Internal cooling actuator coil

Abstract

The present invention provides a fluid-cooled coil for use in an electromagnetic actuator of a lithography apparatus, the coil comprising: a coil formed of a plurality of electrically insulated flat wire coil conductors and configured to conduct electric current and generate an electromagnetic field during use; and at least one cooling fluid channel that makes thermal conductive contact with the coil to guide the flow of a cooling fluid to draw heat from the coil, wherein the cooling fluid channel is provided throughout the coil, traversing a plurality of the coil conductors.

Description

Technical Field

[0001] (Cross - reference to related applications)

[0001] This application claims the priority of European Application No. 23167210.6 filed on April 7, 2023 and European Application No. 23181744.6 filed on June 27, 2023, the entire contents of which are incorporated herein by reference.

[0002]

[0002] The present invention relates to a fluid - cooled coil for use in an electromagnetic actuator of a lithographic apparatus. The present invention further relates to an exposure apparatus, such as a lithographic apparatus, comprising such a coil, and to a method of manufacturing such a coil.

Background Art

[0003]

[0003] A lithographic apparatus is a machine configured to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus can project, for example, a pattern of a patterning device (e.g., a mask), often referred to as a “design layout” or “design”, onto a layer of radiation - sensitive material (resist) provided on a substrate (e.g., a wafer).

[0004]

[0004] As semiconductor manufacturing processes continue to advance, the dimensions of circuit elements have continuously decreased, while the amount of functional elements such as transistors per device has steadily increased over decades, following a trend commonly known as "Moore's Law." To keep up with Moore's Law, the semiconductor industry is pursuing technologies that enable the creation of increasingly smaller features. To project patterns onto a substrate, lithography equipment can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the feature that can be patterned on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. To form features smaller on a substrate than those produced by a lithography equipment using radiation with a wavelength of 193 nm, for example, a lithography equipment using extreme ultraviolet (EUV) radiation with wavelengths in the range of 4 nm to 20 nm, for example, 6.7 nm or 13.5 nm, can be used.

[0005]

[0005] Magnetic coils currently form the backbone of, for example, electromagnetic actuators. Such actuators are often used in exposure equipment, such as lithography equipment for manufacturing semiconductor products. These coils receive alternating current through their conductors, and these conductors are often called "windings" because they are typically manufactured by windings. The current passing through the coil induces an electromagnetic field, which can interact with magnets, such as permanent magnets, to cause mutual displacement between them.

[0006]

[0006] During use, the magnetic coil tends to heat up as a result of the electrical resistance of the current flowing through the coil, and therefore needs to be cooled. This is typically done by a cooling fluid, which flows along the coil through a cooling conduit, drawing heat from the coil into the cooling fluid. The cooling fluid is typically a liquid cooling fluid, but gaseous cooling fluids or evaporative cooling fluids are also used.

[0007]

[0007] In current coils, there are multiple material layers between the coil and the cooling fluid, and since these layers typically all have low thermal conductivity, cooling is quite inefficient. Examples of these include, starting with the coil, the coil winding insulation, the coil winding bonding layer, the coil potting, the electrical insulating foil, the insulating foil adhesive, and the cooling conduit material. In such current coils, it is usually preferable to keep the thermal resistance sufficiently low by making all these layers as thin as possible. However, limiting the thickness of the layers generates higher thermal shear stress, which can lead to delamination of the layers. Also, since known cooling conduits are typically made of conductive materials, this can increase the risk of electrical breakdown or short circuits between the coil and the cooling conduit. Furthermore, the direction of the heat path is aligned parallel to the path of the magnetic force between the coil and the magnet, which suggests that the accumulation of stress from thermal stress and magnetic force can lead to further delamination and overheating, as this delamination will further reduce thermal conductivity.

[0008]

[0008] As a potential solution, it is known to provide coils with hollow windings through which a cooling fluid can be passed and circulated. Although this may allow for more direct contact between the coil winding material and the cooling fluid, it has been found to be disadvantageous because it may result in a relatively large cooling fluid pressure drop due to the need for the cooling fluid to flow along the entire length of the coil winding, and a relatively low coil filling density, i.e., high electrical resistance and low current density. Also, the smallest manufacturable wire size and form factor that these hollow coils can have is too large for current applications. Finally, coating the inside of these long, thin wires with insulating, non-corrosive coating materials can be complicated.

[0009]

[0009] As a further alternative, it is known that the coil is directly submerged in the cooling fluid. However, these coils have the disadvantage that all the operating force from the coil must flow through the coil core, which can lead to high stress inside the coil and at the interface between the coil and the core. Furthermore, when the entire coil housing is filled with cooling fluid, relatively large stresses can be generated inside the housing due to high coolant pressure and pressure fluctuations induced by acceleration. [Overview of the project]

[0010]

[0010] In view of the above, an object of the present invention is to provide a coil that can be cooled with less heat loss by an improved method, and / or can operate at a higher current without overheating, and / or can be manufactured at a lower cost. A further object of the present invention is to provide an exposure apparatus equipped with such a coil, and a method for manufacturing such a coil.

[0011]

[0011] The present invention provides a fluid-cooled coil for use in an electromagnetic actuator of a lithography apparatus, the coil being formed of a plurality of electrically insulated flat wire coil conductors and configured to conduct electric current and generate an electromagnetic field during use, and comprising at least one cooling fluid channel that is in thermal conductive contact with the coil to guide the flow of a cooling fluid to draw heat from the coil, wherein the cooling fluid channel is provided throughout the coil, traversing the plurality of coil conductors.

[0012]

[0012] According to the present invention, a coil is formed of conductors through which electric current can pass and be guided. These conductors are sometimes referred to as windings, considering that coils can be manufactured by winding wires into a ring shape to obtain a conductor. Alternatively, the present invention also envisions so-called "hairpin" type coils, in which the coil is assembled from various individual interconnected conductors.

[0013]

[0013] The coil of the present invention is made of flat wire coil conductors, which should be understood as adjacent conductors or windings being in contact with each other over a relatively large width compared to their thickness in the stacking direction of the coil. Compared to other coils, for example, in which the conductors may have a circular cross-section, flat wire coil conductors can offer the advantage of already being able to improve heat transfer between individual conductors, i.e., in the stacking direction. Furthermore, flat wire coil conductors can allow more conductors to be present in the same cross-section compared to circular windings, which can reduce electrical resistance and reduce the required voltage across the coil and heat loss in the coil. In addition, the individual conductors are electrically insulated from each other to prevent short circuits from occurring between them.

[0014]

[0014] Cooling fluid channels within the coil are configured to guide the cooling fluid, so that heat from the coil conductors can be conducted to the cooling fluid. The present invention adds that the cooling fluid channels are provided throughout the coil, which suggests that during use, the cooling fluid flows through recesses or holes in the coil, and that the cooling fluid comes into direct contact with the coil conductors only through a relatively thin coil coating applied to the conductors within the cooling fluid channels.

[0015]

[0015] The coil of the present invention may be manufactured by machining the coil to form cooling fluid channels inside. This may be done, for example, by forming open grooves in the coil conductors or by drilling through the coil conductors, through which the cooling fluid can be guided.

[0016]

[0016] The cooling fluid channel is provided through multiple conductors, so that the cooling fluid is in direct contact with two or more conductors. This can improve cooling efficiency as it no longer requires heat to dissipate between conductors before it can dissipate into the cooling fluid.

[0017]

[0017] Preferably, the cooling fluid channels extend substantially throughout all coil conductors so that heat can be directly drawn from each conductor into the cooling fluid, which can further improve the cooling efficiency of the coil.

[0018]

[0018] The coil of the present invention, having direct contact between the cooling fluid and the conductor, can provide up to a four-fold improvement in cooling because the thermal path between the coil conductor and the cooling fluid is shortened. The thermal path of the coil of the present invention goes from the coil conductor to the coil insulator and then to the cooling fluid. In addition, the surface area of ​​the coil in contact with the cooling fluid can be increased for the same coil volume, which also improves cooling.

[0019]

[0019] Furthermore, the coil of the present invention can operate at higher temperatures. In existing coils, thermal stress arising from the difference in thermal expansion coefficients between the coil and the cooling plate caused delamination of the layer between the coil and the cooling plate. In the coil of the present invention, the direction of thermal shear stress and thermal paths is different from the force paths, which prevents thermal stress and magnetic coil forces from contributing to coil delamination and allows for a greater force density within the coil.

