JP6232462B2 - Alignment system - Google Patents

Description

  The present disclosure relates to an alignment system for a laser apparatus.

  In recent years, along with miniaturization of semiconductor processes, miniaturization of transfer patterns in optical lithography of semiconductor processes has been rapidly progressing. In the next generation, fine processing of 70 nm to 45 nm, and further fine processing of 32 nm or less will be required. Therefore, for example, in order to meet the demand for fine processing of 32 nm or less, development of an exposure apparatus combining an apparatus for generating extreme ultraviolet (EUV) light with a wavelength of about 13 nm and a reduced projection reflection optical system is expected. .

  As the EUV light generation apparatus, an LPP (Laser Produced Plasma) type apparatus in which plasma generated by irradiating a target material with laser light is used, and a DPP (Discharge Produced Plasma) in which plasma generated by discharge is used. Three types of devices have been proposed: a device of the type and an SR (Synchrotron Radiation) type device using synchrotron radiation.

US Patent Application Publication No. 2010/0127191

Overview

An alignment system according to one aspect of the present disclosure includes a guide laser device that outputs guide laser light, an adjustment mechanism that adjusts the traveling direction of the laser light , and the traveling directions of the laser light and the guide laser light substantially coincide with each other. An optical path coupling unit; a light detection unit that is disposed on the downstream side of the optical path coupling unit and that detects the laser light and the guide laser beam; and a control unit that controls the adjustment mechanism based on a detection result of the light detection unit. The adjusting mechanism may be disposed upstream of the optical path of the laser beam with respect to the optical path coupling portion.

Several embodiments of the present disclosure are described below by way of example only and with reference to the accompanying drawings.
FIG. 1 schematically shows the configuration of an exemplary LPP type EUV light generation system. FIG. 2 is a partial cross-sectional view of the EUV light generation system according to the first embodiment. FIG. 3 is a flowchart showing the operation of the first control unit in the first embodiment. FIG. 4 is a flowchart showing the operation of the second control unit in the first embodiment. FIG. 5 is a partial cross-sectional view of the EUV light generation system according to the second embodiment. FIG. 6 is a partial cross-sectional view of an EUV light generation system according to the third embodiment. FIG. 7 is a partial cross-sectional view of an EUV light generation system according to the fourth embodiment. FIG. 8 is a partial cross-sectional view of an EUV light generation system according to the fifth embodiment. FIG. 9 schematically shows a part of a laser beam traveling direction control unit in an EUV light generation system according to the sixth embodiment. FIG. 10A schematically shows a first example of a detector in the EUV light generation system according to the above-described embodiment. FIG. 10B schematically shows a modification of the first example of the detector. FIG. 10C schematically shows another modification of the first example of the detector. FIG. 11A schematically shows a second example of the detector in the EUV light generation system according to the above-described embodiment. FIG. 11B schematically shows a modification of the second example of the detector. FIG. 12A schematically shows a third example of the detector in the EUV light generation system according to the above-described embodiment. FIG. 12B schematically shows a modification of the third example of the detector. FIG. 13 schematically shows a fourth example of the detector in the EUV light generation system according to the above-described embodiment. FIG. 14 schematically shows a fifth example of the detector in the EUV light generation system according to the above-described embodiment. FIG. 15 is a diagram for explaining the operation of the laser beam traveling direction adjusting mechanism. FIG. 16 shows a specific example of an actuator unit in the laser beam traveling direction adjusting mechanism.

Embodiment

<Contents>
1. Outline 2. 2. Explanation of terms 3. Overall description of extreme ultraviolet light generation system 3.1 Configuration 3.2 Operation 4. 4. EUV light generation system including alignment mechanism 4.1 Configuration 4.2 Operation 5. EUV light generation system using prepulse laser light (1)
6). EUV light generation system using prepulse laser light (2)
7). 7. EUV light generation system including a high-speed alignment mechanism 8. EUV light generation system including a guide laser light adjustment mechanism Laser amplifier arrangement10. Detector 10.1 Example of detecting beam profiles at two different positions 10.2 Example of detecting beam profile and pointing 10.3 Example of using Shack-Hartmann wavefront sensor 10.4 Example of using optical position detector 10 .5 Combination of first to fourth examples Supplementary explanation 11.1 Explanation of adjustment mechanism 11.2 Explanation of actuator section

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Embodiment described below shows some examples of this indication, and does not limit the contents of this indication. In addition, all the configurations and operations described in the embodiments are not necessarily essential as the configurations and operations of the present disclosure. In addition, the same referential mark is attached | subjected to the same component and the overlapping description is abbreviate | omitted.

1. Outline In the LPP type EUV light generation apparatus, the target material may be converted into plasma by condensing and irradiating the laser light output from the laser device onto the target material in the chamber. Light including EUV light may be emitted from the plasma. Of the emitted light, EUV light may be collected by an EUV collector mirror disposed in the chamber and output to an external apparatus such as an exposure apparatus. The elements that make up the laser beam path from the laser device to the inside of the chamber change in its arrangement, posture, shape, etc. due to vibration of the laser device, vibration of the beam steering mechanism between the laser device and the chamber, temperature change, etc. There is a case. As a result, the laser beam path may fluctuate.

  According to one aspect of the present disclosure, a guide laser beam is output separately from the laser beam output from the laser device, the optical paths of the laser beam and the guide laser beam are matched, and the laser beam and the guide laser beam are beam-steered. It may be incident on the mechanism. Then, the condensing position of the laser beam may be stabilized by detecting the guide laser beam on the downstream side of the beam steering mechanism and feeding back the detection result to the beam steering mechanism. Further, even when the laser beam is not output, the converging position when the laser beam output is resumed may be stabilized by detecting the guide laser beam and controlling the beam steering mechanism.

2. Explanation of Terms Some terms used in this application are defined below. The “chamber” is a container for isolating a space where plasma is generated from the outside in an LPP type EUV light generation apparatus. The “target supply device” is a device for supplying a target material such as molten tin used for generating EUV light into the chamber in the form of a droplet. The “EUV collector mirror” is a mirror for reflecting EUV light emitted from plasma and outputting it outside the chamber.

3. 3. General Description of Extreme Ultraviolet Light Generation System 3.1 Configuration FIG. 1 schematically shows a configuration of an exemplary LPP type EUV light generation system. The EUV light generation apparatus 1 may be used together with at least one laser apparatus 3. In the present application, a system including the EUV light generation apparatus 1 and the laser apparatus 3 is referred to as an EUV light generation system 11. As shown in FIG. 1 and described in detail below, the EUV light generation apparatus 1 may include a chamber 2 and a target supply device 26. The chamber 2 may be sealable. The target supply device 26 may be attached, for example, so as to penetrate the wall of the chamber 2. The material of the target substance supplied from the target supply device 26 may include, but is not limited to, tin, terbium, gadolinium, lithium, xenon, or a combination of any two or more thereof.

  The wall of the chamber 2 may be provided with at least one through hole. A window 21 may be provided in the through hole, and the pulse laser beam 32 may be transmitted through the window 21. In the chamber 2, for example, an EUV collector mirror 23 having a spheroidal reflecting surface may be disposed. The EUV collector mirror 23 may have first and second focal points. For example, a multilayer reflective film in which molybdenum and silicon are alternately laminated may be formed on the surface of the EUV collector mirror 23. For example, the EUV collector mirror 23 is preferably arranged 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 (IF) 292. . A through hole 24 for allowing the pulse laser beam 33 to pass therethrough may be provided at the center of the EUV collector mirror 23.

  The EUV light generation apparatus 1 may further include an EUV light generation control unit 5 and a target sensor 4. The target sensor 4 may have an imaging function, and may detect the presence, trajectory, position, speed, and the like of the target.

