TEMPERATURE CONTROL DEVICE FOR TEMPERING A POSITION-SENSITIVE COMPONENT OF A LITHOGRAPHING PLANT, LITHOGRAPHING PLANT AND METHOD FOR OPERATING A TEMPERATURE CONTROL DEVICE

Abstract

A temperature control device (200) for temperature control of a position-sensitive component (102) of a lithography system (1), comprising a liquid line (208) with a line section (218) for transporting a temperature control liquid (206), and a gas bubble separator (220) with a branch line section (222) branching off from the line section (218), wherein within the branch line section (222) a fluid space (224) and a gas space (226) are formed, fluidly connected to the line section (218), and the gas space (226) is connected to the liquid space (224) by means of a gas passage unit (228) for allowing gas bubbles (216) to pass from the liquid space (224) into the gas space (226).

Description

[0001] The present invention relates to a temperature control device for temperature control of a position-sensitive component of a lithography system, a lithography system with such a temperature control device and a method for operating such a temperature control device.

[0002] Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system, which includes an illumination system and a projection system. The image of a mask (reticule) illuminated by the illumination system is projected by the projection system onto a substrate, such as a silicon wafer, coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system. This transfers the mask structure onto the photosensitive coating of the substrate.

[0003] Driven by the pursuit of ever smaller structures in the fabrication of integrated circuits, EUV lithography systems are currently being developed that utilize light with wavelengths ranging from 0.1 nm to 30 nm, particularly 13.5 nm. Since most materials absorb light of this wavelength, such EUV lithography systems must employ reflective optics, i.e., mirrors, instead of the previously used refracting optics, i.e., lenses.

[0004] The demands on the accuracy and precision of the imaging properties of lithography systems are constantly increasing. From a dynamic perspective, it is therefore essential to minimize the influence of disturbances on the movement of various position-sensitive components of the lithography system. For example, very precise positioning of optical components, especially mirrors, is required. Dynamic disturbances of optical components can be generated, for example, by the movement of other components of the lithography system or by acoustic disturbances. Acoustic disturbances can be transmitted to temperature-controlled, position-sensitive components of the lithography system as pressure fluctuations of a fluid in the fluid lines of a temperature control device (e.g., a cooling device). Pressure fluctuations of the fluid are generated, for example, by flow-induced vibrations (FIV).Pressure fluctuations of the liquid can also be generated by the transmission of mechanical vibrations from other mechanical components (e.g. support elements) to a liquid line (e.g. via fastening elements) or by external acoustic excitation ("vibrating pipelines").

[0005] With the increasing complexity of lithography systems, further dynamic disturbances within and outside the system are to be expected, making additional mechanisms for their suppression or compensation desirable and necessary. Conventional solutions for reducing disturbance excitation of mirrors in a lithography system due to flow-induced vibrations are known, for example, from WO 2021 013 441 A1.

[0006] Against this background, one object of the present invention is to improve the temperature control of a position-sensitive component of a lithography system.

[0007] According to a first aspect, a temperature control device for temperature-controlling a position-sensitive component of a lithography system is proposed. The temperature control device comprises a fluid line with a section for transporting a temperature control fluid. Furthermore, the device includes a gas bubble separator with a branch line extending from the main line. Within the branch line, a fluid chamber and a gas chamber are formed, both fluidically connected to the main line. The gas chamber is also connected to the fluid chamber by means of a gas passage unit, allowing gas bubbles to pass from the fluid chamber into the gas chamber.

[0008] The gas bubble separator allows gas bubbles to be drawn off and / or removed from the temperature control fluid in the section of the fluid line of the temperature control device. This reduces and / or prevents (and / or allows for targeted adjustment) the reflection of a pressure wave entering the line section by one or more gas bubbles (e.g., at the phase boundaries of the gas bubbles), thus preventing the generation of a standing pressure wave in that section. This allows pressure maxima (e.g., pressure peaks) of a pressure wave in the temperature control fluid to be reduced and / or avoided (and / or selectively relocated).

[0009] Furthermore, the gas bubble separation device can shift the spectrum of a resulting standing pressure wave from a frequency range sensitive to the position-sensitive component to a frequency range that is insensitive and / or less sensitive to the position-sensitive component. For example, a frequency range sensitive to the position-sensitive component is one in which the position of the component is controlled based on a control loop.

[0010] Consequently, the gas bubble separator can reduce and / or prevent the impact of acoustic interference on the position-sensitive component caused by pressure fluctuations in the temperature control fluid (e.g., by shifting it to an insensitive frequency range). This, in turn, can improve the imaging properties of the lithography system (or an optical property of another system in which the temperature control device is used). Furthermore, interference can be better compensated for and / or controlled, even in increasingly complex lithography systems (or other systems) with a growing number of interference sources.

[0011] The gas bubble separator is, in particular, a device for separating gas bubbles from the main pipe section into the secondary pipe section. The separated gas bubbles can be collected in the secondary pipe section (together with a small amount of temperature control fluid) and / or removed from the secondary pipe section, e.g., discharged as gas. Therefore, the gas bubble separator described herein can also be referred to as a gas bubble separator and / or gas bubble collection device.

[0012] Herein, the temperature control device is usually described as a device for controlling the temperature of a position-sensitive component of a lithography system. However, the temperature control device can also be used for a position-sensitive component of another optical system, such as a mask testing system (e.g., a modified lithography system) or a mask repair system (e.g., a system for particle beam-induced processing of a photomask for microlithography). Therefore, where reference is made here to a lithography system, this could also refer to another optical system, such as a mask testing system or a mask repair system. Furthermore, where reference is made here to a position-sensitive component of a lithography system, this could also refer to a position-sensitive component of the other system.

[0013] The position-sensitive component can be an optical or a mechanical component of the lithography system, e.g., a projection system. In particular, the position-sensitive component is a part that must be held in a precise position with only small tolerances during operation of the lithography system.

[0014] The position-sensitive component of the lithography system is, for example, a mirror within the system, such as a mirror in the projection optics. The mirrors of a projection optic in an EUV lithography system are typically mounted on a support frame by means of actuators, allowing precise adjustment of the mirror's position, for example, in six degrees of freedom. These six degrees of freedom include, in particular, three translational degrees of freedom (e.g., in three mutually perpendicular spatial directions) and three rotational degrees of freedom (e.g., with respect to rotation about the three mutually perpendicular spatial directions).

[0015] The position-sensitive component of the lithography system can also be a support structure and / or frame structure that serves as a (e.g., optical) reference. The position-sensitive component can, for example, be a sensor frame of the lithography system, such as the projection optics of the lithography system. A sensor frame typically includes a sensor device for measuring the current position of one or more optical components of the lithography system relative to the sensor frame. The sensor frame is, for example, vibrationally decoupled from a support frame of the optical component(s). The sensor device comprises, for example, one or more sensors, such as interferometers and / or other measuring devices for detecting the position of the optical component(s). The optical component(s) may, for example, include reflector elements for reflecting light (e.g., laser light) emitted by the sensors.For example, one or more sensors are used to detect the position of the optical component(s) in the six degrees of freedom.

[0016] The temperature control device can be used to influence the thermal condition of the position-sensitive component. Specifically, the temperature control device can be used to regulate the temperature of the position-sensitive component, meaning it can be cooled or heated. Accordingly, the temperature control device is, for example, a cooling device or a heating device. Furthermore, the temperature control fluid is, for example, a cooling fluid or a heating fluid.

[0017] In the following, the temperature control device is usually described as a cooling device. However, in other embodiments, the temperature control device can also be a heating device. Therefore, whenever the present application refers to a cooling device, cooling unit, cooling, coolant, cooling line, etc., it could just as easily mean a heating device, heating unit, heating, heating fluid, heating line, etc.

[0018] The cooling device, as an example of a temperature control device, serves in particular to prevent high temperatures and temperature fluctuations (e.g. spatial and temporal temperature fluctuations) of the position-sensitive component.

[0019] In particular, mirrors in an EUV lithography system (as an example of position-sensitive components) heat up as a result of (e.g., partial) absorption of the high-energy EUV radiation. The resulting high temperatures and temperature fluctuations within the mirror, and the associated thermal deformations, can lead to wavefront aberrations and thus impair the imaging properties of the mirrors. To prevent thermally induced deformations, mirrors in the lithography system can be actively cooled.

