Extreme ultraviolet light generation system and method for manufacturing electronic devices

Abstract

The timing of pulsed laser beam irradiation was not corrected frequently enough, and when changes in target velocity occurred, it could not be adequately compensated for. [Solution] An extreme ultraviolet light generation system that generates plasma and produces extreme ultraviolet light by irradiating a target with pulsed laser light comprises a chamber, a target supplyer that supplies a target into the chamber, a target passage detection device that detects a target passing through a predetermined area, a laser device that irradiates pulsed laser light onto the target that has passed through the predetermined area, and a processor. The target passage detection device includes a light source that irradiates light onto a predetermined area, and a sensor that receives the light and outputs a signal corresponding to the amount of light received. The processor obtains the passage timing when the target is detected and the time width during which the target is detected from the signal, and determines the irradiation timing for irradiating with pulsed laser light from the laser device based on the passage timing and time width.

Description

Technical Field

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

Background Art

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

[0003] As an EUV light generation apparatus, the development of a Laser Produced Plasma (LPP) type apparatus that uses plasma generated by irradiating a target material with laser light has been progressing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0005] An extreme ultraviolet light generation system according to one aspect of the present disclosure is an extreme ultraviolet light generation system that generates plasma and generates extreme ultraviolet light by irradiating a target with pulsed laser light, comprising: a chamber; a target supplyer that supplies a target into the chamber; a target passage detection device that detects a target passing through a predetermined region; a laser device that irradiates pulsed laser light onto the target that has passed through the predetermined region; and a processor, wherein the target passage detection device includes a light source that irradiates light onto the predetermined region and a sensor that receives light and outputs a signal according to the amount of light received, and the processor obtains from the signal the passage timing when the target is detected and the time width during which the target is detected, and determines the irradiation timing for irradiating with pulsed laser light from the laser device based on the passage timing and time width.

[0006] A method for manufacturing an electronic device according to another aspect of the present disclosure is an extreme ultraviolet light generation system comprising: a chamber; a target supplyer for supplying a target into the chamber; a target passage detection device for detecting a target passing through a predetermined region; a laser device for irradiating the target with pulsed laser light after it has passed through the predetermined region; and a processor, wherein the system generates extreme ultraviolet light by irradiating the target with pulsed laser light to generate plasma and generate extreme ultraviolet light, the target passage detection device comprising: a light source for irradiating a predetermined region with light; and a sensor for receiving light and outputting a signal corresponding to the amount of light received; the processor obtains from the signal the passage timing and the time width during which the target is detected, and determines the irradiation timing for irradiating the laser device with pulsed laser light based on the passage timing and time width; the system generates extreme ultraviolet light, outputs the extreme ultraviolet light to an exposure apparatus, and exposes a photosensitive substrate with extreme ultraviolet light in the exposure apparatus in order to manufacture an electronic device.

[0007] A method for manufacturing an electronic device according to another aspect of the present disclosure is an extreme ultraviolet light generation system comprising: a chamber; a target supplyer for supplying a target into the chamber; a target passage detection device for detecting a target passing through a predetermined region; a laser device for irradiating the target that has passed through the predetermined region with pulsed laser light; and a processor, wherein the system generates plasma and generates extreme ultraviolet light by irradiating the target with pulsed laser light, the target passage detection device includes a light source for irradiating a predetermined region with light and a sensor for receiving light and outputting a signal corresponding to the amount of light received, the processor obtains from the signal the passage timing and the time width in which the target was detected, and determines the irradiation timing for irradiating the laser device with pulsed laser light based on the passage timing and time width, the system includes irradiating a mask with the extreme ultraviolet light generated by the extreme ultraviolet light generation system to inspect the mask for defects, selecting a mask using the inspection results, and exposing and transferring the 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 a PDA module. [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 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 schematically shows an example of an image acquired through the image sensor of the comparative example. [Figure 8] Figure 8 is a timing chart showing the generation timing of each trigger signal with corrected delay time. [Figure 9] Figure 9 shows the generation timing of each trigger signal generated by the trigger selection / delay device of the comparative example. [Figure 10] Figure 10 shows the configuration of the EUV light generation apparatus according to Embodiment 1. [Figure 11] Figure 11 is an explanatory diagram showing the calculation method for the timing correction amount Δtad in Embodiment 1. [Figure 12] Figure 12 shows the generation timing of each trigger signal generated by the trigger selection / delay device of Embodiment 1. [Figure 13] Figure 13 is an explanatory diagram of the operation of the pulse waveform processing device of Embodiment 1. [Figure 14] Figure 14 is a flowchart showing an example of the operation related to timing correction of the trigger signal in the EUV light generation apparatus according to Embodiment 1. [Figure 15] Figure 15 is a flowchart of the subroutine for updating the delay time that is applied to step S15 in Figure 14. [Figure 16] Figure 16 is an explanatory diagram of the rate coefficient update process in the EUV light generation apparatus according to Embodiment 2. [Figure 17] Figure 17 is a flowchart showing an example of the operation related to timing correction of the trigger signal of the EUV light generation device according to Embodiment 2. [Figure 18] Figure 18 is a flowchart showing the subroutine for updating the velocity coefficient applied in step S26 of Figure 17. [Figure 19] Figure 19 shows the configuration of the EUV light generation apparatus according to Embodiment 3. [Figure 20] Figure 20 is an explanatory diagram of various parameters used in the EUV light generation apparatus according to Embodiment 3. [Figure 21]FIG. 21 is a flowchart showing the flow of database creation processing in Embodiment 3. [Figure 22] FIG. 22 is a flowchart showing an example of update processing of the delay time of each trigger signal performed during EUV emission in Embodiment 3. [Figure 23] FIG. 23 is a chart showing an example of a database. [Figure 24] FIG. 24 is a chart showing an example of a database. [Figure 25] FIG. 25 is a chart showing an example of a database. [Figure 26] FIG. 26 is an explanatory diagram of an example of utilization of the databases shown in FIGS. 23 to 25. [Figure 27] FIG. 27 is an explanatory diagram of a target detection signal obtained by connecting the outputs of two adjacent sensor elements. [Figure 28] FIG. 28 schematically shows the configuration of an exposure apparatus connected to an EUV light generation apparatus. [Figure 29] FIG. 29 schematically shows the configuration of an inspection apparatus connected to an EUV light generation apparatus. Embodiment

[0009] -Contents- 1. Explanation of Terms 2. Overall Explanation of EUV Light Generation System 2.1 Configuration 2.2 Operation 3. EUV Light Generation Apparatus According to Comparative Example 3.1 Configuration 3.2 Operation 4. Problems 5. Embodiment 1 5.1 Configuration 5.2 Operation 5.3 Relationship between Detection Signal Obtained from Target Passage Detection Apparatus and Threshold Value 5.4 Function and Effect ​​​​​​​​​​​ 7.2 Operation 7.2.1 Creating a Database 7.2.2 Operation during EUV emission 7.2.3 Specific Examples 7.3 Action and Effects 8. Embodiment 4 8.1 Configuration 8.2 Operation 8.3 Action and Effects 9. Method for manufacturing electronic devices 10. About the processor 11. Other

[0010] 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.