  Further, the EUV light generation apparatus 1 may include a connection unit 29 that allows the inside of the chamber 2 and the inside of the exposure apparatus 6 to communicate with each other. A wall 291 in which an aperture is formed may be provided inside the connection portion 29. The wall 291 is preferably arranged so that its aperture is located at the second focal point of the EUV collector mirror 23.

  Furthermore, the EUV light generation apparatus 1 may include a laser beam traveling direction control unit 34, a laser beam focusing mirror 22, a target recovery unit 28 for recovering the target 27, and the like. The laser beam traveling direction control unit 34 may include an optical system for defining the traveling direction of the laser beam and an actuator for adjusting the arrangement, posture, and the like of the optical system.

3.2 Operation Referring to FIG. 1, the pulsed laser beam 31 output from the laser device 3 passes through the window 21 as the pulsed laser beam 32 through the laser beam traveling direction control unit 34 and enters the chamber 2. May be. The pulse laser beam 32 may travel along the at least one laser beam path into the chamber 2, be reflected by the laser beam collector mirror 22, and irradiate at least one target 27 as the pulse laser beam 33.

  The target supply device 26 may be configured to output the target 27 toward the plasma generation region 25 in the chamber 2. The target 27 may be irradiated with at least one pulse included in the pulse laser beam 33. The target 27 irradiated with the pulse laser beam 33 is turned into plasma, and radiation light 251 can be emitted from the plasma. The EUV light 252 included in the radiation light 251 may be selectively reflected by the EUV collector mirror 23. The EUV light 252 reflected by the EUV collector mirror 23 may be output to the exposure apparatus 6 through the intermediate condensing point 292. A single target 27 may be irradiated with a plurality of pulses included in the pulse laser beam 33.

  The EUV light generation controller 5 may be configured to control the entire EUV light generation system 11. The EUV light generation controller 5 may process the image data of the target 27 captured by the target sensor 4. Further, the EUV light generation control unit 5 may be configured to control the timing of outputting the target 27, the output direction of the target 27, and the like. Further, the EUV light generation control unit 5 may be configured to control, for example, the oscillation timing of the laser device 3, the traveling direction of the pulse laser light 32, the condensing position of the pulse laser light 33, and the like. The various controls described above are merely examples, and other controls may be added as necessary.

4). EUV Light Generation System Including Alignment Mechanism 4.1 Configuration FIG. 2 is a partial cross-sectional view of the EUV light generation system according to the first embodiment. In the first embodiment, the chamber 2 may be disposed on the clean room floor, and the laser device 3 may be disposed on the subfab floor. The subfab floor may be located below the clean room floor. The laser beam traveling direction control unit 34 for controlling the traveling direction of the laser beam supplied from the laser device 3 into the chamber 2 may be disposed across the clean room floor and the subfab floor.

  In the subfab floor, the laser beam traveling direction control unit 34 includes a guide laser device 40, a laser beam traveling direction adjustment mechanism 41, an optical path coupler 44, a light detection unit 45, and a first control unit 48. Good.

  The guide laser device 40 may be configured to output guide laser light separately from the laser light output from the laser device 3. The guide laser device 40 may be a laser device that continuously oscillates (CW oscillation) or a laser device that performs pulse oscillation at a predetermined repetition rate. The average output of the guide laser beam may be lower than the average output of the laser beam output from the laser device 3. Further, the guide laser beam may include a wavelength component different from the laser beam output from the laser device 3.

  The laser beam traveling direction adjusting mechanism 41 may include high reflection mirrors 42 and 43. The high reflection mirror 42 may be supported by the mirror holder 421, and the position and posture of the high reflection mirror 42 and the mirror holder 421 may be adjusted by the actuator unit 422. Similarly, the high reflection mirror 43 may be supported by the mirror holder 431, and the position and posture of the high reflection mirror 43 and the mirror holder 431 may be adjusted by the actuator unit 432. The traveling direction of the laser beam output from the laser device 3 may be adjusted by adjusting the positions and postures of the high reflection mirrors 42 and 43.

  The optical path coupler 44 may include a dichroic mirror. Laser light output from the laser device 3 may be incident on the first surface (the right surface in the drawing) of the optical path coupler 44. The guide laser beam output from the guide laser device 40 may be incident on the second surface (the left surface in the drawing) of the optical path coupler 44. The optical path coupler 44 may transmit the laser light incident on the first surface and reflect the guide laser light incident on the second surface. Thereby, the optical path coupler 44 may substantially match the traveling direction of the laser light output from the laser device 3 with the traveling direction of the guide laser light output from the guide laser device 40.

  The light detection unit 45 may include a beam sampler 46 and a detector 47. The beam sampler 46 transmits part of the laser light output from the laser device 3, reflects the other part as sample light, transmits part of the guide laser light output from the guide laser device 40, Another part may be reflected as sample light. The detector 47 may have a light receiving surface on which sample light is incident. The detector 47 may be configured to detect the light receiving position of the sample light on the light receiving surface and output the detection result.

  The first control unit 48 detects a deviation between the traveling direction of the laser light transmitted through the optical path coupler 44 and the traveling direction of the guide laser light reflected by the optical path coupler 44 based on the detection result by the detector 47. May be. The first control unit 48 may control the laser beam traveling direction adjustment mechanism 41 in order to reduce the deviation between the traveling direction of the laser beam and the traveling direction of the guide laser beam. In the laser beam traveling direction adjusting mechanism 41, an actuator driver (not shown) receives the control signal from the first control unit 48 and drives the actuator units 422 and 432, whereby the traveling direction of the laser beam output from the laser device 3 is reached. May be adjusted. The first controller 48 may have a function of transmitting a control signal to the guide laser device 40 and outputting or stopping the guide laser beam at a desired timing.

  In the region extending over the sub-fab floor and the clean room floor, the laser beam traveling direction control unit 34 may include a beam steering mechanism 51. The beam steering mechanism 51 includes a hollow optical path tube 510, and dry air, inert gas, or the like may be introduced into the optical path tube 510. The beam steering mechanism 51 may guide the laser light and the guide laser light transmitted through the beam sampler 46 on the sub-fab floor to the clean room floor.

  The beam steering mechanism 51 may include high reflection mirrors 52 and 53. The high reflection mirror 52 may be supported by the mirror holder 521, and the position and posture of the high reflection mirror 52 and the mirror holder 521 may be adjusted by the actuator unit 522. Similarly, the high reflection mirror 53 may be supported by the mirror holder 531, and the position and posture of the high reflection mirror 53 and the mirror holder 531 may be adjusted by the actuator unit 532. The traveling directions of the laser light and the guide laser light may be adjusted by adjusting the positions and postures of the high reflection mirrors 52 and 53.

  In the clean room floor, the chamber 2 may be fixed on the chamber reference member 10. The chamber reference member 10 may be fixed on the floor by the installation mechanism 9. The chamber reference member 10 may have a space in which an optical element group constituting a part of the laser beam traveling direction control unit 34, the mirror storage container 60, and the like are arranged. A laser beam condensing mirror 220 may be disposed in the mirror storage container 60.

  In the clean room floor, the laser beam traveling direction control unit 34 may include a light detection unit 55, a second control unit 58, and high reflection mirrors 59 and 61. The light detection unit 55 and the high reflection mirrors 59 and 61 may be disposed in the chamber reference member 10.

  The high reflection mirror 59 may reflect the laser beam and the guide laser beam propagated to the clean room floor by the beam steering mechanism 51 toward the light detection unit 55.

  The light detection unit 55 may include a beam splitter 56 and a detector 57. The beam splitter 56 may transmit the laser light reflected by the high reflection mirror 59 toward the high reflection mirror 61 with high transmittance. The beam splitter 56 may reflect the guide laser light reflected by the high reflection mirror 59 toward the detector 57 with high reflectivity as sample light. The detector 57 may have a light receiving surface on which sample light is incident. The detector 57 may be configured to detect the light receiving position of the sample light on the light receiving surface and output the detection result.

