Internally cooled actuator coil

Abstract

The invention provides a coil to be fluid-cooled in an electromagnetic actuator for a lithographic apparatus, the coil comprising: a coil formed of a plurality of electrically insulated flat wire coil conductors and configured to conduct an electrical current during use to generate an electromagnetic field, and at least one cooling fluid channel in thermally conductive contact with the coil, and a plurality of coil conductors for directing a flow of cooling fluid to take away heat from the coil, characterized in that the cooling fluid channel is disposed across the coil through the plurality of coil conductors.

Description

Cross-references to related applications

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

[0002] This invention relates to a fluid-cooled coil in an electromagnetic actuator for a photolithography apparatus. The invention also relates to an exposure apparatus, such as a photolithography apparatus, including the coil, and a method for manufacturing the coil. Background Technology

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

[0004] As semiconductor manufacturing processes continue to advance, the size of circuit components continues to shrink, while the number of functional components (such as transistors) in each device has steadily increased over the decades, following a trend commonly known as "Moore's Law." To keep pace with Moore's Law, the semiconductor industry is pursuing technologies capable of creating increasingly smaller features. To project patterns onto a substrate, photolithography apparatuses 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 used are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. Compared to photolithography apparatuses using radiation with a wavelength of, for example, 193 nm, extreme ultraviolet (EUV) radiation in the range of 4 nm to 20 nm, such as 6.7 nm or 13.5 nm, can be used to form even smaller features on the substrate.

[0005] Magnetic coils currently form the backbone of electromagnetic actuators. These actuators are frequently used, for example, in exposure equipment, such as photolithography apparatuses used to manufacture semiconductor products. These coils are subjected to alternating current flowing through their conductors, which are often called “windings” because they are typically manufactured by winding. The current through the coil induces an electromagnetic field that can interact with magnets, such as permanent magnets, to achieve mutual displacement between them.

[0006] During use, the magnetic coil needs to be cooled because the resistance of the current flowing through it causes it to heat up. This is typically achieved by means of a cooling fluid that travels along the coil through cooling conduits to draw heat away from the coil. The cooling fluid is typically a liquid, although gaseous or evaporative cooling fluids can also be used.

[0007] In current coils, cooling efficiency is quite low because there are multiple layers of material between the coil and the cooling fluid, all of which typically have poor thermal conductivity. Examples of these materials, starting with the coil, include coil winding insulation, coil winding adhesive, coil potting, electrical insulating foil, insulating foil adhesive, and cooling conduit material. In these current-carrying coils, it is generally preferable to maintain sufficiently low thermal resistance by making all these layers as thin as possible. However, the finite thickness of the layers introduces higher thermal shear stress, which can cause delamination and also increases the risk of electrical breakdown or short circuits between the coil and the cooling conduit, since known cooling conduits are typically made of conductive materials. Furthermore, the direction of the thermal path is parallel to the alignment of the magnetic path between the coil and the magnet, meaning that the accumulation of thermal stress and stress induced by the magnetic force can cause additional delamination and thus overheating, as this delamination further reduces thermal conductivity.

[0008] As a potential solution, it is known to provide hollow windings for the coil through which cooling fluid circulates. This allows for more direct contact between the coil winding material and the cooling fluid; however, this has been found to be disadvantageous because it can involve a relatively large cooling fluid pressure drop, as the cooling fluid would need to traverse the entire length of the coil winding, and a relatively low coil fill factor, resulting in high resistance and low current density. Furthermore, the minimum manufacturable wire size and form factor of these hollow coils can be excessive for current applications. Finally, coating the interior of these thin wires with an insulating and non-corrosive coating material can be complex.

[0009] As another alternative, it is known to immerse the coil directly in a cooling fluid. However, these coils can have the disadvantage that the actuating force from the coil must flow through the coil core, which can cause high stress in the coil and at the coil-core interface. Furthermore, when the entire coil housing is filled with cooling fluid, the high coolant pressure and the pressure fluctuations caused by acceleration can create relatively large stresses within the housing. Summary of the Invention

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

[0011] Therefore, the present invention provides a coil to be cooled by fluid in an electromagnetic actuator of a photolithography apparatus, the coil being formed of a plurality of electrically insulated flat wire coil conductors and configured to conduct current during use to generate an electromagnetic field, and including at least one cooling fluid channel in thermal contact with the coil for guiding the flow of cooling fluid to dissipate heat from the coil, characterized in that the cooling fluid channel is disposed across the coil and passes through the plurality of coil conductors.

[0012] According to the invention, the coil is composed of conductors through which current can be conducted. These conductors are sometimes referred to as windings because the coil is made by obtaining conductors by winding wires into loops. However, alternatively, the invention also envisions so-called "hairpin" type coils, in which the coil is assembled from various individual and interconnected conductors.

[0013] This coil is made of flat wire conductors. It should be understood that adjacent conductors or windings contact each other over a relatively large width, for example, compared to their thickness in the stacking direction of the coil. Compared to other coils, such as where the conductors can have a circular cross-section, flat wire conductors offer the benefit of improved heat transfer between individual conductors, i.e., heat transfer in the stacking direction. Furthermore, compared to circular windings, flat wire conductors can accommodate more conductors in the same cross-section, which reduces resistance, thereby reducing the voltage required on the coil and heat loss within the coil. Additionally, the individual conductors are electrically insulated from each other to prevent short circuits between them.

[0014] The cooling fluid channels in the coil are configured to guide the cooling fluid, allowing heat from the coil conductors to be conducted toward the cooling fluid. Therefore, the invention further adds that the cooling fluid channels are arranged across the coil, meaning that during use, the cooling fluid passes through recesses or holes in the coil and comes into direct contact with the coil conductors, optionally only through a relatively thin coil coating applied to the conductors within the cooling fluid channels.

[0015] This coil can be manufactured by machining the coil to form cooling fluid channels therein. This can be achieved, for example, by forming open grooves in the coil conductor or by drilling holes through the coil conductor, through which the cooling fluid can be guided.

[0016] By providing cooling fluid channels through multiple conductors, the cooling fluid can be in direct contact with more than one conductor. This eliminates the need for heat to dissipate between conductors before reaching the cooling fluid, thus improving cooling efficiency.

[0017] Preferably, the cooling fluid channels extend across substantially all of the coil conductors to enable heat to be absorbed directly from each conductor into the cooling fluid, which can further improve the cooling efficiency of the coil.

[0018] Because the thermal path between the coil conductor and the cooling fluid is reduced, this coil, which has direct contact between the cooling fluid and the conductor, provides up to four times the improvement in cooling. The thermal path of this coil is now from the coil conductor to the coil insulation to the cooling fluid. Furthermore, the coil surface area in contact with the cooling fluid can be increased within the same coil volume, which also improves the cooling effect.

[0019] Furthermore, this coil can operate at higher temperatures. In existing coils, the thermal stress between the coil and the cooling plate—that is, the thermal stress caused by the difference in the coefficients of thermal expansion—can indeed cause delamination between the coil and the cooling plate. In this coil, the direction of thermal shear stress and the thermal path is different from the force path, which prevents thermal stress and magnetic coil force from causing coil delamination, resulting in a higher force density in the coil.

[0020] Furthermore, this coil eliminates the need for a separate cooling conduit beside it, freeing up more space within the electromagnetic actuator for increased force density. Finally, the absence of a cooling plate allows the coil to be positioned closer to the actuator's magnet, further enhancing force density. The overall combination of these improvements results in a more than twofold increase in magnetic force density.

[0021] Furthermore, the absence of coils near cooling conduits reduces the risk of electrical breakdown. Additionally, the absence of cooling fluid flowing through the actuator housing or cooling conduits allows for the use of different materials for manufacturing the actuator housing, such as ceramics, thus avoiding the risk of stress corrosion cracking in the absence of water or other non-conductive materials. This can further contribute to avoiding the risk of electrical breakdown.

