Extreme ultraviolet light generating apparatus and method for manufacturing electronic devices

Abstract

To provide an extreme ultraviolet light generation apparatus capable of suppressing a decrease in reliability.SOLUTION: An extreme ultraviolet light generation apparatus may include: a chamber; a housing extending from the internal space to outside of the chamber, surrounding the plasma generation region except on a trajectory of the droplet target at the internal space and on an optical path of the laser light to the plasma generation region at the internal space, and including a first opening through which extreme ultraviolet light generated from the plasma passes; a light concentrating mirror arranged in a first space outside the housing at the internal space and configured to reflect the extreme ultraviolet light having passed through the first opening in a direction different from an incident direction of the extreme ultraviolet light; a gas supply port provided in the chamber and configured to supply a gas from outside of the chamber to the first space; and a gas exhaust port provided at the housing outside the chamber and configured to exhaust the gas flowing from the first space to a second space inside of the housing through the first opening to the outside of the chamber, wherein an optical axis of the laser light when being radiated to the droplet target may be along a direction in which the gas flows in the plasma generation region.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to an extreme ultraviolet light generating device and a method for manufacturing an electronic device.

Background Art

[0002] In recent years, with the miniaturization of semiconductor processes, the miniaturization of transfer patterns in optical lithography of semiconductor processes has been rapidly progressing. In the next generation, microfabrication of 10 nm or less will be required. For this reason, development of a semiconductor exposure apparatus combining a device for generating extreme ultraviolet (EUV) light with a wavelength of about 13 nm and a reduction projection reflective optical system has been expected.

[0003] As an EUV light generating device, development of a Laser Produced Plasma (LPP) type device using plasma generated by irradiating a target material with laser light has been progressing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] An extreme ultraviolet light generation apparatus according to one aspect of the present disclosure includes: a chamber with an internal space containing a plasma generation region in which plasma is generated from a droplet target irradiated with laser light; a housing extending from the internal space to the outside of the chamber, surrounding the plasma generation region except on the trajectory of the droplet target in the internal space and on the optical path of the laser light to the plasma generation region in the internal space, and including a first aperture through which extreme ultraviolet light generated from the plasma passes; a focusing mirror disposed in the first space outside the housing in the internal space, which reflects the extreme ultraviolet light that has passed through the first aperture in a direction different from the incident direction of the extreme ultraviolet light; a gas supply port provided in the chamber for supplying gas from outside the chamber to the first space; and a gas exhaust port provided in the housing outside the chamber for exhausting gas flowing from the first space through the first aperture to the second space inside the housing to the outside of the chamber, wherein the optical axis of the laser light irradiated onto the droplet target may be aligned with the direction in which the gas flows in the plasma generation region.

[0006] An extreme ultraviolet light generation apparatus according to another aspect of the present disclosure comprises a chamber including a plasma generation region in its internal space, a target supply unit for supplying a droplet target to the plasma generation region, a laser device for irradiating a droplet target with laser light so that plasma is generated from the droplet target in the plasma generation region, and a control unit, wherein the chamber includes a housing extending from the internal space to the outside of the chamber, surrounding the plasma generation region except on the optical path of the laser light to the plasma generation region in the internal space, and including a first aperture through which extreme ultraviolet light generated from the plasma passes, a droplet supply aperture through which a droplet target supplied from the target supply unit to the plasma generation region passes, and a droplet discharge aperture through which the droplet target that has passed through the plasma generation region passes, and a first space in the internal space between the chamber and the housing, which directs the extreme ultraviolet light that has passed through the first aperture in a direction different from the incident direction of the extreme ultraviolet light. The system includes a focusing mirror with a rotating ellipsoidal reflective surface that reflects light in a certain direction; a gas supply port provided in the chamber for supplying gas from outside the chamber to a first space; a gas exhaust port provided in the housing, located outside the chamber, for exhausting gas flowing from the first space to a second space inside the housing through a first opening to the outside of the chamber; a target supply pipe arranged in the first space and surrounding the trajectory of a droplet target supplied from a target supply unit; a target gas supply port provided in the target supply pipe for supplying gas to the plasma generation region through the target supply pipe and the droplet supply opening; an illumination unit for irradiating illumination light onto the droplet target supplied from the target supply unit to the plasma generation region; and a light receiving unit for receiving the illumination light. The control unit may receive a signal related to the timing of the droplet target's passage from the light receiving unit that has received the illumination light, and output a light emission trigger signal to the laser device that is delayed by a predetermined time relative to the signal.

[0007] Furthermore, a method for manufacturing an electronic device according to one aspect of the present disclosure includes: a chamber with an internal space containing a plasma generation region in which plasma is generated from a droplet target irradiated with laser light; a housing extending from the internal space to the outside of the chamber, surrounding the plasma generation region except on the trajectory of the droplet target in the internal space and on the optical path of the laser light to the plasma generation region in the internal space, and including a first aperture through which extreme ultraviolet light generated from the plasma passes; and a first space located outside the housing in the internal space, which allows the extreme ultraviolet light that has passed through the first aperture to be directed in a direction different from the incident direction of the extreme ultraviolet light. The apparatus includes a focusing mirror that reflects light in a certain direction, a gas supply port provided in the chamber for supplying gas from outside the chamber to a first space, and a gas exhaust port provided in the housing outside the chamber for exhausting gas flowing from the first space through a first opening to a second space inside the housing to the outside of the chamber, wherein the optical axis of the laser beam when irradiated onto the droplet target is aligned with the direction in which the gas flows in the plasma generation region. The apparatus may also include outputting extreme ultraviolet light generated by an extreme ultraviolet light generator to an exposure apparatus and exposing a photosensitive substrate to extreme ultraviolet light in the exposure apparatus in order to manufacture an electronic device.

[0008] Furthermore, a method for manufacturing an electronic device according to another aspect of the present disclosure includes: a chamber with an internal space containing a plasma generation region in which plasma is generated from a droplet target irradiated with laser light; a housing extending from the internal space to the outside of the chamber, surrounding the plasma generation region except on the trajectory of the droplet target in the internal space and on the optical path of the laser light to the plasma generation region in the internal space, and including a first aperture through which extreme ultraviolet light generated from the plasma passes; and a focusing system disposed in the first space outside the housing in the internal space, which reflects the extreme ultraviolet light that has passed through the first aperture in a direction different from the incident direction of the extreme ultraviolet light. The apparatus includes a mirror, a gas supply port provided in the chamber for supplying gas from outside the chamber to a first space, and a gas exhaust port provided in the housing outside the chamber for exhausting gas flowing from the first space through a first opening to a second space inside the housing to the outside of the chamber, wherein the optical axis of the laser beam irradiated onto the droplet target is aligned with the direction of gas flow in the plasma generation region. The apparatus may also include irradiating a mask with extreme ultraviolet light generated by an extreme ultraviolet light generator to inspect for defects in the mask, selecting a mask based on the inspection results, and exposing and transferring the pattern formed on the selected mask onto a photosensitive substrate. [Brief explanation of the drawing]

[0009] 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 an electronic device manufacturing apparatus, different from the one shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram showing an example of the overall configuration of a comparative example of an extreme ultraviolet light generation device. [Figure 4] Figure 4 is a cross-sectional view of the chamber perpendicular to the trajectory of the droplet target in the comparative example. [Figure 5] Figure 5 is a cross-sectional view perpendicular to the optical axis of the laser beam when irradiating the droplet target. [Figure 6] Figure 6 shows the change in the intensity of EUV light generated immediately after irradiating a droplet target with a shifted laser beam position. [Figure 7] Figure 7 is a cross-sectional view of the chamber perpendicular to the trajectory of the droplet target in Embodiment 1. [Figure 8] Figure 8 is a cross-sectional view of the chamber perpendicular to the trajectory of the droplet target in Embodiment 2. [Figure 9] Figure 9 is a cross-sectional view of the chamber perpendicular to the trajectory of the droplet target in Embodiment 3. [Figure 10] Figure 10 is a cross-sectional view of the chamber perpendicular to the trajectory of the droplet target in Modification 1 of Embodiment 3. [Figure 11] Figure 11 is a cross-sectional view of the chamber perpendicular to the trajectory of the droplet target in a modified example 2 of Embodiment 3. [Figure 12] Figure 12 is a cross-sectional view perpendicular to the optical axis of the laser beam when irradiating the droplet target in Embodiment 4. [Figure 13] Figure 13 is a cross-sectional view of the chamber perpendicular to the trajectory of the droplet target in Embodiment 4. Embodiment

[0010] 1. Overview 2. Description of manufacturing equipment for electronic devices 3. Description of the comparative example extreme ultraviolet light generator 3.1 Configuration 3.2 Operation 3.3 Challenges 4. Description of the extreme ultraviolet light generating device of Embodiment 1 4.1 Configuration 4.2 Action and Effects 5. Description of the extreme ultraviolet light generation device of Embodiment 2 5.1 Configuration 5.2 Action and Effects 6. Description of the extreme ultraviolet light generating device of Embodiment 3 6.1 Configuration 6.2 Operation 6.3 Effects Description of the extreme ultraviolet light generating device of Embodiment 4 7.1 Configuration 7.2 Operation 7.3 Effects

[0011] 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 redundant descriptions are omitted.

