Temperature control system, lithography apparatus, and method for temperature control of objects

Abstract

The present invention provides a temperature conditioning system that uses a conditioning fluid to condition a temperature of an object, the temperature conditioning system including a conditioning conduit, a return conduit, a supply chamber and an exhaust chamber, arranged to provide a static pressure differential between a supply chamber outlet and an exhaust chamber inlet to create a flow through the conditioning conduit. A lithographic apparatus and a method for conditioning the temperature of an object are also described.

Description

Technical Field

[0001] Cross-reference to Related Applications

[0001] This application claims priority to European Patent Application No. 21169681.0 filed on April 21, 2021, European Patent Application No. 21178831.0 filed on June 10, 2021, and European Patent Application No. 21209310.8 filed on November 19, 2021, the entire contents of which are incorporated herein by reference.

[0002]

[0002] The present invention relates to a temperature control system, a lithography apparatus, and a method for temperature-controlling an object.

Background Art

[0003]

[0003] A lithography apparatus is a machine constructed to apply a desired pattern onto a substrate. The lithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). The lithography apparatus can, for example, project a pattern on a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) provided on the substrate.

[0004]

[0004] To project a pattern onto a substrate, a lithography apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. A lithography apparatus that uses extreme ultraviolet (EUV) radiation having a wavelength in the range of 4 to 20 nm (e.g., 6.7 nm or 13.5 nm) can be used to form smaller features on a substrate than a lithography apparatus that uses radiation having a wavelength of 193 nm, for example.

[0005]

[0005] As the demand for focus and overlay in the lithography process increases, the stability of critical objects in lithography is becoming increasingly important. These critical objects include, for example, the mirror elements of the projection system of a lithography apparatus. Object stability relates to dealing with the position of the object (such as object vibration) and temperature effects (such as deformation due to thermal stress of the object (critical object)).

[0006]

[0006] Mirror elements are used in projection systems to reflect a patterned radiation beam. This reflection results in a substantial thermal load of the radiation beam on the mirror elements. This thermal load can generate internal thermal stress that leads to deformation of the mirror elements. In known embodiments of lithography apparatus, preheating systems are used to control thermal stress by adjusting the temperature of objects such as mirror elements. These preheating systems do not always provide sufficient temperature control of the mirror elements.

[0007]

[0007] Alternatively, temperature control using a regulating fluid is used to control the temperature of one or more objects in a lithography apparatus. Such temperature control includes at least one regulating conduit (usually a network of regulating conduits) that extends through or along the object whose temperature is to be regulated. The temperature control system includes a tank that holds a relatively large amount of regulating fluid at a predetermined temperature and a pump for pumping the regulating fluid through at least one regulating conduit.

[0008]

[0008] A drawback of the temperature control system is that the pumping action of the pump generates pressure fluctuations that propagate through the control fluid. These pressure fluctuations can cause vibrations in the object to be controlled. These fluid-induced vibrations in the object (e.g., vibrations of the mirror elements in a projection system) can adversely affect the focus and / or overlay performance of the lithography apparatus. A further drawback is that the pressure of the control fluid affects the deformation of the surface shape of the mirror elements, which can further adversely affect the focus and / or overlay performance of the lithography apparatus. Another cause of pressure fluctuations in the liquid is the acceleration of a portion of the liquid system caused by vibrations of the mechanical parts to which the fluid components are attached and / or vibrations of the floor. [Overview of the Initiative]

[0009]

[0009] An object of the present invention is to provide a thermal control system for thermally controlling an object, specifically a thermal control system using a control fluid, which can substantially reduce flow-induced vibrations within the object caused by pressure fluctuations in the flow of a control fluid. A further object of the present invention is to provide such a thermal control system for use in a lithography apparatus and a method for temperature-controlling an object using a control fluid in a temperature control system.

[0010]

[0010] According to an aspect of the present invention, a temperature control system that uses a regulating liquid to regulate the temperature of an object, A regulating conduit for guiding a regulating fluid through or along an object, comprising a regulating conduit inlet and a regulating conduit outlet, A return conduit having a return conduit inlet and a return conduit outlet, A supply chamber having a supply chamber inlet connected to a return conduit outlet and a supply chamber outlet connected to a control conduit inlet, A discharge chamber having a discharge chamber inlet connected to a control conduit outlet and a discharge chamber outlet connected to a return conduit inlet. Includes, A temperature control system is provided, which is positioned to create a static pressure difference between the supply chamber outlet and the discharge chamber inlet to generate flow through a regulating conduit.

[0011]

[0011] In earlier embodiments of the present invention, the first pressure in the supply chamber and the second pressure in the discharge chamber are maintained at a pressure level lower than atmospheric pressure.

[0012]

[0012] According to an aspect of the present invention, a lithography apparatus is provided which includes a temperature control system for using a regulating liquid to regulate the temperature of an object, wherein the object is part of the lithography apparatus.

[0013]

[0013] According to an aspect of the present invention, a method for controlling the temperature of an object using a temperature control liquid in a temperature control system, wherein the temperature control system is A regulating conduit for guiding a regulating fluid through or along an object, comprising a regulating conduit inlet and a regulating conduit outlet, A return conduit having a return conduit inlet and a return conduit outlet, A supply chamber having a supply chamber inlet connected to a return conduit outlet and a supply chamber outlet connected to a control conduit inlet, A discharge chamber having a discharge chamber inlet connected to a control conduit outlet and a discharge chamber outlet connected to a return conduit inlet. This is a method that includes, A static pressure difference is created between the supply chamber outlet and the discharge chamber inlet to generate flow through the regulating conduit. A method is provided that includes this.

[0014]

[0014] Embodiments of the present invention will be described herein by way of example only with reference to the accompanying schematic drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] [Figure 1] depicts a schematic diagram of a lithography apparatus including a temperature control system. [Figure 2] depicts a schematic diagram of a lithography apparatus including a temperature control system. [Figure 3] schematically depicts a first embodiment of a temperature control system according to the present invention. [Figure 4] schematically depicts a second embodiment of a temperature control system according to the present invention. [Figure 5] schematically depicts a third embodiment of a temperature control system according to the present invention. [Figure 6] schematically depicts a fourth embodiment of a temperature control system according to the present invention. [Figure 7] schematically depicts an exemplary embodiment of a discharge chamber. [Figure 8] schematically depicts an alternative exemplary embodiment of a discharge chamber. [Figure 9] schematically depicts an exemplary embodiment of a supply chamber. [Figure 10] schematically depicts an exemplary embodiment of a porous channel. [Figure 11A] schematically depicts an embodiment of a method for producing a porous channel. [Figure 11B] schematically depicts an embodiment of a method for producing a porous channel. [Figure 11C] schematically depicts an embodiment of a method for producing a porous channel. [Figure 12] depicts an embodiment of the temperature control system of FIG. 4, having a first embodiment of a gas-liquid separator in an overflow line. [Figure 13] depicts the gas-liquid separator of FIG. 12 in further detail. [Figure 14]Figure 3 illustrates an embodiment of the temperature control system having a second embodiment of a gas-liquid separator in the overflow line. [Figure 15] Figure 14 shows the gas-liquid separator in more detail. [Modes for carrying out the invention]

[0016]

[0015] In this document, the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation, which include ultraviolet radiation (e.g., having wavelengths of 365, 248, 193, 157 or 126 nm) and EUV (e.g., extreme ultraviolet radiation having wavelengths in the range of about 5 to 100 nm).

[0017] The terms “reticle,” “mask,” or “patterning device” used in this text can be broadly interpreted to refer to any general patterning device that can be used to provide an incident radiation beam with a patterned cross section corresponding to the pattern to be created on a target portion of a substrate. The term “light bulb” may also be used in this text. In addition to classic masks (transmissive or reflective masks, binary masks, phase-shift masks, hybrid masks, etc.), other examples of such patterning devices include programmable mirror arrays and programmable LCD arrays.

[0018]

[0016] Figure 1 schematically depicts a lithography apparatus LA. The lithography apparatus LA includes an illumination system (also called an illuminator) IL configured to adjust a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation), a mask support (e.g., a mask table) MT constructed to support a patterning device (e.g., a mask) MA and connected to a first positioner PM configured to precisely position the patterning device MA according to specific parameters, a substrate support (e.g., a wafer table) WT constructed to hold a substrate (e.g., a resist-coated wafer) W and connected to a second positioner PW configured to precisely position the substrate support according to specific parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project the pattern applied to the radiation beam B by the patterning device MA onto a target portion C of the substrate W (e.g., including one or more dies).

[0019]

[0017] During operation, the illumination system IL receives the radiant beam from the radiation source SO, for example, via the beam delivery system BD. The illumination system IL may include various types of optical components for inducing, shaping and / or controlling the radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic and / or other types of optical components or any combination thereof. The illuminator IL can be used to adjust the radiant beam B so that the radiant beam B has a desired spatial intensity distribution and angular intensity distribution in its cross-section on the surface of the patterning device MA.

