Adjustment method, adjustment system and laser beam device
By locating three measurement planes in the laser beam device to detect the beam diameter, calculating the beam caustics, and adjusting the optical device, the problems of large measurement workload and time-consuming adjustment in the prior art are solved, and fast and accurate laser beam device adjustment and real-time monitoring are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TRUMPF LASER SYSTEMS SEMICONDUCTOR MANUFACTURING EUROPE AG
- Filing Date
- 2024-10-10
- Publication Date
- 2026-05-08
AI Technical Summary
In existing technologies, adjusting the beam caustics of laser beam equipment requires multiple measurements and disassemblies, resulting in a large workload and time consumption, making it difficult to quickly meet specifications.
By positioning three measurement planes along the laser beam propagation direction, the beam diameter of the laser beam is detected, and the beam caustic is determined by calculation. The optical device is then quickly adjusted to match the target caustic.
It significantly reduces the workload of detecting the beam diameter, improves the adjustment speed and accuracy, and enables rapid, reliable adjustment and real-time monitoring of laser beam equipment.
Smart Images
Figure CN122003584A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for adjusting the beam caustics of a laser beam in a laser beam apparatus having optical devices. The invention also relates to an adjustment system. Furthermore, the invention relates to a laser beam apparatus. Background Technology
[0002] Laser beam devices are used in many different ways. A particular application of laser beam devices is the generation of extreme ultraviolet (EUV) radiation. In this process, a suitable material, particularly a droplet of tin, is exposed to a laser beam, resulting in the generation of the desired EUV radiation. Laser beam devices used to generate EUV radiation are used, for example, in the production of semiconductors.
[0003] In the case of laser beam equipment, particularly laser beam equipment used to generate EUV, it is essential to ensure that the laser beam equipment, and especially the laser beam itself, meets predetermined specifications before it is used as intended. These specifications may include safety-related factors or factors that determine the quality and performance of the laser beam.
[0004] To ensure the expected state of a laser beam device or laser beam, the beam caustics of the laser beam are typically measured and evaluated. If the beam caustics are not within the predetermined specifications, the optics on the laser system are usually adjusted or replaced. This process typically requires multiple measurements of beam caustics and calibration of the optics before specifications are met and the laser can begin operating as intended.
[0005] Conventional methods explicitly involve detecting the laser beam at multiple predetermined points along the beam axis using multiple cameras. Here, the cameras are typically guided directly into the laser beam. In practice, camera images are usually detected at at least nine predetermined locations, and often up to fourteen. Then, statistical methods, particularly by means of a fitting function, are used to determine the beam caustics from the camera images.
[0006] The method known from the prior art has the following drawbacks: a large number of measurements must be performed at different locations on the laser beam. This constitutes a considerable measurement workload. Furthermore, repeated measurements are typically required to adjust the optical setup, which further increases the workload.
[0007] Furthermore, the measurement location of the laser beam is typically predetermined and cannot be changed without affecting the statistical evaluation. Therefore, particularly in areas where the laser system is difficult to access, measurements can only be performed by partially disassembling and then reassembling the system. This further increases the workload, thereby increasing the time and cost involved.
[0008] Purpose of the invention Therefore, the object of the present invention is to provide a method and apparatus for reliably and rapidly adjusting and using a laser beam device. Summary of the Invention
[0009] According to the invention, this objective is achieved by an adjustment method having the features of claim 1. This objective is also achieved by an adjustment system having the features of claim 10. This objective is also achieved by a laser beam device having the features of claim 12. The dependent claims describe preferred embodiments of the invention.
[0010] According to the present invention, an adjustment method is provided.
[0011] This adjustment method is configured to adjust the beam caustics of a laser beam from a laser beam device. Specifically, the laser beam device is configured and constructed to generate extreme ultraviolet (EUV) radiation by irradiating a suitable material, such as tin droplets. The laser beam device typically has optical devices for generating the laser beam. Preferably, the adjustment method is configured to adjust these optical devices. This allows for particularly effective adjustment of the laser beam device.
[0012] Laser beams can be constructed as a single beam or as sub-beams. Sub-beams can be split, particularly by means of a beam splitter. Such a sub-beam can be used as a measurement beam for measurement and evaluation tasks, while another sub-beam is used as intended, particularly for generating extreme ultraviolet radiation.
