Microlithographic projection exposure system

Abstract

The invention relates to a microlithographic projection exposure system comprising an illumination system (10) and a projection objective (22). The illumination system (10) has a first set of optical elements (18, 19) which are designed to direct electromagnetic radiation emitted by the radiation source (14) onto the photomask (13) in order to irradiate the photomask (13) with the electromagnetic radiation. The projection objective (22) may have a second set of optical elements (M1-M6) to form an imaging beam path through which the photomask (13) is imaged onto the lithographic object. The actuator (33, 39, 67) may be designed to adjust an operating parameter of an optical element (18, 19) of the lighting system (10) or an optical element (M1-M6) of the projection objective (22). The actuator (33, 39, 67) is electrically actuated via an input interface (42), wherein the electric actuation is operated between the input interface (42) and the actuator (33, 39, 67) via a printed circuit board (70). The printed circuit board (70) is arranged inside the housing (34), and the housing (34) is equipped with a cooling channel (46). The printed circuit board (70) is releasably connected to the housing (34) such that the printed circuit board (70) can be separated from the housing (34) without opening the cooling channel (46).

Description

[0001] This patent application claims priority to German patent application DE 10 2023 210 078.9, filed on 13 October 2023, the entire contents of which are incorporated herein by reference (“incorporated by reference”). Technical Field

[0002] This invention relates to a microlithography projection exposure apparatus. Background Technology

[0003] Microlithography projection exposure equipment, comprising an illumination system and a projection lens, is used to fabricate microstructured components. The illumination system guides very short-wavelength deep ultraviolet radiation (DUV radiation) or extreme ultraviolet radiation (EUV radiation) onto a photomask. The projection lens images the photomask onto a lithographic object (such as a silicon wafer) to transfer the mask structure onto a photosensitive coating of the lithographic object.

[0004] Projection exposure equipment includes several optical elements for the beam path of the shaping illumination system and the beam path of the projection lens. In the case of DUV radiation, the optical elements may be lens elements or DUV mirrors. In the case of EUV radiation, these may be optical elements including optical surfaces that reflect EUV radiation. The optical elements have precisely defined shapes and are precisely positioned so that the image of the photomask on the lithographic object has sufficient quality.

[0005] To enable the optical element to be positioned in a manner corresponding to the requirements of the projection exposure equipment, actuators are provided that can influence one or more operating parameters of the optical element. For example, the actuators can be used to influence the position, alignment, and / or temperature of the optical element. Electrical control signals are used to control the actuators.

[0006] Actuators can be controlled via printed circuit board (PCB) modules. For effective heat dissipation, PCB modules can be equipped with liquid cooling, where coolant is conducted through the components of the PCB module to dissipate heat from its electronic components. However, liquid-cooled PCB modules often incur additional costs during maintenance or repair. Summary of the Invention

[0007] The problem addressed by this invention is to provide a microlithography projection exposure apparatus that reduces these drawbacks. This problem is solved by the features of the independent claim. Advantageous embodiments are specified in the dependent claims.

[0008] The microlithography projection exposure apparatus according to the present invention includes an illumination system and a projection lens, wherein the illumination system includes a first set of optical elements designed to guide electromagnetic radiation emitted from a radiation source onto a photomask for irradiating the photomask with electromagnetic radiation, and wherein the projection lens includes a second set of optical elements for shaping an imaging beam path for imaging the photomask onto a lithographic object. The microlithography projection exposure apparatus includes actuators for adjusting operating parameters of the optical elements and an input interface for electrical control of the actuators. An electrical control path between the input interface and the actuators extends via a printed circuit board. The housing is equipped with cooling channels. The printed circuit board is detachably connected to the housing, allowing the printed circuit board to be separated from the housing without opening the cooling channels.

[0009] This invention proposes a functional separation between the printed circuit board and the liquid-cooled housing. It has been found that the opening of the cooling circuitry around the microlithography projection exposure equipment is a common source of failure during maintenance and repair work. According to this invention, maintenance and repair work are significantly simplified because the printed circuit board can be replaced without opening the cooling channels.

[0010] In one embodiment, the microlithography projection exposure apparatus includes a vacuum chamber in which the optical elements of the illumination system and / or the optical elements of the projection lens are arranged. A housing containing a printed circuit board may be arranged within the vacuum chamber. The pressure within the housing may be higher than the pressure within the vacuum chamber.

[0011] To date, control in this design has typically been achieved via printed circuit board modules located outside the vacuum housing. In this design, it is almost inevitable that the printed circuit board modules are positioned at a certain distance from the controlled actuators. As system complexity and the number of actuators to be controlled increase, transmission losses due to distance become increasingly detrimental.