[0011] 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.

[0012] A "droplet" is a form of target supplied into the chamber.

[0013] "Plasma light" is synchrotron radiation emitted from a plasma-enhanced target. This synchrotron radiation includes EUV light.

[0014] 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.

[0015] 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.

[0016] 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 292. 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.

[0017] 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.

[0018] 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, there is a wall 291 in which an aperture 293 is formed. The wall 291 is positioned such that its aperture 293 is located at the second focal point of the EUV focusing mirror 23.

[0019] 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.

[0020] 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.

[0021] 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 292 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] At least the interior of the tank 261 is composed 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.

[0030] 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.

[0031] 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.

[0032] The plasma generation region 25, located inside the chamber 2, is situated on the extension of the central axis direction of the nozzle 262.

[0033] The target supply unit 26 includes a heater 711 and a heater power supply 712, which serve as mechanisms 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] The target supply unit 26 includes a pressure regulator 721 that regulates the pressure in 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 maintained at approximately the same temperature as the temperature inside the tank 261.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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, or it can also be called the target generation frequency. The piezo frequency f0 is, for example, about 180 kHz, and the droplet generation period (1 / f0 period) is, for example, about 0.005 ms.

[0049] 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.

[0050] 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. The stage 265 may also move the target feeder 26 in a direction substantially perpendicular to the direction of the target trajectory F.

[0051] 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.

[0052] 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.

[0053] Stage 265 may move the target supply 26 based on control signals from the arithmetic control processor 51. This allows the position of the target 27 output into the chamber 2 in the X and Z directions to be adjusted so that the target 27 reaches the target position.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The illuminator 71 emits illumination light, which is continuous light, onto the droplet 271 as it travels along the target trajectory F. The continuous light irradiated onto the droplet 271 may be continuous laser light.

[0060] 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).

[0061] 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.

[0062] 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 that includes 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".

[0063] 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 irradiated from the illuminator 71 may be different from an ellipse.

[0064] 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.

[0065] 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.

[0066] The imaging optical system 84 may be an optical system such as a collimator. This optical system such as a collimator may be 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 the filter 82.

[0067] The optical sensor 86 may be a light-receiving element including a photodiode. The optical sensor 86 may be a photodiode array including multiple sensor elements. The optical sensor 86 outputs an electrical signal corresponding to the amount of light received. The optical sensor 86 detects the light intensity of the continuous laser light guided by the imaging optical system 84.

[0068] 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".

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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 moves along the target trajectory F.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] Image data generated using the image sensor 107 is sent to the arithmetic control processor 51.

[0084] 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 commonly referred to as a "size sensor."

[0085] 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.

[0086] 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.

[0087] 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.

[0088] The imaging trigger signal controls the imaging timing of the image sensor 107. The shutter trigger signal controls the opening and closing timing (operation timing) of the shutter 105. The light emission trigger signal controls the light emission timing of the flash lamp 92. The laser trigger signal controls the irradiation timing of the pulsed laser light 33 of the laser device 3.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] The target passage detection device 70 irradiates a sheet-shaped (elliptical beam-shaped) CW 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.

[0097] 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.

[0098] 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.

[0099] 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%".

[0100] When the droplet 271, ejected at a piezo frequency f0 (approximately 180 kHz), passes through the target detection area of ​​the target passage detection device 70, the detection signal output from the PDA module decreases.

[0101] 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 generated from this detection signal.

[0102] 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.

[0103] 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 two points as the timing of passing through the target 27. Specifically, if the passing timing is denoted as ta, then ta is calculated by the following equation.

[0104] ta = (t1 + t2) / 2 The timing at t1 is called the "signal drop timing," and the timing at 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.

[0105] As shown in the lower part of Figure 4, the pulse waveform processing device 55 outputs a target detection trigger signal with respect to the passing timing ta.

[0106] Figures 5 and 6 show examples of the generation timing of each trigger signal generated by the trigger selection / delay device 53.

[0107] The top panel of Figure 5 shows an example of a target detection trigger signal, the middle panel shows an example of a target detection trigger signal for EUV emission, and the bottom panel shows an example of a target detection trigger signal for image measurement.

[0108] A target detection trigger signal is generated for each of the droplets 271, for example, at a piezoelectric frequency of approximately 180 kHz.

[0109] 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.

[0110] [Operation 1] Since EUV emission is performed at a frequency of approximately 20 kHz or 40 kHz, the trigger selection / delay device 53 generates a target detection trigger signal for EUV emission by downsampling the target detection trigger signal to achieve that frequency.

[0111] [Operation 2] Since the measurement of the target 27 by the target image measurement device 90 is performed at approximately 5 Hz, the trigger selection / delay device 53 further reduces the target detection signal for EUV emission to generate a target detection trigger signal for image measurement.

[0112] Figure 6 shows examples of trigger signals, from top to bottom: an EUV emission target detection trigger signal or an image measurement target detection trigger signal, an imaging trigger signal, an emission trigger signal, a shutter trigger signal, and a laser trigger signal.

[0113] The trigger selection / delay device 53 receives delay time information from the arithmetic control processor 51 and generates various trigger signals.

[0114] The delay time information received by the trigger selection / delay device 53 includes a delay time Δti applied to the imaging trigger signal, a delay time Δtf applied to the light emission trigger signal, a delay time Δts applied to the shutter trigger signal, and a delay time Δtl applied to the laser trigger signal.

[0115] The trigger selection / delay device 53 generates a laser trigger signal by adding a delay time Δtl to the EUV emission target detection trigger signal.

[0116] The trigger selection / delay device 53 generates an imaging trigger signal, a light emission trigger signal, and a shutter trigger signal, respectively, by adding delay times (Δti, Δtf, Δts) to operate the target image measurement device 90 based on the target detection signal for image measurement.

[0117] The operation for periodic delay time correction based on information obtained from the target image measurement device 90 is as follows:

[0118] First, as shown in Figure 6, the image sensor 107 receives an imaging trigger signal generated with a delay of Δti from the image measurement target detection trigger signal, and starts exposure for a certain period of time.

[0119] The flash lamp 92 receives a light emission trigger signal generated with a delay of Δtf from the target detection trigger signal for image measurement, and emits light for a certain period of time. The light emitted by the flash lamp 92 illuminates 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.

[0120] Shutter 105 receives a shutter trigger signal generated with a delay of Δts from the target detection trigger signal for image measurement, and applies a voltage for a certain period of time (opening shutter 105).

[0121] Light passing through shutter 105 passes through imaging optical system 106 and reaches image sensor 107. The two imaging optical systems 104 and 106 transfer an image of the plasma generation region 25 onto image sensor 107, so that an image including the shadow image of target 27 in the plasma generation region 25 is output from image sensor 107.