[0020]

[0020] Furthermore, the coil of the present invention no longer requires a separate cooling conduit beside the coil, which can provide more space for the coil within the electromagnetic actuator and may further contribute to the improved higher force density. Finally, the absence of a cooling plate allows the coil to be positioned closer to the magnet of the electromagnetic actuator, which may also increase the force density. The overall combination of the above improvements may lead to an increase of more than twofold in the magnetic force density.

[0021]

[0021] In addition, the absence of coils located in close proximity to the cooling conduits reduces the risk of electrical failure. Furthermore, the absence of cooling fluid passing through the electromagnetic actuator housing or cooling conduits, for example, water or other non-conductive materials, avoids the risk of stress corrosion cracking, so different materials such as ceramic materials can be used in the manufacture of the actuator housing. This can further contribute to avoiding the risk of electrical failure.

[0022]

[0022] In one embodiment of the present invention, the coil conductors extend within the coil plane. The coil conductors may be arranged adjacent to each other in the stacking direction, and they may be aligned within the coil plane so that a circular, rectangular, or so-called “racetrack-shaped” coil is obtained. In such a coil, the cooling fluid channels may extend throughout the coil in a direction having at least one component substantially parallel to the coil plane. Alternatively, however, the stacking direction may be aligned perpendicular to the coil plane, i.e., to form an “edge-wound” type coil, and the cooling fluid channels may extend throughout the coil in a direction having at least one component substantially perpendicular to the coil plane. In either example, the cooling fluid channels may extend parallel to the stacking direction of the coil, or may have at least one component extending parallel to the stacking direction of the coil.

[0023]

[0023] In one embodiment, the cooling fluid channel is formed by at least one hole that traverses the coil conductor. The hole may be defined entirely inside the coil conductor, so that the cooling fluid can contact the conductor around the entire circumference of the hole. The hole extends traverse the coil, i.e., parallel to the stacking direction, and typically extends through all conductors, in order to effectively draw heat from all conductors. Optionally, the coil may have multiple holes that extend adjacent to one another so that heat can be drawn from multiple different locations within each conductor.

[0024]

[0024] In an alternative embodiment, the cooling fluid channel is formed by at least one groove extending over the entire coil conductor on the inner surface, outer surface, or head end face of the coil. These grooves are open, for example, having a rectangular or rounded cross-section, and are formed on each surface of the coil conductor, i.e., so that the cooling fluid can come into contact with the conductor on three sides. The inner surface can be defined as the surface within the central opening of the coil, the outer surface can be defined as surrounding the outermost conductor, and the head end face of the coil can be provided at the head ends of the coil facing each other in the stacking direction.

[0025]

[0025] In one embodiment, the grooved cooling fluid channel may be provided with a cover element which is provided to cover the open groove in order to provide an enclosed cooling fluid channel and prevent leakage of the cooling fluid.

[0026]

[0026] In one embodiment, a plurality of coils, for example two coils, may be provided, which may be arranged adjacent to each other, with the coil planes of the coils extending parallel to each other, so that the coils together can generate a combined magnetic field. The coils may be arranged adjacent to each other at the head end faces, and they may be electrically insulated from each other via an electrical insulating layer, and a cooling fluid channel is formed by combining the grooves of each coil. The grooves of the opposing coils also face each other, so that these grooves together define a fluid flow path for the cooling fluid, and both coils can be cooled through a single flow of the cooling fluid.

[0027] Alternatively, the plurality of coils may be concentric with each other, i.e., the inner coil may be disposed within the central opening of the outer coil. Thereby, the inner surface of the outer one of the coils and the outer surface of the inner one of the coils contact each other through an electrical insulation layer. In this embodiment, the grooves of the coils face each other, for example, the inner groove on the inner surface of the outer coil faces the outer groove on the outer surface of the inner coil, and as a result, these grooves together define a cooling fluid channel for the cooling fluid, and both coils can be cooled through a single flow of the cooling fluid. In any of these embodiments, cooling can be conveniently and efficiently established for the plurality of coils using a single but shared cooling fluid channel, which can further improve the cooling efficiency and further reduce the cost.

[0028]

[0028] In cross-section, the groove may have a depth perpendicular to the surface in which the groove is defined, but this depth is relatively shallow compared to the width of the groove. Although a groove having such a cross-section can effectively draw heat from the coil, it may cause a relatively large stress between the opposing coils as a result of the hydraulic fluid pressure of the cooling fluid in the opposing grooves, i.e., the wide grooves. Alternatively, the groove may be relatively deep compared to its width, and as a result, the stress induced at the interface between the conductor and the cooling fluid circuit, i.e., resulting from the hydraulic fluid pressure, can be smaller. Further, when viewed along the surface in which the groove is defined, the spacing between adjacent grooves may be adjusted to adjust the stress resulting from the hydraulic fluid pressure and the cooling capacity of the cooling fluid.

[0029]

[0029] In one embodiment, the coil comprises a coating on the coil conductor within the cooling fluid channel. The coating may be disposed on the surface defining the cooling fluid channel and can serve various purposes, for example, a corrosion-resistant coating, an electrical insulation coating, and / or a sealing coating to prevent leakage of the cooling fluid.

[0030]

[0030] For example, the coating may comprise a plurality of different coating layers. For example, the coating may comprise one or more ceramic coating layers made of a ceramic material. As an example, the ceramic coating layer may be made of diamond-like carbon (DLC) or aluminum nitride, and these ceramic materials have been found to have desirable corrosion resistance, electrical insulation, and thermal conductivity properties. Additionally or alternatively, the coating may comprise one or more polymer coating layers made of, for example, parylene. The ceramic coating may have pinholes therein, and since those pinholes can be filled with a polymer material, the polymer coating layer may be beneficial in addition to the ceramic coating layer. The one or more polymer coating layers may be applied on top of the one or more ceramic coating layers, or directly on the coil conductor, for example, under the ceramic coating layer, i.e., as an intermediate layer to improve the adhesion of the ceramic coating layer. Additionally or alternatively, the coating may comprise a multilayer coating comprising one or more polymer layers made of, for example, parylene and one or more atomic layer deposition (ALD) coatings made of an inorganic material such as aluminum oxide, titanium oxide, and hafnium oxide.

[0031]

[0031] In one embodiment, the coil further comprises a cooling fluid connector fluidly connected to a cooling fluid channel, the cooling fluid connector being connectable to an external cooling fluid source, the cooling fluid connector being disposed within a central opening of the coil and surrounded by the coil conductor. The cooling fluid connector is configured to receive a cooling fluid flow from a cooling fluid source and to guide the cooling fluid flow into the cooling fluid channel. Advantageously, the cooling fluid connector can be housed within the central opening of the coil, such that the outer surface of the coil is substantially exposed, such that the magnet of the electromagnetic actuator can be positioned close to the coil, or the volume of the coil can be increased with the same housing size. However, alternatively, the cooling fluid connector may be positioned outside the coil.

[0032]

[0032] In one embodiment, the cooling fluid channel traces an annular path throughout the coil and extends circumferentially along the coil conductors. This allows the cooling fluid channel to substantially follow the path of the conductors. This may be beneficial when the coil is embodied as a racetrack coil where all conductors are in a single coil plane.

[0033]

[0033] In an alternative embodiment, the cooling fluid channel traces a meandering reciprocating path throughout the coil. The meandering path may suggest that the cooling fluid channel may extend across various coil conductors to contact a number of conductors at a relatively large number of locations along the conductor path in order to improve cooling efficiency. In one embodiment, the cooling fluid channel is subdivided into at least one supply section and at least one return section fluid-connected in series, the at least one supply section and at least one return section extending adjacent to each other through the coil, the at least one supply section and at least one return section being antiparallel to each other, so that the direction of flow of the cooling fluid in at least one supply section is opposite to the direction of flow of the cooling fluid in at least one return section. The supply section and return section extend adjacent to each other, so that a counterflow heat exchanger can be obtained at each point along the cooling fluid path. The cooling fluid in the supply section just out of the cooling fluid source may be relatively cold, while the cooling fluid in the return section that has passed through the coil over a longer length may be relatively warm. The net cooling fluid temperature, i.e., the combined temperature of the cooling fluid flow in the supply and return sections, can be relatively constant over the length of the cooling fluid channel, which can provide a more uniform extraction of heat from the conductor. The supply and return sections can be fluidly interconnected in series by reversal turns at their ends.

