end 75a decreases in the Z direction from one end to the other.

[0076] With this configuration, when viewed along the X direction, the non-uniformity of the pre-ionization intensity in the virtual axis 50 can be more suppressed compared to the case where the extending direction of the first end 65a is not parallel to the extending direction of the second end 75a, and the decrease in the stability of the energy of the laser light emitted from the gas laser device 100 can be more suppressed. Note that when viewed along the X direction, the extending direction of the first end 65a may be not parallel to the extending direction of the second end 75a. Also, when viewed along the Y direction, the extending direction of the first end 65a may be offset from the extending direction of the second end 75a.

[0077] 4. Description of the Chamber in Embodiment 2 Next, the chamber 131 of this embodiment will be described. Components similar to those described above will be denoted by the same reference numerals, and redundant descriptions will be omitted unless specifically stated.

[0078] 4.1 Configuration Figure 12 is a view of the area around the preliminary ionization electrodes 60 and 70 in this embodiment, along the Z direction, and Figure 13 is a top view of the area around the preliminary ionization electrodes 60 and 70 shown in Figure 12. In Figure 13, the electrode 133b and the electrical insulation portion 135 are omitted from the illustration for clarity.

[0079] In this embodiment, the chamber 131 differs from that of Embodiment 1 in that two additional pre-ionization electrodes are added. For the sake of explanation, the two added pre-ionization electrodes will be described as the third pre-ionization electrode and the fourth pre-ionization electrode. The third pre-ionization electrode may be referred to as pre-ionization electrode 80, and the fourth pre-ionization electrode as pre-ionization electrode 90.

[0080] The pre-ionization electrodes 80 and 90 have the same configuration as the pre-ionization electrode 10 in the comparative example, with pre-ionization electrode 80 positioned to the side of electrode 133a and pre-ionization electrode 90 positioned to the side of electrode 133b.

[0081] For the sake of explanation, the dielectric pipe, pre-ionization inner electrode, pre-ionization outer electrode, and end of the pre-ionization electrode 80 will be described as the third dielectric pipe, the third pre-ionization inner electrode, the third pre-ionization outer electrode, and the third end. Hereafter, each of these components in the pre-ionization electrode 80 may be referred to as the dielectric pipe 81, the inner electrode 83, the outer electrode 85, and the third end 85a. Similarly, the dielectric pipe, pre-ionization inner electrode, pre-ionization outer electrode, and end of the pre-ionization electrode 90 will be described as the fourth dielectric pipe, the fourth pre-ionization inner electrode, the fourth pre-ionization outer electrode, and the fourth end. Hereafter, each of these components in the pre-ionization electrode 90 may be referred to as the dielectric pipe 91, the inner electrode 93, the outer electrode 95, and the fourth end 95a.

[0082] The pre-ionization electrode 80 is located on the other side of electrode 133a in the X direction, that is, on the opposite side from the pre-ionization electrode 60. The pre-ionization electrode 90 is located on the other side of electrode 133b, that is, on the opposite side from the pre-ionization electrode 60, and facing the pre-ionization electrode 80. In Figure 13, the dielectric pipe 81, the third end 85a, and the portion of the outer electrode 85 that overlaps with the dielectric pipe 91, the fourth end 95a, and the outer electrode 95 are shown with dashed lines. The pre-ionization electrodes 80 and 90 are positioned downstream of the laser gas flowing in the X direction between electrodes 133a and 133b. In Figure 12, the flow of the laser gas is shown with thick arrows.

[0083] Dielectric pipe 81 is parallel to dielectric pipe 61, and dielectric pipe 91 is parallel to dielectric pipe 71. Therefore, the longitudinal directions of dielectric pipes 81 and 91 are tilted in opposite directions in the X direction with respect to the virtual axis 50, such that dielectric pipes 81 and 91 intersect each other when viewed along the Y direction. Figure 13 illustrates the central axes 81a and 91a of dielectric pipes 81 and 91 to facilitate understanding of this tilt. Consequently, the extending directions of the ends 85a and 95a are tilted in the same way as the extending directions of the ends 65a and 75a. Also, when viewed along the Y direction, the center of the third end 85a in the longitudinal direction of the outer electrode 85 coincides with the center of the fourth end 95a in the longitudinal direction of the outer electrode 95. Furthermore, the third end 85a is tilted counterclockwise with respect to the virtual axis 50 around the center of the third end 85a, and the fourth end 95a is tilted clockwise with respect to the virtual axis 50 around the center of the fourth end 95a. Therefore, when viewed along the Y direction, the distance from the virtual axis 50 to the third end 85a decreases from one end to the other in the Z direction. Also, when viewed along the Y direction, the distance from the virtual axis 50 to the fourth end 95a increases from one end to the other in the Z direction. Note that when viewed along the X direction, the third end 85a and the fourth end 95a are arranged parallel to each other.

