Extreme ultraviolet light generation system and method for manufacturing electronic devices

Abstract

During the 200ms imaging interval, it was not possible to correct for the timing shift in irradiation caused by changes in the velocity of the target used for EUV light generation. [Solution] An extreme ultraviolet light generation system that generates extreme ultraviolet light by irradiating a target with pulsed laser light comprises a chamber, a target supplyer that continuously generates targets at specific time intervals and supplies them into the chamber, a timing sensor that detects targets passing through a first region and outputs a signal, a laser device that irradiates pulsed laser light onto targets that have passed through the first region, and a processor that determines from the signal the first time when the first target passed through the first region and the second time when a second target, which was generated immediately before the first target, passed through the first region, and determines the timing for irradiating the first target with the pulsed laser light of the laser device based on the first time, the second time, and the time interval.

Description

[Technical Field]

[0001] This disclosure relates to an extreme ultraviolet light generation system and a method for manufacturing electronic devices. [Background technology]

[0002] In recent years, with the miniaturization of semiconductor processes, the miniaturization of transfer patterns in semiconductor photolithography has been progressing rapidly. Next-generation models will require microfabrication of 10 nm or less. Therefore, the development of semiconductor exposure equipment combining a device for generating extreme ultraviolet (EUV) light with a wavelength of approximately 13 nm with a reduction projection reflective optical system is highly anticipated.

[0003] As for EUV light generation devices, development is progressing on Laser Produced Plasma (LPP) type devices that use plasma generated by irradiating a target material with laser light. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2016 / 079810 [Patent Document 2] International Publication No. 2014 / 189055 [Patent Document 3] Summary of International Publication No. 2017 / 130443

[0005] An extreme ultraviolet light generation system according to one aspect of the present disclosure is an extreme ultraviolet light generation system that generates extreme ultraviolet light by irradiating a target with pulsed laser light, comprising: a chamber; a target supplyer that continuously generates targets at specific time intervals and supplies them into the chamber; a timing sensor that detects targets passing through a first region and outputs a signal; a laser device that irradiates pulsed laser light onto targets that have passed through the first region; and a processor that determines from the signal a first time when the first target passed through the first region and a second time when a second target, generated immediately before the first target, passed through the first region, and determines the timing for irradiating the first target with pulsed laser light from the laser device based on the first time, the second time, and the time interval.

[0006] A method for manufacturing an electronic device according to another aspect of the present disclosure includes: a chamber; a target supplyer that continuously generates and supplies targets into the chamber at specific time intervals; a timing sensor that detects targets passing through a first region and outputs a signal; a laser device that irradiates pulsed laser light onto targets that have passed through the first region; and a processor that determines from the signal a first time when the first target passed through the first region and a second time when a second target, generated immediately before the first target, passed through the first region, and determines the timing for irradiating the first target with the pulsed laser light from the laser device based on the first time, the second time, and the time interval; and further includes generating extreme ultraviolet light using an extreme ultraviolet light generation system that generates extreme ultraviolet light by irradiating the target with pulsed laser light, outputting the extreme ultraviolet light to an exposure apparatus, and exposing a photosensitive substrate to extreme ultraviolet light in the exposure apparatus in order to manufacture an electronic device.

[0007] A method for manufacturing an electronic device relating to another aspect of the present disclosure includes: a chamber; a target supplyer that continuously generates and supplies targets into the chamber at specific time intervals; a timing sensor that detects targets passing through a first region and outputs a signal; a laser device that irradiates pulsed laser light onto targets that have passed through the first region; a processor that determines from the signal a first time when the first target passed through the first region and a second time when a second target, generated immediately before the first target, passed through the first region, and determines the timing for irradiating the first target with the pulsed laser light of the laser device based on the first time, the second time, and the time interval; and an extreme ultraviolet light generation system that generates extreme ultraviolet light by irradiating a target with pulsed laser light to inspect a mask for defects in the mask; selecting a mask using the inspection results; and exposure-transferring a pattern formed on the selected mask onto a photosensitive substrate. [Brief explanation of the drawing]

[0008] Some embodiments of this disclosure are described below, merely as examples, with reference to the accompanying drawings. [Figure 1] Figure 1 shows a schematic configuration of an LPP-type EUV light generation system. [Figure 2] Figure 2 shows the configuration of the EUV light generation apparatus according to the comparative example. [Figure 3] Figure 3 shows an example of an image formed on the light-receiving surface of the optical sensor of a target passage detection device. [Figure 4] Figure 4 shows an example of a detection signal output from a target passage detection device and an example of a target detection trigger signal generated from this detection signal. [Figure 5] Figure 5 shows an example of the generation period timing of each trigger signal generated by the trigger selection / delay device of the comparative example. [Figure 6] Figure 6 shows an example of the generation timing of each trigger signal generated by the comparative example trigger selection / delay device. [Figure 7]Figure 7 is a flowchart showing the operation of the EUV light generation apparatus according to the comparative example. [Figure 8] Figure 8 is a flowchart of the subroutine for the timing adjustment A process applied to step S25 in Figure 7. [Figure 9] Figure 9 schematically shows an example of an image acquired through the image sensor of the comparative example. [Figure 10] Figure 10 shows the generation period timing of each trigger signal generated by the trigger selection / delay device of the comparative example. [Figure 11] Figure 11 shows the configuration of the EUV light generation apparatus according to Embodiment 1. [Figure 12] Figure 12 schematically shows a target passing through the detection area of ​​the timing sensor. [Figure 13] Figure 13 shows an example of a sensor signal output from a timing sensor and an example of a DL pass-through signal generated from the sensor signal. [Figure 14] Figure 14 shows the relationship between the N-1th and Nth droplets and the distance from the nozzle to the timing sensor. [Figure 15] Figure 15 shows the relationship between the (N-1)th and Nth droplets, the distance from the nozzle to the timing sensor, and the distance from the timing sensor to the plasma generation region. [Figure 16] Figure 16 is a flowchart showing an example of the operation of the EUV light generation apparatus according to Embodiment 1. [Figure 17] Figure 17 is a flowchart of the subroutine for the timing adjustment B process applied to step S15 in Figure 16. [Figure 18] Figure 18 is a graph showing examples of laser irradiation timing delay times adjusted by timing adjustments A and B of the EUV light generator. [Figure 19] Figure 19 shows the configuration of the EUV light generation apparatus according to Embodiment 2. [Figure 20] Figure 20 is a flowchart showing an example of the operation of the EUV light generation apparatus according to Embodiment 2. [Figure 21]Figure 21 is a flowchart of the subroutine for the timing adjustment C process applied to step S16 in Figure 20. [Figure 22] Figure 22 shows the configuration of the EUV light generation apparatus according to Embodiment 3. [Figure 23] Figure 23 is a flowchart showing an example of the operation of the EUV light generation apparatus according to Embodiment 3. [Figure 24] Figure 24 is a flowchart of the subroutine for the timing adjustment D process applied to step S18 in Figure 23. [Figure 25] Figure 25 schematically shows the configuration of the exposure apparatus connected to the EUV light generator. [Figure 26] Figure 26 schematically shows the configuration of the inspection device connected to the EUV light generator. Embodiment

[0009] -table of contents- 1. Explanation of Terms 2. Overall description of the EUV light generation system 2.1 Configuration 2.2 Operation 3. EUV light generation apparatus related to the comparative example 3.1 Configuration 3.2 Operation 4. Challenges 5. Embodiment 1 5.1 Configuration 5.2 Overview of Timing Adjustment B 5.3 About the time interval I0 5.4 Time deviation dT 1,N About 5.5 Operation 5.6 Action and Effects 5.7 Other 6. Embodiment 2 6.1 Configuration 6.2 Operation 6.3 Action and Effects 7. Embodiment 3 7.1 Configuration 7.2 Operation 7.3 Action and Effects 8. Methods for Manufacturing Electronic Devices 9. About the processor 10. Others The embodiments of this disclosure will be described in detail below with reference to the drawings. The embodiments described below are examples of the disclosure and are not intended to limit the scope of this disclosure. Furthermore, not all configurations and operations described in each embodiment are necessarily essential to the configurations and operations of this disclosure. The same reference numerals are used for identical components, and redundant descriptions are omitted.

[0010] 1. Explanation of Terms The "target" is the object that is irradiated by the laser beam introduced into the chamber. When the target is irradiated with laser light, it becomes plasma and emits EUV light.

[0011] A "droplet" is a type of target supplied into a chamber. "DL" is an abbreviation for droplet.

[0012] "Plasma light" is synchrotron radiation emitted from a plasma-enhanced target. This synchrotron radiation includes EUV light.

[0013] 2. Overall description of the EUV light generation system 2.1 Configuration Figure 1 schematically shows the configuration of the LPP-type EUV light generation system 11. The EUV light generation device 1 is used together with the laser device 3. In this disclosure, the system including the EUV light generation device 1 and the laser device 3 is referred to as the EUV light generation system 11.

[0014] The EUV light generator 1 includes a chamber 2 and a target supply 26. The chamber 2 is a sealable container. The target supply 26 supplies the target material into the chamber 2. The target material may include tin, terbium, gadolinium, lithium, xenon, or any combination of two or more of these.

[0015] The wall of chamber 2 is provided with a through-hole. This through-hole is covered by a window 21, and pulsed laser light 32 output from the laser device 3 passes through the window 21. Inside chamber 2, an EUV focusing mirror 23 with a spheroidal reflective surface is positioned. The EUV focusing mirror 23 has a first focal point and a second focal point. A multilayer reflective film is formed on the surface of the EUV focusing mirror 23, in which molybdenum and silicon are alternately layered. The EUV focusing mirror 23 may be positioned such that its first focal point is located in the plasma generation region 25 and its second focal point is located in the intermediate focal point 293. A through-hole 24 is provided in the center of the EUV focusing mirror 23, and pulsed laser light 33 passes through the through-hole 24.

[0016] The EUV light generator 1 includes a processor 5, a target sensor 4, and the like. The target sensor 4 detects at least one of the following: the presence, trajectory, position, and velocity of the target 27. The target sensor 4 may also have an imaging function.

