WO2018046280A1

WO2018046280A1 - Lithographic apparatus and support structures background

Info

Publication number: WO2018046280A1
Application number: PCT/EP2017/070896
Authority: WO
Inventors: Andrew JUDGE
Original assignee: Asml Holding N.V.
Priority date: 2016-09-09
Filing date: 2017-08-18
Publication date: 2018-03-15
Also published as: TW201812986A; JP2019529970A; NL2019437A; CN109690406A; KR20190046986A

Abstract

A lithographic apparatus can include a stationary frame having a first electrical conductor, and a support structure configured to support an object. The support structure is movably coupled to the frame and has a second electrical conductor. The lithographic apparatus can also include a conductive fluid that electrically couples the first electrical conductor to the second electrical conductor.

Description

LITHOGRAPHIC APPARATUS AND SUPPORT STRUCTURES

BACKGROUND

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of U.S. Provisional Patent Application No.

62/385,623, which was filed on September 9, 2016, and which is incorporated herein in its entirety by reference.

FIELD

[0002] The present disclosure relates to lithographic apparatuses and support structures that support an object, for example, a substrate or a patterning device.

BACKGROUND

[0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, to manufacture integrated circuits (ICs). In such a case, a patterning device, for example, a mask or a reticle, can generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (for example, including part of, one, or several dies) on a substrate (for example, a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. Generally, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatuses include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the "scanning"-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0004] A lithographic apparatus typical includes at least one movable support structure that supports an object, for example, a substrate table that supports a substrate or a mask table that supports a patterning device. Electrical current for power or signals is provided to the movable support structure from a stationary source, for example, a frame, using one or more wires. Typically, these wires (and other components such as compressed air lines) are housed in a conduit carrier (for example, a cable slab or an umbilical cord) that provides conduit for the wires to pass from the stationary component to the movable support structure. Often the conduit carrier is configured to flex (for example, to fold and unfold) as the movable support structure moves within the lithographic apparatus, and as the conduit carrier flexes so too do the wires contained therein.

[0005] One source of system failure and contamination within the lithographic apparatus is the conduit carrier and the wires contained within the conduit carrier. As the conduit carrier and the wires flex due to the movement of the moveable support structure, the material forming the conduit carrier and the wires (for example, the material forming the conduit carrier or the polymer insulation of the wires) begins to wear. And ultimately, the conduit carrier and the wires wear to a point of system failure and/or generate contamination particles due to this wear.

SUMMARY

[0006] Accordingly, in some embodiments the use of conduit carriers and wires to transmit electrical current from a stationary component to the movable support structure within a lithographic apparatus is reduced or eliminating, thereby reducing or eliminating a source of system failure and contamination.

[0007] In some embodiments, a lithographic apparatus includes a stationary frame having a first electrical conductor, and a support structure configured to support an object. The support structure is movably coupled to the frame and has a second electrical conductor. The lithographic apparatus also includes a conductive fluid (for example, a fluid comprising a conductive metal such as mercury, a fluid comprising water and a salt, a fluid comprising plasma, or a fluid comprising ionized gas) that electrically couples the first electrical conductor to the second electrical conductor.

[0008] In some embodiments, the frame defines a cavity that contains the conductive fluid. The support can be configured to move a first distance along a first direction, and the cavity can have a dimension in the first direction equal to or greater than the first distance. The support can also be configured to move a second distance along a second direction different than the first direction, and the cavity can have a dimension in the second direction equal to or greater than the second distance. The cavity can overlap the support in a vertical direction. The lithographic apparatus can be configured to generate a gas flow that retains the conductive fluid within the cavity, or configured to generate a magnetic field that retains the conductive fluid within the cavity.

[0009] In some embodiments, the second electrical conductor includes a first portion submerged in the conductive fluid.

[0010] In some embodiments, the lithographic apparatus includes an electrical component electrically coupled to the second electrical conductor and coupled to the support structure such that the electrical component moves with the support structure. The electrical component can include a sensor configured to transmit or receive a signal transmitted via the conductive fluid. The electrical component can include a positioner configured to move the support structure.

