WO2025153282A1

WO2025153282A1 - Directly actuated patterning device for a lithography apparatus

Info

Publication number: WO2025153282A1
Application number: PCT/EP2024/086755
Authority: WO
Inventors: Matthew Stephen Beaton MOLITERNO; Enrico Zordan
Original assignee: ASML Netherlands BV
Current assignee: ASML Netherlands BV
Priority date: 2024-01-16
Filing date: 2024-12-17
Publication date: 2025-07-24
Anticipated expiration: 2026-07-16

Abstract

Existing lithography apparatuses use a reticle clamp to hold a reticle, and a chuck having actuators and position sensors, for a reticle stage. This requires substantial mass and infrastructure on reticle stage chucks. Advantageously, new reticle motion control systems and methods for a lithography apparatus are described. In contrast to existing lithography apparatuses, the new systems and methods utilize magnetically actuatable targets configured to be coupled to a reticle. Electromagnetic actuators are configured to apply magnetic forces to the magnetically actuatable targets for suspending the patterning device in space in a lithography apparatus, and actuating the magnetically actuatable targets to facilitate contactless precision movements of the reticle for semiconductor lithography.

Description

DIRECTLY ACTUATED PATTERNING DEVICE FOR A LITHOGRAPHY APPARATUS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63/621,309 which was filed on 16 January 2024 and which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

[0002] This description relates generally to a directly actuated patterning device for a lithography apparatus.

BACKGROUND

[0003] A lithography (e.g., projection) apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device (e.g., a mask) may contain or provide a pattern corresponding to an individual layer of the IC (“design layout”), and this pattern can be transferred onto a target portion (e.g. comprising one or more dies) on a substrate (e.g., silicon wafer) that has been coated with a layer of radiation-sensitive material (“resist”), by methods such as irradiating the target portion through the pattern on the patterning device. In general, a single substrate contains a plurality of adjacent target portions to which the pattern is transferred successively by the lithographic projection apparatus, one target portion at a time. In one type of lithographic projection apparatus, the pattern on the entire patterning device is transferred onto one target portion in one operation. Such an apparatus is commonly referred to as a stepper. In an alternative apparatus, commonly referred to as a step-and-scan apparatus, a projection beam scans over the patterning device in a given reference direction (the “scanning” direction) while synchronously moving the substrate parallel or anti-parallel to this reference direction. Different portions of the pattern on the patterning device are transferred to one target portion progressively. A patterning device is generally held in a lithography apparatus using electrostatic or vacuum clamps.

SUMMARY

[0004] Existing lithography apparatuses use a reticle clamp to hold a patterning device such as a reticle, and a chuck having actuators and position sensors, for a reticle stage. This requires substantial mass and infrastructure on reticle stage chucks. Advantageously, new reticle motion control systems and methods for a lithography apparatus are described. In contrast to existing lithography apparatuses, the new systems and methods utilize magnetically actuatable targets configured to be coupled to a reticle and/or other patterning devices. Electromagnetic actuators are configured to apply magnetic forces to the magnetically actuatable targets for suspending the reticle in space in a lithography apparatus, and actuating the magnetically actuatable targets to facilitate contactless precision movements of the reticle for semiconductor lithography. [0005] According to an embodiment, there is provided a motion control system for a semiconductor lithography apparatus. The system comprises magnetically actuatable targets configured to be coupled to a patterning device. The system comprises electromagnetic actuators configured to apply magnetic forces to the magnetically actuatable targets for suspending the patterning device in space in the lithography apparatus, and actuating the magnetically actuatable targets to facilitate contactless precision movements of the patterning device for semiconductor lithography.

[0006] In some embodiments, the system comprises the patterning device. The patterning device may comprise a reticle having a pattern for an exposure of a semiconductor wafer, for example.

[0007] In some embodiments, the magnetically actuatable targets comprise one or more ferromagnetic materials, and/or one or more permanent magnets. In some embodiments, the one or more ferromagnetic materials comprise a magnetic steel. In some embodiments, the magnetically actuatable targets are directly bonded to the patterning device via adhesive.

[0008] In some embodiments, the system comprises a frame configured to be coupled to the patterning device and/or the electromagnetic actuators. The frame is configured to couple the magnetically actuatable targets to the patterning device. In some embodiments, the frame comprises one or more studs configured to be coupled to the patterning device configured to receive the one or more magnetically actuatable targets. In some embodiments, the one or more magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the patterning device to couple the one or more magnetically actuatable targets to the patterning device.

[0009] In some embodiments, actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces.

[0010] In some embodiments, the electromagnetic actuators are configured to suspend the patterning device in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets.

[0011] In some embodiments, the system comprises one or more sensors configured to generate one or more output signals conveying information related to a position of the patterning device in the space. In some embodiments, the one or more sensors comprise one or more interferometers. In some embodiments, the one or more interferometers comprise one or more laser interferometers.

[0012] In some embodiments, the system comprises a controller configured to receive the one or more output signals and control the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the patterning device in the space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate the contactless precision movements of the patterning device for semiconductor lithography based on the information related to the position of the patterning device in the one or more output signals.

[0013] In some embodiments, the system comprises one or more mirrors located adjacent to the patterning device and the space; the patterning device or a frame configured to be coupled to the patterning device comprises one or more wedges; and the one or more sensors are configured to generate the one or more output signals conveying the information related to the position of the patterning device in the space based on radiation reflected by the one or more wedges and the one or more mirrors.

[0014] In some embodiments, the one or more sensors comprise an x-laser interferometer configured to measure an x-position of the patterning device using radiation reflected from an x-wedge of the one or more wedges and an x-mirror of the one or more mirrors, a y-laser interferometer configured to measure a y-position of the patterning device using radiation reflected from a perpendicular surface of the patterning device, a second y-laser interferometer configured to measure a rotation of the patterning device about a z axis, and a z-laser interferometer configured to measure a z-position of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z-mirror of the one or more mirrors, and a second and third z-laser interferometer with z-wedges and z-mirrors configured to measure rotation about x and y axes.

[0015] In some embodiments, the one or more wedges are formed at corners of the patterning device by grinding corner surfaces of the patterning device. In some embodiments, the one or more wedges are formed at corners of the patterning device by coupling wedge components to corner surfaces of the patterning device using adhesive.

[0016] In some embodiments, the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus.

[0017] In some embodiments, the system comprises a gas flow system configured to flow cooling gas across a surface of the patterning device in the space between the patterning device and the electromagnetic actuators.

[0018] According to another embodiment, the system comprises the electromagnetic actuators (with the magnetically actuatable targets coupled to the patterning device).

[0019] According to another embodiment, a patterning device for a semiconductor lithography apparatus is provided. The patterning device comprises a body, and the magnetically actuatable targets coupled to the body (with electromagnetic actuators in the lithography apparatus configured to apply the magnetic forces to the magnetically actuatable targets to suspend the body in space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate contactless precision movements of the body for semiconductor lithography).

[0020] According to another embodiment, there is provided a motion control method. The method comprises one or more operations performed by the motion control system and/or the patterning device described above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts.

[0022] Fig. 1 schematically depicts a lithography apparatus, according to an embodiment.

[0023] Fig. 2 schematically depicts an embodiment of a lithographic cell or cluster, according to an embodiment.

[0024] Fig. 3A illustrates a portion of an extreme ultra violet (EUV) lithographic apparatus, according to an embodiment.

[0025] Fig. 3B illustrates a portion of a deep ultra violet (DUV) lithographic apparatus, according to an embodiment.

[0026] Fig. 4 illustrates a motion control system for a semiconductor lithography apparatus (such as the lithography apparatus shown in Figs. 1, 3 A, and/or 3B), according to an embodiment.

[0027] Fig. 5 illustrates a frame that may be coupled to a patterning device, electromagnetic actuators, and/or other components of the motion control system and/or the lithography apparatus, according to an embodiment.

[0028] Fig. 6 illustrates an embodiment of the motion control system that includes one or more sensors, according to an embodiment.

[0029] Fig. 7 illustrates an embodiment of the motion control system comprising a gas flow system configured to flow cooling gas across a surface of the patterning device in space between the patterning device and the electromagnetic actuators, according to an embodiment.

[0030] Fig. 8 illustrates how the motion control system may be configured to correct for sag of the patterning device, according to an embodiment.

[0031] Fig. 9 illustrates an embodiment of the motion control system comprising additional Z-direction magnetically actuatable targets and additional corresponding electromagnetic actuators near the Z- direction magnetically actuatable targets configured to hold a patterning device substantially flat, according to an embodiment.

[0032] Fig. 10 illustrates a motion control method, according to an embodiment.

[0033] Fig. 11 is a block diagram of an example computer system, according to an embodiment.

DETAILED DESCRIPTION

[0034] In general, a patterning device such as a mask or reticle may be a transparent block of material that is covered with a pattern defined by a different, opaque material. Various masks are fed into a lithographic apparatus and used to form layers of a semiconductor device. The pattern defined on a given mask or reticle corresponds to features produced in one or more layers of the semiconductor device. Often, a plurality of masks or reticles are automatically fed into a lithographic apparatus during manufacturing and used to form corresponding layers of a semiconductor device. A clamp (e.g., an electrostatic reticle clamp) in the lithographic apparatus is typically used to secure masks, reticles, and/or other patterning devices during processing. [0035] As described above, a clamp is often used with a chuck to hold a patterning device such as a reticle. Various additional components such as actuators and position sensors are also included with the clamp and the chuck in a reticle stage. This requires substantial mass and infrastructure (motors, electrical connections, structural members, couplers, etc.) on reticle stage chucks. Traditional reticle stages work by clamping a reticle to a chuck, and then performing servo control on that reticle chuck to accurately position the reticle in a light column in a lithographic apparatus.

[0036] New and improved reticle motion control systems and methods for a lithography apparatus are described. In contrast to existing lithography apparatuses, the new systems and methods utilize magnetically actuatable targets configured to be coupled to a reticle and/or other patterning devices. Electromagnetic actuators are configured to apply magnetic forces to the magnetically actuatable targets for suspending the reticle in space in a lithography apparatus, and actuating the magnetically actuatable targets to facilitate contactless precision movements of the reticle for semiconductor lithography. This eliminates the need for a typical clamp and chuck (and the associated mass and infrastructure) all together, provides faster and more precise control of a reticle (e.g., because movement does not depend on the accuracy of a motor, the dimensions of a track or other structure governing movement of a reticle, mass is reduced, etc.), reduces or eliminates the influence of outside objects that may have come into contact with a reticle in prior systems (e.g., the reticle no longer needs to contact burls or other similar surfaces that may include debris, or may not be perfectly flat, etc.), reduces heat effects from surrounding structures in a lithography apparatus, facilitates faster acceleration and/or other movement of a patterning device, and/or has other advantages. For example, the new and improved systems and methods eliminate the reticle chuck, and instead the lithography apparatus interacts with the reticle (patterning device) directly, with a touchless sensor system, touchless cooling, and touchless actuators. This substantially reduces the mass of the reticle stage, and as a result improves the acceleration (among other possible improvements) that can be achieved by the system.