[0012] 1. Overview Embodiments of the present disclosure relate to an extreme ultraviolet light generating device that generates light having a wavelength called extreme ultraviolet (EUV), and a manufacturing device for electronic devices. Hereinafter, extreme ultraviolet light may be referred to as EUV light in some cases.

[0013] 2. Description of the manufacturing device for electronic devices Figure 1 is a schematic diagram showing an example of the overall configuration of an electronic device manufacturing apparatus. The electronic device manufacturing apparatus shown in Figure 1 includes an EUV light generator 100 and an exposure apparatus 200. The exposure apparatus 200 includes a mask irradiation unit 210 which includes a plurality of mirrors 211, 212 which are reflective optical systems, and a workpiece irradiation unit 220 which includes a plurality of mirrors 221, 222 which are reflective optical systems separate from those of the mask irradiation unit 210. The mask irradiation unit 210 illuminates the mask pattern on the mask table MT via the mirrors 211, 212 with EUV light 101 incident from the EUV light generator 100. The workpiece irradiation unit 220 images the EUV light 101 reflected by the mask table MT onto a workpiece (not shown) placed on the workpiece table WT via the mirrors 221, 222. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure apparatus 200 exposes the workpiece to EUV light 101 reflecting the mask pattern by synchronously moving the mask table MT and the workpiece table WT in parallel. By transferring the device pattern to the semiconductor wafer through this exposure process, a semiconductor device can be manufactured.

[0014] Figure 2 is a schematic diagram showing an example of the overall configuration of an electronic device manufacturing apparatus different from the one shown in Figure 1. The electronic device manufacturing apparatus shown in Figure 2 includes an EUV light generator 100 and an inspection apparatus 300. The inspection apparatus 300 includes an illumination optical system 310 which includes a plurality of mirrors 311, 313, and 315 which are reflective optical systems, and a detection optical system 320 which includes a plurality of mirrors 321, 323 which are reflective optical systems separate from the illumination optical system 310, and a detector 325. The illumination optical system 310 reflects the EUV light 101 incident from the EUV light generator 100 with the mirrors 311, 313, and 315 to irradiate a mask 333 placed on a mask stage 331. The mask 333 includes mask blanks before a pattern is formed. The detection optical system 320 reflects the EUV light 101 reflecting the pattern from the mask 333 with the mirrors 321 and 323 to form an image on the light-receiving surface of the detector 325. The detector 325, which receives EUV light 101, acquires an image of the mask 333. The detector 325 is, for example, a TDI (Time Delay Integration) camera. The image of the mask 333 acquired through the above process is used to inspect for defects in the mask 333, and the results of the inspection are used to select a mask suitable for the manufacture of an electronic device. Then, the pattern formed on the selected mask is exposed and transferred onto a photosensitive substrate using the exposure apparatus 200 to manufacture the electronic device.

[0015] 3. Description of the comparative example extreme ultraviolet light generator 3.1 Configuration A comparative example of the EUV light generation apparatus 100 will now be described. Note that the comparative examples in this disclosure are forms that the applicant recognizes as being known only to the applicant, and are not publicly known examples acknowledged by the applicant. Furthermore, the following description will use an EUV light generation apparatus 100 that emits EUV light 101 toward an exposure apparatus 200 as an external device, as shown in Figure 1. Note that similar effects and benefits can be obtained with an EUV light generation apparatus 100 that emits EUV light 101 toward an inspection apparatus 300 as an external device, as shown in Figure 2.

[0016] Figure 3 is a schematic diagram showing an example of the overall configuration of the EUV light generator 100 in this example. As shown in Figure 3, the EUV light generator 100 mainly includes a chamber 10, a laser device LD, a processor 120, and a laser light delivery optical system 30.

[0017] Chamber 10 is a sealable container. Chamber 10 includes an inner wall 10b enclosing an internal space with a low-pressure atmosphere. Chamber 10 also includes a sub-chamber 15, to which a target supply unit 40 is mounted so as to penetrate the wall of the sub-chamber 15. The target supply unit 40 includes a tank 41, a nozzle 42, and a pressure regulator 43, and supplies droplet targets DL to the internal space of Chamber 10. Droplet targets DL may be abbreviated as droplets or targets.

[0018] Tank 41 stores a target substance, which will become a droplet target DL, inside. The target substance contains tin. The inside of Tank 41 is in communication with a pressure regulator 43 that regulates the pressure inside Tank 41. A heater 44 and a temperature sensor 45 are attached to Tank 41. The heater 44 heats Tank 41 with an electric current supplied from a heater power supply 46. This heating melts the target substance inside Tank 41. The temperature sensor 45 measures the temperature of the target substance inside Tank 41 via Tank 41. The pressure regulator 43, temperature sensor 45, and heater power supply 46 are electrically connected to the processor 120.

[0019] The nozzle 42 is attached to the tank 41 and dispenses the target substance. A piezoelectric element 47 is attached to the nozzle 42. The piezoelectric element 47 is electrically connected to a piezoelectric power supply 48 and is driven by the voltage applied from the piezoelectric power supply 48. The piezoelectric power supply 48 is electrically connected to the processor 120. The operation of the piezoelectric element 47 causes the target substance dispensed from the nozzle 42 to become a droplet target DL.

[0020] The chamber 10 includes a target recovery unit 14. The target recovery unit 14 is a box-shaped body attached to the inner wall 10b of the chamber 10 and communicates with the internal space of the chamber 10 through an opening 10a provided in the inner wall 10b of the chamber 10. The opening 10a is located directly below the nozzle 42, and the target recovery unit 14 is a drain tank that recovers unwanted droplet targets DL that pass through the opening 10a and reach the target recovery unit 14.

[0021] At least one through-hole is provided in the inner wall 10b of the chamber 10. This through-hole is blocked by a window 12, and pulsed laser light 90 emitted from the laser device LD passes through the window 12.

[0022] Furthermore, a laser focusing optical system 13 is arranged in the internal space of the chamber 10. The laser focusing optical system 13 includes a laser beam focusing mirror 13A and a high-reflection mirror 13B. The laser beam focusing mirror 13A reflects and focuses the laser beam 90 that passes through the window 12. The high-reflection mirror 13B reflects the laser beam 90 that is focused by the laser beam focusing mirror 13A. The positions of the laser beam focusing mirror 13A and the high-reflection mirror 13B are adjusted by the laser beam manipulator 13C so that the focusing position of the laser beam 90 in the internal space of the chamber 10 is a position specified by the processor 120. This focusing position is adjusted to be located directly below the nozzle 42, and when the laser beam 90 irradiates the target material at this focusing position, plasma is generated by the irradiation, and EUV light 101 is emitted from the plasma. The region where plasma is generated is sometimes called the plasma generation region AR. The plasma generation region AR is a region with a radius of, for example, 40 mm centered on the plasma point, and is located in the internal space of the chamber 10.

[0023] An EUV light focusing mirror 75, including, for example, a spheroidal reflecting surface 75a, is positioned within the internal space of the chamber 10. The EUV light focusing mirror 75 is positioned in the internal space of the chamber 10 so as not to overlap with the laser beam 90. The reflecting surface 75a reflects the EUV light 101 emitted from the plasma in the plasma generation region AR. The reflecting surface 75a includes a first focal point and a second focal point. The reflecting surface 75a may be positioned, for example, such that the first focal point is located in the plasma generation region AR and the second focal point is located in the intermediate focal point IF. In Figure 3, a straight line passing through the first and second focal points is shown as the focal line L0.

[0024] Furthermore, the EUV light generator 100 includes a connecting section 19 that connects the internal space of the chamber 10 and the internal space of the exposure apparatus 200. Inside the connecting section 19, there is a wall with an aperture formed therein. Preferably, this wall is positioned so that the aperture is located at the second focal point. The connecting section 19 is the outlet for the EUV light 101 in the EUV light generator 100, and the EUV light 101 is emitted from the connecting section 19 and incident on the exposure apparatus 200.

[0025] The EUV light generator 100 also includes a pressure sensor 26 and a detection unit 27 as a target sensor. The pressure sensor 26 and the detection unit 27 are mounted on the chamber 10 and electrically connected to the processor 120. The pressure sensor 26 measures the pressure in the internal space of the chamber 10 and outputs a signal indicating this pressure to the processor 120.

[0026] The detection unit 27 includes, for example, an imaging function and detects the presence, trajectory, position, flow velocity, etc., of the droplet target DL ejected from the nozzle hole of the nozzle 42 in accordance with instructions from the processor 120. The detection unit 27 may be located inside the chamber 10, or it may be located outside the chamber 10 and detect the droplet target DL through a window (not shown) provided in the wall of the chamber 10. The detection unit 27 includes a light-receiving optical system (not shown) and an imaging unit (not shown), such as a CCD (Charge-Coupled Device) or photodiode. The light-receiving optical system forms an image of the droplet target DL's trajectory and surrounding area on the light-receiving surface of the imaging unit in order to improve the detection accuracy of the droplet target DL. When the droplet target DL passes through a light-collecting area of ​​the detection unit 27 provided by a light source (not shown) arranged to improve the contrast within the field of view of the detection unit 27, the imaging unit detects the trajectory of the droplet target DL and the change in light passing around it. The imaging unit converts the detected change in light into an electrical signal as a signal relating to the image data of the droplet target DL. The imaging unit outputs this electrical signal to the processor 120.