[0122] Figure 7 schematically shows an example of an image 99 acquired via the image sensor 107. The image sensor 107 captures an image 99 that includes the shadow images of multiple targets 27 sequentially output from the nozzle 262. The arithmetic control processor 51 reads the image 99 output from the image sensor 107, performs image processing 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.

[0123] V=ΔP×f0 (Formula 1) To give a specific example, if the target spacing ΔP is, for example, 250 μm and the piezoelectric frequency f0 is, for example, 180 kHz, then the target velocity V is 45 m / s.

[0124] The arithmetic control processor 51 calculates the amount of deviation ΔH when the height of the target 27 on the output image 99 deviates from the reference target height corresponding to the plasma generation region 25. The amount of deviation ΔH is referred to as the "target height deviation ΔH". The arithmetic control processor 51 calculates the timing deviation Δtd from the target height deviation ΔH and the target velocity V.

[0125] Δtd = ΔH / V ... (Equation 2) The unit of the timing deviation Δtd 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).

[0126] Note that the term "height" for target 27 refers to its position in the target's direction of travel (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 positive value, and when it is on the opposite side (target retrieval device 28 side), it takes a negative value. The target height deviation ΔH is caused by a change in the target velocity V.

[0127] The timing deviation Δtd calculated by Equation 2 is the timing correction amount. The term "timing correction amount" is synonymous with "timing correction time."

[0128] The arithmetic control processor 51 uses this deviation amount Δtd to correct the delay times Δti, Δtf, Δts, and Δts of each trigger signal, and transmits the corrected delay time information to the trigger selection / delay device 53.

[0129] In other words, the arithmetic control processor 51 adds the deviation amount Δtd to the current delay time Δti to correct the delay time and calculates a new (corrected) delay time Δti.

[0130] Δti = Δti + Δtd The left-hand side of the equation represents the corrected delay time, while Δti on the right-hand side represents the current (uncorrected) delay time.

[0131] Similarly, the arithmetic control processor 51 calculates new delay times for the light emission trigger signal Δtf, the shutter trigger signal Δts, and the laser trigger Δtl, using the displacement amount Δtd.

[0132] Δtf = Δtf + Δtd Δts = Δts + Δtd Δtl = Δtl + Δtd Hereafter, for the sake of simplicity, Δti, Δtf, Δts, and Δtl will be collectively referred to as "Δti (or f or s or l)". The notation "i (or f or s or l)" indicates that the subscript is one of "i", "f", "s", or "l".

[0133] Figure 8 is a timing chart showing the generation timing of each trigger signal with corrected delay time.

[0134] The trigger selection / delay device 53 transmits a trigger signal to each device at a timing ti (or f or s or l) which is the delay time Δti (or f or s or l) of the modified trigger signal, in synchronization with the timing ta of the target 27 passing by.

[0135] ti(or f or s or l)=ta+Δti(or f or s or l) The trigger selection / delay device 53 operates with Δti (or f or s or l) fixed until the next periodic delay time Δti (or f or s or l) is corrected.

[0136] 4. Challenges In the comparative example EUV light generator 1, the timing shift of the pulsed laser light 33 due to the change in the velocity of the target 27 is corrected using the processing result of the image 99 obtained by the target image measuring device 90. Therefore, the timing shift correction was performed at a low frequency, such as the image acquisition frequency of 99, for example, 5 Hz (imaging time interval of 200 ms).

[0137] However, the velocity of the target 27 also changes during the 200ms imaging interval of the target image measurement device 90, and the EUV light generation device 1 in the comparative example cannot adequately correct for the timing difference of the irradiation.

[0138] In other words, as shown by the dashed ellipse in Figure 9, 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 the change in the velocity of the target 27 used for EUV light generation during this period cannot be corrected.

[0139] 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.

[0140] 5. Embodiment 1 5.1 Configuration Figure 10 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 10 and the EUV light generator 1 shown in Figure 2 will be explained below.

[0141] The 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. The processor 5A includes an arithmetic control processor 51A and a trigger selection / delay device 53A.

[0142] In the EUV light generator 1A, the target passage detection device 70 (timing sensor) is used to measure the change in velocity of the target 27 and correct the timing deviation caused by the change in velocity.

[0143] The pulse waveform processing device 55A calculates a new time width Δtx at the time of target passage from the waveform of the detection signal obtained from the target passage detection device 70. This time width Δtx may be, for example, the time width from the signal drop timing t1 to the signal recovery timing t2 (Δtx = t2 - t1).

[0144] The trigger selection / delay device 53A calculates a timing correction amount Δtad based on the distance ΔQ from the target passage detection height to the reference target height, the distance ΔL that the target 27 moves from the target position where the detection signal output from the target passage detection device 70 falls below the threshold th to the target position where the detection signal recovers to the threshold th, and the time width Δtx, and updates the timing correction amount Δtad. By updating the timing correction amount Δtad, the trigger selection / delay device 53A updates the delay time Δti (or f or s or l) of each trigger signal. The distance ΔL is called the velocity coefficient. Other configurations may be the same as in Figure 2.

[0145] 5.2 Operation In Embodiment 1, the delay time Δti (or f or s or l) of each trigger signal is newly decomposed and defined as shown in Equation 3 below.

[0146] Δti(or f or s or l)=Δtai(or f or s or l)+Δtad (Equation 3) In the formula, Δtai (or f or s or l) is the individual delay time for the operation of each device. Δtai is the delay time for the operation of the image sensor 107, Δtaf is the delay time for the operation of the flash lamp 92, Δtas is the delay time for the operation of the shutter 105, and Δtal is the delay time for the operation of the laser device 3. Δtai (or f or s or l) is a fixed value and is a negative value.

[0147] Δtad is the time it takes for target 27 to travel the distance ΔQ from the target passage detection height to the reference target height. This Δtad is called the timing correction amount.

[0148] Figure 11 is an explanatory diagram showing the calculation method for the timing correction amount Δtad in Embodiment 1. The target passage detection height shown in Figure 11 is the height of the target detection region where the target 27 is detected by the target passage detection device 70, and is the height at which the CW laser light from the illuminator 71 is irradiated onto the target trajectory F.

[0149] The target 27, emitted from the nozzle hole 262a of the nozzle 262, travels toward the plasma generation region 25. The distance ΔQ from the target passage detection height to the reference target height within the plasma generation region 25 is a fixed value. The target velocity V may vary depending on the target 27. The reference target height may be the same as or different from the target plasma generation height. It is desirable that the reference target height be approximately the same as the target plasma generation height.

[0150] The reference target height is an example of a “reference position” in this disclosure.

[0151] Figure 12 shows examples of the generation timing of each trigger signal generated by the trigger selection / delay device 53A. Similar to Figure 6, Figure 12 shows examples of trigger signals for EUV emission target detection trigger signal or image measurement target detection trigger signal, imaging trigger signal, emission trigger signal, shutter trigger signal, and laser trigger signal. In Figure 12, the delay time for each trigger signal is defined by Equation 3, which is different from Figure 6.