[0020] The cooling device, as an example of a temperature control device, can also be used (additionally or instead) to cool, for example, a sensor frame (as an example of a position-sensitive component). This prevents thermal crosstalk (e.g., heating of the sensor frame by heat radiation). Heat radiation is emitted particularly by mirror surfaces or structural elements of the lithography system. Other heat sources that contribute to increased surface temperatures can include actuators and heating heads. The cooling device creates a stable temperature environment for the sensor frame. This allows for more accurate position measurement of the mirror or mirrors using the sensor device held by the sensor frame.

[0021] The cooling device, as an example of a temperature control device, further comprises, for example, a cooling unit for cooling the coolant, one or more pumps for generating a required coolant flow rate, and one or more valves for controlling the coolant flow.

[0022] Cooling requires a specific coolant flow rate, which is achieved via a pump system. This results in dynamic disturbances, as each pump generates local pressure fluctuations. These are transmitted throughout the cooling circuit via coolant noise (fluid noise, longitudinal fluid sound wave). Furthermore, any change in cross-section, any bend in the fluid line, and any valve within the cooling circuit can represent a source of disturbance, causing local pressure fluctuations in the fluid. This type of dynamic disturbance is also known as flow-induced vibration (FIV). The disturbance is transmitted to the cooled position-sensitive component via fluid noise. This can cause the position of the position-sensitive component to deviate from a desired position.In particular, a pressure surge from the coolant acts on surfaces of the cooled position-sensitive component. This pressure surge is converted into a force at the surfaces on which it acts. This force can cause the position of the position-sensitive component to deviate from a desired position. Generally speaking, any pressure disturbance, such as one or more pressure surges, a harmonic pressure signal, and / or a harmonic pressure fluctuation of the coolant, can cause disturbances in the cooled position-sensitive component.

[0023] The lithography system is, for example, an EUV or a DUV lithography system. EUV stands for "extreme ultraviolet" and refers to a wavelength of the working light in the range of 0.1 nm to 30 nm, specifically 13.5 nm. DUV stands for "deep ultraviolet" and refers to a wavelength of the working light between 30 nm and 250 nm.

[0024] The EUV or DUV lithography system comprises an illumination system and a projection system. Specifically, the EUV or DUV lithography system projects the image of a mask (reticule) illuminated by the illumination system onto a substrate, such as a silicon wafer, coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system, in order to transfer the mask structure onto the photosensitive coating of the substrate.

[0025] The section of the fluid line (e.g., cooling line) includes, for example, a fluid pipe (e.g., a metal pipe and / or a stainless steel pipe). The fluid pipe has, for example, an outer and an inner wall. Alternatively, the section of the fluid line (e.g., cooling line) can also include, for example, a fluid channel formed within a solid body (e.g., a support frame of the lithography system).

[0026] The fluid line serves, for example, to transport the temperature control fluid, e.g., to and / or from the position-sensitive component. The fluid line serves, for example, to transport the temperature control fluid from a temperature control unit (e.g., a cooling unit) of the temperature control device to the position-sensitive component and / or from the position-sensitive component (back) to the temperature control unit. The temperature control device can also have more than one fluid line.

[0027] The liquid line and / or the line section has / have, for example, a circular cross-section, an oval cross-section, a square cross-section, a rectangular cross-section and / or a polygonal cross-section.

[0028] The section of the liquid line has, in particular, an interior space (liquid chamber) for receiving the temperature control fluid.

[0029] The temperature control fluid (e.g., cooling fluid) is or comprises, for example, water or another suitable liquid.

[0030] The gas bubble separator serves to separate (i.e., remove) gas bubbles from the temperature control fluid in the main line section (e.g., also to collect gas bubbles in the branch line section). The gas bubbles are moved and / or transported from the main line section into the fluid space of the branch line section. From the fluid space of the branch line section, the gas bubbles are then moved and / or transported, for example, at least partially, through the gas passage unit into the gas space of the branch line section.

[0031] The bypass section of the gas bubble separator is fluidly connected to the liquid line section. In other words, the liquid chamber of the bypass section is fluidly connected to a liquid chamber within the main line section. Therefore, the temperature control fluid can flow from the main line section into the liquid chamber of the bypass section.

[0032] The branch line section includes, for example, a fluid pipe (e.g., a metal pipe and / or a stainless steel pipe) and / or a fluid hose (e.g., an elastic fluid hose, which is connected to the line section, for example, via a flange and / or a tee) branching off from the line section.

[0033] Optionally, the branch line section can form a T-junction together with the main line section.

[0034] However, the branch line section may also simply be a bulge in the line section, e.g. a dome-shaped bulge, a chamber and / or a cavitation.

[0035] The liquid chamber in the branch line section is designed to hold the temperature control fluid. Additionally, the gas chamber in this branch line section is designed to hold gas bubbles from the temperature control fluid and / or gas from the gas bubbles. If the gas passage unit (e.g., a valve) is configured to allow the gas bubbles to pass through along with the temperature control fluid as a gas-liquid mixture, the gas chamber of the branch line section can also be designed to hold this gas-liquid mixture.

[0036] A gas in gas bubbles contains, for example, nitrogen, oxygen, argon, and / or carbon dioxide. However, a gas in gas bubbles can also contain, additionally or instead, one or more other gases and / or gas components.

[0037] The gas space of the bypass section is connected to the liquid space of the bypass section by means of a gas passage unit for allowing gas bubbles to pass through. The gas passage unit is specifically designed to selectively allow gas bubbles from the liquid space of the bypass section into the gas space. A first example of selective gas bubble passage is a gas-permeable and liquid-impermeable gas passage unit (e.g., a membrane). In this first example, the gas passage unit is thus designed to allow only the gas bubbles to pass into the gas space while remaining impermeable to the temperature control liquid. In a second example of selective gas bubble passage, the gas passage unit can be designed to allow the gas bubbles (e.g., as part of a gas-liquid mixture) to pass through only temporarily (e.g., a valve).

[0038] One can also say that the gas passage unit (in both the first and second examples) partially separates the gas space of the bypass section from the liquid space of the bypass section. In the first example (e.g., a diaphragm), partial separation means separation with respect to the temperature control fluid, while the gas passage unit is permeable with respect to the gas bubbles. In the second example (e.g., a valve), partial separation means temporary separation with respect to a gas-liquid mixture (i.e., the temperature control fluid with the gas bubbles).

[0039] The gas bubble separator is specifically designed to guide, i.e., move and / or transport, gas bubbles within the temperature control fluid from the main line section to the secondary line section (i.e., the fluid space of the secondary line section). For example, the gas bubble separator is designed to guide gas bubbles within the temperature control fluid from the main line section to the secondary line section based on one or more physical and / or chemical mechanisms. These physical and / or chemical mechanisms include, for example, hydrostatic buoyancy, a flow effect, a temperature field, an acoustic trap, adhesion in porosities, and / or a concentration gradient. The physical and / or chemical mechanisms may also, for example, be a combination of one, several, or all of the aforementioned mechanisms.

[0040] Regarding the flow effect, the flow rate of the temperature control fluid in the main pipe section can, for example, cause gas bubbles to be diverted into the secondary pipe section. Furthermore, the gas bubble separation device can also include one or more baffles, for example, within the main pipe section, within the secondary pipe section, and / or in a transition zone between the main pipe section and the secondary pipe section, to divert gas bubbles into the secondary pipe section by changing the momentum of the flow through the baffles.

[0041] With regard to the temperature field, the gas bubble separation device can, for example, have one or more heating elements (e.g., external heating elements) that generate a temperature gradient and, accordingly, a density gradient that diverts gas bubbles from the main line section to the secondary line section.

[0042] With regard to the acoustic trap, an ultrasonic unit can be used to generate local pressure fields and / or pressure gradients in the fluid, along which the one or more gas bubble(s) are guided into the bypass section.

[0043] Regarding adhesion in porosities, the surface tension of the contact area between a gas bubble and the coolant is used to transport the gas bubble. For this purpose, a porous material such as metal foam with a gradient of cavity sizes can be used. The gas bubble is trapped in the relatively large cavities and drawn into relatively small cavities by the surface tension of the contact area between the gas bubble and the coolant. In addition to irregularly distributed cavities, the porosity can also feature structured cavities, such as conically tapered channels. The gradient of cavity size is adjusted so that the corresponding gas bubble(s) are diverted from the main pipe section to the secondary pipe section.

[0044] Regarding the concentration difference, a chemical substance, such as a salt, is introduced into the branch line. As the salt dissolves continuously, a concentration difference develops between the fluid in the main line and the fluid in the branch line, thus generating a fluid flow. The gas bubbles then migrate along this flow from the main line to the branch line.