[0011] In some embodiments, the lithographic apparatus includes an electrical component electrically coupled to the first electrical conductor. The electrical component can include a data processing apparatus configured to control a process of the lithographic apparatus.

[0012] In some embodiments, the conductive fluid includes mercury or gallium. In some embodiments, the conductive fluid includes a solvent and an electrolyte solute. The solvent can include water, and the electrolyte solute can include a salt, for example, sodium chloride. In some embodiments, the conductive fluid comprises a plasma or an ionized gas.

[0013] In some embodiments, the support structure includes a substrate table configured to support a substrate. In some embodiments, the support structure includes a mask table configured to support a patterning device.

[0014] Further features and advantages of the embodiments, as well as the structure and operational of various embodiments, are described in detail below with reference to the accompanying drawings. It is noted that the invention is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the relevant art(s) to make and use the invention.

[0016] FIG. 1A is a schematic illustration of a reflective lithographic apparatus, according to an embodiment.

[0017] FIG. IB is a schematic illustration of a transmissive lithographic apparatus, according to an embodiment.

[0018] FIG. 2 is a schematic plan view of a substrate table and substrate according to an embodiment.

[0019] FIG. 3 is a schematic, side-view illustration of a lithographic apparatus having a stationary frame and a movable support structure, according to an embodiment.

[0020] FIG. 4. is a schematic, plan-view illustration of the lithographic apparatus of FIG.

3, according to an embodiment.

[0021] FIG. 5 is a block diagram of a lithographic apparatus having a stationary frame and a movable support structure, according to an embodiment.

[0022] FIG. 6 is a schematic, side-view illustration of a lithographic apparatus configured to generate an air shower, according to an embodiment.

[0023] FIG. 7 is a schematic, side-view illustration of a lithographic apparatus configured to generate a magnetic field, according to an embodiment.

[0024] The features and advantages of the disclosed embodiments will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.

DETAILED DESCRIPTION

[0025] The disclosed embodiment(s) merely exemplify the invention. The scope of the invention is not limited to the disclosed embodiment(s). The invention is defined by the claims appended hereto. [0026] The embodiment(s) described, and references in the specification to "an example," "one embodiment," "an embodiment," "an example embodiment," "some embodiments," etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0027] Before describing such embodiments in more detail, however, it is instructive to present an example environment in which embodiments of this disclosure may be implemented.

[0028] Example Reflective and Transmissive Lithographic Systems

[0029] FIGs. 1A and IB are schematic illustrations of a lithographic apparatus 100 and lithographic apparatus 100', respectively, in which embodiments of this disclosure may be implemented. Lithographic apparatus 100 and lithographic apparatus 100' each include the following: an illumination system (illuminator) IL configured to condition a radiation beam B (for example, DUV or EUV radiation); a support structure (for example, a mask table) MT configured to support a patterning device (for example, a mask, a reticle, or a dynamic patterning device) MA and connected to a first positioner PM configured to accurately position the patterning device MA; and, a substrate support structure (for example, a substrate table) WT configured to hold a substrate (for example, a resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate W. Lithographic apparatuses 100 and 100' also have a projection system PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion (for example, comprising part of one or more dies) C of the substrate W. In lithographic apparatus 100, the patterning device MA and the projection system PS are reflective. In lithographic apparatus 100', the patterning device MA and the projection system PS are transmissive. In some embodiments, the projection system PS is catadioptric.

[0030] The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for directing, shaping, or controlling the radiation B. [0031] The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA, the design of the lithographic apparatuses 100 and 100', and other conditions, such as whether or not the patterning device MA is held in a vacuum environment. The support structure MT may use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. The support structure MT can be a frame or a table, for example, which can be fixed or movable, as required. The support structure MT can ensure that the patterning device is at a desired position, for example, with respect to the projection system PS.