[0013] This adjustment method is particularly suitable for inspecting already configured optical devices. The configured optical devices are typically constructed to approximate a beam caustic for forming a laser beam. In other words, this adjustment method is particularly suitable for fine-tuning laser beam equipment.
[0014] The adjustment method includes the following steps: In step a) of the adjustment method, the following steps are set: the three beam diameters of the laser beam are determined at three measurement planes positioned along the laser beam propagation direction. In other words, the radial extension of the laser beam relative to the laser beam propagation direction is detected at three different measurement locations. Specifically, the positions of the measurement planes can be freely determined along the laser beam propagation direction. This allows the positions of the measurement planes to be determined, for example, based on the accessibility of a specific location. This makes the measurement even faster and easier, as it eliminates the need, for example, to disassemble the laser beam equipment.
[0015] Preferably, a maximum of three beam diameters are detected on a maximum of three measurement planes. Compared to known methods, this significantly reduces the metrological workload involved in detecting beam diameters. Furthermore, the detected beam diameters can be processed much faster, which can significantly accelerate the processing speed of the adjustment method.
[0016] The subsequent method step b) of the adjustment method: The beam caustics of the laser beam are determined by calculating at least one beam propagation parameter based on the three obtained beam diameters. Preferably, two or more beam propagation parameters, particularly all necessary beam propagation parameters, are calculated to determine the beam caustics. The accuracy of beam caustics determination can be improved as the number of calculated beam propagation parameters increases.
[0017] Beam propagation parameters include, but are not limited to, the focal position of the laser beam, the beam waist diameter of the laser beam, the divergence angle of the laser beam, the Rayleigh length of the laser beam, and / or the diffraction index.
[0018] In step c) of the adjustment method, the laser beam deviation is determined by comparing the determined beam caustic of the laser beam with the target beam caustic. By comparing the actual beam caustic with the target beam caustic, deviations in the adjustment of the laser beam equipment, particularly the optical device, can be determined. Furthermore, signs of wear caused by operation on the laser beam equipment can be detected.
[0019] A target beam caustic is understood as a predetermined beam propagation in the direction of laser beam propagation, which is optimized for the operation and configuration of the laser beam apparatus. Typically, the target beam caustic is defined before the laser beam apparatus is put into operation, or the laser beam apparatus is adjusted to form the target beam caustic.
[0020] In the subsequent step d) of the adjustment method, the laser beam device, particularly the optical apparatus, is adjusted based on the obtained laser beam deviation. In other words, the laser beam device, particularly the optical apparatus, is adjusted so that the beam caustic of the laser beam matches the target beam caustic. Preferably, the beam caustic corresponds to the target beam caustic after adjustment.
[0021] Preferably, the focal position is changed when adjusting the laser beam device, which allows the performance of the laser beam device to be maintained at a high level, especially when EUV radiation is generated.
[0022] Alternatively or additionally, when adjusting the laser beam equipment, it can be configured to: repair or replace worn and / or damaged parts of the laser beam equipment. Additionally, it can be configured to: perform planned maintenance earlier to ensure smooth operation.
[0023] In summary, the present invention relates to a novel method for determining the beam caustics of a laser beam. This adjustment method makes it particularly easy to detect and process the associated beam diameters to determine the beam caustics. This saves a significant amount of time during the setup and commissioning of laser beam equipment. Because the metrological workload for detecting only three beam diameters is reduced, the adjustment method can be performed using measurement techniques integrated into the laser beam equipment. The greatly reduced workload for detecting beam diameters also results in particularly rapid further processing and therefore rapid determination of the beam caustics, enabling a particularly rapid response to any detected deviations. This makes the adjustment method according to the invention suitable for real-time monitoring of laser beam equipment. For example, automatic or machine-controlled adjustment of the focal position can be used to adapt to changing operating conditions in real time, thereby further improving the efficiency of the laser beam equipment.
[0024] In a preferred embodiment of the adjustment method, in step a), the far-field beam diameter of the laser beam is determined at a first measurement plane located in the far field of the laser beam. The far field is understood as the region along the laser beam propagation direction at a certain distance from the focal point of the laser beam, in which the beam cross-sectional area of the laser beam increases linearly with distance from the focal point. Typically, in step b), the divergence angle of the laser beam is determined by the far-field beam diameter. This means that beam propagation parameters crucial for determining beam caustics can be determined using a single measurement.