  The second control unit 58 may control the beam steering mechanism 51 so that the laser light is focused on the plasma generation region 25 based on the detection result by the detector 57. In the beam steering mechanism 51, an actuator driver (not shown) may adjust the traveling directions of the laser beam and the guide laser beam by driving the actuator units 522 and 532 in response to a control signal from the second control unit 58. .

  The high reflection mirror 61 may reflect the laser light transmitted through the beam splitter 56 toward the inside of the mirror storage container 60. The mirror container 60 may be provided with a window 66, and the laser light reflected by the high reflection mirror 61 may pass through the window 66 with high transmittance. The laser light that has passed through the window 66 is reflected with a high reflectivity by the plane mirror 62, is reflected with a high reflectivity by the laser light condensing mirror 220, and is condensed on the target supplied to the plasma generation region 25. Good. The target is turned into plasma by being irradiated with laser light, and EUV light can be emitted from the plasma.

4.2 Operation FIG. 3 is a flowchart showing the operation of the first control unit in the first embodiment. The first control unit 48 detects the laser light output from the laser device 3 and the guide laser light output from the guide laser device 40 by the following processing, and the traveling direction of the laser light and the traveling of the guide laser light. In order to reduce the deviation from the direction, the laser beam traveling direction adjusting mechanism 41 may be controlled.

  First, the 1st control part 48 may transmit a control signal to the guide laser apparatus 40, and may start the output of a guide laser beam (S101).

  Next, the first control unit 48 may receive a detection signal from the detector 47 (S102). The first control unit 48 may store the detection value Pg1 of the guide laser beam included in the detection signal (S103). The detection value Pg1 may include a value indicating the light receiving position of the guide laser light received on the light receiving surface of the detector 47. The detection value Pg1 may be, for example, coordinate information indicating the position of the center of gravity of the intensity distribution calculated from the detected intensity distribution of the guide laser light.

  Next, the first control unit 48 may receive a signal from the EUV light generation control unit 5 and determine whether or not output of laser light from the laser device 3 has been started (S104). When the output of the laser beam is not started (S104: NO), the process may return to the above-described S102 to detect the guide laser beam.

  When the output of the laser beam is started (S104: YES), the first control unit 48 may receive a detection signal from the detector 47 (S105). The first control unit 48 may store the detection value Pm1 of the laser beam included in the detection signal (S106). The detection value Pm1 may include a value indicating the light receiving position of the laser beam received on the light receiving surface of the detector 47. The detection value Pm1 may be, for example, coordinate information indicating the gravity center position of the intensity distribution calculated from the detected intensity distribution of the laser light.

Next, the first control unit 48 may calculate the difference ΔP1 between the detection value Pg1 and the detection value Pm1 using the following equation (S107).
ΔP1 = Pm1−Pg1
When the detection value Pg1 and the detection value Pm1 are both coordinate information, ΔP1 may include a difference in values at the corresponding coordinates.

  Next, the first control unit 48 may determine whether or not the absolute value | ΔP1 | of the difference between the detection value Pg1 and the detection value Pm1 is equal to or less than a predetermined threshold value ΔPr1 (S108). When the detection value Pg1 and the detection value Pm1 are both coordinate information, the threshold value ΔPr1 may include an allowable range of values at the corresponding coordinates.

  In S108, when the absolute value | ΔP1 | is equal to or smaller than the threshold value ΔPr1 (S108: YES), the process may be advanced to S109. In S109, the first control unit 48 may transmit a control signal to the laser beam traveling direction adjusting mechanism 41 in order to make ΔP1 approach zero. Next, the first control unit 48 may determine whether to stop the control according to this flowchart by receiving a signal from the EUV light generation control unit 5 (S110). When a signal indicating control stop is received from the EUV light generation controller 5 (S110: YES), the processing may be stopped. When the signal indicating the control stop is not received (S110: NO), the process may return to the above-described S102 to detect the guide laser beam.

  In S108, when the absolute value | ΔP1 | exceeds the threshold value ΔPr1 (S108: NO), the process may be advanced to S111. In S <b> 111, the first control unit 48 may transmit a signal indicating alignment abnormality to the EUV light generation control unit 5. Next, similarly to S109, the first controller 48 may transmit a control signal to the laser beam traveling direction adjusting mechanism 41 in order to make ΔP1 close to 0 (S112). Then, it may return to above-mentioned S102 and may detect a guide laser beam.

  FIG. 4 is a flowchart showing the operation of the second control unit in the first embodiment. The second controller 58 may detect the guide laser beam and control the beam steering mechanism 51 so that the laser beam is focused on the plasma generation region 25 by the following process.

  First, the second control unit 58 may receive a detection signal from the detector 57 (S202). The second control unit 58 may store the detection value Pg2 of the guide laser beam included in the detection signal (S203). The detection value Pg2 may include a value indicating the light receiving position of the guide laser light received on the light receiving surface of the detector 57. The detection value Pg2 may be, for example, coordinate information indicating the gravity center position of the intensity distribution calculated from the detected intensity distribution of the guide laser light.

Next, the second control unit 58 may calculate a difference ΔP2 between the detection value Pg2 and the target value Pt for condensing the laser light in the plasma generation region 25 by the following equation (S207). .
ΔP2 = Pt−Pg2
When the detected value Pg2 is coordinate information, the target value Pt may include a value at a corresponding coordinate. Further, ΔP2 may include a difference in values at corresponding coordinates.

  Next, the second control unit 58 may determine whether or not the absolute value | ΔP2 | of the difference between the detection value Pg2 and the target value Pt is equal to or less than a predetermined threshold value ΔPr2 (S208). When the detected value Pg2 and the target value Pt are both coordinate information, the threshold value ΔPr2 may include an allowable range of values at the corresponding coordinates.

  In S208, when the absolute value | ΔP2 | is equal to or less than the threshold value ΔPr2 (S208: YES), the process may be advanced to S209. In S209, the second control unit 58 may transmit a control signal to the beam steering mechanism 51 in order to bring ΔP2 close to zero. Next, the second control unit 58 may determine whether or not to stop the control according to this flowchart by receiving a signal from the EUV light generation control unit 5 (S210). When a signal indicating control stop is received from the EUV light generation control unit 5 (S210: YES), the processing may be stopped. When a signal indicating control stop is not received (S210: NO), the process may return to the above-described S202 to detect the guide laser beam.

  In S208, when the absolute value | ΔP2 | exceeds the threshold value ΔPr2 (S208: NO), the process may be advanced to S211. In S211, the second control unit 58 may transmit a signal indicating an alignment error to the EUV light generation control unit 5. Next, similarly to S209, the second control unit 58 may transmit a control signal to the beam steering mechanism 51 in order to bring ΔP2 close to 0 (S212). Then, it may return to above-mentioned S202 and may detect a guide laser beam.

  According to the first embodiment, the condensing position of the laser beam can be stabilized by detecting the guide laser beam on the downstream side of the beam steering mechanism and feeding back the detection result to the beam steering mechanism. Further, according to the first embodiment, the laser beam and the guide laser beam are detected on the downstream side of the optical path coupler, and the detection result is fed back to the laser beam traveling direction adjusting mechanism, so that the traveling direction of the laser beam Deviation from the traveling direction of the guide laser beam can be reduced. Even when the laser beam is not output, the converging position of the laser beam when the laser beam output is resumed can be stabilized by detecting the guide laser beam and controlling the beam steering mechanism.

  The beam splitter 56 may reflect not only the guide laser beam but also a part of the laser beam as sample light toward the detector 57. The detector 57 may receive not only the guide laser beam but also the laser beam reflected by the beam splitter 56 and output the detection result. In this case, by measuring the curvature (described later) of the wavefront of the laser light in the first and second control units, the location where the wavefront distortion is generated (whether the beam steering mechanism 51 or the upstream side) is specified. Also good.