[0020]

[0018] The term “projection system” PS as used herein should be interpreted broadly to encompass various types of projection systems, including refractive, reflective, reflective-refracting, anamorphic, magnetic, electromagnetic, and / or electrostatic-optical systems or any combination thereof, suitable for the exposure radiation used and / or other factors (such as the use of immersion liquid or vacuum). Any use of the term “projection lens” herein can be considered synonymous with the more general term “projection system” PS.

[0021]

[0019] The lithography apparatus LA may be of a type in which at least a portion of the substrate is covered with a liquid having a relatively high refractive index (e.g., water) so as to fill the space between the projection system PS and the substrate W, and this is also called immersion lithography. Details of the immersion technique are shown in U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0022]

[0020] The lithography apparatus LA may be of a type having two or more substrate support units WT (also called a “dual-stage” machine). In such a “multi-stage” machine, the substrate support units WT can be used in parallel, and / or, while a substrate W located on one substrate support unit WT is being used to expose a pattern onto that substrate W, subsequent exposure preparation steps can be performed on another substrate W located on another substrate support unit WT.

[0023]

[0021] In addition to the substrate support WT, the lithography apparatus LA may include a measurement stage. The measurement stage is positioned to hold sensors and / or cleaning devices. Sensors may be positioned to measure the characteristics of the projection system PS or the characteristics of the radiating beam B. The measurement stage may hold multiple sensors. Cleaning devices may be positioned to clean parts of the lithography apparatus (e.g., parts of the projection system PS or parts of the system that provides the immersion fluid). The measurement stage may move directly below the projection system PS when the substrate support WT moves away from the projection system PS.

[0024]

[0022] During operation, the radiating beam B is incident on a patterning device (e.g., a mask) MA held on a mask support MT, and a pattern is formed by the pattern (design layout) present on the patterning device MA. After crossing the patterning device MA, the radiating beam B passes through a projection system PS, which focuses the beam onto a target portion C on the substrate W. With the assistance of a second positioner PW and a position measuring system PMS, the substrate support WT can be precisely moved so that, for example, different target portions C are positioned at focus and alignment positions along the path of the radiating beam B. Similarly, a first positioner PM and possibly another position sensor (not explicitly shown in Figure 1) can be used to precisely position the patterning device MA relative to the path of the radiating beam B. The patterning device MA and the substrate W can be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. The substrate alignment marks P1 and P2 occupy dedicated target areas as shown, but can also be located in the spaces between target areas. When the substrate alignment marks P1 and P2 are located between target areas C, they are known as scribelane alignment marks.

[0025]

[0023] Figure 2 shows a lithography system including a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and to supply the EUV radiation beam B to the lithography apparatus LA. The lithography apparatus LA includes an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W.

[0026]

[0024] The illumination system IL is configured to adjust the EUV radiation beam B before it is incident on the patterning device MA. In addition, the illumination system IL may include a field facet mirror device 10 and a pupil facet mirror device 11. Both the field facet mirror device 10 and the pupil facet mirror device 11 provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The illumination system IL may include other mirrors or devices in addition to or instead of the field facet mirror device 10 and the pupil facet mirror device 11.

[0027]

[0025] After this adjustment, the EUV radiation beam B interacts with the patterning device MA. As a result of this interaction, a patterned EUV radiation beam B' is generated. The projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. For this purpose, the projection system PS may include a number of mirrors 13, 14 configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate table WT. The projection system PS can apply a reduction factor to the patterned EUV radiation beam B', and thus can form an image with features smaller than the corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 can be applied. In Figure 2, the projection system PS is shown to have only two mirror elements 13, 14, but the projection system PS may include a different number of mirrors (e.g., six or eight mirrors).

[0028]

[0026] The substrate W may include a previously formed pattern. If this is the case, the lithography apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the previously formed pattern on the substrate W.

[0029]

[0027] The radiation source SO, the illumination system IL and / or the projection system PS can provide a relative vacuum (i.e., a small amount of gas (e.g., hydrogen) at a pressure far below atmospheric pressure).

[0030]

[0028] The radiation source SO may be a laser-generated plasma (LPP) source, a discharge-generated plasma (DPP) source, a free-electron laser (FEL), or any other radiation source capable of generating EUV radiation.

[0031]

[0029] The projection system PS of the lithography apparatus LA in Figure 2 includes a mirror element 14 for reflecting the patterned radiation beam and guiding the patterned radiation beam along the projection path. This reflection of the patterned radiation beam induces a substantial thermal load in the mirror element ME. This thermal load can cause thermal stress and deformation as a result of these thermal stresses within the mirror element ME. Deformation of the mirror element ME can have a substantial adverse effect on the focus and overlay performance of the lithography apparatus and should therefore be avoided.

[0032]

[0030] A thermal control system TCS is provided for regulating the temperature of the mirror element 14 in order to prevent or at least control thermal stress in the mirror element 14. The thermal control system TCS includes a regulating conduit CC arranged to guide a regulating fluid (e.g., water). The regulating conduit CC, which may have a number of tubes, extends along and / or through the mirror element 14 to facilitate heat exchange between the regulating fluid and the mirror element 14. The thermal control system TCS can be used to cool and / or heat (preheat) the mirror element 14.

[0033]

[0031] Figure 3 shows in more detail a first embodiment of a temperature control system TCS for temperature control of a mirror element ME (for example, mirror element 14 shown in Figure 2). The temperature control system TCS includes a supply chamber SC and a discharge chamber DC. In the supply chamber SC, the regulated liquid is held up to a first liquid level LL1. The first liquid level LL1 in the supply chamber SC is held at a constant height using an overflow line OFL to discharge any liquid that would be held above the first liquid level LL1 into the discharge chamber DC. In other words, excess liquid enters the overflow line OFL and is discharged into the discharge chamber DC. In the discharge chamber DC, the regulated liquid is held up to a second liquid level LL2.

[0034]

[0032] In Figures 3-6, only one mirror element ME is shown. In other embodiments, the temperature control system TCS is configured to temperature control multiple mirror elements ME from the same supply / discharge chamber or in parallel with separate chambers.

[0035]

[0033] A thermal conditioner TC (e.g., a control heating element) is provided to control the temperature of the regulated fluid flowing toward the mirror element ME along the regulated conduit CC toward the mirror element ME. The thermal conditioner includes, for example, a temperature sensor and a heating element positioned to maintain a constant temperature of the regulated fluid. The thermal conditioner TC may also include a cooling element (control cooling element). In an alternative embodiment, the thermal conditioner TC may be positioned at least partially within or adjacent to the supply chamber SC to control the temperature of the regulated fluid in the supply chamber SC. In another alternative embodiment, the thermal conditioner TC may be positioned in another suitable location, such as in the return conduit RC between the pump PU and the supply chamber SC, to remove heat from the liquid.

[0036]

[0034] The supply chamber SC includes a supply chamber inlet SCI and a supply chamber outlet SCO. The supply chamber inlet SCI is positioned above the first liquid level LL1, and the supply chamber outlet SCO is positioned below the first liquid level LL1. Correspondingly, the discharge chamber DC includes a discharge chamber inlet DCI and a discharge chamber outlet DCO, where the discharge chamber inlet DCI is positioned above the second liquid level LL2, and the discharge chamber outlet DCO is positioned below the second liquid level LL2. By positioning the discharge chamber inlet DCI above the second liquid level LL2, it is advantageous to eliminate the influence of the second liquid level LL2 on the regulated fluid pressure in the regulated circuit CC. Thus, with a more stable pressure, the transmission of FIV is advantageously reduced.

[0037]

[0035] The supply chamber outlet SCO is connected to the regulating conduit inlet CCI of the regulating conduit CC, and the discharge chamber inlet DCI is connected to the regulating conduit outlet CCO of the regulating conduit CC. Thus, the regulating fluid can flow from the supply chamber SC through the regulating conduit CC to the discharge chamber DC. Since the first fluid level LL1 is maintained at a first height and the discharge chamber inlet DCI is positioned at a second height (the second height is lower than the first height), there is a constant hydrostatic pressure difference between the supply chamber outlet SCO and the discharge chamber inlet DCI. This results in a continuous flow with low pressure fluctuations in the regulating conduit CC. These flow pressure fluctuations are undesirable because they can cause flow-induced oscillations in the mirror element ME, which can adversely affect the focus and / or overlay of the lithography process. Since the continuous flow is driven by a stable pressure difference, the present invention can significantly reduce flow-induced oscillations in the mirror element ME, which can advantageously improve the overlay performance of the lithography apparatus LA.