[0025] To determine the divergence angle, an instrument lens with a predetermined focal length can be positioned in front of the first measurement plane along the beam path of the laser beam. For example, this allows the divergence angle to be determined according to the following formula: According to the exemplary formula, Let w be the divergence angle, w1 be the far-field beam diameter, and f This is the focal length of the instrument's lens.
[0026] Alternatively or additionally, the divergence angle can be determined, for example, by means of a trigonometric relationship between the far-field beam diameter at the first measurement plane and the second far-field beam diameter at the auxiliary plane. The auxiliary plane can be generated, for example, by moving the first measurement plane in the laser beam propagation direction. According to this embodiment, the adjustment method can be performed using only four measurement planes.
[0027] In a preferred further improvement to the adjustment method, in step a), a first near-field beam diameter is determined at a first measuring plane positioned in the near field of the laser beam, and a second near-field beam diameter is determined at a second measuring plane positioned in the near field. The near field is understood as the region along the laser beam propagation direction in which the beam cross-section does not change linearly based on the laser beam propagation direction. Typically, the near field extends along the laser beam propagation direction within a range of + / - Rayleigh lengths around the focal position. Typically, in step b), the focal position is determined. When determining the focal position, the positions of the first and second measuring planes, the first and second near-field beam diameters, and the divergence angle are considered. Knowing the focal position enables even more precise adjustment of the laser beam device, particularly the optical apparatus.
[0028] For example, the focal position can be determined using the following formula: According to the exemplary formula, z0 is the focal position, w1 is the first beam cross-section, w2 is the second beam cross-section, z1 is the first measurement plane position, and z2 is the second measurement plane position. It is the divergence angle.
[0029] Another preferred improvement to the adjustment method is that, in step b), the beam waist diameter is determined. The beam waist diameter can be understood as the diameter of the laser beam at the focal position. When calculating the beam waist diameter, the focal position, the position of the first measuring plane, and the diameter of the first near-field beam are typically considered. In this way, the adjustment of the laser beam device can be further improved.
[0030] For example, the waist diameter can be determined using the following formula: According to the exemplary formula, w0 is the beam waist diameter, w is the beam cross-section, z is the measurement plane position, and z0 is the focal point position. It is the divergence angle.
[0031] Another preferred improvement to the adjustment method is that, in step b), the Rayleigh length and / or diffraction index are determined. When calculating the Rayleigh length and / or diffraction index, the beam waist diameter and divergence angle are typically considered. By calculating the Rayleigh length and diffraction index, the beam caustics can be completely determined. This makes it possible to fully predict the beam caustics of the laser beam.
[0032] For example, the Rayleigh length can be determined using the following formula: According to the exemplary formula, z R w0 is the Rayleigh length, and w0 is the waist diameter. Let λ be the divergence angle, λ be the wavelength, and M be the diffraction index.
[0033] For example, the diffraction index can be determined using the following formula: According to the exemplary formula, M is the diffraction index, λ is the wavelength, w0 is the beam waist diameter, and... It is the divergence angle.
[0034] In a preferred further improvement to the adjustment method, in step a), the second near-field beam diameter is determined at an interval from the near-field measurement plane distance between the first and second measurement planes. In other words, the first near-field beam diameter is determined at a local distance from the second near-field beam diameter. This avoids inaccuracies in determining beam caustics that could occur if the distance between the first and second measurement planes is too small.
[0035] A further improvement to the adjustment method is preferred, wherein the first measuring plane is positioned in front of the focal point in the laser beam propagation direction. In other words, the first measuring plane is located upstream of the focal point in the laser beam propagation direction. Therefore, the first measuring plane is positioned in the region of the laser beam having a beam cross-section that gradually narrows in the laser beam propagation direction. This can improve the accuracy and robustness of the adjustment method.
[0036] Furthermore, another preferred improvement to the adjustment method is that the second measuring plane is positioned behind the focal point in the laser beam propagation direction. In other words, the second measuring plane is located downstream of the focal point in the laser beam propagation direction. Therefore, the second measuring plane is positioned in the region of the laser beam that has a beam cross-section that gradually widens in the laser beam propagation direction. This can further improve the accuracy and robustness of the adjustment method.