[0037] Although specific reference may be made in this text to the manufacture of integrated circuits (ICs), it should be understood that the description herein has many other possible applications. For example, it may be employed in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid-crystal display panels, thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “reticle”, “wafer” or “die” in this text should be considered as interchangeable with the more general terms “mask”, “substrate” and “target portion”, respectively. In addition, any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device.”

[0038] As an introduction, prior to transferring a pattern from a patterning device such as a mask to a substrate, the substrate may undergo various procedures, such as priming, resist coating and a soft bake. After exposure, the substrate may be subjected to other procedures (“post-exposure procedures”), such as a post-exposure bake (PEB), development, a hard bake and measurement and/or other inspection of the transferred pattern. This array of procedures is used as a basis to make an individual layer of a device, e.g., an IC. The substrate may then undergo various processes such as etching, ion-implantation (doping), metallization, oxidation, chemical mechanical polishing, etc., all intended to finish an individual layer of the device. If several layers are required in the device, then the whole procedure, or a variant thereof, is repeated for each layer. Eventually, a device will be present in each target portion on the substrate. These devices are then separated from one another by a technique such as dicing or sawing, whence the individual devices can be mounted on a carrier, connected to pins, etc.

[0039] Manufacturing devices, such as semiconductor devices, typically involves processing a substrate (e.g., a semiconductor wafer) using a number of fabrication processes to form various features and multiple layers of the devices. Such layers and features are typically manufactured and processed using, e.g., deposition, lithography, etch, chemical mechanical polishing, ion implantation, and/or other processes. Multiple devices may be fabricated on a plurality of dies on a substrate and then separated into individual devices. This device manufacturing process may be considered a patterning process. A patterning process involves a patterning step, such as optical and/or nanoimprint lithography using a patterning device in a lithographic apparatus, to transfer a pattern on the patterning device to a substrate and typically, but optionally, involves one or more related pattern processing steps, such as resist development by a development apparatus, baking of the substrate using a bake tool, etching using the pattern using an etch apparatus, etc. One or more metrology processes are typically involved in the patterning process.

[0040] Lithography is a step in the manufacturing of device such as ICs, where patterns formed on substrates define functional elements of the devices, such as microprocessors, memory chips, etc. Similar lithographic techniques are also used in the formation of flat panel displays, micro-electro mechanical systems (MEMS) and other devices.

[0041] As semiconductor manufacturing processes continue to advance, the dimensions of functional elements have continually been reduced while the number of functional elements, such as transistors, per device has been steadily increasing over decades, following a trend commonly referred to as “Moore’s law”. At the current state of technology, layers of devices are manufactured using lithographic projection apparatuses that project a design layout onto a substrate using illumination from a deep-ultraviolet illumination source, creating individual functional elements having dimensions well below 100 nm, i.e. less than half the wavelength of the radiation from the illumination source (e.g., a 193 nm illumination source).

[0042] This process in which features with dimensions smaller than the classical resolution limit of a lithographic projection apparatus are printed, is commonly known as low-kl lithography, according to the resolution formula CD = klxk/NA, where I is the wavelength of radiation employed (currently in most cases 248nm or 193nm), NA is the numerical aperture of projection optics in the lithographic projection apparatus, CD is the “critical dimension’ -generally the smallest feature size printed-and kl is an empirical resolution factor. In general, the smaller kl the more difficult it becomes to reproduce a pattern on the substrate that resembles the shape and dimensions planned by a designer in order to achieve particular electrical functionality and performance. To overcome these difficulties, sophisticated fine-tuning steps are applied to the lithographic projection apparatus, the design layout, or the patterning device. These include, for example, but not limited to, optimization of NA and optical coherence settings, customized illumination schemes, use of phase shifting patterning devices, optical proximity correction (OPC, sometimes also referred to as “optical and process correction”) in the design layout, overlay measurement, or other methods generally defined as “resolution enhancement techniques” (RET).

[0043] Fig. 1 schematically depicts an embodiment of a lithographic apparatus LA that may be included in and/or associated with the present systems and/or methods. The apparatus comprises: an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., ultra violet (UV) radiation, deep ultra violet (DUV) radiation, or extreme ultra violet (EUV) radiation); a support structure (e.g. a mask table) MT constructed to support a patterning device (e.g. a mask or reticle) MA and connected to a first positioner PM configured to accurately position the patterning device in accordance with certain parameters; a substrate table (e.g. a wafer table) WT (e.g., WTa, WTb or both) configured to hold a substrate (e.g. a resist-coated wafer) W and coupled to a second positioner PW configured to accurately position the substrate in accordance with certain parameters; and a projection system (e.g. a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g. comprising one or more dies and often referred to as fields) of the substrate W. The projection system is supported on a reference frame (RF). As depicted, the apparatus is of a transmissive type (e.g. employing a transmissive mask). Alternatively, the apparatus may be of a reflective type (e.g. employing a programmable mirror array of a type as referred to above, or employing a reflective mask).

[0044] The illuminator IL receives a beam of radiation from a radiation source SO. The source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In such cases, the source is not considered to form part of the lithographic apparatus and the radiation beam is passed from the source SO to the illuminator IL with the aid of a beam delivery system BD comprising for example suitable directing mirrors and/or a beam expander. In other cases, the source may be an integral part of the apparatus, for example when the source is a mercury lamp. The source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system.

[0045] The illuminator IL may alter the intensity distribution of the beam. The illuminator may be arranged to limit the radial extent of the radiation beam such that the intensity distribution is non-zero within an annular region in a pupil plane of the illuminator IL. Additionally or alternatively, the illuminator IL may be operable to limit the distribution of the beam in the pupil plane such that the intensity distribution is non-zero in a plurality of equally spaced sectors in the pupil plane. The intensity distribution of the radiation beam in a pupil plane of the illuminator IL may be referred to as an illumination mode.

[0046] The illuminator IL may comprise adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam. Generally, at least the outer and/or inner radial extent (commonly referred to as o-outer and o-inner, respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. The illuminator IL may be operable to vary the angular distribution of the beam. For example, the illuminator may be operable to alter the number, and angular extent, of sectors in the pupil plane wherein the intensity distribution is non-zero. By adjusting the intensity distribution of the beam in the pupil plane of the illuminator, different illumination modes may be achieved. For example, by limiting the radial and angular extent of the intensity distribution in the pupil plane of the illuminator IL, the intensity distribution may have a multi-pole distribution such as, for example, a dipole, quadrupole or hexapole distribution. A desired illumination mode may be obtained, e.g., by inserting an optic which provides that illumination mode into the illuminator IL or using a spatial light modulator.

[0047] The illuminator IL may be operable to alter the polarization of the beam and may be operable to adjust the polarization using adjuster AD. The polarization state of the radiation beam across a pupil plane of the illuminator IL may be referred to as a polarization mode. The use of different polarization modes may allow greater contrast to be achieved in the image formed on the substrate W. The radiation beam may be unpolarized. Alternatively, the illuminator may be arranged to linearly polarize the radiation beam. The polarization direction of the radiation beam may vary across a pupil plane of the illuminator IL. The polarization direction of radiation may be different in different regions in the pupil plane of the illuminator IL. The polarization state of the radiation may be chosen in dependence on the illumination mode. For multi-pole illumination modes, the polarization of each pole of the radiation beam may be generally perpendicular to the position vector of that pole in the pupil plane of the illuminator IL. For example, for a dipole illumination mode, the radiation may be linearly polarized in a direction that is substantially perpendicular to a line that bisects the two opposing sectors of the dipole. The radiation beam may be polarized in one of two different orthogonal directions, which may be referred to as X-polarized and Y-polarized states. For a quadrupole illumination mode, the radiation in the sector of each pole may be linearly polarized in a direction that is substantially perpendicular to a line that bisects that sector. This polarization mode may be referred to as XY polarization. Similarly, for a hexapole illumination mode the radiation in the sector of each pole may be linearly polarized in a direction that is substantially perpendicular to a line that bisects that sector. This polarization mode may be referred to as TE polarization.

[0048] In addition, the illuminator IL generally comprises various other components, such as an integrator IN and a condenser CO. The illumination system 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 radiation. Thus, the illuminator provides a conditioned beam of radiation B, having a desired uniformity and intensity distribution in its cross section.

[0049] The support structure MT supports the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as for example whether or not the patterning device is held in a vacuum environment. The support structure may use magnetic, mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device. The support structure may be a frame or a table, for example, which may be fixed or movable as required. The support structure may ensure that the patterning device is at a desired position, for example with respect to the projection system.

[0050] The term “patterning device” used herein should be broadly interpreted as referring to any device that can be used to impart a pattern in a target portion of the substrate. In an embodiment, a patterning device is any device that can be used to impart a radiation beam with a pattern in its crosssection to create a pattern in a target portion of the substrate. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so called assist features. Generally, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in a target portion of the device, such as an integrated circuit.

[0051] A patterning device may be transmissive or reflective. Examples of patterning devices include reticles or masks, programmable mirror arrays, and programmable LCD panels. Reticles or 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 to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in a radiation beam, which is reflected by the mirror matrix.

[0052] The projection system PS has an optical transfer function which may be non-uniform, which can affect the pattern imaged on the substrate W. For unpolarized radiation such effects can be fairly well described by two scalar maps, which describe the transmission (apodization) and relative phase (aberration) of radiation exiting the projection system PS as a function of position in a pupil plane thereof. These scalar maps, which may be referred to as the transmission map and the relative phase map, may be expressed as a linear combination of a complete set of basis functions. A convenient set is the Zernike polynomials, which form a set of orthogonal polynomials defined on a unit circle. A determination of each scalar map may involve determining the coefficients in such an expansion. Since the Zernike polynomials are orthogonal on the unit circle, the Zernike coefficients may be determined by calculating the inner product of a measured scalar map with each Zernike polynomial in turn and dividing this by the square of the norm of that Zernike polynomial.

[0053] The transmission map and the relative phase map are field and system dependent. That is, in general, each projection system PS will have a different Zernike expansion for each field point (i.e. for each spatial location in its image plane). The relative phase of the projection system PS in its pupil plane may be determined by projecting radiation, for example from a point-like source in an object plane of the projection system PS (i.e. the plane of the patterning device MA), through the projection system PS and using a shearing interferometer to measure a wavefront (i.e. a locus of points with the same phase). A shearing interferometer is a common path interferometer and therefore, advantageously, no secondary reference beam is required to measure the wavefront. The shearing interferometer may comprise a diffraction grating, for example a two dimensional grid, in an image plane of the projection system (i.e. the substrate table WTa or WTb) and a detector arranged to detect an interference pattern in a plane that is conjugate to a pupil plane of the projection system PS. The interference pattern is related to the derivative of the phase of the radiation with respect to a coordinate in the pupil plane in the shearing direction. The detector may comprise an array of sensing elements such as, for example, charge coupled devices (CCDs).

