# US 2025/0085641 A1 · Calibration system for an extreme ultraviolet light source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0085641 A1 - Document ID: US20250085641A1 - Status: Published application - Kind: A1 - Application number: 18/960,519 - Filed: 2024-11-26 - Published: 2025-03-13 - Earliest claimed: 2019-12-20 - Assignees: ASML Netherlands B.V. - Applicants: ASML Netherlands B.V. - Inventors: Daniel Jason Riggs; Liane Manuela Matthes; Rilpho Ludovicus Donker; Martinus Hendrikus Antonius Leenders - Web page: https://patentgrep.com/patent/US20250085641A1 ## CPC - G03F 7/70558: {Dose control, i.e. achievement of a desired dose} - G01B 11/24: for measuring contours or curvatures - G02B 5/0891: {Ultraviolet [UV] mirrors (apparatus for microlithography exposure G03F7/70; X-ray multilayer structures G21K1/06)} - G03F 7/70033: {by plasma extreme ultraviolet [EUV] sources} - G03F 7/70041: {by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control} - G03F 7/7085: {Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load} - H05G 2/0027: {Arrangements for controlling the supply; Arrangements for measurements} - H05G 2/0084: {Control of the laser beam} - G02B 26/08: for controlling the direction of light (in light guides G02B6/35) - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H05G: X-RAY TECHNIQUE (investigating or analysing materials by the use of X-rays G01N23/00; apparatus for X-ray photography G03B42/02; X-ray tubes H01J35/00; TV systems having X-ray input H04N5/321) ## Abstract A metrology system includes a light beam metrology apparatus configured to sense one or more aspects of an amplified light beam and to make adjustments to the amplified light beam based on the sensed one or more aspects; a target metrology apparatus configured to measure one or more properties of a modified target after a target has interacted with the amplified light beam, and to determine a moment when the modified target achieves a reference calibration state; and a control apparatus configured to: receive the reference calibration state and the moment at which the reference calibration state is achieved from the target metrology apparatus; determine a light beam calibration state of the amplified light beam based on the received reference calibration state and the moment at which the reference calibration state is achieved; and provide the light beam calibration state to the light beam metrology apparatus. ## Claims ### Claim 1 An alignment apparatus comprising: a light source configured to: direct a first amplified light beam toward a target space such that an interaction between the first amplified light beam and a moving target in the target space forms a modified target; and direct a second amplified light beam toward the target space such that an interaction between the second amplified light beam and the modified target in the target space generates plasma; and a light beam actuation system configured to: adjust a position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target; and after adjusting the position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target, adjust the position of the second amplified light beam relative to the first amplified light beam to cause the second amplified light beam to overlap the modified target. ### Claim 2 (depends on 1) The alignment apparatus of claim 1, wherein the light beam actuation system comprises a steering mechanism configured to steer or adjust a direction of the amplified light beam. ### Claim 3 (depends on 1) The alignment apparatus of claim 1, further comprising a target metrology apparatus configured to image one or more of: the interaction between the first amplified light beam and the target; the interaction between the second amplified light beam and the modified target; the target; and the modified target. ### Claim 4 (depends on 3) The alignment apparatus of claim 3, wherein the light beam actuation system is configured to adjust the position of the first amplified light beam relative to the target based on the imaging. ### Claim 5 (depends on 3) The alignment apparatus of claim 3, wherein the light beam actuation system is configured to adjust the position of the first amplified light beam relative to the target based on an orientation of the modified target determined from imaging the modified target. ### Claim 6 (depends on 3) The alignment apparatus of claim 3, wherein the target metrology is configured to determine when the second amplified light beam and the modified target overlap. ### Claim 7 (depends on 1) The alignment apparatus of claim 1, wherein the light beam actuation system is configured to adjust the position of the second amplified light beam relative to the first amplified light beam to cause the second amplified light beam to overlap the modified target by moving the second amplified light beam to center the modified target. ### Claim 8 (depends on 1) The alignment apparatus of claim 1, wherein the light beam actuation system is configured to adjust the position of the second amplified light beam relative to the first amplified light beam to cause the second amplified light beam to overlap the modified target by moving the second amplified light beam to maximize the overlap such that the second amplified light beam overlaps with a greater area of the modified target. ### Claim 9 (depends on 1) The alignment apparatus of claim 1, wherein the light beam actuation system is configured to adjust the position of the second amplified light beam relative to the first amplified light beam to cause the second amplified light beam to overlap the modified target by adjusting the position of the second amplified light beam along a