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EP-4735957-A1 - ASSEMBLY IN A MICROLITHOGRAPHIC PROJECTION EXPOSURE SYSTEM

EP4735957A1EP 4735957 A1EP4735957 A1EP 4735957A1EP-4735957-A1

Abstract

The invention relates to an assembly in a microlithographic projection exposure system, the assembly (100, 200, 300, 400) comprising: an optical element (101, 201, 301, 401); at least one weight-force compensation device (110, 210, 310, 410) having a passive magnetic circuit (111, 211, 311, 411) for generating a magnetic field which causes a force for at least partially compensating for the weight force acting on the optical element and having an active component for generating an actively controllable force transmitted to the optical element, the at least one weight-force compensation device (110, 210, 310, 410) being coupled to the optical element (101, 201, 301, 401) by means of an articulatedly mounted pin (115, 215, 315, 415); and at least three Lorentz actuators (120, 130, 220, 230, 320, 330, 340, 420, 430, 440) each designed to exert a controllable force on the optical element, at least one of said Lorentz actuators being fastened directly to the optical element.

Inventors

  • SCHOENHOFF, ULRICH

Assignees

  • Carl Zeiss SMT GmbH

Dates

Publication Date
20260506
Application Date
20240527

Claims (13)

  1. 1. Assembly in a microlithographic projection exposure system, the assembly (100, 200, 300, 400) comprising: • an optical element (101, 201, 301, 401); • at least one weight force compensation device (1 10, 210, 310, 410) with - a passive magnetic circuit (1 1 1 , 21 1 , 31 1 , 41 1 ) for generating a magnetic field which produces a force for at least partially compensating the weight force acting on the optical element (101 , 201 , 301 , 401 ), and - an active component for generating an actively controllable force transmitted to the optical element (101, 201, 301, 401); - wherein the at least one weight force compensation device (110, 210, 310, 410) is coupled to the optical element (101, 201, 301, 401) via an articulated pin (115, 215, 315, 415); and • at least three Lorentz actuators (120, 130, 220, 230, 320, 330, 340, 420, 430, 440) each designed to exert a controllable force on the optical element (101, 201, 301, 401), wherein at least one of these Lorentz actuators is fixed directly to the optical element (101, 201, 301, 401).
  2. 2. Assembly according to claim 1, characterized in that the active component comprises at least one coil (112, 212, 312, 412) to which electrical current can be applied.
  3. 3. Assembly according to claim 1 or 2, characterized in that at least three, in particular at least six of these Lorentz actuators (120, 130, 220, 230, 320, 330, 340, 420, 430, 440) are mounted directly on the optical element (101 , 201 , 301 , 401 ) are fixed.
  4. 4. Assembly according to one of claims 1 to 3, characterized in that a natural frequency of this coupling is less than 3 times, in particular less than 2 times, further in particular less than 1.5 times the control bandwidth.
  5. 5. Assembly according to one of the preceding claims, characterized in that it has at least two, in particular at least three such weight force compensation devices (110, 210, 310, 410).
  6. 6. Assembly according to one of claims 1 to 5, characterized in that it has three actuator units, each of these actuator units having a weight force compensation device and two Lorentz actuators, these Lorentz actuators and the weight force compensation device each running towards a common force introduction point.
  7. 7. Assembly according to one of claims 1 to 5, characterized in that it has three actuator units, each of these actuator units having a weight force compensation device, a Lorentz actuator and an inertial actuator, the Lorentz actuator, the inertial actuator and the weight force compensation device each running towards a common force introduction point.
  8. 8. Assembly according to one of the preceding claims, characterized in that it has more than three, in particular more than six Lorentz actuators for exerting a controllable force on the optical element (101, 201, 301, 401) in the vertical direction.
  9. 9. Assembly according to one of the preceding claims, characterized in that it is designed to exert a controllable force on the optical Element (401) has at least three inertial actuators, in particular at least six inertial actuators for partially decoupling a reaction path associated with the application of the controllable force to the optical element (401).
  10. 10. Assembly according to one of the preceding claims, characterized in that it further comprises a controller, said controller being designed to separately control the weight force compensation device for exerting static forces and the Lorentz actuators for exerting dynamic forces.
  11. 1 1. Assembly according to claim 10, characterized in that the control of the weight force compensation device takes place via an integrator branch (I-component) and the control of the Lorentz actuators takes place via a separate PD branch.
  12. 12. Assembly according to one of the preceding claims, characterized in that the optical element (101, 201, 301, 401) is a mirror.
  13. 13. Optical system, in particular of a microlithographic projection exposure system, characterized in that it has at least one assembly according to one of the preceding claims.