[0054] The projection system PS of a lithography apparatus may not produce visible fringes and therefore the accuracy of the determination of the wavefront can be enhanced using phase stepping techniques such as, for example, moving the diffraction grating. Stepping may be performed in the plane of the diffraction grating and in a direction perpendicular to the scanning direction of the measurement. The stepping range may be one grating period, and at least three (uniformly distributed) phase steps may be used. Thus, for example, three scanning measurements may be performed in the y- direction, each scanning measurement being performed for a different position in the x-direction. This stepping of the diffraction grating effectively transforms phase variations into intensity variations, allowing phase information to be determined. The grating may be stepped in a direction perpendicular to the diffraction grating (z direction) to calibrate the detector.

[0055] The diffraction grating may be sequentially scanned in two perpendicular directions, which may coincide with axes of a co-ordinate system of the projection system PS (x and y) or may be at an angle such as 45 degrees to these axes. Scanning may be performed over an integer number of grating periods, for example one grating period. The scanning averages out phase variation in one direction, allowing phase variation in the other direction to be reconstructed. This allows the wavefront to be determined as a function of both directions.

[0056] The transmission (apodization) of the projection system PS in its pupil plane may be determined by projecting radiation, for example from a point-like source in an object plane of the projection system PS (i.e. the plane of the patterning device MA), through the projection system PS and measuring the intensity of radiation in a plane that is conjugate to a pupil plane of the projection system PS, using a detector. The same detector as is used to measure the wavefront to determine aberrations may be used. [0057] The projection system PS may comprise a plurality of optical (e.g., lens) elements and may further comprise an adjustment mechanism configured to adjust one or more of the optical elements to correct for aberrations (phase variations across the pupil plane throughout the field). To achieve this, the adjustment mechanism may be operable to manipulate one or more optical (e.g., lens) elements within the projection system PS in one or more different ways. The projection system may have a co- ordinate system wherein its optical axis extends in the z direction. The adjustment mechanism may be operable to do any combination of the following: displace one or more optical elements; tilt one or more optical elements; and/or deform one or more optical elements. Displacement of an optical element may be in any direction (x, y, z, or a combination thereof). Tilting of an optical element is typically out of a plane perpendicular to the optical axis, by rotating about an axis in the x and/or y directions although a rotation about the z axis may be used for a non-rotationally symmetric aspherical optical element. Deformation of an optical element may include a low frequency shape (e.g. astigmatic) and/or a high frequency shape (e.g. free form aspheres). Deformation of an optical element may be performed for example by using one or more actuators to exert force on one or more sides of the optical element and/or by using one or more heating elements to heat one or more selected regions of the optical element. In general, it may not be possible to adjust the projection system PS to correct for apodization (transmission variation across the pupil plane). The transmission map of a projection system PS may be used when designing a patterning device (e.g., mask) MA for the lithography apparatus LA. Using a computational lithography technique, the patterning device MA may be designed to at least partially correct for apodization.

[0058] The lithographic apparatus may be of a type having two (dual stage) or more tables (e.g., two or more substrate tables WTa, WTb, two or more patterning device tables, a substrate table WTa and a table WTb below the projection system without a substrate that is dedicated to, for example, facilitating measurement, and/or cleaning, etc.). In such “multiple stage” machines, the additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposure. For example, alignment measurements using an alignment sensor AS and/or level (height, tilt, etc.) measurements using a level sensor LS may be made.

[0059] The lithographic apparatus may also be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g. water, to fill a space between the projection system and the substrate. An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the patterning device and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems. The term “immersion” as used herein does not mean that a structure, such as a substrate, must be submerged in liquid, but rather only means that liquid is located between the projection system and the substrate during exposure.

[0060] In operation of the lithographic apparatus, a radiation beam is conditioned and provided by the illumination system IL. The radiation beam B is incident on the patterning device (e.g., mask) MA, which is held on the support structure (e.g., mask table) MT. Having traversed the patterning device MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF (e.g., an interferometric device, linear encoder, 2-D encoder, or capacitive sensor), the substrate table WT can be moved accurately, e.g. to position different target portions C in the path of the radiation beam B. Similarly, the first positioner PM and another position sensor (which is not explicitly depicted in Fig. 1) can be used to accurately position the patterning device MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library, or during a scan. In general, movement of the support structure MT may be realized with the aid of a long-stroke module (coarse positioning) or stage and a short-stroke module (fine positioning) or stage, which form part of the first positioner PM. Similarly, movement of the substrate table WT may be realized using a long-stroke module or stage and a short-stroke module or stage, which form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the support structure MT may be connected to a shortstroke actuator or stage only, or may be fixed. Patterning device MA and substrate W may be aligned using patterning device alignment marks Ml, M2 and substrate alignment marks Pl, P2. Although the substrate alignment marks as illustrated occupy dedicated target portions, they may be located in spaces between target portions (these are known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the patterning device MA, the patterning device alignment marks may be located between the dies.

[0061] The depicted apparatus may be used in a step mode and/or a scan mode. In step mode, the support structure MT and the substrate table WT are kept essentially stationary, while a pattern imparted to the radiation beam is projected onto a target portion C at one time (i.e. a single static exposure). The substrate table WT is then shifted in the X and/or Y direction so that a different target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure. In scan mode, the support structure MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam is projected onto a target portion C (i.e. a single dynamic exposure). The velocity and direction of the substrate table WT relative to the support structure MT may be determined by the (de-) magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, whereas the length of the scanning motion determines the height (in the scanning direction) of the target portion. In another mode, the support structure MT is kept essentially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam is projected onto a target portion C. In this mode, generally a pulsed radiation source is employed, and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device, such as a programmable mirror array of a type as referred to above. Combinations and/or variations on the abovedescribed modes of use or entirely different modes of use may also be employed.

[0062] A substrate 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) or a metrology or 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 includes multiple processed layers.

[0063] The terms “radiation” and “beam” used herein encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g. having a wavelength of 365, 248, 193, 157 or 126 nm) and extreme ultra-violet (EUV) radiation (e.g. having a wavelength in the range of 5-20 nm), as well as particle beams, such as ion beams or electron beams.

[0064] Various patterns on or provided by a patterning device may have different process windows, i.e., a space of processing variables under which a pattern will be produced within specification. Examples of pattern specifications that relate to potential systematic defects include checks for necking, line pull back, line thinning, critical dimension (CD), edge placement, overlapping, resist top loss, resist undercut and/or bridging. The process window of the patterns on a patterning device or an area thereof may be obtained by merging (e.g., overlapping) process windows of each individual pattern. The boundary of the process window of a group of patterns comprises boundaries of process windows of some of the individual patterns. In other words, these individual patterns limit the process window of the group of patterns.

[0065] As shown in Fig. 2, the lithographic apparatus LA may form part of a lithographic cell LC, also sometimes referred to a lithocell or cluster, which also includes apparatuses to perform pre- and postexposure processes on a substrate. Conventionally these include one or more spin coaters SC to deposit one or more resist layers, one or more developers to develop exposed resist, one or more chill plates CH and/or one or more bake plates BK. A substrate handler, or robot, RO picks up one or more substrates from input/output port I/Ol, I/O2, moves them between the different process apparatuses and delivers them to the loading bay LB of the lithographic apparatus. These apparatuses, which are often collectively referred to as the track, are under the control of a track control unit TCU which is itself controlled by the supervisory control system SCS, which also controls the lithographic apparatus via lithography control unit LACU. Thus, the different apparatuses can be operated to maximize throughput and processing efficiency.

[0066] In order that a substrate that is exposed by the lithographic apparatus is exposed correctly and consistently and/or in order to monitor a part of the patterning process (e.g., a device manufacturing process) that includes at least one pattern transfer step (e.g., an optical lithography step), it is desirable to inspect a substrate or other object to measure or determine one or more properties such as alignment, overlay (which can be, for example, between structures in overlying layers or between structures in a same layer that have been provided separately to the layer by, for example, a double patterning process), line thickness, critical dimension (CD), focus offset, a material property, etc. For example, contamination on reticle clamp membranes (e.g., as described herein) may adversely affect overlay because clamping a reticle over such contamination will distort the reticle. Accordingly, a manufacturing facility in which lithocell LC is located also typically includes a metrology system that measures some or all of the substrates W (Fig. 1) that have been processed in the lithocell or other objects in the lithocell. The metrology system may be part of the lithocell LC, for example it may be part of the lithographic apparatus LA (such as alignment sensor AS (Fig. 1)).

[0067] The one or more measured parameters may include, for example, alignment, overlay between successive layers formed in or on the patterned substrate, critical dimension (CD) (e.g., critical linewidth) of, for example, features formed in or on the patterned substrate, focus or focus error of an optical lithography step, dose or dose error of an optical lithography step, optical aberrations of an optical lithography step, etc. This measurement may be performed on a target of the product substrate itself and/or on a dedicated metrology target provided on the substrate. The measurement can be performed after-development of a resist but before etching, after-etching, after deposition, and/or at other times.

[0068] There are various techniques for making measurements of the structures formed in the patterning process, including the use of a scanning electron microscope, an image -based measurement tool and/or various specialized tools. As discussed above, a fast and non-invasive form of specialized metrology tool is one in which a beam of radiation is directed onto a target on the surface of the substrate and properties of the scattered (diffracted/reflected) beam are measured. By evaluating one or more properties of the radiation scattered by the substrate, one or more properties of the substrate can be determined. This may be termed diffraction-based metrology. One such application of this diffractionbased metrology is in the measurement of feature asymmetry within a target. This can be used as a measure of overlay, for example, but other applications are also known. For example, asymmetry can be measured by comparing opposite parts of the diffraction spectrum (for example, comparing the -1st and +l^st orders in the diffraction spectrum of a periodic grating). Another application of diffractionbased metrology is in the measurement of feature width (CD) within a target.

[0069] Thus, in a device fabrication process (e.g., a patterning process, a lithography process, etc.), a substrate or other objects may be subjected to various types of measurement during or after the process. The measurement may determine whether a particular substrate is defective, may establish adjustments to the process and apparatuses used in the process (e.g., aligning two layers on the substrate or aligning the patterning device to the substrate), may measure the performance of the process and the apparatuses, or may be for other purposes. Examples of measurement include optical imaging (e.g., optical microscope), non-imaging optical measurement (e.g., measurement based on diffraction such as the ASML YieldStar metrology tool, the ASML SMASH metrology system), mechanical measurement (e.g., profiling using a stylus, atomic force microscopy (AFM)), and/or non-optical imaging (e.g., scanning electron microscopy (SEM)).

[0070] Metrology results may be provided directly or indirectly to the supervisory control system SCS. If an error is detected, an adjustment may be made to exposure of a subsequent substrate (especially if the inspection can be done soon and fast enough that one or more other substrates of the batch are still to be exposed) and/or to subsequent exposure of the exposed substrate. Also, an already exposed substrate may be stripped and reworked to improve yield, or discarded, thereby avoiding performing further processing on a substrate known to be faulty. In a case where only some target portions of a substrate are faulty, further exposures may be performed only on those target portions which meet specifications.

[0071] Within a metrology system, a metrology apparatus is used to determine one or more properties of the substrate, and in particular, how one or more properties of different substrates vary, or different layers of the same substrate vary from layer to layer. As noted above, the metrology apparatus may be integrated into the lithographic apparatus LA or the lithocell LC or may be a stand-alone device.