5. EUV light generation system using prepulse laser light (1)
FIG. 5 is a partial cross-sectional view of the EUV light generation system according to the second embodiment. In the second embodiment, a method may be used in which a target is irradiated with prepulse laser light to diffuse the target, and the diffused target is irradiated with main pulse laser light to convert the target into plasma. For example, laser light with a wavelength of 1.06 μm output from a YAG laser device is used as prepulse laser light, and laser light with a wavelength of 10.6 μm output from a carbon dioxide (CO ₂ ) laser device is used as main pulse laser light. Also good.

  Although depending on conditions such as the diameter of the droplet-shaped target and the light intensity of the prepulse laser beam, preplasma can be generated from the surface of the target irradiated with the prepulse laser beam when the target is irradiated with the prepulse laser beam. The pre-plasma is a target in which a portion near the surface irradiated with the pre-pulse laser beam becomes a vapor containing ions or neutral particles. Such a phenomenon that pre-plasma is generated is also called laser ablation.

  Alternatively, when the target is irradiated with prepulse laser light, the target can be destroyed. The destroyed target can be diffused by a reaction force caused by the ejection of pre-plasma.

  The target including at least one of the pre-plasma generated by the irradiation of the pre-pulse laser beam on the target and the destroyed target is hereinafter referred to as a diffusion target.

  By irradiating the diffusion target generated by the irradiation with the pre-pulse laser beam with the main pulse laser beam, the diffusion target can be turned into plasma. According to this method, higher energy EUV light is expected to be emitted than a method of generating EUV light by converting a target into plasma using only main pulse laser light.

  As shown in FIG. 5, a prepulse laser device 3a for outputting prepulse laser light and a main pulse laser device 3b for outputting main pulse laser light may be arranged on the subfab floor.

  In the subfab floor, the laser beam traveling direction control unit 34 includes a first guide laser device 40a, a laser beam traveling direction adjustment mechanism 41a, an optical path coupler 44a, a light detection unit 45a, and a first control unit 48a. May be included. The configuration and operation of the light detection unit 45a may be the same as the configuration and operation of the light detection unit 45 in the first embodiment. In a region spanning the sub-fab floor and the clean room floor, the laser beam traveling direction control unit 34 may include a beam steering mechanism 51a. The configuration and operation of the beam steering mechanism 51a may be the same as the configuration and operation of the beam steering mechanism 51 in the first embodiment. In the clean room floor, the laser beam traveling direction control unit 34 may include a second control unit 58a and a high reflection mirror 59a. These components may be provided to control the traveling direction of the prepulse laser beam output from the prepulse laser apparatus 3a. These configurations and operations are output from the laser apparatus 3 in the first embodiment. It may be the same as the configuration and operation of the components provided to control the traveling direction of the laser beam.

  The beam steering mechanism 51a may include a high reflection mirror 50a in addition to the high reflection mirrors 52a and 53a. The actuator portion may not be attached to the high reflection mirror 50a.

  In the subfab floor, the laser beam traveling direction control unit 34 includes a second guide laser device 40b, a laser beam traveling direction adjustment mechanism 41b, an optical path coupler 44b, a light detection unit 45b, and a first control unit 48b. May be included. The configuration and operation of the light detection unit 45b may be the same as the configuration and operation of the light detection unit 45 in the first embodiment. In the region spanning the sub-fab floor and the clean room floor, the laser beam traveling direction control unit 34 may include a beam steering mechanism 51b. The configuration and operation of the beam steering mechanism 51b may be the same as the configuration and operation of the beam steering mechanism 51 in the first embodiment. In the clean room floor, the laser beam traveling direction control unit 34 may include a second control unit 58b and a high reflection mirror 59b. These components may be provided to control the traveling direction of the main pulse laser beam output from the main pulse laser device 3b. These configurations and operations are the same as those of the laser device 3 in the first embodiment. This may be the same as the configuration and operation of the components provided to control the traveling direction of the laser beam output from the.

  For example, the first guide laser beam output from the first guide laser device 40a may be a laser beam having a wavelength of 635 nm, and the second guide laser beam output from the second guide laser device 40b is a laser having a wavelength of 532 nm. Light may be used.

  The high reflection mirror 59a may reflect the pre-pulse laser beam and the first guide laser beam with high reflectivity. The high reflection mirror 59b may reflect the main pulse laser beam and the second guide laser beam with high reflectivity. The pre-pulse laser beam and the first guide laser beam reflected by the high reflection mirror 59a may be incident on the first surface (the right surface in the drawing) of the beam splitter 56. The main pulse laser beam and the second guide laser beam reflected by the high reflection mirror 59b may be incident on the second surface (the left surface in the drawing) of the beam splitter 56.

  The beam splitter 56 may reflect the prepulse laser light incident on the first surface toward the high reflection mirror 61 with high reflectivity. Further, the beam splitter 56 may transmit the first guide laser light incident on the first surface toward the detector 57 with high transmittance.

  Further, the beam splitter 56 may transmit the main pulse laser beam incident on the second surface toward the high reflection mirror 61 with high transmittance. Further, the beam splitter 56 may reflect the second guide laser light incident on the second surface toward the detector 57 with high reflectivity.

  The detector 57 may have a light receiving surface sensitive to the first guide laser light transmitted through the beam splitter 56 and the second guide laser light reflected by the beam splitter 56.

  The beam splitter 56 may function as a beam combiner that matches the traveling direction of the pre-pulse laser beam and the traveling direction of the main pulse laser beam. As a substrate material of such a beam splitter 56, diamond may be used.

  The high reflection mirror 61 may reflect the pre-pulse laser beam reflected by the beam splitter 56 and the main pulse laser beam transmitted through the beam splitter 56 with high reflectivity.

  The pre-pulse laser beam and the main pulse laser beam reflected by the high reflection mirror 61 may pass through the window 66 with high transmittance. The pre-pulse laser beam and the main pulse laser beam that have passed through the window 66 may be reflected by the plane mirror 62 with a high reflectance. Thereafter, the pre-pulse laser beam and the main pulse laser beam reflected by the flat mirror 62 may be focused on the plasma generation region 25 by the laser beam focusing mirror 220, respectively. By irradiating the target with pre-pulse laser light, a diffusion target is generated. By irradiating the diffusion target with main pulse laser light, the diffusion target becomes plasma, and EUV light can be emitted from the plasma.

  According to the second embodiment, even when the target is irradiated with the prepulse laser light and then the diffusion target is irradiated with the main pulse laser light, the condensing positions of the prepulse laser light and the main pulse laser light can be stabilized. . Even when the pre-pulse laser beam and main pulse laser beam are not output, the laser beam focusing position is stabilized when the laser beam output is resumed by detecting the guide laser beam and controlling the beam steering mechanism. Can be.

  The beam splitter 56 may transmit a part of the prepulse laser light incident on the first surface toward the detector 57 as sample light. Further, the beam splitter 56 may reflect a part of the main pulse laser beam incident on the second surface toward the detector 57 as sample light. The detector 57 may receive these sample lights in addition to the first and second guide laser lights and output the detection results. In this case, the curvature of the laser beam wavefront (described later) is measured by the first and second control units, respectively, so that the laser beam wavefront distortion is generated at the beam steering mechanism 51a or 51b or upstream thereof. May be specified.

6). EUV light generation system using prepulse laser light (2)
FIG. 6 is a partial cross-sectional view of an EUV light generation system according to the third embodiment. In the third embodiment, the laser beam traveling direction control unit 34 may not include the light detection units 45a and 45b and the first control units 48a and 48b in the second embodiment.