[0017] Furthermore, the EUV light generator 1 includes a connecting section 29 that connects the inside of the chamber 2 to the inside of the exposure apparatus 6. Inside the connecting section 29 is a wall 291 in which an aperture 292 is formed. The wall 291 is positioned such that the opening of the aperture 292 is located at the second focal point of the EUV focusing mirror 23.

[0018] Furthermore, the EUV light generation device 1 includes a laser light transmission device 34, a laser light focusing mirror 22, a target retrieval device 28 for retrieving the target 27, and the like. The laser light transmission device 34 includes an optical element for defining the transmission state of the laser light and an actuator for adjusting the position, orientation, etc., of this optical element.

[0019] 2.2 Operation Referring to Figure 1, the operation of the EUV light generation system 11 will be explained. The pulsed laser light 31 output from the laser device 3 passes through the laser light transmission device 34 and enters the chamber 2 as pulsed laser light 32, passing through the window 21. The pulsed laser light 32 travels through the chamber 2 along the laser light path, is reflected by the laser light focusing mirror 22, and is irradiated onto the target 27 as pulsed laser light 33.

[0020] The target supplier 26 outputs a target 27 formed from the target material toward the plasma generation region 25 inside the chamber 2. The target 27 is irradiated with pulsed laser light 33. The target 27 irradiated with pulsed laser light 33 becomes plasma, and synchrotron radiation 251 is emitted from the plasma. The EUV light 252 contained in the synchrotron radiation 251 is selectively reflected by the EUV focusing mirror 23. The EUV light 252 reflected by the EUV focusing mirror 23 is focused at an intermediate focusing point 293 and output to the exposure apparatus 6. Note that multiple pulses contained in the pulsed laser light 33 may be irradiated onto a single target 27.

[0021] The processor 5 is configured to oversee the control of the entire EUV light generation system 11. The processor 5 processes image data of the target 27 captured by the target sensor 4, etc. The processor 5 also performs at least one of the following: control of the timing of the output of the target 27 and control of the output direction of the target 27. Furthermore, the processor 5 performs at least one of the following: control of the oscillation timing of the laser device 3, control of the direction of propagation of the pulsed laser light 32, and control of the focusing position of the pulsed laser light 33. The various controls described above are merely examples, and other controls may be added as needed.

[0022] 3. EUV light generation apparatus related to the comparative example 3.1 Configuration The configuration of the EUV light generation apparatus 1 in the comparative example will be explained using Figure 2. The comparative example in this disclosure is a form that the applicant recognizes as being known only to the applicant, and is not a prior art example acknowledged by the applicant.

[0023] In Figure 2, the Z-axis represents the direction in which EUV light 252 is guided from the chamber 2 of the EUV light generator 1 toward the exposure apparatus 6 (not shown in Figure 2). The X-axis and Y-axis are perpendicular to the Z-axis and mutually perpendicular. The coordinate axes in subsequent drawings will be the same as those in Figure 2.

[0024] Chamber 2 is formed, for example, in a hollow spherical or cylindrical shape. The central axis direction of the cylindrical chamber 2 may be the Z-axis direction. In Figure 2, the laser beam focusing mirror 22 (see Figure 1) is omitted from the illustration, and the pulsed laser beam 33 output from the laser device 3 is shown for convenience, irradiating the plasma generation region 25. The description in Figure 1 is not intended to specify the irradiation direction of the pulsed laser beam 33. The irradiation direction of the pulsed laser beam 33 may be the Z-axis direction.

[0025] Chamber 2 is provided with a target supply passage 2a for supplying targets 27 from outside to inside Chamber 2. The target supply passage 2a is formed in a cylindrical shape. The central axis direction of the cylindrical target supply passage 2a may be approximately perpendicular to the Z axis. In Figure 2, the central axis direction of the target supply passage 2a is the Y direction.

[0026] If the chamber 2 is a hollow spherical shape, the target supply passage 2a may be provided on the wall surface of the chamber 2 where the window 21 and connection portion 29 are not located. The target supply passage 2a communicating with the chamber 2 may be understood as part of the chamber 2, and the interior of the target supply passage 2a is understood as the interior of the chamber 2.

[0027] The target supply unit 26 is located at the Y-direction end of the target supply path 2a (the upper Y-direction end in Figure 2). The target supply unit 26 includes a tank 261, a nozzle 262, and a piezoelectric element 731. The tank 261 is formed in a hollow cylindrical shape. The target material 267 is contained inside the tank 261.

[0028] At least the inner surface of the tank 261 is made of a material that does not readily react with the target substance 267. The material that does not readily react with the target substance 267 may be, for example, SiC, SiO2, Al2O3, molybdenum, tungsten, or tantalum.

[0029] The nozzle 262 is located at the bottom of the tank 261. One end of the pipe-shaped nozzle 262 is fixed to the hollow tank 261, and the other end has a nozzle hole 262a. The tank 261 is located outside the chamber 2, and the nozzle hole 262a is located inside the chamber 2. That is, the tank 261 is located outside the target supply passage 2a, and the nozzle 262 is located inside the target supply passage 2a through the target supply hole 2b of the target supply passage 2a. The target supply device 26 is located at the end of the target supply passage 2a, thereby blocking the target supply hole 2b. As a result, the inside of the chamber 2 is isolated from the atmosphere. The tank 261, nozzle 262, target supply passage 2a, and chamber 2 are all interconnected internally.

[0030] At least the inner surface of the nozzle 262 is made of a material that does not readily react with the target substance 267. The nozzle hole 262a is shaped to eject the molten target substance 267 into the chamber 2 in a jet-like manner.

[0031] The plasma generation region 25, located inside the chamber 2, is situated on the extension of the central axis direction of the nozzle 262.

[0032] The target supply unit 26 includes a heater 711 and a heater power supply 712 as a mechanism for regulating the temperature of the tank 261. The heater 711 is fixed to the outer side of the tank 261 and heats the tank 261. The heater 711 is connected to the heater power supply 712. The heater power supply 712 supplies power to the heater 711.

[0033] Processor 5 includes an arithmetic control processor 51 and a trigger selection / delay device 53. Processor 5 functions as an EUV light generation control unit.

[0034] The heater power supply 712 is connected to the arithmetic control processor 51, and the power supply to the heater 711 is controlled by the arithmetic control processor 51.

[0035] A temperature sensor (not shown) is fixed to the outer side of the tank 261. The temperature sensor is connected to the arithmetic control processor 51. The temperature sensor detects the temperature of the tank 261 and outputs a detection signal to the arithmetic control processor 51. The arithmetic control processor 51 can adjust the power supplied to the heater 711 based on the detection signal from the temperature sensor in order to heat and maintain the target substance 267 in the tank 261 at a predetermined temperature above its melting point. If the target substance 267 is tin, the predetermined temperature is a temperature above the melting point of tin, 231.93°C, for example, between 240°C and 290°C. Based on the output from the temperature sensor, the arithmetic control processor 51 adjusts the value of the current supplied from the heater power supply 712 to the heater 711 to control the temperature of the target substance 267 to the predetermined temperature.

[0036] The target supply unit 26 includes a pressure regulator 721 that regulates the pressure inside the tank 261. The pressure regulator 721 is connected to the tank 261 via piping 722. The piping 722 may be covered with insulation material or the like (not shown). A heater (not shown) may be placed in the piping 722. The temperature inside the piping 722 may be kept approximately the same as the temperature inside the tank 261.

[0037] As described above, the pressure regulator 721 is located at the bottom of the cylindrical tank 261, on the side opposite to the nozzle 262, via piping 722.

[0038] The pressure regulator 721 includes internal components such as solenoid valves for air supply and exhaust, and a pressure sensor. The pressure regulator 721 may also detect the pressure inside the tank 261 using the pressure sensor.

[0039] The pressure regulator 721 is connected to the gas cylinder 723. The gas cylinder 723 is filled with an inert gas such as helium or argon. The gas cylinder 723 supplies the inert gas into the tank 261 via the pressure regulator 721.

[0040] The pressure regulator 721 is connected to an exhaust pump (not shown). The pressure regulator 721 can operate the exhaust pump to exhaust the gas in the tank 261. The pressure regulator 721 can increase or decrease the pressure in the tank 261 by supplying gas to the tank 261 or exhausting the gas from the tank 261.

[0041] The pressure regulator 721 is connected to the arithmetic control processor 51. The pressure regulator 721 outputs a pressure detection signal detected by the pressure sensor to the arithmetic control processor 51. The pressure regulator 721 receives a control signal output from the arithmetic control processor 51.

[0042] The control signal output from the arithmetic control processor 51 may be a control signal for controlling the operation of the pressure regulator 721 so that the pressure in the tank 261 reaches the target pressure, based on the detection signal output from the pressure regulator 721.

[0043] The pressure regulator 721 supplies gas into the tank 261 or exhausts gas from the tank 261 based on a control signal from the arithmetic control processor 51. This allows the pressure in the tank 261 to be adjusted to a target pressure.

[0044] The target supplyer 26 forms droplets 271, for example, by a continuous jet method. In the continuous jet method, the nozzle 262 is vibrated to create standing waves in the jet-like flow of target 27, periodically separating the target 27. The separated target 27 can form free interfaces due to their own surface tension, thereby forming droplets 271.

[0045] The piezoelectric element 731, which serves as a means for vibrating the nozzle 262, is fixed to the outer side surface of the pipe-shaped nozzle 262. The target supply unit 26 is equipped with a piezoelectric drive circuit 732, and the piezoelectric element 731 is connected to the piezoelectric drive circuit 732. The piezoelectric drive circuit 732 supplies power to the piezoelectric element 731. The piezoelectric drive circuit 732 is connected to the arithmetic control processor 51. The arithmetic control processor 51 controls the power supply to the piezoelectric element 731.

[0046] The flow of the target substance 267 ejected in a jet-like manner from the nozzle 262 is periodically interrupted by the vibration of the piezoelectric element 731, forming droplets 271.