[0022] In embodiments of the invention, the coil conductors extend within the coil plane. The coil conductors can be arranged adjacent to each other in the stacking direction and aligned within the coil plane to obtain circular, rectangular, or so-called "racetrack" coils. In such coils, cooling fluid channels can extend across the coil in a direction having at least one component substantially parallel to the coil plane. Alternatively, however, the stacking direction can be aligned perpendicular to the coil plane, i.e., in "edge-wound" type coils, whereby the cooling fluid channels can extend across the coil in a direction having at least one component substantially perpendicular to the coil plane. In both examples, the cooling fluid channels can extend parallel to the coil's stacking direction, or can have at least one component extending parallel to the coil's stacking direction.

[0023] In one embodiment, the cooling fluid channel is formed by at least one hole extending laterally through the coil conductors. The hole may be entirely contained within the coil conductors, allowing the cooling fluid to contact the conductors across the entire perimeter of the hole. These holes extend laterally through the coil, i.e., parallel to the stacking direction, and typically extend through all conductors to effectively remove heat from all conductors. Optionally, the coil includes multiple holes extending adjacent to each other to enable heat extraction at multiple different locations within each conductor.

[0024] In an alternative embodiment, the cooling fluid channel is formed by at least one groove extending across the coil conductor at the inner surface, outer surface, or head end surface of the coil. These grooves are open-faced, for example having a rectangular or circular cross-section, and the coil conductor is formed on their respective surfaces, i.e., such that the cooling fluid can contact the conductor at three sides. The inner surface may be defined as the surface within the central aperture of the coil, the outer surface surrounds the outermost conductor, and the head end surfaces of the coil may be located at the head end of the coil, opposite each other in the stacking direction.

[0025] In one embodiment, the recessed cooling fluid channel may be provided with a cover element configured to cover the open recess to provide a closed cooling fluid channel and prevent cooling fluid leakage.

[0026] In one embodiment, multiple coils, such as two coils, may be provided, arranged adjacent to each other such that the coil planes extend parallel to each other, enabling the coils together to generate a combined magnetic field. The coils may be arranged adjacent to each other, wherein their end surfaces may be electrically insulated from each other by an electrical insulating layer, and wherein a cooling fluid channel is formed by a combination of grooves in each coil. The grooves in opposing coils are also opposite to each other, such that they together define a fluid flow path for the cooling fluid, and both coils can be cooled by a single flow of cooling fluid.

[0027] Alternatively, multiple coils can be arranged concentrically, i.e., the inner coil is located within the central aperture of the outer coil. Thus, 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. In this embodiment, the grooves of the coils face each other and are opposite each other; for example, an inner groove on the inner surface of the outer coil faces an outer groove on the outer surface of the inner coil, such that they together define a cooling fluid channel for cooling fluid, and both coils can be cooled by a single flow of cooling fluid. In both embodiments, cooling can be conveniently and efficiently established for multiple coils with a single but shared cooling fluid channel, which can further improve cooling efficiency and further reduce costs.

[0028] In cross-section, grooves can have a depth perpendicular to the surface defining them, which is relatively shallow compared to the width of the groove. Grooves with this type of cross-section can effectively remove heat from the coil, but relatively large stresses can be generated between the opposing coils due to the hydraulic fluid pressure of the cooling fluid in the opposite groove (i.e., the wide groove). Alternatively, the grooves can be relatively deep compared to their width, so that the stress induced at the interface between the conductor and the cooling fluid loop, i.e., the stress caused by the hydraulic fluid pressure, can be reduced. Furthermore, from the perspective of the surfaces defining adjacent grooves, the spacing between adjacent grooves can be adjusted to regulate the stress caused by the hydraulic fluid pressure and the cooling capacity of the cooling fluid.

[0029] In one embodiment, the coil includes a coating on the coil conductor within a cooling fluid passage. The coating may be applied to the surface defining the cooling fluid passage and may be used for various purposes, such as as an anti-corrosion coating, an electrical insulating coating, and / or a sealing coating, to prevent cooling fluid leakage.

[0030] For example, the coating may include multiple different coatings. For instance, the coating may include one or more ceramic coatings made of ceramic materials. As an example, the ceramic coating may be made of diamond-like carbon (DLC) or aluminum nitride, as these ceramic materials are found to have desirable corrosion resistance, electrical insulation, and thermal conductivity properties. Additionally or alternatively, the coating may include one or more polymer coatings, such as those made of parylene. Polymer coatings are also advantageous in addition to ceramic coatings because ceramic coatings may contain pinholes that can be filled with the polymer material. One or more polymer coatings may be applied over one or more ceramic coatings or directly onto the coil conductor, for example, under the ceramic coating, as an intermediate layer to improve the adhesion of the ceramic coating. Additionally or alternatively, the coating may include a multilayer coating comprising one or more polymer layers, such as those made of parylene, and one or more atomic layer deposition (ALD) coatings, such as those made of inorganic materials like alumina, titanium oxide, and hafnium oxide.

[0031] In one embodiment, the coil further includes a cooling fluid connector in fluid communication with a cooling fluid channel, wherein the cooling fluid connector is connectable to an external cooling fluid source, and wherein the cooling fluid connector is disposed in a central aperture of the coil and surrounded by the coil conductors. The cooling fluid connector is configured to receive a flow of cooling fluid from the cooling fluid source and is configured to direct the flow of cooling fluid into the cooling fluid channel. The cooling fluid connector can advantageously be housed in the central aperture of the coil such that the outer surface of the coil is substantially exposed, allowing the magnet of the electromagnetic actuator to be positioned near the coil, or increasing the volume of the coil within the same housing size. Alternatively, however, the cooling fluid connector can also be positioned outside the coil.

[0032] In one embodiment, the cooling fluid channel describes a circular path across the coil, extending along the circumference of the coil conductors. The cooling fluid channel thus substantially follows the path of the conductors. This can be advantageous when the coil is embodied as a racetrack coil in which all conductors lie within a single coil plane.

[0033] In an alternative embodiment, the cooling fluid channel describes a meandering, back-and-forth path through the coil. The meandering path can mean that the cooling fluid channel can extend laterally across various coil conductors to contact a large number of conductors at relatively numerous locations along its path, thereby improving cooling efficiency. In one embodiment, the cooling fluid channel is subdivided into at least one supply section and at least one return section, which are fluidly connected in series, wherein the at least one supply section and at least one return section extend adjacent to each other through the coil, and wherein the at least one supply section and at least one return section are antiparallel to each other, such that 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. The supply and return sections extend adjacent to each other, allowing for a counter-flow type heat exchanger at every point along the cooling fluid path. The cooling fluid in the supply section, just emerging from the cooling fluid source, can be relatively cold, while the cooling fluid in the return section, having passed through a longer length of the coil, can be relatively hot. The net cooling fluid temperature, i.e., the temperature of the combined cooling fluid flow in the supply and return sections, can be relatively constant over the length of the cooling fluid channel, which can provide more uniform heat dissipation from the conductors. The supply and return sections can be fluidly interconnected in series by means of a reverse turn at their ends.

[0034] In another embodiment, the coil includes two supply sections and a single return section, with the return section centrally located between the two supply sections. Viewed from any point along the length of the cooling fluid channel, the return section is surrounded by the supply sections on opposite sides. During use, the outermost section of the cooling fluid channel contains the cooling fluid at its lowest temperature. This can be advantageous at the outermost or innermost edge conductors of the coil. These conductors may not intersect the cooling fluid channel, i.e., in the case of being embodied as recesses, as this could cause leakage. For this purpose, the edge conductors are positioned near the coldest cooling fluid in the supply sections, outside the return section, to maximize cooling in the edge conductors.