[0038]

[0036] The supply chamber SC and the discharge chamber DC are arranged or positioned such that there is a height difference between them, so that a constant hydrostatic pressure flow is provided between both chambers SC, DC and the regulating conduit CC, thereby creating a difference between the two chambers. This advantageously reduces the FIV transmitted to the mirror element ME. The absence of FIV transmission to the mirror element ME eliminates distortion or image errors caused by the interaction between the radiated beam and the mirror element ME. In one embodiment, the temperature control system TCS may arrange the supply chamber SC and the discharge chamber DC at different heights from each other, or there may be a height difference between the supply chamber SC and the discharge chamber DC. This creates a pressure rise, more specifically, a hydrostatic pressure rise. Preferably, the supply chamber SC is at a higher height than the floor.

[0039]

[0037] A return conduit RC is provided to return the regulated fluid from the discharge chamber DC to the supply chamber SC. The discharge chamber outlet DCO is connected to the return conduit inlet RCI of the return conduit RC, and the supply chamber inlet SCI is connected to the regulated conduit outlet CCO of the return conduit RC. In the return conduit RC, a pump PU is provided to pump the regulated fluid from the discharge chamber DC to the supply chamber SC. To ensure that the first liquid level LL1 in the supply chamber is maintained constant, the flow rate of the fluid pumped by the pump PU through the return conduit RC must always be greater than the flow rate of the fluid through the regulated conduit CC, so that there is always a fluid flow through the overflow line OFL. Given a specific vertical distance between LL1 and DCI, a first flow resistance can be provided between the supply chamber SC and the mirror element ME, and / or a second flow resistance can be provided between the mirror element ME and the discharge chamber DC to control the flow.

[0040]

[0038] The thermal control system TSC may include a flow control device for controlling the flow rate of liquid pumped by the pump PU through a return conduit RC, the control device being positioned to maintain a flow rate of liquid pumped by the pump PU that is greater than the flow rate of liquid through the regulating conduit CC. The flow control device can operate the pump, for example, based on a sensor signal from a flow sensor that measures the flow rate of regulating liquid in the regulating conduit and / or overflow line OFL, or based on a sensor signal from a liquid level sensor that measures the height of a first liquid level LL1 in the supply chamber SC.

[0041]

[0039] The pumping action of the pump can cause pressure fluctuations in the regulated fluid present in the return conduit RC. To prevent these pressure fluctuations from propagating to the regulated fluid in the regulated conduit CC, the pressure fluctuations are at least partially attenuated by providing relatively large gas volumes in the supply chamber SC and the discharge chamber DC. To provide a substantial attenuation effect, each of the first gas volume GV1 in the supply chamber SC and the second gas volume GV2 in the discharge chamber has a volume of at least 0.5 liters (e.g., at least 10 liters).

[0042]

[0040] To prevent pressure fluctuations caused by acceleration of a portion of the liquid system due to vibration of machine parts and / or floor vibration, damping devices or means can be provided. The damping device or means may be located, for example, between the temperature conditioner TC and the mirror element or between the mirror element and the discharge chamber DC. The damping device may be a Helmholtz resonator type or bellows type damper or other type damper or a combination thereof.

[0043]

[0041] The liquid circuit may have many connections for filling the circuit with a primed conditioning fluid, for draining the circuit, for performing a leak test on the circuit (i.e., for testing for leaks in the circuit), and for flushing and priming the circuit.

[0044]

[0042] In the embodiment shown in Figure 3, the control conduit CC is liquid-separated from the return conduit. This means that there is no continuous liquid volume between the control conduit CC and the return conduit RC or at least a portion of the return conduit RC where the pump is located. This has a further beneficial effect in preventing the flow-excited vibrations of the return conduit RC from being propagated to the control conduit CC. This liquid separation is created by a first gas volume GV1 located above the first liquid level LL1 of the supply chamber SC and a second gas volume GV2 located above the second liquid level LL2 of the discharge chamber DC.

[0045]

[0043] Since the supply chamber inlet SCI and the discharge chamber inlet DCI are positioned above the first liquid level LL1 and the second liquid level LL2, respectively, there is no continuous liquid volume between the regulating conduit CC and the return conduit RC. Any pressure fluctuations generated by the pump PU and propagating through the regulating fluid present in the return conduit RC are mainly absorbed by the first and / or second gas volumes of the supply chamber SC and the discharge chamber DC, and therefore substantially do not reach the regulating fluid in the regulating conduit CC. The mechanical rigidity of the connections between the supply chamber SC and the discharge chamber DC is low, and as a result, pressure fluctuations in the supply conduit SC and / or regulating conduit CC are not generated, for example, by mechanical vibration. These connections include, for example, the connections to the return conduit RC, the overflow line OFL, the regulating conduit inlet CCI, and the regulating conduit outlet CCO.

[0046]

[0044] The flow in the regulating conduit is driven by a constant hydrostatic pressure difference between the pressure at the supply chamber outlet SCO and the pressure at the discharge chamber inlet DCI, without any pressure fluctuations caused by the pump PU and other parts / components. Therefore, the flow of the regulating fluid through the regulating conduit has very small flow-induced oscillations. The supply chamber inlet SCI and / or the discharge chamber inlet DCI may not be positioned above the first liquid level LL1 and the second liquid level LL2, respectively. In such embodiments, as described with respect to the embodiment in Figure 6, one or more valves may be provided to block the flow-induced oscillations present in the return conduit RC before reaching the regulating conduit CC, or damping materials or damping devices such as foamed material, mesh material and / or perforated material may be provided to dampen the propagation of pressure fluctuations through the regulating fluid. In such embodiments, relatively large first gas volume GV1 and second gas volume GV2 also have the effect of damping the flow-induced oscillations. The temperature control system TCS in Figure 3 is a closed system. This means that there is no direct fluid communication with the environment. The pressure in the first gas volume GV1 of the supply chamber SC and the pressure in the second gas volume GV2 of the discharge chamber DC are controlled by the gas pressure controller GPC. The pressure in the first volume GV1 and the pressure in the second gas volume GV2 are the same. Therefore, the flow through the regulating conduit CC is driven only by a constant hydrostatic pressure difference between the pressure at the supply chamber outlet SCO and the pressure at the discharge chamber inlet DCI, which is caused by the height difference between the first liquid level LL1 and the height of the discharge chamber inlet DCI. In a further embodiment, a pressure sensor PSE can be provided to measure the pressure in the regulating conduit CC. The measured pressure can be used as an input to the gas pressure controller GPC.

[0047]

[0045] The gas pressure controller GPC is used to maintain a constant pressure below atmospheric pressure in the first gas volume GV1 and the second gas volume GV2. In one embodiment, the first pressure in the supply chamber SC and the second pressure in the discharge chamber DC are maintained at a pressure below atmospheric pressure. The pressures in the first gas volume GV1 and the second gas volume GV2 are set to an absolute pressure level below, for example, 0.5 bar (e.g., in the range of 0.1 to 0.3 bar). Advantageously, a thermal control system below atmospheric pressure reduces deformation of the surface of the mirror element ME. In addition, the regulated fluid flowing at a pressure throw below atmospheric pressure advantageously reduces the stiffness of the mirror element dynamic link, thereby achieving dynamic isolation of vibrations.

[0048]

[0046] In one embodiment, the thermal control system TCS includes a gas pressure controller configured to control the gas pressure level of at least one chamber (i.e., the supply chamber only, the discharge chamber only, or both). As described above, the first pressure in the supply chamber and the second pressure in the discharge chamber are maintained at a pressure level lower than atmospheric pressure.

[0049]

[0047] Figure 4 shows a second embodiment of the thermal control system TCS. This embodiment differs from the embodiment in Figure 3 in how it controls the gas pressure in the supply chamber SC and the discharge chamber DC. The embodiment in Figure 3 includes one gas pressure controller GPC to maintain a constant pressure below atmospheric pressure in the first gas volume GV1 and the second gas volume GV2, whereas the embodiment in Figure 4 includes a first gas pressure controller GPC1 for controlling the gas pressure in the first gas volume GV1 of the supply chamber SC and a second gas pressure controller GPC2 for controlling the gas pressure in the second gas volume GV2 of the discharge chamber SC. In further embodiments, a pressure sensor PSE can be provided to measure the pressure in the regulating conduit CC. The measured pressure can be used as input to the first gas pressure controller GPC1 and the second gas pressure controller GPC2.