[0152] Figure 13 is an explanatory diagram of the operation of the pulse waveform processing device 55A. The graph F13A shown in the upper part of Figure 13 shows an example of a detection signal obtained from the target passage detection device 70. The waveform Gr shown by the thick line in graph F13A shows the time change in the signal intensity of the detection signal. Figure F13B in the lower part of Figure 13 is a schematic diagram showing the relative positional relationship between the target 27 moving in the direction of target movement and the light-receiving surface of the sensor element 871 in a time series.

[0153] The pulse waveform processing device 55A calculates the passage timing ta based on the detection signal obtained from the target passage detection device 70, as described in Figure 4. The timing indicated by t1 is an example of the "first timing" in this disclosure, and the timing indicated by t2 is an example of the "second timing" in this disclosure.

[0154] The pulse waveform processing device 55A compares the detection signal output from the target passage detection device 70 with a threshold th, and calculates the time width Δtx from the signal drop timing t1, which is the point when the detection signal falls below the threshold th, to the signal recovery timing t2, which is the point when the signal recovers to the threshold th.

[0155] Δtx=t2-t1 (Equation 4) The time interval Δtx corresponds to the duration during which the detected signal is below the threshold th.

[0156] The trigger selection / delay device 53A calculates the target velocity V using the distance ΔL that the target 27 moves from the target position where the detection signal from the target passage detection device 70 falls below the threshold th to the target position where it recovers to the threshold th, and the time width Δtx.

[0157] V = ΔL / Δtx (Equation 5) The target position where the detected signal falls below the threshold th corresponds to the position of target 27 at the signal drop timing t1. The target position where the detected signal recovers to the threshold th corresponds to the position of target 27 at the signal recovery timing t2. As shown in Figure 13, the distance ΔL is a fixed value determined by the relationship between the size of the light-receiving surface of the sensor element 871, the diameter of target 27, and the threshold th. The distance ΔL is referred to as the velocity coefficient ΔL.

[0158] The trigger selection / delay device 53A calculates a timing correction amount Δtad based on the target velocity V calculated by equation 5 and the distance ΔQ obtained from the arithmetic control processor 51A.

[0159] Δtad=ΔQ / V=ΔQ / (ΔL / Δtx) (Equation 6) Note that Δtad always takes a positive value.

[0160] The trigger selection / delay device 53A updates the delay time Δti (or f or s or l) of each trigger signal in Equation 3 using the calculated timing correction amount Δtad.

[0161] Figure 14 is a flowchart illustrating an example of the operation related to timing correction of the trigger signal in the EUV light generator 1A. The operation of the processor 5A and the pulse waveform processing device 55A will be explained using Figure 14. Figure 14 shows an example of the processing performed on the target 27 for EUV emission.

[0162] In step S10, processor 5A starts EUV emission.

[0163] In step S11, processor 5A determines whether or not to terminate EUV emission. If the result of the determination in step S11 is NO, the process proceeds to step S13.

[0164] In step S13, the EUV emission target 27 passes through the target detection area of ​​the target passage detection device 70.

[0165] In step S14, the pulse waveform processing device 55A measures the passing timing ta from the detection signal output from the target passing detection device 70, in the same manner as in Figure 4. That is, the pulse waveform processing device 55A measures the midpoint between the signal drop timing t1 and the signal recovery timing t2 as the passing timing ta. Instead of determining the passing timing ta from t1 and t2, the passing timing ta may be detected as the point in time when the detection signal in Figure 13 is at its minimum (lower peak).

[0166] In step S15, the trigger selection / delay device 53A performs an update process for the delay time Δti (or f or s or l). Details of the process applied in step S15 will be described later with reference to Figure 15.

[0167] In step S16, the trigger selection / delay device 53A transmits each trigger signal generated using the delay time Δti (or f or s or l) updated in step S15 to each device. The trigger selection / delay device 53A transmits the trigger signal to each device at a timing that is synchronized with the target 27's passing timing ta, by adding the delay time Δti (or f or s or l) updated in step S15 to this passing timing ta.

[0168] The trigger selection / delay device 53A transmits each trigger signal ti (or f or s or l) at the following timings.

[0169] ti(or f or s or l)=ta+Δti(or f or s or l) After step S16, the process returns to step S11.

[0170] If the result of step S11 is YES, the process proceeds to step S18, and processor 5 terminates EUV emission.

[0171] Figure 15 is a flowchart of the delay time update subroutine applied to step S15 in Figure 14. When the processing of step S15 begins, in step S151, the pulse waveform processing device 55A acquires the waveform of the detection signal from the target passage detection device 70 when the EUV emission target is passed.

[0172] In step S152, the pulse waveform processing device 55A compares the detection signal from the target passage detection device 70 with a threshold th and calculates the timing t1 when the detection signal falls below the threshold th and the timing t2 when it recovers to the threshold th.

[0173] In step S153, the pulse waveform processing unit 55A calculates the time width Δtx when passing the target from timings t1 and t2. The pulse waveform processing unit 55A calculates the time width Δtx using equation 4.

[0174] In step S154, the trigger selection / delay device 53A calculates the target velocity V from the time width Δtx and the velocity coefficient ΔL. The trigger selection / delay device 53A calculates the target velocity V using equation 5.

[0175] In step S155, the trigger selection / delay device 53A calculates the timing correction amount Δtad from the target velocity V and distance ΔQ. The trigger selection / delay device 53A calculates the timing correction amount Δtad using equation 6.

[0176] As is clear from Equation 6, the processing in step S154 may be included within the processing in step S155. In other words, the trigger selection / delay device 53A is understood to be essentially calculating the target velocity V by calculating (ΔQ / ΔL)·Δtx in step S155.

[0177] In step S156, the trigger selection / delay device 53A updates the delay time Δti (or f or s or l) of each trigger signal according to equation 3.

[0178] After step S156, the process returns to the flowchart in Figure 14.

[0179] The transmission frequency of each trigger signal may differ depending on the device. For example, the laser trigger signal tl may be transmitted at a frequency of 20 kHz, while the imaging trigger signal ti may be transmitted at a frequency of 5 Hz.

[0180] 5.3 Relationship between detection signals obtained from target passage detection device and thresholds Figure 13 shows an example where the detection signal decreases upon passing the target 27. However, the detection signal obtained from the target passage detection device 70 is not limited to this example; it may also increase upon passing the target 27. For example, a detection signal that increases upon passing the target 27 can be generated by inverting the detection signal shown in Figure 13. In this case, the time width Δtx is calculated from the timing t1 when the threshold th is exceeded and the timing t2 when it recovers to the threshold th.

[0181] As illustrated in Figure 13, if the detection signal decreases upon passing through target 27, the timing t1 at which it falls below the threshold th is an example of a “timing at which it exceeds the threshold” in this disclosure. The phrase “exceeding the threshold” includes the concept of the case where it exceeds and falls below the threshold th, as shown in Figure 13.

