Optical device for changing the polarization of a polarized light beam, optical system, EUV drive laser and EUV light generation facility

Abstract

The present invention relates to an optical device (10) for changing the polarization (12) of a polarized beam (14). The optical device (10) has: a beam input end (16) for the polarized beam (14) which is capable of entering the beam input end (16) of the optical device (10) along a first propagation axis (18); and a beam output end (20) for the polarized beam (14) which is capable of exiting the beam output end (20) of the optical device (10) along a second propagation axis (22). Furthermore, the optical device (10) has a plurality of deflection elements (24), each of which is configured to deflect the polarized beam (14) within the optical device (10), wherein at least one of the deflection elements (24) is configured to change at least one polarization component of the polarized beam (14). The optical device (10) also has a beam path (26) configured within the optical device (10) by means of deflecting elements (24) to extend from the beam input end (16) of the optical device (10) to the beam output end (20) of the optical device (10). According to the invention, the deflecting elements (24) are arranged such that they can rotate together about a rotation axis (28). Furthermore, according to the invention, the first propagation axis (18), the second propagation axis (22), and the rotation axis (28) are parallel to each other.

Description

Technical Field

[0001] This invention relates to an optical device for changing the polarization of a polarized light beam, the optical device having: a) A beam input for a polarized beam that can enter the optical device along a first propagation axis. b) A beam output terminal for a polarized beam that can exit the beam output terminal of the optical device along the second propagation axis. c) A plurality of deflecting elements, each configured to deflect a polarized beam within an optical device, wherein at least one of these deflecting elements is configured to alter at least one polarization component of the polarized beam. d) Beam path, which is constructed within the optical device by means of deflection elements to extend from the beam input end of the optical device to the beam output end of the optical device.

[0002] The present invention also relates to an optical system having the above-described optical device, an EUV-driven laser having such an optical system or such optical device, and an EUV light generation facility having such an EUV-driven laser. Background Technology

[0003] In the production of integrated circuits, i.e., microchips, a semiconductor substrate, typically a single crystal (hereinafter referred to as a wafer), is coated with a layer in a relatively early manufacturing step. This coating is then structured in subsequent manufacturing steps. Such structuring acts as a mask in subsequent manufacturing steps, allowing for the introduction of foreign materials into the structuring, for example, etching of functional layers beneath the coating, doping with foreign atoms (e.g., by ion implantation), or (e.g., by LIGA and stripping).

[0004] The purpose of these methods is primarily to fabricate transistors on wafers and to create conductive regions that connect the transistors to each other. Various methods can be used to incorporate structuring into the coating.

[0005] For example, in photolithography, the coating is constructed as a photosensitive coating, specifically as a photoresist. Here, the photoresist is exposed in a specific pattern to light of a specific wavelength to which it is sensitive, thereby affecting the chemical properties of the exposed areas of the photoresist, such as the solubility of the exposed areas in the developer solution. There are photoresists where the exposed areas polymerize—meaning the solubility of the exposed areas increases compared to the unexposed areas (so-called negative photoresists). Additionally, there are photoresists where the exposed areas become more soluble than the unexposed areas (so-called positive photoresists). In either case, to form a structure in the photoresist and thus a mask for the functional layer beneath the photoresist, the more soluble areas in the photoresist are removed using a developer solution.

[0006] In order to introduce a specific pattern into the photoresist, a mask element (hereinafter referred to as a photomask) is usually placed between the light source and the wafer. The mask element is configured to form a structured negative or positive image on the photoresist to be formed, depending on the photoresist used (negative or positive photoresist).

[0007] In conventional photolithography, the photomask is either placed directly on the photoresist or positioned directly above it, separated from it, such that the photomask and the resulting structure on the photoresist are in a 1:1 ratio. Since photomasks can only be shrunk to a limited extent, the structural size is theoretically limited to a few hundred nanometers. Because smaller structures enable microchips to have significantly higher performance per unit area or volume (as this allows for more transistors to be implemented in a small area that remains constant), there is a general trend towards shrinking structures to their absolute physical limits.

[0008] For this reason, projection lithography facilities are now commonly used, in which focusing optics are typically arranged between the photomask and the photoresist, allowing the photomask to be imaged onto the photoresist at a significantly reduced size. On the one hand, this makes the photomask cheaper to manufacture because its structure does not need to be so small. On the other hand, it also allows for the imaging of significantly smaller structures on the wafer compared to conventional photolithography. Then, for example, the photomask and the resulting structure on the photoresist can exist in a ratio of 5:1 or higher. The photomask itself can be constructed as an absorptive photomask or a reflective photomask.

[0009] Since a reduced image on the photoresist using a photomask cannot cover the entire wafer, the wafer is often exposed at a so-called "step-repeated" position in known methods. The wafer is then moved a certain distance and exposed again at a second exposure position. This process is repeated in these known methods until the wafer is covered with as many instances of the same structure as possible.

