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KR-20260065817-A - Measuring device for determining the position of a moving component

KR20260065817AKR 20260065817 AKR20260065817 AKR 20260065817AKR-20260065817-A

Abstract

A measuring device (10; 110, 210; 310) for determining the position of a movable component (526) in a microlithographic optical system (500) comprises: an optical resonator (26) having two resonator mirrors (28, 30) surrounding a resonator cavity (32), and a movable measuring mirror (14) arranged within the resonator cavity to be assigned to the component and to direct measuring radiation back and forth between the resonator mirrors. The measuring mirror is arranged at an operating distance (34) from one of the resonator mirrors, and the resonator mirror has a curvature that is matched to the measuring mirror in this manner, such that the center of curvature (31) is arranged on the measuring mirror or at a distance of 10% or less of the operating distance from the measuring mirror.

Inventors

  • 뮌츠 홀거

Assignees

  • 칼 짜이스 에스엠테 게엠베하

Dates

Publication Date
20260511
Application Date
20240830
Priority Date
20230904

Claims (20)

  1. A measuring device (10; 110, 210; 310) for determining the position of a movable component (526) in a microlithographic optical system (500), and - An optical resonator (26) having two resonator mirrors (28, 30) surrounding a resonator cavity (32), and - Includes a movable measuring mirror (14) that is assigned to a component and arranged within the resonator cavity to direct the measuring radiation back and forth between the resonator mirrors, and A measuring device in which a measuring mirror is arranged at an operating distance (34) from one of the resonator mirrors, and the resonator mirror has a curvature that matches the measuring mirror, and accordingly, the center (31) of the curvature is arranged on the measuring mirror or at a distance of 20% or less of the operating distance from the measuring mirror.
  2. In paragraph 1, One of the resonator mirrors (28) is configured as an input coupling mirror for input coupling of the measurement radiation (18) into the resonator cavity, and the other resonator mirror (30) is configured as a counter mirror for the input coupling mirror, and the resonator mirror (30) having a curvature matched to the measurement mirror is the counter mirror, a measuring device.
  3. In paragraph 1 or 2, A measuring device in which an optical resonator (26) is configured to form a beam path having a beam waist (38) for a measuring radiation (18), and the beam waist has a curvature that matches the measuring mirror and is positioned between the measuring mirror (14) and the first resonator mirror (30).
  4. In paragraph 3, A measuring device, wherein the beam waist (38) is arranged at a distance of at least 5% of the working distance (34) from the measuring mirror (14) and at least 5% of the working distance (34) from the first resonator mirror (30).
  5. In any one of paragraphs 1 through 4, A measuring device comprising a resonator mirror (30) that is part of an optical resonator and has a curvature matched to a measuring mirror (14), and another resonator mirror (28) that surrounds the resonator cavity (32), wherein the center (29) is located on the side of the measuring mirror facing the other resonator mirror and has a curvature at a distance of at least 10% of the working distance (34) from the measuring mirror.
  6. In paragraph 3 or 4, Another resonator mirror (28) surrounding the resonator cavity (32) together with the first resonator mirror (30) has a curvature, and the relationship described below applies to the radius of curvature (R2) of the first resonator mirror, the radius of curvature (R1) of the other resonator mirror, and the relative distance (a) of the beam waist from the first resonator mirror with respect to the operating distance (34): A measuring device having, or having a deviation of 10% or less from this relationship.
  7. In any one of paragraphs 1 through 6, A measuring device in which the measuring mirror is configured as a flat mirror.
  8. In any one of paragraphs 1 through 7, An optical resonator (26) is a measuring device configured such that the measuring radiation (18) emitted from the measuring mirror (14) forms an angle of 100 mrad or less with the measuring radiation (18) reflected therefrom.
  9. In paragraph 8, A measuring device in which two resonator mirrors are arranged offset from each other with respect to the incident direction of the measuring radiation in the measuring mirror (14).
  10. In any one of paragraphs 1 through 9, An optical resonator is a measuring device configured such that the measuring radiation emitted from a measuring mirror forms an angle of 1 mrad or less with the measuring radiation reflected thereon.
  11. In any one of paragraphs 1 through 10, A measuring device in which a polarizing beam splitter is arranged within the beam path of an optical resonator, and the beam path of the measuring radiation between the measuring mirror and one of the resonator mirrors is deflected thereon.
  12. In any one of paragraphs 1 through 10, A measuring device in which the resonator operates in a Laguerre-Gauss mode having an azimuth index of at least 1.
  13. In any one of paragraphs 1 through 10 or paragraph 12, A measuring device having one of two resonator mirrors having a central cutout where the other resonator mirror is arranged.
  14. In any one of paragraphs 1 through 13, A measuring device having an operating distance of at least 2 cm.
  15. A microlithographic projection exposure apparatus having at least one movable component and at least one measuring device according to any one of claims 1 to 14 for determining the position of the movable component.
  16. In paragraph 15, A projection exposure device comprising a plurality of optical elements for guiding exposure radiation within the projection exposure device, wherein one of the optical elements acts as a movable component.
  17. A lighting device (515) for a microlithographic projection exposure device having at least one movable component and at least one measuring device according to any one of claims 1 to 14 for determining the position of the movable component.
  18. A projection lens (516) for a microlithographic projection exposure device having at least one movable component and at least one measuring device according to any one of claims 1 to 14 for determining the position of the movable component.
  19. An inspection device for inspecting the surface of a substrate, particularly a mask or wafer for microlithography, and having at least one measuring device according to any one of claims 1 to 14 for determining the position of at least one movable component.
  20. A coordinate measuring device having at least one movable component and at least one measuring device according to any one of claims 1 to 14 for determining the position of the movable component.