[0182] 5.4 Action and Effects According to the EUV light generator 1A of Embodiment 1, the laser irradiation timing can be corrected for the continuous target 27 used for EUV emission, and the decrease in EUV emission performance due to changes in the velocity of the target 27 can be suppressed. Furthermore, according to the EUV light generator 1A, fragmentation caused by the relative positional misalignment between the target 27 and the pulsed laser beam 33 can be suppressed, and contamination of the EUV focusing mirror 23 can be suppressed.

[0183] 6. Embodiment 2 6.1 Configuration The configuration of the EUV light generation apparatus according to Embodiment 2 is the same as that of the EUV light generation apparatus 1A, but differs from Embodiment 1 in the following respects.

[0184] In other words, in the EUV light generation apparatus 1A according to Embodiment 2, the target height deviation ΔH, which is the difference between the target 27 and the target target position (reference target height), is calculated from the target image captured by the target image measurement device 90 by image processing, and the velocity coefficient ΔL in Embodiment 1 is corrected based on ΔH.

[0185] After adjusting the timing of the trigger signal using the timing correction amount Δtad determined in Embodiment 1, when the target image is captured by the target image measuring device 90, there may be a slight misalignment between the target 27 and the target position in the image.

[0186] This is because changes in the size of the target 27 and changes in the target passage position cause changes in the detection signal output from the target passage detection device 70. As a result, when a constant (fixed) velocity coefficient ΔL is used, the target velocity V cannot be accurately determined from the time width Δtx using equation 5, and a shift occurs in the target height (position of the target 27) in the plasma generation region 25.

[0187] 6.2 Operation Figure 16 is an explanatory diagram of the update process of the velocity coefficient ΔL in the EUV light generation apparatus 1A according to Embodiment 2. The arithmetic control processor 51A obtains the target height displacement ΔH from the image 99 measured by the target image measurement device 90, updates the velocity coefficient ΔL according to the following equation 7, and transmits the updated velocity coefficient ΔL to the trigger selection / delay device 53A.

[0188] ΔL = (ΔQ - ΔH) × ΔL / ΔQ (Equation 7) In Equation 7, ΔL on the left side represents the velocity coefficient after the update (correction), and ΔL on the right side represents the velocity coefficient before the update (current state).

[0189] The update process for the velocity coefficient ΔL may be performed only if the target image measurement device 90 has calculated ΔH.

[0190] The derivation of Equation 7 is explained below.

[0191] When the velocity coefficient is ΔL1, if a target height shift ΔH occurs in the image 99 captured by the target image measuring device 90 after updating the timing correction amount Δtad1, the distance (ΔQ-ΔH) that the target 27 travels within the time of the timing correction amount Δtad1 (=ΔQ×Δtx / ΔL1) is expressed by the following equation 8, where V is the velocity of the target 27.

[0192] ΔQ-ΔH=V×ΔQ×Δtx / ΔL1 (Formula 8) Assuming that a target 27 with the same velocity V has a velocity coefficient of ΔL2, and that no target height shift ΔH occurs in image 99 after updating the timing correction amount Δtad, the distance ΔQ that the target 27 travels within the time of the timing correction amount Δtad2 (=ΔQ × Δtx / ΔL2) is expressed by the following equation 9.

[0193] ΔQ=V×ΔQ×Δtx / ΔL2 (Formula 9) From equations 8 and 9, the velocity coefficient ΔL2, corrected so that ΔH is zero, can be expressed using the previously obtained velocity coefficient ΔL1 as shown in equation 10 below.

[0194] ΔL2=(ΔQ-ΔH)×ΔL1 / ΔQ (Equation 10) Therefore, based on the result of Equation 10, updating the velocity coefficient ΔL using Equation 7 will eliminate the target height displacement ΔH.

[0195] Figure 17 is a flowchart illustrating an example of the operation related to timing correction of the trigger signal of the EUV light generator 1A according to Embodiment 2. The differences between Figure 17 and the flowchart in Figure 14 will be explained below.

[0196] In Figure 17, step S25 is added between step S14 and step S15, and step S26 is added, which branches parallel to step S25.

[0197] In step S25, the arithmetic control processor 51A determines whether or not to update the speed coefficient ΔL. If the result of the determination in step S25 is YES, the process proceeds to step S26 in parallel.

[0198] In step S26, the velocity coefficient ΔL is updated. Details of the process applied in step S26 will be described later with reference to Figure 18. After step S26, step S26 is completed and the parallel processing ends. The processing in step S26 is performed in parallel with steps S11 to S16.

[0199] Furthermore, if the result of step S25 is NO, the process proceeds to step S15. The other steps are the same as in Figure 14.

[0200] Figure 18 is a flowchart showing the subroutine for updating the velocity coefficient ΔL, which is applied in step S26 of Figure 17.

[0201] When the parallel processing in step S26 begins, in step S261, the arithmetic control processor 51A acquires an image 99 of the target 27 from the target image measuring device 90.

[0202] In step S262, the arithmetic control processor 51A calculates the target height shift ΔH from the acquired image 99.

[0203] In step S263, the arithmetic control processor 51A updates the velocity coefficient ΔL according to equation 7. The arithmetic control processor 51A transmits the updated velocity coefficient ΔL to the trigger selection / delay device 53A.

[0204] After step S263, the parallel processing in step S26 is completed, and only the loop processing from step S11 to step S16 is performed.

[0205] 6.3 Action and Effects According to Embodiment 2, by periodically updating the velocity coefficient ΔL based on the image 99 obtained from the target image measuring device 90, the target height deviation ΔH caused by changes in the size of the target 27 and the target passage position dy can be corrected.

[0206] 7. Embodiment 3 7.1 Configuration Figure 19 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 1A will be explained below.

[0207] The EUV light generator 1C includes a pulse waveform processing unit 55C and a processor 5C instead of the pulse waveform processing unit 55A and processor 5A shown in Figure 10. The processor 5C includes an arithmetic control processor 51C and a trigger selection / delay device 53C.

[0208] EUV light generator 1C differs from EUV light generator 1A in that it creates a database (see Figures 20, 23-25) that defines the relationship between the target diameter Rd, the target passage position d, the passage signal height ΔDa, the passage signal height ΔDb, and the velocity coefficient ΔL, and uses this database to perform a process to correct the velocity coefficient ΔL. The target diameter Rd is an example of an index representing the size of the target 27.

[0209] Other configurations may be the same as those of the EUV light generator 1A.

[0210] 7.2 Operation 7.2.1 Creating a Database Figure 20 is an explanatory diagram of various parameters used in the EUV light generator 1C. The upper part of Figure 20, F20A, schematically shows the image of the target 27 formed on the light-receiving surfaces of two adjacent sensor elements 871 and 872 of the optical sensor 86 in the target passage detection device 70. Sensor element 871 is designated as channel A (Ch.A), and sensor element 872 is designated as channel B (Ch.B). Sensor element 871 is an example of the "first sensor element" in this disclosure, and sensor element 872 is an example of the "second sensor element" in this disclosure. "Adjacent" is an example of "adjacent" in this disclosure.