[0010] After the areas where the photoresist is more soluble than the developer solution have been removed and the underlying functional layer has been etched, the photoresist is often removed from the functional layer through a process called "stripping".

[0011] For multi-layered microchips, the projection exposure method described above can be performed up to one hundred times on the same microchip.

[0012] EUV light generation facilities and EUV generation Besides shrinking photomasks and using focusing optics, another possibility for reducing the size of structured components on wafers is to use light with shorter wavelengths for exposure.

[0013] In a method known according to the prior art, extreme ultraviolet light (EUV light) with a wavelength range of about 8 nm to about 15 nm is generated for this purpose, wherein the main part of the EUV light is at 13.5 nm, and the EUV light is guided onto the photoresist by means of EUV projection optics and EUV focusing optics of a projection exposure facility.

[0014] EUV light generation facilities for this purpose mainly include: an EUV-driven laser, by means of which at least one excitation beam can be generated; a target generator; and an EUV light generation chamber. Typically, a pulsed high-power laser is used as the EUV-driven laser, and a droplet generator is used as the target generator, by means of which droplets of the target material are injected into the EUV light generation chamber. To avoid damage to the system due to particle contamination, in embodiments known in the art, a high vacuum can be maintained in the EUV light generation chamber under a process gas atmosphere, wherein hydrogen (H2) or helium (He) is particularly suitable as the process gas.

[0015] In methods known according to existing technology, tin (Sb) is frequently used as the target material. Besides tin (Sb), targets including xenon (Xe), gold (Au), and / or lithium (Li) are also possible. To increase the amount of emitted EUV light, the droplets generated by the droplet generator can be excited, for example, first with a first excitation beam, i.e., a pre-pulse, and then with a second excitation beam, i.e., a main pulse. The two excitation beams can be two independent beams, or they can be generated by splitting a single beam. In principle, EUV light can be generated by a single excitation beam; therefore, a second excitation beam is not absolutely necessary. However, by using a second excitation beam, the so-called conversion efficiency, i.e., the ratio of input laser power to generated EUV power, is significantly improved.

[0016] This is because in these known methods, excitation with a pre-pulse results in the pretreatment of the target droplet. Currently, this pretreatment involves the target droplet forming an approximately disk-shaped form due to the energy input through the pre-pulse, thereby relatively increasing the surface area of ​​the target droplet that can be excited by the second excitation beam. The main pulse then encounters the pretreated target droplet, thereby exciting the pretreated target droplet. In known methods, this excitation involves generating an ionized gas of the target—if the target is a tin material, this generates tin plasma. This tin plasma then emits EUV light required to form the structure in the photoresist.

[0017] In another known method, for further pretreatment, a third excitation beam in the form of a so-called rarefaction pulse can be used, which impinges on the target droplet between the pre-pulse and the main pulse. In this known method, the rarefaction pulse causes the target droplet—which forms a disk shape through the pre-pulse—to become rarefied or increase in volume toward a target cloud, where the term "cloud" is not equivalent to a gaseous aggregate or vapor state of the target. Using such a rarefaction pulse further improves the conversion efficiency.

[0018] Here, a rarefied pulse can be generated by splitting the first excitation beam into a prepulse and a rarefied pulse. However, a separate beam source can also be used to generate the rarefied pulse, or even a single excitation beam can be split into a prepulse, a rarefied pulse, and a main pulse. Furthermore, it is also possible for the rarefied pulse to be constructed as part of the main pulse, which precedes the main pulse in time and can be distinguished temporally with respect to its time-varying intensity distribution. In this case, it is more often referred to as a so-called "pedestal".

[0019] EUV-driven lasers are also conceivable, in which more than three excitation beams are used to excite the target and generate EUV light.

[0020] In each of the above cases, the main pulse impacts the target droplet with a power ranging from 20 kW to 50 kW.

[0021] EUV driven laser EUV-driven lasers known in the prior art, sometimes also called EUV-Drivelasers, can have a beam source, a pump source, an amplifier assembly with multiple optical amplifiers, and a focusing unit.

[0022] A beam source can generate an excitation beam, which is then amplified into an amplified excitation beam by multiple optical amplifiers at specific points along the optical path.

[0023] If more than one beam is used to generate EUV light in methods known in the prior art, a separate beam source can be provided for each excitation beam (prepulse, sparse pulse, and main pulse), i.e., a prepulse beam source, a sparse pulse beam source, and a main pulse beam source.

[0024] In known methods, the term "pulse" refers to a beam of light that has a relatively short duration and therefore a start and end time, is part of a large number of time-sequential beams of the same type, and is generated by a pulsed laser. The duration of a pulse can be in the range of microseconds, nanoseconds, picoseconds, or femtoseconds. Lasers operating in continuous wave (CW) mode should be distinguished from this.

[0025] If one, two, three or more separate beam sources are used to generate an excitation beam or pre-pulse, sparse pulse and / or master pulse, these beam sources can generate excitation beams with the same or different wavelengths and the same or different intensities, modes, beam caustics and / or polarizations, or the excitation beams can be incident on the target droplet with the same or different wavelengths and the same or different intensities, modes, beam caustics and / or polarizations.