[0037] In a preferred embodiment of the adjustment method, at least one, and in particular all, of the beam diameters are determined by graphical evaluation of images (Abbildung) of the laser beam cross-section. Preferably, this image is generated by an image generating device, particularly a camera and / or a photodiode. Graphical evaluation methods have proven to be particularly reliable and rapid for determining beam caustics.
[0038] Preferably, the images of the laser beam cross-section are generated and evaluated at frequencies above 50 Hz, particularly preferably above 100 Hz. This ensures particularly effective real-time monitoring.
[0039] The objective of this invention is also achieved through an adjustment system.
[0040] The adjustment system is designed and configured for adjusting laser beam equipment, particularly the optical components of laser beam equipment. Specifically, the adjustment system is configured to perform the adjustment methods described above and below.
[0041] The adjustment system is configured to determine multiple beam diameters along the laser beam propagation direction of the laser beam from the laser beam device. In other words, the adjustment system has at least the following components.
[0042] The adjustment system has at least one image generating device. The image generating device is specifically configured as a camera and / or a photodiode. The image generating device is configured to detect the beam diameter of a laser beam. The image generating device may be positioned immediately adjacent to and / or within the beam path of the laser beam. The image generating device is configured to be positioned, at least temporarily, within the beam path of the laser beam.
[0043] The adjustment system also includes a calculation unit. The calculation unit is designed and configured to determine the beam caustic based on the detected beam diameter, and to determine the laser beam deviation by comparing the beam caustic with the target beam caustic.
[0044] The adjustment system also includes an output unit. The output unit is designed and configured to output the determined laser beam deviation, particularly graphically. In other words, the output unit is configured to output the results from the calculation unit. The output unit can be configured as a display for the adjustment system.
[0045] A preferred embodiment of the adjustment system has two, and particularly three, image generating devices. Preferably, at least one, and particularly all, of the image generating devices is configured to be fixedly positioned on and / or within the beam path of the laser beam from the laser beam device. This fixed arrangement of the image generating devices means that they can remain positioned in hard-to-access areas of the laser beam device. This eliminates the need for costly disassembly and reassembly of the laser beam device.
[0046] The objective of this invention is also achieved through a laser beam device.
[0047] The laser beam device has optical components for outputting a laser beam and adjustment systems described above and below. The optical components typically include multiple optical elements and / or groups of optical functions configured to generate a predetermined target beam caustic for the laser beam.
[0048] Laser beam devices are preferably designed and configured to target materials for targeted irradiation to produce extreme ultraviolet (EUV) radiation.
[0049] Further advantages of the invention will be apparent from the description and drawings. Similarly, the features mentioned above and those yet to be described can each be used individually or in any desired combination according to the invention. The illustrated and described embodiments should not be construed as an exhaustive enumeration, but rather as exemplary features used to describe the invention. Attached Figure Description
[0050] Figure 1 A schematic representation of a method for adjusting beam caustics in a laser beam device is shown.
[0051] Figure 2 A schematic representation of a laser beam device showing the laser beam propagating in the laser beam propagation direction is shown.
[0052] Figure 3 A schematic representation of a first embodiment of a laser beam device with an adjustment system is shown.
[0053] Figure 4 A schematic representation of a second embodiment of a laser beam device with an adjustment system is shown. Detailed Implementation
[0054] Figure 1 A schematic representation of adjustment method 10 is shown. Adjustment method 10 will now be described with reference to other figures in the accompanying drawings.
[0055] Adjustment method 10 is configured to adjust laser beam 14 (see Figure 2 , Figure 3 and Figure 4 ) beam caustics 12 (see Figure 2 , Figure 3 and Figure 4 Beam caustics 12 refer to the laser beam 14 in the direction of laser beam propagation 16 (see...). Figure 2 , Figure 3 and Figure 4 The propagation or diameter variation on the beam 14. Beam caustics 12 typically define characteristic properties of the laser beam 14, such as the focal position 18 (see [reference]). Figure 2 ) and / or waist diameter 20 (see Figure 2 ).