[0084] When viewed along the Y direction, the extension direction of the third end 85a is inclined at a third angle θ3 with respect to the virtual axis 50, and the extension direction of the fourth end 95a is inclined at the same fourth angle θ4 as the third angle θ3, but in the opposite direction to the third end 85a with respect to the virtual axis 50. Therefore, the third end 85a is positioned symmetrically with respect to the fourth end 95a with respect to its center. Also, the extension direction of the third end 85a is inclined at the same angle as the extension direction of the fourth end 95a with respect to the virtual axis 50, but in the opposite direction to the extension direction of the fourth end 95a. The angles θ3 and θ4 are acute angles between 0.2 degrees and 3.0 degrees. As described above, dielectric pipe 81 is parallel to dielectric pipe 61, and dielectric pipe 91 is parallel to dielectric pipe 71. Therefore, the extension direction of the third end 85a is parallel to the extension direction of the first end 65a, and the extension direction of the fourth end 95a is parallel to the extension direction of the second end 75a. The third angle θ3 is the same as the first angle θ1, and the fourth angle θ4 is the same as the second angle θ2. The third end 85a may be positioned asymmetrically with respect to the fourth end 95a with respect to the center of the third end 85a, and angles θ3 and θ4 may be different from each other. Also, the third angle θ3 may be different from the first angle θ1, and the fourth angle θ4 may be different from the second angle θ2.

[0085] Furthermore, it is preferable that the third distance L3 in the X direction from the center of the third end 85a in the longitudinal direction of the external electrode 85 to the virtual axis 50 is the same as the fourth distance L4 in the X direction from the center of the fourth end 95a in the longitudinal direction of the external electrode 95 to the virtual axis 50. If the third distance L3 and the fourth distance L4 are different, it is preferable that one of them is 0.9 times or more and 1.1 times or less of the other. Also, it is preferable that the third distance L3 is the same as the first distance L1, and the fourth distance L4 is the same as the second distance L2.

[0086] In the above explanation, we used the ends 85a and 95a, but the dielectric pipes 81 and 91, the internal electrodes 83 and 93, and the external electrodes 85 and 95 are also tilted in the same way as the ends 85a and 95a.

[0087] In this embodiment, the electrode holder portion 137 is provided with a third spacer 87, which has the same configuration as the first spacer 67 and is fixed to the electrode 133a. Furthermore, the electrical insulation portion 135 is provided with a fourth spacer 97 on the side facing the internal space of the chamber 131, which has the same configuration as the second spacer 77 and is fixed to the electrode 133b. The external electrodes 85 and 95 are individually fixed to the spacers 87 and 97, respectively, in the same manner as the external electrodes 65 and 75 are fixed to the spacers 67 and 77. Therefore, the external electrode 85 is fixed to the electrode 133a via the third spacer 87, and the external electrode 95 is fixed to the electrode 133b via the fourth spacer 97. Note that the external electrode 85 may be directly fixed to the electrode 133a, and the external electrode 95 may be directly fixed to the electrode 133b.

[0088] Furthermore, the electrode holder portion 137 is provided with holders 29 and 30, which have the same configuration as holders 27 and 28. One end of the dielectric pipe 81 is inserted into the hole 29a on the electrode holder portion 137 side of holder 29, and one end of the dielectric pipe 91 is inserted into the hole 29b on the electrical insulation portion 135 side of holder 29. As a result, one end of the dielectric pipe 81 and one end of the dielectric pipe 91 are held by holder 29. The other end of the dielectric pipe 81 is inserted into a hole (not shown) on the electrode holder portion 137 side of holder 30, and the other end of the dielectric pipe 91 is inserted into a hole (not shown) on the electrical insulation portion 135 side of holder 30. As a result, the other end of the dielectric pipe 81 and the other end of the dielectric pipe 91 are held by holder 30.