[0026] For example, in conventional EUV excitation light generation facilities, solid-state lasers are known to be used as prepulse beam sources for prepulses. Such known solid-state lasers generate prepulses with wavelengths in the range of about 1 µm. Solid-state lasers can also be used as sparse pulse beam sources, which, for example for metrological purposes, preferably have wavelengths different from the prepulses, also in the range of about 1 µm.

[0027] CO2 lasers are typically used as the main pulse beam source for the main pulse, generating a main pulse with wavelengths in the range of approximately 10.6 µm.

[0028] Problems with existing technology In existing optical devices for changing the polarization of a polarized beam, the polarized beam is guided to a target region for polarization by means of a deflection element that forms a beam path for the polarized beam.

[0029] At least one of these deflection elements is configured to alter at least one polarization component of the polarized beam, for example, to provide a desired polarization of the polarized beam in a target region. In particular, due to manufacturing tolerances of the deflection elements or thermal and / or mechanical effects on the deflection elements, the polarization of the beam in the target region may deviate from the desired polarization.

[0030] For example, if the actual polarization of a polarized beam differs from the desired polarization due to thermal and / or mechanical stress within the optical device, in the prior art, at least one deflector element, which is typically configured to change at least one polarization component of the polarized beam, is usually manually replaced at a relatively high cost with a deflector element that induces a different polarization of the polarized beam in the target region. For this purpose, deflector elements with different polarization-changing characteristics can be provided.

[0031] Typically, several of these deflection elements must be replaced manually, that is, by a maintenance worker using specialized tools. By replacing these deflection elements, the desired polarization setting can be approximately achieved in the target area.

[0032] In addition to the desired polarization in the target area, another requirement for polarized beams or optical systems and / or optical equipment is that the polarized beam is incident on a specific target location. If the deflection element is manually replaced as described above, the position of the deflection element usually needs to be manually adjusted to correct the actual target position of the polarized beam to the target location in order to approximate the set beam path and thus achieve the desired target location with the highest possible accuracy.

[0033] Despite the measures described herein, undesirable and significant deviations often remain in the target area relative to the desired polarization and / or the desired target position. This is particularly true in applications where the polarized beam must possess exceptionally high power, where even the smallest deviations exceeding the defined tolerances can have serious consequences for the desired results. Furthermore, the manual replacement of deflection elements results in particularly high workload and, consequently, maintenance costs. Moreover, polarization changes caused by thermal and / or mechanical effects during operation cannot be easily compensated for without posing considerable health risks to maintenance personnel.

[0034] This is particularly relevant for EUV-driven lasers or EUV light-generating facilities that may have such optical equipment, meaning that the method used to generate EUV light must be interrupted and the beam path must be opened for this purpose. There is also a high risk of malfunction and contamination in this particular technical field. Summary of the Invention

[0035] Therefore, the object of the present invention is to provide the optical device mentioned at the beginning, which overcomes the disadvantages of the prior art mentioned above.

[0036] According to the present invention, this objective is achieved by means of the optical device mentioned at the beginning, wherein, f) The deflecting elements are arranged such that they can rotate together about the axis of rotation, and g) The first propagation axis, the second propagation axis, and the rotation axis are parallel to each other.

[0037] Using this optical device, in which the first propagation axis, the second propagation axis, and the rotation axis are parallel to each other, and the deflection elements are arranged such that they can rotate together about the rotation axis, a particularly precise polarization setting can be achieved in the target area.

[0038] Furthermore, the optical device according to the invention allows the deflection element to be adjusted relative to the rotation axis during operation, i.e., by rotating together about the rotation axis, without opening the beam path. In other words, depending on the position of the deflection element relative to the rotation axis, the polarized beam at the beam output end of the optical device can have a different polarization than the polarized beam at the beam input end of the optical device.

[0039] Because the first propagation axis, the second propagation axis, and the rotation axis are parallel to each other, angular deviations between the polarized beam entering and leaving the optical device are largely avoided when the deflecting element is in different positions relative to the rotation axis. This allows for particularly precise setting of the target position in the target region for different positions of the deflecting element relative to the rotation axis.

[0040] The axis of rotation is preferably a common axis of rotation for the deflecting elements. Preferably, the deflecting elements are thus able to rotate together about a single common axis of rotation.

[0041] In general, a polarized beam, that is, the sum of all polarization components of a polarized beam, can be linearly polarized, circularly polarized, or elliptically polarized.