[0034]

[0034] In a further embodiment, the coil comprises two supply sections and one return section, the return section being located in the center between the two supply sections. At any point along the length of the cooling fluid channel, the return section is surrounded on both sides by the supply sections. The outermost part of the cooling fluid channel contains the cooling fluid at the lowest temperature during use. This may be beneficial in the outermost or innermost edge conductors of the coil, as these conductors may not be able to cross the cooling fluid channel, i.e., if embodied as grooves, this could cause leakage. For this reason, the edge conductors are positioned in close proximity to the coldest cooling fluid in the supply section located outside the return section to maximize cooling in the edge conductors.

[0035]

[0035] In an alternative embodiment, the cooling fluid channel may extend mainly along the coil conductors, forming a reciprocating side step across a smaller number of the various coil conductors, e.g., two or three, to create turbulence in the cooling fluid flow, which can diffuse the current density and heat generation across the coil conductors and improve the cooling effect. The cooling fluid channel is subdivided into at least one supply section and at least one return section, which are fluidly connected in series. Preferably, the supply section is located as the innermost and outermost parts of the cooling fluid channel, so that the innermost and outermost parts of the cooling fluid channel contain the cooling fluid at the lowest temperature during use. This may be beneficial at the outermost or innermost edge conductors of the coil, as these conductors may not be able to cross the cooling fluid channel, i.e., if embodied as grooves, this may cause leakage. For this reason, the edge conductors are located in close proximity to the coldest cooling fluid in the supply section located outside the return section to maximize cooling at the edge conductors. To efficiently deliver and receive the cooling fluid spatially, the coolant manifold may be optionally positioned within the coil core.

[0036]

[0036] In an alternative embodiment, at least one feeder and at least one returner trace a double helix path through the coil. The feeder and returner still extend side by side with each other, but substantially follow a helical path of the conductor.

[0037]

[0037] In one embodiment, the flat wire coil conductors have, for example, an elongated rectangular cross-section perpendicular to the stacking direction. Thus, the relatively longer sides of the conductors are in contact with each other, while the shorter sides of the conductors form the head end of the coil. This can be beneficial for cooling the coil because the large adjacent interfaces between the conductors can allow for a relatively large degree of mutual heat exchange between the conductors, and the distance between each winding and the cooling fluid circuit can be minimized while still having conductors with sufficiently large cross-sections.

[0038]

[0038] In yet another embodiment, the elongated coil perpendicular to the stacking direction has a rectangular shape with rounded corners when viewed along the stacking direction. The cooling fluid channels may be arranged to extend across the coil conductors in a direction substantially perpendicular to the coil plane and therefore parallel to the stacking direction, typically extending through all conductors. The cooling fluid channels may be formed by holes having a circular cross-section. The holes may be evenly spaced along the outer circumference of the conductors or along the length of each side of the rectangular conductor. The holes may be drilled through the coil conductors. The cooling fluid may be supplied to and returned from the opposing head end faces of the coil.

[0039]

[0039] In an alternative embodiment, an elongated coil perpendicular to the stacking direction has a rectangular shape with rounded corners when viewed along the stacking direction. V-shaped cooling fluid channels may be arranged to extend throughout the coil in a plane parallel to the stacking direction, typically extending through all conductors. The V-shaped cooling fluid channel comprises a supply section and a return section, thereby supplying and returning the cooling fluid to the same head end face of the coil. V-shaped cooling fluid channels may be provided on each side of the coil. Two or more V-shaped cooling fluid channels may be arranged on one or more sides of the coil. The cooling fluid channels may be in a shape other than V-shape to achieve a similar cooling effect. The cooling fluid channels may be formed by holes having a circular cross-section. The holes may be formed by drilling through various coil conductors, and the drilling process may form a fluid connection point, thereby fluidly connecting the supply section and the return section.

[0040]

[0040] In one exemplary embodiment, the rectangular cross-section of the flat wire coil conductor may be substantially square.

[0041]

[0041] The present invention further provides an exposure apparatus, for example a lithography apparatus, comprising a coil disclosed herein. The exposure apparatus, i.e., its coil, may have one or more of the features and / or advantages disclosed herein with respect to the coil according to the present invention, as described, for example, in the claims. The coil may be used as an electromagnetic actuator in the exposure apparatus, or alternatively or additionally as a linear actuator, rotary actuator, inductor, transformer, inverter, etc.

[0042]

[0042] Finally, the present invention provides a method for manufacturing a coil disclosed herein, the method which is The steps include forming a coil from multiple flat wire coil conductors, The method comprises the step of forming a cooling fluid channel throughout the coil. The method, i.e., the coil manufactured by the method, may have one or more of the features and / or advantages disclosed herein with respect to the coil according to the present invention, as described, for example, in the claims.

[0043]

[0043] This method may be advantageous as a result of forming a cooling fluid channel within the coil, instead of relying on a separate cooling conduit that needs to be joined to the coil, as in the case of current manufacturing methods. The formation of the cooling fluid channel is preferably, though not necessarily, carried out after the formation of the coil. This coil formation may involve winding a flat wire coil conductor, i.e., obtaining a coil with windings, but alternatively, it may involve forming a hairpin coil by assembling several separate interconnected conductor sections to form a coil.

[0044]

[0044] In one embodiment, the method further comprises the step of joining coil conductors to hold them together. This optional joining may improve the structural rigidity of the coil but is not essential for forming cooling fluid channels throughout the coil.

[0045]

[0045] In one embodiment, the step of forming a cooling fluid channel comprises removal manufacturing of the cooling fluid channel, for example, laser ablation, etching, drilling, milling, or spark erosion. During removal manufacturing, material is removed from the coil, thereby obtaining the cooling fluid channel.

[0046]

[0046] In one embodiment, the step of forming a cooling fluid channel comprises drilling at least one hole across a plurality of, for example, all of the coil conductors. The drilled cooling fluid hole may be completely surrounded by the coil conductors, so that the cooling fluid can come into contact with the conductors around the entire circumference of the hole. The hole extends across the coil, i.e., parallel to the stacking direction, and typically extends through all of the conductors, in order to effectively draw heat from all of the conductors. Optionally, this method comprises the step of drilling a plurality of holes through the coil that extend adjacent to one another, so as to provide a coil that can draw heat at a plurality of different locations within each conductor.

[0047]

[0047] In an alternative embodiment, the step of forming a cooling fluid channel comprises milling at least one groove through the coil conductor. The milled groove in the coil is open and has, for example, a rectangular cross-section and is formed on each surface of the coil conductor, so that the cooling fluid comes into contact with the conductor over the largest possible surface area.

[0048]

[0048] In one embodiment, the method further comprises the step of applying a coating on a coil conductor in a cooling fluid channel, for example by physical vapor deposition and / or (plasma-enhanced) chemical vapor deposition. The coating may comprise one or more ceramic coating layers made of a ceramic material. For example, the ceramic coating layer may be made of diamond-like carbon (DLC) or aluminum nitride, and these ceramic materials can be appropriately coated onto a surface by vapor deposition. Additionally or alternatively, the coating may comprise one or more polymer coating layers made of, for example, parylene, which can be applied on the coil conductor or on one or more ceramic coating layers. Additionally or alternatively, the coating may comprise a multilayer coating comprising one or more polymer layers made of, for example, parylene and one or more atomic layer deposition (ALD) coatings made of inorganic materials such as aluminum oxide, titanium oxide, and hafnium oxide. [Brief explanation of the drawing]

[0049]

[0049] Embodiments of the present invention will be described below as merely illustrative examples with reference to the attached schematic diagrams.

[0050] [Figure 1] This shows a schematic overview of a lithography apparatus. [Figure 2] Figure 1 shows a detailed view of a part of the lithography apparatus. [Figure 3] A schematic diagram of the position control system is shown. [Figure 4] A plan view of one embodiment of the coil according to the present invention is shown. [Figure 5] A plan view of one different embodiment of the coil is shown. [Figure 6] A plan view of one different embodiment of the coil is shown. [Figure 7] A side view of one embodiment of the coil is shown. [Figure 8] A side view of one different embodiment of the coil is shown. [Figure 9] A plan view of another embodiment of the coil is shown. [Figure 10] A perspective cross-sectional view of another embodiment of the coil is shown. [Figure 11] Figure 9 shows a cross-sectional view of the coil along line AA. [Figure 12] A perspective cross-sectional view of an alternative embodiment of the coil is shown. [Figure 13] A cross-sectional view of a further alternative embodiment of the coil is shown. [Figure 14] A cross-sectional view of another embodiment of the coil is shown. [Figure 15] A perspective view of a further alternative embodiment of the coil is shown. [Figure 16] A perspective view of a further alternative embodiment of the coil is shown. [Figure 17] A perspective view of another embodiment of the coil is shown. [Figure 18] A plan view of another embodiment of the coil is shown. [Figure 19(a)] A perspective view of another embodiment of the coil is shown. [Figure 19(b)] Figure 19(a) shows a cross-sectional perspective view of the coil along line 19B-19B. [Figure 20(a)] A perspective view of a further alternative embodiment of the coil is shown. [Figure 20(b)] Figure 20(a) shows a cross-sectional perspective view of the coil along line 20B-20B. [Modes for carrying out the invention]

[0051]

[0050] In this document, the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g., having wavelengths of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and EUV (extreme ultraviolet radiation, e.g., having wavelengths in the range of about 5 to 100 nm).