[0047] The piezo drive circuit 732 vibrates the piezoelectric element 731 at frequency f0, generating a droplet 271 with a period of 1 / f0. The frequency f0 that drives the piezoelectric element 731 is called the "piezo frequency f0". The piezo frequency f0 is the droplet generation frequency, and can also be called the target generation frequency. The piezo frequency f0 is, for example, about 200 kHz, and the droplet generation period (1 / f0 period) is, for example, about 0.005 ms. The piezo frequency f0 is an example of the "vibration frequency" in this disclosure. 1 / f0 corresponds to the time interval I0 of target generation described later.

[0048] The term "target 27" includes the concept of droplet 271. The trajectory of target 27, which is emitted from nozzle 262, as it moves toward the plasma generation region 25 is called the target trajectory F. The direction in which target 27 moves toward the plasma generation region 25 is called the "target travel direction." In Figure 2, the target travel direction is the Y direction.

[0049] The target feeder 26 is fixed to a stage 265 located at the end of the target feed path 2a. The stage 265 can move the target feeder 26 in two axial directions, the X and Z directions.

[0050] Stage 265 is connected to the arithmetic control processor 51. Control signals output from the arithmetic control processor 51 may be input to Stage 265.

[0051] The control signal output from the arithmetic control processor 51 may be a control signal for adjusting the position of the target supplyer 26 so that the target 27 output into the chamber 2 reaches the target position.

[0052] The target retrieval device 28 is positioned on the extension of the direction in which the target 27, which is output into the chamber 2, moves.

[0053] The EUV light generator 1 comprises a target passage detection device 70, a target image measurement device 90, and a pulse waveform processing device 55. The target passage detection device 70 and the target image measurement device 90 are examples of target sensors 4.

[0054] The target passage detection device 70 detects the target 27 as it passes through a predetermined region within the chamber 2. The predetermined region for monitoring the passage of the target 27 is located between the nozzle hole 262a and the plasma generation region 25, and intersects with the target trajectory F.

[0055] The target passage detection device 70 is provided at a predetermined position on the side of the target supply path 2a. The target passage detection device 70 is located between the target supply unit 26 and the plasma generation region 25.

[0056] The target passage detection device 70 comprises a luminaire 71 and a measuring instrument 81. The luminaire 71 and the measuring instrument 81 may be positioned opposite each other with the target trajectory F in between. In Figure 2, the opposing directions of the luminaire 71 and the measuring instrument 81 are shown to be approximately parallel to the X direction, but this is not the only option.

[0057] The illuminator 71 irradiates the droplet 271, which is traveling along the target trajectory F, with illumination light, which is continuous light. The continuous light irradiated onto the droplet 271 may be continuous laser light.

[0058] The illuminator 71 includes an illumination light source 72, an illumination optical system 73, and a window 78. The window 78 is mounted on the wall of the chamber 2. The illuminator 71 is positioned outside the chamber 2 via the window 78. The illumination light source 72 may be, for example, a light source that emits continuous laser light, such as a CW (Continuous Wave) laser power generator. The beam diameter of the continuous laser light may be sufficiently larger than the diameter of the droplet 271 (e.g., 20 μm).

[0059] The illumination optical system 73 includes optical elements such as lenses. The optical elements may be transmissive optical elements such as lenses, reflective optical elements such as mirrors, or a combination of these.

[0060] The illumination optical system 73 may include, for example, a cylindrical lens. The illumination optical system 73 may irradiate the target trajectory F with an elliptical beam. The length of the minor axis of the elliptical beam may be close to the diameter of the droplet 271, and the major axis may be perpendicular to the direction of the target trajectory F. For example, the direction of the minor axis of the elliptical beam may coincide with the Y direction, and the direction of the major axis may coincide with the Z direction. Note that the beam shape of the continuous laser light emitted from the illuminator 71 may be different from an ellipse.

[0061] The illumination optical system 73 focuses the continuous laser light emitted from the illumination light source 72 through the window 78 into a predetermined region including the target passage detection position on the target trajectory F. The predetermined region including the focusing region of the illumination optical system 73 is called the "target detection region." This target detection region is an example of the "first region" in this disclosure.

[0062] When the droplet 271, traveling along the target trajectory F, reaches the target detection area, the continuous laser light emitted from the illuminator 71 illuminates the droplet 271.

[0063] The measuring instrument 81 receives light emitted from the illuminator 71 and detects the light intensity. The measuring instrument 81 includes a window 88, a filter 82, an imaging optical system 84, and a light sensor 86. The window 88 is mounted on the wall of the chamber 2. The measuring instrument 81 is located outside the chamber 2 through the window 88.

[0064] The imaging optical system 84 may be an optical system such as a collimator and is composed of optical elements such as lenses. The imaging optical system 84 guides the continuous laser light emitted from the illuminator 71 to the light sensor 86 via the window 88 and filter 82.

[0065] The light sensor 86 may be a light-receiving element including a photodiode. The light sensor 86 may be a photodiode array including a plurality of sensor elements.

[0066] When the droplet 271 passes through a predetermined region of the target trajectory F, a portion of the continuous laser light is blocked by the droplet 271, and the light intensity (amount of light received) received by the measuring instrument 81 decreases. The measuring instrument 81 outputs a detection signal corresponding to the change in light intensity due to the passage of the droplet 271 to the pulse waveform processing device 55. The detection signal corresponding to the change in light intensity obtained from the optical sensor 86 is sometimes called the "target passage detection signal".

[0067] The pulse waveform processing device 55 receives the target passage detection signal output by the target passage detection device 70 and generates a target detection trigger signal from this target passage detection signal. The target detection trigger signal is a signal that indicates the timing when the target 27 has passed through a predetermined region of the target trajectory F.

[0068] The pulse waveform processing unit 55 outputs a target detection trigger signal to the trigger selection / delay device 53. In this way, the trigger selection / delay device 53 can detect the timing when the target 27, which is moving from the target supplier 26 toward the plasma generation region 25, has passed through a predetermined region on the target trajectory F. The target passage detection device 70 is also called a "timing sensor". The pulse waveform processing unit 55 may be included in the processor 5.

[0069] The target image measuring device 90 images the target 27 supplied to the plasma generation region 25 and generates image data. The target image measuring device 90 includes an illuminator 91 and a measuring instrument 101. The illuminator 91 and the measuring instrument 101 may be positioned opposite each other with the target trajectory F in between. The direction in which the illuminator 91 and the measuring instrument 101 face each other may be approximately perpendicular to the target trajectory F or not.

[0070] The illuminator 91 irradiates the target 27, which is traveling along the target trajectory F, with pulsed light. The illuminator 91 includes a flash lamp 92, an illumination optical system 94, and a window 98. The window 98 is mounted on the wall of the chamber 2. The illuminator 91 is positioned outside the chamber 2 through the window 98.

[0071] The flash lamp 92 is connected to the trigger selection / delay device 53. The flash lamp 92 pulses on and emits pulsed light based on the light emission trigger signal output from the trigger selection / delay device 53.

[0072] The illumination optical system 94 may be an optical system such as a collimator, and is composed of optical elements such as lenses. The illumination optical system 94 guides the pulsed light emitted from the flash lamp 92 onto the target trajectory F via the window 98.

[0073] The illuminator 91 can emit pulsed light toward the target trajectory F based on a light emission trigger signal. The pulsed light emitted from the illuminator 91 illuminates the target 27 as it travels along the target trajectory F.

[0074] The measuring instrument 101 captures an image of the shadow of the target 27, which is illuminated by pulsed light from the illuminator 91. The measuring instrument 101 includes a window 108, a filter 102, an imaging optical system 104, a shutter 105, an imaging optical system 106, and an image sensor 107. The window 108 is mounted on the wall of the chamber 2. The measuring instrument 101 is positioned outside the chamber 2 via the window 108.

[0075] The imaging optical system 104 may be a pair of optical elements such as lenses. The shutter 105 may be an electric shutter or a mechanical shutter. The shutter 105 is connected to the trigger selection / delay device 53. The shutter 105 opens and closes when it receives a shutter trigger signal output from the trigger selection / delay device 53, thereby regulating the exposure time of the image sensor 107.

[0076] The shutter 105 can use, for example, a gate-operated image intensifier (IIU). The image intensifier comprises a photocathode, a microchannel plate (MCP), and a phosphor screen. The photocathode converts light into electrons. The MCP is an electron multiplier that detects and multiplies electrons emitted from the photocathode in two dimensions. The gain can be adjusted by adjusting the voltage applied to the MCP. The phosphor screen converts electrons emitted from the output terminal of the MCP into light.

[0077] The gate operation of an image intensifier is achieved by changing the potential difference between the photocathode and the input surface of the microcluster crystal display (MCP). Gate operation is synonymous with shutter operation. When the potential of the photocathode is lower than the potential of the input surface of the MCP, electrons emitted from the photocathode are incident on the MCP, and an output image is obtained from the fluorescent screen. This gate-on state corresponds to the "shutter open" state. Conversely, when the potential of the photocathode is higher than the potential of the input surface of the MCP, electrons do not reach the MCP, and no output image is obtained from the fluorescent screen. This gate-off state corresponds to the "shutter closed" state. For example, gate operation can be achieved by fixing the potential of the MCP's incident surface and applying a negative pulse voltage to the photocathode.

[0078] The imaging optical systems 104 and 106 project the shadow of the target 27, guided through the window 108, onto the light-receiving surface of the image sensor 107.

[0079] The image sensor 107 may be a two-dimensional image sensor such as a CMOS (Complementary Metal Oxide Semiconductor). The image sensor 107 captures an image of the shadow of the target 27 that has been imaged by the imaging optical systems 104 and 106.

[0080] The image sensor 107 is connected to the trigger selection / delay device 53 and the arithmetic control processor 51. The image sensor 107 captures an image of the target 27's shadow based on the imaging trigger signal from the trigger selection / delay device 53. The image sensor 107 may also include a signal processing circuit that generates digital image data, such as bitmap data, from the image signal obtained by imaging.