[0027] The laser device LD includes a master oscillator, which is a burst-operating light source. The master oscillator emits pulsed laser light 90 when burst-on. The master oscillator is a laser device that emits laser light 90 by exciting a gas, such as helium or nitrogen mixed in carbon dioxide, through an electrical discharge. Alternatively, the master oscillator may be a quantum cascade laser device. The master oscillator may also emit pulsed laser light 90 using a Q-switching method. Furthermore, the master oscillator may include an optical switch or a polarizer. Burst operation refers to the operation of emitting continuous pulsed laser light 90 at a predetermined repetition frequency when burst-on, and suppressing the emission of laser light 90 when burst-off.

[0028] The direction of propagation of the laser beam 90 emitted from the laser device LD is adjusted by the laser beam delivery optical system 30. The laser beam delivery optical system 30 includes a plurality of mirrors 31, 32 that adjust the direction of propagation of the laser beam 90. The position of at least one of the mirrors 31, 32 is adjusted by an actuator (not shown). By adjusting the position of at least one of the mirrors 31, 32, the laser beam 90 can be properly propagated from the window 12 into the internal space of the chamber 10.

[0029] The processor 120 of this disclosure is a processing unit that includes a storage device storing a control program and a CPU (Central Processing Unit) that executes the control program. The processor 120 is specially configured or programmed to perform various processes included in this disclosure and controls the entire EUV light generation apparatus 100. The processor 120 receives signals related to the pressure in the internal space of the chamber 10 measured by the pressure sensor 26, signals related to image data of the droplet target DL captured by the detection unit 27, and burst signals from the exposure apparatus 200 that instruct burst operation. The processor 120 processes the above various signals and may control, for example, the timing at which the droplet target DL is ejected and the ejection direction of the droplet target DL. The processor 120 may also control the emission timing of the laser device LD, the direction of propagation and focusing position of the laser beam 90, and so on. The various controls described above are merely examples, and other controls may be added as needed, as described later.

[0030] Figure 4 is a cross-sectional view of the chamber 10 perpendicular to the trajectory of the droplet target DL in the comparative example, and Figure 5 is a cross-sectional view perpendicular to the optical axis of the laser beam 90 when irradiating the droplet target DL. In Figure 4, for the sake of simplicity, the laser beam focusing mirror 13A and the high-reflection mirror 13B are omitted, and the propagation path of the laser beam 90 from the window 12 to the plasma generation region AR is simply illustrated.

[0031] The EUV light generator 100 includes a housing 500 positioned within the internal space of the chamber 10. In Figures 4 and 5, the space outside the housing 500 within the internal space of the chamber 10 is shown as the first space 11a, and the space inside the housing 500 is shown as the second space 11b. Note that the housing 500 is not shown in Figure 3.

[0032] The housing 500 is made of, for example, stainless steel or metallic molybdenum. The housing 500 surrounds the plasma generation region AR, which is located in the second space 11b. The housing 500 extends linearly from the internal space of the chamber 10 through the inner wall 10b of the chamber 10 to the external space of the chamber 10. A first opening 501 is provided at one end of the housing 500 located inside the chamber 10, and a gas exhaust port 503 is provided at the other end of the housing 500 located outside the chamber 10.

[0033] EUV light 101 generated from the plasma in the plasma generation region AR passes through the first aperture 501 from the second space 11b toward the first space 11a. The EUV light 101 then travels to the EUV light focusing mirror 75 located in the first space 11a. The EUV light focusing mirror 75 reflects the EUV light 101 toward an intermediate focusing point IF located in a direction different from the incident direction of the EUV light 101. In Figures 4 and 5, the EUV light 101 reflected by the EUV light focusing mirror 75 is omitted for clarity. The first aperture 501 faces the gas exhaust port 503, and the plasma generation region AR is located between the first aperture 501 and the gas exhaust port 503. The gas exhaust port 503 is connected to a first exhaust system 531, which includes an exhaust pump.

[0034] The housing 500 also includes a second aperture 505, a droplet supply aperture 507, and a droplet discharge aperture 509. The second aperture 505 is located on the optical path of the laser beam 90 to the plasma generation region AR in the internal space of the chamber 10 and faces the plasma generation region AR. The laser beam 90 passes through the second aperture 505 from the first space 11a toward the plasma generation region AR. The droplet supply aperture 507 and the droplet discharge aperture 509 are located on the trajectory of the droplet target DL and face each other. The droplet target DL supplied from the target supply unit 40 to the plasma generation region AR passes through the droplet supply aperture 507. The droplet target DL that has passed through the plasma generation region AR passes through the droplet discharge aperture 509, and the droplet discharge aperture 509 faces the aperture 10a connected to the target recovery unit 14. In this manner, the housing 500 surrounds the plasma generation region AR, except on the trajectory of the droplet target DL within the internal space of the chamber 10 and on the optical path of the laser beam 90 to the plasma generation region AR within the internal space.

[0035] A gas supply port 601a is provided on the inner wall 10b of the chamber 10, and the gas piping 601b of the first gas supply device 601 is connected to the gas supply port 601a. ​​The first gas supply device 601 and the gas piping 601b are located outside the chamber 10. The first gas supply device 601 is controlled by a processor 120. A supply gas flow rate adjustment unit (not shown), which is a valve, may be provided in the gas piping 601b. The first gas supply device 601 supplies etching gas to the gas piping 601b, and the gas supply port 601a to which the gas piping 601b is connected supplies etching gas to the first space 11a. In Figures 4 and 5, the flow of etching gas in the gas piping 601b is indicated by arrow F1. The flow rate of etching gas flowing from the gas supply port 601a into the first space 11a is, for example, 40 nm or more and 60 nm or less. nlm represents the volume of etching gas flowing per minute, converted to 0°C and 1 atmosphere. The etching gas flowing into the first space 11a flows into the second space 11b through the first opening 501, the second opening 505, the droplet supply opening 507, and the droplet discharge opening 509. In Figures 4 and 5, the flow of etching gas flowing into the second space 11b from each is indicated by arrow F2.

[0036] As described above, since the target material contains tin, the etching gas is a hydrogen-containing gas that can be considered to have a hydrogen gas concentration of 100%, for example. Alternatively, the etching gas may be a balance gas with a hydrogen gas concentration of about 3%, for example. The balance gas contains nitrogen (N2) gas and argon (Ar) gas. When the target material is irradiated with laser light 90 in the plasma generation region AR and turned into plasma, tin nanoparticles and charged tin particles are generated. The tin constituting these nanoparticles and charged particles reacts with hydrogen contained in the etching gas supplied to the second space 11b of the chamber 10. When tin reacts with hydrogen, it becomes stannane (SnH4), which is a gas at room temperature. Also, when the target material is turned into plasma in the plasma generation region AR, residual gas is generated in the second space 11b as exhaust gas. The residual gas contains tin nanoparticles and charged particles generated by the plasmaification of the target material, stannane formed when they react with the etching gas, and unreacted etching gas. Note that some of the charged particles are neutralized in the second space 11b, and these neutralized charged particles are also included in the residual gas. The gas exhaust port 503 exhausts the etching gas that has flowed from the first space 11a to the second space 11b through the first opening 501, the second opening 505, the droplet supply opening 507, and the droplet discharge opening 509, along with the residual gas, to the outside of the chamber 10. Specifically, the gas exhaust port 503 exhausts the etching gas and residual gas to the first exhaust device 531 by suction of the first exhaust device 531. Hereafter, the etching gas and residual gas in the second space 11b may be simply referred to as gas. In Figures 4 and 5, the flow of gas toward the first exhaust device 531 in the second space 11b is indicated by arrow F3.

[0037] The area of ​​the gas exhaust port 503 is larger than the area of ​​the first opening 501, and the area of ​​the first opening 501 is larger than the areas of the second opening 505, the droplet supply opening 507, and the droplet discharge opening 509. The areas of the droplet supply opening 507 and the droplet discharge opening 509 are approximately the same and are larger than the area of ​​the second opening 505.

[0038] In the following explanation, the direction along the trajectory of the droplet target DL may be referred to as the Y direction, the direction from the plasma generation region AR toward the first exhaust device 531 and perpendicular to the Y direction as the X direction, and the direction perpendicular to both the Y and X directions as the Z direction.

[0039] 3.2 Operation Next, the operation of the comparative example EUV light generator 100 will be described.