[0052]

[0051] The terms “reticle,” “mask,” or “patterning device,” as used herein, may be broadly interpreted to refer to a general-purpose patterning device that can be used to give an incoming radiation beam a patterned cross-section corresponding to a pattern created on a target portion of a substrate. The term “light bulb” can also be used in this context. 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.

[0053]

[0052] Figure 1 schematically shows 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 connected to a first positioner PM built to support a patterning device (e.g., a mask) MA and configured to precisely position the patterning device MA according to specific parameters, a substrate support (e.g., a wafer table) WT built to hold a substrate (e.g., a resist-coated wafer) W and connected to a second positioner PW built 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., comprising one or more dies).

[0054]

[0053] 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, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for inducing, shaping, and / or controlling the radiation. The illuminator IL may be used to adjust the radiant beam B so that its cross-section has a desired spatial and angular intensity distribution in the plane of the patterning device MA.

[0055]

[0054] As used herein, the term “projection system” PS should be interpreted broadly to encompass a variety of projection systems, including refractive optical systems, reflective optical systems, reflective-refractory optical systems, anamorphic optical systems, magneto-optical systems, electromagnetic optical systems, and / or electrostatic optical systems, or any combination thereof, as appropriate in accordance with the exposure radiation used and / or other factors such as the use of immersion liquid or vacuum. Where the term “projection lens” is used herein, it can be considered synonymous with the more general term “projection system” PS.

[0056]

[0055] The lithography apparatus LA may be of a type that can cover at least a portion of the substrate with a liquid having a relatively high refractive index, such as water, to fill the space between the projection system PS and the substrate W. This is also known as immersion lithography. Further information relating to immersion technology is given in U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0057]

[0056] The lithography apparatus LA may be of a type having two or more substrate support WTs (also called a “dual-stage”). In such a “multi-stage” machine, the substrate support WTs may be used in parallel, and / or, while another substrate W on another substrate support WT is being used to expose a pattern on the other substrate W, a preparation step for subsequent exposure of the substrate W located on one of the substrate support WTs may be performed on the substrate W.

[0058]

[0057] 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 a cleaning device. The sensors may be positioned to measure the characteristics of the projection system PS or the characteristics of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning device may be positioned to clean a part of the lithography apparatus, for example, a part of the projection system PS or a part of the system that provides the immersion fluid. The measurement stage may move below the projection system PS when the substrate support WT is away from the projection system PS.

[0059]

[0058] During operation, the radiating beam B is incident on a patterning device MA, such as a mask, which is held on a mask support MT, and a pattern is formed by the pattern (design layout) present on the patterning device MA. The radiating beam B, having crossed the patterning device MA, passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. Using a second positioner PW and a position measuring system PMS, the substrate support WT can be precisely moved to position, for example, various target portions C in a focused and aligned position within the path of the radiating beam B. Similarly, using a first positioner PM and optionally another position sensor (not explicitly shown in Figure 1), the patterning device MA can be precisely positioned 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, P2 occupy dedicated target portions in the illustration, but may be located in the space between target portions. When substrate alignment marks P1 and P2 are located between target portions C, they are known as scribe line alignment marks.

[0060]

[0059] To clarify the present invention, the Cartesian coordinate system is used. The Cartesian coordinate system has three axes, namely the x-axis, y-axis, and z-axis. Each of the three axes is orthogonal to the other two axes. A rotation about the x-axis is called the Rx rotation. A rotation about the y-axis is called the Ry rotation. A rotation about the z-axis is called the Rz rotation. The x-axis and y-axis define the horizontal plane, while the z-axis is perpendicular. The Cartesian coordinate system is not limiting to the present invention, but is used only for clarification. Alternatively, another coordinate system, such as the cylindrical coordinate system, may be used to clarify the present invention. The orientation of the Cartesian coordinate system may be different, for example, such that the z-axis has a component along the horizontal plane.

[0061]

[0060] Figure 2 shows a more detailed view of a part of the lithography apparatus LA of Figure 1. The lithography apparatus LA may comprise a base frame BF, a balance mass BM, a metrology frame MF, and a vibration isolation system IS. The metrology frame MF supports the projection system PS. The metrology frame MF may also support a part of the position measurement system PMS. The metrology frame MF is supported by the base frame BF via the vibration isolation system IS. The vibration isolation system IS is positioned to prevent or reduce the propagation of vibrations from the base frame BF to the metrology frame MF.

[0062]

[0061] The second positioner PW is positioned to accelerate the substrate support WT by providing a driving force between the substrate support WT and the balance mass BM. The driving force accelerates the substrate support WT in the desired direction. Due to the conservation of momentum, the driving force is also applied to the balance mass BM on the same scale, but in the opposite direction to the desired direction. Typically, the mass of the balance mass BM is significantly larger than the mass of the second positioner PW and the moving parts of the substrate support WT.

[0063]

[0062] In one embodiment, the second positioner PW is supported by a balance mass BM. For example, in this case, the second positioner PW includes a planar motor for levitating the substrate support WT above the balance mass BM. In another embodiment, the second positioner PW is supported by a base frame BF. For example, in this case, the second positioner PW includes a linear motor and a bearing such as a gas bearing for levitating the substrate support WT above the base frame BF.

[0064]

[0063] The position measurement system PMS may include any type of sensor suitable for determining the position of the substrate support WT. The position measurement system PMS may include any type of sensor suitable for determining the position of the mask support MT. The sensor may be an optical sensor such as an interferometer or an encoder. The position measurement system PMS may include a combined system of an interferometer and an encoder. The sensor may be another type of sensor, such as a magnetic sensor, a capacitive sensor, or an inductive sensor. The position measurement system PMS may determine the position relative to a reference, such as a metrology frame MF or a projection system PS. The position measurement system PMS may determine the position of the substrate table WT and / or mask support MT by measuring the position or by measuring the time derivative of the position, such as velocity or acceleration.

[0065]

[0064] The position measurement system (PMS) may include an encoder system. An encoder system is known, for example, from U.S. Patent Application No. 2007 / 0058173A1, filed on September 7, 2006, which is incorporated herein by reference. The encoder system comprises an encoder head, a grating, and a sensor. The encoder system can receive a primary radiation beam and a secondary radiation beam. Both the primary and secondary radiation beams originate from the same radiation beam, i.e., the original radiation beam. At least one of the primary and secondary radiation beams is produced by diffracting the original radiation beam through a grating. If both the primary and secondary radiation beams are produced by diffracting the original radiation beam through a grating, the primary radiation beam must have a different diffraction order than the secondary radiation beam. Different diffraction orders are, for example, +1, -1, +2, and -2. The encoder system optically combines the primary and secondary radiation beams to form a combined radiation beam. A sensor in the encoder head determines the phase or phase difference of the combined radiation beam. The sensor generates a signal based on its phase or phase difference. The signal represents the position of the encoder head relative to the grid. Either the encoder head or the grid may be placed on a substrate structure WT. The other of the encoder head or grid may be placed on a metrology frame MF or a base frame BF. For example, multiple encoder heads may be placed on a metrology frame MF, while one grid is placed on the upper surface of a substrate support WT. In another example, one grid is placed on the bottom surface of a substrate support WT, and one encoder head is placed below the substrate support WT.