direction that is perpendicular to a direction at which the second amplified light beam travels. ### Claim 10 (depends on 1) The alignment apparatus of claim 1, wherein the light beam actuation system is configured to adjust the position of the second amplified light beam relative to the first amplified light beam to cause the second amplified light beam to overlap the modified target by adjusting a beam waist of the second amplified light beam along a direction at which the second amplified light beam travels. ### Claim 11 (depends on 10) The alignment apparatus of claim 10, wherein the light beam actuation system is configured to adjust the beam waist of the second amplified light beam along the direction at which the second amplified light beam travels by an amount that improves an amount of EUV light produced by the generated plasma. ### Claim 12 (depends on 1) The alignment apparatus of claim 1, wherein the light beam actuation system is configured to measure a position of the second amplified light beam relative to a position of the first amplified light beam. ### Claim 13 (depends on 12) The alignment apparatus of claim 12, wherein the light beam actuation system is configured to adjust the position of the second amplified light beam relative to the first amplified light beam based on the measured position of the second amplified light beam relative to the position of the first amplified light beam. ### Claim 14 An alignment method comprising: directing a first amplified light beam toward a target space such that an interaction between the first amplified light beam and a moving target in the target space forms a modified target; directing a second amplified light beam toward the target space such that an interaction between the second amplified light beam and the modified target in the target space generates plasma; adjusting a position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target; and after adjusting the position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target, adjusting the position of the second amplified light beam relative to the first amplified light beam to cause the second amplified light beam to overlap the modified target. ### Claim 15 (depends on 14) The alignment method of claim 14, wherein adjusting the position of the first amplified light beam relative to the target is based on an interaction between the first amplified light beam and the target. ### Claim 16 (depends on 14) The alignment method of claim 14, wherein adjusting the position of the first amplified light beam relative to the target is based on imaging of the modified target. ### Claim 17 (depends on 14) The alignment method of claim 14, wherein adjusting the position of the first amplified light beam relative to the target is based on an orientation of the modified target. ### Claim 18 (depends on 14) The alignment method of claim 14, wherein adjusting the position of the second amplified light beam relative to the first amplified light beam to cause the second amplified light beam to overlap the modified target comprises moving the second amplified light beam to center the modified target. ### Claim 19 (depends on 14) The alignment method of claim 14, wherein adjusting the position of the second amplified light beam relative to the first amplified light beam to cause the second amplified light beam to overlap the modified target comprises moving the second amplified light beam to maximize the overlap such that the second amplified light beam overlaps with a greater area of the modified target. ### Claim 20 (depends on 14) The alignment method of claim 14, wherein adjusting the position of the second amplified light beam relative to the first amplified light beam comprises adjusting the position of the second amplified light beam along a direction that is perpendicular to a direction at which the second amplified light beam travels. ### Claim 21 (depends on 14) The alignment method of claim 14, wherein adjusting the position of the second amplified light beam relative to the first amplified light beam comprises adjusting a beam waist of the second amplified light beam along a direction at which the second amplified light beam travels. ### Claim 22 (depends on 21) The alignment method of claim 21, wherein adjusting the beam waist of the second amplified light beam along the direction at which the second amplified light beam travels comprises adjusting by an amount that improves an amount of EUV light produced by the generated plasma. ### Claim 23 (depends on 14) The alignment method of claim 14, further comprising measuring a position of the second amplified light beam relative to a position of the first amplified light beam. ### Claim 24 (depends on 23) The alignment method of claim 23, wherein adjusting the position of the second amplified light beam relative to the first amplified light beam is based on the measured position of the second amplified light beam relative to the position of the first amplified light beam. ### Claim 25 An alignment apparatus comprising: a light source configured to direct a first amplified light beam toward a target space within a chamber such that an interaction between the first amplified light beam and a moving target in the target space forms a modified target; a target metrology apparatus configured to detect the interaction between the first amplified beam and the target; and a control system in communication with the light source and the target metrology apparatus, the control system configured to: analyze the detected interaction output from the target metrology apparatus; and instruct the light source to adjust a position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target, the