[0012] By reducing the distance between the printed circuit board (PCB) and the actuator of the optical element, losses in electrical signal transmission can be reduced. For this purpose, the PCB can be housed within a casing located in a vacuum chamber. This opens the possibility of operating the PCB within a vacuum chamber in which the controlled optical element is arranged, without the PCB being exposed to the same vacuum atmosphere as the optical element. Therefore, the PCB can operate under different pressure conditions than the optical element, and any potential degassing products from components of the PCB cannot permeate into the optical element.

[0013] If the printed circuit board (PCB) is housed within such a enclosure, it is crucial to dissipate heat from the PCB out of the enclosure and out of the vacuum chamber. If a pressure-sealed enclosure is constructed around the liquid-cooled PCB module, the limited space near the optics would mean that replacing a defective PCB without disassembling the system would be virtually impossible. Therefore, it is proposed that the enclosure be equipped with liquid cooling, while the PCB is not subjected to direct liquid cooling. This improves maintenance convenience because the PCB can be separated from the enclosure without opening the cooling channels formed within it. Furthermore, it reduces wiring costs.

[0014] Cooling channels can extend within the housing structure. During operation of the microlithography projection exposure apparatus, coolant used to dissipate heat from the housing can be conducted along the cooling channels. The coolant can enter the housing structure at a lower temperature and re-enter the housing structure at a higher temperature. The coolant can be guided in a loop, wherein a heat exchanger can be arranged between an outlet exiting the housing structure and an inlet re-entering the housing structure, through which the coolant releases heat. The heat exchanger can be located outside the vacuum chamber. Between the inlet and outlet, the cooling channel can be in the form of a closed cavity in which the coolant is guided. If the cooling channel is to be opened, the coolant can flow out of the cavity at a location different from the intended inlet and outlet.

[0015] Between the inlet and outlet, the cooling channel may include a first portion and a second portion, the first portion extending within the structure of the housing, and the second portion, for example, in the form of a conduit, being guided out of the structure of the housing. For example, such a conduit may extend through the interior of the housing. In one embodiment, between the inlet opening and the outlet opening, the cooling channel extends entirely within the structure of the housing.

[0016] The housing structure can be made of a material with good thermal conductivity. In one embodiment, the housing structure is made of copper. Another possibility is that the housing is made of aluminum, which has the advantage of being lighter. The housing can be designed to avoid direct contact between the coolant and the copper or aluminum material of the housing, for example, by guiding the coolant in tubes (e.g., steel pipes) formed in the housing structure.

[0017] Alternatively, the casing can be made of steel, particularly high-alloy steel, which offers the advantage of higher mechanical strength. The lower thermal conductivity of steel is acceptable in some applications. Regardless of the casing material, the casing can be equipped with one or more heat pipes to improve heat conduction. The heat pipes can be arranged within the casing material.

[0018] To dissipate heat from the printed circuit board (PCB) via liquid cooling, good heat transfer from the PCB to the housing structure is advantageous. A support surface can be formed within the housing structure, on which the PCB or a PCB module including the PCB rests. The housing structure may include uniform structural members within which cooling channels extend, and the support surface is formed on these uniform structural members. In the region where the PCB rests on the support surface, the PCB can be coated with a material with good thermal conductivity. For example, a copper or ENIG (electroless nickel immersion gold) coating can be applied in this region as a thermally conductive material. This then provides a thermal path from the electrical components arranged on the PCB through the PCB substrate and the thermally conductive material to the housing structure.

[0019] In one embodiment, the printed circuit board (PCB) is an integral part of the PCB module, allowing the PCB module to be separated from the housing without opening the cooling channels of the housing. The PCB module may include the PCB and a cooling plate. The cooling plate may be a passive cooling plate, allowing heat to dissipate through thermal conduction within the material of the cooling plate. The cooling plate may be thermally coupled to the PCB through physical contact with the cooling plate. The PCB module may be designed such that a surface portion of the PCB rests on a surface portion of the cooling plate. For good heat transfer, it is advantageous to press the PCB against the cooling plate. In one embodiment, the PCB is screwed onto the cooling plate.

[0020] The printed circuit board module may include a cover over the printed circuit board. The printed circuit board may be disposed between the cover and a cooling plate. The cover may be screwed onto the cooling plate, such that the printed circuit board is pressed against the cooling plate by the cover.

[0021] Heat generated on the printed circuit board (PCB) can be dissipated into the housing via a cooling plate through thermal conduction. The PCB module may include a first thermal path extending from electrical or electronic components disposed on the PCB through the PCB substrate to the cooling plate. Surface areas of the PCB located on the cooling plate may be provided with a metallic coating to improve heat transfer between the PCB and the cooling plate. The metallic coating should be electrically isolated from areas of the PCB that transmit electrical signals. For example, the metallic coating may be a copper coating or an ENIG (electroless nickel immersion gold) coating.