[0042] The polarization components of a polarized beam can be understood as an S-polarization component and / or a P-polarization component. Therefore, a polarization component of a polarized beam can be either an S-polarization component or a P-polarization component. The S-polarization and P-polarization components of a polarized beam are typically defined relative to the polarization plane. The polarization plane is defined by the incident beam component and the outgoing beam component of the polarized beam. In this case, the incident beam component falls onto the deflecting element, and the outgoing beam component leaves the deflecting element, i.e., is deflected by the deflecting element. The P-polarization component is polarized within the polarization plane, i.e., it oscillates within and parallel to the polarization plane. The S-polarization component is polarized perpendicular to the polarization plane, i.e., it oscillates perpendicular to the polarization plane. Therefore, the P-polarization and S-polarization components are orthogonal to each other.

[0043] If the deflection elements rotate together about the rotation axis, at least one polarization component of the polarized beam, that is, the outgoing beam component compared specifically to the incident beam component, can be altered as a result of the rotation and due to the at least one deflection element configured to change the polarization.

[0044] The optical device can be designed in a relatively simple manner with a relatively small number of deflection elements. The optical device can, for example, have at least three, four, five, six or more deflection elements.

[0045] At least one deflecting element configured to alter at least one polarization component of a polarized beam can be advantageously constructed as a phase-shifting mirror. Phase-shifting mirrors are particularly suitable for beams with relatively high power, such as those provided by EUV-driven lasers. Therefore, phase-shifting mirrors are particularly suitable for EUV-driven lasers because birefringent materials are not available for the power and wavelength range produced by EUV-driven lasers.

[0046] In this context, a phase-shifting mirror is understood as a mirror that reflects a polarized beam by a phase shift between its P-polarization and S-polarization components relative to the polarization plane. Phase shift involves the difference between the polarization components of the outgoing beam and the incident beam. For example, a phase-shifting mirror can induce a 90° phase shift in a polarized beam, although any other amount of phase shift is conceivable and possible. In this context, a 90° phase shift is understood as a phase shift of λ / 4. This means that a phase-shifting mirror that induces a 90° phase shift can reflect a linearly polarized beam incident on it with equal P-polarization and S-polarization components as a circularly polarized beam.

[0047] Advantageously, the first propagation axis, the second propagation axis, and the rotation axis coincide in a common reference axis. In this case, the position and / or orientation of the polarized beam exiting the optical device relative to the rotation axis does not change. In other words, regardless of the position of the deflecting element relative to the rotation axis, the position and / or orientation of the beam exiting the optical device remains substantially unchanged.

[0048] Preferably, the beam path is formed within the beam plane. In this case, the beam plane also passes through deflecting elements, by means of which a beam path is formed within the optical device from the beam input end to the beam output end. Because the beam path is formed within the beam plane, the optical device can be designed to be particularly compact and space-saving in the direction perpendicular to the beam plane.

[0049] Furthermore, if the deflecting elements are arranged on a common rotating body configured to rotate about a rotation axis, advantages arise. Arranging the deflecting elements on a common rotating body allows the deflecting elements to rotate relatively easily about the rotation axis, for example, by a positioning device operated mechanically and / or electrically.

[0050] Advantageously, the rotating body is constructed as a single piece. In other words, the rotating body can be constructed as a monolithic body. Such a rotating body is particularly easy to manufacture, especially by machining processes, casting processes such as injection molding, or 3D printing. Therefore, the tolerances of the position and / or orientation of the deflecting elements relative to each other—which can practically only be controlled to a certain minimum resolution—can be kept relatively low, and relatively high position and / or orientation accuracy of the deflecting elements can be achieved.

[0051] Preferably, the rotating body has a cooling device configured to dissipate heat from the deflecting element. By deflecting the beam at the deflecting element, a relatively high heat input may occur from the polarized beam into the deflecting element. This is especially true for polarized beams from EUV-driven lasers. The cooling device dissipates heat from the deflecting element, thereby reducing the risk of thermal deformation and damage to the deflecting mirror. The cooling device can be specifically configured as water-cooled. Water cooling dissipates the relatively high heat input from the deflecting element. This heat dissipation can preferably be achieved directly via water cooling. In this direct cooling, heat is dissipated directly from the deflecting mirror into the water-cooled cooling water. In other words, the deflecting element can be in direct contact with or surrounded by the cooling water. In principle, the cooling device can also be configured as air-cooled.

[0052] It is advantageous if at least one deflecting element is connected to the rotating body via a connecting device, allowing the at least one deflecting element to expand axially and radially. Heat input to the deflecting element causes thermal deformation and / or expansion, which may further increase or even decrease if the at least one deflecting element cannot expand axially and radially. Suitable connecting devices that allow at least one deflecting element to expand axially and radially may, for example, include spring elements. Such spring elements may include, for example, helical springs, gas springs, and disc springs. In the present sense, a spring element is understood to include at least one force-fitting connecting element that can force-fit the deflecting element to the rotating body and allow for both axial and radial expansion of the deflecting element.

[0053] Preferably, at least one deflecting element can be adjusted regarding its orientation relative to a predetermined beam path using a correction device. With such a correction device, the orientation of at least one deflecting element can be adjusted, particularly by changing its position and / or attitude, so that the actual beam path can be adapted to the predetermined beam path. This avoids the need to remove at least one deflecting element and install a new deflecting element corresponding to the predetermined beam path when the attitude and / or position changes. In this context, it is also advantageous if such adjustment of at least one deflecting element can be performed without tools, for example by means of an actuator controlled by a control device, thus eliminating the need for maintenance personnel.