[0035] In an alternative embodiment, the cooling fluid channel may extend primarily along the coil conductors, while making back-and-forth side steps on a smaller number of various coil conductors (e.g., two or three) to create turbulence in the cooling fluid flow. This disperses current density and heat generation over the coil conductors and improves cooling performance. 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 arranged as the innermost and outermost sections of the cooling fluid channel, such that during use, the innermost and outermost sections of the cooling fluid channel contain the cooling fluid at its lowest temperature. This can be advantageous at the outermost or innermost edge conductors of the coil. These conductors may not intersect the cooling fluid channel, i.e., in the case of being embodied as recesses, as this could cause leakage. For this purpose, the edge conductors are positioned near the coldest cooling fluid in the supply section, outside the return section, to maximize cooling in the edge conductors. A cooling fluid manifold may optionally be arranged within the core of the coil for delivering and receiving the cooling fluid in a space-efficient manner.

[0036] In an alternative embodiment, at least one supply segment and at least one return segment describe a double-helix path through the coil. Thus, the supply and return segments still extend side by side, but essentially follow the conductor's path in a helical manner.

[0037] In one embodiment, the flat wire coil conductors have a rectangular cross-section, elongated, for example, in a direction perpendicular to the stacking direction. Thus, the relatively long sides of the conductors abut against each other, while the short sides of the conductors begin at the head end of the coil. This can be beneficial for coil cooling because the large adjacent interfaces between the conductors allow for a relatively large degree of mutual heat exchange, and because the distance between each winding and the cooling fluid loop can be minimized while still having a sufficiently large conductor cross-section.

[0038] In another embodiment, the coil extending in a direction perpendicular to the stacking direction has a rectangular shape and rounded corners when viewed along the stacking direction. Cooling fluid channels can be arranged to extend across the coil conductors in a direction substantially perpendicular to the coil plane, thus parallel to the stacking direction, and typically extend through all conductors. The cooling fluid channels can be formed by holes of circular cross-section. These holes can be evenly distributed above the perimeter of the conductors or along the length of each side of the rectangular conductor. Holes can be drilled through the coil conductors. Cooling fluid can be supplied and returned at opposite end surfaces of the coil.

[0039] In an alternative embodiment, the coil extending in a direction perpendicular to the stacking direction has a rectangular shape and rounded corners when viewed along the stacking direction. A V-shaped cooling fluid channel can be arranged to extend across the coil in a plane parallel to the stacking direction, typically extending through all conductors. The V-shaped cooling fluid includes a supply section and a return section, such that cooling fluid is supplied to and returns from the same end surface of the coil. A V-shaped cooling fluid channel can be provided on each side of the coil. More than one V-shaped cooling fluid channel can be arranged on one or more sides of the coil. To achieve a similar cooling effect, the cooling fluid channel can be selected in forms other than V-shape. The cooling fluid channel can be formed by holes with a circular cross-section. The holes can be formed by drilling through various coil conductors, and fluid connection points can be formed by a drilling process, allowing the supply and return sections to be fluidly connected.

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

[0041] The present invention also provides an exposure apparatus, such as a photolithography apparatus, which includes the coil disclosed herein. The exposure apparatus, i.e., its coil, may include one or more features and / or benefits disclosed herein in relation to the coil according to the invention, such as those described in claims. The coil may be used in an electromagnetic actuator of the exposure apparatus, or alternatively or additionally, may be used in a linear actuator, rotary actuator, sensor, transformer, inverter, etc.

[0042] Finally, this invention provides a method for manufacturing the coil disclosed herein, the method comprising the following steps: - A coil is formed by multiple flat wire coil conductors, and - Forming a cooling fluid channel across the coil. The method, i.e., the coil manufactured using this method, may include one or more features and / or benefits disclosed herein in relation to the coil according to the invention, such as those described in the claims.

[0043] This method can be advantageous because the cooling fluid channels are formed within the coil, rather than relying on separate cooling conduits that need to be bonded to the coil, as is the case in current manufacturing methods. Although not mandatory, the formation of the cooling fluid channels preferably occurs after the coil is formed. This formation of the coil can include winding flat wire coil conductors, i.e., obtaining a coil with windings, but alternatively, it can include forming the coil by assembling multiple separate and interconnected conductor segments, thereby forming a hairpin coil.

[0044] In one embodiment, the method further includes the step of bonding the coil conductors to hold them together. Optional bonding can increase the structural rigidity of the coil, but is not necessary for forming cooling fluid channels across the coil.

[0045] In one embodiment, the step of forming the cooling fluid channel includes subtractive fabrication of the cooling fluid channel, such as laser ablation, etching, drilling, milling, or electrical discharge machining. During subtractive fabrication, material is removed from the coil, thereby obtaining the cooling fluid channel.

[0046] In one embodiment, the step of forming cooling fluid channels includes drilling at least one hole laterally through a plurality of, for example, all coil conductors. The drilled cooling fluid holes may be completely surrounded by the coil conductors, such that cooling fluid can contact the conductors throughout the perimeter of the holes. These holes extend laterally through the coils, i.e., parallel to the stacking direction, and typically extend through all conductors to effectively remove heat from all conductors. Alternatively, the method includes the step of drilling a plurality of holes extending adjacent to each other through the coils to provide coils capable of extracting heat at multiple different locations in each conductor.

[0047] In an alternative embodiment, the step of forming the cooling fluid channel includes milling at least one groove through the coil conductor. The milled groove in the coil is open-faceted, for example having a rectangular cross-section, and is formed at a corresponding surface of the coil conductor such that the cooling fluid contacts the conductor over the largest possible surface area.

[0048] In one embodiment, the method further includes the step of coating a coil conductor in a cooling fluid channel, for example by means of physical vapor deposition and / or (plasma-enhanced) chemical vapor deposition. The coating may include one or more ceramic coatings made of ceramic materials. As an example, the ceramic coating may be made of diamond-like carbon (DLC) or aluminum nitride, which may be coated onto a surface in a suitable manner by means of a vapor deposition method. Additionally or alternatively, the coating may include one or more polymer coatings, such as those made of parylene, which may be coated onto the coil conductor or one or more ceramic coatings. Additionally or alternatively, the coating may include a multilayer coating comprising one or more polymer layers, such as those made of parylene, and one or more atomic layer deposition (ALD) coatings, such as those made of inorganic materials such as alumina, titanium oxide, and hafnium oxide. Attached Figure Description

[0049] Embodiments of the invention will now be described by way of example only, with reference to the accompanying schematic diagrams, in which: - Figure 1 A schematic overview of the photolithography apparatus is depicted; - Figure 2 Depicting Figure 1 Detailed view of the components of the photolithography apparatus; - Figure 3 The position control system is schematically depicted; - Figure 4 A plan view according to an embodiment of the coil according to the present invention is depicted. - Figure 5 Plan views of different embodiments of the coil are depicted. - Figure 6 Plan views of different embodiments of the coil are depicted. - Figure 7 A side view of an embodiment of the coil is depicted. - Figure 8 Side views of different embodiments of the coil are depicted. - Figure 9 A plan view depicting another embodiment of the coil is shown. - Figure 10 A perspective cross-sectional view of another embodiment of the coil is depicted. - Figure 11 Depicting Figure 9 A cross-sectional view of the middle coil along line AA. - Figure 12 A perspective cross-sectional view of an alternative embodiment of the coil is depicted. - Figure 13 A cross-sectional view of another alternative embodiment of the coil is depicted. - Figure 14 A cross-sectional view of another embodiment of the coil is depicted. - Figure 15 A perspective view depicting another alternative embodiment of the coil is shown. - Figure 16 A perspective view depicting another alternative embodiment of the coil is shown. - Figure 17 A perspective view depicting another embodiment of the coil is shown. - Figure 18 A plan view depicting another embodiment of the coil is shown. - Figure 19(a) depicts a perspective view of another embodiment of the coil, - Figure 19(b) depicts a cross-sectional perspective view of the coil in Figure 19(a) along line 19B-19B. - Figure 20(a) depicts a perspective view of another alternative embodiment of the coil, and - Figure 20(b) depicts a cross-sectional perspective view of the coil along line 20B-20B in Figure 20(a). Detailed Implementation

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

[0051] As used herein, the terms “reticle,” “mask,” or “patterning device” can be broadly interpreted as any general patterning device that can be used to impart a patterned cross-section to an incident radiation beam, corresponding to a pattern to be created in the target portion of the substrate. The term “light valve” can also be used in this context. Examples of other such patterning devices besides traditional masks (transmission or reflection, binary, phase-shifting, hybrid, etc.) include programmable mirror arrays and programmable LCD arrays.