[0022] The printed circuit board module may include a second thermal path extending directly from electrical or electronic components disposed on the printed circuit board to a cooling plate. Components can be thermally coupled to the printed circuit board by placing a suitable thermally conductive material (thermal interface material, TIM) as a gap filler between the component and the cooling plate. For example, one or more components disposed on the printed circuit board may be thermally coupled to the cooling plate by means of thermal paste. In particular, this may involve those components that generate a particularly large amount of heat during the operation of a microlithography projection exposure apparatus.

[0023] If there is a large contact area between the surface of the cooling plate and the supporting surface, good heat transfer from the cooling plate of the printed circuit board module to the housing structure can be facilitated. For example, the supporting surface may extend over at least 5%, preferably at least 10%, and more preferably at least 20% of the area of ​​the cooling plate. In the case of a rectangular cooling plate, the area of ​​the cooling plate is given by the product of the longer and shorter edges. The dimensions of the cooling plate can be determined such that it completely covers the printed circuit board. In embodiments where the printed circuit board rests directly on the housing structure, the specifications may relate to the area of ​​the printed circuit board.

[0024] The housing may include a first support surface and a second support surface, wherein a first portion of the cooling plate rests on the first support surface and a second portion of the cooling plate rests on the second support surface. The first and second portions of the cooling plate may be edge portions of the cooling plate, such that the remaining surface of the cooling plate is surrounded between the first and second portions. The printed circuit board may also be placed on the cooling plate with its edge portions.

[0025] In one embodiment, the housing structure includes a support surface that covers the surface of the cooling plate. This allows the cooling plate to rest entirely on the support surface.

[0026] For optimal heat transfer from the printed circuit board (PCB) to the housing structure, it may be advantageous to press the PCB module against a support surface. Specifically, contact pressure can be generated by pressing the PCB module against the housing using mechanical means. The housing may include a mating surface opposite the support surface. Pressure between the PCB module and the support surface can be generated by means of an extension mechanism. The extension mechanism can be supported on the mating surface to press the PCB module against the support surface. The PCB module can be held between the extension mechanism and the support surface.

[0027] The housing and printed circuit board (PCB) can be designed such that the PCB or PCB module can be inserted into the housing in an insertion direction parallel to the support surface. The expansion mechanism can be configured such that it can be actuated by a tool brought into the expansion mechanism in the insertion direction. To facilitate easy replacement of the PCB or PCB module within the limited space around the optical element, it is advantageous that the insertion direction of the PCB or PCB module corresponds to the direction of actuation of the expansion mechanism.

[0028] If the housing has a first support surface and a second support surface, as well as a first mating surface and a second mating surface, a first extension mechanism can be used to press a printed circuit board or printed circuit board module onto the first support surface, and a second extension mechanism can be used to press a printed circuit board or printed circuit board module onto the second support surface. In this case, care should be taken to ensure that jamming does not occur when tensioning the extension mechanism. Therefore, it may be advantageous to alternately tighten the first extension mechanism and the second extension mechanism.

[0029] The expansion mechanism applies pressure to the printed circuit board (PCB) or PCB module, pressing it against a support surface. This mechanism reduces the air gap between the PCB's cooling plate and the support surface, thereby decreasing thermal resistance. Furthermore, the expansion mechanism itself creates a parallel thermal path between the PCB and the housing structure, allowing heat from the PCB to enter the housing structure. This is typically a secondary thermal path, with most heat continuing to be transferred to the housing via the compressed support surface of the PCB module.

[0030] For good heat transfer, large-area contact between the expansion mechanism and the mating surface, and between the expansion mechanism and the printed circuit board or printed circuit board module, is advantageous. The expansion mechanism may include a wedge-shaped surface through which it expands transversely to its actuation direction. The expansion mechanism may be designed such that the outer surfaces of the expansion mechanism, respectively arranged between two wedge-shaped surfaces, are pressed against the printed circuit board or printed circuit board module and against the mating surface.

[0031] Heat can be transferred from the expansion mechanism to the structure of the housing through the mating surfaces of the housing. To further improve heat transfer, the expansion mechanism may include one or more outer surfaces that abut against the structure of the housing in a direction transverse to the diffusion direction.

[0032] Electrical contacts can be formed within the housing, designed to establish electrical contact with the printed circuit board. These can be insert contacts. The contacts can be designed to automatically engage when the printed circuit board or printed circuit board module is correctly inserted into the housing. The contacts can also be formed on a connecting plate arranged within the housing.

[0033] An output interface may be formed on the housing, through which voltage supply and / or electrical control signals for controlling the actuators of the microlithography projection exposure apparatus are transmitted. The output interface may be formed on the same connection board to which the printed circuit board is also connected. Control signals can be directly transmitted from the output interface to the actuator. Alternatively, another control stage can be inserted between the output interface and the actuator, receiving control information from the output interface and processing it to generate control commands for the actuator. The output interface may also be designed to transmit sensor data acquired within the microlithography projection exposure apparatus to the housing and then to the printed circuit board.