[0089] One end of each of the internal electrodes 83 and 93 is electrically connected to each other by an internal electrode connector 33b having the same configuration as the internal electrode connector 33a. The other ends of each of the internal electrodes 83 and 93 may also be electrically connected to each other by the internal electrode connector 33b. The other end of the external electrode 85 is electrically connected to electrode 133a via electrode holder portion 137, and is also electrically connected to chamber 131 via electrode holder portion 137 and wiring 137a. The external electrode 85, electrode holder portion 137, wiring 137a, and chamber 131 are at ground potential. The other end of the external electrode 95 is electrically connected to electrode 133b.

[0090] Figure 14 is an electrical circuit diagram of the chamber 131 in this embodiment. When switch 143a is turned ON, the charge stored in the charging capacitor is transferred to the peaking capacitor 31a, and at the same time, the voltage between electrode 133a and electrode 133b increases. In addition, a voltage equal to half the voltage between electrode 133a and electrode 133b is induced in each of the internal electrodes 63, 73, 83, and 93. As a result, corona discharge occurs near dielectric pipe 61 and its first end 65a, near dielectric pipe 71 and its second end 75a, near dielectric pipe 81 and its third end 85a, and near dielectric pipe 91 and its fourth end 95a, and ultraviolet light is emitted from each of these locations. When ultraviolet light irradiates the laser gas between electrode 133a and electrode 133b, the laser gas between electrode 133a and electrode 133b is pre-ionized. Then, the main discharge between electrode 133a and electrode 133b occurs. As a result, an excimer is generated from the laser medium contained in the laser gas between electrode 133a and electrode 133b, and emits light when it dissociates.

[0091] 4.2 Action and Effects In the chamber 131 of this embodiment, the distance from the virtual axis 50 to the third end 85a decreases from one end to the other in the Z direction. Also, the distance from the virtual axis 50 to the fourth end 95a increases from one end to the other in the Z direction.

[0092] In this configuration, in the virtual axis 50, the pre-ionization intensity from the pre-ionization electrode 80, which increases from one end to the other in the Z direction, and the pre-ionization intensity from the pre-ionization electrode 90, which decreases from one end to the other in the Z direction, are further combined. As a result, the non-uniformity of the pre-ionization intensity in the virtual axis 50 can be further suppressed, and the decrease in the energy stability of the laser light emitted from the gas laser device 100 can be further suppressed.

[0093] Furthermore, in this chamber 131, the extension direction of the third end 85a is inclined in the opposite direction to the extension direction of the fourth end 95a at the same angle as the extension direction of the fourth end 95a with respect to the virtual axis 50, and the third distance L3 is the same as the fourth distance L4.

[0094] In this configuration, when viewed along the Y direction, the third end 85a and the fourth end 95a are arranged symmetrically with respect to their respective centers, and when viewed along the X direction, the third end 85a and the fourth end 95a are arranged parallel to each other. Therefore, non-uniformity of the pre-ionization intensity along the virtual axis 50 can be further suppressed, and the decrease in the energy stability of the laser light emitted from the gas laser device 100 can be further suppressed.

[0095] Furthermore, in this chamber 131, when viewed along the Y direction, the extension direction of the third end 85a is parallel to the extension direction of the first end 65a, and the extension direction of the fourth end 95a is parallel to the extension direction of the second end 75a.

[0096] With this configuration, non-uniformity of the pre-ionization intensity along the virtual axis 50 can be more suppressed compared to the case where the extending direction of the first end 65a is not parallel to the extending direction of the third end 85a. Also, non-uniformity of the pre-ionization intensity along the virtual axis 50 can be more suppressed compared to the case where the extending direction of the second end 75a is not parallel to the extending direction of the fourth end 95a. Therefore, the decrease in the stability of the energy of the laser light emitted from the gas laser device 100 can be more suppressed. Note that when viewed along the Y direction, the extending direction of the third end 85a may be not parallel to the extending direction of the first end 65a, and the extending direction of the fourth end 95a may also be not parallel to the extending direction of the second end 75a.