[0040] In the EUV light generator 100, the air inside the chamber 10 is exhausted, for example, during new installation or maintenance. In this case, purging and exhausting of the inside of the chamber 10 may be repeated to remove atmospheric components. Preferably, an inert gas such as nitrogen or argon is used as the purge gas. After that, when the pressure inside the chamber 10 falls below a predetermined pressure, the processor 120 starts introducing etching gas from the first gas supply device 601 to the first space 11a of the chamber 10 through the gas supply port 601a. ​​At this time, the processor 120 may control a supply gas flow rate adjustment unit (not shown) and a first exhaust device 531 so that the pressure inside the chamber 10 is maintained at a predetermined pressure. After that, the processor 120 waits until a predetermined time has elapsed since the start of the introduction of etching gas.

[0041] Furthermore, the processor 120 uses the first exhaust device 531 to exhaust the gas from the internal space of the chamber 10 through the gas exhaust port 503, and maintains the pressure inside the chamber 10 at a nearly constant level based on a signal indicating the pressure inside the chamber 10 measured by the pressure sensor 26.

[0042] Furthermore, the processor 120 supplies current from the heater power supply 46 to the heater 44 to heat and maintain the target substance in the tank 41 at a predetermined temperature above its melting point, thereby raising the temperature of the heater 44. At this time, the processor 120 adjusts the value of the current supplied from the heater power supply 46 to the heater 44 based on the output from the temperature sensor 45, thereby controlling the temperature of the target substance to the predetermined temperature. The predetermined temperature is, in the case of the target substance being tin, a temperature above the melting point of tin, 231.93°C, for example, between 240°C and 290°C. Thus, preparation for ejecting the droplet target DL is complete.

[0043] Once preparation is complete, the processor 120 adjusts the pressure in the tank 41 by supplying inert gas from a gas supply source (not shown) via a pressure regulator 43 so that the molten target material is discharged from the nozzle hole of the nozzle 42 at a predetermined flow rate. Under this pressure, the target material is discharged from the nozzle hole of the nozzle 42 into the first space 11a of the chamber 10. The target material discharged from the nozzle hole may take the form of a jet. At this time, the processor 120 applies a voltage of a predetermined waveform from the piezoelectric power supply 48 to the piezoelectric element 47 in order to generate a droplet target DL. The piezoelectric power supply 48 applies a voltage such that the waveform of the voltage value is, for example, sinusoidal, square, or sawtooth. The vibration of the piezoelectric element 47 can propagate through the nozzle 42 to the target material discharged from the nozzle hole of the nozzle 42. The target material is divided at a predetermined period by this vibration, becoming a droplet target DL. The diameter of the droplet target (DL) is generally between 10 μm and 30 μm.

[0044] When the droplet target DL is ejected, it passes through the droplet supply opening 507 and proceeds to the plasma generation region AR. The detection unit 27 detects the timing of the passage of the droplet target DL as it passes a predetermined position in the second space 11b of the chamber 10. Based on the signal from the detection unit 27, the processor 120 controls the timing of the emission of laser light 90 from the laser device LD so that the laser light 90 is irradiated onto the droplet target DL, and outputs a trigger signal. The trigger signal output from the processor 120 is input to the laser device LD. When the trigger signal is input to the laser device LD, it emits laser light 90.

[0045] The emitted laser beam 90 passes through the laser beam delivery optical system 30 and the window 12 before entering the laser focusing optical system 13. The laser beam 90 then travels from the laser focusing optical system 13 through the second aperture 505 towards the plasma generation region AR. In the plasma generation region AR, the laser beam 90 irradiates the droplet target DL. At this time, the processor 120 controls the laser beam manipulator 13C of the laser focusing optical system 13 so that the laser beam 90 is focused into the plasma generation region AR. The processor 120 also controls the timing of the emission of the laser beam 90 from the laser device LD based on a signal from the detection unit 27, so that the laser beam 90 irradiates the droplet target DL. As a result, the laser beam 90 focused by the laser beam focusing mirror 13A irradiates the droplet target DL in the plasma generation region AR. This irradiation generates plasma, and light including EUV light 101 is emitted from the plasma.

[0046] Of the light, including EUV light 101 generated in the plasma generation region AR, the EUV light 101 passes through the first aperture 501 and proceeds to the EUV light focusing mirror 75. After being focused at the intermediate focusing point IF by the EUV light focusing mirror 75, it enters the exposure apparatus 200 from the connection section 19.

[0047] As described above, the first gas supply device 601 supplies etching gas to the first space 11a of the chamber 10 through the gas piping 601b and the gas supply port 601a. ​​The etching gas flows into the second space 11b through the first opening 501, the second opening 505, the droplet supply opening 507, and the droplet discharge opening 509. The first exhaust device 531 sucks the etching gas, along with the residual gas in the second space 11b, through the gas exhaust port 503. As a result, the gas in the second space 11b is exhausted to the outside of the chamber 10. Due to this exhaust of gas, the pressure in the second space 11b becomes lower than the pressure in the first space 11a. Therefore, the etching gas in the first space 11a can easily flow from the first space 11a to the second space 11b through the first opening 501, the second opening 505, the droplet supply opening 507, and the droplet discharge opening 509. When etching gas flows more easily into the second space 11b, stagnation of etching gas in the first space 11a is suppressed, and the accumulation of debris such as unreacted target material that is not plasma-generated on the EUV light focusing mirror 75 is suppressed. In addition, backflow of gas from the second space 11b to the first space 11a is suppressed. The gas drawn into the first exhaust device 531 is subjected to predetermined exhaust treatment, such as detoxification.

[0048] 3.3 Challenges A plasma generation region AR is located in the second space 11b of the housing 500, and in the second space 11b, gas flows in the X direction toward the first exhaust device 531 due to the suction of the first exhaust device 531. As a result, in the plasma generation region AR, the droplet target DL, which is irradiated with laser light 90, tends to shift in the X direction due to the gas flow in the second space 11b. The position of the nozzle 42 that discharges the droplet target DL is adjusted so that the laser light 90 can be irradiated onto the droplet target DL in the plasma generation region AR. When the laser light 90 is irradiated onto the droplet target DL in this state, the droplet target DL is heated and turned into plasma. As a result, the gas around the plasma generation region AR is also heated and expands, and the pressure wave propagates outward from the plasma generation region AR, for example, in a radius of about 40 mm. As the pressure wave passes through this range, the distribution of gas flow in the second space 11b changes over time, and the amount by which the droplet target DL is shifted in the X direction due to the gas flow during this time also changes over time. As the displacement of the droplet target DL varies over time, the irradiation position of the laser beam 90 relative to the droplet target DL shifts, and the intensity of the EUV light 101 generated from the droplet target DL irradiated with the laser beam 90 may not stabilize. The droplet target DL tends to shift in the X direction due to the gas flow from the first aperture 501 and in the Y direction due to the gas flow from the droplet supply aperture 507 and the droplet discharge aperture 509. In addition, the droplet target DL tends to shift in the direction of the propagation of the laser beam 90 in the internal space of the chamber 10 due to the gas flow from the second aperture 505. However, because the area of ​​the first aperture 501 is larger than the areas of the second aperture 505, the droplet supply aperture 507, and the droplet discharge aperture 509, the droplet target DL tends to shift more in the X direction than in other directions. Figure 6 shows the change in the intensity of the EUV light 101 generated immediately after irradiating the droplet target DL, which has shifted irradiation position as described above, with the laser beam 90.In Figure 6, the horizontal axis represents the number of pulses of the laser beam 90, and the vertical axis represents the intensity of the EUV light 101. If the irradiation position of the laser beam 90 on the droplet target DL is shifted, there is a concern that the intensity of the EUV light 101 will not stabilize even if the laser beam 90 continues to irradiate the droplet target DL. If the intensity of the EUV light 101 is not stable, there is a concern that the EUV light 101 that meets the performance requirements of the exposure device 200 and inspection device 300 will not be emitted, leading to a decrease in the reliability of the EUV light generator 100.

[0049] Therefore, in the following embodiment, an EUV light generation apparatus 100 is provided in which a decrease in reliability can be suppressed.

[0050] 4. Description of the extreme ultraviolet light generating device of Embodiment 1 Next, the configuration of the EUV light generator 100 of Embodiment 1 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.

[0051] 4.1 Configuration Figure 7 is a cross-sectional view of the chamber 10 perpendicular to the trajectory of the droplet target DL in this embodiment. In the EUV light generator 100 of this embodiment, the configuration of the housing 500 differs from that of the housing 500 of the comparative example, and the direction along which the optical axis of the laser beam 90 irradiates the droplet target DL is different from the direction along which the optical axis of the laser beam 90 irradiates the droplet target DL in the comparative example. In the comparative example, the direction along which the optical axis of the laser beam 90 irradiates the droplet target DL is the Z direction. Similar to the comparative example, the direction in which the gas flows in the plasma generation region AR of this embodiment is the X direction.

[0052] The housing 500 of this embodiment does not have a second aperture 505. Therefore, the laser beam 90 of this embodiment passes to the side of the EUV light focusing mirror 75 in the first space 11a and proceeds from the first aperture 501 to the plasma generation region AR. In this embodiment, the laser beam 90 proceeds to the plasma generation region AR such that the optical axis of the laser beam 90 when irradiating the droplet target DL is aligned with the direction of gas flow in the plasma generation region AR. The inclination angle of the optical axis of the laser beam 90 when irradiating the droplet target DL with respect to the direction of gas flow in the plasma generation region AR is preferably, for example, within 20 degrees.