[0032] The term "patterning device" MA should be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section, such as to create a pattern in the target portion C of the substrate W. The pattern imparted to the radiation beam B can correspond to a particular functional layer in a device being created in the target portion C, such as an integrated circuit.

[0033] The patterning device MA may be transmissive (as in lithographic apparatus 100' of FIG. IB) or reflective (as in lithographic apparatus 100 of FIG. 1A). Examples of patterning devices MA include reticles, masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography, and include mask types such as binary, alternating phase shift, and attenuated phase shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam B which is reflected by the mirror matrix.

[0034] The term "projection system" PS can encompass any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors, such as the use of an immersion liquid or the use of a vacuum. A vacuum environment can be used for EUV or electron beam radiation since other gases can absorb too much radiation or electrons. A vacuum environment can therefore be provided to the whole beam path with the aid of a vacuum wall and vacuum pumps.

[0035] Lithographic apparatus 100 and/or lithographic apparatus 100' can be of a type having two (dual stage) or more substrate support structures WT (and/or two or more mask tables). In such "multiple stage" machines, the additional substrate support structures WT can be used in parallel, or preparatory steps can be carried out on one or more tables while one or more other substrate support structures WT are being used for exposure.

[0036] Referring to FIGs. 1A and IB, the illuminator IL receives a radiation beam from a radiation source SO. The source SO and the lithographic apparatuses 100, 100' can be separate entities, for example, when the source SO is an excimer laser. In such cases, the source SO is not considered to form part of the lithographic apparatuses 100 or 100', and the radiation beam B passes from the source SO to the illuminator IL with the aid of a beam delivery system BD (in FIG. IB) including, for example, suitable directing mirrors and/or a beam expander. In other cases, the source SO can be an integral part of the lithographic apparatuses 100, 100'— for example when the source SO is a mercury lamp. The source SO and the illuminator IL, together with the beam delivery system BD, if required, can be referred to as a radiation system.

[0037] The illuminator IL can include an adjuster AD (in FIG. IB) for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer and/or inner radial extent (commonly referred to as "σ-outer" and "σ-inner," respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. In addition, the illuminator IL can comprise various other components (in FIG. IB), such as an integrator IN and a condenser CO. The illuminator IL can be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross section.

[0038] Referring to FIG. 1A, the radiation beam B is incident on the patterning device (for example, mask) MA, which is held on the support structure (for example, mask table) MT, and is patterned by the patterning device MA. In lithographic apparatus 100, the radiation beam B is reflected from the patterning device (for example, mask) MA. After being reflected from the patterning device (for example, mask) MA, the radiation beam B passes through the projection system PS, which focuses the radiation beam B onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF2 (for example, an interferometric device, linear encoder, or capacitive sensor), the substrate support structure WT can be moved accurately (for example, so as to position different target portions C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor IF1 can be used to accurately position the patterning device (for example, mask) MA with respect to the path of the radiation beam B. Patterning device (for example, mask) MA and substrate W can be aligned using mask alignment marks Ml, M2 and substrate alignment marks PI, P2. [0039] Referring to FIG. IB, the radiation beam B is incident on the patterning device

(for example, mask MA), which is held on the support structure (for example, mask table MT), and is patterned by the patterning device. Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. The projection system has a pupil PPU conjugate to an illumination system pupil IPU. Portions of radiation emanate from the intensity distribution at the illumination system pupil IPU and traverse a mask pattern without being affected by diffraction at a mask pattern create an image of the intensity distribution at the illumination system pupil IPU.

[0040] With the aid of the second positioner PW and position sensor IF (for example, an interferometric device, linear encoder, or capacitive sensor), the substrate support structure WT can be moved accurately (for example, so as to position different target portions C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor (not shown in FIG. IB) can be used to accurately position the mask MA with respect to the path of the radiation beam B (for example, after mechanical retrieval from a mask library or during a scan).