[0066]

[0065] The position measurement system PMS may include an interferometer system. Interferometer systems are known, for example, from U.S. Patent No. 6020964, filed July 13, 1998, which is incorporated herein by reference. An interferometer system may include a beam splitter, mirrors, a reference mirror, and a sensor. The radiated beam is split by the beam splitter into a reference beam and a measurement beam. The measurement beam propagates to the mirrors, is reflected by the mirrors and returns to the beam splitter. The reference beam propagates to the reference mirrors, is reflected by the reference mirrors and returns to the beam splitter. In the beam splitter, the measurement beam and the reference beam are combined to form a combined radiated beam. The combined radiated beam is incident on the sensor. The sensor determines the phase or frequency of the combined radiated beam. The sensor generates a signal based on its phase or frequency. The signal represents the displacement of the mirror. In one embodiment, the mirrors are connected to a substrate support WT. The reference mirror may be connected to a metrology frame MF. In one embodiment, the measurement beam and the reference beam are combined into a combined emission beam by an additional optical component rather than a beam splitter.

[0067]

[0066] The first positioner PM may comprise a long-stroke module and a short-stroke module. The short-stroke module is positioned to move the mask support MT over a small range of movement with high precision relative to the long-stroke module. The long-stroke module is positioned to move the short-stroke module over a large range of movement with relatively low precision relative to the projection system PS. The combination of the long-stroke module and the short-stroke module allows the first positioner PM to move the mask support MT over a large range of movement with high precision relative to the projection system PS. Similarly, the second positioner PW may comprise a long-stroke module and a short-stroke module. The short-stroke module is positioned to move the substrate support WT over a small range of movement with high precision relative to the long-stroke module. The long-stroke module is positioned to move the short-stroke module over a large range of movement with relatively low precision relative to the projection system PS. The combination of the long-stroke module and the short-stroke module allows the second positioner PW to move the substrate support WT over a large range of movement with high precision relative to the projection system PS.

[0068]

[0067] The first positioner PM and the second positioner PW each include an actuator for moving the mask support MT and the substrate support WT, respectively. The actuator may be a linear actuator for providing driving force along a single axis, for example, the y-axis. Multiple linear actuators may be used to provide driving force along multiple axes. The actuator may be a planar actuator for providing driving force along multiple axes. For example, a planar actuator may be arranged to move the substrate support WT with 6 degrees of freedom. The actuator may be an electromagnetic actuator comprising at least one coil and at least one magnet. The actuator is arranged to move at least one coil relative to at least one magnet by applying current to at least one coil. The actuator may be a movable magnet actuator, which has at least one magnet coupled to the substrate support WT or the mask support MT. The actuator may be a movable coil actuator, which has at least one coil coupled to the substrate support WT or the mask support MT. The actuator may be a voice coil actuator, a reluctance actuator, a Lorentz actuator, or a piezo actuator, or any other suitable actuator.

[0069]

[0068] The lithography apparatus LA is equipped with a position control system PCS, as schematically shown in Figure 3. The position control system PCS comprises a setpoint generator SP, a feedforward controller FF, and a feedback controller FB. The position control system PCS provides a drive signal to the actuator ACT. The actuator ACT may be the actuator of a first positioner PM, or it may be the actuator of a second positioner PW. The actuator ACT drives a plant P, which may be equipped with a substrate support WT or a mask support MT. The output of the plant P is a position quantity, such as position, velocity, or acceleration. The position quantity is measured by a position measuring system PMS. The position measuring system PMS generates a signal, which is a position signal representing the position quantity of the plant P. The setpoint generator SP generates a signal, which is a reference signal representing a desired position quantity of the plant P. For example, the reference signal represents a desired trajectory of the substrate support WT. The difference between the reference signal and the position signal forms the input to the feedback controller FB. Based on that input, the feedback controller FB provides at least a portion of the drive signal for the actuator ACT. A reference signal may form the input to a feedforward controller FF. Based on this input, the feedforward controller FF provides at least a portion of the drive signal for the actuator ACT. The feedforward FF may utilize information about the mechanical properties of the plant P, such as mass, stiffness, resonance mode, and natural frequency.

[0070]

[0069] Figure 4 shows a first embodiment of a coil according to the present invention, which is referred to by reference numeral 1. The coil 1 comprises a plurality of coil conductors 10, i.e., windings, which are formed from a plurality of electrically insulated flat wires. In the schematic representation of Figure 4, the coil 1 comprises five conductors 10, but it should be understood that in practice, a coil can comprise a much larger number of conductors.

[0071]

[0070] All coils shown in the figures have a coil conductor, which is manufactured by winding a wire into a ring to obtain a conductor. For this reason, the coil conductor is sometimes referred to as the "winding" of the coil. Alternatively, the present invention also envisions a so-called "hairpin" type coil, in which the coil is assembled from various individual interconnected conductors.

[0072]

[0071] The coil conductor 10 is configured to conduct current and generate an electromagnetic field during use. The plane of Figure 4 is aligned parallel to the coil plane of the coil conductor 10, and the electromagnetic field is emitted from this coil 1 in a direction perpendicular to the coil plane and the plane of Figure 4. The coil conductors 10 are arranged adjacent to each other in the stacking direction S aligned within the coil plane to obtain a so-called "racetrack type" coil. In fact, although the coil conductors 10 are shown as concentric rings in the figure for clarity, the coil conductors may actually form a helical path as a whole.

[0073]

[0072] The coil 1 of the present invention is made of flat wire coil conductors 10, where the term “flat wire” should be understood to mean that adjacent conductors 10 are in contact with each other over a large width relative to each other, i.e., compared to their thickness in the stacking direction S. In the representation in Figure 4, the conductors 10 have a large height in the direction perpendicular to the coil plane and the plane of the drawing, compared to their thickness in the stacking direction S. Compared to other coils, for example, in which the conductors may have a circular cross-section, flat wire coil conductors can offer the advantage that heat transfer in the stacking direction S between individual conductors 10 is already improved.

[0074]

[0073] The coil 1 further comprises a cooling fluid channel 20 extending throughout the coil 1 in a direction substantially parallel to the coil plane. The cooling fluid channel 20 is formed by a plurality of holes 21 extending across all of the coil conductors 10. The cooling fluid channel 20 is in thermal conduction contact with the coil conductors 10. During use, a flow F of cooling fluid is guided through the cooling fluid channel 20, and as a result, heat from the coil conductors can be transferred to the cooling fluid.

[0075]

[0074] In the coil 1 shown in Figure 4, the cooling fluid extends in a reciprocating path through the cooling fluid channel 20. Thus, the direction of the cooling fluid flow is reversed between adjacent holes 21, as indicated by the arrows in Figure 4, and as a result, the cooling fluid flows in opposite directions in adjacent holes 21. This suggests that all holes 21 in the coil 1 are fluidly connected in series.

[0076]

[0075] Figure 5 shows an alternative embodiment of the coil 101, in which, as in Figure 4, the cooling fluid channel 120 is formed by adjacent through holes 121. However, in the embodiment of Figure 5, the directions of the cooling fluid flow F in each of the holes 121 are aligned parallel to each other, which suggests that all the holes 121 in the coil 101 extend parallel through the coil conductor 110.

[0077]

[0076] Figure 6 shows a further alternative embodiment of the coil 201, in which the cooling fluid channel 220 comprises a plurality of transverse holes 221 distributed over the outer circumference of the conductor 210. The holes 221 extend from the inner surface 202 of the coil 201 toward the outer surface 203 of the coil, and the cooling fluid flow F is guided from the inside to the outside of the coil 201. Similarly, further alternative embodiments of the coil may envision a cooling fluid channel consisting of transverse holes in which the cooling fluid flow is guided from the outside to the inside of the coil, i.e., opposite to the flow in Figure 6.

[0078]

[0077] The coil 201 further comprises a cooling fluid connector 230 which is fluidly connected to a hole 221 in the cooling fluid channel 220. The cooling fluid connector 230 can be connected to an external cooling fluid source, which is not visible in the drawing, and can receive a flow of cooling fluid F from there during use. The cooling fluid connector 230 is located within the central opening A of the coil 201 and is therefore surrounded by the coil conductor 210. The cooling fluid connector 230 is configured to receive a flow of cooling fluid from the cooling fluid source and to guide the cooling fluid flow F into the cooling fluid channel 220. The position of the cooling fluid connector 230 within the central opening A of the coil 201 is advantageous because the outer surface 203 of the coil 201 is substantially exposed, and as a result, the magnet of the electromagnetic actuator can be positioned in close proximity to the coil 201.

[0079]

[0078] Figure 7 shows a side view of one embodiment of the coil 301. The coil 301 in Figure 7 is also a racetrack coil, and the line of sight is aligned parallel to the stacking direction S of the coil 301. Figure 7 shows that the coil 301 has a cooling fluid channel consisting of four through holes 321, which extend across all of the coil conductors 310 stacked in a direction parallel to the stacking direction S. In Figure 7, it can be seen that the perforated cooling fluid holes 321 are completely surrounded by the coil conductors 310, and as a result, the cooling fluid can contact the conductors 310 around the entire circumference of the holes 321.