[0045] The temperature control device can also have more than one gas bubble separator. The one or more gas bubble separators are, for example, located far away from the position-sensitive component and / or at acoustically insensitive positions in the liquid line.

[0046] According to one embodiment, the branch line section is arranged ascending from the line section with respect to gravity.

[0047] This means that the gas bubble separation device is designed to guide, i.e., move and / or transport, gas bubbles within the temperature control fluid from the main line section to the secondary line section (i.e., the fluid space of the secondary line section) based on a hydrostatic buoyancy acting on the gas bubbles.

[0048] According to another embodiment, the gas bubble separator has a suction unit for extracting gas from the gas space.

[0049] The extraction unit can be used to extract gas located in the gas chamber.

[0050] The extraction unit allows, for example, the setting of a predetermined gas pressure in the gas space. This, in the case of a gas-permeable and liquid-tight gas passage unit (e.g., a membrane), can enhance the diffusion of gas from the liquid space of the secondary line section into the gas space.

[0051] If the gas passage unit (e.g. a valve) is designed to allow a gas-liquid mixture to pass through (e.g. temporarily), a gas-liquid mixture located in the gas space can also be extracted using the extraction unit.

[0052] The extraction unit includes, for example, one or more pumps and / or one or more gas lines. For instance, the extraction unit may have a gas line leading from the gas space of the secondary line section and a pump operatively connected to it. Alternatively, the extraction unit may have a gas line leading from the pump to outside a vacuum enclosure to discharge the gas into a space outside the vacuum enclosure. The vacuum enclosure is, for example, a vacuum enclosure of the lithography system or another system (e.g., mask testing system, mask repair system) in which the temperature control device is used. The described features of the extraction unit(s) and / or the gas line(s) can apply to all extraction units and gas lines described herein.

[0053] According to another embodiment, the gas passage unit has a gas-permeable membrane.

[0054] This means that the gas passage unit is designed to allow gas from gas bubbles in the temperature control fluid to pass into the gas space of the secondary line section.

[0055] The membrane is particularly liquid-tight, especially with regard to the temperature control fluid.

[0056] The gas passage unit, designed as a gas-permeable membrane, can be configured to selectively and / or controllably allow gas from gas bubbles in the temperature control fluid to pass from the liquid chamber of the bypass section into the gas chamber of the bypass section. This allows the effective amount of gas in the liquid chamber of the bypass section to be set and / or regulated. This, in turn, allows the compliance of the membrane to be adjusted. In particular, the compliance of the membrane, in the case of a rigid membrane, depends on the amount of gas in the liquid chamber of the bypass section. By regulating and / or setting this amount of gas in the liquid chamber, the bypass section can function as a local gas spring (analogous to a Helmholtz resonator). This allows pressure fluctuations of the temperature control fluid to be, for example, within a desired frequency range (e.g.,...).a frequency range that is not critical for position control of the position-sensitive component.

[0057] For example, the gas bubble separator has a sensor unit for detecting the actual gas pressure of a gas in the gas chamber. Additionally or instead, the gas bubble separator has, for example, another sensor unit for detecting the actual gas quantity in the liquid chamber of the bypass section. Furthermore, the gas bubble separator has, for example, a control unit configured to regulate the gas pressure in the gas chamber and / or the gas quantity in the liquid chamber based on the detected actual gas pressure of the gas in the gas chamber and / or based on the detected actual gas quantity in the liquid chamber. This allows the diaphragm's compliance to be adjusted.

[0058] According to another embodiment, the membrane is elastic. Furthermore, the membrane is designed to dampen pressure fluctuations of the temperature control fluid in the pipe section.

[0059] The elastic membrane can convert the energy of a pressure fluctuation into deformation energy and / or kinetic energy of the membrane's elastic material. Specifically, the elastic membrane is compressed and / or expanded and / or set in motion by an incoming pressure wave.

[0060] The elastic membrane can, for example, also be made of a viscoelastic material. In the case of a viscoelastic material that exhibits both elastic and viscous properties, the energy of the incoming pressure wave can be at least partially dampened by the viscous component. This allows the energy of the incoming pressure wave to be dissipated and the amplitude of the outgoing pressure wave to be reduced.

[0061] The elastic material may contain, for example, polyurethane (PUR), silicone, rubber, natural rubber, silicone rubber, fluororubber, perfluororubber, polynorbornene rubber, perfluoroalcyl vinyl ether, perfluoroalkoxy, polyvinyl chloride, one or more thermoplastic elastomers, a fluorothermoplastic such as tetrafluoroethylene, polytetrafluoroethylene, hexafluoropropylene and / or vinylidene fluoride, and / or another elastic material.

[0062] An elastic diaphragm can also be used as a local gas spring (Helmholtz resonator). In the case of an elastic diaphragm, its compliance depends not only on the amount of gas in the liquid space of the bypass section, but also on the amount of gas in the gas space of the bypass section and on the compliance of the elastic diaphragm itself.

[0063] According to a further embodiment, the gas bubble separator has a control unit for regulating the gas pressure of a gas in the gas space, wherein the control unit is preferably configured to control a suction unit of the gas bubble separator.

[0064] By regulating the gas pressure in the gas space, diffusion (e.g., a diffusion flow) of gas bubbles and / or gas from the gas bubbles from the liquid space into the gas space can be controlled. In other words, regulating the gas pressure in the gas space controls the permeability of the gas passage unit (e.g., the membrane). This means that regulating the gas pressure (and thus the gas content) in the gas space allows for the control of a diffusion flow through the membrane and, consequently, the adjustment of the gas quantity in the liquid space. For example, if irregularities are detected in the position-sensitive component, the gas content in the liquid space can be adjusted by regulating the gas content and thus the diffusion flow. This can, for instance, influence standing waves that form in the liquid space (e.g.,...).shifted to a more favorable frequency range).

[0065] The gas pressure of the gas in the gas space is, for example, a measure of the gas concentration of the gas in the gas space.

[0066] The control unit is designed, for example, to regulate the gas pressure in the gas chamber to a predetermined target gas pressure based on sensor data. The sensor data includes, for example, the actual gas pressure in the gas chamber. Alternatively or additionally, the sensor data can also be used to derive, for example, the actual gas pressure in the gas chamber and / or a deviation of the actual gas pressure from a target gas pressure.

[0067] The control unit is designed, for example, to determine a control variable for controlling the extraction unit and to control the extraction unit based on the determined control variable.

[0068] The control unit is specifically designed to regulate the gas pressure in the gas space based on feedback control. Specifically, the control unit is designed to regulate the gas pressure in the gas space based on a (closed) control loop. The target gas pressure corresponds to a reference variable in the control loop. Additionally, the measured actual gas pressure is fed to the control unit (or a deviation detection unit) as a negative value to determine any deviation between the actual gas pressure and the target gas pressure.

[0069] According to a further embodiment The gas bubble separator has a sensor unit for detecting the actual gas pressure of a gas in the gas space, and the control unit is configured to regulate the gas pressure in the gas space to a predetermined target gas pressure based on the detected actual gas pressure, and / or The control unit is designed to regulate the gas pressure of the gas in the gas space based on position sensor data from a position sensor unit of the position-sensitive component.

[0070] The sensor unit for measuring the actual gas pressure of a gas in the gas space can, for example, also be configured to measure the partial pressures of several gas components within that gas space. From the measured partial pressures, the concentration of a respective gas component and / or the gas content of that respective gas component can be derived.

[0071] The control unit and / or a deviation detection unit is configured, for example, to determine any deviation of the measured actual gas pressure from the target gas pressure (and, if necessary, to transmit the determined deviation to the control unit). Furthermore, the control unit is configured, for example, to determine a manipulated variable for controlling the extraction unit based on the determined deviation.

[0072] In addition to or instead of directly measuring the actual gas pressure in the gas chamber, the control unit can also be configured to regulate the gas pressure in the gas chamber based on position sensor data from a position sensor unit of the position-sensitive component. In other words, position sensor data from an existing position sensor unit used to measure the position of the position-sensitive component can also be used to regulate the gas pressure in the gas chamber and thus the permeability of the gas passage unit. This is because position sensor data from the position sensor unit used to measure the position of the position-sensitive component also indirectly contains information about pressure fluctuations in the temperature control fluid and the gas bubble content of the temperature control fluid.

[0073] In embodiments, the control unit is configured to regulate the gas pressure of the gas in the gas space based on pressure sensor data of an acoustic pressure in the cooling line and / or the line section.