[0097] Figure 15 is a view of the area around the preliminary ionization electrodes 80 and 90 in a modified example of this embodiment, along the Z direction, and Figure 16 is a view of the area around the preliminary ionization electrodes 80 and 90 shown in Figure 15, along the X direction.

[0098] In this modified example, the direction of inclination of the ends 65a, 75a, 85a, and 95a differs from that of Embodiment 2. Note that the direction of inclination of the ends 65a and 75a in this modified example is the same as that of the modified example in Embodiment 1, so a detailed explanation is omitted.

[0099] First, in this modified example, when viewed along the Y direction, the dielectric pipe 81, the outer electrode 85, and the third end 85a overlap with the dielectric pipe 91, the outer electrode 95, and the fourth end 95a, and are not misaligned with them. Also, in this modified example, the extending directions of the third end 85a and the fourth end 95a are inclined in the same direction in the Y direction with respect to the virtual axis 50 when viewed along the X direction. Specifically, the third end 85a approaches the virtual axis 50 from one end to the other in the Z direction, and the fourth end 95a moves away from the virtual axis 50 from one end to the other in the Z direction. The extending direction of the third end 85a is parallel to the extending direction of the fourth end 95a. Therefore, the distance from the virtual axis 50 to the third end 85a decreases from one end to the other in the Z direction. Furthermore, the distance from the virtual axis 50 to the fourth end 95a increases from one end to the other in the Z direction. Also, when viewed along the X direction, the extension direction of the third end 85a and the extension direction of the first end 65a are tilted in opposite directions in the Y direction with respect to the virtual axis 50, such that the third end 85a intersects the first end 65a. Also, the extension direction of the fourth end 95a and the extension direction of the second end 75a are tilted in opposite directions in the Y direction with respect to the virtual axis 50, such that the fourth end 95a intersects the second end 75a.

[0100] In this modified example, when viewed along the X direction, the extension direction of the first end 65a is parallel to the extension direction of the second end 75a, and the extension direction of the third end 85a is parallel to the extension direction of the fourth end 95a. With this configuration, non-uniformity of the pre-ionization intensity in the virtual axis 50 can be further suppressed compared to the case where the extension direction of the first end 65a is not parallel to the extension direction of the second end 75a, and the extension direction of the third end 85a is not parallel to the extension direction of the fourth end 95a. Therefore, the decrease in the energy stability of the laser light emitted from the gas laser device 100 can be further suppressed. Note that when viewed along the X direction, the extension direction of the third end 85a may be not parallel to the extension direction of the fourth end 95a. Also, when viewed along the Y direction, the extension direction of the third end 85a may be offset from the extension direction of the fourth end 95a.

[0101] The above description is intended to be illustrative and not restrictive. It will therefore be apparent to those skilled in the art that modifications can be made to the embodiments of this disclosure without departing from the claims. It will also be apparent to those skilled in the art that the embodiments of this disclosure can be used in combination. Terms used in this specification and throughout the claims should be interpreted as "non-limiting" unless otherwise specified. For example, terms such as "includes," "have," "equip," and "possess" should be interpreted as "not excluding the existence of components other than those described." Also, the modifier "one" should be interpreted as "at least one" or "one or more." Furthermore, 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 of these with anything other than "A," "B," and "C."

Claims

1. A chamber for a gas laser device that seals laser gas in its internal space, A first main electrode and a second main electrode are provided in the internal space, facing each other at a distance from each other along a predetermined direction in which the longitudinal direction is the direction of propagation of the laser light, and generating light from the laser gas by an applied voltage, A window is provided on the wall surface of the chamber, through which the light is transmitted, A first pre-ionization electrode is provided on one side in a direction perpendicular to both the predetermined direction of the first main electrode and the direction in which the first main electrode and the second main electrode are aligned, A second pre-ionization electrode is provided on one side of the second main electrode, facing the first pre-ionization electrode, Equipped with, The first pre-ionization electrode comprises a first dielectric pipe, a first pre-ionization internal electrode disposed inside the first dielectric pipe and extending along the longitudinal direction of the first dielectric pipe, and a first pre-ionization external electrode extending along the longitudinal direction of the first dielectric pipe and including a first end facing the first dielectric pipe. The second pre-ionization electrode includes a second dielectric pipe, a second pre-ionization internal electrode disposed inside the second dielectric pipe and extending along the longitudinal direction of the second dielectric pipe, and a second pre-ionization external electrode extending along the longitudinal direction of the second dielectric pipe and including a second end facing the second dielectric pipe. The distance from the virtual axis extending along the predetermined direction between the first main electrode and the second main electrode to the first end increases from one side to the other in the predetermined direction. The distance from the virtual axis to the second end decreases from one side to the other side in the predetermined direction. The longitudinal directions of the first dielectric pipe and the first pre-ionization electrode, as well as the longitudinal directions of the second dielectric pipe and the second pre-ionization electrode, are inclined with respect to the virtual axis. Chamber of a gas laser device.

