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EP-4735960-A1 - OPTICAL MODULE AND PROJECTION EXPOSURE SYSTEM

EP4735960A1EP 4735960 A1EP4735960 A1EP 4735960A1EP-4735960-A1

Abstract

The invention relates to an optical module (30, 40, 50) with an optical element (M3), wherein the optical element (M3) has an optical active surface (31) and is connected to a reinforcing body (32) via at least one connecting element (33, 41). The connecting element is characterized in that the connecting element (33, 41) comprises a decoupling region (34, 42.2, 42.3) by means of which a mechanical decoupling of the reinforcing body (32) and of the optical element (M3) parallel to the optical active surface (31) is produced. In the process, the material of the reinforcing body (32) can have an elastic modulus which is greater than that of the material of the optical element (M3) at least by a factor of two, preferably by a factor of three, particularly preferably by a factor of four, and/or the reinforcing body (32) can be made of a ceramic material, in particular a silicon carbide. The invention additionally relates to a projection exposure system (1, 101) for semiconductor lithography, comprising an optical module (30, 40, 50) according to one of the described embodiments.

Inventors

  • KUGLER, JENS
  • Raba, Andreas
  • NEFZI, MARWENE

Assignees

  • Carl Zeiss SMT GmbH

Dates

Publication Date
20260506
Application Date
20240626

Claims (17)

  1. 1. Optical module (30, 40, 50) with an optical element (M3), wherein the optical element (M3) has an optical active surface (31) and is connected to a stiffening body (32) via at least one connecting element (33, 41), wherein the connecting element (33, 41) comprises a decoupling region (34, 42.2, 42.3) by means of which a mechanical decoupling of the stiffening body (32) and the optical element (M3) parallel to the optical active surface (31) is created, characterized in that the material of the stiffening body (32) has an E-modulus that is at least two times higher, preferably three times higher, particularly preferably four times higher than the material of the optical element (M3).
  2. 2. Optical module according to claim 1, characterized in that the stiffening body (32) is made of a ceramic material, in particular silicon carbide.
  3. 3. Optical module (30,40,50) with an optical element (M3), wherein the optical element (M3) has an optical active surface (31) and is connected to a stiffening body (32) via at least one connecting element (33,41), wherein the connecting element (33,41) comprises a decoupling region (34,42.2,42.3) by means of which a mechanical decoupling of the stiffening body (32) and the optical element (M3) parallel to the optical active surface (31) is created, characterized in that the stiffening body (32) is made of a ceramic material, in particular of silicon carbide.
  4. 4. Optical module (30,40,50) according to one of claims 1 to 3, characterized in that the at least one connecting element (33,41) is directed in the direction of an optical Axis (36,46) of the optical module (30) is arranged between the optical element (M3) and the stiffening body (32).
  5. 5. Optical module (30,40,50) according to one of claims 1 to 4, characterized in that the at least one connecting element is designed as an actuator (41).
  6. 6. Optical module (30,40,50) according to claim 5, characterized in that the actuator (41) comprises at least one region (42.2,42.3) which can be deflected parallel to the optical active surface (31).
  7. 7. Optical module (30,40,50) according to claim 6, characterized in that the actuator (41) comprises at least two regions (42.2,42.3) which can be deflected perpendicular to one another and parallel to the optical active surface (31).
  8. 8. Optical module (30,40,50) according to one of claims 6 or 7, characterized in that the at least one region (42.2,42.3) is actively controllable.
  9. 9. Optical module (30,40,50) according to one of claims 5 to 8, characterized in that the actuator (41) comprises at least one region (42.1) which can be deflected perpendicular to the optical active surface (31).
  10. 10. Optical module (30,40,50) according to one of claims 6 to 9, characterized in that the at least one region (42.2,42.3) which can be deflected parallel to the optical active surface (31) is connected to an evaluation unit which is designed to detect mechanical stresses.
  11. 11 .Optical module (50) according to one of the preceding claims, characterized in that the stiffening body (51) has at least one thickened region (54,55).
  12. 12. Optical module (50) according to claim 11, characterized in that at least one thickened region (54) is designed as a stiffening rib.
  13. 13. Optical module (50) according to claim 11 or 12, characterized in that at least one thickened region (55) is designed as a reference region on which sensor elements (57) are arranged.
  14. 14. Optical module (50) according to one of the preceding claims, characterized in that the optical element (M3) and/or the stiffening body (51) have fluid channels (61).
  15. 15. Optical module (50) according to one of the preceding claims, characterized in that the optical element (M3) is a mirror.
  16. 16. Optical module (330,340) according to one of the preceding claims, characterized in that the at least one connecting element (41 ,250,260,273,283,293,294,321 ,343) at least one area (242,252,274,291 ) which can be deflected parallel to the optical axis (36,46) - and wherein the at least one connecting element (41 ,250,260,273,283,293,294,321 ,343) at least one area (43,251 ,278,295,257) which is parallel to the optical effective surface (31 ,41 ,271 ) is deflectable, - and wherein the at least one connecting element (41,250,260,273,283,293,294,321,343) as a hybrid connecting element (241 ,273) is formed - and wherein the region (242,252,274,291,258) which can be deflected parallel to the optical axis (36,46) is designed as a passive decoupling element (292) and the region (43,251,278,295,257) which can be deflected parallel to the optical effective surface (31,41,271) is designed as an actuator (283,291).
  17. 17. Projection exposure system (1, 101) for semiconductor lithography, with an optical module (330,340) according to one of the preceding claims.