[0074] This means that the control unit – in addition to or instead of directly detecting the actual gas pressure of a gas in the gas space and / or in addition to or instead of based on position sensor data from a position sensor unit of the position-sensitive component – ​​can also be configured to control the gas pressure of the gas in the gas space based on pressure sensor data from a pressure sensor unit that detects an acoustic pressure in the cooling line and / or the line section.

[0075] According to another embodiment, the gas passage unit has a valve (first valve) for allowing gas bubbles to pass through when the valve is open.

[0076] This allows gas bubbles to be collected in the liquid space of the bypass section when the valve is closed, and then transferred to the gas space of the bypass section by opening the valve.

[0077] If an extraction unit is provided, a negative pressure can be created in the gas space so that when the valve is opened, a gas-liquid mixture flows through the valve into the gas space.

[0078] According to another embodiment, the gas bubble separator has an additional sensor unit for detecting the actual amount of gas in the liquid space of the secondary line section.

[0079] This allows the valve to be opened depending on the measured actual amount of gas in the liquid space of the secondary line section.

[0080] The additional sensor unit is designed, for example, to detect the actual amount of gas in the liquid space of the branch line section adjacent to the valve.

[0081] The additional sensor unit includes, for example, an optical sensor unit. This optical sensor unit is configured, for example, to determine the number and / or size of gas bubbles, and thus the quantity of gas, based on light reflected from them (i.e., at the phase boundaries of the gas bubbles). The optical sensor unit can also be configured, for example, to determine the quantity of gas based on absorbed components of the light spectrum, either additionally or instead.

[0082] The additional sensor unit can, for example, also include an ultrasonic sensor unit. This ultrasonic sensor unit is configured, for instance, to emit an ultrasonic signal and determine the gas quantity based on the ultrasonic signal reflected by gas bubbles (ultrasound echo). The frequency of the emitted ultrasonic signal is, for example, different from the frequency range of a position control system of the position-sensitive component (e.g., significantly larger than the frequency range of the position control system).

[0083] Even in the case of a gas bubble separator designed as a membrane, an additional sensor unit can be used, as described above, to detect the actual gas quantity in the liquid chamber of the secondary line section. This allows the gas quantity in the liquid chamber to be regulated in order to adjust the effective compliance of the gas spring formed by the gas chamber, the gas in the liquid chamber, and the elastic membrane.

[0084] According to another embodiment, the gas bubble separator has a further control unit for regulating a quantity of gas in the liquid space of the secondary line section based on the detected actual quantity of gas and by controlling the valve.

[0085] This allows the valve to be controlled depending on the measured actual gas volume in the liquid chamber of the branch line section. Specifically, the valve can be opened if the actual gas volume in the liquid chamber of the branch line section exceeds a predetermined threshold. Alternatively, the gas volume in the liquid chamber of the branch line section can also be regulated to a predetermined target gas volume.

[0086] The additional control unit is designed, for example, to control the valve, e.g., an opening and closing mechanism of the valve.

[0087] According to another embodiment, the gas bubble separator has: a fluid-connected extraction unit for extracting gas from the gas space, and a second valve arranged between the gas space and the extraction unit to maintain a negative pressure generated in the gas space by the extraction unit.

[0088] The first valve of the gas passage unit, which is arranged between the liquid space and the gas space of the secondary line section, and the second valve, which is arranged between the gas space and the extraction unit, together form in particular a lock.

[0089] The gas bubble separator is specifically designed to operate the first and second valves according to the following scheme (e.g., in bistable operation): Initially, the first valve is closed and the second valve is open. The suction unit creates a relative vacuum in the gas space (e.g., relative to a local pressure at one end of the bypass section opposite the main line). Then, the second valve is closed and the first valve is opened. This causes the gas bubbles accumulated in the liquid space of the bypass section to move, driven by the vacuum in the gas space, through the open first valve into the gas space. When the first valve is closed again, the accumulation of gas bubbles in the liquid space of the bypass section can begin anew.

[0090] The extraction unit can also be configured to extract a gas-liquid mixture from the gas space.

[0091] According to another embodiment, the gas bubble separator has: a gas-liquid separation unit for separating a gas-liquid mixture in the gas space, a return line section connecting the gas-liquid separation unit with the fluid line section for returning a liquid separated from the gas-liquid mixture to the line section, and A gas discharge line fluidly connected to the gas-liquid separation unit for the removal of a gas separated from the gas-liquid mixture.

[0092] This allows a liquid separated from the gas-liquid mixture to be returned to the main line (i.e., the section of the liquid line), i.e., fed back in.

[0093] This also has the advantage that, in the case of a valve as a gas passage unit, only a (e.g., pure) gas from the system (e.g., outside a vacuum housing) needs to be discharged through the gas discharge line - and not a gas-liquid mixture.

[0094] According to another embodiment, a third valve is arranged between the return line section and the line section.

[0095] This allows the injection of the liquid separated from the gas-liquid mixture into the pipeline section to be controlled.

[0096] The gas-liquid separation unit is located, in particular, between the second and third valves.

[0097] A second aspect is addressed by proposing a lithography system. This system includes a position-sensitive component and a temperature control device as described above.

[0098] The temperature control device and / or the position-sensitive component is / are preferably part of the projection system of the projection exposure unit. However, the temperature control device and / or the position-sensitive component can / can also be part of a lighting system of the projection exposure unit.

[0099] Another aspect is the proposal for a mask testing system. This system includes a position-sensitive component and a temperature control device as described above.

[0100] Another aspect is the proposal for a mask repair system. This system includes a position-sensitive component and a temperature control device as described above.

[0101] According to a third aspect, a method for operating a temperature control device for a lithography system is proposed. The method comprises the following steps: a) Transporting a temperature control fluid in a fluid line of the temperature control device, wherein the fluid line has a line section with a branch line section, within the branch line section a fluid space and a gas space are formed that are fluidly connected to the line section, and the gas space is connected to the fluid space by means of a gas passage unit for allowing gas bubbles to pass from the fluid space into the gas space, b) Moving one or more gas bubbles from the main pipe section into the liquid space of the secondary pipe section, and c) Allowing gas bubbles to pass from the liquid space through the gas passage unit into the gas space of the secondary line section.

[0102] In embodiments of the third aspect, the method involves regulating the gas pressure of a gas in the gas space.

[0103] In embodiments of the third aspect, a gas passage unit of the temperature control device has a valve for allowing gas bubbles to pass through when the valve is open. Furthermore, in step b), the method includes an accumulation of gas bubbles in the liquid space of the bypass section, and in step c), a passage of gas bubbles from the liquid space through the gas passage unit into the gas space of the bypass section (e.g., when a quantity of gas in the liquid space of the bypass section exceeds a predetermined threshold).

[0104] In embodiments of the third aspect, a gas bubble separator of the temperature control device includes a suction unit fluidly connected to the gas space for extracting gas from the gas space. In addition to the first valve, which is arranged between the liquid space and the gas space of the bypass section, the gas bubble separator also includes a second valve arranged between the gas space and the suction unit for maintaining a negative pressure generated by the suction unit in the gas space. Furthermore, the method in step b) includes: closing the first valve, opening the second valve, and generating a negative pressure in the gas space by means of the suction unit. The method in step c) further includes: closing the second valve, opening the first valve, and moving the gas bubbles from the liquid space of the bypass section through the open first valve into the gas space.Steps b) and c) can be repeated in this order as many times as desired.

[0105] In embodiments of the third aspect, a gas bubble separator of the temperature control device comprises: a gas-liquid separation unit for separating a gas-liquid mixture in the gas space, a return line section fluidly connecting the gas-liquid separation unit to the line section for returning a liquid separated from the gas-liquid mixture to the line section, and a gas discharge line fluidly connected to the gas-liquid separation unit for discharging a gas separated from the gas-liquid mixture. Furthermore, the method comprises, in step c) or after step c), the return of a liquid separated from the gas-liquid mixture to the line section.

[0106] The term "one" here is not necessarily to be understood as restricting the number to exactly one element. Rather, it can also refer to multiple elements, such as two, three, or more. Similarly, every other counter used here should not be interpreted as restricting the number to the exact number stated. Instead, numerical deviations, both higher and lower, are possible unless otherwise specified.

[0107] The embodiments and features described for the temperature control device apply, mutatis mutandis, to the proposed method accordingly and vice versa.