[0081] Image data generated using the image sensor 107 is sent to the arithmetic control processor 51.

[0082] The arithmetic control processor 51 calculates parameters related to the target 27 based on image data obtained from the image sensor 107. These parameters may include, for example, the size, velocity, position, and distance (interval) between targets. The target image measuring device 90 is also called a "size sensor".

[0083] The spacing between targets 27 is the distance between two adjacent targets 27 sequentially output from the target supplier 26 into the chamber 2, and is the distance between targets in the target travel direction.

[0084] The measuring instrument 101 can perform fixed-point observations of a specific range on the target trajectory F. The position of the droplet 271 in the Y direction as imaged by the measuring instrument 101 may be its relative position within the imaging range in the target's direction of travel. In the captured image, the position of the target 27 in the Y direction may be the position of the target 27 in a direction substantially parallel to the target's direction of travel.

[0085] The trigger selection / delay device 53 generates various trigger signals based on the target detection trigger signal received from the pulse waveform processing device 55. The trigger selection / delay device 53 adds an appropriate delay time to the target detection trigger signal to generate an imaging trigger signal, a shutter trigger signal, a light emission trigger signal, and a laser trigger signal.

[0086] The laser trigger signal is a signal that controls the irradiation timing of the pulsed laser light 33 of the laser device 3.

[0087] Furthermore, the trigger selection / delay device 53 generates a target detection trigger signal for EUV emission and a target detection trigger signal for image measurement by thinning out the target detection trigger signal. The target detection trigger signal for EUV emission is a signal that controls the timing of generating EUV light. The target detection trigger signal for image measurement is a signal that controls the timing of target measurement by the target image measurement device 90.

[0088] The arithmetic control processor 51 sends trigger selection information and delay data to the trigger selection / delay device 53. The trigger selection information includes information for selecting a trigger signal. The delay data includes information for the delay time required to generate the corresponding trigger signal.

[0089] 3.2 Operation The operation of the target passage detection device 70 and the trigger signal generation process will be explained using Figures 3 to 6. Figure 3 shows an example of an image formed on the light-receiving surface of the optical sensor 86 of the target passage detection device 70. The optical sensor 86 may be, for example, a photodiode array (PDA) module equipped with multiple sensor elements 87. The shape of the light-receiving surface of each of the multiple sensor elements 87 may be a square, a rectangle, or another shape. In Figure 3, a PDA module with nine sensor elements 87 arranged in a row is shown as an example, but the number and arrangement of sensor elements 87 are not limited to the example in Figure 3. The sensor elements 87 are understood to be pixels that perform photoelectric conversion.

[0090] The image of the elliptical beam of laser light used as illumination may be incident on the entirety of the multiple sensor elements 87. When the target 27 passes through the focusing region of the elliptical beam, a shadow of the target 27 may be generated on any of the multiple sensor elements 87.

[0091] The diameter of the shadow of target 27 may be smaller than the length of the side of the light-receiving surface of sensor element 87. The shadow of target 27 may be a magnified image of target 27. The arrangement direction of the multiple sensor elements 87 may be substantially perpendicular to the direction of target movement. Also, the arrangement direction of the multiple sensor elements 87 may be substantially perpendicular to the normal direction of the light-receiving surface. The normal direction of the light-receiving surface may substantially coincide with the direction in which the laser light is incident.

[0092] Figure 3 shows an example in which the shadow of target 27 passes over the light-receiving surface of sensor element 87 located in the center of the PDA module. The downward arrow in Figure 3 indicates the direction of target movement, and the velocity V of target 27 is, for example, 45 m / s.

[0093] The direction of movement of the target 27's shadow on the light-receiving surface is determined by the positional relationship between the direction in which the illumination light is incident on the light-receiving surface and the target trajectory F. Therefore, the direction of movement of the target 27's shadow on the light-receiving surface does not necessarily have to coincide with the direction of movement of the target 27.

[0094] The target passage detection device 70 irradiates a sheet-like (elliptical beam-shaped) continuous laser beam from the illuminator 71 so that it passes 2.5 mm above the plasma generation region 25. "Above" the plasma generation region 25 means the upstream side in the target's direction of travel on the target trajectory F, that is, the side closer to the target supplier 26.

[0095] The position 2.5 mm above the plasma generation region 25 is an example of a position set as the target detection region. The laser light that passes 2.5 mm above the plasma generation region 25 passes through the imaging optical system 84 and is incident on the PDA module.

[0096] The imaging optical system 84 forms an image of a predetermined region, including a position 2.5 mm above the plasma generation region 25, onto the sensor surface of the PDA module.

[0097] If droplet 271 is not present in the target detection area, the laser beam enters the PDA module without obstruction, causing the PDA module to output a constant detection signal corresponding to the amount of light received. Here, the signal level of this "constant detection signal" is defined as a signal intensity of "100%".

[0098] When the droplet 271, ejected at frequency f0 (approximately 200 kHz), passes through the target detection area of ​​the target passage detection device 70, the detection signal output from the PDA module decreases.

[0099] Figure 4 shows an example of a detection signal output from the target passage detection device 70, and an example of a target detection trigger signal Td generated from this detection signal.

[0100] As shown in the upper part of Figure 4, the detection signal output from the target passage detection device 70 decreases in signal strength as the target 27 passes through. When the target 27 moves outside the target detection area, the signal strength of the detection signal returns to its original 100% level.

[0101] The pulse waveform processing device 55 uses the level at which the signal intensity of the detected signal is 100% as a reference, and detects the midpoint between the time when the detected signal decreases to a threshold set at a certain ratio to this reference intensity as t1, and the time when the decreased detected signal recovers to the threshold as t2, as the passing timing of the target 27. That is, if the passing timing is denoted as ta, ta is calculated by the following equation.

[0102] ta = (t1 + t2) / 2 Time t1 is called the "signal drop timing," and time t2 is called the "signal recovery timing." The threshold may be set, for example, to 90% of the reference intensity. The dashed line shown in the upper graph of Figure 4 indicates the threshold level.

[0103] As shown in the lower part of Figure 4, the pulse waveform processing device 55 outputs a target detection trigger signal Td with respect to time ta. In Figure 4, the target detection trigger signal Td is generated and output at the timing ta = Td.

[0104] Figures 5 and 6 show examples of generation cycle timings and generation timings for each trigger signal generated by the trigger selection / delay device 53. The top panel of Figure 5 shows an example of the target detection trigger signal Td, the middle panel shows an example of the target detection trigger signal for EUV emission, and the bottom panel shows an example of the target detection trigger signal for image measurement.

[0105] The target detection trigger signal Td is generated for each of the droplets 271, which are generated at approximately 200 kHz.

[0106] The trigger selection / delay device 53 receives trigger selection information from the arithmetic control processor 51 and performs the following operations 1 and 2 based on the target detection trigger signal Td.

[0107] [Operation 1] Since EUV emission is performed, for example, at about 20 kHz or 40 kHz, the trigger selection / delay device 53 decimates the target detection trigger signal Td so as to achieve that frequency and generates a target detection trigger signal for EUV emission.

[0108] [Operation 2] Since the measurement of the target 27 by the target image measurement device 90 is carried out, for example, at a time interval of about 200 ms (about 5 Hz), the trigger selection / delay device 53 further decimates the target detection trigger signal for EUV emission and generates a target detection trigger signal for image measurement.

[0109] In FIG. 6, examples of each trigger signal such as the target detection trigger signal Td for EUV emission or image measurement, imaging trigger signal, emission trigger signal, shutter trigger signal, and laser trigger signal T l are shown.

[0110] The trigger selection / delay device 53 receives delay time information from the arithmetic control processor 51 and generates various trigger signals.

[0111] The delay time information received by the trigger selection / delay device 53 includes the delay time TT0 i applied to the imaging trigger signal, f the delay time TT0 s applied to the emission trigger signal, l the delay time TT0 l applied to the shutter trigger signal, and

[0112] the delay time TT0 l applied to the laser trigger signal T. l is included.

[0113] The trigger selection / delay device 53 sets a delay time (TT0) for operating the target image measurement device 90 based on the target detection signal for image measurement. i TT0 f TT0 s The delay time (TT0) of each device is added to generate the imaging trigger signal, the light emission trigger signal, and the shutter trigger signal, respectively. i TT0 f TT0 s TT0 l The operating delay time is determined by considering the operating delay time between when each device receives a trigger signal and when it starts operating. The operating delay time is a value unique to each device.

[0114] Figure 7 is a flowchart illustrating an example of EUV emission operation.

[0115] In step S10, the arithmetic control processor 51 starts EUV emission.

[0116] In step S11, the arithmetic control processor 51 determines whether or not to terminate the emission of EUV light. If the result of the determination in step S11 is NO, the process proceeds to step S12.

[0117] In step S12, the pulse waveform processing device 55 detects the timing sensor passage time Td of the EUV emission target 27. As shown in Figure 4, the pulse waveform processing device 55 detects the midpoint ta = (t1 + t2) / 2 as the target passage timing from the time t1 when the output signal of the timing sensor decreases to a set threshold and the time t2 when the decreased signal recovers to the threshold.

[0118] The pulse waveform processing unit 55 detects the timing ta=Td as the timing sensor passage time Td and outputs it to the trigger selection / delay device 53. The passage timing ta may be determined from t1 and t2, or it may be the point in time when the detection signal of the timing sensor is at its minimum (lower peak).

[0119] In step S13, the arithmetic control processor 51 determines whether or not timing adjustment A can be performed. Timing adjustment A is performed based on the image acquired by the target image measuring device 90, and the delay time TT0 of the trigger signal (i or f or s or l) This is a process to adjust the subscript. Note that the notation "(i or f or s or l)" indicates that the subscript is one of "i", "f", "s", or "l", and is sometimes omitted.