Description

Optical module and projection exposure system The present application claims the priorities of the German patent applications DE 10 2023 116 895.9 and DE 10 2023 116 899.1 , filed on June 27, 2023, the contents of which are incorporated herein in their entirety by reference. The invention relates to an optical module for a projection exposure system and a projection exposure system for semiconductor lithography. Projection exposure systems for semiconductor lithography are used to create the finest structures, particularly on semiconductor components or other microstructured components. The functional principle of the systems mentioned is based on creating the finest structures down to the nanometer range by means of a generally reduced-size image of structures on a mask, a so-called reticle, on an element to be structured that is provided with photosensitive material, such as a wafer. The minimum dimensions of the structures created depend on the resolution of the optical system used for the image. The resolution, in turn, depends directly on the wavelength of the radiation used for imaging, the so-called useful radiation, and the numerical aperture, i.e. the product of the refractive index of the surrounding medium and the aperture angle of the optical system used for imaging. To generate the useful radiation, light sources are used which produce radiation in an emission wavelength range of 100 nm to 300 nm, known as the DUV range. In recent times, light sources with an emission wavelength in the range of a few nanometers, for example between 1 nm and 120 nm, in particular in the range of 13.5 nm, have been increasingly used. The emission wavelength range described last is also known as the EUV range. In the optical system, optical elements such as lenses and mirrors are used to illuminate the structures and in particular to image them. det, whereby in the area of E UV lithography almost exclusively mirrors are used due to the high absorption of the emission wavelengths used there by most materials. To image the structures, so-called optical effective surfaces of the optical elements are exposed to useful radiation. During imaging, deviations in the position of the optical elements from an optimal target position have a massive effect on the quality of the image and thus on the quality of the manufactured components. In order to meet the high positioning requirements, the position of the majority of the mirrors is actively controlled. Such a control requires a high control bandwidth, which depends, among other things, on the first internal natural frequencies of the optical element or optical module, whereby the lowest internal natural frequency should be above 1500 Hz. Lower natural frequencies mean that the sensors required for the control start to oscillate in the low frequency range (< 1500 Hz), which can make the rigid body control for positioning the mirror unstable. In addition to the optical element, an optical module also includes at least the actuators and sensors required for positioning and their connection to the optical element. The high natural frequencies required as shown above require a certain amount of relatively expensive materials to achieve the required rigidity, particularly with regard to the base bodies, for example the base bodies of mirrors. In the past, in view of this problem, it was proposed to arrange relatively thin optical elements on stiffening bodies made of relatively stiff materials, whereby the stiff materials did not have to be the expensive materials of the base bodies of optical elements according to the state of the art. The challenge, however, remains to compensate for the considerable deviations in the respective thermal expansion coefficients of the elements involved in this case. The object of the present invention is to provide an optical module in which an optical element is arranged on a separate stiffening body and in which the problem of the different thermal expansion coefficients is effectively counteracted. This object is achieved by a device having the features of independent claim 1. The subclaims relate to advantageous developments and variants of the invention. An optical module according to the invention comprises an optical element and a stiffening body, wherein the optical element has an optical effective surface. The optical element is connected to the stiffening body via at least one connecting element. According to the invention, the connecting element comprises a decoupling region, by means of which a mechanical decoupling of the stiffening body and the optical element is created parallel to the optical effective surface. Decoupling in the sense of the invention means the reduction of the transmission of forces and/or moments and/or tensions between the optical element and the stiffening body. This ensures that a lateral deformation of the stiffening body due to temperature changes does not lead to the introduction of adverse forces and/o