[0041] In general, movement of the mask table MT can be realized with the aid of a long- stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM. Similarly, movement of the substrate support structure WT can be realized using a long- stroke module and a short- stroke module, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask table MT can be connected to a short-stroke actuator only or can be fixed. Mask MA and substrate W can be aligned using mask alignment marks Ml, M2, and substrate alignment marks PI, P2. Although the substrate alignment marks (as illustrated) occupy dedicated target portions, they can be located in spaces between target portions (known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the mask MA, the mask alignment marks can be located between the dies.

[0042] Mask table MT and patterning device MA can be in a vacuum chamber, where an in-vacuum robot IVR can be used to move patterning devices such as a mask in and out of vacuum chamber. Alternatively, when mask table MT and patterning device MA are outside of the vacuum chamber, an out-of-vacuum robot can be used for various transportation operation, similar to the in-vacuum robot IVR. Both the in-vacuum and out-of-vacuum robots need to be calibrated for a smooth transfer of any payload (e.g., mask) to a fixed kinematic mount of a transfer station.

[0043] The lithographic apparatuses 100 and 100' can be used in at least one of the following modes:

[0044] 1. In step mode, the support structure (for example, mask table) MT and the substrate support structure WT are kept essentially stationary, while an entire pattern imparted to the radiation beam B is projected onto a target portion C at one time (i.e., a single static exposure). The substrate support structure WT is then shifted in the X and/or Y direction so that a different target portion C can be exposed.

[0045] 2. In scan mode, the support structure (for example, mask table) MT and the substrate support structure WT are scanned synchronously while a pattern imparted to the radiation beam B is projected onto a target portion C (i.e., a single dynamic exposure). The velocity and direction of the substrate support structure WT relative to the support structure (for example, mask table) MT can be determined by the (de-)magnification and image reversal characteristics of the projection system PS.

[0046] 3. In another mode, the support structure (for example, mask table) MT is kept substantially stationary holding a programmable patterning device, and the substrate support structure WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C. A pulsed radiation source SO can be employed and the programmable patterning device is updated as required after each movement of the substrate support structure WT or in between successive radiation pulses during a scan. This mode of operational can be readily applied to maskless lithography that utilizes a programmable patterning device, such as a programmable mirror array of a type as referred to herein.

[0047] Combinations and/or variations on the described modes of use or entirely different modes of use can also be employed.

[0048] FIG. 2 schematically depicts an arrangement of substrate support structure WT depicted in the lithographic apparatuses of FIGs. 1A or IB, according to an embodiment in which substrate support structure WT includes an image sensor. In some embodiments, as shown in FIG. 2, substrate support structure WT includes two image sensors IAS 1 and IAS2. Image sensors IAS 1 and IAS2 can be used to determine a location of an aerial image of a pattern, e.g., an object mark, on mask MA by scanning the image sensor IAS 1 or IAS2 through the aerial image. The relative position of object marks on the mask MA with respect to the wafer table WT can be deduced from information obtained with the image sensors IAS 1, IAS2, and a number of parameters can be calculated from the measured positions of object marks on the mask MA. For example, such parameters of mask MA can include magnification of the MA (M), rotation about the z axis (R), translation along the x axis and the y axis of mask MA (Cx, Cy), magnification in the y direction (My), and scan skew (RI).

[0049] It must be understood that instead of two image sensors IAS 1 and IAS2, more or fewer image sensors may be present, e.g. one or three. The form of these sensors and electronics is known to the skilled person and will not be described in further detail. Alternative forms of alignment mechanism are possible, and useful within the scope of the present invention. In other embodiments, it may be possible to dispense with image sensors IAS 1, IAS2, or to provide them on a support separate from the wafer table which carries the substrate.