  In the third embodiment, the beam splitter 56 reflects the prepulse laser light incident on the first surface (the right surface in the drawing) toward the high reflection mirror 61 with high reflectivity, and the incident prepulse laser light. May be transmitted as sample light toward the detector 57. Further, the beam splitter 56 may transmit the first guide laser light incident on the first surface toward the detector 57 with high transmittance.

  The beam splitter 56 transmits the main pulse laser beam incident on the second surface (the left surface in the drawing) toward the high reflection mirror 61 with high transmittance and a part of the incident main pulse laser beam. May be reflected toward the detector 57 as sample light. Further, the beam splitter 56 may reflect the second guide laser light incident on the second surface toward the detector 57 with high reflectivity.

  The detector 57 has a light receiving surface sensitive to the pre-pulse laser beam and the first guide laser beam transmitted through the beam splitter 56 and the main pulse laser beam and the second guide laser beam reflected by the beam splitter 56. May be. The detector 57 may detect the light receiving positions of the pre-pulse laser light and the first guide laser light and the light receiving positions of the main pulse laser light and the second guide laser light on the light receiving surface, and output the detection result. .

  The controller 58c may control the laser beam traveling direction adjusting mechanisms 41a and 41b and the beam steering mechanisms 51a and 51b based on the detection result by the detector 57.

  That is, the control unit 58c reduces the deviation between the traveling direction of the prepulse laser light and the traveling direction of the first guide laser light based on the detection result of the prepulse laser light and the first guide laser light by the detector 57. In order to do this, the laser beam traveling direction adjusting mechanism 41a may be controlled.

  The control unit 58c also shifts the traveling direction of the main pulse laser light and the traveling direction of the second guide laser light based on the detection results of the main pulse laser light and the second guide laser light by the detector 57. In order to reduce this, the laser beam traveling direction adjusting mechanism 41b may be controlled.

  In addition, the control unit 58c performs beam steering so that the pre-pulse laser beam is focused on the plasma generation region 25 based on the detection result of at least one of the first guide laser beam and the pre-pulse laser beam by the detector 57. The mechanism 51a may be controlled.

  Further, the control unit 58c is configured so that the main pulse laser beam is focused on the plasma generation region 25 based on the detection result of at least one of the second guide laser beam and the main pulse laser beam by the detector 57. The beam steering mechanism 51b may be controlled. About another point, it may be the same as that of 2nd Embodiment.

  Also in the third embodiment, the condensing positions of the pre-pulse laser beam and the main pulse laser beam can be stabilized. Even when the pre-pulse laser beam and main pulse laser beam are not output, the laser beam focusing position is stabilized when the laser beam output is resumed by detecting the guide laser beam and controlling the beam steering mechanism. Can be.

7). EUV Light Generation System Including High-Speed Alignment Mechanism FIG. 7 is a partial cross-sectional view of an EUV light generation system according to the fourth embodiment. In the fourth embodiment, a mechanism for detecting reflected light in the window 661 of the mirror container 60 and controlling the traveling direction of the laser light may be further included.

  As shown in FIG. 7, the beam splitter 56 may transmit not only the laser beam but also a part of the guide laser beam. A steering mirror 611 may be disposed on the optical path of the laser beam and the guide laser beam that have passed through the beam splitter 56. The steering mirror 611 may reflect the laser light and the guide laser light toward the window 661. The window 661 may be arranged at an angle other than perpendicular to the traveling direction of the laser light and the guide laser light. The window 661 may transmit the laser light with a high transmittance and reflect the guide laser light with a high reflectance.

  A detector 67 may be disposed on the optical path of the guide laser beam reflected by the window 661. The detector 67 may be a light position detector (PSD) that detects the barycentric position of light on the light receiving surface at high speed. The barycentric position of the light detected by the detector 67 may be input to the third control unit 68. The third control unit 68 may control the attitude of the steering mirror 611 so that the laser light is focused on the plasma generation region 25 based on the detection result by the detector 67. The steering mirror 611 may include an actuator that can adjust its posture at high speed using a piezoelectric element.

  According to the fourth embodiment, of the fluctuations in the traveling direction of the guide laser light, fluctuations having a large amplitude or a low frequency can be canceled by the control of the beam steering mechanism 51 by the second control unit 58. On the other hand, of the fluctuation in the traveling direction of the guide laser light, the fluctuation having a small amplitude or a high frequency can be canceled by high-speed control of the attitude of the steering mirror 611 by the third control unit. Thereby, the condensing position of a laser beam can be stabilized.

8). EUV Light Generation System Including Guide Laser Light Adjustment Mechanism FIG. 8 is a partial cross-sectional view of an EUV light generation system according to the fifth embodiment. In the fifth embodiment, an adjusting mechanism 81 for adjusting the traveling direction of the guide laser light may be disposed between the guide laser device 40 and the optical path coupler 44.

  The adjustment mechanism 81 may include high reflection mirrors 82 and 83. The positions and postures of the high reflection mirrors 82 and 83 may be adjusted by the actuator unit, similarly to the high reflection mirrors 42 and 43 described above. The traveling direction of the guide laser beam output from the guide laser device 40 may be adjusted by adjusting the positions and postures of the high reflection mirrors 82 and 83.

  The first control unit 48 reduces the deviation between the traveling direction of the laser light output from the laser device 3 and the traveling direction of the guide laser light output from the guide laser device 40 based on the detection result by the detector 47. In order to do so, the adjusting mechanism 81 may be controlled. In this case, instead of the laser beam traveling direction adjustment mechanism 41 for adjusting the traveling direction of the laser beam output from the laser device 3, an optical element that does not have a traveling direction adjustment function may be used.

9. Arrangement of Laser Amplifier FIG. 9 schematically shows a part of a laser beam traveling direction control unit in an EUV light generation system according to the sixth embodiment. In the sixth embodiment, the laser device 3 may include a master oscillator 300 and amplifiers 301 and 302. Further, amplifiers 303 and 304 for further amplifying the laser beam are provided downstream of the guide laser device 40, the laser beam traveling direction adjusting mechanism 41, and the optical path coupler 44 that constitute a part of the laser beam traveling direction control unit 34. It may be arranged. Amplifiers 303 and 304 may be located on the subfab floor.

  The master oscillator 300 may be configured to output seed light of laser light for converting the target into plasma. The amplifier 301 may amplify the seed light output from the master oscillator 300, and the amplifier 302 may further amplify the laser light amplified by the amplifier 301 and output from the amplifier 301.

  The laser beam traveling direction adjusting mechanism 41 may adjust the traveling direction of the laser beam output from the amplifier 302. The guide laser device 40 may be configured to output guide laser light. The optical path coupler 44 substantially matches the traveling direction of the laser beam output from the amplifier 302 and passed through the laser beam traveling direction adjusting mechanism 41 with the traveling direction of the guide laser beam output from the guide laser device 40. May be.

  The amplifier 303 may amplify at least the laser light among the laser light and the guide laser light whose traveling directions are matched in the optical path coupler 44. The amplifier 304 may further amplify at least the laser light out of the laser light and the guide laser light output from the amplifier 303. The laser beam and the guide laser beam output from the amplifier 304 may be incident on the light detection unit 45, 45a, or 45b as described in the first and second embodiments. Alternatively, the laser beam and the guide laser beam output from the amplifier 304 may be incident on the beam steering mechanism 51, 51a, or 51b as described in the third embodiment. Further, as described in the fifth embodiment, the adjusting mechanism 81 may be disposed between the guide laser device 40 and the optical path coupler 44.

  In the EUV light generation system, there is a case where a target is irradiated with laser light having high energy in order to output EUV light having desired energy. When the energy of the laser beam increases, the optical element disposed in the optical path of the laser beam may be deformed by a thermal load, and the traveling direction of the laser beam may change. In particular, when a plurality of amplifiers are used, the energy of the laser light becomes high at the output section of the downstream amplifier. For this reason, the change in the traveling direction of the laser light is larger at the output portion of the amplifier on the downstream side, and the control amount in the case where the traveling direction of the laser light and the traveling direction of the guide laser light are matched can be increased.