[0034] The printed circuit board may have input contacts that electrically contact the input interface of the housing. The printed circuit board may also have output contacts that electrically contact the output interface. The number of electrical contacts on the output interface may be greater than the number of electrical contacts on the input interface, preferably at least twice as large, and more preferably at least five times as large. This opens up the possibility of controlling a greater number of actuators in the microlithography projection exposure apparatus.

[0035] In the case of the microlithography projection exposure apparatus according to the present invention, the housing can be arranged inside the vacuum chamber, and the optical components are also arranged in the vacuum chamber. During the operation of the microlithography projection exposure apparatus, a high vacuum can exist in the vacuum chamber. In particular, the pressure in the vacuum chamber can be 10... -6 mbar and 10 -9 Between mbar, preferably between 10 -7 and 10 -8 Between mbar. Electronic components are not typically designed to operate at such low pressures, which is why pressures higher than those in a vacuum chamber can exist within the housing where printed circuit boards are housed. The pressure within the housing can exceed 10 mbar. -2 millibars, preferably greater than 10 -1 millibars. In one embodiment, atmospheric pressure is present in the housing.

[0036] To maintain the pressure difference, airtight separation between the interior of the housing and the pressure in the vacuum chamber is advantageous. In one embodiment, the housing itself is designed such that its interior is airtightly separated from the vacuum conditions in the vacuum chamber. Alternatively, a sealed outer housing can be arranged within the vacuum chamber, with a housing containing the printed circuit board disposed inside the outer housing. In this case, free pressure exchange can exist between the interior of the outer housing and the interior of the housing containing the printed circuit board.

[0037] In the event of a printed circuit board (PCB) failure, the PCB or PCB module can be pulled out of the housing without opening the cooling channels. The housing can be designed to disconnect the electrical contacts between the PCB and the connector board, allowing for simultaneous pull-out of the PCB or PCB module. The vacuum chamber, housing, and optional external housing can be designed to be opened to remove the PCB or PCB module, thus allowing access to the PCB or PCB module from outside the vacuum chamber.

[0038] The housing can be designed such that the connector plate remains in position when the printed circuit board or printed circuit board module is pulled out of the housing. In one embodiment, the housing is designed such that the printed circuit board can be removed from the housing together with the connector plate without opening cooling channels. For this purpose, the housing can be equipped with a plug-in unit that carries both the connector plate and the printed circuit board. In a variation, the plug-in unit can be selectively removed from the housing or the printed circuit board can be removed from the plug-in unit.

[0039] Alternatively, the housing can be designed so that the connecting plate cannot be removed from the housing without opening the cooling channels. To allow removal of the connecting plate, the housing may include a first housing portion and a second housing portion, which can separate from each other at a separation point. After the first housing portion separates from the second housing portion, the connecting plate can be removed from the housing. The cooling channels may extend at the separation point such that a first portion of the cooling channel is formed in the first housing portion, and a second portion of the cooling channel is formed in the second housing portion. Therefore, when the first housing portion separates from the second housing portion, the cooling channels are opened.

[0040] The inlet for the cooling channel entering the housing and the outlet for the cooling channel leaving the housing can be arranged in the first housing section. The input interface, printed circuit board, and output interface can be arranged in the second housing section. This allows the second housing section, containing electrical components, to be detached from the first housing section for easy maintenance of the electrical components. This is possible without needing to open the connections of the cooling channels arranged in the first housing section.

[0041] If a failure occurs in an electrical component other than the printed circuit board, such maintenance of the electrical component may become necessary. According to the invention, a printed circuit board with high fault sensitivity can be replaced without opening the cooling channels. The housing may include a housing cover that allows access to the printed circuit board in this manner.

[0042] The optical elements of a microlithography projection exposure apparatus can be EUV mirrors, which are highly reflective mirrors used for electromagnetic radiation with wavelengths between 5 nm and 30 nm, particularly 13.5 nm. An EUV mirror may comprise a mirror body on which a continuous optical surface is formed. This can be used for the projection lens of a microlithography production exposure apparatus. Actuators can be designed to adjust the alignment of the mirror body relative to the frame structure and / or operating parameters associated with the thermal state of the EUV mirror.

[0043] EUV mirrors can also be EUV mirrors for the illumination system of microlithography projection exposure equipment. In one embodiment, an EUV mirror is a faceted mirror with multiple small mirror elements. Specifically, an EUV mirror can be a MEMS mirror module. A MEMS mirror module can include multiple small mirror elements, each individually movably mounted relative to a common base. For each mirror element, an actuator is provided, enabling adjustment of the mirror element along predetermined degrees of freedom. Sensors can be provided to establish the position of the mirror element relative to the carrier base. The sensors can be used to monitor the alignment of the mirror.

[0044] A MEMS mirror module can contain more than 10,000, preferably more than 50,000, and more preferably more than 100,000 mirror elements, which requires a corresponding number of actuators. Given such a large number of actuators, the advantages of this invention are particularly useful.