2. A chamber for a gas laser apparatus according to claim 1, The first pre-ionization electrode and the second pre-ionization electrode are positioned upstream of the laser gas flowing between the first main electrode and the second main electrode.

3. A chamber for a gas laser apparatus according to claim 1, The first pre-ionization electrode is electrically connected to the second pre-ionization electrode. The first pre-ionization electrode is electrically connected to the first main electrode, The second pre-ionization electrode is electrically connected to the second main electrode.

4. A chamber for a gas laser apparatus according to claim 1, The first pre-ionization electrode is fixed to the first main electrode via a first spacer. The second auxiliary ionization electrode is fixed to the second main electrode via a second spacer.

5. A chamber for a gas laser apparatus according to claim 1, The extending directions of the first end and the extending directions of the second end are inclined in opposite directions with respect to the virtual axis such that the first end and the second end intersect each other when viewed along the direction in which the first and second main electrodes are aligned.

6. A chamber for a gas laser apparatus according to claim 5, The extending direction of the first end is inclined with respect to the virtual axis at the same angle as the extending direction of the second end, but in the opposite direction to the extending direction of the second end. The first distance from the center of the first end of the first pre-ionization electrode in the longitudinal direction to the virtual axis is the same as the second distance from the center of the second end of the second pre-ionization electrode in the longitudinal direction to the virtual axis.

7. A chamber for a gas laser apparatus according to claim 6, The repetition frequency of the aforementioned light is 2 kHz or higher.

8. A chamber for a gas laser apparatus according to claim 1, When viewed along a direction perpendicular to the predetermined direction and the alignment direction of the first and second main electrodes, the extending direction of the first end and the extending direction of the second end are inclined in the same direction with respect to the virtual axis in the alignment direction of the first and second main electrodes.

9. A chamber for a gas laser apparatus according to claim 8, The repetition frequency of the aforementioned light is 2 kHz or higher.

10. A chamber for a gas laser apparatus according to claim 1, A third pre-ionization electrode is provided on the other side of the first main electrode, opposite to the one side on which the first pre-ionization electrode is provided, A fourth pre-ionization electrode is provided on the other side of the second main electrode, facing the third pre-ionization electrode, Furthermore, The third pre-ionization electrode comprises a third dielectric pipe, a third pre-ionization internal electrode disposed inside the third dielectric pipe and extending along the longitudinal direction of the third dielectric pipe, and a third pre-ionization external electrode extending along the longitudinal direction of the third dielectric pipe and including a third end facing the third dielectric pipe. The fourth pre-ionization electrode comprises a fourth dielectric pipe, a fourth pre-ionization internal electrode disposed inside the fourth dielectric pipe and extending along the longitudinal direction of the fourth dielectric pipe, and a fourth pre-ionization external electrode extending along the longitudinal direction of the fourth dielectric pipe and including a fourth end facing the fourth dielectric pipe. The distance from the virtual axis to the third end decreases from one side to the other in the predetermined direction. The distance from the virtual axis to the fourth end increases from one side to the other in the predetermined direction. The longitudinal directions of the third dielectric pipe and the third preliminary ionization electrode, as well as the longitudinal directions of the fourth dielectric pipe and the fourth preliminary ionization electrode, are inclined with respect to the virtual axis.