  According to the sixth embodiment, the laser beam traveling direction adjusting mechanism 41 and the optical path coupler 44 are arranged between the plurality of amplifiers, so that the laser beam can be processed at a stage where the variation in the traveling direction of the laser beam due to the thermal load is small. And the traveling direction of the guide laser beam can coincide with each other. Therefore, the amount of control by the laser beam traveling direction adjusting mechanism 41 for reducing the deviation between the traveling direction of the laser beam and the traveling direction of the guide laser beam can be reduced. If the control amount by the laser beam traveling direction adjusting mechanism 41 can be reduced, the laser beam traveling direction adjusting mechanism 41 can be operated at higher speed and more frequently. As a result, the deviation between the traveling direction of the laser beam and the traveling direction of the guide laser beam can be stabilized in a small state.

10. Detector 10.1 Example of Detecting Beam Profiles at Two Different Positions FIG. 10A schematically shows a first example of a detector in the EUV light generation system according to the embodiment described above. In the first example, in order to detect the beam profile of the beam cross section at two different positions of the sample light, the sample light is branched by the beam splitter 73, and these branched lights have different optical path lengths, respectively. The beam profile may be detected. The sample light may be laser light or guide laser light that is branched from the laser light path from the laser device 3 to the chamber 2 and enters the detector 57 (or 47).

  As shown in FIG. 10A, the detector may include a bandpass filter 70, a beam splitter 73, a high reflection mirror 77, transfer optical systems 75 and 79, and beam profilers 570 and 590.

  The bandpass filter 70 may be an optical filter that transmits light (laser light or guide laser light) to be detected with high transmittance and attenuates or blocks light of other wavelengths. The beam splitter 73 may transmit part of the light transmitted through the band pass filter 70 toward the transfer optical system 75 and reflect the other part toward the high reflection mirror 77. The high reflection mirror 77 may reflect the light reflected by the beam splitter 73 toward the transfer optical system 79 with a high reflectance.

  The transfer optical system 75 may transfer the beam cross section at the position A1 on the optical path of the sample light to the light receiving surface of the beam profiler 570. The transfer optical system 79 may transfer the beam cross section at the position A2 on the optical path of the sample light to the light receiving surface of the beam profiler 590. The beam profilers 570 and 590 may output the intensity distribution of the light transferred to the light receiving surface.

  The second controller 58 (or the first controller 48) may calculate the position, traveling direction, and divergence (wavefront curvature) of the laser light or guide laser light based on the outputs from the beam profilers 570 and 590. Good. For example, the barycentric position of the intensity distribution of the light detected by the beam profilers 570 and 590 may be calculated and used as a value indicating the position of the laser light or the guide laser light. Further, the traveling direction of the laser light or the guide laser light may be calculated from the difference between the center positions of the light intensity distributions detected by the beam profilers 570 and 590 and the distance between the positions A1 and A2. This may be used as a value indicating the traveling direction of the laser beam or the guide laser beam. Furthermore, the curvature of the wave front of the laser beam or the guide laser beam may be calculated from the difference between the beam widths (for example, half widths) of the respective lights detected by the beam profilers 570 and 590.

  Based on the above calculation result, the second control unit 58 may control at least one of the laser beam traveling direction adjustment mechanism 41 and the beam steering mechanism 51. Alternatively, the first control unit 48 may control the laser beam traveling direction adjustment mechanism 41 based on the above calculation result.

  10B and 10C schematically show a modification of the first example of the detector. The modified example of the first example may be different from the first example shown in FIG. 10A in that the plurality of bandpass filters 71 and 72 can be used by switching them. As shown in FIGS. 10B and 10C, the bandpass filters 71 and 72 may be configured to be movable by the driving unit 78. The drive unit 78 may be controlled by the second control unit 58 (or the first control unit 48). The band pass filter 71 may be an optical filter that transmits the laser light output from the laser device 3 with high transmittance and attenuates or blocks light of other wavelengths. The bandpass filter 72 may be an optical filter that transmits guide laser light with high transmittance and attenuates or blocks light of other wavelengths.

  As illustrated in FIG. 10B, when the driving unit 78 moves the bandpass filter 71 on the optical path of the sample light, the laser beam can reach the beam splitter 73. Therefore, the position, traveling direction, and wavefront curvature of the laser beam can be calculated by the second controller 58 (or the first controller 48).

  As illustrated in FIG. 10C, when the driving unit 78 moves the bandpass filter 72 on the optical path of the sample light, the guide laser light can reach the beam splitter 73. Accordingly, the position, traveling direction, and wavefront curvature of the guide laser beam can be calculated by the second controller 58 (or the first controller 48).

  The transfer optical systems 75 and 79 preferably have a function of correcting chromatic aberration with respect to the wavelengths of the laser light and the guide laser light. For example, the transfer optical systems 75 and 79 are preferably achromatic lenses or combinations thereof. Furthermore, it is preferable that the transfer optical systems 75 and 79 have a configuration with little chromatic aberration in principle. For example, the transfer optical systems 75 and 79 are preferably reflection optical systems.

  According to the modification of the first example, since the same beam profilers 570 and 590 are used to detect the laser beam and the guide laser beam, the traveling direction of the laser beam and the traveling of the guide laser beam are highly accurate. A deviation from the direction can be detected.

10.2 Example of Detecting Beam Profile and Pointing FIG. 11A schematically shows a second example of a detector in the EUV light generation system according to the above-described embodiment. In the second example, the sample light may be branched by the beam splitter 73 in order to detect the beam profile of the beam cross section of the sample light and the beam profile or pointing at the focal position.

  As shown in FIG. 11A, the detector may include a bandpass filter 70, a beam splitter 73, a condensing optical system 74, a transfer optical system 75, and beam profilers 540 and 570.

  The bandpass filter 70 may be an optical filter that transmits light (laser light or guide laser light) to be detected with high transmittance and attenuates or blocks light of other wavelengths. The beam splitter 73 may transmit part of the light transmitted through the bandpass filter 70 toward the transfer optical system 75 and reflect the other part toward the condensing optical system 74.

  The transfer optical system 75 may transfer the beam cross section of the light transmitted through the beam splitter 73 to the light receiving surface of the beam profiler 570. The condensing optical system 74 may image the light reflected by the beam splitter 73 on the light receiving surface of the beam profiler 540 disposed at a position away from the condensing optical system 74 by the focal length F. The focal length F may be a focal length in the condensing optical system 74. The beam profilers 540 and 570 may output intensity distributions of light imaged and transferred to the light receiving surface, respectively.

  The second controller 58 (or the first controller 48) may calculate the position, traveling direction, and divergence (wavefront curvature) of the laser light or guide laser light based on the outputs from the beam profilers 540 and 570. Good. For example, the barycentric position of the intensity distribution of the light detected by the beam profilers 540 and 570 may be calculated and used as a value indicating the position of the laser light or the guide laser light. Further, the traveling direction of the laser light or the guide laser light may be calculated from the difference between the center positions of the light intensity distributions detected by the beam profilers 540 and 570. Further, the curvature of the wavefront of the laser light or the guide laser light may be calculated from the beam width (for example, half-value width) of the light detected by the beam profiler 570 and the size of the focal point detected by the beam profiler 540.

  Based on the above calculation result, the second control unit 58 may control at least one of the laser beam traveling direction adjusting mechanism 41 and the beam steering mechanism 51. Alternatively, the first control unit 48 may control the laser beam traveling direction adjustment mechanism 41 based on the above calculation result.

