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US-12619090-B2 - Multibeam 3-D focus generator

US12619090B2US 12619090 B2US12619090 B2US 12619090B2US-12619090-B2

Abstract

The invention relates to a device for focusing a photon beam into a material. The device comprises: means for splitting the photon beam into a plurality of component beams; means for focusing the component beams at a predetermined focal depth within the material; and means for adapting the wavefronts of the component beams based at least in part on the focal depth.

Inventors

  • Markus Seesselberg
  • Johannes Stock

Assignees

  • CARL ZEISS SMT GMBH

Dates

Publication Date
20260505
Application Date
20230512
Priority Date
20220513

Claims (20)

  1. 1 . A device for focusing a photon beam into a material, comprising: means for splitting the photon beam into a plurality of component beams; means for focusing the component beams at a predetermined focal depth within the material; and means for adapting the wavefronts of the component beams based at least in part on the focal depth.
  2. 2 . The device of claim 1 , wherein the means for adapting is configured in such a way that the wavefronts are adapted so as to generate a first given focus quality of the foci of the component beams at a first predetermined focal depth.
  3. 3 . The device of claim 2 , wherein the means for adapting is configured in such a way that the wavefronts are adapted so as to generate a second given focus quality of the foci of the component beams at a second predetermined focal depth.
  4. 4 . The device of claim 2 , wherein the given focus quality is based at least partially on a target state of the wavefronts at the focal depth.
  5. 5 . The device of claim 4 , wherein the given focus quality is based at least in part on a target state of the wavefronts in a plane of the device, which corresponds to a transformation of the target state of the wavefronts at the focal depth.
  6. 6 . The device of claim 4 , wherein the given focus quality comprises a comparison measure of the target state of the wavefronts at the focal depth and/or target state of the wavefronts in the plane of the apparatus with respect to a corresponding actual state of the wavefronts.
  7. 7 . The device of claim 6 , wherein the comparison measure comprises a root mean square (RMS) wavefront error of the actual state at the focal depth with respect to the target state at the focal depth of less than 500 mλ, preferably less than 200 mλ, more preferably less than 100 mλ, most preferably less than 50 mλ.
  8. 8 . The device of claim 1 , wherein the device comprises a means for determining the actual state of the wavefronts, preferably the actual state in a plane of the device and/or at the predetermined focal depth, and a means for controlling the means for adapting based on a deviation of the determined actual state of the wavefronts with respect to a target state of the wavefronts.
  9. 9 . The device of claim 1 , wherein the means for adapting is configured to adapt the wavefronts based at least in part on a refractive index difference experienced by the focused component beams.
  10. 10 . The device of claim 9 , wherein the refractive index difference is caused by a refractive index of a medium adjoining the material and a refractive index of the material.
  11. 11 . The device of claim 1 , wherein the means for adapting is configured in such a way that it adapts the wavefront of the photon beam in order to adapt the wavefronts of the component beams.
  12. 12 . The device of claim 1 , wherein the means for splitting is configured so that at least two component beams have substantially the same energy and/or substantially the same power.
  13. 13 . The device of claim 1 , wherein the means for splitting splits the photon beam into a plurality of component beams by way of a diffraction of the photon beam; and/or wherein the means for splitting splits the photon beam into a plurality of component beams by way of a local phase modulation of the photon beam.
  14. 14 . The device of claim 1 , wherein the means for splitting comprises the means for adapting, with the means for adapting being configured to adapt the wavefront of the photon beam such that the latter is split into the plurality of component beams at the same time.
  15. 15 . The device of claim 1 , wherein the means for splitting is configured to cause a predetermined geometric distribution of the foci of the component beams in the material.
  16. 16 . The device of claim 1 , wherein the means for splitting is arranged in a surround of a pupil and/or in a surround of a conjugate pupil of the means for focusing in the device, in such a way that the component beams are substantially encompassed in the diameter of the pupil of the means for focusing.
  17. 17 . The device of claim 16 , wherein the means for splitting is arranged at a position relative to the pupil so that an intersection of a direction ray of a component beam with a plane of the pupil includes a distance from the center of the pupil of no more than 10% of the diameter, preferably no more than 1% of the diameter, most preferably no more than 0.1% of the diameter of the pupil.
  18. 18 . The device of claim 16 , wherein the means for splitting is arranged at a position relative to the pupil so that the intersections of the direction rays of at least two component beams with the plane of the pupil are arranged within the pupil, and a distance between the intersections is no more than 10% of the diameter of the pupil, preferably no more than 1% of the diameter of the pupil, most preferably no more than 0.1% of the diameter of the pupil.