[0108] Other possible implementations of the invention also include combinations of features or embodiments described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In such cases, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0109] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention will be explained in more detail below with reference to preferred embodiments and the accompanying figures. Fig. Figure 1 shows a schematic meridional section of a projection exposure system for EUV projection lithography according to one embodiment; Fig. Figure 2 shows an optical system with an optical component of the projection exposure system. Fig. 1 according to one embodiment; Fig. Figure 3 shows a cooling device for cooling the optical component. Fig. 2 according to one embodiment; Fig. Figure 4 shows an enlarged section IV from Fig. 3 with a pipe section and a gas bubble separator according to an embodiment; Fig. Figure 5 shows a control loop for regulating a gas pressure in a gas space of the gas bubble separator. Fig. 4 according to one embodiment; Fig. 6 shows a similar view Fig. 4 with a pipe section and a gas bubble separator according to a further embodiment; Fig. 7 shows a similar view Fig. 6 with a pipe section and a gas bubble separator according to a further embodiment; and Fig. Figure 8 shows a flow diagram of a method for operating a temperature control device for a lithography system according to one embodiment.

[0110] In the figures, identical or functionally equivalent elements have been labelled with the same reference symbols, unless otherwise indicated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

[0111] Fig. Figure 1 shows an embodiment of a projection exposure system 1 (lithography system), in particular an EUV lithography system. One embodiment of the illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optic 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system 2. In this case, the illumination system 2 does not include the light source 3.

[0112] A reticule 7 arranged in the object field 5 is exposed. The reticule 7 is held by a reticule holder 8. The reticule holder 8 can be moved, particularly in a scanning direction, via a reticule displacement drive 9.

[0113] In the Fig. Figure 1 shows a Cartesian coordinate system with an x-direction x, a y-direction y, and a z-direction z. The x-direction x runs perpendicular to the plane of the drawing. The y-direction y runs horizontally, and the z-direction z runs vertically. The scan direction runs in the Fig. 1 along the y-direction y. The z-direction z runs perpendicular to the object plane 6.

[0114] The projection exposure system 1 comprises a projection optic 10. The projection optic 10 serves to image the object field 5 onto an image field 11 in an image plane 12. The image plane 12 is parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0115] A structure on the reticulum 7 is imaged onto a photosensitive layer of a wafer 13 located in the image plane 12 within the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be moved, particularly along the y-direction y, via a wafer transfer drive 15. The movement of the reticulum 7 via the reticulum transfer drive 9 and of the wafer 13 via the wafer transfer drive 15 can be synchronized.

[0116] Light source 3 is an EUV radiation source. Light source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation 16 has a wavelength in the range between 5 nm and 30 nm. Light source 3 can be a plasma source, for example, an LPP source (Laser Produced Plasma) or a DPP source (Gas Discharged Produced Plasma). It can also be a synchrotron-based radiation source. Light source 3 can be a free-electron laser (FEL).

[0117] The illumination radiation 16 emanating from the light source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloid reflective surfaces. The at least one reflective surface of the collector 17 can be illuminated by the illumination radiation 16 at grazing incidence (GI), i.e., with angles of incidence greater than 45°, or at normal incidence (NI), i.e., with angles of incidence less than 45°. The collector 17 can be structured and / or coated to optimize its reflectivity for the useful radiation and to suppress stray light.

[0118] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optics 4.

[0119] The illumination optics 4 comprise a deflecting mirror 19 and, downstream in the beam path, a first faceted mirror 20. The deflecting mirror 19 can be a planar deflecting mirror or, alternatively, a mirror with an effect that influences the beam shape beyond the mere deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first faceted mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6 as the field plane, it is also referred to as a field faceted mirror. The first faceted mirror 20 comprises a plurality of individual first facets 21, which can also be referred to as field facets. Of these first facets 21, the following are in the Fig. 1 only some examples are shown.

[0120] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or semicircular border contour. The first facets 21 can be designed as planar facets or alternatively as convexly or concavely curved facets.

[0121] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 can themselves each be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can in particular be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

[0122] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction y.

[0123] In the beam path of the illumination optics 4, a second faceted mirror 22 is arranged downstream of the first faceted mirror 20. If the second faceted mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil faceted mirror. The second faceted mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first faceted mirror 20 and the second faceted mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1, and US 6,573,978.

[0124] The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0125] The second facets 23 can also be macroscopic facets, which may, for example, have round, rectangular, or hexagonal edges, or alternatively, facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0126] The second facets 23 can have planar or alternatively convex or concave curved reflective surfaces.

[0127] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (English: Fly's Eye Integrator).

[0128] It can be advantageous not to arrange the second faceted mirror 22 exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the second faceted mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0129] With the aid of the second faceted mirror 22, the individual first facets 21 are imaged into the object field 5. The second faceted mirror 22 is the last beam-shaping, or indeed the last, mirror for the illumination radiation 16 in the beam path before the object field 5.

[0130] In another embodiment of the illumination optics 4, not shown, a transmission optic can be arranged in the beam path between the second facet mirror 22 and the object field 5, which contributes in particular to imaging the first facets 21 into the object field 5. The transmission optic can have exactly one mirror, or alternatively two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optic can in particular comprise one or two mirrors for normal incidence (NI mirrors) and / or one or two mirrors for grazing incidence (GI mirrors).

[0131] The lighting optics 4, in the version shown in the Fig. Figure 1 shows exactly three mirrors after the collector 17, namely the deflecting mirror 19, the first faceted mirror 20 and the second faceted mirror 22.

[0132] In a further embodiment of the lighting optics 4, the deflecting mirror 19 can also be omitted, so that the lighting optics 4 after the collector 17 can then have exactly two mirrors, namely the first faceted mirror 20 and the second faceted mirror 22.

[0133] The mapping of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optic into the object plane 6 is regularly only an approximate mapping.

[0134] The projection optics 10 comprise a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0135] In the Fig. In the example shown, the projection optics 10 comprise six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The projection optics 10 is a doubly obscured optic. The penultimate mirror M5 and the last mirror M6 each have an aperture for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0136] The reflective surfaces of the mirrors Mi can be designed as freeform surfaces without an axis of rotational symmetry. Alternatively, the reflective surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflective surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0137] The projection optics 10 has a large object-image offset in the y-direction y between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction y can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

[0138] The projection optics 10 can be anamorphic. In particular, they have different magnifications βx, βy in the x and y directions. The two magnifications βx, βy of the projection optics 10 are preferably (βx, βy) = (+ / - 0.25, + / - 0.125). A positive magnification β indicates a projection without image inversion. A negative magnification β indicates a projection with image inversion.

[0139] The projection optics 10 thus lead to a reduction in the x-direction x, that is, in the direction perpendicular to the scan direction, in a ratio of 4:1.

[0140] The projection optics 10 lead to a reduction of 8:1 in the y-direction y, that is, in the scan direction.

[0141] Other magnification ratios are also possible. Magnification ratios with the same sign and absolute value in the x and y directions (x, y), for example with absolute values ​​of 0.125 or 0.25, are also possible.

[0142] The number of intermediate image planes in the x and y directions x, y in the beam path between the object field 5 and the image field 11 can be the same or, depending on the design of the projection optics 10, different. Examples of projection optics with different numbers of such intermediate images in the x and y directions x, y are known from US 2018 / 0074303 A1.

[0143] Each of the second facets 23 is assigned to exactly one of the first facets 21 to form an illumination channel for illuminating the object field 5. This can result, in particular, in illumination according to Köhler's principle. The far field is divided into a multitude of object fields 5 with the help of the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to each of them.

[0144] The first facets 21 are each superimposed on a corresponding second facet 23 to illuminate the object field 5 on the reticle 7. The illumination of the object field 5 is particularly homogeneous. It preferably exhibits a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0145] The illumination of the entrance pupil of the projection optics 10 can be geometrically defined by arranging the second facets 23. By selecting the illumination channels, in particular the subset of the second facets 23 that carry light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting or illumination pupil filling.

[0146] Another preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by a redistribution of the illumination channels.

[0147] Further aspects and details of the illumination of the object field 5 and, in particular, the entrance pupil of the projection optics 10 are described below.

[0148] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0149] The entrance pupil of the projection optics 10 cannot be precisely illuminated by the second faceted mirror 22. When the projection optics 10 image the center of the second faceted mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found where the pairwise determined separation of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in real space. In particular, this surface exhibits a finite curvature.

[0150] The projection optics 10 may have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second faceted mirror 22 and the reticle 7. This optical element can accommodate the different positions of the tangential and sagittal entrance pupils.