[0211] The arrangement direction of the sensor elements 871 and 872 may be, for example, the Z direction. The direction in which the target 27 moves is, for example, the Y direction. The Y direction is an example of a “first direction” in this disclosure, and the Z direction is an example of a “second direction” in this disclosure. The optical sensor 86, which includes the sensor elements 871 and 872, is an example of a “sensor” in this disclosure.

[0212] Graph F20B in the lower left of Figure 20 shows the detection signal obtained from sensor element 871. Graph F20C in the lower right of Figure 20 shows the detection signal obtained from sensor element 871. The detection signal output by sensor element 871 (graph F20B) is an example of the "first signal" in this disclosure, and the detection signal output by sensor element 872 (graph F20C) is an example of the "second signal" in this disclosure.

[0213] The target passage position dy is the position where the target 27 passes in the direction of the arrangement of sensor elements 871 and 872 (e.g., the Z direction), and is defined as the distance from the center of sensor element 871 to the center of target 27, with the center of sensor element 871 as the reference point. The target passage position dy can be changed by moving the stage 265.

[0214] The target diameter Rd represents the diameter of target 27.

[0215] The EUV light generator 1C performs the following [Process 1] to [Process 4] in order to create a database.

[0216] [Process 1] The arithmetic control processor 51C measures the target 27 with the target passage detection device 70 while changing the piezoelectric frequency f0 of the target supply device 26 and the target passage position dy. The pulse waveform processing device 55C calculates the time width Δtxa and the passage signal heights ΔDa and ΔDb from the detection signals of two adjacent sensor elements 871 and 872 of the target passage detection device 70. However, ΔDa ≥ ΔDb.

[0217] When the nozzle diameter is Rn, the target diameter Rd is changed by adjusting the piezoelectric frequency f0, according to equation 11 below.

[0218]

number

[0219] The time interval Δtxa is calculated as the time during which the detection signal from the sensor element 871 is below (or above) the threshold th. The method for calculating the time interval Δtxa is the same as the method for calculating the time interval Δtx described in Figure 13. The time interval Δtxa is an example of the "first time interval" in this disclosure.

[0220] [Process 2] The arithmetic control processor 51C performs process 1 and, using equation 1, calculates the target velocity V from the target interval ΔP of the image 99 acquired by the target image measuring device 90 and the piezoelectric frequency f0, and sends it to the trigger selection / delay device 53C.

[0221] [Process 3] The trigger selection / delay device 53C calculates the velocity coefficient ΔL from the time width Δtxa and the target velocity V.

[0222] ΔL = V·Δtxa (Equation 12) [Process 4] The trigger selection / delay device 53C stores in advance the relationships between ΔDa, ΔDb, and ΔL when dy and Rd are changed by the above processes 1 to 4 as a database (see Figures 23 to 25).

[0223] Figure 21 is a flowchart showing the flow of the database creation process in the EUV light generation device 1C.

[0224] Here, we will explain an example in which the target diameter Rd is changed by a predetermined amount ΔRd from the initial value Rd_start to the closing value Rd_end, and the target passing position dy is changed by a predetermined amount Δdy from the initial value dy_start to the closing value dy_end, and then ΔDa, ΔDb, and ΔL are calculated.

[0225] In step S31, the arithmetic control processor 51C adjusts the piezoelectric frequency f0 so that the target diameter Rd becomes the initial value Rd_start. Rd_start may be, for example, 12 μm.

[0226] In step S32, the arithmetic control processor 51C adjusts the position of the stage 265 so that the target passage position dy becomes the initial value dy_start. dy_start may be, for example, 0 μm.

[0227] In step S33, the pulse waveform processing device 55C measures the passing signal height ΔDa, the passing signal height ΔDb, and the time width Δtxa based on the detection signals obtained from two adjacent sensor elements 871 and 872 of the target passing detection device 70.

[0228] In step S34, the arithmetic control processor 51C measures the target velocity V from the image 99 obtained from the target image measuring device 90.

[0229] In step S35, the trigger selection / delay device 53C calculates the velocity coefficient ΔL from the time width Δtxa and the target velocity V using equation 12.

[0230] In step S36, the trigger selection / delay device 53C stores the values ​​of the passing signal height ΔDa, the passing signal height ΔDb, and the velocity coefficient ΔL in the database, linked to dy and Rd.

[0231] In step S37, the arithmetic control processor 51C determines whether dy matches dy_end. If the determination result in step S37 is No, the process proceeds to step S38. In step S38, the arithmetic control processor 51C updates the value of dy by adding a predetermined change amount Δdy to the current value of dy and adjusts the position of the stage 265 so that dy = dy + Δdy. The change amount Δdy may be, for example, 1 μm. After step S38, the process returns to step S33.

[0232] If the result of the judgment in step S37 is a Yes judgment, that is, if dy has reached dy_end, the process proceeds to step S39.

[0233] In step S39, the arithmetic control processor 51C adjusts the position of the stage 265 so that dy = dy_start.

[0234] After step S39, in step S40, the arithmetic control processor 51C determines whether the target diameter Rd matches the closing price Rd_end. If the result of the determination in step S40 is No, the process proceeds to step S42.

[0235] In step S42, the arithmetic control processor 51C updates the value of Rd by adding a predetermined change amount ΔRd to the current value of Rd, and adjusts the piezoelectric frequency f0 so that Rd = Rd + ΔRd. The change amount ΔRd may be, for example, 1 μm. After step S42, the process returns to step S33.

[0236] The process from step S33 to step S42 is repeated until Rd matches Rd_end. If the result of the determination in step S40 is Yes, the database creation process is terminated.

[0237] Note that the database creation process shown in the flowchart of Figure 21 is performed during the preparation phase without EUV emission.

[0238] The database thus created is used to determine the delay time of each trigger signal during EUV emission. It is not necessary to create such a database for each individual EUV light generator 1C; one database per model is sufficient. A database created by an EUV light generator 1C of the same model can be applied to other units of the same model.

[0239] 7.2.2 Operation during EUV emission Next, we will explain the operation during EUV emission. Figure 22 is a flowchart showing an example of the delay time update process for each trigger signal performed during EUV emission in Embodiment 3.

[0240] The delay time update process shown in Figure 22 may be applied to step S15 in Figure 14.

[0241] In step S50, the delay time update process is initiated.

[0242] In step S51, the pulse waveform processing device 55C acquires the waveforms of the detection signals of two adjacent sensor elements 87 when the target is passed from the target passage detection device 70.

[0243] In step S52, the pulse waveform processing device 55C measures the transmission signal height ΔDa, ΔDb, and time width Δtxa from the detection signals obtained from the two sensor elements 87, where ΔDa ≥ ΔDb. The two sensor elements 87 here may be any two adjacent sensor elements 87 from the nine sensor elements 87 shown in Figure 3.