[0045] In one embodiment, the optical element is a component of a microlithography projection exposure apparatus operating with DUV radiation. DUV radiation specifically refers to electromagnetic radiation with wavelengths between 150 nm and 400 nm. The optical element may be a component of a DUV projection lens, particularly a DUV lens element or a DUV mirror. The optical element may be a component of a DUV illumination system, particularly a DUV lens element or a DUV mirror. The DUV projection exposure apparatus may be designed such that the optical element operates at atmospheric pressure. The pressure within the housing where the printed circuit board is disposed can be matched to the pressure exposed to the optical element. The optical element may be a lens element of a DUV projection lens. The optical element may be a DUV mirror of a DUV projection lens.

[0046] The present invention also relates to a system comprising a vacuum chamber and a printed circuit board. The printed circuit board is arranged inside a housing located within the vacuum chamber, wherein the housing is equipped with cooling channels. In a first state of the system, a vacuum pressure exists within the vacuum chamber, and the pressure within the housing is greater than the pressure within the vacuum chamber. In a second state of the system, the pressure inside the housing corresponds to the pressure within the vacuum chamber, such that the printed circuit board, detachably connected to the housing, can be separated from the housing without opening the cooling channels. In such a system, the advantages of the present invention can be used to control components arranged within the vacuum chamber other than optical elements. The present invention includes improvements to systems having the features described in the context of a mirror system according to the invention. Attached Figure Description

[0047] The invention is described below by way of example based on advantageous embodiments and with reference to the accompanying drawings, wherein:

[0048] Figure 1 : Shows an embodiment of the projection exposure apparatus according to the present invention;

[0049] Figure 2 This illustration shows an embodiment of a microlithography projection exposure apparatus according to the present invention;

[0050] Figure 3 : Show Figure 2 A schematic diagram of the housing of a microlithography projection exposure device;

[0051] Figure 4 It shows Figure 3 One aspect of the shell;

[0052] Figure 5 It shows Figure 3 On the other side of the shell;

[0053] Figure 6 : Shown in enlarged view Figure 5 Details of the casing;

[0054] Figure 7 The following illustrates an alternative embodiment of the invention. Figure 6 The view;

[0055] Figure 8 : illustrated in the diagram Figure 6 Extended mechanism;

[0056] Figure 9 An alternative embodiment of the housing according to the invention is shown;

[0057] Figure 10 : A schematic diagram illustrating an alternative embodiment of the microlithography projection exposure apparatus according to the present invention;

[0058] Figure 11 : Shown in enlarged view Figure 10 Details of the microlithography projection exposure equipment;

[0059] Figure 12 : This illustrates a printed circuit board module of a microlithography projection exposure apparatus according to the present invention. Detailed Implementation

[0060] Figure 1 A microlithography EUV projection exposure apparatus is schematically shown. The projection exposure apparatus includes an exposure beam source 14, an illumination system 10, and a projection lens 22, which operate together in a vacuum chamber 23.

[0061] Exposure beam source 14 generates electromagnetic radiation in the EUV range, specifically electromagnetic radiation with wavelengths between 5 nm and 30 nm. The exposure radiation emitted from exposure beam source 14 is focused into intermediate focal plane 16 by condenser 15. The exposure radiation passing through intermediate focal plane 16 is guided into object plane 12 by illumination system 10, resulting in the object field in object plane 12 being illuminated with uniform radiation intensity.

[0062] The illumination system 10 includes a deflector 17 for deflecting exposure radiation to the first faceted mirror 18. A second faceted mirror 19 is disposed downstream of the first faceted mirror 18. The second faceted mirror 19 is used to image the facets of the first faceted mirror 18 onto the object plane 12.

[0063] A photomask 13 is arranged in the object plane 12 and imaged onto the image plane 21 by multiple mirrors M1-M6 of the projection lens 22. The structure formed on the photomask 13 is transferred to the radiation-sensitive layer of the wafer 20 arranged in the image plane 21. The photomask 13 is suspended on the first scanning device 24, and the wafer 20 is placed on the second scanning device 25, so that the wafer 20 can be exposed during the scanning process, during which the photomask 13 and the wafer 20 move synchronously with each other.

[0064] Various reflectors used in projection exposure equipment to reflect illumination radiation are configured as EUV reflectors. EUV reflectors are provided with a highly reflective coating. Multilayer coatings can be involved, particularly multilayer coatings with alternating layers of molybdenum and silicon.

[0065] One or more of the EUV reflectors M1-M6 can be as follows: Figure 2 The components of the EUV reflector system are schematically shown. The reflector bodies 38 of reflectors M1-M6 are held on the frame structure 31 by an adjustment mechanism 30. The adjustment mechanism 30 can be used to change the position of the reflector bodies 38 relative to the frame structure 31 in order to orient and position the reflector bodies 38. An optical surface 32 for reflecting EUV radiation is formed on the reflector bodies 38.