[0052] Figure 1A lithography apparatus LA is schematically depicted. The lithography apparatus LA includes an irradiation system (also referred to as an irradiator) IL configured to modulate a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation); a mask support (e.g., a mask stage) MT configured to support a patterning device (e.g., a mask) MA and connected to a first positioner PM, the first positioner PM being configured to precisely position the patterning device MA according to certain parameters; a substrate support (e.g., a wafer stage) WT configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioner PW, the second positioner PW being configured to precisely position the substrate support according to certain parameters; and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted by the radiation beam B by the patterning device MA onto a target portion C (e.g., comprising one or more dies) of the substrate W.

[0053] In operation, the irradiation system IL receives a radiation beam from the radiation source SO, for example via the beam delivery system BD. The irradiation 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 guiding, shaping, and / or controlling the radiation. The irradiator IL can be used to adjust the radiation beam B to have a desired spatial and angular intensity distribution in a cross-section at the plane of the patterning device MA.

[0054] As used herein, the term "projection system" (PS) should be interpreted broadly to encompass all types of projection systems, including refractive, reflective, antirefractive, distorting, magnetic, electromagnetic, and / or electrostatic optical systems, or any combination thereof, applicable to the exposure radiation used, and / or to other factors such as the use of immersion liquids or vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system" (PS).

[0055] A lithography apparatus LA can be a type in which at least a portion of the substrate can be covered by a liquid (e.g., water) with a relatively high refractive index to fill the space between the projection system PS and the substrate W—this is also known as immersion lithography. More information on immersion techniques is given in US6952253, which is incorporated herein by reference.

[0056] The lithography apparatus LA can also be of the type with two or more substrate supports WT (also known as "dual-stage"). In this type of "multi-stage" machine, the substrate supports WT can be used in parallel, and / or the subsequent exposure steps for preparing the substrate W can be performed on the substrate W located on one substrate support WT, while another substrate W on another substrate support WT is used to expose a pattern on another substrate W.

[0057] In addition to the substrate support WT, the lithography apparatus LA may include a measurement stage. The measurement stage is arranged to hold sensors and / or cleaning equipment. Sensors may be arranged to measure properties of the projection system PS or the radiation beam B. The measurement stage may hold multiple sensors. Cleaning equipment may be arranged to clean components of the lithography apparatus, such as components of the projection system PS or components of a system providing immersion in liquid. The measurement stage may move below the projection system PS as the substrate support WT moves away from the projection system PS.

[0058] In operation, a radiation beam B is incident on a patterning device (e.g., a mask MA) held on a mask support MT and patterned by a pattern (design layout) present on the patterning device MA. After passing through the patterning device MA, the radiation beam B passes through a projection system PS, which focuses the radiation beam onto a target portion C of the substrate W. With the aid of a second positioner PW and a position measurement system PMS, the substrate support WT can be precisely moved, for example, to position different target portions C in the path of the radiation beam B at focused and aligned locations. Similarly, a first positioner PM and possibly another position sensor (in...) Figure 1 (Not explicitly depicted) can be used to precisely position the patterning device MA relative to the path of the radiation 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. Although the substrate alignment marks P1, P2 occupy dedicated target portions, they can also be located in the space between target portions. When the substrate alignment marks P1, P2 are located between target portions C, they are referred to as scribe alignment marks.

[0059] To illustrate the invention, a Cartesian coordinate system is used. A Cartesian coordinate system has three axes: the x-axis, the y-axis, and the z-axis. Each of the three axes is orthogonal to the other two axes. A rotation about the x-axis is called an Rx rotation. A rotation about the y-axis is called an Ry rotation. A rotation about the z-axis is called an Rz rotation. The x-axis and y-axis define a horizontal plane, while the z-axis lies in the vertical direction. The Cartesian coordinate system is not limiting of the invention and is only used for illustration. Conversely, another coordinate system, such as a cylindrical coordinate system, can be used to illustrate the invention. The orientation of the Cartesian coordinate system can be different, for example, such that the z-axis has a component along the horizontal plane.

[0060] Figure 2 It shows Figure 1 A more detailed view of the components of the lithography apparatus LA. The lithography apparatus LA can be configured with a base frame BF, a counterweight BM, a measurement frame MF, and a vibration isolation system IS. The measurement frame MF supports the projection system PS. Furthermore, the measurement frame MF can support components of the position measurement system PMS. The measurement frame MF is supported by the base frame BF via the vibration isolation system IS. The vibration isolation system IS is arranged to prevent or reduce the propagation of vibration from the base frame BF to the measurement frame MF.

[0061] The second positioner PW is arranged to accelerate the substrate support WT by providing a driving force between the substrate support WT and the balancing mass block BM. The driving force accelerates the substrate support WT in the desired direction. Due to the conservation of momentum, an equal driving force is also applied to the balancing mass block BM, but in the opposite direction to the desired direction. Typically, the mass of the balancing mass block BM is significantly larger than the mass of both the moving part of the second positioner PW and the substrate support WT.

[0062] In one embodiment, the second positioner PW is supported by a balancing mass block BM. For example, the second positioner PW includes a planar motor to suspend the substrate support WT above the balancing mass block BM. In another embodiment, the second positioner PW is supported by a base frame BF. For example, the second positioner PW includes a linear motor and a bearing, such as a gas bearing, to suspend the substrate support WT above the base frame BF.

[0063] The Position Measurement System (PMS) can include any type of sensor suitable for determining the position of the substrate stage WT. The PMS can also include any type of sensor suitable for determining the position of the mask support MT. This sensor can be an optical sensor, such as an interferometer or encoder. The PMS can include a combined system of interferometers and encoders. The sensor can also be another type of sensor, such as a magnetic sensor, a capacitive sensor, or an inductive sensor. The PMS can determine the position relative to a reference, such as a measurement frame MF or a projection system PS. The PMS can determine the position of the substrate stage WT and / or the mask support MT by measuring the position or by measuring the time derivative of the position, such as velocity or acceleration.

[0064] A position measurement system (PMS) may include an encoder system. An encoder system is known from, for example, U.S. Patent Application US2007 / 0058173A1, filed September 7, 2006, which is incorporated herein by reference. The encoder system includes 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 created by diffracting the original radiation beam using a grating. If both the primary and secondary radiation beams are created by diffracting the original radiation beam using a grating, the primary radiation beam needs to have a different diffraction order than the secondary radiation beam. Different diffraction orders are, for example, +1st, -1st, +2nd, and -2nd orders. The encoder system optically combines the primary and secondary radiation beams into 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 the phase or phase difference. This signal represents the position of the encoder head relative to the grating. One of the encoder head and the grating can be arranged on the substrate structure WT. The other of the encoder head and the grating can be arranged on the measurement frame MF or the base frame BF. For example, multiple encoder heads are arranged on the measurement frame MF, while the grating is arranged on the top surface of the substrate support WT. In another example, the grating is arranged on the bottom surface of the substrate support WT, and the encoder head is arranged below the substrate support WT.