[0053] 4.2 Action and Effects In the chamber 10 apparatus of this embodiment, the optical axis of the laser beam 90 irradiated onto the droplet target DL is aligned with the direction in which the gas flows in the plasma generation region AR.

[0054] When gas flows in the X direction through the second space 11b, the droplet target DL tends to shift in the X direction in the plasma generation region AR, and the amount of X-direction displacement of the droplet target DL changes over time due to the effect of laser irradiation. With this configuration, even if the droplet target DL irradiated with laser light 90 shifts in the direction of gas flow in the plasma generation region AR, the droplet target DL remains positioned on the optical axis of the laser light 90 irradiating it. Therefore, the shift in the irradiation position of the laser light 90 relative to the droplet target DL can be suppressed. By suppressing this shift, the intensity of the EUV light 101 generated from the droplet target DL irradiated with laser light 90 can be stabilized. Therefore, EUV light 101 that meets the performance requirements of the exposure apparatus 200 and inspection apparatus 300 can be emitted, and a decrease in the reliability of the EUV light generator 100 can be suppressed.

[0055] Furthermore, the laser beam 90 travels from the first aperture 501 to the plasma generation region AR. With this configuration, since most of the gas flowing from the first aperture 501 to the second space 11b travels in the X direction, the optical axis of the laser beam 90 when irradiating the droplet target DL can be easily aligned with the direction in which the gas flows in the plasma generation region AR.

[0056] 5. Description of the extreme ultraviolet light generation device of Embodiment 2 Next, the configuration of the EUV light generator 100 of Embodiment 2 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.

[0057] 5.1 Configuration Figure 8 is a cross-sectional view of the chamber 10 perpendicular to the trajectory of the droplet target DL in this embodiment. In the EUV light generation apparatus 100 of this embodiment, the configuration of the EUV light focusing mirror 75 and the position of the laser beam 90 passing through the EUV light focusing mirror 75 differ from those of Embodiment 1.

[0058] The EUV light focusing mirror 75 of this embodiment includes a mirror aperture 75c through which the laser beam 90 traveling to the first aperture 501 passes. The mirror aperture 75c is located in the center of the EUV light focusing mirror 75 and faces the first aperture 501. Therefore, the laser beam 90 passes through the center of the EUV light focusing mirror 75. The mirror aperture 75c may be located anywhere on the EUV light focusing mirror 75 as long as it faces the first aperture 501. The area of ​​the mirror aperture 75c is smaller than the area of ​​the first aperture 501, but may be larger than or equal to the area of ​​the first aperture 501.

[0059] 5.2 Action and Effects The EUV light focusing mirror 75 in this embodiment includes a mirror aperture 75c. With this configuration, the laser beam 90 passes through the mirror aperture 75c and the first aperture 501 to proceed to the plasma generation region AR, thereby improving the freedom of arrangement of equipment placed in the internal space of the chamber 10, such as the EUV light focusing mirror 75 and the housing 500. Furthermore, the mirror aperture 75c faces the first aperture 501. With this configuration, the optical axis of the laser beam 90 when irradiating the droplet target DL can be more easily aligned with the direction of gas flow in the plasma generation region AR. Note that the mirror aperture 75c does not need to face the first aperture 501 as long as the optical axis of the laser beam 90 when irradiating the droplet target DL is aligned with the direction of gas flow in the plasma generation region AR.

[0060] 6. Description of the extreme ultraviolet light generating device of Embodiment 3 Next, the configuration of the EUV light generator 100 of Embodiment 3 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.

[0061] 6.1 Configuration Figure 9 is a cross-sectional view of the chamber 10 perpendicular to the trajectory of the droplet target DL in this embodiment. In the EUV light generator 100 of this embodiment, the configuration of the EUV light generator 100 differs from that of the comparative example.

[0062] The EUV light generation apparatus 100 of this embodiment further comprises a first pipe 551 that surrounds the optical path of the laser beam 90 in the first space 11a, a first gas passage 513 provided in the housing 500 and facing the second opening 505, and a second pipe 555 connected to the first gas passage 513.

[0063] The first pipe 551 extends from the first space 11a to the outside of the chamber 10 and is located inside the gas pipe 603b outside the chamber 10. The gas pipe 603b is connected to the outer wall of the chamber 10 and is provided with a window 603c through which the laser light 90 passing through the inside of the first pipe 551 is transmitted. The gas pipe 603b is also connected to the second gas supply device 603 outside the chamber 10. The second gas supply device 603 supplies gas to the first pipe 551 through the gas pipe 603b. This gas is an etching gas. The second gas supply device 603 is controlled by the processor 120. A supply gas flow rate adjustment unit, which is a valve (not shown), may be provided in the gas pipe 603b. In Figure 9, the gas flow in the gas pipe 603b and the first pipe 551 is indicated by arrow F4. The flow rate of gas into the first pipe 551 is, for example, between 40 nm and 60 nm.

[0064] Furthermore, the first pipe 551 extends toward the second opening 505 in the first space 11a. The first pipe 551 is connected to the second opening 505. The first pipe 551, extending in this manner, supplies gas flowing from the second gas supply device 603 through the gas pipe 603b to the plasma generation region AR through the second opening 505. The tip of the first pipe 551 located toward the plasma generation region AR in the second space 11b is, for example, 20 mm or more away from the plasma generation region AR. The first pipe 551 may gradually taper toward the plasma generation region AR. Note that the first pipe 551 does not need to be connected to the second opening 505, and the tip of the first pipe 551 may face the second opening 505 in the first space 11a.

[0065] The first flow velocity in the plasma generation region AR of the gas traveling from the first pipe 551 to the plasma generation region AR is faster than the second flow velocity in the plasma generation region AR of the gas traveling from the first space 11a through the first opening 501 to the plasma generation region AR. The first flow velocity is, for example, 200 m / s or more and 600 m / s or less, with 400 m / s being preferred. The second flow velocity is, for example, 40 m / s or more and 80 m / s or less, with 60 m / s being preferred.

[0066] The first gas passage 513 is provided on the opposite side from the second opening 505 with respect to the plasma generation region AR. The area of ​​the first gas passage 513 is preferably greater than or equal to the area of ​​the second opening 505, but it may be smaller than the area of ​​the second opening 505.

[0067] The second pipe 555 extends from the first space 11a to the outside of the chamber 10. The second pipe 555 is also connected to a second exhaust device 533 located outside the chamber 10. The second exhaust device 533 includes a suction pump. In this embodiment, the second exhaust device 533 may not be provided, and the second pipe 555 may be connected to the first exhaust device 531.

[0068] 6.2 Operation Next, the operation of the EUV light generator 100 in this embodiment will be described.

[0069] The second gas supply device 603 supplies gas to the first pipe 551 through the gas pipe 603b. The gas flows through the first pipe 551 and then flows from the first pipe 551 toward the plasma generation region AR. Therefore, unlike in Embodiment 1, the gas in the plasma generation region AR flows more easily in the direction of the extension of the first pipe 551 than in the X direction. Most of the gas then passes through the plasma generation region AR and the first gas passage 513 and flows into the second pipe 555. The gas that flows into the second pipe 555 is exhausted to the second exhaust device 533 by suction. In Figure 9, the gas flow in the second pipe 555 is indicated by arrow F5. Another portion of the gas flows in the X direction, similar to Embodiment 1, and is exhausted to the first exhaust device 531 by suction.

[0070] The laser beam 90 travels through the first pipe 551 to the plasma generation region AR. In this EUV light generator 100, the optical axis of the laser beam 90 when irradiating the droplet target DL is aligned with the direction of gas flow in the plasma generation region AR, that is, the direction of extension of the first pipe 551. Therefore, even if the droplet target DL irradiated by the laser beam 90 passing through the first pipe 551 shifts in the direction of gas flow in the plasma generation region AR, the droplet target DL remains on the optical axis of the laser beam 90. This suppresses the shift in the irradiation position of the laser beam 90 relative to the droplet target DL. When the laser beam 90 irradiates the droplet target DL, plasma is generated and EUV light 101 is emitted from the plasma. The EUV light 101 travels through the first aperture 501 to the EUV light focusing mirror 75, where it is reflected in a direction different from the incident direction and travels to the exposure apparatus 200.

[0071] 6.3 Action and Effects The EUV light generator 100 of this embodiment further includes a first pipe 551 that surrounds the optical path of the laser beam 90 in the first space 11a. The first pipe 551 extends toward the second aperture 505 and supplies gas from outside the chamber 10 to the plasma generation region AR. With this configuration, the optical axis of the laser beam 90 can be more easily aligned with the direction in which the gas flows in the plasma generation region AR. Therefore, the deviation of the irradiation position of the laser beam 90 relative to the droplet target DL irradiated with the laser beam 90 can be further suppressed.