[0056] Adjusting the beam caustic 12 of laser beam 14 for laser beam device 22 (see Figure 2 , Figure 3 and Figure 4 The effectiveness of the laser beam is quite important. Especially when generating extreme ultraviolet radiation (EUV radiation), in which the laser beam 14 is guided to a target material (not shown) such as a tin droplet, the precise determination and adjustment of the beam caustic 12, and in particular the focal position 18, is crucial for a successful process.
[0057] Adjustment method 10 includes at least the following steps: In step 24 of the first method of adjustment method 10, the following setting is made: along the laser beam propagation direction 16 (see...) Figure 2 and Figure 3 The three beam diameters 26 of laser beam 14 are determined at the three measuring planes 28 of the positioning (see...). Figure 2 , Figure 3 and Figure 4 ).
[0058] like Figure 2 As shown, one of the measurement planes 28 can be positioned as the first measurement plane 30 in the near field of the laser beam 14 (see Figure 1). Figure 2 Thus, one of the beam diameters 26 can be determined as the first near-field beam diameter 32 (see...). Figure 2 ).
[0059] Preferably, another measurement plane 34 in the measurement plane 28 is positioned in the near field of the laser beam 14 (see...). Figure 2 Thus, the other of the beam diameters 26 can be identified as the second near-field beam diameter 36 (see...). Figure 2 ).
[0060] Alternative or additional land, such as Figure 2 One of the measurement planes 28 shown is preferably positioned as a third measurement plane 38 in the far field of the laser beam 14 (see [reference]). Figure 2 Therefore, the beam diameter of 26 can be determined as the far-field beam diameter of 40 (see...). Figure 2 ).
[0061] In step 42 of another method of adjustment method 10, the beam caustics 12 of the laser beam 14 are determined by analyzing and calculating the beam propagation parameters of the laser beam 14 based on the three obtained beam diameters 26.
[0062] Typical beam propagation parameters could be, for example, the focal position 18 of the laser beam 14, the beam waist diameter 20, and the divergence angle 44 (see...). Figure 2 Rayleigh length (not shown) and / or diffraction index (not shown). This enumeration should not be construed as exhaustive.
[0063] In a preferred embodiment of adjustment method 10, the far-field beam diameter 40 may be determined in method step 24. Knowing the far-field beam diameter 40, the divergence angle 44 can be calculated. This allows for more accurate calculation of further beam propagation parameters.
[0064] In a preferred embodiment of adjustment method 10, the method may further include determining the first near-field beam diameter 32 in step 24. The beam waist diameter 20 can be determined, for example, by knowing the near-field beam diameter 32 and knowing or assuming the focal position 18.
[0065] In method step 24, alternatively or additionally, the following can be set: determining the second near-field beam diameter 36. The focal position 18 can be determined, for example, by knowing the second near-field beam diameter 36 and knowing or assuming the divergence angle 44.
[0066] Alternatively, the Rayleigh length and / or diffraction index can be determined by knowing or assuming the waist diameter 20 and / or by knowing or assuming the divergence angle 44.
[0067] By knowing the beam propagation parameters, the propagation of the laser beam 14 or the beam caustics 12 can be accurately determined or predicted.
[0068] In step 46 of the subsequent method of adjustment method 10, the following is set: The laser beam deviation is calculated. The laser beam deviation may include one or more beam propagation parameters of the laser beam 14 and the target beam caustic 48 (see [reference]). Figure 2 The deviation of the target beam propagation parameters. In other words, the comparison between the beam caustics 12 of the executing laser beam 14 and the target beam caustics 48.
[0069] In another method step 50, the following is set: adjusting the laser beam device 22, particularly the optical device 52 (see...). Figure 2 and Figure 3 The adjustment is performed based on the obtained laser beam deviation. In other words, if the deviation of one or more beam propagation parameters from the predetermined target beam propagation parameters is known, the laser beam device 22, and in particular the optical device 52, can be accurately and specifically adjusted.
[0070] Figure 2 The laser beam device 22 is shown schematically.
[0071] The laser beam device 22 has a laser beam generator 54. The laser beam generator 54 is configured to generate a laser beam 14. The laser beam generator 54 is located upstream of the optical device 52 in the laser beam propagation direction 16.