[0065] A position measurement system (PMS) may include an interferometer system. An interferometer system can be known from, for example, U.S. Patent 6,020,964, filed July 13, 1998, which is incorporated herein by reference. The interferometer system may include a beam splitter, a mirror, a reference mirror, and a sensor. A radiation beam is split into a reference beam and a measurement beam by the beam splitter. The measurement beam propagates to the mirror and is reflected back to the beam splitter. The reference beam propagates to the reference mirror and is reflected back to the beam splitter. At the beam splitter, the measurement beam and the reference beam are combined into a combined radiation beam. The combined radiation beam is incident on the sensor. The sensor determines the phase or frequency of the combined radiation beam. The sensor generates a signal based on the phase or frequency. This signal represents the displacement of the mirror. In one embodiment, the mirror is connected to a substrate support WT. The reference mirror may be connected to a measurement frame MF. In one embodiment, the measurement beam and the reference beam are combined into a combined radiation beam by additional optical components instead of a beam splitter.

[0066] The first positioner PM may include a long-stroke module and a short-stroke module. The short-stroke module is configured to move the mask support MT with high precision relative to the long-stroke module within a small range of motion. The long-stroke module is configured to move the short-stroke module relative to the projection system PS with relatively low precision within a large range of motion. Using the combination of the long-stroke and short-stroke modules, the first positioner PM can move the mask support MT relative to the projection system PS with high precision within a large range of motion. Similarly, the second positioner PW may include a long-stroke module and a short-stroke module. The short-stroke module is configured to move the substrate support WT with high precision relative to the long-stroke module within a small range of motion. The long-stroke module is configured to move the short-stroke module relative to the projection system PS with relatively low precision within a large range of motion. Using the combination of the long-stroke and short-stroke modules, the second positioner PW can move the substrate support WT relative to the projection system PS with high precision within a large range of motion.

[0067] The first positioner PM and the second positioner PW are each provided with actuators to move the mask support MT and the substrate support WT, respectively. The actuators can be linear actuators to provide a driving force along a single axis (e.g., the y-axis). Multiple linear actuators can be applied to provide driving forces along multiple axes. The actuators can be planar actuators to provide driving forces along multiple axes. For example, a planar actuator can be arranged to move the substrate support WT in six degrees of freedom. The actuator can 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 can be a moving magnet type actuator having at least one magnet coupled to the substrate support WT and the mask support MT, respectively. The actuator can be a moving coil type actuator having at least one coil coupled to the substrate support WT and the mask support MT, respectively. The actuator can be a voice coil actuator, a magnetoresistive actuator, a Lorentz actuator, or a piezoelectric actuator, or any other suitable actuator.

[0068] The lithography apparatus LA includes a position control system (PCS), such as... Figure 3The position control system (PCS) includes a setpoint generator (SP), a feedforward controller (FF), and a feedback controller (FB). The PCS provides a drive signal to an actuator (ACT). The actuator (ACT) can be an actuator of a first positioner (PM) or a second positioner (PW). The actuator (ACT) drives a device (P), which may include a substrate support (WT) or a mask support (MT). The output of the device (P) is a position quantity, such as position, velocity, or acceleration. The position quantity is measured using a position measurement system (PMS). The PMS generates a signal representing the position quantity of the device (P). The setpoint generator (SP) generates a signal representing the desired position quantity of the device (P). The difference between the reference signal and the position signal forms the input to the feedback controller (FB). Based on this input, the feedback controller (FB) provides at least one component of the drive signal to the actuator (ACT). The reference signal may form the input to the feedforward controller (FF). Based on this input, the feedforward controller (FF) provides at least one component of the drive signal to the actuator (ACT). The feedforward controller (FF) may utilize information about the dynamic characteristics of the device (P), such as mass, stiffness, resonant modes, and eigenfrequency.

[0069] exist Figure 4 The diagram illustrates a first embodiment of a coil according to the invention, designated by reference numeral 1. The coil 1 comprises a plurality of coil conductors 10, i.e., windings, formed of a plurality of electrically insulated flat wires. Figure 4 In the schematic diagram, coil 1 includes five conductors 10, although it should be understood that in practice, coil may include a greater number of conductors.

[0070] All coils shown in the figure include coil conductors, which are obtained by winding wires into a loop. Therefore, coil conductors are sometimes referred to as the “windings” of the coil. Alternatively, however, the invention also contemplates so-called “hairpin” type coils, in which the coil is assembled from various individual and interconnected conductors.

[0071] The coil conductor 10 is configured to conduct current during use to generate an electromagnetic field. Figure 4 The plane of the coil 1 is aligned parallel to the plane of the coil conductor 10, wherein the electromagnetic field will be drawn from the coil 1 along a path perpendicular to the plane of the coil. Figure 4 The coil conductors 10 are arranged adjacent to each other along the stacking direction S, which is aligned in the coil plane to obtain a so-called "racetrack" coil. In fact, for clarity, the coil conductors 10 are shown as concentric loops in the figure, while the coil conductors can actually be described together as a helical path.

[0072] This coil 1 is made of flat wire coil conductor 10, wherein the term "flat wire" should be understood as adjacent conductors 10 contacting each other over a relatively large width, i.e., compared to their thickness in the stacking direction S. Figure 4 In the illustration, conductors 10 have a large height in the direction perpendicular to the coil plane and the drawing plane, compared to their thickness in the stacking direction S. Compared to other coils, such as where the conductors can have a circular cross-section, flat wire coil conductors can provide the benefit that heat transfer between individual conductors 10 in the stacking direction S has been improved.

[0073] The coil 1 also includes a cooling fluid channel 20 that extends across the coil 1 in a direction substantially parallel to the plane of the coil. The cooling fluid channel 20 is formed by a plurality of holes 21 extending laterally through all the coil conductors 10. The cooling fluid channel 20 is in thermal contact with the coil conductors 10. During use, a cooling fluid flow F is directed through the cooling fluid channel 20, allowing heat from the coil conductors to be transferred to the cooling fluid.

[0074] exist Figure 4 In the coil 1 shown, cooling fluid flows back and forth in the cooling fluid channel 20. Therefore, as Figure 4 As indicated by the arrows, the flow direction of the cooling fluid is opposite between adjacent holes 21, causing the cooling fluid to flow in opposite directions within adjacent holes 21. This means that all holes 21 in coil 1 are fluidly connected in series.

[0075] Figure 5 An alternative embodiment of coil 101 is shown, wherein cooling fluid channels 120 are also formed by adjacent through-holes 121, similar to... Figure 4 However, in Figure 5 In one embodiment, the direction of the cooling fluid flow F in each hole 121 is aligned parallel to each other, which means that all holes 121 in the coil 101 extend parallel through the coil conductor 110.

[0076] Figure 6 Another alternative embodiment of the coil 201 is depicted, wherein the cooling fluid channel 220 includes a plurality of transverse holes 221 distributed above the periphery of the conductor 210. Thus, the holes 221 extend from the inner surface 202 of the coil 201 toward its outer surface 203, wherein the cooling fluid flow F is guided from the interior of the coil 201 toward the exterior. Similarly, another alternative embodiment of the coil can be conceived as a cooling fluid channel consisting of transverse holes, wherein the cooling fluid flow is guided from the exterior of the coil to the interior, i.e., with… Figure 6 The flow is opposite.

[0077] Coil 201 also includes a cooling fluid connector 230, which is fluidly connected to an aperture 221 of the cooling fluid channel 220. The cooling fluid connector 230 can be connected to an external cooling fluid source (not visible in the figure) from which a cooling fluid flow F can be received during use. The cooling fluid connector 230 is arranged in the central aperture A of coil 201 such that it is surrounded by coil conductor 210. The cooling fluid connector 230 is configured to receive a cooling fluid flow from the cooling fluid source and to direct the cooling fluid flow F into the cooling fluid channel 220. The position of the cooling fluid connector 230 in the central aperture A of coil 201 is advantageous because the outer surface 203 of coil 201 is substantially exposed, allowing the magnet of the electromagnetic actuator to be positioned near coil 201.