[0072] Furthermore, the first flow velocity is faster than the second flow velocity. With this configuration, the droplet target DL irradiated with the laser beam 90 may be more prone to shifting in the direction of gas flow from the first pipe 551 to the plasma generation region AR than in the X direction in which gas flows from the first space 11a through the first aperture 501 to the plasma generation region AR. In this configuration, the laser beam 90 travels along the first pipe 551. Therefore, even if the droplet target DL shifts in the direction of gas flow in the plasma generation region AR as described above, the droplet target DL is located on the optical axis of the laser beam 90, so the shift in the irradiation position of the laser beam 90 relative to the droplet target DL can be suppressed. When this shift is suppressed, the intensity of the EUV light 101 generated from the droplet target DL irradiated with the laser beam 90 can be stabilized. Note that the first flow velocity may be less than or equal to the second flow velocity.

[0073] Furthermore, the EUV light generator 100 of this embodiment further includes a first gas passage 513 provided in the housing 500 and facing the second opening 505, and a second pipe 555 connected to the first gas passage 513 and extending from the first space 11a to the outside of the chamber 10. With this configuration, the gas supplied to the plasma generation region AR through the first pipe 551 can pass through the plasma generation region AR and be exhausted to the outside of the chamber 10 through the first gas passage 513 and the second pipe 555. This can suppress the gas that has passed through the plasma generation region AR from colliding with the inner wall 10b of the housing 500, and can suppress turbulence in the gas flow in the plasma generation region AR due to collisions. Therefore, the optical axis of the laser beam 90 can be more easily aligned with the direction in which the gas flows in the plasma generation region AR.

[0074] In this embodiment of the EUV light generation apparatus 100, the first gas passage 513, the second piping 555, and the second exhaust device 533 may not be provided.

[0075] Figure 10 is a cross-sectional view of the chamber 10 perpendicular to the trajectory of the droplet target DL in Modification 1 of this embodiment. In this modification, the first pipe 551 extends through the second opening 505 toward the plasma generation region AR in the second space 11b. This configuration makes it easier to align the optical axis of the laser beam 90 with the direction of gas flow in the plasma generation region AR.

[0076] Figure 11 is a cross-sectional view of the chamber 10 perpendicular to the trajectory of the droplet target DL in Modification 2 of this embodiment. In this modified EUV light generator 100, the second exhaust device 533 is not provided, and the configuration of the EUV light generator 100 and the housing 500 differs from that of Embodiment 3.

[0077] The modified EUV light generator 100 includes a second gas passage 515 provided in the housing 500, and a third pipe 557 located in the first space 11a and connected to the first gas passage 513 and the second gas passage 515. The second gas passage 515 is located in a different position from the first opening 501, the gas exhaust port 503, the second opening 505, the droplet supply opening 507, the droplet discharge opening 509, and the first gas passage 513 in the housing 500.

[0078] In this configuration, the gas supplied to the plasma generation region AR through the first pipe 551 passes through the plasma generation region AR and proceeds to the second space 11b through the first gas passage 513, the third pipe 557, and the second gas passage 515. In Figure 11, the gas flow in the third pipe 557 is indicated by arrow F6. The gas can then be exhausted to the outside of the chamber 10 through the gas exhaust port 503. Furthermore, with this configuration, it is not necessary to provide an opening in the chamber 10 to extend the second pipe 555 to the outside of the chamber 10, and the second exhaust device 533 may become unnecessary, thus simplifying the configuration of the chamber 10.

[0079] Furthermore, the second gas passage 515 is located between the first gas passage 513 and the gas exhaust port 503 in the X direction. With this configuration, the gas flowing through the third pipe 557 proceeds downstream of the plasma generation region AR. Therefore, disturbances in the trajectory of the droplet target DL in the plasma generation region AR caused by the gas that has passed through the plasma generation region AR can be suppressed.

[0080] In this modified example, the first pipe 551 does not need to pass through the second opening 505; it may be connected to the second opening 505, or the tip of the first pipe 551 may face the second opening 505 in the first space 11a.

[0081] 7. Description of the extreme ultraviolet light generating device of Embodiment 4 Next, the configuration of the EUV light generator 100 of Embodiment 4 will be described. Components similar to those described above will be denoted by the same reference numerals, and redundant explanations will be omitted unless specifically stated.

[0082] 7.1 Configuration Figure 12 is a cross-sectional view perpendicular to the optical axis of the laser beam 90 when irradiating the droplet target DL in this embodiment, and Figure 13 is a cross-sectional view of the chamber 10 perpendicular to the trajectory of the droplet target DL. In the EUV light generator 100 of this embodiment, the configuration of the EUV light generator 100 differs from that of the comparative example.

[0083] The EUV light generator 100 further comprises a target supply pipe 571, a target receiving pipe 573, and a gas passage pipe 575.

[0084] The target supply pipe 571 is positioned along the Y direction in the first space 11a and extends outside the chamber 10. The target supply pipe 571 surrounds the trajectory of the droplet target DL supplied from the target supply unit 40 located outside the chamber 10. In this embodiment, the target supply pipe 571 extends through the droplet supply opening 507 toward the plasma generation region AR in the second space 11b. The tip of the target supply pipe 571 located toward the plasma generation region AR in the second space 11b is, for example, 20 mm or more away from the plasma generation region AR.

[0085] A target gas supply port 571a is provided in the target supply piping 571 outside the chamber 10. Gas piping 605b is connected to this target gas supply port 571a, and a third gas supply device 605 is connected to gas piping 605b outside the chamber 10. The third gas supply device 605 supplies gas to the target gas supply port 571a through gas piping 605b, and the target gas supply port 571a supplies gas to the plasma generation region AR through the target supply piping 571. This gas is an etching gas. The third gas supply device 605 is controlled by the processor 120. A supply gas flow rate adjustment unit (not shown), which is a valve, may be provided in gas piping 605b. In Figure 13, the gas flow in gas piping 605b and the target supply piping 571 is indicated by arrow F7. The flow rate of gas flowing into the target supply piping 571 is, for example, 40 nm or more and 60 nm or less.

[0086] The third flow velocity in the plasma generation region AR of the gas traveling from the target gas supply port 571a through the target supply pipe 571 to the plasma generation region AR is, for example, 200 m / s or more and 600 m / s or less, with 400 m / s being preferred. The third flow velocity is faster than the second flow velocity in the plasma generation region AR of the gas traveling from the first space 11a through the first opening 501 to the plasma generation region AR.

[0087] The target receiving pipe 573 is positioned in the first space 11a, connected to the droplet discharge opening 509, and extends along the Y direction toward the opening 10a. In this way, the target receiving pipe 573 surrounds the trajectory of the droplet target DL after it passes through the droplet discharge opening 509.

[0088] A target receiving piping 573 is provided with a target receiving exhaust port 573a, and a gas passage piping 575 is connected to the target receiving exhaust port 573a. The target receiving exhaust port 573a exhausts the gas that has flowed from the second space 11b of the housing 500 through the droplet discharge opening 509 into the gas passage piping 575. In Figure 12, the gas flow in the target receiving piping 573 is indicated by arrow F8, and the gas flow in the gas passage piping 575 is indicated by arrow F9.

[0089] The gas passage piping 575 extends outside the chamber 10 and is connected to a gas passage 517 provided in the housing 500. The gas passage 517 is located in a different position from the first opening 501, gas exhaust port 503, second opening 505, droplet supply opening 507, and droplet discharge opening 509 in the housing 500. In the X direction, the gas passage 517 is located between the droplet discharge opening 509 and the gas exhaust port 503.

[0090] The detection unit 27 of this embodiment includes a light source unit 710 that emits light 92 toward the droplet target DL, and an imaging unit 720 that detects the light 92 emitted from the light source unit 710. The light source unit 710 and the imaging unit 720 are electrically connected to the processor 120. The light source unit 710 is positioned on the opposite side from the imaging unit 720 with respect to the trajectory of the droplet target DL. In other words, the light source unit 710 and the imaging unit 720 are positioned opposite each other with the trajectory of the droplet target DL in between. The direction in which the light source unit 710 and the imaging unit 720 are aligned is perpendicular to the trajectory, but it may be non-perpendicular to the trajectory. The light source unit 710 is attached to the inner wall 10b of the chamber 10 on the outside of the chamber 10 and is positioned coaxially with the window 731a provided on the inner wall 10b. The imaging unit 720 is also attached to the inner wall 10b of the chamber 10 and is positioned coaxially with the window 731b provided on the inner wall 10b.

[0091] The light source unit 710 includes a container 715 and a light source 711 and illumination optical system 713 housed in the container 715. The light source 711 may be, for example, a light source that emits monochromatic laser light, or a flash lamp that emits light containing multiple wavelengths. The illumination optical system 713 focuses the light 92 emitted from the light source 711 onto the trajectory of the droplet target DL through the window 731a and the aperture 519a of the housing 500. The illumination optical system 713 may include, for example, a collimating lens.