[0050]

[0048] The advantage of having two separate gas pressure controllers GPC1 and GPC2 is that the static pressure difference between the supply chamber outlet SCO and the discharge chamber inlet DCI is determined not only by the height difference between the first liquid level LL1 and the height of the discharge chamber inlet DCI, but also by the pressure difference between the pressure of the first gas volume GV1 and the pressure of the second gas volume GV2. Since the gas pressure provided by the first gas pressure controller GPC1 and the second gas pressure controller GPC2 can be controlled precisely and actively, this setup provides further flexibility in the vertical relative arrangement of the supply chamber SC and the discharge chamber DC. In the embodiment of Figure 3, the flow through the regulating conduit CC is driven only by the hydrostatic pressure difference resulting from the height difference as shown in the embodiment of Figure 3, so a required height difference exists between the supply chamber SC and the discharge chamber DC. In the embodiment shown in Figure 4, the pressure difference provided by the gas pressure controllers GPC1 and GPC2 offers further possibilities for controlling the flow through the regulating conduit CC, so the height difference requirement is not as stringent.

[0051]

[0049] In the embodiment shown in Figure 4, the discharge chamber inlet DCI is positioned below the first liquid level LL1. In this embodiment, the relatively large volume of the first gas volume GV1 reduces the propagation of flow-induced vibrations coming from the return state RC to the regulating conduit CC. In addition, the supply chamber inlet SCI includes a mesh / foam material to dampen the propagation of pressure fluctuations through the regulating fluid. The regulating fluid flows through the mesh, reducing / damping vibrations as it flows into the supply chamber SC and discharge chamber DC, respectively. Examples of such embodiments of the discharge chamber DC and supply chamber SC are shown in Figures 7-9.

[0052]

[0050] In the embodiment shown in Figure 4, the flow through the regulating conduit CC is based on a static pressure difference that results in a flow with low pressure fluctuations through the regulating conduit CC. This is advantageous because it allows for a flow with extremely small flow-excited oscillations, since the flow is driven by a stable pressure difference. The first gas pressure controller GPC1 and the second gas pressure controller GPC2 are also used to maintain a pressure lower than atmospheric pressure in the first gas volume GV1 and the second gas volume GV2. Along with this, the presence of flow-excited oscillations in the mirror element ME due to the flow of the regulating fluid can be further reduced.

[0053]

[0051] Figure 5 shows a third embodiment of the thermal control system TCS. This embodiment differs from the embodiment in Figure 3 in the method of controlling the first liquid level LL1. This embodiment provides a movable piston MPI which includes a piston body partially immersed in the liquid in the supply chamber SC and a linear actuator configured to move the piston body vertically to actively adapt the depth to which the piston body is immersed in the liquid.

[0054]

[0052] A liquid level sensor LSE is provided to measure a first liquid level LL1 of the liquid in the supply chamber SC. Based on the first liquid level LL1 as measured by the liquid level sensor LSE, the position of the piston body can be adapted to control the first liquid level LL1. In this way, a constant hydrostatic pressure difference can be maintained between the supply chamber outlet SCO and the discharge chamber inlet DCI to drive a constant flow through the regulating conduit CC.

[0055]

[0053] In addition to or as an alternative, a pressure sensor PSE can be provided to measure the pressure in the regulating conduit CC, and a movable piston MPI is actively controlled to maintain a constant pressure at the location of the pressure sensor PSE (i.e., where the pressure in the regulating conduit CC is measured).

[0056]

[0054] By using this active control of the pressure at the measurement location of the first liquid level LL1 and / or the regulating conduit CC based on the measured height of the first liquid level LL1, fluctuations in the pressure rise of the thermal control system TCS can be dealt with more accurately. For example, a temporary shortage in the inflow of regulating fluid can be balanced by moving the piston MPI downward and thereby maintaining the desired first liquid level LL1. This prevents fluctuations in the level of the first liquid level LL1 due to fluctuations in the pump flow of the pump PU, which cause deviations from the desired pressure level of the regulating conduit CC and fluctuations in the flow rate in the regulating conduit CC.

[0057]

[0055] Similar to the embodiment in Figure 3, the regulating conduit CC is separated from the return conduit RC by the first gas volume GV1 of the supply chamber SC and the second gas volume GV2 of the discharge chamber DC. Since the supply chamber inlet SCI and the discharge chamber inlet DCI are located above the first liquid level LL1 and the second liquid level LL2, respectively, there is no continuous liquid volume between the regulating conduit CC and the return conduit RC that can propagate pressure fluctuations caused by the pumping action of the pump PU. Alternatively or in addition to this, structures / materials that attenuate pressure fluctuations can be provided.

[0058]

[0056] Figure 6 shows a fourth embodiment of the thermal control system TCS. In this embodiment, the supply chamber SC includes a main supply chamber MSC and an auxiliary supply chamber ASC connected to each other via a first connecting conduit including a first connecting valve CVA1. The discharge chamber DC includes a main discharge chamber MDC and an auxiliary discharge chamber ADC connected to each other via a second connecting conduit including a second connecting valve CVA2. Furthermore, the return conduit RC includes a first valve VA1 located downstream of the pump PU and a second valve VA2 located upstream of the pump PU. The first and second connecting valves CVA1 and CVA2, and the first and second valves VA1 and VA2, can each be positioned in a closed position and an open position.

[0059]

[0057] The thermal control system TCS also includes a first gas pressure controller GPC1 for controlling the gas pressure of the main supply chamber MSC and the auxiliary supply chamber ASC, and a second gas pressure controller GPC2 for controlling the gas pressure of the main discharge chamber MDC and the auxiliary discharge chamber ADC. A first pressure valve PV1 and a second pressure valve PV2 are provided to open and / or close the pressure control of the auxiliary supply chamber ASC and the auxiliary discharge chamber ADC, respectively.

[0060]

[0058] The liquid levels in the main supply chamber MSC and the main discharge chamber MDC may change over time. In certain embodiments not shown, a first liquid level sensor LLSS may be provided to the main supply chamber MSC to measure the liquid level in the main supply chamber MSC. Correspondingly, a second liquid level sensor LLSD may be provided to the main discharge chamber MDC to measure the liquid level in the main discharge chamber MDC. The liquid levels measured by the first liquid level sensor LLSS and the second liquid level sensor LLSD may be used as inputs to the first gas pressure controller GPC1 and the second gas pressure controller GPC2, respectively, to adjust the pressure levels according to the actual liquid levels in the main supply chamber MSC and the main discharge chamber MDC.

[0061]

[0059] The configuration in Figure 6 allows for two (main) operating modes. In the first mode, the first valve VA1 and the second valve VA2 are closed, and the first connecting valve CVA1 and the second connecting valve CVA2, as well as the first pressure valve PV1 and the second pressure valve PV2, are open.

[0062]

[0060] In this first mode, the main supply chamber MSC and the auxiliary supply chamber function as a single supply chamber SC, and the main discharge chamber MDC and the auxiliary discharge chamber ADC function as a single discharge chamber DC. By controlling the pressures of the supply chamber SC and the discharge chamber DC, respectively, using the first gas pressure controller GPC1 and the second gas pressure controller GPC2, the static pressure difference between the supply chamber outlet SCO and the discharge chamber inlet DCI can be precisely controlled so that a constant flow with low pressure fluctuations is produced through the regulating conduit CC.

[0063]

[0061] This control can be further improved by using a measured pressure level, for example, measured by a pressure sensor PSE in the regulating conduit CC. In this first operating mode, the return conduit RC is at least partially separated from the regulating conduit by a closed first valve VA1 and a closed second valve VA2. The regulating fluid flows from the supply chamber SC to the discharge chamber DC, but since the first valve VA1 and the second valve VA2 are closed, the regulating fluid cannot return from the discharge chamber DC to the supply chamber SC.

[0064]

[0062] In the second operating mode, the first valve VA1 and the second valve VA2 are open, and the first connecting valve CVA1 and the second connecting valve CVA2, as well as the first pressure valve PV1 and the second pressure valve PV2, are closed. In this second mode, only the main supply chamber MSC functions as the supply chamber SC, and only the main discharge chamber MDC functions as the discharge chamber DC. By controlling the pressures of the main supply chamber SC and the main discharge chamber MDC, respectively, using the first gas pressure controller GPC1 and the second gas pressure controller GPC2, the static pressure difference between the supply chamber outlet SCO and the discharge chamber inlet DCI can be precisely controlled so that a constant flow with low pressure fluctuations is generated through the regulating conduit CC, in order to prevent flow-induced oscillations in the Miller element.

[0065]

[0063] In the second operating mode, the regulating fluid from the auxiliary discharge chamber ADC can be pumped into the auxiliary supply chamber ASC by the pump PU through the return conduit RC to replenish the auxiliary supply chamber ASC. In this second operating mode, the main supply chamber MSC is separated from the portion of the return conduit RC where the pump PU is located by a closed first connecting valve CVA1, and the main discharge chamber MDC is separated from the portion of the return conduit RC where the pump PU is located by a closed second connecting valve CVA2. Thus, in the second operating mode, the regulating fluid is pumped into the auxiliary supply chamber ASC at the same time that the regulating conduit CC is separated from the return conduit RC.