[0078] Figure 7 A side view of an embodiment of coil 301 is depicted. Figure 7 Coil 301 in the middle is also a runway coil, in which the observation direction is parallel to the stacking direction S of coil 301 is aligned. Figure 7 The diagram shows that coil 301 includes a cooling fluid channel consisting of four through-holes 321, which extend laterally through all stacked coil conductors 310 in a direction parallel to the stacking direction S. Figure 7 As can be seen, the drilled cooling fluid hole 321 is completely surrounded by the coil conductor 310, so that the cooling fluid can contact the conductor 310 at the entire perimeter of the hole 321.

[0079] In this embodiment, each hole 321 includes a coating 322, which is applied to the coil conductor 310. However, the presence of a coating is not necessarily necessary for all holes. The coating 322 is disposed on the peripheral surface of the holes 321 that define the interior of the coil conductor 310. This coating 322 is a corrosion-resistant, electrically insulating, and thermally conductive coating, and includes several different coatings. The coating 322 primarily includes a ceramic coating, which is applied directly to the coil conductor 310 and is made of diamond-like carbon (DLC), a ceramic material with desired corrosion resistance, electrical insulation, and thermal conductivity properties. Additionally, the coating 322 includes a polymer coating made of parylene applied over the ceramic coating. The polymer coating is also advantageous in addition to the ceramic coating because pinholes can exist in the ceramic coating, which are filled with the polymer material. The coating 322 is applied to the holes 321 by means of a chemical vapor deposition process.

[0080] Figure 8Side views of different embodiments are depicted, including 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, such that coils 401 and 451 can generate a combined magnetic field together. Coils 401 and 451 face each other with their end surfaces 404 and 454 facing each other, and they are electrically insulated from each other by an electrical insulating layer 405. Cooling fluid channels are formed by holes 421 provided at the interface of coils 401 and 451. Thus, during use, cooling fluid will contact the coil conductor 410 of the first coil 401 and the coil conductor 460 of the second coil 451, allowing heat to be extracted from both coils 401 and 451 into the cooling fluid.

[0081] Figure 9 A plan view of another embodiment of coil 501 is depicted, wherein the cooling fluid channel is formed by four open recesses 525, these recesses in Figure 9 The dotted lines are used for indication. Figure 11 In the diagram, the same coil 501 is shown in a cross-sectional view. In this embodiment, a groove 525 is provided in the head end surface 504 of the coil 501, which is Figure 8 The cooling fluid channel describes an annular path across the head end surface 504 of the coil 501, extending circumferentially along the coil conductor 510. The groove 525 of the cooling fluid channel thus substantially follows the path of the conductor 510, which is advantageous in this embodiment where the coil is implemented as a racetrack coil 501, wherein all conductors 510 lie within a single coil plane, i.e., parallel to the plane of the figures.

[0082] The groove 525 of the cooling fluid channel is formed in the conductor 510 of the coil 501 by means of a subtractive manufacturing method, thereby removing material from the coil conductor 510. In this embodiment, the cooling fluid channel is obtained by milling the groove 525 through the coil conductor 510 at the head end surface 504 of the coil 501.

[0083] Figure 10 A perspective cross-section of another embodiment of coil 601 is depicted, in which cooling fluid channels 620 depict a meandering, back-and-forth path across the head end surface 604 of coil 601. The cooling fluid channels 620 are also formed by grooves 625, the meandering paths of which mean they extend laterally across the individual coil conductors 610.

[0084] The cooling fluid passage 620 is further subdivided into two recesses forming a supply section 626 and a single recess forming a cooling fluid return section 627. The supply and return sections are fluidly connected in series and extend adjacent to each other via coil 601. The supply section 626 and return section 627 are aligned antiparallel to each other such that the flow direction of the cooling fluid in the supply section is opposite to the flow direction of the cooling fluid in the return section, as by means of... Figure 10 As indicated by the middle arrow. The cooling fluid in the supply section 626, which has just exited the cooling fluid source, can be relatively cold, while the cooling fluid in the return section 627, which has passed through the longer length of coil 601, can be relatively hot. Over the length of the cooling fluid channel 620, the net cooling fluid temperature, i.e., the temperature of the combined cooling fluid flow in the supply and return sections, can be relatively constant, which can provide more uniform heat dissipation from conductor 610.

[0085] The return section 627 is centrally positioned between the two supply sections 626, such that, viewed from any point along the length of the cooling fluid passage 620, the return section 627 is surrounded on opposite sides by the supply sections 626. The outward placement of the supply sections 626 means that, during use, the outermost section of the cooling fluid passage 620 contains the cooling fluid at its lowest temperature. This can be advantageous at the outermost edge conductor 611 and the innermost edge conductor 612 of the coil 601, which abut against the other conductors 610 only on one side, to maximize cooling in the edge conductors 611, 612. Figure 11 Depicting Figure 9 The cross-sectional view of coil 501 along line AA shows four grooves 525 provided in conductor 510 at the head end surface 504 of coil 501. For clarity, conductor 510 has... Figure 11 It is depicted as a single conductor.

[0086] The groove 525 may have a rectangular cross-section, allowing cooling fluid to contact the conductor 510 on three sides of the groove 525, but other types of cross-sections, such as semi-circular or circular cross-sections, are also conceivable. The groove 525 has a depth D perpendicular to the head end surface 504, which is relatively shallow compared to its width W in the stacking direction S. Alternatively, however, the groove may be configured to be relatively deep compared to its width. In another alternative embodiment, the groove may have a circular or circular cross-section.

[0087] The coil 501 is also provided with a cover element 540 above the groove 525 to cover the open groove 525 from above and to provide a closed cooling fluid passage to prevent cooling fluid leakage.

[0088] Figure 12 A cross-sectional view of an alternative embodiment is depicted, wherein the first coil 701 is coupled with... Figure 8The embodiment is arranged adjacent to the second coil 751 in a similar manner. The coil planes of coils 701 and 751 extend parallel to each other, enabling coils 701 and 751 to generate a combined magnetic field together. Coils 701 and 751 face each other with their end surfaces 704 and 754 facing each other, and they are electrically insulated from each other by an electrical insulating layer 705. A cooling fluid channel 720 is formed by three grooves 725 in the first coil 701 and three grooves 775 in the second coil 751, these three grooves facing each other, so that they together define the fluid flow path of the cooling fluid. In this way, a cooling fluid channel 720 is formed between the two coils 701 and 751, and the two coils 701 and 751 can be cooled by a single flow of cooling fluid.

[0089] It is manufactured by first forming a first coil 701 having a first coil conductor 710 and a second coil 751 having a second coil conductor 760. Figure 12The embodiments described herein. Next, grooves 725 and 775 are milled in the head end surfaces 704 and 754 of the respective coils 701 and 751, and finally, the coils 701 and 751 are arranged adjacent to each other such that the cooling fluid channel 720 is ultimately formed by the respective opposing grooves 725 and 775. Optionally, after milling the grooves 725 and 775 and before arranging the coils 701 and 751 adjacent to each other, a coating may be applied to the coils, covering the walls of the grooves 725 and 775 and the head end surfaces 704 and 754, or covering the entire coil. The coating may include multiple different coatings. For example, the coating may include one or more ceramic coatings made of ceramic materials. As an example, the ceramic coating may be made of diamond-like carbon (DLC) or aluminum nitride, which are found to have desirable corrosion resistance, electrical insulation, and thermal conductivity properties. Additionally or alternatively, the coating may include one or more polymer coatings, such as those made of parylene. In addition to ceramic coatings, polymer coatings are also advantageous because ceramic coatings can contain pinholes that can be filled with polymer materials. One or more polymer coatings can be applied over one or more ceramic coatings or directly onto the coil conductors, for example, under the ceramic coating, as an intermediate layer to improve the adhesion of the ceramic coating. Additionally or alternatively, the coating may include a multilayer coating comprising one or more polymer layers, such as those made of parylene, and one or more atomic layer deposition (ALD) coatings, such as those made of inorganic materials such as alumina, titanium oxide, and hafnium oxide. After coating, adhesive can then be applied to the end surfaces 704, 754 to bond adjacent coated coils 701, 751 such that coated cooling fluid channels 720 are formed by corresponding opposing grooves 725, 775. Alternatively or additionally, the coating coils can be bonded by thermal bonding, such as by first melting at least one component of the coating material at a temperature above a certain level, and then bonding the coated end surfaces together using at least partially melted coating material.