[0072] Optical device 52 is configured to output laser beam 14. Preferably, the beam caustic 12 of the laser beam 14 is known through the approximate formation of optical device 52. In particular, with the approximate formation of the beam caustic 12 known, the near field and / or far field of the laser beam 14 can be determined particularly quickly. This makes it possible to execute adjustment method 10 (see [link to relevant documentation]) particularly efficiently and quickly. Figure 1 ).
[0073] In a particular application of the laser beam device 22, the optical device 52 is configured to irradiate a target material (not shown), particularly a tin droplet (not shown), to generate extreme ultraviolet radiation (EUV radiation).
[0074] As shown, the first measurement plane 30 and the second measurement plane 34 are spaced apart by a near-field measurement plane distance 56. In other words, the second near-field beam diameter 36 is determined to be spaced apart from the first near-field beam diameter 32 in the laser beam propagation direction 16. This avoids inaccuracies caused by an excessively small near-field measurement plane distance 56 when determining the beam caustic 12.
[0075] Preferably, the first measuring plane 30 is positioned in front of the focal point 18 in the laser beam propagation direction 16, as shown. In other words, the first measuring plane 30 is positioned in the tapering region of the laser beam 14. This allows for particularly precise determination of the beam caustics 12.
[0076] More preferably, the second measuring plane 34 can be positioned behind the focal position 18 in the laser beam propagation direction 16, as shown. This allows for even more precise determination of the beam caustics 12.
[0077] Figure 3 The laser beam device 22, on which the adjustment system 58 is arranged, is shown schematically.
[0078] The adjustment system 58 is configured to adjust the optical device 52 of the laser beam device 22. Preferably, the adjustment system 58 is configured to adjust the optical device 52 using a approximately known beam caustic 12. The adjustment system 58 is configured to define a plurality of (three in this case) beam diameters 26 along the laser beam propagation direction 16 of the laser beam 14.
[0079] Typically, the beam diameter 26 is determined using a graphic image 60 of the laser beam 14. The graphic image 60 is preferably processed by one or more image generating devices 62, 64, 66, such as cameras and / or image sensors. The image generating devices 62, 64, 66 are configured to directly or indirectly detect the beam cross-section 67 of the laser beam 14. For clarity, only one beam cross-section 67 is provided with reference numerals. In other words, the image generating devices 62, 64, 66 can be directly positioned at the measurement plane 28 in the beam path of the laser beam 14. As shown, the image generating device 66 is directly positioned at the measurement plane 28. Alternatively, the image generating devices 62, 64, 66 can be configured to detect the beam cross-section 67 of the laser beam 14 reflected at the measurement plane 28. As shown, the image generating devices 62, 64 are configured to indirectly detect the beam cross-section 67 by reflecting the laser beam 14 via a partially transparent mirror or beam splitter 68. Indirect detection allows the laser beam device 22 to operate in parallel.
[0080] Image generating devices 62, 64, and 66 can be fixedly arranged or positioned on laser beam device 22. As shown, image generating devices 62 and 64 are fixedly arranged or positioned in the beam path of laser beam device 22 or laser beam 14. As shown, image generating device 66 is configured to be temporarily arranged in the beam path of laser beam 14.
[0081] With a fixed arrangement, the costly installation of image generation devices 62, 64, and 66 for detecting the beam diameter 26 can be eliminated. This means that adjustment method 10 can be performed particularly quickly (see...). Figure 1 During the operation of the laser beam device 22, the fixing devices 62 and 64 can remain arranged on the laser beam device 22.
[0082] Preferably, fixed image generating devices 62, 64 are used in areas where the laser beam device 22 is difficult to access, thereby generating a considerable time advantage by eliminating the setup and dismantling time for detecting the beam diameter 26.
[0083] Particularly preferably, all image generating devices 62, 64, and 66 are fixedly positioned at the laser beam device 22. This allows adjustment method 10 to be performed during operation of the laser beam device 22. This enables high-frequency monitoring, particularly real-time monitoring of beam caustics 12. Continuous monitoring allows for the monitoring of wear on components of the laser beam device 22, particularly the optical components 52, and allows for adjustment of maintenance intervals. This also improves the effectiveness of the laser beam device 22.