[0072] To enable the metrology, one or more targets can be provided on the substrate. In an embodiment, the target is specially designed and may comprise a periodic structure. In an embodiment, the target is a part of a device pattern, e.g., a periodic structure of the device pattern. In an embodiment, the device pattern is a periodic structure of a memory device (e.g., a Bipolar Transistor (BPT), a Bit Line Contact (BLC), etc. structure).

[0073] In an embodiment, the target on a substrate may comprise one or more 1-D periodic structures (e.g., gratings), which are printed such that after development, the periodic structural features are formed of solid resist lines. In an embodiment, the target may comprise one or more 2-D periodic structures (e.g., gratings), which are printed such that after development, the one or more periodic structures are formed of solid resist pillars or vias in the resist. The bars, pillars, or vias may alternatively be etched into the substrate (e.g., into one or more layers on the substrate).

[0074] In an embodiment, one of the parameters of interest of a patterning process is overlay. Overlay can be measured using dark field scatterometry in which the zeroth order of diffraction (corresponding to a specular reflection) is blocked, and only higher orders processed. Diffraction-based overlay using dark-field detection of the diffraction orders enables overlay measurements on smaller targets. These targets can be smaller than the illumination spot and may be surrounded by device product structures on a substrate. In an embodiment, multiple targets can be measured in one radiation capture.

[0075] As lithography nodes keep shrinking, more and more complicated wafer designs may be implemented. Various tools and/or techniques may be used by designers to ensure complex designs are accurately transferred to physical wafers. These tools and techniques may include mask optimization, source mask optimization (SMO), OPC, design for control, and/or other tools and/or techniques.

[0076] The present systems, and/or methods may be used as stand-alone tools and/or techniques, and/or or used in conjunction with semiconductor manufacturing processes, to enhance the accurate transfer of complex designs to physical wafers.

[0077] As described above, an electrostatic clamp was often used in a lithography and/or metrology apparatus to clamp an object such as a patterning device (e.g., a reticle), a substrate such as a wafer, and/or other objects. Before clamping, the lithographic apparatus (for example) may move the object through typical movements and/or positions of a reticle to clamping position. By way of a non-limiting example, Fig. 3A and Fig. 3B illustrate example portions of a typical lithographic apparatus 300. Fig. 3A illustrates a portion of an extreme ultra violet (EUV) lithographic apparatus. Fig. 3B illustrates a portion of a deep ultra violet (DUV) lithographic apparatus.

[0078] Fig. 3A illustrates an example embodiment of an object 302 (e.g., in transit to and/or in proximity to a clamp 312 of lithographic apparatus 300) and various components of lithographic apparatus 300 including a tool handler (comprising a reticle handler turret gripper 306, a reticle handler robot gripper 307 (having associated components 308, etc. for gripping a reticle during transport)), and/or other components. Object 302 (e.g., a reticle in this example) is configured to be brought into apparatus 300 using a reticle pod. Object 302 is secured from the outside environment in an inner pod. Object 302 in the inner pod is placed on an EUV inner pod baseplate. Object 302 is moved from outside vacuum through the reticle handling system on to the turret of a tool handler (e.g., which may be formed by a portion of elements of the tool handler) of lithographic apparatus 300.

[0079] In some embodiments, lithographic apparatus 300 can be configured for deep ultraviolet (DUV) lithography with one or more adjustments from what is shown in Fig. 3A. Fig. 3B illustrates an example DUV apparatus with object 302 (e.g., in transit to and/or from a clamp 312 of lithographic apparatus 300 in these figures) and various components of lithographic apparatus 300 including a tool handler 306, 307, 308, reticle stage 310, reticle clamp(s) 312, and/or other components.

[0080] In some embodiments, the tool handler comprises a reticle handler turret gripper 306, a reticle handler robot gripper 307 (having associated components 308, etc. for gripping a reticle during transport), and/or other components. Reticle handler robot gripper 307 may, for example, move a reticle from a pod 320 (e.g., after a user places a reticle in pod 320). Reticle handler turret gripper 306 may, for example, move a reticle from reticle handler robot gripper 307 to reticle clamp(s) 312. Eithographic apparatus 300 may include various other mechanical components 322 (translation mechanisms, elevation mechanisms, rotational mechanisms, motors, power generation and transmission components, structural components, etc.) configured to facilitate movement and control of object 302 through lithographic apparatus 300.

[0081] Fig. 4 illustrates a motion control system 400 for a semiconductor lithography apparatus (such as the lithography apparatus shown in Figs. 1, 3A (e.g., EUV), and/or 3B (e.g., DUV)). System 400 comprises magnetically actuatable targets 402, a patterning device 404, electromagnetic actuators 406, a controller 450, and/or other components. Patterning device 404 may be transmissive or reflective, and/or may have other characteristics that facilitate the functionality described herein. Magnetically actuatable targets 402 are configured to be coupled to patterning device 404. Electromagnetic actuators 406 are configured to apply magnetic forces to magnetically actuatable targets 402 for suspending the patterning device in space 410 in the lithography apparatus, and actuating magnetically actuatable targets 402 to facilitate contactless precision movements of patterning device 404 for semiconductor lithography.

[0082] Because pattering device 404 is suspended in space (where there is essentially no friction and/or other disturbance forces), and because the collective mass of the components of system 400 is several times lower than the mass of a typical reticle chuck (among other advantageous features of system 400), patterning device 404 may be accelerated by electromagnetic actuators 406 far faster than in prior systems. This faster acceleration may decrease processing times, for example, and/or have other advantageous effects, as described herein.

[0083] Patterning device 404 may have a body 405 and/or other components configured for coupling magnetically actuatable targets 402. In some embodiments, as shown in Fig. 4, patterning device 404 body 405 has a rectangular shape. Patterning device 404 and/or body 405 may be formed as a single block of material shaped as a rectangular prism. In some embodiments, some or all of patterning device 404 including body 405 may be formed from an opaque, transparent, or nearly transparent material such as ultra-low thermal-expansion quartz (SFS), a transparent material such as glass, an opaque material such as metal, a polymer, a ceramic, and/or other materials. Fabrication of patterning device 404 can utilize any number of materials. Patterning device 404 and/or body 405 may comprise a reticle having a pattern for an exposure of a semiconductor wafer, for example (as described above).

[0084] In the example shown in Fig. 4, using an assigned coordinate system for reference purposes and ease of understanding, magnetically actuatable targets 402 may include one or more “X” targets 402 (two X targets are shown in this example), one or more “Y” targets 402 (two Y targets are shown in this example), one or more “Z” targets 402 (three Z targets are shown in this example), and/or other magnetically actuatable targets. Each of the X, Y, and/or Z targets 402 may facilitate movement of patterning device 404 in a corresponding direction (e.g., by electromagnetic actuators 406). Note that the “Z” targets 402 in this example may be on the top or bottom of body 405, though no corresponding electromagnetic actuators 406 are shown for these targets 402 (so that there is a clearer view of the other components shown in Fig. 4).

[0085] In some embodiments, magnetically actuatable targets 402 comprise one or more ferromagnetic materials, one or more permanent magnets, and/or other targets. The one or more ferromagnetic materials may comprise a magnetic steel, for example, and/or other materials. Use of a magnetic steel may reduce cost, for example, and/or have other advantages, though use of other materials is contemplated. In some embodiments, magnetically actuatable targets 402 have a rectangular shape, as shown in Fig. 4. However, magnetically actuatable targets may have a square shape, a round shape, a triangular shape, and/or other shapes; may have thickness; may form some or all of a sphere; and/or have other characteristics. In general, magnetically actuatable targets 402 may be formed from any material and in any shape that allows them to function as described herein.

[0086] In some embodiments, magnetically actuatable targets 402 are directly bonded to patterning device 404 (to body 405). Direct bonding may comprise coupling a target 402 to patterning device 404 body 405 without any other intervening structures, so that a bonded target 402 touches a surface of patterning device 404 body 405. The direct bonding may be via adhesive, via a chemical bond, via an optical bond, and/or using other bonding techniques. In some embodiments, each magnetically actuatable target 402 may be individually bonded to body 405 to minimize thermal expansion effects, for example, and/or for other reasons.

[0087] In some embodiments, as shown in Fig. 5, a frame 500 may be coupled to patterning device 404 (Fig. 4), electromagnetic actuators 406 (Fig. 4), and/or other components of motion control system 400 and/or a lithography apparatus (e.g., as shown in Fig. 1, 3A, and/or 3B). Frame 500 may be configured to couple magnetically actuatable targets 402 (Fig. 4) to patterning device 404. For example, the frame may comprise one or more studs 502 (representative examples of studs 502 are also shown in Fig. 4) and/or other fixtures 503 configured to be coupled to patterning device 404. The one or more studs 502 and/or other components may be configured to receive one or more magnetically actuatable targets 402. In this example, a given stud 502 may be coupled to body 405 (Fig. 4) of patterning device 404 at one end via adhesive, and configured to be press fit (or fit in some other way) into a corresponding receptacle on a magnetically actuatable target 402. In some embodiments, one or more magnetically actuatable targets 402 are coupled to frame 500, and frame 500 is configured to removably receive patterning device 404 to couple the one or more magnetically actuatable targets 402 to patterning device 404. In one embodiment, studs 502 are bonded to the patterning device, and fixtures 503 are attached to a frame 500. The actuatable targets 402 are bonded or fastened to the frame 500. The studs and fixtures can be repeatedly attached and detached using a tool which releases the clips on fixtures 503, so that the patterning device and frame system can be manufactured and utilized separately, for example. [0088] Returning to Fig. 4, electromagnetic actuators 406 are configured to apply magnetic forces to magnetically actuatable targets 402. The magnetic forces (between electromagnetic actuators 406 and magnetically actuatable targets 402) may be used for suspending patterning device 404 in space 410 in the lithography apparatus (as described above). The magnetic forces may be used for actuating magnetically actuatable targets 402 to facilitate contactless precision movements of patterning device 404 for semiconductor lithography. Actuating magnetically actuatable targets 402 comprises magnetically attracting or repelling magnetically actuatable targets 402 toward or away from electromagnetic actuators 406 with magnetic forces (though repelling may actually be an attraction from an oppositely located electromagnetic actuator), and/or other actions.

[0089] In some embodiments, electromagnetic actuators 406 comprise reluctance actuators and/or other actuators. Electromagnetic actuators may be located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus, and/or in other locations. Using magnetic reluctance or resistance, a reluctance actuator causes non-permanent magnetic poles on a ferromagnetic rotor, which generates torque. In a reluctance actuator, one or more non-permanent magnetic poles are excited on a ferromagnetic core facing one or more ferromagnetic targets across a gap. A closed magnetic circuit with a material and geometry dependent magnetic reluctance or resistance is formed. The resulting attractive force between the ferromagnetic parts across the gap(s) between them is due to the system seeking to minimizes the magnetic reluctance or resistance of the magnetic circuit.