[0090] Figure 13 A cross-sectional view of another alternative embodiment of coil 801, a so-called "edge-wound" type coil, is depicted. Figure 13In coil 801, the coil plane extends parallel to the plane of the attached drawing, and the stacking direction S is aligned perpendicular to both the coil plane and the plane of the attached drawing. In coil 801, cooling fluid channels extend through coil 801 in a direction substantially perpendicular to the coil plane, and therefore parallel to the stacking direction S. The cooling fluid channels are formed by four recesses 825 disposed in the outer surface 803 of coil 801, evenly distributed above the perimeter of conductor 810. Coil 801 also includes a cover element embodied as a cover ring 840, which surrounds conductor 810 and covers the open recesses 825 from the outside to provide closed cooling fluid channels to prevent cooling fluid leakage.

[0091] Figure 13 The grooves 825 in the embodiments also have rectangular cross-sections, but the relationship between their depth D and width W is relative to... Figure 11 The coils shown are different. Figure 13 In the coil 801, as best seen in the enlarged view in the upper right corner, the grooves 825 have a depth D when viewed from the outer surface 803 of the coil 801. This depth is relatively large compared to their width W along the perimeter of the conductor 810, which means that these grooves 825 are relatively deep relative to their width.

[0092] Figure 14 A cross-sectional view of another embodiment is depicted, which includes a first coil 901 and a second coil 951 arranged concentrically with each other. The second coil (e.g., an inner coil) 951 is thus placed in the central aperture A' of the first coil (e.g., an outer coil) 901, and the coil planes of the two coils 901 and 951 extend parallel to each other, enabling the coils 901 and 951 to generate a combined magnetic field together. Furthermore, the inner surface 902 of the first coil 901 and the outer surface 953 of the second coil 951 are thus in contact with each other through an electrical insulating layer 905.

[0093] The grooves 925 and 975 of coils 901 and 951 face each other and are opposite to each other. Thus, the cooling fluid channel is formed by four grooves 925 in the inner surface 902 of the conductor 910 of the first coil 901 and four grooves 975 in the outer surface 953 of the conductor 960 of the second coil 951. In this way, both coils 901 and 951 can be cooled by a single flow of cooling fluid through the opposing grooves 925 and 975. In this embodiment of the coils, no cover element is provided 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, because the cooling fluid channel 920 is completely enclosed between the conductors 910 and 960 of the two coils 901 and 951.

[0094] Figure 15A perspective view depicting another alternative embodiment of coil 1001, which is a so-called "edge-wound" type coil. Figure 15 In coil 1001, the coil plane extends perpendicular to the stacking direction S. In coil 1001, cooling fluid channels extend across coil 1001 in a direction substantially perpendicular to the coil plane, and are therefore parallel to the stacking direction S. The cooling fluid channels are formed by grooves 1025, which are disposed in the outer surface 1003 of coil 1001 and are evenly distributed above the perimeter of conductor 1010. Grooves 1025 are open-faceted and have a circular cross-section.

[0095] Figure 15 The coil 1001 depicted may also include Figure 16 The cover element depicted is embodied as a cover ring 1040 surrounding the conductor 1010 and covering the open recess 1025 from the outside to provide a closed cooling fluid passage to prevent cooling fluid leakage.

[0096] Figure 17 A perspective view of another embodiment is depicted, which includes a first coil 1101 and a second coil 1151 arranged concentrically with each other. The second coil (e.g., an inner coil) 1151 is thus placed in the central aperture A' of the first coil (e.g., an outer coil) 1101, and the coil planes of the two coils 1101 and 1151 extend parallel to each other, enabling the coils 1101 and 1151 to generate a combined magnetic field together. Furthermore, the inner surface 1102 of the first coil 1101 and the outer surface 1153 of the second coil 1151 are thus in contact with each other through an electrical insulating layer 1105.

[0097] The grooves 1125 and 1175 of coils 1101 and 1151 face each other and have circular cross-sections. Thus, a cooling fluid channel is formed by the groove 1125 in the inner surface 1102 of the conductor 1110 of the first coil 1101 and the groove 1175 in the outer surface 1153 of the conductor 1160 of the second coil 1151. In this way, both coils 1101 and 1151 can be cooled by a single flow of cooling fluid through the opposing grooves 1125 and 1175. This embodiment of the coils may also be free of capping 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, because the cooling fluid channel 1120 is completely enclosed between the conductors 1110 and 1160 of the two coils 1101 and 1151.

[0098] Figure 18A plan view of another embodiment of coil 1201 is depicted, wherein cooling fluid channel 1220 depicts a meandering, back-and-forth path across the head end surface 1204 of coil 1201, which is the plane of the figure. Similar to... Figure 10 The groove 625 in the middle, the cooling fluid channel 1220 is also formed by the open groove 1225. With Figure 10 Compared to the coil, Figure 18 The meandering paths mean that they extend primarily along the coil conductors, while forming back-and-forth side steps 1208 on a smaller number of various coil conductors 1210 (e.g., two or three). These side steps create turbulence in the cooling fluid flow, which can distribute current density and heat generation over the coil conductors and improve cooling performance. At least one supply section 1226 and at least one return section 1227 are provided for the cooling fluid channel 1220, which are fluidly connected in series. Preferably, the supply sections are arranged as the innermost and outermost sections of the cooling fluid channel, such that during use, the innermost and outermost sections of the cooling fluid channel contain the cooling fluid at its lowest temperature. This can be advantageous at the outermost or innermost edge conductors of the coil. These conductors may not intersect the cooling fluid channel, i.e., in the case of being embodied as recesses, as this could cause leakage. For this purpose, the edge conductors are positioned near the coldest cooling fluid in the supply section, outside the return section, to maximize cooling in the edge conductors.

[0099] The supply and return sections are aligned essentially antiparallel to each other, such that the flow direction of the cooling fluid in the supply section is opposite to the flow direction of the cooling fluid in the return section, as achieved by means of... Figure 18 As indicated by the middle arrow. The cooling fluid in the supply section 1226 from the cooling fluid source can be relatively cold, while the cooling fluid in the return section 1227, which has already passed through the longer length of coil 1201, can be relatively hot. Over the length of the cooling fluid channel 1220, the net cooling fluid temperature, i.e., the temperature of the combined cooling fluid flow in the supply and return sections, can be relatively constant, which can provide more uniform heat dissipation from conductor 1210. Optionally, a cooling fluid manifold 1207 can be arranged in the core 1206 of the coil to deliver cooling fluid to and from the supply and return sections 1226 and 1227 in a space-efficient manner.

[0100] Figure 19(a) depicts a perspective view of another embodiment of coil 1301, which comprises an "edge-wound" type coil having a rectangular shape with rounded corners as seen along the stacking direction S. In coil 1301, the coil plane extends perpendicular to the stacking direction S. Figure 19(b) is a cross-sectional perspective view of coil 1301 taken along line 19B-19B and perpendicular to the coil plane. In this coil 1301, cooling fluid channels 1320 extend across 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 coil 1301 and evenly distributed over the length of each side of conductor 1310. Preferably, the holes 1325 penetrate the coil conductor. In this coil 1301, cooling fluid can be supplied and returned at opposite end surfaces 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).