[0050] In a further embodiment, lithographic apparatus 100 includes an extreme ultraviolet (EUV) source, which is configured to generate a beam of EUV radiation for EUV lithography. In general, the EUV source is configured in a radiation system, and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

[0051] Exemplary Embodiments of a Lithographic Apparatus

[0052] FIG. 3 is a schematic side-view of a lithographic apparatus 100 including a frame

102, and a support structure 104 configured to support an object, according to an embodiment. Frame 102 can be stationary in some embodiments, and in other embodiments, frame 102 can be movable. In some embodiments, support structure 104 can be movably coupled to frame 102 such that support structure 104 moves relative to frame 102.

[0053] In some embodiments, lithographic apparatus 100 is similar to lithographic apparatus 100 or 100' in structure and function as described above with reference to FIGs. 1A and IB. In some embodiments, support structure 104 can be, for example, a mask table MT as discussed in FIGS. 1A and IB that is configured to support a patterning device (for example, a mask, a reticle, or a dynamic patterning device). In some embodiments, support structure 104 can be a substrate support structure WT as discussed in FIGS. 1A and IB that is configured to support a substrate such as a wafer. In some embodiments, frame 102 is an insulator.

[0054] Lithographic apparatus 100 can also include a conductive fluid 106 that conducts an electric current through the movement of electrons, ions, or both. In some embodiments, conductive fluid 106 has an electrical conductivity greater than the conductivity of pure water, i.e., greater than about 10^"4 mho/m.

[0055] In some embodiments, conductive fluid 106 includes, entirely or partially, mercury, gallium, any other suitable metal, or combination thereof that has a fluidic state at a temperature at which lithographic apparatus 100 operates.

[0056] In some embodiments, conductive fluid 106 includes, entirely or partially, a solvent and an electrolyte solute. For example, the solvent can be water, and the electrolyte solute can be a salt, such as sodium chloride or calcium chloride. In other embodiments, the solvent can be a fluid other than water, and the electrolyte solute can be a material other than a salt.

[0057] Frame 102 can include at least one electrical conductor 108 electrically coupled to conductive fluid 106, and support structure 104 can include at least one electrical conductor 110 electrically coupled to conductive fluid 106. As such, conductive fluid 106 electrically couples electrical conductor 108 to electrical conductor 110 such that an electrical current can be transmitted between electrical conductors 108 and 110. As discussed in more detail below, the transmitted electrical current can be, for example, an input signal, an output signal, or power to an electrical component.

[0058] Electrical conductors 108 and 110 can be any suitable electrical conductor comprising, for example, a solid conductive metal (e.g., copper or any other suitable solid conductive metal) or any other suitable solid conductive material. In some embodiments, electrical conductor 108 is a power or signal input/output electrical connector. In some embodiments, electrical conductor 110 is a bar or any other suitable structure composed of a solid conductive metal, for example, copper. Electrical conductor 110 can be coupled to support structure 104 such that conductor 110 moves along with support structure 104 in some embodiments.

[0059] In some embodiments, frame 102 defines a cavity 112 that contains conductive fluid 106. Cavity 112 is positioned such that at least a portion 114 of electrical conductor 110 contacts conductive fluid 106 (for example, portion 114 can be submerged in conductive fluid 106), and a portion 118 of electrical conductor 108 can also contact conductive fluid 106 in cavity 112 (for example, portion 118 can be submerged in conductive fluid 106). Thereby, conductive fluid 106 electrically couples electrical conductor 110 to electrical conductor 108. [0060] In some embodiments, cavity 112 is configured (e.g., shaped, sized, and positioned) such that portion 114 of electrical conductor 110 contacts conductive fluid 106 throughout some or the entire range of motion of movable support structure 104. For example, as shown in FIGS. 3 and 4, movable support structure 104 can be configured to move a first distance in a first direction 122 and a second distance in a second, different direction 124. In some embodiments, first and second directions 122 and 124 are perpendicular to each other as shown in FIGS. 3 and 4 and can correspond to the X and Y axes of lithographic apparatus 100. In such embodiments, cavity 112 can be shaped and sized to have a first dimension 126 in a direction parallel to direction 122 that accommodates movement of support structure 104 in the first direction 122, and cavity 112 can be shaped and sized to have a second dimension 128 parallel to second direction 124 that accommodates movement of support structure 104 in the second direction 124.