[0092] The imaging unit 720 includes a container 725 and a light-receiving optical system 721 and an imaging unit 723 housed in the container 725. The light-receiving optical system 721 includes, for example, a focusing lens. The light-receiving optical system 721 focuses light 92 from the second space 11b onto the imaging unit 723 via the aperture 519b and window 731b of the housing 500. Specifically, the light-receiving optical system 721 images the trajectory of the droplet target DL and the image around it onto the light-receiving surface of the imaging unit 723 in order to improve the detection accuracy of the droplet target DL. When the droplet target DL passes through the focusing region of light 92 by the light source unit 710, the imaging unit 723 detects the change in light 92 passing through the trajectory of the droplet target DL and around it. The imaging unit 723 converts the detected change in light 92 into an electrical signal as a signal relating to the image data of the droplet target DL. The imaging unit 723 outputs this electrical signal to the processor 120. Furthermore, the imaging unit 723 outputs a signal related to the detection timing of the droplet target DL to the processor 120. The processor 120 outputs a light emission trigger signal to the laser device LD that is delayed by a predetermined time relative to the signal related to the detection timing of the droplet target DL. The imaging unit 723 is, for example, a CCD (Charge-Coupled Device), a photodiode, etc. The light source unit 710, imaging unit 720, apertures 519a, 519b, and windows 731a, 731b are arranged such that the detection point of the droplet target DL by the detection unit 27 is located, for example, 2 mm from the plasma generation region AR toward the droplet supply aperture 507 in the second space 11b.

[0093] 7.2 Operation Next, the operation of the EUV light generator 100 in this embodiment will be described.

[0094] The target supply unit 40 discharges droplet targets DL, which then travel through the target supply piping 571 to the plasma generation region AR. Unwanted droplet targets DL then pass through the plasma generation region AR and are recovered by the target recovery unit 14 through the droplet discharge opening 509, the target receiving piping 573, and the opening 10a.

[0095] In this state, the light source unit 710 emits light 92 toward the droplet target DL, and the imaging unit 720 detects the light 92.

[0096] The third gas supply device 605 supplies gas to the target supply pipe 571 through the gas pipe 605b and the target gas supply port 571a. The gas flows through the target supply pipe 571 and then flows from the target supply pipe 571 toward the plasma generation region AR. Therefore, unlike in Embodiment 1, the gas in the plasma generation region AR flows more easily in the direction of extension of the target supply pipe 571 than in the X direction. Most of the gas then passes through the plasma generation region AR, the target receiving pipe 573, and the target receiving exhaust port 573a and flows into the gas passage pipe 575. The gas that flows into the gas passage pipe 575 then flows into the second space 11b through the gas passage port 517 and is exhausted to the first exhaust device 531 by the suction of the first exhaust device 531. Another portion of the gas flows in the X direction, similar to Embodiment 1, and is exhausted to the first exhaust device 531 by the suction of the first exhaust device 531.

[0097] In the EUV light generator 100 of this embodiment, the direction of travel of the droplet target DL supplied from the target supply unit 40 to the plasma generation region AR is aligned with the direction in which the gas supplied from the target supply pipe 571 flows in the plasma generation region AR. Since the gas flows from the third gas supply device 605 towards the plasma generation region AR in the Y direction via the gas pipe 605b and the target supply pipe 571, the droplet target DL tends to shift in the direction of gas flow in the plasma generation region AR. The direction of gas flow is the Y direction.

[0098] The processor 120 receives a signal from the detection unit 27 related to the detection timing of the droplet target DL, and outputs a light emission trigger signal to the laser device LD that is delayed by a predetermined time relative to the said signal. Because the detection point of the droplet target DL by the detection unit 27 is located very close to the plasma generation region AR, even if the droplet target DL irradiated with the laser beam 90 shifts in the direction of gas flow, the effect on the timing of when the laser beam 90 reaches the plasma generation region AR is extremely small. Therefore, the shift in the irradiation position of the laser beam 90 relative to the droplet target DL is also extremely small. When the laser beam 90 irradiates the droplet target DL, plasma is generated, and EUV light 101 is emitted from the plasma. The EUV light 101 passes through the first aperture 501 and proceeds to the EUV light focusing mirror 75, where it is reflected in a direction different from the incident direction and proceeds to the exposure device 200.

[0099] 7.3 Action and Effects In the chamber 10 device of this embodiment, the processor 120 receives a signal related to the detection timing of the droplet target DL from the detection unit 27 and outputs a light emission trigger signal to the laser device LD that is delayed by a predetermined time relative to the said signal.

[0100] As gas flows in the Y direction through the second space 11b, the droplet target DL in the plasma generation region AR tends to shift in the direction of gas flow due to the gas flow in the second space 11b, as described above. In the EUV light generation apparatus 100 of this embodiment, the direction of travel of the droplet target DL supplied from the target supply unit 40 to the plasma generation region AR is aligned with the direction of gas flow in the plasma generation region AR supplied from the target supply pipe 571. In the above configuration, the detection point of the droplet target DL by the detection unit 27 is located directly above the plasma generation region AR, and the detection unit 27 detects the passage of the droplet target DL at the detection point and then determines the irradiation timing of the laser device LD. Therefore, even if the droplet target DL irradiated with laser light 90 shifts in the direction of gas flow, the shift in the irradiation position of the laser light 90 relative to the droplet target DL can be suppressed. By suppressing this shift, the intensity of the EUV light 101 generated from the droplet target DL irradiated with laser light 90 can be stabilized. Therefore, EUV light 101 that meets the performance requirements of the exposure apparatus 200 and inspection apparatus 300 can be emitted, and a decrease in the reliability of the EUV light generator 100 can be suppressed.

[0101] Furthermore, the target supply pipe 571 extends through the droplet supply opening 507 towards the plasma generation region AR in the second space 11b. With this configuration, the droplet target DL supplied from the target supply unit 40 towards the plasma generation region AR can be easily routed along the direction of gas flow in the plasma generation region AR via the target supply pipe 571. Note that the target supply pipe 571 does not need to pass through the droplet supply opening 507 and may be connected to the droplet supply opening 507. Alternatively, the tip of the target supply pipe 571 may face the droplet supply opening 507 in the first space 11a.

[0102] Furthermore, the third flow velocity is faster than the second flow velocity. With this configuration, the droplet target DL irradiated with laser light 90 in the plasma generation region AR may be more prone to shifting in the direction of gas flow through the target supply pipe 571 to the plasma generation region AR than in the direction of gas flow from the first space 11a through the first aperture 501 to the plasma generation region AR. In this configuration, the laser light 90 travels along the target supply pipe 571. Therefore, even if the droplet target DL shifts in the direction of gas flow as described above, the droplet target DL is located on the optical axis of the laser light 90, so the shift in the irradiation position of the laser light 90 relative to the droplet target DL can be suppressed. When this shift is suppressed, the intensity of the EUV light 101 generated from the droplet target DL irradiated with laser light 90 can be stabilized. Note that the third flow velocity may be less than or equal to the second flow velocity.

[0103] Furthermore, the EUV light generator 100 of this embodiment includes a droplet discharge opening 509 and a target receiving pipe 573. With this configuration, the gas supplied to the plasma generation region AR through the target supply pipe 571 can pass through the plasma generation region AR and be exhausted to the outside of the chamber 10 through the droplet discharge opening 509 and the target receiving pipe 573. This can suppress the collision of the gas supplied to the plasma generation region AR through the target supply pipe 571 and passing through the plasma generation region AR with the inner wall 10b of the housing 500, thereby suppressing turbulence in the gas flow in the plasma generation region AR due to collisions. Therefore, the optical axis of the laser beam 90 can be more easily aligned with the direction of gas flow in the plasma generation region AR. Note that the target receiving pipe 573 is not required.

[0104] Furthermore, the EUV light generator 100 of this embodiment further includes a target receiving exhaust port 573a, a gas passage port 517, and a gas passage pipe 575. With this configuration, the gas flowing from the second space 11b to the target receiving pipe 573 proceeds back to the second space 11b through the target receiving exhaust port 573a, the second pipe 555, and the gas passage port 517, and can be exhausted to the outside of the chamber 10 from the gas exhaust port 503. Therefore, the accumulation of gas in the target receiving pipe 573 and the accumulation of debris in the target receiving pipe 573 can be suppressed.

[0105] Furthermore, the gas passage 517 is located between the droplet discharge opening 509 and the gas exhaust port 503. With this configuration, the gas flowing through the target receiving pipe 573 proceeds downstream of the plasma generation region AR. Therefore, disturbances in the trajectory of the droplet target DL in the plasma generation region AR caused by the gas that has passed through the plasma generation region AR can be suppressed.

[0106] In the EUV light generation apparatus 100 of this embodiment, the target receiving pipe 573, the gas passage port 517, and the gas passage pipe 575 may not be provided. Alternatively, in the EUV light generation apparatus 100 of this embodiment, the target receiving exhaust port 573a, the gas passage port 517, and the gas passage pipe 575 may not be provided.