[0080]

[0079] In this embodiment, all holes 321 are provided with a coating 322 applied to the coil conductor 310. However, the presence of the coating is not necessarily required for all holes. The coating 322 is located on the outer circumferential surface defining the holes 321 inside the coil conductor 310. The coating 322 of the present invention is a corrosion-resistant, electrically insulating, and thermally conductive coating, comprising a plurality of different coating layers. The coating 322 first comprises a ceramic coating layer made of diamond-like carbon (DLC), a ceramic material having desirable corrosion resistance, electrical insulation, and thermal conductivity properties, which is applied directly onto the coil conductor 310. In addition, the coating 322 comprises a polymer coating layer made of parylene, which is applied on top of the ceramic coating layer. The polymer coating layer is beneficial in addition to the ceramic coating layer because the ceramic coating may have pinholes, and these pinholes are filled with the polymer material. The coating 322 is applied to the holes 321 by a chemical vapor deposition process.

[0081]

[0080] Figure 8 shows a side view of a different embodiment, which comprises a first coil 401 and a second coil 451 arranged adjacent to each other. The coil planes of coils 401 and 451 extend parallel to each other, i.e., perpendicular to the plane of the drawing, so that coils 401 and 451 together can generate a combined magnetic field. Coils 401 and 451 face each other at head end faces 404 and 454, which are electrically insulated from each other via an electrical insulation layer 405. Cooling fluid channels are formed by holes 421 provided at the interface of coils 401 and 451. Thus, the cooling fluid comes into contact with both the coil conductor 410 of the first coil 401 and the coil conductor 460 of the second coil 451 during use, so that heat can be drawn from both coils 401 and 451 into the cooling fluid.

[0082]

[0081] Figure 9 shows a plan view of a further embodiment of the coil 501, in which the cooling fluid channel is formed by four open grooves 525, indicated by dashed lines in Figure 9. Figure 11 shows the same coil 501 in a cross-sectional view. In this embodiment, the grooves 525 are provided on the head end face 504 of the coil 501, which is the plane of the drawing in Figure 8. The cooling fluid channel traces an annular path across the entire head end face 504 of the coil 501 and extends circumferentially along the coil conductors 510. The grooves 525 of the cooling fluid channel substantially follow the path of the conductors 510, which is beneficial in this embodiment where the coil is embodied as a racetrack-shaped coil 501, i.e., all conductors 510 are located within a single coil plane, i.e., parallel to the plane of the drawing.

[0083]

[0082] The grooves 525 of the cooling fluid channels are formed in the conductors 510 of the coil 501 by a removal manufacturing method in which the material is removed from the coil conductors 510. In this embodiment, the cooling fluid channels are obtained by milling grooves 525 through the coil conductors 510 at the head end face 504 of the coil 501.

[0084]

[0083] Figure 10 shows a perspective cross-sectional view of another embodiment of the coil 601, in which the cooling fluid channels 620 trace a meandering reciprocating path across the head end face 604 of the coil 601. These cooling fluid channels 620 are also formed by grooves 625, and their meandering paths suggest that they extend across various coil conductors 610.

[0085]

[0084] The cooling fluid channel 620 is further subdivided into two grooves forming a supply section 626 for the cooling fluid and a single groove forming a return section 627. The supply section and the return section are fluid-connected in series and extend adjacent to each other through the coil 601. The supply section 626 and the return section 627 are positioned antiparallel to each other, and as a result, the direction of cooling fluid flow in the supply section is opposite to the direction of cooling fluid flow in the return section, as indicated by the arrows in Figure 10. The cooling fluid in the supply section 626, having just left the cooling fluid source, may be relatively cold, while the cooling fluid in the return section 627, having traveled a longer distance through the coil 601, may be relatively warm. The net cooling fluid temperature, i.e., the combined temperature of the cooling fluid flow in the supply section and the return section, may be relatively constant over the length of the cooling fluid channel 620, which may provide a more uniform extraction of heat from the conductor 610.

[0086]

[0085] The return section 627 is positioned in the center between the two supply sections 626, and as a result, at any point along the length of the cooling fluid channel 620, the return section 627 is surrounded on both sides by the supply sections 626. Placing the supply sections 626 on the outside suggests that the outermost part of the cooling fluid channel 620 contains the cooling fluid at the lowest temperature during use. This may be beneficial in maximizing cooling at the edge conductors 611, 612, in the outermost edge conductor 611 and innermost edge conductor 612 of the coil 601, which abut the other conductor 610 on only one side. Figure 11 shows a cross-sectional view of the coil 501 along line AA of Figure 9, showing that four grooves 525 are provided in the conductor 510 at the head end face 504 of the coil 501. For clarity, the conductor 510 is shown as a single conductor in Figure 11.

[0087]

[0086] The groove 525 may have a rectangular cross-section so that the cooling fluid can contact the conductor 510 on three surfaces of the groove 525, but other types of cross-sections, such as a semicircular or rounded cross-section, can also be considered. The groove 525 has a depth D perpendicular to the head end face 504, which is relatively shallow compared to the width W in the stacking direction S. Alternatively, the groove may be made relatively deep compared to its width. In another alternative embodiment, the groove may have a circular or rounded cross-section.

[0088]

[0087] The coil 501 further includes a cover element 540 over the open groove 525 to cover the groove from above and to provide an enclosed cooling fluid channel in order to prevent leakage of the cooling fluid.

[0089]

[0088] Figure 12 shows a cross-sectional view of an alternative embodiment, in which, similar to the embodiment in Figure 8, the first coil 701 is positioned adjacent to the second coil 751. The coil planes of coils 701 and 751 extend parallel to each other, and as a result, coils 701 and 751 together can generate a combined magnetic field. Coils 701 and 751 face each other at head end faces 704 and 754, and these head end faces are electrically insulated from each other via an electrical insulation layer 705. The cooling fluid channel 720 is formed by three grooves 725 in the first coil 701 and three grooves 775 in the second coil 751, which face each other, and as a result, these grooves together define a fluid flow path for the cooling fluid. In this way, the cooling fluid channel 720 is formed between the two coils 701 and 751, and both coils 701 and 751 can be cooled through a single flow of cooling fluid.

[0090]

[0089] The embodiment shown in Figure 12 is manufactured by first forming a first coil 701 with a first coil conductor 710 and a second coil 751 with a second coil conductor 760. Next, grooves 725, 775 are milled into the head end faces 704, 754 of the respective coils 701, 751, and finally, the coils 701, 751 are placed adjacent to each other, so that the cooling fluid channel 720 is ultimately formed by the respective opposing grooves 725, 775. Optionally, after milling the grooves 725, 775 and before placing the coils 701, 751 adjacent to each other, a coating may be applied to the coils so as to cover the walls of the grooves 725, 775 and the head end faces 704, 754, or the entire coil. The coating may comprise several different coating layers. For example, the coating may comprise one or more ceramic coating layers made of ceramic material. As an example, the ceramic coating layer may be made of diamond-like carbon (DLC) or aluminum nitride, and these ceramic materials have been found to have desirable corrosion resistance, electrical insulation, and thermal conductivity properties. Additionally or alternatively, the coating may comprise one or more polymer coating layers, for example, made of parylene. Since ceramic coatings may have pinholes, and these pinholes can be filled with polymer materials, the polymer coating layers may be beneficial in addition to the ceramic coating layers. One or more polymer coating layers may be applied on top of one or more ceramic coating layers, or directly on the coil conductor, for example, under the ceramic coating layers, i.e., as an intermediate layer to improve the adhesion of the ceramic coating layers. Additionally or alternatively, the coating may comprise a multilayer coating comprising one or more polymer layers, for example, made of parylene, and one or more atomic layer deposition (ALD) coatings made of inorganic materials such as aluminum oxide, titanium oxide, and hafnium oxide.After the coating is applied, adhesive may be applied to the head end faces 704, 754 to join adjacent coated coils 701, 751, thereby forming coated cooling fluid channels 720 by their respective opposing grooves 725, 775. Joining the coated coils may also be achieved by thermal joining, for example, by first melting at least a portion of the coating material at a temperature above a certain temperature, and then joining the coated head end faces together using the at least partially melted coating material.