Description

assembly in a microlithographic projection exposure system The present application claims priority from German patent application DE 10 2023 206 041.8, filed on June 27, 2023. The content of this DE application is incorporated by reference into the present application text. BACKGROUND OF THE INVENTION field of the invention The invention relates to an assembly in a microlithographic projection exposure system. State of the art Microlithography is used to produce microstructured components, such as integrated circuits or LCDs. The microlithography process is carried out in a so-called projection exposure system, which has an illumination device and a projection lens. The image of a mask (= reticle) illuminated by the illumination device is projected by the projection lens onto a substrate (e.g. a silicon wafer) coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection lens in order to transfer the mask structure onto the light-sensitive coating of the substrate. In a projection exposure system designed for EUV (eg for wavelengths of eg about 13 nm or about 7 nm), mirrors are used as optical components for the imaging process due to the lack of transparent materials. These mirrors can be attached to a support frame and designed to be at least partially manipulable in order to enable movement of the respective mirror in six degrees of freedom (ie with regard to displacements in the three spatial directions x, y and z and with regard to rotations R x , Ry and Rz about the corresponding axes). Changes in the optical properties that occur during operation of the projection exposure system, eg as a result of thermal influences, can be compensated for. For example, it is known to use three actuator arrangements in a projection lens of an EUV projection exposure system for manipulating optical elements such as mirrors in up to six degrees of freedom - as schematically indicated in Fig. 13 - which each have at least two Lorentz actuators 1302 and 1303, 1304 and 1305 or 1306 and 1307 (i.e. two actively controllable axes of movement). Furthermore, in the structure of Fig. 13, for each of these actuator arrangements or for each associated force introduction point, a weight compensation device (also referred to as "MGC" = "Magnetic Gravity Compensator") is provided which carries the mass of an optical element or mirror 1300 in order to minimize the energy consumption of the active or controllable actuating elements, so that no permanent energy flow with the associated heat generation is required. The weight compensation device can be adjustable to a certain holding force, which is transferred to the mirror 1300 via a mechanical element (pin) 1315, 1325 or 1335 which is mechanically coupled to the mirror 1300. Furthermore, it is also known, for example, to design the weight compensation device to additionally exert a controllable force. There are different approaches to connecting the Lorentz actuators and the weight compensation device. A particular problem that occurs during operation is that, depending on the specific configuration, comparatively high parasitic moments or forces are transferred to the mirror, particularly via the Lorentz actuators, which in turn leads to undesirable deformations of the optical effective surface of the mirror in question and thus to an impairment of the performance of the optical system. In the course of increasing demands on the projection exposure system in terms of achieved resolution and contrast and the associated increasing numerical apertures and mirror sizes, the coupling of both the Lorentz actuators and the weight force compensation device represents an increasingly demanding challenge. For the state of the art, reference is made solely to DE 10 2009 054 549 A1, WO 2012/084675 A1, DE 10 2018 202 694 A1 and DE 10 2018 207 949 A1 as examples. SUMMARY OF THE INVENTION It is an object of the present invention to provide an assembly in a microlithographic projection exposure system which enables an actuation of an optical element that is as free from interference and deformation as possible while at least largely avoiding the problems described above. This object is solved according to the features of independent claim 1. An assembly according to the invention, in particular in a microlithographic projection exposure system, comprises: an optical element; at least one weight force compensation device with - a passive magnetic circuit for generating a magnetic field which produces a force for at least partially compensating the weight force acting on the optical element, and - an active component for generating an actively controllable force transmitted to the optical element; - wherein the at least one weight force compensation device is coupled to the optical element via an articulated pin; • and at least three Lorentz actuators, each designed to exert a controllable force on the optical element, wherein at least one of these Lorentz ac