[0107] The above description is intended to be illustrative and not restrictive. Therefore, it will 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 containing a plasma generation region within its internal space where plasma is generated from a droplet target irradiated with laser light, A housing that extends from the internal space to the outside of the chamber, surrounds the plasma generation region except on the trajectory of the droplet target in the internal space and on the optical path of the laser beam to the plasma generation region in the internal space, and includes a first aperture through which extreme ultraviolet light generated from the plasma passes; A light-gathering mirror is provided, which is located in the first space outside the housing within the internal space, and which reflects the extreme ultraviolet light that has passed through the first opening in a direction different from the incident direction of the extreme ultraviolet light. The chamber is provided with a gas supply port for supplying gas from outside the chamber to the first space, A gas exhaust port is provided outside the chamber, facing the first opening of the housing, and exhausts the gas flowing from the first space through the first opening to the second space inside the housing to the outside of the chamber, Equipped with, The optical axis of the laser beam irradiated onto the droplet target is aligned with the direction in which the gas flows in the plasma generation region. Extreme ultraviolet light generator.

2. An extreme ultraviolet light generating apparatus according to claim 1, The laser light propagates from the first aperture to the plasma generation region.

3. An extreme ultraviolet light generating apparatus according to claim 1, The focusing mirror includes a mirror opening through which the laser light traveling to the first aperture passes and which faces the first aperture.

4. An extreme ultraviolet light generating apparatus according to claim 1, The inclination angle of the optical axis of the laser beam irradiated onto the droplet target with respect to the direction in which the gas flows in the plasma generation region is within 20 degrees.

5. An extreme ultraviolet light generating apparatus according to claim 1, The first space further comprises a first pipe that surrounds the laser beam and extends from the first space to the outside of the chamber, The first piping extends toward a second opening in the housing through which the laser light passes from the first space toward the plasma generation region, and supplies gas from outside the chamber to the plasma generation region through the second opening.

6. An extreme ultraviolet light generating apparatus according to claim 5, The first flow velocity of the gas traveling from the first pipe to the plasma generation region in the plasma generation region is faster than the second flow velocity of the gas traveling from the first space through the first opening to the plasma generation region in the plasma generation region.

7. An extreme ultraviolet light generating apparatus according to claim 6, The first flow velocity is between 200 m / s and 600 m / s.

8. An extreme ultraviolet light generating apparatus according to claim 6, The second flow velocity is between 40 m / s and 80 m / s.

9. An extreme ultraviolet light generating apparatus according to claim 5, The housing is provided with a first gas passage opening facing the second opening, A second pipe connected to the first gas passage and extending from the first space to the outside of the chamber, To further prepare.

10. An extreme ultraviolet light generating apparatus according to claim 5, The first piping extends further through the second opening toward the plasma generation region in the second space.

11. An extreme ultraviolet light generating apparatus according to claim 5, The housing is provided with a first gas passage opening facing the second opening, A second gas passage is provided in the housing at a position different from the first opening, the second opening, the gas exhaust port, and the first gas passage, A third pipe is arranged in the first space and connected to the first gas passage and the second gas passage, To further prepare.

12. An extreme ultraviolet light generating apparatus according to claim 11, The second gas passage is located between the gas exhaust port and the first gas passage.

13. A chamber containing a plasma generation region within its internal space, A target supply unit that supplies droplet targets to the plasma generation region, A laser device that irradiates the droplet target with laser light so that plasma is generated from the droplet target in the plasma generation region, Control unit and Equipped with, The aforementioned chamber is A housing extending from the internal space to the outside of the chamber, surrounding the plasma generation region in the internal space except on the optical path of the laser beam to the plasma generation region, and including a first aperture through which extreme ultraviolet light generated from the plasma passes, and a droplet supply aperture through which the droplet target supplied from the target supply unit to the plasma generation region passes; A light-gathering mirror is provided, which is located in the first space outside the housing within the internal space, and which reflects the extreme ultraviolet light that has passed through the first opening in a direction different from the incident direction of the extreme ultraviolet light. The chamber is provided with a gas supply port for supplying gas from outside the chamber to the first space, A gas exhaust port is provided on the housing outside the chamber, which exhausts the gas flowing from the first space through the first opening into the second space inside the housing to the outside of the chamber. A target supply pipe is arranged in the first space and surrounds the trajectory of the droplet target supplied from the target supply unit, A target gas supply port is provided in the target supply piping and supplies gas to the plasma generation region through the target supply piping, A detection unit for detecting the droplet target supplied from the target supply unit to the plasma generation region, Equipped with, The control unit receives a signal from the detection unit relating to the detection timing of the droplet target, and outputs a light emission trigger signal to the laser device that is delayed by a predetermined time relative to the signal. Extreme ultraviolet light generator.

14. An extreme ultraviolet light generating apparatus according to claim 13, The target supply piping extends through the droplet supply opening toward the plasma generation region in the second space.

15. An extreme ultraviolet light generating apparatus according to claim 13, The third flow velocity of the gas traveling from the target gas supply port through the target supply piping to the plasma generation region is faster than the second flow velocity of the gas traveling from the first space through the first opening to the plasma generation region.

16. An extreme ultraviolet light generating apparatus according to claim 13, The housing is provided with a droplet discharge opening through which the droplet target, having passed through the plasma generation region, passes; A target receiving pipe is arranged in the first space, connected to the droplet discharge opening, and surrounds the trajectory of the droplet target after it has passed through the droplet discharge opening, To further prepare.

17. An extreme ultraviolet light generating apparatus according to claim 16, A target receiving exhaust port is provided in the target receiving piping and exhausts the gas flowing from the second space into the target receiving piping, A gas passage opening provided in the housing at a position different from the first opening, the droplet supply opening, the droplet discharge opening, and the gas exhaust port, A gas passage pipe connected to the target receiving exhaust port and the gas passage port, To further prepare.

18. An extreme ultraviolet light generating apparatus according to claim 17, The gas passage is located between the droplet discharge opening and the gas exhaust port.

19. A chamber containing a plasma generation region within its internal space where plasma is generated from a droplet target irradiated with laser light, A housing that extends from the internal space to the outside of the chamber, surrounds the plasma generation region except on the trajectory of the droplet target in the internal space and on the optical path of the laser beam to the plasma generation region in the internal space, and includes a first aperture through which extreme ultraviolet light generated from the plasma passes; A light-gathering mirror is provided, which is located in the first space outside the housing within the internal space, and which reflects the extreme ultraviolet light that has passed through the first opening in a direction different from the incident direction of the extreme ultraviolet light. The chamber is provided with a gas supply port for supplying gas from outside the chamber to the first space, A gas exhaust port is provided on the housing outside the chamber, which exhausts the gas flowing from the first space through the first opening into the second space inside the housing to the outside of the chamber. A first pipe surrounds the laser beam in the first space and extends from the first space to the outside of the chamber, Equipped with, The first piping extends toward the second opening in the housing through which the laser beam passes from the first space toward the plasma generation region, and supplies gas from outside the chamber to the plasma generation region through the second opening. The optical axis of the laser beam irradiated onto the droplet target is aligned with the direction in which the gas flows in the plasma generation region. Extreme ultraviolet light generator.

20. A chamber containing a plasma generation region within its internal space where plasma is generated from a droplet target irradiated with laser light, A housing extending from the internal space to the outside of the chamber, surrounding the plasma generation region in the internal space except on the trajectory of the droplet target, and including a first aperture through which extreme ultraviolet light generated from the plasma passes and a second aperture through which the laser light passes toward the plasma generation region, A light-gathering mirror is provided, which is located in the first space outside the housing within the internal space, and which reflects the extreme ultraviolet light that has passed through the first opening in a direction different from the incident direction of the extreme ultraviolet light. The chamber is provided with a gas supply port for supplying gas from outside the chamber to the first space, A gas exhaust port is provided on the housing outside the chamber, which exhausts the gas flowing from the first space through the first opening into the second space inside the housing to the outside of the chamber. Equipped with, The optical axis of the laser beam irradiated onto the droplet target is aligned with the direction in which the gas flows in the plasma generation region. The extreme ultraviolet light generated by the extreme ultraviolet light generator is output to the exposure apparatus. In order to manufacture an electronic device, the photosensitive substrate is exposed to the extreme ultraviolet light in the exposure apparatus. A method for manufacturing electronic devices, including the following.

21. A chamber containing a plasma generation region within its internal space where plasma is generated from a droplet target irradiated with laser light, A housing extending from the internal space to the outside of the chamber, surrounding the plasma generation region in the internal space except on the trajectory of the droplet target, and including a first aperture through which extreme ultraviolet light generated from the plasma passes and a second aperture through which the laser light passes toward the plasma generation region, A light-gathering mirror is provided, which is located in the first space outside the housing within the internal space, and which reflects the extreme ultraviolet light that has passed through the first opening in a direction different from the incident direction of the extreme ultraviolet light. The chamber is provided with a gas supply port for supplying gas from outside the chamber to the first space, A gas exhaust port is provided on the housing outside the chamber, which exhausts the gas flowing from the first space through the first opening into the second space inside the housing to the outside of the chamber. Equipped with, The optical axis of the laser beam irradiated onto the droplet target is aligned with the direction in which the gas flows in the plasma generation region. Extreme ultraviolet light generated by an extreme ultraviolet light generator is irradiated onto the mask to inspect for defects in the mask. Using the results of the above inspection, select a mask. The pattern formed on the selected mask is then exposed and transferred onto a photosensitive substrate. A method for manufacturing electronic devices, including the following.

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