[0061] First and second dimensions 126 and 128 can be equal to the respective distances support structure 104 moves in the first and second directions 122 and 124 in some embodiments. Accordingly, if electrical conductor 110 is positioned at the center of support structure 104, electrical conductor 110 does not contact a peripheral wall defining cavity 112 until support structure 104 reaches its terminal position in either the first or second directions 122 and 124.

[0062] In other embodiments (as shown in FIGS. 3 and 4), first and second dimensions 126 and 128 can be greater than the respective distances support structure 104 moves in the first and second directions 122 and 124. Accordingly, if electrical conductor 110 is positioned at the center of support structure 104, electrical conductor 110 does not abut a peripheral wall defining cavity 112 at any point in the range of motion of support structure 104.

[0063] Referring collectively to FIGS. 3-5, electrical conductor 110 is, directly or indirectly, electrically coupled to one or more electrical components 130, which are coupled to movable support structure 104. In some indirect electrical coupling embodiments, electrical conductor 110 is electrically coupled to a bus bar coupled to movable support structure 104, and electrical component 130 is electrically coupled to the bus bar, which electrically couples electrical component 130 to electrical conductor 110. In some embodiments, a plurality of electrical components 130 can be coupled to the bus bar. In some indirect electrical coupling embodiments, electrical conductor 110 is electrically coupled to one or more signal processing or conditioning components, for example, amplifiers and filters, which are electrically coupled to electrical component 130.

[0064] Electrical component 130 can be any device that requires power, receives a signal, emits a signal, or any combination thereof at any point during operation of lithographic apparatus 100. For example, in some embodiments, electrical component 130 can be a long-stroke module (coarse positioning) or a short-stroke module (fine positioning) that form part of positioner PM or positioner PW as described above with reference to FIGS. 1A and IB. In some embodiments, electrical component 130 can be a sensor (for example, an interferometric device, linear encoder, or capacitive sensor). For example, electrical component 130 can be a sensor that composes position sensor IFl or position sensor IF2 that are used to position patterning device support MT or substrate support structure WT as described above with reference to FIGS. 1A and IB. Or for example, electrical component 130 can be a sensor composing image sensors IAS 1 and IAS2 that determine a location of an aerial image of a pattern, e.g., an object mark, on a patterning device MA as described above with reference to FIG. 2.

[0065] Referring collectively to FIGS. 3-5, electrical conductor 108 is directly or indirectly electrically coupled to one or more electrical components 132 that may or may not be coupled to frame 102. In some embodiments, electrical component 132 comprises a data processing apparatus, for example, a controller that controls all or some of the movements and measurements of the various components (for example, actuators and sensors) of lithographic apparatus 100. Exemplary data processing apparatuses include signal processing and data processing capacity to implement desired calculations relevant to the operation of lithographic apparatus 100. In some embodiments, the data processing apparatus is a system of many sub- units, each handling the real-time data acquisition, processing and control of a subsystem or component within lithographic apparatus 100. For example, one processing subsystem may be dedicated to servo control of positioner PW, and separate units may even handle coarse and fine actuators, or different axes. Another unit might be dedicated to the readout of position sensors IFl or IF2. Overall control of the lithographic apparatus 100 may be controlled by a central processing unit, communicating with these sub-systems processing units, with operators and with other apparatuses involved in the lithographic manufacturing process. The data processing apparatus can be a microprocessor in some embodiments, and can execute instructions recorded on a nontransitory computer readable storage medium such as a hard disk drive, floppy disk, optical disc such as a compact disc (CD) or digital versatile disc (DVD), flash memory, etc, in some embodiments.