[0066]

[0064] By alternating between the first and second operating modes, a constant flow can be generated based on the static pressure difference between the supply chamber outlet SCO and the discharge chamber inlet DSI, while at least a portion of the return conduit RC where the pump is located is separated from the regulating conduit CC. This has the advantage that, for example, the flow-excited vibrations of the mirror element ME caused by pressure fluctuations of the regulating fluid as a result of the pumping action of the pump PU are substantially reduced.

[0067]

[0065] In the embodiment of the thermal control system TCS described above, it is beneficial that the inflow and outflow of the regulating fluid in the supply chamber SC and the discharge chamber DC do not generate pressure fluctuations that can propagate through the regulating fluid, particularly in the regulating conduit CC.

[0068]

[0066] For example, at the location of the supply chamber outlet SCO, the regulating fluid enters the small-diameter tube of the regulating conduit CC from the large volume of the supply chamber SC so that the flow is accelerated. Without this provision, the flow tends to separate at the regulating conduit inlet CCI, which can cause flow-induced oscillations in the mirror element ME. To prevent this, for example, a curved inlet with a flow straightener can be placed at the supply chamber outlet SCO.

[0069]

[0067] Where water flows into the supply chamber and / or discharge chamber, the regulating fluid may flow into each chamber from above the respective liquid level. To reduce / prevent the effects of pressure fluctuations, control of the flow of the regulating fluid into the chamber can be created by providing specific structures or materials that interrupt the flow of the regulating fluid, allowing the regulating fluid to smoothly enter the volume of regulating fluid in the chamber. For example, the regulating fluid may enter the chamber from above and fall onto a wire mesh placed inside a perforated tube. The wire mesh interrupts the water column, and the perforated tube allows for a smooth flow of the regulating fluid into the volume of regulating fluid in each chamber.

[0070]

[0068] Figure 7 shows an exemplary embodiment of the discharge chamber DC in more detail. From the viewpoint of pressure level control, it is desirable to separate the regulated fluid entering the discharge chamber DC through the discharge chamber inlet DCI from the second liquid level LL2 so that changes in the second liquid level LL2 do not result in changes in the pressure level, thereby preventing changes in the flow and pressure level returning to the regulated conduit CC. Separation of the regulated fluid flowing through the discharge chamber inlet DCI from the regulated fluid already present in the discharge chamber DC is achieved by placing the discharge chamber inlet DCI on the upper wall of the discharge chamber DC. To further reduce / prevent pressure fluctuations caused by the regulated fluid falling into the second liquid level LL2, a wire mesh WM is provided inside the perforated tube PFT. The wire mesh WM divides the regulated fluid column falling through the discharge chamber inlet DCI, and the perforated tube PT ensures that the regulated fluid enters the volume of regulated fluid in the discharge chamber smoothly. The wire mesh WM may be an example of an inlet flow damping device.

[0071]

[0069] In alternative embodiments, a stepped or stepped shape (i.e., a wide step) that allows the regulated fluid to flow into the chamber at a low speed and a small step before the regulated fluid comes into contact with the liquid surface can be applied. The stepped or stepped shape may be an example of an inlet flow damping device.

[0072]

[0070] Another alternative embodiment provides a slit or small slit as a water inlet for flowing water into the chamber. This slit may take the form of a planar slit or a circular slit. In yet another embodiment, as shown in Figure 8, the inner wall of the chamber may be coated with wire mesh material WMM on the back side of a perforated plate to facilitate the inflow of the regulated fluid into the chamber. The slit or small slit may be an example of an inlet flow damping device.

[0073]

[0071] In embodiments in which the controlled fluid enters the chamber from below the liquid surface, damping materials such as porous materials, foamed materials, mesh materials and / or perforated materials can be provided to dampen pressure fluctuations in the controlled fluid. The wire mesh WM described in these embodiments and in the embodiments of Figures 7 and 8 may also be applicable to the supply chamber SC. Thus, the supply chamber SC may include the wire mesh WM, damping material, steps and / or slits described above. All of these elements may be examples of inlet flow damping devices.

[0074]

[0072] Figure 9 shows an exemplary embodiment of the supply chamber SC. The supply chamber inlet DCI is aligned with a wire mesh and perforated inlet WMPI to reduce the liquid velocity to near 0 m / s before the liquid enters the supply chamber SC in order to prevent pressure fluctuations in the supply chamber. The overflow line OFL includes an overflow pipe OFT that extends to the first liquid level LL1 to maintain the first liquid level LL1 at a constant height. To maintain the first liquid level LL1 at a constant height (i.e., to stabilize it within a range of less than 0.2 mm), the overflow pipe OFT is made hydrophobic to prevent the formation of a meniscus due to the surface tension of the fluid (which would adversely affect the desired height of the first liquid level LL1). The volume of gas located above the first liquid level LL1, which is related to water level fluctuations, is an important parameter in the attenuation of pressure fluctuations caused by water level fluctuations. Therefore, the volume of gas in the supply chamber is at least 0.5 liters (e.g., at least 10 liters).

[0075]

[0073] More generally, it may be desirable to provide suitable materials at locations in the regulating fluid circuit of a temperature control system where discontinuities in the flow path (e.g., curves, constrictions, or manifolds) exist that can cause flow-excited oscillations in the regulating fluid circuit. These materials may include, for example, foamed materials, porous materials, mesh materials, perforated materials, and (other) materials with high damping properties (e.g., PUR). It may also be possible to provide multiple substantially parallel channels to reduce flow obstructions in the flow of the regulating fluid.

[0076]

[0074] The main operating principle is based on homogenizing the flow in combination with increasing the dominance of viscous force over inertial force. Porous materials, foamed materials, or similar materials locally block the flow in the conduit, and larger flow structures / turbulent vortices are divided into smaller structures / vortices, resulting in a more uniform flow distribution. Furthermore, high shear stress in porous materials or similar materials increases local viscous force, dispersing high pressure losses. Also, by enabling the use of porous materials or similar materials, the effective Reynolds number is reduced, which further contributes to increasing the dominance of viscous force over inertial force. As a result, the redirection of flow momentum is mitigated by balancing the pressure gradient associated with flow curvature through a more uniform flow distribution and a locally increased dominance of viscous force over inertial force. Consequently, the flow is guided more smoothly through channels with discontinuities in the flow path, leading to the effect of reduced flow separation and induced flow-excited oscillations.

[0077]

[0075] In certain embodiments, a metal foam material may be used. Such a metal foam material can be produced by sintering, additive manufacturing, or other known techniques for producing a metal foam structure, such as powder metallurgy process techniques or metallurgical melting process techniques.

[0078]

[0076] Multiple parallel channels can be formed, for example, by a metal component having many small laser-cut channels, by a bundle of fiber / microfiber / nanofiber tubes packed into a component, or by additive manufacturing.

[0079]

[0077] Figure 10 shows a first exemplary embodiment of a tube provided with elements for forming a partially filled channel. This embodiment includes an ultra-low expansion glass (ULE) cylinder CYL filled with sintered ULE beads BEA to avoid thermal expansion differences. Multiple inlet openings INO are provided on the top surface for the inflow of a regulated fluid. During manufacturing, sacrificial material can be mixed with the BEA beads and removed by solvent or heating to increase the proportion of voids. The primary material choice for the cylinder is ULE to minimize the thermal expansion of the material to prevent stress that may be introduced into the mirror. If such stress is acceptable, alternative materials may be considered. In addition to or as an alternative thereto, other colloidal particle shapes for infiltration into the cylinder may also be considered, such as fibers, microfibers, nanofibers, fiber bundles or polygonal shapes. One end of the cylinder CYL may be provided with a ULE ramp to guide the flow of liquid through the cylinder CYL. The structure shown in Figure 9 can be used, for example, as a manifold in a thermal control system.

[0080]

[0078] Figures 11A to 11C show an alternative process for creating an inverted, more open structure. Figure 11A shows a template created with removable elements REM (e.g., those that can be removed by solvent or heating). Figure 11B shows a permanent material PEM being impregnated into the spaces not occupied by the removable elements. In the final step, the removable elements are removed. This results in the porous structure shown in Figure 11C.

[0081]

[0079] Other techniques can also be applied to create suitable damping materials. For example, a flexible viscoelastic hose can be applied to provide damping.

[0082]

[0080] Thus, a thermal control system for thermal control of mirror elements of a projection system of a lithography apparatus is disclosed. The thermal control system can also be applied to thermal control of other objects in a lithography apparatus or other device, where flow-excited vibrations of an object caused by the flow of a controlled fluid should be reduced.

[0083]

[0081] In the embodiments shown in Figures 3-5, in order to satisfy the pressure stability conditions in the regulating conduit CC that extends through or along the mirror element ME, it is necessary to control the liquid level LL1 of the supply chamber SC to a precise level (e.g., within a height range of 0.2 mm). Based on the pressure rise due to gravity Δp = ρgΔh, a first liquid level LL1 fluctuation of 0.2 mm results in a pressure fluctuation of 2 Pa.