[0151] During the Fig. In the arrangement of the components of the illumination optics 4 shown in Figure 1, the second faceted mirror 22 is arranged in a plane conjugate to the entrance pupil of the projection optics 10. The first faceted mirror 20 is arranged tilted relative to the object plane 6. The first faceted mirror 20 is arranged tilted relative to an arrangement plane defined by the deflecting mirror 19. The first faceted mirror 20 is arranged tilted relative to an arrangement plane defined by the second faceted mirror 22.

[0152] Fig. Figure 2 shows an optical system 100 with an optical component 102 (as an example of a position-sensitive component) according to an embodiment.

[0153] The optical component 102 is, for example, a mirror of the projection exposure system 1 (lithography system), in particular of the projection optics 10, made of Fig. 1. The optical component 102 is, for example, one of the mirrors M1 to M6. In the following, the position-sensitive component 102 is described as a mirror; however, in other examples, it may also be a different optical or mechanical component of the projection exposure system 1 than a mirror.

[0154] As in Fig. As shown in Figure 2, the mirror 102 comprises a coating 104 with an optically active surface 106. The mirror 102 also comprises a substrate 108. Cooling lines 110 are arranged in the substrate 108, through which a cooling fluid 112, such as water, is circulated to actively cool the mirror 102. Cooling the mirror 102 serves to prevent thermal deformations of the mirror 102, for example, when exposed to high-energy EUV radiation 16 ( Fig. 1) to avoid.

[0155] The mirror 102 is movably attached to a support frame 116 by means of an actuator assembly 114. The actuator assembly 114 comprises, for example, several actuators 118 and a drive unit (not shown). The actuator assembly 114 serves, for example, to move the mirror 102 with respect to six degrees of freedom (translation in the x, y, and z directions and rotation about the x, y, and z directions). Fig. 2) to position.

[0156] The optical system 100 further includes a sensor device 120 for detecting the current position of the mirror 102. The sensor device 120 is in Fig. 2 is only shown schematically. The sensor device 120 has one or more sensors, such as interferometers. The sensors of the sensor device 120 are, for example, attached to a sensor frame (not shown). The sensor frame is, for example, vibration-isolated from the support frame 116. For example, the current position of the mirror 102 is detected using laser beams 122. The sensor device 120 is, for example, configured to detect the position of the mirror 102 in its six degrees of freedom.

[0157] In Fig. Figure 3 shows a cooling device 200 (as an example of a temperature control device) for cooling a position-sensitive component 102 (e.g., the mirror 102). The cooling device 200 has a cooling circuit 202. The cooling device 200 comprises a cooling unit 204 for cooling a coolant 206 and a fluid line 208 (cooling line 208) for transporting the coolant 206. The cooling device 200 also includes one or more pumps 210 for generating a required coolant flow rate of the coolant 206. The cooling device 200 further includes one or more valves 212 for controlling the coolant flow.

[0158] Although not shown in the figures, the cooling device 200 can also be used to cool several position-sensitive components 102 of the lithography system 1.

[0159] Pumps of the cooling device 200, such as pump 210, cause local pressure fluctuations in the coolant 206. These pressure fluctuations are transmitted throughout the entire cooling circuit 202 via longitudinal fluid sound waves. Furthermore, changes in cross-sectional area (not shown) of the cooling line 208, bends 214 of the cooling line 208, and valves 212 of the cooling device 200 can also be sources of disturbance that cause local pressure fluctuations in the coolant 206. Such acoustic disturbances are transmitted via fluid sound to the cooled position-sensitive component 102 (e.g., the mirror 102). This can lead to an undesired change in the position of the position-sensitive component 102.

[0160] Gas bubbles 216 can also be transported in the coolant 206. These gas bubbles can form, for example, through leaks at connection points of the cooling line 208, through outgassing due to supersaturation, or through other mechanisms. Such gas bubbles 216, especially phase boundaries of the gas bubbles 216, represent a reflective surface for pressure waves of the coolant 206. Reflections of the pressure wave at one or more gas bubbles 216 can generate standing pressure waves with local pressure maxima, for example, in the position-sensitive component 102. To prevent this, a gas bubble separator 220 is provided on a line section 218. The gas bubble separator 220 serves to separate gas bubbles 216 from the coolant 206 of the line section 218. The reference numeral S in Fig. 3 denotes a flow direction of the coolant 206 in the pipe section 218.

[0161] As in Fig. As shown in Figure 3, the gas bubble separator 220 has a branch line section 222 extending from the main line section 218. Within the branch line section 222, a liquid chamber 224 and a gas chamber 226 are formed. The liquid chamber 224 of the branch line section 222 is fluidly connected to the main line section 218 of the cooling line 208. A gas passage unit 228 is arranged between the liquid chamber 224 and the gas chamber 226 of the branch line section 222. In particular, the gas chamber 226 is connected to the liquid chamber 224 by means of the gas passage unit 228. The gas passage unit 228 is designed to allow gas bubbles 216 to pass from the liquid chamber 224 into the gas chamber 226.

[0162] In Fig. 4 is an enlarged section IV from Fig. 3 shown.

[0163] The gas passage unit 228, for example, has a membrane 230 which is gas-permeable and liquid-tight.

[0164] The branch line section 222 is separated from the line section 218 with respect to a direction of the acceleration due to gravity or a direction of a gravitational force F associated with the acceleration due to gravity. G for example, arranged in ascending order, as in Fig. Figure 3 shows that in this case, the branch line section 222 can also be referred to as a riser. In the examples shown in the figures, an angle α ( Fig. 4) a right angle (i.e., a 90° angle) exists between the main line section 218 and the branch line section 222. In other examples, the angle α between the main line section 218 and the branch line section 222 may also be a non-right angle. In the case of a branch line section 222 that is separated from the main line section 218 with respect to the direction of gravity F G Arranged in an ascending order, gas bubbles 216 are formed due to a buoyant force F. A ( Fig. 4) transported from pipe section 218 into the liquid space 224 of the branch pipe section 222.

[0165] In other examples, other physical and / or chemical mechanisms may also be used – in addition to or instead of a buoyant force F. A to ensure the transport of gas bubbles 216 from line section 218 into the liquid space 224 of the branch line section 222.

[0166] Although not shown in the figures, the branch line section 222 - instead of being an elongated branch line section 222 - could also simply be a bulge, e.g. a dome-shaped bulge and / or a chamber.

[0167] As in Fig. As shown in Figure 4, the gas bubble separator 220 can also include a suction unit 232 for extracting gas 216' from the gas space 226 of the secondary line section 222. The suction unit 232 includes, for example, a gas line 234 fluidly connected to the gas space 226. The suction unit 232 also includes, for example, a pump 236 arranged on the gas line 234. With the aid of the pump 236, gas 216' can be discharged from the gas space 226 through the gas line 234. As shown in Fig. As schematically indicated in Figure 4, gas 216' can, for example, escape outside a vacuum housing 238 of the lithography system 1 ( Fig. 1) be taken away.

[0168] The gas bubble separator 220 can optionally include a control unit 240. The control unit 240 is configured, for example, to regulate the gas pressure P of a gas 216' in the gas chamber 226. For example, the gas bubble separator 220 includes a sensor unit 242 for detecting the actual gas pressure P.IST in gas chamber 226. The reference sign A in Fig. 4 identifies sensor data from sensor unit 242, which is transmitted to control unit 240. Furthermore, control unit 240 is configured, for example, to adjust the gas pressure P in gas space 226 based on the measured actual gas pressure P. IST and a predetermined target gas pressure P SOLL to regulate. Furthermore, the control unit 240 is configured to regulate the gas pressure P of the gas 216' in the gas space 226 by controlling the extraction unit 232, e.g., the pump 236. The reference numeral B in Fig. 4 denotes a control signal that is transmitted from the control unit 240 to the extraction unit 232 to control the extraction unit 232.

[0169] In Fig. Figure 5 illustrates a control loop, for example, for controlling a gas pressure P and / or a partial pressure P of a gas 216' in the gas space 226. Fig. The reference symbol r(t) denotes a reference variable of the control loop 300. The reference variable r(t) corresponds to the setpoint gas pressure P. SOLL of gas 216' in gas space 226. The target value r(t), P SOLL The controlled variable can be a time-dependent quantity t or a time-constant quantity. The reference symbol y(t) denotes a controlled variable as a function of time t within control loop 300. The controlled variable y(t) corresponds to the determined actual gas pressure P. IST of gas 216' in gas space 226.