[0084] As shown, the instrument lens 69 can be positioned upstream of one of the image generating devices 62, 64, and 66—here, image generating device 66—in the laser beam propagation direction 16. In other words, as shown, the image generating device 66 and the instrument lens 69 are arranged in the far field of the laser beam 14. Preferably, the instrument lens 69 is positioned together with the image generating device 66 in the laser beam 14.
[0085] The instrument lens 69 is typically constructed as a converging lens with a predetermined or known focal length 70. The instrument lens 69 is typically located upstream of the image generating device 66, at a distance of focal length 70. This makes it particularly easy to determine the divergence angle 44 based on the beam diameter 26 and the focal length 70 (see [link to image processing device]). Figure 2 ).
[0086] The adjustment system 58 also includes a calculation unit 71. The calculation unit 71 is designed and configured to determine the beam caustic 12 based on the detected beam diameter 26. Furthermore, the calculation unit 71 is designed and configured to compare the beam caustic 12 with the target beam caustic 48 (see [reference]). Figure 2The deviation between the beam propagation parameters and the target beam propagation parameters is determined by comparison.
[0087] Preferably, the calculation unit 71 is further configured to determine the beam diameter 26 based on the graphic image 60. The calculation unit 71 may, for example, use a graphic evaluation algorithm for this purpose.
[0088] The adjustment system 58 also includes an output unit 72. The output unit 72 is configured to output the determined laser beam deviation. The output can be provided, for example, by means of a display (not shown). Preferably, the output unit 72 is configured to output adjustment suggestions related to the adjustment of the laser beam device 22 or the optical device 52.
[0089] Particularly preferably, the adjustment system 58 is configured to exchange data with the control unit (not shown) of the laser beam device 22. Therefore, the adjustment of the laser beam device 22 can be performed automatically by the adjustment system 58. This increases the level of automation of the laser beam device 22.
[0090] Alternatively or additionally, the adjustment method 10 described above and below may be performed on the measuring beam (not shown), and / or the adjustment system 58 described above and below may be arranged on the measuring beam. The measuring beam is typically generated by reflecting a sub-beam from the laser beam 14. Generally, the measuring beam should be understood as a copy of the laser beam 14. In this way, interference with the operation of the laser beam 14 or the laser beam device 22 can be avoided.
[0091] Figure 4 Another embodiment of the laser beam device 22 on which the adjustment system 58 is arranged is shown schematically.
[0092] The adjustment system 58 and Figure 3 The fundamental difference in the adjustment system 58 is the modification of the image generating device 66 in the far field of the laser beam 14.
[0093] As shown, image generating devices 62, 64, and 66—here image generating device 66—can be movably arranged within the laser beam 14. In other words, at least slight movement of image generating device 66 can be provided. This makes it particularly easy, for example, to operate without the instrument lens 69 (see...). Figure 3 The divergence angle is determined under the condition of 44 (see Figure 2 ).
[0094] As shown, the image generating device 66 can move bidirectionally from the first measurement position 74 to the second measurement position 76 along the laser beam propagation direction 16. The second measurement position 76 is spaced apart from the first measurement position 74 by a predetermined travel path 78. The first measurement position 74 and the second measurement position 76 are positioned in the far field of the laser beam 14.
[0095] The diameter difference 80 can be obtained by comparing the beam diameter 26 at measurement position 74 with that at measurement position 76. The divergence angle 44 can then be determined in a particularly simple manner based on the diameter difference 80 and the travel path 78.
[0096] Alternatively, an auxiliary plane (not shown in more detail) can be arranged at a distance from the first measurement position 74 and the travel path 78, or in the second measurement position 76. This means that it is not necessary to move the image generating device 66 to obtain the diameter difference 80.
[0097] List of reference numerals 10. Adjustment methods; 12. Beam caustics; 14. Laser beam; 16. Direction of laser beam propagation; 18. Focal point; 20 mm waist diameter; 22. Laser beam equipment; 24. Methods and steps; 26 Beam diameter; 28. Measuring plane; 30 First measuring plane; 32. First near-field beam diameter; 34. Second measuring plane; 36. Second near-field beam diameter; 38. Third measuring plane; 40mm far-field beam diameter; 42. Methods and steps; 44° divergence angle; 46. Methods and steps; 48. Target beam caustics; 50 Methods and Steps; 52. Optical devices; 54. Laser beam generator; 56. Near-field measurement of planar distance; 58. Adjust the system; 60. Graphic images; 62. Image generating apparatus; 64. Image generating apparatus; 66. Image generating apparatus; 67. Beam cross-section; 68 beam splitters; 69. Instrument lens; 70 focal length; 71. Calculation unit; 72 Output Units; 74 First measurement position; 76 Second measurement position; 78. Path of travel; 80 diameter difference.