[0120] Timing adjustment A is performed, for example, at time intervals of 200ms, and the process takes time. Therefore, in step S13, the arithmetic control processor 51 determines whether timing adjustment A is complete and whether the next image can be acquired. If acquisition is possible (YES determination), the process in step S14 and the timing adjustment A process in step S25 are performed in parallel. The subroutine for timing adjustment A will be described later using Figure 8.

[0121] On the other hand, if the result of the judgment in step S13 indicates that it is not possible to perform timing adjustment A (NO judgment), the processor 5 will perform the process in step S14 independently.

[0122] In step S14, the trigger selection / delay device 53 sets a delay time TT0 with respect to the target 27's passage time Td. (i or for s or l) Timing T with added (i or f or s or l) Then, a trigger signal is sent to each device.

[0123] T (i or f or s or l) =Td+TT0 (i or f or s or l) (Formula 1) T i , T f , T s This represents the timing of the imaging trigger signal, light emission trigger signal, and shutter trigger signal in the target image measurement device 90. i This is an example of the "image sensor imaging timing" in this disclosure. fThis is an example of the "flashing timing of the flash lamp" in this disclosure. s This is an example of the "shutter operation timing" in this disclosure.

[0124] After step S14, the process returns to step S11.

[0125] If the result of step S11 is YES, the process proceeds to step S28, and processor 5 terminates EUV emission.

[0126] Figure 8 is a flowchart showing an example of the timing adjustment A process applied in step S25. Timing adjustment A is performed in parallel with the flow of steps S11 to S14 in Figure 7, and involves a delay time TT0 determined by a size sensor. (i or f or s or l) This is the adjustment process.

[0127] In step S251, the arithmetic control processor 51 acquires an image of the target 27 in the plasma generation region 25 from the image sensor 107. In detail, the image acquisition procedure is as follows: the processor 5 gives a trigger signal to the size sensor at the timing shown in Figure 6, and acquires the image in the following steps [ST1] to [ST5].

[0128] [ST1] The image sensor 107 receives the target detection trigger signal Td for image measurement from TT0 i Upon receiving the imaging trigger signal, which is generated with a delay of a certain amount, the system starts exposure for a set period of time.

[0129] [ST2] The flash lamp 92 receives the target detection trigger signal Td for image measurement from TT0 f It receives a light-emitting trigger signal that is generated with a delay, and emits light for a certain period of time.

[0130] [ST3] The light emitted by the flash lamp 92 irradiates the plasma generation region 25, and the light that passes through the plasma generation region 25 passes through the imaging optical system 104 and reaches the shutter 105.

[0131] [ST4] The shutter 105 receives the target detection trigger signal Td for image measurement from TT0 s Upon receiving the shutter trigger signal, which is generated with a delay of a certain amount, a voltage is applied for a certain period of time (opening shutter 105).

[0132] [ST5] Light that has passed through the shutter 105 passes through the imaging optical system 106 and reaches the image sensor 107. The two imaging optical systems 104 and 106 transfer an image of the plasma generation region 25 onto the image sensor 107, so that an image including the shadow image of the target 27 in the plasma generation region 25 is output from the image sensor 107.

[0133] Figure 9 schematically shows an example of an image 99 acquired via the image sensor 107. The image sensor 107 captures an image 99 that includes images of shadows of multiple targets 27 sequentially output from the nozzle 262. The region including the plasma generation region 25 captured by the image sensor 107 is an example of a “second region” in this disclosure.

[0134] In step S252 of Figure 8, the arithmetic control processor 51 reads the image 99 output from the image sensor 107, processes the image data to determine the target interval ΔP on the image 99, and calculates the target velocity V from the target interval ΔP and the piezoelectric frequency f0 (target generation frequency). The target velocity V is synonymous with the droplet (DL) velocity.

[0135] V=ΔP×f0 (formula 2) To give a specific example, if the target spacing ΔP is 225 μm and the piezoelectric frequency f0 is 200 kHz, then the target velocity V is 45 m / s.

[0136] Next, in step S253, the arithmetic control processor 51 calculates the amount of deviation ΔH from the image data if the height of the target 27 deviates from the reference target height corresponding to the plasma generation region 25. This amount of deviation ΔH is called the "target height deviation ΔH". Furthermore, the arithmetic control processor 51 calculates the timing deviation ΔTT from the target height deviation ΔH and the target velocity V. d Calculate.

[0137] ΔTT d =-ΔH / V (Equation 3) Timing difference ΔTT d The unit of the time difference is seconds (s), the unit of the target height deviation ΔH is meters (m), and the unit of the target velocity V is meters per second (m / s).

[0138] Note that the term "height" for target 27 refers to its position in the target travel direction (Y direction). The target 27 used to calculate the target height deviation ΔH is the target 27 closest to the reference target height among the multiple targets 27 included in image 99. When this target 27 is on the target supply side 26 relative to the reference target height, ΔH is a negative value, and when it is on the opposite side (target retrieval device 28 side), it is a positive value. The Y axis is downward in Figure 9 and represents the target travel direction. The reference target height is an example of the "reference target position" in this disclosure.

[0139] ΔTT shown in Equation 3 d The sign of this value is the opposite of the sign of ΔH. Note that the target height shift ΔH is caused by the change in target velocity V.

[0140] The timing difference ΔTT calculated by Equation 3 d The delay time TT0 (i or f or s or l) This becomes the correction amount.

[0141] In step S254, the arithmetic control processor 51 determines the timing difference ΔTT d delay time TT0 (i or f or s or l)Reflected in the delay time TT0 (i or f or s or l) Update.

[0142] In other words, the arithmetic control processor 51 sets the delay time TT0 for each trigger for the operation of the laser device 3 and the size sensor. (i or f or s or l) ΔTT d After making only the necessary corrections, the data is sent to the trigger selection / delay device 53, completing the parallel processing of the subroutine shown in Figure 8.

[0143] TT0 (i or f or s or l) =TT0 (i or f or s or l) +ΔTT d (Formula 4) The left side of Equation 4 represents the corrected delay time, and the right side represents TT0 (i or f or s or l) This represents the current (pre-correction) delay time.

[0144] After the completion of timing adjustment A in Figure 8, the trigger selection / delay device 53 synchronizes with the passage time Td of the new target with the modified delay time TT0 according to Equation 4. (i or f or s or l) Timing T with added (i or f or s or l) Then, a trigger signal is sent to each device (step S14 in Figure 7).

[0145] In other words, the trigger selection / delay device 53 determines the delay time TT0 due to the next timing adjustment A. (i or f or s or l) Until the correction is complete, the delay time TT0 (i or f or s or l) Fix it in place and operate it.

[0146] 4. Challenges In the comparative example EUV light generator 1, the timing shift of the pulsed laser beam 33 irradiation due to the velocity change of the target 27 is corrected using the processing result of the image 99 obtained by the target image measuring device 90. For this reason, the timing shift correction was performed at a low frequency, such as the image acquisition frequency of 5 Hz (imaging time interval of 200 ms).

[0147] However, the velocity of the target 27 changes even during the 200ms imaging interval of the target image measurement device 90, and the EUV light generator 1 cannot adequately compensate for the timing difference in irradiation.

[0148] In other words, as shown in the dashed ellipse in Figure 10, the target 27 cannot be measured by the target image measuring device 90 during the 200ms imaging interval, and therefore the timing shift caused by changes in the velocity of the target 27 used for EUV light generation during this period cannot be corrected.

[0149] This leads to a decrease in EUV emission performance, such as a reduction in energy conversion efficiency (CE) and an increase in the variation of EUV light energy. In addition, contamination of the EUV focusing mirror 23 occurs due to fragmentation caused by the relative positional misalignment between the target 27 and the irradiation position of the pulsed laser beam 33.

[0150] 5. Embodiment 1 5.1 Configuration Figure 11 shows the configuration of the EUV light generator 1A according to Embodiment 1. The differences between the configuration of the EUV light generator 1A shown in Figure 11 and the EUV light generator 1 shown in Figure 2 will be explained below.

[0151] EUV light generator 1A includes a pulse waveform processing unit 55A and a processor 5A instead of the pulse waveform processing unit 55 and processor 5 shown in Figure 2. Processor 5A includes an arithmetic control processor 51A and a trigger selection / delay device 53A. The other configurations are the same as those of EUV light generator 1.

[0152] EUV light generator 1A differs from EUV light generator 1 in that it uses a target passage detection device 70 (timing sensor) to measure the velocity change of the target 27 and corrects the timing deviation caused by the velocity change. In other words, EUV light generator 1A performs the timing adjustment B described below.

[0153] 5.2 Overview of Timing Adjustment B The trigger selection / delay device 53A receives a time interval I0 for generating a target from the arithmetic control processor 51A. The time interval I0 may be the reciprocal of the frequency f0 that vibrates the piezoelectric element 731 of the nozzle 262. The Sn target material ejected from the nozzle 262 is divided at frequency f0 by the piezoelectric element 731 vibrating at frequency f0, and spherical droplets are generated due to surface tension. Therefore, the time interval I0 is the reciprocal of the frequency f0.

[0154] Furthermore, the trigger selection / delay device 53A detects the target passage time Td from the output signal (sensor signal) of the timing sensor from the pulse waveform processing device 55A. N and Td N-1 Received, Td N and Td N-1 Time interval I N Calculate.

[0155] I N =Td N -Td N-1 (Formula 5) Td N Td is the time it takes for target 27 to pass through the Nth target detected by the timing sensor. N-1 Td is the passage time of the (N-1)th target 27 detected by the timing sensor. N is an integer greater than or equal to 1. Td is the passage time of the Nth target 27, which is one of several targets 27 generated consecutively at time intervals I0. N This is an example of the “first time” in this disclosure. Also, the transit time Td of the (N-1)th target 27 generated immediately before the Nth target. N-1 This is an example of the “second time” in this disclosure. Time interval I N This is an example of "passing interval" in this disclosure.

[0156] Figure 12 schematically shows the targets passing through the detection area of ​​the timing sensor. The targets 27, which are sequentially output from the nozzle 262, are detected by the timing sensor, and the pulse waveform processing device 55A generates a pass signal (DL pass signal) for each target.