[0091]

[0090] Figure 13 shows a cross-sectional view of a further alternative embodiment of the coil 801, which is a so-called "edge-wound" type coil. In the coil 801 of Figure 13, the coil plane extends parallel to the plane of the drawing, and the stacking direction S is aligned perpendicular to the coil plane and the plane of the drawing. In this coil 801, the cooling fluid channel extends throughout the coil 801 in a direction substantially perpendicular to the coil plane and therefore parallel to the stacking direction S. The cooling fluid channel is formed by four grooves 825, which are provided on the outer surface 803 of the coil 801 at equal intervals along the outer circumference of the conductor 810. The coil 801 further comprises a cover element embodied as a covering 840, which surrounds the conductor 810 and covers the open grooves 825 from the outside to prevent leakage of the cooling fluid and provides an enclosed cooling fluid channel.

[0092]

[0091] The groove 825 in the embodiment of Figure 13 also has a rectangular cross-section, but the relationship between its depth D and width W is different from that of the coil shown in Figure 11. In the coil 801 of Figure 13, as is best seen in the enlarged view of the upper right corner, the groove 825 has a depth D that is relatively large compared to the width W along the outer circumference of the conductor 810 when viewed from the outer surface 803 of the coil 801, which suggests that these grooves 825 are provided to be relatively deep relative to their width.

[0093]

[0092] Figure 14 shows a cross-sectional view of a further embodiment, which comprises a first coil 901 and a second coil 951 arranged concentrically with respect to each other. The second coil, for example, an inner coil 951, is installed in the central opening A' of the first coil, for example, an outer coil 901, and the coil planes of both coils 901 and 951 extend parallel to each other, so that the coils 901 and 951 together can generate a combined magnetic field. In addition, the inner surface 902 of the first coil 901 and the outer surface 953 of the second coil 951 are in contact with each other via an electrical insulating layer 905.

[0094]

[0093] The grooves 925 and 975 of the coils 901 and 951 face each other. Thus, the cooling fluid channel is formed by the four grooves 925 on the inner surface 902 of the conductor 910 of the first coil 901 and the four grooves 975 on the outer surface 953 of the conductor 960 of the second coil 951. In this way, both coils 901 and 951 can be cooled through a single flow of cooling fluid through the opposing grooves 925 and 975. This embodiment of the coil can further be provided without cover elements on the outer surface of the conductor 910 of the first coil 901 and the inner surface of the conductor 960 of the second coil 951, since the cooling fluid channel 920 is completely enclosed between the conductors 910 and 960 of both coils 901 and 951.

[0095]

[0094] Figure 15 shows a perspective view of a further alternative embodiment of coil 1001, which is a so-called "edge-wound" type coil. In coil 1001 of Figure 15, the coil plane extends perpendicular to the stacking direction S. In this coil 1001, the cooling fluid channels extend throughout the coil 1001 in a direction substantially perpendicular to the coil plane and therefore parallel to the stacking direction S. The cooling fluid channels are formed by grooves 1025, which are provided on the outer surface 1003 of coil 1001 at equal intervals along the outer circumference of the conductor 1010. The grooves 1025 are open and have a rounded cross-section.

[0096]

[0095] The coil 1001 shown in Figure 15 may further comprise a cover element, embodied as a covering 1040, as shown in Figure 16, which surrounds the conductor 1010 and covers the open groove 1025 from the outside to prevent leakage of the cooling fluid and provides an enclosed cooling fluid channel.

[0097]

[0096] Figure 17 shows a perspective view of a further embodiment, which comprises a first coil 1101 and a second coil 1151 arranged concentrically with respect to each other. The second coil, for example, an inner coil 1151, is installed in the central opening A' of the first coil, for example, an outer coil 1101, and the coil planes of both coils 1101 and 1151 extend parallel to each other, so that the coils 1101 and 1151 together can generate a combined magnetic field. In addition, the inner surface 1102 of the first coil 1101 and the outer surface 1153 of the second coil 1151 are in contact with each other via an electrical insulating layer 1105.

[0098]

[0097] The grooves 1125 and 1175 of the coils 1101 and 1151 face each other and have rounded cross-sections. Thus, the cooling fluid channel is formed by the groove 1125 on the inner surface 1102 of the conductor 1110 of the first coil 1101 and the groove 1175 on the outer surface 1153 of the conductor 1160 of the second coil 1151. In this way, both coils 1101 and 1151 can be cooled through a single flow of cooling fluid through the opposing grooves 1125 and 1175. This embodiment of the coil can further be provided without cover elements on the outer surface of the conductor 1110 of the first coil 1101 and the inner surface of the conductor 1160 of the second coil 1151, since the cooling fluid channel 1120 is completely enclosed between the conductors 1110 and 1160 of both coils 1101 and 1151.

[0099]

[0098] Figure 18 shows a plan view of another embodiment of the coil 1201, in which the cooling fluid channel 1220 traces a meandering reciprocating path across the head end face 1204 of the coil 1201, which is the plane of the drawing. Similar to the groove 625 in Figure 10, this cooling fluid channel 1220 is also formed by an open groove 1225. Compared to the coil in Figure 10, the meandering path in Figure 18 suggests that it extends mainly along the coil conductors, forming reciprocating side steps 1208 that span a smaller number of the various coil conductors 1210, for example, two or three. The side steps create turbulence in the cooling fluid flow, which can diffuse the current density and heat generation across the coil conductors and improve the cooling effect. The cooling fluid channel 1220 is provided with at least one supply section 1226 and at least one return section 1227, which are fluidly connected in series. Preferably, the supply section is positioned as the innermost and outermost parts of the cooling fluid channel, so that the innermost and outermost parts of the cooling fluid channel contain the cooling fluid at the lowest temperature during use. This may be beneficial in the outermost or innermost edge conductors of the coil, as these conductors may not be able to cross the cooling fluid channel, i.e., if embodied as grooves, this could cause leakage. For this reason, the edge conductors are positioned close to the coldest cooling fluid in the supply section located outside the return section to maximize cooling in the edge conductors.

[0100]

[0099] The supply and return sections are positioned substantially in opposite parallels to each other, and as a result, the direction of the cooling fluid flow in the supply section is opposite to the direction of the cooling fluid flow in the return section, as shown by the arrows in Figure 18. The cooling fluid in the supply section 1226 coming out of the cooling fluid source may be relatively cold, while the cooling fluid in the return section 1227 having passed through the coil 1201 over a longer length may be relatively warm. The net cooling fluid temperature, i.e., the combined temperature of the cooling fluid flow in the supply and return sections, may be relatively constant over the length of the cooling fluid channel 1220, which can provide a more uniform extraction of heat from the conductor 1210. Optionally, a cooling fluid manifold 1207 may be located within the coil core 1206 to spatially efficiently deliver the cooling fluid to the supply section 1226 and receive it from the return section 1227.

[0101] [000100] Figure 19(a) shows a perspective view of a further embodiment of the coil 1301, which comprises an “edge-wound” type coil having a rectangular shape with rounded corners when viewed along the stacking direction S. In the coil 1301, the coil plane extends perpendicular to the stacking direction S. Figure 19(b) is a cross-sectional perspective view of the coil 1301 cut perpendicular to the coil plane along line 19B-19B. In this coil 1301, the cooling fluid channels 1320 extend throughout the coil 1301 in a direction substantially perpendicular to the coil plane and therefore parallel to the stacking direction S. The cooling fluid channels are formed by holes 1325 having a circular cross-section, which are provided in the coil 1301 at equal intervals along the length of each side of the conductor 1310. Preferably, the holes 1325 are drilled through the coil conductor. In this coil 1301, the cooling fluid may be supplied and returned from opposing head end faces of the coil, for example, supplied from the top of the coil and returned from the bottom, as indicated by the arrows in Figure 19(b).

[0102] [000101] Figure 20(a) shows a perspective view of an alternative embodiment of coil 1401, which features an “edge-wound” type coil having a rectangular shape with rounded corners when viewed along the stacking direction S. In coil 1401, the coil plane extends perpendicular to the stacking direction S. Figure 20(b) is a cross-sectional perspective view of coil 1401 cut perpendicular to the coil plane along line 20B-20B. In this coil 1401, a V-shaped cooling fluid channel 1420 extends throughout the coil 1401 in a plane parallel to the stacking direction S. Typically, the cooling fluid channel extends through all conductors. The V-shaped cooling fluid channel comprises a supply section 1426 and a return section 1427, thereby supplying and returning the cooling fluid to the same head end face of the coil, as indicated by the arrows in Figure 20(b). The V-shaped cooling fluid channel is provided on each side of coil 1401. Optionally, two or more V-shaped cooling fluid channels may be arranged on each side of the coil. Alternatively, other shapes of cooling fluid channels may be selected to achieve a similar cooling effect. The cooling fluid channels are formed by holes 1425 having a circular cross-section. Preferably, the supply and return holes are drilled through various coil conductors, and the drilling process forms a connection point 1408, thereby fluidly connecting the supply 1426 and the return 1427.