Claims
1. A method (10) for adjusting the beam caustic (12), particularly the focal position (18), of a laser beam (14) of a laser beam device (22), the laser beam device having an optical device (52) specifically for generating extreme ultraviolet radiation (EUV), the adjustment method comprising the following steps: a) Determine the three beam diameters (26, 32, 36, 40) of the laser beam (14) described in (24) at three measurement planes (28, 30, 34, 38) located along the laser beam propagation direction (16). b) The beam caustics (12) of the laser beam (14) are determined by analyzing the beam propagation parameters of the laser beam (14) based on the three obtained beam diameters (26, 32, 36, 40). c) The laser beam deviation (46) is determined by comparing the beam caustic (12) of the laser beam (14) with the target beam caustic (48); d) Adjust (50) the laser beam device (22), and in particular the optical device (52), according to the obtained laser beam deviation.
2. The adjustment method (10) according to claim 1, wherein, In step a), the far-field beam diameter (40) of the laser beam (14) is determined at a third measuring plane (38) located in the far field of the laser beam (14); wherein, in step b), the divergence angle (44) of the laser beam (14) is determined by the far-field beam diameter (40).
3. The adjustment method (10) according to claim 2, wherein, In step a), a first near-field beam diameter (32) is determined at a first measurement plane (30) located in the near field of the laser beam (14), and a second near-field beam diameter (36) is determined at a second measurement plane (34) located in the near field; wherein, in step b), the focal position (18) is determined.
4. The adjustment method (10) according to claim 3, wherein, In step b), the waist diameter (20) is determined.
5. The adjustment method (10) according to claim 4, wherein, In step b), the Rayleigh length and / or diffraction index are determined.
6. The adjustment method (10) according to any one of claims 3 to 5, wherein, In step a), the second near-field beam diameter (36) is determined separately from the first near-field beam diameter (32) by the near-field measurement plane distance (56) between the first measurement plane (30) and the second measurement plane (34).
7. The adjustment method (10) according to any one of claims 3 to 6, wherein, The first measuring plane (30) is positioned in front of the focal point (18) in the direction of laser beam propagation (16).
8. The adjustment method (10) according to any one of claims 3 to 7, wherein, The second measuring plane (34) is positioned behind the focal point (18) in the direction of laser beam propagation (16).
9. The adjustment method (10) according to any one of the preceding claims, wherein, At least one of the beam diameters (26, 32, 36, 40), and in particular all of the beam diameters, are determined by graphical evaluation of a graphical image (60) of the laser beam cross-section.
10. An adjustment system (58) for adjusting an optical device (52) of a laser beam apparatus (22) by determining a plurality of beam diameters (26, 32, 36, 40) along the laser beam propagation direction (16) of a laser beam (14), the adjustment system being particularly configured to perform an adjustment method (10) according to any one of the preceding claims, the adjustment system having: - At least one image generating device (62, 64, 66), particularly a camera and / or a photodiode, for detecting the beam diameter (26, 32, 36, 40) of the laser beam (14), wherein, The image generating apparatus (62, 64, 66) is configured to be positioned at least temporarily in the beam path of the laser beam (14); - A calculation unit (71) is used to determine the beam caustic (12) based on the detected beam diameter (26, 32, 36, 40) and to determine the laser beam deviation by comparing the beam caustic (12) with the target beam caustic (48); - Output unit (72) for outputting the determined laser beam deviation.
11. The adjustment system (58) according to claim 10, wherein the adjustment system has two image generating devices (62, 64, 66), particularly three image generating devices, wherein, At least one of the image generating devices (62, 64, 66), and in particular all of the image generating devices, are configured to be positioned in a fixed manner on the beam path of the laser beam (14).
12. A laser beam device (22) having an optical device (52) specifically for generating EUV radiation, the laser beam device having an adjustment system (58) according to any one of claims 10 or 11.