[0090] Controller 450 is configured to coordinate the operation of the other components of system 400 (e.g., including electromagnetic actuators 406 described above, one or more sensors 600 shown in Fig. 6 and described below, the gas flow system 700 shown in Fig. 7, etc.) to provide the functionality described herein. For example, controller 450 may control electromagnetic actuators 406 to cause patterning device 404 to move as required for a lithography operation.

[0091] Controller 450 may bidirectionally communicate with each of the components of system 400, or direct the components to communicate with one another. Communication may be via wires; wirelessly via a local network, the internet, and/or some other network; by transmitting data between separate applications or processes on one computing device; or by passing values to and from functions, modules, or objects within an application or process, e.g., by reference or by value. Controller 450 may be formed by one or more processors, for example, configured by machine readable instructions. Controller 450 may be configured to direct the operation of one or more components of system 400 by software; hardware; firmware; some combination of software, hardware, or firmware; or other mechanisms for configuring processing capabilities. In some embodiments, controller 450 may be a controller of a lithography apparatus (e.g., as shown in Fig. 1, 3A, and/or 3B). For example, controller 450 may be associated with control software running on lithographic apparatus LA (Fig. 1) and/or apparatus 300 (Fig. 3A and/or 3B). Controller 450 may facilitate receiving entry and/or selection of control commands from a user via a user interface. In some embodiments, controller 450 may determine control commands automatically. These control commands may be determined in real time or near real time during a lithography operation, for example. In some embodiments, the control commands comprise adjustments to a scan movement profile, for example, forces provided by the motion control system 400, and/or other control commands.

[0092] Fig. 6 illustrates an embodiment of system 400 that includes one or more sensors 600, one or more mirrors 602, one or more wedges 604, and/or other components. One or more sensors 600 are configured to generate one or more output signals conveying information related to a position of patterning device 404 in space (e.g., space 410 shown in Fig. 4). One or more sensors 600 may comprise one or more interferometers, such as laser interferometers, for example, and/or other sensors. Note that in this embodiment, even though not specifically illustrated in Fig. 6, a frame (e.g., a measurement system frame) and/or other mechanical components may be used to position one or more of the described components relative to each other, relative to patterning device 404, and/or relative to other components of system 400.

[0093] In some embodiments, one or more mirrors 602 may be located adjacent to patterning device 404 and the space (i.e., where patterning device 404 is suspended in the lithography apparatus). The mirrors may be constructed of a low expansion material with high stability such as Zerodur, ULE, or Inconel, or similar metal or ceramic material. The surfaces of the mirrors are polished and/or coated to provide a highly reflective, flat surface which can return laser radiation to the sensors 600. The mirrors 602 and sensors 600 may be fixed to a frame and/or other mechanical components, which may be held stable using an isolation system and used as a reference for lithographic processes which communicate the position of the patterning device with respect to the projection system PS and the wafer table systems WTa and WTb, for example.

[0094] Patterning device 404 or a frame (e.g., frame 500 shown in Fig. 5) configured to be coupled to patterning device 404 may comprise one or more wedges 604. One or more wedges 604 may be formed at or near corners of patterning device 404 (or the frame), for example. One or more wedges 604 may be formed by grinding corner surfaces of patterning device 404, by coupling wedge components to corner surfaces of patterning device 404 (e.g., using adhesive and/or some other coupling mechanism), by coating one or more surfaces of patterning device 404, and/or by other methods. The ground or coupled surface of a wedge 604 may be oriented at an angle of approximately 45 degrees relative to a corresponding mirror 602 and/or sensor 600, for example. This angle may be adjusted based on the relative locations of the corresponding mirror 602 and/or sensor 600 such that system 400 functions as described. One or more wedges 604 (whether formed by grinding, coupled wedge components, and/or other methods) may be reflective and/or have other characteristics. For example, one or more wedges 604 may comprise a reflective coating such as a metallic (silver, gold, chromium, etc.) or multilayer Bragg mirror coating on an angled surface. One or more wedges may have a generally rectangular shape, a generally triangular shape, and/or any other shape that allows one or more wedges 604 to function as described herein.

[0095] One or more sensors 600 are configured to generate one or more output signals conveying the information related to the position of patterning device 404 in space based on radiation 610 (e.g., laser radiation in this example) reflected by one or more wedges 604 and one or more mirrors 602 (see the bi-directional arrows on radiation 610 in Fig. 6). For example, one or more sensors 600 may comprise an x-laser interferometer (XI) configured to measure an x-position of patterning device 404 using radiation 610 reflected from an x-wedge (and/or an xz wedge) of the one or more wedges 604 and an x-mirror (or an xz mirror) of the one or more mirrors 602. One or more sensors 600 may comprise two y-laser interferometers (e.g., Y1 and/or Y2 in this example) configured to measure two y-positions of patterning device 404 using radiation 610 reflected from a perpendicular surface 615 of patterning device 404. The two Y positions are used to determine the Y position as well as the rotation of the patterning device about the Z axis. One or more sensors 600 may comprise three z-laser interferometers (Zl, Z2, and/or Z3 in this example) configured to measure z-positions of patterning device using radiation reflected from a z-wedge (or an xz wedge) of the one or more wedges 604 and a z-mirror (or an xz mirror) of the one or more mirrors 602. The positions that the three Z sensors measure are used to determine the Z position of the patterning device as well as its rotation about the X axis and Y axis and/or other information.

[0096] Controller 450 is configured to communicate with one or more sensors 600 (wirelessly or via wires as described above) to receive the one or more output signals. Controller 450 is configured to control electromagnetic actuators 406 (Fig. 4) to apply the magnetic forces to magnetically actuatable targets 402 to suspend patterning device 404 in space in the lithography apparatus, and actuate magnetically actuatable targets 402 to facilitate the contactless precision movements of patterning device 404 for semiconductor lithography. This control is based on the information related to the position of patterning device 404 in the one or more output signals, and/or other information.

[0097] Fig. 7 illustrates (a side view of) an embodiment of system 400 comprising a gas flow system 700 and/or other components. Gas flow system 700 is configured to flow 702 cooling gas from an injection point 701, across a surface 704 of patterning device 404 in space 410 between patterning device 404 and electromagnetic actuators 406, to a removal point 703. The gas may comprise air, hydrogen (e.g., H2), oxygen, nitrogen (e.g., N2), helium, and/or other gasses. Flow 702 may be used to manage heating of patterning device 404. Flow 702 may be configured to conduct heat away from and/or otherwise cool patterning device 404. Patterning device 404 may heat up because of radiation associated with lithography, heat provided by nearby electromagnetic actuators 406, and/or for other reasons. Note that Fig. 7 also illustrates a portion of a long stroke or short stroke stage 710 of a lithography apparatus (e.g., as shown in Fig. 1, 3A, and/or 3B). Electromagnetic actuators 406 are coupled to stage 710.

[0098] In some embodiments, as shown in Fig. 8 (another side view), system 400 may be configured to correct for sag 800 of patterning device 404. A patterning device 404 such as a reticle may sag (e.g., sink or subside, or bow downward in the example shown in Fig. 8) under gravity, for example. This may be due to a weight, size, thickness, and/or other properties of patterning device 404. In some embodiments, patterning device 404 may be pre-fabricated with a certain material, size, thickness, weight, and/or other characteristics so that it is substantially flat when supported by electromagnetic actuators 406 as described above. In some embodiments, patterning device 404 may be (over) actuated to correct for gravity sag. For example, in Fig 9, additional electromagnetic actuators 406 near Z magnetically actuatable targets 402 may be configured to attract Z magnetically actuatable targets 402 with more force than they otherwise would, a constant force, and/or other forces configured to keep patterning device 404 substantially flat; with additional electromagnetic actuators 406 near additional Z magnetically actuatable targets 402; and/or with other configurations.

[0099] Fig. 9 illustrates (another side view of) an embodiment of system 400 comprising additional Z magnetically actuatable targets 402 and additional corresponding electromagnetic actuators 406 near Z magnetically actuatable targets 402. In this example, there are more Z magnetically actuatable targets 402 and additional corresponding electromagnetic actuators 406 near Z magnetically actuatable targets 402 than in a Y direction (or an X direction, though the X direction is not shown in Fig. 9). In some embodiments, patterning device 404 may be (over) actuated to correct for gravity sag by additional Z magnetically actuatable targets 402 and additional corresponding electromagnetic actuators 406 near Z magnetically actuatable targets 402. The six (in this example) electromagnetic actuators 406 near the six Z magnetically actuatable targets 402 may be configured to attract Z magnetically actuatable targets 402 with magnetic forces configured to keep patterning device 404 substantially flat, for example.

[00100] Fig. 10 illustrates a motion control method 1000 for a semiconductor lithography apparatus. Method 1000 may be performed with a motion control system such as system 400 shown in Fig. 4-9 and/or portions thereof, a patterning device such as patterning device such as patterning device 404 shown in Fig. 4-9, for example, and/or other systems as described herein. In some embodiments, one or more operations of method 1000 are performed or controlled by a controller such as controller 450 shown in Figs. 4 and 6 and described above, one or more processors, and/or a computing system, as described below (see Fig. 11), which may form and/or be included in the controller. The operations of method 1000 presented below are intended to be illustrative. In some embodiments, method 1000 may be accomplished with one or more additional operations not described, and/or without one or more of the operations discussed. Additionally, the order in which the operations of method 1000 are illustrated in Fig. 10 and described below is not intended to be limiting.

[00101] In some embodiments, one or more operations of method 1000 may be implemented in and/or controlled by one or more processing devices (e.g., a digital processor, an analog processor, a digital circuit designed to process information, an analog circuit designed to process information, a state machine, and/or other mechanisms for electronically processing information, as described with respect to Fig. 11 below). The one or more processing devices may include one or more devices executing some or all of the operations of method 1000 in response to instructions stored electronically on an electronic storage medium. The one or more processing devices may include one or more devices configured through hardware, firmware, and/or software to be specifically designed for execution of one or more of the operations of method 1000 (e.g., see discussion related to Fig. 11 below). For example, the one or more processing devices may run software configured to control movement of a reticle.

[00102] At an operation 1002, magnetically actuatable targets are coupled to a patterning device. In some embodiments, the magnetically actuatable targets comprise one or more ferromagnetic materials, one or more permanent magnets, and/or other targets. The one or more ferromagnetic materials may comprise a magnetic steel, for example, and/or other materials.

[00103] In some embodiments, the magnetically actuatable targets are directly bonded to the patterning device. Direct bonding may comprise coupling a target to the patterning device without any other intervening structures, so that a bonded target touches a surface of the patterning device. The direct bonding may be via adhesive, via a chemical bond, via an optical bond, and/or using other bonding techniques.