[0084]

[0082] In the embodiments shown in Figures 3 and 4, the overflow line OFL is used to maintain a stable first liquid level LL1 in the supply chamber SC and, together with it, to maintain a stable supply pressure to the mirror element ME within a desired pressure range.

[0085]

[0083] However, in the overflow channel OFL, gas present above the first liquid level LL1 in the supply chamber SC may be drawn into the overflow line OFL by the liquid and mix with the liquid heading toward the discharge chamber DC, thus causing a two-phase flow. Such a mixture of gas and liquid can cause pressure fluctuations propagated in the supply chamber SC and the discharge chamber DC. These pressure fluctuations can result in displacement and deformation of the mirror element ME, which is undesirable as it can lead to overlay errors, fading, and flaring.

[0086]

[0084] Furthermore, in the embodiment shown in Figure 4, the separate control of the pressure of the first gas volume GV1 and the pressure of the second gas volume GV2 using the first gas pressure controller GPC1 and the second gas pressure controller GPC2 can create a further pressure difference between the supply chamber SC and the discharge chamber DC. This further pressure difference can also induce gas flow from the supply chamber SC to the discharge chamber DC. This gas flow can also create a two-phase flow that leads to pressure fluctuations, resulting in associated adverse effects of overlay error, fading, and flare. In addition, the presence of gas in the flow through the overflow line OFL can also affect the set pressure difference between the supply chamber SC and the discharge chamber DC. Therefore, it is desirable that the gas in the flow through the overflow line OFL be substantially reduced.

[0087]

[0085] Figure 12 shows the thermal control system of Figure 4, in which a gas-liquid separator GLS is provided in the overflow line OFL to prevent gas flow through the overflow line OFL due to the gas pressure difference between the supply chamber SC and the discharge chamber DC. The gas-liquid separator GLS is formed by a liquid trap (i.e., an inverted siphon), which is shown in more detail in Figure 13.

[0088]

[0086] The gas-liquid separator GLS is part of the overflow line OFL. The liquid enters the gas-liquid separator GLS from the OFL-I side and exits the gas-liquid separator GLS from the OFL-O side. In the gas-liquid separator GLS, instead of the gas flowing further through the overflow line as a two-phase flow, at least one channel portion URC extending upward in the flow direction is provided to form a liquid trap so that the gas can return to the inlet of the gas-liquid separator GLS on the OFL-I side. A porous material POM is placed in the upward-extending channel portion URC. The porous material POM can provide damping to prevent or reduce flow pressure fluctuations caused by the inflow and sloshing of the liquid flow. The porous material POM includes, for example, balls, mesh and / or perforated elements.

[0089]

[0087] The gas-liquid separator GLS is positioned to at least partially prevent gas mixed in with the liquid flow from flowing further along the overflow line OFL toward the discharge chamber DC. Gas mixed in with the liquid flow that flows into the overflow line OFL can be separated from the liquid flow and return through the overflow line OFL to the supply chamber SC. At the same time, the two-phase flow in the overflow line OFL is effectively stopped or at least substantially reduced in the gas-liquid separator GLS.

[0090]

[0088] Due to the additional pressure difference that may arise in the embodiment of Figure 4, the liquid level in the upward-extending channel portion URC is higher than the liquid level in the channel portion coming from the supply chamber (the left channel). The height of the upward-extending channel portion URC is selected to accommodate this additional pressure difference.

[0091]

[0089] The gas-liquid separator GLS is positioned relatively close to the supply chamber SC, at least in the vertical direction. For example, when the height difference between the first liquid level LL1 and the discharge chamber inlet DCI of the discharge chamber is H, the gas-liquid separator GLS can be positioned at a maximum distance of 0.2H (e.g., a maximum of 0.1H) from the supply chamber SC in the vertical direction. In this case, the length of the overflow line OFL where two-phase flow occurs (i.e., between the supply chamber SC and the gas-liquid separator GLS) is relatively short. The distance between the supply chamber SC and the gas-liquid separator may be, for example, less than 1m.

[0092]

[0090] The gas-liquid separator inlet on the OFL-I side and the gas-liquid separator outlet on the OFL-O side are designed so that the interaction between water and gas does not cause or at least reduces the film formation / breakdown process, because it may cause pressure fluctuations. For example, highly wettable materials and / or coatings can be placed in the inlet OFL-I and outlet OFL-O. For example, metallic materials can be provided in the inlet OFL-I and outlet OFL-O. Furthermore, the geometry of the inlet / outlet can be optimized by allowing a conical or funnel-like design with a sufficiently large diameter to allow for the smooth flow of water into the gas-liquid separator.

[0093]

[0091] The gas-liquid separator GLS can be made from any suitable material, such as a metal like stainless steel or a plastic material like polyurethane.

[0094]

[0092] Figure 14 shows an embodiment of Figure 3, which provides an alternative embodiment of the gas-liquid separator GLS for separating gases mixed with liquids flowing into the overflow line OFL. The gas-liquid separator GLS of Figure 14 is shown in more detail in Figure 15.

[0095]

[0093] As depicted in Figure 15, the gas-liquid separator GLS is formed in a sealed box shape and is provided with a first plate PLA1 defining a lower opening in the gas-liquid separator GLS and a second plate PLA2 defining an upper opening in the gas-liquid separator GLS, forming a liquid trap structure. The liquid level LL of the liquid trap structure is at the same height as the upper end of the second plate PLA2.

[0096]

[0094] Near the inlet OFL-I of the gas-liquid separator GLS, a gas return channel GRC is provided to allow the gas separated from the liquid flow to return to the supply chamber SC through a channel separate from the overflow line OFL. Such a separate gas return channel GRC can further reduce the occurrence of pressure fluctuations caused by the presence of gas in the overflow line. To make effective use of the gas return channel GRC, the gas-liquid separator GLS is designed to have a gas volume GV that is directly connected to the gas return channel GRC, so that the gas separated from the liquid can enter the gas return channel GRC through the gas volume GV.

[0097]

[0095] The position of the gas return channel GRC inlet of the supply camber SC must be carefully selected. It must satisfy the following conditions: it must be located above the liquid level LL1 to prevent the formation of bubbles by the gas, which then burst on the surface, causing vibration or acoustic disturbances. In addition, to prevent vibration or acoustic disturbances, the gas coming from the gas return channel GRC must not interfere with the return flow coming from the supply chamber inlet SCI. Furthermore, to dampen pressure fluctuations, the gas return channel GRC must be in fluid communication with the first gas volume GV1. In the embodiment of Figure 14, the gas return channel GRC inlet of the supply camber SC is located below the supply chamber inlet SCI so that these conditions are met. In other embodiments, the gas return channel GRC inlet may be located above the supply chamber inlet SCI or on the upper surface of the supply chamber SC, and in that case, these conditions may also be met.

[0098]

[0096] To prevent pressure fluctuations due to inflow and sloshing, porous material POM is placed in the gas-liquid separator GLS so as to attenuate the liquid flow. The porous material POM includes, for example, balls, mesh and / or perforated elements. The porous material is present in the liquid trap structure, for example, up to the liquid level LL, to attenuate pressure fluctuations in the liquid present in the liquid trap structure. If desired, for example, by a manufacturing method, further porous material can be provided in the gas-liquid separator GLS. For example, before closing the box, porous material can be introduced from the top of the box, across the entire bottom of the box, until a desired level of porous material in the box is reached.

[0099]

[0097] In accordance with the embodiments of Figures 12 and 13, the gas-liquid separator GLS is positioned to at least partially prevent gas mixed in with the liquid flow from flowing further along the overflow line OFL toward the discharge chamber DC. Gas mixed in with the liquid flow that flows into the overflow line OFL is separated from the liquid flow and moves upward toward the gas volume GV, from which the gas returns through the gas return channel toward the supply chamber SC.

[0100]

[0098] As described with reference to the embodiments of Figures 12 and 13, it may be advantageous to position the gas-liquid separator GLS so that it is relatively close to the supply chamber SC, at least in the vertical direction.

[0101]

[0099] The gas-liquid separator GLS can be made from any suitable material, such as a metal like stainless steel or a plastic material like polyurethane.

[0102] [000100] The gas-liquid separator GLS in Figure 15 can also be combined with the embodiment of the thermal control system in Figure 4. In that embodiment, a further pressure difference can be created between the supply chamber SC and the discharge chamber DC by the separate control of the pressure of the first gas volume GV1 and the pressure of the second gas volume GV2, respectively, using the first gas pressure controller GPC1 and the second gas pressure controller GPC2. To accommodate such a further pressure difference, the vertical height HD between the lower end of the first plate PLA1 and the upper end of the second plate PLA2 must be appropriately selected. In practice, this length may be at least 30 cm (e.g., at least 50 cm).