[0066] A cooling channel 37, extending along a serpentine path through the reflector body 38, is formed inside the reflector body 38. The cooling channel 37 is part of a cooling system in which coolant is delivered by means of a pump 33 along a closed cooling loop. The cooling loop extends from the pump 33 through a feed line 35 to the cooling channel 37 and returns to the supply container 41 via a return line 36, from which the pump 33 draws coolant. The feed line 35 and the return line 36 are sufficiently flexible to not impede the adjustment and alignment of the reflector. The coolant absorbs heat generated due to absorbed EUV radiation and removes it from the reflector body 38.

[0067] The heating device 39 is arranged and aligned such that the infrared radiation emitted by the heating device 39 can be directed to the optical surface 32 of the EUV mirror. Using the heating device 39, heat can be supplied to the mirror body 38 to maintain the optical surface 32 at a target temperature during operation of the projection exposure apparatus.

[0068] The regulating mechanism 30, the pump 33 of the cooling circuit, and the heating device 39 each form an actuator for the EUV reflector system, which can be used to adjust the operating parameters of the EUV reflector. The EUV reflector system includes a controller that controls the actuators of the EUV reflector system based on various input variables. The controller includes a housing 34, which, in the exemplary embodiment shown, is attached to the frame structure 31 of the EUV reflector.

[0069] In this exemplary embodiment, the housing 34 is pressure-sealed, and an airtight separation is formed between the interior and exterior of the housing 34. This allows the components inside the housing 34 to operate at pressures deviating from the vacuum conditions exposed by the EUV reflectors M1-M6. In particular, a pressure approximately corresponding to atmospheric pressure can exist inside the housing 34.

[0070] according to Figure 3 As shown in the schematic diagram, housing 34 is provided with input interface 42 and output interface 43. In an exemplary embodiment, power is supplied to the EUV mirror system via input interface 42, and control signals such as sensor data and other control information related to the operation of the EUV mirror system are transmitted.

[0071] Inside the housing 34 is a connection plate 44 that connects to the output interface 43. The connection plate 44 has multiple insertion positions into which the printed circuit board module 40 is inserted. The printed circuit board module 40 is electrically coupled to the input interface 42. Coupling can be achieved via a cable sleeve or cable connection suitable for vacuum.

[0072] according to Figure 12Each printed circuit board module 40 includes a printed circuit board 70 having electronic components 71. The printed circuit board module 40 also includes a cooling plate 72 extending parallel to the printed circuit board 70 and covering the main portion of the printed circuit board 70. The printed circuit board 70 rests on a protrusion of the cooling plate 72 with its edge region, such that the electronic components 71 are surrounded between the printed circuit board 70 and the cooling plate 72. Opposite sides of the printed circuit board 70 are covered by a cover 73, which is screwed onto the cooling plate 72. The printed circuit board 70, disposed between the cover 73 and the cooling plate 72, is pressed against the cooling plate 72 by screw connections.

[0073] The heat generated in electronic component 71 diffuses into the substrate of printed circuit board 70 via thermal conduction and is transferred to cooling plate 72 through edge region 74 of printed circuit board 70. Edge region 74 of printed circuit board 70 is provided with a metallic coating, resulting in good thermal conductivity. In the case of components that generate a large amount of heat, it is recommended to attach the component to the cooling plate, which can be achieved by using a spacer / spacer filler and a cooling plate design with a supporting surface; see [link to relevant documentation]. Figure 9 .

[0074] A printed circuit board module 40 is provided, which is designed as a DC / DC converter to supply voltage to the EUV mirror system. Other printed circuit board modules 40 carry FPGAs (Field Programmable Gate Arrays) that handle the control functions of the EUV mirror system. In this exemplary embodiment, each printed circuit board module 40 has input contacts electrically connected to an input interface 42 and output contacts coupled to an output interface 43 via a connection board 44.

[0075] The actuator of the EUV reflector system can be directly controlled from the output interface 43. Another control stage can also be arranged between the output interface 43 and the actuator, processing control commands received from the output interface 43 to control the actuator. The number of electrical contacts in the output interface 43 can be substantially greater than the number of electrical contacts in the input interface 42. All computational operations within the housing 34 are performed by the printed circuit board 70 of the printed circuit board module 40. The connection board 44 is used only for transmitting signals to the output interface 43.

[0076] according to Figure 4 In another schematic diagram, the housing 34 is provided with an inlet 48 and an outlet 49 for a liquid cooling system. A cooling channel 46 extending along a serpentine path over a large area of ​​the housing 34 is formed inside the structure 50 of the housing 34. The cooling channel 46 forms a closed path between the inlet 48 and the outlet 49. Cooling liquid flowing in through the inlet 48 moves along a predetermined path to the outlet 49 and has no further possibility of leaving the cooling channel 46.