[00104] In some embodiments, operation 1002 comprises coupling a frame to the patterning device and/or electromagnetic actuators. The frame may be configured to couple the magnetically actuatable targets to the patterning device. For example, the frame may comprise one or more studs and/or other components configured to be coupled to the patterning device. The one or more studs and/or other components may be configured to receive the one or more magnetically actuatable targets. In some embodiments, the one or more magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the patterning device to couple the one or more magnetically actuatable targets to the patterning device. [00105] In some embodiments, operation 1002 may comprise simply providing the patterning device with the magnetically actuatable targets. The patterning device may have a body and/or other components configured for coupling the magnetically actuatable targets. The patterning device and/or the body may comprise a reticle having a pattern for an exposure of a semiconductor wafer, for example. In some embodiments, method 1000 need not include operation 1002 at all (e.g., so that method 1000 is performed only by a lithography apparatus or a motion control system that is part of the lithography apparatus). In some embodiments, the magnetically actuatable targets are similar to and/or the same as targets 402 shown in Fig. 4 (and other figures), and/or other components. In some embodiments, the patterning device is similar to and/or the same as patterning device 404 shown in Fig. 4 (and other figures), for example.

[00106] At an operation 1004, magnetic forces are applied to the magnetically actuatable targets with electromagnetic actuators for suspending the patterning device in space in the lithography apparatus. The electromagnetic actuators are configured to suspend the patterning device in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets. In some embodiments, the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus, and/or other actuators. Operation 1004 also includes actuating the magnetically actuatable targets to facilitate contactless precision movements of the patterning device for semiconductor lithography. Actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces. In some embodiments, the electromagnetic actuators are similar to and/or the same as electromagnetic actuators 406 shown in Fig. 4 (and other figures), and/or other components. The electromagnetic actuators may be controlled to actuate the magnetically actuatable targets by a controller that is similar to and/or the same as controller 450 shown in Fig. 4 (and other figures).

[00107] At operation 1006, one or more sensors generate one or more output signals conveying information related to a position of the patterning device in space. The one or more sensors may comprise one or more interferometers, such as laser interferometers, for example, and/or other sensors. In some embodiments, one or more mirrors may be located adjacent to the patterning device and the space (i.e., where the patterning device is suspended in the lithography apparatus). The patterning device or a frame configured to be coupled to the patterning device may comprise one or more wedges. The one or more wedges may be formed at or near corners of the patterning device. The one or more wedges may be formed by grinding corner surfaces of the patterning device, by coupling wedge components to corner surfaces of the patterning device (e.g., using adhesive and/or some other coupling mechanism), and/or by other methods. The one or more sensors are configured to generate the one or more output signals conveying the information related to the position of the patterning device in the space based on radiation reflected by the one or more wedges and the one or more mirrors. For example, the one or more sensors may comprise one or more x-laser interferometers configured to measure an x- position of the patterning device using radiation reflected from an x-wedge of the one or more wedges and an x-mirror of the one or more mirrors, one or more y-laser interferometers configured to measure a y-position and rz rotation of the patterning device using radiation reflected from a perpendicular surface of the patterning device, and z-laser interferometers configured to measure a z-position and rx and ry rotations of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z-mirror of the one or more mirrors (e.g., as shown in Fig. 6 and described above).

[00108] Operation 1006 also includes receiving, with a controller, the one or more output signals and controlling the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the patterning device in the space in the lithography apparatus, and actuating the magnetically actuatable targets to facilitate the contactless precision movements of the patterning device for semiconductor lithography based on the information related to the position of the patterning device in the one or more output signals. In some embodiments, the one or more sensors are similar to and/or the same as sensors 600 shown in Fig. 6. As described above, the controller may be similar to and/or the same as controller 450 shown in Fig. 4 (and Fig. 6). The frame may be similar to and/or the same as frame 500 shown in Fig. 5. The one or more mirrors may be similar to and/or the same as mirrors 602 shown in Fig. 6. The one or more wedges may be similar to and/or the same as wedges 604 shown in Fig. 6.

[00109] In some embodiments, method 1000 comprises flowing, with a gas flow system, cooling gas across a surface of the patterning device in the space between the patterning device and the electromagnetic actuators (e.g., as shown in Fig. 7 and described above).

[00110] Fig. 11 is a block diagram that illustrates a computer system 1100 that can assist in implementing the methods, flows, or the system(s) disclosed herein. Computer system 1100 may be included in and/or electronically coupled to lithography apparatus LA described above (Fig. 1, Fig. 3 A, 3B, etc.), motion control system 400 shown in Fig. 4-9, and/or other systems. For example, computer system 1100 may form some or all of controller 450 shown in Fig. 4 and Fig.6 and described above. Computer system 1100 includes a bus 1102 or other communication mechanism for communicating information, and a processor 1104 (or multiple processors 1104, 1105, etc.) coupled with bus 1102 for processing information. Computer system 1100 also includes a main memory 1106, such as a random access memory (RAM) or other dynamic storage device, coupled to bus 1102 for storing information and instructions to be executed by processor 1104. Main memory 1106 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 1104. Computer system 1100 includes a read only memory (ROM) 1108 or other static storage device coupled to bus 1102 for storing static information and instructions for processor 1104. A storage device 1110, such as a magnetic disk or optical disk, is provided and coupled to bus 1102 for storing information and instructions.

[00111] Computer system 1100 may be coupled via bus 1102 to a display 1112, such as a flat panel or touch panel display for displaying information to a computer user. An input device 1114, including alphanumeric and other keys and/or other input devices, is coupled to bus 1102 for communicating information and command selections to processor 1104. Another type of user input device is cursor control 1116, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor 1104 and for controlling cursor movement on display 1112. This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane. A touch panel (screen) display may also be used as an input device.

[00112] According to one embodiment, portions of one or more flows and/or methods described herein may be performed by computer system 1100 in response to processor 1104 executing one or more sequences of one or more instructions contained in main memory 1106. Such instructions may be read into main memory 1106 from another computer-readable medium, such as storage device 1110. Execution of the sequences of instructions contained in main memory 1106 causes processor 1104 to perform the flows and/or process steps described herein. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in main memory 1106. In an alternative embodiment, hard-wired circuitry may be used in place of or in combination with software instructions. Thus, the description herein is not limited to any specific combination of hardware circuitry and software.

[00113] The term “computer-readable medium” or “machine readable medium” as used herein refers to any medium that participates in providing instructions to processor 1104 for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as storage device 1110. Volatile media include dynamic memory, such as main memory 1106. Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise bus 1102. Transmission media can also take the form of acoustic or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD- ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read. [00114] Various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to processor 1104 for execution. For example, the instructions may initially be borne on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a network. The instructions received by main memory 1106 may optionally be stored on storage device 1110 either before or after execution by processor 1104.

[00115] Computer system 1100 may also include a communication interface 1118 coupled to bus 1102. Communication interface 118 provides a two-way data communication coupling to a network link 1120 that is connected to a local network 1122. For example, communication interface 1118 may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, communication interface 1118 may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, communication interface 1118 sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[00116] Network link 1120 typically provides data communication through one or more networks to other data devices. For example, network link 1120 may provide a connection through local network 1122 to a host computer 1124 or to data equipment operated by an Internet Service Provider (ISP) 1126. ISP 1126 in turn provides data communication services through the worldwide packet data communication network, now commonly referred to as the “Internet” 1128. Local network 1122 and Internet 1128 both use electrical, electromagnetic, or optical signals that carry digital data streams. The signals through the various networks and the signals on network link 1120 and through communication interface 1118, which carry the digital data to and from computer system 1100, are exemplary forms of carrier waves transporting the information.

[00117] Computer system 1100 can send messages and receive data, including program code, through the network(s), network link 1120, and communication interface 1118. In the Internet example, a server 1130 might transmit a requested code for an application program through Internet 1128, ISP 1126, local network 1122 and communication interface 1118. One such downloaded application may provide all or part of a method described herein, for example. The received code may be executed by processor 1104 as it is received, and/or stored in storage device 1110, or other non-volatile storage for later execution. In this manner, computer system 1100 may obtain application code in the form of a carrier wave.

[00118] Various embodiments of the present systems and methods are disclosed in the subsequent list of numbered clauses:

1. A motion control system for a semiconductor lithography apparatus, comprising: magnetically actuatable targets configured to be coupled to a patterning device; and electromagnetic actuators configured to apply magnetic forces to the magnetically actuatable targets for suspending the patterning device in space in the lithography apparatus, and actuating the magnetically actuatable targets to facilitate contactless precision movements of the patterning device for semiconductor lithography.

2. The system of clause 1, further comprising the patterning device, wherein the patterning device comprises a reticle having a pattern for an exposure of a semiconductor wafer.

3. The system of any of the previous clauses, wherein the magnetically actuatable targets comprise one or more ferromagnetic materials, and/or one or more permanent magnets.

4. The system of any of the previous clauses, wherein the one or more ferromagnetic materials comprise a magnetic steel.

5. The system of any of the previous clauses, wherein the magnetically actuatable targets are directly bonded to the patterning device via adhesive.

6. The system of any of the previous clauses, further comprising a frame configured to be coupled to the patterning device and/or the electromagnetic actuators, the frame configured to couple the magnetically actuatable targets to the patterning device.

7. The system of any of the previous clauses, wherein the frame comprises one or more studs configured to be coupled to the patterning device and configured to receive one or more of the magnetically actuatable targets.

8. The system of any of the previous clauses, wherein the magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the patterning device to couple the magnetically actuatable targets to the patterning device.

9. The system of any of the previous clauses, wherein actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces.

10. The system of any of the previous clauses, wherein the electromagnetic actuators are configured to suspend the patterning device in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets.

11. The system of any of the previous clauses, further comprising one or more sensors configured to generate one or more output signals conveying information related to a position of the patterning device in the space.

12. The system of any of the previous clauses, further comprising a controller configured to receive the one or more output signals and control the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the patterning device in the space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate the contactless precision movements of the patterning device for semiconductor lithography based on the information related to the position of the patterning device in the one or more output signals.

13. The system of any of the previous clauses, wherein the one or more sensors comprise one or more interferometers.

14. The system of any of the previous clauses, wherein the one or more interferometers comprise one or more laser interferometers.

15. The system of any of the previous clauses, wherein: the system further comprises one or more mirrors located adjacent to the patterning device and the space; the patterning device or a frame configured to be coupled to the patterning device comprises one or more wedges; and the one or more sensors are configured to generate the one or more output signals conveying the information related to the position of the patterning device in the space based on radiation reflected by the one or more wedges and the one or more mirrors. 16. The system of any of the previous clauses, wherein the one or more sensors comprise an x-laser interferometer configured to measure an x-position of the patterning device using radiation reflected from an x- wedge of the one or more wedges and an x-mirror of the one or more mirrors, a y-laser interferometer configured to measure a y-position of the patterning device using radiation reflected from a perpendicular surface of the patterning device, a second y-laser interferometer to measure the rotation of the patterning device about the z axis, and a z-laser interferometer configured to measure a z-position of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z- mirror of the one or more mirrors, and a second and third z-laser interferometer with z-wedges and z- mirrors to measure rotation about the x and Y axes.

17. The system of any of the previous clauses, wherein the one or more wedges are formed at corners of the patterning device by grinding corner surfaces of the patterning device.

18. The system of any of the previous clauses, wherein the one or more wedges are formed at corners of the patterning device by coupling wedge components to corner surfaces of the patterning device using adhesive.