[0066] In some embodiments, conductive fluid 106 partially or completely replaces the functionality of traditional conduit carriers that provide conduits for wires that electrically couple electrical components 130 and 132 and run between stationary frame 102 and movable support structure 104 and that used in lithographic apparatuses. Accordingly, in some embodiments, all or some of the conduit carriers that carry wires or other conductors to electrically couple electrical components 130 on movable support structure 104 to electrical components 132 not on movable support structure 104 can be omitted from lithographic apparatus 100, thereby reducing or eliminating the risk of system failure and/or contamination.

[0067] In some embodiments, lithographic apparatus 100 is configured to operate in a vacuum environment used with, for example, EUV or electron beam radiation. In some vacuum embodiments, lithographic apparatus 100 includes a mechanism for retaining conductive fluid 106 within cavity 112. FIGs. 6 and 7 illustrate two exemplary embodiments.

[0068] As shown in FIG. 6, lithograph apparatus 100 can be configured to create an air shower that retains conductive fluid 106 within cavity 112 in some embodiments. In some air- shower embodiments, conductive fluid 106 can have a low vapor pressure. For example, in some embodiments, conductive fluid 106 is an ionic liquid having a vapor pressure of about 100 pPa at room temperature (compared to pure water having a vapor pressure of about 3 kPa at room temperature). And lithographic apparatus 100 is configured to generate a gas flow 134 over the exposed surface of conductive fluid 106 in cavity 112. Gas flow 134 forms the air shower that retains conductive fluid 106 in cavity 112. In some embodiments, frame 102 includes an inlet 136 that introduces gas flow 134, and an outlet 138 that exhausts gas flow 134. In some embodiments, gas flow 134 is composed of one or more of helium, argon, hydrogen, nitrogen, or the like.

[0069] As shown in FIG. 7, lithographic apparatus 100 can be configured to create a magnetic field that repels conductive fluid 106 such that it is retained in cavity 112 in some embodiments. In some magnetic field embodiments, conductive fluid 106 is an ionized gas or plasma. For example, in some embodiments, the ionized gas or plasma comprises noble gases or mercury vapor. Lithographic apparatus 100 can also include a magnetic configured to generate a magnetic field 142 that repels conductive fluid 106 (e.g., ionized gas or plasma) in a manner that conductive fluid is retained in cavity 112. In some embodiments, magnet 140 is a permanent magnet. In other embodiments, magnetic 140 is an electromagnet.

[0069] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms "wafer" or "die" herein may be considered as synonymous with the more general terms "substrate" or "target portion", respectively. The substrate referred to herein may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool and/or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

[0070] Although specific reference may have been made above to the use of embodiments in the context of optical lithography, it will be appreciated that the embodiments may be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography. In imprint lithography a topography in a patterning device defines the pattern created on a substrate. The topography of the patterning device may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof. The patterning device is moved out of the resist leaving a pattern in it after the resist is cured.

[0071] It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.

[0072] In the embodiments described herein, the terms "lens" and "lens element," where the context allows, can refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic, and electrostatic optical components. [0073] Further, the terms "radiation" and "beam" used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) radiation (for example, having a wavelength λ of 365, 248, 193, 157 or 126 nm), extreme ultraviolet (EUV or soft X-ray) radiation (for example, having a wavelength in the range of 5-20 nm such as, for example, 13.5 nm), or hard X-ray working at less than 5 nm, as well as particle beams, such as ion beams or electron beams. Generally, radiation having wavelengths between about 400 to about 700 nm is considered visible radiation; radiation having wavelengths between about 780-3000 nm (or larger) is considered IR radiation. UV refers to radiation with wavelengths of approximately 100- 400 nm. Within lithography, the term "UV" also applies to the wavelengths that can be produced by a mercury discharge lamp: G-line 436 nm; H-line 405 nm; and/or, I-line 365 nm. Vacuum UV, or VUV (i.e., UV absorbed by gas), refers to radiation having a wavelength of approximately 100-200 nm. Deep UV (DUV) generally refers to radiation having wavelengths ranging from 126 nm to 428 nm, and in an embodiment, an excimer laser can generate DUV radiation used within a lithographic apparatus. It should be appreciated that radiation having a wavelength in the range of, for example, 5-20 nm relates to radiation with a certain wavelength band, of which at least part is in the range of 5-20 nm.