[0054] Advantageously, at least one deflection element is equipped with a temperature monitoring device. The temperature monitoring device can detect the thermal state of the deflection element and identify critical over-temperature conditions at the deflection element. For example, if a critical over-temperature condition is reached, the power of the polarized beam can be reduced, or the beam source can be placed in standby mode or completely shut down to reduce the risk of damage to the deflection element. Furthermore, if at least one deflection element experiences a critical over-temperature condition, it can be identified and replaced.

[0055] It is advantageous to equip an optical device with a polarization measuring device. Using such a device, polarization can be detected, particularly in the measurement region within the optical device or in the target region of the polarized beam, and compared with a set polarization in the measurement or target region. The deviation from the set polarization can be corrected by rotation, i.e., by changing the position of the deflection element relative to the axis of rotation.

[0056] It will be clear to those skilled in the art that all statements made above concerning "at least one" element of a particular type may also refer to some or even all elements of the same type. Therefore, these further developments are naturally included in this invention.

[0057] According to another aspect of the invention, the aforementioned problem is solved by an optical system comprising a first optical device and a second optical device, the first and second optical devices including some or all of the features mentioned above for optical devices, wherein the optical devices are arranged to rotate independently of each other, and the axes of rotation of the optical devices are parallel to each other. Using such an optical system, a larger polarization range can be set by rotation about the axis of rotation compared to a single optical device. In addition to a larger adjustment range, polarization can also be set by relatively short rotations of the first and / or second optical devices about the axis of rotation, i.e., rotations over a particularly small adjustment distance from a specific reference point.

[0058] Advantageously, in the optical system, a sealing and / or shielding device is arranged between the first and second optical devices, which is configured to substantially prevent the escape of process gas and / or scattered light between the optical devices. If a gas laser, particularly a CO2 laser, is used as the beam source for the polarized beam, the escape of the active laser gas, which acts as the process gas, between the first and second optical devices can be significantly reduced by means of the sealing and / or shielding device. Furthermore, the risk of contamination of the active laser gas due to the ingress of other substances can be reduced. Besides being an active laser gas, the process gas can also be a cooling gas or an inert gas, for example, used to create an atmosphere with particularly low reactivity. In addition, atmospheric conditions, overpressure conditions, or underpressure conditions may exist within the optical devices or optical system.

[0059] According to another aspect of the invention, the problem mentioned at the beginning is also solved by an EUV-driven laser that includes an optical device or optical system having some or all of the features mentioned above for the optical device or optical system.

[0060] According to another aspect of the invention, the problem mentioned at the beginning is also solved by an EUV light generation facility comprising an EUV-driven laser, a target generator, and an EUV light generation chamber, the EUV light generation facility including some or all of the features mentioned above for the EUV-driven laser. Attached Figure Description

[0061] The exemplary embodiments of the present invention will now be explained in more detail with the aid of the accompanying drawings. In the drawings: Figure 1 A longitudinal cross-sectional view along the XY plane is shown for an exemplary embodiment of the optical device according to the present invention; Figure 2 As shown Figure 1The optical device according to the present invention shown in the figure Figure 1 A magnified view of region II marked in the middle, where, Figure 2 The connecting device is shown in particular; Figure 3 An exemplary embodiment of the optical system according to the present invention is shown in a perspective view; Figure 4 An exemplary embodiment of the EUV light generating facility according to the present invention is illustrated in schematic diagram.

[0062] This invention is not limited to the exemplary embodiments shown. The exemplary embodiments illustrated in the figures are merely specific examples of the invention. Those skilled in the art will recognize exemplary embodiments of the invention not explicitly shown. Detailed Implementation

[0063] Figure 1 A longitudinal cross-sectional view along the XY plane is shown of an exemplary embodiment of the optical device 10 according to the invention. The optical device 10 is configured to alter the polarization 12 of a polarized beam 14. The polarized beam 14 has particularly high power in the present case and is configured and arranged to be directed onto a target such as tin (Sb), lithium (Li), or gold (Au) to generate EUV light. The polarized beam 14 directed onto such a target results in the generation of target plasma, which in turn emits EUV light. Regarding EUV light, the so-called secondary source is sometimes referred to. In the current context, EUV light is understood to be light with a wavelength of approximately 7.5 nm to approximately 15 nm.

[0064] However, the polarized beam 14 can of course also have relatively low power and be used, for example, for laser marking or cutting processes.

[0065] The optical device 10 has a beam input end 16 for a polarized beam 14, which can enter the beam input end 16 of the optical device 10 along a first propagation axis 18. In addition, the optical device 10 has a beam output end 20 for a polarized beam 14, which can exit the beam output end 20 of the optical device 10 along a second propagation axis 22.