[0103] [000101] The gas-liquid separator GLS in Figure 13 can also be combined with the embodiment of the thermal control system in Figure 3.

[0104] [000102] While this document specifically refers to the use of lithography equipment in IC manufacturing, it should be understood that the lithography equipment described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, induction and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, and the like.

[0105] [000103] This document specifically refers to embodiments of the present invention in the context of lithography apparatus, but embodiments of the present invention can also be used in other apparatuses. Embodiments of the present invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatuses can generally be called lithography tools. Such lithography tools may operate under vacuum conditions or ambient (non-vacuum) conditions.

[0106] [000104] Although the above specifically refers to the use of embodiments of the present invention in the context of optical lithography, it will be understood that the present invention is not limited to optical lithography and can be used in other applications (e.g., imprint lithography) as long as it is recognized in the context.

[0107] [000105] While specific embodiments of the present invention have been described above, it will be understood that the present invention can be carried out in ways other than those described. The above description is for illustrative purposes only and not limitations. Accordingly, it will be apparent to those skilled in the art that the described invention can be modified without departing from the scope of the following clauses. 1. A temperature control system that uses a regulating liquid to adjust the temperature of an object, A regulating conduit for guiding a regulating fluid through or along an object, comprising a regulating conduit inlet and a regulating conduit outlet, A return conduit having a return conduit inlet and a return conduit outlet, A supply chamber having a supply chamber inlet connected to a return conduit outlet and a supply chamber outlet connected to a control conduit inlet, A discharge chamber having a discharge chamber inlet connected to a control conduit outlet and a discharge chamber outlet connected to a return conduit inlet. Includes, A temperature control system is positioned to create a static pressure difference between the supply chamber outlet and the discharge chamber inlet, thereby generating flow through a regulating conduit. 2. A temperature control system according to Clause 1, comprising a return conduit and a pump configured to pump a regulating fluid from a discharge chamber to a supply chamber, wherein the return conduit is positioned to attenuate the propagation of fluid-excited vibrations generated by the pump to the regulating conduit. 3. The temperature control system according to Clause 1 or 2, wherein the supply chamber includes a first gas volume and the discharge chamber includes a second gas volume, and the first gas volume and the second gas volume have at least one volume of 0.5 liters. 4. The temperature control system according to clause 2 or 3, wherein the pressure of the first supply chamber and the pressure of the second discharge chamber are maintained at a pressure level lower than atmospheric pressure. 5. A temperature control system as described in any one of Clauses 2 to 4, wherein a regulating conduit is arranged to separate the liquid from at least a portion of the return conduit where the pump is located. 6. The temperature control system according to Clause 5, wherein a portion of the return conduit is separated from the control conduit by providing a first gas volume between the supply chamber inlet and the supply chamber outlet and / or a second gas volume between the discharge chamber inlet and the discharge chamber outlet. 7. The supply chamber has a first liquid level, the supply chamber inlet is located above the first liquid level, the supply chamber outlet is located below the first liquid level, and / or The temperature control system according to Clause 5 or 6, wherein the discharge chamber has a second liquid level, the discharge chamber inlet is located above the first liquid level, and the discharge chamber outlet is located below the second liquid level. 8. A temperature control system as described in any one of the preceding clauses, which is arranged to maintain a constant hydrostatic pressure difference between the supply chamber outlet and the discharge chamber inlet, and to maintain the first liquid level of the supply chamber at a constant height above the discharge chamber inlet. 9. The temperature control system according to Clause 8, wherein the supply chamber includes an overflow line for controlling a first liquid level. 10. The temperature control system according to Clause 9, wherein the overflow line includes a gas-liquid separator for separating gases mixed with the liquid flowing into the overflow line from the liquid. 11. A temperature control system as described in Clause 10, wherein the gas-liquid separator includes a liquid trap structure. 12. A temperature control system according to Clause 10 or 11, comprising a gas-liquid separator and a gas return conduit connected to the gas-liquid separator and the supply chamber, for allowing gas to return from the gas-liquid separator to the supply chamber. 13. A temperature control system according to any one of Clauses 10 to 12, wherein a porous material is provided in the flow channel of a gas-liquid separator to attenuate the flow through the channel. 14. A temperature control system according to any one of clauses 10 to 13, wherein the vertical distance between the gas-liquid separator and the supply chamber is less than 20% of the vertical distance between the first liquid level and the discharge chamber inlet. 15. The temperature control system according to Clause 8, wherein the first liquid level is controlled by a body that is vertically movable and partially extends into the regulated liquid of the supply chamber. 16. A temperature control system as described in any one of clauses 1 to 15, including a gas pressure controller for controlling the gas pressure levels of the supply chamber and the discharge chamber. 17. A temperature control system according to any one of Clauses 1 to 15, comprising a first gas pressure controller for controlling a first gas pressure in a supply chamber and a second gas pressure controller for controlling a second gas pressure level in a discharge chamber. 18. A temperature control system according to any one of Clauses 2 to 17, wherein the return conduit includes a first valve located downstream of the pump and a second valve located upstream of the pump, and the regulating conduit can separate liquid from a portion of the return conduit by closing the first valve and the second valve. 19. The temperature control system according to Clause 18, wherein the supply chamber includes a main supply chamber and an auxiliary supply chamber connected to each other via a first connecting conduit including a first connecting valve, and the discharge chamber includes a main discharge chamber and an auxiliary discharge chamber connected to each other via a second connecting conduit including a second connecting valve. 20. The temperature control system according to Clause 18, wherein the main supply chamber can separate liquid from a portion of the return conduit by closing a first valve and / or a first connecting valve and a second valve, and the main discharge chamber can separate liquid from a portion of the return conduit by closing a second valve and / or a second connecting valve. 21. A temperature control system according to any one of clauses 18 to 20, comprising a first gas pressure controller for controlling a first gas pressure in a supply chamber and a second gas pressure controller for controlling a second gas pressure level in a discharge chamber. 22. A temperature control system according to any one of the preceding clauses, wherein the supply chamber inlet and / or discharge chamber inlet each include an inlet flow damping device for reducing the flow rate to the supply chamber and the discharge chamber, respectively. 23. A temperature control system according to any one of the preceding clauses, wherein the regulating conduit, supply chamber and / or discharge chamber are at least partially filled with foamed material, porous material, mesh material and / or perforated material, or a plurality of substantially parallel channels are filled with foamed material, porous material, mesh material and / or perforated material, in order to reduce flow obstruction in the flow of the regulating fluid. 24. A temperature control system according to Clause 23, wherein foamed material, porous material, mesh material and / or perforated material or a plurality of substantially parallel channels are provided in or near locations where flow discontinuities exist, such as curves, constrictions and manifolds. 25. A temperature control system according to Clause 23 or 24, wherein foamed material, porous material, mesh material and / or perforated material or a plurality of substantially parallel channels are provided in the inlet area of ​​a supply chamber and / or in the inlet area of ​​a discharge chamber. 26. A temperature control system as described in any of the preceding clauses, including a damping device for reducing pressure fluctuations caused by acceleration of a portion of a liquid system due to vibration of machine components and / or floor vibration. 27. A lithography apparatus including a temperature control system as described in any of the preceding clauses, wherein the object is part of the lithography apparatus. 28. Lithography apparatus as described in Clause 27, wherein the object is a mirror element of the projection system. 29. A method for controlling the temperature of an object using a control liquid in a temperature control system, wherein the temperature control system is A regulating conduit for guiding a regulating fluid through or along an object, comprising a regulating conduit inlet and a regulating conduit outlet, A return conduit having a return conduit inlet and a return conduit outlet, A supply chamber having a supply chamber inlet connected to a return conduit outlet and a supply chamber outlet connected to a control conduit inlet, A discharge chamber having a discharge chamber inlet connected to a control conduit outlet and a discharge chamber outlet connected to a return conduit inlet. This is a method that includes, By creating a static pressure difference between the supply chamber outlet and the discharge chamber inlet, a flow is generated through the regulating conduit, Maintain the pressure of the first supply chamber and the pressure of the second discharge chamber at a pressure level lower than atmospheric pressure. Methods that include... 30. The method according to Clause 29, wherein the supply chamber includes a first gas volume and the discharge chamber includes a second gas volume, and the first gas volume and the second gas volume have a volume of at least 0.5 liters. 31. Simultaneously pump the regulating fluid from the discharge chamber to the supply chamber through the return conduit. A method described in Clause 29 or 30, including, A method in which a temperature control system is arranged to attenuate the propagation of fluid-induced vibrations generated by a pump to a control conduit. 32. The method according to any one of the clauses 29 to 31, comprising the step of maintaining a first liquid level in the supply chamber at a constant height above the discharge chamber inlet in order to maintain a constant hydrostatic pressure difference between the supply chamber outlet and the discharge chamber inlet. 33. The method according to Clause 32, wherein the step of maintaining the first liquid level in the supply chamber at a constant height above the discharge chamber inlet includes using an overflow line in the supply chamber. 34. The method according to Clause 33, comprising using a gas-liquid separator to deconvert gases mixed with the liquid flowing into the overflow line to reduce the liquid flow in the overflow line. 35. A method according to any one of the clauses 29 to 34, wherein the temperature control system includes a gas pressure controller for controlling the gas pressure levels of a supply chamber and a discharge chamber, the method comprising controlling the gas pressure levels of the supply chamber and the discharge chamber to a level lower than atmospheric pressure. 36. A method according to any one of the clauses 29 to 35, wherein the temperature control system includes a first gas pressure controller for controlling a first gas pressure in a supply chamber and a second gas pressure controller for controlling a second gas pressure level in a discharge chamber, the method comprising controlling the first gas pressure and the second gas pressure such that a static pressure difference is created between the supply chamber outlet and the discharge chamber. 37. A method according to any one of the paragraphs 29 to 36, wherein the return conduit includes a first valve located downstream of the pump and a second valve located upstream of the pump, the method comprising separating the liquid from a portion of the regulating conduit by closing the first valve and the second valve. 38. The method according to Clause 37, wherein the supply chamber includes a main supply chamber and an auxiliary supply sub-chamber connected to each other via a first connecting conduit including a first connecting valve, and the discharge chamber includes a main discharge chamber and an auxiliary discharge chamber connected to each other via a second connecting conduit including a second connecting valve, By closing the first and second valves while applying a static pressure difference between the supply chamber outlet and the discharge chamber inlet to create a flow from the supply chamber to the discharge chamber, the liquid is separated from a portion of the return conduit into the regulating conduit, and the first and second connecting valves are opened. By closing the first and second connecting valves while applying a static pressure difference between the supply chamber outlet and the discharge chamber inlet to create a flow from the main supply chamber to the main discharge chamber, the liquid is separated from a portion of the return conduit into the regulating conduit, and by opening the first and second valves, the regulating liquid is pumped from the auxiliary discharge chamber to the auxiliary supply chamber by a pump. A method that involves alternating between the two.