Description

Measuring device for determining the position of a moving component This application claims priority to German patent application No. 10 2023 208 513.5, filed on September 4, 2023. The entire contents of this patent application are incorporated herein by reference. The present invention relates to a measuring device for determining the position of a movable component within a microlithographic optical system, a microlithographic projection exposure device each having at least one such measuring device, an illumination device, a projection lens, an inspection device, and a coordinate measuring device. Microlithography is used to manufacture microstructured components, such as integrated circuits or LCDs. This is implemented by a so-called projection exposure device comprising an illumination device and a projection lens. In this context, an image of a mask positioned on a reticle and illuminated by an illumination device is projected by a projection lens onto a substrate (e.g., a silicon wafer) coated with a photosensitive layer (photoresist) and aligned within the image plane of the projection lens in order to transfer the mask structure onto the photosensitive coating of the substrate. During the operation of these projection lenses, in which the mask and wafer are typically moved relative to each other during the scanning process, the position of the mirror, which is partially movable in all six degrees of freedom, must be set and maintained with high accuracy relative to each other and also relative to the mask and/or wafer to avoid or at least reduce aberrations and associated damage to the imaging results. Determining this position may require very high accuracy, especially in EUV lithography. Various approaches for measuring the position of individual lens mirrors and also of wafers, wafer stages, and reticle planes are known in the prior art. In addition to interferometric devices, frequency-based position measurement using optical resonators is also known herein. The structure used for this purpose according to FIG. 3 of US11,274,914B2 comprises a resonator having two resonator mirrors, a retroreflector in the form of a triple mirror, and a planar mirror that serves as a measurement target and in which the beam path is folded. The resonator mirrors and the triple mirror represent a measurement head that is rigidly connected to the housing of a projection lens within a projection exposure device, and the measurement target is attached to an element of the projection exposure device intended to be measured in terms of its position. The actual distance measuring device comprises a radiation source that generates input coupled radiation that is adjustable for its optical frequency, passes through a beam splitter, and is input coupled within an optical resonator. In this case, the radiation source is controlled by a coupling device in such a way that the optical frequency of the radiation source is adjusted to the resonant frequency of the optical resonator and thus coupled to said resonant frequency. The input coupled radiation output coupled through the beam splitter is analyzed by an optical frequency measuring device, which may include, for example, a frequency comb generator for highly accurate determination of the absolute frequency. When the position of the component to be measured changes in the direction of the range of the resonator, along with the distance between the resonator mirrors, the resonant frequency of the optical resonator also changes, and thus—due to the coupling of the frequency of the adjustable radiation source with respect to the resonant frequency of the resonator—the optical frequency of the input coupled radiation likewise changes, which is then directly matched by the frequency measuring device. The use of a planar mirror as a measurement target, as illustrated in FIG. 3 of US11,274,914B2, is preferable to a triple mirror, which may also be used here, for optomechanical reasons, particularly in relation to avoiding multiple reflections and reducing the size of the structure. However, a slight tilt of the planar mirror during its axial displacement during the measurement mode can result in a lateral offset of the modes formed within the resonator on the resonator mirror acting as the input coupling mirror, thereby reducing the coupling efficiency of the radiation field ("input coupling field") present at the input of the resonator path into the mode field ("resonator field") of the optical resonator. A reduction in coupling efficiency exceeding a certain tolerance limit impairs the measurement accuracy of the position measurement, and as a result, the measurement may become unusable. A similar effect may also occur when a non-planar mirror is used as a measurement target. The aforementioned features and other advantageous features of the present invention will be illustrated in the following detailed description of exemplary embodiments or embodiments or variations of embod