[0103] [000102] While specific embodiments of the present invention have been described above, it will be understood that the present invention can also be practiced in ways other than those described. The above description is intended to be illustrative and not limiting. It will therefore be apparent to those skilled in the art that modifications to the described invention can be made without departing from the claims set forth below. Other aspects of the present invention are described in the following numbered clauses.

[0104] 1. A fluid-cooled coil for use in an electromagnetic actuator of a lithography apparatus, wherein the coil is formed of multiple electrically insulated flat wire coil conductors and is configured to conduct electric current and generate an electromagnetic field during use. It is equipped with at least one cooling fluid channel that makes thermal conduction contact with the coil in order to guide the flow of cooling fluid to extract heat from the coil, A coil characterized in that cooling fluid channels are provided throughout the entire coil, crossing multiple coil conductors. 2. The cooling fluid channel extends through substantially all of the coil conductors, as described in Clause 1. 3. The coil according to Clause 1 or 2, wherein the cooling fluid channel extends throughout the coil in a direction having at least one component substantially parallel to the coil plane over which the coil conductors extend. 4. The coil according to Clause 1 or 2, wherein the cooling fluid channel extends throughout the coil in a direction having at least one component substantially perpendicular to the coil plane over which the coil conductors extend. 5. The coil according to any one of the clauses 1 to 4, wherein the cooling fluid channel is formed by at least one hole that crosses the coil conductor. 6. The coil according to any one of the clauses 1 to 4, wherein the cooling fluid channel is formed by at least one groove extending throughout the coil conductor on the inner surface, outer surface, or head end face of the coil. 7. Equipped with multiple coils, The coils are arranged adjacent to each other, with the coil conductors extending parallel to each other and at a distance from each other. The opposing head ends of the coils are in contact with each other via an electrical insulating layer. The coil according to Clause 6, wherein the cooling fluid channels are formed by opposing grooves in each coil, and each groove extends across the entire length of each coil conductor at the opposing head end faces. 8. Equipped with multiple coils, The coils are arranged concentrically, and the coil conductors extend on the same plane. The inner surface of the outer coil and the outer surface of the inner coil are in contact with each other through an electrical insulating layer. The coil according to Clause 6, wherein the cooling fluid channels are formed by opposing grooves in each coil, and each groove extends across the entire coil conductor on opposing inner and outer surfaces. 9. A coil according to any one of clauses 6 to 8, further comprising a cover element disposed on the inner surface, outer surface, or head end face of the coil to cover a groove. 10. A coil according to any one of the clauses 1 to 9, further comprising a coating on the coil conductor within a cooling fluid channel. 11. The coil according to Clause 10, wherein the coating comprises one or more ceramic coating layers made of, for example, diamond-like carbon (DLC) or aluminum nitride, and / or one or more polymer coating layers made of, for example, parylene. 12. Further comprising a cooling fluid connector that is connected to a cooling fluid channel, The cooling fluid connector can be connected to an external cooling fluid source. The cooling fluid connector is located within the central opening of the coil and surrounded by the coil conductors, as described in any of the clauses 1 to 11. 13. The cooling fluid channel forms an annular path throughout the coil and extends circumferentially along the coil conductor, as described in any of clauses 1 to 12. 14. The cooling fluid channel traces a meandering reciprocating path throughout the coil, as described in any of clauses 1 to 12. 15. The cooling fluid channel is subdivided into at least one supply section and at least one return section, which are fluidly connected in series. At least one supply section and at least one return section extend through the coil adjacent to each other, The coil according to any one of the clauses 1 to 14, wherein at least one supply section and at least one return section are antiparallel to each other, and as a result, the direction of flow of the cooling fluid in at least one supply section is opposite to the direction of flow of the cooling fluid in at least one return section. 16. It comprises two of the supply sections and one of the return sections, The return section is located in the center between the two supply sections, as described in Clause 15. 17. The coil as described in Clause 15, wherein at least one supply section and at least one return section trace a double helix path through the coil. 18. A flat wire coil conductor having a rectangular cross-section, as described in any of clauses 1 to 17. 19. An exposure apparatus, for example, a lithography apparatus, comprising a coil as described in any of clauses 1 to 18. 20. The step of forming a coil from multiple flat wire coil conductors, The steps include forming a cooling fluid channel throughout the coil, A method for manufacturing a coil as described in any of the clauses 1 to 18, comprising: 21. The method according to clause 20, wherein the step of forming a cooling fluid channel comprises removing the cooling fluid channel through manufacturing, for example, laser ablation, etching, drilling, milling, or spark erosion. 22. The method according to clause 20 or 21, wherein the step of forming a cooling fluid channel comprises drilling a plurality of holes, for example, across all coil conductors, at least one hole. 23. The method according to clause 20 or 21, wherein the step of forming a cooling fluid channel comprises milling at least one groove through which a coil conductor passes. 24. The method according to any one of the clauses 20 to 23, further comprising the step of applying a coating to a coil conductor in a cooling fluid channel, for example by physical vapor deposition and / or (plasma-enhanced) chemical vapor deposition.

Claims

1. A fluid-cooled coil for use in an electromagnetic actuator of a lithography apparatus, wherein the coil is formed of a plurality of electrically insulated flat wire coil conductors and is configured to conduct electric current and generate an electromagnetic field during use. The device includes at least one cooling fluid channel that makes thermal conduction contact with the coil in order to guide the flow of cooling fluid in order to extract heat from the coil. A coil characterized in that the cooling fluid channel is provided throughout the entire coil, traversing a plurality of the coil conductors.

2. The coil according to claim 1, wherein the cooling fluid channel extends substantially across all coil conductors.

3. The coil according to claim 1 or 2, wherein the cooling fluid channel extends throughout the coil in a direction having at least one component substantially parallel to the coil plane on which the coil conductor extends.

4. The coil according to claim 1 or 2, wherein the cooling fluid channel extends throughout the coil in a direction having at least one component substantially perpendicular to the coil plane on which the coil conductor extends.

5. The coil according to any one of claims 1 to 4, wherein the cooling fluid channel is formed by at least one hole that crosses the coil conductor.

6. The coil according to any one of claims 1 to 4, wherein the cooling fluid channel is formed by at least one groove extending over the entire coil conductor on the inner surface, outer surface, or head end face of the coil.

7. The coil according to any one of claims 1 to 6, further comprising a coating on the coil conductor within the cooling fluid channel.

8. The coil according to claim 7, wherein the coating comprises, for example, one or more ceramic coating layers made of diamond-like carbon (DLC) or aluminum nitride, and / or one or more polymer coating layers made of, for example, parylene.

9. The cooling fluid connector is further connected to the aforementioned cooling fluid channel, The cooling fluid connector is connectable to an external cooling fluid source. The coil according to any one of claims 1 to 8, wherein the cooling fluid connector is located within the central opening of the coil and is surrounded by the coil conductor.

10. The coil according to any one of claims 1 to 9, wherein the cooling fluid channel traces an annular path throughout the coil and extends circumferentially along the coil conductor.

11. The coil according to any one of claims 1 to 9, wherein the cooling fluid channel traces a meandering reciprocating path throughout the entire coil.

12. The cooling fluid channel is subdivided into at least one supply section and at least one return section, which are fluidly connected in series. The at least one supply section and the at least one return section extend adjacent to each other through the coil, The coil according to any one of claims 1 to 11, wherein the at least one supply section and the at least one return section are antiparallel to each other, and as a result, the flow direction of the cooling fluid in the at least one supply section is opposite to the flow direction of the cooling fluid in the at least one return section.

13. The coil according to any one of claims 1 to 12, wherein the flat wire coil conductor has a rectangular cross-section.

14. An exposure apparatus, for example, a lithography apparatus, comprising a coil according to any one of claims 1 to 13.

15. The steps include forming the coil from a plurality of flat wire coil conductors, The steps include forming the cooling fluid channel throughout the coil, A method for manufacturing a coil according to any one of claims 1 to 13, comprising:

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