19. The system of any of the previous clauses, wherein the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus.

20. The system of any of the previous clauses, further comprising a gas flow system configured to flow cooling gas across a surface of the patterning device in the space between the patterning device and the electromagnetic actuators.

21. A motion control system for a semiconductor lithography apparatus, comprising: electromagnetic actuators configured to apply magnetic forces to magnetically actuatable targets configured to be coupled to a patterning device to suspend the patterning device in space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate contactless precision movements of the patterning device for semiconductor lithography.

22. The system of any of the previous clauses, wherein the patterning device comprises a reticle having a pattern for an exposure of a semiconductor wafer.

23. The system of any of the previous clauses, wherein the magnetically actuatable targets comprise one or more ferromagnetic materials, and/or one or more permanent magnets.

24. The system of any of the previous clauses, wherein the one or more ferromagnetic materials comprise a magnetic steel.

25. The system of any of the previous clauses, wherein the magnetically actuatable targets are directly bonded to the patterning device via adhesive.

26. The system of any of the previous clauses, further comprising a frame configured to be coupled to the patterning device and/or the electromagnetic actuators, the frame configured to couple the magnetically actuatable targets to the patterning device.

27. The system of any of the previous clauses, wherein the frame comprises one or more studs coupled to the patterning device and configured to receive one or more of the magnetically actuatable targets.

28. The system of any of the previous clauses, wherein the magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the patterning device to couple the magnetically actuatable targets to the patterning device.

29. The system of any of the previous clauses, wherein actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces.

30. The system of any of the previous clauses, wherein the electromagnetic actuators are configured to suspend the patterning device in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets.

31. The system of any of the previous clauses, further comprising one or more sensors configured to generate one or more output signals conveying information related to a position of the patterning device in the space.

32. The system of any of the previous clauses, further comprising a controller configured to receive the one or more output signals and control the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the patterning device in the space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate the contactless precision movements of the patterning device for semiconductor lithography based on the information related to the position of the patterning device in the one or more output signals.

33. The system of any of the previous clauses, wherein the one or more sensors comprise one or more interferometers.

34. The system of any of the previous clauses, wherein the one or more interferometers comprise one or more laser interferometers.

35. The system of any of the previous clauses, wherein: the system further comprises one or more mirrors located adjacent to the patterning device and the space; the patterning device or a frame configured to be coupled to the patterning device comprises one or more wedges; and the one or more sensors are configured to generate the one or more output signals conveying the information related to the position of the patterning device in the space based on radiation reflected by the one or more wedges and the one or more mirrors.

36. The system of any of the previous clauses, wherein the one or more sensors comprise an x-laser interferometer configured to measure an x-position of the patterning device using radiation reflected from an x- wedge of the one or more wedges and an x-mirror of the one or more mirrors, a y-laser interferometer configured to measure a y-position of the patterning device using radiation reflected from a perpendicular surface of the patterning device, a second y-laser interferometer configured to measure a rotation of the patterning device about a z axis, and a z-laser interferometer configured to measure a z -position of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z-mirror of the one or more mirrors, and a second and third z-laser interferometer with z-wedges and z-mirrors configured to measure rotation about x and y axes.

37. The system of any of the previous clauses, wherein the one or more wedges are formed at corners of the patterning device by grinding corner surfaces of the patterning device.

38. The system of any of the previous clauses, wherein the one or more wedges are formed at corners of the patterning device by coupling wedge components to corner surfaces of the patterning device using adhesive.

39. The system of any of the previous clauses, wherein the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus.

40. The system of any of the previous clauses, further comprising a gas flow system configured to flow cooling gas across a surface of the patterning device in the space between the patterning device and the electromagnetic actuators.

41. A patterning device for a semiconductor lithography apparatus, comprising: a body; and magnetically actuatable targets coupled to the body; wherein electromagnetic actuators in the lithography apparatus are configured to apply magnetic forces to the magnetically actuatable targets to suspend the body in space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate contactless precision movements of the body for semiconductor lithography.

42. The device of clause 41, wherein the body comprises a reticle having a pattern for an exposure of a semiconductor wafer.

43. The device of any of the previous clauses, wherein the magnetically actuatable targets comprise one or more ferromagnetic materials, and/or one or more permanent magnets.

44. The device of any of the previous clauses, wherein the one or more ferromagnetic materials comprise a magnetic steel.

45. The device of any of the previous clauses, wherein the magnetically actuatable targets are directly bonded to the patterning device via adhesive.

46. The device of any of the previous clauses, further comprising a frame configured to be coupled to the body, the frame configured to couple the magnetically actuatable targets to the body.

47. The device of any of the previous clauses, wherein the frame comprises one or more studs coupled to the body and configured to receive one or more of the magnetically actuatable targets.

48. The device of any of the previous clauses, wherein the magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the body to couple the magnetically actuatable targets to the body.

49. The device of any of the previous clauses, wherein actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces.

50. The device of any of the previous clauses, wherein the electromagnetic actuators are configured to suspend the body in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets.

51. The device of any of the previous clauses, wherein one or more sensors are configured to generate one or more output signals conveying information related to a position of the patterning device in the space.

52. The device of any of the previous clauses, wherein a controller is configured to receive the one or more output signals and control the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the body in the space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate the contactless precision movements of the body for semiconductor lithography based on the information related to the position of the body in the one or more output signals.

53. The device of any of the previous clauses, wherein the one or more sensors comprise one or more laser interferometers.

54. The device of any of the previous clauses, wherein the body or a frame configured to be coupled to the body comprises one or more wedges.

55. The device of any of the previous clauses, wherein: one or more mirrors are located adjacent to the patterning device and the space; and one or more sensors are configured to generate one or more output signals conveying information related to a position of the body in the space based on radiation reflected by the one or more wedges and the one or more mirrors.

56. The device of any of the previous clauses, wherein the one or more sensors comprise an x-laser interferometer configured to measure an x-position of the patterning device using radiation reflected from an x- wedge of the one or more wedges and an x-mirror of the one or more mirrors, a y-laser interferometer configured to measure a y-position of the patterning device using radiation reflected from a perpendicular surface of the patterning device, a second y-laser interferometer configured to measure a rotation of the patterning device about a z axis, and a z-laser interferometer configured to measure a z -position of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z-mirror of the one or more mirrors, and a second and third z-laser interferometer with z-wedges and z-mirrors configured to measure rotation about x and y axes.

57. The device of any of the previous clauses, wherein the one or more wedges are formed at corners of the body by grinding corner surfaces of the patterning device.

58. The device of any of the previous clauses, wherein the one or more wedges are formed at corners of the body by coupling wedge components to corner surfaces of the body using adhesive.

59. The device of any of the previous clauses, wherein the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus.

60. The device of any of the previous clauses, wherein a gas flow system is configured to flow cooling gas across a surface of the body in the space between the patterning device and the electromagnetic actuators. 61. A motion control method for a semiconductor lithography apparatus, comprising: coupling magnetically actuatable targets to a patterning device; and applying, with electromagnetic actuators, magnetic forces to the magnetically actuatable targets for suspending the patterning device in space in the lithography apparatus, and actuating the magnetically actuatable targets to facilitate contactless precision movements of the patterning device for semiconductor lithography.

62. The method of clause 61, further comprising providing the patterning device, wherein the patterning device comprises a reticle having a pattern for an exposure of a semiconductor wafer.

63. The method of any of the previous clauses, wherein the magnetically actuatable targets comprise one or more ferromagnetic materials, and/or one or more permanent magnets.

64. The method of any of the previous clauses, wherein the one or more ferromagnetic materials comprise a magnetic steel.

65. The method of any of the previous clauses, wherein the magnetically actuatable targets are directly bonded to the patterning device via adhesive.

66. The method of any of the previous clauses, further comprising coupling a frame to the patterning device and/or the electromagnetic actuators, the frame configured to couple the magnetically actuatable targets to the patterning device.

67. The method of any of the previous clauses, wherein the frame comprises one or more studs configured to be coupled to the patterning device and configured to receive one or more of the magnetically actuatable targets.

68. The method of any of the previous clauses, wherein the magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the patterning device to couple the magnetically actuatable targets to the patterning device.

69. The method of any of the previous clauses, wherein actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces.

70. The method of any of the previous clauses, wherein the electromagnetic actuators are configured to suspend the patterning device in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets.

71. The method of any of the previous clauses, further comprising generating, with one or more sensors, one or more output signals conveying information related to a position of the patterning device in the space.

72. The method of any of the previous clauses, further comprising receiving, with a controller, the one or more output signals and controlling the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the patterning device in the space in the lithography apparatus, and actuating the magnetically actuatable targets to facilitate the contactless precision movements of the patterning device for semiconductor lithography based on the information related to the position of the patterning device in the one or more output signals. 73. The method of any of the previous clauses, wherein the one or more sensors comprise one or more interferometers.

74. The method of any of the previous clauses, wherein the one or more interferometers comprise one or more laser interferometers.

75. The method of any of the previous clauses, wherein: one or more mirrors are located adjacent to the patterning device and the space; the patterning device or a frame configured to be coupled to the patterning device comprises one or more wedges; and the one or more sensors are configured to generate the one or more output signals conveying the information related to the position of the patterning device in the space based on radiation reflected by the one or more wedges and the one or more mirrors.

76. The method of any of the previous clauses, wherein the one or more sensors comprise an x-laser interferometer configured to measure an x-position of the patterning device using radiation reflected from an x- wedge of the one or more wedges and an x-mirror of the one or more mirrors, a y-laser interferometer configured to measure a y-position of the patterning device using radiation reflected from a perpendicular surface of the patterning device, a second y-laser interferometer configured to measure a rotation of the patterning device about a z axis, and a z-laser interferometer configured to measure a z -position of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z-mirror of the one or more mirrors, and a second and third z-laser interferometer with z-wedges and z-mirrors configured to measure rotation about x and y axes.

77. The method of any of the previous clauses, wherein the one or more wedges are formed at corners of the patterning device by grinding corner surfaces of the patterning device.

78. The method of any of the previous clauses, wherein the one or more wedges are formed at corners of the patterning device by coupling wedge components to corner surfaces of the patterning device using adhesive.

79. The method of any of the previous clauses, wherein the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus.

80. The method of any of the previous clauses, further comprising flowing, with a gas flow system, cooling gas across a surface of the patterning device in the space between the patterning device and the electromagnetic actuators.

81. A motion control method for a semiconductor lithography apparatus, comprising: applying, with electromagnetic actuators, magnetic forces to magnetically actuatable targets configured to be coupled to a patterning device to suspend the patterning device in space in the lithography apparatus, and actuating the magnetically actuatable targets to facilitate contactless precision movements of the patterning device for semiconductor lithography.

82. The method of any of the previous clauses, wherein the patterning device comprises a reticle having a pattern for an exposure of a semiconductor wafer.

83. The method of any of the previous clauses, wherein the magnetically actuatable targets comprise one or more ferromagnetic materials, and/or one or more permanent magnets.

84. The method of any of the previous clauses, wherein the one or more ferromagnetic materials comprise a magnetic steel.