[0066] Furthermore, the optical device 10 has a plurality of deflection elements 24, each of which is configured to deflect the polarized beam 14 within the optical device 10. At least one of these deflection elements 24 is configured to change at least one polarization component of the polarized beam 14.

[0067] A beam path 26 is formed within the optical device 10 by means of a deflection element 24, extending from the beam input end 16 of the optical device 10 to the beam output end 20 of the optical device 10. In the illustrated exemplary embodiment, the beam path 26 is shown as a dashed line.

[0068] According to the invention, in the optical device 10, the deflection elements 24 are arranged such that they can rotate together about the rotation axis 28. Furthermore, according to the invention, in the optical device 10, the first propagation axis 18, the second propagation axis 22, and the rotation axis 28 are parallel to each other. By virtue of these features according to the invention, particularly precise polarization setting of the polarized beam 14 in the target region can be achieved.

[0069] Furthermore, the optical device 10 according to the invention allows the deflection element 24 to be adjusted relative to the rotation axis 28 during operation, i.e., by rotating together about the rotation axis 28, without opening the beam path 16. In other words, depending on the position of the deflection element 24 relative to the rotation axis 16, the polarized beam 14 at the beam output end 20 of the optical device 10 may have a different polarization than the polarized beam 14 at the beam input end of the optical device 10.

[0070] Since the first propagation axis 18, the second propagation axis 22, and the rotation axis 28 are parallel to each other, the angular deviation between the polarized beam 14 entering the optical device 10 and the polarized beam 14 leaving the optical device is largely avoided when the deflection element 24 is in different positions relative to the rotation axis 28. This allows for particularly precise setting of the target position in the target area for different positions of the deflection element 24 relative to the rotation axis 28.

[0071] In the current configuration, the first propagation axis 18, the second propagation axis 22, and the rotation axis 28 exemplarily coincide in a common reference axis 30. Figure 1 In the exemplary embodiment shown, the common reference axis 30 is located on the X-axis of the XY section plane.

[0072] In this exemplary embodiment, the beam path 26 of the optical device 10 is formed within the beam plane 32 by way of example. The beam plane 32 here coincides with the XY plane.

[0073] Furthermore, the deflection elements 24 of the optical device 10 are, in the present case, arranged on a common rotating body 34, which is configured to rotate about a rotation axis 28. In the present case, the rotating body 34 is exemplary constructed as a single piece. The rotating body 34 could also be constructed from multiple parts, and the various parts of the rotating body 34 could be connected to each other using common connection methods. In contrast, the single-piece construction of the rotating body 34 has proven advantageous because such a rotating body 34 is less costly to manufacture and less sensitive to thermal stress. Generally, the deflection elements 24 can therefore be oriented with particular precision when they are arranged on the common rotating body 34, since the common rotating body can rotate about a common rotation axis 28. This eliminates the need for a separate rotating mechanism for each deflection element 24.

[0074] The polarized beam 14 has a first polarization 12.1 before entering the optical device 10. After leaving the optical device 10, the polarized beam 14 has a second polarization 12.2. In the present case, the first polarization 10.1 and the second polarization 10.2 are different, but the first polarization 10.1 and the second polarization 10.2 can also be the same. The first polarization 10.1 can be changed into a second polarization 12.2, different from the first polarization 12.1, by means of the common rotation of the deflection element 24 about the rotation axis 28. In this way, the optical device 10 can be used to set the desired polarization of the polarized beam 14 emitted from the optical device 10.

[0075] An exemplary embodiment of the optical device 10 includes, by way of example, a cooling device 36 configured to dissipate heat from the deflecting element 24. The cooling device 36 is here configured for active fluid cooling, whereas in an exemplary embodiment not specifically shown, the cooling device is configured, for example, as a passive cooling device in the form of a heat dissipation component with a relatively high thermal conductivity. In this case, the heat generated in the deflecting element 24 is dissipated by means of a cooling fluid used for active fluid cooling. The cooling fluid is, for example, water, and thus the fluid cooling is water cooling. In an exemplary embodiment not specifically shown, the cooling fluid is alternatively configured as cooling oil, particularly hydrocarbon-based cooling oil, or as a gas. The deflecting element 24 is thus in direct contact with the cooling water. By means of the cooling device 36, cooling water that has absorbed heat from the deflecting element 24 is discharged, and cooling water at a temperature lower than the discharged cooling water is supplied.

[0076] In exemplary embodiments not specifically shown, the entire rotating body 34 is cooled by means of a cooling device 36. In these exemplary embodiments, the rotating body 34 has cooling channels, whereby heat from the deflecting element 24 can be passively discharged via these cooling channels or via cooling fluid present in these cooling channels, since the deflecting element 24 is in direct contact with the rotating body 34.