[0157] Figure 13 shows the sensor signal output from the timing sensor and the DL pass signal generated from the sensor signal. The DL pass signal can be understood as being the same as the target detection trigger signal. In Figure 13, the horizontal axis represents time and the vertical axis represents signal intensity.

[0158] In Figure 13, time T1 N The target 27 that passes through the detection area of ​​the timing sensor at the specified timing is referred to as the "Nth droplet". In Figure 12, the Nth droplet is referred to as "T1 N It is written as "DL". The interval between the passage time between the Nth droplet and the (N-1)th droplet is I N That is the case.

[0159] If there is no variation in the speed of the target 27 sequentially output from nozzle 262, the time interval I of the DL passing signal N This corresponds to the target generation period 1 / f0, i.e., the time interval I0. If the velocity of target 27 changes, the time interval I N This value will be different from the time interval I0.

[0160] The trigger selection / delay device 53A controls the time interval I N Time deviation dT with respect to time interval I0 1,N Calculate.

[0161] dT 1,N =I N -I0 (formula 6) The trigger selection / delay device 53A controls the time deviation dT 1,N The estimated time deviation dT for when the target 27 reaches the plasma generation region 25, which is estimated from this. 2,N Calculate the delay time TT N(i or f or s or l) Estimated time deviation dT 2,N Adding the delay time TT N(i or f or s or l) Update this estimated time deviation dT 2,N Delay time TT N(i or f or s or l) The series of adjustments is timing adjustment B.

[0162] Subsequently, the trigger selection / delay device 53A receives the updated delay time TT. N(i or f or s or l) Apply this to each trigger signal T N(i or f or s or l) The timing is determined by the following equation 7 and transmitted to each device.

[0163] T N(i or f or s or l) =Td N +TT N(i or f or s or l) (Formula 7) Delay time TT Nl This is an example of the “first delay time” in this disclosure.

[0164] 5.3 About the time interval I0 The time interval I0 does not need to be based on the vibration frequency of the piezoelectric element 731, as long as it indicates the time interval between the generated droplets. In devices that generate the target 27 using other vibration transmission components, it may be based on, for example, the vibration frequency or period of a voice coil or ultrasound. Furthermore, in cases where means other than vibration are used, such as in a target generation device that draws the target 27 from the nozzle 262 using gas pressure or a pulsed electric field, it may be based on the time interval of the pressure control or the frequency of the applied electric field.

[0165] 5.4 Time deviation dT 1,N About As previously described, the time interval I of the DL-passed signal output from the pulse waveform processing unit 55A N If there is no difference in the speed of the (N-1)th and Nth droplets, then the time interval I0 for target generation will be the same. Therefore, in that case, the time deviation dT is 1,N It becomes zero.

[0166] Figure 14 shows the relationship between the (N-1)th and Nth droplets and the distance D1 from the nozzle 262 to the detection area of ​​the timing sensor. Figure 14F14A on the left shows the (N-1)th droplet passing through the detection area of ​​the timing sensor, and Figure 14B on the right shows the Nth droplet passing through the detection area of ​​the timing sensor.

[0167] Here, let the speeds of the (N - 1)-th and N-th droplets be V N-1 and V N . Then, the time T 1,N-1 and T 1,N required for each droplet to move the distance D1 from the nozzle 262 to the detection area of the timing sensor is as follows.

[0168] T 1,N-1 = D1 / V N-1 (Equation 8) T 1,N = D1 / V N (Equation 9)

[0169] The difference in required time T 1,N - T 1,N-1 is equal to the time deviation dT 1,N detected by the timing sensor, so the following Equation 10 is obtained.

[0170] dT 1,N = I N - I0<00008​​​​​​​​​​​​​​​​​​​​​​​​The time T required for the (N-1)th and Nth droplets to travel the distance D2 from the timing sensor's detection area to the plasma generation area 25. 2,N-1 , T 2,N This can be calculated using the following equations 11 and 12.

[0173] T 2,N-1 = D2 / V N-1 =(D2 / D1)×T 1,N-1 (Formula 11) T 2,N = D2 / V N =(D2 / D1)×T 1,N (Formula 12) Furthermore, Equation 8 is applied to Equation 11, and Equation 9 is applied to Equation 12.

[0174] Estimated time deviation dT in plasma generation region 25 2,N V is the velocity of the droplet. N-1 If VN is constant between distance D1 and distance D2, then the following equation 13 holds.

[0175] dT 2,N = T 2,N - T 2,N-1 ={(D2 / D1)×T 1,N}-{(D2 / D1)× T 1,N-1} =(D2 / D1)×dT 1,N (Formula 13) Note that Equation 10 is applied to Equation 13.

[0176] In other words, the time deviation dT measured by the timing sensor 1,N By multiplying by (D2 / D1), the estimated time deviation dT in the plasma generation region 25 is obtained. 2,N This can be estimated. The time difference dT required for the (N-1)th and Nth droplets to reach the plasma generation region 25. 2,N =T 2,N - T 2,N-1 This corresponds to the difference in delay time.

[0177] The Nth droplet is an example of the “first target” in this disclosure, and the N-1th droplet is an example of the “second target”. Distance D1 is an example of the “first distance” in this disclosure, and distance D2 is an example of the “second distance” in this disclosure. (D2 / D1) is an example of the “ratio of the second distance to the first distance” in this disclosure. Time T 1,N This is an example of the “first required time” in this disclosure, and the required time T 1,N-1 This is an example of the “second required time” in this disclosure.

[0178] 5.5 Operation Figure 16 is a flowchart illustrating an example of the operation of the EUV light generator 1A. The differences between the flowchart in Figure 16 and that in Figure 7 will be explained below.

[0179] In the flowchart of Figure 16, step S12 in Figure 7 is removed, and steps S15 and S17 are included instead of step S14. In addition, steps S23 and S24 are added in Figure 16, which are performed when the result of step S13 is YES, and step S26 is added, which is performed after timing adjustment A in step S25.

[0180] If the result of step S13 is YES, processor 5A executes the flow (steps S23-S26) including the timing adjustment A (step S25) in parallel with step S15. The flow of steps S23-S26 will be described later.

[0181] If the result of step S13 is NO, processor 5A performs the timing adjustment B process in step S15 independently. The detailed flow of timing adjustment B will be described later using Figure 17.

[0182] After step S15, processor 5A proceeds to step S17. In step S17, trigger selection / delay device 53A receives a trigger signal T for each device. N(i or f or s or l) Generate and transmit to each device.

[0183] T N(i or f or s or l) = Td N + TT N(i or f or s or l) (Formula 7) Furthermore, the trigger selection / delay device 53A sends a trigger signal T to each device. N(i or f or s or l) The arithmetic control processor 51A is notified that the transmission process is complete. After step S17, the process returns to step S11. The other steps are the same as in the flowchart in Figure 7.

[0184] Figure 17 is a flowchart showing an example of a subroutine for the timing adjustment B process applied in step S15.

[0185] In step S31, the pulse waveform processing device 55A determines the timing sensor transit time Td of the Nth target 27. N The pulse waveform processing device 55A detects the timing of the target 27's passage timing, which is the midpoint ta = (t1 + t2) / 2 obtained from the time t1 when the output signal of the timing sensor, upon passing through the droplet, drops to a threshold set at a certain percentage (e.g., 90%), and the time t2 when the dropped signal recovers to the threshold. The passage timing ta may be determined not from t1 and t2, but from the time when the detected signal is at its minimum (lower peak), etc. In Embodiment 1, the timing sensor passage time Td is determined at the timing ta = Td. N It detects this and outputs to the trigger selection / delay device 53A.

[0186] In step S32, the trigger selection / delay device 53A selects the previously stored timing sensor passage time Td N-1 The following is read. That is, the trigger selection / delay device 53A reads the parameter Td stored in step S33 described below during the previous processing (the N-1th target 27). B The value of this value is the timing sensor transit time Td of the previous target in the processing of this current target (the Nth target, 27). N-1 It will be read as the equivalent time.

[0187] In step S33, the trigger selection / delay device 53A stores the timing sensor passing time Td of the currently passed target 27, which was acquired in step S31, as the parameter Td. N in the parameter Td B The stored Td B is read as the time corresponding to the timing sensor passing time Td of the previous droplet at the time of step S32 of the next process. N-1

[0188] In step S34, the trigger selection / delay device 53A calculates the time interval I from Td N and Td N-1 using Equation 5. N

[0189] I N = Td N - Td N-1 (Equation 5) For example, when the current passing droplet is the first droplet at the start of the flow, etc., the time of Td N-1 is indeterminate, and the I N calculated from Equation 5 may be an abnormal value. Therefore, when I N becomes, for example, a value twice or more the time interval I0 for generating the target 27, the following steps S35, S36, and S38 may be skipped.

[0190] In step S35, the trigger selection / delay device 53A receives the time interval I0 for generating the target 27 from the arithmetic control processor 51A and calculates the time deviation dT 1,N using Equation 6.

[0191] dT 1,N = I N - I0 (Equation 6) In step S-36, the trigger selection / delay device 53A calculates the estimated time deviation dT 2,N in the plasma generation region 25 using Equation 13.

[0192] dT 2,N = (D2 / D1) × dT 1,N (Equation 13)​ In step S38, the trigger selection / delay device 53A sets the delay time TT for each device. N(i or f or s or l) Estimated time deviation dT 2,N By adding (Equation 14), the delay time TT N(i or f or s or l) Update.

[0193] TT N(i or f or s or l) =TT N(i or f or s or l) +dT 2,N (Formula 14) The left side of Equation 14 represents the delay time after the update (correction), and the right side is TT. N(i or f or s or l) This represents the delay time before the update (before the correction).

[0194] After processing in step S38, the flowchart in Figure 17 is terminated, and the process proceeds to step S17 in Figure 16.

[0195] If the result of step S13 in Figure 16 is a YES result, the processes from step S23 to step S26 are executed in parallel with the loop (steps S11 to S17) that includes steps S15 and S17.