adjustment being based on the analysis of the detected interaction. ### Claim 26 (depends on 25) The alignment apparatus of claim 25, wherein the light source is configured to direct a second amplified light beam toward the target space such that an interaction between the second amplified light beam and the modified target in the target space generates plasma. ### Claim 27 (depends on 25) The alignment apparatus of claim 25, wherein the target metrology apparatus comprises a camera arranged so that the target space is in the field of view of the camera. ### Claim 28 (depends on 25) The alignment apparatus of claim 25, wherein the target metrology apparatus comprises two cameras arranged at different viewing angles and both arranged so that the target space is in their respective fields of view. ### Claim 29 (depends on 25) The alignment apparatus of claim 25, wherein the control system is configured to activate the target metrology apparatus to thereby detect the interaction between the first amplified light beam and the target based on information regarding the first amplified light beam provided by the light source. ### Claim 30 (depends on 29) The alignment apparatus of claim 29, wherein the target metrology apparatus includes a dual droplet formation camera system that includes an illumination system and at least two cameras. ### Claim 31 (depends on 30) The alignment apparatus of claim 30, wherein the at least two cameras and the illumination system are mechanically referenced to a reference point in the chamber, wherein the reference point is a location within the target space, or a primary focus at which extreme ultraviolet light produced from the plasma is collected. ### Claim 32 (depends on 25) The alignment apparatus of claim 25, further comprising an extreme ultraviolet (EUV) light collector defining a primary focus configured to collect EUV light and to direct EUV light to an intermediate focus. ### Claim 33 (depends on 32) The alignment apparatus of claim 32, wherein the target metrology apparatus includes a dual droplet formation camera system including two cameras that are oriented such that the primary focus of the EUV light collector is in the field of view of each camera. ### Claim 34 (depends on 32) The alignment apparatus of claim 32, wherein the target metrology apparatus comprises a target steerer, the control system is in communication with the target steerer and is configured to adjust the position of the target stream to thereby align the target stream to the primary focus of the EUV light collector. ### Claim 35 (depends on 34) The alignment apparatus of claim 34, wherein the control system is configured to instruct the light source to adjust the position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target, the adjustment being based on the analysis of the detected interaction after the target stream has been aligned to the primary focus of the EUV light collector. ### Claim 36 An alignment method comprising: directing a first amplified light beam toward a target space within a chamber such that an interaction between the first amplified light beam and a moving target in the target space forms a modified target; detecting the interaction between the first amplified beam and the target; analyzing the detected interaction; and adjusting a position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target, the adjustment being based on the analysis of the detected interaction. ### Claim 37 (depends on 36) The alignment method of claim 36, wherein detecting the interaction between the first amplified light beam and the target comprises imaging the target at at least one image plane facing the target space. ### Claim 38 (depends on 36) The alignment method of claim 36, wherein detecting the interaction between the first amplified light beam and the target comprises imaging the target at two differently angled image planes, each facing the target space. ### Claim 39 (depends on 36) The alignment method of claim 36, wherein detecting the interaction between the first amplified light beam and the target comprises detecting the interaction upon a trigger signal that is generated based on a time at which the first amplified light beam is generated. ### Claim 40 (depends on 36) The alignment method of claim 36, wherein detecting the interaction between the first amplified light beam and the target comprises imaging, at a primary image plane, a backlit image of the target. ### Claim 41 (depends on 40) The alignment method of claim 40, wherein detecting the interaction between the first amplified light beam and the target comprises imaging, at a secondary image plane that is distinct from the primary image plane, a second backlit image of the target. ### Claim 42 (depends on 36) The alignment method of claim 36, further comprising collecting extreme ultraviolet (EUV) light produced by the generated plasma at a primary focus and directing the EUV light to an intermediate focus. ### Claim 43 (depends on 42) The alignment method of claim 42, further comprising, prior to adjusting the position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target, adjusting a position of the target stream to thereby align the target stream to the primary focus. ### Claim 44 (depends on 36) The alignment method of claim 36, further comprising, after adjusting the position of the first amplified light beam relative to the target to cause the first amplified light beam to overlap the target, adjusting a position of a second amplified light beam directed toward the target space relative to the modified target to cause the second amplified light beam to overlap the modified target.