85. The method of any of the previous clauses, wherein the magnetically actuatable targets are directly bonded to the patterning device via adhesive.

86. The method of any of the previous clauses, further comprising providing a frame configured to be coupled to the patterning device and/or the electromagnetic actuators, the frame configured to couple the magnetically actuatable targets to the patterning device.

87. The method of any of the previous clauses, wherein the frame comprises one or more studs coupled to the patterning device and configured to receive one or more of the magnetically actuatable targets.

88. The method of any of the previous clauses, wherein the magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the patterning device to couple the magnetically actuatable targets to the patterning device.

89. The method of any of the previous clauses, wherein actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces.

90. The method of any of the previous clauses, wherein the electromagnetic actuators are configured to suspend the patterning device in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets.

91. The method of any of the previous clauses, further comprising generating, with one or more sensors, one or more output signals conveying information related to a position of the patterning device in the space.

92. The method of any of the previous clauses, further comprising receiving, with a controller, the one or more output signals and controlling the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the patterning device in the space in the lithography apparatus, and actuating the magnetically actuatable targets to facilitate the contactless precision movements of the patterning device for semiconductor lithography based on the information related to the position of the patterning device in the one or more output signals.

93. The method of any of the previous clauses, wherein the one or more sensors comprise one or more interferometers.

94. The method of any of the previous clauses, wherein the one or more interferometers comprise one or more laser interferometers.

95. The method of any of the previous clauses, wherein: one or more mirrors located adjacent to the patterning device and the space; the patterning device or a frame configured to be coupled to the patterning device comprises one or more wedges; and the one or more sensors are configured to generate the one or more output signals conveying the information related to the position of the patterning device in the space based on radiation reflected by the one or more wedges and the one or more mirrors. 96. The method of any of the previous clauses, wherein the one or more sensors comprise an x-laser interferometer configured to measure an x-position of the patterning device using radiation reflected from an x- wedge of the one or more wedges and an x-mirror of the one or more mirrors, a y-laser interferometer configured to measure a y-position of the patterning device using radiation reflected from a perpendicular surface of the patterning device, a second y-laser interferometer configured to measure a rotation of the patterning device about a z axis, and a z-laser interferometer configured to measure a z -position of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z-mirror of the one or more mirrors, and a second and third z-laser interferometer with z-wedges and z-mirrors configured to measure rotation about x and y axes.

97. The method of any of the previous clauses, wherein the one or more wedges are formed at corners of the patterning device by grinding corner surfaces of the patterning device.

98. The method of any of the previous clauses, wherein the one or more wedges are formed at corners of the patterning device by coupling wedge components to corner surfaces of the patterning device using adhesive.

99. The method of any of the previous clauses, wherein the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus.

100. The method of any of the previous clauses, further comprising flowing, with a gas flow system, cooling gas across a surface of the patterning device in the space between the patterning device and the electromagnetic actuators.

101. A patterning method for a semiconductor lithography apparatus, comprising: providing a body of a patterning device; and coupling magnetically actuatable targets to the body; wherein electromagnetic actuators in the lithography apparatus are configured to apply magnetic forces to the magnetically actuatable targets to suspend the body in space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate contactless precision movements of the body for semiconductor lithography.

102. The method of any of the previous clauses, wherein the body comprises a reticle having a pattern for an exposure of a semiconductor wafer.

103. The method of any of the previous clauses, wherein the magnetically actuatable targets comprise one or more ferromagnetic materials, and/or one or more permanent magnets.

104. The method of any of the previous clauses, wherein the one or more ferromagnetic materials comprise a magnetic steel.

105. The method of any of the previous clauses, wherein the magnetically actuatable targets are directly bonded to the body of the patterning device via adhesive.

106. The method of any of the previous clauses, further comprising providing a frame configured to be coupled to the body, the frame configured to couple the magnetically actuatable targets to the body.

107. The method of any of the previous clauses, wherein the frame comprises one or more studs coupled to the body and configured to receive one or more of the magnetically actuatable targets.

108. The method of any of the previous clauses, wherein the magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the body to couple the magnetically actuatable targets to the body.

109. The method of any of the previous clauses, wherein actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces.

110. The method of any of the previous clauses, wherein the electromagnetic actuators are configured to suspend the body in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets.

111. The method of any of the previous clauses, wherein one or more sensors are configured to generate one or more output signals conveying information related to a position of the patterning device in the space.

112. The method of any of the previous clauses, wherein a controller is configured to receive the one or more output signals and control the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the body in the space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate the contactless precision movements of the body for semiconductor lithography based on the information related to the position of the body in the one or more output signals.

113. The method of any of the previous clauses, wherein the one or more sensors comprise one or more laser interferometers.

114. The method of any of the previous clauses, wherein the body or a frame configured to be coupled to the body comprises one or more wedges.

115. The method of any of the previous clauses, wherein: one or more mirrors are located adjacent to the patterning device and the space; and one or more sensors are configured to generate one or more output signals conveying information related to a position of the body in the space based on radiation reflected by the one or more wedges and the one or more mirrors.

116. The method of any of the previous clauses, wherein the one or more sensors comprise an x-laser interferometer configured to measure an x-position of the patterning device using radiation reflected from an x- wedge of the one or more wedges and an x-mirror of the one or more mirrors, a y-laser interferometer configured to measure a y-position of the patterning device using radiation reflected from a perpendicular surface of the patterning device, a second y-laser interferometer configured to measure a rotation of the patterning device about a z axis, and a z-laser interferometer configured to measure a z -position of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z-mirror of the one or more mirrors, and a second and third z-laser interferometer with z-wedges and z-mirrors configured to measure rotation about x and y axes.

117. The method of any of the previous clauses, wherein the one or more wedges are formed at corners of the body by grinding corner surfaces of the patterning device.

118. The method of any of the previous clauses, wherein the one or more wedges are formed at corners of the body by coupling wedge components to corner surfaces of the body using adhesive.

119. The method of any of the previous clauses, wherein the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus.

120. The method of any of the previous clauses, wherein a gas flow system is configured to flow cooling gas across a surface of the body in the space between the patterning device and the electromagnetic actuators.

[00119] The concepts disclosed herein may be associated with any generic imaging system for imaging sub wavelength features, and may be especially useful with emerging imaging technologies capable of producing increasingly shorter wavelengths. Emerging technologies already in use include EUV (extreme ultra violet), DUV lithography that is capable of producing a 193nm wavelength with the use of an ArF laser, and even a 157nm wavelength with the use of a Fluorine laser. Moreover, EUV lithography is capable of producing wavelengths within a range of 20-5nm by using a synchrotron or by hitting a material (either solid or a plasma) with high energy electrons in order to produce photons within this range.

[00120] While the concepts disclosed herein may be used for wafer manufacturing on a substrate such as a silicon wafer, it shall be understood that the disclosed concepts may be used with any type of manufacturing system, e.g., those used for manufacturing on substrates other than silicon wafers. In addition, the combination and sub-combinations of disclosed elements may comprise separate embodiments. For example, a reticle, and the motion control system and/or an associated lithography apparatus may comprise separate embodiments, and/or these features may be used together in the same embodiment.

[00121] 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 as described without departing from the scope of the claims set out below.

Claims

2. The system of claim 1, further comprising the patterning device, wherein the patterning device comprises a reticle having a pattern for an exposure of a semiconductor wafer.

3. The system of claim 1, wherein: the magnetically actuatable targets comprise one or more ferromagnetic materials, and/or one or more permanent magnets; and the magnetically actuatable targets are directly bonded to the patterning device via adhesive.

4. The system of claim 1 , further comprising a frame configured to be coupled to the patterning device and/or the electromagnetic actuators, the frame configured to couple the magnetically actuatable targets to the patterning device, wherein: the frame comprises one or more studs configured to be coupled to the patterning device and configured to receive one or more of the magnetically actuatable targets; and the magnetically actuatable targets are coupled to the frame, and the frame is configured to removably receive the patterning device to couple the magnetically actuatable targets to the patterning device.

5. The system of claim 1, wherein actuating the magnetically actuatable targets comprises magnetically attracting or repelling the magnetically actuatable targets toward or away from the electromagnetic actuators with magnetic forces.

6. The system of claim 1 , wherein the electromagnetic actuators are configured to suspend the patterning device in space in the lithography apparatus using magnetic forces between the electromagnetic actuators and the magnetically actuatable targets.

7. The system of claim 1, further comprising: one or more sensors configured to generate one or more output signals conveying information related to a position of the patterning device in the space; and a controller configured to receive the one or more output signals and control the electromagnetic actuators to apply the magnetic forces to the magnetically actuatable targets to suspend the patterning device in the space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate the contactless precision movements of the patterning device for semiconductor lithography based on the information related to the position of the patterning device in the one or more output signals.

8. The system of claim 7, wherein: the one or more sensors comprise one or more interferometers comprising one or more laser interferometers; the system further comprises one or more mirrors located adjacent to the patterning device and the space; the patterning device or a frame configured to be coupled to the patterning device comprises one or more wedges; and the one or more sensors are configured to generate the one or more output signals conveying the information related to the position of the patterning device in the space based on radiation reflected by the one or more wedges and the one or more mirrors.

9. The system of claim 8, wherein the one or more sensors comprise an x-laser interferometer configured to measure an x-position of the patterning device using radiation reflected from an x- wedge of the one or more wedges and an x-mirror of the one or more mirrors, a y-laser interferometer configured to measure a y-position of the patterning device using radiation reflected from a perpendicular surface of the patterning device, a second y-laser interferometer configured to measure a rotation of the patterning device about a z axis, and a z-laser interferometer configured to measure a z -position of the patterning device using radiation reflected from a z-wedge of the one or more wedges and a z-mirror of the one or more mirrors, and a second and third z-laser interferometer with z-wedges and z-mirrors configured to measure rotation about x and y axes.

10. The system of claim 8, wherein the one or more wedges are formed at corners of the patterning device by grinding corner surfaces of the patterning device; or are formed at corners of the patterning device by coupling wedge components to corner surfaces of the patterning device using adhesive.

11. The system of claim 1 , wherein the electromagnetic actuators comprise reluctance actuators located on a short stroke stage and/or a long stroke stage of the semiconductor lithography apparatus.

12. The system of claim 1, further comprising a gas flow system configured to flow cooling gas across a surface of the patterning device in the space between the patterning device and the electromagnetic actuators.

13. A patterning device for a semiconductor lithography apparatus, comprising: a body; and magnetically actuatable targets coupled to the body; wherein electromagnetic actuators in the lithography apparatus are configured to apply magnetic forces to the magnetically actuatable targets to suspend the body in space in the lithography apparatus, and actuate the magnetically actuatable targets to facilitate contactless precision movements of the body for semiconductor lithography.

14. A motion control method for a semiconductor lithography apparatus, comprising: coupling magnetically actuatable targets to a patterning device; and applying, with electromagnetic actuators, magnetic forces to the magnetically actuatable targets for suspending the patterning device in space in the lithography apparatus, and actuating the magnetically actuatable targets to facilitate contactless precision movements of the patterning device for semiconductor lithography.