[0196] In step S23, the pulse waveform processing device 55A detects the target passage time Td of the timing sensor and outputs it to the trigger selection / delay device 53A. For the sake of simplicity, here we will explain the case in which the following timing adjustment A is performed based on the passage time Td of a third target that is different from the Nth target 27 (first target) or the N-1th target 27 (second target) processed by timing adjustment B.

[0197] However, since timing adjustment A (step S25) and timing adjustment B (step S15) are performed in parallel, the third target may be the same as the first or second target.

[0198] In step S24, before entering the timing adjustment A process, the arithmetic control processor 51A checks the currently set delay time TT in the trigger selection / delay device 53A.N(i or f or s or l) Read the value of TT0 (i or f or s or l) Set this as the initial value.

[0199] TT0 (i or f or s or l) =TT N(i or f or s or l) (Formula 15) In step S25, the arithmetic control processor 51A, according to the flowchart in Figure 8, determines TT0 from the captured image of the droplet. (i or f or s or l) Update.

[0200] In step S26, the arithmetic control processor 51A determines the delay time TT of the trigger selection / delay device 53A. N(i or f or s or l) The TT0 updated by timing adjustment A (i or f or s or l) Then, the following equation 16 is used to update the process, and steps S23 to S26, which are parallel processes, are terminated.

[0201] TT N(i or f or s or l) =TT0 (i or f or s or l) (Formula 16) 5.6 Action and Effects According to the EUV light generator 1A, the timing adjustment B determines the difference in the time required from the detection region of the timing sensor to the plasma generation region 25 for each droplet (estimated time deviation dT). 2,N By calculating the delay time TT for each droplet, N(i or f or s or l) It becomes possible to adjust this.

[0202] Figure 18 is a graph showing examples of laser irradiation timing delay times adjusted by timing adjustments A and B of the EUV light generator 1A. The horizontal axis represents time, and the vertical axis represents the delay time TT. Nl This is represented by the white circles in Figure 18, which represent the delay time due to timing adjustment A using the size sensor's measurement values. The black circles in Figure 18 represent the delay time due to timing adjustment B using the DL passage time interval of the timing sensor. As shown in Figure 18, timing adjustment A is performed on the target 27 every 5Hz, which is the size sensor measurement period, but timing adjustment B can be performed on all targets 27.

[0203] As a result, the EUV light generator 1A can continuously correct the laser irradiation timing for the target 27 used for EUV emission. The EUV light generator 1A reduces the variation in the irradiation position of droplets in the vertical direction (Y direction) at the laser irradiation timing, and improves the energy stability of the EUV light.

[0204] Furthermore, the EUV light generator 1A suppresses fragmentation caused by relative misalignment between the target 27 and the pulsed laser beam 33, thereby reducing contamination of the EUV focusing mirror 23.

[0205] 5.7 Other The timing adjustment B process in Embodiment 1 may be performed on all droplets or not on some droplets. For example, timing adjustment B may be performed on each EUV emission droplet (each laser irradiation) as shown in Figure 5. In this case, if the EUV emission droplet is the Nth droplet, then the timing sensor passage time Td for the Nth and N-1 droplets. N , Td N-1 By obtaining this data, the delay time correction for the EUV light generator 1A can be applied (see Figure 18).

[0206] Furthermore, distances D1 and D2 may be determined based on design values ​​such as those from CAD (Computer-Aided Design).

[0207] 6. Embodiment 2 6.1 Configuration Figure 19 shows the EUV light generator 1B according to Embodiment 2. The differences in the configuration of the EUV light generator 1B compared to the EUV light generator 1A shown in Figure 11 will be explained below.

[0208] The EUV light generation device 1B includes a buffer gas supply device 20 that supplies buffer gas into the chamber 2. The EUV light generation device 1B is flowing buffer gas into the chamber 2 to protect the device from tin fine particles and charged particles generated during plasma generation. When the buffer gas is hydrogen gas, radicals or ions generated from the hydrogen gas react with the tin that makes up these tin debris to generate stannane (SnH4) gas. In this process, the tin adhering to the surface of the component parts is removed.

[0209] The buffer gas supply device 20 is connected to, for example, the target supply path 2a and may supply buffer gas to the space between the nozzle 262 and the target passage detection device 70.

[0210] The EUV light generation device 1B includes a pulse waveform processing device 55B and a processor 5B instead of the pulse waveform processing device 55A and the processor 5A in FIG. 11. The processor 5B includes an arithmetic control processor 51B and a trigger selection / delay device 53B. The buffer gas supply device 20 is controlled by the arithmetic control processor 51B. Other configurations are the same as those of the EUV light generation device 1A.

[0211] 6.2 Operation The target 27 ejected from the nozzle 262 has its speed V1 near the target passage detection device 70 and its speed V2 near the target image measurement device 90 (plasma generation region 25) changed by the influence of the buffer gas supplied from the buffer gas supply device 20.

[0212] Therefore, the trigger selection / delay device 53B estimates the delay time deviation amount of the trigger signal in consideration of the influence coefficient k1 of the buffer gas injected into the chamber 2. The influence of the buffer gas is, for example, droplet acceleration or deceleration by the injected buffer gas and air resistance. Specifically, the relationship between the speed V1, the speed V2, and the influence coefficient k1 of the buffer gas is set as the relationship shown in Equation 17.

[0213] V1 = k1 × V2 (Equation 17) Accordingly, the relational expression in timing adjustment B will be changed as follows.

[0214] T 1,N =D1 / V1 N (Formula 18) T 2,N =D2 / V2 N =k1 ×(D2 / D1) ×T 1,N (Formula 19) dT 2,N =k1 ×(D2 / D1)×dT 1,N (Formula 20) Note that V1 in Equation 18 N V2 represents the velocity of the Nth droplet near the target passage detection device 70. N This represents the velocity of the Nth droplet near the target image measurement device 90 (plasma generation region 25).

[0215] Figure 20 is a flowchart illustrating an example of the operation of the EUV light generator 1B. The differences between the flowchart in Figure 20 and that in Figure 16 will be explained below.

[0216] The flowchart in Figure 20 includes timing adjustment C in step S16 instead of timing adjustment B (step 15) in Figure 16.

[0217] Figure 21 is a flowchart of an example of a subroutine for the timing adjustment C process applied in step S16. The differences between the flowchart in Figure 21 and Figure 17 are explained below. The flowchart in Figure 21 includes step S37 instead of step S35 in Figure 17.

[0218] In step S37, the arithmetic control processor 51B estimates the time deviation dT in the plasma generation region 25. 2,N This is calculated from equation 20.

[0219] The influence coefficient k1 can generally take a value of around 1. The value of the influence coefficient k1 can be determined by simulation calculations or determined experimentally. For example, in a simulation calculation for assumed buffer gas conditions, the influence coefficient k1 was 1.00002. The other steps are the same as the flowchart shown in Figure 17.

[0220] 6.3 Action and Effects According to the EUV light generator 1B, it is possible to correct the delay time, including the change in droplet velocity due to the effect of buffer gas.

[0221] 7. Embodiment 3 7.1 Configuration Figure 22 shows the configuration of the EUV light generator 1C according to Embodiment 3. The differences between the configuration of the EUV light generator 1C and the EUV light generator 1B will be explained below.

[0222] The EUV light generator 1C includes a pulse waveform processing unit 55C and a processor 5C instead of the pulse waveform processing unit 55B and processor 5B shown in Figure 19. The processor 5C includes an arithmetic control processor 51C and a trigger selection / delay device 53C.

[0223] In the EUV light generator 1C, the delay time information exchanged between the arithmetic control processor 51C and the trigger selection / delay device 53C is different from the delay time information exchanged between the arithmetic control processor 51B and the trigger selection / delay device 53B of the EUV light generator 1B.

[0224] In other words, the trigger selection / delay device 53C sets the timing sensor transit time Td of the Nth droplet. N The delay time TT0 and estimated time deviation dT were obtained using a size sensor (timing adjustment A). 2,N Adding this together creates the trigger signal T N It generates and transmits to each device. This delay time TT0 is an example of the “second delay time” in this disclosure.

[0225] T N =TdN +TT0+dT 2,N (Formula 21) Furthermore, the arithmetic control processor 51C periodically updates TT0 by timing adjustment A. Other configurations may be the same as those of the EUV light generator 1B.

[0226] 7.2 Operation Figure 23 is a flowchart illustrating an example of the operation of the EUV light generator 1C. The differences between the flowchart in Figure 23 and that in Figure 20 will be explained below.

[0227] In the flowchart of Figure 23, timing adjustment D in step S18 is included instead of timing adjustment C (step S16) in Figure 20, and step S19 is included instead of step S17. Also, in the flowchart of Figure 23, steps S24 and S26 in Figure 20 are deleted, and if the judgment result of step S13 is YES, a flow that proceeds to steps S23 and S25 and a flow that proceeds to step S18 and loops through steps S11 to S19 are executed in parallel.

[0228] If the result of the judgment in step S13 is NO, the process proceeds to step S18.

[0229] In step S18, the trigger selection / delay device 53C performs timing adjustment D. The details of timing adjustment D will be described later with reference to Figure 24.

[0230] In step S19 following step S18, the trigger selection / delay device 53C reads the delay time TT0 obtained in timing adjustment A (step S25) from the arithmetic control processor 51C, and the estimated time deviation dT obtained in timing adjustment D. 2,N Adding the trigger signal T N(i or f or s or l) The timing is generated (Equation 21), and a trigger signal is sent to each device.

[0231] After step S19, the process returns to step S11. The remaining steps are the same as in the flowchart in Figure 20.

[0232] Figure 24 is a flowchart showing an example of a subroutine for the timing adjustment D process applied in step S18.

[0233] The differences between the flowchart in Figure 24 and Figure 17 will be explained. In the flowchart in Figure 24, step S38 from Figure 17 is omitted, and the flowchart in Figure 24 ends upon completion of step S36. The other steps are the same as in Figure 17.

[0234] 7.3 Action and Effects According to Embodiment 3, the same effects as in Embodiment 1 can be obtained.