[0244] In step S53, the trigger selection / delay device 53C selects the database element with the value closest to the combination of pass signal height ΔDa and pass signal height ΔDb. A specific example of step S53 will be described later with reference to Figure 26.

[0245] In step S54, the trigger selection / delay device 53C selects a velocity coefficient ΔL corresponding to the element selected from the database.

[0246] In step S55, the trigger selection / delay device 53C calculates the target speed V from the time width Δtxa and the speed coefficient ΔL selected from the database.

[0247] V = ΔL / Δtxa (Equation 13) In step S56, the trigger selection / delay device 53C calculates the timing correction amount Δtad from the distance ΔQ and the target speed V using Equation 6.

[0248] In step S57, the trigger selection / delay device 53C updates the delay time Δti (or f or s or l) according to Equation 3 using the calculated timing correction amount Δtad.

[0249] After step S57, the process returns to the flowchart of FIG. 14.

[0250] 7.2.3 Specific Example Figures 23 to 25 show examples of databases created by the EUV light generation device 1C. When the range of 10 to 20 μm for the target passing position dy is changed in three levels at 5-μm steps and the range of 12 to 18 μm for the target diameter Rd is changed in seven levels at 1-μm steps, the data of ΔDa, ΔDb, and ΔL are shown in tabular form as Tables 1 to 3 shown in Figures 23 to 25.

[0251] Figure 26 is a graph of the databases in Figures 23 to 25. The horizontal axis of Figure 26 indicates the value of the passing signal height ΔDa or ΔDb, and the vertical axis indicates the value of the speed coefficient ΔL.

[0252] For example, let's consider the case where the values ​​of ΔDa and ΔDb obtained in step S52 are ΔDa = 0.24 and ΔDb = 0.08, respectively. In this case, if we focus on the value of ΔDa and refer to the database, the areas enclosed by the frame indicated by symbol A in Figure 24 and the areas enclosed by the frame indicated by symbol B in Figure 25 are extracted as being close to ΔDa = 0.24. Of these, if we further focus on the value of ΔDb, the area enclosed by symbol A in Figure 24 is closer to ΔDb = 0.08.

[0253] Therefore, in this case, the trigger selection / delay device 53C selects the velocity coefficient ΔL element indicated by symbol A from the database shown in Figure 24. That is, 32.0 μm is applied as the value of the velocity coefficient ΔL.

[0254] 7.3 Action and Effects According to Embodiment 3, it becomes possible to update the velocity coefficient ΔL using only information from the target passage detection device 70, without waiting for measurements by the target image measurement device 90. Therefore, according to Embodiment 3, it becomes possible to correct deviations in target height due to changes in target diameter Rd and target passage position dy at a high frequency.

[0255] 8. Embodiment 4 8.1 Configuration The configuration of the EUV light generation device according to Embodiment 4 may be the same as the configuration of the EUV light generation device 1A shown in Figure 10. The EUV light generation device according to Embodiment 4 differs from Embodiment 1 in that it is configured to connect the outputs of two adjacent sensor elements 87 of the target passage detection device 70 and output their sum.

[0256] Figure 27 is an explanatory diagram of the target detection signal obtained by concatenating the outputs of two adjacent sensor elements 871 and 872. The upper part of Figure 27, F27A, schematically shows the image of the target 27 formed on the light-receiving surfaces of two adjacent sensor elements 871 and 872 of the optical sensor 86 in the target passage detection device 70.

[0257] Graph F27B, shown in the lower part of Figure 27, is an example of a target pass signal obtained by concatenating the output signals of sensor element 871 and sensor element 872. The target pass signal shown in Graph F27B is an example of a "sum signal" in this disclosure. The pass signal height ΔDab is an example of a "peak height of the sum signal" in this disclosure.

[0258] 8.2 Operation The pulse waveform processing unit 55A measures the pass signal height ΔDab from the coupled target pass signal, and calculates the time width Δtxab of the target pass signal, with a threshold th set as a constant ratio C to ΔDab.

[0259] th=C×ΔDab (Equation 14) The ratio C can be a constant between 0.05 and 0.9, for example.

[0260] In other words, the threshold th may be set to any value between 5% and 90% of the transmitted signal height ΔDab.

[0261] The trigger selection / delay device 53A calculates a timing correction amount Δtad using the time width Δtxab, similar to Embodiment 1, and corrects the laser irradiation timing, etc.

[0262] 8.3 Action and Effects According to Embodiment 4, by linking the outputs of two adjacent sensor elements 87, the value of the velocity coefficient ΔL is not affected by changes in the target passage position dy. Furthermore, as shown in Equation 14, since the threshold th is updated at a constant rate C with respect to the passage signal height ΔDab of the linked target passage signals, the value of the velocity coefficient ΔL is not affected by changes in the target diameter Rd.

[0263] For the reasons stated above, in Embodiment 4, updating the velocity coefficient ΔL is unnecessary in response to changes in the target passage position dy and the target diameter Rd.

[0264] 9. Method for manufacturing electronic devices Figure 28 schematically shows the configuration of the exposure apparatus 6a connected to the EUV light generator 1A. In Figure 28, 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.

[0265] Figure 29 schematically shows the configuration of the inspection device 6b connected to the EUV light generator 1A. In Figure 29, 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.

[0266] Instead of the EUV light generator 1A shown in Figures 28 and 29, the EUV light generator 1C can be used.

[0267] 10. Regarding the Processor Processors such as processor 5, arithmetic control processors 51, 51A, 51C, etc. may be physically configured in the form of hardware to execute various processes included in the present disclosure. For example, the processor may be a computer including a memory storing a control program that defines various processes and a processing device that executes the control program. The control program may be stored in one memory, or may be divided and stored in a plurality of memories existing physically apart, and various processes may be defined by the control program as an aggregate thereof. The processing device may be a general-purpose processing device such as a CPU, or a special-purpose processing device such as a GPU.

[0268] Also, the processor may be programmed in the form of software to execute various processes included in the present disclosure. For example, the processor may be one in which functions for executing various processes are implemented in a dedicated device such as an ASIC or a programmable device such as an FPGA.

[0269] Various processes included in the present disclosure may be executed by one computer, one dedicated device, or one programmable device, or may be executed by the cooperation of a plurality of physically separated computers, a plurality of dedicated devices, or a plurality of programmable devices. Various processes may be executed by a combination of at least two of one or more computers, one or more dedicated devices, and one or more programmable devices.

[0270] The arithmetic control processors 51A, 51C, trigger selection / delay devices 53A, 53C, and pulse waveform processing devices 55A, 55C shown in FIGS. 10 and 19 may perform calculation processing by a processor and a memory after being digitized by an analog electrical signal processing circuit or an AD converter in order to perform the processes described in each embodiment.

[0271] 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.

[0272] 11. Other 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.