[0077] Furthermore, in an exemplary embodiment of the optical device 10, a polarization measuring device 44 is provided for the optical device. The polarization measuring device 44 is capable of measuring the second polarization 12.2 of the polarized beam 14. By means of this measurement of the second polarization 12.2, the actual polarization of the polarized beam 14 after leaving the optical device 10 is determined. The actual polarization is then compared with the set polarization. If an unacceptable deviation occurs between the actual polarization and the set polarization, the second polarization 12.2 can be brought closer to the set polarization by means of the common rotation of the deflection element 24 about the rotation axis 28.

[0078] In the optical device 10 according to an exemplary embodiment, at least one deflecting element 24 is connected to a rotating body 34 via a connecting means 38, such that the deflecting element 24 can expand axially and radially. Specifically, in the present exemplary embodiment, all deflecting elements 24 are connected to the rotating body 34 via such connecting means 38. The number of deflecting elements 24 connected to the rotating body 34 via such connecting means 38 depends substantially on the thermal energy input to the deflecting elements 24. If the polarized beam 14 is deflected with particularly high power, it is advantageous to connect all deflecting elements in such a way that they can expand radially and axially. For a polarized beam 14 with relatively low power, it may be sufficient to connect only one of the deflecting elements 24 to the rotating body 34 in this way.

[0079] In the current configuration, deflection element 24 is constructed as a silicon mirror. In exemplary embodiments not specifically shown, the deflection mirror may alternatively be constructed as a deflection mirror coated with copper (Cu) or gold (Au), or made from a monolithic block of copper (Cu) or gold (Au). In other exemplary embodiments not specifically shown, deflection element 24 may also be constructed as an optical grating, such as a diffraction grating.

[0080] Figure 2 Now shown Figure 1 The connection device 38 of an exemplary embodiment of the optical device shown is in an enlarged view in region II.

[0081] The connecting device 38 is connected to the rotating body 34 via the housing 35. In the present case, this connection is configured to be releasable by a tool, wherein, in the present case, this releasable connection is a screw (not shown). In exemplary embodiments not specifically shown, the connecting device is connected to the rotating body 34 by means of a rivet, a screw with a locking nut, or a pin. Other exemplary embodiments not specifically shown have adhesive or putty materials, material combinations such as welds or brazed joints, or clamping connectors as the connection between the connecting device 38 and the housing 35.

[0082] The deflecting element 24 is arranged inside the housing 35 in the present case, and is guided and / or sealed relative to the housing 35 with respect to the radial extension of the deflecting element 24. This seal blocks cooling fluid, particularly cooling water, and prevents cooling fluid from entering the beam region 27 of the optical device 10. The beam region 27 is subjected to a process gas, and contamination of the process gas is greatly reduced by sealing it with an O-ring 37. The O-ring 37 allows the deflecting element 24 to expand radially. In this way, tension and / or deformation of the deflecting element 24, for example due to thermal stress, are significantly reduced.

[0083] Additionally, the deflecting element 24 is pressed against the contact surface 33 of the rotating body 34 by means of an axial spring 39 supported on the housing 35. In this way, the deflecting element 24 can be precisely positioned relative to the rotating body 34. The contact surface 33 is manufactured using a relatively precise manufacturing process, such as precision milling. The deflecting element 24 can expand axially along the direction of the axial spring 38. In this way, the tension and / or deformation of the deflecting element 24 is further significantly reduced.

[0084] In the optical device 10 according to an exemplary embodiment, at least one deflection element 24 can be adjusted with respect to the orientation of the deflection element relative to a predetermined beam path by means of a correction device 40. The orientation of the deflection element 24 relative to the rotating body 34 can be adjusted by means of the correction device 40. Disorientation of the deflection element 24 relative to the rotating body 34 causes the beam path 26 to deviate from the predetermined beam path. The beam path 26 approaches the predetermined beam path by means of the correction device 40.

[0085] Furthermore, at least one deflection element 24 is equipped with a temperature monitoring device 42. In the optical device 10 of the present exemplary embodiment, all deflection elements 24 are equipped with a temperature monitoring device 42. The temperature monitoring device 42 detects the temperature of the deflection element 24 to which it is respectively assigned, and is also configured to detect over-temperature at the corresponding deflection element 24. As explained above with respect to one or more connecting devices 38, similarly, in the case of a polarized beam 14 with relatively low power, a single temperature monitoring device 42 may be sufficient for only one deflection element 24. As is the case now, where the polarized beam 14 is deflected with particularly high power, it is advantageous to equip each deflection element 24 with a temperature monitoring device 42.

[0086] Figure 3An exemplary embodiment of an optical system 46 according to the present invention is shown. The optical system 46 includes a first optical device 10.1 and a second optical device 10.2, wherein each optical device 10.1, 10.2 has the features of the optical device 10 according to the present invention. The first optical device 10.1 and the second optical device 10.2 are arranged to be rotatable independently of each other, and the first axis of rotation 28.1 of the first optical device 10.1 and the second axis of rotation 28.2 of the second optical device 10.2 are parallel to each other. Therefore, the first rotational stroke of the first optical device 10.1 about the rotational axis 28.1 may be different from the second rotational stroke of the second optical device 10.2 about the rotational axis 28.2. Similarly, the first rotation direction of the first optical device 10.1 and the second rotation direction of the second optical device 10.2 may be different from each other. In other words, the rotation directions may be opposite to each other.