[0077] The housing 34 has a separation point 47 at which the upper portion 29 of the housing 34 can be separated from the lower portion 28 of the housing 34. When the housing 34 is opened at the separation point 47, the liquid cooling system is also activated, resulting in liquid in the cooling channel 46 leaking out in the area of ​​the separation point 47. The inlet 48 of the cooling channel 46 entering the housing 34 and the outlet 49 of the cooling channel 46 leaving the housing 34 are connected to the lower portion 28 of the housing 34, so that when the upper portion 29 of the housing 34 is lifted from the lower portion 28, it is not necessary to activate the cooling circuit. The printed circuit board module 40 and the connection plate 44, as well as the input interface 42 and the output interface 43, are connected to the upper portion 29 of the housing 34, making them accessible for maintenance when the upper portion 29 is lifted.

[0078] Specifically, this maintenance procedure becomes necessary if a fault occurs in the connection board 44 or the wiring near the connection board 44. Such a fault is not highly probable because the connection board 44 and the electrical wiring are simple electrical components. More complex electronic devices with higher fault susceptibility are fully housed within the printed circuit board module 40.

[0079] To eliminate faults in the printed circuit board module 40, the housing 34 is provided with a housing cover 45, which can be lifted without opening the cooling channel 46. In another schematic diagram, Figure 5 The view shown is the result after the housing cover 45 has been opened. The housing 34, constructed of solid copper, has a recess 51 extending into its depth and defining the insertion direction of the printed circuit board module 40. The recess 51 forms a track along which the printed circuit board 40 can be inserted into the housing 34. Electrical contacts for the connecting plate 44 are formed in the rear of the housing 34 and automatically engage when the printed circuit board 40 has been correctly inserted along the two recesses 51.

[0080] according to Figure 6 In the enlarged view, one surface of the groove 51 forms a support surface 57 on which the peripheral portion of the printed circuit board module 40 rests. An extension mechanism 52 is arranged between the opposing surface of the printed circuit board module 40 and the mating surface 58 of the groove 51. The extension mechanism 52 extends in the direction of the arrow to press the printed circuit board 40 against the support surface 57. Figure 8 The expansion mechanism 52 includes a plurality of blocks 54 that abut against each other via wedge-shaped surfaces. The blocks 54 can be tensioned against each other in the longitudinal direction 56 by means of a tensioning device 55, and thus expand in a direction transverse to the longitudinal direction 56. The large surfaces of the blocks 54 then press against mating surfaces 58 or the printed circuit board module 40. Pressure is transmitted via the printed circuit board module 40 to the support surface 57.

[0081] This creates two parallel thermal paths through which heat generated in the electronic components 71 of the printed circuit board 70 during operation of the EUV mirror system can be dissipated. The first thermal path extends from the electronic components 71 through the substrate of the printed circuit board 70 and the edge region of the cooling plate 72 to the housing structure 50, where heat can be dissipated via cooling channels 46. The second thermal path extends from the electronic components 71 through the substrate of the printed circuit board 70, the edge region of the cooling plate 72, and the extension mechanism 52 to the structure 50 of the housing 34.

[0082] Figure 7 An alternative embodiment of the extension mechanism 52 is shown, which extends additionally in a direction transverse to it. This creates another surface through which the extension mechanism 52 rests against the structure 50 of the housing 34, thus further improving heat transfer from the printed circuit board module 40 to the housing 34.

[0083] exist Figure 9 In an alternative embodiment of the housing 34, the structure 50 of the housing 34 includes a planar region 61 extending above and below the printed circuit board module 40 on its surface. The planar region 61 is provided with cooling channels 46 in a manner similar to other regions of the structure 50 of the housing 34. An extension mechanism 52, schematically shown, is supported between the mating surface 58 and the printed circuit board module 40 to press the printed circuit board module 40 against the surface of the upper planar region 61 over a large area. This improves cooling efficiency because it increases the heat transfer from the cooling plate 72 of the printed circuit board module 40 to the available areas within the structure 50 of the housing 34.

[0084] An electronic component 71 that emits a particularly large amount of heat during the operation of the EUV reflector system is shown on the upper side of the printed circuit board 40. The electronic component 71 is thermally coupled to the cooling plate 72 of the printed circuit board module 40 above it by means of thermal paste 60.

[0085] Figure 10 A schematic diagram of the first faceted mirror 18 of the illumination system 10 of the microlithography projection exposure apparatus is shown, wherein the first faceted mirror 18 is in the form of a MEMS mirror module. The MEMS mirror module includes a frame structure 63 that carries a plurality of multi-mirror units 64. A plurality of housings 34 of the same type are attached to the frame structure 63.

[0086] MEMS mirror modules can include a large number of multi-mirror units 64, such as hundreds of such units. Each multi-mirror unit 64 can further include a large number of small mirror elements, so the MEMS mirror module can include tens of thousands of mirror elements in total.