[0170] The control unit 240, 302 ( Fig. 5) or a deviation detection unit 304 is configured to detect a deviation e(t) of the actual gas pressure P IST , y(t) of the predetermined target gas pressure P SOLL, to determine r(t). Furthermore, the control unit 240, 302 is configured to determine a manipulated variable u(t) based on the determined deviation e(t). The manipulated variable u(t) is used to adjust the gas pressure P in the gas chamber 226.

[0171] Reference number 306 in Fig. 5 designates a controlled system of the control loop 300. The controlled system 306 includes a sensor 308 (e.g., the sensor unit 242 in Fig. 4) to determine the actual gas pressure P IST , y(t). The control loop 306 also includes an actuator 310 (e.g. the extraction unit 232 in Fig. 4) for adjusting the gas pressure P of a gas 216' in the gas space 226. The control section 306 also includes the gas space 226 in which the gas pressure P is regulated.

[0172] Additionally or instead of being based on sensor data A of the sensor unit 242 of the gas bubble separator 220, a gas pressure P of a gas 216' in the gas space 226 of the gas bubble separator 220 can also be controlled based on position sensor data C ( Fig. 4) which are carried out by a position sensor unit (e.g. the sensor device 120 in Fig. 2) the position-sensitive component 102 is detected. In other examples (not shown), the gas pressure P of the gas 216' in the gas space 226 can also be controlled based on pressure sensor data, which indicate an acoustic pressure of the coolant 206 in the cooling line 208 and / or the line section 218.

[0173] Optionally, the gas bubble separator 220 can be installed in Fig. 4 also includes a second sensor unit 242' for detecting the actual gas quantity in the liquid space 224 of the branch line section 222. The second sensor unit 242' is, for example, designed similarly to the one described below in connection with Fig. 6 described sensor unit 442. In this case, the control unit 240 or another control unit not shown can be configured to control a quantity of gas in the liquid space 224 based on the detected actual quantity of gas in the liquid space 224.

[0174] By regulating the gas pressure (and thus the amount of gas) in the gas space 226 and the amount of gas in the liquid space 224, an effective compliance of the secondary line section 222 can be set, taking into account the elasticity of the membrane 230.

[0175] The membrane 230, as an example of a gas passage unit 228, can optionally also be an elastic membrane 244 ( Fig. 4) which is designed to dampen pressure fluctuations of the coolant 206 in the pipe section 218.

[0176] In Fig. Figure 6 shows a further embodiment of a gas bubble separator 420 of the cooling device 200. The main differences from the embodiment in Figure 6 are described below. Fig. 4 described.

[0177] The gas bubble separator 420 in Fig. 6 The gas passage unit 428 has a valve 430. In an open state, the valve 430 is configured to allow gas bubbles 416 from a liquid chamber 424 to pass into a gas chamber 426 of a branch line section 422 of the gas bubble separator 420. In the embodiment shown Fig. 6. In its open state, valve 430 allows not only gas bubbles 416 (or gas from the gas bubbles 416) to pass through, but also, to a lesser extent, the coolant 206. It can also be said that in the open state of valve 430, a gas-liquid mixture 444 is transported from the liquid chamber 424 to the gas chamber 426.

[0178] Similar to in Fig. 4 can also be the gas bubble separator 420 in Fig. 6 have a suction unit 432 with a gas line 434 and a pump 436.

[0179] Furthermore, the gas bubble separator 420 can be used in Fig. 6 (and any other gas bubble separator described herein 220, 520, see Fig. 4, Fig. 7) a further sensor unit 442 for detecting a gas quantity M (actual gas quantity M) IST) in the liquid chamber 424 of the branch line section 422. In particular, the sensor unit 442 is designed to detect the quantity of gas M contained in the gas bubbles 416 which are located in the liquid chamber 424 (e.g., have accumulated there). This allows the effective compliance of a gas spring implemented by the gas bubble separator 420 to be adjusted.

[0180] Optionally, the gas bubble separator 420 can also include an additional control unit 440. This additional control unit 440 is, for example, a control unit 440', which is configured to control the gas quantity M in the liquid chamber 424 of the branch line section 422. The control unit 440' is specifically designed to control the gas quantity M based on the measured actual gas quantity M. IST set up. The reference D in Fig. 6 identifies sensor data acquired by the additional sensor unit 442, which is transmitted to the additional control unit 440, e.g., to the control unit 440'. If the control unit 440' determines, for example, that the actual gas quantity M IST greater than a predetermined threshold M S If the gas quantity M is specified, then the control unit 440' can be configured to control valve 430, e.g., an opening and closing mechanism of valve 430, to open. The reference numeral E in Fig. 6 denotes a control signal that is transmitted to valve 430 to control valve 430.

[0181] In other examples, the additional control unit 440 can also be a control unit 440" which is configured to control the gas quantity M in the liquid space 424 of the secondary line section 422 based on the detected actual gas quantity M ISTand to regulate a target gas quantity. This regulation can be implemented based on a control loop, which is similar to the one in Fig. The control loop 300 shown in section 5 is shown.

[0182] Optionally, the gas bubble separator 420 can also have a second valve 446, as shown in Fig. Figure 6 shows the second valve 446 being located between the gas chamber 426 and the extraction unit 432, e.g., the gas line 434 of the extraction unit 432. The second valve 446 controls the flow of gas and / or the flow of the gas-liquid mixture 444 from the gas chamber 426 to the extraction unit 432. The first valve 430 and the second valve 446 together form, in particular, a valve for expelling the gas 416' from the gas bubbles 416 from the liquid chamber 424 into the gas chamber 426 and to the extraction unit 432.

[0183] The separation of gas bubbles 416 from the line section 218 can be carried out using the two valves 430 and 446 as follows. In the first operating state, the first valve 430 is closed and the second valve 446 is open. The gas bubbles 416 cannot pass through the first valve 430 and therefore collect in the liquid chamber 424 of the branch line section 422 adjacent to the valve 430. In the first operating state, the suction unit 432 creates a relative vacuum in the gas chamber 426. Then, in the second operating state, the second valve 446 is closed and the first valve 430 is opened. Driven by the vacuum in the gas chamber 426, the gas bubbles 416 that have accumulated in the liquid chamber 424 of the branch line section 422 now move through the open first valve 430 into the gas chamber 426.The gas 416' originating from the gas bubbles 416 in the gas space 426 cannot pass through the second valve 446 in the second operating state. Following the second operating state, the first operating state is repeated, i.e., the first valve 430 is closed again and the second valve 446 is opened again. This allows the accumulation of gas bubbles 416 in the liquid space 424 of the branch line section 422 to begin again, while simultaneously a negative pressure is created again in the gas space 426 by means of the suction unit 432.

[0184] In Fig. 7 is a variant of the embodiment of the gas bubble separator 420 made of Fig. 6 shown. The following essentially describes the differences from the embodiment in Fig. 6 described.

[0185] The gas bubble separator 520 in Fig. 7, similar to the gas bubble separator 420, also has a branch line section 522, which branches off from the line section 218 of the cooling line 208. The branch line section 522, similar to the gas bubble separator 420, also has a liquid chamber 524, a gas chamber 526, and a gas passage unit 528 in the form of a valve 530 (first valve 530) connecting the liquid chamber 524 with the gas chamber 526.

[0186] In contrast to gas bubble separator 420, gas bubble separator 520 features in Fig. 7 a gas-liquid separation unit 546. The gas-liquid separation unit 546 is designed to separate the gas-liquid mixture 544 (which contains gas 516' from the gas bubbles 516) from the gas space 526. The gas-liquid separation unit 546 is specifically designed to separate the gas-liquid mixture 544 into a liquid 550 and a gas 516".

[0187] The gas bubble separator 520 also has a return line section 548. The return line section 548 connects the gas-liquid separation unit 546 to the line section 218 (fluid connection). The return line section 548 is designed to return the liquid 550 separated from the gas-liquid mixture 544 to the line section 218. The reference numeral S' in Fig. 7 indicates a flow direction of the liquid 550 in the return line section 548.

[0188] The gas bubble separator 520 also has a gas discharge line 552 for discharging the gas 516" separated from the gas-liquid mixture 544.

[0189] As in Fig. As shown in Figure 7, the gas bubble separator 520 can have a third valve 554, which is arranged between the return line section 548 and the line section 218. The third valve 554 can be used to control the injection of the liquid 550 separated from the gas-liquid mixture 544 into the line section 218.

[0190] Although in Fig. Not shown in section 7, the gas bubble separator 520 can be found in Fig. 7 - similar to the gas bubble separator 420 in Fig. 6 - also include a suction unit 432 and / or another control unit 440.