[0087] Furthermore, a sealing and / or shielding device 48 is arranged between the first optical device 10.1 and the second optical device 10.2, which is configured to substantially prevent the escape of processing gas and / or scattered light between the first optical device 10.1 and the second optical device 10.2.

[0088] Figure 4 An exemplary embodiment of an EUV light generation facility 52 is shown, which includes an EUV-driven laser 50, a target generator 54, and an EUV light generation chamber 56. According to the invention, the EUV-driven laser includes, Figure 3 The optical system 46 is shown in the figure.

[0089] List of reference numerals 10 Optical Equipment 10.1 First Optical Equipment 10.2 Second Optical Equipment 12 Polarization 12.1 First Polarization 12.2 Second Polarization 14. Polarized beam 16 Beam Input Terminal 18 First propagation axis 20 beam output end 22 Second propagation axis 24 Deflection elements 26. Beam Path 27 Beam Area 28. Axis of rotation 28.1 First axis of rotation 28.2 Second axis of rotation 30 Shared reference axis 32 Beam Plane 33 Contact surface 34 Shared rotating body 35 Housing 36 Cooling device 37 O-ring 38 Connecting device 39 Axial Spring 40 Calibration Device 42 Temperature monitoring device 44 Polarization Measurement Device 46 Optical System 48 Sealing and / or shielding devices 50 EUV driven laser 52 EUV light generation facility 54 Target Generator 56 EUV light generation chamber

Claims

1. An optical device (10) for changing the polarization (12) of a polarized light beam (14), said optical device having: a) A beam input terminal (16) for the polarized beam (14), which is capable of entering the beam input terminal (16) of the optical device (10) along the first propagation axis (18). b) A beam output end (20) for the polarized beam (14), which is capable of exiting the beam output end (20) of the optical device (10) along the second propagation axis (22). c) A plurality of deflection elements (24), each of which is configured to deflect the polarized beam (14) within the optical device (10), wherein, At least one of these deflection elements (24) is configured to change at least one polarization component of the polarized beam (14). d) Beam path (26), which is configured within the optical device (10) by means of the deflection element (24) to extend from the beam input end (16) of the optical device (10) to the beam output end (20) of the optical device (10). Its features are, e) The deflection element (24) is arranged such that the deflection element can rotate together with the rotation axis (28), and f) The first propagation axis (18), the second propagation axis (22), and the rotation axis (28) are parallel to each other.

2. The optical device (10) according to claim 1, characterized in that, The first propagation axis (18), the second propagation axis (22) and the rotation axis (28) coincide in a common reference axis (30).

3. The optical device (10) according to any one of the preceding claims, characterized in that, The beam path (26) is formed within the beam plane (32).

4. The optical device (10) according to any one of the preceding claims, characterized in that, The deflection element (24) is arranged on a common rotating body (34), which is configured to rotate about the rotation axis (28).

5. The optical device (10) according to claim 4, characterized in that, The rotating body (34) is constructed as a single piece.

6. The optical device (10) according to claim 4 or 5, characterized in that, The rotating body (34) has a cooling device (36) configured to dissipate heat from the deflection element (24).

7. The optical device (10) according to claims 4 to 6, characterized in that, At least one deflection element (24) is connected to the rotating body (34) via a connecting device (38), such that at least one of the deflection elements (24) can expand axially and radially.

8. The optical device (10) according to any one of the preceding claims, characterized in that, At least one deflection element (24) can be adjusted with respect to the orientation of the deflection element relative to the set beam path by means of a correction device (40).

9. The optical device (10) according to any one of the preceding claims, characterized in that, At least one deflection element (24) is equipped with a temperature monitoring device (42).

10. The optical device (10) according to any one of the preceding claims, characterized in that, A polarization measurement device (44) is provided to the optical device (10).

11. An optical system (46) comprising a first optical device (10.1) and a second optical device (10.2) according to any one of the preceding claims, characterized in that, The optical devices (10.1, 10.2) are arranged to rotate independently of each other, and the rotation axes (28.1, 28.2) of the optical devices (10.1, 10.2) are parallel to each other.

12. The optical system (46) according to claim 11, characterized in that, A sealing and / or shielding device (48) is arranged between the first optical device (10.1) and the second optical device (10.2), the sealing and / or shielding device being configured to substantially prevent the escape of processing gas and / or scattered light between the optical devices (10.1, 10.2).

13. An EUV-driven laser (50) comprising an optical device (10) according to any one of claims 1 to 10 or an optical system (46) according to any one of claims 11 or 12.

14. An EUV light generation facility (52) comprising an EUV driven laser (50), a target generator (54), and an EUV light generation chamber (56) as claimed in claim 13.

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