  19. 19 . The device of claim 2 , wherein the means for focusing is configured so that the given focus quality can be generated without an adaptation of the wavefronts for a predetermined compensated focal depth and for wavefronts incident in substantially planar fashion on the means for focusing.
  20. 20 . The device of claim 1 , wherein the device is configured so that the focal depth is adjusted by displacing the means for focusing and/or by displacing the material.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present patent application claims the priority of the German patent application DE 10 2022 204 688.9, entitled “Multi-Strahl 3D Fokus Generator,” which was filed at the German Patent and Trade Mark Office on May 13, 2022. The German patent application DE 10 2022 204 688.9 is incorporated by reference in its entirety in the present patent application. TECHNICAL FIELD The present invention relates to a device for focusing a photon beam into a material, a corresponding method and computer program. BACKGROUND In the field of optical technologies, applications in which a photon beam is focused within a material in a targeted manner are increasingly tinder discussion. By way of example, applications are known, in which a reaction is generated in the region of the focus of the photon beam in the material, wherein the reaction can locally modify the material in this region or locally transform the material (permanently) into a different state. For application-specific focusing, it may be helpful to place the focus of the photon beam with a defined optical quality and in a targeted manner at different positions within the three-dimensional space of the material, wherein the optical quality should be ensured independently of the position (e.g., with respect to the focal depth, the spatial coordinates) in order to allow a reliable application, for example in the case of an application within the scope of a local material modification. In some applications, the local modification may for example comprise the change of any desired physical property of the material (e.g., a change in a mechanical, an optical and/or a chemical property, etc.). For example, applications are known, in which the focus is introduced in a targeted manner into an object for lithography for the purpose of processing the said object. By way of example, reference in this respect is made to US 2019/170991 A1. In this case, the object may comprise a lithography mask for example. By introducing the focus of a photon beam within the mask, it is possible in the process to implement a corresponding local modification, for example a repair or correction of the mask. Further, other applications that may require focusing within the material are also known, for example within the scope of a (three-dimensional) polymerization (e.g., a multiphoton polymerization), laser drilling in a transparent medium (e.g., in glass), a production of microfluidic systems, etc. In this context, it may be assumed that further applications requiring reliable focusing of a photon beam within a material may arise in future. In previous applications, desired foci with a defined optical quality can be produced within a certain parameter space. However, the parameter space for a satisfactory quality is usually spatially restricted to a certain portion of the material. Moreover, known focus systems usually have time restrictions in relation to the focus generation since the number of foci that can be generated per unit time are often subject to a technical limitation of the system set-up. Further, it may be technically desirable for the focusing to be able to occur with a suitable optical quality within the material, even in the case of different materials or material surrounds (e.g., this should also be ensured in the case of different refractive indices for different materials and material surrounds). However, previous approaches could only partly fulfil the technically desired requirements within the scope of focusing. It is therefore a general aspect of the present invention to improve the focusing within a material. SUMMARY This general aspect is at least partly achieved by the various aspects of the invention. A first aspect relates to a device for focusing a photon beam into a material. The device comprises a means for splitting the photon beam into a plurality of component beams and a means for focusing the component beams at a predetermined focal depth within the material. Further, the device may comprise a means for adapting the wavefronts of the component beams based at least in part on the focal depth. Accordingly, the invention can allow not only the introduction of one photon beam within the material but the possibility of introducing a plurality of component beams into the material. In the process, the plurality of component beams can be focused (substantially) simultaneously into the material, with the result that a plurality of foci are present (substantially) simultaneously at the predetermined focal depth. In this case, the foci at the predetermined focal depth may be in the form of spatially separable and distinguishable foci, which for example are situated at different surface coordinates at the predetermined focal depth. Thus, the invention may firstly allow the parallel or simultaneous generation of foci within a material; this may be advantageous for various applications. The scope of processing the material may req