  FIG. 11B schematically shows a modification of the second example of the detector. The modification of the second example may be different from the second example shown in FIG. 11A in that a plurality of bandpass filters 71 and 72 can be used by switching them. As shown in FIG. 11B, the bandpass filters 71 and 72 may be configured to be movable by a drive unit 78. The drive unit 78 may be controlled by the second control unit 58 (or the first control unit 48). The band pass filter 71 may be an optical filter that transmits the laser light output from the laser device 3 with high transmittance and attenuates or blocks light of other wavelengths. The bandpass filter 72 may be an optical filter that transmits guide laser light with high transmittance and attenuates or blocks light of other wavelengths.

  As shown in FIG. 11B, when the driving unit 78 moves the bandpass filter 71 on the optical path of the sample light, the laser light can reach the beam splitter 73. Therefore, the position, traveling direction, and wavefront curvature of the laser beam can be calculated by the second controller 58 (or the first controller 48).

  When the driving unit 78 moves the bandpass filter 72 on the optical path of the sample light, the guide laser light can reach the beam splitter 73. Accordingly, the position, traveling direction, and wavefront curvature of the guide laser beam can be calculated by the second controller 58 (or the first controller 48).

  The condensing optical system 74 and the transfer optical system 75 preferably have a function of correcting chromatic aberration with respect to the wavelengths of the laser light and the guide laser light. For example, the condensing optical system 74 and the transfer optical system 75 are preferably an achromatic lens or a combination thereof. Furthermore, it is preferable that the condensing optical system 74 and the transfer optical system 75 have a configuration with little chromatic aberration in principle. For example, the condensing optical system 74 and the transfer optical system 75 are preferably reflection optical systems.

  According to the modification of the second example, since the same beam profilers 540 and 570 are used to detect the laser beam and the guide laser beam, the traveling direction of the laser beam and the traveling of the guide laser beam are highly accurate. A deviation from the direction can be detected.

10.3 Example Using Shack-Hartmann Wavefront Sensor FIG. 12A schematically shows a third example of a detector in the EUV light generation system according to the above-described embodiment. In the third example, a Shack-Hartmann wavefront sensor may be used to measure the traveling direction of the laser beam or the guide laser beam and the curvature of the wavefront.

  As shown in FIG. 12A, the detector may include a bandpass filter 70 and a Shack-Hartmann wavefront sensor 90. The Shack-Hartmann wavefront sensor 90 may include a microlens array 91 and a CCD (charge coupled device) camera 93.

  The bandpass filter 70 may be an optical filter that transmits light (laser light or guide laser light) to be detected with high transmittance and attenuates or blocks light of other wavelengths. The microlens array 91 may be an optical element in which a plurality of minute convex lenses or concave lenses are two-dimensionally arranged. The CCD camera 93 may be an element for capturing a projection image formed by the microlens array 91.

  The second control unit 58 (or the first control unit 48) may calculate the position, traveling direction, and divergence (wavefront curvature) of the laser beam or guide laser beam based on the output from the CCD camera 93. Based on this calculation result, the second control unit 58 may control at least one of the laser beam traveling direction adjusting mechanism 41 and the beam steering mechanism 51. Alternatively, the first control unit 48 may control the laser beam traveling direction adjustment mechanism 41 based on the calculation result.

  FIG. 12B schematically shows a modification of the third example of the detector. The modification of the third example may be different from the third example shown in FIG. 12A in that the plurality of bandpass filters 71 and 72 can be used by switching them. As shown in FIG. 12B, the bandpass filters 71 and 72 may be configured to be movable by a driving unit 78. The drive unit 78 may be controlled by the second control unit 58 (or the first control unit 48). In the Shack-Hartmann wavefront sensor 90, a screen 92 having a large number of pinholes may be used instead of the microlens array 91. The band pass filter 71 may be an optical filter that transmits the laser light output from the laser device 3 with high transmittance and attenuates or blocks light of other wavelengths. The bandpass filter 72 may be an optical filter that transmits guide laser light with high transmittance and attenuates or blocks light of other wavelengths.

  As illustrated in FIG. 12B, when the driving unit 78 moves the band pass filter 71 on the optical path of the sample light, the laser light can reach the Shack-Hartmann wavefront sensor 90. Therefore, the position, traveling direction, and wavefront curvature of the laser beam can be calculated by the second controller 58 (or the first controller 48).

  When the driving unit 78 moves the bandpass filter 72 on the optical path of the sample light, the guide laser light can reach the Shack-Hartmann wavefront sensor 90. Accordingly, the position, traveling direction, and wavefront curvature of the guide laser beam can be calculated by the second controller 58 (or the first controller 48).

  According to the modification of the third example, since the same Shack-Hartmann wavefront sensor 90 is used to detect the laser beam and the guide laser beam, the traveling direction of the laser beam and the traveling of the guide laser beam are highly accurate. A deviation from the direction can be detected.

10.4 Example Using Optical Position Detector FIG. 13 schematically shows a fourth example of a detector in the EUV light generation system according to the above-described embodiment. In the fourth example, an optical position detector (PSD) may be used to detect the position of the guide laser beam at high speed.

  As shown in FIG. 13, the detector may include a bandpass filter 720, a condensing optical system 740, and an optical position detector 571. The bandpass filter 720 may be an optical filter that transmits guide laser light and attenuates or blocks light of other wavelengths. The condensing optical system 740 may condense the light transmitted through the bandpass filter 720 on the light receiving surface of the optical position detector 571 disposed at a position away from the condensing optical system 740 by the focal length F0. The focal length F0 may be a focal length in the condensing optical system 740. The optical position detector 571 may output the position of the center of gravity of the light collected on the light receiving surface.

  Based on the output result of the optical position detector 571, the second controller 58 may control the beam steering mechanism 51. Since the optical position detector 571 outputs the center of gravity position instead of the light intensity distribution, the processing can be executed at high speed. Therefore, vibrations of the beam steering mechanism 51 and the like can be dealt with, and changes in the traveling direction of the laser light and the guide laser light can be suppressed. A quadrant sensor may be used instead of the optical position detector 571.

10.5 Combination of First to Fourth Examples FIG. 14 schematically illustrates a fifth example of a detector in the EUV light generation system according to the above-described embodiment. In the fifth example, the above first to fourth examples may be combined.

  As described in the third embodiment (see FIG. 6), the pre-pulse laser beam and the first guide laser beam are incident on the first surface of the beam splitter 56, and the second surface of the beam splitter 56 is incident on the second surface. The main pulse laser beam and the second guide laser beam may be incident. At least the pre-pulse laser beam and the main pulse laser beam may be output from the first surface of the beam splitter 56 and introduced into the chamber 2. From the second surface of the beam splitter 56, a part of the pre-pulse laser light, the first guide laser light, a part of the main pulse laser light, and the second guide laser light may be output as sample light.

  On the optical path of the sample light, beam splitters 561, 562 and 56a and a high reflection mirror 56b may be arranged in this order. The beam splitter 561 may reflect a part of the first guide laser light and transmit the remaining sample light. The beam splitter 562 may reflect a part of the second guide laser light and transmit the remaining sample light. The beam splitter 56a may reflect the pre-pulse laser beam and the first guide laser beam with a high reflectance and transmit the main pulse laser beam and the second guide laser beam with a high transmittance. The high reflection mirror 56b may reflect the main pulse laser beam and the second guide laser beam with high reflectivity.

  On the optical path of the first guide laser beam reflected by the beam splitter 561, the same detectors as in the fourth example of the above-described detector, that is, the bandpass filter 721, the condensing optical system 741, and the light A position detector 571 may be arranged. Thereby, the 2nd control part 58 may detect the position of the 1st guide laser beam, and may control the beam steering mechanism 51a at high speed.

  On the optical path of the second guide laser beam reflected by the beam splitter 562, the same detectors as in the fourth example of the above-described detector, that is, the bandpass filter 722, the condensing optical system 742, and the light A position detector 572 may be arranged. Thereby, the 2nd control part 58 may detect the position of a 2nd guide laser beam, and may control the beam steering mechanism 51b at high speed.