[0191] Each of the temperature control devices 200 (e.g. cooling device) and / or each of the gas bubble separation devices 220, 420, 520 described herein can, for example, also be used in a DUV lithography system, a mask repair system, a mask testing system or another suitable optical system.

[0192] The following refers to Fig. 8 a method for operating a cooling device 200 (as an example of a temperature control device) for a lithography system 1 (or e.g. also a mask repair system or a mask testing system) according to an embodiment is described.

[0193] In a first step S1 of the procedure, a coolant 206 is introduced into a cooling line 208 of the cooling device 200 ( Fig. 3) transported (e.g., to or from a position-sensitive component 102). The cooling line 208 has a line section 218 with a branch line section 222. Within the branch line section 222, a fluid chamber 224 and a gas chamber 226 are formed, which are fluidly connected to the line section 218. The gas chamber 226 is separated from the fluid chamber 224 by means of a gas passage unit 228 (e.g., a membrane 230 in Fig. 3, Fig. 4 or a valve 430 in Fig. 6) connected.

[0194] In a second step S2 of the process, gas bubbles 216 are transported from the line section 218 into the liquid space 224 of the branch line section 222 (e.g. driven by a buoyancy force F). A and / or using another mechanism).

[0195] In a third step S3 of the process, gas bubbles 216 from the liquid space 224 are allowed to pass through the gas passage unit 228 into the gas space 226 of the secondary line section 222.

[0196] Steps S2 and / or S3 can be adapted accordingly and carried out using any of the gas bubble separators 220, 420, 520 described herein.

[0197] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. REFERENCE MARK LIST 1 Projection exposure system 2 Lighting system 3 light source 4 Lighting optics 5 object field 6 Object level 7 reticles 8 label holders 9 Reticle displacement drive 10 Projection optics 11 Image field 12 Image plane 13 wafers 14 wafer holders 15 wafer transfer drive 16 Lighting radiation 17 Collector 18 Intermediate focus plane 19 deflecting mirrors 20 first faceted mirror 21 first facet 22 second faceted mirror 23 second facet 100 optical system 102 optical components 104 Coating 106 area 108 Substrat 110 Cooling line 112 Coolant 114 Actuator setup 116 support frames 118 Actuator 120 sensor device 122 Laser beam 200 cooling device 202 Cooling circuit 204 Cooling unit 206 Coolant 208 Cooling line 210 pump 212 Valve 214 Deflection 216, 216' Gas bubble 218 Line section 220 Gas bubble separator 222 Branch line section 224 Liquid space 226 Gas chamber 228 Gas passage unit 230 Membran 232 Extraction unit 234 Gas pipeline 236 Pump 238 vacuum housings 240 control unit 242, 242' Sensor unit 244 Elastic membrane 300 control loop 302 Control unit 304 Deviation Determination Unit 306 Control section 308 Sensors 310 Actuators 416, 416' Gas bubble 420 Gas bubble separator 422 Branch line section 424 Liquid space 426 Gas chamber 428 Gas passage unit 430 valve 432 Extraction unit 434 Gas pipeline 436 Pump 440,440',440'' Control unit 442 Sensor unit 444 Gas-liquid mixture 446 Valve 516 Gas bubble 516',516'' Gas 520 Gas bubble separator 522 Branch line section 524 Liquid space 526 Gas chamber 528 Gas passage unit 530 valve 544 Gas-liquid mixture 546 Gas-liquid separation unit 548 Return line section 550 liquid 552 Gas discharge pipe 554 Valve α angle A sensor data B Control signal C Position sensor data D Sensor data E control signal e(t) deviation F A Buoyancy force F G Gravity M Gas quantity M1-M6 mirrors M IST Actual gas quantity M S threshold P print P IST Actual gas pressure P SOLL Target gas pressure r(t) reference variable S, S' Flow direction S1-S3 Process step t time u(t) Control variable y(t) controlled variable QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2021 013 441 A1

[0005] DE 10 2008 009 600 A1 [0121, 0125] US 2006 / 0132747 A1

[0123] EP 1 614 008 B1

[0123] US 6,573,978

[0123] DE 10 2017 220 586 A1

[0128] US 2018 / 0074303 A1

[0142]

Claims

Temperature control device (200) for temperature control of a position-sensitive component (102) of a lithography system (1), comprising a liquid line (208) with a line section (218) for transporting a temperature control liquid (206), and a gas bubble separation device (220) with a branch line section (222) branching off from the line section (218), wherein within the branch line section (222) a fluid-connected liquid space (224) and a gas space (226) are formed, and the gas space (226) is connected to the liquid space (224) by means of a gas passage unit (228) for allowing gas bubbles (216) to pass from the liquid space (224) into the gas space (226). Temperature control device according to claim 1, wherein the auxiliary line section (222) is arranged ascending from the line section (218) with respect to gravity (FG). Temperature control device according to claim 1 or 2, wherein the gas bubble separator (220) has a suction unit (232) for suctioning gas (216') from the gas space (226). Temperature control device according to one of claims 1 to 3, wherein the gas passage unit (228) has a gas-permeable membrane (230). Temperature control device according to claim 4, wherein the membrane (230, 244) is elastic and is designed to dampen pressure fluctuations of the temperature control fluid (206) in the line section (218). Temperature control device according to one of claims 1 to 5, wherein the gas bubble separator (220) has a control unit (240) for controlling a gas pressure (P) of a gas (216') in the gas space (226), wherein the control unit (240) is preferably configured to control a suction unit (232) of the gas bubble separator (220). Temperature control device according to claim 6, wherein the gas bubble separator (220) has a sensor unit (242) for detecting an actual gas pressure (PIST) of a gas (216') in the gas space (226), and the control unit (240) is configured to control the gas pressure (P) in the gas space (226) based on the detected actual gas pressure (PIST) to a predetermined target gas pressure (PSOLL), and / or the control unit (240) is configured to control the gas pressure (P) of the gas (216') in the gas space (226) based on position sensor data (C) of a position sensor unit (120) of the position-sensitive component (102). Temperature control device according to one of claims 1 to 3, wherein the gas passage unit (428) has a valve (430) for allowing gas bubbles (416) to pass through in an open state of the valve (430). Temperature control device according to one of claims 1 to 8, wherein the gas bubble separator (420) has a further sensor unit (442) for detecting an actual amount of gas (MIST) in the liquid space (424) of the secondary line section (422). Temperature control device according to claim 9, wherein the gas bubble separator (420) has a further control unit (440) for controlling a quantity of gas (M) in the liquid space (424) of the bypass section (422) based on the detected actual quantity of gas (MIST) and by actuating the valve (430). Temperature control device according to one of claims 8 to 10, wherein the gas bubble separator (420) comprises a suction unit (432) fluidly connected to the gas space (426) for suctioning gas (416') from the gas space (426), and a second valve (446) arranged between the gas space (426) and the suction unit (432) for maintaining a negative pressure generated by the suction unit (432) in the gas space (426). Temperature control device according to one of claims 8 to 11, wherein the gas bubble separator (520) comprises a gas-liquid separation unit (546) for separating a gas-liquid mixture (544) in the gas space (526), ​​a return line section (548) fluid-connecting the gas-liquid separation unit (546) to the line section (218) for returning a liquid (550) separated from the gas-liquid mixture (544) to the line section (218), and a gas discharge line (552) fluid-connected to the gas-liquid separation unit (546) for discharging a gas (516") separated from the gas-liquid mixture (544). Temperature control device according to claim 12, wherein a third valve (554) is arranged between the return line section (548) and the line section (218). Lithography system (1) with a position-sensitive component (102) and a temperature control device (200) according to one of claims 1 to 13 for temperature control of the position-sensitive component (102). Method for operating a temperature control device (200) for a lithography system (1), comprising: a) transporting (S1) a temperature control fluid (206) in a fluid line (208) of the temperature control device (200), wherein the fluid line (208) has a line section (218) with a branch line section (222) therefrom, within the branch line section (222) a fluid chamber (224) and a gas chamber (226) are formed fluidly connected to the line section (218), and the gas chamber (226) is connected to the fluid chamber (224) by means of a gas passage unit (228) for allowing gas bubbles (216) to pass from the fluid chamber (224) into the gas chamber (226), b) moving (S2) gas bubbles (216) from the line section (218) into the fluid chamber (226) of the Branch line section (222),and c) Passing (S3) gas bubbles (216) from the liquid space (226) through the gas passage unit (228) into the gas space (226) of the branch line section (222).

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