[0087] Figure 11 A cross-section of a multimirror unit 64 having three mirror elements 66 is shown. Each mirror element 67 is connected to the base 65 of the multimirror unit 64 via a flexure 69. An actuator 67 can be used to change the alignment of the mirror element 66 relative to the base 65. Each mirror element 66 is also equipped with a sensor 68 for determining the current alignment of the mirror element 66.

[0088] Each housing 34 is responsible for controlling a portion of the mirror element 67 of the MEMS faceted mirror. The controller can be organized such that each multi-mirror unit 64 includes a control unit for controlling the individual mirror elements 66, and the control unit of the multi-mirror unit 64 is controlled from the housing 34. In this configuration, the housings 34 can collectively form a complete interface to the outside, allowing all power for actuating the actuator 67 and all necessary control information to be fed into the MEMS mirror module system through the housings 34.

Claims

1. A microlithography projection exposure apparatus comprising an illumination system (10) and a projection lens (22), wherein the illumination system (10) includes a first set of optical elements (18, 19) designed to guide electromagnetic radiation emitted by a radiation source (14) onto a photomask (13) to illuminate the photomask (13) with the electromagnetic radiation, wherein the projection lens (22) includes a second set of optical elements (M1-M6) to form an imaging beam path for imaging the photomask (13) onto a lithographic object; and having actuators (33, 39, 67) for adjusting the optical elements (18, 19) of the illumination system (10) or the projection lens. Operating parameters of the optical elements (M1-M6) of the head (22); and an input interface (42) for electrically controlling the actuators (33, 39, 67), wherein the electrical control path between the input interface (42) and the actuators (33, 39, 67) extends via a printed circuit board (70), wherein the printed circuit board (70) is arranged inside a housing (34), wherein the housing (34) is equipped with a cooling channel (46), wherein the printed circuit board (70) is detachably connected to the housing (34) such that the printed circuit board (70) can be separated from the housing (34) without opening the cooling channel (46).

2. The microlithography projection exposure apparatus according to claim 1, comprising a vacuum chamber (23), wherein the optical elements (18, 19) of the illumination system (10) and / or the optical elements (M1-M6) of the projection lens (22) are arranged in the vacuum chamber (23), wherein a housing (34) is arranged in the vacuum chamber (23), and wherein the pressure in the housing (34) is higher than the pressure in the vacuum chamber (23).

3. The microlithography projection exposure apparatus according to claim 1 or 2, wherein the cooling channel (46) extends in the structure (50) of the housing (34).

4. The microlithography projection exposure apparatus according to any one of claims 1 to 3, comprising a printed circuit board module (40) capable of being separated from the housing (34) without the cooling channel (46) being opened, wherein the printed circuit board module (40) comprises the printed circuit board (70) and a cooling plate (72) thermally coupled to the printed circuit board (40).

5. The microlithography projection exposure apparatus according to claim 4, wherein the printed circuit board (40) is coated with a thermally conductive material in the area where the printed circuit board (40) rests on the cooling plate (72).

6. The microlithography projection exposure apparatus according to claim 4 or 5, wherein a support surface (57) is formed in the structure (50) of the housing (34), and the cooling plate (72) of the printed circuit board module (40) rests on the support surface.

7. The microlithography projection exposure apparatus according to any one of claims 4 to 6, wherein the housing (34) includes a mating surface (58) opposite to the support surface (57), and wherein the extension mechanism (52) is supported on the mating surface (58) to press the cooling plate (72) of the printed circuit board module (40) against the support surface (57).

8. The microlithography projection exposure apparatus according to claim 7, wherein the extension mechanism (52) is designed to extend laterally to its actuation direction (56).

9. The microlithography projection exposure apparatus according to claim 7 or 8, wherein the extension mechanism (52) forms a thermal path between the cooling plate (72) of the printed circuit board module (40) and the structure (50) of the housing (34), such that heat from the printed circuit board module (40) enters the structure (50) of the housing (34) through the extension mechanism (52).

10. The microlithography projection exposure apparatus according to any one of claims 1 to 9, wherein the housing (34) hermetically separates the interior of the housing (34) from the vacuum conditions in the vacuum chamber (23).

11. The microlithography projection exposure apparatus according to any one of claims 1 to 10, wherein the housing (34) comprises a first housing portion (28) and a second housing portion (29) capable of separating from each other at a separation point (47), wherein the cooling channel (46) extends at the separation point (47).

12. The microlithography projection exposure apparatus according to any one of claims 1 to 11, wherein the optical element is an EUV reflector (M1-M6) of an EUV projection lens (22).

13. The microlithography projection exposure apparatus according to any one of claims 1 to 12, wherein the optical element is a MEMS mirror module.

14. The microlithography projection exposure apparatus according to any one of claims 1 to 11, wherein the optical element is the EUV reflector (M1-M6) of the projection lens (22).

15. The microlithography projection exposure apparatus according to any one of claims 1 to 11, wherein the optical element is a lens element of a DUV mirror or a DUV projection lens (22).

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