  A detector similar to the modified example of the second example of the detector described above may be disposed on the optical paths of the pre-pulse laser beam and the first guide laser beam reflected by the beam splitter 56a. Thereby, the second control unit 58 calculates the position, traveling direction, and wavefront curvature of the pre-pulse laser beam and the first guide laser beam, and controls the beam steering mechanism 51a (or the laser beam traveling direction adjusting mechanism 41a). May be. Instead of a detector similar to the second example of the detector, a detector similar to the first or third example of the detector may be used.

  A detector similar to the modified example of the second example of the detector described above may be disposed on the optical path of the main pulse laser beam and the second guide laser beam reflected by the high reflection mirror 56b. Accordingly, the second control unit 58 calculates the position, traveling direction, and curvature of the wavefront of the main pulse laser beam and the second guide laser beam, and moves the beam steering mechanism 51b (or the laser beam traveling direction adjusting mechanism 41b). You may control. Instead of a detector similar to the second example of the detector, a detector similar to the first or third example of the detector may be used.

11. Supplementary Explanation 11.1 Explanation of Adjustment Mechanism FIG. 15 is a diagram for explaining the operation of the laser beam traveling direction adjustment mechanism. By controlling the posture angles (θx, θy) of the two high reflection mirrors 42 and 43, the traveling direction of the incident laser light may be adjusted to be a desired direction. Here, the direction of the angle θx and the direction of the angle θy may be orthogonal to each other. For example, the mirror holders 421 and 431 (FIG. 2) to which the high reflection mirrors 42 and 43 are mounted may have an adjustment function by a gimbal mechanism. The gimbal mechanism is a kind of turntable that rotates an object around two axes orthogonal to each other.

11.2 Description of Actuator Section FIG. 16 shows a specific example of the actuator section in the laser beam traveling direction adjusting mechanism. The high reflection mirror 42 may be supported by the mirror holder 421, and the mirror holder 421 may be supported to be displaceable with respect to the base portion 423 via the connection portion 422. For example, the connecting portion 422 may be configured by a spring and a guide. The spring applies a force to each of the mirror holder 421 and the base portion 423 so that the mirror holder 421 and the base portion 423 are attracted to each other, and the guide is displaced so that the mirror holder 421 can be displaced in a predetermined direction with respect to the base portion 423 The direction may be restricted. One end of each of the three connection portions 422 in which the piezoelectric element is used may be fixed to the base portion 423. The other end of each of the three connection portions 422 may be in contact with the mirror holder 421. Each of the three connection portions 422 includes a feed mechanism that independently expands and contracts the distance between the base portion 423 and the mirror holder 421 for each connection portion 422 by a drive signal from a driver controlled by the first control unit 48. But you can. The base portion 423 may be fixed to a housing or the like of the laser beam traveling direction adjustment mechanism.

  As described above, the posture of the high reflection mirror 42 may be adjusted in the direction of the angle θx and the direction of the angle θy by expanding and contracting the distances at the three points of the mirror holder 421 with respect to the base portion 423. Actuators for adjusting the postures of the high reflection mirrors 43, 52, 53, etc. may be similarly configured.

  The above description is intended to be illustrative only and not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the embodiments of the present disclosure without departing from the scope of the appended claims.

  Terms used throughout this specification and the appended claims should be construed as "non-limiting" terms. For example, the terms “include” or “included” should be interpreted as “not limited to those described as included”. The term “comprising” should be interpreted as “not limited to what is described as having”. Also, the modifier “one” in the specification and the appended claims should be interpreted to mean “at least one” or “one or more”.

  DESCRIPTION OF SYMBOLS 1 ... EUV light generation apparatus, 2 ... Chamber, 3 ... Laser apparatus, 3a ... Prepulse laser apparatus, 3b ... Main pulse laser apparatus, 4 ... Target sensor, 5 ... EUV light generation control part, 6 ... Exposure apparatus, 9 ... Installation Mechanism: 10 ... Chamber reference member, 11 ... EUV light generation system, 21 ... Window, 22 ... Laser beam collector mirror, 23 ... EUV collector mirror, 24 ... Through-hole, 25 ... Plasma generation region, 26 ... Target supply device , 27 ... target, 28 ... target recovery part, 29 ... connection part, 31, 32, 33 ... pulse laser beam, 34 ... laser beam traveling direction control part, 40, 40a, 40b ... guide laser device, 41, 41a, 41b ... Laser beam traveling direction adjusting mechanism, 42, 43 ... High reflection mirror, 44, 44a, 44b ... Optical path couplers, 45, 45a, 45b ... Light detector 46 ... Beam sampler, 47 ... Detector, 48, 48a, 48b ... First controller, 50a ... High reflection mirror, 51, 51a, 51b ... Beam steering mechanism, 52, 52a, 52b, 53, 53a, 53b ... High Reflection mirror, 55 ... light detection unit, 56, 56a ... beam splitter, 56b ... high reflection mirror, 57 ... detector, 58, 58a, 58b ... second control unit, 58c ... control unit, 59, 59a, 59b ... high Reflection mirror, 60 ... mirror storage container, 61 ... high reflection mirror, 62 ... planar mirror, 66 ... window, 67 ... detector, 68 ... third control unit, 70, 71, 72 ... band pass filter, 73 ... beam splitter 74 ... Condensing optical system, 75 ... Transfer optical system, 77 ... High reflection mirror, 78 ... Drive unit, 79 ... Transfer optical system, 81 ... Adjustment mechanism, 82, 83 ... High reflection mirror , 90 ... Shack-Hartmann wavefront sensor, 91 ... Micro lens array, 92 ... Screen, 93 ... Camera, 220 ... Laser light collecting mirror, 251 ... Radiated light, 252 ... EUV light, 291 ... Wall, 292 ... Intermediate focusing point , 300: Master oscillator, 301, 302, 303, 304 ... Amplifier, 421 ... Mirror holder, 422 ... Connection part, 423 ... Base part, 424 ... Leg part, 431 ... Mirror holder, 432 ... Actuator part, 510 ... Optical path tube 521: Mirror holder, 522 ... Actuator part, 531 ... Mirror holder, 532 ... Actuator part, 540 ... Beam profiler, 561, 562 ... Beam splitter, 570 ... Beam profiler, 571, 572 ... Optical position detector, 590 ... Beam Profiler, 611 ... Steering mirror, 661 ... Window, 720, 721, 722 ... Band pass filter, 740, 741, 742 ... Condensing optical system, F, F0 ... Focal length

Claims (5)

An alignment system used with a laser device that outputs laser light,
A guide laser device that outputs a guide laser beam;
An adjusting mechanism for adjusting the traveling direction of the laser beam;
An optical path coupling unit that substantially matches the traveling directions of the laser beam and the guide laser beam;
A light detection unit disposed downstream of the optical path coupling unit and detecting the laser beam and the guide laser beam;
A control unit for controlling the adjustment mechanism based on a detection result by the light detection unit;
With
The adjusting mechanism is disposed on the upstream side of the optical path of the laser light from the optical path coupling portion.
Alignment system. A second adjusting mechanism for adjusting a traveling direction of the guide laser beam;
The alignment system according to claim 1. The second adjusting mechanism is disposed on the upstream side of the optical path of the guide laser light from the optical path coupling portion.
The alignment system according to claim 2 . A beam steering mechanism that is disposed on the downstream side of the optical path coupling unit and adjusts the traveling direction of the laser beam and the guide laser beam;
The alignment system as described in any one of Claims 1-3. The alignment system according to any one of claims 1 to 4,
A chamber provided with an entrance for introducing the laser beam inside;
A target supply unit provided in the chamber for supplying a target material to a predetermined region in the chamber;
A laser condensing optical system for condensing the laser light in the predetermined region;
An extreme ultraviolet light generator.

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