[0101] Figure 20(a) depicts a perspective view of an alternative embodiment of coil 1401, which comprises an "edge-wound" type coil having a rectangular shape with rounded corners as seen 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 along line 20B-20B and perpendicular to the coil plane. In this coil 1401, a V-shaped cooling fluid channel 1420 extends across 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 includes a supply section 1426 and a return section 1427, such that cooling fluid is supplied to and returns from the same end surface of the coil, as indicated by the arrows in Figure 20(b). V-shaped cooling fluid channels are provided on each side of coil 1401. Optionally, more than one V-shaped cooling fluid channel 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 passage is formed by a hole 1425 with a circular cross-section. Preferably, the supply section hole and the return section hole pass through various coil conductor boreholes and a connection point 1408 is formed by the drilling process, so that the supply section 1426 and the return section 1427 are fluidly connected.

[0102] While specific embodiments of the invention have been described above, it should be understood that the invention can be practiced in ways other than those described. The above description is intended to illustrate and not limit. Therefore, it will be apparent to those skilled in the art that modifications can be made to the described invention without departing from the scope of the claims set forth below. Other aspects of the invention are set forth in the following numbered clauses. 1. A fluid-cooled coil in an electromagnetic actuator for a photolithography apparatus, the coil being formed of a plurality of electrically insulated flat wire coil conductors and configured to conduct current during use to generate an electromagnetic field, and comprising: At least one cooling fluid channel, in thermal contact with the coil, is provided to guide the flow of cooling fluid to remove heat from the coil. Its features are, The cooling fluid channel is provided across the coil and passes through multiple coil conductors. 2. The coil as described in Clause 1, wherein the cooling fluid passage passes through substantially all of the coil conductors. 3. The coil according to clause 1 or 2, wherein the cooling fluid channel extends across the coil in a direction having at least one component that is substantially parallel to the coil plane in which the coil conductor extends. 4. The coil according to Clause 1 or 2, wherein the cooling fluid channel extends across the coil in a direction having at least one component that is substantially perpendicular to the coil plane in which the coil conductor extends. 5. The coil according to any one of the preceding clauses, wherein the cooling fluid channel is formed by at least one hole that extends laterally through the coil conductor. 6. The coil according to any one of clauses 1-4, wherein the cooling fluid channel is formed by at least one groove extending across the coil conductor at the inner surface, outer surface or head end surface of the coil. 7. The coil as described in Clause 6, comprising a plurality of coils, The coils are arranged adjacent to each other, with their coil conductors extending parallel to each other and spaced apart by a distance. The opposing ends of the coils are in contact with each other through an electrical insulating layer, and The cooling fluid channels are formed by opposing grooves in each coil of the coil, each groove extending through its respective coil conductor at its opposing end surfaces. 8. The coil as described in Clause 6, comprising a plurality of said coils, The coils are arranged concentrically to each other, with their coil conductors extending coplanarly. 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, and The cooling fluid channels are formed by opposing grooves in each coil of the coil, each groove extending through its respective coil conductor at its opposing inner and outer surfaces. 9. The coil according to any one of clauses 6-8 further includes a cover element disposed on the inner surface, outer surface or head end surface of the coil to cover a groove. 10. The coil according to any one of the foregoing clauses further includes a coating on the coil conductor in the cooling fluid channel. 11. The coil according to Clause 10, wherein the coating comprises one or more ceramic coatings, such as those made of diamond-like carbon (DLC) or aluminum nitride, and / or one or more polymer coatings, such as those made of parylene. 12. The coil according to any one of the foregoing clauses further includes a cooling fluid connector fluidly connected to the cooling fluid channel. The cooling fluid connector is capable of connecting to an external cooling fluid source, and the cooling fluid connector is arranged in the central aperture of the coil and surrounded by the coil conductor. 13. The coil according to any one of the preceding clauses, wherein the cooling fluid channel describes an annular path extending in a circumferential direction across the coil and along the coil conductor. 14. The coil according to any one of clauses 1-12, wherein the cooling fluid passage describes a meandering, back-and-forth path across the coil. 15. The coil according to any one of the preceding clauses, wherein the cooling fluid passage is subdivided into at least one supply section and at least one return section, the supply section and the return section being 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, and The at least one supply section and the at least one return section are antiparallel to each other, such that 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. 16. The coil as described in Clause 15, comprising two supply sections in the supply section and a single return section in the return section, and The return section is centrally located between the two supply sections. 17. The coil according to Clause 15, wherein at least one of the supply sections and at least one of the return sections describe a double helix path through the coil. 18. The coil according to any one of the preceding clauses, wherein the flat wire coil conductor has a rectangular cross-section. 19. An exposure apparatus, such as a photolithography apparatus, comprising a coil according to any one of the preceding clauses. 20. A method of manufacturing a coil according to any one of clauses 1-18, comprising the following steps: The coil is formed by multiple flat wire coil conductors, and The cooling fluid channel is formed across the coil. 21. The method according to Clause 20, wherein the step of forming the cooling fluid channel includes the sub-manufacturing of the cooling fluid channel, such as laser ablation, etching, drilling, milling, or electrical discharge machining. 22. The method according to clause 20 or 21, wherein the step of forming the cooling fluid channel includes drilling at least one hole through the plurality of coil conductors laterally. 23. The method according to clause 20 or 21, wherein the step of forming the cooling fluid channel includes milling at least one groove through the coil conductor. 24. The method according to any one of clauses 20-23 further includes the step of coating the coil conductor in the cooling fluid channel with a coating, for example by means of physical vapor deposition and / or (plasma-enhanced) chemical vapor deposition.

Claims

1. A fluid-cooled coil in an electromagnetic actuator for a photolithography apparatus, the coil being formed of a plurality of electrically insulated flat wire coil conductors and configured to conduct current during use to generate an electromagnetic field, and comprising: At least one cooling fluid channel, in thermal contact with the coil, is provided to guide the flow of cooling fluid to remove heat from the coil. Its features are, The cooling fluid channel is provided across the coil and passes through multiple coil conductors.

2. The coil of claim 1, wherein the cooling fluid channel passes through substantially all of the coil conductors.

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

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

5. The coil according to any one of the preceding claims, wherein the cooling fluid channel is formed by at least one hole that extends laterally through the coil conductor.

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

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

8. The coil of claim 7, wherein the coating comprises one or more ceramic coatings, such as those made of diamond-like carbon (DLC) or aluminum nitride, and / or one or more polymer coatings, such as those made of parylene.

9. The coil according to any one of the preceding claims further includes a cooling fluid connector fluidly connected to the cooling fluid channel. The cooling fluid connector is capable of connecting to an external cooling fluid source, and the cooling fluid connector is arranged in the central aperture of the coil and surrounded by the coil conductor.

10. The coil according to any one of the preceding claims, wherein the cooling fluid channel describes an annular path extending in a circumferential direction across the coil and along the coil conductor.

11. The coil according to any one of claims 1-9, wherein the cooling fluid channel describes a meandering, back-and-forth path across the coil.

12. The coil according to any one of the preceding claims, wherein the cooling fluid passage is subdivided into at least one supply section and at least one return section, the supply section and the return section being 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, and The at least one supply section and the at least one return section are antiparallel to each other, such that 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 the preceding claims, wherein the flat wire coil conductor has a rectangular cross-section.

14. An exposure apparatus, such as a photolithography apparatus, comprising a coil according to any one of the preceding claims.

15. A method for manufacturing a coil according to any one of claims 1-13, comprising the following steps: The coil is formed by multiple flat wire coil conductors, and The cooling fluid channel is formed across the coil.

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