[0235] 8. Methods for Manufacturing Electronic Devices Figure 25 schematically shows the configuration of the exposure apparatus 6a connected to the EUV light generator 1A. In Figure 25, the exposure apparatus 6a, as an external device, includes a mask irradiation unit 68 and a workpiece irradiation unit 69. The mask irradiation unit 68 illuminates the mask pattern on the mask table MT via a reflective optical system using EUV light incident from the EUV light generator 1A. The workpiece irradiation unit 69 images the EUV light reflected by the mask table MT onto a workpiece (not shown) placed on the workpiece table WT via a reflective optical system. The workpiece is a photosensitive substrate such as a semiconductor wafer coated with photoresist. The exposure apparatus 6a exposes the workpiece to EUV light reflecting the mask pattern by synchronously moving the mask table MT and the workpiece table WT in parallel. By transferring a device pattern onto a semiconductor wafer through this exposure process, an electronic device can be manufactured.

[0236] Figure 26 schematically shows the configuration of the inspection device 6b connected to the EUV light generator 1A. In Figure 26, the inspection device 6b, as an external device, includes an illumination optical system 63 and a detection optical system 66. The illumination optical system 63 reflects the EUV light incident from the EUV light generator 1A and irradiates the mask 65 placed on the mask stage 64. The mask 65 here includes mask blanks before a pattern is formed. The detection optical system 66 reflects the EUV light from the illuminated mask 65 and forms an image on the light-receiving surface of the detector 67. The detector 67, having received the EUV light, acquires an image of the mask 65. The detector 67 is, for example, a TDI (Time Delay Integration) camera. Based on the image of the mask 65 acquired through the above process, defects in the mask 65 are inspected, 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 can be exposed and transferred onto a photosensitive substrate using the exposure device 6a to manufacture an electronic device.

[0237] Instead of EUV light generator 1A in Figures 25 and 26, EUV light generator 1B or 1C can be used.

[0238] 9. About the processor Processors such as processors 5, 5A, 5B, 5C and arithmetic control processors 51, 51A, 51B, 51C may be physically configured in hardware form to perform the various processes included in this disclosure. For example, a processor may be a computer including a memory storing control programs that define the various processes, and a processing unit that executes the control programs. The control programs may be stored in a single memory, or they may be divided and stored in multiple physically separate memories, and the various processes may be defined by the control program as a collection of these memories. The processing unit may be a general-purpose processing unit such as a CPU (Central Processing Unit), or a purpose-specific processing unit such as a GPU (Graphics Processing Unit).

[0239] Furthermore, the processor may be programmed in software form to perform the various processes included in this disclosure. For example, the processor may have functions for performing the various processes implemented in a dedicated device such as an ASIC (Application Specific Integrated Circuit) or a programmable device such as an FPGA (Field Programmable Gate Array).

[0240] The various processes included in this disclosure may be performed by one computer, one dedicated device, or one programmable device, or by the cooperation of multiple computers, multiple dedicated devices, or multiple programmable devices located physically separately. The various processes may be performed by at least two combinations of one or more computers, one or more dedicated devices, and one or more programmable devices.

[0241] The arithmetic control processors 51A, 51B, 51C, trigger selection / delay devices 53A, 53B, 53C, and pulse waveform processing devices 55A, 55B, 55C shown in Figures 11, 19, and 22 may perform calculation processing by the processor and memory after the signal has been digitized by an analog electrical signal processing circuit or an AD converter in order to carry out the processing described in each embodiment.

[0242] Furthermore, the processing may be divided into multiple processing units using different processing functions than those described above, or it may be consolidated into a single processing unit. For example, the arithmetic control processor 51A and the trigger selection / delay device 53A may be consolidated into a single processing unit for processing. These options are selected appropriately depending on the processing speed and accuracy.

[0243] 10. Others 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.

[0244] 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." In addition, it should be interpreted as including combinations of these with anything other than "A," "B," and "C."

Claims

1. An extreme ultraviolet light generation system that generates extreme ultraviolet light by irradiating a target with pulsed laser light, Chamber and, A target supplyer that continuously generates the aforementioned targets at specific time intervals and supplies them into the chamber, A timing sensor that detects the target passing through the first region and outputs a signal, A laser device that irradiates the pulsed laser light toward the target that has passed through the first region, A processor that determines from the signal the first time when the first target passed through the first region and the second time when the second target, which was generated immediately before the first target, passed through the first region, and determines the timing for irradiating the first target with the pulsed laser light of the laser device based on the first time, the second time, and the time interval. Equipped with, Extreme ultraviolet light generation system.

2. An extreme ultraviolet light generation system according to claim 1, The aforementioned timing sensor, A light source that irradiates the first region with light, A sensor that receives the aforementioned light, Extreme ultraviolet light generation system.

3. An extreme ultraviolet light generation system according to claim 1, The aforementioned target supplyer is Includes a piezoelectric element for generating the target, The aforementioned time interval is the reciprocal of the vibration frequency of the piezoelectric element. Extreme ultraviolet light generation system.

4. An extreme ultraviolet light generation system according to claim 1, The aforementioned processor, The timing is determined based on the time difference between the first time and the second time, which is the time deviation of the passing interval relative to the time interval, and the first time. Extreme ultraviolet light generation system.

5. An extreme ultraviolet light generation system according to claim 4, The aforementioned processor, An estimated time deviation, which represents the time difference between the first time required for the first target to reach the plasma generation region from the first region and the second time required for the second target to reach the plasma generation region from the first region, is obtained from the time deviation. The first time, The timing is determined based on the estimated time deviation. Extreme ultraviolet light generation system.

6. An extreme ultraviolet light generation system according to claim 5, The aforementioned processor, The estimated time deviation is obtained by multiplying the time deviation by the ratio of the second distance from the first region to the plasma generation region to the first distance from the nozzle of the target supply that outputs the target to the first region. Extreme ultraviolet light generation system.

7. An extreme ultraviolet light generation system according to claim 5, The system further includes a buffer gas supply device for injecting buffer gas into the chamber, The aforementioned processor, The estimated time deviation is calculated based on the aforementioned time deviation and the influence coefficient due to the buffer gas. Extreme ultraviolet light generation system.

8. An extreme ultraviolet light generation system according to claim 5, The aforementioned processor, The first delay time is updated by adding the estimated time deviation to the first delay time. The timing is determined by adding the updated first delay time to the first time. Extreme ultraviolet light generation system.

9. An extreme ultraviolet light generation system according to claim 8, The system further includes an image sensor that images a second region including the plasma generation region, The aforementioned processor, The first delay time is updated based on the difference between the position of the third target acquired by the image sensor and the reference target position. Extreme ultraviolet light generation system.

10. An extreme ultraviolet light generation system according to claim 9, The aforementioned reference target position is set in the plasma generation region. Extreme ultraviolet light generation system.

11. An extreme ultraviolet light generation system according to claim 9, A flash lamp that illuminates the target in the second region captured by the image sensor, A shutter that regulates the exposure time to the image sensor, Equipped with, The aforementioned processor, The first time, Based on the estimated time deviation, at least one of the following is determined: the image acquisition timing of the image sensor, the light emission timing of the flash lamp, and the operation timing of the shutter. Extreme ultraviolet light generation system.

12. An extreme ultraviolet light generation system according to claim 5, The aforementioned processor, At the first time mentioned above, The second delay time, The timing is determined by adding the estimated time deviation mentioned above. Extreme ultraviolet light generation system.

13. An extreme ultraviolet light generation system according to claim 12, The system further includes an image sensor that images a second region including the plasma generation region, The aforementioned processor, The second delay time is updated based on the difference between the position of the third target acquired by the image sensor and the reference target position. Extreme ultraviolet light generation system.

14. An extreme ultraviolet light generation system according to claim 13, The aforementioned reference target position is set in the plasma generation region. Extreme ultraviolet light generation system.

15. An extreme ultraviolet light generation system according to claim 13, A flash lamp that illuminates the target in the second region captured by the image sensor, A shutter that regulates the exposure time to the image sensor, Equipped with, The aforementioned processor, The first time, Based on the estimated time deviation, at least one of the following is determined: the image acquisition timing of the image sensor, the light emission timing of the flash lamp, and the operation timing of the shutter. Extreme ultraviolet light generation system.

16. A method for manufacturing electronic devices, Chamber and, A target supplyer that continuously generates targets at specific time intervals and supplies them into the chamber, A timing sensor that detects the target passing through the first region and outputs a signal, A laser device that irradiates pulsed laser light onto the target that has passed through the first region, The system comprises: a processor that determines from the signal a first time when the first target passed through the first region and a second time when a second target, generated immediately before the first target, passed through the first region, and determines the timing for irradiating the first target with the pulsed laser light of the laser device based on the first time, the second time, and the time interval; and an extreme ultraviolet light generation system that generates extreme ultraviolet light by irradiating the target with the pulsed laser light, The aforementioned extreme ultraviolet light is output to the exposure device, To manufacture an electronic device, the process involves exposing a photosensitive substrate to extreme ultraviolet light in the exposure apparatus, A method for manufacturing electronic devices.

17. A method for manufacturing electronic devices, Chamber and, A target supplyer that continuously generates targets at specific time intervals and supplies them into the chamber, A timing sensor that detects the target passing through the first region and outputs a signal, A laser device that irradiates pulsed laser light onto the target that has passed through the first region, The system includes a processor that determines from the signal a first time when the first target passed through the first region and a second time when the second target, which was generated immediately before the first target, passed through the first region, and determines the timing for irradiating the first target with the pulsed laser light of the laser device based on the first time, the second time, and the time interval, and inspects the mask for defects in the mask by irradiating the mask with the extreme ultraviolet light generated by an extreme ultraviolet light generation system that generates extreme ultraviolet light by irradiating the target with the pulsed laser light, Using the results of the above inspection, select a mask. This includes exposing and transferring the pattern formed on the selected mask onto a photosensitive substrate. A method for manufacturing electronic devices.

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