[0273] 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 plasma by irradiating a target with pulsed laser light and generates extreme ultraviolet light, Chamber and, A target supply device that supplies the target into the chamber, A target passage detection device for detecting the target passing through a predetermined area, A laser device that irradiates the pulsed laser light toward the target that has passed through the predetermined region, Equipped with a processor, The target passage detection device is A light source that irradiates the predetermined region with light, The sensor includes a sensor that receives the aforementioned light and outputs a signal corresponding to the amount of light received, The aforementioned processor, The timing at which the target is detected and the time interval during which the target is detected are obtained from the aforementioned signal. Based on the aforementioned passing timing and time width, the irradiation timing for irradiating the laser device with the pulsed laser light is determined. Extreme ultraviolet light generation system.

2. An extreme ultraviolet light generation system according to claim 1, The aforementioned processor, The signal is compared with a threshold, and the period during which the signal exceeds the threshold is determined as the time width. Extreme ultraviolet light generation system.

3. An extreme ultraviolet light generation system according to claim 1, The aforementioned processor, Using the aforementioned time interval, calculate the velocity of the target. The irradiation timing is determined based on the distance between the predetermined region and the reference position and the velocity of the target. Extreme ultraviolet light generation system.

4. An extreme ultraviolet light generation system according to claim 3, The velocity coefficient is defined as the distance the target travels during the period from when the signal exceeds a threshold due to the passing of the target until it recovers to the threshold. The processor calculates the speed of the target from the speed coefficient and the time width. Extreme ultraviolet light generation system.

5. An extreme ultraviolet light generation system according to claim 4, The system includes an image sensor that captures an image of a region including the aforementioned reference position, The processor updates the velocity coefficient based on the difference between the position of the target, which is acquired using the image sensor, and the reference position. Extreme ultraviolet light generation system.

6. An extreme ultraviolet light generation system according to claim 5, The aforementioned reference position is set in the plasma generation region where the plasma is generated. Extreme ultraviolet light generation system.

7. An extreme ultraviolet light generation system according to claim 5, A flash lamp that illuminates the target within the region captured by the image sensor, A shutter that regulates the exposure time to the image sensor, Equipped with, The aforementioned processor, Based on the passing timing and the time width, 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 shutter operation timing. Extreme ultraviolet light generation system.

8. An extreme ultraviolet light generation system according to claim 1, The aforementioned sensor is The first sensor element, A second sensor element adjacent to the first sensor element, The light-receiving surfaces of the first sensor element and the second sensor element are arranged in a second direction different from the first direction in which the target moves. The signal includes a first signal output from the first sensor element corresponding to the amount of light received, and a second signal output from the second sensor element corresponding to the amount of light received. Extreme ultraviolet light generation system.

9. An extreme ultraviolet light generation system according to claim 8, The velocity coefficient is defined as the distance the target travels during the period from when the signal exceeds a threshold due to the passing of the target until it recovers to the threshold. The system includes a memory that pre-stores the relationship between a first signal height indicating the peak height of the first signal, a second signal height indicating the peak height of the second signal, and the velocity coefficient when the target passes through the predetermined region. The aforementioned processor, From the first signal and the second signal obtained from the sensor, the height of the first signal, the height of the second signal, and the first time interval during which the first signal exceeds the threshold are determined. From the relationship stored in the memory, the velocity coefficient corresponding to the combination of the first signal height and the second signal height is obtained. The velocity of the target is calculated from the acquired velocity coefficient and the first time width. The irradiation timing is determined based on the distance between the predetermined region and the reference position and the velocity of the target. Extreme ultraviolet light generation system.

10. An extreme ultraviolet light generation system according to claim 9, The relationship stored in the memory is, The size of the target and the position of the target passing through the second direction in the predetermined region are determined in advance by changing these values. Extreme ultraviolet light generation system.

11. An extreme ultraviolet light generation system according to claim 8, The aforementioned processor, The sum signal of the first signal and the second signal is obtained, The sum signal is compared with a threshold, and the period during which the sum signal exceeds the threshold is obtained as the time width. Extreme ultraviolet light generation system.

12. An extreme ultraviolet light generation system according to claim 11, The threshold is set based on the peak height of the sum signal. Extreme ultraviolet light generation system.

13. An extreme ultraviolet light generation system according to claim 11, The threshold is 5% or more and 90% or less of the peak height of the sum signal. Extreme ultraviolet light generation system.

14. An extreme ultraviolet light generation system according to claim 1, The aforementioned processor, The passing timing is defined as the midpoint between a first timing at which the signal exceeds a threshold due to the target passing through the predetermined region, and a second timing at which the signal recovers to the threshold. Extreme ultraviolet light generation system.

15. An extreme ultraviolet light generation system according to claim 1, When the distance between the predetermined region and the reference position is ΔQ, the time width is Δtx, and the velocity coefficient indicating the distance the target moves during the time width Δtx is ΔL, The aforementioned processor, The timing correction amount Δtad that determines the irradiation timing is given by the following equation: Δtad=(ΔQ / ΔL)×Δtx Calculated by, Extreme ultraviolet light generation system.

16. A method for manufacturing electronic devices, Chamber and, A target supply device that supplies targets to the inside of the chamber, A target passage detection device for detecting the target passing through a predetermined area, A laser device that irradiates pulsed laser light toward the target that has passed through the predetermined region, Equipped with a processor, An extreme ultraviolet light generation system that generates plasma and generates extreme ultraviolet light by irradiating the target with the pulsed laser light, The target passage detection device is A light source that irradiates the predetermined region with light, The sensor includes a sensor that receives the aforementioned light and outputs a signal corresponding to the amount of light received, The aforementioned processor, The timing at which the target is detected and the time interval during which the target is detected are obtained from the aforementioned signal. An extreme ultraviolet light generation system generates the extreme ultraviolet light, which determines the irradiation timing for irradiating the laser device with the pulsed laser light based on the aforementioned passing timing and time width. The aforementioned extreme ultraviolet light is output to the exposure device, A method for manufacturing an electronic device, comprising exposing a photosensitive substrate to extreme ultraviolet light in an exposure apparatus for the purpose of manufacturing an electronic device.

17. A method for manufacturing electronic devices, Chamber and, A target supply device that supplies targets to the inside of the chamber, A target passage detection device for detecting the target passing through a predetermined area, A laser device that irradiates pulsed laser light toward the target that has passed through the predetermined region, Equipped with a processor, An extreme ultraviolet light generation system that generates plasma and generates extreme ultraviolet light by irradiating the target with the pulsed laser light, The target passage detection device is A light source that irradiates the predetermined region with light, The sensor includes a sensor that receives the aforementioned light and outputs a signal corresponding to the amount of light received, The aforementioned processor, The timing at which the target is detected and the time interval during which the target is detected are obtained from the aforementioned signal. Based on the aforementioned passage timing and time width, the irradiation timing for irradiating the laser device with the pulsed laser light is determined. The extreme ultraviolet light generated by the extreme ultraviolet light generation system is irradiated onto the mask to inspect for defects in the mask. 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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