11. A chamber for a gas laser apparatus according to claim 10, The third pre-ionization electrode is electrically connected to the fourth pre-ionization electrode. The third auxiliary ionization electrode is electrically connected to the first main electrode, The fourth auxiliary ionization electrode is electrically connected to the second main electrode.

12. A chamber for a gas laser apparatus according to claim 10, The third auxiliary ionization electrode is fixed to the first main electrode via a third spacer. The fourth auxiliary ionization electrode is fixed to the second main electrode via a fourth spacer.

13. A chamber for a gas laser apparatus according to claim 10, The extending directions of the third end and the fourth end are inclined in opposite directions with respect to the virtual axis such that the third end and the fourth end intersect each other when viewed along the direction in which the first and second main electrodes are aligned.

14. A chamber for a gas laser apparatus according to claim 13, The extension direction of the third end is inclined with respect to the virtual axis at the same angle as the extension direction of the fourth end, but in the opposite direction to the extension direction of the fourth end. The third distance from the center of the third end of the third pre-ionization electrode in the longitudinal direction to the virtual axis is the same as the fourth distance from the center of the fourth end of the fourth pre-ionization electrode in the longitudinal direction to the virtual axis.

15. A chamber for a gas laser apparatus according to claim 14, The aforementioned angle is between 0.2 degrees and 3.0 degrees.

16. A chamber for a gas laser apparatus according to claim 14, The extension direction of the third end is parallel to the extension direction of the first end. The extension direction of the fourth end is parallel to the extension direction of the second end.

17. A chamber for a gas laser apparatus according to claim 10, When viewed along a direction perpendicular to the predetermined direction and the alignment direction of the first and second main electrodes, the extending direction of the third end and the extending direction of the fourth end are inclined in the same direction with respect to the virtual axis in the alignment direction of the first and second main electrodes.

18. A chamber for a gas laser apparatus according to claim 17, When viewed along a direction perpendicular to the predetermined direction and the alignment direction of the first and second main electrodes, the extending direction of the first and second ends is in the same orientation with respect to the virtual axis in the alignment direction of the first and second main electrodes, but is inclined in the opposite direction to the extending direction of the third and fourth ends.

19. A chamber for a gas laser apparatus according to claim 17, The extension direction of the first end is parallel to the extension direction of the second end. The extension direction of the third end is parallel to the extension direction of the fourth end.

20. A method for manufacturing an electronic device, Optical resonators and, A chamber is placed in the optical path of the optical resonator and seals laser gas in its internal space, A first main electrode and a second main electrode are provided in the internal space, facing each other at a distance from each other along a predetermined direction in which the longitudinal direction is the direction of propagation of the laser light, and generating light from the laser gas by an applied voltage, A window is provided on the wall surface of the chamber, through which the light is transmitted, A first pre-ionization electrode is provided on one side in a direction perpendicular to both the predetermined direction of the first main electrode and the direction in which the first main electrode and the second main electrode are aligned, A second pre-ionization electrode is provided on one side of the second main electrode, facing the first pre-ionization electrode, Equipped with, The first pre-ionization electrode comprises a first dielectric pipe, a first pre-ionization internal electrode disposed inside the first dielectric pipe and extending along the longitudinal direction of the first dielectric pipe, and a first pre-ionization external electrode extending along the longitudinal direction of the first dielectric pipe and including a first end facing the first dielectric pipe. The second pre-ionization electrode includes a second dielectric pipe, a second pre-ionization internal electrode disposed inside the second dielectric pipe and extending along the longitudinal direction of the second dielectric pipe, and a second pre-ionization external electrode extending along the longitudinal direction of the second dielectric pipe and including a second end facing the second dielectric pipe. The distance from the virtual axis extending along the predetermined direction between the first main electrode and the second main electrode to the first end increases from one side to the other in the predetermined direction. The distance from the virtual axis to the second end decreases from one side to the other side in the predetermined direction. The longitudinal directions of the first dielectric pipe and the first pre-ionization electrode, as well as the longitudinal directions of the second dielectric pipe and the second pre-ionization electrode, are inclined with respect to the virtual axis. A gas laser device generates laser light, The laser light is output to the exposure apparatus, To manufacture the aforementioned electronic device, the laser light is exposed onto the photosensitive substrate within the exposure apparatus. A method for manufacturing electronic devices including

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