[0074] The term "substrate" as used herein generally describes a material onto which subsequent material layers are added. In embodiments, the substrate itself may be patterned and materials added on top of it may also be patterned, or may remain without patterning.

[0075] The term "in substantial contact" as used herein generally describes elements or structures that are in physical contact with each other with only a slight separation from each other which typically results from misalignment tolerances. It should be understood that relative spatial descriptions between one or more particular features, structures, or characteristics (e.g., "vertically aligned," "substantial contact," etc.) used herein are for purposes of illustration only, and that practical implementations of the structures described herein may include misalignment tolerances without departing from the spirit and scope of the present disclosure.

[0076] While specific embodiments have been described above, it will be appreciated that the embodiments may be practiced otherwise than as described. The description is not intended to limit the invention. [0077] The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the present invention as described without departing from the scope of the claims set out below.

[0078] It is to be appreciated that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments as contemplated by the inventor(s), and thus, are not intended to limit the present invention and the appended claims in any way.

[0079] The embodiments have described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed.

[0080] The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance.

[0081] The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A lithographic apparatus comprising:

a stationary frame having a first electrical conductor;

a support structure configured to support an object, movably coupled to the frame, and having a second electrical conductor; and

a conductive fluid configured to electrically couple the first electrical conductor to the second electrical conductor.

2. The lithographic apparatus of claim 1, wherein the frame defines a cavity that contains the conductive fluid.

3. The lithographic apparatus of claim 2, wherein:

the support structure is configured to move a first distance along a first direction; and the cavity has a dimension in the first direction equal to or greater than the first distance.

4. The lithographic apparatus of claim 2, wherein:

the support structure is configured to move a second distance along a second direction different than the first direction; and

the cavity has a dimension in the second direction equal to or greater than the second distance.

5. The lithographic apparatus of claim 2, wherein the cavity overlaps the support structure in a vertical direction.

6. The lithographic apparatus of claim 2, wherein the lithographic apparatus is configured to generate a gas flow that retains the conductive fluid within the cavity.

7. The lithographic apparatus of claim 2, wherein the lithographic apparatus is configured to generate a magnetic field that retains the conductive fluid within the cavity.

8. The lithographic apparatus of claim 1, wherein the second electrical conductor comprises a first portion submerged in the conductive fluid.

9. The lithographic apparatus of claim 1, further comprising an electrical component electrically coupled to the second electrical conductor and coupled to the support structure such that the electrical component moves with the support structure.

10. The lithographic apparatus of claim 9, wherein the electrical component comprises a sensor configured to transmit or receive a signal transmitted via the conductive fluid.

11. The lithographic apparatus of claim 9, wherein the electrical component comprises a positioner configured to move the support structure.

12. The lithographic apparatus of claim 1, further comprising an electrical component electrically coupled to the first electrical conductor.

13. The lithographic apparatus of claim 12, wherein the electrical component comprises a data processing apparatus configured to control a process of the lithographic apparatus.

14. The lithographic apparatus of claim 1, wherein the conductive fluid comprises mercury.

15. The lithographic apparatus of claim 1, wherein the conductive fluid comprises gallium.

16. The lithographic apparatus of claim 1, wherein the conductive fluid comprises a solvent and a electrolyte solute.

17. The lithographic apparatus of claim 16, wherein the solvent comprises water and the electrolyte solute comprises a salt.

18. The lithographic apparatus of claim 17, wherein the salt comprises sodium chloride.

19. The lithographic apparatus of claim 1, wherein the support structure comprises a sub table configured to support a substrate.

20. The lithographic apparatus of claim 1, wherein the support structure comprises a mask configured to support a patterning device.