Claims

1. A temperature control system that uses a regulating liquid to adjust the temperature of an object, A regulating conduit for guiding a regulating fluid through or along the object, comprising a regulating conduit inlet and a regulating conduit outlet, A return conduit having a return conduit inlet and a return conduit outlet, A supply chamber having a supply chamber inlet connected to the return conduit outlet and a supply chamber outlet connected to the adjustment conduit inlet, A discharge chamber having a discharge chamber inlet connected to the adjustment conduit outlet and a discharge chamber outlet connected to the return conduit inlet, A gas pressure controller for controlling the gas pressure levels of the supply chamber and the discharge chamber. Includes, The first pressure in the supply chamber and the second pressure in the discharge chamber are maintained at a pressure level lower than atmospheric pressure. A temperature control system configured to maintain the first liquid level in the supply chamber at a constant height above the discharge chamber inlet in order to create a static pressure difference between the supply chamber outlet and the discharge chamber inlet, thereby generating a flow through the regulating conduit.

2. The return conduit includes a pump configured to pump the regulating fluid from the discharge chamber to the supply chamber, The temperature control system according to claim 1, further arranged to attenuate the propagation of fluid-excited vibrations generated by the pump to the control conduit.

3. The temperature control system is provided to separate the control conduit from the liquid in at least a portion of the return conduit in which the pump is located, The portion of the return conduit is separated from the control conduit by providing a first gas volume between the supply chamber inlet and the supply chamber outlet and / or by providing a second gas volume between the discharge chamber inlet and the discharge chamber outlet, and / or The supply chamber has a first liquid level, the supply chamber inlet is located above the first liquid level, the supply chamber outlet is located below the first liquid level, and / or The temperature control system according to claim 2, wherein the discharge chamber has a second liquid level, the discharge chamber inlet is positioned above the first liquid level, and the discharge chamber outlet is positioned below the second liquid level.

4. The supply chamber includes an overflow line for controlling the first liquid level, and / or The temperature control system according to any one of claims 1 to 3, wherein the first liquid level is controlled by a body that is vertically movable and partially extends into the regulated liquid of the supply chamber.

5. The temperature control system according to any one of claims 1 to 4, wherein the gas pressure controller comprises one gas pressure controller for controlling the gas pressure levels of the supply chamber and the discharge chamber.

6. The temperature control system according to any one of claims 1 to 4, wherein the gas pressure controller includes a first gas pressure controller for controlling a first gas pressure in the supply chamber and a second gas pressure controller for controlling a second gas pressure level in the discharge chamber.

7. The temperature control system according to claim 3, wherein the return conduit includes a first valve located downstream of the pump and a second valve located upstream of the pump, and the regulating conduit can separate liquid from the portion of the return conduit by closing the first valve and the second valve.

8. The temperature control system according to claim 7, wherein the supply chamber includes a main supply chamber and an auxiliary supply chamber connected to each other via a first connecting conduit including a first connecting valve, and the discharge chamber includes a main discharge chamber and an auxiliary discharge chamber connected to each other via a second connecting conduit including a second connecting valve.

9. The temperature control system according to claim 8, wherein the main supply chamber can separate liquid from the portion of the return conduit by closing the first valve and / or the first connecting valve and the second valve, and the main discharge chamber can separate liquid from the portion of the return conduit by closing the second valve and / or the second connecting valve.

10. The temperature control system according to any one of claims 7 to 9, wherein the gas pressure controller includes a first gas pressure controller for controlling a first gas pressure in the supply chamber and a second gas pressure controller for controlling a second gas pressure level in the discharge chamber.

11. The temperature control system according to any one of claims 1 to 10, wherein the supply chamber inlet and / or the discharge chamber inlet each include an inlet flow damping device for reducing the flow rate to the supply chamber and the discharge chamber.

12. A temperature control system according to any one of claims 1 to 11, wherein the regulating conduit, the supply chamber and / or the discharge chamber are at least partially filled with a foamed material, a porous material, a mesh material and / or a perforated material, or a plurality of substantially parallel channels are filled.

13. A lithography apparatus comprising a temperature control system according to any one of claims 1 to 12, wherein the object is a part of the lithography apparatus.

14. A method for controlling the temperature of an object using a control liquid in a temperature control system, wherein the temperature control system is A regulating conduit for guiding a regulating fluid through or along the object, comprising a regulating conduit inlet and a regulating conduit outlet, A return conduit having a return conduit inlet and a return conduit outlet, A supply chamber having a supply chamber inlet connected to the return conduit outlet and a supply chamber outlet connected to the adjustment conduit inlet, A discharge chamber having a discharge chamber inlet connected to the adjustment conduit outlet and a discharge chamber outlet connected to the return conduit inlet, A gas pressure controller for controlling the gas pressure levels of the supply chamber and the discharge chamber. Includes, The temperature control system is configured to maintain the first liquid level in the supply chamber at a constant height above the discharge chamber inlet. The method described above is A static pressure difference is created between the supply chamber outlet and the discharge chamber inlet to generate a flow through the regulating conduit, Maintain the first pressure in the supply chamber and the second pressure in the discharge chamber at a pressure level lower than atmospheric pressure. Methods that include...

15. This includes simultaneously pumping the adjustment fluid from the discharge chamber to the supply chamber through the return conduit, The temperature control system is arranged to attenuate the propagation of fluid-induced vibrations generated by the pump to the control conduit. The return conduit includes a first valve located downstream of the pump and a second valve located upstream of the pump, and the method includes separating the liquid from a portion of the return conduit by closing the first valve and the second valve, The supply chamber includes a main supply chamber and an auxiliary supply chamber connected to each other via a first connecting conduit including a first connecting valve, and the discharge chamber includes a main discharge chamber and an auxiliary discharge chamber connected to each other via a second connecting conduit including a second connecting valve, and the method is By closing the first valve and the second valve while applying a static pressure difference between the supply chamber outlet and the discharge chamber inlet to create a flow from the supply chamber to the discharge chamber, the liquid is separated from the portion of the return conduit into the regulating conduit, and the first connecting valve and the second connecting valve are opened. To create a flow from the main supply chamber to the main discharge chamber, a static pressure difference is applied between the supply chamber outlet and the discharge chamber inlet, and the first and second connecting valves are closed to separate the liquid from the portion of the return conduit into the regulating conduit, and the first and second valves are opened, and the regulating liquid is pumped from the auxiliary discharge chamber to the auxiliary supply chamber by the pump. The method according to claim 14, comprising performing the actions alternately.

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